• International Journal of Naval Architecture and Ocean Engineering
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• 제11권1호
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• pp.572-583
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• 2019

This paper aims to assess the applicability of the Runge Kutta Discontinuous Galerkin-Direct Ghost Fluid Method to the internal explosion inside a water-filled tube, which previously was studied by many researchers in separate works. Once the explosive charge located at the inner center of the water-filled tube explodes, the tube wall is subjected to an extremely high intensity fluid loading and deformed. The deformation causes a modification of the field of fluid flow in the region near the water-structure interface so that has substantial influence on the response of the structure. To connect the structure and the fluid, valid data exchanges along the interface are essential. Classical fluid structure interaction simulations usually employ a matched meshing scheme which discretizes the fluid and structure domains using a single mesh density. The computational cost of fluid structure interaction simulations is usually governed by the structure because the size of time step may be determined by the density of structure mesh. The finer mesh density, the better solution, but more expensive computational cost. To reduce such computational cost, a non-matched meshing scheme which allows for different mesh densities is employed. The coupled numerical approach of this paper has fewer difficulties in the implementation and computation, compared to gas dynamics based approach which requires complicated analytical manipulations. It can also be applied to wider compressible, inviscid fluid flow analyses often found in underwater explosion events.

• Structural Engineering and Mechanics
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• 제77권6호
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• pp.721-734
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• 2021

The seismic analysis of structures without applying the effects of soil can undermine functional objectives of structure so that it can affect all the desired purposes at the design and control stages of the structure. In this research, employing OpenSees and MATLAB software simultaneously and developing a definite three-dimensional finite element model of a high-rise concrete structure, designed using performance-based plastic design approach, the performance of Tuned Mass Damper (TMD) and Active Mass Damper (AMD) is both examined and compared. Moreover some less noted aspects such as nonlinear interaction of soil and structure, uplift, nonlinear behavior of structure and structural torsion have received more attention. For this purpose, the analysis of time history on the structural model has been performed under 22 far-field accelerogram records. Examining a full range of all structural seismic responses, including lateral displacement, acceleration, inter-story drift, lost plastic energy, number of plastic hinges, story shear force and uplift. The results indicate that TMD performs better than AMD except for lateral displacement and inter-story drift to control other structural responses. Because on the one hand, nonlinear structural parameters and soil-structure interaction have been added and on the other hand, the restriction on the control force applied that leads up to saturation phenomenon in the active control system affect the performance of AMD. Moreover, the control force applied by structural control system has created undesirable acceleration and shear force in the structure.

• Molecules and Cells
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• 제45권7호
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• pp.495-501
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• 2022

Leucine dehydrogenase (LDH, EC 1.4.1.9) catalyzes the reversible deamination of branched-chain L-amino acids to their corresponding keto acids using NAD⁺ as a cofactor. LDH generally adopts an octameric structure with D4 symmetry, generating a molecular mass of approximately 400 kDa. Here, the crystal structure of the LDH from Pseudomonas aeruginosa (Pa-LDH) was determined at 2.5 Å resolution. Interestingly, the crystal structure shows that the enzyme exists as a dimer with C2 symmetry in a crystal lattice. The dimeric structure was also observed in solution using multiangle light scattering coupled with size-exclusion chromatography. The enzyme assay revealed that the specific activity was maximal at 60℃ and pH 8.5. The kinetic parameters for three different amino acid and the cofactor (NAD⁺) were determined. The crystal structure represents that the subunit has more compact structure than homologs' structure. In addition, the crystal structure along with sequence alignments indicates a set of non-conserved arginine residues which are important in stability. Subsequent mutation analysis for those residues revealed that the enzyme activity reduced to one third of the wild type. These results provide structural and biochemical insights for its future studies on its application for industrial purposes.

• 한국산업융합학회 논문집
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• 제26권1호
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• pp.69-78
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• 2023

For this purpose, the research is to study the architectural characteristic of SooMaJaiJeon which is one of the DongHwaSa in the traditional wooden architecture by dividing it into three section-bracket, roof structure and frame structure. This study is largely divided into four stage-section do subject, research and actual measurement and conclusion. The whole process was consistently executed through detailed steps. The com position of this study is as follows. The 1^st chapter-the purpose, background, method, object and range of the research. The 2^nd chapter-the history of SooMajaiJeon. the 3^rd chapter-the structure of Dapo-style bracket has generally considered, the frame structure of Dapo-style, vertical and horizontal member and podium, the characteristic of bracket with member and the structure, design of bracket, roof structure. In the 4^th chapter, the conclusion of this study has been summarized, Dapo-style is the building that has deep symbolism and structural characteristic of traditional wooden architecture. The frame structure has a dominant regional characteristic and a typical part of typological classification in SooMaJaiJeon.

• 한국항만학회지
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• 제6권1호
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• pp.69-91
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• 1992

A new type of horizontal submerged break water or fixed structure to control waves near coastal area is introduced to focus wave energy before or behind it. Intentionally, the water depth near the structure is changed gradually to get a refraction and diffraction effect. The concentration of wave energy due to the structure was analyzed for the selected design of structure. The shape of the submerged structure in consideration is a circular combined with elliptical curve not to cause reflection of waves at the extreme edge of the structure but cause wave scattering. The direction of the structure against the incident wave is changed easily in the model Applying a regular wave train the following were examined. 1) whether a crescent plain submerged structure designed by the wave refraction theory can concentrate wave energy at a focal zone behind and before it without wave breaking phenomenon. 2) Location of maximum wave amplification factor in terms of the incident wave direction, wave period, etc. In any event the study would contribute to control waves near coastal area and to protect a beach from erosion without interruption of ocean view it is an useful study for the concentration of wave energy efficiently with the increase of wave height.

• Smart Structures and Systems
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• 제31권5호
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• pp.531-543
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• 2023

Base isolation is one of the most widely implemented and well-known technique to reduce structural vibration and damages during an earthquake. However, while the base-isolated structure reduces storey drift significantly, it also increases the base drifts causing many practical problems. This study proposes the use of Shape Memory Alloys (SMA) wires for the reduction in base drift while controlling the overall structure vibrations. A multi-degree-of-freedom (MDOF) structure along with base isolators and Shape-Memory-Alloys (SMA) wires in diagonal is tested experimentally and analytically. The isolation bearing considered in this study consists of laminates of steel and silicon rubber. The performance of the proposed structure is evaluated and studied under different loadings including harmonic loading and seismic excitation. To assess the seismic performance of the proposed structure, shake table tests are conducted on base-isolated MDOF frame structure incorporating SMA wires, which is subjected to incremental harmonic and historic seismic loadings. Root mean square acceleration, displacement and drift are analyzed and discussed in detail for each story. To better understand the structure response, the percentage reduction of displacement is also determined for each story. The result shows that the reduction in the response of the proposed structure is much better than conventional base-isolated structure.

• Nuclear Engineering and Technology
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• 제56권10호
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• pp.4042-4049
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• 2024

A new automatic group structure optimization method based on the perturbation theory was proposed for the few-group structure in two-step nuclear design procedure for VHTR. It applies the sensitivity coefficient of the perturbation theory which includes not only the effect of the cross section on the multiplication factor but also the adjoint weighted reaction rate. The sensitivity coefficient of the fine group for the multiplication factor was calculated and the group boundary for a few-group can be determined so that the summation of the fine group sensitivity for a few-group should be evenly distributed over every few-group. This method was successfully implemented in the ABGO code. VHTR-350 and MiHTR 2D core were used to investigate the performance and applicability of the proposed method. The code generated the new group structures for two cores and the error of the multiplication and reaction rate by the new group structure was compared with the result by the fine group structure. The comparisons indicate that the new group structure by the proposed method can provide the multiplication factor and reaction rates comparable to the existing group structure and more accurate results than the group structure obtained using the Contributon theory.

• 한국강구조학회 논문집
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• 제25권4호
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• pp.399-407
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• 2013

장경간의 대공간구조물은 지진하중에 의하여 일반구조물과는 다른 응답특성이 나타나고 있으므로 대공간구조물에 대한 내진설계를 위해서는 대공간구조물의 동적특성 및 지진응답특성에 대한 정확한 분석이 필요하다. 본 논문에서는 예제 구조물로 대공간구조물의 동적특성을 기본적으로 내재하고 있는 장견간의 아치구조물로 선정하여 다중지점 지진하중이 가진되는 대공간구조물의 진동응답 특성을 분석하였다. 다중지점 지진하중은 대공간구조물의 지점 지반조건이 다른 경우 그리고 시간지연을 갖는 지진하중이 가진되는 경우로 하여 수치해석을 수행하였다. 다중지점 지진하중 적용한 경우의 지진응답이 단일 지진하중 적용에 의한 지진응답과 비교하여 경우에 따라서 상이한 지진응답을 나타내고 있다. 따라서 대공간구조물의 경우에 정확한 지진응답 분석 및 적절한 내진설계를 위해서는 다중지점 지진하중을 적용하여 지진응답을 분석하는 것 바람직하다.

• 한국안전학회지
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• 제28권6호
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• pp.49-56
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• 2013

The statistics of recent accidents in warehouses show that a heavy toll of lives were produced by various accidents, e.g. collision, overturn, fall, slip, exposure to harmful substances or environments, etc. Of significant concern amongst them is the collision, especially the collision between forklift and storage rack structure. Accordingly, this study focuses on behavioral characteristics of rack structure subjected to dynamic impact loading of a forklift. For this purpose, time-domain response analysis has been performed on a standard 2-bay six-story rack structure consisting of columns, beams and bracing members with perforated open section. In order to investigate the most critical scenario, the impact loads are applied in both down-aisle and cross-aisle directions, and the impact locations are also varied along the shelves of the palettes. In order to deal with storage distributions, three types of rack structures are further taken into account: original empty rack structure with no storage, half-loaded rack structure and fully-loaded rack structure. The numerical simulation results demonstrate that the dynamic characteristics of the rack structure are significantly dependent on the distribution of the storage goods and its natural period varies from 0.24sec to 1.06sec, approximately 4.4 times. Further, the parametric studies show that the forklift impact is most critical to the safety of the rack structure when it collides either at the base or at the top of the rack structure.

• 전자공학회논문지
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• 제51권1호
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• pp.179-184
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• 2014

교류형 플라즈마 디스플레이에서의 Vt 폐곡선 측정에 기초하여 개방형 유전체 구조에서 방전 전압과 내부 벽전압 등의 방전 특성이 종래의 구조와 비교되어 조사되었다. 일반적인 교류형 플라즈마 디스플레이의 구조에서 상판은 유리, 전극, 유전체 등으로 이루어져 있는데, 개방형 유전체 구조는 상판 전극사이에 있는 유전체를 제거하여 상판에 있는 유지 전극간의 방전이 더욱 쉽게 발생하도록 하는 구조이다. 개방형 유전체 구조는 종래의 구조와 다르기 때문에 종래의 구동파형으로 구동시에 여러 가지 문제가 발생한다. 특히 상판의 두 전극인 주사와 유지전극 간 방전 개시전압이 달라지기 때문에 종래의 기입 파형을 포함한 초기화 파형도 수정되어야 한다. 본 연구에서는 종래와 개방형 유전체 구조에서 3 전극의 방전개시전압을 비교하기 위하여 Vt 폐곡선을 측정하였고 분석에 기초하여 개방형 유전체 구조에 적합하도록 구동파형이 수정되었다.