• 대한기계학회논문집A
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• 제31권6호
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• pp.665-670
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• 2007

Alpha-phase alumina TGO(Thermally Grown Oxide) forms on the interface between zirconia top coat and bond coat of thermal barrier coating system for superalloys during exposure to high temperature over $1000^{\circ}C$. It is known to provide a good protection against hot corrosion and to cause surface failure such as rumpling and cracking due to difference in thermal expansion coefficient from the substrate metal and the lateral growth. Consequently, mechanical properties of the alumina TGO at the high temperature are the key parameters determining the integrity of TBC system. In this work, by using Fecralloy foils as the alumina forming substrate, creep tests and tensile tests have been performed with various TGO thicknesses$(h=0{\sim}4{\mu}m)$ and yttrium contents(0, 200ppm) at $1200^{\circ}C$. Displacement-time curves and load-displacement curves for each TGO thickness(h=1,2,..) were measured from the creep and tensile tests, respectively, and compared with the curves without TGO thickness(h=0). As the result, the intrinsic tensile and creep properties of TGO itself were determined.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 하계학술대회 논문집 B
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• pp.749-752
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• 1993

This paper deals with the development of three phase 440[V], 500[KVA] Inverter system using the IGBT Devices. IGBT's have been used very successfully in variable frequency induction motor drive equipment. Problems associated with power devices characteristics when power devices are operated in parallel, such as balanced switching behavior and thermal stability, can be solved by using NPT type IGBT's. By Experimental results, it is confirmed that the voltage overshoot and reverse recovery current was very low. The equipment had proved to be reliable and short circuit proof. In addition, the performances in term of thermal characteristics, protection functions and stability are satisfactory.

• 한국태양에너지학회 논문집
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• 제25권2호
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• pp.63-69
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• 2005

This study is the survey of a transition procedure of building services systems(heat source, HVAC, water supply) through the survey of existing office buildings, building design documents. The preference & major consideration of system selection is the engineer's opinions. The results of this survey can be used in selection of building services system design. In this survey, "Hot & cold water generator system" and "single duct CAV+FCU system", "Elevated water tank system" are selected. The most important consideration in system selection is the energy saving in heat source system, and comfort in HVAC system, and water pressure in water supply system. They prefer "steam boiler+absorption chiller system" for heat source system, "steam boiler+ice thermal storage system", "hot & cold water generator system", "district heating+absorption chiller system" : "single duct CAV+FCU system" and "single duct VAV+convector system" for HVAC system: and "booster pump system" for water supply system.

• Journal of Radiation Protection and Research
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• 제43권4호
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• pp.160-169
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• 2018

Background: This study aims to develop an integrated optical system that can simultaneously or selectively measure the signals obtained from radioluminescence (RL), thermoluminescence (TL), and optically stimulated luminescence (OSL), which are luminescence phenomena of materials stimulated by radioactivity, heat, and light, respectively. The luminescence mechanism of various materials could be investigated using the glow curves of the luminescence materials. Materials and Methods: RL/TL/OSL integrated measuring system was equipped with a X-ray tube (50 kV, $200{\mu}A$) as an ionizing radiation source to irradiate the sample. The sample substrate was used as a heating source and was also designed to optically stimulate the sample material using various light sources, such as high luminous blue light emitting diode (LED) or laser. The system measured the luminescence intensity versus the amount of irradiation/stimulation on the sample for the purpose of measuring RL, TL and OSL sequentially or by selectively combining them. Optical filters were combined to minimize the interference of the stimulation light in the OSL signal. A long-pass filter (420 nm) was used for 470 nm LED, an ultraviolet-pass filter (260-390 nm) was used for detecting the luminescence of the sample by PM tube. Results and Discussion: The reliability of the system was evaluated using the RL/OSL characteristics of $Al_2O_3:C$ and the RL/TL characteristics of LiF:Mg,Cu,Si, which were used as dosimetry materials. The RL/OSL characteristics of $Al_2O_3:C$ showed relatively linear dose-response characteristics. The glow curve of LiF:Mg,Cu,Si also showed typical RL/OSL characteristics. Conclusion: The reliability of the proposed system was verified by sequentially measuring the RL characteristics of radiation as well as the TL and OSL characteristics by concurrent thermal and optical stimulations. In this study, we developed an integrated measurement system that measures the glow curves of RL/TL/OSL using universal USB-DAQs and the control program.

• Journal of Radiation Protection and Research
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• 제37권1호
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• pp.35-40
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• 2012

국내 교정기관 또는 표준기관은 중성자 검출기의 교정을 위해 비감속 및 중수감속 $^{252}Cf$ 선원과 $^{241}AmBe$ 선원을 사용하고 있다. 이런 선원들로 교정된 중성자 검출기를 이용하여 입자가속기와 같이 속중성자가 다량 존재하는 시설을 선량평가할 때, 그 정확도가 떨어지게 된다. 그 이유는, 대부분의 중성자 검출기는 열중성자에 민감하게 반응하므로 수 MeV 이상의 에너지를 가지는 속중성자장에 대한 선량당량 반응도는 부정확하다. 또한 높은 에너지의 중성자는 열중성자보다 선량기여정도가 훨씬 크기 때문이다. 이와 같은 이유로, 기존의 교정용 기준 중성자장이 아닌 수 MeV 이상의 속중성자가 존재하는 중성자장에서도 검출기를 교정할 필요가 있다. DT 중성자 발생기, 흑연집합체 그리고 폴리에틸렌 중성자 집속체를 사용하여 속중성자의 선속분율이 서로 다른 중성자장을 제작하였고, 이 중성자장에서 중성자 검출기의 선량당량 반응도를 측정하였다. 시험결과에 의하면, 속중성자 선속분율과 중성자 검출기의 종류에 따라 중성자 검출기의 반응도는 많은 차이를 보였다. 이러한 반응도 차이는 선량당량의 과대 및 과소평가를 의미하므로, 검출기가 사용되는 시설환경과 유사한 중성자장에서 반응도 교정이 필요함을 확인하였다.

• 한국태양에너지학회 논문집
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• 제34권2호
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• pp.73-81
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• 2014

Ocean thermal energy conversion(OTEC) is a power generation method that utilizes temperature difference between the warm surface seawater and cold deep sea water of ocean. As potential sources of clean-energy supply, Ocean thermal energy conversion(OTEC) power plants' viability has been investigated. Therefore, this paper evaluated the thermodynamic performance of solar-OTEC convergence system for the production with electric power and desalinated water. The comparison analysis of solar-OTEC convergence system performance was carried out as the fluid temperature, saturated temperature difference and pressure of flash evaporator under equivalent conditions. As a results, maximum system efficiency, electric power and fresh water output show at 40, 10, 2.5 kPa of the flash evaporator pressure, respectively. And their respective enhancement ratios were approximately 6.1, 18, 8.6 times higher than that of the base open OTEC system. Also, performance of solar-OTEC system is the highest in the flash evaporator pressure of 10 kPa.

• 전기학회논문지
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• 제58권6호
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• pp.1100-1104
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• 2009

As national power consumption every year increases, the power plant which is in the process of planning tries to establish high-capacity generator. The power system tends to become a large size. With the progress of electronic components, the control systems of the generator have been digitalized and rapid-response control system is possible. However, the minute frequency vibration of grid occurred with the effect of rapid-response control system. To solve these problem, PPS(Power System Stability) has been introduced since 2004, and it has being installed and applied to the thermal and nuclear power plant which are high-capacity, over 800MVA. However the minute frequency vibration is gradually changed to the bigger frequency vibration by fast-action control system, and this regional frequency fluctuation might be diffused wide area. Therefore, it is applied to the hydro generator which is small with fast-action governor system, and it is necessary to control the minute frequency vibration to prevent to diffuse. In this paper, the effect will be proved by establishing PSS on the Hydro-Generator which has both digital excitation and governor system for the first time in Korea.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2002년도 춘계학술대회논문집
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• pp.61-65
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• 2002

The present study was numerically and experimentally performed to investigate the fire suppression performance of water mist spray subjected to thermal radiation in closed space. Downward-directed water mist sprays to interact with an under kerosine pool fire were investigated in test facility. The mass mean diameters of water mist droplet were measured by PMAS under various flow conditions. The developed water mist spray nozzle was satisfied to the criteria of NFPA 750, Class 1. The mechanism of the fire suppression by water mist was concluded to be cooling of the fire surface which lead to suppressed of fuel evaporation. It was proved that the water mist spray system under lower pressures could be applied to underground fire protection system.

• KIEAE Journal
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• 제13권1호
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• pp.75-81
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• 2013

The balcony of our apartment building consists of unique construction similar to double skin. It is announced broadly that double skin is very effective system in improvement of natural ventilation and indoor thermal environment, and outdoor sound protection. So, for the improvement of indoor climate and energy saving, many peoples studied about environmental performance of our balcony construction. This study focus on shaft box facade, special form of box window construction. It consists of a system of box window with continuous vertical shafts that extend over a number of stories to create a stack effect. Proto-type was decided by analyzing various types of exiting apartments. Shaft box type balcony was created by setting up shaft space at a part of balcony. Air flow and contribution of air temperature were simulated, performance of shaft box type balcony was compared with existing balcony. Finally, we confirmed that shaft box type balcony has many possibility for improvement of indoor environment.

• 한국화재소방학회논문지
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• 제33권2호
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• pp.56-62
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• 2019

스프링클러는 방호구역에 설치된 감지기 또는 헤드가 화재를 감지하여 자동으로 화재를 진압하는 소화설비로 화재 초기에 뛰어난 소화효과가 있어 폭넓게 설치되고 있다. 하지만 국토교통부의 "건축물의 피난 방화구조 기준 등에 관한 규칙"에는 공장 또는 창고의 경우 스프링클러설비를 설치하면 방화구획을 3배까지 완화해 줄 수 있도록 그 근거를 제공하고 있다. 이에 본 연구에서는 스프링클러설비 설치로 방화구획을 완화한 실제 Printed Circuit Board (PCB) 공장 1개소를 대상으로 화재위험성을 분석하였고, 컴퓨터 시뮬레이션을 통한 스프링클러설비의 헤드 개방 특성 및 스프링클러 설비의 설치기준, 감열성능, 작동범위, 방수량 등을 분석하였다. 또한 이를 통해 화재 시 스프링클러 설비 작동의 문제점을 확인하고, 제도 개선을 위한 요구 살수유량 등 근거를 제시하고자 한다.