• 대한화학회지
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• 제45권5호
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• pp.481-490
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• 2001

이 연구의 목적은 제 6차 교육과정에 의한 중학교 1학년 과학 교과서 분별 증류 실험의 문제점을 파악하고, 중학생들이 분별 증류 실험을 능률적으로 수행할 수 있는 실험 방법을 제시하고자 하는 것이다. 이를 위한 첫 번째 단계로서 현재 사용되고 있는 8종의 과학 교과서를 분별 증류 실험 장치와 액체 혼합물의 종류에 따라 6가지로 분류하였다. 두 번째 단계로서 액체 혼합물을 가열 방법에 따라 직접 가열과 물 중탕 가열로 나누어 교과서 실험과정에 따라 같은 실험을 세 번 실시하였다. 세 번재 단계로서 실험 결과의 문제점을 해결하기 위한 대안 실험을 실시하였다. 대안 실험에서는 알코올 램프로 직접가열 하는 방법과 기름 중탕으로 가열하는 방법, 그리고 가열 맨틀을 사용하여 가열하는 방법을 사용하였다. 연구결과, 가지달린 둥근 플라스크를 직접 가열하는 실험 결과가 가지 달린 시험관을 물 중탕으로 가열하는 실험 결과보다 이론적인 결과에 근접하였다. 그리고 가지 달린 둥근 플라스크를 직접 가열하는 실험에서 플라스크 윗 부분을 보온해 주는 실험이 보온하지 않은 실험보다 실험 결과가 더 나았다. 대안 실험에서는 액체 혼합물의 증류 온도 증가를 보면서 가열 맨틀의 가열 온도를 올려 준 실험의 결과가 이론적인 결과에 가장 가까웠다. 이러한 연구 결과로부터 가지 달린 시험관을 물 중탕으로 가열하는 분별 증류 실험장치는 탐구실험 수업에 부적절한 것이므로 개선이 요구되며, 중학교 과학실 여건을 고려할 때, 액체 혼합물의 증류 온도 증가를 보면서 가열 맨틀의 가열 온도를 변화시키는 분별 증류 실험이 가장 능률적인 방법임을 알 수 있었다.

• 대한기계학회논문집B
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• 제23권3호
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• pp.330-341
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• 1999

An experimental study for the two types of burners used in the non-oxidizing direct fired furnaces of the heat treatment process for the cold rolled plate has been carried out to investigate the combustion characteristics and the oxidization of the surface of steel plate. A steep temperature gradient and entrainment of residual oxygen were found near the heating surface in the flame of the nozzle mixing burner which has strong swirl velocity component. It was concluded that the elimination of the residual oxygen and the increase of the temperature of combustion gas on the heating surface are needed to enhance the performance of the burners for application to the non-oxidizing direct fired furnaces.

• Carbon letters
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• 제15권1호
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• pp.15-24
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• 2014

As a part of the electromagnetic spectrum, microwaves heat materials fast and efficiently via direct energy transfer, while conventional heating methods rely on conduction and convection. To date, the use of microwave heating in the research of carbon-based materials has been mainly limited to liquid solutions. However, more rapid and efficient heating is possible in electron-rich solid materials, because the target materials absorb the energy of microwaves effectively and exclusively. Carbon-based solid materials are suitable for microwave-heating due to the delocalized pi electrons from sp2-hybridized carbon networks. In this perspective review, research on the microwave heating of carbon-based solid materials is extensively investigated. This review includes basic theories of microwave heating, and applications in carbon nanotubes, graphite and other carbon-based materials. Finally, priority issues are discussed for the advanced use of microwave heating, which have been poorly understood so far: heating mechanism, temperature control, and penetration depth.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2007년도 추계학술대회 논문집
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• pp.73-74
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• 2007

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.1433-1438
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• 2007

Characteristics of a phase change type micro actuator have been studied. The micro actuator has been designed for a micro-pump in an active direct methanol fuel cell(DMFC), consisting of an actuating chamber, a membrane, an electric heater, and a sensor of resistance temperature detector (RTD). In the present study, researches have been focused on the response of the actuator to control algorithm of the heater. The experiments demonstrated that the displacement of the membrane increase with temperature variation which is a function of applied voltage, duty ratio, and operating frequency of heating. The results also showed that operation of the actuator with high voltage at small duty of heating is more efficient than the same power consumption of heating with low voltage at large duty.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2004년도 추계학술대회논문집
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• pp.83-88
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• 2004

Micro wires manufactured by the straightening progress are widely used in bio-medical and semi-conductor fields. In this study, we have developed a novel straightener which uses the direct heating method for straightening. In order to avoid the surface oxidization, during the heating process, we supplied the inert gas(Ar) and examined the effect of the gas flow rate. The effect of the tension and the current applied to the tungsten micro wires were thoroughly studied. From various experiments, it was found that when the tension is $500{\sim}600gf$ and the current is about 1.5A, we obtained higher straightness(${\approx}1{\mu}m/1000{\mu}m$) and roundness ($<{\pm}2{\mu}m/100{\mu}m$).

• Nuclear Engineering and Technology
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• 제33권5호
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• pp.468-482
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• 2001

As a process of Direct Containment Heating (DCH) issue resolution for Korean Standard Nuclear Power Plants (KSNPs), a containment load/strength assessment with two different approaches, the probabilistic and the deterministic, was performed with all plant-specific and phenomena-specific data. In case of the probabilistic approach, the framework developed to support the Zion DCH study, Two-Cell Equilibrium (TCE) coupled with Latin Hypercubic Sampling (LHS), provided a very efficient tool to resolve DCH issue. In case of the deterministic approach, the evaluation methodology using the sophisticated mechanistic computer code, CONTAIN 2.0 was developed, based on findings from DCH-related experiments or analyses. For three bounding scenarios designated as Scenarios V, Va, and VI, the calculation results of TCE/LHS and CONTAIN 2.0 with the conservatism or typical estimation for uncertain parameters, showed that the containment failure resulted from DCH loads was not likely to occur. To verify that these two approaches might be conservative , the containment loads resulting from typical high-pressure accident scenarios (SBO and SBLOCA) for KSNPs were also predicted. The CONTAIN 2.0 calculations with boundary and initial conditions from the MAAP4 predictions, including the sensitivity calculations for DCH phenomenological parameters, have confirmed that the predicted containment pressure and temperature were much below those from these two approaches, and, therefore, DCH issue for KSNPS might be not a problem.

• 한국결정성장학회지
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• 제12권6호
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• pp.288-291
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• 2002

We developed a new RF indirect-heating LPE furnace. The thermal gradient of our newly developed furnace is less than that of direct heating, and is as gentle as that of the resistance-heating LPE furnace. With this new furnace, the heating and/or cooling is faster than that of the resistance-heating furnace. Impurity-doped YIG film was grown from a $PbO-B_{2}O_{3}$, based flux on a (111) GGG substrate. To study the effect of the impurities on the MSSW threshold power and the saturation response time, we used two microstrip lines to excite and propagate the MSSW at 1.9 GHz. The MSSW threshold power and saturation response time was found to be related to the $\Delta$H.

• 대한기계학회논문집
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• 제11권1호
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• pp.97-104
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• 1987

본 논문에서는 순수한 액체상태의 온수 단위 질량을 대상으로 동력발생에서부 터 열펌프 까지의 가능한 응용을 고려하여 온도에 따른 최적 사용방법과 최대성능 발 휘시의 용량산정을 통하여 온수의 최적능력을 확인하고자 한다. 단 본 연구의 결과 는 순수히 열역하적인 것으로 경제적 관점에서 본다면 다소 다른 견해가 있을 수 있겠 으나 열역학적 및 경제적 관점 사이의 관계 및 제2법칙의 역할의 중요성은 이미 여러 논문에서 충분히 거론된 것으로서 여기서 언급하지 않는다.

• 한국식품과학회지
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• 제22권5호
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• pp.575-581
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• 1990

일정한 열처리 공정에 대해 Equivalent point가 존재함을 이상적인 두가지의 직접가열곡선 즉, $120^{\circ}C$에서 10분간 $135^{\circ}C$에서 10초간의 등온가열 곡선을 이용하여 예시하였다. 이러한 조건하에서 Arrhe nius model을 적용한 경우 임의의 Ea-값을 사용하여 G-값을 결정하고 Bigelow model을 적용한 경우, 임의의 z-값을 사용하여 F-값을 결정하였다. 이들 값을 사용하여 Equivalent time과 Equivalent Temperature를 두가지 방법 즉, 직교좌표법과 회기분석법에 의해 결정하였다. 이들 두 방법에 의해 결정된 Equivalent Point는 서로 일치하였으며 각각의 값은 초기에 가정했던 직접가열곡선의 가열시간 및 온도와 일치하였다.