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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korean Society of Marine Engineering
Journal Basic Information
Journal DOI :
Korean Society of Marine Engineers
Editor in Chief :
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
Synchronization and identification of ship shaft power and speed for energy efficiency design index verification
Lee, Donchool ; Barro, Ronald Dela Cruz ; Nam, Jeonggil ;
Journal of the Korean Society of Marine Engineering, volume 38, issue 2, 2014, Pages 123~132
DOI : 10.5916/jkosme.2014.38.2.123
The maritime sector is advancing with dedicated endeavor to reduce greenhouse gas in addressing issues with regards to global warming. Since 01 January 2013, the International Maritime Organization (IMO) regulation mandatory requirement for Energy Efficiency Design Index (EEDI) has been in place and should be satisfied by newly-built ships of more than 400 gross tonnage and the Ship Energy Efficiency Management Plan (SEEMP) for all ships type. Therefore, compliance to this necessitates planning during the design stage whereas verification can be carried-out through an acceptable method during sea trial. The MEPC-approved 2013 guidance, ISO 15016 and ISO 19019 on EEDI serves the purpose for calculation and verification of attained EEDI value. Individual ships EEDI value should be lower than the required value set by these regulations. The key factors for EEDI verification are power and speed assessment and their synchronization. The shaft power can be measured by telemeter system using strain gage during sea trial. However, calibration of shaft power onboard condition is complicated. Hence, it relies only on proficient technology that operates within the permitted ISO allowance. On the other hand, the ship speed can be measured and calibrated by differential ground positioning system (DGPS). An actual test on a newly-built vessel was carried out to assess the correlation of power and speed. The Energy-efficiency Design Index or Operational Indicator Monitoring System (EDiMS) software developed by the Dynamics Laboratory-Mokpo Maritime University (DL-MMU) and Green Marine Equipment RIS Center (GMERC) of Mokpo Maritime University was utilized for this investigation. In addition, the software can continuously monitor air emission and is a useful tool for inventory and ship energy management plan. This paper introduces the synchronization and identification method between shaft power and ship speed for EEDI verification in accordance with the ISO guidance.
Microstructural behavior on weld fusion zone of Al-Ti and Ti-Al dissimilar lap welding using single-mode fiber laser
Lee, Su-Jin ; Katayama, Seiji ; Kim, Jong-Do ;
Journal of the Korean Society of Marine Engineering, volume 38, issue 2, 2014, Pages 133~139
DOI : 10.5916/jkosme.2014.38.2.133
Titanium (Ti) metal and its alloys are desirable materials for ship hulls and other ocean structures because of their high strength, corrosion-resistance and light weight properties. And light weight and corrosion-resistant aluminum (Al) is the ideal metal for shipbuilding. The joining of Ti and Al dissimilar metals is one of the effective methode to reduce weight of the structures. Ti and Al have great differences in materials properties, and intermetallic compounds such as
are easily formed at the contacting surface between Ti and Al. Thus, dissimilar welding and joining of Ti and Al are considered to be very difficult. However, it was clarified that ultra-high speed welding could suppress the formation of intermetallic compounds in the previous study. Results of tensile shear strength increases with an increase in the welding speed, and therefore extremely high welding speed (50 m/min) is good to dissimilar weldability for Ti and Al. In this study, therefore, full penetration dissimilar lap welding of Ti (upper) - Al (lower) and Al (upper) - Ti (lower) with single-mode fiber laser was tried at ultra-high welding speed, and the microstructure of the interface zones in the dissimilar Al and Ti weld beads was investigated.
Effects of stenotic severity on the flow structure in a circular channel under a pulsatile flow
Kim, Kyung-Won ; Cheema, Taqi-Ahmad ; Park, Cheol-Woo ;
Journal of the Korean Society of Marine Engineering, volume 38, issue 2, 2014, Pages 140~146
DOI : 10.5916/jkosme.2014.38.2.140
Stenosis is the drastic reduction in the cross-sectional area of blood vessel caused by accumulations of cholesterol. It affects the blood flow property and structure from the fluid dynamic point of view. To understand the flow phenomenon more clearly, a particle image velocimetry method is used and the fluid dynamic characteristics in a circular channel containing stenosis structure is investigated experimentally in this study. Different stenotic-structured models made of acrylic material are subjected to a pulsatile flow generated by an in-house designed pulsatile pump. The inner diameter of the tube inlet is 20 mm and the length of reduced area for stenosis ranges between 35mm and 40mm. It is circulated continuously through a circular channel by the pump system. Pressure is measured at four different sections during systolic and diastolic phase changes. The phase-averaged velocity field distribution shows a recirculation regime after the stenotic structure. The effects of the stenotic obstructions are found to be more severe when the aspect ratio is varied.
Separation characteristics of particles in a self-rotating type centrifugal oil purifier
Pyo, Young-Seok ; Jung, Ho-Yun ; Choi, Yoon-Hwan ; Doh, Deog-Hee ; Lee, Yeon-Won ;
Journal of the Korean Society of Marine Engineering, volume 38, issue 2, 2014, Pages 147~153
DOI : 10.5916/jkosme.2014.38.2.147
The centrifugal oil purifier is used in an engine for lubrication and to remove impurities. The momentum needed for the rotation of the cylindrical chamber is obtained by jet injections. An impure particle in the oil is separated by the centrifugal forces moving to the inner wall of the rotating cylindrical chamber body. The dust particles are eliminated when the particles are absorbed onto the surface of the inner wall of the chamber body. The flow characteristics and the physical behaviors of particles in this centrifugal oil purifier were investigated numerically and the filtration efficiencies was evaluated. For calculations, a commercial code is used and the SST (Shear Stress Transport) turbulence model has been adopted. The MFR (Multi Frames of Reference) method is introduced to consider the rotating effect of the flows. Under various variables, such as particle size, particle density and rotating speed, the filtration efficiencies are evaluated. It has been verified that the filtration efficiency is increased with the increments in the particle size, the particle density and the rotating speed of the cylindrical chamber.
Structural design and evaluation of a 3MW class wind turbine blade
Kim, Bum-Suk ;
Journal of the Korean Society of Marine Engineering, volume 38, issue 2, 2014, Pages 154~161
DOI : 10.5916/jkosme.2014.38.2.154
This research presents results of structural designs and evaluations for 3MW Wind Turbine Blade by FEM analysis. After the GFRP model was designed as a baseline model, failure check by Puck's failure criterion and buckling analysis were accomplished to verify safety of wind turbine blade in the critical design load case. Moreover, applicability of two kinds of carbon spar cap model, was studied by comparing total mass, price and tip deflection to the GFRP model. The results showed that the GFRP model had sufficient structural integrity in the critical design load case, and the carbon spar cap model could be a reasonable solution to reduce weights, tip deflections.
Merits of all-electric subsea production control system
Oh, Jin-Seok ; Kang, Se-Ra ;
Journal of the Korean Society of Marine Engineering, volume 38, issue 2, 2014, Pages 162~168
DOI : 10.5916/jkosme.2014.38.2.162
Recently, researches on all-electric subsea system have been in progress. This paper describes a subsea tree using a lot of electrical signal and subsea control system. The way of subsea control is classified as all-electric systems or electro hydraulic systems. One of that has more merits in terms of cost, weight, power consumption, etc. because it uses electric signal instead of hydraulic signal. This paper describes the difference of each system's power consumption and simulation. As the result, if each system applies the same number of sensors, actuators, etc. The power consumption of all-electric system's load is less than at least 400kWh/day compared to the electro hydraulic system load.
LED transceivers with beehive-shaped reflector for visible light communication
Sohn, Kyung-Rak ; Kim, Min-Soo ;
Journal of the Korean Society of Marine Engineering, volume 38, issue 2, 2014, Pages 169~174
DOI : 10.5916/jkosme.2014.38.2.169
This paper proposes a novel beehive-shaped reflector for application to light-emitting diode (LED) transceivers for illumination and bi-directional visible light communication (VLC). By using a diffuse propagation model extended to line-of-sight and direct signals, the distribution of illuminance and the path loss of the transceiver are investigated to evaluate the performance of the beehive-shaped reflector. To verify bi-directional communication, a VLC-based image capture system, comprising a complementary metal-oxide semiconductor (CMOS) image sensor and video processor unit, is demonstrated. Real-time images captured by the CMOS camera are successfully transmitted to the monitoring system via a free-space channel at a rate of 115.2 kbps.
A hand-off mechanism of mobile nodes in a location positioning system based on ZigBee tags
Eun, Seong Bae ; Chae, Yi Geun ;
Journal of the Korean Society of Marine Engineering, volume 38, issue 2, 2014, Pages 175~181
DOI : 10.5916/jkosme.2014.38.2.175
Location awareness is one of the key functions to build an U-city. Recently, many of works for the location-aware systems are emerging to be applied to on-going large-scale apartment complex. For example, when dwellers or cars with active tags are move in the apartment complex, the active tags broadcast their own identifiers periodically and receivers such that routers use this information to calculate the location of the active tags. Since the active tags can actually move between routers and coordinators, it requires a hand-off mechanism. In this paper, we investigate the hand-off problem occurred in location awareness system based on ZigBee active tags. We propose and analyze a new approach for handling the hand-off problem. Through a mathematical analysis, we show that our approach diminishes the quantity of packet transfer than ZigBee's approach.
A nonlinear transformation methods for GMM to improve over-smoothing effect
Chae, Yi Geun ;
Journal of the Korean Society of Marine Engineering, volume 38, issue 2, 2014, Pages 182~187
DOI : 10.5916/jkosme.2014.38.2.182
We propose nonlinear GMM-based transformation functions in an attempt to deal with the over-smoothing effects of linear transformation for voice processing. The proposed methods adopt RBF networks as a local transformation function to overcome the drawbacks of global nonlinear transformation functions. In order to obtain high-quality modifications of speech signals, our voice conversion is implemented using the Harmonic plus Noise Model analysis/synthesis framework. Experimental results are reported on the English corpus, MOCHA-TIMIT.
Relative azimuth estimation algorithm using rotational displacement
Kim, Jung-Ha ; Kim, Hyun-Jun ; Kim, Jong-Su ; Lee, Sung-Geun ; Seo, Dong-Hoan ;
Journal of the Korean Society of Marine Engineering, volume 38, issue 2, 2014, Pages 188~194
DOI : 10.5916/jkosme.2014.38.2.188
Recently, indoor localization systems based on wireless sensor networks have received a great deal of attention because they help achieve high accuracy in position determination by using various algorithms. In order to minimize the error in the estimated azimuth that can occur owing to sensor drift and recursive calculation in these algorithms, we propose a novel relative azimuth estimation algorithm. The advantages of the proposed technique in an indoor environment are that an improved weight average filter is used to effectively reduce impulse noise from the raw data acquired from nodes with inherent errors and a rotational displacement algorithm is applied to obtain a precise relative azimuth without using additional sensors, which can be affected by electromagnetic noise. Results from simulations show that the proposed filter reduces the impulse noise, and the acquired estimation error does not accumulate with time by using proposed algorithm.
A comparison of coupled and uncoupled dynamic analysis for the flexible riser in shallow water
Jo, Chul-Hee ; Kim, Do-Youb ; Hwang, Su-Jin ; Rho, Yu-Ho ;
Journal of the Korean Society of Marine Engineering, volume 38, issue 2, 2014, Pages 195~201
DOI : 10.5916/jkosme.2014.38.2.195
Flexible risers have been used extensively in recent years for floating and early production systems. Such risers offer the advantage of having inherent heave compliance in their catenary thereby greatly reducing the complexity of the riser-to-rig and riser-to subsea interfaces. Another advantage with flexible risers is their greater reliability. Concerns about fatigue life, gas permeation and pigging of lines have been overcome by extensive experience with these risers in production applications. In this paper, flexible riser analysis results were compared through coupled and uncoupled dynamic analyses methods. A time domain coupled analysis capability has been developed to model the dynamic responses of an integrated floating system incorporating the interactions between vessel, moorings and risers in a marine environment. For this study, SPM (Single Point Mooring) system for an FSU in shallow water was considered. This optimization model was integrated with a time-domain global motion analysis to assess both stability and design constraints of the flexible riser system.
The study on a ship energy management system applied rechargeable battery
Jang, Jae-Hee ; Oh, Jin-Seok ;
Journal of the Korean Society of Marine Engineering, volume 38, issue 2, 2014, Pages 202~207
DOI : 10.5916/jkosme.2014.38.2.202
Recently, the study of energy saving technology of ships begins in earnest, as energy saving policies are performed all around the world. SEMS (Ship Energy Management System) is one of the techniques to increase energy efficiency by applying to a independent system like a ship and offshore. SEMS is composed of Cooling Pump Control System (CPCS), Renewable Energy Emergency Power Control System (REEPCS), Load Control System (LCS), and Heating, Ventilation, and Air Conditioning System (HVACS). SEMS is enable to increase energy efficiency and achieve integrated management through the interlocking of each system. Especially, it is possible to improve the flexibility of the selection of the generator capacity in conjunction with a rechargeable battery and renewable energy. In this paper, SEMS applied rechargeable battery is proposed and simulated. By applying the rechargeable battery, it was confirmed that SEMS applied rechargeable battery can be operated at optimum efficiency of the generator.
Analysis of haline channel formed in the East China Sea and the Atlantic Ocean using the T-S gradient diagram
Kim, Juho ; Kim, Hansoo ; Paeng, Dong-Guk ;
Journal of the Korean Society of Marine Engineering, volume 38, issue 2, 2014, Pages 208~216
DOI : 10.5916/jkosme.2014.38.2.208
In case of any coastal ocean near the mouth of huge rivers, low salinity water can be formed due to its large amount of freshwater discharge. For the acoustic analysis on the low salinity environment, some oceanographic data of the East China Sea and the Atlantic Ocean were collected through KODC (Korea Oceanographic Data Center) and NODC (National Oceanographic Data Center) online service. In this paper, the T-S gradient diagram is introduced to show a relation between the gradients of temperature and salinity in view of acoustic surface channel formation. Existence of haline channel, quantitative contribution of gradients of salinity and temperature, effectiveness of the channel formation can be known by the T-S gradient diagram. After applying the collected data into the diagram, tropical regions of the Atlantic Ocean show strong haline channel due to its nearly invariant temperature and drastic change of salinity with depth. The averaged transmission loss in the channel is about 5.7 ~ 7.5 dB less than that out of the channel by the results of acoustic propagation model (RAM: Range independent Acoustic Model). On the other hand, the East China Sea and temperate region of the Atlantic ocean have weaker haline channel with less difference of the averaged transmission loss between in and out of the channel as 3.2 ~ 6.0 dB. Although data samples used in this study have limitation to represent the general physical structures of the three ocean regions, the T-S gradient diagram is shown to be useful and acoustic field affected by low salinity environment is investigated in this study.
Dynamics model of the float-type wave energy converter considering tension force of the float cable
Hadano, Kesayoshi ; Lee, Sung-Bum ; Moon, Byung-Young ;
Journal of the Korean Society of Marine Engineering, volume 38, issue 2, 2014, Pages 217~224
DOI : 10.5916/jkosme.2014.38.2.217
We have developed the novel device that can extract energy from ocean waves utilizing the heaving motion of a floating mass. The major components of the energy converter are: a floater, a counterweight, a cable, a driving pulley, two idler pulleys, a ratchet, and a generator. The device generates power through the tension force in the cable and the weight difference between the floater and the counterweight. When the system is at static free condition, the tension in the cable is equal to the weight of the counterweight which is minimum. Therefore it is desirable to keep the counterweight lighter than the floater. However, experiments show that during the rise of the water level, the torque generated by weight of the counterweight is insufficient to rotate the driving pulley which causes the cable on the floater side to slack. The proposed application of the tension pulley rectifies these problems by preventing the cable from becoming slack when the water level rises. In this paper, the dynamics model is modified to incorporate the dynamics of the tension pulley. This has been achieved by first writing the dynamical equations for the tension pulley and the energy converter separately and combining them later. This paper investigates numerically the effect of the tension pulley on various physical quantities such as the cable tension, the floater displacement, and the floater velocity. Results obtained indicate that this application is successful in suppressing large fluctuations of the cable tension.
A modified tabu search for redundancy allocation problem of complex systems of ships
Kim, Jae-Hwan ; Jang, Kil-Woong ;
Journal of the Korean Society of Marine Engineering, volume 38, issue 2, 2014, Pages 225~232
DOI : 10.5916/jkosme.2014.38.2.225
The traditional RAP (Redundancy Allocation Problem) of complex systems has considered only the redundancy of subsystem with homogeneous components. In this paper we extend it as a RAP of complex systems with heterogeneous components which is more flexible than the case of homogeneous components. We model this problem as a nonlinear integer programming problem, find its optimal solution by tabu search, and suggest an example of the efficient reliability design with heterogeneous components. In order to improve the quality of the solution of the tabu search, we suggest a modified tabu search to employ an adaptive procedure (1-opt or 2-opt exchange) to generate the efficient neighborhood solutions. Computational results show that our modified procedure obtains better solutions as the size of problem increases from 30 to 50, even though it requires rather more computing time. With some adjustment of the parameters of the proposed method, it can be applied to the optimal reliability designs of complex systems of ships.