• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 추계학술대회논문집 II
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• pp.1260-1265
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• 2001

It is important to model the mechanical structure precisely and reasonably in predicting the dynamic characteristics, controlling the vibration, and designing the structural dynamics. In the finite element modeling, the errors can be contained from the physical parameters, the approximation of the boundary conditions, and the element modeling, From the dynamic test. more precise dynamic characteristics can be obtained. Model updating using parameter modification is appropriate when the design parameter is used to analyze the input parameter like finite element method. Finite element analysis for free-free-free-free(FFFF) and clamped-free-free-free(CFFF) plate with uniform area and shape change are carried out as model updating examples, Mass and stiffness matrices are updated by comparing test and analytical modal frequencies. The result shows that the updated frequencies become closer to the test frequencies.

• Korea-Australia Rheology Journal
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• 제19권2호
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• pp.51-59
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• 2007

A polyelectrolyte chain confined in a slit nanochannel exhibits a structural transition from the one in free space. In this paper, the effect of the long-range electrostatic interactions between the xanthan polyelectrolyte and the slit wall on the confined xanthan conformation is investigated via the Brownian dynamics simulation. A neutral and two negatively charged surfaces of polydimethylsiloxane (PDMS) and glass are combined to make four kinds of slit channels with different charge characteristics: i) neutral-neutral, ii) glass-glass, iii) neutral-PDMS and iv) neutral-glass walls. Their walls are characterized by uniform surface charge densities determined from experimental data of zeta potential. Both the nonmonotonic chain size variation and the loss of long-range bond vector correlation, previously observed under confinement in the PDMS-PDMS slit, are also found in the neutral slit, demonstrating the nonelectrostatic origin of such crossover behaviors. As expected, the effect of wall charges is negligible at sufficiently high medium ionic strength of 100mM but it becomes significant in the opposite limit of 0.01mM. In the latter case, the high charge density of glass walls strengthens the effective confinement of a negatively charged polyelectrolyte and produces a xanthan structure comparable to that confined in a much narrower neutral slit. The obtained structural data suggest the possibility of controlling the structure of confined polyelectrolytes by the modification of surface charge characteristics of micro/nanofluidic devices in combination with the adjustment of the medium ionic strength.

• 한국지진공학회논문집
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• 제2권4호
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• pp.63-72
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• 1998

본 연구는 허용진동환경을 만족하기 위한 콘크리트 슬래브의 미진동해석 및 제어기법에 관한 것이다. 본 연구에서는 제시된 방법은 임의 두 점간의 전달 함수와 가속 도로부터 미지의 가진력을 산정하고 수치해석 및 구조실험의 검증을 통하여 콘크리트 슬래브의 미진동해석 및 제어를 실시하였다. 미진동제어 설계를 위한 구조물의 고유진동수는 25-30Hz 이상이 되는 것인 바람직하며 콘크리트 구조물에서의 감쇠가 3%-5%인 경우 가진력 진동성분의 1.5배 이상 되는 것이 바람직함을 밝혔다.

• 센서학회지
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• 제8권5호
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• pp.377-387
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• 1999

결합형 유한요소-경계요소 기법을 사용하여 심해저용 유연형 압전체 쏘나 트랜스듀서를 설계하였다. 쏘나 트랜스듀서의 역학적 구동을 3차원적으로 모델링하였고 전기적 외부 부하 조건을 가지고 분석하였다. 쏘나 트랜스듀서의 정상 상태 변위 모드, 지향성, 공진 주파수, TVR과 같은 결과들을 보였다. 본 논문의 술통 형태의 압전체 쏘나 트랜스듀서를 설계하면서, 심해저용으로 사용하기 위해 쏘나 트랜스듀서의 내외부에 동일한 수압이 가해지도록 쏘나 트랜스듀서의 외부 표면 구조를 새롭게 변형시킨 결과 낮은 주파수의 새로운 공진 모드가 발생하였으나 그 크기는 외부 표면 구조 변형의 정도에 따라 조절될 수 있다.

• Journal of Electrical Engineering and Technology
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• 제11권1호
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• pp.215-226
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• 2016

Modeling, control and implementation of a real redundant robot with five Degrees Freedom (DOF) of the SCARA (Selective Compliant Assembly Robot Arm) manipulator type is presented. Through geometric methods and structural and functional considerations, the inverse kinematics for redundant robot can be obtained. By means of a modification of the classical sliding mode control law through a hyperbolic function, we get a new algorithm which enables reducing the chattering effect of the real actuators, which together with the learning and adaptive controllers, is applied to the model and to the real robot. A simulation environment including the actuator dynamics is elaborated. A 5 DOF robot, a communication interface and a signal conditioning circuit are designed and implemented for feedback. Three control laws are executed in: a simulation structure (together with the dynamic model of the SCARA type redundant manipulator and the actuator dynamics) and a real redundant manipulator of the SCARA type carried out using MatLab/Simulink programming tools. The results, obtained through simulation and implementation, were represented by comparative curves and RMS indices of the joint errors, and they showed that the redundant manipulator, both in the simulation and the implementation, followed the test trajectory with less pronounced maximum errors using the adaptive controller than the other controllers, with more homogeneous motions of the manipulator.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문집
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• pp.301-305
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• 2002

Among many structural dynamics modification methods for plate and shell vibration problems, embedding an emboss to the surface is very efficient. But deciding an optimal position and shape using optimization algorithm needs defining geometry and remeshing the model for every iteration step to implement the method, which takes much numerical cost. An equivalent element produced here lessen the cost by representing the geometrical characteristics of an emboss using the element's material properties and thickness becoming a geometrically homogenous element of the base plate or shell. Some efficient factors which let the equivalent system have the same dynamical response as the original system embedded with emboss will be shown and the degree of equivalence will be tested in terms of natural frequency matching.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 춘계학술대회논문집
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• pp.485-491
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• 2000

We obtain the mathematical model of the hard disk drive actuator system from the system response data of the finite element analysis or experimental results. System response data including the dynamics of the considered system are expressed as the mathematical model. It allows the dynamic analysis of the actuator system without resort to the repetitive finite element modeling work. Even though the dynamic characteristics of the system are affected somewhat by the structural modification and the change of the dynamic properties, we can use the modified size and material properties of the actuator system in the mathematical model to some extent. In this study, we express the mathematical model of the simplified rectangular plate first and then proceed to the actual hard disk drive actuator system.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 춘계학술대회 논문요약집
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• pp.71-71
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• 2004

일반적으로 동흡진기는 하나의 가진진동수에 의해 진동하는 감쇠가 작은 기계나 구조물에 효과적으로 적용되고 있다 대부분의 동흡진기의 적용 사례는 주 진동이 유발되는 부위, 또는 진동을 억제해야하는 부위에 직접적으로 동흡진기를 부가하여 효과를 얻는 방식을 택하고 있다. 그러나 절연기를 설치 할 수 없는 경우라든지, 절연기로는 한계가 있는 경우, 이미 설치가 완료된 기계 시스템에 절연 변경이 곤란한 경우 또는 국부 진동모드에 대한 진동저감을 할 때는 동흡진기에 대해 보다 일반적인 접근 방법이 필요하며 질량과 스프링계를 부착하기 힘든 경우나 억제시키려는 부위에 설비나 기기의 성능을 저해할 수 있는 경우에는 부득이 그 위치를 변경시켜 줘야 할 경우가 생긴다 할 수 있다.(중략)

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 춘계학술대회논문집
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• pp.72-76
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• 2003

Even though embossing is an effective SDM(Structural Dynamics Modification) technique, it is difficult to implement the method in fields owing to its geometric complexity. In this research low flat-top emboss shape, rather than general shape, is considered and a systematic procedure is derived in describing the emboss implementation procedure utilizing the fact that the emboss shape can be fully expressed only if the boundary elements are appropriately given. Best position to maximize natural frequencies is found using the procedure and usefulness of the suggested technique is illustrated.

• BMB Reports
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• 제51권12호
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• pp.609-610
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• 2018

Glycosylation is one form of protein modification and plays a key role in protein stability, function, signaling regulation and even cancer. NleB and SseK are bacterial effector proteins and possess glycosyltransferase activity, even though they have different substrate preferences. NleB/SseKs transfer the GlcNAc sugar to an arginine residue of host proteins, leading to reduced $NF-{\kappa}B-dependent$ responses. By combining X-ray crystallography, NMR, molecular dynamics, enzyme kinetic assays and in vivo experiments, we demonstrated that a conserved HEN (His-Glu-Asn) motif in the active site plays a key role in enzyme catalysis and virulence. The lid-domain regulates the opening and closing of the active site and the HLH domain determines the substrate specificity. Our findings provide evidence for the enzymatic mechanism by which arginine can be glycosylated by SseK/NleB enzymes.