• Journal of Preventive Medicine and Public Health
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• 제33권4호
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• pp.469-476
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• 2000

Objectives : To analyze differences in health behaviors among the social strata in Korea by using the 1995 National Health and Health Behavior Survey Data. Methods : Study Participants numbered 2,352 men and 1,016 women aged between 15-64 years old, with housewives, students and non-waged family workers excluded. Health behaviors in this study were defined according to the recommendations of the Alameda 7 study. The measure of health behaviors was based on the Health Practices Index(HPI; 0-5 range, with the exclusion of snacking between meals and regularly eating breakfast) developed by the Alameda County research. The significance of the relationship between social strata and HPI was assessed by considering the adjusted means from the multi-variate model. Results : For men, incidence rates of never having smoked, no/moderate use of alcohol, regular exercise, and regular 7-8 hours sleep per night were higher in the upper social strate. Meanwhile, for women, incidence rates of never having smoked, no/moderate use of alcohol, appropriate weight, regular exercise, and regular 7-8 hours sleep per night were higher in the upper strata. HPI varied significantly among social strata in both sexes (p<0.001), a result which held true when adjusted for age, education, income, social insurance type, marital status and region. Conclusions : Health behaviors assessed by Health Practices Index(HPI) varied significantly among social strata for both sexes. Therefore, the existing gap in health behaviors among social strata can be corrected more effectively by target oriented health promotional activities.

• Geomechanics and Engineering
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• 제20권6호
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• pp.547-556
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• 2020

An understanding of the influence of MR (Magmatic Rock) thickness on the surrounding rock behaviors is essential for the prevention and management of dynamic disasters in coal mining. In this study, we used FLC3D to study the breaking and instability laws of surrounding rock with different MR thicknesses in terms of strata movement, stress and energy. The mechanism of dynamic disasters was revealed. The results show that the thicker the MR is, (1) the smaller the subsidence of the overlying strata is, but the subsidence span of the overlying strata become wider, and the corresponding displacement deformation value of the basin edge become smaller. (2) the slower the growth rate of abutment pressure in front of the working face is, but the peak value is smaller, and the influence range is larger. The peak value decreases rapidly after the breaking, and the stress concentration coefficient is maintained at about 1.31. (3) the slower the peak energy in front of coal wall, but the range of energy concentration increases (isoline "O" type energy circle). Finally, a case study was conducted to verify the disaster-causing mechanism. We anticipate that the research findings presented herein can assist in the control of dynamic hazards.

• Geomechanics and Engineering
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• 제22권4호
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• pp.349-359
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• 2020

Quantification of the influence of the fracture of thick magmatic rock (TMR) on the behavior of its overlying strata is a prerequisite to the understanding of the deformation behavior of the earth's surface in deep mining. A three-dimensional numerical model of a special geological mining condition of overlying TMR was developed to investigate the overburden movement and fracture law, and compare the influence of the occurrence horizon of TMR. The research results show that the movement of overlying rock was greatly affected by the TMR. Before the fracture of TMR, the TMR had shielding and controlling effects on the overlying strata, the maximum vertical and horizontal displacement values of overlying strata were 0.68 m and 0.062 m. After the fracture, the vertical and horizontal displacements suddenly increased to 3.06 m and 0.105 m, with an increase of 350% and 69.4%, respectively, and the higher the occurrence of TMR, the smaller the settlement of the overlying strata, but the wider the settlement span, the smaller the corresponding deformation value of the basin edge (the more difficult the surface to crack). These results are of tremendous importance for the control of rock strata and the revealing of surface deformation mechanism under TMR mining conditions in mines.

• 대한예방의학회:학술대회논문집
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• 대한예방의학회 1999년도 제51차 추계 학술대회 연제집
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• pp.41-41
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• 1999

• Geomechanics and Engineering
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• 제19권3호
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• pp.269-282
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• 2019

Due to top-coal and immediate roof as cushion layer connecting with support and overlying strata, it can make significant influence on strata behaviors in fully mechanical top-coal caving working face (TCCWF). Taking Qingdong 828 working face as engineering background, $FLAC^{3D}$ and $UDEC^{2D}$ were adopted to explore the influence of top-coal thickness (TCT), immediate roof thickness (IRT), top-coal elastic modulus (TCEM) and immediate roof elastic modulus (IREM) on the vertical stress and vertical subsidence of roof, caving distance, and support resistance. The results show that the maximum roof subsidence increases with the increase of TCT and IRT as well as the decrease of TCEM and IREM, which is totally opposite to vertical stress in roof-control distance. Moreover, although the increase of TCEM and IREM leading to the increase of peak value of abutment pressure, the position and distribution range have no significant change. Under the condition of initial weighting occurrence, support resistance has negative and positive relationship with physical parameters (e.g., TCT and IRT) and mechanical properties (e.g., TCEM and IREM), respectively.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1999년도 가을 학술발표회 논문집
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• pp.431-438
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• 1999

Vertical congressive and horizontal pile load tests were performed to a instrumented large diameter (D : 1,000 mm) drilled shaft. A drilled shaft was penetrated into the weathered soil and weathered rock. PMT was done for evaluation of properties for these strata. It was expected to be difficult to get undisturbed samples of weathered soils and rocks. Thus. PMT was done at the several selected depths. In those strata, to prevent the test bore hole from collapsing, bentonite slurry was used for making the test bore hole. In this study. soil properties was evaluated by means of PMT results and estimating method (direct method, the Memard method) of vertical pile capacity and horizontal pile behaviors were summarized. Also, vertical and horizontal pile capacity were calculated using PMT and pile load test results.

• Geomechanics and Engineering
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• 제19권3호
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• pp.255-268
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• 2019

Taking top-coal caving mining face (TCCMF) as research object, this paper considers the combination of top-coal and immediate roof as cushion layer to build the solution model of support resistance based on the theory of elastic foundation beam. Meanwhile, the physical and mechanical properties of coal-rock combination influencing on strata behaviors is explored. The results illustrate that the subsidence of main roof in coal wall increases and the first weighting interval decreases with the increase of top-coal and immediate roof thicknesses as well as the decrease of top-coal and immediate roof elastic modulus. Moreover, the overlying strata reflecting on support has negative and positive relationship with top-coal thickness and immediate roof thickness, respectively. However, elastic modulus has limit influence on the dead weight of top-coal and immediate roof. As a result, it has similar roles on the increase of total support resistance and overlying strata reflecting on support in the limit range of roof control distance. In view of sensitive analysis causing the change of total support resistance, it can be regards as the rank of three components as immediate roof weight > overlying strata reflecting on support > top coal weight. Finally, combined with the monitoring data of support resistance in Qingdong 828, the validity of support resistance determined based on elastic foundation beam is demonstrated, and this method can be recommended to adopt for support type selecting in TCCMF.

• 농촌의학ㆍ지역보건
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• 제34권2호
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• pp.202-213
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• 2009

본 연구는 농촌지역 청소년들의 건강행태를 도시지역 청소년들과 비교하기 위해 2005년에 실시한 전국청소년건강행태 온라인 조사 자료를 이용하여 분석하였다. 그 결과 흡연경험률, 중학교 입학전 흡연경험률, 음주빈도, 음주후 위험행동 경험률, 점심 및 저녁 결식, 과일 및 우유 섭취, 칫솔질 횟수, 구강질환 증상 경험, 구강 진료 경험, 구강 에방진료. 안전 및 위생의식 등의 행태에서 도시지역 청소년에 비해 바람직하지 못 한 결과를 보였다. 이러한 결과가 지역규모에 따른 차이인지 혹은 도농간의 사회경제적 수준의 격차와 관련이 있는지에 대하여 향후 추가적인 연구가 필요하다. 본 조사 결과를 통해 청소년 건강행태 개선을 위한 건강증진사업은 농촌 청소년을 대상으로 우선적으로 수행하여야 할 당위성을 확인하였다고 할 수 있다.

• 한국학교ㆍ지역보건교육학회지
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• 제10권2호
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• pp.43-54
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• 2009

Objectives: Adolescent health risk behaviors are typically smoking, drinking, violence, and the use of harmful media. The articles published in the literature are about those behaviors which was individually studied. Teenagers, however, are likely to have those behaviors simultaneously such as smoking and drinking. Also, the use of media and harmful materials are common among adolescents. This study was conducted with the purpose of investigating the relationship of smoking, drinking, the use of harmful media. Methods: This study was a secondary analysis using the data drawn from National Youth Committee's survey of adolescent harmful environment in 2007. The self-reported questionnaires were administered to 7,409 students attending junior high schools between October 10 and November 20. The samples were randomly selected based on strata of geography, schools, and gender. Results: Junior high school students used the harmful media ranging from 13.9 % to 31% depending on the type of media. The most accessed one was adult-only games. The current smoking rates was 5.4% and drinking rates was 27.4%. There are statistically significant relationship between smoking and the use of harmful media, between drinking and the use of harmful media, and between smoking and drinking. The behavioral factors that can predict the use of harmful media based on logistic regression analysis are the grade and smoking. Conclusion: Students were at risk of engaging health risk behaviors as they were getting older. Like other literature, smoking was a significant predictor of adolescent behavioral problems.

• 터널과지하공간
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• 제14권4호
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• pp.295-303
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• 2004

연약층과 견고한 암반층이 습곡형태로 혼재된 지질조건의 지하 심부 채굴 현장을 대상으로, 심부 급경사 연약층의 단계적 굴착 진행에 따른 갱도 및 주변 암반의 거동 양상을 전산해석과 현장계측을 통하여 비교 분석하였다. 전산해석에서는 Hoek ＆ Brown의 경험적 파괴기준 및 변형률연화모델을 적용한 탄소성 해석 기법을 이용하였다. 현장계측에서는 유압캡슐, 지중변위계, 내공변위계를 갱도 및 주변 암반에 설치하여 응력과 변위를 계측하였다. 경험적 파괴조건 및 변형률연화모델을 이용한 탄소성 해석은, 현장 지질조건 및 채굴과정의 복잡함에도 불구하고 현장계측결과와 유사한 양상을 보여주어 타당성을 검증할 수 있었다. 이러한 전산해석 및 현장계측의 비교를 통해 지하 굴착 갱도의 변형 거동 과정을 예측하고 이후의 굴착 및 지보보강 설계의 지침을 제공할 수 있을 것이다.