• 설비공학논문집
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• 제17권4호
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• pp.370-376
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• 2005

For the purpose of investigating the effective removal of heating/cooling load from light-weighted building envelope, two air-conditioning systems, conventional parameter air-conditioning system and air-barrier system, are evaluated and compared by both experiment and simulation with six different cases during heating and cooling season. In addition, the characteristics of window-side building thermal load are assessed by varying supply air velocity in order to seek the optimal system operation condition. The results are as follows. 1) Air-barrier system is more effective to remove heating/cooling load at perimeter zone than conventional parameter air-conditioning system. Moreover, the better effectiveness appears during cooling season than during heating season. 2) The experiment during cooling season provides that indoor temperature of air-barrier system shows $1^{\circ}C$ less than that of the conventional system with similar outdoor air temperature profile, and indoor temperature distribution is more uniform throughout the experimented model space. It concludes that air-barrier system can achieve energy saving comparing to the conventional system. 3) The capturing efficiency of air-barrier system is 0.47 on heating season and 0.2 on cooling season with the same supply air volume. It results that the system performs effectively to remove building thermal load, moreover demonstrates high efficiency during cooling season. 4) The simulation results provide that capturing efficiency to evaluate the effective removal of building load from perimeter zone shows high value when supply air velocity is 1 m/s.

• 한국분말재료학회지
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• 제23권1호
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• pp.1-7
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• 2016

Cu-Mn compacts are fabricated by the pulsed current activated sintering method (PCAS) for sputtering target application. For fabricating the compacts, optimized sintering conditions such as the temperature, pulse ratio, pressure, and heating rate are controlled during the sintering process. The final sintering temperature and heating rate required to fabricate the target materials having high density are $700^{\circ}C$ and $80^{\circ}C/min$, respectively. The heating directly progresses up to $700^{\circ}C$ with a 3 min holding time. The sputtering target materials having high relative density of 100% are fabricated by employing a uniaxial pressure of 60 MPa and a sintering temperature of $700^{\circ}C$ without any significant change in the grain size. Also, the shrinkage displacement of the Cu-Mn target materials considerably increases with an increase in the pressure at sintering temperatures up to $700^{\circ}C$.

• 한국기계가공학회지
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• 제14권4호
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• pp.8-13
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• 2015

In this study, we fabricated and characterized a nanostructured surface based on a plastic injection molding with a local mold heating (LMH) system. A metal mold core with a closed packed nano convex array (CVA) was achieved by integrated engineering procedures: (1) master template fabrication by anodic aluminum oxidation (AAO), (2) nickel electroforming (NE) process, and (3) post-processing by precision machining. The nickel mold core was utilized to replicate a surface with a closed packed nano concave-array (CCA) based on injection molding using cyclic olefin copolymer (COC) as a plastic material. In particular, an LMH system was introduced to enhance transcription quality of the nano structures by delaying solidification of molten polymer near the surface of the mold core.

• 한국조리학회지
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• 제14권3호
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• pp.196-209
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• 2008

This study was conducted to mass-produce brown stock optimized by using a high-pressure heating extractor and to use brown stock as a material for developing various products. For these purposes, we attempted to produce standardized brown stock by extracting brown stock using a high-pressure heating extractor and compared it with brown stock extracted by the traditional method in terms of general elements and mechanical and sensory characteristics. With regard to how to prepare optimal brown stock, the best brown stock was that extracted seven times repeatedly by the traditional method, but the method had a large economic loss in terms of material consumption and took a long time in extraction. Thus, considering time and labor, it was concluded that extraction at 120$^{\circ}C$ for 15 hours using a high-pressure heating extractor is the optimal extraction condition in terms of economic efficiency and quality. The results of this study are expected to be useful as a practical material for making brown stock production process more convenient, applying cooks' traditional cooking techniques to mass production, maintaining standardized superior quality and taste, and improving shelf life.

• 한국세라믹학회지
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• 제41권11호
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• pp.804-811
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• 2004

본 연구는 colemanite원광을 출발원료로 하여 붕산을 추출하는 공정에서 마이크로파 적용에 대한 연구로, 황산을 첨가하고 가열하여 colemanite의 칼슘 성분을 황산칼슘으로 분리하여 내고, 액상에 존재하는 붕소 성분은 붕산으로 재결정화 하여 제조하였다 Colemanite에 황산을 첨가해 가열하는 공정에 마이크로파를 적용하면, 일반 가열원을 사용하였을 때와 비교하여 적은 양의 황산을 사용하여 추출이 가능하고, 가열시간을 단축하는 것이 가능하였다. 생성된 붕산의 순도는 일반 가열원을 사용하였을 때와 동등한 수준이고 열 특성 또한 동일하였으나, 입자의 크기는 작아졌다.

• 한국재료학회지
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• 제17권2호
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• pp.91-95
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• 2007

Electromigration characteristics of Sn-3.5Ag flip chip solder bump were analyzed using flip chip packages which consisted of Si chip substrate and electroplated Cu under bump metallurgy. Electromigration test temperatures and current densities peformed were $140{\sim}175^{\circ}C\;and\;6{\sim}9{\times}10^4A/cm^2$ respectively. Mean time to failure of solder bump decreased as the temperature and current density increased. The activation energy and current density exponent were found to be 1.63 eV and 4.6, respectively. The activation energy and current density exponent have very high value because of high Joule heating. Evolution of Cu-Sn intermetallic compound was also investigated with respect to current density conditions.

• Journal of Advanced Marine Engineering and Technology
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• 제31권5호
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• pp.558-566
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• 2007

The performance characteristics of water-chilling heat pump using $CO_2$ with respect to variation of refrigerant charge amount was investigated experimentally. An experimental apparatus is consisted of a compressor, a gas cooler, an expansion valve, an evaporator and a liquid receiver. All heat exchangers used in the test rig are counter-flow-type heat exchangers with concentric dual tubes, which are made of copper. The gas cooler and the evaporator consist of 6 and 4 straight sections respectively arranged in parallel, each has 2400 mm length. The experimental results summarize as the followings : As the refrigerant charge ratio of $CO_2$ heat pump system increases, the discharge pressure and compressor ratio increases, but mass flow rate of refrigerant decreases. Also the compressor work increases with the increase of refrigerant charge ratio. However, the heating and cooling capacity of $CO_2$ heat pump decreases as the refrigerant charge ratio increases. The maximum heating COP of $CO_2$ heat pump system presented at 0.25 refrigerant charge ratio. It is possible to confirm the optimum charge ratio of $CO_2$ heat pump system by the viewpoint of heating COP.

• 대한조선학회논문집
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• 제42권5호
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• pp.472-478
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• 2005

From a rapid cooling to a slow cooling in the actual cooling process in shipyards, the phase of steel becomes martensite, bainite, ferrite, and pearlite. In order to simulate the cooling process, heat transfer analysis was performed considering the effects of impinging water jet, film boiling, and radiation. From above simulation it is possible to find the cooling speed at the inherent strain region and volume percentage of all phases in that region. By the suggested method based on the precise material properties calculated from volume percentage of all phases, it will be possible to predict the plate deformations by line heating more precisely. It is verified by comparing with some experimental results that the present method is very effective and efficient.

• 대한한방부인과학회지
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• 제20권3호
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• pp.238-245
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• 2007

Purpose: In postpartum period, women are very weak and liable to various diseases. So postpartum care is very important. But excessive heating and sweating cause postpartum diseases. Methods: The patient in this case, 37 years-old female was in Kyunghee University East-West neo medical center for 8days(27th/Oct/2006 - 3rd/Nov/2006). Her chief complains when she was admitted in the hospital were sweating, chilling, and mild dizziness. These symptoms were caused by excessive heating and sweating. We thought that her condition was deficiency of Qi. After giving her the therapies with herb medicine, acupuncture and moxibustion, her symptoms got almost disappeared and her condition got better. Results: After the oriental medical treatment, the clinical symptom of postpartum disease was improved. Conclusion: This case study shows that excessive heating and sweating cause postpartum diseases and the oriental medical therapy is effective in treating postpartum disease. And the guideline of postpartum care is needed.

• 전력전자학회논문지
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• 제27권3호
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• pp.256-264
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• 2022

The frequency power control method (FCM) which has a wide operating frequency range is adopted for induction heating (IH) cooktops. When FCM is applied to the full-bridge series resonant converter (FB-SRC) based IH system, high-frequency switching of the inverter is required compared to the half-bridge SRC (HB-SRC)-based IH system. Therefore, the switching loss of the inverter increases, and applying FCM under the condition that the inverter operating frequency range is limited is difficult. Therefore, this paper proposes a control strategy with the phase shift power control method considering that limited frequency conditions are presented. Loss analysis following the control method is performed through simulation and mathematical analysis. In addition, the validity of the proposed control strategy is verified by analyzing the heating performance following the control method through the test results of the 3,200[W] prototype.