• Proceedings of the Korean Geotechical Society Conference
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• 2010.09b
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• pp.96-103
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• 2010

This paper presents of effect of tunneling on pile group of being operated bridge using Three-dimensional numerical modeling to study the effect of coordination of tunneling location under discontinuous group pile. In order to find idealistic tunneling location that causes settlement, change of stress on the piles and movement of soil at a minimum, a fully coupled 3D finite element model is adopted. The study contains pile settlement, axial force on each piles in the group, axial displacement of piles and soil behaviour caused by tunneling. Based on the result some insights into the pile behavior due to tunneling obtained from numerical analysis were mentioned and discussed.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2011.04a
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• pp.235-238
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• 2011

본 연구에서는 필요한 수준의 성과품 납품을 위해 교량정보모델의 상세수준을 분류하고 각 상세수준에서 요구되는 세부정보를 분석하였다. 이는 기본적으로 교량 설계 업무가 단계별로 이루어지며 각 단계마다 성과품을 납품하도록 규정 되어있다는 사실을 바탕으로 연구가 이루어졌다. 이를 위하여 본 연구에서는 우선, 국내의 교량 설계준공단계 성과품 납품 항목 중 교량정보모델에 요구되는 항목을 분류하였으며 분류한 요구항목에 맞춰 3D객체와 속성정보수준을 정하여 업무 프로세스 단계별 상세수준을 정의하였다. 또한, 정의한 상세수준을 기준으로 하여 각 상세수준에서 포함하도록 요구되는 세부정보 분석을 수행하였으며, 분석된 세부요구정보는 성과품 납품에 활용가능하다.

• Steel and Composite Structures
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• v.27 no.2
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• pp.217-227
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• 2018

This paper utilizes 3D FEM to provide deeper insights about the structural behaviour of a 6.1 m span steel culvert, which was previously tested under extreme loading. The effect of different input parameters pertaining to the backfill soil has been investigated, where the structural response is compared to field measurements. The interface choice between the steel and soil materials was also studied. The results enabled to realize the major influence of the friction angle on the load effects. Moreover, the analyses showed some differences concerning the estimation of failure load, whereas reasons beyond this outcome were arguably presented and discussed.

• Journal of international Conference on Electrical Machines and Systems
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• v.3 no.1
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• pp.78-82
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• 2014

Power Transformers with more than one secondary winding are not uncommon in industrial applications. But new classes of applications where very large number of independent secondaries are used are becoming popular in controlled converters for medium and high voltage applications. Cascade H-bridge medium voltage drives and Pulse Step Modulation (PSM) based high voltage power supplies are such applications. Regulated high voltage power supplies (Fig. 1) with 35-100 kV, 5-10 MW output range with very fast dynamics (${\mu}S$ order) uses such transformers. Such power supplies are widely used in fusion research. Here series connection of isolated voltage sources with conventional switching semiconductor devices is achieved by large number of separate transformers or by single unit of multi-secondary transformer. Naturally, a transformer having numbers of secondary windings (~40) on single core is the preferred solution due to space and cost considerations. For design and simulation analysis of such a power supply, the model of a multi-secondary transformer poses special problem to any circuit analysis software as many simulation softwares provide transformer models with limited number (3-6) of secondary windings. Multi-Secondary transformer models with 3 different schemes are available. A comparison of test results from a practical Multi-secondary transformer with a simulation model using magnetic component is found to describe the behavior closer to observed test results. Earlier models assumed magnetising inductance in a linear loss less core model although in actual it is saturable core made-up of CRGO steel laminations. This article discusses a more detailed representation of flux coupled magnetic model with saturable core properties to simulate actual transformers very close to its observed parameters in test and actual usage.

• Journal of the korean academy of Pediatric Dentistry
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• v.43 no.1
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• pp.93-108
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• 2016

One of the fields to which the 3D printing technology can be applied is the field of medicine. Recently, the application of 3D printing technology to the bio-medical field has been gradually increasing with the commercializing of the bio-compatible or bio-degradable materials. The technology is currently contributing to the biomedical field by reducing times required for operations or minimizing adverse effects through preoperative identification of post-surgical consequences or model surgery with artificial bones and organs. This technology also enables the production of customized biomedical auxiliary products like hearing aids or artificial legs etc. For the field of dentistry, the 3D printing technology is also expected to elevate the level of dental treatment by making the customized orthodontic models, crown, bridge, inlay, and surgical guides for implant and surgery. However, issues remaining unidentified or incomplete in printing materials, modeling technology, software technology associated with CAD, verification of bio-stability and bio-effectiveness of materials or in compatibility and standardization of the technology are yet to be solved or be clarified for the full-scale application of the 3D printing technology, thus, it seems such issues should be resolved through further studies.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2010.04a
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• pp.375-378
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• 2010

본 논문은 엔지니어링 문서정보를 준구조화된 XML 문서로 변환하고 이를 3차원 교량 모델과 연계하는 방법을 제시한다. 이를 위해 먼저 구조계산서의 세부 목차에 따른 문서구조를 추출하는 기법을 이용하여 3차원 교량모델을 구성하는 각 부재와 매핑되는 구조계산서 문서의 일부를 프로그램 상에서 자동으로 추출하기 위한 모듈을 개발하였다. 또한 3차원 교량모델의 정보를 운영하기 위해 IFC 기반의 교량정보모델을 개발하였다. 개발된 정보모델은 교량요소들의 논리적 구성체계를 공간적 요소, 물리적 요소 및 그룹 요소별로 표현할 수 있도록 지원한다. 이와 같이 개발된 기술을 이용하여 3차원 교량모델 뷰어에서 구조계산서의 정보를 검색하기 위한 시범 툴을 개발하였으며, 4개의 단위 교량으로 구성된 복합형식의 교량에 대한 3차원 모델을 구축하고 각 교량에 대한 구조계산서 또한 XML 문서로 변환하였다. 이와 같이 구축된 두 정보체계에서 사용자가 선택한 임의의 구성요소에 관한 세부 문서정보의 조회가 가능함을 보임으로써 제시된 방법의 적합성을 검증하였다.

• Journal of Korean Society of Steel Construction
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• v.23 no.2
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• pp.199-210
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• 2011

The cables in cable-stayed bridges are under high stress and are very sensitive to vibration due to their small section areas compared with other members. Therefore, it is reasonable to evaluate the cable impact factor by taking into account the dynamic effect due to moving-vehicle motion. In this study, the cable impact factors were evaluated via moving-vehicle-load analysis, considering the design parameters, i.e., vehicle weight, cable model, road surface roughness, vehicle speed, longitudinal distance between vehicles. For this purpose, two steel composite cable-stayed bridges with 230- and 540-m main spans were selected. The results of the analysis were then compared with those of the influence line method that is currently being used in design practice. The road surface roughness was randomly generated based on ISO 8608, and the convergence of impact factors according to the number of generated road surfaces was evaluated to improve the reliability of the results. A9-d.o.f. tractor-trailer vehicle was used, and the vehicle motion was derived from Lagrange's equation. 3D finite element models for the selected cable-stayed bridges were constructed with truss elements having equivalent moduli for the cables, and with beam elements for the girders and the pylons. The direct integration method was used for the analysis of the bridge-vehicle interaction, and the analysis was conducted iteratively until the displacement error rate of the bridge was within the specified tolerance. It was acknowledged that the influence line method, which cannot consider the dynamic effect due to moving-vehicle motion, could underestimate the impact factors of the end-cables at the side spans, unlike moving-vehicle-load analysis.

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.3
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• pp.104-112
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• 2015

Non-contact surface wave transmission (SWT) measurements are used to evaluate the depth of a surface-breaking crack in concrete slabs. The author propose a measurement model that includes an appropriate configuration of the source and receivers, and a transmission function for the given configuration. A series of numerical simulations using a 3D finite element model is used to obtain the transmission function. Then, validity of a proposed model is verified through experimental studies. Two air-coupled sensors are used to measured surface waves across surface-breaking cracks with varying depths from 0mm to 100mm with intervals of 10mm in a concrete slab ($1500{\times}1500{\times}180mm^3$) in laboratory. As a result, the proposed method is demonstrated as to be effective for charactering the depth of a surface-breaking crack in concrete bridge deck with an average error of 10%. A discussion on practical applications of the proposed method is also included in this article.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1998.11a
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• pp.150-151
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• 1998

Drug delivery to the brain is facilitated by the synthesis of chimeric peptides, where in neuropharmaceuticals are linked to a vector such as an antibody to the transferrin receptor that mediates transcytosis through the blood-brain barrier (BBB). When disulfide linkers are used in the chimeric peptide, it is crucial that the S-S bridge is stable during transit and that cleavage does not occur prematurely within endothelial cells, as the peptide drug moiety would then be sequestered by the BBB instead of passing through it. The present study addressed that problem. As a model drug a metabolically stable opioid peptide, [$^3$H]DALDA (Tyr-dArg-Phe-Lys-NH$_2$), was used. It was monobiotinylated with NHS-SS-biotin to yield bio-[$^3$H]DALDA. The biotinylated peptide was bound to the vector OX26-SA which is a covalent conjugate of OX26 and streptavidin (molar ratio = 1: 1). In vitro treatment of the chimeric peptide, bio-[$^3$H]DALDA/OX26-SA, with a reducing agent, dithiothreitol, released the labeled peptide from the vector by conversion of bio-[$^3$H]DALDA to the desbiotinylated derivative, desbio-[$^3$H]DALDA.

• Geomechanics and Engineering
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• v.32 no.1
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• pp.111-123
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• 2023

The slope of an open cut tunnel is located above the exit of the Leijia tunnel on the Changgan high-speed railway. During the excavation of the open cut tunnel foundation pit, the slope slipped twice, a large landslide of 92500 m³ formed. The landslide body and unstable slope body not only caused the foundation pit of the open cut tunnel to be buried and the anchor piles to be damaged but also directly threatened the operational safety of the later high-speed railway. Therefore, to study the stability change in the slope of the open cut tunnel under heavy rain and excavation conditions, a 3D numerical calculation model of the slope is carried out by Midas GTS software, the deformation mechanism is analyzed, anti-sliding measures are proposed, and the effectiveness of the anti-sliding measures is analyzed according to the field monitoring results. The results show that when rainfall occurs, rainwater collects in the open cut tunnel area, resulting in a transient saturation zone on the slope on the right side of the open cut tunnel, which reduces the shear strength of the slope soil; the excavation at the slope toe reduces the anti-sliding capacity of the slope toe. Under the combined action of excavation and rainfall, when the soil above the top of the anchor pile is excavated, two potential sliding surfaces are bounded by the top of the excavation area, and the shear outlet is located at the top of the anchor pile. After the excavation of the open cut tunnel, the potential sliding surface is mainly concentrated at the lower part of the downhill area, and the shear outlet moves down to the bottom of the open cut tunnel. Based on the deformation characteristics and the failure mechanism of the landslides, comprehensive control measures, including interim emergency mitigation measures and long-term mitigation measures, are proposed. The field monitoring results further verify the accuracy of the anti-sliding mechanism analysis and the effectiveness of anti-sliding measures.