• Proceedings of the Korea Society for Simulation Conference
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• 2001.05a
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• pp.133-133
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• 2001

무선 근거리 지역망(Wireless LAN;WLAN) 환경에서 다중 채널을 이용하여 실시간 서비스를 제공하기 위한 매체 접근제어 계층에서의 채널의 사용 구간 할당 방법을 제안하고, 컴퓨터 모의 실험을 통하여 제한된 방식의 실시간 서비스 지원 성능과 채널의 사용 효율을 분석한다. 제안한 채널 사용 구간 할당 방안은 개선된 매체 접근 제어 프로토콜 RICH-DP (Receiver-Initiated Channel-Hopping with Dual Polling)를 바탕으로 한다. 무선 환경에서 RTS-CTS를 사용하는 프로토콜은 SRMA, MACA, MACAW, IEEE 802.11, FAMA 등이 있다. 최근에 단일 채널을 환경에서 RICH(Receiver Initiated Channel-Mopping) 프로토콜이 제안되었다. RICH는 충돌 회피를 위해서 경쟁 구간에서 충돌 감지(carrier sensing)을 사용한다. RICH는 제한된 어플케이션에 국한되는 단절이 있다. 반면에 RICH-DP는 다중 채널 환경에서 충돌 감지와 특별한 코드(spreading code) 할당 없이 일반화된 충돌 회피를 제공한다. 실시간 서비스를 이용하자 차는 단말들로 하여금 RICH-DP를 사용하여 서비스를 제공할 때, 대역폭에 대한 정보를 AP(Access Point)로 전송토록 함으로써 비경쟁 구간에서 뿐 아니라, 경쟁구간에서도 높은 채널 효율이 얻어질 수 있도록 하고 있다. 제한된 방안의 성능 평가를 위한 모의 실험은 OPNET를 이용하여 실시간 서비스 데이터를 7개의 상태 천이를 갖는 VBR 소스로 모델링하고 비동기 트래픽들은 Poisson 소스로 모델링하여 실시간 서비스 단발들의 이용 대역폭과 채널 처리율과 시스템 지연시간을 성능 평가 인자로 하여 수행하였다. 논문에서 제한된 방법을 적용한 개선된 RICH-DP을 모의 실험을 통하여 분석한 결과 기존의 제한된 RICH-DP는 실시간 서비스에 대한 처리율이 낮아지며 서비스 시간이 보장되지 못했다. 따라서 실시간 서비스에 대한 새로운 제안된 기법을 제안하고 성능 평가한 결과 기존의 RICH-DP보다 성능이 향상됨을 확인 할 수 있었다.

• Proceedings of the Safety Management and Science Conference
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• 2007.04a
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• pp.113-123
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• 2007

Through so that accident of semiconductor industry deduces unsafe factor of the person center on unsafe behaviour that incident history and questionnaire and I made starting point that extract very important factor. It served as a momentum that make up base that analyzes factors that happen based on factor that extract factor cause classification for the first factor, the second factor and the third factor and presents model of human error. Factor for whole defines factor component for human factor and to cause analysis 1 stage in human factor and step that wish to do access of problem and it do analysis cause of data of 1 step. Also, see significant difference that analyzes interrelation between leading persons about human mistake in semiconductor industry and connect interrelation of mistake by this. Continuously, dictionary road map to human error theoretical background to basis traditional accidental cause model and modern accident cause model and leading persons. I wish to present model and new model in semiconductor industry by backbone that leading persons of existing scholars who present model of existent human error deduce relation. Finally, I wish to deduce backbone of model of pre-suppression about accident leading person of the person center.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.12
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• pp.53-62
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• 2005

This paper presents an interface configuration between the Access Point(AP) of Wibro and Radio Over Fiber(ROF) transceivers for the wireless broadband internet system. The wireless internet could provides 60km/h mobility and 50Mbps IP based data services for each mobile terminal. Thus, low cost of each cell is inevitably required. This paper suggests an interface configuration between AP and Passive Integrated Picocell(PIP) involving ROF links. Characteristics of a typical Fabry-Perot ROF link and a PIP using a passive Electro-Absorption Modulator(EAM) are described and measured for wireless internet applications. In addition, results of RF coverage of a PIP have been shown.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.10
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• pp.23-32
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• 2007

This paper proposes a reconfigurable parallel processor architecture which can efficiently implement various multimedia applications, such as 3D graphics, H.264/H.263/MPEG-4, JPEG/JPEG2000, and MP3. The proposed architecture directly connects memories and processors so that memory access time and power consumption are reduced. It supports floating-point operations needed in the geometry stage of 3D graphics. It adopts partitioned SIMD to reduce hardware costs. Conditional execution of instructions is used for easy development of parallel algorithms.

• Journal of Magnetics
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• v.2 no.3
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• pp.96-100
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• 1997

A spin valve structure of NiO(40 nm)/Co(2 nm)/Cu(2.6 nm)/Co(x nm)/Ta(5 nm) has been investigated for the application of magnetic random access memory (MRAM). The spin valve structure exhibited very large difference in the coercivities between pinned and free layers, a relatively high GMR ratio, and a low free layer coercivity. The spin valves were prepared by sputtering and were characterized by dc 4-point probe, and VSM. The spin valves with combined free layer exhibited a maximun GMR ratio of 10.4% with a free layer coercivity of about 82 Oe. The spin valves with a single 10 nm thick a-CoNbZr free layer exhibited a GMR ratio of about 4.3% with a free layer coercivity of about 12 Oe. The GMR ratio of the spin valves increased by addition of Co between Cu and a-CoNbZr. It has been confirmed that the coercivity of free layer can be decreased by increasing the thickness of a-CoNbZr. It has been confirmed that the coercivity of free layer can be decreased by increasing the thickness of a-CoNbZr layer without losing the GMR ratio substantially, which was mainly due to high resistivity of the amorphous "layers".

• Journal of the Korea Society of Computer and Information
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• v.21 no.1
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• pp.65-72
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• 2016

Network virtualization is an emerging technology for solving the rigidity of the physical network infrastructure. The innovative technique virtualizes all resources in the network, including the network links and nodes, and provides a number of virtual networks on a single network infrastructure. In order to realize a virtual network, a thorough and complete monitoring of all resources in the network should be performed firstly. OpenFlow is an open source stack for network virtualization. However, it is impossible to apply OpenFlow to AP-based legacy wireless LAN environment because OpenFlow targets ethernet-based LAN environment. In this paper, we implement an adaptor-styled virtual switch for AP-based wireless LAN through customizing the Open vSwitch which is a virtual switch of OpenFlow. The evaluation test results show that the implemented OpenFlow stack operates successfully. The implemented OpenFlow stack can now be plugged immediately in existing AP-based wireless LAN environment and plays network resource monitoring. In the future, we can develop wireless LAN virtualization applications on the wireless OpenFlow stack.

• Journal of Korean Society of Archives and Records Management
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• v.7 no.1
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• pp.145-170
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• 2007

Unlike paper records, accessing electronic records needs to be supported by specific combination of hardware and software. The electronic records have longer life span than the storage media, hardware, software and the formats that were used for the production of such records. Because the quality of electronic record can become deteriorated as time goes on, we need to have appropriate mechanisms to secure the long-term preservation and access to the digital information at a certain point in the future. Based on this reality, this study proposes the functions and the development method of the format registry, which efficiently supports the preservation strategy such as migration and emulation, collecting and managing technical information elements. These elements consist of the foundation of the long-term preservation of the electronic records.

• Korean Journal of Construction Engineering and Management
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• v.16 no.6
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• pp.92-100
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• 2015

This paper examines the extent of China's market liberalization in the construction market seen through the point of view of WTO agreements and Korea-China FTA. Since the environment set by these agreements form the institutional background that Korean firms must work with to successfully access the market, the Korean government must work to reduce Chinese barriers as much as possible through international negotiations on these agreements. The paper sets out three goals for negotiations and the appropriate agreements and fora the government can use to advance these goals.

• Journal of Communications and Networks
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• v.18 no.3
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• pp.420-428
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• 2016

In this paper, we investigate the scheduling and power allocation for coordinated multi-point transmission in downlink long term evolution advanced (LTE-A) systems, where orthogonal frequency division multiple-access is used. The proposed scheme jointly optimizes user selection, power allocation, and modulation and coding scheme (MCS) selection to maximize the weighted sum throughput with fairness consideration. Considering practical constraints in LTE-A systems, the MCSs for the resource blocks assigned to the same user need to be the same. Since the optimization problem is a combinatorial and non-convex one with high complexity, a low-complexity algorithm is proposed by separating the user selection and power allocation into two subproblems. To further simplify the optimization problem for power allocation, the instantaneous signal-to-interference-plus-noise ratio (SINR) and the average SINR are adopted to allocate power in a single cell and multiple coordinated cells, respectively. Simulation results show that the proposed scheme can improve the average system throughput and the cell-edge user throughput significantly compared with the existing schemes with limited feedback.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.3B
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• pp.260-267
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• 2011

Wireless Local Area Network (WLAN) is recently become popular on the internet since we can download and transfer mass data through it. However, transferring data with distances over 100m often causes some troubles. When downloading mass data from moving vehicles such as cars, jeeps, tanks, etc., if the download process from the first AP (Access Point) is not completed then we have to re-start this process from the second AP (from 0%). Therefore, the question is how to maintain the data we have received from the first AP, and then continuously download remaining data from the next APs in a battlefield environment. In this paper, we propose an effective method for receiving mass data separately from the mobile receive nodes in a Delay Tolerant Network (DTN). We carried on an experiment and evaluation by simulation; these simulation results are provided to show the proposed information delivery scheme performance.