• KSII Transactions on Internet and Information Systems (TIIS)
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• 제7권8호
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• pp.1770-1785
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• 2013

In this paper, a multi-hop transmission protocol based on parallel communication of secondary users (SUs) is proposed. The primary multi-hop network coexists with a set of SUs by cooperative spectrum sharing. The main optimization target of our protocol is the overall performance of the secondary system with the guarantee of the primary outage performance. The energy consumption of the primary system is reduced by the cooperation of SUs. The aim of the primary source is to communicate with the primary destination via a number of primary relays. SUs may serve as extra decode-and-forward relays for the primary network. When an SU acts as a relay for a primary user (PU), some other SUs that satisfy the condition for parallel communication are selected to simultaneously access the primary spectrum for secondary transmissions. For the proposed protocol, two opportunistic routing strategies are proposed, and a search algorithm to select the SUs for parallel communication is described. The throughput of the SUs and the PU is illustrated. Numerical results demonstrate that the average throughput of the SUs is greatly improved, and the end-to-end throughput of the PU is slightly increased in the proposed protocol when there are more than seven SUs.

• 한국전자통신학회논문지
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• 제16권6호
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• pp.1145-1152
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• 2021

1.4P 대형 스토리지의 성능을 최적화하기 위하여 청크모드별 특성을 조사하고, I/O 속도면에서 청크 512K 모드를 선택하였다. NVME 스토리지 시스템을 구성하여 대형 스토리지의 데이터 서버 성능 측정에 활용하였다. 1.4P 대형 스토리지의 쓰레드 수에 따른 스루풋의 변화를 측정하여 대형 스토리지 시스템의 특성을 파악하였으며, 스루풋의 최대값은 블록크기 32KB에서 133Gbps 성능을 보임을 확인하였다. GridFTP 방식의 globus-url-copy를 이용하여 데이터 송수신 실험을 수행한 결과, 이 대형 스토리지는 33Gbps의 스루풋을 가지고 있음을 알 수 있었다.

• 한국인터넷방송통신학회논문지
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• 제23권1호
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• pp.45-50
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• 2023

본 논문에서는 기지국이 단말들에게 데이터를 전송하는 경우에, 전체 시스템의 수율을 향상시키기 위하여 다중사용자 다중안테나 기법(MU-MIMO), 시공간부호화 기법(STBC), 비직교 다중접속 기법(NOMA)을 동시에 적용하는 방식을 제안한다. 기지국과 가까이 위치한 두 개의 단말에 대해서는 MU-MIMO 기법을 적용하고, 기지국과 멀리 떨어진 단말은 채널 정보를 얻기가 어렵기 때문에 STBC 기법을 적용한다. 또한 기지국에 가까운 단말과 멀리 떨어진 단말의 데이터들을 구분하기 위하여 NOMA 기법을 적용한다. MU-MIMO를 적용하는 단말들 간에는 서로 직교하는 두 개의 프리코딩 벡터들을 사용함으로써 서로 간의 간섭이 존재하지 않도록 설계한다. 또한 기지국에서 멀리 떨어진 단말에 대해서는 두 개의 프리코딩 벡터들을 사용하는 STBC 기법을 적용한다. 성능 분석 및 모의실험을 통하여 제안하는 기법이 기존 기법보다 더 높은 전체 시스템 수율 값을 갖는다는 것을 보인다.

• 한국통신학회논문지
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• 제28권12A호
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• pp.951-957
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• 2003

통신 시스템의 무선성능 요구조건 분석은 시스템의 성능을 예측하는 중요한 지표이다. 아직 표준안이 제정되지 않은 UWB(Ultra Wide Band) 시스템은 명확한 시스템 성능 요구조건을 유도하기 어렵다. 또한, 기존의 UWB 시스템과 멀티밴드 UWB 시스템의 무선성능 요구조건 분석에는 차이점이 있다. 이러한 차이점을 본 논문을 통해 분석하였으며, 이를 바탕으로 도출한 멀티밴드 UWB 시스템의 성능 요구조건을 본 논문에 기술하였다. 멀티밴드 UWB 시스템은 Sub-Band의 수에 따라 Throughput, 송신 최대 전력, 수신감도 등이 변화하는 것을 관찰할 수 있었다. 또한, 멀티패스의 영향으로 PRF(Pulse Repetition Frequency)를 변경하면 Link Margin은 증가하여 멀티패스 에너지 손실(Multi-path Energy Loss)에 대한 보상으로 멀티패스 마진(Multi-path Link Margin)이 발생하는 것을 알 수 있었으며 멀티패스 마진에 따라 수신신호 감도 및 간섭신호에 대한 저항성이 변화하는 것을 모의실험을 통하여 분석하였다.

• International Journal of Contents
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• 제3권1호
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• pp.34-38
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• 2007

Load redistribution is a critical resource in computer system. In sender-initiated load redistribution algorithms, the sender continues to send unnecessary request messages for load transfer until a receiver is found while the system load is heavy. These unnecessary request messages result in inefficient communications, low CPU utilization, and low system throughput in distributed systems. To solve these problems, we propose a genetic algorithm based approach for improved sender-initiated load redistribution in distributed systems. Compared with the conventional sender-initiated algorithms, the proposed algorithm decreases the response time and task processing time.

• 산업공학
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• 제9권3호
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• pp.225-235
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• 1996

The SECS Ⅰ and Ⅱ Protocol has been widely used for the TFT LCD and semiconductor industry. This paper shows how the SECS protocol is implemented for data communications between the Host (CAM) and the TFT LCD equipments. In addition, this study introduces a way to apply the SECS protocol to the manufacturing systems control. It provides better throughput in terms of production and faster control of the automated TFT LCD manufacturing system by way of shortcut and distribution of control and data communications. The SECS protocol is successfully used for the control of the real TFT LCD manufacturing system.

• 대한산업공학회지
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• 제23권2호
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• pp.343-357
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• 1997

This paper proposes a new AGV dispatching algorithm which is suitable for heterarchical manufacturing control structure. It is developed on the basis of bidding concept utilizing the information of work-in-process in incoming and outgoing buffers of workstation, and travel time of AGV. Since the bidding functions are functions of two parameters, sensitivity test is performed to find their appropriate values. The performance of the algorithm is compared with those of well-known existing rules in terms of system throughput through simulation on a hypothetical job shop type manufacturing system.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 하계종합학술대회 논문집(1)
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• pp.85-88
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• 2002

Maintaining a proper level of cell lead, system throughput can be maximized by a transmission rate control over the uplink in DS/CDMA cellular system to support integrated services of real-time and delay-tolerant traffic. We find that the cell load-based rate control scheme can be further enhanced by taking the varying channel condition into account In conjunction with some fair scheduling algorithm. Our simulation results show that the proposed scheme outperforms the original cell load-based rate control with the round-robin sharing scheduling scheme.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권9호
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• pp.3907-3923
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• 2020

An enhanced irregular repetition slotted ALOHA (IRSA) protocol is proposed by using polarization characteristic of satellite link and MIMO detection in low earth orbit (LEO) satellite networks, which is dubbed polarized MIMO IRSA (PM-IRSA). In the proposed scheme, one or two packets in one slot can be decoded by employing polarized MIMO detection, and more than two collided packets in multiple slots which can construct the virtual MIMO model can be decoded by the MIMO detection algorithm. The performance of the proposed scheme is analyzed with the density evolution (DE) approach and the degree distribution is optimized to maximize the system throughput by using a differential evolution. Numerical results certify our analysis and show that the normalized throughput of the proposed PM-IRSA can achieve 1.89 bits/symbol.

• 한국항해항만학회지
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• 제39권5호
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• pp.417-422
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• 2015

Sea-ports in Northern Vietnam have experienced a rapid growth of container throughput in recent years. To accompany with such development, huge investment also has been performed to enhance not only local port capacity but also the regional logistics system. Container terminals in Northern Vietnam locate centrally along Cam river of Haiphong city, leaving 2 others in Quang Ninh province. Five out of totally 11 container terminals in the area are under the control of Vinalines - a national corporation in field of maritime industry. In this paper, those terminals are classified in terms of location and ownership. The volume of container throughput and facilities of all container terminals in Northern Vietnam from 2005 to 2014 are recorded in order to compare the performance of groups. A Data Envelopment Analysis (DEA) is then applied to evaluate the relative efficiency of such terminals. Before conclusion, number of suggestions will be contributed to related parties.