• 한국건축시공학회지
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• 제20권6호
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• pp.505-514
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• 2020

본 연구는 KBIMS가 적용된 건축 및 구조 부재 형상과 속성 데이터가 포함된 BIM 라이브러리를 구축하는 방법과, 속성 데이터 변환 과정의 문제를 해결하여 KBIMS IFC 파일로 변환하는 방법을 제시한다. 프로젝트에서 다양한 BIM 도구가 활용되어짐에도 불구하고 라이브러리 연구에 특정 도구가 주로 활용되었는데 본 연구에서는 클라우드 기반 데이터베이스 통합플랫폼에 포함된 카티아V6를 활용하여 주요 12개 카테고리, 총 793개의 건축 및 부재 형상 및 수치 라이브러리를 개발했다. KBIMS IFC 속성 입력 과정에서 데이터 타입과 특수문자 속성명으로 인한 데이터베이스 입력 제한을 파악하였다. 입력 가능한 데이터 타입을 찾아 입력하고, 아스키코드를 활용한 특수문자 속성명 대체 입력 방법을 개발했다. 변환기 프로토타입을 개발하여 추출된 IFC 파일을 KBIMS 원래 속성명이 포함된 IFC 파일로 변환하고 시범모델을 활용하여 검증하였다. 본 연구 결과는 실제 프로젝트에서 KBIMS 적용시 BIM 도구의 선택의 폭을 넓히고, 프로젝트 데이터 호환 문제를 줄이는데 도움을 줄 것이다. 마지막으로 KBIMS 라이브러리의 지속적인 활용을 위해서는 관련 조직 간의 유지 관리 방안에 대한 논의가 필요하다.

• 한국항공우주학회지
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• 제31권3호
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• pp.23-30
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• 2003

본 연구는 풍력발전 시스템에 관련된 IEC61400-1 국제규격 및 GL규격에 정의된 다양한 하중조건을 고려하였고, 이러한 하중들을 효과적으로 견딜 수 있는 특별한 복합재 구조형상을 제안하였다. 복합재 풍력터빈 블레이드 주고에 대한 평가를 위해 유한요소 구조해석을 수행하였다. 구조설꼐에서는 파라미터 분석 연구를 통해 블레이드 구조형상을 결정하였고, 대부분의 주요 설꼐 피라미터를 결정하였다. FEM을 이용한 응력해석결과를 검토하여 설계된 블레이드 구조는 어떠한 하중조건에 대해서도 안전함을 확인하였다. 뿐만 아니라, 본 연구에 의해 새롭게 고안된 삽입볼트를 사용한 허브 연결부의의 설계하중과 피로하중에 대한 안전성을 검토하였으며, 잘 알려진 S-N 선형 손상 이론, 하중 스펙트럼 및 Spera의 실험식에 의해 20년 이상의 피로수명을 갖도록 하였다. 몇 개의 집중하중으로 모사된 공력하중에 대한 실물 정적구조시험을 수행하였으며, 실험결과로부터 설계된 블레이드는 구조적으로 안전함을 확인하였다. 더욱이, 변위 및 응력, 중량, 무게중심 증의 측정된 결과는 해석결과와 일치함을 확인하였으며, 연구된 블레이드는 독일의 국제적 인증기관인 GL사의 인증을 획득하였다.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2008년도 정기 학술대회
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• pp.216-221
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• 2008

Shape design optimization for linear elasticity problem is performed using isogeometric analysis method. In many design optimization problems for real engineering models, initial raw data usually comes from CAD modeler. Then designer should convert this CAD data into finite element mesh data because conventional design optimization tools are generally based on finite element analysis. During this conversion there is some numerical error due to a geometry approximation, which causes accuracy problems in not only response analysis but also design sensitivity analysis. As a remedy of this phenomenon, the isogeometric analysis method is one of the promising approaches of shape design optimization. The main idea of isogeometric analysis is that the basis functions used in analysis is exactly same as ones which represent the geometry, and this geometrically exact model can be used shape sensitivity analysis and design optimization as well. In shape design sensitivity point of view, precise shape sensitivity is very essential for gradient-based optimization. In conventional finite element based optimization, higher order information such as normal vector and curvature term is inaccurate or even missing due to the use of linear interpolation functions. On the other hands, B-spline basis functions have sufficient continuity and their derivatives are smooth enough. Therefore normal vector and curvature terms can be exactly evaluated, which eventually yields precise optimal shapes. In this article, isogeometric analysis method is utilized for the shape design optimization. By virtue of B-spline basis function, an exact geometry can be handled without finite element meshes. Moreover, initial CAD data are used throughout the optimization process, including response analysis, shape sensitivity analysis, design parameterization and shape optimization, without subsequent communication with CAD description.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.159-159
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• 2016

Vertically-aligned carbon nanotubes (VCNT) have attracted much attention due to their unique structural, mechanical and electronic properties, and possess many advantages for a wide range of multifunctional applications such as field emission displays, heat dissipation and potential energy conversion devices. Surface modification of the VCNT plays a fundamental role to meet specific demands for the applications and control their surface property. Recent studies have been focused on the improvement of the electron emission property and the structural modification of CNTs to enable the mass fabrication, since the VCNT considered as an ideal candidate for various field emission applications such as lamps and flat panel display devices, X-ray tubes, vacuum gauges, and microwave amplifiers. Here, we investigate the effect of surface morphology of the VCNT by water vapor exposure and coating materials on field emission property. VCNT with various height were prepared by thermal chemical vapor deposition: short-length around $200{\mu}m$, medium-length around $500{\mu}m$, and long-length around 1 mm. The surface morphology is modified by water vapor exposure by adjusting exposure time and temperature with ranges from 2 to 10 min and from 60 to 120oC, respectively. Thin films of SiO2 and W are coated on the structure-modified VCNT to confirm the effect of coated materials on field emission properties. As a result, the surface morphology of VCNT dramatically changes with increasing temperature and exposure time. Especially, the shorter VCNT change their surface morphology most rapidly. The difference of field emission property depending on the coating materials is discussed from the point of work function and field concentration factor based on Fowler-Nordheim tunneling.

• Bulletin of the Korean Chemical Society
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• 제23권2호
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• pp.281-285
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• 2002

The photophysical properties and the singlet oxygen generation efficiencies of meso-tetraphenyl-trithiasapphyrin $(S_3TPS)$ and meso-tetmkis(p-methoxy phenyl)-trithiasapphy rin ((p-MeO)-$S_3TPS$) have been investigated, utilizing steady-state and time-resolved spectroscopic methods to elucidate the possibility of their use as photosensitizers for photodynamic therapy (PDT). The observed photophysical properties were compared with those of other porphyrin-like photosensitizers in geometrical and electronic structural aspects, such as extended ${\pi}$ conjugation, structural distortion, and internal heavy atoms. The steady-state electronic absorption and fluorescence spectra were both red-shifted due to the extended ${\pi}$-conjugation. The fluorescence quantum yields were measured as very small. Even though intersystem crossing rates were expected to increase due to the increment of spin orbital coupling, the triplet quantum yields were measured as less than 0.15. Such characteristics can be ascribed to the more enhanced internal conversion rates compared with the intersystem crossing rates. Furthermore, the triplet state lifetimes were shortened to -1.0 ${\mu}s$ as expected. Therefore, the singlet oxygen quantum yields were estimated to be near zero due to the fast triplet state decay rates and the inefficient energy transfer to the oxygen molecule as well as the low triplet quantum yields. The low efficiencies of energy transfer to the oxygen molecule can be attributed to the lower oxidation potential and/or the energetically low lying triplet state. Such photophysical factors should be carefully evaluated as potential photosensitizers that have extended ${\pi}$-conjugation and heavy core atoms synthesized for red-shifted absorption and high triplet state quantum yields.

• 한국재료학회지
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• 제28권10호
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• pp.539-543
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• 2018

We report the structural, morphological and magnetic properties of the $Ni_{70}Mn_{30}$ alloy prepared by Planetary Ball Mill method. Keeping the milling time constant for 30 h, the effect of different ball milling speeds on the synthesis and magnetic properties of the samples was thoroughly investigated. A remarkable variation in the morphology and average particle size was observed with the increase in milling speed. For the samples ball milled at 200 and 300 rpm, the average particle size and hence magnetization were decreased due to the increased lattice strain, distortion and surface effects which became prominent due to the increase in the thickness of the outer magnetically dead layer. For the samples ball milled at 400, 500 and 600 rpm however, the average particle size and hence magnetization were increased. This increased magnetization was attributed to the reduced surface area to volume ratio that ultimately led to the enhanced ferromagnetic interactions. The maximum saturation magnetization (75 emu/g at 1 T applied field) observed for the sample ball milled at 600 rpm and the low value of coercivity makes this material useful as soft magnetic material.

• BMB Reports
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• 제33권2호
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• pp.120-125
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• 2000

M2PI is an active single chain mini-proinsulin with a 9-residue linker containing the turn-forming sequence 'YPGDV' between the B- and A-chains, but which retains about 50% of native insulin receptor binding activity. The refolding efficiency of M2PI is higher than proinsulin by 20-40% at alkaline pH, and native insulin is generated by the enzymatic conversion of M2PI. The solution structure of M2PI was determined by NMR spectroscopy. The global structure of M2PI is similar to that of native insulin, but the flexible linker between the B- and A-chains perturbed the N-terminal A-chain and C-terminal B-chain. The helix in the N-terminal A-chain is partly perturbed and the ${\beta}$-turn in the B-chain is disrupted in M2PI. However, the linker between the two chains was completely disordered indicating that the designed turn was not formed under the experimental conditions (20% acetic acid). Considering the fact that an insulin analogue, directly cross-linked between the C-terminus of the B-chain and the N-terminus of the A-chain, has negligible binding activity, a flexible linker between the two chains is sufficient to keep binding activity of M2PI, but the perturbed secondary structures are detrimental to receptor binding.

• Journal of Microbiology and Biotechnology
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• 제27권8호
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• pp.1472-1482
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• 2017

Bacterial cytochrome P450 (CYP) steroid hydroxylases are effectively useful in the pharmaceutical industry for introducing hydroxyl groups to a wide range of steroids. We found a putative CYP steroid hydroxylase (BaCYP106A2) from the bacterium Bacillus sp. PAMC 23377 isolated from Kara Sea of the Arctic Ocean, showing 94% sequence similarity with BmCYP106A2 (Bacillus megaterium ATCC 13368). In this study, soluble BaCYP106A2 was overexpressed to evaluate its substrate-binding activity. The substrate affinity ($K_d$ value) to 4-androstenedione was $387{\pm}37{\mu}M$. Moreover, the crystal structure of BaCYP106A2 was determined at $2.7{\AA}$ resolution. Structural analysis suggested that the ${\alpha}8-{\alpha}9$ loop region of BaCYP106A2 is intrinsically mobile and might be important for initial ligand binding. The hydroxyl activity of BaCYP106A2 was identified using in vitro enzyme assays. Its activity was confirmed with two kinds of steroid substrates, 4-androstenedione and nandrolone, using chromatography and mass spectrometry methods. The main products were mono-hydroxylated compounds with high conversion yields. This is the second study on the structure of CYP106A steroid hydroxylases, and should contribute new insight into the interactions of bacterial CYP106A with steroid substrates, providing baseline data for studying the CYP106A steroid hydroxylase from the structural and enzymatic perspectives.

• 한국전산구조공학회논문집
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• 제30권3호
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• pp.231-238
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• 2017

3D 기반의 BIM 도면을 활용을 통해 다양한 건설 시뮬레이션이 가능하다. 이러한 BIM을 기반으로 강력한 몰입환경이 수반되는 가상현실 공간에서 실증실험이 가능한 시뮬레이션 시스템 구축사례가 국내에는 전무한 상황이다. 본 논문에서는 다양한 의사결정 및 가상건설 시뮬레이션이 가능하도록 BIM 도면을 기반으로 3D 기반의 강력한 몰입환경을 제공하는 다면(Multi Screen) 기반의 시뮬레이션 시스템 개발사례를 제시하였다. 구축된 시뮬레이션 실험실은 4K 이상의 해상도를 기반으로 대규모의 3면 디스플레이 공간내에서 다양한 Haptic 장비를 활용해 도면검토, 재난/재해시뮬레이션, 극한건설, 도시계획설계 등이 가능하다. 또한 기존의 BIM 소프트웨어와 완벽한 호환이 가능하여 데이터의 실시간 변환없이 대용량의 도면 등을 검토할 수 있다.

• 한국응용약물학회:학술대회논문집
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• 한국응용약물학회 2000년도 춘계학술대회
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• pp.10-14
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• 2000

The cycloooxygenase enzymes catalyze the oxidative conversion of arachidonic acid into prostag1andin H$_2$Which mediates both benificial and pathological effects. The COX-1 is constitutively expressed in most tissues and in blood platelets wherease the expression of COX-2 isoform is induced in response to inflmmatory stimuli such as cyctokynes. Thus the identification of a novel COX-2 selective inhibitor should offer excellent antiinflammatory activity with minimal side effects such as gastrointestinal toxicity. Recently, a group of structurally unique and biologically active pimarane diterpenoids has been isolated from indigenous Korean medicinal plants. These new diterpenoids turned out to be potential analgesic and antiinflammatory agent due to their potent inhibitory activities of prostaglandin synthesis. We have also found that the inhibition of PGE$_2$synthesis is attributed to the potent COX inhibition by pimarane diterpenoid in arachidonic acid cascade. In conjunction with development of new analgesic and nonsteroidal antiinflammatory agent, a series of works on these diterpenoids have been extensively carried out in our laboratories. These efforts involve the structure-activity relationship of pimaradienoic acid, molecular modelings and COX inibitory activities as well as actiinflammatory effects of its structural analogues. In addition, the total syntheses of the new natural pimarane diterpenoids, their stereoisomers and other structural variants were intensively investigated.