• 품질경영학회지
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• 제35권2호
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• pp.37-44
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• 2007

Today, the statistical process control (SPC) in manufacture environment is an important role at the process by the productivity improvement of the manufacturing systems. The control chart in this statistical method is widely used as an important statistical tool to find the assignable cause that provoke the change of the process parameters such as the mean of interest or standard deviation. But the traditional SPC don't grasp the change of process according to the points fallen the near control limits because of monitoring the variance of process such as the fixed sampling interval and the sample size and handle the cost of the aspect of these sample point. The control chart can be divided into the statistical and economic design. Generally, the economic design considers the cost that maintains the quality level of process. But it is necessary to consider the cost of the process improvement by the learning effects. This study does the economic design in the VSI $\bar X$ control chart and added the concept of loss function of Taguchi in the cost model. Also, we preyed that the VSI $\bar X$ control chart is better than the FSI $\bar X$ in terms of the economic aspects and proposed the standard of the process improvement using the VSI $\bar X$ control chart.

• 한국콘텐츠학회논문지
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• 제10권4호
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• pp.225-235
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• 2010

본 연구는 심폐소생술 교육 경험이 없는 중학생의 심폐소생술에 관한 노래 동영상 자가 학습과 심폐소생술 동영상 자가 학습(VSI)과의 교육 효과를 파악함으로써, 중학생을 대상으로 효과적인 심폐소생술 교육방법을 위한 기초자료를 제공하고자 시도하였다. 연구의 대상자는 G광역시에 소재한 S중학교 3학년 학생을 대상으로 편의표집하여 총 68명으로 실험군 33명, 대조군 35명이 최종 실험처치까지 참여하였다. 조사기간은 2009년 4월 22일부터 23일까지 2일에 걸쳐서 자료를 수집하였다. 연구 결과는 중학생을 대상으로 한 심폐소생술에 관한 노래 동영상 자가 학습이 심폐소생술 동영상 자가 학습(VSI)보다 좋은 결과가 나왔다고는 볼 수는 없다. 하지만 교육 효과가 확인되었으므로 중학생을 대상으로 한 심폐소생술 교육에 있어 유용하게 활용 될 수 있을 것으로 사료된다.

• 천문학회보
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• 제31권2호
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• pp.53.2-53.2
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• 2006

• 융합신호처리학회논문지
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• 제12권4호
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• pp.333-340
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• 2011

한국천문연구원은 한일상관센터 (Korea-Japan Correlation Center, KJCC)에 2009년부터 한일공동VLBI상관기(Korea-Japan Joint VLBI Correlator, KJJVC)를 설치하여 운영하고 있다. 한일공동VLBI상관기는 한국우주전파관측망(Korean VLBI Network, KVN), VERA(VLBI Exploration of Radio Astrometry), JVN(Japanese VLBI Network) 및 공동 관측망 등에서 관측한 VLBI(Very Long Baseline Interferometer) 데이터를 상관처리하고, 과학적 목적을 위해 관측데이터를 처리하는 전용 계산기로 사용된다. KJJVC는 각 구성시스템 사이의 데이터 입출력 규격으로 VLBI 국제표준인 VSI(VLBI Standard Interface)를 따르고 있다. 특히 관측된 데이터를 상관처리하기 위해 고속재생기인 Mark5B시스템과 동기재생처리장치(Raw VLBI Data Buffer, RVDB) 사이에는 1024 Mbps급으로 데이터가 전송된다. 고속 데이터 전송에 있어 발생하는 전자기 방해 (Electromagnetic Interference, EMI)는 관측데이터의 손실을 야기 시키며, 전송 케이블의 길이가 길수록 손실 발생빈도가 많고, 디지털 데이터 신호의 전압레벨을 감소시켜 데이터 인식 오류를 초래한다. 따라서 본 논문에서는 VSI 규격의 통신에서 발생하는 EMI 잡음 정도를 측정하고, 데이터 손실을 최소화할 수 있는 방법으로 1) RC 필터를 사용한 방법, 2) Microstrip 라인을 이용한 임피던스 매칭, 3) Differential line driver를 이용한 신호 복원 방법 등을 제안하였다. 각 제안방법들의 유효성을 확인하기 위해 제안방법들은 시뮬레이션과 실험적인 구현을 통하여 성능시험을 수행하였으며, 각각의 제안 방법이 VSI 규격의 고속 데이터 전송에 유효함을 확인하였다.

• Journal of Electrical Engineering and Technology
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• 제6권2호
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• pp.215-225
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• 2011

In this paper, a buck DC-DC bridge converter is used as a power factor correction (PFC) converter for feeding a voltage source inverter (VSI) based permanent magnet brushless DC motor (PMBLDCM) drive. The front end of the PFC converter is a diode bridge rectifier (DBR) fed from single phase AC mains. The PMBLDCM is used to drive the compressor of an air conditioner through a three-phase voltage source inverter (VSI) fed from a variable voltage DC link. The speed of the air conditioner is controlled to conserve energy using a new concept of voltage control at a DC link proportional to the desired speed of the PMBLDC motor. Therefore, VSI operates only as an electronic commutator of the PMBLDCM. The current of the PMBLDCM is controlled by setting the reference voltage at the DC link as a ramp. The proposed PMBLDCM drive with voltage control-based PFC converter was designed and modeled. The performance is simulated in Matlab-Simulink environment for an air conditioner compressor load driven through a 3.75 kW, 1500 rpm PMBLDC motor. To validate the effectiveness of the proposed speed control scheme, the evaluation results demonstrate improved efficiency of the complete drive with the PFC feature in a wide range of speed and input AC voltage.

• Journal of Power Electronics
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• 제9권5호
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• pp.679-690
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• 2009

The paper presents a new photovoltaic inverter for stand-alone induction motor application. The proposed system is composed of two stages. First stage is for the photovoltaic dc power feeding and second stage is dedicated to the motor-inverter subsystem and control technique. A direct torque control (DTC) with a novel switching strategy for motor torque ripple minimization is introduced. The novel DTC strategy is based on selecting a suitable voltage vector group for motor torque ripple minimization. A three-level voltage source inverter (VSI) is used instead of a two level inverter because the first has more available vectors and lower ripples in the output current and flux than the second, thus it has lower torque ripples. The photovoltaic array and battery bank are sized and the configuration is indicated based on sun-hour methodology. Simulation results show a comparison between three systems; two level VSI with conventional DTC strategy, three level VSI with conventional DTC, and the proposed system that has a novel DTC switching strategy applied to three level VSI. The results show that the proposed system has lower ripples in the current, flux and torque of the motor.

• Journal of Power Electronics
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• 제10권5호
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• pp.477-484
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• 2010

A pulse width modulation-voltage source inverter (PWM-VSI) is used for variable speed permanent magnet synchronous motor (PMSM) drives. The PWM-VSI fed PMSM has two major disadvantages. Firstly, the PWM-VSI DC-link voltage limits the magnitude of the PMSM terminal voltage. As a result, the motor speed is restricted. Secondly, in a low speed range, the PWM-VSI modulation index declines. This is caused by a high DC-link voltage and a low terminal voltage ratio. As a result, the distortion of the voltage command and the stator current are increased. This paper proposes an optimal pulse amplitude modulation (PAM) control which can adjust the inverter DC-link voltage by using a buck-boost DC-DC converter. At a low speed range, the proposed system can reduce the distortion of the voltage command, which improves the stator current waveform. Also, the allowable speed range is extended. In order to verify the proposed method, experimental results are provided to confirm the simulation results.

• 한국학교ㆍ지역보건교육학회지
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• 제10권1호
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• pp.1-16
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• 2009

Objectives: This study aims to perform comparative analysis of educational effects between video self-instruction (VSI) and basic cardiopulmonary resuscitation among college students in some areas. Methods: This study was conducted with 57 college students (28 for control group and 29 for experimental group) in U Metropolitan City from September 27 to October 5, 2007, and SPSS 14.0 Version was used for analysis. Results: As for differences in attitudes before and after cardiopulmonary resuscitation training, the experimental group (1.48) was higher than the control group (.91), which was significant (p<.001). The experimental group (9.56) also showed higher knowledge score than the control group (7.79) with significant differences (p<.05). The former (3.93) also showed higher concrete self-efficacy than the latter (2.17). with significant differences (p<.05). The experimental group (43.24) showed higher practical performance ability than the control group (34.48), with no significant difference. The former (30.93) also showed higher accuracy in chest compression skill than the control group (20.25). with no significant difference.

• 한국통신학회논문지
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• 제15권11호
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• pp.886-897
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• 1990

본 논문은 PWM 패턴의 연적 펄스폭 사이에서 정의된 선형관계에 기초한 새로운 optimal PWM 방식을 제시하였다. 새로운 PWM 방식에서 펄스폭 계산은 MW와 CW의 방정식에 의존하지않고 수행할 수 있다. 이 방식에 의해 마이크로프로세서로 제어되는 인버터를 위한 PWM 패턴은 패턴의 연적 펄스폭에서 최적 증분치를 얻으므로서 쉽게 구성할 수 있다. 더구나, PWM 인버터의 출력에서 고조도레벨은 본 PWM패턴이 최소 THD를 기초로 선정되기 때문에 항상 적다. 본 방식을 1(HP), 삼상 유도전동기에 적용시켜 종래의 regular PWM 방식과 비교해 보았다. 계산 및 실험의 결과에서 새로운 optiaml PWM 방식이 VSI-PWM 인버터에서 고조도를 최소화하기 위한 효과적인 일반화 연구임을 보였다.

• Journal of Power Electronics
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• 제16권3호
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• pp.970-981
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• 2016

Leakage currents occur in pulse-width-modulated voltage source inverter (PWM-VSI)-fed permanent magnet synchronous motor (PMSM) drives for air-conditioners, which seriously affect system safety and operation performance. High accuracy modeling and prediction of leakage currents are key issues for the design and implementation of air-conditioning products. In this study, the generation mechanism of leakage currents is discussed. A systematic modeling approach of leakage currents is proposed, including the modeling of leakage current sources and leakage current paths. By using the proposed approach, the complete model of leakage currents in PWM-VSI-fed PMSM drives for air-conditioners has been developed based on the extraction of all parameters. A comparison between the simulated leakage currents based on the developed model and measured leakage currents in the outdoor unit of an air-conditioning product is conducted. The comparison verifies the effectiveness of the proposed modeling approach, and the developed model exhibits high accuracy within a wide frequency range.