• 한국습지학회지
• /
• 제10권1호
• /
• pp.21-30
• /
• 2008

증발산은 지표와 대기 사이에서 일어나는 에너지 상호작용에 기여하는 중요한 요소 중 하나이다. 갈대로 덮인 고흥만 간척지에서 현열, 토양열 그리고 순복사를 측정하여 증발산량을 조사하였다. 자동기상관측 자료로부터 산출된 증발산량은 구름과 바람의 연직경도가 $1s^{-1}$보다 미약한 경우를 제외하고 열수지 방정식으로 추정한 값과 잘 일치하였다. 토양열은 순복사의 약 10%로 평가되었다. 갈대로 구성된 식생캐노피 내에서 온도에 따른 포화수증기압의 변화율($${\Delta}{\sim_=}de_s/dT$$)이 약 1.5로 근사되었고, 증발산량은 순복사 에너지의 함수로 설명될 수 있다.

• 한국의류산업학회지
• /
• 제4권6호
• /
• pp.564-566
• /
• 2002

Protective clothing for firefighters typically consists of a flame resistant outer shell and inner layers. The inner layers are generally composed of a moisture barrier and a thermal barrier. On performing the task in fire place the heat and perspiration generated from the body become trapped inside the protective clothing. Those heat and moisture result into heat-stress and physical fatigue of fire fighter, which hinder the work. Therefore, the system of clothing designs and material layers must be chosen carefully to balance protection and comfort. 3 kinds of protective clothing of 3 layer structure were used in the experiment of physiological comfort. From the comparison of wear trials with the 3 kinds of layers in firefighters clothing, it indicates that the moisture dissipation of A+B2+C was highest, following A+BI+C andA+B3+C. And the heat dissipation of A+BI+C and A+B2+C were better than A+B3+C. In the protective clothing with A+B3+C, heat and perspiration generated through exercise remained in clothing system long and caused discomfort.

• 대한기계학회논문집B
• /
• 제31권10호
• /
• pp.823-831
• /
• 2007

This paper presents the experimental and simulation study of a loop heat pipe (LHP) that can be applied to present electronics, space missions and thermal control systems. The present experimental study was carried out employing sintered alumina ceramic wick ($d=2.96\;{\mu}m$, ${\phi}=0.61$). High purity R-134a, R-22 and water were also used as alternative working fluids in addition to ammonia. The experimental study showed that the maximum heat transfer performance for the test LHP in the vertical top heating mode was over 100 Watts when ammonia was used as the working fluid. The simulation results have been compared with the experimental results to validate a simulation model based on the thermal resistance network that was developed to evaluate the performance of LHPs, focusing on their prospective applications in electronics. The simulation model is based on the loop overall energy, mass, and momentum balance. The simulation program can predict the effects of various parameters which affect the performance of LHP within 5% compared with the experimental results.

• 한국신재생에너지학회:학술대회논문집
• /
• 한국신재생에너지학회 2008년도 추계학술대회 논문집
• /
• pp.21-24
• /
• 2008

We have developed a $kW_e$ class liquid fuel based solid oxide fuel cell (SOFC) system. Our final target is to develop the 1 $kW_e$ diesel based SOFC system for residential power generator(RPG). In this study, we present the conceptual design of SOFC system. System is composed of hot-box and cold-box. Planar typed SOFC stack, heat exchanger, combustor for stack tail gas, and fuel processor, such as fuel reformer and desulfurizer, are contained in the hot-box. And several balance of plants(BOP), such as fuel suppliers and controller, are contained in the cold-box. Before the SOFC system fabrication, we have already operated the selfsustaining fuel processor, and heat exchange of all heat-related components is simulated using ASPEN HYSYS, because heat maintenance and management in hot-box are important for stable operation of SOFC system. The self-sustained fuel processor was successfully operated for about 250 hours, and heat exchange is enough to operate the SOFC system.

• 대한설비공학회지:설비저널
• /
• 제17권4호
• /
• pp.408-417
• /
• 1988

This study optimized the condenser dimension of heat pump system with the heat sources which are solar irradiation and ambient air. At first, the author selected the principal design factors influencing the performance of heat pump system. And the author considered the variation of condenser dimension according to the variation of the selected design factors, that is, ambient air temperature, condenser temperature, degree of superheating, degree of sub-cooling and irradiation. As a result this study, among refrigerants R12, R22 and R500, refrigerant R22 has more heating output than R12 and R500, and the coefficient of performance on this heat pump system is not greatly influenced by the degree of superheating and degree of sub cooling. The ambient air temperature is below $5^{\circ}C$ at balance point and the optimal tube length of condenser dimension is about 3.8 m. Also the author gained the optimal design diagram for the optimization of condenser dimension according to various design factors.

• 열처리공학회지
• /
• 제32권4호
• /
• pp.161-167
• /
• 2019

Impact toughness and fracture behavior were studied in five kinds of non-heat treating steels containing bainite; standard(0.25C-1.5Mn-0.5Cr-0.2Mo-0.15V), high V(0.3V), Ni(0.5Mn-2Ni), W(0.4W instead of Mo), and high C-Ni(0.35C-0.5Mn-2Ni) steels. The good hardness and impact toughness balance was exhibited in the $1100^{\circ}C$-rolled condition, while the impact toughness was deteriorated due to coarse grained microstructure in the $1200^{\circ}C$-rolled condition. The impact toughness decreased with increasing the hardness in all steels studied. The fracture behavior was also basically identical, that is, the fracture area was divided into 3 zones; shear and fibrous zone, fracture transition zone with ductile dimples and cleavage cracks, where the cracks initiate and grow to critical size, unstable cleavage fracture propagation zone. The energy absorbed for the critical crack formation through the plastic deformation inside the plastic zone in front of the notch root contributed to a mostly significant portion of the total impact energy.

• 한국지열·수열에너지학회논문집
• /
• 제15권3호
• /
• pp.14-20
• /
• 2019

In this study, the technologies and regulations for distributing standing column well(SCW) ground source heat pump systems to the residential cluster homes were investigated. They have only been installed in the public or commercial building having different load pattern and site structure compared with the residential cluster homes. Some of SCWs for the residential cluster homes should be installed under the basement due to a lack of site area. There are pressure differences between the SCWs installed under ground surface and basement. It is needed to develop the technology or devices to prevent overflow caused by pressure difference among the SCWs. In addition, heat balance algorithm between SCWs should be adopted to maximize the system efficiency. A heat pump having heating, cooling, hot water, heating-hot water, and cooling-hot water modes should be developed for adopting an individual air-conditioning system to the residential cluster homes.

• 대한원격탐사학회:학술대회논문집
• /
• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume II
• /
• pp.752-755
• /
• 2006

Evaportranspiration is an important factor in hydrology cycle. Traditionally, it is measured by using basin or empirical formula with meteorology data, while it does not represent the evaportranspiration over a regional area. With the advent of improved remote sensing technology, it becomes a surface parameter of research interest in the field of remote sensing. Airborne and satellite imagery are utilized in this study. The high resolution airborne images include visible, near infrared, and thermal infrared bands and the satellite images are acquired by MODIS. Surface heat fluxes such as latent heat flux and sensible heat flux are estimate by using airborne and satellite images with surface meteorological measurements. We develop a new method to estimate the evaportranspiration over the rice paddy. The surface heat fluxes are initialized with a surface energy balance concept and iterated for convergent solution with atmospheric correct functions associated with aerodynamic resistance of heat transport. Furthermore, we redistribute the total net energy into sensible heat and latent heat fluxes. The result reveals that radiation and evaporation controlled extremes can be properly decided with both airborne and satellite images. The correlation coefficient of latent heat flux and sensible heat flux with corresponding in situ observations are 0.66 and 0.76, respectively. The relative root mean squared errors (RMSEs) for latent heat flux and sensible heat flux are 97.81 $(W/m^2)$ and 124.33 $(W/m^2)$, respectively. It is also shown that the newly developed retrieval scheme performs well when it is tested by using MODIS date.

• 대한기계학회논문집B
• /
• 제25권2호
• /
• pp.216-224
• /
• 2001

Experiments have been performed to investigate evaporative heat transfer characteristics of R-134a flowing in a small diameter tube. Test section was made of stainless steel tube with an inner diameter of 2.2mm and was uniformly heated by electric current which was applied to the tube wall. The local saturation temperature of refrigerant flowing in a tube is calculated from the measured local saturation pressure by using an equation of state. Inner wall temperature was calculated from measured outer wall temperature, accounting for heat generation in the tube and one dimensional heat conduction through the tube wall. Mass quality of refrigerant flowing in a tube was calculated by considering energy balance in the pre-heater and the test section. Heat flux was varied from 19 to 64kW/$m^2$, and mass flux was chanted from 380 to 570kg/$m^2$s for each heat flux condition. From this study, heat transfer in a small diameter tube is affected by heat flux as well as mass flux for a wide range of mass quality. Heat transfer coefficient in a small diameter tube is much greater than that in medium sized tubes. Test results in this study are compared with Gungor and Winterton correlation, which gives an absolute average deviation of 27%.

• 대한한의학원전학회지
• /
• 제34권2호
• /
• pp.225-240
• /
• 2021

Objectives : The purpose of this paper is to examine Zhang Zihe's reinforcement method based on the theory of keeping balance(以平爲期). Methods : Based on his arguments in the Rumenshiqin and formula compositions, Zhang Zihe's reinforcement method was examined. Results & Conclusions : 1. Despite preconceptions that Zhang Zihe must have been critical of reinforcement methods due to his alliance to the offensive purgative group, in reality his criticism was not aimed at reinforcement methods entirely, but rather at warming and tonifying. 2. Zhang Zihe's criticism of warming and tonifying was based on his research of the Neijing, in which he realized the pathogenic effects of fire-heat and the side effects of warming and tonifying in clinical practice. This is a common conception among the Four Great Doctors of the Jin-Yuan period. 3. Zhang Zihe focused on eliminating pathogenic qi so that the body's qi would circulate smoothly to slowly restore the source qi. The theory of keeping balance was emphasized to achieve this goal. 4. Based on the theory of keeping balance, Zhang Zihe used various medicinals with different properties and flavors to allow for the medicinals in each of the sovereign, minister, assistant and courier positions to co-operate with each other, while using food reinforcement to restore the source qi.