• Wind and Structures
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• 제38권1호
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• pp.15-42
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• 2024

A flexible-base coupled-two-beam (CTB) discrete model with equivalent tuned mass dampers is used to assess the effect of soil-structure interaction (SSI) and different types of lateral resisting systems on the design of passive dynamic absorbers (PDAs) under the action of along-wind and across-wind loads due to vortex shedding. A total of five different PDAs are considered in this study: (1) tuned mass damper (TMD), (2) circular tuned sloshing damper (C-TSD), (3) rectangular tuned sloshing damper (R-TSD), (4) two-way liquid damper (TWLD) and (5) pendulum tuned mass damper (PTMD). By modifying the non-dimensional lateral stiffness ratio, the CTB model can consider lateral deformations varying from those of a flexural cantilever beam to those of a shear cantilever beam. The Monte Carlo simulation method was used to generate along-wind and across-wind loads correlated along the height of a real shear wall-frame building, which has similar fundamental periods of vibration and different modes of lateral deformation in the xz and yz planes, respectively. Ambient vibration tests were conducted on the building to identify its real lateral behavior and thus choose the most suitable parameters for the CTB model. Both alongwind and across-wind responses of the 144-meter-tall building were computed considering four soil types (hard rock, dense soil, stiff soil and soft soil) and a single PDA on its top, that is, 96 time-history analyses were carried out to assess the effect of SSI and lateral resisting system on the PDAs design. Based on the parametric analyses, the response significantly increases as the soil flexibility increases for both type of lateral wind loads, particularly for flexural-type deformations. The results show a great effectiveness of PDAs in controlling across-wind peak displacements and both along-wind and across-wind RMS accelerations, on the contrary, PDAs were ineffective in controlling along-wind peak displacements on all soil types and different kind of lateral deformation. Generally speaking, the maximum possible value of the PDA mass efficiency index increases as the soil flexibility increases, on the contrary, it decreases as the non-dimensional lateral stiffness ratio of the building increases; therefore, there is a significant increase of the vibration control effectiveness of PDAs for lateral flexural-type deformations on soft soils.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1991년도 춘계학술대회
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• pp.82-85
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• 1991

Cell kinetics and the chemical mass action principle formulate the basis of immune system dynamics which may be synthesized mathematically as cascades of bilinear systems which are connected by nonlinear nondynamical terms. In this manner, a model for cell-mediated immune response (CMI) to tumor antigens and debris is developed. We also consider parametric control variables relevant to the latest experimental data, i.e., sigmoidal dose-response relationship and Michaelis-Menten dynamics. The preliminary results show that the parametric control variable is important in the destruction of tumors. As well as that, the exacerbation theory is a good method for tumor treatment. Finally, tumor control as an application of immunotherapy is analyzed from the basis established above.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.1800-1803
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• 1997

This paper presents new feedback actuators to achieve an accurate position control of a flexible gnatry robot arm. the translational motion in the plane is generated by two d.c.motors and controlled by emplying elecor-rheological(ER) clutch acutators. The generated motion can be continuously controlled by controlling the intensity of lectric field imposed to the ER fluid domain which tunes the transmitted torque of the ER clutch. n the other hand, during control action of the translational motion a flexible arm attached to the moving mass produces undesirable oscillatins due to its inherent flexibility. The oscillations are actively suppressed by applying feedback voltages to piezoceramic acutators bonded on the surface of the flexible arm. The control electric fields to be applied to the ER clutch and the control voltage for the piezoceramic actuator are determined via the loop shaping esign procedures(LSDP) in the H.inf. control technique. Comsequently, an accuate positiion control at the end-point of the flexible am is achieved during planar motion.

• Bulletin of the Korean Chemical Society
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• 제33권9호
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• pp.2855-2860
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• 2012

The coating N-acetyl cysteine (NAC) on gold surfaces may be used to design the distribution of either gold particle adsorbed to the $ZrO_2$ surface or vice versa by adjusting the electrostatic interactions. In this study, it was performed to find out electrostatic properties of the NAC-coated-gold surface and the $ZrO_2$ surface. The surface forces between the surfaces were measured as a function of the salt concentration and pH value using the AFM. By applying the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory to the surface forces, the surface potential and charge density of the surfaces were quantitatively acquired for each salt concentration and each pH value. The dependence of the potential and charge density on the concentration was explained with the law of mass action, and the pH dependence was with the ionizable groups on the surface.

• Bulletin of the Korean Chemical Society
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• 제25권2호
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• pp.293-297
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• 2004

The ignition of monomethylamine was studied in reflected shock waves over the temperature range of 1255- 1579 K and the pressure range of 1.04-1.51 bar. The ignition delay time was measured by the sudden increase of pressure profile and the radiation emitted by OH radicals. The relationship between the ignition delay time and the concentrations of monomethylamine and oxygen was determined in the form of mass-action expressions with an Arrhenius temperature dependence. In contrast to the behavior observed in hydrocarbons, monomethylamine acts to accelerate rather than inhibit its own ignition. And numerical modeling of the ignition of $CH_3NH_2$ has also been carried out to test the several kinetic mechanisms.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1991년도 추계학술대회 논문집 학회본부
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• pp.336-338
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• 1991

Effects of $Nb_2O_5$ addition ranged from 0.0 to 0.75(wt%) on the microstructure and electrical porperties of PZT ceramics have been investigated. The Pb vacancy concentration increases with increasing NbO content. However, the experimental results show the resistivity increases with increasing $Nb^{5+}$ content. This behavior can be explained as a compensation effect and $Nb^{5+}$ can serve as a donar and contribute electrons to the conduction process. According to the law of mass action, this result may reduce the total charge carrier:thus the resistivity increase with NbO content in PZT.

• Journal of applied mathematics & informatics
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• 제29권5_6호
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• pp.1097-1115
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• 2011

We consider the global stability of a general tuberculosis model with two differential infectivity, n classes of latent individuals and mass action incidence. This system exhibits the traditional threshold behavior. There is always a globally asymptotically stable equilibrium state. Depending on the value of the basic reproduction ratio $\mathcal{R}_0$, this state can be either endemic ($\mathcal{R}_0$ > 1), or infection-free ($\mathcal{R}_0{\leq}1$). The global stability of this model is derived through the use of Lyapunov stability theory and LaSalle's invariant set theorem. Both the analytical results and numerical simulations suggest that patients should be strongly encouraged to complete their treatment and sputum examination.

• Journal of Mechanical Science and Technology
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• 제18권8호
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• pp.1375-1387
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• 2004

A solution is given for the elastodynamic problem of a crack perpendicular to the graded interfacial zone in bonded materials under the action of anti plane shear impact. The interfacial zone is modeled as a nonhomogeneous interlayer with the power-law variations of its shear modulus and mass density between the two dissimilar, homogeneous half-planes. Laplace and Fourier integral transforms are employed to reduce the transient problem to the solution of a Cauchy-type singular integral equation in the Laplace transform domain. Via the numerical inversion of the Laplace transforms, the values of the dynamic stress intensity factors are obtained as a function of time. As a result, the influences of material and geometric parameters of the bonded media on the overshoot characteristics of the dynamic stress intensities are discussed. A comparison is also made with the corresponding elastostatic solutions, addressing the inertia effect on the dynamic load transfer to the crack tips for various combinations of the physical properties.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2002년도 춘계학술대회 논문집
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• pp.505-509
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• 2002

The looper control of hot strip finishing mill is one of the most important control item In hot strip rolling mill process. Loopers are placed between finishing mill stands and control the mass flow of the two stands. Another important action of the looper is to control the strip tension which influences on the width of the strip. So it is very important to control both the looper angle and the strip tension simultaneously but the looper angle and the strip tension are strongly interacted by each other. The gain scheduling is to break the control design process into two steps. First, one designs local linear controllers based on linerizations of the nonlinear system at several different operating conditions. Second, a global nonlinear controller for the nonlinear system is obtained by interpolating.

• 한국산학기술학회논문지
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• 제4권3호
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• pp.307-311
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• 2003

탈염기 혼합 이온교환 수지탑에서 양 ㆍ 음이온의 최적혼합비율을 결정하기 위해 실험을 수행하였다. 2, 3, 4, 5 성분 양ㆍ음이온 흡착은 많은 양이온 그리고 음이온의 선택도를 얻기 위하여 small-volume batch test로부터 실험 데이터를 얻기 위해 수행되었다. Quantitative run time은 반-실험적 질량 작용과 표면 착화 모델을 이용한 이온 교환 모델에 의해서 추정될 수 있었다. 탈염기 수지층의 음이온 교환수지에 대한 양이온 교환수지의 비율을 증가시킴으로써 더 길게 사용될 수 있다.