• Proceedings of the Korea Inteligent Information System Society Conference
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• 2005.11a
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• pp.415-424
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• 2005

The rapid growth of blog has caused information overload where bloggers in the virtual community space are no longer able to effectively choose the blogs they are exposed to. Recommender systems have been widely advocated as a way of coping with the problem of information overload in e-business environment. Collaborative Filtering (CF) is the most successful recommendation method to date and used in many of the recommender systems. Therefore, we propose a CF-based recommender system for bloggers in the virtual community space. Our proposed methodology consists of three main phases: In the first phase, we apply the "Interest Value" to a recommender system. The Interest Value is a quantity value about user preference in virtual community, and can measure the opinion of users accurately. Next phase, we generate the neighborhood group based on the Interest Value. In the final phase, we use the Community Likeness Score (CLS) to generate the top-n recommendation list. The methodology is explained step by step with an illustrative example and is verified with real data of a blog service provider.

• International Journal of Control, Automation, and Systems
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• v.6 no.6
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• pp.845-858
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• 2008

In this paper, we consider a terminal, linear control system with delay, subject to unknown but bounded disturbances. For this system, we consider the problem of constructing a worst-case optimal feedback control policy, which can be corrected at fixed, intermediate time instants. The policy should guarantee that for all admissible uncertainties the system states are in prescribed neighborhoods of predefined system states, at all fixed, intermediate time instants, and in the neighborhood of a given state at a terminal time instant, and the value of the cost function is the best guaranteed value. Simple explicit rules(which can be easily implemented on-line) for constructing the optimal control policy in the original control problem are derived.

• Journal of Information Technology Applications and Management
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• v.20 no.3_spc
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• pp.219-230
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• 2013

Real time accessiblity and agility in Ubiquitous-commerce is required under ubiquitous computing environment. The Research has been actively processed in e-commerce so as to improve the accuracy of recommendation. Existing Collaborative filtering (CF) can not reflect contents of the items and has the problem of the process of selection in the neighborhood user group and the problems of sparsity and scalability as well. Although a system has been practically used to improve these defects, it still does not reflect attributes of the item. In this paper, to solve this problem, We can use a implicit method which is used by customer's data and purchase history data. We propose a new clustering method of weighted preference for customer using k-means clustering and Bayesian network in order to improve the accuracy of recommendation. To verify improved performance of the proposed system, we make experiments with dataset collected in a cosmetic internet shopping mall.

• Journal of Engineering Education Research
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• v.13 no.5
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• pp.36-40
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• 2010

The vehicle oriented block box system based on the u-healthcare and the human-free guard functions is developed in this paper. We also suggested the design philosophies, ideas, and analyzed the performance of the suggested system. The developed vehicle oriented black box system has some characteristics such as; 1) detects the dangerous situation by ultrasonic sensor in advance, and stores the situation information of the neighborhood of the vehicle to the imbedded SD memory card if the dangerous situation may be occurred in the parked vehicle; 2) detects the present location and speed information of the vehicle by GPS receiver and 3-axes acceleration sensor, and stores the information to the SD memory card periodically if the vehicle is running; 3) measures the dioxide carbon in the vehicle inside using $CO_2$ sensor, and forces the ventilation motor of the vehicle to operate and maintains the driver's health if the measured level is more than standard health requirements; 4) provides the stored vehicle's operating information to the driver by GUI (Graphical User Interface) based touch LCD monitor.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.162.1-162
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• 2001

In this paper, the adaptive fuzzy system is used as an adaptive approximator for robot nonlinear dynamic. A theoretical justification for the adaptive approximator is proving that if the representive point(RP or switching function) and its derivative in sliding mode control are used as the inputs of the adaptive fuzzy system, the adaptive fuzzy system can approximate robot nonlinear dynamics in the neighborhood of the switching surface. Thus the fuzzy controller design is greatly simplified and at the same time, the fuzzy control rule can be obtained easily by the reaching condition. Based on this, a new method for designing an adaptive fuzzy control system based on sliding mode is proposed for the trajectory tracking control of a robot with unknown nonlinear dynamics.

• Proceedings of the IEEK Conference
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• 2003.11a
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• pp.321-324
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• 2003

This paper presents a novel system that analyzes and recognizes a gait based on shape context on silhouette images. The main functions of the system consist of three steps: First, the system extracts the silhouette images from galt image sequence by performing a simple pre-processing and acquires the AGM(Averaged Gait Map) by averaging them. Next. it computes the cross-correlation between the AGMs. Finally, it classifies the AGMs based on the cross-correlation using nearest neighborhood classification. The proposed system uses two cues to classify a gait: One corresponds to biometric shape cue such as body height width. and body-part proportions. The other corresponds to gait cue such as stride length and amount of arm swing. Perceptionally, the biometric cues are sailent on the double support (both legs spread and touching the ground) while the gait cues on the midstance. Through a variety of experiments, it is proved that the property of a gait is mainly influenced by gait cues than biometric cues.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.12
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• pp.2511-2518
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• 2002

Dynamic behaviors and stability of an optical disk drive coupled with an automatic ball balancer (ABB) are analyzed by a theoretical approach. The feeding system is modeled a rigid body with six degree-of-freedom. Using Lagrange's equation, we derive the nonlinear equations of motion for a non -autonomous system with respect to the rectangular coordinate. To investigate the dynamic stability of the system in the neighborhood of the equilibrium positions, the monodromy matrix technique is applied to the perturbed equations. On the other hand, time responses are computed by the Runge -Kutta method. We also investigate the effects of the damping coefficient and the position of ABB on the dynamic behaviors of the system.

• Management & Information Systems Review
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• v.20
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• pp.85-113
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• 2007

This study came up with a comparison analysis between the average results of Whole National Cooperatives and Kyonggi cooperatives from 2000 to 2005. 15 Kyonggi Agricultural Cooperatives which are nearly the same in the aspects of size and local conditions, - Songpo, Shindo, Ilsan, Jido, Migum, Dongduchon, Bucheon, Ojeong, Naksaeng, Seongnam, Suwon, Kunja, Banweol, Ansan, Suji- are selected as comparable ones while the cooperatives of Kwangmyung, Kungpo, Anyang, Euiwang represent as Kwachon neighborhood cooperatives. The analysis result proposes some desirable ideas to activate the business of local cooperatives as follows. First, the top limit of allotting profits seem to require having the lower adjustment which takes into account the interest rates. Second, the system allotting the profits in proportion to the record of the use should be improved. Third, In order to activate the business of semi-members, allotting profit system in proportion to the record of the use should be established.

• Journal of Power System Engineering
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• v.6 no.1
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• pp.96-101
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• 2002

In this paper, we address the problem of controlling an end-effector to track and grab a moving target using the visual servoing technique. A visual servo mechanism based on the image-based servoing principle, is proposed by using visual feedback to control an end-effector without calibrated robot and camera models. Firstly, we consider the control problem as a nonlinear least squares optimization and update the joint angles through the Taylor Series Expansion. And to track a moving target in real time, the Jacobian estimation scheme(Dynamic Broyden's Method) is used to estimate the combined robot and image Jacobian. Using this algorithm, we can drive the objective function value to a neighborhood of zero. To show the effectiveness of the proposed algorithm, simulation results for a six degree of freedom robot are presented.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11b
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• pp.983-988
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• 2001

Dynamic behaviors and stability of an optical disk drive coupled with an automatic ball balancer(ABB) are analyzed by a theoretical approach. The feeding system is modeled a rigid body with six degree-of-freedom. Using Lagrange's equation, we derive the nonlinear equations of motion for a non-autonomous system with respect to the rectangular coordinate. To investigate the dynamic stability of the system in the neighborhood of the equilibrium positions, the monodromy matrix technique is applied to the perturbed equations. On the other hand, time responses are computed by the Runge-Kutta method. We also investigate the effects of the damping coefficient and the position of ABB on the dynamic behaviors of the system.