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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korean Society of Marine Engineering
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Journal DOI :
Korean Society of Marine Engineers
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Volume & Issues
Volume 38, Issue 10 - Dec 2014
Volume 38, Issue 9 - Nov 2014
Volume 38, Issue 8 - Oct 2014
Volume 38, Issue 7 - Sep 2014
Volume 38, Issue 6 - Jul 2014
Volume 38, Issue 5 - Jun 2014
Volume 38, Issue 4 - May 2014
Volume 38, Issue 3 - Mar 2014
Volume 38, Issue 2 - Feb 2014
Volume 38, Issue 1 - Jan 2014
Selecting the target year
A study on the welding conditions that affect thermal deformation and mechanical property of Al 5083 non-ferrous alloy for eco-environmental leisure ships
Moon, Byung Young ; Kim, Kyu Sun ; Lee, Ki Yeol ;
Journal of the Korean Society of Marine Engineering, volume 38, issue 10, 2014, Pages 1190~1199
DOI : 10.5916/jkosme.2014.38.10.1190
As a considerable, experimental approach, an autocarriage type of
welding machine and a MIG(metal inert gas) welding robot in the inert gas atmosphere were utilized in order to realize Al 5083 welding to hull and relevant components of green leisure ships. This study aims at investigating the effect of welding conditions(current, voltage, welding speed, etc.) on thermal deformation that occurs as welding operation and tensile characteristics after welding, by using Al 5083, nonferrous material, applied to manufacturing of eco-environmental leisure ships. With respect to welding condition to minimize the thermal deformation, 150 A and 16 V at the wire-feed rate of 6 mm/sec were acquired in the process of welding Al 5083 through an auto carriage type of
welding feeder. As to tensile characteristics of Al 5083 welding through a MIG welding robot, most of tensile specimens showed the fracture behavior on HAZ(heat affected zone) located at the area joined with weld metal, except for some cases. Especially, for the case of the Al specimen with 5 mm thickness, 284.62 MPa of tensile strength and 11.41 % of elongation were obtained as an actual allowable tensile stress-strain value. Mostly, after acquiring the optimum welding condition, the relevant welding data and technical requirements might be provided for actual welding operation site and welding procedure specification (WPS).
Heat transfer enhancement of nanofluids in a pulsating heat pipe for heat dissipation of LED lighting
Kim, Hyoung-Tak ; Bang, Kwang-Hyun ;
Journal of the Korean Society of Marine Engineering, volume 38, issue 10, 2014, Pages 1200~1205
DOI : 10.5916/jkosme.2014.38.10.1200
The effect of nanofluids on the heat transfer performance of a pulsating heat pipe has been experimentally investigated. Water-based diamond nanofluid and aluminium oxide (
) nanofluid were tested in the concentration range of 0.5-5%. The pulsating heat pipe was constructed using clear Pyrex tubes of 1.85 mm in inner diameter in order to visualize the pulsating action. The total number of turns was eight each for heated and cooled parts. The supply temperatures of heating water and cooling water were fixed at
respectively. The liquid charging ratio of the nanofluid was 50-70%. The test results showed that the case of 5% concentration of diamond nanofluid showed 18% increase in heat transfer rate compared to pure water. The case of 0.5% concentration of
nanofluid showed 24% increase in heat transfer rate compared to pure water. But the increase of
nanofluid concentration up to 3% did not show further enhancement in heat transfer. It is also observed that the deposited nanoparticles on the tube wall played a major role in enhanced evaporation of working fluid and this could be the reason for the enhancement of heat transfer by a nanofluid, not the enhanced thermal conductivity of the nanofluid.
The effect of cathodic protection system by means of zinc sacrificial anode on pier in Korea
Jeong, Jin-A ; Jin, Chung-Kuk ;
Journal of the Korean Society of Marine Engineering, volume 38, issue 10, 2014, Pages 1206~1211
DOI : 10.5916/jkosme.2014.38.10.1206
This study has been conducted to confirm the effect of sacrificial anode cathodic protection system for 90 days to protect corrosion on pier that is located in Korea. The cathodically protected structure was a slab and a pile cap. Before the construction of cathodic protection system, the macrography was carried out. As a result of the macrography, many corrosion traces were confirmed in this structure. The trace was mainly focused on joint and zones that concrete cover was eliminated. To apply the cathodic protection system, many onsite techniques have been adopted. In addition, to confirm the inner state of steel in concrete properly, a corrosion monitoring sensor (DMS-100, Conclinic Co. Ltd) has been applied. Test factors were corrosion & cathodic protection potential, 4 hour depolarization potential, resistivity and current density. After 90 days from the installation of cathodic protection system, it could confirm that proper corrosion protection effect was obtained by considering the result of tests.
Numerical analysis results of the cathodic protection for the underground steel pipe by anode installation method
Jeong, Jin-A ; Choo, Yeon-Gil ; Jin, Chung-Kuk ; Park, Kyeong-Wan ;
Journal of the Korean Society of Marine Engineering, volume 38, issue 10, 2014, Pages 1212~1216
DOI : 10.5916/jkosme.2014.38.10.1212
This study aims to find out the best anode location for buried pipelines. Numerical simulation program known as CATPRO (Elsyca, Belgium) were used for confirming the best location of anodes and the effects of impressed current cathodic protection system. Applied conditions for numerical simulation were similar to on-site environmental conditions for optimal application of cathodic protection system. Used criterion of cathodic protection was NACE SP 0169, which describes that minimum requirement for cathodic protection is -850mV vs. CSE. Various layouts for anodes' installation were applied, which were distance between anodes, anode installation location, and applied current. The areas where cathodic protection potential was lower than -850mV vs. CSE was limited up to 50m from anode installation locations. It was founded numerical analysis obtain cost-effective and efficient cathodic protection methods before design and application the impressed cathodic protection system to on-site environment.
Practical scaling method for underwater hydrodynamic model test of submarine
Moonesun, Mohammad ; Mikhailovich, Korol Yuri ; Tahvildarzade, Davood ; Javadi, Mehran ;
Journal of the Korean Society of Marine Engineering, volume 38, issue 10, 2014, Pages 1217~1224
DOI : 10.5916/jkosme.2014.38.10.1217
This paper provides a practical scaling method to solve an old problem for scaling and developing the speed and resistance of a model to full-scale submarine in fully submerged underwater test. In every experimental test in towing tank, water tunnel and wind tunnel, in the first step, the speed of a model should be scaled to the full-scale vessel (ship or submarine). In the second step, the obtained resistance of the model should be developed. For submarine, there are two modes of movement: surface and submerged mode. There is no matter in surface mode because, according to Froude's law, the ratio of speed of the model to the full-scale vessel is proportional to the square root of lengths (length of the model on the length of the vessel). This leads to a reasonable speed and is not so much for the model that is applicable in the laboratory. The main problem is in submerged mode (fully submerged) that there isn't surface wave effect and therefore, Froude's law couldn't be used. Reynold's similarity is actually impossible to implement because it leads to very high speeds of the model that is impossible in a laboratory and inside the water. According to Reynold's similarity, the ratio of speed of the model to the full-scale vessel is proportional to the ratio of the full-scale length to the model length that leads to a too high speed. This paper proves that there is no need for exact Reynold's similarity because after a special Reynolds, resistance coefficient remains constant. Therefore, there is not compulsion for high speeds of the model. For proving this finding, three groups of results are presented: two cases are based on CFD method, and one case is based on the model test in towing tank. All these three results are presented for three different shapes that can show; this finding is independent of the shapes and geometries. For CFD method, Flow Vision software has been used.
A study on the performance and internal flow of inline Francis turbine
Chen, Chengcheng ; Inagaki, Morihito ; Choi, Young-Do ;
Journal of the Korean Society of Marine Engineering, volume 38, issue 10, 2014, Pages 1225~1231
DOI : 10.5916/jkosme.2014.38.10.1225
This paper presents the performance characteristic of a Francis hydro turbine with an inline casing. This turbine is designed for city water supply system. Due to large changes in ground elevation with high points and low points, some systems may experience larger-than-normal required pressures in areas with low ground elevations. One way to dissipate these excess pressures is by the use of an inline-turbine instead of an inline-pressure reducing valve. For best applicability and minimal space consumption, the turbine is designed with an inline casing instead of the common spiral casing. As a characteristic of inline casing, the flow accesses to the runner in the radial direction, showing a low efficiency. The installation of vanes improves the internal flow and gives the positive encouragement to the output power. For the power transmission to the outside of the turbine casing from the runner axis, a belt passage is designed in the inline casing, as its influence, the region after the belt passage shows a relatively low output power. The clearance gap in the runner side space is considered, in which a small volume of flow is contracted into the clearance gap, forming the leakage flow. The leakage flow leads to a decrease in the efficiency.
Numerical simulation of bubble growth and liquid flow in a bubble jet micro actuator
Ko, Sang-Cheol ; Park, Nam-Seob ;
Journal of the Korean Society of Marine Engineering, volume 38, issue 10, 2014, Pages 1232~1236
DOI : 10.5916/jkosme.2014.38.10.1232
Numerical models of fluid dynamics inside the micro actuator chamber and nozzle are presented. The models include ink flow from reservoir, bubble formation and growth, ejection through the nozzle, and dynamics of refill process. Since high tapered nozzle is one of the very important parameters for overall actuator performance design. The effects of variations of nozzle thickness, diameter, and taper angles are simulated and some results are compared with the experimental results. It is found that the ink droplet ejection through the thinner and high tapered nozzle is more steady, fast, and robust.
LBM simulation on friction and mass flow analysis in a rough microchannel
Taher, M.A. ; Kim, H.D. ; Lee, Y.W. ;
Journal of the Korean Society of Marine Engineering, volume 38, issue 10, 2014, Pages 1237~1243
DOI : 10.5916/jkosme.2014.38.10.1237
The aim of the present paper is to analyze the friction and mass flow in a rough microchannel using Lattice Boltzmann Method (LBM). The LBM is a kinetic method based on the particle distribution function, so it can be fruitfully used to study the flow dependence on Knudsen number including slip velocity, pressure drop in rough microchannel. The surface roughness elements are taken to be considered as a series of circular shaped riblets throughout the channel with relative roughness height up to a maximum 10% of the channel height. The friction coefficients in terms of Poiseuille number (Pn), mass flow rate and the flow behaviors have been discussed in order to study the effect of surface roughness in the slip flow regime at Knudsen number (Kn), ranging from 0.01 to 0.10. It is seen that the friction factor and the flow behaviors in a rough microchannel strongly depend on the rarefaction effect and the relative roughness height. The friction factor in a rough microchannel is higher than that in smooth channel but the mass flow rate is lower than that of smooth channel. Moreover, it is seen that the friction factor increased with relative roughness height but decreased with increasing the Kundsen number (Kn) whereas the mass flow rate is decreased with increasing both of surface roughness height and Knudsen number.
Analysis on the performance and internal flow of a tubular type hydro turbine for vessel cooling system
Chen, Zhenmu ; Kim, Joo-Cheong ; Im, Myeong-Hwan ; Choi, Young-Do ;
Journal of the Korean Society of Marine Engineering, volume 38, issue 10, 2014, Pages 1244~1250
DOI : 10.5916/jkosme.2014.38.10.1244
The temperature of the main engine cabin of commercial vessel is very high. The material SS-316L undergoes creep damage at temperatures exceeding
. It is essential to maintain the highly stressed engine cabin below the creep regime. Hence, seawater is employed in this kind of maritime vehicles as cooling liquid. It obtains the thermal energy at the cooling pipe line after passing through main engine cooling system. To harness the energy in the seawater, a turbine can be installed to absorb the energy in the seawater before being released into the sea. In this study, a cooling pipe line is selected to apply the tubular type hydro turbine for transferring the energy. Numerical analysis for investigating the performance and the internal flow characteristics of the tubular turbine is conducted. The results show that the maximum efficiency of 85.8% is achieved although the efficiency drops rapidly at partial flow rate condition. The efficiency descends slowly at the condition of excess flow rate. There is a relatively wide operating range of flow rate of this turbine to keep high efficiency at the excess flow rate condition. For the internal flow of the turbine, there is uniform streamline on the suction and pressure sides of the blade at the design point. However, the secondary flow appears at the suction and pressure sidesat the excess flow rate.In addition, it appears only at pressure side at the partial flow rate condition.
Influence on centrifugal force control in a self-driven oil purifier
Jung, Ho-Yun ; Kwon, Sun-Beom ; Choi, Yoon-Hwan ; Lee, Yeon-Won ;
Journal of the Korean Society of Marine Engineering, volume 38, issue 10, 2014, Pages 1251~1256
DOI : 10.5916/jkosme.2014.38.10.1251
The use of lubrication oil is of many purposes and one among them is to drive the engine mounted on a ship. Hence the supply of clean lubrication oil is important. And an oil purifier is one of key components in marine diesel engines. At present, the element type full-flow oil filter has been widely used for cleaning the engine oil. The self-driven centrifugal oil purifier is a device which is used to remove the impurities in lubrication oil using a jet flow. The flow characteristics and the physical behaviors of particles in this self-driven oil purifier were investigated numerically and the filtration efficiencies were evaluated. For calculations, a Computational Fluid Dynamics method is used and the Shear Stress Transport turbulence model has been adopted. The Multi Frames of Reference method is used to consider the rotating effect of the flows. The influence of centrifugal forcehas been numerically investigatedto improve filtration efficiency of tiny particles. As a result of this research, it was found that the particle filtration efficiency using the only center axis rotating and outer wall rotating system are higher than that of the fully rotating system in the self-driven oil purifier.
Spray characteristics of misaligned impinging injectors
Subedi, Bimal ; Son, Min ; Kim, Woojin ; Choi, Jangsu ; Koo, Jaye ;
Journal of the Korean Society of Marine Engineering, volume 38, issue 10, 2014, Pages 1257~1262
DOI : 10.5916/jkosme.2014.38.10.1257
The variances of atomization characteristics with the misalignment of injectors defined as the fraction of skewness for various angles of impingement and pressure conditions were studied using the doublet impinging injectors with a like-on-like arrangement. Water was used as simulant and the spray characteristics along with the changes in the skewness were analyzed using the methods of spray image photography. Experiment was carried for the impinging nozzles of orifice diameter of 1.2 mm within Reynolds numbers ranging from
and the fraction of skewness considered for the experiment ranges from 0.0 to 0.9 at ambient temperature condition. Flat sheet with a distinct rim produced perpendicular to the plane of impinging jets goes ondisappear and sheet appears comparatively shorterwith the increase in fraction of skewness resulting the atomization of fluid droplet very close to impingement point with decrease in breakup length and increase in spray angle up to certain extent. The maximum allowable skewness was found as the result. The skewness up to the certain extent can be considered as the parameter to control the atomization characteristics of simulant inside the combustion chamberproviding the high economic performance of fuel and time.
Variations of swirl center according to evaluation position in steady flow bench of SI engine
Lee, Sukjong ; Sung, Jaeyong ; Ohm, In Yong ;
Journal of the Korean Society of Marine Engineering, volume 38, issue 10, 2014, Pages 1263~1268
DOI : 10.5916/jkosme.2014.38.10.1263
In this study, the variations of swirl center according to evaluating position have been investigated in a steady flow bench of SI engine. For the experiments, two engine heads with different intake valve angles (
) were tested in the flow bench by varying the evaluating position (1.75~6.0B) and valve lift (2~10 mm). Particle image velocimetry was used to measure the velocity field inside the engine cylinder. The swirl center position is found with a critical point theory and the intensity of turbulence is calculated from PIV velocity data. The results show that the center of swirl is located closer to the center of cylinder and turbulence intensity is lower, when the intake valve angle is the smaller. It is conventional to evaluate the swirl ratio at 1.75B position in the steady flow bench of SI engine. At this position, however, the distance of swirl center from the cylinder center scatters significantly for the variation of valve lift, and the turbulence intensity is much stronger regardless of the valve angle. Thus, to estimate the flow at the end of compression stroke in a real engine from the data in the steady flow experiments, the evaluation position should be moved further downstream more than 4.5B.
CFD analysis of geometric parameters that affect dean flow in a helical microchannel
Prasad, Bibin ; Kim, Jung Kyung ;
Journal of the Korean Society of Marine Engineering, volume 38, issue 10, 2014, Pages 1269~1274
DOI : 10.5916/jkosme.2014.38.10.1269
Due to the presence of Dean flow in curved ducts, helical channels have drawn attention recently because of the practical industrial applications. The manipulation of fluids through microfluidic devices is widely used in many scientific and industrial areas. In the present study, numerical simulations were performed on a helical microchannel to predict the impact of different design parameters that affect Dean flow. Important geometric parameters such as the channel cross section, pitch, radius of curvature, and number of turns were considered for the analysis. The study also incorporates the effect of varying flow rate on Dean flows. It was found from the simulation results that microchannel cross section and pitch have a significant impact on maintaining the Dean flow, compared to the radius of curvature, number of turns, and flow rate.
Evaluation on performances of a real-time microscopic and telescopic monitoring system for diagnoses of vibratory bodies
Jeon, Min Gyu ; Doh, Deog Hee ; Kim, Ue Kan ; Kim, Kang Ki ;
Journal of the Korean Society of Marine Engineering, volume 38, issue 10, 2014, Pages 1275~1280
DOI : 10.5916/jkosme.2014.38.10.1275
In this study, the performance of a real-time micro telescopic monitoring system is evaluated, in which an artificial neural network is adopted for the diagnoses of vibratory bodies, such as solid piping system or machinery. The structural vibration was measured by a non-contact remote sensing method, in which images of a high-speed high-definition camera were used. The structural vibration data that can be obtained by the PIV (particle image velocimetry) technique were used for training the neural network. The structures of the neural network are dynamically changed and their performances are evaluated for the constructed diagnosis system. Optimized structures of the neural network are proposed for real-time diagnosis for the piping system. It was experimentally verified that the performances of the neural network used for real-time monitoring are influenced by the types of the vibration data, such as minimum, maximum and average values of the vibration data. It concludes that the time-mean values are most appropriate for monitoring the piping system.
Improvement of trajectory tracking control performance by using ILC
Le, Dang-Khanh ; Nam, Taek-Kun ;
Journal of the Korean Society of Marine Engineering, volume 38, issue 10, 2014, Pages 1281~1286
DOI : 10.5916/jkosme.2014.38.10.1281
This paper presents an iterative learning control (ILC) approach for tracking problems with specified data points that are desired points at certain time instants. To design ILC systems for such problems, unlike traditional ILC approaches, an algorithm which updates not only the control signal but also the reference trajectory at each trial will be developed. The relationship between the reference trajectory and ILC control in tracking problems where there are specified data points through which the system should pass is investigated as the rate of convergence. In traditional ILC, the desired data is stored in a tracking profile file. Due to the huge size of the data file containing the target points, it is important to reduce the computational cost. Finally, simulation results of the presented technique are mentioned and compared to other related works to confirm the effectiveness of proposed scheme.
Hybrid control of a tricycle wheeled AGV for path following using advanced fuzzy-PID
Bui, Thanh-Luan ; Doan, Phuc-Thinh ; Van, Duong-Tu ; Kim, Hak-Kyeong ; Kim, Sang-Bong ;
Journal of the Korean Society of Marine Engineering, volume 38, issue 10, 2014, Pages 1287~1296
DOI : 10.5916/jkosme.2014.38.10.1287
This paper is about control of Automated Guided Vehicle for path following using fuzzy logic controller. The Automated Guided Vehicle is a tricycle wheeled mobile robot with three wheels, two fixed passive wheels and one steering driving wheel. First, kinematic and dynamic modeling for Automated Guided Vehicle is presented. Second, a controller that integrates two control loops, kinematic control loop and dynamic control loop, is designed for Automated Guided Vehicle to follow an unknown path. The kinematic control loop based on Fuzzy logic framework and the dynamic control loop based on two PID controllers are proposed. Simulation and experimental results are presented to show the effectiveness of the proposed controllers.
PSO based tuning of PID controller for coupled tank system
Lee, Yun-Hyung ; Ryu, Ki-Tak ; Hur, Jae-Jung ; So, Myung-Ok ;
Journal of the Korean Society of Marine Engineering, volume 38, issue 10, 2014, Pages 1297~1302
DOI : 10.5916/jkosme.2014.38.10.1297
This paper presents modern optimization methods for determining the optimal parameters of proportional-integral-derivative (PID) controller for coupled tank systems. The main objective is to obtain a fast and stable control system for coupled tank systems by tuning of the PID controller using the Particle Swarm Optimization algorithm. The result is compared in terms of system transient characteristics in time domain. The obtained results using the Particle Swarm Optimization algorithm are also compared to conventional PID tuning method like the Ziegler-Nichols tuning method, the Cohen-Coon method and IMC (Internal Model Control). The simulation results have been simulated by MATLAB and show that tuning the PID controller using the Particle Swarm Optimization (PSO) algorithm provides a fast and stable control system with low overshoot, fast rise time and settling time.
A study on the optimal tracking problems with predefined data by using iterative learning control
Le, Dang-Khanh ; Le, Dang-Phuong ; Nam, Taek-Kun ;
Journal of the Korean Society of Marine Engineering, volume 38, issue 10, 2014, Pages 1303~1309
DOI : 10.5916/jkosme.2014.38.10.1303
In this paper, we present an iterative learning control (ILC) framework for tracking problems with predefined data points that are desired points at certain time instants. To design ILC systems for such problems, a new ILC scheme is proposed to produce output curves that pass close to the desired points. Unlike traditional ILC approaches, an algorithm will be developed in which the control signals are generated by solving an optimal ILC problem with respect to the desired sampling points. In another word, it is a direct approach for the multiple points tracking ILC control problem where we do not need to divide the tracking problem into two steps separately as trajectory planning and ILC controller.The strength of the proposed formulation is the methodology to obtain a control signal through learning law only considering the given data points and dynamic system, instead of following the direction of tracking a prior identified trajectory. The key advantage of the proposed approach is to significantly reduce the computational cost. Finally, simulation results will be introduced to confirm the effectiveness of proposed scheme.
A sun tracking control system using two DOF active sensor array
Ha, Yun-Su ; Kim, Jong-Hwa ;
Journal of the Korean Society of Marine Engineering, volume 38, issue 10, 2014, Pages 1310~1317
DOI : 10.5916/jkosme.2014.38.10.1310
In our daily life, the need of energy increases day by day. However, the amount of natural resources on the earth is limited and thus gaining renewable energy as an energy resource is one of the important and urgent problems. Solar energy is one of the most popular available energy sources that can be converted into electricity by using solar panels. In order for solar panels to produce maximal output power, the incident angle of the sunlight needs to be persistently perpendicular to the solar panel. By the way, most of the solar panels are installed at fixed position and direction. Therefore, as the sun's position changes, it is impossible to produce maximal output power inevitably. To improve this problem, in this paper, a sun tracking system using two degree-of-freedom (DOF) active sensor array is proposed so that the solar panel may always direct sunlight perpendicularly. And also a series of software, such as a search mode and a holding mode, which can control the developed sun tracking system is developed. Several experiments using the implemented sun tracking system are executed and the effectiveness of the system is verified from the experimental results.
An attitude control of stabilizing system using indirect adaptive fuzzy control
Kim, Jae-Hoon ; Kim, Jong-Hwa ;
Journal of the Korean Society of Marine Engineering, volume 38, issue 10, 2014, Pages 1318~1326
DOI : 10.5916/jkosme.2014.38.10.1318
The purpose of a tracking control system is to track a moving target and to find the exact information of the target. If the platform of the tracking control system is equipped on a moving vehicle such as a ship, the tracking control system will treat even the additional platform motion. In order to avoid the complexity comprising the tracking control system, a process to treat the platform motion, named stabilizing system, must be separated from the tracking control system. In this paper, a method to comprise an attitude control system for the platform stabilization is proposed using an adaptive fuzzy control which is applicable to the system with structural and parametric uncertainty. The suggested adaptive fuzzy control algorithm is the 2nd/1st-type indirect adaptive fuzzy control algorithm using the advantages of 1st-type and 2nd-type indirect adaptive fuzzy control algorithm. Several experiments using the implemented stabilizing system are executed for verifying the effectiveness of the suggested method.
Design on illumination of structures for lighthouse in Korea
Han, Ju-Seop ; Yu, Yong-Su ; Kim, Jong-Uk ;
Journal of the Korean Society of Marine Engineering, volume 38, issue 10, 2014, Pages 1327~1332
DOI : 10.5916/jkosme.2014.38.10.1327
This paper presents information about the examples of the design on Illumination of Structures(LED Light Pipe for lighthouse) in Korea. We have applied illumination by flood-lighting or facade-lighting in place of the 57 lighthouses (offshore structures) and 4 beacons. The ways of illumination of structures are using direct illumination with LED, halogen lamps and metal halide lamps, and indirect illumination with LED non-neon lamps. The illumination of structures helps a observer to identify the Aids to Navigation and w aterway. The fabricated LED Light Pipe is a transparent acrylic round bar and easy to install. The Light Pipe is arranged in two rows of L ED (78ea). It can be connected in series. It has 4 colours(Red, Green, Yellow, White). We analyzed and the horizontal divergence angle of the LED light pipe is defined as the range with 50% of maximum luminous intensity. Also, we evaluated the conspicuity on the origin al lantern and LED Light pipe for lighthouse. The field experiment was conducted in 'Yeosuguhang lighthouse' in Yeosu-city (Korea). F rom the experimental results, it was confirmed that the fabricated LED Light Pipe is clearly distinguished.
An experimental study on the effects of internal tubular coatings on mitigating wax deposition in offshore oil production
Jung, Sun-Young ; Kang, Pan-Sang ; Lim, Jong-Se ;
Journal of the Korean Society of Marine Engineering, volume 38, issue 10, 2014, Pages 1333~1339
DOI : 10.5916/jkosme.2014.38.10.1333
As the demand for petroleum resources increases, and oilfields on lands and in shallow-sea become exhausted, the areas for oil production are expanding to the deep sea and therefore technologies for flow assurance are coming into the highlight. In low temperature environment such as the deep sea, wax is accumulated and prevents stable oil production. Therefore, the development of flow assurance technologies is required. Wax is precipitated in crystalline form when the oil temperature decreases below the wax appearance temperature; it then accumulates on the inner walls of pipelines causing blockages. In particular, in subsea pipelines, which have a large surface contact area with the surrounding seawater, wax deposition problems are frequent. The internal tubular coating can effectively reduce wax deposition without pausing oil production when the coating is appropriately designed. This study carried out wax deposition tests on a number of internal tubular coatings under single flow conditions. The results were analyzed for the effects that the physical properties of the coatings had on wax deposition.
Metaheuristics for reliable server assignment problems
Jang, Kil-Woong ; Kim, Jae-Hwan ;
Journal of the Korean Society of Marine Engineering, volume 38, issue 10, 2014, Pages 1340~1346
DOI : 10.5916/jkosme.2014.38.10.1340
Previous studies of reliable server assignment considered only to assign the same cost of server, that is, homogeneous servers. In this paper, we generally deal with reliable server assignment with different server costs, i.e., heterogeneous servers. We formulate this problem as a nonlinear integer programming mathematically. Our problem is defined as determining a deployment of heterogeneous servers to maximize a measure of service availability. We propose two metaheuristic algorithms (tabu search and particle swarm optimization) for solving the problem of reliable server assignment. From the computational results, we notice that our tabu search outstandingly outperforms particle swarm optimization for all test problems. In terms of solution quality and computing time, the proposed method is recommended as a promising metaheuristic for a kind of reliability optimization problems including reliable sever assignment and e-Navigation system.
Separation of dissolved gases from water using synthesized gases based on exhalation characteristics
Heo, Pil Woo ; Park, In Sub ;
Journal of the Korean Society of Marine Engineering, volume 38, issue 10, 2014, Pages 1347~1353
DOI : 10.5916/jkosme.2014.38.10.1347
It's possible for a human to breathe under water, if dissolved oxygen is effectively used. Fish can stay under water using the gill which extracts dissolved oxygen from water. Water includes small amounts of oxygen, so a human needs larger amounts of water to acquire oxygen enough for underwater breathing. The exhalation gas from a human is another method to get higher amounts of oxygen under water. It mainly composes of oxygen, nitrogen and carbon dioxide. So, if only carbon dioxide is decreased, the exhalation gas has good characteristics for breathing of a human under water. In this paper, composition of the exhalation gas from a human was analyzed using GC. Based on these results, the synthesized gas was prepared and mixed into water which was used for experimental devices to analyze separation characteristics of dissolved gases from water. Experimental devices included a water pump, a hollow fiber membrane module and a vacuum pump. The effects of pressure and water flow on separation characteristics of synthesized gas were investigated. The compositions of gases separated from water using synthesized gas were investigated using GC. These results expect to be applied to the development of underwater breathing technology for a human.
A study on market predictions of eco ship's engine and machinery
Lee, Kang Ki ; Doh, Deog Hee ; Kim, Ue Kan ; Moon, Hyun Seok ;
Journal of the Korean Society of Marine Engineering, volume 38, issue 10, 2014, Pages 1354~1359
DOI : 10.5916/jkosme.2014.38.10.1354
A survey is carried out for the future energy sources to be used for ship's propulsion and ship's machinery and operations. 44 global experts from Korea, America, Norway, Denmark, Japan and German who are currently working in the shipyard and offshore fields participated at the survey. Quantitative predications on the market shares of various energy sources, such as oil, LNG, fuel cell, wind energy, solar energy and nuclear energy are made. MPI (market prediction index) is considered as a quantitative index for easy comparison between future's energy sources used for ship's propulsion and operations. It is expected that the MPI of LNG becomes twofold in 2020 against 'before 2016'. It could be also said that hydrogen based fuel cell is expected to increase rapidly for the coming years unless a new alternative energy appears.