• 한국정보과학회논문지:컴퓨팅의 실제 및 레터
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• 제6권1호
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• pp.68-81
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• 2000

트레이더 서비스는 서비스를 이용하고자 하는 객체가 서비스를 제공하는 객체에 관한 사전지식이 없더라도 서비스의 특성에 따라 가장 적절한 서비스를 찾아 이용할 수 있게 한다. 이를 위해 트레이더 서비스는 임포터가 요청한 서비스를 임포터, 트레이더, 링크의 정책에 따라 매칭되는 서비스를 지역 트레이더나 타 트레이더와의 연합을 통해 서비스 오퍼를 가공하여 전달한다. 이러한 기존의 트레이더 방식은 임포터가 요청한 서비스 오퍼의 양과 트레이더간 연합에 따라 요청에 대한 결과가 늦게 전달됨으로써 사용자의 대기시간이 길어지고 트레이더의 성능을 저하시킨다. 정확한 서비스 오퍼와 빠른 서비스 제공을 위해 트레이더 서비스의 성능 문제는 트레이더 서비스 구현 시 중요한 기준이다. 본 논문에서는 트레이더 서비스의 성능 저하 문제를 해결하고 최상의 서비스를 제공하기 위해 OMG에서 정의한 임포터와 트레이더의 정책에 새로운 정책을 추가하고, 빠른 서비스 제공을 위한 트레이더 서비스의 향상된 PUTS(PUsh Trader Service) 모델을 제시한다. 또한 모델의 주요 모듈 설계 및 구현을 제시하고, 제안한 모델을 이용하여 트레이더 서비스 시스템을 구현한다. 구현 시스템의 성능 평가를 위해 일반적인 트레이더 서비스 시스템의 유형별로 분석, 평가한다.

• 한국정보기술학회논문지
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• 제16권11호
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• pp.97-103
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• 2018

본 논문에서는 시변 최적 FIR 필터를 이용한 전력 신호의 고조파 검출 방법을 제안한다. 잡음이 고려된 전력 신호에 대해 고조파의 진폭과 위상각의 변화량이 확률적 정보로 고려된 시변 상태 방정식 모델에 대해 시변 최적 FIR 필터를 설계하여 고조파 성분을 검출한다. 제안한 검출 방법에 사용된 시변 FIR 필터는 유한 구간의 정보만을 사용하고 어떠한 초기 조건도 사용하지 않도록 설계되어 칼만 필터 기반의 검출 방법의 오차 누적에 따른 검출 성능 저하나 발산 문제를 해결할 수 있다. 또한 FIR 구조의 필터 사용을 통해 칼만 필터 대비 불확실성에 대해 보다 강인한 검출이 가능하다. 시변 최적 FIR 필터의 사용을 통해 시불변 최적 FIR 필터 기반 고조파 검출 방법 대비 보다 일반적인 해를 제공한다. 제안하는 검출 방법의 우수성을 검증하기 위해 시변 칼만 필터 및 적응 칼만 필터 기반 고조파 검출 방법과의 비교 시뮬레이션을 수행한다.

• Earthquakes and Structures
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• 제20권1호
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• pp.55-70
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• 2021

In urban cities, buildings were built in the neighborhood, these buildings influence each other through structure-soilstructure interaction (SSSI) and seismic pounding due to limited separation distance in-between. Generally, the effects of the interaction between soil and structure are disregarded during seismic design and analysis of superstructure. However, the system of soil-base adversely changes structural behavior and response demands. Thus, the vibration characteristics plus the seismic response of a building are not able to be independent of those in adjacent buildings. The interaction between structure, soil, and structure investigates the action of the attendance of adjacent buildings to the others by the interaction effect of the sub-soil under dynamic disturbances. The main purpose of this research is to analyze the effects of SSSI and seismic pounding on the behavior of adjacent buildings. The response of a single structure or two adjacent structures with shallow raft base lying on soft soil are studied. Three dimensions finite element models are developed to investigate the effects of pounding; gap distance; conditions of soil; stories number; a mass of adjacent building and ground excitation frequency on the seismic responses and vibration characteristics of the structures. The variation in the story displacement, story shear, and story moment responses demands are studied to evaluate the presence effect of the adjacent buildings. Numerical results acquired using conditions of soil models are compared with the condition of fixed support and adjacent building models to a single building model. The peak responses of story displacement, story moment, and story shear are studied.

• KEPCO Journal on Electric Power and Energy
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• 제7권2호
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• pp.329-333
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• 2021

V2G (Vehicle to Grid) technology for an EV (Electric Vehicle) has been assumed as so promising in a near future for its useful energy resource concept but still yet to be developed around the world for specific service purposes through various R&BD projects. Basically, V2G returns power stored in vehicle at a cheaper or unused time to the grid at more expensive or highly peaked time, and is accordingly supposed to provide such roles like peak shaving or load levelling according to customer load curve, frequency regulation or ancillary reserves, and balancing power fluctuation to grid from the weather-sensitive renewable sources like wind or solar generations. However, it has recently been debated over its prominent usage as diffusing EVs and the required charging/discharging infrastructure, partially for its addition of EV ownership costs with more frequent charging/discharging events and user inconvenience with a relative long-time participation in the previously engaged V2G program. This study suggests that a Korean DR (Demand Response) service integrated V2G system especially based upon a dynamic charge/pause/discharge scheme newly proposed to ISO/IEC 15118 rev. 2 can deal with these concerns with more profitable business model, while fully making up for the additional component (ex. battery) and service costs. It also indicates that the optimum economic, environmental, and grid impacts can be simulated for this V2G-DR service particularly designed for EV aggregators (V2G service providers) by proposing a specific V2G engagement program for the mediated DR service providers and the distributed EV owners.

• 한국소음진동공학회논문집
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• 제21권12호
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• pp.1112-1119
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• 2011

The goal of this study is the stability evaluation of a vacuum pump through modal test and rotor dynamics. Roots type vacuum pump, which is a dry vacuum pump, is necessary for the manufacturing process of the semiconductor and the display. Eigenvalue was solved by the finite-element method(FEM) using 2D and 3D models, then the modal test result was compared with the FEM result. According to the comparison, the analysis result using the 2D was more accurate than the 3D model. Therefore, rotor dynamics was performed by the 2D model. Campbell diagram and root-locus maps, which were calculated by complex-eigenvalue analysis, were used to evaluate the stability of the rotors of the vacuum pump. And displacement solved by unbalance response analysis was compared with the minimum clearance between two rotors of the vacuum pump. Thus, the vacuum pump is assumed operated under steady state through the evaluation of the rotor dynamics.

• 대한가정학회지
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• 제50권7호
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• pp.59-66
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• 2012

The purpose of this study was to identify a causal relationship in the career preparation behavior, parental social support, career decision making self-efficacy and the career maturity of the pre-service elementary school teachers. A total of 374 questionnaires were used for data analysis, excluding the 23 copies deemed insincere in response. To ensure the reliability and validity of the questions, technical statistics of the frequency, ratio, average, standard deviation, skewness, and kurtosis via PASW 18.0, item-total correlation, the totality, and the reliability analysis. The structural analysis via AMOS 7.0 in the bootstrapping method was undertaken to perform the path analysis among the variables and to assess the suitability of the model. The findings of the study led to the following conclusions: First, the causal model for the career preparation behavior, parental social support, career decision making self-efficacy, and the career maturity of the pre-service elementary school teachers is suitable to empirical analysis on research variables. Second, the career decision making self-efficacy of pre-service elementary teachers has direct effect on career preparation behavior positively. Third, parental social support of the pre-service elementary teachers has indirect effects on the career preparation behavior positively.

• Wind and Structures
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• 제26권6호
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• pp.355-367
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• 2018

This paper studies the aerodynamic stability of a tensioned, geometrically nonlinear orthotropic membrane structure with hyperbolic paraboloid in sag direction. Considering flow separation, the wind field around membrane structure is simulated as the superposition of a uniform flow and a continuous vortex layer. By the potential flow theory in fluid mechanics and the thin airfoil theory in aerodynamics, aerodynamic pressure acting on membrane surface can be determined. And based on the large amplitude theory of membrane and D'Alembert's principle, interaction governing equations of wind-structure are established. Then, under the circumstance of single-mode response, the Bubnov-Galerkin approximate method is applied to transform the complicated interaction governing equations into a system of second-order nonlinear differential equation with constant coefficients. Through judging the frequency characteristic of the system characteristic equation, the critical velocity of divergence instability is determined. Different parameter analysis shows that the orthotropy, geometrical nonlinearity and scantling of structure is significant for preventing destructive aerodynamic instability in membrane structures. Compared to the model without considering flow separation, it's basically consistent about the divergence instability regularities in the flow separation model.

• 한국지반공학회논문집
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• 제16권1호
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• pp.203-210
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• 2000

최근 대중교통 및 물류 운송 수단으로써 철도의 중요성이 부각되면서 부수적으로 발생되는 열차하중에 의한 환경진동은 국제표준화기구(ISO)의 기준에 반영될 정도로 관심의 대상이 되었다. 하지만 도심지의 시설물 또는 진동원 주위의 주거지역 조성 시, 이에 대한 체계적이고 합리적인 대책은 미흡한 실정이다. 따라서 현재까지 설계 및 시공 시에 주요 인자로 취급되지 않았던 동적 열차하중에 대한 지반진동의 예측과 저감대책의 마련이 절실히 요구되고 있다. 본 연구에서는 열차하중에 의한 철도연변의 지반진동을 분석/예측하기 위한 열차주행에 의한 하중산정 모델과 이에 의한 토공구간에서의 진동의 지중 전달과정 해석기술 및 전산프로그램을 개발하고 그에 따른 해석치와 실측치를 비교 검증하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.320-320
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• 2010

In the case of existing ultrasonic motors, they have characteristics such as outstanding response speed, speed and high efficiency. However, it's very hard to use practically them as small motors due to complicated structure and expensive cost. This paper proposed v-type ultrasonic linear motor. Stator of the motor is composed of thin elastic body and four ceramics attached to upper and bottom areas of the body. The ceramics have each direction of polarization. When two harmonic voltages which had $90^{\circ}$ phase difference were applied to the ceramics, the symmetric and anti-symmetric displacements were generated at the tip to make the elliptical motion. To find out a model that generates maximum displacement at contact tip, FEM program was used with change of leg-angle. In addition, optimal model was chosen by considering magnitude and shape of displacement according to change of frequency.

• 대한전자공학회논문지SD
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• 제41권7호
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• pp.7-12
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• 2004

본 논문에서는 교류전류 집중현상이 고려된 바이폴라 등가모델에서 내부 베이스-컬렉터 캐패시턴스(C/sub μ/)와 외부 베이스-컬렉터 캐패시턴스(C/sub μx/)를 분리해서 추출하는 개선된 방법을 연구하였다. 먼저, 기존 추출방법들의 문제점들을 파악하고, 교류전류 집중 캐패시턴스가 포함된 차단모드 등가회로로부터 개선된 추출방정식들을 유도하였다. 이렇게 추출된 C/sub μx/와 C/sub μx/를 사용하여 모델 된 전류 및 전력이득 주파수 응답곡선들은 기존 추출방법으로 얻어진 곡선보다 측정 데이터와 훨씬 잘 일치되었으며, 이는 개선된 추출방법의 정확도를 증명한다.