• Environmental Analysis Health and Toxicology
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• 제24권3호
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• pp.231-240
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• 2009

We explored collective behaviors of indicator species to elucidate the effect of the chemical stress. After the treatments of an insecticide, diazinon, at low concentrations (1.0 and 10.0 ${\mu}g/L$), spatial dispersion patterns of Daphnia magna were checked in a test chamber. The I-index was used to characterize the movement data before (0~1 h) and after (1~2 h) the treatments in laboratory conditions. The slopes of the frequency distribution of I-index in semi-log scale decreased significantly, and the test populations appeared to be more dispersed with a lower degree of aggregation after the treatments. The index was feasible in indicating decrease in the ability of the specimens to keep desirable distances with neighbor individuals under chemical stress and showed a possibility of monitoring presence of toxic chemicals in environment through group behavior measurement.

• International Journal of Internet, Broadcasting and Communication
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• 제7권2호
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• pp.28-35
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• 2015

Thin film electronic devices which brought the current mobile environment could be fabricated only under the high quality vacuum conditions provided by high vacuum systems. Especially for the development of advanced thin film devices, constant high quality vacuum as the deposition pressure is definitely needed. For this purpose, the variable conductance throttle valves were employed to the high vacuum system. In this study, the effects of throttle valve applications on vacuum characteristics were simulated to obtain the optimum design modelling of variable conductance of high vacuum system. Commercial simulator of vacuum system, $VacSim^{(multi)}$, was used on this investigation. Reliability of employed simulator was verified by the simulation of the commercially available models of high vacuum system. Simulated vacuum characteristics of the proposed modelling were agreed with the observed experimental behaviour of real systems. Pressure limit valve and normally on-off control valve were schematized as the modelling of throttle valve for the constant process-pressure of below $10^{-3}torr$. Simulation results were plotted as pump down curve of chamber, variable valve conductance and conductance logic of throttle valve. Simulated behaviors showed the applications of throttle valve sustained the process-pressure constantly, stably, and reliably.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2009년도 제33회 추계학술대회논문집
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• pp.134-137
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• 2009

본 연구에서는 친환경 추진제인 고농도 과산화수소와 케로신을 사용하는 저추력 이원추진제 로켓 엔진의 O/F ratio에 따른 연소 성능 특성을 파악하였다. 연소시험에 사용된 엔진은 6개의 동축 스월 인젝터로 구성된 멀티 인젝터와 연소실, 노즐로 구성되어있으며, 촉매 점화 방식을 사용하였다. 연소 시험은 O/F ratio 3.8에서 11.0까지 변화시켜가며 수행하였다. 연소 시험 결과를 이용하여 특성 속도($C^*$)와 압력 섭동 값을 계산한 결과, 연소 효율은 O/F ratio 5~6 구간에서 가장 좋았으며 모든 구간에서 연소실 압력대비 압력 섭동 값이 5% 미만으로 안정적임을 확인하였다.

• Nuclear Engineering and Technology
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• 제52권8호
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• pp.1689-1696
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• 2020

In this study, we developed a fiber-optic humidity sensor (FOHS) system for the monitoring and detection of coolant leakage in nuclear power plants. The FOHS system includes an FOHS, a spectrometer, a halogen white-light source, and a Y-coupler. The FOHS is composed of a humidity-sensing material, a metal tube, a multi-mode plastic optical fiber, and a subminiature version A (SMA) fiber-optic connector. The humidity-sensing material is synthesized from a mixture of polyvinylidene fluoride (PVDF) in dimethyl sulfoxide (DMSO) and hydroxyethyl cellulose (HEC) in distilled water. We measured the optical intensity of the light signals reflected from the FOHS placed inside the humidity chamber with relative humidity (RH) variation from 40 to 95%. We found that the optical intensity of the sensing probe increased linearly with the RH. The reversibility and reproducibility of the FOHS were also evaluated.

• 한국재료학회지
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• 제5권1호
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• pp.63-74
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• 1995

클러스터형의 다중 공정용 장치에 부착키 위해 제작된 콘택 산화막 식각용 공정모듈에 대한 적정 식각 공정조건을 확립하기 위해, Taguchi 방법을 활용하여 공정최적화 실험을 수행하였다. Taguchi 실험은 2회에 걸쳐 시행되었는데, 제1차 실험은 장비변수에 대한 식각공정변수의 개괄적 거동을 타진하기 위함이었고, 제2차 실험은 상세 공정조건 확립을 위해서였다. 실험 및 분석 결과 $CHF_{3}/CF_{4}$ 가스유량은 72/8sccm, 공정압력은 50 mTorr, RF 전력은 500 Watts, 자계강도는 90 Gauss일때 최적 공정 성능을 발휘함을 알 수 있다.

• 교육시설
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• 제14권1호
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• pp.58-65
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• 2007

For the moderns who spend more than 80% of the time inside a building, interior environment became important since it directly affects their health. Recently as noxiousness of the air contaminants of the interior space stood out as well as the above trend, the Ministry of Environment enacted a lawto maintain the interior air quality at certain level of standard in the multi use facility and newly constructed apartment. To make the indoor air clean, removal technology of various contaminants should be developed and interior materials with chemical treatment should be restrained. In other words, selection of interior finish affects indoor air quality from the initial design stage to the construction stage. However, only limited contaminants emission data of building materials are supplied by related companies. There is no average contaminants emission data for overall materials. Moreover, high cost and equipments for one time measurement of VOCs emission of interior finish are the obstacles of active research and data measurement. Therefore, this paper searched the current condition of average VOCs & HCHO emission of various interior finish based on the study requested to research center from the building material company through Stands Test Method for Indoor Air Quality.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.2
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• pp.995-998
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• 2003

This paper presents the deposition of poly-Si thin-film and fabrication of a solar cell by VHF-PECVD method. The poly-Si thin films. and pin-type solar cells are fabricated using multi-chamber cluster tool system. A 7.4% conversion efficiency was achieved from poly-Si thin film solar cells with total thickness less than $5{\mu}m$. The physical characteristic was measured by Raman spectroscopy, solar cell characteristic was measured under AM1.5 illumination.

• 한국태양에너지학회 논문집
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• 제22권1호
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• pp.1-8
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• 2002

With the possibility of hot water being able to be used as a heating source in a liquid desiccant system, an experimental apparatus for regeneration of the liquid desiccant was set up and series of experiments were conducted in a climate-controlled chamber. This study was performed to ascertain the influences of experimental factors on regenerating performance and to suggest the optimal combination of factors affecting regeneration rate. Furthermore. in order to figure out the contribution ratio of the factors on regenerating performance, a multi-way factorial design among the design of experiments was adopted. According to experimental results, the most influential factor on regenerating performance was temperature of the liquid desiccant and its contribution ratio was about 79.4%. In addition. the optimal operating combination was as follows; $60^{\circ}C$ of solution temperature, $14\ell$/min of solution flow rate, and 190m3/h of air volume.

• 설비공학논문집
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• 제28권10호
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• pp.414-419
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• 2016

Air flow measurement is a fundamental and important task for testing, adjusting, and balancing of HVAC system. However, it is difficult to carry out in the field due to the large size and weight of the flow meter. In this study, for the purpose of developing a small and portable flow meter, we proposed a different method of static pressure measurement and verified it experimentally. In the proposed method, static pressure difference was measured by inserting a tube inside the chamber before and after the nozzles. The results were compared with measurements according to the ANSI/ASHRAE standard. The results were in good agreement, indicating that the inserted tube method could be used for static pressure measurement of a portable flow meter. The proposed method eliminates the pressure tubes that are attached outside, which results in smaller size and easy handling.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 추계학술대회 논문집 학회본부 C
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• pp.873-875
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• 1999

We have fabricated good quality superconducting $YBa_{2}Cu_{3}O_{7-\delta}$ thin films on Hastelloy(Ni-Cr-Mo alloys) metallic substrate with $CeO_2$ and $BaTiO_3$ buffer layers in-situ by pulsed laser deposition in a multi-target processing chamber. We have chosen $CeO_2$ as a buffer layer which has cubic structure of $5.41{\AA}$ lattice parameter and only 0.2% of lattice mismatch with YBCO. $CeO_2$ layer may be helpful for power transmission due to its conducting property. In order to enhance the crystallization of YBCO films on metallic substrates. we deposited $CeO_2$ and $BaTiO_3$ buffer layers at various temperatures. The YBCO superconducting tape fabricated with $BaTiO_3$ and $CeO_2$ buffer layers shows 85K of transition temperature and about $8.4{\times}10^4A/cm^2$ of critical current density at 77K.