• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
• /
• pp.734-738
• /
• 1996

An adaptive output feedback controller is designed for tracking control of an n-link robot manipulator with unknown load. High-gain observers with same structure as error dynamic systems are used to estimate joint velocities. The parameter adaptation is achieved by the smoothed projection algorithm. The control inputs are saturated outside a domain of interest. Simulation results on a 2-link manipulator illustrate that when the speed of the high-gain observer is sufficiently high, the proposed controller recovers the performance under state feedback control.

• 한국신뢰성학회:학술대회논문집
• /
• 한국신뢰성학회 2001년도 정기학술대회
• /
• pp.455-462
• /
• 2001

We propose a new method to evaluate the network reliability which greatly reduces the intermediate steps toward calculations of maximum capacity flow by excluding unnecessary simple paths contained in the set of failure simple paths. By using signed simple paths and signed flow, we show that our method is more efficient than that of Lee and Park (2001a) in the number of generated composite paths and in the procedure for obtaining minimal success composite paths. Numerical examples are given to illustrate the use and the efficiency of the method.

• Communications for Statistical Applications and Methods
• /
• 제13권3호
• /
• pp.577-585
• /
• 2006

This paper presents a method for reliability evaluation of a telecommunication network with variable link-capacities when the simple paths of the network are known. The LP-EM, suggested by Lee and Park (2001), identifies a composite path as a subnetwork and adds only a minimal set of links at each step which gives maximal increase on the maximum capacity flow of the subnetwork. Thereby the LP-EM reduces the possible occurrence of redundant composite paths significantly over other existing methods. Based on the LP-EM, our method further reduces the possible redundancy by identifying such simple paths that could give no increase of maximum capacity flow on the current subnetwork and excluding those simple paths from consideration in the process of constructing composite paths.

• 대한교통학회지
• /
• 제26권6호
• /
• pp.81-89
• /
• 2008

도시고속도로의 확대와 더불어 일반 간선도로에 접속되는 도시고속도로 진출램프 또한 증가하고 있으며, 진출램프가 혼잡한 간선도로 상에 접속시 간선도로에서의 차량 혼입으로 인한 혼잡 가중 및 이로 인한 진출램프에서의 대기행렬이 역류하여 도시고속도로 본선에 혼잡의 영향이 미치는 현상이 발생하고 있다. 이러한 문제를 해결하고자 본 연구에서는 도시고속도로 진출부 교차로 제어의 개념으로 접근하여 도시고속도로 진출차량을 포함한 간선도로에서의 교통상황(하류부 링크 포함)까지도 고려하여 간선도로가 포화된 경우, 진출램프가 포화된 경우, 간선도로와 진출램프 모두 포화된 경우로 나누어 각 교통상황별 제어전략의 효과를 분석하였으며, 제어전략의 효과에 영향을 미치는 기하조건을 반영하기 위하여 COSMOS에서 제시한 하류부 링크저장공간 200m를 기준으로 이상일 때와 이하일 때로 구분하여 전체 6가지 CASE에 대한 감응식 신호제어전략 적용 전 후의 효과를 평가하였다. 그 결과, 전체 네트워크 차원에서 하류부링크 저장공간 200m 이하일 때 CASE I${\sim}$III에서는 4.4%${\sim}$6.2%, 200m 이상일 때 CASE Ⅳ${\sim}$Ⅵ에서는 6.1%${\sim}$16.2%의 지체 감소 효과가 발생하였으며, 상대적으로 하류부 링크저장공간이 큰 네트워크에서 효과가 더욱 크게 발생한 것으로 분석되었다.

• 한국ITS학회 논문지
• /
• 제14권4호
• /
• pp.40-51
• /
• 2015

본 연구에서는 직각교차 4지 신호교차로를 대상으로 다양한 신호현시 순서대안을 비교하여 교차로 하류부 도로의 통과교통량 처리능력을 극대화하는 신호현시 순서대안을 분석하였다. 현시배열 대안은 동서축과 남북축 도로의 직진과 좌회전 신호현시 배치순서에 따라 총 6개로 구성하였다. 이론적 분석에 따르면 동일한 목적링크를 향하는 신호현시를 신호주기 전체에 분산배치한 현시배열 대안2(동서축:직진 후 좌회전, 남북축:좌회전 후 직진)와 현시배열 대안5(동서축:좌회전 후 직진, 남북축:직진 후 좌회전)가 나머지 4개 현시배열 대안에 비하여 작은 최대지체가 발생하는 것으로 나타났다. 즉, 현시배열 대안에 따라 교차로가 최대지체의 수용가능 여부가 변화하는 용량상태 교차로에서 효과를 나타낼 수 있다. 미시 교통시뮬레이터인 PTV VISSIM F 7.0을 이용하여 각각의 현시배열 대안을 검증한 결과 용량상태를 넘어서가나 미달한 교차로에서는 현시순서 대안의 변화에 따라 통과교통량의 변화가 매우 미미한 수준으로 나타났다. 그러나 용량상태인 평균제어지체 100초 내외의 교차로는 현시순서 대안에 따라 평균제어지체가 용량상태인 100초 안팎으로 변화하며 효과를 나타냈다. 이론적 분석결과와 동일하게 현시배열 대안2와 현시배열 대안5가 다른 현시배열 대안에 비하여 교차로 통과교통량 및 목적링크 통과교통량을 최소 3.8%에서 최대 5.1%까지 증대시킨 것으로 분석되었다.

• Coupled systems mechanics
• /
• 제7권1호
• /
• pp.43-59
• /
• 2018

The presence of the pore fluid strongly influences the reponse of the soil subjected to external loading and in many cases increases the risk of final failure. In this paper, we propose the use of a discrete beam lattice model with the aim to investigate the coupling effects of the solid and fluid phase on the response and failure mechanisms in the saturated soil. The discrete cohesive link lattice model used in this paper, is based on inelastic Timoshenko beam finite elements with enhanced kinematics in axial and transverse direction. The coupling equations for the soil-pore fluid interaction are derived from Terzaghi's principle of effective stresses, Biot's porous media theory and Darcy's law for fluid flow through porous media. The application of the model in soil mechanics is illustrated through several numerical simulations.

• 대한교통학회지
• /
• 제9권1호
• /
• pp.47-56
• /
• 1991

With respect to stochastic delays at linked signals the solid quantitative information has not been available as yet. On the basis of field data the values of "I" (variance-mean ration of flow) were related with the rate of flow. The stochastic delays with specific "I" values were obtained from the distribution of overflow queue, which were calculated by the use of Markov chains. This examination of the results led to the derivation of a simple method for calculating stochastic dclays through the introduction of "I" into Miller's model. The good agreement was shown between the model and the field. The relationships between the cycle lengths and delays were examinated in a large number of conditions with regard to degree of saturation. signal split and link length. Within the practical range of cycle length uniform delays were dominant and no critical point was found in terms of minimum, delay. In highly saturated conditions however the weight of stochastic delay is noticeable.

• 대한화학회지
• /
• 제17권4호
• /
• pp.247-255
• /
• 1973

$Li^{+},\;Na^{+},\;K^{+}, Ca^{2+},\;Ni^{2+},\;Al^{3+}$, 과 $F^{3+}$의 陽이온을 포화시킨 Wyoning montmorillonite에 acetone, methyl-ethyl ketone. diethyl ketone을 加熱用 i.r. gas cell 內에서 各各 다른 壓力아래 吸着시켜 $4000{\sim}1200cm^{-1}$에서spectra를 얻었다.두가지 형태의 C=O결합변화가$1713cm^{-1}$과 $1690cm^{-1}$ 나타났으며 이들은 陽이온의 水酸基 및 吸着水와 그리고 表面水酸基와 水素結合을 일으키는 결과로 나타났다. OH 吸收 spectra의 强度는 陽이온의 水酸基의 resonance 理論을 뒷받침해 주었다. coordinate bond를 일으키는 경향은 計算한 C=O기의 酸素의 formal charge의 크기와 잘 맞았다.

• Asia Marketing Journal
• /
• 제15권3호
• /
• pp.141-157
• /
• 2013

Managing customers based on customer equity (CE) has emerged as the most effective way of doing business because of its ability to foster profitable customer relationship management (CRM) through appropriate marketing activities. Most research studies provide conceptual and empirical evidence of the positive link between CE and firm performance. However, regarding this possibility, it has been suggested by some researchers that this link may not hold true for other firms with different firmographic factors, such as firm growth rate, size, and resources. As previous research emphasizes that marketing managers should implement a strategy based on their unique business environment, our study addresses this issue by extending the framework to a different industry setting to investigate the impact of CE on firm performance. We develop a model for examining the relationship between the firm's estimated CE and firm performance by each time period using a distributed lagged model. Then, we investigate the effect of CE on the firm's profitability using a regression analysis. Finally, even though CRM is in increasing demand and firms are focusing on the customer as an asset, we conclude that there is a limited condition for this positive effect of CE. When the life cycle was divided by growth rate, CE was shown to have a distinctive effect on profit. In the case of a high-growth stage, the effect of CE on profit is positive because of its potential customer base, whereas the effect is not significant in a low-growth stage. That is, when the business environment is saturated and the firms are no longer competing in the market, CRM may not be effective. In other words, a long-term performance orientation may not be as effective as previously believed. This research contributes to the previous literature, providing a counterintuitive suggestion that firm managers should be cautious about implementing a CRM strategy and should allocate resources properly in terms of their resource capabilities and ability depending on their situation.

• 한국소음진동공학회논문집
• /
• 제25권11호
• /
• pp.753-763
• /
• 2015

This paper proposes a decentralized robust adaptive neural network control scheme using multiple radial basis function neural networks for electrically driven robot manipulators with bounded input voltages in the presence of uncertainties. The proposed controller considers both robot link dynamics and actuator dynamics. Practically, the controller gain coefficients applied at each joint may be nonlinear time-varying and the input voltage at each joint is saturated. The proposed robot controller overcomes the various uncertainties and the input voltage saturation problem. The proposed controller does not require any robot and actuator parameters. The adaptation laws of the proposed controller are derived by using the Lyapunov stability analysis and the stability of the closed-loop control system is guaranteed. The validity and robustness of the proposed control scheme are verified through simulation results.