• Journal of Korean Society of Coastal and Ocean Engineers
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• v.27 no.4
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• pp.197-201
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• 2015

Experimental and numerical analysis has been carried out in this paper to understand correlation between volume and yield of cellular bulkhead. It was firstly confirmed from these results that the conditions and parameters considered in the finite element analysis were reasonable and realistic due to the fact that the yield loads determined by the two different methods were equivalent in actual. Based on this results, a series of intensive numerical analysis has been further performed and revealed that the yield load varied in direct proportion to the change in the volume of the cellular bulkhead.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.9A
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• pp.1372-1382
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• 1999

The major source of errors in high-speed networks such as Broadband ISDN(B-lSDN) is buffer overflow during congested conditions. These congestion errors are the dominant sources of errors in 1high-speed networks and result in cell losses. Conventional communication protocols use error detection and retransmission to deal with lost packets and transmission errors. However, these conventional ARQ(Automatic Repeat Request) methods are not suitable for the high-speed networks since the transmission delay due to retransmissions becomes significantly large. As an alternative, we have presented a method to recover consecutive cell losses using forward error correction(FEC) in ATM(Asynchronous Transfer Mode)networks to reduce the problem. The performance estimation based on the cell discard process model has showed our method can reduce the cell loss rate substantially. Also, the performance estimations in ATM networks by interleaving and IP multicast service are discussed.

• The KIPS Transactions:PartB
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• v.12B no.4 s.100
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• pp.369-378
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• 2005

Document image is segmented and classified into text, picture, or table by a document layout analysis, and the words in table regions are significant for keyword spotting because they are more meaningful than the words in other regions. This paper proposes a method to extract words from table regions in document images. As word extraction from table regions is practically regarded extracting words from cell regions composing the table, it is necessary to extract the cell correctly. In the cell extraction module, table frame is extracted first by analyzing connected components, and then the intersection points are extracted from the table frame. We modify the false intersections using the correlation between the neighboring intersections, and extract the cells using the information of intersections. Text regions in the individual cells are located by using the connected components information that was obtained during the cell extraction module, and they are segmented into text lines by using projection profiles. Finally we divide the segmented lines into words using gap clustering and special symbol detection. The experiment performed on In table images that are extracted from Korean documents, and shows $99.16\%$ accuracy of word extraction.

• Proceedings of the KIPE Conference
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• 2010.07a
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• pp.422-423
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• 2010

직렬 연결된 배터리는 각 셀의 내부 화학적 특성 차이로 인해 동일 전류로 충전 및 방전 과정을 진행하여도 셀 간에 미세한 전압 차이가 발생한다. 이러한 셀 간 전압 불균형은 배터리 셀에 해로운 영향을 끼치게 되는데, 2차 전지의 경우 배터리 용량의 변화를 야기한다. 이러한 문제를 해결하기 위해서 배터리 운용 범위를 제한하는 보호회로가 있지만 보호회로는 직렬 연결된 배터리 셀 중 가장 전압이 높거나 가장 낮은 셀을 기준으로 충전과 방전 사이클을 종료시키므로 배터리 팩의 용량을 최대한으로 사용하지 못하게 하는 문제를 발생시킨다. 배터리 균등화 회로는 셀 간의 전압 차이를 줄여 배터리의 최대 용량을 사용하고자 하는 목적을 가진다. 저항을 기반으로 하는 수동적인 방법과는 달리 스위칭 소자를 이용하는 능동적인 방법에서는 스위칭으로 인해 입출력 전압 변동이 발생하여 컨버터 내부에 흐르는 전류가 수시로 변하는 문제가 생긴다. 위 문제를 해결하기 위한 방법으로 본 논문에서는 배터리 균등화 회로에 전하 제어(Charge control)기법을 제안하고, 그에 따른 회로 설계 요소를 제시한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.8B
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• pp.687-694
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• 2012

In OFDMA-based cellular system, inter-cell interference (ICI) reduces system capacity by aggravating receiving performance of the users located in edge of the cell. Therefore, to mitigate ICI is very important issue in cellular system. To deal with ICI problem, fractional frequency reuse (FFR) is introduced. FFR is an interference management technique. It separates each cell into inner cell and outer cell. Then, it allocates whole system bandwidth to inner cell and different frequency partition to each sector of outer cell. By doing this, outer cell users can ignore interferences from adjacent cells. So, the receiving performance of the cell edge users can be fairly increased. However, using FFR technique has a fatal side effect. In order to use different frequency partition among three sectors of outer cell, they can use only a third of the whole system bandwidth. Then, the reduction of available bandwidth reduces the system throughput directly. To solve this problem, we propose a new FFR method that allocates partially overlapped frequency partition to each sector of outer cell. And then, we suggest a proper overlapping ratio for practical cellular system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.3A
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• pp.217-224
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• 2010

In this paper, we propose a hard handover algorithm for a base station's self-optimization, one of the automatic operational technologies for the 3GPP LTE systems. The proposed algorithm simultaneously considers a mixed target sell selection method for optimal selection and a multiple parameter based active hysteresis method with the received signal strength from adjacent cells and the cell load information of the candidate target cells from information exchanges between eNBs through X2 interface. The active hysteresis method chooses optimal handover hysteresis value considering the costs of the various environmental parameters effect to handover performance. The algorithm works on the optimal target cell and the hysteresis value selections for a base station's automatic operational optimization of the LTE system with the gathered informaton effects to the handover performance. The simulation results show distinguished handover performances in terms of the most important performance indexes of handover, handover failure rate and load balancing.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.11C
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• pp.113-122
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• 2001

Several guidelines can be developed for a satellite-based ATM switch. One of the most important of these is that the switch must provide a requirement for CLRs on the order of 10-10 to meet the QoS of high- performance traffic and avoid costly retransmissions. In this paper, the proposed approach shows not only the better traffic performance but also requires the little switching elements and buffers compared with original Knockout switch and other scheduling algorithm. As a result, the complexity becomes reduced. Simulation results indicate that proposed approach shows excellent cell loss ratio compared with existing switch architecture. Also, iii performance can be approached to the cell loss ratio, which is requirement for the satellite system, as window size increases. An(1 it shows thats low complexity is induced. Therefore, the proposed approach is appropriate for satellite on-board ATM switch architecture.

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.5
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• pp.1601-1610
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• 1991

본 연구에서는 3차원 스트레칭 문제의 2차원화가 가능한 주요 단면에 대해서 박막요소와 적층 셸(degenerated shell) 요소를 혼합하여 사용하는 선택적 M/S 방법을 이용하여 2차원 문제로 해석하였다. M/S변환 조건으로는 변형형상의 기하학적 조건 을 고려하였다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.10a
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• pp.599-602
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• 2014

Proposal algorithm in this thesis introduced cells, units of router group, for distributed processing of previous genetic algorithm. This thesis presented ways to reduce search delay time of overall network through cell-based genetic algorithm. With regard to procedures of proposal algorithm, duplicated agents were transferred to the point, where the second, third, and fourth cells were created in order, after the first cell was made, and the agents were engineered to search the shortest path to each cell, and then find the most efficient element through competition.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2001.05a
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• pp.266-269
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• 2001

이미지와 비디오신호 처리는 영상인식에 있어 중요한 요소이다. 셀룰라 신경회로망은 영상과 관련된 분야에서 많이 사용되고 있다. 그 응용분야로서 본 논문에서는 로봇축구에 적용하기 위하여 8색의 컬러구분을 통한 축구로봇의 인식과, 또한 경기장의 격자구조의 분할을 통한 셀간의 이동을 통하여 간단한 경로 이동과 급변하는 환경의 변화에 적응하는 시스템을 구현한다. CNN을 이용한 영상처리에서는 각 셀을 화면상의 각 화소에 대응하고, 셀의 출력의 값을 화소의 값으로 정한다. CNN을 이용한 경로계획에서는 각 셀이 격자구조 경기장의 한 부분이 되고, 정의된 출력의 셀이 로봇이 이동할 목표가 된다.