• Journal of KIISE:Computing Practices and Letters
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• v.8 no.4
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• pp.411-422
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• 2002

Recently, there have been active researches about the VPCS (Virtual Parallel Computing System) based on multiple agents. The PVCS uses personal computers or workstations that are dispersed all over the internet, rather than a high-cost supercomputer, to solve complex problems that require a huge number of calculations. It can be made up with either homogeneous or heterogeneous computers, depending on resources available on the internet. In this paper, we propose a new method in order to distribute worker agents and work packages efficiently on the VPCS based on the IBM Aglets. The previous methods use mainly the master-slave pattern for distributing worker agents and work packages. However, in these methods the workload increases dramatically at the central master as the number of agents increases. As a solution to this problem, our method appoints worker agents to distribute worker agents and workload packages. The proposed method is evaluated in several ways on the VPCS, and its results are improved to be worthy of close attention as compared with the previous ones.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.7B
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• pp.647-659
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• 2003

LPM(Longest Prefix Matching)searching in If address lookup is a major bottleneck of IP packet processing in the high speed router. In the conventional lookup table for the LPM searching in CAM(Content Addressable Memory) the complexity of fast update take 0(1). In this paper, we designed pipeline architecture for fast update of 0(1) cycle of lookup table and high throughput and low area complexity on LPM searching. Lookup-table architecture was designed by CAM(Content Addressable Memory)away that uses 1bit RAM(Random Access Memory)cell. It has three pipeline stages. Its LPM searching rate is affected by both the number of key field blocks in stage 1 and stage 2, and distribution of matching Point. The RTL(Register Transistor Level) design is carried out using Verilog-HDL. The functional verification is thoroughly done at the gate level using 0.35${\mu}{\textrm}{m}$ CMOS SEC standard cell library.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.11C
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• pp.1491-1497
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• 2004

The psychoacoustic model in MPEG audio layer-III (MP3) encoder is optimized for the fixed-point processing. The optimization process consists of determining the data word length of arithmetic unit and the algorithm for transcendental functions that are often used in the psychoacoustic model. In order to determine the data word length, we defined a statistical model expressing the relation between the fixed-point operation errors of the psychoacoustic model and the probability of alteration of the allocated bits doe to these errors. Based on the simulations using this model, we chose a 24-bit data path and constructed a 24-bit fixed-point MP3 encoder. Sound quality tests using the constructed fixed-point encoder showed a mean degradation of -0.2 on ITU-R 5-point audio impairment scale.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.3A
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• pp.185-196
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• 2009

SCA is proposed in order to operate various wireless systems in the single terminal platforms and uses the CORBA middleware to guarantee the platform-independence for software components. As the reconstruction demand is expanded in the software component to the logic level to many reasons, CORBA has to guarantee the independence of hardware on board. Accordingly. the characteristics depending on hardware board is ed. And the IDL-based interworking interface about the component has to be provided. In this paper, we described about local transport for guaranteeing the independency on the hardware board and the HAO Core for providing a coupling by the CORBA IDL identically with the other component. HAO produced at 2,900 logic cell size in average and provided the performance of the tens times than the software component. Through the use of HAO in the SCA-based development environment, it was naturally expanded to not only the software area but also the FPGA logic.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.11B
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• pp.685-692
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• 2007

Recent advances in wireless communications and electronics have enabled the development of low-cost, low-power, multi-functional sensors. A typical wireless sensor network (WSN) consists of a large number of sensor nodes that can measure and process data while communicating through wireless channels. In this paper, we propose a hybrid query processing (HQP) algorithm for user queries submitted to the WSN. Unlike previous algorithms that consider continuous queries only, HQP supports both continuous queries and ad-hoc queries. Specially. HQP tries to reduce energy consumption of ad-hoc queries by using query results cached at each sensor node which are created during the execution of the previous continuous query. HQP can also exploit a trade-off between energy consumption and data accuracy. We evaluate the performance of HQP under a variety of WSN configurations.

• The KIPS Transactions:PartA
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• v.13A no.3 s.100
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• pp.223-230
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• 2006

A MMORPG(Massively Multiplayer Online Role-Playing Game) is an online role-playing game in which a large number of players can interact with each other in the same world at the same time. Most of them require significant hardware requirements(e.g., servers and bandwidth), and dedicated support staff. Despite the efforts of developers, users often cite overpopulation, lag, and poor support as problems of games. In this paper, a dynamic load balancing method for MMORPGS is proposed. It tries to adapt to dynamic change of population by using dynamic map-partition method with VML(Virtual Map Layer) which consists of fields, sector groups, sectors, and cells. From the experimental results, our approach achieves about $23^{\sim}67%$ lower loads for each field server. By the modification to Virtual Area Layer, we can easily manage problems that come from changes of map data, resources' status, and users' behavior pattern.

• The Transactions of the Korean Institute of Power Electronics
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• v.14 no.1
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• pp.72-81
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• 2009

This paper presents quasi-resonant type high power factor ac power supply for atmospheric pressure plasma cleaning system adopting three phase PFC boost converter and it's control method. The presented ac power supply consists of single phase H-bridge inverter, step-up transformer for generating high voltage and three phase PFC boost converter for high power factor on source utility. Unlikely to the traditional LC resonant converter, the propose one has an inductor inside only. A single resonant takes place through the inside inductor and the capacitor from the plasma load modeled into two series capacitor and one resistance. The quasi-resonant can be achieved by cutting the switching signal when the load current decrease to zero. To obtain power control ability, the propose converter controlled by two control schemes. One is the changing output pulse period scheme in the manner of PFM(Pulse Frequency Modulation) control. On the other, to provide more higher power to load, the DC rail voltage is directly controlled by the 3-phase PFC boost converter. The significant merits of the proposed converter are the uniform power providing capability for high quality plasma generation and low reactive power in AC and DC side. The proposed work is verified through digital simulation and experimental implementation.

• Journal of Information Management
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• v.43 no.4
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• pp.49-68
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• 2012

This study analyzes the general operations of the current services and usages, and the perceptions on the service quality and satisfaction of the 480 users of the electronic information centers (EIC) in the 5 selected university libraries in Daegu and Kyoungpook area. Each libraries provide various levels of their services. Service quality is supposed to be comprised of 3 dimensions of facilities and equipments, contents, and staff. Each of three dimensions influences statistically significantly the user satisfaction of the EIC. Users are satisfied with the facilities and equipments highly. Users in each libraries show statistically different satisfactions in the dimensions of facilities and equipments, and contents, except staff dimensions. Users of each universities show different overall satisfactions on the EICs also.

• Communications of the Korean Institute of Information Scientists and Engineers
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• v.18 no.2
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• pp.4-7
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• 2000

이상에서 소개된 정보통신부 리눅스 활성화 방안을 요약하면 다음과 같다.1991년 개발된 리눅스가 최근 저비용 고효율 안정성 등의 여러가지 이점 때문에 대표적인 PC서버용 운영체제로 부각되고 있다. IBM, Intel, Sun 등 세계적인 하드웨어 및 소프트웨어 업체들이 공식적으로 리눅스 지원을 시작하면서 Windows NT에 대적하는 새로운 서버 운영체제로 부각되었고, 이에 따라 다른 여러 업체들도 리눅스 시장을 선점하기 위해 활발한 개발활동을 전개하고 있다. 본 활성화 방안은 국내에서 리눅스 활성화를 통해 다음의 목표를 달성하기 위해 마련되었다. 추진목표는 첫째, 저가격 고성능의 리눅스를 이용한 PC 보급 확산으로 인터넷 이용환경 구축 예산을 절감하고 교육정보화 등 정보화사업에 리눅스 적용을 통해 국민의 보편적 이용환경을 조성하는 데 있고, 둘째, 리눅스 기반기술 개발을 통해 소프트웨어 기술을 국제수준으로 향상시키고, 셋째, 리눅스의 보급 활성화를 통한 국내 소프트웨어 산업을 육성하는 데 있다. 구체적 추진전략은 다음과 같다. 첫째, 리눅스 한글환경 표준화 및 리눅스 기반기술 개발 등과 같은 원활한 리눅스 보급을 위한 연구개발을 추진한다. 둘째, 리눅스 환경하의 다양한 응용 개발 촉진체계를 구축한다. 셋째, 공공분야에 대한 리눅스 보급을 추진한다. 셋째, 공공분야에 대한 리눅스 보급을 추진한다. 정보화사업 추진 시 리눅스 활용을 적극 추진하고 교육정보화 사업의 기본장비로 활용하는 시범사업을 추진한다. 또한 산 학 연의 리눅스 전문가들로 리눅스 협의회를 구성하여 리눅스 보급 확산을 위한 활동을 추진하게 될 것이다. 이 과정에서 기업들의 요구사항 및 이용활성화에 대해서 협의가 이루어질 것이다. 새 천년에는 시작부터 국가간에 치열한 정보화 경쟁이 있을 것이다. 정보화 환경이 얼마나 저비용 고효율으로 잘 구축되었느냐, 그리고 정보화 인력을 얼마나 갖고 있느냐가 그러한 국제사회에서의 경쟁력을 좌우하게 될 것이다. 이러한 관점에서 리눅스의 활성화는 매우 중요하다. 본 활성화 방안이 성공적으로 수행되어 우리나라가 아시아의 리눅스 메카로 떠올라 새천년에 우리나라가 정보화 선진국에 진입하도록 정부에서는 최대의 노력을 기울일 방침이다.

• Journal of Elementary Mathematics Education in Korea
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• v.10 no.1
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• pp.21-42
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• 2006

The purpose of this study is to identify the influences of the reciprocal writing-reflection activities on the mathematical learning of the 2nd grade students by developing a class model using reciprocal writing-reflection activities method as one of the interactive application of manipulative activities, reflective thought and communication activities which are the learning principles of constructivism. We have experimented and investigated to after dividing experimental objects into two group, experimental groups and comparative group, The conclusions of this study are followings. First, reciprocal writing-reflection activities showed significant effects on mathematical achievements of the group with lower achievements in learning. Second, reciprocal writing-reflection activities positively influenced mathematical tendency of the students. Third, the students had positive attitudes in interest, desire and usefulness regarding reciprocal writing-reflection activities. And reciprocal writing- reflection activities are helpful for their reflective thinking and communication activities.