• 제어로봇시스템학회논문지
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• 제17권3호
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• pp.241-247
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• 2011

This paper is intended to improve efficiency of two-phase BLDC motor using analytical and statistical methods, and then the stability of the starting for the designed model is investigated. The characteristics of the motor according to magnetization directions of permanent magnet are analyzed through the analytical method, and design variables that affect the efficiency are selected. Preliminary optimal design is performed using the analytical method with the design variable. The RSM (Response Surface Method) based on the FEA (Finite Element Analysis) is applied to complement errors of the analytical method. As a result, the optimal design is determined. Finally, the stability of the starting for the optimal designed model is evaluated by analyzing cogging torque, and it is verified through the FEA.

• 품질경영학회지
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• 제39권2호
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• pp.170-178
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• 2011

In general, a software fault detection phenonenon is described by a software reliability model based on a nonhomogeneous Poisson process(NHPP). In this paper, we propose a software reliability growth model considering the differences of the software environments in both the testing phase and the operational phase. Also, we consider the problem of determining the optimal release time and the optimal warranty period that minimize the total expected software cost which takes account of periodic software maintenance(e.g. patch, update, etc). Finally, we analyze the sensitivity of the optimal release time and warranty period based on the fault data observed in the actual testing process.

• 한국균학회지
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• 제20권1호
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• pp.58-64
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• 1992

Trichoderma 속의 제균종중에서 10균주를 선별하여 protoplast 형성에 관한 제반조건을 검토하였으며 그 결과는 다음과 같았다. 보편적으로 protoplast 형성에 있어서 삼투안정제의 효과는 ${KCI}>(NH_4)_2{SO_4}>NaCl>mannitol>{MgSO}_4$ 순이었으며, 최적농도는 0.6-0.9M 사이에서 결정되었다. Protoplast형성을 위한 DRISELASE의 최적조건은 pH5.0, 효소농도 2%. 반응시간 4시간, 반응온도 $30^{\circ}C$ 이었다. NOVOZYM 234의 최적조건은 pH 5.5, 효소농도 1%,반응시간 3시간, 반응온도 $30^{\circ}C$ 이었다. Protoplast 생성은 대수증식기 초기와 증기사이의 균사체가 최적이었다. Protoplast 생성에 있어서는 DRISELASE가 효과적이었으나 T. longibruchiatum IAM 13107과 T. viride IAM 5141의 경우에는 NOVOZYM 234가 보다 효과적이었다.

• Journal of electromagnetic engineering and science
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• 제4권4호
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• pp.162-167
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• 2004

In this paper, optimal position of optical phase conjugator(OPC) for best compensating distorted WDM channels due to both chromatic dispersion and self phase modulation(SPM) is numerically investigated, and the compensation characteristics of overall WDM channels at this position is investigated, comparing with that in case of OPC placed at mid-way of total transmission length. It is confirmed that the compensation extents in WDM system with OPC is more improved by the shifting OPC position from the mid-way of total transmission length. And, we confirmed that the optimal position of OPC must be selected to the position decreasing not only eye opening penalty(EOP) of overall WDM channels but also EOP deviation between WDM channels, and this OPC position should be altered as various system parameters such as modulation format, and fiber dispersion, etc. Using proposed configuration, it is possible to remove all in-line dispersion compensator, reducing span losses and system costs.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.672_673
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• 2009

In this paper seeks the parameter which relates with the efficiency from premium efficiency level single-phase induction motor. Also it compares with the parameters and it analyzes and an optimum parameter it seeks by FEM. Consquently, a optimal design is accomplished from the this paper. Also parameters compare efficiency. And it analyzes and studies about optimum parameter by FEM. The sample single-phase induction motor selection selected existing premium level motor. We analyze each parameter using 2-D finite element analysis (FEM). According to Study of losses and Design flow, losses and efficiency can be explain by many parameter. So this paper present optimal parameters. Finally, this paper presents the method which raises the efficiency of premium efficiency level single-phase induction motor.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 추계학술대회논문집 I
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• pp.465-470
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• 2001

Two-phase BLDC(brushless DC) motor has larger torque ripple than three-phase BLDC motor because of its unique skeleton-type structure. An electronic switching mechanism to change the current-direction of the BLDC motor can be a source of vibration as well as unbalanced rotor weight. A proper switching timing which makes less vibrations was considered by changing the position of sensing element around the center of rotation. Also, the current of the motor was measured for the calculation of the motor efficiency. From the vibration test results and with the consideration of the motor efficiency, an optimal switching position of the Hall sensor was found.

• Journal of information and communication convergence engineering
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• 제7권3호
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• pp.372-376
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• 2009

In this paper, new and simple optical transmission link with fixed dispersion management (DM) scheme, i.e., pre(post) compensation and residual dispersion per span (RDPS) are fixed to net residual dispersion (NRD) = 0 ps/nm, and optical phase conjugator (OPC) having optimal position depending on launch power in WDM transmission system is proposed. Also, effective launch power range of WDM channels resulting 1 dB eye opening penalty (EOP) is induced as a function of OPC position. First, it is confirmed that, for applying DM into WDM transmission link fixed pre(post)compensation and RDPS, which are independence on exact system parameters except launch power, sufficiently are used in WDM links, but OPC with optimal position is needed for effective compensating impairments of WDM channels. And, it is confirmed that effective launch power is broader in case of RDPS = 100 ps/nm than in RDPS = 50 ps/nm. But, it is shown that the best OPC position offset is -0.6 km from a point of view of power window, which is defined as difference between maximum and minimum effective launch power.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.24-26
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• 2002

The recent emphasis on energy conservation demands an improvement of the efficiency of single-phase induction motors. To take the efficiency operation of the capacitor run single-phase induction motor with auxiliary and main winding, it is very important to select the capacitance value. This paper describes the theoretical analysis method of a single-phase induction motor which is based on the rotating field theory, using the method of symmetrical components. The optimal selection method of capacitance is proposed.

• Journal of Electrical Engineering and Technology
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• 제7권1호
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• pp.69-74
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• 2012

This paper presents a distributed winding type axial flux permanent magnet synchronous generator (AFPMSG) with reduced the total harmonic distortion (THD), suitable for wind turbine generation systems. Although the THD of the proposed distributed winding type is more reduced than the concentrated winding type, the unbalance of the phase back EMF occurs. To improve the unbalance of the phase back EMF and the output power of the distributed winding type AFPMSG, the Kriging based on the latin hypercube sampling (LHS) is utilized. Finally, these optimization results are confirmed by experimental results. As a result, the unbalance of the phase back EMF and the output power of the distributed winding type AFPMSG were improved while maintaining the total harmonic distortion (THD) and the average phase back EMF.

• 산업경영시스템학회지
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• 제29권2호
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• pp.7-12
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• 2006

This study considers the problem of scheduling jobs on uniform parallel machines with a common due date. The objective is to minimize the total absolute deviation of job completion times about the common due date. This problem is motivated by the fact that a certain phase of printed circuit board manufacturing is bottleneck and the processing speeds of parallel machines in this phase are uniformly different for all jobs. Optimal properties are proved and a simple polynomial time optimal algorithm is developed.