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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 40, Issue 6 - Jul 2016
Volume 40, Issue 5 - Jun 2016
Volume 40, Issue 4 - May 2016
Volume 40, Issue 3 - Mar 2016
Volume 40, Issue 2 - Feb 2016
Volume 40, Issue 1 - Jan 2016
Selecting the target year
Analysis of the thermal management of a high power LED package with a heat pipe
Kim, Jong-Soo ; Kim, Eun-Pil ;
Journal of the Korean Society of Marine Engineering, volume 40, issue 2, 2016, Pages 96~101
DOI : 10.5916/jkosme.2016.40.2.96
The thermal management of high-power LED components in an assembly structure is crucial for the stable operation and proper luminous function. This study employs numerical tools to determine the optimum thermal design in LEDs with a heat sink consisting of a crevice-type vapor-chamber heat pipe. The effects of the MCPCB are investigated in terms of the substrate thicknesses on which the LEDs are mounted. Further, different placement configurations in a system module are considered. This study found that for a confined area, a power of 40 W/LED is applicable to a high-power package. Furthermore, the thermal conductivity of dielectric layer materials should ideally be greater than 0.9 W/m.K. The temperature conditions of the vapor chamber in a heat pipe greatly affect the thermal performance of the system. At an offset distance of 9.0 mm and a
increase in the temperature of the heat pipe, the resulting maximum temperature increase is approximately
for each heat dissipation temperature. Finally, at a thermal conductivity of 0.3 W/m.K, it was found that the total thermal resistance changes dramatically. Above 1.2 W/m.K, the resistance change reduces exponentially.
Effects of various densities and velocities on gaseous hydrocarbon fuel on near nozzle flow field under different laminar coflow diffusion flames
Ngorn, Thou ; Jang, Sehyun ; Yun, Seok Hun ; Park, Seol Hyeon ; Lee, Joo Hee ; Chung, Suk Ho ; Choi, Jae Hyuk ;
Journal of the Korean Society of Marine Engineering, volume 40, issue 2, 2016, Pages 102~106
DOI : 10.5916/jkosme.2016.40.2.102
An experimental study on the flow characteristics under various laminar coflow diffusion flames was conducted with a particular focus on the buoyancy force exerted from gaseous hydrocarbon fuels. Methane (
), ethylene (
), and n-butane (
) were used as the fuels. A coflow burner and the Schlieren imaging technique were used to observe the flow field of each fuel near the nozzle exit as well as the flow characteristics in the flames. The results show that a vortex with a density heavier than air appeared in n-butane near the nozzle exit with a strong negative buoyancy on the fuel steam. As the Reynolds number increased through the control of the fuel velocity of the n-butane flame, the vortices were greater and the vortex tips were moved up from the nozzle exit. In addition, the heated nozzle affected the flow fields of the fuel steam near the nozzle exit.
Corrosion behaviors of cement mortar specimens with different cover thickness in natural sea water
Jeong, Jin-A ; Jin, Chung-Kuk ; Jeong, Eun-Seok ;
Journal of the Korean Society of Marine Engineering, volume 40, issue 2, 2016, Pages 107~111
DOI : 10.5916/jkosme.2016.40.2.107
This paper presents electrochemical corrosion behaviors of cement mortar specimens in the high salinity condition. Chloride ion is known as the most detrimental parameter to cause the corrosion in reinforced concrete. Increasing the concrete cover thickness is one of the corrosion protection methods against chloride ion; so, this study mainly focuses on the effects of mortar cover thickness on corrosion protection. In specimens, rebar, which was a height of 200 mm and a diameter of 10 mm, was installed at the center of the small size form. Later on, mortar was injected into the form, and 10, 20, 30, 40, and 50 mm of the different mortar cover thicknesses were selected. Potential measurements, linear polarization resistance tests, and cyclic potentiodynamic polarization tests were performed for specimens that were exposed to seawater. These results were compared with visual inspection results of rebar. The results show that an increase in the cover thickness contributes to corrosion protection. In addition, the result of electrochemical corrosion tests generally agreed with that of an autopsy visual inspection.
CFD analysis of the effect of different PAR locations against hydrogen recombination rate
Lee, Khor Chong ; Ryu, Myungrok ; Park, Kweonha ;
Journal of the Korean Society of Marine Engineering, volume 40, issue 2, 2016, Pages 112~119
DOI : 10.5916/jkosme.2016.40.2.112
Many studies have been conducted on the performance of a passive autocatalytic recombiner (PAR), but not many have focused on the locations where the PAR is installed. During a severe accident in a nuclear reactor containment, a large amount of hydrogen gas can be produced and released into the containment, leading to hydrogen deflagration or a detonation. A PAR is a hydrogen mitigation method that is widely implemented in current and advanced light water reactors. Therefore, for this study, a PAR was installed at different locations in order to investigate the difference in hydrogen reduction rate. The results indicate that the hydrogen reduction rate of a PAR is proportional to the distance between the hydrogen induction location and the bottom wall.
A study on rotational motion control for ship steering motion control
Park, Seong-Hwan ; Kim, Jong-Hwa ;
Journal of the Korean Society of Marine Engineering, volume 40, issue 2, 2016, Pages 120~130
DOI : 10.5916/jkosme.2016.40.2.120
In general, a series of ship steering motions is composed of a combination of translational motions and rotational motions of the ship. In particular, a series of rotational motions frequently occurs in narrow areas such as ports and canal zones. In this paper, a method was suggested for composing an integrated control algorithm based on the jog dial as a command instrument for rotational motion control. In order to realize the rotational motions, several algorithms were suggested for generating rotational commands, for selecting motion variables, for choosing reference input values for the motion variables, for computing required accelerations and thrusts, and for allocating thrusts to actuators. A simulation program was compiled to execute simulations for three rotational motions. Finally, the effectiveness of the suggested method was verified by analyzing the simulation results.
Analysis of generalized progressive hybrid censored competing risks data
Lee, Kyeong-Jun ; Lee, Jae-Ik ; Park, Chan-Keun ;
Journal of the Korean Society of Marine Engineering, volume 40, issue 2, 2016, Pages 131~137
DOI : 10.5916/jkosme.2016.40.2.131
In reliability analysis, it is quite common for the failure of any individual or item to be attributable to more than one cause. Moreover, observed data are often censored. Recently, progressive hybrid censoring schemes have become quite popular in life-testing problems and reliability analysis. However, a limitation of the progressive hybrid censoring scheme is that it cannot be applied when few failures occur before time T. Therefore, generalized progressive hybrid censoring schemes have been introduced. In this article, we derive the likelihood inference of the unknown parameters under the assumptions that the lifetime distributions of different causes are independent and exponentially distributed. We obtain the maximum likelihood estimators of the unknown parameters in exact forms. Asymptotic confidence intervals are also proposed. Bayes estimates and credible intervals of the unknown parameters are obtained under the assumption of gamma priors on the unknown parameters. Different methods are compared using Monte Carlo simulations. One real data set is analyzed for illustrative purposes.
Subset selection in multiple linear regression: An improved Tabu search
Bae, Jaegug ; Kim, Jung-Tae ; Kim, Jae-Hwan ;
Journal of the Korean Society of Marine Engineering, volume 40, issue 2, 2016, Pages 138~145
DOI : 10.5916/jkosme.2016.40.2.138
This paper proposes an improved tabu search method for subset selection in multiple linear regression models. Variable selection is a vital combinatorial optimization problem in multivariate statistics. The selection of the optimal subset of variables is necessary in order to reliably construct a multiple linear regression model. Its applications widely range from machine learning, timeseries prediction, and multi-class classification to noise detection. Since this problem has NP-complete nature, it becomes more difficult to find the optimal solution as the number of variables increases. Two typical metaheuristic methods have been developed to tackle the problem: the tabu search algorithm and hybrid genetic and simulated annealing algorithm. However, these two methods have shortcomings. The tabu search method requires a large amount of computing time, and the hybrid algorithm produces a less accurate solution. To overcome the shortcomings of these methods, we propose an improved tabu search algorithm to reduce moves of the neighborhood and to adopt an effective move search strategy. To evaluate the performance of the proposed method, comparative studies are performed on small literature data sets and on large simulation data sets. Computational results show that the proposed method outperforms two metaheuristic methods in terms of the computing time and solution quality.
15kW-class wave energy converter floater design and structural analysis
Singh, Patrick Mark ; Chen, Zhenmu ; Choi, Young-Do ;
Journal of the Korean Society of Marine Engineering, volume 40, issue 2, 2016, Pages 146~151
DOI : 10.5916/jkosme.2016.40.2.146
This study concentrates on the design of floater for 15kW-class wave energy converter that extracts the ocean energy by oscillating vertically along the wave motion. The floater connects to a arm structure that connects to a hydraulic cylinder, which drives a hydraulic generator. The study mainly focuses on the structural analysis of the floater. Previous studies have been conducted using a miniature model; however, this study focuses on the size selection of the floater for a full scale model. Static structural analysis is conducted using fine numerical grids. Due to the complexity of the whole model, it is analyzed as a separate component. There are several load cases for each floater size, and they are analyzed thoroughly for stress (von-mises, shear, and normal) and deformation. The initial design was conducted by scaling up from the miniature model of the previous study, and the final design has been redesigned by changing the thickness and internal support structure shape.