• Journal of Advanced Marine Engineering and Technology
• /
• v.35 no.6
• /
• pp.740-749
• /
• 2011

The strengthened regulations for atmospheric emissions from ships have caused a necessity of new, alternative power system in ships for the low pollutant emissions and the high energy efficiency. Recently, new kinds of propulsion power system such as fuel cell system, which use hydrogen as an energy source, have been sincerely considered. The purpose of this work is to predict the performance of gasoline fueled SOFC system and to analyze the influence of operating temperature, current density, S/C, and H2 utilization ratio. The results are compared with the methane fueled system. The results show that the cell voltage and $O_2$ utilization ratio are major factors on the performance of system and the gasoline fueled SOFC system have lower efficiency than the methane fueled system.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.42 no.1
• /
• pp.19-29
• /
• 2006

To investigate the fishery and fishing ground environment of red horsehead (Branchiostegus japonicus), the author analyzed the fishery data and examined the amount of catches and oceanic environment on the adjacent seas of Jeju island and East China Sea. It was turned out that the favourable season of the red horsehead fishery is the month from March to June, the main fishing ground is located in 60 mile radius from the position $32.5^{\circ}N,\;125.7^{\circ}E$. The bottom seawater temperature in fishing ground was shown between $l3^{\circ}C\;and\;16^{\circ}C$, the salinity was appeared between 33.5 and 34.0psu without the seasonal variation of the year. Concentrations of materials(e.g, $NO_3^-\;and\;NO_2^-$) in spring and summer time in main fishing ground were higher than any other seasons, but that of phospheric materials were lower than any other seasons. Concentrations of $chlorophyll\;-\;{\alpha}$ in the main fishing ground was the highest in spring and summer at the surface layer, but the vertical profile of the $chlorophyll\;-\;{\alpha}$ concentrations in all seasons were not variable at bottom layer. Mean density of zooplankton abundance according to the vertical structure was higher and much stable in summer and autumn than spring and winter.

• Journal of Ocean Engineering and Technology
• /
• v.26 no.4
• /
• pp.50-56
• /
• 2012

When a liquid cargo tank is partially filled with fluid, internal impact loads can be occurred from the vessel's motions. In this study, liquid sloshing problems with a thin top layer of particles with a lighter density than water and the coupling effects of the liquid-sloshing/vessel-motion were investigated in order to reduce the sloshing-induced impact loads. The PNU-MPS (Pusan-National-University-modified Moving Particle Simulation) method for solving the liquid motion inside a tank and the CHARM3D BEM (Boundary Element Method) based time-domain ship motion analysis program for vessel-motion simulation were coupled. From the simulation results, we could see that the floaters seemed to be quite effective at reducing the sloshing impact loads in the case of tank-only sloshing problems, but not as much for the coupling problem with vessel motion.

• Journal of Advanced Marine Engineering and Technology
• /
• v.35 no.5
• /
• pp.590-599
• /
• 2011

The electrification of the waste heat of fuel cell is necessary to enhance the efficiency of fuel cell system. For this purpose, the SOFC/ST(Solid oxide fuel cell/Steam turbine) hybrid system is suitable. The purpose of this work is to predict the performance of methane fueled SOFC/ST hybrid power system and to analyze the influence of operating temperature of stack, current density of stack, combustor outlet gas temperature, and boiler outlet gas temperature. According to the analysis, it is proved that making the best use of the waste heat of stack and minimizing the fuel consumption of combustor are essential for the high-efficiency of SOFC/ST hybrid system.

• Design & Manufacturing
• /
• v.14 no.2
• /
• pp.62-68
• /
• 2020

Recently, research on precise parts required in aerospace, ship, and automobile industries has been actively conducted. In this paper, electron beam drilling machining parameters were selected and experiments were conducted to compare processing characteristics analysis according to machining parameters through machining experiments of a vaporization amplification sheet to which STS 304 was applied. Also, as a result of measuring the machining. As the thickness gradually increased, it was confirmed that the electron beam could not reach the vaporization amplification sheet and thus melted on the surface of the material. As a result of the experimental analysis, it was analyzed that the vaporization explosion reaction of the vaporization amplification sheet was not normally performed due to the working distance (WD) according to the material thickness.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.38 no.2
• /
• pp.101-109
• /
• 2002

The aluminum honeycomb sandwich panel (AHSP) structure not only have high flexural rigidity and strength per density but also excellence in vibration and noise properties. The AHSP structure are very useful for railway, airplane and high speed ship which need lighter-weighted and more strengthened elements. In this paper, from comparison the AHSP with the equivalent aluminum single plate (EASP) structure on the result of analysis, it was shown that the AHSP is S times lighter weight to the same stiffness than the EASP. And the AHSP structure have high bending rigidity and small shear rigidity in the direction of the thickness. Also, to the characteristics of vibration for the AHSP and EASP, which the stiffness is larger than the EASP, are higher than EASP.

• Journal of Nutrition and Health
• /
• v.38 no.1
• /
• pp.56-66
• /
• 2005

The purpose of this study was to assess the zinc and copper status of type 2 diabetic women and to analyse the relation-ship among zinc and copper status, and diabetic control indices of diabetes. The mean age of diabetes was 57.9 years old. The mean duration of diabetes was 8.0 $\pm$ 6.5 years. The mean daily energy intake of diabetes was 1562 kcal. There were no significant differences of age, BMI, %body fat, nutritional intakes, total energy intake, and energy composition from carbohydrate, protein, and fat between diabetes (n = 50) and control group (n = 68). However, both zinc intake density (4.15 mg/1000 kcal) and zinc %RDA (62.0%) of diabetes were significantly lower than control group (p <0.05, P < 0.01, respectively). The plasma zinc level was not significantly different between diabetes and control group (90$\mu$g/dl, 91$\mu$g/dl respectively). The proportion of diabetic women whose plasma zinc levels were lower than 76 $\mu$g/dl(borderline zinc deficiency) was 18.8%. This was about 38% higher than control group. It has been suggested that insulin secretion might decrease in borderline plasma zinc and copper deficiency and increase in normal plasma zinc and copper status. The urinary zinc excretion was twice higher in diabetes than in control group (p < 0.001). The urinary zinc loss was positively correlated with the duration of diabetes (p < 0.05), hyperglycemia (p < 0.001) and insulin resistance (p < 0.05). These results lead us to conclude that normal blood glucose level controlled by diet therapy could improve the hyperzincuria in diabetic women.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2004.08a
• /
• pp.208-216
• /
• 2004

Since 2000, the authors have been developing remote radar network system to observe the vessel traffic in Tokyo Bay. In December 2002, the first operational remote radar station was set at the National Defense Academy in Yokosuka, and vessel traffic observation was started. However, it was impossible to perform accurate observation in the northern part of Tokyo Bay by this Yokosuka radar station only. In September 2003, the second remote radar station and AIS receiving station were installed at Higashi Ogishima in Kawasaki. This second radar enabled us to carry out accurate observation in that area. Both radars can be remotely controlled from the monitoring station in Tokyo University of Marine Science and Technology. On September 30 and October 1,2003, the vessel traffic observation was carried out using both radars. Combining radar images observed by both radars, the ships' tracks were taken and the dangerous ships were extracted by using SJ value and Bumper Model. The time changes of dangerous ship density in some areas in Tokyo Bay and utilization ratio of the traffic routes were also investigated. In addition, analyzing the AIS date received at Kawasaki station, the positions and speed vectors of the ships equipped with AIS were shown.

• Journal of Ocean Engineering and Technology
• /
• v.21 no.5
• /
• pp.33-38
• /
• 2007

The welding methods have been applied in the most structural products from multi-field of automobile, ship construction and construction, and so on. The structure steel must have enough strength of structure. In this study, SS400 steel and STS304 steel were used to estimate the corrosion characteristics of the weld thermal cycle simulated HAZ. To evaluate the corrosion characteristics, also, the materials with two conditions were used in 3.5% NaCl. The one is to the drawing with diameter of ${\Phi}10$ and the other is to the residual stress removal treatment. The electrochemical polarization test and immersion test were carried out. From test results, corrosion potential, corrosion current density, weight loss ratio and corrosion rate were measured. In the kinds of SS400 steels, corrosion potential of weld thermal cycle simulated specimens after the heat treatment showed somewhat the direction of noble potential. And in the base metal to be drawing weight loss ratio and corrosion rate occurred higher than the other kinds. In the kinds of STS304 steels, the result of base metal to be drawing was similar to results of SS400 steels, too. Two kinds of $750^{\circ}C$ and $1300^{\circ}C$ of weld thermal cycle simulation after the heat treatment were rather higher than the other kinds in weight loss ratio and corrosion rate.

• Journal of Advanced Marine Engineering and Technology
• /
• v.36 no.1
• /
• pp.40-50
• /
• 2012

The electrification of the waste heat of stack is necessary to enhance the efficiency of fuel cell system. For this purpose, the hybrid SOFC/GT/ST system is suitable. The purpose of this work is to predict the performance of methane fueled SOFC/GT/ST hybrid power system and to analyze the influence of operating temperature of stack, current density of stack, and gas turbine pressure ratio. According to the analysis, it is proved that the SOFC/GT/ST hybrid system suppress the rapid decrease in efficiency and lead to the significant improvement of efficiency as compared with SOFC system.