• Journal of the KSME
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• v.37 no.10
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• pp.41-46
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• 1997

철강구조물 부재 내에 노치나 균열이 존재할 수 있고, 외부의 피로하중에 의하여 취약부에서 발생한 균열이 진전하여 전구조물의 최종파손을 야기시킬 수 있다. 부재를 보다 안전하게 사용하고 또한 신뢰성을 확보하기 위해서는 이미 손상된 부재에서 균열의 진전상태를 계측할 수 있는 방법이 확립되어져야 하고, 파괴역학적 파라미터를 이용한 사용재의 균열진전거동특성이 평가되어야 한다. 균열길이의 측정방법은 지금까지 많은 연구자들에 의하여 개발되어져 왔는데 크게 광학현미경을 이용하여 육안으로 직접 균열길이를 측정하는 방법과 컴플라이언스, 초음파, AE 또는 전기적 신호를 통하여 얻어진 결괄부터 균열길이로 환산하는 간접적인 방법으로 대별된다. 대부분의 균열길이의 측정방법은 많은 수작업이 요구되고, 특히 하한계응력확대계수영역의 미세한 균열진전량을 측정하기에는 어려움이 따르고 있다. 이에 대하여 전도체 시험편에 일정전류를 흐르게 하고 균열길이의 증가에 따라 변화하는 전위차로 이를 균열길이로 평가하는 전기적인 측정방법이 있다. 이 방법은 실험장치가 비교적 간단하고 미세한 균열길이의 측정이 용이하여 균열길이의 직접적인 측정이 곤란한 고온역 그리고 충격하중하에서의 균열길이 측정에 이용이 확대되고 있다. 이 글에서는 여러 균열길이 측정방법의 장.단점에 대하여 고찰하고, 그 중 많은 장점을 갖고 있는 직류전위차법의 실험방법을 소개한다.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.4 no.2
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• pp.33-40
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• 1990

고압 수은등의 전기적 특성을 예측하기 위한 컴퓨터 프로그램을 작성하였다. 즉 고압기체방전에서 성립되는 단위체적당 에너지 평형식과 입자의 밀도에 대한 연속방정식을 방전관의 반경과 시간에 대하여 풀어서 전류값을 예측하였다. 프로그램의 수행결과, 방전광에 입력된 에너지는 방사에너지로 가장 크게 손실되며, 전도손실은 시간에 무관하게 거의 일정한 것으로 나타났다. 또한 비교적 길이가 짧은 방전관의 특성을 예측하기 위하여 음극강하를 고려하여 산정한 길이를 추정하는 방법을 개발하였다.

• Journal of IKEEE
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• v.24 no.4
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• pp.1129-1135
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• 2020

The effects of battery aging limit the rechargeable capacity, State of Health(SoH). It is very important to estimate the SoH in the battery monitoring system(BMS) and many algorithms of measuring the internal resistance of the battery were proposed. A method is used by applying a current source of a specific frequency to the battery and measuring the voltage response. When charging harmonic noise is generated in the voltage response, it results in poor resistance measurement accuracy. In this paper, a robust battery internal resistance measurement algorithm is proposed to eliminate the effect of charging noise by integrating the current source and voltage response signals for a certain period. It showed excellent accuracy and stable measurement results. Applying to the BMS for uninterruptible power supply, the usefulness of the proposed method is verified.

• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
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• v.7 no.6
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• pp.709-718
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• 2017

The installation of the elevator ARD(Automatic Rescue Device) system has been forced into law in these days in order to safely rescue passengers during power failure. The configuration of the ARD system consists of energy storage device, power converter and control systems. The EDLC(Electric Double Layer Capacitor) are used as energy storage device for rapid charge/discharge purposes. The power conditioning system (PCS) consists of bi-directional converter, 3-phase converter and control system. The dead-beat control system is adopted for most systems however it requires complex mathematical calculations, the high performance microprocessors are mandatory and thus it can be a cause of high manufacturing cost. In this paper the new control method for average current mode control is presented for simple structure. The control algorithm is applied to the single phase system and then expands to three phase system to meet the sysem requirements. The mathematical modeling using average modeling method is presented and analysed by PSIM computer simulation to verifie the validity of the proposed control methods.

• Journal of the Korean Chemical Society
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• v.34 no.6
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• pp.600-605
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• 1990

Electron injection from excited rose bengal into the conduction band of a thin film of SnO$2$, semiconductor was investigated in an electrochemical cell, ITO/SnO$2$/rose bengal, NaClO$4$/Pt. It was observed that urea enhanced the supersensitized photocurrent, followed by the reduction in the photocurrent after a shallow maximum. Spectroscopic analyses of the dye solution containing urea revealed that dye aggregation appeared to be involved in the increased photocurrent, although the concentration of the dye was continuously decreased dye to photochemical reactions.

• Proceedings of the KIPE Conference
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• 2010.11a
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• pp.38-39
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• 2010

태양광 및 풍력발전에서 계통연계 인버터의 LCL필터설계 시계통에 주입되는 전류의 고조파 저감만을 고려하였으나 연료전지 발전과 같이 독립부하가 존재하는 경우, 이 같은 설계 기법을 적용 시 독립부하의 전압은 일정한 품질을 보장할 수 없다. 본 논문에서는 계통에 주입되는 전류 품질 뿐만 아니라 독립부하의 전압 품질도 고려한 LCL필터 설계방법을 제안한다.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.11b
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• pp.475-480
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• 1996

Alloy 600 및 Alloy 690의 Caustic 분위기에서, 시편의 포텐셜을 재료의 anodic polarization curve의 active-passive transition 영역의 한 값으로 일정하게 유지함으로서 응력부식균열을 쉽게 유발시키는 정전위 시험방법을 사용하여, 두 합금의 부식저항성을 비교하였다. C-ring형태의 Alloy 600 및 690 시편에 응력을 부과하고 30$0^{\circ}C$의 10% NaOH용액에서 7일간 정전위 응력부식시험을 수행하였다. Alloy 600의 경우, 입계를 따르는 100$\mu$m정도 깊이의 균열이 발생하였으나 Alloy 690의 경우는 균열이 유발되지 않았다. Alloy 690의 경우 부식 시험시간이 경과함에 따라 표면부식전류밀도는 주기적인 Passivation 경향을 보이나 Alloy 600의 경우는 점진적으로 표면부식전류밀도가 증가한다. Alloy 690의 강한 응력부식저항성은 이와 같은 주기적인 Passivation에 의한 것으로 판단된다.

• The Transactions of the Korean Institute of Power Electronics
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• v.9 no.4
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• pp.356-363
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• 2004

This paper presents a precision voltage control technique of a single phase PWM inverter for a constant voltage and constant frequency(CVCF) applications. The proposed control scheme employs an additional phase-locked loop(PLL) compensator which is constructed using the output capacitor voltage and current. The computer simulation and experiment are carried out for the actual single-phase PWM inverter and it is well demonstrated from these results that the steady-state performance and total harmonic distortion(THD) are remarkably improved by employing the proposed technique.

• Journal of IKEEE
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• v.24 no.3
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• pp.883-889
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• 2020

In this paper, we propose a method to use PV(Park's Vector) pattern for inductive motor stator fault diagnosis using CNN(Convolution Neural Network). The conventional CNN based fault diagnosis method was performed by imaging three-phase currents, but this method was troublesome to perform normalization by artificially setting the starting point and phase of current. However, when using PV pattern, the problem of normalization could be solved because the 3-phase current shows a certain circular pattern. In addition, the proposed method is proved to be superior in the accuracy of CNN by 18.18[%] compared to the previous current data image due to the autonomic normalization.

• Journal of the Korea Concrete Institute
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• v.21 no.4
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• pp.409-417
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• 2009

In this study, autogenous crack healing and artificial crack healing using electrochemical electro deposition method were conducted to compare in the aspects of corrosion monitoring. Furthermore, the analysis of impressed voltage characteristics, galvanic current and linear polarization resistance comparison, and photo image processing technique were performed for quantitative comparisons of healing ratio. As a result, it was found that, in view of impressed voltage of artificial crack healing, the measured voltage was increased as time goes by. From the galvanic test results of artificial crack healing, the current vs. potential distribution value were formed widely in comparison with autogenous crack healing. In this point, it was shown that artificial crack healing has more eleatic resistance capacity than autogenous crack healing technique. Finally, it was found that artificial crack healing was 1.63 times higher than autogenous healing in view of crack healing ratio.