• Journal of Biosystems Engineering
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• 제42권4호
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• pp.242-250
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• 2017

Purpose: This study was conducted to determine the appropriate operating conditions through a factorial experiment for the secondary separating part of the self-propelled pepper harvester. Methods: An experimental setup that simulates the secondary separating part of the self-propelled pepper harvester was organized. Test samples were classified into three types according to the number of peppers on a stem, and 12 sets were prepared for each type. Among the operating conditions of the secondary separating part, the rotational speed of drum B (four levels), radial clearance between drums and cylindrical teeth (three levels), and speed ratio between the three drums (two levels) were set as the test factors, and tests were repeated three times for different levels of each factor. The appropriate operating conditions were determined by analyzing the separation ratio and damage ratio of the peppers collected through the secondary separating part. Results: The test factors changed the overall separation ratio and overall damage ratio in similar trends. In other words, the conditions that caused high overall separation ratios also exhibited high overall damage ratios. Owing to the high overall damage ratio in the condition with the highest overall separation ratio, the operating conditions should be selected considering both ratios. Conclusions: When the condition with more than 60% of overall separation ratio and less than 15% of overall damage ratio was considered as the appropriate operating condition, 70 rpm of the rotational speed of drum B, 5 mm of the radial clearance between drums and cylindrical teeth, and 7:3:5 for the speed ratio of the three drums A, B, and C should be applied for the secondary separating part used in this study. Supplementary studies will be required in the future to find optimal operating conditions through the actual field test under further divided test factors.

• 전기전자학회논문지
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• 제26권3호
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• pp.333-340
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• 2022

고전압용 정전기 보호소자인 DDDNMOS(double diffused drain N-type MOSFET) 소자의 더블 스냅백 방지를 위한 최적의 이온주입 조건을 결정하기 위해 공정 및 소자 시뮬레이션이 수행되었다. HP-Well, N^- 드리프트 및 N⁺ 드레인 이온주입량의 변화가 더블 스냅백 및 애발란치 브레이크다운 전압에 미치는 영향을 고찰함으로써 더블 스냅백을 방지하여 정전기 보호 성능 개선할 수 있었다. HP-Well 영역보다는 N^- 드리프트 영역의 이온주입 농도를 최적으로 설계할 경우, 1차 on 상태에서 2차 on 상태로 전이하는 것을 막아주므로 비교적 양호한 정전기 보호 성능을 얻을 수 있었다. 또한 드리프트 이온주입 농도는 누설전류 및 애발란치 브레이크다운 전압에도 영향을 미치므로 동작전압이 30V보다 큰 공정기술에서는 DPS와 같은 새로운 구조를 적용하거나, 대안으로 여러 공정 변수들을 종합(colligation)하여 적용할 경우 향상된 정전기 보호 성능을 실현할 수 있을 것이다.

• 한국추진공학회지
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• 제14권1호
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• pp.29-39
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• 2010

증기분사 재생 가스터빈 시스템의 성능을 해석하고 최적 운전조건을 분석하였다. 해석모델을 통해 압력비, 증기분사율, 주위온도나 터빈입구온도 등의 설계변수들이 시스템의 열효율, 연료소모율, 비동력등 성능에 미치는 영향을 최적 운전조건에서 분석하였다. 해석결과들은 증기분사가 재생 가스터빈시스템의 열효율과 비동력을 대폭 향상시킬 수 있음을 보여주었다.

• 전자공학회논문지A
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• 제31A권3호
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• pp.77-86
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• 1994

A New environment SENSATION for circuit optimization and statistical analysis has been developed. It provides real time simulation and includes automatic algorithms to assist for reaching optimal solution. Furthermore, statistical analysis environment is presented which aids in Monte Carlo analysis. worst case corner analysis, and sensitivity analysis. These capabilities faciliate the characterization of the effects of several operating conditions and manufacture process paramenters on the design performances. We verify that the proposed methods can obtain the optimal solution of the objective function through several experimental results.

• 대한전기학회논문지
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• 제38권8호
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• pp.585-592
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• 1989

This paper presents an efficient algorithm for the reactive planning of transmission network under normal operating conditions. The optimal operation of a power system is a prerequisite to obtain the optimal investment planning. The operation problem is decomposed into a P-optimization module and a Q-optimization module, but both modules use the same objective function of generation cost. In the investment problem, a new variable decomposition technique is adopted which can operate the operation and the investment variables. The optimization problem is solved by using the gradient projection method (GPM).

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제51권12호
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• pp.664-669
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• 2002

In this paper the method to determine tire optimal switching instants in order to reduce the transient surges during switching not relevant to the neutral treatment of shunt reactors is presented. This method consists of the following two steps. First, the instants of the voltage peaks between the contacts of each poles and the voltage magnitude as well as the moments of the current zero crosses were found out analytically. Next, the instants of the contact touches or separations were determined in consideration of the rate of decrease of dielectric strength or a circuit breaker and the variation of the its operating time. The results obtained from the EMTP(Electromagnetic Transient Program) analysis studies show that the making instants are established at the peak voltage of each three poles for any conditions of a neutral point and the possible upper limited values of inrush currents due to the variation of the mechanical operating time can be estimated.

• 한국산학기술학회논문지
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• 제18권3호
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• pp.493-500
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• 2017

본 논문은 서울도시철도공사 유피스 내 전동차관리 고장데이타(BOM)을 통해 지속적으로 관리된 데이터를 활용하여 노후 철도차량부품의 신뢰성분석을 하고 개선방안을 제시하고자 하였다. 분석대상인 서울도시철도공사 7호선 2차분 보조전원장치(Static Inverter)는 객실 내 각종 서비스장치에 전원을 공급하여 직접적으로 승객 만족도에 영향을 주는 핵심적인 장치이다. 경영정보시스템의 장기간에 걸친 필드데이타를 바탕으로 고장의 패턴을 분석하기 위해 운용환경 스트레스 인자를 고려한 통계 신뢰성분석을 하였다. 보조전원장치(Static Inverter)의 하절기 집중고장현상과 관련하여 고장과 온도 스트레스인자와의 상관성에 대해 통계적 분석을 하였고 IGBT 인버터의 수명분석을 통하여 수리 전 후의 온도 스트레스 인자의 영향을 분석해 보았다. 그리고 전동차 부하량과 외기온도의 두 변수를 고려한 최적운행조건을 분석하여 고장다수 발생조건과의 냉각용량차이가 발생함을 확인할 수 있었고, 이러한 분석을 바탕으로 최적의 운행을 위한 냉각용량차이를 줄일 수 있는 방안을 제시하였다.

• Journal of Advanced Marine Engineering and Technology
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• 제25권5호
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• pp.1148-1160
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• 2001

An electronic control system of the automobile engine for optimal start and idle speed control has been developed. This system employs the microcoputer-based electronic control unit and crank angle sensor for precise control on fuel injection, ignition timing, and idle speed more quickly and accurately at the start and idling. Consequently, the number of misfire can be reduced during been affected by air flow rate, idle quality(roughness), spark timing, fuel injection, water temperature, and load, Thus, this electronic control system strivers to reach the optimal idle operating point, defined the lowest idle speed(fuel economy) and idle quality(roughness), under any engine operating conditions.

• 대한기계학회논문집B
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• 제30권4호
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• pp.381-388
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• 2006

The objective of this study is to predict the etching characteristics using spray characteristics for the optimization on the etching process of Lead-Frame. The etching characteristics such as etching factor, uniformity were investigated on the actual operating conditions. The correlation between the etching characteristics and the spray ones obtained by measurement were analyzed to simulate the etching characteristics according to actual conditions of lead-frame etching process. These conditions of lead-frame process were spray pressure, distance from nozzle tip to substrate, pipe pitch, and nozzle pitch. To improve the etching characteristics in the lead-frame process, effects of the various operating conditions should be understood in detail. The spray characteristics obtained by experiment using PDA system were simulated by the Monte-Carlo method. The etching process model was coded by Java language. It was found that simulation results generally agreed well with the measured results of etching characteristics in lead-frame etching process. The optimal operating parameters were successfully found under variable conditions.

• 전기학회논문지
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• 제60권11호
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• pp.2076-2082
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• 2011

The goal of this paper is to find an operating conditions of the single direct ethanol fuel cell such as the cell temperature, and flow rates of ethanol and oxygen. To investigate the output characteristics, the electrical current increased from 0[A] with interval of 0.001[A] every 2[s], and the cell voltage was increased until the voltage became 0.05[V]. Related to the effect of the cell temperature, the output characteristics both voltage and power were increased upto 80[$^{\circ}C$] according to the increase of the current density, but those were decreased over that temperature. In addition, the optimal flow rate of ethanol in anode was identified as of 2[mL/min] due to the dependence of generation rate such as the hydrogen ion and electron. And the flow rate of oxygen in cathode was desirable to about 300[sccm/min], it might be affected by the chemical reaction rate of the water formation among hydrogen ion, electron, and oxygen. Consequently, the fundamental conditions were identified in this work, and it will be carried out to find the best conditions of membrane by the effect of the plasma surface treatment, and the effect of other catalysts except for a platinum.