• 센서학회지
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• 제25권5호
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• pp.344-348
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• 2016

We developed a 2-channel fiber-optic temperature sensor (FOTS) using a temperature sensing probe, a fiber-optic coupler, transmitting optical fiber, and an optical time domain reflectometer (OTDR). The temperature sensing probe is divided into a sensing probe and a reference probe for accurate thermometry. A sensing probe is composed of a silicon oil, a FC terminator, a brass pipe, and a singlemode optical fiber and the structure of a reference probe is identical with that of the sensing probe excluding a silicon oil. In this study, we measured the modified optical powers of the light signals reflected from the temperature sensing probe placed inside of the water with a thermal variation from 5 to $70^{\circ}C$. Although the optical power of the reference probe was constant regardless of the temperature change, the optical power of the sensing probe decreased linearly as the temperature increased. As experimental results, the FOTS using a subtraction method showed a small difference (i.e., hysteresis) in its response due to heating and cooling. The reversibility and reproducibility of the FOTS were also evaluated.

• 대한전자공학회논문지SD
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• 제41권12호
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• pp.59-65
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• 2004

적외선 소자로부터 생성되는 신호의 잡음 특성의 향상, 즉 좋은 영상을 얻기 위해서 적외선 영상신호 취득회로(ROIC)에서는 안정적인 기준 전압원이 필요하다. 본 논문은 극저온인 77K에서 동작하는 적외선 영상신호 취득회로(readout integrated circuit)를 위한 밴드갭 회로를 처음으로 제작한 후 측정, 평가하여 그 실용 가능성을 입증하고 있다. 밴드갭 회로는 대표적인 전압 기준회로로서 기존에 발표된 대부분의 밴드갭 회로는 실온에서 동작하는 것이며, 액체질소 온도 77K에서는 그 특성이 적합하지 않다. 본 논문에서는 극저온에서 동작하는 밴드갭 회로 설계를 위하여, 그에 맞는 회로를 선택하여 온도변화에 따른 사용되는 소자들의 파라미터에 대한 이론정립을 통한 그것의 특성을 살펴보고, 이러한 특성들을 고려하여 저온동작에 적합도록 하였다. 이 회로는 Hynix 0.6um standard CMOS 공정을 통해서 제작되었으며, 측정된 출력전압($V_{out}$)은 60K에서 110K까지 1.0396$\pm$0.0015V로서 기존의 실온에 동작하던 밴드갭 회로보다 더 높은 안정도를 보여주었다.

• 한국구조물진단유지관리공학회 논문집
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• 제17권2호
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• pp.94-100
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• 2013

본 논문은 철근콘크리트 구조물이 화재를 입었을 경우의 최고 노출 온도 예측 및 화재손상 분석을 위하여 콘크리트 시험체에 대한 기기 분석적 고찰을 실시하였다. 시차열분석 결과, $200^{\circ}C$까지는 모세관수 및 겔수의 증발로 인한 강한 흡열피크가 일어났으며, $520^{\circ}C$정도에서 수산화칼슘 ($Ca(OH)_2$)의 분해로 인해 흡열피크가 생성되었고, 흡열 반응으로 인해 시료의 중량이 크게 감소되었다. $720^{\circ}C$정도에서 칼사이트 ($CaCO_3$)의 분해로 인해 또 한번의 강한 흡열반응이 발생한 것을 알 수 있었다. 또한 X-선 회절분석 결과, $400^{\circ}C$까지는 $Ca(OH)_2$가 존재하지만 $600^{\circ}C$이상부터는 CH성분은 거의 소멸되고 CaO의 성분이 나타났으며, 온도가 높을수록 생성량이 증가하였다. 이것은 화재 시 콘크리트의 온도가 증가될수록 $Ca(OH)_2$과 $CaCO_3$가 분해되어 CaO로 변환되기 때문이며, $Ca(OH)_2$와 $CaCO_3$가 완전히 분해되어 피크가 없어지고 대신 CaO의 피크가 크게 형성되는 온도 범위를 약 $700{\sim}800^{\circ}C$로 추정할 수 있다. 주사형 전자현미경 분석 결과, 고열에 의해 콘크리트를 구성하고 있는 시멘트 반응생성물에서 결합수 및 겔수의 탈수로 인해 콘크리트의 수축이 발생함으로써 미세한 균열이 전반적으로 심하게 발생되는 것을 볼 수 있다. 이를 통해 보통 콘크리트가 열을 받으면 $300^{\circ}C$부터 미세균열이 발생되어 $500^{\circ}C$에서는 상당히 심하게 균열이 발생되는 것을 알 수 있다.

• JSTS:Journal of Semiconductor Technology and Science
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• 제16권6호
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• pp.728-735
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• 2016

A 70 MHz temperature-compensated on-chip CMOS relaxation oscillator for mobile display driver ICs is proposed to reduce frequency variations. The proposed oscillator compensates for frequency variation with respect to temperature by adjusting the bias currents to control the change in delay of comparators with temperature. A bandgap reference (BGR) is used to stabilize the bias currents with respect to temperature and supply voltages. Additional temperature compensation for the generated frequency is achieved by optimizing the resistance in the BGR after measuring the output frequency. In addition, a trimming circuit is implemented to reduce frequency variation with respect to process. The proposed relaxation oscillator is fabricated using 45 nm CMOS technology and occupies an active area of $0.15mm^2$. The measured frequency variations with respect to temperature and supply voltages are as follows: (i) ${\pm}0.23%$ for changes in temperature from -30 to $75^{\circ}C$, (ii) ${\pm}0.14%$ for changes in $V_{DD1}$ from 2.2 to 2.8 V, and (iii) ${\pm}1.88%$ for changes in $V_{DD2}$ from 1.05 to 1.15 V.

• 한국안전학회지
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• 제32권5호
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• pp.54-61
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• 2017

The purpose of this study is to develop standard reference materials for safety control of construction materials considering the required performance of standard materials including flow performance incorporating particles. The flow characteristics of concrete are very complicated depending on mixing proportions of constituent materials, admixtures, amount of mixing, type of mixer, time of mixing, temperature and so forth. Uncertainties and multidimensional properties of concrete have been evaluated through various studies but there are few researches for the development of standard reference material. In this study, based on the rheological concept, the flow performance of construction materials was evaluated to understand the properties of standard reference materials and was finally obtained representing materials which simulate the standard reference materials.

• 전기학회논문지
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• 제61권5호
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• pp.753-756
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• 2012

In this paper, a modified low-votlage CMOS bandgap voltage reference with CTAT compensation is presented. The proposed structure doesn't use PTAT current. The proposed structure is more simple than the existing structure and doesn't use the eighteen BJT. The modified low-votlage CMOS bandgap voltage reference with CTAT compensation has been successfully verified in a standard 0.18um CMOS process. The simulation results have confirmed that, with the minimum supply voltage of 1.25V, the output reference voltage at 549mV has a temperature coefficient of 12$ppm/^{\circ}C$ from $0^{\circ}C$ to $100^{\circ}C$.

• 한국식품과학회지
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• 제25권6호
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• pp.643-648
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• 1993

표준온도 상당시간을 이용하여 규칙적인 온도변화 조건에서 식품의 품질변화를 간편하게 예측하는 근사식의 유효성을 밝히기 위하여, 비등온 가속조건 및 상온저장 조건에서 Sucrose 가수분해속도를 측정한 설험자료로 비교, 분석을 분석하였다. 정속가열 (定速加熱) 가속(加速)실험을 통해 구한 sucrose의 가수분해 반응은 1차 반응이고, 활성화에너지는 25.84kcal/mol이었으며, 반응속도상수는 pH가 감소함에 따라 직선적으로 증가하였다. 하루 동안의 온도변화를 sine wave 형태 온도변화로 가정하고 하루 동안에 일어난 품질변화를 표준온도 $T_{ref}$에서 몇일 동안에 일어난 변화에 상당하는가를 의미하는 표준온도 상당시간 $T_{eq.i}$를 이용하여 품질변화를 근사적으로 간단히 예측하는 방법을 제안하였다. Sucrose 액체 모델 시스템을 sine wave 형태의 규칙적인 온도변화 조건에서의 가속 가수분해실험 결과와 $T_{eq.i}$를 이용하여 품질변화를 computer simulation한 결과, 실험값과 예측값과의 상관계수는 0.99로서 잘 일치하였으므로 표준온도상당시간을 이용한 예측 모델의 유효함을 확인하였다. 뿐만 아니라 sucrose 모델 시스템을 실제 상온 저장한 실험결과와 계절적 온도변화를 computer simulation하여 예측한 값과는 상관계수가 0.92로서 잘 일치하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.1316-1317
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• 2011

This paper presents analysis of temperature and light intensity characteristics of PV modules with solar cell type. Taking the effect of sunlight irradiance on the cell temperature, the first experiment takes ambient temperature as reference input and uses the solar insolation as a unique varying parameter. Then taking the effect of the cell temperature on sunlight irradiance, the second experiment takes 1000W/$m^2$ as reference input and uses the cell temperature as a unique varying parameter. As a result, varying sunlight irradiance, the Cell-Type with the smallest change in output is HIT and the Cell-Type with the biggest change in output is a-Si. Varying the cell temperature, the Cell-Type with the smallest change in output is a-Si and the Cell-Type with the biggest change in output is Single-Si. And considering both temperature and light intensity characteristics, the Cell-Type with the smallest change in output is HIT.

• 전자공학회논문지S
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• 제34S권11호
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• pp.80-92
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• 1997

This research focuses onan efficient control method of temperature for multiple points using only one processor. For a yarn production system, the surface temperature control of heaters are very important for quality control. Therefore, we designed a temperature controller for a draw and twist machine and applied Fuzzy-PWM algorithm to the controller. If we use a processor for the temperature control of multiple points with the conventional ON/OFF control, the control performance of the system becomes poor. To overcome these problems, we developed a new Fuzzy-PWM algorithm for the adjustment of power rate to the heaters in the conventional ON/OFF control. It is shown that this algorithm has the same effects as the PID algorithm for the temperature control of each point. The proposed algorithm is robust against the production condition and environment such as the reference temperature and the thickness of yarn, since the power rate to the heater is adjusted by Fuzzy Rules derived from the values of the reference termperatureand the thickness of yarn. To obtain optimal Fuzzy rulees, the control simulations are perfodrmed through the modelling of the heater and simulation of Fuzzy rules. This algorithm is applied for the multiple pont temperature controller and showed satisfactory performance.

• Journal of information and communication convergence engineering
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• 제8권2호
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• pp.197-200
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• 2010

The FLL(frequency locked loop) circuit is used to generate an output signal that tracks an input reference signal. The locking time of FLL is short compared to PLL(phase locked loop) circuit because the output signal of FLL is synchronized only in frequency. Also the FLL is designed to allow the circuit to be fully integrated. In this paper, the temperature stable FLL circuit is designed by using full CMOS transistors. When the temperature is varied from $-20^{\circ}C$ to $70^{\circ}C$, the variation of output frequency is about from -2% to 1.6% from HSPICE simulation results.