• 전력전자학회논문지
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• 제19권5호
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• pp.391-398
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• 2014

This paper presents a resonant step-down DC/DC converter to reduce the voltage stresses of a 3-phase inverter module under the three-phase AC utility line condition. Under this condition, a conventional 3-phase inverter module suffers from high voltage stresses as a result of the high rectified DC link voltage; hence, a high-cost high-voltage-rating inverter module must be used. However, using the proposed converter, a low-cost low-voltage-rating inverter module may be adopted to drive the motor even under the 3-phase AC line condition. The proposed converter, which can be realized with small size inductor and low-voltage-rating semiconductor devices, operates at a high-efficiency mode because of the zero-current switching operations of all the semiconductor devices. The operational principles are explained and a design example is provided in the study. Experimental results demonstrate the validity of the proposed converter.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2000년도 가을 학술발표회 논문집
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• pp.493-500
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• 2000

Rock Mass Rating has been widely applied to the underground tunnel excavation and many other practical problems in rock engineering. However, Rock Mass Rating is hard to make out because it is difficult to estimate each valuation items through all kind of field situations and items of RMR have interdependence. So the experts of tunnel assessment have problems with rating rock mass. In this study, using multivariate analysis based on domestic data(1011EA) of water conveyance tunnel, we presented rock mass rating system which is objective and easy to use. The constituents of RMR are decided to RQD, condition of discontinuities, groundwater conditions, orientation of discontinuities, intact rock strength, spacing of discontinuities in important order. In each step, we proposed the best multiple regression model for RMR system. And using data which have been collected at other site, we examined that presented multiple regression model was useful.

• 한국염색가공학회지
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• 제23권4호
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• pp.263-273
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• 2011

Digital textile printing(DTP) technology made considerable advances in recent years. In this study, a pre-treatment agent has been prepared for the better coloration of digital textile printing. The ink formulation contained three kinds of 5g thickener (CMC, Sodium alginate, Dextrin), 25g urea, 5g sodium carbonate, and 465g distilled water. The optimal sharpness of outline was found in the 1-3% concentration of the pre-treating agent with a viscosity of 10-15 cSt. Even if the color difference between untreated and treated samples was not apparent in the printing step, the color appearance increased after steaming. The color appearance of cyan, magenta, yellow, black reactive colorants increased in the order of CMC>Sodium alginate>Dextrin. Wash fastness to shade change and staining for the treated samples were 4-5 rating, while untreated sample was 1-2 rating. Also, the pre-treated sample with 1:1 mixtures had 4-5 rating. Both dry and wet rubbing fastness to shade change and staining were excellent in the treated samples, whereas rubbing fastness of untreated sample was 1-2 rating. With exception of 3 rating to black color, light fastness properties were 4 rating for the remaining three colors in the regardless of treatment condition and mixing of pre-treating agents. Dry cleaning fastness of all samples were also 4-5 rating irrespective of treatment condition and mixing of pre-treating agents.

• Smart Structures and Systems
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• 제20권2호
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• pp.139-150
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• 2017

The structural strain plays a significant role in structural condition assessment of in-service bridges in terms of structural bearing capacity, structural reliability level and entire safety redundancy. Therefore, it has been one of the most important parameters concerned by researchers and engineers engaged in structural health monitoring (SHM) practices. In this paper, an SHM system instrumented on the Jiubao Bridge located in Hangzhou, China is firstly introduced. This system involves nine subsystems and has been continuously operated for five years since 2012. As part of the SHM system, a total of 166 fiber Bragg grating (FBG) strain sensors are installed on the bridge to measure the dynamic strain responses of key structural components. Based on the strain monitoring data acquired in recent two years, the strain-based structural condition assessment of the Jiubao Bridge is carried out. The wavelet multi-resolution algorithm is applied to separate the temperature effect from the raw strain data. The obtained strain data under the normal traffic and wind condition and under the typhoon condition are examined for structural safety evaluation. The structural condition rating of the bridge in accordance with the AASHTO specification for condition evaluation and load and resistance factor rating of highway bridges is performed by use of the processed strain data in combination with finite element analysis. The analysis framework presented in this study can be used as a reference for facilitating the assessment, inspection and maintenance activities of in-service bridges instrumented with long-term SHM system.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1990년도 가을 학술발표회 논문집
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• pp.45-50
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• 1990

This study develops practical models and methods for the assessment of safety and capacity rating of existing P.C. girder bridges based on the reliability methods. One of the main objectives of the study is to propose a practical but realistic limit state model for safety assessment and LRFR rating criteria, which explicitly incorporates the degree of deterioration and damage as well as actual condition of P.C. girder bridges in terms of the damage factor and the response ratio. The damage factor proposed in the paper is defined as the ratio of the current estimated stiffness to the intact base-line stiffness of a member. Based on the observation and the results of applications to existing bridges, it may be concluded that the proposed methods for the assessment and capacity rating models, which explicitly account for the uncertainties and effects of degree of deterioration or damage, provide more realistic and consistent safety-assessment and capacity rating.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2010년도 제34회 춘계학술대회논문집
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• pp.231-238
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• 2010

75톤급 기술검증용 연소기의 저압 조건 연소안정성 시험이 수행되었다. 동일한 추진제 유량을 연소실에 공급하면서 분사기 수량이 감소된 연소기 헤드의 경우 연소압력 30 bar에서 자발 불안정이 발생하였으나, 분사기 수량이 증가된 연소기 헤드에서는 동일한 연소압력 조건에서 고주파 연소안정성이 유지됨을 보였다. 30 bar에서 연소안정성을 보인 연소기 헤드는 연소압력 20 bar에서 자발 불안정이 발생하여 안정성 경계 영역을 보여주었다.

• 한국산학기술학회논문지
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• 제15권5호
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• pp.3046-3050
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• 2014

본 연구는 음성장애 청지각적 평가인 EAI(등간척도)와 VAS(시각적 아날로그 척도)의 차이점, 각 평가방법에 대한 평가자 자가-신뢰도(confidence rating)을 알아보았다. 30명의 언어병리전공 학생들이 음성장애로 진단받은 화자(N=25)의 발성과 읽기 샘플을 듣고 EAI는 7점 척도, VAS는 0-10cm의 직선에 음성장애 정도를 표시했고, 판단에 대한 자가 신뢰도 점수는 7점 척도로 실시했다. 음성장애 정도에 대한 판단의 준거가 제시되는 상황(조건 1)과 그렇지 않은 상황(조건 2)에서 모음 연장발성과 읽기 과제에 대해 각각 실시했다. 연구 결과, 발성이나 읽기과제에서 모두 동일하게 모두 VAS평가 점수가 높게 산출되었고, 통계적으로 유의하였다. 그 외 조건 1의 읽기과제와 조건 2의 발성과제에 대한 EAI와 VAS평가 점수 간에는 차이가 없었다. 이러한 결과는 음성장애 화자들의 발화 과제와 청지각적 평가유형이 청취자들의 지각적인 판단에 영향을 미칠 수 있으며, 이에 대한 보다 집중된 임상 연구가 계속되어야 할 것을 시사한다.

• 한국의류학회지
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• 제28권9_10호
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• pp.1265-1272
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• 2004

The purpose of this study is to develope wrinkle recovery property, DP rating of Tencel by using BTCA(1,2,3,4-butanetetracarboxylic acid) and MgCl$_2$ that does not make water pollution. The adoptable condition to improve the wrinkle resistance and DP rating was determined 10％ BTCA(o.w.f), 3％ catalyst(o.w.f), 0.5％ softener(o.w.f), 5min padding time, 150$^{\circ}C$ curing temperature, 2min curing time and pH 2.7. It was proven that ester groups were formed and cross-links increased by treating Tencel with BTCA. By XPS diffraction, Tencel treatment using BTCA was proved not to affect crystal formation.

• 한국터널지하공간학회 논문집
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• 제14권5호
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• pp.503-516
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• 2012

터널 시공 중 암반등급은 지보패턴의 결정에 큰 영향을 주는 요소이다. 따라서 터널 설계 시에 터널이 시공되는 노선의 암반등급을 파악하기 위해서 시추조사를 수행한다. 시추구간 사이의 미시추 구간에서는 전기비저항 탐사, 탄성파 탐사 등과 같은 지구물리탐사를 통해 암반등급을 파악한다. 따라서 전기비저항과 암반등급의 상관관계를 찾기 위한 연구가 다수 수행되었다. 그러나 대부분의 연구는 실내시험 또는 전기비저항 탐사로부터 얻어진 전기비저항과 암반등급의 상관관계에 대한 연구이다. 따라서 본 연구에서는 현장의 전기비저항 검층 시험으로부터 얻어진 전기비저항과 RMR의 상관관계를 분석하였다. 현장 데이터 분석 결과, 전기비저항과 RMR은 약 90%이상의 매우 높은 상관관계가 있는 것으로 나타났다. 또한 RMR 평가 요소들과 전기비저항의 상관관계 분석을 수행한 결과, 전기비저항과 불연속면상태는 약 80%이상의 양호한 상관관계가 나타났으나 지하수상태는 약 57%이하의 낮은 상관관계가 나타났다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2000년도 가을 학술발표회 논문집(II)
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• pp.1285-1290
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• 2000

The inspection of bridge condition is of extreme importance. Current inspection codes for bridge inspection are vague and uncertain. So, the results are highly subjective and different from person to person and even day to day for a given person. To circumvent possible inconsistencies in inspection and rating of bridge components, the revised inspection guidelines have been proposed.