• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.3
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• pp.88-93
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• 2019

This study concerns the distributions of flow in an air conditioning duct used for a marine and oil drilling ship. From the results of carrying out flow analysis and structural analysis of a ventilation duct applied to a marine structure, the following conclusion could be gained. The pressure tended to increase as the flow velocity at the inlet increased and the pressure at the inlet increased. It was recognized that the pressure decreased due to the influence of a corrugated tube when it entered and exited from the duct. As a result of structural analysis, a higher train was generated at the corrugated tube compared with the duct. In addition, in the case of the internal pressure of 0.7MPa, which was the designed load, it was found that there was almost no influence as it was within 0.1mm.

• Journal of the Korean Society for Marine Environment & Energy
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• v.18 no.4
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• pp.304-309
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• 2015

To evaluate the degree of contamination caused by oil spill accident in the sea, the in-situ sensors which are based on the scientific method are needed in the real site. The sensors which are based on the fluorescence detection theory can provide the useful data, such as the concentration of oil. However these kinds of sensors commonly are composed of the ultraviolet (UV) light source such as UV mercury lamp, the multiple excitation/emission filters and the optical sensor which is mainly photomultiplier tube (PMT) type. Therefore, the size of the total sensing platform is large not suitable to be handled in the oil spill field and also the total price of it is extremely expensive. To overcome these drawbacks, we designed the fluorimeter for the oil spill detection which has compact size and cost effectiveness. Before the detail design process, we conducted the experiments to measure the excitation and emission spectrum of oils using five different kinds of crude oils and three different kinds of processed oils. And the fluorescence spectrometer were used to analyze the excitation and emission spectrum of oil samples. We have compared the spectrum results and drawn the each common spectrum regions of excitation and emission. In the experiments, we can see that the average gap between maximum excitation and emission peak wavelengths is near 50 nm for the every case. In the experiment which were fixed by the excitation wavelength of 365 nm and 405 nm, we can find out that the intensity of emission was weaker than that of 280 nm and 325 nm. So, if the light sources having the wavelength of 365 nm or 405 nm are used in the design process of fluorimeter, the optical sensor needs to have the sensitivity which can cover the weak light intensity. Through the results which were derived by the experiment, we can define the important factors which can be useful to select the effective wavelengths of light source, photo detector and filters.

• Proceedings of the Korean Nuclear Society Conference
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• 1997.05a
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• pp.587-591
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• 1997

The DGs (Diesel Generators) in NPP (Nuclear Power Plant) has been used for the emergency electric power source to shut down the nuclear reactor safely in case of station blackout. The RCM (Reliability Centered Maintenance) has been applied to DGs for increasing the safety of NPP. The structured defects of DG were not remedied by the improvement of maintenance method. As the first stage of RCM, to find the structured defects, its failure modes were searched and analyzed through the ten year maintenance information. The structured defects such as the air compressor, the lubricating oil pressure, and the insufficient load were the root causes of main failures. The air reservoir reinstallation, the lubricating oil tube modification, the load bank installation, and the qualitative instrumentation were the solutions for the hardware oriented RCM of DGs. There remains the software oriented RCM such as the rejection of useless maintenance, the preventive maintenance, the database of maintenance information, and the predictive maintenance.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2006.06a
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• pp.93-98
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• 2006

Warm forming technology was classified into hot gas forming of using compressible fluid as a nitrogen gas and warm hydroforming of using the incompressible fluid as a thermal oil by using medium fluid. In this study, the aluminum side-rail part was developed with warm hydroforming technology. For the warm hydroforming system, top and bottom die was designed to insert heating cartridge in die cavity and special indirect fluid heating system was designed to heat the thermal oil. As increase the temperature, hydroformability was increased linearly. Aluminum side-rail center part was formed 90% at the internal pressure of 100bar and perfectly formed at 300bar within a moderate temperature. The tube material used for warm hydroforming was a aluminum 6000 series alloy with the diameter of 120mm, thickness of 5mm, length of 1,300mm. Warm hydroformed side-rail center part had 20% of maximum expansion ratio and below 20% of maximum thinning ratio at corner radius. This results were provided to show warm hydroforming possibility for aluminum automotive components.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.436-439
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• 2008

This paper is to research the heat transfer performance of the sintered pipe. Recently, oil prices is to be 127 $ per barrel, we expect higher costs this summer. We promote alternative fuels, after oil and gasoline prices reached record highs. The governments have made efforts to avoid future crisis by continuing the move toward renewable energy and energy saving. In this paper, we have fabricated a sintered pipe, the heat transfer performance of sintered pipe is achieved experimentally. The pipe is copper tube of outer diameter of 15.88 mm, the length of the pipe is 800 mm. Based on the experimental results, it is shown the overall heat transfer coefficient of sintered pipe is increased as compared with that of a straight pipe, is equal as compared with that of a spiral pipe. The overall heat transfer coefficient was $0.075{\sim}0.09\;kW/^{\circ}C$

• Journal of Advanced Marine Engineering and Technology
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• v.28 no.3
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• pp.500-508
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• 2004

The heat transfer coefficients during gas cooling process of carbon dioxide in a horizontal tube were investigated. The experiments are conducted without oil in the refrigerant loop. The main components of the refrigerant loop are a receiver, a variable-speed pump, a mass flow meter, a pre-heater, and a gas cooler(test section). The water loop consists of a variable-speed pump, an isothermal tank, and a flow meter. The gas cooler is a counterflow heat exchanger by cooled water flowing in the annulus. The $CO_2$ flows in the horizontal stainless steel tube. which is 9.53mm in O.D. and 7.75mm in I.D. The gas cooler is 6 [m] in length. which is divided into 12 subsections, respectively. The experimental conditions considered in the study are following range of variables : refrigerant temperature is between 20 and $100^{\circ}C$. mass fluxes ranged from 200 to 400kg/($m^2$.s), average pressure varied from 7.5 to 10.0MPa. The main results were summarized as follows : The friction factors of $CO_2$ in the gas cooler show a relatively good agreement with those predicted by Blasius' correlation. The local heat transfer coefficient in the gas cooler has compared with most of correlations, which are the famous ones for forced convection heat transfer of turbulent flow. The results show that the local heat transfer coefficient of gas cooler agrees well with the correlation by Bringer-Smith except that at the region near pseudo critical temperature. while that at the near pseudo critical temperature is higher than the correlation.

• Journal of Advanced Marine Engineering and Technology
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• v.28 no.1
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• pp.65-74
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• 2004

The heat transfer coefficient and pressure drop of $CO_2$(R-744) during gas cooling Process of carbon dioxide in a horizontal tube were investigated experimentally and theoretically. The experiments were conducted without oil in the refrigerant loop. The main components of the refrigerant loop consist of a receiver. a variable-speed pump. a mass flowmeter, an evaporator. and a gas cooler(test section). The main components of the water loop consist of a variable-speed Pump. an constant temperature bath. and a flowmeter. The gas cooler is a counterflow heat exchanger with refrigerant flowing in the inner tube and water flowing in the annulus The test section consists of smooth, horizontal stainless steel tube of 9.53 mm outer diameter and 7.75 mm inner diameter. The length of test section is 6 m. The refrigerant mass fluxes were 200 ~ 300 kg/($m^2{\cdot}s$) and the inlet pressure of the gas cooler varied from 7.5 MPa to 8.5 MPa. The main results were summarized as follows : The predicted correlation can evaluated the R-744 exit temperature from the gas cooler within ${\pm}10%$ for most of the experimental data, given only the inlet conditions. The predicted gas cooley capacity using log mean temperature difference showed relatively food agreement with gas cooler capacity within ${\pm}5%$. The pressure drop predicted by Blasius estimated the pressure drop on the $CO_2$ side within ${\pm}4.3%$. The predicted heat transfer coefficients using Gnielinski's correlation evaluated the heat transfer coefficients on the $CO_2$ side well within the range of experimental error. The predicted heat transfer coefficients using Gao and Honda's correlation estimated the heat transfer coefficients on the coolant side well within ${\pm}10\;%$. Therefore. The predicted equation's usefulness is demonstrated by analyzing data obtained in experiments.

• Korean Journal of Veterinary Research
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• v.55 no.4
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• pp.253-257
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• 2015

Oregano (Origanum vulgare) is an aromatic herb belonging to the Lamiaceae family. This study evaluated the therapeutic effect of oregano essential oil (OEO) on clinical bovine mastitis caused by Staphylococcus (S.) aureus and/or Escherichia (E.) coli. Thirty-two quarters from 18 lactating cows with subclinical mastitis were selected from a dairy farm and were divided into 4 groups (8 quarters/group): negative control (CON), positive control (GEN) and two OEO-treated groups (OEO-1 and OEO-2). Each group was intramammarily treated with saline, 10 g/tube of gentamicin ointment, and single and double doses of 0.9 mL OEO ointment twice a day for three days, respectively. After the treatments, physical udder conditions were greatly improved in GEN and OEO groups. In CON group, somatic cell counts (SCCs), number of white blood cells (WBC) and bacteria were increased. However, in OEO groups, SCCs and number of WBC were significantly decreased and S. aureus and E. coli were not detected in milk as compared with those before the treatments as well as GEN group. These results suggest that OEO may be a useful alternative to antibiotics for the control of subclinical bovine mastitis caused by S. aureus and/or E. coli.

• Journal of Nutrition and Health
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• v.19 no.4
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• pp.255-265
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• 1986

This study was designed to investigate the effect of age on the lipid metabolism in the rats fed different diets. In experiment A male Wistar rats of 5 weeks of age and of 32 weeks of age were divided into low fat diet groups and high fat-cholesterol groups. The rats were sacrificed 1 week, 2 weeks and 4 weeks after experiment begins. Also after 4 weeks. the rats in low and high fat diet groups were tube-fed 500mg of choelsterol and were sacrified 3 days later. In experiment b, male Wistar rats of 4 weeks of age and of 6 months of age were divided into 2 groups of butter and cron oil groups. And then eachgroup were divided into 2 subgroups ; meal feeding and nibbling groups . Each diet was fed for 4 weeks. In experiment A, age of the rats and experimental diets did not affect the serum cholesterol and triglycerides concentrations were higher in rats fed high fat cholesterol diet than in those fed low-fat or high -fat diets, but age of the animals had no effect on liver lipid content. The weight and cholesterol content of epidymal fat pad, however were higher in adult rats than in young ones regardless of the diets fed. When the rats were challenged with 500mg cholesterol, the rates of increase in serum and hepatic cholesterol level were higher in adult rats compared to young rats regardless of the diets . On the other hand, the rate of increase of small intestinal cholesterol content was lower in adult rats than in young rats. In experiment B, serum cholesterol and triglyceride content were relatively higher in young rats than adult ones. Stored body lipid was higher in adult rats, as judged by epididymal fat pad weight and total carcass lipid. Meal frequency and the kinds of fat in the diet did not affect the serum choelstero concentration . The serum triglyceride levels. however, was higher in butter fed rats thancron oil fed ones. The cholesterol content of live rand epididymal fat pad was lower in butter fed groups than corn oil groups for both young and adult rats, but there was no difference in liver triglycerides livel.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.22 no.1
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• pp.131-137
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• 2013

Gas springs have been widely used in motor vehicles as well as in most areas of industry. Instead of coil springs, these gas springs are easily operated to extrusion process or compression process the doors because $N_2$ gas with high pressure and oil are charged in tube. Gas spring sustain the constant elasticity change rate in the high reaction force and long stroke, and they have compact design, appearance and an excellent assembling ability to be mounted easily with any applicatory products. By means of these aspects, gas springs have been widely used in stead of coil springs in the over all industries. In this study, using acommonly used program, ANSYS, the basic research about the heat transfer and equivalent stress change of bimetal.