• 정보처리학회논문지C
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• 제15C권5호
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• pp.409-418
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• 2008

본 논문에서는 운영체제에서 지원하는 PPP 프로그램이 없는, 즉 별도의 운영체제를 사용하지 않는 임베디드 시스템에서 글로벌스타 인공위성 모뎀을 이용하기 위한 PPP 프로그램을 작성하였다. 글로벌스타를 포함한 오브컴, 인말샛과 같은 많은 위성통신 시스템은 데이터 링크 구현을 위하여 그 자체의 인터페이스를 제공하고 있다. 글로벌스타 위성 시스템과 데이터 링크를 구현하기 위해서는 글로벌스타 위성에서 사용하는 PPP를 사용해야 한다. 따라서 본 논문에서는 임베디드 프로세서 기반의 PPP를 구현하였으며, 이와 더불어 사용자 단말 장치를 개발하였다. 사용자 단말 장치는 다양한 응용분야에 사용될 수 있도록 여러 가지 입출력 장치 및 센서를 장착하여 설계 및 실현하였다. 실험 테스트를 통하여 이와 같이 구축된 모든 시스템은 글로벌스타 데이터 링크를 통해서 잘 동작함을 확인한다.

• 한국정밀공학회지
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• 제28권9호
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• pp.1025-1031
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• 2011

Take-out robots used for handling of the plastic parts manufactured with the injection mold are usually the gantry type that consists of long and thin links, The performance of the take-out robot is determined by the speed of the motion and the positioning accuracy to grab the part out of the mold, As the speed of the robot increases the flexure in the links of the take-out robot becomes more significant and it results in more residual vibration, The residual vibration deteriorates the positioning accuracy and compels the operator to slow down the motion of the robot. The typical method to reduce the vibration in the robot requires stiffening the links and/or slowing down the robot, Vibration control could achieve the desired performance without increasing the manufacturing cost or the operation cost that would be incurred otherwise, Considering the point-to-point nature of the task to be performed by the take-out robot the time-delay command (or input) shaping filter approach would be the most effective control method to be adopted among a few available control schemes. In this paper a direct adaptive command shaping filter (ACSF) algorithm has been modified and applied to design the optimal command shaping filters for various configuration of the take-out robot. Optimal filters designed by ACSF algorithm have been implemented on a take-out robot and the effectiveness of the designed filters in terms of vibration suppression has been verified for multiple positions of the robot.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제6권5호
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• pp.1303-1315
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• 2012

In the draft of the IEEE 802.11s standard, a tree topology is established by the proactive tree-building mode of the Hybrid Wireless Mesh Protocol (HWMP). It is used for cases in which the root station (e.g., gateway) is an end point of the majority of the data connections. In the tree topology, the root or central stations (e.g., parent stations) are connected to the other stations (e.g., leaves) that are one level lower than the central station. Such mesh stations are likely to suffer heavily from contention in bottleneck links when the network has a high traffic load. Moreover, the dependence of the network on such stations is a point of vulnerability. A failure of the central station (e.g., a crash or simply going into sleep mode to save energy) can cripple the whole network in the tree topology. This causes performance degradation for end-to-end transmissions. In a connected mesh topology where the stations having two or more radio links between them are connected in such a way that if a failure subsists in any of the links, the other link could provide the redundancy to the network. We propose a scheme to utilize this characteristic by organizing the network into concentric tiers around the root mesh station. The tier structure facilitates path recovery and congestion control. The resulting mode is referred to as Tier-based Proactive Path Selection Mode (TPPSM). The performance of TPPSM is compared with the proactive tree mode of HWMP. Simulation results show that TPPSM has better performance.

• 한국콘텐츠학회논문지
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• 제14권9호
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• pp.556-566
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• 2014

목적 : 경혈, 침구 온톨로지의 연계율을 높이기 위한 연구를 시행하였다. 방법 : 혈성(효능) 용어와 치법 용어를 최소 의미 단위로 분해하여 상호 연계하였다. 결과 : 혈성(효능)과 치법의 연계가 증가함에 따라 경혈, 침구 온톨로지 간 연계성이 증가하였으며, 확장 연계되는 프로퍼티의 수와 프로퍼티 간 노드의 수도 증가하였다. 결론 : 혈성(효능) 용어와 치법 용어의 최소 의미 단위로의 연계를 통해 온톨로지의 연계율이 개선되고 이에 따라 온톨로지의 활용성이 제고될 수 있음을 알 수 있었다.

• 한국통신학회논문지
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• 제28권5B호
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• pp.427-434
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• 2003

본 논문은 TCP-Reno등의 TCP 등에서 사용되는 다른 혼잡 제어 알고리즘보다 에러가 많은 무선 환경에 더욱 강인한 향상된 TCP 혼잡 제어 알고리즘을 제안한다. 제안하는 알고리즘은 혼잡 윈도우 크기를 패킷 에러율과 현 TCP의 상태가 fast recovery 혹은 slow start 상태에 있느냐에 따라 결정한다. 시뮬레이션을 통해 제안하는 알고리즘의 유효성을 보여 주며, 여러 TCP 혼잡 제어 알고리즘들과 혼잡 윈도우 크기와 효율과 같은 성능 지표 관점에서 비교하였다. 제안하는 알고리즘은 다른 알고리즘보다 높은 PER하에서는 높은 효율을 가지며, 낮은 PER하에서는 비슷한 효율을 가진다.

• 한국경영과학회지
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• 제34권4호
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• pp.123-138
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• 2009

This study examined the first- and second-best pricing by stable dynamics in congested transportation networks. Stable dynamics, suggested by Nesterov and de Palma (2003), is a new model which describes and provides a stable state of congestion in urban transportation networks. The first-best pricing in user equilibrium models introduces user-equilibrium in the system-equilibrium by tolling the difference between the marginal social cost and the marginal private cost on each link. Nevertheless, the second-best pricing, which levies the toll on some, but not all, links, is relevant from the practical point of view. In comparison with the user equilibrium model, the stable dynamic model provides a solution equivalent to system-equilibrium if it is focused on link flows. Therefore the toll interval on each link, which keeps up the system-equilibrium, is more meaningful than the first-best pricing. In addition, the second-best pricing in stable dynamic models is the same as the first-best pricing since the toll interval is separately given by each link. As an effect of congestion pricing in stable dynamic models, we can remove the inefficiency of the network with inefficient Braess links by levying a toll on the Braess link. We present a numerical example applied to the network with 6 nodes and 9 links, including 2 Braess links.

• ETRI Journal
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• 제34권1호
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• pp.122-125
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• 2012

A video signal through a high-density optical link has been demonstrated to show the reliability of optical link for high-data-rate transmission. To reduce optical point-to-point links, an electrical link has been utilized for control and clock signaling. The latency and flicker with background noise occurred during the transferring of data across the optical link due to electrical-to-optical with optical-to-electrical conversions. The proposed synchronization technology combined with a flicker and denoising algorithm has given good results and can be applied in high-definition serial data interface (HD-SDI), ultra-HD-SDI, and HD multimedia interface transmission system applications.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2002년도 ICCAS
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• pp.94.4-94
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• 2002

Traditional control systems that consist of sensors, actuators and a controller centralized and connected with point-to-point links, have become distributed because of their performance limits and maintenance problems. Sensors and actuators are changed to smart devices having a processor and these devices and controllers are connected with fieldbuses such as Profibus, FIP, CAN, LonWorks and so on. Because they are distributed, it takes any delay to transmit data from sensor to controller and data from controller to actuator according to network characteristic. Also, the execution times of tasks in a node are not regular and depend on the node characteristic and the number of tasks and so on...

• Child Health Nursing Research
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• 제10권1호
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• pp.37-47
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• 2004

Purpose: This study aimed to identify the alcohol drinking pattern of parents and to analyze drinking related factors in problem drinking among adolescent's parents. Method: This study was conducted through a structured questioning from November 5th to 22th in 2002. Those are 2,522 parents of the students of the 1st and 2nd grade who were selected randomly among 26 middle and high schools located in Socho-gu, Seoul. Data was analyzed using SAS program that included descriptive statistics, Chi-square test, and multiple logistic regression analysis. Result: 1. For frequency of drinking, 33.1％ of the subjects responded to drink two-four times a month, 26.0％ drink more than two times a week. 2. For the amount of drinking, 29.6％ drink one or two glasses while 9.4％ drink over ten glasses at a time. 3. The mean AUDIT score was 8.27 7.02(score of range: 0- 40). 4. Based on AUDIT score, drinkers with less than eight point from AUDIT(normal group) were 55.1％, from more than eight point to less than twelve point from AUDIT(problematic drinker) were 16.3％, and more than twelve point from AUDIT(alcohol abuse and dependency) were 28.6％. 5. Based on more than twelve point from AUDIT, female(mother), high school and, have religion, housekeeper were the significantly higher score than counter parts. Conclusion: Alcohol drinking pattern and level of drinking of their parents links to their children's drinking and results in family, social, and national loss. Active prevention is needed. Specially, pertinent education about drinking and public education for mothers who are housekeepers should be carried out with concentrated intervention programs for the problematic drinker so alcohol abuse and dependency can be reduced.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1987년도 한국자동제어학술회의논문집(한일합동학술편); 한국과학기술대학, 충남; 16-17 Oct. 1987
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• pp.915-920
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• 1987

When a task requires two robot arms to move in a cooperative manner sharing a common workspace, potential collision exists between the two robot arm . In this paper, a novel approach for collision-free trajectory planning along paths of two SCARA-type robot arms is presented. Specifically, in order to describe potential collision between the links of two moving robot arms along the designated paths, an explicit form of "Virtual Obstacle" is adopted, according to which links of one robot arm are made to grow while the other robot arm is forced to shrink as a point on the path. Then, a notion of "Coordination Chart" is introduced to visualize the collision-free relationship of two trajectories.of two trajectories.