• 한국정보시스템학회지:정보시스템연구
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• 제9권1호
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• pp.61-86
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• 2000

CALS(Commerce At Light Speed) which originated in the early 1980's in the military sector is now an integral component in our global strategy to further heighten competitiveness. Through integration and streamlining of production, distribution, technical information and management, CALS will certainly lead the world out of these economically challenging times and into new global prosperity. However, not much effort have been focused on the development and diffusion issues of component technologies such as ERP/SCM(Enterprise Resourses Planning/supply Chain Management), PDM(Product Data Management), and BPR(Business Process Reengineering) related with the CALS in electronic industry. Therefore, the purpose of this study is to analyze the advancing status and to present suggestions for the development of the CALS in electronic industry. In order to achieve the purpose, the case study has been conducted using the questionaries on the end-users and the interviews on the managers in the CALS area. The case study cover 57 users of the CALS for the three outstanding electronics(L, S, and D Electronics) in Korea. The questionaries include five success measures and eleven diffusion factors for the component technologies such as ERP/SCM, PDM, and BPR. In summary, the CALS will serve as the bases for exciting corporated innovations and the common business framework which facilitates the realization of Virtual Enterprise and Electronic Commerce in the 21st century.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집D
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• pp.759-764
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• 2001

Heat (mass) transfer characteristics have been investigated on the endwall of a large-scale linear turbine cascade passage under a combustor-level high free-stream turbulence with a large length scale. Local heat (mass) transfer coefficients are measured by using the naphthalene sublimation technique. The result shows that local heat (mass) transfer on the endwall is greatly enhanced in the central region of the turbine passage, but there is no noticeable change in the local heat (mass) transfer in the region suffering severe heat load. Under the high free-stream turbulence, the local heat (mass) transfer coefficient shows more uniform distribution and its average value across the whole endwall region is increased by 26% of that at low turbulence condition. The heat (mass) transfer data on the endwall strongly supports that well-organized vortices near the endwall tends to suffer an suppression by the high free-stream turbulence.

• 대한전자공학회논문지SD
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• 제39권2호
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• pp.27-38
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• 2002

양자 우물 반도체 소자 모델링에 있어서 양자 우물의 다중 에너지 부준위 각각에 대한 Boltzmann 방정식의 해를 직접적으로 구하는 self-consistent한 방법을 개발하였다 양자 우물의 특성을 고려하여 Schrodinger 방정식과 Poisson 방정식 및 Boltzmann 방정식으로 구성된 양자 우물 소자 모델을 설정하였으며 이들의 직접적인 해를 유한 차분법과 Gummel-type iteration scheme에 의해 구하였다. Si MOSFET의 inversion 영역에 형성되는 양자 우물에 적용하여 그 시뮬레이션 결과로부터 본 방법의 타당성 및 효율성을 보여 주었다.

• 한국수학교육학회지시리즈B:순수및응용수학
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• 제5권2호
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• pp.123-132
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• 1998

Let F and G denote the distribution functions of the failure times and the censoring variables in a random censorship model. Susarla and Van Ryzin(1978) verified consistency of $F_{\alpha}$, he NPBE of F with respect to the Dirichlet process prior D($\alpha$), in which they assumed F and G are continuous. Assuming that A, the cumulative hazard function, is distributed according to a beta process with parameters c, $\alpha$, Hjort(1990) obtained the Bayes estimator $A_{c,\alpha}$ of A under a squared error loss function. By the theory of product-integral developed by Gill and Johansen(1990), the Bayes estimator $F_{c,\alpha}$ is recovered from $A_{c,\alpha}$. Continuity assumption on F and G is removed in our proof of the consistency of $A_{c,\alpha}$ and $F_{c,\alpha}$. Our result extends Susarla and Van Ryzin(1978) since a particular transform of a beta process is a Dirichlet process and the class of beta processes forms a much larger class than the class of Dirichlet processes.

• 한국전자파학회논문지
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• 제16권6호
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• pp.571-579
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• 2005

본 논문은 80 MHz 이하의 주파수 대역에서 사용하기 위해 제안된 강제 공진형 EMI 다이폴 안테나에 대한 시험장 감쇠량 이론 곡선을 계산하고 있다. 이론 해석으로서는 안테나에 흐르는 전류 분포에 관한 연립 적분 방정식을 유도하고 구분 정현 함수를 사용한 Galerkin의 모멘트 법으로 그 해를 구하여 시험장 감쇠 량을 검토하고 있다. 그 결과, 강제 공진형 EMI 다이폴 안테나는 50 MHz 이하 주파수 대역의 수평 편파 시험장 감쇠량 측정에 유용하게 사용할 수 있음을 확인할 수 있었다. 제시된 시험장 감쇠량 이론치는 강제 공진형 EMI 다이폴 안테나를 사용하여 야외 시험장의 적합성을 평가할 때 기준 이론 곡선으로 활용할 수 있다.

• 한국전자파학회논문지
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• 제12권6호
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• pp.939-947
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• 2001

본 논문에서는 외부 다이폴 파원에 의해 합체의 개구를 통하여 침투하는 침투 전계와 함체의 공진 주파수 특성을 검토하고 있다. 이론해석 방법으로서는 외부 다이폴 파원의 전류분포 및 함체에 있는 개구의 개구면 전계분포에 관한 연립 적분방정식을 Galerkin의 모멘트 법으로 해석하고 있다. 이론해석의 결과, 침투전계는 개구면 부근에서 가장 크며, 함체의 공진 주파수는 개구가 없는 경우의 공진 주파수와 거의 일치하므로 함체의 크기가 결정되면 공진 주파수의 추정이 가능하다는 것을 알 수 있었다. 이론해석의 타당성을 화인하기 위하여 함체의 내부 전계 및 공진 주파수의 실험치와도 비교하고 있다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.1323-1328
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• 2004

This paper shows the study on the design of the spray-freeze dryer for the production of the pulmonary inhalation powders. Powder production and handling has been an integral part of pharmaceutical processing because of the wide use of oral dosage forms. There are a few commonly used powder preparation methods including mechanical milling, precipitaion, spray drying, freeze drying, and so on. In general, methods available for preparing inhalation powders are limited due to certain inhalation powder's sensitive nature to the processing environments. This is particularly true for preparing dry powder aerosols where the aerodynamic particle size$(<5{\mu}m)$ and the size distribution are pivotal. Supercritical fluid antisolvent and spray freeze drying have recently emerged as promising techniques for producing powders for use in microcapsulation. However, the aerosol applications of these powders are yet to be explored. The purpose of this study is to test the feasibility of using spray freeze-dried pulmonary inhalation powders for aerosolization.

• 한국정밀공학회지
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• 제14권3호
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• pp.156-165
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• 1997

In the practical control systems, the dynamic range of actuatiors is limited(or saturated) when actuators are driven by sufficiently large signals. This gives rise to a nonlinearity as a result of actuator saturation. For example, the upper limit is imposed on productive capability by available factory space and capital equipment. Other examples of those kinds of actuator saturations are a maximum torque of the actua- ting motors and a throttle position in an aircraft speed control A saturating actuator may lead not only to a large overshoot during start-up and shut-down, but also to deterioration of the performance due to the uncertainties. That is, the speed of response is decreased and, possibly, the system output may not follow the lalrge reference inputs. The large-overshoot may be accompanied by rest wind-up(or called by integra- tor wind-up) which comes from controllers with integral action in saturation operation regions. Eventually, as the overshoot increases, the system has a limit cycle or becomes oscillatorily unstable. Due to these cir- cumstances, many studies are focused on the stability and robustness of the nonlinear systems with satu- rating actuator in the time-domain as well as in the frequency-domain.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 춘계학술대회
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• pp.621-625
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• 2007

Oscillating wave amplitude in a bottom-mounted owe chamber designed for wave energy converter is investigated by applying characteristic wave conditions in Korean coastal water. The effects of shape parameters of OWC chamber in a view of wave energy absorbing capability are analyzed. Both experimental and numerical approaches are adopted and their results are compared to optimize the shape parameters which can result in a maximum power production under given wave distribution. The experiment was carried out in a wave flume under 2-D assumption of OWC chamber. In numerical scheme, the potential problem inside the chamber is solved by use of the Green integral equation associated with the Rankine Green function, while outer problem with the Kelvin Green function taking account of fluctuating air pressure in the chamber. Air duct diameter, chamber width, and submerged depths of front skirt and back wall of chamber changes the magnitude and peak frequency of wave absorption significantly.

• 한국방사선학회논문지
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• 제13권7호
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• pp.925-932
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• 2019

플라스틱 섬광체와 상용 50 mm, f1.8 렌즈 및 고감도 CMOS 카메라를 사용하여 방사선치료 시 흡수선량을 측정할 수 있는 광 도시메트리 시스템을 구축하였다. 아울러 촬영된 방사선 분포 영상에 대한 비네팅 보정, 기하학적 왜곡 보정, 스케일 보정을 통하여 화소값으로 선량을 교정하는 절차를 확립하였다. 개발된 광 도시메트리 시스템을 6 MV 의료용 선형가속기에 대하여 선량 특성 평가를 수행한 결과, 심부선량백분율은 이온챔버로 측정한 결과에 비하여 빌드 업 깊이 이상에서는 오차 범위 2% 이내로 일치하였으며, 90% 조사야에 대하여 2.8%의 평탄도가 측정됨에 따라 방사선치료선량 측정 시스템으로서의 충분한 활용가능성을 확인하였다.