• Proceedings of the Korea Multimedia Society Conference
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• 1998.10a
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• pp.106-111
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• 1998

본 연구의 목적은 트랜잭션 순서화 기법중 데이터 우선순위 알고리즘(DPLP: Data-Priority Based Locking Potocol)의 높은 재시작 비율을 낮추고, 시스템의 처리 효율을 향상 시키는 것이다. 이를 위해서 트랜잭션을 일정한 크기의 그룹으로 그룹핑하고, 같은 그룹에 있는 트랜잭션은 선점권을 인정함으로써 자원을 점유하고 있는 트랜잭션에게 우선순위를 상속하여 트랜잭션의 재시작 비율을 낮춘다. 낮은 트랜잭션이 데이터를 장시간 잠금(lock)하는 것을 방지하기 위해서 그룹 우선순위를 적용한다. 상속에 의한 데드락 방지를 위해서 충돌전에 다른 데이터의 잠금여부를 검사한다. 성능을 평가하기 위해서 분산 데이터 베이스 시스템으로 시뮬레이션 환경을 구축하여 기존의 기법들과 성능을 비교하였다. 성능 비교 결과는 본 논문에서 제안하는 데이터 우선순위 상속 알고리즘이 기존의 상속 알고리즘과 데이터 우선순위 알고리즘 보다 성능이 우수함을 확인하였다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.10a
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• pp.723-725
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• 2016

In Gen-2 Q-algorithm, if the number of tags is small and we let the initial $Q_{fp}$ be large, the number of empty slot will be large. On the other hand, if we let the initial $Q_{fp}$ be small in spite of many tags, almost all the slots will be collided. Also, if the reader selects an inappropriate weight, there are a lot of empty or collided slots. As a result, the performance will be declined because the frame size does not converge to the optimal point quickly during the query round. In this paper, we propose a scheme to select the weight based on the slot-count size of current query round through the tag number estimation and.

• Proceedings of the KAIS Fall Conference
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• 2002.11a
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• pp.209-211
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• 2002

본 연구에서는 비교적 하드웨어의 복잡성보다는 효율적인 Routing 알고리즘을 통하여 스위칭 네트워크의 성능을 향상시킬 수 있는 Sort-Banyan을 기본으로 한 스위칭 구조를 근간으로 하여 하드웨어 구조의 개선과 그에 맞는 최적의 Routing 알고리즘을 개발하고자 한다. 따라서 고속 통신망의 스위치 네트워크를 구현하기 위해 두 단계의 패킷 분배 결정 알고리즘을 구성하고 그에 따라 분배를 결정하여 패킷이 전송될 때 출력 단에서 충돌이 발생하지 않도록 사전에 선택적으로 전송함으로서 패킷의 손실을 방지하는 패킷 스위치 네트워크를 제안한다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.2
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• pp.287-292
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• 2007

In this paper, a QT_ecfi algorithm is proposed for identifying all the tags within the identification range. The proposed QT_ecfi algorithm revises the QT algorithm, which has a memoryless property. In the QT_ecfi algorithm, the tag will send the remaining bits of their identification codes when the query string matches the first bits of their identification codes. When the reader receives all the responses of the tags, it knows which bit is collided. If the collision occurs in the last bit, the reader can identify two tags simultaneously without further query. While the tags are sending their identification codes, if the reader detects a collision bit, it will send a signal to the tags to stop sending. According to the simulation results, the QT_ecfi algorithm outperforms the QT algorithm in terms of the number of queries and the number of response bits.

• 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.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.431-432
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• 2013

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2006.07a
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• pp.347-347
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• 2006

• KIPS Transactions on Software and Data Engineering
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• v.10 no.12
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• pp.561-568
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• 2021

In recent years, autonomous driving technologies have become a high-value-added technology that attracts attention in the fields of science and industry. For smooth Self-driving, it is necessary to accurately detect an object and estimate its movement speed in real time. CNN-based deep learning algorithms and conventional dense optical flows have a large consumption time, making it difficult to detect objects and estimate its movement speed in real time. In this paper, using a single camera image, fast object detection was performed using the YOLOv5 algorithm, a deep learning algorithm, and fast estimation of the speed of the object was performed by using a local dense optical flow modified from the existing dense optical flow based on the detected object. Based on this algorithm, we present a system that can predict the collision time and probability, and through this system, we intend to contribute to prevent tram accidents.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.2 s.344
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• pp.27-38
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• 2006

When an RFID reader attempts to read tags, interference might occur if the neighboring readers also attempt to communicate with the same tag at the same time or the neighboring readers use the same frequency at the same time. These interferences cause the RFID reader collision. When the RFID reader collision occirs, either the command from the reader can not be transmitted to the tags or the response from the tags can not be received by the reader correctly. RFID reader anti-collision algorithms have been developed to reduce it. One of the best blown reader anti-collision algorithms is the Colorwave algorithm proposed by MIT. The Colorwave algorithm reduces the reader collisions by having the readers operate at different times. In Colorwave the time is divided into frames and a frame is divided into a number of slots. Each reader can access the tags using the slot time assigned to it. Depending on the probability of the interference, the colorwave adjusts the frame size to improve the efficiency. In this paper, we analyze the operations and the performance of the Colorwave algorithm and identify the problems of the algorithm. We also show that by adding some modifications to the algorithm the performance can be improved significantly.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.6
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• pp.1333-1340
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• 2015

IEEE 802.11 MAC(Media Access Control) defines DCF(Distributed Coordination Function) for data transmission control. BEB(Binary Exponential Backoff) algorithm of DCF has a problem that if the number of stations connected are over a certain threshold, it degrades network performance because of packet collisions caused from the minimum contention window size. To cope with this problem, we proposed a novel algorithm, named as VBS(Variable Backoff Stage) algorithm, which adjusts the rate of backoff stage increment depending on the number of stations associated with an AP(Access Point). Analytic model of proposed algorithm was derived and simulations on the BEB and the VBS algorithms have been conducted on the OFDM (Orthogonal Frequency Division Multiplexing) method. Simulation results showed that when the rate of backoff state increment was 5 and 10, the number of retransmission were reduced to 1/5 and 1/10 comparing to that of BEB, respectively. Our algorithm showed improvement of 19% and 18% in network utilization, respectively. Packet delay was reduced into 1/12.