• 설비공학논문집
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• 제11권3호
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• pp.369-376
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• 1999

Experiments were carried out to study the heat transfer characteristics of a disrober for 150 RT LiBr-water absorption heat pump. An experimental apparatus was divided into four sections, a combustion chamber area, two bare-tube areas, and finally a finned-tube area to quantify the heat transfer rate of each section by measuring the generation rate of vapor. Dividing plates was installed at the upper inside part of deserter to prohibit the moving of vapor generated at heating tubes of a section to another section near. In the first bare-tube area, the generation rate of vapor was the largest among the four sections. The finned-tube area only contributed to give sensible heat increase of solution to the saturation temperature. The heat transfer area of the finned-tube area was 52.2%, which absorbed only 9.2% of the total heat from the combustion gas. On the contrary, the heat transfer area of the first bare-tube area was 16.6%, but it absorbed 52.4% of the total absorbed heat. The temperature of the solution at upper part at the finned-tube area was lower than that of the lower part, because weak solution came in upper part of the finned-tube area. But, this tendency was changed at the first and second bare-tube area due to the vigorous heat transfer and fluid flow enhanced by vapor generation through heating tubes. The overall heat transfer coefficient and heat flux were the largest at the first bare-tube area among the other sections.

• International Union of Geodesy and Geophysics Korean Journal of Geophysical Research
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• 제24권1호
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• pp.29-45
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• 1996

Before (March 26, 1994) or after the occurrence of a downslope windstorm (March 29), the NO, $NO_2$, and $SO_2$ at the ground level of Kangnung city were monitored with high concentrations in the afternoon, due to a large amount of gases emitted from combustion of motor vehicle and heating apparatus, especially near 1600-1800 LST and 2000-2100 LST, but at night, they had low concentrations, resulting from small consumptions of vehicle and heating fuels. When both moderate westerly synoptic-scale winds flow over Mt. Taegwallyang and easterly meso-scale sea breeze during the day, atmospheric pollutants should be trapped by two different wind systems, resulting in higher concentration at Kangnung city in the afternoon. At night, the association of westerly synoptic wind and land breeze can produce relatively strong winds and the dissipation by the winds cause these low concentrations to lower and lower, as nightime goes on. From March 27 through 28, an enforced localized windstorm could be produced along the lee side of the mountain near Kangnung, generating westerly internal gravity waves with hydraulic jump motions. Sea breeze toward inland appartantly confines to the bottom of the eastern side of the mountain, due to the interruption of eastward violent internal gravity waves. As the windstorm moves down toward the ground, an encountering point of two opposite winds approaches Kangnung, and a great amount of NO and $NO_2$ were removed by the strong surface winds. Thus, their maximum concentrations are found to be near 18 and 20 LST, 17 and 21 LST. In the nighttime, the more developed storm should produce very strong surface winds and the NO and $NO_2$ could be easily dissipated into other place. The $SO_2$ concentration had no maximum value, that is, almost constant one all day long, due to its removal by the strong surface winds. Especially, the CO concentrations were slightly lower during the strom period than both before or after the strom, but they were nearly constant without much changes during the during the daytime and nighttime.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.2102-2107
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• 2007

GSHP systems are used for air-conditioning systems in commercial buildings, schools, and factories because of low operating and maintenance costs. These systems use the earth as a heat source in heating and a heat sink in cooling mode. Ground heat exchangers are classified by a horizontal and vertical type according to the installation method. Vertical type is usually constructed by placing small diameter high density polyethylene tube in a vertical borehole. Vertical tube sizes range from 20 to 40 mm nominal diameter. Borehole depth range between 100 and 200 m depending on local drilling conditions and available equipment. In this study, to evaluate the performance of single u-tube with bentonite grouting, single u-tube with broken stone grouting and double u-tube bentonite grouting of vertical ground heat exchangers, test sections are buried on the earth and experimental apparatus is installed. Therefore the heat transfer performance and pressure loss of these are estimated.

• Journal of Welding and Joining
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• 제27권5호
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• pp.62-67
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• 2009

Welding deformation during the assembly process is affected by not only local shrinkage due to rapid heating and cooling, but also root gap and misalignment between parts to be welded. Therefore, the prediction and control of welding deformation have become of critical importance. In this study, it was focused on the development of the 3-axis apparatus for real-time measurement of the welded deformation. To achieve the objective, a D-H algorithm has been carried out to check the behavioral and performance evaluation for the developed robot. The sequence experiments were taken the base materials of $400{\times}200{\times}4.5mm$ plate for butt welding. The real-time experimental measurements are in good agreement with the measured results.

• 에너지공학
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• 제8권2호
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• pp.233-241
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• 1999

온수생산을 위하여 기존의 강제순환식이 아닌 자연순환식 회로를 이용한 대형 온수생산 시스템을 개발하였다. 그리고 이 시스템의 설계와 성능평가를 위한 시뮬레이션 프로그램을 개발하여 실용화 가능성을 제시하였다. 실제규모의 성능실험에서 주어진 기하학적 조건하에 시스템이 정상상태 운전 시 보일러 가열량(695㎾)일 때, 급수 유량이 0.3$\ell$/s 로 일정하게 순환함을 보였다. 그리고, 비정상상태로 작동 할 경우 순환유량이 0.4~0.6 $\ell$/s 로 시스템이 불안정함을 실험을 통해 확인하였다. 개발된 프로그램과 대형의 온수생산 시스템의 성능평가의 비교.검증을 통하여 시뮬레이션 프로그램을 이용한 시스템 설계에 적용될 수 있음을 보였다.

• 한국식품과학회지
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• 제9권2호
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• pp.165-169
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• 1977

용액의 열처리 온도까지의 온도 상승시간과 열처리 후 냉각시간이 무시될 수 있을 정도로 단시간이어서 고온에서의 측정이 가능한 연속 살균장치를 이용하여 열처리온도 $110^{\circ}C$와 $140^{\circ}C$범위 내에서 horseradish peroxidase의 열에 의한 불활성화 속도와 열역학적 자료를 측정 수집하였다. 그 결과 peroxidase의 열에 의한 불활성화 enthalpy, 146.4kJ/mol, free enegy of activation 113 kJ/mol, entropy of activation 82.9 J/mol.k를 얻었다. 본 실험에서 얻은 자료를 기초로하여 일반 미생물 살균 그래프와 비교하고 고온 단시간 살균공정(HTST)에서 효소의 불활성화에 충분한 열처리 시간을 고려해야함을 토론하였다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 춘계학술대회
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• pp.466-469
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• 2007

Heat pumps are used for air-conditioning systems in commercial buildings, schools, and factories because of low operating and maintenance costs. These systems use the earth as a heat source in heating mode and a heat sink in cooling mode. Ground heat exchangers are classified by a horizontal type and vertical type according to the installation method. A horizontal type means that a heat exchanger is laid in the trench bored in 1.2 to 1.8 m depth. And a vertical type is usually constructed by placing small diameter high density polyethylene tube in a vertical borehole. Vertical tube sizes range from 20 to 40 mm nominal diameter. Borehole depth range between 100 and 200 m depending on local drilling conditions and available equipment. In this study, to evaluate the performance of single u-tube with bentonite grouting, single u-tube with broken stone grouting and double n-tube bentonite grouting of vertical ground heat exchangers, test sections are buried on the earth and experimental apparatus is installed. Therefore the heat transfer performance and pressure loss of these are estimated.

• 한국자동차공학회논문집
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• 제10권4호
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• pp.69-76
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• 2002

The aim of this study is to provide fundamental informations that make it possible to use a cool stream and a hot stream simultaneously. We changed the pressure of compressed air that flows into a tube, the inner diameter of orifice that a cold stream exits, and the mass flow rate ratio. And in each case, we measured the temperature of a cold stream and a hot stream in each exit of a tube. Also we measured the axial and the radial temperature distribution in internal spare of a tube. From the study, fellowing conclusive remarks 7an be made. First, As the number of nozzles increase, separation point move into the hot exit. Second, When we use guide vane type nozzle, the axial temperature distribution constant over the 0.75 of air mass flow rate radio. Third, When we use Spiral type nozzle, axial and radial temperature distribution in the inner space is higher than another nozzle. Fourth, Axial and radial temperature distribution in the inner space vortex-tube is determined by separation point. And separation point is moved by changing of air mass flow rate ratio. At last, A heating apparatus is possible far vortex-tube to use.

• 한국산학기술학회논문지
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• 제13권3호
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• pp.1275-1278
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• 2012

도전성 복합체의 최적 설계 요소와 세라믹 제조기법을 찾고 발열체 제작을 위한 기초기반 기술을 확보하였다. 제품 응용시 세라믹 발열체를 하나의 몸체로 제작하여 접촉 저항을 최대한 줄이면 시스 발열체보다 1.1배 느린 초기 상승 온도 속도를 높일 수 있고, 보온력에서는 SiC계 세라믹 발열체가 시스 발열체보다 약 2.7배 높기 때문에 제품의 사용 기간이 길어질수록 에너지 절감 효과를 얻을 수 있어, 경제성 면에서 대단히 유리하게 평가 된다.

• 태양에너지
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• 제2권2호
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• pp.11-20
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• 1982

This paper presents the experimental investigations of a system as a second treatment means to increase boiler efficiency and heat transfer from combustion gas to heating surfaces in the case of spray combustion. In order to reburn residual combustible components accelerate the burning rate of sprayed fuel droplets, improve the diffusion flame and delay the residence time of the flame, advice with slit type nozzles for spouting preheated supplementary air is used in this study. In the experiment, boiler efficiency and smoke concentration in the exhaust gas at given conditions are measured in both case of installing and not-installing device in the model of combustion chamber which was designed to be equipped with five surfaces. The results obtained in this experiment are as follows ; 1. The optimum values of air rate ${\lambda}$ are about 1.3 in both case. 2. The exhaust gas temperature in the case with device increases about $30{\sim}70^{\circ}C$ above that of the case without the device. 3. Boiler efficiency and reduction effect of smoke emissions are improved considerably.