• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2005년도 춘계학술대회
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• pp.684-687
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• 2005

Ground source heat pump systems are used for heating, ventilating and 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. The solar heat and the rainwater are affected by the performance of heat exchanger and causes mutual influence among heat exchangers. In this study, to evaluate the performance of straight type, slinky type, and spiral type of horizontal ground heat exchangers designed on 1 RT scale, test sections are buried on the earth and experimental apparatus is installed. Therefore the performance of these is estimated.

• 대한한의학회지
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• 제16권1호통권29호
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• pp.370-378
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• 1995

In order to consider the clinical efficacy of moxa combustion, understand the quality and quantity of heat stimulation and get the basic data for the development of electric moxibustion apparatus, the pattern of combustion temperature was measured by size of moxa(small, medium, large and maximum size). The results were as follows. 1. The pattern of combustion temperature by moxa burning was classified into input period, consisting of preheating and heating periods, and output period, consisting of heat retaining and cooling periods, in all experimental groups. But it was difficult to observe the preheating period in small sized moxa. 2. It was inclined that the more moxa size was large, the more the heating and heat retaining periods were long and the maximum temperature was high. The characteristics of moxa combustion is primarily by the rate of combustion temperature, gradient temperature and duration of combustion, and their correlation among these factors and their clinical effects in practice.

• 한국산학기술학회논문지
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• 제12권1호
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• pp.26-31
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• 2011

본 논문은 기존의 스파크 점화 방식이 아닌 bulk combustion 방식을 도입하여 별도의 점화장치 없이 상용 단기통 디젤기관에 유입되는 흡입공기를 가열 및 제어하여 흡기관에 분사되는 가솔린연료의 압축착화성을 향상시킴으로서 기관작동을 가능하게 하였다. 제동열효율의 최대값은 공기-연료비가 35부근에서 나타나며, 35이상의 영역에서는 급격히 감소하고 흡입공기 가열온도가 올라갈수록 제동열효율은 증가한다. 따라서 공기-연료비를 감소시키면서 흡입공기의 가열온도를 상승시키는 방식이 열효율 측면에서 효과적이라는 것을 알 수 있다.

• 대한기계학회논문집B
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• 제25권2호
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• pp.244-251
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• 2001

This paper describes a design study of heat exchanger assembly to be used for low NOx condensing gas boiler. In this study, specifications of each heat exchanger components(upper and lower fin-type HEX, coil-type HEX, baffle) were investigated experimently by using model apparatus and analytical model, and comprehensive performances of the pilot gas boiler were examined. As a result, the boiler efficiency for heating and hot-water reached 90% and 94%, respectively. NOx and CO emission are less than 50ppm and 200ppm (0$_2$0% basis), respectively, which are very improved results than those of conventional bunsen-type boiler. But it is considered that supplementary investigations necessary for CO emission improvement and optimum design with boiler capacity.

• Preventive Nutrition and Food Science
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• 제20권2호
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• pp.102-109
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• 2015

In order to investigate the thermal degradation of glucose and maltose solutions after high temperature and high pressure (HTHP) treatment, the samples were treated at temperatures of 110, 120, 130, 140, and $150^{\circ}C$ for 1, 2, 3, 4, and 5 h in an apparatus for HTHP treatment. Glucose and maltose solutions (20% w/w) were prepared by weighing glucose and maltose and adding distilled water in the desired proportion. Chromaticity, pH, organic acids, 5-hydroxymethylfurfural (HMF), free sugar contents, electron donating ability (EDA), and ascorbic acid equivalent antioxidant capacity (AEAC) were evaluated. With increasing heating temperatures and times, the L-, a-, and b-values decreased. The pH and free sugar contents decreased, and organic acids and HMF contents increased with greater temperatures and times. EDA (%) and the AEAC of the heating sugars increased with the increases in temperatures and times.

• 소성∙가공
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• 제17권8호
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• pp.570-578
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• 2008

A flexible forming apparatus is composed a number of punches which have spherical pin tip shape instead of conventional solid die. The flexible forming tool consisted of punch array in a matrix form was proposed as an alternative forming method to substitute the conventional line heating method which use heat source to induce residual stress along specified heating lines. In this study, application of the flexible forming process to the small scale curved plate forming was conducted. Numerical simulations for both solid and flexible die forming process were carried out to compare the shape of the products between flexible and conventional die forming process. In addition, spring-back analysis was conducted to figure out the feasibility of the flexible forming process comparing with the die forming process in view of final configuration of the specimens. Moreover, experiment was also carried out to confirm the formability of the process. Consequently, it was confirmed that the flexible die forming method has capability and feasibility to manufacture the curved plates for shipbuilding.

• 신재생에너지
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• 제16권2호
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• pp.47-53
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• 2020

The amount of food waste and its water content depends on both the season and region. In particular, the water content typically varies between 73.8 wt.% and 83.3 wt.%, depending on the proportion of vegetables. Current food waste drying technologies are capable of reducing the water content to less than 10 wt.%, while increasing the heating value. Ongoing studies aim to utilize dried food waste as fuel. Food waste can be used to produce solid refuse fuel (SRF) by mixing it with various solid fuels or other types of waste. The analysis of specimens is very important when considering the direct combustion of food waste or its co-firing with solid fuels. In this study, the weight reduction of specimens after burning them in a small combustor, and compared with the results of thermogravimetric analysis (TGA). The concentration of various chemicals was also measured to define the characteristics of waste generation. Performed proximate analysis, elemental analysis, TGA, combustion experiment, the heating value, and derivative thermogravimetry (DTG).

• 한국가스학회지
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• 제17권5호
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• pp.69-74
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• 2013

본 연구에서는 Mg분진의 분진입경과 승온속도에 따른 열분해 및 발화온도 특성을 실험적으로 조사하였다. 이를 위해 시료는 평균 입경이 서로 다른 38, 142, $567{\mu}m$의 Mg분진을 사용하였다. 실험에서는 열중량분석장치(TGA)와 IEC 61241-2-1규격에 따라 제작한 자연발화온도(MIT) 실험장치를 사용하여 실시하였다. 실험 결과 퇴적 Mg에 있어서 공기중 승온속도가 증가하면 중량개시온도는 증가하였으며, 동일한 승온속도 조건에서 입경의 증가는 발화온도의 증가로 나타났다. 또한 부유 Mg분진의 최저발화온도(MIT)는 평균 입경이 증가할수록 증가하는 경향을 보였다.

• 한국기계가공학회지
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• 제19권10호
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• pp.44-51
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• 2020

We studied the heating characteristics of a whirling spindle. This spindle is an important component of a whirling machine for turning a ball screw shaft. In the manufacturing process for a conventional ball screw shaft, a single tool is used to form a spiral in a lathe machine tool. Thereafter, a high-frequency heat treatment process is performed. Recently, a whirling-type cutting method has emerged. This method can perform hard turning in the rotating direction of the spiral portion of the ball screw shaft by rotating and mounting multiple tools. The whirling method can be applied to the heat-treated material. In this study, an experimental apparatus was constructed to analyze the whirling spindle. The experiment proceeded in four steps. The rotating speed of the whirling spindle was set to ISO random and sequential rising conditions. Cooling and non-cooling modes in the cooling jacket were tested. As a result of the above experiment, the heating characteristics of the whirling spindle were derived.

• 한국융합학회논문지
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• 제6권6호
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• pp.241-246
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• 2015

추운 겨울철 실내를 따뜻하게 해주는 발열 및 난방기구들은 필수적인 요소이며, 2000년대부터 이러한 난방기구들의 사용량은 급격하게 증가하고 있다. 하지만, 화재 사고와 화재의 위험성 역시 증가하고 있다. 따라서 본 연구에서는 보다 안전한 난방기구의 설계를 위하여 시중에서 판매되는 세라믹, 카본 및 근적외선 히터들로서의 세 가지 형상의 전기히터들을 참고하여 3D 모델링하였으며, 이들 모델들을 가지고 열 해석을 수행하여 열변형량과 열응력 등에 따른 내구성을 연구하였다. 본 연구에서 도출된 연구 결과들을 바탕으로 각 형상에 따른 전기히터 모델들의 내구성을 예측할 수 있었고, 궁극적으로 보다 안전한 내화성이 있는 새로운 난방기구의 개발에 기여할 수 있었다. 또한 디자인 면에서 융합 기술로의 접목도 가능하여 미적인 감각을 나타낼 수 있다.