• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 하계학술대회 논문집 A
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• pp.99-101
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• 1993

This paper presents an approach to feeder reconfiguration in order to achieve an efficient operation of distribution systems utilizing knowledge base. The optimal feeder reconfiguration in this study eliminates various abnormal states which will create feeder overloads and feeder constraint problems. and will also accomplish minimum power loss of the distribution systems under normal operating condition by means of branch exchanges to change the status of sectionalizing switches with experiences of the experts. For an effective implementation of feeder reconfiguration, a best-first tree searching strategy based on heuristics is employed to evaluate the various alternatives of load transfer. The heuristic exchange of branches results in reduction of the search space as a means of implementing the best-first searching strategy.

• 품질경영학회지
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• 제8권1호
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• pp.3-7
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• 1980

In many industrial processes, there are more than two responses (i.e., yield, percent impurity, etc.) of interest, and it is desirable to determine the optimal levels of the factors (i.e., temperature, pressure, etc.) that influence the responses. Suppose the response relationships are assumed to be approximated by second-order polynomial regression models. The problems considered in this paper is, first, to propose how to select polynomial terms to fit the multivariate regression surfaces for a given set of data, and, second, to propose how to analyze the data to obtain an optimal operating condition for the factors. The proposed techniques were applied for empirical process optimization in a tire company in Korea. This case is presented as an illustration.

• 실천공학교육논문지
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• 제15권2호
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• pp.419-427
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• 2023

In this study, optimal adhesion conditions to alleviate defects caused by heat shrinkage with FDM type 3D printers with machine learning are researched. Machine learning is one of the "statistical methods of extracting the law from data" and can be classified as supervised learning, unsupervised learning and reinforcement learning. Among them, a function model for adhesion between the bed and the output is presented using supervised learning specialized for optimization, which can be expected to reduce output defects with FDM type 3D printers by deriving conditions for optimum adhesion between the bed and the output. Machine learning codes prepared using Python generate a function model that predicts the effect of operating variables on adhesion using data obtained through adhesion testing. The adhesion prediction data and verification data have been shown to be very consistent, and the potential of this method is explained by conclusions.

• 한국정밀공학회지
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• 제22권3호
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• pp.68-77
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• 2005

The set-up of an injection molding process is a ye complicated and time-consuming job because it is required to well determine a lot of variables closely related to products. Thus, the productivity of the set-up process mainly depends on operators' expertise and know-how. To solve the problem mentioned before, this research constructs a support system which helps operators determining the condition of the injection molding easily and systematically. The construction of the support system consists of the following four steps: 1) to determine the control variables which affect the target defect types, 2) to design and implement UI(user interface) using a scenario of set-up process, 3) to design and implement the search algorithms for the initial and optima] condition, and 4) to construct the embedded system which integrates the support system with the operating system of a plastic injection molding machine. The test experiments of some typical products are performed using the embedded system to verify the validity of the support system.

• 인터넷정보학회논문지
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• 제10권2호
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• pp.85-98
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• 2009

최근 들어 SaaS기반 이동형 개인 맞춤 소프트웨어 플랫폼에 관한 연구 및 개발이 활발해지고 있다. 이러한 플랫폼들은 다양한 사용자의 OS를 만족시키기 위해 최적화된 가상머신이 필수적으로 요구된다. 또한 다양한 Host OS에서 내부, 외부 네트워크 간에 빠르고 안정적인 서비스를 지원 함으로서 사용자의 작업환경 이동성을 보장해야 한다. 이를 위해 가상머신은 다양한 관점에서의 성능 측정이 필요하다. 하지만 기존 연구에서 가상머신의 성능 측정은 Host 컴퓨터에 설치된 VM에 Guest OS를 설치하여 이를 하나의 컴퓨터로 간주하고, 외부의 클라이언트에서 네트워크 성능을 측정한다. 이는 이동형 개인 맞춤 소프트웨어 플랫폼을 위한 가상머신 성능 측정에 적합하지 않다. 본 논문은 SaaS기반 이동형 개인 맞춤 소프트웨어 플랫폼을 위한 최적화된 가상머신을 선정하기 위해서 네트워크 성능 측정 방법과 측정된 결과 분석을 통한 최적화된 가상머신을 제안한다.

• 대한기계학회논문집B
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• 제32권4호
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• pp.307-316
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• 2008

The objective of this study is to provide numerical and experimental data that can be used to investigate the performance characteristics of a flat plate fin-tube evaporator in household and commercial refrigerators under frosting conditions. Computer simulations with variations of operating conditions such as air inlet temperature, relative humidity, and geometries were performed to find out optimal design parameters of a fin-tube evaporator for household and commercial refrigerators. The tube-by-tube method was used in the simulation and the frost growth model was considered under frosting conditions. The developed analytical model predicted the decreasing rates of heat transfer capacity and air flow rate ratio within ${\pm}$10% compared to the experimental results for a refrigerator under real operating conditions. As a result, the frost thickness at $3^{\circ}C$ & 80% is increased 40% than that of $-3^{\circ}C$ & 80%, and the frost thickness at $3^{\circ}C$ & 90% is increased 30% than that of $3^{\circ}C$ & 60%. Accordingly, the operating time of the evaporator in the refrigerator was reduced with the increase of the decreasing rate of air flow rate ratio at each condition.

• 한국소음진동공학회논문집
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• 제25권10호
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• pp.685-691
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• 2015

In this work, to identify effective parameter for performance of piezoelectric jetting dispenser, experimental investigation is carried out based on design of experiment. After preparing jetting dispenser using two stack-type piezoelectric actuators, basic working principle of the jetting dispenser is described. Eight operating conditions are chose as main factors and it is assumed that each factor has two levels. To reduce number of experiments for performance evaluation, the experimental sets are designed based on factional factorial design method. Experimental setup is established and the weight of single dot is measured by using precision scale. The main and interaction effects of factors are analyzed using commercial statistical program and optimal operating condition for small amount and small variation of weight of dispensed single dot are determined.

• 드라이브 ㆍ 컨트롤
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• 제18권4호
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• pp.84-90
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• 2021

Viscosity of hydraulic oils decreases due to loss reduction and efficiency increase of fluid power systems. However, low viscosity is not always appropriate due to the induction of large leakage and small lubricity. Therefore, a detailed study on the optimum viscosity of hydraulic oils is necessary. In this study, based on the thermohydrodynamic lubrication theory, numerical simulation was conducted using the slipper model of swashplate-type axial piston pumps and motors. The viscosity grades' (VG) effects of oils on power losses are mainly discussed numerically in fluid film lubrication, including changes in temperature and viscosity. The simulation results reveal that the flow rate increases and the friction torque decreases as VG decreases. The film temperature and power loss were minimised for a specific oil with a VG. The minimum conditions regarding the temperature and loss were different and closed. Under various operating conditions, the film temperature and power loss were minimised, suggesting that an optimum hydraulic oil with a specific VG could be selected for given operating conditions of pressure and speed. Otherwise, a preferable operating condition must be established to determine a specific VG oil.

• 한국전산유체공학회지
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• 제16권2호
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• pp.75-80
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• 2011

In this study, three-dimensional transient numerical simulations were carried out for a paint drying system of vehicle. The vehicle on assembly line passes through the drying system consisting of hot and cool air blow region. For the moving motion of the vehicle, moving of inlet boundary condition and MRF technique are used. The transient distribution of temperature and velocity in the drying system were predicted numerically. In order to validate the numerical results, transient distribution of the vehicle surface temperature was compared with experimental data, showing a good agreement. As a result of present study, optimal operating condition of the drying system are to be suggested.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2009년도 춘계 학술대회 제21권1호
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• pp.227-228
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• 2009

본 연구는 80MPa급 고강도콘크리트를 적용한 건축물의 화재시 성능확보를 위한 보강인자 배합사용에 있어 효율적인 내화성능 및 시공성을 확보하기 위한 최적배합비를 도출하고자 하였다. 이를 위한 분석 방법인 반응표면분석을 이용한 과정을 통하여 내화보강인자간의 최적공정조건 도출시 각 물성의 한계 값 설정에 따른 최적배합의 타당성을 검토하고자 하였다.