• Title/Summary/Keyword: protective behavior

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Reinforcing Effects around Face of Soil-Tunnel by Crown & Face-Reinforcing - Large Scale Model Testing (천단 및 막장면 수평보강에 의한 토사터널 보강효과 - 실대형실험)

  • Kwon Oh-Yeob;Choi Yong-Ki;Woo Sang-Baik;Shin Jong-Ho
    • Journal of the Korean Geotechnical Society
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    • v.22 no.6
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    • pp.71-82
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    • 2006
  • One of the most popular pre-reinforcement methods of tunnel heading in cohesionless soils would be the fore-polling of grouted pipes, known as RPUM (reinforced protective umbrella method) or UAM (umbrella arch method). This technique allows safe excavation even in poor ground conditions by creating longitudinal arch parallel to the tunnel axis as the tunnel advances. Some previous studies on the reinforcing effects have been performed using numerical methods and/or laboratory-based small scale model tests. The complexity of boundary conditions imposes difficulties in representing the tunnelling procedure in laboratory tests and theoretical approaches. Full-scale study to identify reinforcing effects of the tunnel heading has rarely been carried out so far. In this study, a large scale model testing for a tunnel in granular soils was performed. Reinforcing patterns considered are four cases, Non-Reinforced, Crown-Reinforced, Crown & Face-Reinforced, and Face-Reinforced. The behavior of ground and pipes as reinforcing member were fully measured as the surcharge pressure applied. The influences of reinforcing pattern, pipe length, and face reinforcement were investigated in terms of stress and displacement. It is revealed that only the Face-Reinforced has decreased sufficiently both vertical settlement in tunnel heading and horizontal displacement on the face. Vertical stresses along the tunnel axis were concentrated in tunnel heading from the test results, so the heading should be reinforced before tunnel advancing. Most of maximum axial forces and bending moments for Crown-reinforced were measured at 0.75D from the face. Also it should be recommended that the minimum length of the pipe is more than l.0D for crown reinforcement.

Experimental Study on Combined Failure Damage of Bi-directional Prestressed Concrete Panel under Impact-Fire Loading (충돌 후 화재에 대한 이방향 프리스트레스트 콘크리트 패널부재의 복합 파괴손상에 관한 실험적 연구)

  • Yi, Na-Hyun;Lee, Sang-Won;Choi, Seung-Jai;Kim, Jang-Ho Jay
    • Journal of the Korea Concrete Institute
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    • v.26 no.4
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    • pp.429-440
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    • 2014
  • Since the World Trade Center and Pentagon attacks in 2001, terror, military attack, or man-made disaster caused impact, explosion, and fire accident have frequently occured on civil infrastructures. However, structural behavior researches on major Prestressed Concrete (PSC) infrastructures such as bridges, tunnels, Prestressed Concrete Containment Vessel (PCCVs), and LNG tanks under extreme loading are significantly lacking. Especially, researches on possible secondary fire scenarios after terror, bombing, collision of vehicles and vessels on concrete structures have not been performed domestically where most of the past researches related to extreme loadings on structures focused on an independent isolated extreme loading scenario. Due to the outcry of public concerns and anxiety of potential terrorist attacks on major infrastructures and structures, a study is urgently needed at this time. Therefore, in this study, the bi-directional prestressed concrete $1400{\times}1000{\times}300mm$ panels applied with 430 kN prestressing force using unbonded prestressing thread bars were experimentally evaluated under impact, fire, and impact-fire combined loadings. Due to test site restrictions, impact tests were performed with 14 kN impactor with drop heights of 10m and 3.5 m to evaluate impact resistance capacity. Also, fire and impact-fire combined loading were tested using RABT fire loading curve. The measured residual strength capacities of PSC and RC specimens applied with impact, fire, impact-fire combined loadings were compared with the residual strength capacity of undamaged PSC and RC specimens for evaluation. The study results can be used as basic research data for related research areas such as protective design and numerical simulation under extreme loading scenarios.

A Survey on the Knowledge and Attitude of Workers Concerning Occupational Health (근로자의 산업보건 지식과 태도에 관한 조사연구)

  • 박영식;조수열;남철현
    • Journal of Environmental Health Sciences
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    • v.18 no.2
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    • pp.3-18
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    • 1992
  • This research was carried out on 1,017 production workers for four months from May to August, 1991, to search more effective management method of their health by grasping their knowledge and attitude on industrial health. The results of this study can be summarized as follows: 1. As for general characteristics, 74.2% were male and 25.8% were female among the 1,017 workers. The two largest age groups were 30~39, 38.7%. As for education level, graduation from high school was 58.6%, 61.2% were married, 35.9% owned their house, and workers who worked more than 1 year less than 5 years was 52.9%, workers who worked 8 hours a day was 46.7%, the largest group income level was 60~69 thousand won 21.2%, and the degree of satisfaction with work was ordinary, 45.6%. 2. The degree of recognition concerning occupational diseases was 92.5% at a very high rate. Causes of occupational diseases under the present work field were in order of noise, dust, heavy metal. The largest group of the counterplan for prevention was an improvement of working environment, 62.0%. 3. The major cause that threatens worker's health was poor working environment, 31.4%. As the best method for workers' health management, working environment management was pointed. 4. As for health examination result, the response that it is of use to health management was 53.8%. As for examination method and result, 42.7% responded that they are formal. The practice period was more than once every six months as the largest group, and the highest desire for improvement was that they wants an exact information of the result. 5. 49.3% of the respondents know about the measurement of working environment an the response that the measurement is necessary to improve working environment was 57.9%, and that the results from the measurement were reflected on improvement an management 57.5%. Appropriate period to take a measurement was more than once per six months, 40.2% and per three months, 29.1%. 6. As for safety and halth instruction, 34.5% were educated for both, 38.2% for only safety education and just 4.6% for only health education. 51.9% responded that they had never been educated out of work place. The period of its practice was more than once a month, 39.5% and every three months, 21.3%. 7. The importance of safety and health showed that the one is equal to the other, 59.8%, that the one is more important, 29.6%, and that other is more important, 7.6%. 67.7% said the necessity of a safety and health manager. 8. In spite of more or less health obstacle of work environment, 14.9% of the respondents wanted to overwork to gain an allowance for over-time work, 39.9% didn't, and 40.2% according to condition and state. 9. As the most important cause of industrial accident, 40.2% indicated unsafe behavior. As for the individual protective instrument, 66.1% of all the respondents said they have worn it to protect industrial diseases. 10. As for the degree of understanding of the contents in Industrial Safety and Health Law and Industrial Law of Accident Insurance, an affirmative response was respectively 49.3% and 50.8% and the sources of safety-health information were televisions and radios, 28.0%. Therefore, it is necessary that we do positive working environmental improvement, continuous management and health education's inforcement to increase their health and prevent occupational diseases.

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Anti-amnesic and Neuroprotective Effects of Artemisia argyi H. (Seomae mugwort) Extracts (섬애쑥 추출물의 뇌 신경세포 보호효과에 의한 학습 및 기억능력 개선 효과)

  • Ha, Gi-Jeong;Lee, Doo Sang;Seung, Tae Wan;Park, Chang Hyeon;Park, Seon Kyeong;Jin, Dong Eun;Kim, Nak-Ku;Shin, Hyun-Yul;Heo, Ho Jin
    • Korean Journal of Food Science and Technology
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    • v.47 no.3
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    • pp.380-387
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    • 2015
  • The anti-amnesic effect of Artemisia argyi H against trimethyltin (TMT)-induced learning and memory impairment and its neuroprotective effect against $H_2O_2$-inducedoxidative stress were investigated. Cognitive behavior was examined by Y-maze and passive avoidance test for 4 weeks, which showed improved cognitive functions in mice treated with the extract. In vitro neuroprotective effects against $H_2O_2$-induced oxidative stress were examined using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium-bromide and lactate dehydrogenase (LDH) assays. A. argyi H. extract showed protective effects against $H_2O_2$-induced neurotoxicity; moreover, LDH release into the medium was inhibited. Finally, high-performance liquid chromatography (HPLC) analysis showed that eupatilin and jaceosidin were the major phenolic compounds in A. argyi H. extract. These results suggest that A. argyi H. could be a good source of functional substances to prevent neurodegenerative diseases.

Thought of ChunChu and a practical solution of Song Joon Kil (동춘당 송준길의 춘추정신과 현실 대응)

  • Kim, Moon Joon
    • The Journal of Korean Philosophical History
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    • no.50
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    • pp.37-74
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    • 2016
  • Song Joon Kil(宋浚吉, 1606-1672) intended to establish the subjectivity of people as a "Great Justice". He declared that at that time "Great Justice" was meant to respect 'Ming(明)' and reject 'Ching'(淸). He understood 'Ching' as a country which destroyed the human community and reasoned that if we put Ching's uncivilized behavior out of our mind in favor of the pursuit of present existence and merits, a temporary peace may be got but eternal peace and stability would not be achieved. 'Ming' doesn't refer only to the name of a country, but a country with the capacity to perform 'humanity and justice' with a human culture. On the other hand, he considered 'Ching' to signify the uncivilised country that destroyed or repressed the humanity and peaceful order of the world. He thought the international order can only be maintained under the organization respectful and protective of humanity. He believed a country should act to unify the whole world guaranteeing life and stability. He possessed this cultivated spirit which acted to protect the civilised world from the perils of an uncivilised world. But because of the great famine for a lot of years and the international state(Ming was regressing, and Ching was continuing to make rapid strides) was timely unsuitable to revenge and to wash the shame off. So Song propeled to stabilize the government and to strengthen the national ethics. Song focused on administering the domestic affairs. To him a high priority was a internal affairs, and a low priority was a external affairs[military aggression]. Song considered 'providing for the welfare of the people'(安民) before 'pushing ahead with military aggression'(外攘). And a high priority was 'restoring the people'(養民), a low priority was 'the military affairs'(治兵). Song regarded 'domestic affairs'(內治) as a fundamental affairs. He putted 'to nurse people'(養民) and 'to straighten King's mind'(格君心) first, than 'to buildup military'. His foreign policy was 'respecting Ming' and 'rejecting Ching'. Song was bothered about defining Chosun dynasty's moral obligations to the southern Ming government(1644~46) at Nanjing at that time.