• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 학술대회 논문집 전문대학교육위원
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• pp.55-59
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• 2002

This paper presents a novel three-phase current-fed Pulse Width Modulation converter with switched capacitor type resonant DC link commutation circuit operating PWM pattern strategy under a design consideration of low-pass filter, which can operate on the basis of the principle of zero current soft switching commutation. In the first place, the steady state operating principle of this converter with a new resonant DC link snubber circuit is described in connection with the equivalent operation circuit, together with the practical design procedure of the switched-capacitor type resonant DC link circuit is discussed from a theoretical viewpoint on the basis of a design example for high-power applications. The actively delayed time correction method to compensate distorted currents due to a relatively long resonant commutation time is newly implemented in the open loop control scheme so as to acquire the new optimum PWM pattern. Finally, the experiment of set-up in laboratory system of this converter is concretely demonstrated herein to confirm a zero current soft-switching commutation of this converter. The comparative evaluations between current -fed hard switching PWM and soft-switching PWM converters are carried out from a viewpoint of their PWM converter characteristics.

• 전기학회논문지P
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• 제52권2호
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• pp.49-55
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• 2003

This paper presents a novel three-phase current-fed Pulse Width Modulation converter with switched capacitor type resonant DC link commutation circuit operating PWM pattern strategy under a design consideration of low-pass filter, which can operate on the basis of the principle of zero current soft switching commutation. In the first place, the steady state operating principle of this converter with a new resonant DC link snubber circuit is described in connection with the equivalent operation circuit, together with the practical design procedure of the switched-capacitor type resonant DC link circuit is discussed from a theoretical viewpoint on the basis of a design example for high-power applications. The actively delayed time correction method to compensate distorted currents due to a relatively long resonant commutation time is newly implemented in the open loop control scheme so as to acquire the new optimum PWM pattern. Finally, the experiment of set-up in laboratory system of this converter is concretely demonstrated herein to confirm a zero current soft-switching commutation of this converter. The comparative evaluations between current-fed hard switching PWM and soft-switching PWM converters are carried out from a viewpoint of their PWM converter characteristics.

• Environmental Engineering Research
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• 제23권3호
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• pp.309-315
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• 2018

Chlortetracycline (CTC) is one of the most important compounds in antibiotic production, and its distribution has been widely investigated due to health and ecological concerns. This study presents systematic approach to optimize the high-performance liquid chromatography-tandem mass spectrometry for analyzing CTC in a multiple reaction monitoring mode ($479{\rightarrow}462m/z$). One-factor-at-a-time (OFAT) test with response surface analysis (RSA) was used as optimization strategy. In OFAT tests, the fragmentor voltage, collision energy, and ratio of acetonitrile in the mobile phase were selected as major factors for RSA. The experimental conditions were determined using a composite in cube design (CCD) to maximize the peak area. As a result, the partial cubic model precisely predicted the peak area response with high statistical significance. In the model, the (solvent composition) and (collision $energy^2$) terms were statistically significant at the 0.1 ${\alpha}$-level, while the two-way interactions of the independent variables were negligible. By analyzing the model equation, the optimum conditions were derived as 114.9 V, 15.7 eV, and 70.9% for the fragmentor voltage, collision energy, and solvent composition, respectively. The RSA, coupled with the CCD, offered a comprehensive understanding of the peak area that responds to changes in experimental conditions.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2006년도 춘계학술대회
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• pp.241-244
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• 2006

Recently wind turbines become large, constructed as farms and going out to offshore. Different design approach from onshore is needed for offshore wind turbine. At this paper concept and preliminary design of an offshore wind turbine of 3MW rated power are performed. The concept design started from modelling of the generator and gearbox. With these modelling the optimum specifications was acquired. Integrated type of drive train is designed with all parts are mounted on the tower top as the offshore maintenance strategy. At the preliminary stage control system, power production algorithm and safety system are designed. Load calculation is also performed. The 3MW offshore wind turbine concept/preliminary design and the process of design are obtained as results.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 추계학술대회논문집
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• pp.962-966
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• 2004

Ball screw feed drive systems have been broadly used in machine tools or precision automatic feed systems. Recently, modern machine tools require high speed and high precision and drive system to achieve high productivity. Unfortunately, a feed drive system, even though it was optimum designed, may experience severe transient vibrations during high-speed operation if its feed rate control is unsuitable. A rough feed rate curve having discontinuity in its acceleration profile causes a serious vibration problem in the feed slide system. This paper presents a feed rate optimization of a machine tool feed slide system, which is driven by a ball screw, for its minimum vibrations. Firstly, a 6-degree-of-freedom lumped parameter model was proposed for the vibration analysis of a ball screw driven machine tool feed drive system. Next, a feed rate optimization of the feed slide was carried out for minimum vibrations. The feed rate curve optimization strategy is to find out the most appropriate acceleration profile having finite jerk. Of course, the optimized feed rate should approximate to the desired one as possible. A genetic algorithm with variable penalty function was used in this feed rate optimization.

• 한국분무공학회지
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• 제26권3호
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• pp.135-141
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• 2021

High-efficient HEV Engine cooling systems reflects variable coolant temperature because it can decrease the hydrodynamic frictional losses of lubricated engine parts in light duty conditions. In order to safely raise the operating temperature of passenger cars to a constant higher level, and thus optimize combustion and all accompanying factors, a new thermostat technology was developed : the electronically map-controlled thermostat. In this work, various crystalline plastics such as polyphthalamide (PPA) and polyphenylenesulfide (PPS) mixed with various glass fiber amounts were introduced into plastic fittings of automotive electronic controlled thermostat for the purpose of suppressing influx of coolant into the element and undesirable opening during hot soaking. Skirt was installed around element frame of automotive electronic controlled thermostat for improving thermal sensitivity in terms of response time, hysteresis and melting temperature. To validate the effectiveness and optimum shape of skirt, thermal sensitivity test and three-dimensional CFD simulation have been performed. As a consequence, important improvement in thermal sensitivity with less than 3℃ of maximum coolant temperature between opening and engine inlet was obtained.

• 마이크로전자및패키징학회지
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• 제29권1호
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• pp.1-6
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• 2022

The mobile device industry demands much higher levels of integration and lower costs coupled with a growing awareness of the complete system's configuration. A subsystem module package is similar to a board-level circuit that integrates a system function in a package beyond a System-in-Package (SiP) design. It is an advanced IC packaging solution to enhance the PDN and achieve a smaller form factor. Unlike a system-level design with a decoupling capacitor, a subsystem module package system needs to redefine the role of the capacitor and its configuration for PDN performance. Specifically, the design of package's form factor should include careful consideration of optimal PDN performance and the number of components, which need to define the decoupling capacitor's value and the placement strategy for a low impedance profile with associated cost benefits. This paper will focus on both the static case that addresses the voltage (IR) drop and AC analysis in the frequency domain with three specific topics. First, it will highlight the role of simulation in the subsystem module design for the PDN. Second, it will compare the performance of double-sided component placement (DSCP) motherboards with the subsystem module package and then prove the advantage of the subsystem module package. Finally, it will introduce three-terminal decoupling capacitor (decap) configurations of capacitor size, count and value for the subsystem module package to determine the optimum performance and package density based on the cost-effective model.

• Smart Structures and Systems
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• 제32권1호
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• pp.37-47
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• 2023

Indirect determination of pan evaporation (PE) has been highly regarded, due to the advantages of intelligent models employed for this objective. This work pursues improving the reliability of a popular intelligent model, namely multi-layer perceptron (MLP) through surmounting its computational knots. Available climatic data of Fresno weather station (California, USA) is used for this study. In the first step, testing several most common trainers of the MLP revealed the superiority of the Levenberg-Marquardt (LM) algorithm. It, therefore, is considered as the classical training approach. Next, the optimum configurations of two metaheuristic algorithms, namely cuttlefish optimization algorithm (CFOA) and teaching-learning-based optimization (TLBO) are incorporated to optimally train the MLP. In these two models, the LM is replaced with metaheuristic strategies. Overall, the results demonstrated the high competency of the MLP (correlations above 0.997) in the presence of all three strategies. It was also observed that the TLBO enhances the learning and prediction accuracy of the classical MLP (by nearly 7.7% and 9.2%, respectively), while the CFOA performed weaker than LM. Moreover, a comparison between the efficiency of the used metaheuristic optimizers showed that the TLBO is a more time-effective technique for predicting the PE. Hence, it can serve as a promising approach for indirect PE analysis.

• 국제학술발표논문집
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• The 5th International Conference on Construction Engineering and Project Management
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• pp.141-144
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• 2013

This paper presents a system called a Cash-flow based Construction Schedule Optimization system(CfSO). The existing CPM effectively handles schedule and cost management. However, funding strategy should be considered to obtain maximum profit and to progress a project favorably. One of measures is to coordinate the contract terms between owner and subcontractors (or suppliers). Contractor may decrease the interest cost attributed to project financing by adjusting the timing of cash-inflows and cash-outflows. It is an excellent method maximizing profits. This paper presents a method to estimate the amount of a cash-flow occurred periodically by integrating the terms of contract into scheduling. The proposed method is implemented as a system prototype in Microsoft Excel. This system provides a user an automated tool that identifies an optimal schedule that secures maximum profit by adjusting start and finish times of non-critical activities' free-floats without affecting on the project completion time. This system supports a project manager to establish an optimum project schedule and identifies profitable contractual conditions against to a construction owner.

• 패션비즈니스
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• 제1권2호
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• pp.55-64
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• 1997

This study adapted OSL (Optimum Stimulation Level) to induce the customer's behavior, especially customer's fashion behavior. The purpose of the fashion advertisement was to accelerate the purchasing desire for the clothes by catching the customer's attention. OSL is one of the methods. OSL can satisfy customers' desires using the new stimulation that reveals a customer's individual characters. In general, women are more concern about fashion and sensitive to the clothes of new fashion than men. But nowadays, many of the men are also concern about their appearance and fashion. The differences between men and women in fashion behavior and in each factor, of OSL, especially a relationship between OSL factor and fashion behavior are researched in this study. Such differences analyzed to find the sources that can satisfy their various desires. This study was expected to provide good information to plan advertising strategy in unpredictable market situation. The subjects for this study were 308 male and female university students. Mehrabian and Russell (1974),s ASTS(Arousal Seeking Tendency Scale) was adapted to measure the OSL, and twenty questions regarding fashion leadership and clothing importance released by Kwon, Shin, Lee, are adapted to measure the fashion behavior. An ANOVA was used as statistical analyzing method to find out the difference between men and women in fashion behavior. The relationship between fashion behavior and difference between men and women in OSL factors were measured by MANOVA. Conclusions were as follows; 1. In consciousness degree of fashion leadership and clothing importance in the fashion behavior, women were higher than men. 2. There was a difference between men and women in OSL's each factors in "unusual stimuli" and "sensuality", but there is no significant statistical difference in factors of "change", "risk", "new environment". Therefore women are higher than men in the stimulation level of "unusual stimuli" and" sensuality". 3. Low element of OSL relating to fashion behavior is from "change" and "unusual stimuli". 4. For the relationship between OSL and fashion behavior, fashion leadership and clothing importance were recognized better in the group of higher level of "change" and "unusual stimuli" irrespective of sex. In the case of "change" which is one of OSL factors, High OSL groups were higher than low OSL groups in the consciousness level of the fashion leadership and clothing importance. In men's case, High OSL-Change groups were higher than Low OSL-Change groups in the fashion leadership, but there was no difference between two groups in the consciousness of the clothing importance. In the case of "Unusual Stimuli", High OSL groups were superior to Low OSL groups in the fashion leadership, but there was no significant difference between two groups in the clothing importance. In women's case, High OSL-Change groups were superior to Low OSL-Change groups. In the case of "Unusual Stimuli", High OSL groups were superior to Low OSL groups in the fashion leadership, but there was no difference between two groups in the clothing importance.