• 한국안전학회지
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• 제16권3호
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• pp.53-60
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• 2001

This paper presents a graphical method for hazard assessment of electric shock by safety criteria. For the human body to be safety actual body current should not exceed safety criteria, i.e. allowable body current. The assessment method presented in this paper is based m the safety criteria of the IEEE Standard 80 as well as the IEC 479-1. The hazard can be assessed in terms of alterable touch voltages instead of alterable body current. Thus, the hazard assessment of given electric shock condition is referred to a procedure by which the actual touch voltages are compared with the allowable (safe) touch voltages. Since the IEC 479-1 safety criteria are nonlinear, the graphical method is presented for the hazard assessment. Body current and body voltage are calculated with the allowable touch voltage. A comparison of the safety criteria of two widely accepted standards, i.e. the IEEE Std 80 End the IEC 479-1 is proposed. Also Thevenin equivalent resistance is obtained from electric shock model expressed by two-port earth-grid-foot system. On the basis of calculated results, the allowable touch voltage, the body current and the body voltage we can conduct the hazard or safety assessment and estimate the severity of electric shock.

• 동의신경정신과학회지
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• 제7권1호
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• pp.15-37
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• 1996

This thesis investigates 220 female students ranging from 19 to 26 years old attending universities in the Wonju area to determine the correlations between mental health and the density of serum iron . According to their serum iron levels, they were divided into three groups and analyzed with the GARS Scale Assessment and the THI Test Assessment. The results are as follows;1. On the comprehensive GARS Scale tests, for all groups, task, occupation and levels of university-related frustration(1) marked the highest scores.2. On the comparative assessment of each group's GARS Scale scores, Group A showed higher stress perception in terms of personal relationship(2,3) than any orther groups. 3. On the comprehensive THI test scores coverring all groups, Multiple subjective symptoms(I) marked the highest scores. 4. On the comparative assessment of each group's THI test scores, Group A showed higher Multiple subjective symptoms(I) and Irregularities of life(G) than any orther groups.5. Comparing and analyzing the GARS Scale Assessment and the THI Test, we found that Group A showed high stress perception, which may cause psychosomatic diseases such as 'yu zheng(鬱證;melancholia). With those results, we can see that the contant of serum iron is correlated to stress perception and the condition of mental health. In the future studies using the GARS Scale and the THI Test, it will be necessary to examine more subject groups in terms of multi-aspects and to investigate the standard group in more detail.

• 한국물환경학회지
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• 제31권3호
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• pp.319-327
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• 2015

The present study was carried out to develop biological criteria for aquatic ecosystem health assessment using composition and diversity of collected species. The sampling sites were a total of 67 sites in the Han River (29 sites) and the Nakdong River (38 sites), May and September 2012. During the survey period fish were collected totally 93 species. In each water system, 73 and 61 species were collected in the Han River and the Nakdong River respectively. The current composition of fish species between the Han River and Nakdong River showed similar pattern. The dominant species was Zacco platypus of the Han River, and the Nakdong River was Opsariichthys uncirostris. In particular, ecological characteristics of O. uncirostris frequently appeared in general polluted waters. In conclusion, in the Nakdong River, average value of FAI (Fish Assessment Index) was averaged 41.3, indicating a "poor condition", and the Han River was 53.1, indicating a "poor condition". The aquatic health of the Nakdong River assessed based on FAI was considered to be worse than that of the Han River.

• Nuclear Engineering and Technology
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• 제42권6호
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• pp.680-689
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• 2010

The crack-tip stress fields and fracture mechanics assessment parameters for a surface crack, such as the elastic stress intensity factor or the elastic-plastic J-integral, can be affected significantly by the adjacent cracks. Such a crack interaction effect due to multiple cracks can alter the fracture mechanics assessment parameters significantly. There are many factors to be considered, for instance the relative distance between adjacent cracks, the crack shape, and the loading condition, to quantify the crack interaction effect on the fracture mechanics assessment parameters. Thus, the current assessment codes on crack interaction effects (crack combination rules), including ASME Sec. XI, BS7910, British Energy R6 and API 579-1/ASME FFS-1, provide different rules for combining multiple surface cracks into a single surface crack. The present paper investigates crack interaction effects by evaluating the elastic stress intensity factor and the elastic-plastic J-integral of adjacent in-plane surface cracks in a plate through detailed 3-dimensional elastic and elastic-plastic finite element analyses. The effects on the fracture mechanics assessment parameters of the geometric parameters, the relative distance between two cracks, and the crack shape are investigated systematically. As for the loading condition, an axial tension is considered. Based on the finite element results, the acceptability of the crack combination rules provided in the existing guidance was investigated, and the relevant recommendations on a crack interaction for in-plane surface cracks are discussed. The present results can be used to develop more concrete guidance on crack interaction effects for crack shape characterization to evaluate the integrity of defective components.

• 환경영향평가
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• 제20권1호
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• pp.89-96
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• 2011

This study was carried out to assess the variations of water quality caused by the dam construction on the river. Six dams-Yongdam, Miryang, Hoengseong, Boryeong, Jangheung and Buan- constructed recently in Korea were selected for the study. Chemical oxygen demand(COD) was increased in the initial stage of water storage at dams compared to the lotic(river) environment, but after 3 years it was maintained lower and stabilized concentrations. Five dams except for Jangheung Dam were maintained Ia~Ib grade conditions under the water quality criteria of Korea. The concentrations of total nitrogen(T-N) were decreased under the lentic(reservoir) environment compared to the river status. Total phosphorus(T-P) was decreased 13~63% at the reservoir condition. We concluded that increase of COD concentration was due to the debris organic materials of the land, but temporary phenomenon. T-N and T-P concentrations were decreased at the lentic condition compared to the lotic.

• 한국학교수학회논문집
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• 제18권3호
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• pp.335-352
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• 2015

본 논문에서는 P대학에서 시행하는 수학진단평가에 응시한 공과대학 학생 중에서, 대학수학능력시험 수학 B형의 성적이 4~7등급으로 기초수학 교과목을 수강하는 145명을 연구대상으로 선정하였다. 연구대상 학생들의 대학입학능력시험 수학영역 등급, 수학진단평가 성적, 대입전형 유형, 학생실태 설문조사 결과 및 기초수학 교과목 중간고사 성적 등을 비교 분석하여 이들 사이의 상관관계를 알아보고, 교양수학 교과목 수강학생들의 기초학력 향상을 위한 학습지도 방안에 대해 연구하였다.

• Structural Monitoring and Maintenance
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• 제2권2호
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• pp.115-132
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• 2015

This paper presents a new method for seismic vulnerability assessment of buildings with reference to their operational limit state. The importance of this kind of evaluation arises from the civil protection necessity that some buildings, considered strategic for seismic emergency management, should retain their functionality also after a destructive earthquake. The method is based on the identification of experimental modal parameters from ambient vibrations measurements. The knowledge of the experimental modes allows to perform a linear spectral analysis computing the maximum structural drifts of the building caused by an assigned earthquake. Operational condition is then evaluated by comparing the maximum building drifts with the reference value assigned by the Italian Technical Code for the operational limit state. The uncertainty about the actual building seismic frequencies, typically significantly lower than the ambient ones, is explicitly taken into account through a probabilistic approach that allows to define for the building the Operational Index together with the Operational Probability Curve. The method is validated with experimental seismic data from a permanently monitored public building: by comparing the probabilistic prediction and the building experimental drifts, resulting from three weak earthquakes, the reliability of the method is confirmed. Finally an application of the method to a strategic building in Italy is presented: all the procedure, from ambient vibrations measurement, to seismic input definition, up to the computation of the Operational Probability Curve is illustrated.

• 한국지반신소재학회논문집
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• 제17권4호
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• pp.53-64
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• 2018

본 연구에서는 안정성과 위험도 평가의 중요성이 증대되고 있는 DCM(Deep Cement Mixing, 이하 DCM) 보강 지반상의 항만 구조물에 대하여 위험도 평가를 위한 파괴확률을 산정하였다. DCM 개량 지반의 위험도에 영향을 미치는 확률변수로 개량체의 설계기준강도와 시공중첩, 원지반의 강도 및 내부마찰각, 개량지반의 단위중량을 선정하고 관련 통계치를 산정하여 적용하였다. 또한, 상시 조건과 지진시 조건에서의 전체 시스템에 대한 파괴확률을 분석하였다. 본 연구를 통해 DCM 개량지반의 위험도 평가를 위한 확률변수에서 변동계수가 가장 큰 것은 설계기준강도이나 안전율의 변동성 즉, 시스템의 위험도에는 큰 영향을 미치지는 않는 것을 알 수 있었다. DCM 보강 지반에 대한 시스템의 파괴확률 영향인자 즉, 주된 위험요소는 상시 및 지진시 모두 외적안정의 경우 수평활동, 내적안정의 경우 압축파괴인 것으로 평가되었다. 또한, 수평활동에 대해서는 상시 파괴확률이 지진시 파괴확률보다 높고 압축파괴에 대해서는 상시 파괴확률이 지진시 파괴확률보다 낮은 것으로 나타났다. 전체 시스템의 상시 파괴확률과 지진시 파괴확률은 유사하지만, 본 사례의 경우 지진시 위험도가 다소 높은 것으로 나타났다.

• 한국인터넷방송통신학회논문지
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• 제14권5호
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• pp.131-135
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• 2014

본 논문은 상체움직임을 통하여 자세기능의 변화를 나타냈다. 자세의 기능은 상체의 움직임 변화에 따라 자세의 방향성을 분석하였다. 측정항목은 균형시스템에 따라 자세에 대한 평가로 활용하였다. 중추신경은 $0.226{\pm}0.04$의 변화가 발생하였고, 체성감각은 $0.939{\pm}0.46$의 변화, 전정기관은 $4.009{\pm}1.05$이고, 시각은 $8.336{\pm}4.05$로 변화가 나타났다. 본연구의 결과로 상체움직임에 따른 시각적 변화에 미세하게 영향으로 나타났고, 중수신경의 변화에도 다소 변화가 나타남으로 확인하였다.

• Journal of Mechanical Science and Technology
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• 제16권7호
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• pp.889-895
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• 2002

This paper presents the effect of external corrosion, material properties, operation condition and design thickness in pipeline on failure prediction using a failure probability model. The predicted failure assessment for the simulated corrosion defects discovered in corroded pipeline is compared with that determined by ANSI/ASME B31G code and a modified B31G method. The effects of environmental, operational, and random design variables such as defect depth, pipe diameter, defect length, fluid pressure, corrosion rate, material yield stress and pipe thickness on the failure probability are systematically studied using a failure probability model for the corrosion pipeline.