• 한국지열·수열에너지학회논문집
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• 제8권1호
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• pp.7-12
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• 2012

This study proposes a hybrid geothermal system combined with heating mode and snow-melting mode for winter season in order to increase the annual operating efficiency of the GSHP(Ground Source Heat Pump). The purpose of this study is to get effectiveness of the hybrid geothermal system by the site experiments. In case of snow-melting only mode, the GSHP COP is 0.7 higher than system COP in average. And in case of hybrid mode, heating GSHP COP is 0.5 higher than snow-melting GSHP COP. And it is also found out that all COP obtained through measurement periods is higher than nominal COPs given by GSHP manufacturer. As a conclusion, it is clear that the proposed hybrid geothermal system is expected as a highly efficient system.

• 한국광학회:학술대회논문집
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• 한국광학회 1989년도 제4회 파동 및 레이저 학술발표회 4th Conference on Waves and lasers 논문집 - 한국광학회
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• pp.32-35
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• 1989

A 150W industrial Nd:YAG laser was developed. The thermal lensing effect was examined and the radius and position of rear mirror were optimized for higher efficiency. The efficiency of 2.5% was achieved. Also, the performance of laser welding in fine thermocouples and between high-temperature-melting dissimilar metals were investigated.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.2285-2290
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• 2007

The main objective of this study is to analyze the heat transfer characteristics in the electric melting furnace. Local temperatures are measured at various location in the furnace using the B-type thermocouples. In this paper, the numerical simulation was performed using the ANSYS software, and compared with experimental data. Mathematical heat transfer model for the prediction of temperature distribution has been developed by considering the thermal radiation among heating element, crucible and insulating materials. The results show that the temperature distributions predicted by the numerical simulation agree with experimental results comparatively.

• Journal of Mechanical Science and Technology
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• 제15권6호
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• pp.796-803
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• 2001

Numerical solutions for the convection-dominated melting in a rectangular cavity are presented. The enthalpy-porosity model is employed as the mathematical model. This model is applied in conjunction with the EIT method to detect boundary movement in a phase changing environment. The absorption and evolution of latent heat during the phase change is dealt with by the enthalpy-based energy equation. This seems to be more efficient than resolving the temperature-based energy equation. The velocity switch-off, which is required when solid changes into liquid, is modeled by the porous medium assumption. For efficiency and simplicity of the solutions procedure, this paper proposes a simple algorithm, which iterates the temperature and the liquid fraction of the cells comprising the front layer. The numerical results agree reasonably well with the experimental data and other previous works using the transformed-grid system.

• 자원리싸이클링
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• 제13권4호
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• pp.46-52
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• 2004

저공해 소각 시스템이 구성되어 현재 폐기물처리의 주축을 이루고 있으나 경제 발전과 환경에 대한 인식, 재활용을 위한 분리수거율 향상 등으로 인하여 폐기물의 발열량이 점차 증가되고 있는 실정이다. 따라서 높은 발열량을 이용한 에너지의 효율적 이용에 대한 요구와 소각로에서 필수적으로 수반되는 중금속 ash문제, dioxin의 저감문제 등을 보다 효과적으로 처리하는 방법에 대한 연구가 끊임없이 지속되어 왔다. 여기에서는 최근에 가장 현실적으로 접근되고 있는 열분해시스템, 열분해용융시스템, 열분해가스화용융시스템의 대표적인 설비에 관하여 기술하였다.

• 한국에너지공학회:학술대회논문집
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• 한국에너지공학회 2004년도 춘계 학술발표회 논문집
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• pp.165-170
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• 2004

• 자원리싸이클링
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• 제21권4호
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• pp.69-75
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• 2012

본 연구는 가스화용융 시스템을 활용한 폐차 냉매의 친환경 파괴 기술개발을 목표로 하였다. 실증규모(생활폐기물 100톤/일) 가스화용융 시스템내 냉매를 주입할 수 있는 주입장치를 개발 및 제작하였으며, HFC-134a 주입량에 따른 냉매 분해효율 및 유해가스 특성을 고찰하였다. 분해효율은 3 kg/hr 냉매 주입시 99.995%이었고, 18시간 동안 유해가스 연속 측정 및 샘플링 측정결과, CO, SOx, NOx, HCl, HF 등의 유해가스는 환경법규를 만족하였고, 특히 냉매파괴 발생 HF는 0.1 ppm으로 법적 기준치 2ppm에 비해 미량으로 검출되었다.

• 한국컴퓨터정보학회논문지
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• 제12권4호
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• pp.201-207
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• 2007

제조업에서는 2개 이상의 상관이 있는 품질특성치를 동시에 감시하거나 관리를 하기 위한 필요성이 많이 제기되고 있다. 하지만 복수의 품질특성치를 각각 독립적으로 감시하면 판단의 오류가 발생될 수 있다. 복수의 품질특성치를 동시에 감시하고자 할 때 $X^2$ 또는 $T^2$와 같은 다변량 관리도가 사용되어질 수 있다. 본 논문에서는 다수의 품질특성치를 갖는 용해공정에서 조기에 이상 징후를 파악하기 위하여 다변량 관리도를 이용한 조기경보 시스템을 구현하였다. 용해공정에서 상관성이 있는 다수의 품질특성치를 동시에 관리하기 위해 개발된 이 모듈은 용해공정의 통계적 공정관리 활동에 효율성 및 효과성을 향상시켜 주었다.

• 한국기계가공학회지
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• 제18권10호
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• pp.93-98
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• 2019

Recently, with the development of the aerospace and automotive industries, the demand for high-melting-point materials has increased. However, high-melting-point materials are difficult to cut through conventional machining methods. Thermally assisted machining (TAM) is a method for improving the machinability by preheating the materials. A laser, the most commonly used device for TAM, has high efficiency through local preheating but is not sufficient for maintaining a high preheating temperature due to rapid cooling. However, the use of multi-heat sources can supplement the disadvantage of a single heat source. The high preheating temperature can be maintained with a wide and deep heat-affected zone (HAZ) by multi-heat sources. The purpose of this study is to analyze the preheating effects of multi-heat sources using laser plasma. Thermal analysis and preheating experiments were carried out. As a result, the high preheating effect of multi-heat sources compared with a single heat source was verified.

• 설비공학논문집
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• 제10권6호
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• pp.649-657
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• 1998

In this study, the effects of the various conditions of frosting and defrosting on the behavior of defrosting in a fin-tube heat exchanger have been examined experimentally. The electric heater is used for defrosting in a fin-tube heat exchanger It is shown that there are several local maxima in the water draining rate. The amount of residual water on the heat exchanger after the completion of defrosting is kept constant due to surface tension on the heat exchanger. Without considering the degradation of the thermal performance due to the frosting, the defrosting efficiency is improved with increasing amount of the frost irrespective of the frosting condition. The defrosting behavior is affected by the frosting density as well as the frost accumulation, which vary with the experimental operating conditions during the frosting period. The heat loss to the surrounding air decreases, and the melting and defrosting efficiencies show high values with decreasing heat input.