• Journal of The Korean Association For Science Education
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• v.40 no.2
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• pp.191-201
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• 2020

This study investigated verbal and physical interactions which appeared in collaborative science concept learning using augmented reality. Twelve 10th grade students participated in this study. After being organized into three four-member small groups, they participated in classes using smart device-based augmented reality application developed for the understanding of the chemical bonding concept. Their class activities were audio- and video-taped. Semi-structured interviews were also conducted. The results revealed that within individual statement units of verbal interaction, the proportions of information question/explanation and direction question/explanation were found to be high. Within interaction units, the proportions of reformative and cumulative interaction were relatively high. The proportions of progress were also found to be high within both individual statement units and interaction units of verbal interaction. Students' physical interactions were mainly conducted without meaningful verbal interactions. When their physical interactions were accompanied by knowledge construction-related verbal interactions, the proportions of gazing virtual objects and worksheet-related interactions were high. In contrast, various exploratory activities related to the manipulation of markers mainly appeared when they conducted physical interactions only, or when their physical interactions were accompanied by management-related verbal interactions. On the bases of the results, effective methods for collaborative concept learning using augmented reality in science education are discussed.

• Journal of the Korean Society of Marine Environment & Safety
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• v.15 no.1
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• pp.57-62
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• 2009

In order to investigate the hydrodynamic interaction between the tug-barge and bank or ship which is crossing to the opposite direction, the towing simulations of tug-barge transportation were performed. Heading of barge, yaw moment and lateral force of tug boat were obtained by this simulation. The characteristics of results were analyzed and the safety towing method for tug-barge operation was proposed. In order to reduce the slewing motion of barge for safe towing operation, the speed of tug boat should be kept slow ahead state with shortened towing line as length of barge within the limits of the possible.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.05b
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• pp.362-366
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• 2005

종방향 유속의 연직분포 흐름 특성을 파악하기 위해서 중심각이 $180^{\circ}$인 급변곡선수로에서 실험을 수행하였다. 3차원 유속장 측정은 side-looking ADV를 이용하였다. 실험결과, 흐름이 하류 방향으로 진행함에 따라서 최대 종방향 유속이 하상 근처에서 발생하였으며, 이차류에 의한 이송모멘텀의 분포 값이 바뀌는 단면에서 종방향 유속의 연직분포가 대수분포를 만족하지 않음을 파악하였다 직선하천과는 달리 만곡부 내에서 흐름이 하류방향으로 진행함에 따라서 종방향 유속의 연직분포가 변형되는 현상과 관련된 메카니즘은 지형학적 원인에 의한 원심력 작용은 이차류를 발생시키며, 이로 인해 이송 모멘텀이 종방향 유속의 연직분포를 변형시킨다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.1
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• pp.85-92
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• 2015

It is well known that axial tension decreases the shear strength of RC & PSC beams without transverse reinforcement, and axial compression increases the shear resistance. What is perhaps not very well understood is how much the shear resistance capacity is influenced by axial load. RC beams without shear reinforcement subjected to large axial compression and shear may fail in a very brittle manner at the instance of first diagonal cracking. As a result, a conservative approach should be used for such members. According to the ACI Code, the shear strength in web is calculated by effect of axial force and the vertical force in the stirrups calculated by $45^{\circ}$ truss model. This study was performed to examine the effect of axial force in reinforced concrete beams by nonlinear FEM program (ATENA-2D).

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.11
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• pp.7870-7877
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• 2015

In the case of CWR (Continuous welded rail) located on the railway bridge, the CWR has additional axial force due to interaction of bridge and track. Therefore, the CWR tracks located on the bridge have to secure the safety of running train and CWR track through mitigating influence for interaction of bridge and track. The railway design guide in Korea (KR C-08080) provides a certain value for property of longitudinal friction behavior of rail fastening system that is major parameter of interaction behavior by applying European codes. However, in order to apply to domestic railway, it is necessary to review property characteristics of the rail fastening system in actual use. In this paper, the experiment for longitudinal friction behavior of rail fastener applied to concrete track on the railway bridge in Korea was carried out, and statistical characteristic for property of the rail fastener was analyzed from the result of the experiment.

• The Journal of the Petrological Society of Korea
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• v.17 no.2
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• pp.83-94
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• 2008

The Pungcheon-myeon, Andong, consists mainly of Precambrian metamorphic rocks, Jurassic igneous rocks, Cretaceous sedimentary rocks (Hasandong, Jinju and Iljik Formations) and Cretaceous igneous rocks (gabbroic rocks, dykes), in which several major faults are developed; Andong fault of ENE trend, which is the boundary fault of the Cretaceous Gyeongsang Basin and the Precambrian-Jurassic basement (Yeongnam Massif), Namhu fault parallel to it, Maebong fault of NNW direction, bow-shaped Gwangdeok fault of ENE direction which is convex toward SSE direction, and Hahoe fault of NNE direction. This paper is researched the geological structures around these major faults by means of the detailed geometric analysis on beddings, joints, faults and drag folds. As a result, a reverse slip faulting of top-to-the SSE movement accompanied with a regional drag folding is recognized from the arrangement of bedding poles measured around the Gwangdeok and Hahoe faults at its northeastern extension, and a zone of Gwangdeok drag fold of 150-300 m width, which is wider at the central and eastern parts of Gwangdeok fault and narrower at its western part and Hahoe fault, is also defined. It indicates that the Hahoe and Gwangdeok faults are a single fault and their movements are coeval unlike the results of earlier reasearchers. And, In this area are recognized two types of faults [(E)NE${\sim}$EW(fault I), WNW${\sim}$NNW (fault II), trending faults] and four types of joints [EW (I), (N)NW (II), NNE (III), NE (IV) trending joints]. These fractures were formed at least through four different events, named as Dn to Dn+3 phases. (1) Dn phase; the formation of joint (I) (Gwangdeok joint) and the intrusion of acidic dykes of EW trend under the compression of EW direction. (2) Dn+1 phase; the formations of joint (II) (Maebong joint), lens-shaped boudinage of acidic dykes, oblique-slip reverse fault (Fault I-Gwangdeok fault) under the compression of (N)NW direction, and the formation of regional zone of Gwangdeok drag fold accompanying the Gwangdeok faulting. (3) Dn+2 phase; those of joint (III), Fault II (Maebong fault) by dextral strike-slip movement of Maebong joint under the compression of NNE direction, and the extension cutting of Dn+1 structures due to the Maebong faulting. (4) Dn+3 phase; the jointing (IV) and the reactivation of Fault II as oblique-slip type with predominant dextral motion which took place under the compression of NE direction. It also suggests that the Maebong fault is not a tear fault deveolped during thrust tectonics of the Andong and Gwangdeok faults but is a post-fault during different tectonic event.

• Railway Journal
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• v.19 no.1
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• pp.98-109
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• 2016

• Journal of the Earthquake Engineering Society of Korea
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• v.2 no.4
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• pp.11-22
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• 1998

An axisymmetric shell element which includes the effects of the meridional and circumferential cable prestresses is developed. It is coded for personal computer by the maximum use of axisymmetic properties and the dynamic analysis is performed under the seismic exitations. A ring element is used to fully utilize the characteristics of the axisymmetric shell. The eigenvalue solutions using 20 elements under the initial prestresses are in good agreement with the exact solutions. The results of the seismic analysis show that the radial deflection under the meridional prestress is a little larger than that under the circumferential prestress. The finite element model developed in this study can be very useful to the design applications.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.45-48
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• 2008

Under earthquake loads, the columns on the lower stories carry large axial forces and horizontal forces as the earthquake loads are acting horizontally and vertically on the building. To distribute the energy entered into the building under earthquakes according to the plastic deformation of the members, it is safer and more economic to persuade plastic hinge to occur in the beams rather than on the columns. However, it is unavoidable to have plastic hinge occurring on the columns when it is applied on both of the main axes of the building, which results in high shear force on the column end, and reinforced concrete column may result in sudden brittle failure due to bending moment and shear force. To increase restriction of the reinforced concrete column on the horizontal forces, this study uses repetitive loading experiments with different amount of shear reinforcement, and analyzes and compares the structural safety and behaviour of the reinforced test materials.

• Journal of the Earthquake Engineering Society of Korea
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• v.3 no.4
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• pp.71-82
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• 1999

An axisymmetric shell element which includes the effects of the meridional and circumferential cable prestresses is developed. The fluid-structure interaction is expressed as added mass effect which is in proportion to the acceleration of the structure in interface surface. The added mass is obtained by using finite element method under the assumption that the fluid is invicid, incompressible and irrotational. It is coded for personal computer by the maximum use of axisymmetic properties and the dynamic analysis are performed under seismic exitations. A ring element makes the characteristics of the axisymmetric shell to be fully utilized. The elgenvalue solutons under the initial prestresses and the internal fluid are well agreed with the exact solutions and references by using under 20 elements. The eigenvalues are decreased along the increasing the height of internal fluid and these effects are dominant under the lower wave numbers. The results of the seismic analysis show that the radial deflection under the meridional prestress is a little larger than that under the circumferential prestress.