• Clinical and Experimental Pediatrics
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• 제50권7호
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• pp.655-659
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• 2007

목 적 : 만성 복통으로 병원에 내원한 환아들에서 그 원인을 밝히고 Rome III 기준에 의해 진단된 기능성 위장관 질환의 종류 및 양상을 알아보고자 하였다. 방 법 : 2004년 3월부터 2007년 2월까지 노원 을지병원 소아과에 만성 복통을 주소로 내원한 132명을 대상으로 하였다. 결 과 : 대상 환자 중 기질적 질환으로 진단된 경우가 20명(15.2%), 기능성 위장관 질환이었던 경우는 112명(84.8%)이었다. 기능성 위장관 질환은 기질적 질환에 비해 통계적으로 유의하지 않았으나 여자에서 더 흔하게 나타났다. 기능성 위장관 질환 중에는 기능성 소화불량증(32.6%)과 과민성 장증후군(27.3%)이 가장 많았으며 2가지 종류 이상의 기능성 위장관 질환으로 진단된 환아는 7명(5.3%) 이었다. 배꼽 주위 통증, 최근의 스트레스, 기능성 위장관 질환의 가족력, 아침 시간의 통증 등은 기능성 위장관 질환을 갖고 있는 환아 들에서 더 많이 호소하였고 야간 통증, 구토, 두통은 기질적 질환을 갖고 있는 환아 들에서 더 많이 호소하였으나 모두 통계적으로 유의한 차이는 없었다. 결 론 : 소아의 만성 복통의 대부분의 원인은 기능성 위장관 질환이며 특히 기능성 소화 불량증과 과민성 장증후군이 가장 많았다. 불필요한 검사를 하지 않고 효과적인 진단과 치료를 위해 신뢰성 있는 진단 기준을 사용하는 것이 필요하다.

• 대한기계학회논문집
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• 제18권12호
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• pp.3109-3117
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• 1994

To operate a flexible mechanism in high speed its weight must be reduced as far as the structural strength does not decrease too much, but a light-weighted mechanism causes undesirable elastodynamic responses deteriorating the system performance. Besides, clearance within the connections of mechanisms causes rapid wear, increased noise and vibration. Even if the problems described above must be considered in the initial design stage, there has been no effective design process which takes account of the correlation between dynamic characteristics of flexible mechanism and the clearance effect at the joint. In this study, the generalized elastodynamic governing equations which include dynamic characteristics and boundary conditions of flexible mechanism are derived by variational calculus and solved by using FFM theory. To take the clearance effect at joint into account a new dynamic model is presented and also the method of modified stiffness/damping matrix is proposed to activate the dynamic clearance model, which cooperates with the developed governing equation very easily. As the results of this study, the proposed method(modified stiffness/damping matrix) to calculate clearance effect was proved to be superior to the existing one(force reaction method) in solution convergency and calculation performance. Besides this method can be easily adopted to the complex shape joint without calculation of reaction force direction.

• 한국실내디자인학회논문집
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• 제17권5호
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• pp.72-79
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• 2008

Nagaya is one of the traditional Japanese housing types in which multiple houses are attached together. In Nagaya, walls are shared by several houses but entrances are privately owned by houses. Nagaya consists of many wooden houses for common people located in parallel with narrow alleys between them. Nagaya was one of the representative housing types in Japanese architectural history. This research is to study the background of the origination of Nagaya in Japan, the characteristics of space and land planning, the features and causes of the changes in the space and land planning. In this research, we observed and analyzed unit plans of a block of gate-type Nagayas in Hanan, Osaka. The results are as follows. First, as the inner alleys(Roji) are closed, the number of entrances to each housing lot decreased from two to one since one entrance that used to be open to inner alleys(Roji) are permanently closed. Second, walls between streets and housing lots which used to be one of the outstanding characteristics of gate-type Nagayas are disappearing. Third, as the bathrooms are added to houses, the front gardens are being degraded to empty spaces or sometimes totally removed. Fourth, the space in the first floor of houses become family spaces, and that in the second floor is divided into private rooms for individuals.

• International Journal of Naval Architecture and Ocean Engineering
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• 제4권4호
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• pp.477-487
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• 2012

We investigated the aerodynamic characteristics of a three-dimensional (3D) wing with an endplate in the vicinity of the free surface by solving incompressible Navier-Stokes equations with the turbulence closure model. The endplate causes a blockage effect on the flow, and an additional viscous effect especially near the endplate. These combined effects of the endplate significantly reduce the magnitudes of the velocities under the lower surface of the wing, thereby enhancing aerodynamic performance in terms of the force coefficients. The maximum lift-to-drag ratio of a wing with an endplate is increased 46% compared to that of wing without an endplate at the lowest clearance. The tip vortex of a wing-with-endplate (WWE) moved laterally to a greater extent than that of a wing-without-endplate (WOE). This causes a decrease in the induced drag, resulting in a reduction in the total drag.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2005년도 추계 학술대회논문집
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• pp.223-227
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• 2005

A PCV valve is a part to control the flow rate of Blowby gas in a PCV system. A PCV system re-burns Blowby gas with fuel in a combustion chamber. Some gas enters to a crankcase room through the gap between piston ring and engine cylinder wall. This gas si called 'Blowby gas'. This gas causes many problems. In environmental view, Blowby gas includes about $25\~35\%$ hydrocarbon{HC) of total generated HC in an automobile. Hydrocarbon is a very harmful pollutant element in our life. In mechanical view, Blowby gas has some reaction with lubricant oil of crankcase room. Then, this causes lubricant oil contamination, crankcase corrosion and a decrease fo engine efficiency. Consequently, Blowby gas must be eliminated from a crankcase room. In this study, we simulated internal flow characteristics in a PCV valve according to spool dynamic behavior using local remeshing method And, we programmed our sub routine to simulate a spool dynamic motion. As results, spool dynamic behavior is periodically oscillated by the relationship between fluid force and elastic force of spring. And its magnitude is linearly increased by the differential pressure between inlet and outlet. Also, as spool is largely moved, flow area is suddenly decreased at orifice. For this reason, flow velocity is rapidly decreased by viscous effect.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집B
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• pp.248-253
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• 2001

An experiment was carried out to investigate the characteristics of the evaporation heat transfer for refrigerant R-134a flowing in a plate and shell heat exchanger. The data are useful in designing more compact and effective evaporators for various refrigeration and air conditioning systems. Two vertical counterflow channels were formed in the exchanger. The R-134a flows up in one channel exchanging heat with the hot water flowing down in the other channel. The effects of the average heat flux, mass flux, saturation temperature and vapor quality were examined in detail. The present data show that the evaporation heat transfer coefficient increases with the vapor quality. A rise in the refrigerant mass flux causes an increase in the $h_r$ value. A rise in the average imposed heat flux causes an increase in the $h_r$, value at the low quality. Finally, at a higer refrigerant saturation temperature the $h_r$, value is found to be lower.

• 한국화재소방학회논문지
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• 제32권1호
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• pp.99-107
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• 2018

디젤자동차에는 배기가스 중 미세먼지의 배출을 줄이기 위해 디젤미립자포집필터(DPF)가 설치되어 있다. 그런데 디젤자동차에서 DPF로 인해 화재가 발생하는 사례가 보고되고 있다. 이 논문에서는 디젤자동차의 배기가스 배출 규제 실태 및 배기가스 저감 장치에 대해 알아본 후, DPF로 인한 자동차화재 사례, DPF로 인해 발화된 경우의 특징, DPF와 관련된 자동차화재 발생 요인과 예방대책 및 화재원인조사 시 고려사항에 대해 분석한다. 그리고 자동차화재 조사와 관련하여 DPF로 인한 화재의 입증절차를 제시한다.

• 한국재료학회지
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• 제29권2호
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• pp.106-115
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• 2019

Recently, metal cases are widely used in smart phones for their luxurious color and texture. However, when a metal case is used, electric shock may occur during charging. Chip capacitors of various values are used to prevent the electric shock. However, chip capacitors are vulnerable to electrostatic discharge(ESD) generated by the human body, which often causes insulation breakdown during use. This breakdown can be eliminated with a high-voltage chip varistor over 340V, but when the varistor voltage is high, the capacitance is limited to about 2pF. If a chip capacitor with a high dielectric constant and a chip varistor with a high voltage can be combined, it is possible to obtain a new device capable of coping with electric shock and ESD with various capacitive values. Usually, varistors and capacitors differ in composition, which causes different shrinkage during co-firing, and therefore camber, internal crack, delamination and separation may occur after sintering. In addition, varistor characteristics may not be realized due to the diffusion of unwanted elements into the varistor during firing. Various elements are added to control shrinkage. In addition, a buffer layer is inserted in the middle of the varistor-capacitor junction to prevent diffusion during firing, thereby developing a co-fired product with desirable characteristics.

• 디지털융복합연구
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• 제12권10호
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• pp.45-59
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• 2014

특정 지역이 경제적 저성장을 보이는 구조적 원인에 대한 체계적이고 실증적인 분석은 향후 구조적 문제점을 해결하고 원활한 성장구조를 정착시키기 위한 중요한 작업이 된다. 본 연구는 강원도가 산업구조의 저위성과 영세 사업체들의 비중이 타 지역에 비해 높은 구조적 특성을 지녀 자본의 축적 구조가 취약하다는 점을 인식한다. 이러한 인식을 토대로 본 연구는 지역내총생산 및 지역산업연관표를 분석하여 지역의 입지여건과 특성을 고려한 발전전략을 수립할 수 있도록 논거를 제시하고 있다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2005년도 추계학술대회 논문집
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• pp.44-48
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• 2005

In general, the parallel-connected linear induction motors(LIM) are fed by one VVVF inverter in the magnetically levitated vehicle(MAGLEV) or linear motor subway drives. The air gap length of the parallel-connected linear induction motors operating at a grade or curved sections can be different each other. The air gap difference of the two motors attached to the same module causes unequal phase currents, asymmetic thrust and attraction force generation. In this paper, parellel-connected linear induction motors are operated by one IGBT inverter under the different air gap condition so that the phase current characteristics are examined experimentally.