• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2007년도 동계학술발표대회 논문집
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• pp.222-228
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• 2007

The effect of inclination angle on the heat transfer and pressure drop characteristics of brazed aluminum heat exchangers is experimentally investigated. Three samples having different fin pitches (1.25, 1.5 and 2.0 mm) were tested. Results show that heat transfer coefficient is not affected by the inclination angle. However, the friction factor increases as the inclination angle increases with negligible difference between the forward and backward inclination. Both the heat transfer coefficient and the friction factor are the smallest at $P_f$=1.5mm, followed by $P_f$=2.0mm and 1.25mm. Possible explanation is provided considering the louver layout. Comparison with existing correlations is also mad.

• 대한조선학회논문집
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• 제45권3호
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• pp.303-308
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• 2008

The induction heating is more efficient for a plate bending because of its easy operation and control of working parameters, compared with the heating by a gas torch. The existing axis symmetric analysis method could neither handle initial curved plates nor be used in the optimization of coil shapes because of its limit of an axis symmetric coil shape. But the proposed method using some discrete part models and analysis processes could overcome these difficulties and show more accurate results in temperatures and deflections of flat or curved plates with initial curvature than those in the existing axis symmetric analysis method. This method is composed of the multi-disciplinary analyses such as an electro magnetic analysis, a heat transfer analysis and a deformation analysis based on inherent strain approach per each step. Traditionally, the coil shape in the induction heating is circular shape and it needs the moving process along heating lines. To overcome this, the 'Long Type Coil' with some linear parallel coils was proposed. It did not need the moving process along heating lines and reduced the heating process time. The results of experiments were compared with those of the simulation.

• 한국정보처리학회논문지
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• 제6권9호
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• pp.2548-2557
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• 1999

평판 디스플레이 분야의 발달로 대형화와 고해상도화가 진행됨에 따라 이에 알맞은 새로운 개념의 평판 디스플레이를 위한 컨트롤러가 필요하게 되었다. 이에 본 논문에서는 평판 디스플레이 중에서 가장 많은 비중을 차지하는 TFT LCD를 위한 SXGA급 해상도를 지원하는 컨트롤러를 설계하였다. 병렬 버스 구조의 새로운 LCD 컨트롤러의 구조를 제시하였으며, 저해상도 화면을 SXGA급 해상도의 화면으로 확대할 수 있도록 설계하였다. 또한 Synopsys VHDL을 이용하여 제안한 컨트롤러의 기능 검증 및 회로 합성을 수행하였다.

• 대한건축학회연합논문집
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• 제21권4호
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• pp.139-146
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• 2019

The purpose of this study is to propose the building design guideline considering photovoltaic panel installation through the analysis of relevant guidelines from home and abroad in terms of building design and solar panel installation. Conclusions can be summarized as followings; Considerations in building design : selection of the site with high solar accessibility, avoidance of the shade from the adjacent building & trees, south facing orientation of solar panel in building design, removal of shade on the solar panel from the part of building itself, load consideration of solar panel & fixing materials, safe passage securement for solar system maintenance, and planning of piping and mechanical room for solar system. Considerations in solar panel installation : harmonizing of solar panel with surrounding environment, unity of solar panel orientation & slope, regular maintenance of solar system, (in case of flat roof installation) solar panel installation afloat over the roof, installation area within the roof floor, and lower than parapet height, (in case of sloped roof installation) solar panel installation parallel with the roof slope, ventilation space securement below the panel, installation area within the roof surface, and similar material installation in empty space.

• 헤리티지:역사와 과학
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• 제49권3호
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• pp.78-103
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• 2016

본 연구는 부석사 무량수전의 측면 지붕부 결구 구조에 관한 연구이다. 부석사 무량수전은 일제시대에 해체 보수한 기록이 있으며, 팔작지붕의 측면 지붕부 결구 구조기법과 추녀, 귀서까래 등의 결합 수법들이 정연한 형태로 결구되지 않고, 조선시대 팔작지붕의 측면 지붕부 결구구조와 이질적인 요소가 많아 원형이 아닌 것으로 끊임없이 제기되어 왔다. 또한, 그 편년에 대해 다양한 의견(13세기, 12세기 건축)들이 국내외 학자들에 의해 제시되어 왔었다. 본 연구는 동아시아 목조건축 구조틀이라는 관점에 근거하여, 중국 당 송대 팔작지붕에서 부석사 무량수전과 측면 지붕부 결구구조 기법과 유사한 건축을 대상으로 평면비 및 어칸과 퇴칸의 비례를 상호 비교하여 살펴 본 결과 부석사 무량수전의 측면 지붕부 결구구조는 팔작지붕에서도 볼 수 있는 기법으로 판단하였다. 부석사 무량수전처럼 측면 서까래가 내부 보(량(梁))에 직접 접하는 기법은 중국 당 송대 팔작지붕 건축에서도 흔하게 볼 수 없는 수법으로, 중국의 팔작지붕은 당대(唐代) 이후에 산화(山花, 합각) 양가(梁架)를 구성하여 팔작지붕의 측면을 구성하는 기법이 발달되어, 명청대 이전까지 크게 발전된 것으로 보인다. 또한 귀서까래의 발달과정 중 평행서까래에서 말굽서까래로 전환되기 이전 방식인 평행복사연(平行輻射椽)이 현재 부석사 무량수전의 귀서까래 방식과 유사한 것으로 보인다. 다만, 추녀의 중간부분부터 귀서까래가 걸치지 않는 부석사 무량수전의 방식은 중국에서도 현재까지 확인되지 않은 방식으로 부석사 무량수전의 특성으로 보인다. 이런 기법들을 살펴본 결과 부석사 무량수전의 측면 지붕부 결구구조는 중국 남방지역에서는 볼 수 없으며, 북방 지역의 당 송대(唐 宋代) 및 요대(遼代) 시기에 볼 수 있는 기법으로, 건축물의 편년시기와 평면에서 어칸과 퇴칸의 비례 관계를 고려해볼 때 동아시아 북방지역에서 볼 수 있는 고식(古式)의 구조 기법으로 판단된다. 부석사 무량수전의 측면 지붕부 결구구조가 변형된 것이 아니고, 팔작지붕 고유의 방식일 가능성이 있는 만큼 향후 부석사 무량 수전의 평면과 어칸 및 퇴칸의 비례, 측면 지붕부 결구구조를 중심으로 고려시대 이전 폐사지 중 팔작지붕으로 추정되는 건물의 측면 지붕부 결구구조에 대해 복원 설계에 좋은 참고가 될 것으로 보인다.

• Journal of Biosystems Engineering
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• 제41권2호
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• pp.108-115
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• 2016

Purpose: Radio frequency (RF) heating is a promising thawing method, but it frequently causes undesirable problems such as non-uniform heating. This can occur because of the food shape, component distribution, and initial temperature differences between food parts. In this study, RF heating was applied to the thawing of cylindrically shaped pork sirloin by changing the shape of electrodes and the surrounding temperature. Methods: Curved electrodes were utilized to increase the thawing uniformity of cylindrically shaped frozen meat. Pork sirloin in the shape of a half-circle column was frozen in a deep freezer at $-70^{\circ}C$ and then thawed by RF heating with flat and curved electrodes. In order to prevent fast defrosting of the food surface by heat transfer from air to the food, the temperature of the thawing chamber was varied by -5, -10, and $-20^{\circ}C$. The temperature values of the frozen pork sirloin during RF thawing were measured using fiber-optic thermo sensors. Results: After multiple applications of curved electrodes resembling the food shape, and a cooled chamber at $-20^{\circ}C$ the half-cylindrically shaped meat was thawed without surface burning, and the temperature values of each point were similarly increased. However, with the parallel electrode, the frozen meat was partially burned by RF heating and the temperature values of center were overheated. The uniform heating rate and heat transfer prevention from air to the food were crucial factors for RF thawing. In this study, these crucial factors were accomplished by using a curved electrode and lowering the chamber temperature. Conclusions: The curved shape of the electrode and the equipotential surface calculated from the modeling of the parallel capacitor showed the effect of uniform heating of cylindrically shaped frozen food. Moreover, the low chamber temperature was effective on the prevention of the surface burning during RF thawing.

• 한국의학물리학회지:의학물리
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• 제13권4호
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• pp.202-208
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• 2002

본 논문에서는 표면조직에 있는 종양 치료 시 사용되고 있는 고에너지 전자선의 monitor unit을 다양한 방법에 의해 계산하여 평가 하고자 한다. 본 병원에서 6, 9, 그리고 12 MeV 전자선으로 치료한 33명의 유방암 환자가 선택되었다. 각 환자마다 모의 치료기에서 얻어진 시뮬레이션 필름에 불규칙한 모양의 전자선 블록이 제작되었다. 이러한 불규칙한 모양의 블록을 이용하여 최대선량 깊이에 100 cGy의 선량을 주기 위해 필요한 monitor unit 이 3차원 치료계획 시스템 (Pinnacle 6.0, ADAC Lab)을 사용하여 계산되었고 측정되었다. 선원과 표면 거리(SSD)가 100 cm 인 곳에서 plane parallel (PP) 이온전리함(Roos, OTW Germany) 을 사용하여 고체 물 팬텀 내에서 측정하였다. 불균등 조직에 대한 효과를 평가하기 위해 CT 데이터를 사용하였고 monitor unit을 균등조직 및 비균등조직 내에서 계산하였다. 균등조직으로 계산하기 위해 CT의 밀도를 1 g/㎤로 지정하였다. 이러한 방법에 의해 구해진 monitor unit 값들을 비교하였다. 한 지점에서 측정된 선량과 RTP에서 구해진 선량을 비교 할 때 측정된 값이 치료계획에 의해 계산된 값보다 조금 높았다. 평평한 고체 물 표면에 조사된 경우 측정된 값과 계산된 값에는 6 MeV 전자선의 경우 4%, 그리고 9 및 12 MeC 전자선의 경우 2%의 차이가 있었다. 또한 다양한 조사방향에서 CT 데이터를 사용하여 monitor unit을 계산한 경우 불균등한 조직의 밀도를 고려하여 계산된 값과 고려하지 않고 계산된 값은 모든 에너지에서 3% 이내의 차이가 있었다. 이러한 결과는 전자선을 사용하여 유방암 치료 시 조직내의 불균등한 밀도를 고려하지 않고 monitor unit을 계산해도 큰 차이가 발생하지 않는다는 것을 의미한다.

• Radiation Oncology Journal
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• 제1권1호
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• pp.41-45
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• 1983

To obtain 7 MeV electron beam which is suitable for treatment of the chest wall after radical of modified radical mastectomy, the authors reduced the energy of electron beam by means by Lucite plate inserted in the beam. To determine the proper thickness of the Lucite plate necessary to reduce the energy of 9 MeV electron beam to 6 MeV, dosimetry was made by using a parallel plate ionization chamber in polystyrene phantom. Separation between two adjacent fields, 7 MeV for chest wall and 12 MeV for internal mammary region, was studied by means of film dosimetry in both polytyrene phantom and Humanoid phantom. The results were as follows. 1. The average energy of 9 MeV electron beam transmitted through the Lucite plate was reduced. Reduction was proportional to the thickness of the Lucite plate in the rate of 1.7 MeV/cm. 2. The proper thickness of the Lucite plate necessary to obtain 6 MeV electron beam from 9 MeV was 1.2 cm. 3. 7 MeV electron beam, 80% dose at 2cm depth, is adequate for treatment of the chest wall. 4. Proper separation between two adjacent electron fields, 7 MeV and 12 MeV, was 5mm on both flat surface and sloping surface to produce uniform dose distribution.

• 대한기계학회논문집
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• 제7권4호
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• pp.425-433
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• 1983

Fatigue tests by axial loading (R=0.1) were carried out to investigate fatigue crack growth properties of small surface cracks in mild steel at room temperature, 250.deg. C and 400.deg. C, by using flat specimens with a small artificial pit. All the data of the fatigue crack growth rate obtained in the present tests are determined as a function of the stress intensity factor range, so that the applicability of liner fracture mechanics to the fatigue crack growth of surface cracks at elevated temperatures is investigated and discussed in comparison with the data of type 304 stainless steel at room temperature and elevated temperature. The obtained results are as follows: 1) Relations of both surface fatigue crack length and its depth to cycle ratio fall within a narrow scatter band in spite of different stress levels. 2) The .DELTA. .sigma. .root. .pi. a-da/dN relation of surface fatigue crack growth at room temperature is independent of the stress level and can be plotted as a straight line at log-log diagram, but the relation at 400.deg. C depends partly on the stress level. 3) Relations of the fatigue crack growth into depth d(2b)/dN and is stress intensity factor range .DELTA. $K_{I}$, accounted for the aspect ratio variation, fall within a narrow scatter band for wide range of the applied stress levels. And .DELTA. $K_{I}$E-d(2b)/dN relations of mild steel at different stress level coincide relatively well with the data of type 304 stainless steel. 4) The value of aspect ratio obtained by a beach mark method and a temper coloring method approaches about 0.9 in common with crack growth and it is independent of stress level and temperatures. 5) The equi-crack length curve is parallel to S-N$_{f}$ curve at elevated temperatures.s.s.s.

• 한국경영과학회지
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• 제3권1호
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• pp.31-46
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• 1978

Consider a time interval during which the demand for trips is fixed (e.g. the rush hour period). The traveller has a choice between various public modes, whose travel times and fares are fixed, and the automobile mode, for which travel time and cost depend on the volume of traffic flow on those roads, which are subject to congestion. We consider the equilibrium in terms of a representative travellerm, who choses for any trip the mode and route with the least combined money and time cost. When several (parallel) model or routes are chosen, then the combined cost of money and time must be equal among these. Our problem is first, to find the optimal flows of cars and of public mode carriers on the various links of their networks and second the optimal fares for trips by the variousmodes. The object is to minimize the total operating costs of the carriers and car plus the total time costs to travellers. The optimal fares are related to, but not identical with the dual variables of the underlying Nonlinear Program. They are equal to these dual variables only in the case, when congestion tolls on trips or on the use of specific roads are collected from automobile users. When such tolls are not collected, they must be passed on as subsidies to travellers using competing modes. The optimal fares of public modes are then reduced by the amounts of these subsidies. Note that subsidies are not a flat payment to public carriers, but are calculated on the basis of tickets sold. Fares and subsidies depend in general on tile period considered. They will be higher during periods of higher demand. When the assumption of fixed trip demand is relaxed, this tare system is no longer best, but only second best since too much traffic will, in general, be generated. The Free Rider Theorem states the following : Suppose road tolls can be charged, so that a best pricing system for public modes is posssible. Then there may exist free rides on some routes and modes, but never on a complete round trip.