• The Bulletin of The Korean Astronomical Society
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• v.46 no.2
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• pp.73.1-73.1
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• 2021

한국 젊은 천문학자 모임(Korea Young Astronomers Meeting, KYAM)은 국내 젊은 천문학자들의 학술 교류 및 친목을 도모하는 단체로, 대면 중심의 활동이 큰 비중을 차지하고 있었습니다. 그러나, 코로나 사태가 장기화되면서 비대면 활동의 중요성이 매우 커졌습니다. 따라서, 2021년도 KYAM 운영진은 다양한 비대면 활동을 준비하여 KYAM의 본 목적을 성취하고자 노력하였습니다. 그 일환으로 젊은 천문학자들간의 연구 교류 활성화를 위해 매달 '얌마당'이라는 독자적인 대학원생 콜로퀴움을 진행하고 있습니다. 그뿐만 아니라 KYAM 회원들간의 오픈 카카오톡방을 개설하여 시간과 공간의 제약을 뛰어넘어 친목을 다지고 연구 교류를 할 수 있는 장을 마련하였습니다. 이외에도 비대면 모임을 개최하고 KYAM 설립 30주년 기념으로 로고 공모전을 여는 등 코로나 시대에 발맞춘 KYAM의 활동을 본 포스터를 통해 소개하고자 합니다.

• Journal of the Korean Geophysical Society
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• v.5 no.2
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• pp.111-129
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• 2002

Generally, investigation methods of cut slope are conucted only geological surface survey to gain engineering geological data of cut slopes. These methods have many problems such as limitations of investigation for a special area. So geophysical investigations such as geotomography, seismic and electrical resistivity methods have been used to search for failure surface in potential failure slopes or failed slopes. But investigation method using the borehole camera is recently a used method and it is thought that this method is more reliable method than other investigation methods because of being able to see by the eyes. Therefore, this paper was conducted investigations of borings and BIPS(Borehole Image Processing System) to search for potential sliding surfaces and was applied to obtain information of discontinuity on failed and potential failure slope in highway. As the results of BIPS, we could decide potential sliding surface in the slope, conducted to check slope stability and decided slope stability measures.

• The Optical Journal
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• s.99
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• pp.39-41
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• 2005

한남대학교 광전자물리학과의 광학설계연구실은 산업적 응용성이 강한 첨단 응용 광학 연구에 매진함은 물론 높은 취업률이 입증하듯 인재양성의 전략적 거점으로 발돋움하고 있다. 최근 산업계에서 개발이 활발한 초소형 카메라 렌즈모듈을 비롯하여, 내시경용 비구면 렌즈, 각종 조명 광학계, 대구경 비구면 측정용 널(Null) 렌즈 설계 및 제작, 비구면 평가 등 다양한 분야의 연구활동을 벌이고 있는 가운데, 단순 기초교육 및 학문적인 연구에만 머무는 것이 아니라 산업계 및 연구소와 함께 다양한 연구개발 실적 및 논문을 발표하며 활발한 활동으로 주목을 받고 있다.

• Journal of Industrial Convergence
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• v.20 no.7
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• pp.79-88
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• 2022

This study is a one group pretest-posttest design study to confirm the effect of non-face-to-face Havruta's activities on communication competency, academic self-efficacy, and learning immersion of nursing students. The study was conducted from September to October 2021. The collected data were through self-report questionnaires of 69 student nurses. The data were analyzed by frequencies and paired t-test using SPSS 24.0 program. As a result, the subjects' communication competency, academic self-efficacy, and learning immersion were significantly increased after the non-face-to-face Havruta's activities compared to before. The results of this study can be useful basic data for professors who want to apply non-face-to-face Havruta's activities to their classes in the future.

• Journal of the Korean Geotechnical Society
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• v.32 no.10
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• pp.31-40
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• 2016

In order to investigate the change in soil arch structure developed within the soil subjected to trapdoor movement, various responses in the deformed particle assembly were observed via photoelastic measurement technique. The particle assembly was composed of the regularly stacked model particles coated by thin photoelastic material. Variation of the internal structure transmitting contact forces were observed by taking images showing the photoelastic responses and compared with the change in slip lines and pressures measured by load cells placed beneath the assembly. Initial soil arch structure established immediately after the trapdoor movement collapsed progressively and meanwhile a new extended structure was developed against further movement of the trapdoor. For the sufficient movement of the trapdoor, initially identical regions bounded by the soil arch structure and slip lines were separated and the region enclosed by slip lines became a part of the region loosing the transmitting contact forces identified by photoelastic measurement.

• Journal of the Korean Geotechnical Society
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• v.35 no.4
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• pp.15-26
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• 2019

The stability of the gravity quay wall against earthquakes is evaluated on the basis of the allowable displacement of the wall. To estimate the displacement caused by external forces, empirical equations based on the Newmark sliding block method or numerical analysis are widely used. In numerical analysis, it is possible to analyze precisely a complicated site and structure, but difficult to set the appropriate parameters and environments; there are limitations in obtaining reliable results, depending on one's level of expertise. The Newmark method, with only seismic motions, is widely used because it is simpler than numerical simulations when estimating permanent displacement. However, the empirical equations do not have any parameters for the response characteristics and sliding block of the structure, and sliding blocks being assumed as rigid bodies does not consider the nonlinear behavior of the soil and interaction with the structure. Therefore, in order to evaluate the seismic stability of the gravity quay wall, a newly-developed empirical equation is needed to overcome the above-mentioned limitations. In this study, numerical simulations are performed to analyze the response characteristics of the backfill of the structure, and to propose an optimal method of calculating the active area. For this purpose, finite element analyses were performed to analyze the response characteristics, and stress-strain relationships for various seismic motions. As a result, the response characteristics, sliding block, and failure surface of the backfill vary depending on the input seismic motions.

• Journal of the Korean Geotechnical Society
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• v.31 no.4
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• pp.57-66
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• 2015

Empirical seismic displacement equations based on the Newmark sliding block method are widely used to develop seismic landslide hazard map. Most proposed equations have been developed for embankments and landfills, and do not consider the dynamic response of sliding block. Therefore, they cannot be applied to Korean mountain slopes composed of thin, uniform soil-layer underlain by an inclined bedrock parallel to the slope. In this paper, a series of two-dimensional dynamic nonlinear finite difference analyses were performed to estimate the permanent seismic slope displacement. The seismic displacement of mountain slopes was calculated using the Newmark method and the equivalent acceleration time history. The calculated seismic displacements of the mountain slopes were compared to a widely used empirical displacement model. We show that the displacement prediction is significantly enhanced if the slope is modeled as a flexible sliding mass and the amplification characteristics are accounted for. Regression equation, which uses PGA, PGV, Arias intensity of the ground motion and the fundamental period of soil layer, is shown to provide a reliable estimate of the sliding displacement. Furthermore, the empirical equation is shown to reliably predict the hazard category.

• Communications of Mathematical Education
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• v.12
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• pp.1-19
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• 2001

유치원과 초등학교 1학년 아동은 그들의 발달특성과 학습의 효율성 측면을 고려할 때, 일상생활 경험과 놀이 활동 등을 이용한 활동중심 교육방법으로 상호 연계성있게 수학을 학습하는 것이 바람직하다. 이러한 필요성에서, 본 연구는 현행 교육과정 상에 제시된 수학교육의 성격과 목표, 내용, 교수방법, 평가 면에서 유치원과 초등학교 1학년 간에 얼마나 연계되어 있는 지를 분석해 보았다. 분석 결과, 유치원과 초등학교 1학년 수학 교육과정 간에는 수학교육의 방향 및 목표, 내용 영역, 교수학습 방법, 평가 면에서 대체로 높은 연계성을 보였다. 그러나 교과 편제나 명칭, 세부적인 내용 구성에서 차이가 있었으므로 이를 해결하기 위한 교육과정 상에서의 연계 실천 방안을 제시해 보았다. 그리고 실제 수학 교육 활동측면에서의 실천 방안으로서 활동중심 교수학습 자료의 개발, 수학 영역 설치를 통한 개별화 교육의 실천, 가정과의 협력 방안 등을 제시해 보았다.

• The Journal of Engineering Geology
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• v.10 no.3
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• pp.205-216
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• 2000

An unstable natural slope located at Icheon-Ri, Dasa-Eup, Dalseong-Kun which has been severely cracked during heavy rain fall in September, 1998, was investigated and analysed for remedial measures. Various geological data were obtained by performing a surface geological survey, a ground penetrating radar(GPR) exploration, four geotechnical borings with field and laboratory tests, and the precipitation records were also reviewed. Based on the these data, the probable sliding plane was determined as a bedding plane with dip angle of 20 to 25 degrees between sandstone and shale layers at depth of 6 to 8 meters. By performing back analyses with the limit equilibrium method, the friction angle and cohesion of the sliding plane were determined as 18$^{\circ}$ and 0, respectively. Based on these results, a series of stability analyses such as stereo-graphic projection method, limiting equilibrium method and numerical method were carried out. The remedial measures for the unstable slope were selected based on the results of the limit equilibrium analyses by considering various conditions expected at the site. Ground grouting or anchoring method with proper surface drainage systems could be employed for the long term safety of the slope.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.3C
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• pp.113-120
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• 2012

An actual slope failure was analyzed in residual soils at Jinju. Due to rainfall infiltration, the safety factor decreases in the unsaturated layers, since the effective stress and shear strength decrease. In this study, the effective stress is based on suction stress using soil water retention curve. Unsaturated properties were evaluated on soil water retention curve, hydraulic conductivity and shear strength with samples from the site. After infiltration analysis of unsaturated flow under the actual rainfall, the distribution of pore water pressure could be calculated in the slope layers. In the stress field of finite elements, an elastic analysis calculated total stress distribution in the layers and also shear stresses on the slip surface using elastic model. On the slip surface, suction stress and effective stress evaluated the shear strength. As a result, the factor of safety was calculated due to rainfall, which could simulate the actual slope failure. In particular, it was found that the suction stress increases and both the effective stress and the shear strength decrease simultaneously on the slip surface.