• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2022.11a
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• pp.145-146
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• 2022

물동량 증가로 인하여 부산신항에는 극초대형 컨테이너 선박들이 입항하고 있으며 서컨테이너 부두 건설 사업이 완료되면 부산신항 진출입 항로 내 다양한 조우 상황 발생으로 충돌 위험 상황을 초래할 수 있어 선박 통항 안전성 향상 방안 마련을 위하여 부산신항 내 항만 입출항 현황과 해상교통흐름을 살펴보았으며, AHP 기법을 활용하여 위험요소 및 안전대책 식별로 도출된 안전대책을 기반으로 환경 스트레스 모델을 활용하여 해상교통류 시뮬레이션을 실시하여 각 안전대책의 교통 위험도를 파악하였다. 설문조사 및 시나리오 평가 결과, 선박운항자는 일방통행을 위한 진입금지 해역 설정을 가장 중요하게 생각하였으며, 이는 위험도 경감에 큰 효과가 있을 것으로 예상되었다, 본 연구는 부산신항을 입출항 하는 선박들의 통항 안전성 제고를 위한 안전대책 마련의 기반이 될 수 있을 것이다.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.45 no.4
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• pp.53-63
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• 2008

Reader collision may occur when neighboring RFID readers use the same channel at the same time. Especially when the readers are operated in dense mode, even though many channels are available, because of frequent reader collisions we can not guarantee the performance of RFID readers. Conventional solutions such as FH(Frequency Hopping) or LBT(Listen Before Talk) are not effective in this situation because they can not schedule RFID readers effectively when RFID readers are operated in multi-channel, dense reader mode, In this paper, we propose a new RFID reader anti-collision algorithm which employs LBT, random backoff before channel access, and probabilistic channel hopping at the same time. While LBT and Random backoff before channel access reduces collisions between competing readers, probabilistic channel hopping increases channel utilization by adaptively changing the hopping probability by reflecting the reader density and utilization. Simulation results shows that our algorithm outperforms conventional methods.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.20 no.2
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• pp.43-57
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• 2021

The Forward Collision Warning, a representative technology of the Advanced Driver Assistance Systems, was selected as the target technology. The cognitive response time, deceleration, and impact were selected as the measures of effectiveness. And the amount of change with and without the Forward Collision Warning was measured. The experimental scenarios included a sudden stop event (1) of the vehicle in front of the driver and an event (2) in which the vehicle intervened in the next lane. All experiments were divided into day and night. As a result of the analysis, response time and the deceleration rate decreased when the forward collision warning system was installed. It was analyzed that the driver's risk situation could be detected quickly and the number of front-end collisions could be reduced as a result. Reflecting the driver's operating habits and diversifying the experimental scenarios will increase the installation effectiveness of ADAS and be used to estimate the effectiveness of other technologies.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.7
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• pp.430-439
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• 2019

In this study, a nonlinear impact analysis was performed to evaluate the safety and damage of an eco-pillar debris barrier with a hollow cross-section, which was proposed to improve constructability and economic efficiency. The construction of concrete eco-pillar debris barriers has increased recently. However, there are no design standards concerning debris barriers in Korea, and it is difficult to find a study on performance evaluations in extreme environments. Thus, an analysis of an eco-pillar debris barrier was done using the rock impact speed, which was estimated from the debris flow velocity. The diameters of rocks were determined by ETAG 27. The impact position, angles, and rock diameter were considered as variables. A concrete nonlinear material model was applied, and the estimation of damage was done by ABAQUS software. As a result, the damage ratio was found to be less than 1.0 at rock diameters of 0.3 m and 0.5 m, but it was 1.39 when the diameter was 0.7 m. This study could be used as basic data on impact force in the design of the cross section of an eco-pillar debris barrier.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.12
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• pp.918-923
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• 2018

The main function of a fuel tank is to store fuel. On the other hand, the structural soundness of the fuel tank is related directly to the survival of the crew in an emergency situation, such as an aircraft crash, and the relevant performance is demonstrated by a crash impact test. Because crash impact tests have a high risk of failure due to the high impact loads, various efforts have been made to minimize the possibility of trial and error in the actual test at the beginning of the design. Numerical analysis performed before the actual test is a part of such efforts. For the results of numerical analysis to be reflected in the design, however, the reliability of numerical analysis needs to be ensured. In this study, the results of numerical analysis and actual test data were compared to ensure the reliability of numerical analysis for the crash impact test of a rotorcraft fuel tank. For the numerical analysis of a crash impact test, LS-DYNA, crash analysis software, was used and the ALE (arbitrary Lagrangian Eulerian) technique was applied as the analysis method. To obtain actual test data, strain gages were installed on the metal fittings of the fuel tank and linked to the data acquisition equipment. The strain and stress of the fuel tank fitting were calculated by numerical analysis. The reliability of the numerical analysis was enhanced by assessing the error between the strain measurement of the upper fitting obtained from an actual fuel tank and the strain calculated from numerical analysis.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.37 no.2
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• pp.17-23
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• 2000

Wireless link has high bit error rate compared with wired link and many users share this limited bandwidth. So it needs more powerful error control code and efficient media access control(MAC) to provide multimedia service reliably. In this paper we proposed efficient MAC frame format based on TDMA using mini-slot for request access. The number of mini-slots is variable based on the result of collision in the previous frame. This dynamic allocation of request mini-slots helps resolve the contention situation quickly and avoids the waste of bandwidth that may occur when there are several unneeded request mini-slots. The simulation results are also presented in terms of channel utilization, call blocking probability and cell transmission delay for mixed traffic environment.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.7
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• pp.1589-1598
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• 2014

To support the WBAN, IEEE 802.15 Task Group 6 announced standardized documents on technical requirements of the PHY and MAC. In the IEEE 802.15.6 MAC protocol, CSMA/CA(Carrier Sense Multiple Access with Collision Avoidance) algorithm is performed based on the eight-level priorities according to the type of traffics of the periodic data from medical sensor nodes. Several nodes, which detected the changed bio signals, transmit emergency data at the same time, so latency could be higher than emergency latency and energy consumption will increase. In this thesis, we proposed a CSMA/CA algorithm in WBAN to solve these problems. Simulations are performed using a Castalia based on the OMNeT++ network simulation framework to estimate the performance of the proposed superframe and algorithms. Performance evaluation results show that the packet transmission success rate and energy efficiency are improved by reducing the probability of collision using the proposed MAC protocol.

• Journal of Digital Convergence
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• v.12 no.10
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• pp.61-71
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• 2014

Global commerce is apparently here to bind Korean firms as well as Koreans. The advertising, buying and selling of goods and services recognizes no borders. As a result, enforcing territorially based trademark rights has become ever more challenging. Remote trademark owners who peacefully coexisted in a time before the internet and increasing globalism are now bumping heads. The internet also has made it easier for unscrupulous operators to deceive consumers and divert customers from established businesses by misappropriating trademarks on web-sites and in domain names. U.S. federal courts have been willing to help American businesses halt trademark infringements that reaches outside the United States. This is particularly true for e-business, via the internet, and the trend toward enforcement seems to be in favor of the trademark owner. This article discusses this trend as well as the extraterritorial enforcement of trademark rights by U.S. courts under the Lanham Act. It also offers suggestions for protecting valuable trademark rights worldwide. This paper will contribute to global Korean firms and Koreans who carefully read arguments in this valuable literature.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38B no.7
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• pp.543-552
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• 2013

For the safety messages in IEEE 802.11p/WAVE vehicles network environment, strict periodic beacon broadcasting requires status advertisement to assist the driver for safety. In crowded networks where beacon message are broadcasted at a high number of frequencies by many vehicles, which used for beacon sending, will be congested by the wireless medium due to the contention-window based IEEE 802.11p MAC. To resolve the congestion, we consider a MAC scheme based on slotted p-persistent CSMA as a simple non-cooperative Bayesian game which involves payoffs reflecting the attempt probability. Then, we derive Bayesian Nash Equilibrium (BNE) in a closed form. Using the BNE, we propose new congestion control algorithm to improve the performance of the beacon rate under saturation condition in IEEE 802.11p/WAVE vehicular networks. This algorithm explicitly computes packet delivery probability as a function of contention window (CW) size and number of vehicles. The proposed algorithm is validated against numerical simulation results to demonstrate its stability.

• Journal of Navigation and Port Research
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• v.38 no.5
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• pp.493-501
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• 2014

An automated lifting vehicle(ALV) used in an automated container terminal is a type of unmanned vehicle that can self-lift a container as well as self-transport it to a destination. To operate a fleet of ALVs efficiently, one needs to be able to determine a minimum-time route to a given destination whenever an ALV is to start its transport job. To find a route free from any collision or deadlock, the occupation time of the ALV on each segment of the route should be carefully scheduled to avoid any such hazard. However, it is not easy because not only the travel times of ALVs are uncertain due to traffic condition but also the operation times of cranes en route are not predicted precisely. In this paper, we propose a routing method based on an ant colony optimization algorithm that takes into account these uncertainties. The result of simulation experiment shows that the proposed method can effectively find good routes under uncertainty.