• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제50권5호
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• pp.238-245
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• 2001

During an AC motor's start-up accelerating period, a large amount of current is required to reach to the rating speed. This is called in-rush current. This peak in-rush current can be more than about several times the operating or steady-state current in the full load rating of the motor. In-rush current is present in both and electronic ballasts. The main area of concern is the tripping of circuit breaker and fuses which can affect electrical system components From this, we can see that the electrical power controllers will be rather concerned, since they have to supply the actual current necessary to start the motor. This paper presents a new method to reducing in-rush current and energy saving of the single-phase induction motor used in air-conditioner. It can be obtained that proposed system is low cost and small size as compared with other controller. Experiments are focused on a capacitor starting single-phase induction motor. The optimal power saving and in-rush current limiting by phase angle control are verified by experimental results. Also, auxiliary winding was controlled by electronic starting switch.

• 대한한의학회지
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• 제24권2호
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• pp.12-18
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• 2003

Objectives : Hypertension is very prevalent disease, and causes serious cardiovascular complications. Nowadays optimal hypertension treatment is emphasized to reduce the incidence of cardiovascular complications. Auricular acupuncture therapy is economical, safe and effective. Its clinical application is various, and it can be used to control blood pressure. So The effect of auricular acupuncture therapy was investigated. Daily variation of blood pressure during needle-embedded period and variation of blood pressure by blood pressure classification were observed. Methods : The auricular acupuncture points we used were Gangapjeom (降壓點), Sinmun (神門), Gyogam (交感), Sim(心), and Icheom (耳尖). Auricular acupuncture needles were embedded for three days. Blood pressure was checked four times per day and the mean obtained. Results : The following results were obtained : 1. During needle-embedded period, systolic and diastolic blood pressure decreased. Blood pressure decreased most significantly 2 days after treatment. 2. The change of blood pressure in the higher blood pressure group was more remarkable than that of the lower blood pressure group. Conclusions : Through this research, auricular acupuncture therapy is considered as an effective and safe method to lower blood pressure.

• 한국시뮬레이션학회논문지
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• 제12권3호
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• pp.31-40
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• 2003

This paper studies an optimal policy for a certain class of (s, S) inventory control systems, where the demands are characterized by the renewal arrival process. To minimize the average cost over a simulation period, we apply a stochastic optimization algorithm which uses the gradients of parameters, s and S. We obtain the gradients of objective function with respect to ordering amount S and reorder point s via a combined perturbation method. This method uses the infinitesimal perturbation analysis and the smoothed perturbation analysis alternatively according to occurrences of ordering event changes. The optimal estimates of s and S from our simulation results are quite accurate. We consider that this may be due to the estimated gradients of little noise from the regenerative system simulation, and their effect on search procedure when we apply the stochastic optimization algorithm. The directions for future study stemming from this research pertain to extension to the more general inventory system with regard to demand distribution, backlogging policy, lead time, and inter-arrival times of demands. Another direction involves the efficiency of stochastic optimization algorithm related to searching procedure for an improving point of (s, S).

• KIEAE Journal
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• 제17권4호
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• pp.83-88
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• 2017

Purpose: The objective of this study is to develop a predictive model for calculating the amount of cooling load for the different setback temperatures during the setback period. An artificial neural network (ANN) is applied as a predictive model. The predictive model is designed to be employed in the control algorithm, in which the amount of cooling load for the different setback temperature is compared and works as a determinant for finding the most energy-efficient optimal setback temperature. Method: Three major steps were conducted for proposing the ANN-based predictive model - i) initial model development, ii) model optimization, and iii) performance evaluation. Result:The proposed model proved its prediction accuracy with the lower coefficient of variation of the root mean square errors (CVRMSEs) of the simulated results (Mi) and the predicted results (Si) under generally accepted levels. In conclusion, the ANN model presented its applicability to the thermal control algorithm for setting up the most energy-efficient setback temperature.

• Journal of Power Electronics
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• 제18권5호
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• pp.1369-1379
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• 2018

In this paper, a model predictive torque control (MPTC) without the use of a weighting factor for surface mounted permanent-magnet synchronous machine (SPMSM) drive systems is presented. Firstly, the desired voltage vector is predicted in real time according to the principles of deadbeat torque and flux control. Then the sector of this desired voltage vector is determined. The complete enumeration for testing all of the feasible voltage vectors is avoided by testing only the candidate vectors contained in the sector. This means that only two voltage vectors in the sector need to be tested for selecting the optimal voltage vector in each control period. Thus, the calculation time can be reduced when compared with the conventional enumeration method. On the other hand, a novel cost function that only includes the dq-axis voltage errors between the desired voltage and candidate voltage is designed to eliminate the weighting factor used in the conventional MPTC. Thus, the control complexity caused by the tuning of the weighting factor is effectively decreased when compared with the conventional MPTC. Simulation and experimental investigation have been carried out to verify the proposed method.

• Journal of Power Electronics
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• 제17권1호
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• pp.76-87
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• 2017

Finite-set predictive current control (FS-PCC) is advantageous for power converters due to its high dynamic performance and has received increasing interest in multilevel inverters. Among multilevel inverter topologies, the cascaded H-bridge (CHB) inverter is popular and mature in the industry. However, a main drawback of FS-PCC is its large computational burden, especially for the application of CHB inverters. In this paper, an FS-PCC method based on a deadbeat solution for three-phase zero-common-mode-voltage CHB inverters is proposed. In the proposed method, an inverse model of the load is utilized to calculate the reference voltage based on the reference current. In addition, a cost function is directly expressed in the terms of the voltage errors. An optimal control actuation is selected by minimizing the cost function. In the proposed method, only three instead of all of the control actuations are used for the calculations in one sampling period. This leads to a significant reduction in computations. The proposed method is tested on a three-phase 5-level CHB inverter. Simulation and experimental results show a very similar and comparable control performance from the proposed method compared with the traditional FS-PCC method which evaluates the cost function for all of the control actuations.

• 한국정보과학회논문지:시스템및이론
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• 제27권1호
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• pp.61-67
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• 2000

산업용 실시간 시스템에서 사용되는 디지털 제어기는 상호 작용하는 주기적 태스크들로 이루어져 있다. 이러한 태스크들은 최대 수행 주기 (maximum activation periods)를 제약조건으로 가짐으로써, 요구되는 제어특성을 유지한다. 그러므로 실시간 시스템을 개발하는데 있어 필수적인 단계는 각각의 태스크에 게 자원 이용률을 최소화하면서 최대 수행 조건을 만족시킬 수 있는 고정된 주기를 할당하는 것이다.[1] 각각의 태스크간의 생산자/소비자(producer/consumer)관계를 나타내주는 태스크 그래프와 자원 요구량, 그리고 주기에 대한 범위제한이 주어진다면 주기 할당 문제는 비선형 최적화 문제가 된다. 이 논문에서는 최적해의 자원이용률의 두 배를 넘지 않는 해를 찾을 수 있는 선형 수행시간의 근사 알고리즘을 제시한다. 실험 결과에서 알 수 있듯이, 제안된 알고리즘은 대부분의 경우 최적해에 매우 근접한 해를 가지게 된다.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2022년도 추계학술대회
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• pp.52-52
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• 2022

Recently, PE (polyethylene) film has been used increasingly in com cultivation. However, PE films often cause soil and environment contamination. In order to reduce this problem, many researches have been carrying out studies on biodegradable films (BF) that are easily decomposed by soil microorganisms. Therefore, this study was conducted to determine which BF is optimal for growth and yield of com crops while also having the highest rates of film decomposition. BFs Farmsbio (Farm Hannong), Heulgro Film (Sejin Bio), Vonto Film (Eco-Hansung) as well as a selected PE film were used in this study. For the control, we used crops grown without any kind of mulching. Experimental fields were fertilized according to conventional cultivation methods, tilled, and then covered by either BF or PE. After 1 week, com (cv. MIBECK2ho) at the 3-leaf stage (16 days after seeding) was transplanted. Plant height was measured at 18 and 32 days after transplanting and heading stages. Yield components and yield were also measured at harvest. In addition, pH, EC, and decomposition and light transmittance levels of films were investigated during the experimental period. Daily average temperature, relative humidity and organic matter in soils were also measured during the experimental period. There was no significant difference in plant height, heading date, and silking between crops with BFs and PE, but the crops grown with BFs and PE films reached higher growth parameters in a shorter amount of time than the crops in the non-mulching control. Additionally, there were no significant differences in yield components such as length of ears, ear width, ear weight, and yield in crops that were grown using films or crops in the control plot. Light transmittance and decomposition levels of films generally increased with time after transplanting, and was highest in the Heulgro film than other BFs. Soil pH and organic matter in crops using BFs and PE films were significantly higher than in the control plot at 99 and 113 days after transplanting. In general, the EC contents in the control plot was lower than in crops using BFs and PE films. The average daily moisture in soil was higher when BFs and PE films were used than in the control plot. However, the daily average soil temperature was higher in crops using BFs and PE films than in the control plots at the beginning of the experimental period, but there was no consistent difference in soil temperature towards the later part of the experimental period. Therefore, the BFs used in this study were shown to be helpful without causing negative impacts on the growth and yield of com.

• Journal of Ginseng Research
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• 제46권2호
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• pp.290-295
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• 2022

Background: Dried and red ginseng are well-known types of processed ginseng and are widely used as healthy food. The dried and red ginseng quality may vary with the storage period of raw ginseng. Therefore, herein, the effect of the storage period of fresh ginseng on processed ginseng quality was evaluated through multicomponent quantification with statistical analysis. Methods: A method based on ultrahigh performance liquid chromatography coupled to triple quadrupole mass spectrometry in multiple-reaction monitoring mode (UPLC-MRM-MS) was developed for quantitation of ginsenosides and oligosaccharides in dried and red ginseng. Principal component analysis and partial least squares discriminant analysis were conducted to evaluate the dynamic distributions of ginsenosides and oligosaccharides after different storage periods. Results: Eighteen PPD, PPT and OLE ginsenosides and nine reducing and nonreducing oligosaccharides were identified and quantified. With storage period extension, the ginsenoside content in the processed ginseng increased slightly in the first 2 weeks and decreased gradually in the following 9 weeks. The content of reducing oligosaccharides decreased continuously as storage time extending, while that of the nonreducing oligosaccharides increased. Chemical conversions occurred during storage, based on which potential chemical markers for the storage period evaluation of fresh ginseng were screened. Conclusion: According to ginsenoside and oligosaccharide distributions, it was found that the optimal storage period was 2 weeks and that the storage period of fresh ginseng should not exceed 4 weeks at 0 ℃. This study provides deep insights into the quality control of processed ginseng and comprehensive factors for storage of raw ginseng.

• 대한교통학회지
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• 제14권2호
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• pp.59-88
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• 1996

본 연구는 신호교차로에서으 교통변화에 따른 교통상태를 실 시간으로 정확히 판별해 내기 위한 루프 검지기의 적정 형태 및 위치를 결정하였다. 교차로 정시선의 직진용 루프검지기의 적정 형태는 점유와 비점유시간의 신뢰도로서 결정하였으며, 도시간선도로상의 실시간 교통신호제어의 적용에 가장 적합한 루프는 특수형 루프가 적합하다고 판단된다. 결정된 특수형(7,8번) 및 기존검지기(1번)의 형태와 권선방식은 <그림6.1>에 제시하였다. 직진용 루프의 적정 위치는 정지선 부근에서의 차량의 이용특성상 정지선으로부터 50Cm이내에 설치하는것이 바람직하다고 판단되며, 좌회전용 루프의 적정 위치는 정지선 부근의 좌회전 차선 이용행탱로서 결정되며, 루프 한개를 설치할 경우에는 정지선으로부터 20Cm이내에 설치하는것이 바람직하다. 상류부 루프의 적정형태는 특수형 루프(1.8${\times}$4.0m:1,7번)와 기존시스템에서 사용하고 있는 루프(1.8${\times}$1.8m:1번)가 검지기준에 따라 모두 적합하다고 판단되었다. 대기행렬 검지기 및 앞막힘(Spillback) 예방 검지기의 위치는 링크길이,횡단보도여부,대기행렬 예측범위 등을 고려하여 각 검지기의 위치가 결정되었으며 또한 링크길이 250m이하인 경우는 대기행렬을 관리(Queue Management)하는 측명에서 검지기위치가 고려되어야 한다.