• The Journal of Korean Institute of Communications and Information Sciences
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• v.37C no.10
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• pp.894-900
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• 2012

Indoor wireless positioning system uses ranging information of beacons in order to precisely estimate a tag location. To estimate distance between each beacons and tag, the system calculates arrival time of a tag pulse with clock of each beacon including independent clock offset. This clock offset seriously affects the performance of ranging and positioning. We propose in this paper a clock offset compensation method to solve this problem. To verify the performance of the proposed method, we simulated location estimation with random clock offset between -1,000ppm and 1,000ppm, and the result shows that the proposed scheme effectively solves the clock offset problem.

• The Transactions of the Korea Information Processing Society
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• v.4 no.7
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• pp.1788-1796
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• 1997

In this paper, we propose a new connection admission control(CAC) algorithm for traffic control in ATM network in which traffic estimation is performed based on user-specified parameters at every moment of connection request or connection release by recursive formula which makes real-time calculation possible. And traffic estimation using cell flow measurement is carried out when the number of connectioned calls does not change during a measurement reflection period. Performance analysis of the proposed method is carried out using several aspects for homogeneous and heterogeneous bursty traffic. The results showed that the proposed CAC method revealed better performance, than conventional CAC method for burst model in both utilization and QoS point of view.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.12C
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• pp.181-189
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• 2001

In this thesis, a policing algorithm is proposed, which is one of the traffic management function in ATM networks. The proposed algorithm minimizes CLR(Cell Loss patio) of high priority cells and solves burstiness problem of the traffic caused by multiplexing and demultiplexing process. The proposed algorithm has been implemented with VHDL and is divided into three parts, which are an input module, an UPC module, and an output module. In implementation of the UPC module\`s memory access, memory address is assigned according to VCI\`s LSB(Lowest Significant Byte) of ATM header for convenience. And the error of VSA operation from counter\`s wrap-around can be recovered by the proposed method. ANAM library 0.25 $\mu\textrm{m}$ and design compiler of Synopsys are used for synthesis of the algorithm and Synopsys VSS tool is used for VHDL simulation of it

• Journal of Korea Society of Digital Industry and Information Management
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• v.9 no.4
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• pp.127-134
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• 2013

While there are many services that can check current traffic condition and application program such as bus arrival alarm are developed, since it only provide simple alarm and check level of information, it is still insufficient in many senses. Therefore, the program that try to develop in this study is the system that predict arrival time to destination and inform the bus passengers by applying real time traffic information. The system developed related to this study is still very inadequate. In the system developed in this thesis, when the user input the current bus number and destination using smart-phone, relevant server acquire the bus route information from bus information DB, and analyze real time traffic information based on the information from traffic information DB, and inform customer of expected arrival time to destination. In this thesis, traffic congestion can be eased off and regular operation of public transportation can be improved with reliable destination arrival alarm. Also, it is considered that pattern of bus users can be analyzed by using these information, and analyzing average transport speed and time of public transportation, travel time depending on various situation can give a boost to study related to transportation information and its development.

• Journal of the Korea Society for Simulation
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• v.27 no.1
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• pp.39-49
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• 2018

An SLBM (submarine-launched ballistic missile) seriously threatens the national security due to its stealthiness that makes it difficult to detect in advance. We consider a destroyer deployment optimization problem for effectively detecting an SLBM. An optimization model is based on the two-person zero-sum game in which an adversary determines the firing and arriving places with an appropriate trajectory that provides a low detection probability, and we establish a destroyer deployment plan that guarantees the possibly highest detection probability. The proposed two-person zero-sum game model can be solved with the corresponding linear programming model, and we perform computational studies with a randomly generated area and scenario and show the optimal mixed strategies for both the players in the game.

• Journal of the Korea Convergence Society
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• v.12 no.3
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• pp.99-106
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• 2021

This study aims at analyzing the web sites for 2020 art college graduation exhibitions to derive implications that should be considered for future online exhibitions. Fifteen web sites for graduation exhibitions of domestic visual design majors will be selected to analyze the usability of the web sites in the stages of arrival-search-appreciation-communication. The spread of online exhibitions accelerated by the coronavirus pandemic presents issues that were not covered in offline exhibitions. Based on the commonalities and peculiarities of graduation exhibitions by college, implications for mature and rational graduation exhibitions will be suggested.

• Journal of Practical Engineering Education
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• v.13 no.3
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• pp.491-496
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• 2021

In this thesis, we intend to use CCTVs installed in existing parking lots to understand the current status of parking lots and provide real-time information to users through Android applications. It describes how to set the ROI in the parking area using YOLO V3 and how to provide the number of vacancies that change in real time through the set ROI, and describes how to link CCTV-server-user using IMAGE ZMQ and FIREBASE. The user can know the real-time situation of the parking lot near the destination before arriving through the application and can come up with various measures accordingly.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.22 no.1
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• pp.51-58
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• 2022

This paper proposes new measures to aid the uses of pubic transport buses by visually impaired people. Many visually impaired people have difficulty using public buses, but current guidance systems and braille blocks are not useful enough, according to a national survey(2017). In this paper, we develop a system with three functions that help to increase the bus accessibility and mobility of visually impaired people: (1)bus reservation using smart phone applications, (2)arrival notification, and (3)wireless bus stop button using Beacon. Experiments have confirmed that our system supports bus reservation, boarding and getting off the bus efficiently.

• Journal of the Korea Society for Simulation
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• v.19 no.4
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• pp.89-98
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• 2010

In the heterogeneous system of various wired or wireless network with IP-based backbone, the continuities of agreedon QoS for multimedia services should be guaranteed regardless of network types and terminal mobility through seamless vertical handover. This paper proposes a QoS provisioning mechanism called D-ISHO which guarantees the continuities of agreed-on QoS and seamless for multimedia services by considering both such characteristics as delay, loss rate and jitter per each service and such status as available band-width, call arrival rate and data transmission rate during the vertical handover. Simulation is done for performance analysis with the measure of handover failure rate and packet loss rate.

• Annual Conference of KIPS
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• 2009.04a
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• pp.1348-1351
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• 2009

패킷 재배치(packet reodering)는 전송한 패킷의 순서가 처음과 다르게 뒤섞여 수신지에 도착하는 현상을 의미한다. 패킷 재배치는 불필요한 재전송이나 불필요한 혼잡 제어를 수행하여 TCP의 성능을 저하시킨다. 패킷 재배치에 의한 TCP 성능 저하를 막기 위해 다양한 접근 방법이 소개되었다. TCP-DAD는 기존 TCP에서 3으로 고정된 중복 응답 임계값을 동적으로 조절하여, 잘못된 혼잡 제어를 예방하고 있다. 일반적으로 전송한 패킷의 수가 많을 때, 패킷 재배치를 경험할 확률이 높으며, 패킷 재배치에 의해 잘못된 혼잡 제어가 일어날 가능성 많다. 고속 네트워크 환경에서는 혼잡 윈도우 크기 변화의 폭이 매우 크다는 점을 고려할 때, 중복 응답 임계값을 조절하는 TCP-DAD는 한계가 있다. 본 논문에서는 고속 네트워크 환경에서의 패킷 재배치 현상으로 인한 TCP 성능저하를 완화하기 위한 새로운 알고리즘 TCP-DT를 소개한다. 이는 중복 응답 수에 의존하지 않고 타이머를 통해 혼잡 제어를 수행하는 메커니즘 이다. 본 논문은 NS-2를 사용하여 고속 네트워크 환경에서의 시뮬레이션을 통해 제안한 TCP-DT의 성능 향상을 증명하였다.