• ETRI Journal
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• 제18권3호
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• pp.127-145
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• 1996

A new analytic framework based on a linear algebra approach is proposed for examining the performance of a direct sequence spread spectrum (DS/SS) slotted ALOHA wireless communication network systems with delay capture. The discrete-time Markov chain model has been introduced to account for the effect of randomized time of arrival (TOA) at the central receiver and determine the evolution of the finite population network performance in a single-hop environment. The proposed linear algebra approach applied to the given Markov problem requires only computing the eigenvector ${\prod}$ of the state transition matrix and then normalizing it to have the sum of its entries equal to 1. MATLAB computation results show that systems employing discrete TOA randomization and delay capture significantly improves throughput-delay performance and the employed analysis approach is quite easily and staightforwardly applicable to the current analysis problem.

• Journal of international Conference on Electrical Machines and Systems
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• 제3권1호
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• pp.54-60
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• 2014

This paper shows a calculation method of several types of loss and the efficiency of brushless DC motors coupled with a load system by using a simple equivalent circuit, in which copper loss, eddy current loss, hysteresis loss, friction loss, viscous loss, and inverter loss are taken into account. We clarify each loss and motor efficiency at different motor speeds and different output torques by using the Microsoft-Excel. Moreover, the calculated results are in good agreement with the measured ones.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 봄학술 발표회 논문집(I)
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• pp.375-378
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• 2005

In the mechanism of beam shear failure, beam action and arch action always exist simultaneously. According to a/d ratio, the proportion and contribution between these two actions to shear capacity are merely changed. Moreover, the current codes recommendations are founded on the experimental results with normal strength concrete, the applicable range of $f'_{c}$ must be extended. Based on this mechanism and new requirement, an analytical equation is proposed for shear capacity prediction of reinforced concrete beams without stirrups. To reflect contribution change of two actions, stress variation in longitudinal reinforcement along the span is considered with Jenq and Shah Model. Dowel action and shear friction are also taken into account. Size effect is included to derive more precise equation. It is shown that the proposed equation is more accurate than other empirical equations and codes. So, it can be possible that wide range of a/d ratio is considered by one equation.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 C
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• pp.1993-1995
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• 2000

In this paper, we calculate the magnetic field and analyze the inductive interference in conductive material around power transmission line. To compute induced eddy currents as well as magnetic fields, finite element method(FEM) is used for numerical calculation. The characteristics, transmission line height, conductive earth and mitigation wire are taken account of FEM analysis. This research also shows that mitigation wire reduces amount of eddy current in buried pipe line.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2016년도 춘계학술대회
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• pp.621-624
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• 2016

분계점은 전기통신설비에 대해 사업자와 이용자 간의 설비영역을 구분하여 분쟁을 예방하고 유지의 효율성을 제고하기 위한 규정이다. 현행 분계점 기준은 전화통신망을 중심으로 규정되어 있어 새로운 서비스와 설비의 도입에 따른 다양한 접속 방식에 대해 적용성의 검토가 필요하다. 본 논문에서는 분계점에 대한 국내외 규정을 분석하고 고려되어야 할 사항에 대해 고찰하기로 한다.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.1065-1068
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• 2009

The current study introduces a new color space applicable to next-generation media such as UHDTV and 3D-TV systems that are in the middle of development. Display referred approach was taken into account rather than scene referred approach for deriving a new RGB-primary set forming the new color space. The reproducible color range generated by the newly suggested RGB-primary set encompasses almost entire real-world surface colors with a very good efficiency.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 A
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• pp.64-66
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• 1998

This paper presents a new efficient method for transient analysis in magnetodynamic systems of linear eddy current problems. This mehtod employs the Fourier transform and the high-order frequency sensitivity of harmonic finite element method. By taking into account the time-constant of magnetodynamic system, the Fourier integral of continuous frequency is converted into the Fourier series of discrete frequency. And with the results of Fourier series expansion of converted input wave form, the responses of each sinusoids is superposed to give the total response of the magnetodynamic systems. But, if the frequency band of input wave form is broad, it takes long computational time since all responses for each sinusoids must be calculated. Therefore, the high-order frequency sensitivity method is employed to estimate the response variation to frequency. The proposed algorithm is applied to an induction heating system to validate its numerical efficiency.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 A
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• pp.253-255
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• 1999

In this paper, a shape optimization algorithm of superconducting magnet using finite element method is presented. Since the superconductor loses its superconductivity over the critical magnetic field and critical current density, this material property should be taken into account in the design process. Trial and error approach of repeating the change of the design variables costs much time and it sometimes does not guarantee an optimal design. This paper presents a systematic and efficient design algorithm for the superconducting magnet. We employ the sensitivity analysis based on finite element formulation. As for optimization algorithm, the inequality constraint for the superconducting state is removed by modifying the objective function and the nonlinear equality constraint of constant volume is satisfied by the gradient projection method. This design algorithm is applied to an optimal design problem of a solenoid air-cored superconducting magnet that has a design objective of the maximum energy storage.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2019년도 춘계 학술논문 발표대회
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• pp.129-130
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• 2019

In this research, we determine the proper number of entrances in the evacuation facilities for civil and military personnel. The current standards on the emergency evacuation facility only sets the number of possible evacuees and the according architectural floor area since the evacuation have been completed. However, other than static standards such as the floor area, there is needs to consider the dynamic standards along with allowable evacuation time such as the number of entrance, staircases and so on. Therefore, we need to consider the number of entrances and their location in order to account for the allowed evacuation time of particular number of people in a set area. The outcome could be contributed to the standards which should contain the dynamic conditions associated with evacuation.

• 디지털융복합연구
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• 제1권1호
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• pp.69-91
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• 2003

The purpose of this paper is to provide several considerations to be taken into account when institutionalizing the information security(Infosec) pre-assessment. Infosec pre-assessment is a necessary process to embed the security requirements into the information systems at the early stages in their development, resulting in more cost-effective infosec. In order to provide some institutional issues, domestic infosec assessment schemes and U.S. Infosec certification and accreditation schemes are reviewed. Also, the current status of infosec implementation in the public information systems projects is analyzed. Based on the analyses, the seven suggestions are proposed in developing and performing the infosec pre-assessment scheme.