• Journal of the Korean Ceramic Society
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• v.30 no.11
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• pp.967-973
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• 1993

The effect on the hydration of cement was that Cu and Pb reacted with alkali to form soluble hydrates at theinitial stage and then there followed a slow reaction forming insoluble metal hydroxides. These hydroxides were deposited on the surface of cement particles providing a barrier against further hydration. But as a slow reaction continued, the insoluble layers were eventually destroyed and the hydration reaction resumed. Thereafter, another retardation occured by restricting the polymerization of silicates, shown by FT-IR spectroscopy analysis. In the case of Cr, as its reaction with cement caused H2O, the coordinator of Cr complex, to replace or polymerize with OH-, the formation of Cr complex promoted the leakage of OH- and increased the heat of dissolution. So the total heat evolution during hydration was larger than that in the case of Pb or Cu. The retarding effect of heavy metal ions was in the order Pb>Cu>Cr.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.50 no.8
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• pp.365-372
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• 2001

This paper presents a new protection concept to achieve the adaptive optimal function by introducing the multi-agent system technology. Making each relay an agent which consists of relay agent module and coordinator module, each agent works autonomously to improve protection capability by cooperating with other agents. It is applied to the overcurrent protection system of the industrial power system in order to show the feasibility of the proposed methodology.

• Proceedings of the Korean Information Science Society Conference
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• 2003.10a
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• pp.382-384
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• 2003

분산 시스템 상에서 공유되는 정보와 노드들의 동기화를 위하여 코디네이터를 선출하여 하부작업을 다른 노드에 할당하거나 분산된 노드 관리에 사용한다. 코디네이터 선출 알고리즘은, 분산된 노드들 간의 sing-point-of-failure를 피하여 동적으로 코디네이터를 선출하여 코디네이터 부재 시의 시스템의 상태와 기능을 복귀시키게 된다. 본 논문에서는 기존의 코디네이터 선출 알고리즘의 문제점을 보안하기 위하여 fail이 존재하는 네트워크상에서 사용 가능한 안정성 있는 효과적인 코디네이터 선출 알고리즘을 제안하고 실험을 통해 코디네이터 선출과 합병에 걸리는 시간을 측정한다.

• Korean System Dynamics Review
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• v.11 no.4
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• pp.5-23
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• 2010

The competition between hospitals has become an issue for many hospitals because of the sudden increased number of health providers. As the marketing or customer management have become important factors as means of competition, a number of hospital have been considered or already adopted the coordination system. A system dynamics model is developed to see the effect of the hospital coordination system. This paper after briefly explaining the structure of the system dynamics model, discusses the roles of the hospital coordination system with examples. The system dynamics model quantifies through simulations the process of effects of coordination system on the number of customers, productivities of employees (nurses and doctors), and finally the financial status. As a conclusions of the simulations and their analysis, it is concluded that coordination system could be more effective than the investment to the facilities. Since the study is based on only one hospital case, it is limited. However, it explains the mechanism of the coordination system quantitatively as well as qualitatively.

• 한국정보통신설비학회:학술대회논문집
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• 2008.08a
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• pp.249-252
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• 2008

This paper presents a new dynamically adaptable polling scheme for efficient support of real-time traffic over an IEEE 802.11 wireless LAN network. The poll scheduling plays an important role in IEEE 802.11 PCF. However, the current version of the polling list management scheme proposed in the IEEE802.11 standard is inefficient when a variable number of mobile stations have variable packets to transmit. If Point Coordinator has an exact information on the station status, it is possible to efficiently perform polling. In this thesis, we suggest an adaptable polling scheme to meet requirements of the stations. In our scheme, each station transmits packets including a piggyback information to inform that it wants to receive a poll in the next polling duration. Simulation results indicate that our scheme may reduces the packet discard ratio and real-time packet transfer delay.

• Journal of the Korean Institute of Landscape Architecture International Edition
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• no.2
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• pp.206-209
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• 2004

A requirement of park management is to transfer the focus from emphasizing the management of public materials to providing services to visitors. Therefore, it has become indispensable to create a scheme in which residents can take management initiative. At this time, we look at Hyogo Prefectural Arimafuji Park, which encourages citizen management participation, and try to understand their system and project contents. For an initial scheme, we identify 4 elements that promoted subjective participation in a council style scheme; 1. to begin activities at the earliest possible time before opening the park, 2. to coordinate with expert(s) who take a neutral position, 3. to have places available where participants can debate on an equal footing, and 4. to plan the project while feeding back actual results.

• Journal of Korea Multimedia Society
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• v.12 no.12
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• pp.1769-1777
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• 2009

With the advent of the ubiquitous technology age, the progress of network technology has enabled a robust sensor communication, not just in cities, but also in poor surroundings such as deserts, polar regions, or underwater environments. In this paper, we propose a Multiple Acknowledgement (MA) technique to replace the conventional Automatic Repeat request (ARQ) technique. The MA mechanism is to send an Ack to many receivers simultaneously. The CH (master, coordinator) of the unit cluster broadcasts a Beacon frame where Ack information of the previously transmitted data is included. This technique can reduce the number of transmissions and overhead significantly. The proposed technique is a scheme improving the efficiency of an underwater sensor network where the uplink data transmission is the mainstream. The Performance of the ARQ, Block Ack, Pervasive Block Ack and the proposed method were compared with one another and analyzed. The proposed method showed significant performance improvement as compared with the ARQ, BA, and PBA in its channel efficiency.

• Proceedings of the Korea Information Processing Society Conference
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• 2015.10a
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• pp.293-296
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• 2015

오늘날 차량은 고성능화 및 이용자의 편의를 증진시키기 위하여 다양한 전자장비가 탑재 되고 있다. 이러한 전자장비들을 효율적으로 제어하기 위하여 신뢰성이 입증된 CAN(controller Area Network)이 보편적으로 적용된다. 또한 수신만 가능한 노드(node)는 기존시스템에 추가가 가능하지만 송 수신을 항수 있는 노드를 추가 하는 경우에는 전체 시스템을 변경 시스템을 변경 시스템을 변경해야 하는 경우가 발생할 수 있다. 이러한 특징을 해결하기 위하여 본 논문에서는 CAN 코디네이터(Coordinator)라는 새로운 컴포넌트를 제안하고 이를 기반으로 긴급메시지에 대한 전송지연 개선 및 플러그 앤 플레이 기능을 가능케하는 새로운 CAN 프레임워크를 제안한다.

• Journal of the Korea Society of Computer and Information
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• v.24 no.9
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• pp.59-67
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• 2019

The service composition based on Service-Oriented Architecture(SOA) can make us view various machines or its functionalities in the Web or Internet-of-Things environment as 'service', and efficiently create new value-added services that users want by compositing different services if there is no service to satisfy the client. The service composition problem with respect to behavioral descriptions deals with the automatic synthesis of a coordinator service that controls a set of services to reach a goal state. Despite its importance, however, solving the service composition problem with only partial observations remains to be doubly exponential in the number of variables in service descriptions, rendering any attempts to compute an exact solution for modest size impractical. Toward this challenge, in this paper, we propose novel approximation-based approaches using abstraction methods. We empirically validate that our proposals can solve realistic problems efficiently.

• Journal of the Korea Society of Computer and Information
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• v.24 no.3
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• pp.1-9
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• 2019

This paper presents three potential risks in an environment that simultaneously performs the garbage collection and wear leveling in NAND flash memory. These risks may not only disturb the lifespan improvement of NAND flash memory, but also impose an additional overhead of page migrations. In this paper, we analyze the interference of garbage collection and wear leveling and we also provide two theoretical considerations for lifespan prolongation of NAND flash memory. To prove two solutions of three risks, we construct a simulation, based on DiskSim 4.0 and confirm realistic impacts of three risks in NAND flash memory. In experimental results, we found negative impacts of three risks and confirmed the necessity for a coordinator module between garbage collection and wear leveling for reducing the overhead and prolonging the lifespan of NAND flash memory.