• Journal of Korean Tunnelling and Underground Space Association
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• v.19 no.6
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• pp.1013-1028
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• 2017

This paper presents key findings obtained from the numerical experiment investigating into the use of the cylindrical cavity for rock splitting operations. The stress and strain path analyses were carried out in order to provide a better insight into the crack formation. The principal stress analysis carried out along the crack line using the results obtained from these numerical analyses allowed the failure of the brittle material and the crack propagation to be investigated. This paper also suggested possible reasons for the change in crack direction observed during the rock splitting operations using the results obtained.

• 월간 기계설비
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• s.294
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• pp.64-67
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• 2015

전국 시 도회는 지난 해 개최된 총회를 통해 제9대 시 도회장을 새롭게 구성하고 각 지역에서 설비건설업계 및 협회 발전을 위해 활발한 활동을 벌이고 있다. 이에 본지는 전국 시 도회장으로부터 사업계획을 듣는 코너를 연재하고 있다. 이번 호에는 최호선 인천시회 회장으로부터 인천시회의 사업추진 현황과 향후 사업계획을 들었다. 시원시원함과 호탕함으로 사람을 끌어들이는 마력이 있는 최호선 회장은 제8대에 이어 제9대까지 연임 중이다. 1883년 개항으로 근대화의 출발이자 6.25 전쟁 시 인천상륙작전으로 자유와 평화를 지켜낸 보루인 인천시가 아시아 허브로 발돋움할 수 있도록 최호선 회장은 회원사의 경쟁력 제고와 재도약 발판 마련을 위해 적극 노력하고 있다.

• Proceedings of the Optical Society of Korea Conference
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• 2002.07a
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• pp.244-245
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• 2002

1 picosecond 보다 짧은 펄스길이를 갖는 초단파길이 레이저 펄스 (Ultrashort laser pulse, USLP)를 이용한 물질의 절제 (ablation)는 여타 nanosecond 영역의 레이저 절제와 많은 차이를 보인다(1). USLP는 순간 파워가 매우 높기 때문에 직접적으로 물질의 원자를 분리시켜 자유전자를 형성한다 이들 자유전자는 일반 선형흡수체 (linear absorbing chromophore)보다 흡수계수가 몇 십 배로 높아 대부분의 펄스 에너지가 표면 100-200 m 이내의 극히 작은 지역에 밀집되게 된다. (중략)

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 2000.06a
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• pp.241-246
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• 2000

최근 들어 집중호우 및 게릴라성 호우 등 이상강우로부터 야기되는 급격한 하천유량의 증가는 교량에서의 세굴에 대한 안정성 여부에 큰 문제를 야기하고 있다. 홍수시에는 유량이 교량의 상관 위로 월류하게 되는 경우가 생기게 되며, 수심의 증가에 따라 상판의 일부분 또는 전체가 물이 잠기게 된다. 이때의 흐름은 압력흐름 상태를 가지게 되어 세굴의 발달을 더욱 크게 만들게 된다. 흥수시 압력흐름에 대한 위험은 일반 흐름에서보다 훨씬 크며 100년 빈도의 홍수사상일 지라도 그 효과는 500년 빈도의 홍수사상보다 더욱 크게 될 것이다. 기존의 세굴에 대한 연구의 대부분은 자유수면을 기초로 하고 있으며 이에 따라 많은 세굴방정식들도 자유수면에 대해서만 이루어지고 있다. (중략)

• Proceedings of the Korean Nuclear Society Conference
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• 1998.05b
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• pp.633-638
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• 1998

벼의 성장시기에 다른 대기중 삼중수소의 식물채내 흡수실험을 수행하였다. 투명한 아크릴로 만들어진 피폭상자(50x60x120cm)내의 피폭조건은 비록 같은양(18.5 MBq)의 HTO를 증발시키더라도 동일한 농도를 유지하는 것이 거의 불가능하였다. 벼꽃의 매화 직후부터 수확기까지 이삭의 생성시기별로 HTO에 피폭시킨 후 잎, 줄기 및 이삭으로 구분된 시료에서 피폭 후 시간별로 조직자유수의 삼중수소 농토를 측정하였다. 조직자유수의 삼중수소 농도는 이삭에서 가장 느리게 감소하였으나 조직결합수의 삼중수소 농도는 이삭 성장이 가장 왕성한 시기에 높게 측정되었다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.185-185
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• 2004

최근 고속 회전기계에 사용되고 있는 공기호일 베어링은 동압형 기체 베어링으로 매우 안정적이고, 보통의 저널 베어링에서 발생할 수 있는 불안정한 진동을 최소화 할 수 있는 장점을 가지고 있다. 또한 높은 안정성 및 축 자체에 자동 조절 기능을 가지고 있어서 극저온 기계 및 고속 회전기계에 널리 사용되고 있다. 이러한 고속 회전기계는 축의 기동 및 정지 시, 위험속도를 안전하게 통과하기 위해 위험속도에서의 진동을 억제하여야 하고, 운전 가능한 회전수를 증가시키기 위해서 로터 시스템의 동적 해석이 필요하다.(중략)

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.3
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• pp.220-228
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• 2008

In this study the aerodynamic characteristics of a canard-controlled missile with freely spinning tailfins were investigated by using a semi-empirical method and a CFD code. The mean aerodynamic coefficients for the rolling and roll damping moments were first calculated and then used to predict the roll-rate of freely spinning tailfins. The calculation of roll-rate in the CFD code was carried out by combining a Chimera overset grid system and 6-DOF analysis module. The predicted roll-rate was in good agreement with the experimental data for the roll and yaw canard control inputs. It was also shown that the results are in good agreement with the prediction by a CFD code. This indicates that the semi-empirical method can be used to predict the roll-rate of a canard-controlled missile with freely spinning tailfins.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.10
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• pp.4855-4864
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• 2013

The purpose of this research is to examine the effects of infants' free play in forests on the development of their sociality. The 24 infants of a kindergarten in Jeju city, who is four years old, participated in the research. Participants freely played in forests for two hours at each time according to their own interests and demands, and this play performed twice every week for total 12 weeks. The results are as followed. Firstly, the free play activities in forests improved the infants' sociality. Secondly, the activities improved every sub-factors of the sociality such as cooperativeness, the acceptance of view, the free will, and the interaction. The results indicate that forests provide rich natural objects for infants to create various and new play by themselves. In addition, the free play activities in forests could build good inter-personal relationship through active interaction among the infants and lead positive impact on the development of their sociality.

• Journal of Korean Library and Information Science Society
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• v.47 no.4
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• pp.93-122
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• 2016

The present study investigates librarians perceptions of Free Learning Semester, and their commitment to program development for coordination with Free Learning Semester, and whether they currently offer programs for Free Learning Semester. The study results are as follows. First, the results on perceptions of Free Learning semester showed that 54.20% of the librarians who participated in the study were aware of Free Learning Semester, and 80.15% had participated in training related to Free Learning Semester. Regarding the anticipated outcomes of implementation of Free Learning Semester, "Participation in various experiential activities offered through Free Learning Semester" was the most common response, and regarding special considerations in Free Learning Semester, "Need for instituting the dedicated workforce and enhancing their sense of responsibility and expertise" was the most common response. Second, regarding the library program development and provision for coordination with Free Learning Semester, 58.02% thought that the implementation of Free Learning Semester was an opportunity to expand the role of libraries, while insufficient budget was listed as a barrier. In addition, 63.36% stated that they had no experience in providing a program in a library. Finally, the results on the perception on the Free Learning Semester program they want to provide in a library showed that "Human Library" and "Read! Think! Dream!" were the programs they want to provide most, with the mean score of 3.939.

• Korean Journal of Childcare and Education
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• v.12 no.1
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• pp.57-81
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• 2016

The purpose of this study was to find out the feature of children's play according to a player number restriction rule in the free choice activities. And it is expected that the result of this study will contribute to improving the management of free choice activities. The participants of this study were a homeroom teacher, professor as a co-researcher and 25 4-year-old children of a private kindergarten. The data were collected by observation, children interview and reflective journal of the teacher from July to October in 2014. The results indicated that the children were stressed out with using name cards for presenting center selection, showed overcompetitive behaviors, and frequently violated the rules. The researchers found that the restriction rule had some dysfunctions, which were interferences of moral development, social-emotional development, self-regulation development, preventing safety-accident and free choice behavior. The researcher as a teacher abandoned the player number restriction rule, and observed the children's play. As a result, children's self-regulation abilities on physical space, play and conflicts improved and the teacher changed her strategy when managing free choice activities. Based on the results, the needs of various restriction rules and appropriate methods for applying the rules in free choice activities were further discussed.