• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 추계학술대회 논문집
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• pp.465-468
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• 2000

The procedure of semi-solid forming is composed of heating a billet, forming, compression holding and ejecting step. There are several methods to heat a billet during semi-solid forming process such as electric heating and induction heating. Usually in semi-solid forming process, induction heating has been adopted to achieve more uniform temperature of semi-solid material. Although induction heating is better method than any others, however, there is still difference of temperature between internal part and surface part of semi-solid material. Worse yet, in case of high liquid fraction of semi-solid material, liquid of the billet will flow down though solid of the billet still remains, which is very difficult to handle. In the present study, induction heating of semi-solid material with compulsive surface cooling has been performed to obtain uniform distribution of temperature. Distribution of temperature of the billets was measured and compared with that of conventional distribution of temperature. By this new induction heating method, not only temperature over the whole billet become uniform, but also control of temperature is possible.

• 동력기계공학회지
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• 제15권6호
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• pp.11-15
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• 2011

This study investigated the symptoms of the a reduction in output while driving on the road, or increasing of fumer out exhaust gas on inclined road while working air-conditioner in summer. Notice how the experiment in 2010, the Ministry of Environment(Chapter No. 2010-46), and how the vehicle emissions inspection was carried out. 2500cc Diesel cars used in the study were used and compare to output of engine, exhaust gas, inhalation temperature measurement Inhalation of cold air has not been supplied to all agencies when comparing the results when cold air intake temperature of the supply air-conditioning switch range control from 1 to 4, the temperature drops $98^{\circ}C$ to $78^{\circ}C$. At the momentum of switch level 4, output from 63ps to 66ps after the connection has increased 9.6 percent, the highest concentration of exhaust emissions were reduced by 42.8%. This research can contribute in part to the reduction of exhaust directly supply into the cooling air intake line, doing the output of diesel cars in the summer. In addition, construction equipment and machinery that are currently being used excluding the engine's intercooler cooling of the supply line via a separate output in the summer and help reduce exhaust emissions is expected.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2003년도 Proceedings of the international symposium on the fusion technology
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• pp.328-334
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• 2003

Evaluating stability of dam foundations is one of the prime areas of any rock engineering investigations. Despite best engineering efforts in the design and construction of dam foundations, the foundation regime of a constructed dam suffers deterioration due to continuous erosion from backwater current of dam discharge and dynamic effects of loading and unloading process. Even during construction, development of frequent cracks due to sudden thermal cooling of concrete blocks is not uncommon. This paper presents two case studies from India and Bhutan. In the first case, the back current of water discharge from the Srisailam dam in India had continuously eroded the apron and has eaten into the dam foundation. In the second case with dam construction at Tala Hydroelectric Project in Bhutan, sudden overflow of river during the construction stage of dam had led to development of three major cracks across the dam blocks. This was ascribed to adiabatic cooling effect of concrete blocks overlain by chilled water flow. Non-destructive evaluation of rock mass condition in the defect regime by the borehole GPR survey helped in arriving at the crux so as to formulate appropriate restoration plan.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권1호
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• pp.190-207
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• 2015

In the combustion engineering, to decrease pollution and increase production efficiency, and to optimally keep solid burning material amount constant in a burner online, it needs a smart method to detect the amount variation of the burning materials in a high temperature environment. This paper presents an online machine vision system for automatically measuring and detecting the burning material amount inside a burner or a boiler. In the camera-protecting box of the system, a sub-system for cooling is constructed by using the cooling water circulation techqique. In addition, the key and intelligent step in the system is to detect the pile profile of the variable burning material, and the algorithm for the pile profile tracing was studied based on the combination of the gey level (color) discontinuity and similarity based image segmentation methods, the discontinuity based sub-algorithm is made on the quaternion convolution, and the similarity based sub-algorithm is designed according to the region growing with multi-scale clustering. The results of the two sub-algoritms are fused to delineate the final pile profile, and the algorithm has been tested and applied in different industrial burners and boilers. The experiements show that the proposed algorithm works satisfactorily.

• Composites Research
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• 제14권2호
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• pp.33-42
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• 2001

DSC(differential scanning calorimetry)를 이용하여 S2-유리섬유/폴리에스터 프리프레그 복합재료의 경화반응식을 구성하였다. 구성된 경화식과 블리더의 수지 함침에 의한 열전달 조건의 변화를 고려하여, 두꺼운 복합재료의 두께 방향 위치에 따른 온도분포를 계산하였다. 유래섬유 복합재료의 경화중 온도과승을 줄이기 위한 방법으로 냉각 및 재가열 구간을 도입하여 경화 사이클을 개선하였다. 냉각-재가열 구간이 없는 기존의 경화 사이클과 개선된 경화 사이클로 두꺼운 복합재료를 각각 제조하여 short beam shear 시험 및 Barcol 경도시험을 실시하고, 그 결과를 비교하였다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2004년도 추계학술대회논문집
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• pp.294-297
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• 2004

RTP(Rapid Thermal Pressing) is to fabricate desired pattern on polymer substrate by pressing patterned mold against the substrate heated around glass transition temperature. For a successful RTP process, the whole process including heating, molding, cooling and demolding should be conducted 'rapidly' as possible. As the RTP process is effective in replicating patterns on flat large surface without causing shape distortion after cooling, it is being widely used for fabricating various micro/bio application components, especially with channel-type microstructures on surface. This investigation finally aims to develop a RTP process machine for mass-producing micro/bio application components. As a first step for that purpose, we intended to examine the technological difficulties for realizing mass production by RTP process. Therefore, in the current paper, 4 kinds of RTP machines were examined and then the RTP process was conducted experimentally for PMMA film by using one of the machines, HEX 03. The micro-patterned molds used for RTP experiment was fabricated from silicon wafer by semi-conduct process. The replicated micro patterns on PMMA films were examined using SEM and the causes of defect observed in the replicated patterns were discussed.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제41회 하계 정기 학술대회 초록집
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• pp.157-157
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• 2011

Graphene has generated significant interest in the recent years as a functional material for electronics, sensing, and energy applications due to its unique electrical, optical, and mechanical properties. Much of the considerable interest in graphene stems from results obtained for samples mechanically exfoliated from graphite. Practical applications, however, require reliable and well-controlled methods for fabrication of large area graphene films. Recently high quality graphene layers were fabricated using chemical vapor deposition (CVD) on nickel and copper with methane as the source of the carbon atoms. Here, we report a simple and efficient method to synthesize graphene layers using solid carbon source. Few-layer graphene films are grown using filtered vacuum arc source (FVAS) technique by evaporation of carbon atom on Ni catalytic metal and subsequent annealing of the samples at 800$^{\circ}$C. In our system, carbon atoms diffuse into the Ni metal layer at elevated temperatures followed by their segregation as graphene on the free surface during the cooling down step as the solubility of carbon in the metal decrease. For a given annealing condition and cooling rate, the number of graphene layers is easily controlled by changing the thickness of the initially evaporated amorphous carbon film. Based on the Raman analysis, the quality of graphene is comparable to other synthesis methods found in the literature, such as CVD and chemical methods.

• 한국가스학회지
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• 제8권4호
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• pp.42-49
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• 2004

최근 디젤연료대체용으로 각광을 받고 있는 DiMethylEther(DME)를 천연가스로부터 얻어지는 합성가스를 이용하여 직접 생산하는 1단계법의 고정층 촉매 반응기를 시뮬레이션하였다. 그 결과 과잉냉각시 반응기의 온도가 떨어져서 전체적인 반응이 둔화되며, 강제 냉각을 하지 않을 경우 급격한 온도상승으로 인해 역시 반응효율이 떨어지게 된다는 것을 알 수 있었다. 또한, 냉각효과 및 반응물의 공간속도 및 반응물의 온도등의 조건에 따른 최적운전조건을 수립할 수 있었다.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.199-200
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• 2006

PM recent developments focus on increasing this technology's competitiveness when compared to wrought materials. Warm compaction allows the replacement of a double press double sinter process with a single warm press and sintering step, thus allowing cost and time savings. Moreover there are added benefits to consider such as reducing work in process and lessening part's logistics cost. This paper presents a successful industrial trial to replace a double press-double sinter process with a warm die compaction and sintering process. The part chosen was a high performance gear containing 0,9% wt. carbon. Sintering was conducted in a belt furnace at $1120^{\circ}C$ in a nitrogen rich atmosphere with rapid cooling process in order to obtain a quasi fully martensitic structure with a minimum of 700HV0,1 and 450HV10 after annealing. The balance between properties and cost is favoured by the use of a singular lubricant developed in a Eureka frame project together with POMETON S.A. and die warm compaction. Warm compaction is only needed to be effective on the gear teeth, in order to achieve the required properties. Therefore only the die is actually heated. This simplified system avoids flow rate problems typically involved when using more elaborate warm compaction equipments.

• Journal of the Korean Physical Society
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• 제73권9호
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• pp.1346-1350
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• 2018

An electrode-evaporation technology on both the top and bottom sides of the bare vertical-type single chip separated from the traditional substrate by cooling, was developed for III-nitride vertical-type single chip LEDs with thick GaN epilayer. The post-process of the cooling step was followed by sorting the bare vertical-type single chip LEDs into the holes in a pocket-type shadow mask for deposition of the electrodes at the top and bottom sides of bare vertical-type single chip LEDs without the traditional substrate for electrode evaporation technology for vertical-type single chip LEDs. The variation in size of the hole between the designed shadow mask and the deposited electrodes owing to the use of the designed pocket-type shadow mask is investigated. Furthermore, the electrical and the optical properties of bare vertical-type single chip LEDs deposited with two different shapes of n-type electrodes using the pocket-type shadow mask are investigated to explore the possibility of the e-beam evaporation method.