• 한국응용약물학회:학술대회논문집
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• 한국응용약물학회 1995년도 춘계학술대회
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• pp.81-81
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• 1995

It is well known that Src Homology 2(SH2) domain in many intracellular signal transduction proteins is very important. The domain has about 100 amino acid residues and bind phosphotyrosine-containing peptide with high affinity and specificity. Lck SH2 domain is a Src-like, lymphocyte-specific tyrosine kinase. An 11-residue phosphopeptide derived from the hamster polvoma middle-T antigen, EPQp YEEIPIYL, binds with an 1 nM dissociation constant to Lck SH2 domain. And it is known that the phosphotyrosine and isoleucine residues of the peptide are tightly bound by two well-defined pockets on Lck SH2 domain's surface. To investigate the conformational changes during complexation of SH2 domain with phosphopeptide we have performed the molecular dynamics simulation for Lck SH2 domain with peptide and peptide-free form at look in aqueous solution. More than 3000 water molecules were incorporated to solvate Lck SH2 domain and peptide. Periodic boundary condition has been applied in molecular dynamics simulation. Data analysis with the results of that simulation shows that the phosphopeptide makes primary interaction with the Lck SH2 domain at six central residues, The comparison of the complexed and uncomplexed SH2 domain structures in solution has revealed only relatively small change. But the hydrophilic and hydrophobic pockets in the protein surface show the conformational changes in spite of the small structural difference between the complex and peptide-free forms.

• Computers and Concrete
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• 제25권1호
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• pp.67-73
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• 2020

Traditionally used analytical approach to predict the fatigue failure of reinforced concrete (RC) structure is generally conservative and has certain limitations. The nonlinear finite element method (FEM) offers less expensive solution for fatigue analysis with sufficient accuracy. However, the conventional implicit dynamic analysis is very expensive for high level computation. Whereas, an explicit dynamic analysis approach offers a computationally operative modelling to predict true responses of a structural element under periodic loading and might be perfectly matched to accomplish long life fatigue computations. Hence, this study simulates the fatigue behaviour of RC beams with finite element (FE) assemblage presenting a simplified explicit dynamic numerical solution to show computer aided fatigue behaviour of RC beam. A commercial FEM package, ABAQUS has been chosen for this complex modelling. The concrete has been modelled as a 8-node solid element providing competent compression hardening and tension stiffening. The steel reinforcements are simulated as two-node truss elements comprising elasto-plastic stress-strain behaviour. All the possible nonlinearities are duly incorporated. Time domain analysis has been adopted through an automatic Newmark-β time incremental technique. The program consists of twelve RC beams to visualize the real behaviour during fatigue process and to obtain the reliability of the study. Both the numerical and experimental results indicate a redistribution of stresses along the time and damage accumulation of beam which severely affect the serviceability and ultimate capacity of RC beam. The output of the FEM analysis demonstrates good match with the experimental consequences which affirm the efficacy of the computer aided model. The controlled fatigue damage evolution at service fatigue load limits makes the FE model an efficient tool in predicting high cycle fatigue behaviour of RC structures.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.251-251
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• 2012

A lot of studies are undergoing on the magneto-optical (MO) properties of patterned magnetic systems for the reason that they have potential application to information technology such as ultrahigh-speed computing. Moreover, they can be considered as the future candidates for high-density MO storage devices. Not only the technical aspects, but there have been also tremendous interests in studying their properties related to the fundamental physics. The MO Kerr-rotation effects (both in reflected and the diffracted modes) and the magnetic force microscopy (MFM) are very useful techniques to investigate the micromagnetic properties of such periodic structures. Hence, in this study, we report on the MO properties of bilayered Cobalt (Co)/ nickel (Ni) micro-patterned anti-dot arrays. Such a ferromagnetic structure was made by sequentially depositing co (40 nm)/Ni (5 nm) bilayer on a Si substrate. The anti-dot patterning with hole diameter of $1{\mu}m$ was done only on the upper Co layer using photolithography technique, while the Ni underlayer was kept uniform. The longitudinal Kerr rotation (LKR) of the zeroth- and the first-order diffracted beams were measured at an incidence of $30^{\circ}$ by using a photoelastic modulator method. The external magnetic field was applied perpendicularly to the reflected and the diffracted beams using an electromagnet capable of a maximum field of ${\pm}5$ kOe. Significantly, it was observed that the LKR of the first-order diffracted beam is nearly 4 times larger than that of the zeroth-order beam. The simulated results for the hysteresis loops matched qualitatively well with the experimentally obtained ones. In conjunction with the LKR, we also investigated the magnetic-domain structure by using a MFM system, which were analyzed to elucidate the origin of the enhanced MO rotation.

• 한국측량학회지
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• 제9권1호
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• pp.17-25
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• 1991

토목 구조물의 시공을 위해서는 기초굴착이 필수적이며 변형으로 인한 재해의 위험이 있으므로 주기적인 변형측정이 필요하다. 기존의 굴착측면에 대한 현장계측은 상대변위 밖에 얻을 수 없고 표면 측정이 불가능하므로 이러한 난점을 해결할 수 있는 방법의 개발이 절실하다. 본 연구에서는 대상물로부터 독립적으로 단 시간내에 다량의 측점에 대해 절대변형량의 도출이 가능한 지상사진 측량을 굴착현장에 적용하기 위하여 동일점 촬영기법을 개발, 실내실험을 통해 해석 가능성을 제시하고 현장에 적용, 기간별 절대변형량을 산출하였다. 동일 촬영점 기법을 실내실험에 적용한 결과 해석인 가능하였으며, 인접 사진과의 중복도를 보다 크게하여 해석한다면 다른 기법보다 신속하게 양호한 성과를 얻을 수 있음을 알 수 있었다. 이 기법을 실제 굴착측면에 적용한 결과 기대 정확도 범위내에서 일관성있는 3차원 변형량을 도출할 수 있었으며 보다 신속 정확한 기준점 측량방법을 개발한다면 효율적으로 변형량을 얻을 수 있을 것이다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.444-444
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• 2011

Recently, patterned magnetic films and elements attract a wide interest due to their technological potentials in ultrahigh-density magnetic recording and spintronic devices. Among those patterned magnetic structures, magnetic anti-dot patterning induces a strong shape anisotropy in the film, which can control the magnetic properties such as coercivity, permeability, magnetization reversal process, and magneto-resistance. While majority of the previous works have been concentrated on anti-dot arrays with a single magnetic layer, there has been little work on multilayered anti-dot arrays. In this work, we report on study of the magnetic properties of bilayered anti-dot system consisting of upper perforated Co layer of 40 nm and lower continuous Ni layer of 5 nm thick, fabricated by photolithography and wet-etching processes. The magnetic hysteresis (M-H) loops were measured with a superconducting-quantum-interference-device (SQUID) magnetometer (Quantum Design: MPMS). For comparison, investigations on continuous Co thin film and single-layer Co anti-dot arrays were also performed. The magnetic-domain configuration has been measured by using a magnetic force microscope (PSIA: XE-100) equipped with magnetic tips (Nanosensors). An external electromagnet was employed while obtaining the MFM images. The MFM images revealed well-defined periodic domain networks which arise owing to the anisotropies such as magnetic uniaxial anisotropy, configurational anisotropy, etc. The inclusion of holes in a uniform magnetic film and the insertion of a uniform thin Ni layer, drastically affected the coercivity as compared with single Co anti-dot array, without severely affecting the saturation magnetization ($M_s$). The observed changes in the magnetic properties are closely related to the patterning that hinders the domain-wall motion as well as to the magneto-anisotropic bilayer structure.

• 한국인터넷방송통신학회논문지
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• 제20권5호
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• pp.151-156
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• 2020

주기적인 사다리꼴 격자구조에서 광 신호의 회절 특성과 테이퍼 측면의 중요한 효과를 분석하기 위하여, 처음으로 격자구조의 Toeplitz 유전율 tensor를 2D spatial Fourier 급수로 정의하고 공식화하였다. 그때 각 층에서의 필드들은 고유치 문제에 기초하여 표현하였으며, 완전한 해는 적절한 경계 값 문제에 의존하는 모드 전송선로 이론 (MTLT)을 사용하여 정확하게 유도하였다. 이에 기초하여, 사다리꼴 형태의 굴절률 분포를 갖는 격자구조의 테이퍼 측면 프로파일이 서브 파장 격자 반사기 설계에 어떠한 영향을 미치는지 자세하게 수치해석 하였다. 사다리꼴 격자구조의 회절특성에 기초한 수치해석 결과, 테이퍼 측벽 프로파일은 반사 대역폭, 평균 반사율, 그리고 밴드 에지를 결정하는 데 중요한 역할을 하는 것으로 나타났다.

• Smart Structures and Systems
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• 제25권1호
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• pp.57-64
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• 2020

The nonlinear dynamics of a directly forced clamped-clamped-free-free magneto-rheological elastomer (MRE) sandwich shell has been experimentally investigated. Experiments have been conducted on an aluminium shallow shell (shell A) and an MRE-aluminium sandwich shallow shell with single curvature (shell B). An electrodynamic shaker has been used to directly force shells A and B in the vicinity of their fundamental resonance frequency; a laser displacement sensor has been used to measure the vibration amplitude to construct the frequency-response curves. It was observed that for an aluminium shell (shell A), that at small forcing amplitudes, a weak softening-type nonlinear behaviour was observed, however, at higher forcing amplitudes the nonlinear dynamical behaviour shifted and a strong hardening-type response occurred. For the MRE shell (shell B), the effect of forcing amplitude showed softening at low magnetic fields and hardening for medium magnetic fields; it was also observed the mono-curved MRE sandwich shell changed dynamics to quasiperiodic displacement at some frequencies, from a periodic displacement. The presence of a magnetic field, initial curvature, and forcing amplitude has significant qualitative and quantitative effects on the nonlinear dynamical response of a mono curved MRE sandwich shell.

• 한국광학회지
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• 제25권4호
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• pp.193-199
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• 2014

본 연구에서는 FDTD와 광선추적기법을 결합한 시뮬레이션을 활용해 광원으로 설정된 쌍극자의 진동 방향, 유리기판에 적용된 Mie 산란입자와 Pillow 렌즈가 광결정 구조가 포함된 OLED의 광추출효율에 미치는 영향을 조사하였다. 쌍극자 광원의 진동방향이 OLED 표면에 대해 수평인 경우, 광결정구조만 적용된 OLED의 효율이 54%인데 반해 최적화된 조건의 Mie 산란입자, Pillow 렌즈가 적용된 OLED는 약 86%의 광추출효율을 나타냈다. 아울러 광결정 구조로 인해 특정 각도로 광도가 증가하는 문제점이 Mie 산란입자의 산란효과로 인해 완화될 수 있음을 알았다. 본 연구는 광추출효율을 향상시키는 다양한 광학구조를 적용함과 더불어 발광체 유기분자의 배향을 조절함으로써 OLED의 효율을 큰 폭으로 향상시킬 수 있음을 보여준다.

• Applied Microscopy
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• 제15권2호
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• pp.98-110
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• 1985

This study was performed to clarify the morphological structures of the epithelia of the renal papilla, renal pelvis and ureter of the sheep (Ovis aries L.) through the light and scanning electron microscopes, Tissue specimens were taken from the renal papilla (common renal papilla and peripelvic column) and the renal pelvis (pelvis proper and pelvic pouch) of the kidney and the ureter. For the light microscopy, tissue blocks were fixed in 10 % neutral buffered formalin and embedded in paraffin wax, serially sectioned at a thickness of $6{\mu}m$. These sections were stained with hematoxylin-eosin and periodic acid-Schiff reaction. For the scanning electron microscopy, tissue blocks were prefixed in 1% glutaral-dehyde-1.5% paraformaldehyde solution and postfixed in 1% osmium tetroxide solution, dehydrated in graded alcohol, transferred to isoamyl acetate, and then dried by the critical point dryer (Polaron E 3000). These dried tissues were coated with gold and observed with a scanning electron microscope (JSM-35C), The results were as follows: The apex of the common renal papilla was lined with simple columnar epithelium having many microvilli on its luminal surface. Lateral portion of the papilla was lined with stratified epithelium $2{\sim}3$ layers thick, and its superficial cells were microvillar cells having many microvilli. The epithelium lining the peripelvic column was $1{\sim}2$ layers thick. The superficial layer was made of the microvillar cells, but a few microplica cells were appeared in the region near the pelvic pouch. The epithelium of the pelvic pouch was $1{\sim}2$ layered transitional type, and its superficial cells were microplica cells. The epithelia of the pelvis proper and ureter were $4{\sim}6$ layered transitional type, and their superficial cells were typical facet cells existing many round depressions and ridges of cell membranes of the luminal side.

• 한국축산시설환경학회지
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• 제16권1호
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• pp.13-20
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• 2010

본 연구사업 목적은 축분 공동 퇴비화시설에서 배출되는 퇴비화 악취물질이 퇴비화시설 기계에 부식과 마모를 일으켜서 기계 고장을 발생하는 현상을 방지하기 위해 축분퇴비화 시설 기계의 내구성을 재질과 구조 및 보수와 관리 측면에서 평가하여 축분 퇴비화 시설 기계의 내구성을 증대하고, 이에 개선 대책을 마련하는데 있었으며 주요 성과는 아래와 같다. 퇴비화시설 기계의 고장의 주요원인은 부식과 마모, 과부하 상태, 이물질 혼입 등 이었다. 퇴비화시설 기계에서 고장빈도가 높은 곳은 교반장치, 포장장치, 반송장치 등의 체인, 교반 날과 축, 모터, 스크루 베인 등에서 발생 되므로 정기점검과 보수관리가 중요하였다. 퇴비화시설 기계의 내구성 증대를 위한 고장 방지대책은 탈취장치 설치, 돌가루와 쇠붙이 등의 이물질 혼입방지, 고 수분 재료 사용방지 및 재료 과다투입 방지 등 이었다. 미 이용자원의 유효이용 및 유가성 폐기물의 퇴비화 처리를 위한 우리나라 지방자치단체의 바이오매스 타운 건설에 본 조사연구의 성과가 성공적으로 활용될 것으로 기대한다.