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A caving self-stabilization bearing structure of advancing cutting roof for gob-side entry retaining with hard roof stratum

  • Yang, Hongyun;Liu, Yanbao;Cao, Shugang;Pan, Ruikai;Wang, Hui;Li, Yong;Luo, Feng
    • Geomechanics and Engineering
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    • v.21 no.1
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    • pp.23-33
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    • 2020
  • An advancing cutting roof for gob-side entry retaining with no-pillar mining under specific geological conditions is more conducive to the safe and efficient production in a coalmine. This method is being promoted for use in a large number of coalmines because it has many advantages compared to the retaining method with an artificial filling wall as the gateway side filling body. In order to observe the inner structure of the gateway cutting roof and understand its stability mechanism, an equivalent material simulation experiment for a coalmine with complex geological conditions was carried out in this study. The results show that a "self-stabilization bearing structure" equilibrium model was found after the cutting roof caving when the cut line deviation angle was unequal to zero and the cut height was greater than the mining height, and the caving roof rock was hard without damage. The model showed that its stability was mainly controlled by two key blocks. Furthermore, in order to determine the optimal parameters of the cut height and the cut line deviation angle for the cutting roof of the retaining gateway, an in-depth analysis with theoretical mechanics and mine rock mechanics of the model was performed, and the relationship between the roof balance control force and the cut height and cut line deviation angle was solved. It was found that the selection of the values of the cut height and the cut line deviation angle had to conform to a certain principle that it should not only utilize the support force provided by the coal wall and the contact surface of the two key blocks but also prevent the failure of the coal wall and the contact surface.

Studies on the Varietal resistance to the rice stripe virus disease (줄무늬잎마름병(호엽고병)에 대한 벼품종의 저항성에 관한 연구)

  • Lee S. H.;Kim C. H.
    • Korean journal of applied entomology
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    • v.5_6
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    • pp.47-54
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    • 1968
  • In order to develop an effective control measure for the rice stripe disease, methods of testing for resistance and selection of resistant varieties among the leading varieties were investigated. For use as a parent in breeding for resistant variety to the disease, total of 410 rice varieties were tested. 1. Disease occurrence was higher at group inoculation than that of individual inoculation in comparing the inoculation methods. 2. In both methods, Lacrose responded susceptible; Zenith and St. No. 1 resistant, and the rest moderate. 3. Suseptible symptom type A was prevalant among the susceptible varieties, while resistant symptom type C was abundant among the resistant varieties, There was no difference between the inoculation methods. 4. 410 rice varieties tested could he divided into 3 groups as susceptible (21 varieties), moderate (377 varieties) and resistant (12 varieties). Resistant varieties wers St. No. 1 and 2, Shin-2, Gulfrose Bonnet, Arkrose, Sun Bonnet, Zenith, Yeechunchilichal, Norm-24, Opaikjoke, Yangchubatchal and Nonglimana-1, Nams-97,-149, -159, -216. -265, Iri-243, -265, Kanchuk -5, -7, -8, -10, -41, -43, -47, -50, Suwon-56, -77, Norin-22, Cod-4. Lacrose and Chukna were susceptible. 5. There was slight differance in the disease occurrence in regard to maturing period. However late varieties seem to be more resistant than early or medium varieties. The medium varieties seem to be susceptible. Most of the introduced varieties from foreign countries and the upland cultivated varieties were resistant. 6 Among the leading varieties, Shin-2 in Kangwon-Do was resistant, Kosi in Choongchung-Do, was susceptible, aad the others were moderate.

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Improvement of Boar Semen Quality by Sperm Selection Using Magnetic Nano-particles (마그네틱 나노비드를 이용한 돼지 정자 품질의 향상)

  • Chung, KI-Hwa;Son, Jung-Ho
    • Journal of Life Science
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    • v.26 no.8
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    • pp.943-947
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    • 2016
  • The objective of this study was to see if fairly simple magnetic nano-particle treatment enhances boar semen qualities. Boar semen samples were prepared from the swine AI center and samples were divided by 4 different motility groups (1, >90%; 2. 80~90%; 3. 70~80%; 4. <70%) using computer assisted sperm analysis (CASA) evaluation. Boar semen was extended using BTS extender and same number of magnetic nano-particles as total number of spermatozoa in each sample was treated for 20 min and collected for 5 min at room temperature. Sperm qualities such as motility and viability were evaluated by the CASA before and after treatment. Sperm abnormality and degree of agglutination were also evaluated under the microscopic examination before and after treatment. There were significant changes (p<0.05) on sperm motility from all 4 different groups in the average of 7.11% after treatment. The enhancement of sperm motility changes was more clear in the groups of lower sperm motile groups (<70% and 70~80%; 19.12±1.08% and 5.67±0.71%, p<0.05). The sperm motility character in terms of curvilinear velocity (VCL), straight line velocity (VSL), average path velocity (VAP) and linearity (LIN, %) showed also similar pattern but motility enhancement wear more clear in below 70% motile group. Average sperm viability was increased to 4% by magnetic nano-particles (p<0.05). The percentage of sperm abnormality was also reduced significantly (p<0.05) to the range of 3.7~4.5% before after treatment. The degree of sperm agglutination was also reduced in lower motility groups by the magnetic nano-particle purification.

Study of Medical Carein Health Subcenter (보건지소(保健支所) 진료활동(診療活動)에 관(關)한 연구(硏究))

  • Kim, Moon-Shik;Kim, Han-Joong;Kim, Young-Key;Kim, Il-Soon
    • Journal of Preventive Medicine and Public Health
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    • v.9 no.1
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    • pp.109-116
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    • 1976
  • Reorganization of myun health care service is one of the main issues in health care delivery in rural Korea. The fundamenta, concept of the role and function of the myun health subcenter is that it is the basic unit of rural health care service and is to provide comprehensive health care service through the integration of curative and preventive services. The aim of this study is to analyze the patterns of curative activities in the myun health subcenter in terms of the most prevalent types of diseases, necessary diagnostic methods and required equipment, types of treatment, necessary drugs and materials, and finally the cost of curative services. The population on which this study was done was the 1596 patients who visited the two myun health subcenters (Sunwon Myun and Naega Myun) in Kang Wha County, the area of the Yonsei University Community Health Teaching Project, during period from May 1, 1975 to June 10, 1976. For the patient's record in the clinic, problem oriented medical records were used. Decisions regarding the disease classification, the diagnostic methods used and selection of the most appropriate and adequate medical treatment were made by a group of three experienced physicians after reviewing the medical records which had been written by public physicians who were treating patients in the study area. The records were reviewed by resident staff members of the Department of Preventive Medicine, of Yonsei University College of Medicine. A brief summary of results of the study is as follow: 1. 29.9% of the patients who visited the clinics were ages between 0-4. No sex difference was observed among patients less than 20 years of age. However, among patients over 20 years old, females predominated. Thus it is evident that the majority of patients were either children or mothers and grandmothers. 2. The distance from the individual villages to the myun health subcenter was one of important factors in determining the ratio of clinic visits. However, other factors such as the activities of the health workers also affected the rates substantially. 3. The most common 25 diseases comprised 90.2% of all the diseases recorded. Acute respiratory infection (25.5%), Skin (12.7%) , diarrheal diseases (6.8%), neuralgia and back pain (4.9%) and. all other injuries (3.9%) were the five most common diseases. 4. Of all the diseases diagnosed and treated, 9.2% required simple laboratory tests for diagnosis, 6.5% required X-ray examination, and altogether 13.6% required either laboratory test or X-ray examination. 5. Treatment and management of 42.0% of the cases could be accomplished with simple, inexpensive drugs, 12.8% required the use of more expensive drugs (mostly antibiotics) and injections were required in 19.7% of the cases. Minor surgery and referral were necessary in 5% of the cases. 6. The cost for diagnosis and treatment was estimated with a standard which was set by general concensus. The average cost of diagnosis was 144 per case and the cost of treatment was 726 per case, The Total average cost per visit was 870.

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An Instructional Model for the Improvement of Decision Making Skills in the 'Technological Innovation and Invention' Unit of Technology·Home Economics Curriculum (고등학교 기술·가정과 '기술 혁신과 발명' 단원에서 의사결정능력 향상을 위한 수업 모형 개발)

  • Seo, Joung-Wan;Lee, Yong-jin
    • 대한공업교육학회지
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    • v.41 no.1
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    • pp.108-127
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    • 2016
  • We confront incessant choices in life. A person or a group stands at a crossroad continuously and make decisions under limited conditions in each time in order to achieve a goal. These series of processions are referred to as decision making and dominates our actions. Based on this view, the decision making is crucial and it secures its own position in school education as well as in real life. The purpose of this study is to develop decision making skills instructional model that can be applied to improve decision making skills in technological subjects. The components of decision making skills in technological education was problem recognition, problem identification, alternative production, alternative assessment, optimum selection, optimum evaluate. An instructional models for improvement of decision making skills in technology education and examination was designed according to the components of decision making skills in technological education. Depending on the components of decision making skills developed a teaching material to experience each step. And in the teaching material was to verify the improved decision-making skill. Accordingly, a decision making instruction model in technology is expected to contribute to enhance students' decision making skills.

Selection of Quality Indicator to Predict the Shelf-life of Milk (UHT, LTLT) during Distribution (시유(UHT, LTLT)의 유통 중 품질예측을 위한 품질지표 선정)

  • Kim, Ji-Young;Kim, Jong-Hoon;Kim, Byeong-Sam
    • Journal of Dairy Science and Biotechnology
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    • v.29 no.2
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    • pp.37-42
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    • 2011
  • The changes in pH, titratable acidity, chromaticity, total count, coliform group and organoleptic properties of the whole market milks (UHT, LTLT) that sold currently on the domestic market were stored after their production at 0, 10, 20, 30 and $40^{\circ}C$ to predict their quality during distribution, and examined prior to the analysis on the correlation of their quality properties and organoleptic preference level and discovery of optimal quality indicator. The investigation of correlation between pH, acidity and preference level of milks depending on respective storage temperature showed significant correlation (p<0.01) for the milk stored at 10, 20, 30 and $40^{\circ}C$, and the higher temperature was directly proportional to the higher correlation coefficient. The correlation between total count and preference level for LTLT milk stored at 0, 10, 20, 30 and $40^{\circ}C$ showed high correlation coefficient at every high temperature condition respectively as R=0.81, R=0.91, R=0.96, R=0.90 & R=0.99, and the correlation coefficients were also significant level for the UHT milk irrespective of their storage temperature except $0^{\circ}C$. Accordingly, the changes in total colonies turned out to be suitable to be the quality indicator for the quality prediction of the milk on the distribution.

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Assessment of Future Flood According to Climate Change, Rainfall Distribution and CN (기후변화와 강우분포 및 CN에 따른 미래 홍수량 평가)

  • Kwak, Jihye;Kim, Jihye;Jun, Sang Min;Hwang, Soonho;Lee, Sunghack;Lee, Jae Nam;Kang, Moon Seong
    • Journal of The Korean Society of Agricultural Engineers
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    • v.62 no.6
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    • pp.85-95
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    • 2020
  • According to the standard guidelines of design flood (MLTM, 2012; MOE, 2019), the design flood is calculated based on past precipitation. However, due to climate change, the frequency of extreme rainfall events is increasing. Therefore, it is necessary to analyze future floods' volume by using climate change scenarios. Meanwhile, the standard guideline was revised by MOE (Ministry of Environment) recently. MOE proposed modified Huff distribution and new CN (Curve Number) value of forest and paddy. The objective of this study was to analyze the change of flood volume by applying the modified Huff and newly proposed CN to the probabilistic precipitation based on SSP and RCP scenarios. The probabilistic rainfall under climate change was calculated through RCP 4.5/8.5 scenarios and SSP 245/585 scenarios. HEC-HMS (Hydrologic Engineering Center - Hydrologic Modeling System) was simulated for evaluating the flood volume. When RCP 4.5/8.5 scenario was changed to SSP 245/585 scenario, the average flood volume increased by 627 ㎥/s (15%) and 523 ㎥/s (13%), respectively. By the modified Huff distribution, the flood volume increased by 139 ㎥/s (3.76%) on a 200-yr frequency and 171 ㎥/s (4.05%) on a 500-yr frequency. The newly proposed CN made the future flood value increase by 9.5 ㎥/s (0.30%) on a 200-yr frequency and 8.5 ㎥/s (0.25%) on a 500-yr frequency. The selection of climate change scenario was the biggest factor that made the flood volume to transform. Also, the impact of change in Huff was larger than that of CN about 13-16 times.

Review on Soil Erosion and Loss Management System of the Calgary City Government, Albert, Canada (캐나다 앨버트 주 캘거리 시의 토사관리제도에 관한 고찰)

  • Kim, Youngchul;Kim, Lee-Hyung;Hwang, Sung Woo
    • Journal of Wetlands Research
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    • v.17 no.2
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    • pp.163-175
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    • 2015
  • In this paper, soil erosion and soil loss management system (SMS) of the City of Calgary in Albert, Canada was reviewed. Regulatory basis supporting this soil management system, permit process and conditions, guidelines and principles for the SMS, and monitoring and repair duties, inspection were discussed. Permit process in the City of Calgary is handled mainly by Urban Development Division, in which special task force called CPAG (Coorporative Planning Application Group) (if necessary circulated through related subdivisions). Inspects all the permit conditions and decides permit or refusal, and LUM (Land Use and Mobility) advertises the approval, if there is no appeals, permit is released to developers. If permit is rejected, applicant can appeals Development Appeal Board, it can approve or reject. In addition to permit, the city has manual for soil management plan, which includes BMP selection, design, monitoring, maintenance, and inspection activities. Perfect SMS policy does not necessarily guarantee relieving the soil-particle related pollution problem, but in Korea, we have to recognize that construction works during development is potentially the most destructive stage of environmental pollution. The central and local governments must make preparations for the effective and tight regulations and ordinance which is appropriate for regional social-economic conditions.

Analysis of Quantitative Trait Loci for Yield Component Traits in Soybean Using Recombinant Inbred Lines (콩에서 수량구성요인과 관련된 양적형질유전자좌의 분석)

  • Kim, Hyeun-Kyeung;Oh, Ki-Won;Choi, In-Soo;Kang, Jum-Soon;Choi, Young-Whan;Lee, Yong-Jae;Park, Young-Hoon;Son, Beung-Gu
    • Journal of Life Science
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    • v.17 no.5 s.85
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    • pp.599-605
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    • 2007
  • Seed and pod numbers are the main yield components in soybean. Selection for increased yield potential is main goal of plant breeding. The objective of this study was to identify quantitative trait loci(QTLs) that control pod number per plant, seed number per plant and pod in soybean. The 117 $F_{2:10}$ recombinant inbred lines(RILs) developed from a cross of 'Keunolkong' and 'Shinpaldalkong' were used. Two independent QTLs for pod number per plant were identified from linkage group(LG) F and L. Two QTLs for seed number per plant were located on LG F and L. Seed number per pod was related with three QTLs located on LG D1a, D1b and F. Pod and seed number per plant have two common QTLs on LG F and L.

Evaluation on the Practicum Using Standardized Patients for Nursing Assessment to Articular Disease (표준화 환자를 이용한 관절질환 간호사정 실습교육의 평가)

  • Yi, Yeo-Jin;Lim, Nan-Young;Lee, Eun-Hee;Han, Hye-Ja;Kim, Joo-Hyun;Son, Haeng-Mi;Park, Young-Sook;Kang, Hyun-Sook;Cho, Kyung-Sook;Kim, Dong-Oak;Kwon, Sung-Bok;Lee, In-Ok
    • Journal of muscle and joint health
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    • v.14 no.2
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    • pp.137-148
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    • 2007
  • Purpose: This study was performed to evaluate of practicum by using standardized patient(SP) for nursing assessment. Method: This study had 2 steps. The 1st-step was pre-intervention stage including selection of a learning title, formation of case scenario, training of SP and developing the evaluation tools for students' clinical competence to assessment, 6 categories 29 items. The 2nd-step consisted of intervention and evaluation stages. 34 nursing students divided 2 groups participated in assessing the SP. Evaluation of each group was performed by 2 nursing professors. All students recorded their feelings after assessing the SP. The SP also evaluated about nursing students' attitude toward the SP. Results: ICC(Interclass correlation coefficient) between 2 groups was over 0.7 all categories. Students' assessing score(range 0-1) was muscular-joint function status(0.41), nutritional status(0.39), history taking(0.38), IADL(0.18), ADL(0.15), and emotional status (0.07). The mean scores of the nursing students' attitude by SP was 4.03(range 1-6). Also most students showed positive reactions to the education using SP because they had the chance to experience what they could not practice in clinical setting. Conclusion: The evaluation tool revealed high reliability. Nursing students' clinical competence was below average. But they took a good attitude to SP. We recommended further research using SP with various disease.

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