• 한국수소및신에너지학회논문집
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• 제20권4호
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• pp.283-290
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• 2009

This study focuses on the performance characteristics of polymer electrolyte membrane fuel cell (PEMFC) using the AC impedance technique. The experiment was carried out to investigate the optimal operating conditions of PEMFC such as cell temperature, flow rate, humidified temperature and back-pressure. The fuel cell performance was analyzed by DC electronic-loader with constant voltage mode and expressed by voltage-current density. Additionally, AC impedance was measured to analysis of ohmic and activation loss and expressed by Nyquist plot. The results showed that the cell performance increased with increase of cell temperature, air flow rate, humidified temperature and backpressure. Also, the activation loss decreased as the increase of cell temperature, air flow rate, humidified temperature and backpressure.

• 한국전자통신학회논문지
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• 제13권1호
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• pp.77-84
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• 2018

터빈유량계(Turbine flowmeter)는 유량 측정시 높은 정확도와 반복성을 위해 선택되지만 교정시의 표준 환경 조건과 현장에서의 환경 조건 차이로 다양한 측정 불확도 요인을 발생시킨다. 또한 교정된 측정값 외의 구간에서의 사용을 위해 신뢰성 높은 보간 기법(Interpolation method)이 필요하다. 따라서 본 논문에서는 유량 측정(Flow measurement) 신뢰성 향상을 위해 터빈유량계의 출력 신호의 정확한 측정과 교정된 결과값의 보간, 온도변화를 실시간 보정(correction)하는 장비를 설계 및 제작하고 성능 검증을 수행함으로 현장에서의 측정 신뢰도를 확보하였다.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2012년도 전기공동학술대회 논문집
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• pp.130-132
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• 2012

In this paper, a temperature control for LED(Light Emitting Diode) lamp using a cooling fan is studied. An efficient temperature control scheme for the LED lamp using the fan wind at the lowest sound noise is studied. For the study, after measurement of the minimum sound noise of the fan and related temperature of the LED lamp through tests, experiments on temperature control of the LED lamp using the fan with various size of heat sinks was performed. To minimize the fan sound noise, optimal size of the heat sink was studied. Also, a teleoperting control of LED lamps using RF communication was studied.

• 한국해양공학회지
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• 제14권2호
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• pp.60-64
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• 2000

An experimental study was performed to investigate the optimal ejector and operating condition of vessel incinerator. Exhaust gas temperature and secondary air which makes vacuum pressure at ejector throat regions were considered as an important factor. According to the measurement of pressure temperature and nitrogen oxides between non combustion and combustion we found the stream and exhaust gas characteristics of incinerator. This results can give us the exhaust gas temperature control system air pollutant reduction method and the optimum ejector design.

• 한국농공학회논문집
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• 제61권6호
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• pp.73-79
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• 2019

Continuous and tremendous data (canopy temperature and meteorological variables) are necessary to determine Crop Water Stress Index (CWSI). This study investigated the optimal monitoring time and interval of canopy temperature and meteorological variables (air temperature, relative humidity, solar radiation and wind speed) to determine CWSIs. The Nash-Sutcliffe model efficiency coefficient (NSE) was used to quantitatively describe the accuracy of sampling method depending upon various time intervals (t=5, 10, 15, 20, 30 and 60 minutes) and CWSIs per every minute were used as a reference. The NSE coefficient of wind speed was 0.516 at the sampling time of 60 minutes, while the ones of other meteorological variables and canopy temperature were greater than 0.8. The pattern of daily CWSIs increased from 8:00 am, reached the maximum value at 12:00 pm, then decreased after 2:00 pm. The statistical analysis showed that the data collection at 11:40 am produced the closest CWSI value to the daily average of CWSI, which indicates that just one time of measurement could be representative throughout the day. Overall, the findings of this study contributes to the economical and convenient method of quantifying CWSIs and irrigation management.

• 한국정밀공학회지
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• 제16권3호통권96호
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• pp.215-221
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• 1999

The object of the thermal error compensation system in machine tools is improving the accuracy of a machine tool through real time error compensation. The accuracy of the machine tool totally depends on the accuracy of thermal error model. A thermal error model can be obtained by appropriate combination of temperature variables. The proposed method for optimal variable selection in the thermal error model is based on correlation grouping and successive regression analysis. Collinearity matter is improved with the correlation grouping and the judgment function which minimizes residual mean square is used. The linear model is more robust against measurement noises than an engineering judgement model that includes the higher order terms of variables. The proposed method is more effective for the applications in real time error compensation because of the reduction in computational time, sufficient model accuracy, and the robustness.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 추계학술대회 논문집 Vol.17
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• pp.243-246
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• 2004

Boron Phosphide films were deposited on (111) Si substrate at $650^{\circ}C$, by the reaction of $B_2H_6$ with PH, using APCVD. $N_2$ was carried out as carrier gas. The optimal gas rates were 20 ml/min for B2H6, 60 ml/min for PH3 and 1 l/min for N2. After as grown the films were insitu annealed fur 1hour in $N_2$ ambient at $550^{\circ}C$ and measured. The measurement of AFM shows that the average surface roughness is $10.108{\AA}$ for the reaction temperature at $450^{\circ}C$ and $29.626{\AA}$ fur the reaction temperature at $650^{\circ}C$. The measurement of XRD shows that the films have the orientation of(1 0 1). Also, the measurement of AES is shown that the films have $B_{13}P_2$ stoichiometry. For the Result of microwaves absorbtion properties using VNA, it obtained the permittivity of BP about 8 between $1.5{\sim}2.5GHz$. In this study, it obtained the BP thin film by deposited in atmosphere pressure And BP thin film can be after to applicate as microwave absolution material is obtained.

• 한국수소및신에너지학회논문집
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• 제28권6호
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• pp.729-737
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• 2017

The measurement accuracy of Tunable Diode Laser Absorption Spectroscopy based Tomography (TDLAST) for the temperature and concentration fields are dependant upon the arrangement method of the used laser beams. This paper reports on the optimization of laser beam arrangements using phantom data. It has been verified that the measurement error of the TDLAST decreased with increase of laser beam numbers. Further, it has been confirmed that perpendicular arrangements between the horizontal and the vertical laser beams without additional diagonal laser beams shows the minimum measurement errors.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2006년도 하계종합학술대회
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• pp.473-474
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• 2006

Boron Phosphide films were deposited on (111) Si substrate at $650^{\circ}C$, by the reaction of B2H6 with PH3 using APCVD. N2 was carried out as carrier gas. The optimal gas rates were $20\;m{\ell}/min$ for B2H6, $60\;m{\ell}/min$ for PH3 and $1\;{\ell}/min$ for N2. After as grown the films were insitu annealed for 1hour in N2 ambient at $550^{\circ}C$ and measured. The measurement of AFM shows that the RMS is $29.626{\AA}$ for the reaction temperature at $650^{\circ}C$. The measurement of XRD shows that the films have the orientation of (101). Also, the measurement of AES is shown that the films have B13P2 stoichiometry.

• 마이크로전자및패키징학회지
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• 제31권2호
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• pp.63-68
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• 2024

최근 투명 디스플레이 및 유연 소자의 활용도가 증가함에 따라 우수한 유연성과 강성을 갖는 폴리머 소재 기판의 사용이 증가하고 있다. 그러나 폴리머는 열에 취약하여 공정 중 온도 및 열 제어가 필수적이다. 이러한 폴리머 기판 활용의 단점을 해결하기 위해 본 연구에서는 레이저 기반의 선택적 가공 기술에 적용할 수 있는 폴리머 기판 내 레이저 가공영역의 온도 측정 시스템을 제안한다. 레이저 가공 영역의 국부적인 온도 변화 측정을 통해 폴리머 기판의 공정 조건을 최적화하는 가능성을 제시한다. 이를 위해 플랑크 흑체 복사 원리를 기반으로 한 PDPT(Photodiode based Planck Thermometry)를 설계 및 제작하여 레이저가 입사되는 영역의 온도를 측정하였다. PDPT는 비파괴/비접촉식 온도측정 시스템으로, 레이저가 입사되는 국부적인 온도 상승을 실시간으로 측정할 수 있다. 해당 시스템을 활용하여 폴리머 기판의 레이저 가공 공정에서 발생하는 가공영역의 온도 변화를 관측하였다. 본 연구 결과, 제안된 레이저 기반 온도측정 기술은 레이저 가공 공정 중 실시간 온도 측정이 가능하며, 이를 통해 최적의 생산 조건을 확립할 가능성을 보여주고 있다. 또한, 해당 기술은 열 제어가 필수적인 미세 레이저 가공 및 3차원 프린팅과 같은 다양한 레이저 기반 공정에 적용될 수 있을 것으로 기대된다.