• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.125-130
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• 2001

Skilled typists can type characters or words without looking at keyboard, relying on the finger's relative position. If the relative positions of the fingers can be identified, a virtual keyboard may be accomplished by applying the concept of "DataGlove" or "FingerRing". The virtual keyboard may be efficient as a new mobile input device supporting QWERTY keyboard layout. For the purpose of investigating skilled typing pattern, in this paper the touch-positions of the fingers are measured with a touchscreen while five skilled typists type a long sentence. From these measurements it can be observed that the groups of touch-positions are classified into alphabet characters. Though there are some overlapped groups we can find constant distances capable of being discriminated among the groups from investigation of the change of touch-position for touch-time. Based on the analysis, the prediction algorithm of the constant distance is proposed and evaluated, which is useful for realization of a portable virtual keyboard.le virtual keyboard.

• Journal of Communications and Networks
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• v.8 no.4
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• pp.432-441
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• 2006

As the community antenna television (CATV) networks becomes ubiquitous, instead of constructing an entirely new broadband network infrastructure, it has emerged as one of the rapid and economic technologies to interconnecting heterogeneous network to provide broadband access to subscribers. How to support ubiquitous real-time multimedia applications, especially in a heavy traffic environment, becomes a critical issue in modern CATV networks. In this paper, we propose a time guaranteed and efficient upstream minislots allocation algorithm for supporting quality-of-service (QoS) traffic over data over cable service interface specification (DOCSIS) CATV networks to fulfill the needs of realtime interactive services, such as video telephony, video on demand (VOD), distance learning, and so on. The proposed adaptive fast expansion algorithm and the loading statistics with dynamic swapping algorithm have been shown to perform better than that of the multimedia cable network system (MCNS) DOCSIS.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2010.06a
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• pp.155-163
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• 2010

최근 PDA, 휴대폰과 같은 모바일 기기 및 GPS와 같은 무선 통신 기술의 발달로 인하여 위치 기반 서비스의 이용이 확산되었다. 하지만 이러한 서비스는 사용자가 도로 네트워크에서 이동하면서 자신의 위치정보를 통해 LBS 서버에 질의를 요청하기 때문에, 심각한 개인 정보 누출의 위협이 될 수 있다. 따라서 모바일 사용자의 안전하고 편리한 위치기반 서비스 사용을 위한 개인 정보 보호 방법이 필요하다. 이를 위해 본 논문에서는 도로 네트워크 거리를 고려한 사용자 정보 보호를 지원하는 cloaking 영역 설정 기법을 제안한다. 제안하는 기법은 도로 네트워크에서 효율적이고 안전한 위치기반 서비스를 지원하기 위하여, 도로 네트워크의 거리를 고려하여 cloaking 영역을 설정한다. 마지막으로 성능평가를 통해서 제안하는 기법이 cloaking 영역 및 서비스 시간 측면에서 기존 연구보다 우수함을 보인다.

• Journal of Institute of Control, Robotics and Systems
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• v.9 no.9
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• pp.720-726
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• 2003

A virtual keyboard may be efficient as a new mobile input device supporting QWERTY keyboard layout. As a preliminary study for developing a virtual keyboard, the typing pattern of a skilled human is investigated. In the study the touch-positions of the fingers are measured with a touchscreen while five skilled typists perform typing of long sentences. From these measurements it can be observed that the groups of touch-positions are classified into alphabetic characters. Though there are some mismatches, we can find constant distances capable of being discriminated among the groups. Based on the analysis the prediction algorithm of the constant distance is proposed and evaluated, which is useful for realization of a portable virtual keyboard.

• Journal of the Korea Society of Computer and Information
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• v.22 no.12
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• pp.17-25
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• 2017

In this paper, we have implemented a low-cost mobile robot supporting the person tracking by detection using RGB-D cameras and ROS(Robot Operating System) framework. The mobile robot was developed based on the Kobuki mobile base equipped with 2's Kinect devices and a high performance controller. One kinect device was used to detect and track the single person among people in the constrained working area by combining point cloud data filtering & clustering, HOG classifier and Kalman Filter-based estimation successively, and the other to perform the SLAM-based navigation supported in ROS framework. In performance evaluation, the person tracking by detection was proved to be robustly executed in real-time, and the navigation function showed the accuracy with the mean distance error being lower than 50mm. The mobile robot implemented has a significance in using the open-source based, general-purpose and low-cost approach.

• Journal of the Korean Society for Railway
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• v.3 no.3
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• pp.131-138
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• 2000

The design of current collection system of high speed train requires the fundamental understandings for the dynamic characteristics of catenary system and pantograph. The stiffness of catenary system of high speed train has the varying characteristics for the change of contact point with pantograph, since the supporting pole and hanger make the different boundary conditions for the up-down stiffness of a trolley wire. The variation of stiffness results in Mathiue equation, which characterizes the stability of the system. However, the two-term variation of the stiffness due to span length and hanger distance cannot be solved analytically. In this paper, the stiffness variations are calculated and the physical reasoning of linear model and one term Mathieu equation are reviewed. And the numerical analysis for the two-term variation of the stiffness is done for the several design parameters of pantograph.

• Proceedings of the KSME Conference
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• 2000.04a
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• pp.523-528
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• 2000

In this paper, the new type biped walking robot which is composed of the minimum number or links just for walking and its appropriate gaits are proposed. The proposed new gaits for this robot are four-crossing, crawling, standing and turning gait. In designing the biped robot we propose the Performance Index which means the needed torque per a moving distance and generate foot trajectories by $3^{rd}$ order spline Interpolation. Among those, numerically we find the optimal conditions which minimize the Performance Index. Dynamically stable walking of the biped robot is realized by satisfying the stability condition of ZMP(zero moment point), which is related to maintaining the ZMP within the region of the supporting foot during the s1n91e leg support phase. We determine the region of mass center from the stability condition of ZMP and plan references which track the mass conte. trajectory of constant velocity. Finally we implement the gaits statically tracking the planned trajectories using PD control method.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.11
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• pp.507-510
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• 1997

In this paper, we proposed force reflection method using joystick or controlling rehabilitation assisting mobile robot. We defined reflected orce equation as two terms. One is distance between mobile robot and obstacle, the other is speed of rehabilitation assisting robot. And we found the each gain value which guarantees stable navigation of robot. And we experimented simulation with simulation program supporting virtual 2-D map. Through the experiments, we confirmed force reflection algorithm is efficient when controlling rehabilitation assisting robot.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.12
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• pp.3149-3165
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• 2013

Content based image retrieval is increasingly gaining popularity among image repository systems as images are a big source of digital communication and information sharing. Identification of image content is done through feature extraction which is the key operation for a successful content based image retrieval system. In this paper content based image retrieval system has been developed by adopting a strategy of combining multiple features of shape, color and relevance feedback. Shape is served as a primary operation to identify images whereas color and relevance feedback have been used as supporting features to make the system more efficient and accurate. Shape features are estimated through second derivative, least square polynomial and shapes coding methods. Color is estimated through max-min mean of neighborhood intensities. A new technique has been introduced for relevance feedback without bothering the user.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2002.05a
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• pp.44-47
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• 2002

In order to make a doubly curved sheet metal effectively, a sheet metal forming process has been developed by adopting the flexibility of the incremental forming process and the principle of bending deformation which causes slight deformation to thickness. The developed process is an unconstrained forcing process with no holder. For this study, the experimental equipment is set up with the roll set which consists of two pairs of support rolls and one center roll. In the experiments using aluminum sheets and FEM simulation, it is found that the curvature of the formed sheet metal is determined by controlling the distance between supporting rolls in pairs and the forming depth of the center roll. The FEM simulation of the forming process using the roll set along the one path shows the distributions of the curvatures in two directions along the path, and gives information about the characteristics of the proposed forming process.