• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1999.05a
• /
• pp.45-48
• /
• 1999

Monolayers of lipids on a water surface have attracted much interest as models of biological membranes, but also as precursors of multilayer systems promising many technical applications. Until now, many methodologies have been developed in order to gain a better underst. DMPC molecules have one phosphatidylcholine head group and two long alkyl groups with carbonyl group. Displacement currents generated during the compression of monolayers of DMPC on the surface of water were investigated. As results, the displacement pick was generated when the area per molecule was about 190$\AA$$^2$in low pressure, and it was generated when the area per molecule about 190$\AA$$^2$ in for pressure, and it was generated when the area per molecule about 150 $\AA$$^2$ in high pressure. Also. for the study of photo device measured the absorption rate. the maxim value shown was 2800-2900nm.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2017.05a
• /
• pp.9-13
• /
• 2017

본 연구에서는 실내실험을 통하여 보의 경사변화에 따른 흐름특성과 보 상류에서 유사의 퇴적과정을 정량적으로 분석하고, 보 하류에서 세굴 및 지형변화 과정을 분석하였다. 보의 설치각도가 커질수록 보에 의항 굴절되는 유선의 각도가 증가하며, 하류에서 수충부가 형성되고 사수역의 크기가 증가한다. 즉, 보의 길이 대 수로 폭의 비로 정의되는 무차원 수로폭이 증가할수록 무차원 유효길이는 감소하였다. 보 상류에서는 보에 의하여 형성된 배수의 영향이 끝나는 지점에서 delta가 형성되며, 보 하류에서는 흐름이 집중되어 보 직하류 하상은 세굴되고 반대쪽에서는 이동성이 없는 교호사주가 형성되었다. 또한 충부에서는 깊게 세굴되었으며, 보의 설치 각도가 커질수록 수충부가 집중되면서 깊게 세굴되고, 세굴범위는 좁게 나타났다. 무차원 하상고가 증가할수록 유속과 delta의 이동속도의 비인 무차원 속도는 감소하며, 무차원 보의 길이가 증가함에 따라, 무차원 사주의 파장이 감소하였다. 무차원 보의 길이가 증가함에 따라 보에 의하여 굴절되는 흐름의 각이 크므로, 흐름이 집중되어 하상이 깊게 세굴되고 무차원 사주의 파고가 증가하였다.

• Journal of ILASS-Korea
• /
• v.24 no.1
• /
• pp.1-7
• /
• 2019

This study was carried out to analyze the spray characteristics as a function of the operating parameters of urea injector used in Urea-SCR system of passenger diesel vehicle. Spray visualization and PDPA experiment were performed to analyze the macroscopic spray development and atomization performance of urea-water-solution. For the urea injector, the deformation of the spray head does not appear to be significant because it operates at a low pressure conditions, and the liquid core and primary droplet are observed throughout the operating conditions. No increase in atomization is seen when the operating pressure is increased, and the spray develops linearly due to poor atomization characteristics. The macroscopic spray behavior of the low-pressure urea injector is predictable through the modification of the Hiroyasu equation.

• International Journal of Naval Architecture and Ocean Engineering
• /
• v.10 no.5
• /
• pp.651-659
• /
• 2018

A multi-level overtopping wave energy converter was designed according to the large tidal range and small wave heights in China. It consists of two reservoirs with sloping walls at different levels. The reservoirs share a common outflow duct and a low-head axial turbine. The experimental study was carried out in a laboratory wave-flume to investigate the overtopping performance of the device. The depth-gauges were used to measure the variation of the water level in the reservoirs. The data was processed to derive the time-averaged overtopping discharges. It was found that the lower reservoir can store wave waters at the low water level and break the waves which try to climb up to the upper reservoir. The upper sloping angle and the opening width of the lower reservoir both have significant effects on the overtopping discharges, which can provide more information to the design and optimization of this type of device.

• Journal of Ginseng Research
• /
• v.22 no.1
• /
• pp.66-72
• /
• 1998

Studies were performed to determine the effect of Korean red ginseng (extract powder, spray-dried), it is made of choice 6-year-old raw ginseng roots, and processed by steaming and drying, on jejunal crypt survival, endogenous spleen colony formation, and apoptosis in jejunal crypt cells of irradiated mice. Jejunal crypts were protected by pretreatment of red ginseng (1 mg/head, single I.P. at 24hours before irradiation, p<0.05). Red ginseng administration before irradiation (1 mg/head, single I.P at 24hours before irradiation) resulted in an increase of the formation of endogenous spleen colony (p<0.05). The frequency of radiation-Induced apoptosis in intestinal crypt cells was also reduced by treatment of red ginseng both pretreatment (P.O.: 2 mg/ml of drinking water for 7 days, p<0.005, I.P.: 1 mg/head, single I.P. at 24 hours before irradiation, p<0.005) and post-treatment (1 mg/head, single I.P at 30 minutes after irradiation, p<0.05). These results indicated that Korean red ginseng might be a useful radio-protector, especially since it is a relatively nontoxic natural product. Further studies are needed to characterize better the promotion nature of red ginseng and its fractions.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.36 no.1
• /
• pp.1-11
• /
• 2000

A low frequency, high power hydroacoustic transducer with 7 tonpilz piston elements assembled in a circular array suitable for marine application, such as the transmission of underwater information and the development of new fisheries resources in the deep sea zone was designed. A modified Mason's model was applied to monitor and to simulate the transducer behavior at each step during the fabrication. The in air, and in water constructed tonpilz transducer was tested experimentally and numerically by changing the size and the type of the material for head, tail and acoustic window. Also, the developed transducer was excited by pulse signals and the received waveform was analyzed. The resonance peaks in the transmitting voltage response(TVR) of a single tonpilz element without housing were observed at 11.33kHz in air and 10.93kHz in air and 10.93 kHz in water, respectively, with the overall electrical-acoustic efficiency of 43.7%. The value of TVR of single tonpilz element with aluminum housing in water was 129.87dB re 1 $\mu$Pa/V at 12.25 kHz with the frequency bandwith of 2.15 kHz and half beam angle of 30.2$^{\circ}$at -3dB.The resonance peaks in the transmitting voltage response of the 7 element circular transducer were observed at 11.50 kHz in air and 11.45 kHz in water, respectively. The value of TVR in water 144.84 dB re 1$\mu$Pa/V at 11.5kHz with the frequency bandwith of 4.25 kHz and the half beam angle of $22.3^{\circ} $ at -3dB.Reasonable agreement between the experimental measurements and the theoretical predictions for the directivity patterns, TVRs and the impedance characteristics of the designed transducer was achieved.

• The KSFM Journal of Fluid Machinery
• /
• v.15 no.6
• /
• pp.25-30
• /
• 2012

Renewable energy has been interested because of fluctuation of oil price, depletion of fossil fuel resources and environmental impact. Amongst renewable energy resources, hydropower is most reliable and cost effective way. In this study, to develop a new type of micro hydro turbine which can be operated in the range of very low specific speed, a cross-flow hydro turbine with simple structure is proposed. The turbine is designed to be used at the very low specific speed range of hydropower resources, such as very high-head and considerably small-flow rate water resources. CFD analysis on the performance and internal flow characteristics of the turbine is conducted to obtain a practical data for the new design method of the turbine. Results show that optimized arrangement of guide vane angle and inner guide angle can give contribution to the turbine performance improvement.

• Journal of the Korea Institute of Building Construction
• /
• v.4 no.1
• /
• pp.97-103
• /
• 2004

In case of a fire in road or railway tunnel it is always necessary to keep the escape condition as good as possible. Most of the victims of major fires in tunnels are because they couldn't leave the tunnel in time and were trapped by smoke, or rescue teams couldn't reach the place of the accident due to low visibility and high temperature. In spring 2003 a comprehensive field experiment was undertaken in a large scaled tunnel in Youngin City to test the effectiveness of a new water spray curtain system, designed to the air qualify inside of a tunnel in case of fire during passenger's escape to safe routes, In order to control the smoke propagation, fixed water sprayed nozzles were used to make water curtain system, which can be installed or hanging water piping line below ceiling. The experiment was accompanied by an extensive measurement campaign in order to measure temperature dropping effect and flow conditions as well as CO concentration for various water sprayed curtains produced by sprinkler heads or water spray nozzle. Eventually comparison analysis were undertaken to investigate the performance of water curtains under fixed water pressure. Therefore most effective water curtain system was presented on the basis of water droplet size in long tunnel.

• Journal of Advanced Marine Engineering and Technology
• /
• v.32 no.7
• /
• pp.1044-1050
• /
• 2008

Most of developed countries, the consumption of fossil fuels has been serious problems that cause serious environment pollution like acid rain, global warming. Also, we have faced that limitation fossil fuels will be exhausted. Currently, small hydropower attracts attention because of its small, clean, renewable, and abundant energy resources to develop. By using a small hydropower generator of which main concept is based on using the different water pressure levels in pipe lines, energy which was initially wasted by use of a reducing valve at the end of the pipeline, is collected by turbine in the hydropower generator. A propeller shaped hydroturbine has been used in order to use this renewable pressure energy. In this study, in order to acquire basic design data of tubular type hydraulic turbine, output power, head, efficiency characteristics due to the flow coefficient are examined in detail. Tubular-turbine among small hydraulic power generation can be used at low-head. The purpose of this study is to research turbine's efficiency due to runner vane angle using CFD analysis.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2006.05a
• /
• pp.288-293
• /
• 2006

The combustion performances and characteristics of the subscale liquid rocket combustion chamber are discussed in this paper. Subscale combustion chamber is composed of mixing head, ablative cooling cylinder, and water cooling nozzle. The mixing head has eighteen coaxial swirl injectors and one center coaxial swirl injector for ignition. The mixing heads employing the injectors of low different recess length are considered in this paper. The results of the firing test, comparison of performance, and characteristics of static and dynamic pressures of the four different mixing heads are described. The characteristics of combustion at design and of design points are also discussed.