• 한국지리정보학회지
• /
• 제7권4호
• /
• pp.88-97
• /
• 2004

본 연구에서는 원격탐사나 지리정보시스템 등을 적용하여 ASCII형태의 수치표고자료와 원격탐사 자료를 이용하여 분류한 토지피복도를 이용하여 각 토지피복별로 알베도와 바로크계수, 증발효율 등을 이용할 수 있는 격자형 토지피복자료를 격자단위로 분할하여 모형의 입력값으로 이용하였기 때문에 유역의 공간적인 특성을 반영한 보다 정확하고 신뢰성있는 자료의 구축이 가능했고, 기존의 열수지법을 이용하여 증발산량의 시 공간적인 분포양상을 계산할 수 있는 격자기반의 분포형 증발산량 추정 프로그램을 포트란언어로 개발하였으며, 격자형 증발산량 산정 모형은 향후 연구될 격자기반의 분포형 강우-유출모형과 통합할 수 있도록 고려하였다. 또한, 격자기반의 계산으로 증발산량에 대한 유역내 특정지점에서의 시간적 변화 양상과 공간적 분포 양상을 GIS상에서 나타낼 수 있도록 구성하였다. 모형의 적용성 검증을 위해서 비교적 정확한 기상자료와 수문자료를 보유하고 있는 일본의 쇼나이강 유역($532km^2$)을 대상으로 적용한 결과, 유역 연평균 증발산량은 825.4mm로 나타났다.

• 한국수소및신에너지학회논문집
• /
• 제23권4호
• /
• pp.300-309
• /
• 2012

Long endurance is a key issue in the application of unmanned aerial vehicles. This study presents feasibility test results when fuel cell system as an alternative to the conventional engine is applied for the power of the UAV after the 150W fuel cell system is developed and packaged to the 1/4 scale super cub airplane. Fuel cell system is operated by dead-end method in the anode part and periodically purged to remove the water droplet in flow field during the operation. Oxygen in the air is supplied to the stack by the two air blowers. And fuel cell stack is water cooled by cooling circuit to dissipate the heat generated during the fuel cell operation. Weight balance is considered to integrate the stack and balance of plant (BOP) in package layout. In flight performance test, we demonstrated 4 times standalone take-off and landing. In the laboratory test simulating the flight condition to quantify the energy flow, the system is analyzed in detail. Sankey diagram shows that electric efficiency of the fuel cell system is 39.2%, heat loss 50.1%, parasitic loss 8.96%, and unreacted purged gas 1.67%, respectively compared to the total hydrogen input energy. Feasibility test results show that fuel cell system is high efficient and appropriate for the power of UAV.

• 한국조경학회지
• /
• 제40권1호
• /
• pp.1-11
• /
• 2012

이 연구는 인간 에너지 균형 모델에서 출발한 인간 열환경 지수 분석 방법을 이용하여 캐나다 BC주에 있는 나나이모시 상업지구안 좁은 길과 경상남도 창원시 중심상업지구에 있는 소공원을 연구 대상지로 2009년 여름철 열환경을 분석한 것이다. 기후 입력 자료는 기온, 상대습도, 풍속, 태양 및 지구 복사에너지이었으며, 그 결과 인간 열환경 지수에 가장 크게 영향을 미치는 요소들은 태양 직사광선, 건물시계지수 그리고 풍속이었다. 음지는 약간 더운 정도의 열환경을 조성하는 것으로 나타나 매우 덥게 나타난 양지에 비해 훨씬 좋은 열환경을 조성하는 것으로 나타났다. 나나이모 연구 대상지에 있는 좁은 길들은 주변의 넓은 장소들에 비해 주변 건축물에서 나오는 태양 반사광선과 지구 복사에너지들이 더 많이 영향을 미쳐 훨씬 덥게 나타났다. 낮은 풍속에 의해서 인체에서 방출되는 현열과 잠열의 양이 현저히 줄어듦으로서 더 더운 열환경이 조성되는 것으로 나타났다. 기후요소를 조경에 접목하기 위해서, 인간 열환경 지수 분석 방법을 이용하는 것은 열환경적으로 쾌적한 옥외 공간조성에 영향을 미칠 것이며, 도시 열섬 완화와 기후변화 연구에도 잘 이용될 수 있을 것이다.

• 대한한방내과학회지
• /
• 제23권2호
• /
• pp.292-297
• /
• 2002

Fire is known as one of the most common causes of stroke. Chest fever with dysphoria caused by heat in the stomach is one of the fire symptoms, meaning feeling oppressed in the chest. We observed two stroke patients who had chest fever with dysphoria. These patients' clinical symptoms were headache, thirst, heat in the upper part of the body and constipation. They were diagnosed as Chest fever with dysphoria. It is assumed that Exuberance of Yang causes heat. We treated them with Yangkyuksanhoa-tang(凉膈散火湯) based on Dong Ui Su Se Bo Won for about 2 weeks. During this period, we observed that their symptoms of heat in the upper part of the body and constipation had been improved. We suggest that Yangkyuksanhoa-tang makes the balance between water and fire, and improves chest fever with dysphoria of stroke patients.

• 에너지공학
• /
• 제10권4호
• /
• pp.349-356
• /
• 2001

물과 증기의 직접접촉에 의한 응축 열전달은 움직이는 증기/물 경계면에서 열 및 물질 전달이 이루어지는 현상으로서, 매우 큰 열전달계수를 수반하는 특징이 있기 때문에 이를 응용한 설계가 산업계에서 광범위하게 이루어지고 있다. 본 연구에서는 단일 수평 배관을 통해 과냉각수가 있는 응축탱크로 안정된 증기제트가 방출될 때, 증기제트 형상을 예측하는 간단한 응축해석모델을 제시하였다. 해석모델은 축대칭 좌표계에서 질량, 운동량 및 에너지 방정식과 증기/물 경계면에서 의 응축 특성을 고려한 열평형 방정식을 사용하여 유도하였다. 증기/물 경계에서의 매우 큰 열전달율은 기존의 실험을 근거로 한 유효열전도계수에 의해 반영되었다. 해석결과는 실험결과와 비교하였고, 제시된 해석 모델은 실험에서 관찰된 바와 같이 증기 질량유속과 수조 온도가 증가할수록 증기제트 크기(반경 및 길이)가 증가하는 경향을 보였다.

• 한국농업기계학회:학술대회논문집
• /
• 한국농업기계학회 1993년도 Proceedings of International Conference for Agricultural Machinery and Process Engineering
• /
• pp.443-452
• /
• 1993

Direct freezing tests of soybean seed by liquid nitrogen were carried out at various moisture contents and the following important conclusions were drawn from the results of temperature measurements of soybean seed and photographs of bubbles generated on its surface : 1) Assuming that the temperature gradient in a soybean seed is negligible because of its small seed size and the freezing ratio is followed the Heiss's formula, and a differential equation based on the heat energy balance was introduced . The equation was easily solved by the Runge-Kutta-Gill method and the predicted values of the temperature were in good agreement with the observed data. 2) The photographs of bubble generation during freezing showed the boiling mode was nucleate, and then the most suitable formula on the nucleate boiling heat transfer was introduced from many formulate proposed up to now by fitting the calculated values based on the formula to the observed data. The formula used for the predict on of the seed temperature was as follows: $\frac{{\partial}T_s}{\partial\theta}\;=\;-\frac{{\alpha}(T_s\;-\;T_L)^{3.3}}{W(C_s\;-\;\frac{{\delta}m(CT_s\;+\;{\sigma})}{T_s^2})}$ where C = difference of the specific heat between pure ice and water m=moisture content of soybean seed $T_s$ = seed temperature $T_L$ = Temperature of liquid nitrogen W = mass of soybean seed $\alpha$ = proportional constant $\delta$ = constant depends on variety or the type of seed $\theta$ = time $\sigma$ = latent heat of melting of pure ice This study will give important information in the hydro-freezing technique by liquid nitrogen, available as a new technique of processing agricultural products in the near future.

• 한국수소및신에너지학회논문집
• /
• 제33권4호
• /
• pp.419-429
• /
• 2022

Effects of operating variables on temperature profile and performance of 3 MWth chemical looping combustion system were estimated by mass and energy balance analysis based on configuration and dimension of the system determined by design tool. Air reactor gas velocity, fuel reactor gas velocity, solid circulation rate, and solid input percentage to fluidized bed heat exchanger were considered as representative operating variables. Overall heat output and oxygen concentration in the exhaust gas from the air reactor increased but temperature difference decreased as air reactor gas velocity increased. Overall heat output, required solid circulation rate, and temperature difference increased as fuel reactor gas velocity increased. However, overall heat output and temperature difference decreased as solid circulation rate increased. Temperature difference decreased as solid circulation rate through the fluidized bed heat exchanger increased. Effect of each variables on temperature profile and performance can be determined and these results will be helpful to determine operating range of each variable.

• 한국신뢰성학회지:신뢰성응용연구
• /
• 제13권1호
• /
• pp.11-18
• /
• 2013

For a reliability assessment of machinery parts, accurate performance test, environmental test, life test, etc. are required on the sample. In the performance test conditions of various machinery parts, some problems happen such as needs to rise temperature rapidly with large flow of oil having very low thermal conductivity and to measure very high torque or tiny torque, etc. This study brings out the method to apply heat to rise temperature for large flow of oil without chemical change in a performance test of oil cooler. To measure large scale of torque in a performance test of planetary gearbox of excavator, the method of torque measurement is proposed by replacing the large torque meter priced very expensive. To measure very small torque on lubricated friction, a methode of force balance type test mechanism is introduced for tests of piston assembly.

• Nuclear Engineering and Technology
• /
• 제40권7호
• /
• pp.581-592
• /
• 2008

In this study, a conceptual pyroprocess flowsheet has been devised by combining several dry-type unit processes; its applicability as an alternative fuel cycle technology was analyzed. A key point in the evaluation of its applicability to the fuel cycle was the recovery yield of fissile materials from spent fuels as well as the proliferation resistance of the process. The recovery yields of uranium and transuranic elements (TRU) were obtained from a material balance for every unit process composing the whole pyroprocess. The material balances for several elemental groups of interest such as uranium, TRU, rare earth, gaseous fission products, and heat generating elements were calculated on the basis of the knowledge base that is available from domestic and foreign experimental results or technical information presented in open literature. The calculated result of the material balance revealed that uranium and TRU could be recovered at 98.0% and 97.0%, respectively, from a typical PWR spent fuel. Furthermore, the anticipated TRU product was found to emit a non-negligible level of $\gamma$-ray and a significantly higher level of neutrons compared to that of a typical plutonium product obtained from the PUREX process. The results indicate that the product from this conceptual pyroprocessing should be handled in a shielded cell and that this will contribute favorably to retaining proliferation resistance.

• 한국수소및신에너지학회논문집
• /
• 제21권5호
• /
• pp.405-411
• /
• 2010

A 5kW class SOFC cogeneration system consisted of a hot box part, a cold BOP (balance of plant) part, and a hot water reservoir. The hot box part contained a stack, a fuel reformer, a catalytic combustor, and heat exchangers. A cold BOP part was composed of blowers, pumps, a water trap, and system control units. A 5kW stack was designed to integrate 2 sub-modules. In this paper, the 5kW class SOFC system was operated using 2 short stacks connected in parallel to test the sub-module and the system. A short stack had 15 cells with $15{\times}15 cm^2$ area. When a natural gas was used, the total power was about 1.38 kW at 120A. Because the sub-modules were connected in parallel and current was loaded using a DC load, voltages of sub-modules were same and the currents were distributed according to the resistance of sub-modules. The voltage of the first stack was 11.46 V at 61A and the voltage of the second stack was 11.49V at 59A.