• Steel and Composite Structures
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• 제26권5호
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• pp.635-647
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• 2018

In order to improve the efficiency of the Reinforced Concrete, RC, structures against progressive collapse, this paper proposes a procedure using alternate path and specific local resistance method to resist progressive collapse in intermediate RC frame structures. Cap truss consists of multiple trusses above a suddenly removed structural element to restrain excessive collapse and provide an alternate path. Steel strut is used as a brace to resist compressive axial forces. It is similar to knee braces in the geometry, responsible for enhancing ductility and preventing shear force localization around the column. In this paper, column removals in the critical position at the first story of two 5 and 10-story regular buildings strengthened using steel strut or cap truss are studied. Based on nonlinear dynamic analysis results, steel strut can only decrease vertical displacement due to sudden removal of the column at the first story about 23%. Cap truss can reduce the average vertical displacement and column axial force transferred to adjacent columns for the studied buildings about 56% and 61%, respectively due to sudden removal of the column. In other words, using cap truss, the axial force in the removed column transfers through an alternate path to adjacent columns to prevent local or general failure or to delay the progressive collapse occurrence.

• 한국소음진동공학회논문집
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• 제15권2호
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• pp.148-155
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• 2005

As functional requirement of massive digital information storage devices are on a trend for the higher data transfer rate and lower cost, many different technical efforts are being tested and implemented in the industry. FDB(fluid dynamic bearing) is one of the major breakthroughs in rotor design in terms of TMR(track misregistration) budget. Although FDB analysis based on Reynolds' equation is well established and popularly being used for FDB design especially for the estimation of bearing stiffness, there are obvious limitations in the approach due to the inherent assumptions. A generalized analysis tool employing the full Navier-Stokes equation and the energy balance is to be beneficial for detailed FDB design. In this publication, an efficient geometry modeling method is presented that provides fully integrated inputs for general FVM/FDM(finite volume method/ finite difference method) codes. By virtue of the flexibility of the presented method, many different detailed FDB design and analysis are carried over with ease.

• Korea-Australia Rheology Journal
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• 제17권2호
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• pp.47-62
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• 2005

The present study deals with a mathematical model describing the dynamic response of heat and mass transfer in blood flow through bifurcated arteries under stenotic condition. The geometry of the bifurcated arterial segment possessing constrictions in both the parent and the daughter arterial lumen frequently appearing in the diseased arteries causing malfunction of the cardiovascular system, is formulated mathematically with the introduction of the suitable curvatures at the lateral junction and the flow divider. The blood flowing through the artery is treated to be Newtonian. The nonlinear unsteady flow phenomena is governed by the Navier-Stokes equations while those of heat and mass transfer are controlled by the heat conduction and the convection-diffusion equations respectively. All these equations together with the appropriate boundary conditions describing the present biomechanical problem following the radial coordinate transformation are solved numerically by adopting finite difference technique. The respective profiles of the flow field, the temperature and the concentration and their distributions as well are obtained. The influences of the stenosis, the arterial wall motion and the unsteady behaviour of the system in terms of the heat and mass transfer on the blood stream in the entire arterial segment are high­lighted through several plots presented at the end of the paper in order to illustrate the applicability of the present model under study.

• 한국소음진동공학회논문집
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• 제17권1호
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• pp.24-32
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• 2007

This paper presents a finite element method to analyze the free vibration of a flexible HDD composed of the spinning disk-spindle system with fluid dynamic bearings(FDBs), the head-suspension-actuator with pivot bearings, and the base plate with complicated geometry. Experimental modal testing shows that the proposed method well predicts the vibration characteristics of a HDD. This research also shows that even the vibration motion of the spinning disk corresponding to half-speed whirl and the pure disk mode are transferred to a head-suspension-actuator and base plate through the air bearing and the pivot bearing consecutively. The proposed method can be effectively extended to investigate the forced vibration of a HDD and to design a robust HDD against shock.

• 한국자동차공학회논문집
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• 제20권2호
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• pp.47-55
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• 2012

This work deals with dynamic analysis of a monorail system with magnetic caterpillar where magnets are embedded inside each articulated element of the caterpillar, augmenting traction force of main rubber wheels to climb up slope up to 15 degree grade. Considerations are first given to determine stiffness of the primary and secondary suspension springs in order for the natural frequencies of car body and bogie associated with vertical, pitch, roll and yaw motion to be within generally accepted range of 1-2 Hz. Equations for calculating magnetic force needed to climb up given slope are derived, and a magnetic caterpillar system for 1/6 scale monorail is designed based on the derivation. To assess the hill climbing ability and cornering stability, and make sure smooth operation of the side and vertical guiding wheels which is critical for safety, a multibody model that takes into account of every component level design characteristics of car, bogie, and caterpillar is set up. Through hill climbing simulation and comparison with measurement of the limit slope, the validity of the analysis and design of the magnetic caterpillar system are demonstrated. Also by studying the curving behavior, maximum curving speed without rollover, functioning of lateral motion constraint system, the effects of geometry of guiding rails are studied.

• 한국항공우주학회지
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• 제39권3호
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• pp.254-260
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• 2011

원격측정링크는 항공기의 움직임에 따라 안테나 이득과 편파가 실시간으로 변화하는 동적 통신링크이다. 본 논문에서는 항공기의 비행궤적, 자세, 3차원 안테나 패턴을 사용하여 실시간 탑재안테나 이득과 송수신 안테나의 편파 부정합을 계산하였다. 그리고 다중경로 환경을 2-Ray 둥근지구 반사지형으로 모델링하고, 항공기에서 송신한 RF 신호를 빔폭이 좁은 안테나로 수신할 때 수신신호세기를 예측하였다. 또한 비행시험을 실시하고 측정값과 예측값을 비교하여 잘 일치함을 확인하였다.

• Nuclear Engineering and Technology
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• 제43권3호
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• pp.243-256
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• 2011

This paper considers the concept of analog computing based on a cellular neural network (CNN) paradigm to simulate nuclear reactor dynamics using a time-dependent second order form of the neutron transport equation. Instead of solving nuclear reactor dynamic equations numerically, which is time-consuming and suffers from such weaknesses as vulnerability to transient phenomena, accumulation of round-off errors and floating-point overflows, use is made of a new method based on a cellular neural network. The state-of-the-art shows the CNN as being an alternative solution to the conventional numerical computation method. Indeed CNN is an analog computing paradigm that performs ultra-fast calculations and provides accurate results. In this study use is made of the CNN model to simulate the space-time response of scalar flux distribution in steady state and transient conditions. The CNN model also is used to simulate step perturbation in the core. The accuracy and capability of the CNN model are examined in 2D Cartesian geometry for two fixed source problems, a mini-BWR assembly, and a TWIGL Seed/Blanket problem. We also use the CNN model concurrently for a typical small PWR assembly to simulate the effect of temperature feedback, poisons, and control rods on the scalar flux distribution.

• Bulletin of the Korean Chemical Society
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• 제25권12호
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• pp.1845-1849
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• 2004

Apolipoprotein B-100 (Apo-B100) is a major protein component for low density lipoproteins (LDL). A number of mimetic peptides of Apo-B100 were screened from the phase-displayed random peptide library by utilizing monoclonal antibody (B9). Mimetic peptide for B9 epitope against apo B-100 was CRNVPPIFNDVYWIAF (pB1). From the BLAST search, the mimetic peptide pB1 had 40% homology with apo B-100. As a result of the structural determination of this mimotope using homo/hetero nuclear 2D-NMR techniques and NMR-based distance geometry (DG)/molecular dynamic (MD) computations, DG structure had low penalty value of 0.3-0.6 ${\AA}^2$ and the total RMSD was 0.5-1.5 ${\AA}. Moreover, pB1 structure included a weak $3_{10}$-helix from $Ile^7$,/TEX> to $Trp^{13}$.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2010년도 정기 학술대회
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• pp.628-631
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• 2010

환경문제에 대한 관심으로 자동차에 대한 경량화가 요구되는 동시에 안전규제가 강화 되고 있어, 높은 인장강도를 가지는 고강도 강의 차체 적용 비율이 점차 증가하고 있다. 또한, 자동차 1대를 조립하기 위한 저항 점용접 횟수를 줄이고, 용접부에 충격안정성을 확보하기 위한 관심이 고조되고 있다. 따라서, 국내 자동차 산업에서 용접부의 신뢰성을 보장하기 다양한 비파괴 검사를 적용하고 있으며, 생산 공정에 적용하고 있다. 그중에서 용접 전극 사이에서 동저항(Dynamic resistance, 용접 공정중모재의 저항값의 변화)을 계측하여 용접성을 평가하는 방법이 제시되고, 차체 조립공정 중에 적용하려는 시도가 이루어지고 있다. 본 연구에서는 자동차 차체용 냉간 압연강판(590MPa dual-phase steel)을 인버터 DC 저항 점 용접하여, 용접전극 사이에서 동저항을 측정 하였다. 용접성은 인장전단 강도로 평가하였고, 용접 공정 변수는 용접 전류, 용접 시간, 가압력을 선정하였다. 동저항 그래프의 ${\alpha}$-peak와 ${\beta}$-peak값을 인장전단 강도에 따라 회귀 분석하여, 동저항에 따른 인장전단 강도를 예측하였다. 추가적으로, 용접부의 외관 형상 중에 압흔 깊이와 압흔자국 지름에 대한 회귀분석을 실시하였으며, 용접부 형상에 대한 신뢰성을 부여하였다.

• 오토저널
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• 제13권3호
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• pp.32-42
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• 1991

In SI engine research the pressure data in cylinder is the most important fundamental ones leading to engine efficiencies and performances. It is, therefore, necessary to obtain accurate pressure data and yet it is often impossible to install a reliable data producing, flush-mounted type pressure transducer in a cylinder of small and medium size multicylinder SI engines. When flush mounting the transducer is not possible, the spark-plug type pressure transducer is commonly used as an alternative. In this case, the transmission tube of spark-plug type pressure transducer introduces distortions in the pressure signal. Efforts were made to understand the dynamic characteristics of spark-plug pressure transducer by shock tube tests and real engine experiments. In engine experiment the cylinder pressure data were simultaneously obtained by both flush mounted and spark-plug type pressure transducers of certain transmission tube geometry. Those pressure data collected by spark-plug type pressure transducer were tested for correction to flush mounted ones by the application of transfer function. As a result of the calibration the IMEP difference between F/M data and improved S/P data was shown to be corrected about 75-98% from the original ones.