• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 춘계학술대회 논문집
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• pp.277-282
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• 2011

Bogie frame is typical safety part of railway vehicle. Total serviceable life of bogie frame will be evaluated by Cumulative Damage Approach Method that is defined by dynamic strain measurement during revenue service under the actual track conditions. As a result of the standardization process developed in British Standard Institution, BS 7608 defines for fatigue design and test method of steel structure by fatigue test results over the long period. This paper evaluates the total serviceable life applying BS 7608 for the bogie frame of Electric Multiple Unit to verify structural safety of the bogie frame.

• 정신신체의학
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• 제9권2호
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• pp.164-173
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• 2001

연구목적: 피로는 일차 진료에서 흔한 증상이지만 비특이적 주관적 특성상 명확한 정의와 객관적 평가가 어렵고, 특히 기질적 질환이 없는 피로의 평가는 더욱 힘들다. 이에 저자들은 기질적 질환이 없는 피로 환자에게 Fatigue severity scale (FSS) 을 적용하여 그 유용성을 알아보고자 하였다. 방법: 피로환자 44명, 우울 또는 불안증의 정신과 환자 43명과 대조군 45명에게 피로도, 스트레스, 우울 불안 척도를 이용하여 FSS의 신뢰도와 타당도를 조사하였다. 결과: FSS의 신뢰도 계수는 0.935이었고 재검사의 상관관계 계수는 0.916이었다 (p<0.01). FSS 점수는 피로 군에서 유의하게 가장 높았고 대조군에서 가장 낮았다 (p<0.01). FSS와 Chalder fatigue scale의 상관관계 계수는 0.782로 높았다 (p<0.01). 피로군과 대조군에 대한 FSS index의 최적의 절단점은 민감도 84.1%. 특이도 85.7%인 3.22로 조사되었다. 결론: FSS는 일차진료에서 기질적 질환이 없는 피로환자와 우울 또는 불안증 환자에서 피로도를 평가할 수 있는 유용한 도구이며, 향후 보다 많은 환자를 대상으로 한 연구가 필요하리라 생각된다.

• 여성건강간호학회지
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• 제6권3호
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• pp.398-412
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• 2000

The purpose of this study was to identify a relationship between housework hours and fatigue level in middle-aged women. The subjects were 204 women living in Seoul and near the city, ranging in ages of 30-59(mean = 41.6 year) and were interviewed during the month of Oct. to Dec. 1999. The following questionnaires were utilized in this study: a self reporting housework time measurement table and a fatigue symptom scale originated from Yoshitake (1978). The analysis of the data was done by SAS program, t-test, ANOVA, and Pearson correlation. The results of this study were as follows : 1. Total mean hours of housework of the subjects were shown 9.2 hours on weekdays and 8.9 hours on weekend. Mean hours according to the area of houseworks on weekdays and on weekend were preparing and providing meal 3.9 and 4.2, doing laundry and maintaining clothes 3.1 and 1.6, keeping and maintaining house 1.6 and 1.4, caring family 1.3 and 1.2, and keeping household records 0.5 both. 2. With respect to the general characteristics of the subjects, there were significantly difference in age, job, religion, type of family, number of children, experience of present and previous illness, and perceived body size. 3. Average fatigue scores of the subjects were 16.6 of total score 60. Fatigue scores by the area were neuroperceptive fatigue 6.5, mental fatigue 5.2, and physical fatigue 4.9 in order. There were significantly differences in the score of fatigue by religion, number of family, present illness, and perception of body size. 4. There were significantly positive relationships in the scores of fatigue with the total hours of housework, preparing and providing meal, doing laundry and maintaining clothes, keeping and maintaining house, and caring family. 5. The physical fatigue scores were positively related with the areas of preparing and providing meal, doing laundry and maintaining clothes. While the mental fatigue scores were positively related the areas of preparing and providing meal, caring family, and keeping and maintaining house, and neuroperceptive fatigue scores were positively related with the areas of keeping and maintaining house and caring family. The recommendations from this study were further studies to investigate how middle-aged women manage their fatigue level, increase public awareness of middle aged women's fatigue level, and develop programs for middle-aged women to help with high fatigue.

• 한국감성과학회:학술대회논문집
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• 한국감성과학회 2000년도 춘계 학술대회 및 국제 감성공학 심포지움 논문집 Proceeding of the 2000 Spring Conference of KOSES and International Sensibility Ergonomics Symposium
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• pp.195-202
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• 2000

• 대한기계학회논문집A
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• 제27권5호
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• pp.673-680
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• 2003

This study verified the relationship between fracture mechanics parameters(ΔK, ΔK$\sub$eff/, K$\sub$max/) and X-ray parameters (${\alpha}$$\sub$r/, B) for SG365 steel at elevated temperature up to 300$^{\circ}C$. The fatigue crack propagation test were carried out and X-ray diffraction technique according to crack length direction was applied to fatigue fractured surface. The residual stress on the fracture surface was found to increase low ΔK region, reach to a maximum value at a certain value of K$\sub$max/ or ΔK and then decrease. Residual stress were independent on stress ratio by arrangement of ΔK and half value breadth were independent by the arrangement of K$\sub$max/. The equation of ${\alpha}$$\sub$r/ - ΔK was established by the experimental data. Therefore, tincture mechanics parameters could be estimated by the measurement of X-ray parameters.

• 한국해양공학회지
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• 제16권3호
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• pp.54-58
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• 2002

This study investigates a relationship between fracture mechanics parameters (Stress Intensity Factor Range: ΔK, Maximum Stress Intensity Factor; Kmax) and X-ray parameters (residual stress:$\sigma$r half-value breadth: B) for SG365 steel at elevated temperature up to 30$0^{\circ}C$. The fatigue crack propagation test were carried out and X-ray diffraction technique according to the direction of crack length was applied to fatigue fractured surface. The residual stress on the fracture surface was found to increase at low ΔK region, to reach a maximum value at a certain value of Kmax or ΔK and then to decrease. Residual stress was independent of stress ratio by arrangement of ΔK and half value breadth were independent of the arrangement of Kmax. The equation of $\sigma$r-ΔK was established by the experimental data. therefore, fracture mechanics parameters could be estimated by the measurement of X-ray parameters.

• 대한전기학회논문지:시스템및제어부문D
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• 제55권7호
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• pp.344-351
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• 2006

The fatigue of back muscle in the repetitive lifting motion was studied using multiple parameters(FFT_MDF, RMS, 2C, NT) in this study. Recent developments in the time-frequency analysis procedures to compute the IMDF(instantaneous median frequency) were utilized to overcome the nonstationarity of EMG signal using Cohen-Posch distribution. But the above method has a lot of computation time because of its complexity. So, in this study, FFT_MDF(median frequency estimation based on FFT) algorithm was used for median frequency estimation of back muscle EMG signal during muscle work in uniform velocity portion of lumbar movement. The analysis period of EMG signal was determined by using the run test and lumbar movement angle in dynamic task, such as lifting. Results showed that FFT_MDF algorithm is well suited for the estimation of back muscle fatigue from the view point of computation time. The negative slope of a regression line fitted to the median frequency values of back muscle EMG signal was taken as an indication of muscle fatigue. The slope of muscle fatigueness with FFT_MDF method shows the similarity of 77.8% comparing with CP_MDF(median frequency estimation based on Cohen Posch distribution) method.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집A
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• pp.317-323
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• 2001

This study verified the relationship between fracture mechanics parameters$({\Delta}K,\;{\Delta}K_{eff},\;K_{max})$ and X-ray parameters $(\sigma_r,\;B)$ for SG365 steel at elevated temperature up to $300^{\circ}C$. The fatigue crack propagation test were carried out and X-ray diffraction technique according to crack length direction was applied to fatigue fractured surface. The residual stress on the fracture surface was found to increase low ${\Delta}K$ region, reach to a maximum value at a certain value of $K_{max}\;or\;{\Delta}K$ and then decrease. Residual stress were independent on stress ratio by arrangement of ${\Delta}K$ and half value breadth were independent by the arrangement of $K_{max}$. The equation of $\sigma_r-{\Delta}K$ was established by the experimental data. Therefore, fracture mechanics parameters could be estimated by the measurement of X-ray parameters.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2017년도 제48회 춘계학술대회논문집
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• pp.240-244
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• 2017

가스터빈 엔진의 구성품 개발단계에서 블레이드의 Aeromechanics 시험은 블레이드 진동설계와 구조 안정성 검증 프로세스 사이에서 중요한 연결 고리를 제공한다. 이 전제에 근거하여 본 연구에서는 NSMS(Non-Intrusive Stress Measuring Systems)를 축류 압축기 구성품 시험리그에 적용하여 Tip Timing 센서가 장착된 단에서 모든 블레이드의 정적/동적 변위를 시험적으로 측정하였다. 진동 특성 분석을 통해 블레이드 고주기 손상을 유발할 수 있는 피로임계위치(Fatigue Critical Location)에서의 진동 응력을 평가하였으며, 공력가진에 의한 비동기 진동응답 및 개별 블레이드 Mistuning 패턴을 제시하였다.

• 대한기계학회논문집
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• 제13권5호
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• pp.938-946
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• 1989

본 연구에서는 CT시험편을 이용하여 소규모 항복조건하에서 하한계(near threshold)영역과 안전균열성장(제II)영역의 균열진전거동을 파악하고 피로균열 진전속도와 음향방출거동, 파단면 특성을 각각 비교, 고찰하여 각 파라미터간의 상관 관계 및 유용성을 검토하고자 한다.