• 한국전산구조공학회논문집
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• 제24권6호
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• pp.637-643
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• 2011

본 논문에서는 결합 기반 페리다이나믹스 해석법을 사용하여 동적취성 파괴시뮬레이션을 수행하였다. 페리다이나믹스 모델은 분기 균열, 균열 불안정성, 균열 경로의 비대칭성, 연쇄 분기 균열, 2차 균열 전파 등 다양한 동적취성 파괴현상을 잘 해석해 낼 수 있다. 본 논문에서는 분기 균열의 분기 각도와 균열 전파속도에 대한 응력파의 영향에 대해 연구하였다. 극한 시점에 도달한 균열은 둘 이상으로 분기되어 전파되고 그 전파속도는 기존 균열의 전파속도와 크게 달라지지 않는다는 사실이 여러 실험을 통해서 입증이 되었다. 페리다이나믹스로 해석된 분기 균열은 실험을 통해 제안된 균열 전파현상들과 잘 부합되는 것을 확인할 수 있었다.

• BMB Reports
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• 제40권3호
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• pp.302-314
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• 2007

N type calcium channels (CaV2.2) play a key role in the gating of transmitter release at presynaptic nerve terminals. These channels are generally regarded as parts of a multimolecular complex that can modulate their open probability and ensure their location near the vesicle docking and fusion sites. However, the proteins that comprise this component remain poorly characterized. We have carried out the first open screen of presynaptic CaV2.2 complex members by an antibody-mediated capture of the channel from purified rat brain synaptosome lysate followed by mass spectroscopy. 589 unique peptides resulted in a high confidence match of 104 total proteins and 40 synaptosome proteome proteins. This screen identified several known CaV2.2 interacting proteins including syntaxin 1, VAMP, protein phosphatase 2A, $G_{o\alpha}$, G$\beta$ and spectrin and also a number of novel proteins, including clathrin, adaptin, dynamin, dynein, NSF and actin. The unexpected proteins were classified within a number of functional classes that include exocytosis, endocytosis, cytoplasmic matrix, modulators, chaperones, and cell-signaling molecules and this list was contrasted to previous reports that catalogue the synaptosome proteome. The failure to detect any postsynaptic density proteins suggests that the channel itself does not exhibit stable trans-synaptic attachments. Our results suggest that the channel is anchored to a cytoplasmic matrix related to the previously described particle web.

• 한국과학교육학회지
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• 제25권1호
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• pp.41-56
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• 2005

Assessing students' knowledge can be a challenging endeavor, as researchers attempt to capture the full complexity and potential development of children's ideas. In this study, the Dynamic Science Assessment (DSA) method (Magnusson, Templin, and Boyle, 1997) was employed to investigate 9-12 year old students' understandings of light, while engaging in multiple tasks with a flashlight with various reflectors and mirrors. The results showed that DSA was effective in providing an opportunity to establish a Zone of Proximal Development, in addition to diagnosing a student's prior understanding. Throughout the interview, a student showed a conceptual model of light as being a solid single entity whose shape can be determined by the shape of the casing of a flashlight. However, as DSA provided phenomena that could not be explained by his unitary model, the student began to re-examine his original conceptual model, and attempted to revise it. This study addressed how Dynamic Science Assessment can help us better understand, not only students' current state of understanding, but also a potential development of understanding in their ZPD. In that sense, this study argues that we should pay more attention to the instructive role of classroom assessment that can promote and support further development of students' deeper understandings.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2009년 추계학술발표대회
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• pp.239-242
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• 2009

Friction stir spot welding (FSSW), developed based on principle of friction stir welding, has been paid attention as a new solid-state spot welding process. Since FSSW can produce high-quality weld in Al alloys more easily than resistance spot welding, this process has been already used for construction of Al components in the automotive industries. Despite the large industrial interests in FSSW, fundamental knowledge on welding phenomena of this process has not been fully understood. In this study, FSSW phenomena, such as the consolidation mechanism, the microstructural evolution and the material flow, were examined in Al alloy 6061. This study clarified that the elliptical zone found in the vicinity of the pin hole on the cross section was characterized by the initially lapped surface of two sheets. Moreover, the following material flow was proposed; capture of the upper material with the threads on the pin surface, spiral flow along the tool rotation, and then release at the tip of the pin.

• 대한전기학회논문지:전력기술부문A
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• 제48권8호
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• pp.924-931
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• 1999

Most conventional protection relays are based on processing information in the spectrum that is close to or at power frequency. It is, however, widely known that faults on transmission lines produce frequency components of a wide range. High frequency signals caused by sudden changes in system voltage that occurs in the immediate post-fault period are generally outside the bandwidth of receptibility of most protection scheme. In this respect, a specially designed stack tuner is connected to the coupling capacitor of CVT, in order to capture the high frequency signals. Digital signal processing is then applied to the captured information to determine whether the fault is inside or outside the protected zone, and to discriminate the fault type. In this paper, modal transform is not applied to fault generated signals, because signals which are converted by modal transform are not have an information of each phase any longer. Instead, using peak voltage value of data windows is able to discriminate fault type. The paper concludes by presenting fault detection and discrimination of various faults on transmission line which are based on extensive simulation studies carried out on a typical 154kV Korean transmission line, using the EMTP software.

• 한국항만경제학회지
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• 제18권2호
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• pp.109-133
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• 2002

The China entered World Trade Oganization(WTO) last year, thus opening its border to more - and freer - trade. With its foreign trade rapidly expanding and with economic growth continuing at a substantial -rate, China will be the largest container traffic generating country in the world. In the light of this potential trade bonanza, regional ports in North-East Asia strive to gain a competitive-edge. The Port of Busan, the world's third largest container port, wants to capture a significant share of the china's container cargoes. In this circumstance, development strategies of the Port of Busan are suggested as follows. First, to cope with increasing volumes, the New Busan Port on Gaduk island should be constructed without failure. Second, it is necessary to add modernized high-performance gantry cranes and to train crane operators' skill. Third, it needs to apply Dwell Time- Sliding Scale System for transshipment cargoes. Fourth, it needs to develop the EDI network in terminal areas or adjacent hub ports to exchange trustworthy and satisfactory informations Fifth, port authority -needs to enlarge designated Free Trade Zone to facilitate the free flow of cargoes. Sixth, the restoration of rail links between North and South Korea is abundantly clear. Thus it needs to enlarge railroad facilities in advance. Seventh, it needs to establish the Port Authority of Busan immediately. Finally, it needs to strengthen port sales and to open events like 'Marine Week 2001' regularly to attract potential canters or big shippers.

• Computers and Concrete
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• 제22권6호
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• pp.539-550
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• 2018

Concrete is highly non-linear material which is originating from the transition zone in the form of micro-cracks, governs material response under various loadings. In this paper, the constitutive models published by many researchers have been used to generate novel stiffness parameters and constitutive curves for concrete. Following such linear material formulations, where the energy is conservative during the curvature, and a nonlinear contribution to the concrete has been made and investigated. In which, nonlinear concrete elastic modulus modeling has been developed that is capable-of representing concrete elasticity for grades ranging from 10 to 140 MPa. Thus, covering the grades range of concrete up to the ultra-high strength concrete, and replacing many concrete models that are valid for narrow ranges of concrete strength grades. This has been followed by the introduction of the nonlinear Hooke's law for the concrete material through the replacement of the Young constant modulus with the nonlinear modulus. In addition, the concept of concrete elasticity index (${\varphi}$) has been proposed and this factor has been introduced to account for the degradation of concrete stiffness in compression under increased loading as well as the multi-stages micro-cracking behavior of concrete under uniaxial compression. Finally, a sub-routine artificial neural network model has been developed to capture the concrete behavior that has been introduced to facilitate the prediction of concrete properties under increased loading.

• Geomechanics and Engineering
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• 제30권2호
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• pp.211-218
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• 2022

This study characterizes Proctor and geophysical properties in a broad range of grading and fines contents. The results show that soil index properties such as uniformity and fines plasticity control the optimum water content and peak dry unit trends, as well as elastic wave velocity. The capillary pressure at a degree of saturation less than S = 20% plays a critical role in determining the shear wave velocity for poorly graded sandy soils. The reduction in electrical resistivity with a higher water content becomes pronounced as the water phase is connected A parallel set of compaction and geophysical properties of sand-kaolinite mixtures reveal that the threshold boundaries computed from soil index properties adequately capture the transitions from sand-controlled to kaolinite-controlled behavior. In the transitional fines fraction zone between F_F ≈ 20 and 40%, either sand or kaolinite or both sand and kaolinite could dominate the geophysical properties and all other properties associated with soil compaction behavior. Overall, the compaction and geophysical data gathered in this study can be used to gain a first-order approximation of the degree of compaction in the field and produce degree of compaction maps as a function of water content and fines fraction.

• 한국물환경학회지
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• 제36권4호
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• pp.284-299
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• 2020

Dam reservoirs play a particularly crucial role in processing the allochthonous and the autochthonous dissolved (DOC) and the particulate (POC) organic carbon and in the budget of global carbon cycle. However, the complex physical and biogeochemical processes make it difficult to capture the temporal and spatial dynamics of the DOC and the POC in reservoirs. The purpose of this study was to simulate the dynamics of the DOC and the POC in Daecheong Reservoir using the 3-D hydrodynamics and water quality model (AEM3D), and to quantify the mass balance through the source and sink fluxes analysis. The AEM3D model was calibrated using field data collected in 2017 and showed reasonable performance in the water temperature and the water quality simulations. The results showed that the allochthonous and autochthonous proportions of the annual total organic carbon (TOC) loads in the reservoir were 55.5% and 44.5%, respectively. In season, the allochthonous loading was the highest (72.7%) in summer, while in autumn, the autochthonous loading was the majority (77.1%) because of the basal metabolism of the phytoplankton. The amount of the DOC discharged to downstream of the dam was similar to the allochthonous load into the reservoir. However, the POC was removed by approximately 96.6% in the reservoir mainly by the sedimentation. The POC sedimentation flux was 36.21 g-C/㎡/yr. In terms of space, the contribution rate of the autochthonous organic carbon loading was high in order of the riverine zone, the transitional zone, and the lacustrine zone. The results of the study provide important information on the TOC management in the watersheds with extensive stagnant water, such as dam reservoirs and weir pools.

• 한국광물학회지
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• 제20권2호
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• pp.103-114
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• 2007

제주도 동부 신산리해안과 산굼부리에 분포하는 현무암에는 최대 직경 15 cm의 개브로노라이트 성분의 포획암과 거정의 사장석 결정이 포획되어 있다. 이 포획암은 포이킬리틱과 등립질 조직으로 산출되며, 관찰된 모든 포획암에는 사장석의 함량이 가장 우세하며(42-94 vol%), 감람석은 산출되지 않는다. 포이킬리틱조직의 포획암은 사장석을 주정(主晶, oikocryst)으로 자형의 사방휘석과 단사휘석을 포함하고 있는 큐물레이트의 특성을 잘 나타내고 있으며 등립질조직의 포획암은 반자형에서 타형의 사방휘석, 단사휘석, 사장석으로 구성되어 있다. 조직적 특성, 지화학적 특성, 야외 노두에서의 산출상태에 의해 포이킬리틱조직을 보이는 포획암은 모암인 현무암 마그마와의 관계에 있어서 폐쇄계를 이룬 고화대에서, 등립질조직의 포획암은 포이킬리틱한 것에 비해 열린계의 특성을 보이며 마그마 쳄버의 회반죽대에서, 거정질의 사장석은 결정 부유대에 위치하던 암편 혹은 광물편으로 해석된다. 제주도의 반려암질포획암은 제주도를 형성한 마그마 쳄버계의 일부분으로, 분화과정이 제법 진행된 마그마에서 결정화된 암석으로 임시적으로 마그마쳄버를 채웠던 마그마 배치(batch)와 관련된 결정화작용-고립화-포획과정의 암편임을 나타낸다.