• Journal of Magnetics
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• 제11권1호
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• pp.36-42
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• 2006

In this report, we demonstrate a comprehensive analysis of the effects of Au addition on the microstructure and magnetic properties of $Fe_{73.5}Si_{13.5}B_{9}Nb_{3}Au_1$ Finemet-type alloy. It was found that the as-quenched alloys were the amorphous state and turned into nanocrystalline state under heat treatments. The DSC analysis indicates that the sharply exothermal peak corresponding to the crystallization of the $\alpha-Fe(Si)$ was observed at $547-579^{\circ}C$ depending on the heating rates, which is little higher than that of original Finemet (542-$570{^{\circ}C}$, respectively). Besides, the thermomagnetic result confirmed that the full substitution of Cu by Au with the single phase structure in the M(T) curve along cooling cycle. Ultrasoft magnetic properties of the nanocrystallized samples were significantly enhanced by the proper annealing such as the increase of permeability and the decrease of the coercivity. The optimum annealing condition was found at the annealing temperature of $540^{\circ}C$ and the increase of the annealing time up to 90 min.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.2148-2153
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• 2007

The electricity conversion-efficiency of solar cell for commercial application is about 6-15%. More than 85% of the incoming solar energy is either reflected or absorbed as heat energy. Consequently, the working temperature of the photovoltaic cells increases considerably after prolonged operations and the cell's efficiency drops significantly. PV/T refers to the integration of a PV module and a solar thermal collector in a single piece of equipment. By cooling the PV module with a fluid steam like air or water, the electricity yield can be improved. At the same time, the heat pick-up by the fluid can be to support space heating or service hot-water systems. In this study, a pulsating heat pipe solar heat collector was combined with single-crystal silicon photovoltaic cell in hybrid energy-generating unit that simultaneously produced low temperature heat and heat and electricity. This experiment was investigating thermal and electrical efficiency for evaluation of a PV/T system.

• 대한기계학회논문집A
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• 제26권5호
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• pp.813-821
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• 2002

Glass fiber reinforced PET matrix composite was manufactured by rapid press consolidation technique as functions of temperature, pressure and time in pre-heating, consolidation and solidification stages. The optimal manufacturing conditions for this composite were discussed based on the void content, tensile, interlaminar shear and impact properties. In addition, the levels of crystallinity with various manufacturing conditions were measured using differential scanning calorimetry to investigate the mechanical properties of this composite material as a function of crystallinity. Among many processing parameters, the mold temperature and the cooling rate after forming were found to be the most critical factors in determining the level of crystallinity and mechanical properties. The level of crystallinity affects the tensile properties to some degree. However, impact properties are affected much more. It also affects the degree of ductility, which determines the impact energy of this material.

• 한국식품과학회지
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• 제9권2호
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• pp.165-169
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• 1977

용액의 열처리 온도까지의 온도 상승시간과 열처리 후 냉각시간이 무시될 수 있을 정도로 단시간이어서 고온에서의 측정이 가능한 연속 살균장치를 이용하여 열처리온도 $110^{\circ}C$와 $140^{\circ}C$범위 내에서 horseradish peroxidase의 열에 의한 불활성화 속도와 열역학적 자료를 측정 수집하였다. 그 결과 peroxidase의 열에 의한 불활성화 enthalpy, 146.4kJ/mol, free enegy of activation 113 kJ/mol, entropy of activation 82.9 J/mol.k를 얻었다. 본 실험에서 얻은 자료를 기초로하여 일반 미생물 살균 그래프와 비교하고 고온 단시간 살균공정(HTST)에서 효소의 불활성화에 충분한 열처리 시간을 고려해야함을 토론하였다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2008년도 춘계학술대회 논문집
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• pp.634-637
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• 2008

Ground source heat pumps are clean, energy-efficient and environment-friendly systems cooling and heating. Although the initial cost of ground source heat pump system is higher than that of air source heat pump, it is now widely accepted as an economical system since the installation cost can be returned within an short period of time due to its high efficiency. In the present study, performances of ground source compound hybrid heat pump system applied to a large community building are simulated. The system design and operation process appropriate for the surrounding circumstance guarantee the high benefit of the heat pump system applied to a large community building. If among several renewable energy sources, ground, river, sea, waste water source are chosen as available alternative energies are combined, COP of the system can be increased largely and hybrid heat pump system can reduced the fuel cost.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2008년도 춘계학술대회 논문집
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• pp.169-173
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• 2008

Stirling engine is a promising heat engine with a high efficiency, muti-fuel capability, low emission, quiet operation, very low maintenance and long life. As one of the promising applications, solar power system based on the Stirling dish, providing net solar-to-electric conversion efficiencies reaching 30%, can operate as stand-alone units in remote locations or can be linked together in groups to provide utility-scale power. This paper introduced a new Scroll-type Stirling engine, being developed for solar power, superior to conventional Stirling engines. The Scroll-type Stirling engine is characterized as traits of continuous and wholly separated compression and expansion; one-way flow system; direct cooling and heating the fluid in the working spaces through the extensive inner surfaces of scroll wraps. All theses traits contribute to achieving thermodynamic cycle closer to the ideal Stirling cycle (exactly speaking, Ericsson cycle).

• 한국진공학회지
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• 제7권3호
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• pp.255-260
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• 1998

Ionized magnetron sputtering은 high density plasma를 사용하여 스퍼터된 입자의 이온화율을 기판에서의 플럭스 기준으로 80%이상까지 증대시킬 수 있는 방법으로 반도체 소자의 아주 작은 홀이나 via contact등을 채울 수 있는 아주 유용한 수단이나 가스의 압력 이 30mTorr 이상으로 상당히 높아야만 이온화율이 높게 유지되어 스퍼터 증착 속도가 느려 지고 중성입자의 각도 분포가 넓어지는 단점이 있다. 그 원인이 스퍼터된 입자들에 의한 전 자 온도의 급격한 감소와 타겟 주변에서의 가스 희귀화 현상에 있다고 보고 이를 보완하고 자 스퍼터 전력을 펄스화 하는 방법을 고안하여 실험하였다. 그 결과 펄스의 on/off time이 10ms/10ms, 100ms/100ms에서 가장 높은 이온화율을 가시광 분광 결과에서 보였으며 실제 로 Ag의 XRD결과 (111)에서 (200)으로 우선 방위의 현격한 변화가 관찰되었다. 이를 고전 력 스퍼터링에 의한 중성 가스 가열과 냉각의 측면에서 해석하였다.

• 산업공학
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• 제24권3호
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• pp.187-195
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• 2011

The automatic radiopharmaceutical module consists of several 2-way valves, couple of syringes, gas supply unit, heating(cooling) unit and sensors to control the chemical reagents as well as to help the chemical reaction. In order to control the actuators of radiopharmaceutical module, the process is tabulated using spread sheet as like excel. Unlike the common program, a trivial error is too critical to allowed in the process because the error can lead to leak the radioactive reagent and to cause the synthesis equipment failure during synthesizing. Hence, the synthesis process has been validated using graphic simulation while the operator checks the whole process visually and undergoes trial and error. The verification of the synthesis process takes a long time and has a difficulty in finding the error. This study presents a methodology to verify the process algebraically while the radiopharmaceutical module is converted to the network model. The proposed method is validated using actual synthesis process.

• 한국주거학회논문집
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• 제24권6호
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• pp.69-79
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• 2013

The concept of sustainable development to preserve natural environment through economy in resources and energy is gradually distinguished since environmental problems as a series of air pollution and global warming take place now. Building occupies more than 1/3 of energy consumption in the whole world. Energy consumption of buildings caused a quick increase in the amount of energy use by air conditioning, which has a lot of effects on exhaustion of fossil energy as well as an increase in environmental load. Therefore, this research intends to suggest characteristics and direction for the designing of acclimatization's housing through the case study on acclimatization's housing. Acclimatization's housing is designed to reduce building load from the designing stage unlike green home or low-energy apartment. Also, factors which are commonly applied to acclimatization's housing are applied complexly by design strategic factors of Heating, Cooling and Lighting. The applied design factors make effects mutually and complexly. In addition, design strategy showed different priority by designing direction.

• KIEAE Journal
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• 제7권4호
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• pp.57-62
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• 2007

At the moment, the reduction of building energy consumption is a unavoidable task of mankind for conserving global environment. Decreasing overall U-value of building envelope and air infiltration, especially in Korean climate condition with clear four seasons, are the obvious solutions for the objective. Thus low glazing ratio with small window openings are required for heating and cooling load reduction in buildings. Using larger window openings could provide better natural ventilation but it also increases the direct solar radiation penetration into indoor space, heat gain in summer and heat loss in winter. On the other hand, the ventilation rates decreasing problem with smaller window openings could be occurred. As a solution for it, the use of casement window can cause increasing natural ventilation rates by wing wall effect. This paper focuses on deduce the most efficient opening type of casement window in Korean climate. To estimate ventilation performance of each opening types, CFD simulation was used. The best performance of opening type in every wind direction is opening both windows to the center and the most appropriate opening type for Korean climate is also opening both windows to center.