• 대한조선학회지
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• 제23권1호
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• pp.23-32
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• 1986

By virtue of an application of the receptance method, simplified formulae to calculate natural frequencies of stiffened plates having a resiliently mounted or concentrated mass are obtained. Some numerical results are compared with those based on Lagrange's equation of motion and with experimental results. For the problem formulation the stiffened plate is reduced to an equivalent orthotropic plate, a resiliently mounted mass to a spring-mass system, and mode shapes of the plate are assumed with comparison functions consisting of Euler beam functions. The proposed formulae give results in good conformity to both numerical results based on Lagrange's equation of motion and experimental results for in-phase modes of the coupled system. For out-of-phase modes the conformity is assured only in case that the natural frequency of the attached system is less than a half of that the stiffened plate. It is also found that a resiliently mounted mass having its own natural frequency of about two or more times that of the stiffened plate can be reduced to a concentrated mass with assurance of a few percent error in the frequency.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1991년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 22-24 Oct. 1991
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• pp.125-130
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• 1991

This paper presents a tracking filter using pseudomeasurements in an estimated line-of-sight Cartesian coordinate system(ELCCS) whose x-axis is on the line-of-sight to an estimated target position. A target dynamics model and a measurement equation in the ELCCS are derived first and then a tracking filter in the ELCCS named moving coordinate tracking filter(MCTF) is proposed. It is shown that this MCTF is equivalent to a Kalman filter in the inertial Cartesian coordinate system which is widely used in the target tracking system. By approximating the MCTF for a pseudomeasurement noise and an error covariance matrix in the ELCCS, decoupling of three axes can be achieved. In this case, named decoupled moving coordinate tracking filter(DMCTF), computation time can be drastically reduced by utilizing its parallel structure. Finally, the stochastic properties of the MCTF and DMCTF are presented. Especially, a sufficient condition of nondestabilizing deviation for the DMCTF is proposed. The performance of the MCTF and DMCTF are compared with a conventional Kalman tracking filter.

• 전자공학회논문지C
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• 제34C권3호
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• pp.11-22
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• 1997

This paper presents the design and implementation of an efficient algorithm for detecting untestable paths in multi-level circuits. Transforming multi-level circuit into a multiplexor-based one through BDD(binary decision diagram)construction, the proposed algorithm detects untestable paths in the transformed circuits. By constructing ENF (equivalent normal form) only for reconvergent paths, the proposed system detects and removes untestable paths efficiently in terms of the run-time and memory usage. Experimental results for MCNC/ISCAS benchmark circuits show that the system efficiently detects and removes untestable paths. The run-time and memory usage have been reduced by 37.7% and 60/9%, respectively, comapred to the previous methods.

• Journal of Mechanical Science and Technology
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• 제17권9호
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• pp.1287-1296
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• 2003

In this paper the dynamic analysis of the Macpherson strut motor-vehicle suspension system is presented. The equations of motion are formulated using a two-step transformation. Initially, the equations of motion are derived for a dynamically equivalent constrained system of particles that replaces the rigid bodies by applying Newton's second law The equations of motion are then transformed to a reduced set in terms of the relative joint variables. Use of both Cartesian and joint variables produces an efficient set of equations without loss of generality For open chains, this process automatically eliminates all of the non-working constraint forces and leads to an efficient solution and integration of the equations of motion. For closed loops, suitable joints should be cut and few cut-joints constraint equations should be included for each closed chain. The chosen suspension includes open and closed loops with quarter-car model. The results of the simulation indicate the simplicity and generality of the dynamic formulation.

• 한국지진공학회논문집
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• 제9권1호통권41호
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• pp.9-16
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• 2005

본 논문의 목적은 탄성과 비탄성 구조물의 지진응답제어를 위한 마찰감쇠기의 설계절차를 제시하는 것이다. ATC-40과 ATC-55를 이용하여 비탄성 구조물의 등가선형감쇠비와 등가선형주기를 구하였고, 이에 기초하여 목표 성능을 만족하기 위한 마찰감쇠기의 최대마찰력을 결정하는 식을 제시하였다. 이 식은 항복 전후 강성비와 요구되는 탄성강도에 대한 항복강도비, 그리고 구조물의 주기에 따라 비선형 수치해석과 오차가 발생한다. 수식에 의해 산출한 최대마찰력과 비선형 수치 해석에 의해 산출된 값과의 오차를 줄이기 위하여, 최소 제곱법을 사용하여 오차 보정식을 제시하였다. 수치해석결과는 제안된 보정식을 사용하면 탄성 및 비탄성 지진응답제어를 위한 마찰감쇠기의 설계를 합리적으로 수행할 수 있음을 보여준다

• 한국건축시공학회지
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• 제10권2호
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• pp.97-104
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• 2010

본 연구에서는 전열해석 프로그램인 피지벨(PHYSIBEL)을 사용하여 블라인드 내장형 창호시스템의 일사차단성능 및 단열성능에 따른 에너지 성능을 평가하였다. 피지벨 해석시 창호별 구성 재료의 열적특성과 해석조건을 결정하기 위해서 Mock-up시험을 실시하였으며, 컴퓨터 시뮬레이션을 통한 결과를 바탕으로 공동주택 기준층 1개 세대(33평형)를 대상으로 연간에너지 소비특성, 연간전열량, 연간 냉난방 비용을 분석하였다. 실험결과, 연간전열량은 일반 창호시스템 대비 블라인드 내장형 창호시스템에서 블라인드를 올린 경우 냉방시 10%, 난방시 11% 절감할 수 있으며, 블라인드를 내린 경우 냉방시 25%, 난방시 30%정도를 절감할 수 있는 것으로 나타났다. 블라인드 내장형 창호시스템의 냉 난방 부하 절감량은 일반 창호시스템에 비해 냉방시 283.3KWh, 난방시 76.3KWh 로 냉 난방 에너지 절감효과는 단위세대당 359.6KWh 절감시킬 수 있는 것으로 나타났으며, 이것은 단위세대당 연간 에너지원단위(TOE) 약 0.078toe, 이산화탄소톤($tCO_2$) $0.16tCO_2$을 절감시킬 수 있어 온실가스 저감에도 유리할 것으로 판단된다. 또한, 블라인드 내장형 창호시스템의 냉 난방비용 절감액은 일반창호시스템과 비교하여 연간 냉방비용 10만원, 난방비용 5만원으로 연간 냉 난방 비용을 약 15만원 정도 절감시킬 수 있는 것으로 나타났다.

• Structural Engineering and Mechanics
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• 제62권6호
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• pp.719-724
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• 2017

We consider an elastic isotropic plate reinforced by stringers and weakened by a periodic system of rectilinear slots of variable width. The variable width of the slots is comparable with elastic deformations. We study the case when the slots faces get in contact at some area. Determination of parameters characterizing the partial closure of variable width slots is reduced to the solution of a singular integral equation. The action of the stringers is replaced with unknown equivalent concentrated forces at the points of their connection with the plate. The contact stresses and contact zone sizes are found from the solution of the singular integral equation.

• 대한교통학회지
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• 제1권1호
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• pp.10-27
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• 1983

In order to improve the traffic enviroments in the urban streets of Seoul, the computer controlled traffic signal system was installed on 45 intersections at 1980. Afterward, yearly expansion was done to the numbers of 132 intersections and 232 loop detectors. The problems of timing plans were discussed, mainly pedestrian crossing timing as well as the generations of split and offset. The broad urban streets more than 30m require long phasing time of pedestrians, even though the equivalent or correspondent traffic volume is rare. The configuration of computer system for traffic control was disscussed in terms of control strategy. An overview also given. The improvements were measured at every quater. The travel speed improved to 42%, delay time reduced to 41% and number of stops to 43% respectively.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2002년도 추계 학술발표회 논문집
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• pp.258-265
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• 2002

Most structures are expected deform nonlinear and inelastic behavior when subjected to strong ground motion. Nonlinear time history analysis(NTHA) is the most rigorous procedure to compute seismic performance in the various inelastic analysis methods. But nonlinear analysis procedures necessitate more reliable and practical tools for predicting seismic behavior of structures. Some building codes propose the capacity spectrum method. This method is the concept of an equivalent linear system, wherein a linear system having reduced stiffness and increased damping is used to estimate the response of the nonlinear system. This procedure are conceptually simple, but the iterative procedure is time-consuming and may sometimes lead to no solution or multiple solutions. This paper presents a nonlinear direct spectrum method(NDSM) to evaluate seismic performance of structures, without iterative computations, given by the structural initial elastic period and yield strength from the pushover analysis, especially for mixed building structure.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 추계학술대회논문집
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• pp.304-309
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• 2003

A new modal analysis method for rotor systems with periodically time-varying parameters is proposed. The essence of method is to introduce modulated coordinates to derive the equivalent time-invariant equation. This paper presents a modal analysis method using modulated coordinates fur general rotors, of which rotating and stationary parts both possess asymmetric properties. The equation of motion with time-varying parameters is transformed to an infinite order matrix equation with the time-invariant parameters. A theory of modal analysis for the system is presented with the infinite order equation and a couple of reduced order equations. A numerical example with simple asymmetric rotor is provided to demonstrate the effectiveness of the proposed method