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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 39, Issue 10 - Dec 2015
Volume 39, Issue 9 - Nov 2015
Volume 39, Issue 8 - Oct 2015
Volume 39, Issue 7 - Sep 2015
Volume 39, Issue 6 - Jul 2015
Volume 39, Issue 5 - Jun 2015
Volume 39, Issue 4 - May 2015
Volume 39, Issue 3 - Mar 2015
Volume 39, Issue 2 - Feb 2015
Volume 39, Issue 1 - Jan 2015
Selecting the target year
Numerically-Investigated Thermal Performances of Hybrid Fin Heat Sinks for Lightweight Thermal Management of LED Modules Under Natural Convection
Kim, Kyoung Joon ;
Journal of the Korean Society of Marine Engineering, volume 39, issue 6, 2015, Pages 586~591
DOI : 10.5916/jkosme.2015.39.6.586
This study discusses numerically-explored thermal performances of hybrid fin heat sinks (HF HSs) for lightweight thermal management of LED modules under natural convection. A hollow hybrid fin heat sink (HHF HS) and a solid hybrid fin heat sink (SHF HS) are proposed as HF HSs. A 3-D CFD analysis has been carefully conducted to obtain reliable numerical results. The 3-D CFD study investigates the effects of both fin spacing and an internal channel diameter on performances of the HHF HS and the SHF HS. The study results show that the mass-based thermal resistance of the HHF HS is 20~32% smaller compared with the pin fin heat sink (PF HS). The results also show that the mass-based thermal resistance of the HHF HS decreases with the increase of the channel diameter. These results are mainly due to coupled effects of the mass reduction and heat pumping through an internal channel. Considerably superior mass-based thermal performances of the HHF HS to the conventional PF HS suggest the feasible application for the lightweight thermal management of the LED modules under natural convection.
Cooling Performance Characteristics of High-Performance Heat Pump with VI Cycle Using Re-Cooler
Lee, Jin-Kook ; Choi, Kwang-Hwan ;
Journal of the Korean Society of Marine Engineering, volume 39, issue 6, 2015, Pages 592~598
DOI : 10.5916/jkosme.2015.39.6.592
In this study, we experimentally investigate the performance characteristics of a high-performance summer-cooling heat pump for an R410A by applying an air-cooled-type vapor-injection (VI) cycle. The devices used for the experiment consist of a VI compressor, condenser, oil separator, plate-type heat-exchanger, economizer, evaporator, and re-cooler. The experimental conditions employed for the cooling performance were divided into three cycles. First, in Cycle A, we apply a VI cycle and with no heat exchange between the evaporator outlet refrigerant and the VI cycle suction refrigerant in the re-cooler. For Cycle B, there is heat exchange, and for Cycle C, there is neither a VI cycle nor heat exchange between the evaporator outlet refrigerant and the VI cycle suction refrigerant. From the analysis results, we observe that the performance was highest in the VI cycle with heat exchange between the evaporator outlet refrigerant and the VI cycle suction refrigerant (Cycle B), while it was lowest in Cycle C without application of the VI cycle. Moreover, the cooling coefficient of Performance (
) averaged 3.5 in Cycle B, which was 8.6% higher than the corresponding value in Cycle A, and 33% higher than that in Cycle C.
Effect of Storage Tank Structure Variation on Fuel Shiftting
Ryu, Myeong-Rok ; Lee, Gye-Gwang ; Park, Kweon-Ha ;
Journal of the Korean Society of Marine Engineering, volume 39, issue 6, 2015, Pages 599~603
DOI : 10.5916/jkosme.2015.39.6.599
To strengthen the existing regulations with respect to carbon emissions in the marine industry, there has been an increase in the number of studies focusing on realizing improvements in the utilization of vessels. While the development of new techniques related to these improvements can be costly, in this paper, we discuss a cost-effective method that may be applied directly to existing ships. The experimental data obtained suggests that the greatest reduction in energy loses can be realized by installing a double-partition wall on the storage tank of the ship, among other methods.
A Study on the Heat Transfer Characteristic of Insulated Multi Core Tube
Park, Sang-Kyun ; Lee, Tae-Ho ; Kim, Myoung-Jun ;
Journal of the Korean Society of Marine Engineering, volume 39, issue 6, 2015, Pages 604~608
DOI : 10.5916/jkosme.2015.39.6.604
In this paper, we study the characteristics of heat transfer for an insulated multi-core tube using glass wool as an insulator for the multi-core tube. By performing experiments and modeling, we examine the variations in the temperature characteristics of hydraulic oil inside the multi-core tube with atmosphere temperature, inlet temperature, and the flow rate of hydraulic oil for the insulated multi-core tube that we developed. When the minimum inlet flow rate of hydraulic oil employed within the scope of the research is 0.29 l/min, the temperature difference obtained in the experiments and numerical analysis was a maximum of
. For a constant atmospheric temperature, as the inlet temperature of the hydraulic oil increases, the outlet temperature of the hydraulic oil will also increase, regardless of its inlet flow rate. Further, when the inlet flow rate of the hydraulic oil is more than 1.01 l/min, the effect of the atmospheric temperature on the temperature drop of the hydraulic oil is low.
Effects of Rib Angles on Heat Transfer in a Divergent Square Channel With Ribs on One Wall
Lee, Myung Sung ; Ahn, Soo Whan ;
Journal of the Korean Society of Marine Engineering, volume 39, issue 6, 2015, Pages 609~613
DOI : 10.5916/jkosme.2015.39.6.609
In this study, the experiments are performed to investigate the local heat transfer and pressure drops of developed turbulent flows in the diverging square channels along the axial distance. The square divergent channels are manufactured with a fixed rib height (e)
Motion Performance Prediction and Experiments of an Autonomous Underwater Vehicle through Fluid Drag Force Calculations
Kim, Chang Min ; Baek, Woon Kyung ;
Journal of the Korean Society of Marine Engineering, volume 39, issue 6, 2015, Pages 614~619
DOI : 10.5916/jkosme.2015.39.6.614
In this study, a dynamics model was developed to predict the motion performance of an Autonomous Underwater Vehicle (AUV). The dynamics model includes basic dynamic state variables of the hull and force terms to determine the motion of the AUV. The affecting terms for the forces are hydrostatic force, added mass, hydrodynamic damping, lift and drag forces. The force terms can be calculated using analytical and Computational Fluid Dynamics methods. For the underwater motion simulation, a simple PD controller was used. Also, the AUV was tested in a water tank and near sea for the partial verification of the fluid drag force coefficients and way-point tracking motions.
An Experimental Study of the Fuel Additive to Improve the Performance of a 2-Stroke Large Diesel Engine
Ryu, Younghyun ; Lee, Youngseo ; Nam, Jeonggil ;
Journal of the Korean Society of Marine Engineering, volume 39, issue 6, 2015, Pages 620~625
DOI : 10.5916/jkosme.2015.39.6.620
In an effort to reduce the onset of global warming, the International Maritime Organization Marine Environment Protection Committee (IMO MEPC) proposed the reduction in ship speeds as a way of lowering the proportion of carbon dioxide (
) in the Green House Gas emissions from ships. To minimize fuel costs, shipping companies have already been performing slow steaming for their own fleets. Specifically, the slow steaming approach has been adopted for most ocean-going container lines. In addition, because of the increased marine fuel cost that is required to enable increased capacity, there is an urgent need for more advanced fuel-saving technologies. Therefore, in this present study, we propose a fuel-cost reduction method that can improve the performance of diesel engines. We introduce a predetermined amount (0.025% of the amount of fuel used) of fuel additive (oil-soluble calcium-based organometallic compound). For improved experimental accuracy, as the test subjects, we utilize a large two-stroke diesel engine installed in land plants. The loads of the test engine were classified as low, medium, and high (50, 75, and 100%, respectively). We compare the engine performance parameters (power output, fuel consumption rate, p-max, and exhaust temperature) before and after the addition of fuel additives. Our experimental results, confirmed that we can realize fuel-cost savings of at least 2% by adding the fuel additive in low load conditions (50%). Likewise, the maximum combustion pressure was found to have increased. On the other hand, we observed that there was a reduction in the exhaust temperature.
Prediction of Matching Performance of Two-Stage Turbo-charging System Design for Marine Diesel Engine
Bae, Jin-woo ; Lee, Ji-woong ; Jung, Kyun-sik ; Choi, Jae-sung ;
Journal of the Korean Society of Marine Engineering, volume 39, issue 6, 2015, Pages 626~632
DOI : 10.5916/jkosme.2015.39.6.626
The International Maritime Organization (IMO) has adopted several regulations for the prevention of air pollution from ships. In addition, there is a requirement for shipping liners to reduce greenhouse gas emissions. Accordingly, we need to take measurements to ensure that the steps taken are both efficient and environmentally friendly. It has been determined that the application of the Miller cycle in diesel engines has the effect of both reducing the amount of NOx and improving thermal efficiency. However, this method requires a considerably larger charge air pressure. Therefore, we consider a two-stage turbo-charging system, which not only results in a high charging pressure, but also improves the part load performance with an exhaust-gas bypass system or the application of the Miller cycle. Because of complications associated with the two-stage turbo-charging system, it is complex and difficult to realize a design that optimizes matching between diesel engine and turbo-chargers. Accordingly, it is necessary to perform a quantitative analysis to determine the effects and optimal conditions of these different systems in the early stage of system design. In this paper, we develop a simulation program to model these systems, and we verify that the results of this program are reliable. Further, we discuss methods that can be employed to improve its efficiency.
GA-Based Design of a Nonlinear PID Controller and Application to a CSTR Process
Lee, Joo-Yeon ; So, Gun-Baek ; Lee, Yun-Hyung ; So, Myung-Ok ; Jin, Gang-Gyoo ;
Journal of the Korean Society of Marine Engineering, volume 39, issue 6, 2015, Pages 633~641
DOI : 10.5916/jkosme.2015.39.6.633
Several complex processes that are employed in industries, such as shipping, power plants, and the petrochemical industry, involve time-varying behavior as well as strong nonlinear behavior during operation. The fixed-parameter proportional-integral-derivative (PID) controllers have difficulty in dealing with control problems that occur in such processes. In this paper, we propose a method of designing a nonlinear PID controller for industrial processes that exhibit a large number of nonlinearities and time-varying behavior. The gains of the nonlinear PID controller are characterized by a simple nonlinear function of the error and/or error rate depending on the process set-point and output. We tune the user-defined parameters using a genetic algorithm by minimizing the integral of time absolute error (ITAE) index. We verify the effectiveness of the proposed method by performing a comparison of the proposed method and two other nonlinear and adaptive methods that are employed for reference tracking, disturbance-rejection performances, and robustness to parameter changes on a continuously stirred tank reactor.
A Study on the Development of the Engine Room Fan Control System and ERFCS Algorithm for Ships Energy Saving
Kang, Young-Min ; Oh, Jin-Seok ;
Journal of the Korean Society of Marine Engineering, volume 39, issue 6, 2015, Pages 642~648
DOI : 10.5916/jkosme.2015.39.6.642
Recently, there have been many studies pertaining to reducing energy consumption on ships. As part of those studies, the energy consumption of ships can be reduced by understanding and controlling the varying loads, excluding fixed loads. In existing ships, engine room fans are usually operated based on the actual experience of the crew without any special guidelines. To realize energy reduction, we investigate the characteristics of engine-room fans, and we propose an energy-management system called the engine room fan control system (ERFCS) and the ERFCS algorithm. The ERFCS controls the fan speed depending on the temperature and pressure, where one to four fans are operated depending on changes in the load. In addition, the minimum rotation speed of the engine-room fan was limited to 50% to prevent the surging phenomenon, which is due to fan damage or low pressure resulting from mechanical friction or heating at low fan speeds. We develop a fan control system simulation model using LabVIEW that is based on the proposed algorithm and ISO 8861. Finally, we perform simulations to confirm that operation of the proposed fan control system is possible using only 46.4% of the power required by the existing method.
A Single Image Defogging Algorithm Based on Multi-Resolution Method Using Histogram Information and Dark Channel Prior
Yang, Seung-Yong ; Yang, Jeong-Eun ; Hong, Seok-Keun ; Cho, Seok-Je ;
Journal of the Korean Society of Marine Engineering, volume 39, issue 6, 2015, Pages 649~655
DOI : 10.5916/jkosme.2015.39.6.649
In this paper, we propose a defogging algorithm for a single image. Dark channel prior (DCP), which is a well-known defogging algorithm, can cause halo artifacts on boundary regions, low-contrast defogging images, and requires a large computational time. To solve these problems, we use histogram information with DCP on transmission estimation regions and a multi-resolution method. Local histogram information can reduce the low-contrast problem on a defogging image, and the multi-resolution method with edge information can reduce the total computational time and halo artifacts. We validate the proposed method by performing experiments on fog images, and we confirm that the proposed algorithm is more efficient and superior than conventional algorithms.
Performance Analysis of a Korean Word Autocomplete System and New Evaluation Metrics
Lee, Songwook ;
Journal of the Korean Society of Marine Engineering, volume 39, issue 6, 2015, Pages 656~661
DOI : 10.5916/jkosme.2015.39.6.656
The goal of this paper is to analyze the performance of a word autocomplete system for mobile devices such as smartphones, tablets, and PCs. The proposed system automatically completes a partially typed string into a full word, reducing the time and effort required by a user to enter text on these devices. We collect a large amount of data from Twitter and develop both unigram and bigram dictionaries based on the frequency of words. Using these dictionaries, we analyze the performance of the word autocomplete system and devise a keystroke profit rate and recovery rate as new evaluation metrics that better describe the characteristics of the word autocomplete problem compared to previous measures such as the mean reciprocal rank or recall.
Analysis of Influential Factors on Wax Deposition for Flow Assurance in Subsea Oil Production System
Jung, Sun-Young ; Kang, Pan-Sang ; Lim, Jong-Se ;
Journal of the Korean Society of Marine Engineering, volume 39, issue 6, 2015, Pages 662~669
DOI : 10.5916/jkosme.2015.39.6.662
There has been an increased interest in the mitigation of wax deposition because wax, which usually accumulates in subsea oil-production systems, interrupts stable oil production and significantly increases the cost. To guarantee a required oil flow by mitigating wax deposition, we need to obtain a reliable estimation of the wax deposition. In this research, we perform simulations to understand the major mechanisms that lead to wax deposition, namely molecular diffusion, shear stripping reduction, and aging. While the model variables (shear reduction multiplier, wax porosity, wax thermal conductivity, and molecular diffusion multiplier) can be measured experimentally, they have high uncertainty. We perform an analysis of these variables and the amount of water and gas in the multiphase flow to determine these effects on the behavior of wax deposition. Based on the results obtained during this study for a higher wax porosity and molecular diffusion multiplier, we were able to confirm the presence of thicker wax deposits. As the shear reduction multiplier decreased, the thickness of the wax deposits increased. As the amount of water increased, there was also an increase in the amount of wax deposits until 40% water cut and decreased. As the amount of gas increased, the amount of wax deposits increased because of the loss of the light hydrocarbon component in the liquid phase. The results of this study can be utilized to estimate the wax deposition behavior by comparing the experiment (or field) and simulation data.