• Proceedings of the Korea Information Processing Society Conference
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• 2011.04a
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• pp.655-658
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• 2011

본 연구는 이종 무선 네트워크에서 발생하는 핸드오버 부하를 개선하는 알고리즘을 제안한다. 핸드오버는 단말기의 위치가 네트워크의 구성 단위인 셀을 옮겨갈 때 발생한다. 이 위치 업데이트 비용은 매우 크다. 효과적인 위치 업데이트를 위해서 idle 상태에서는 단말기가 셀 선택 알고리즘에 의해서 셀을 결정한 뒤, 핸드오버 여부를 보고한다. 본 논문에서 제안하는 방식은 셀 내부에 가상의 버퍼 영역을 두어 버퍼 영역 안쪽의 핸드오버를 제한하고, 버퍼 영역 바깥쪽의 핸드오버는 기존 방식을 이용하는 것이다. 실험은 네트워크 시뮬레이터 NS-3에서 수행되었고, 그 결과 제안된 알고리즘이 핸드오버 횟수를 프로필 기반 네트워크 선택 프레임워크(Profile-based Network Selection Framework, PNSF) 알고리즘 대비 약 7% 감소시켰으며, 위치 정보의 정확성은 PNSF와 동등한 성능을 보여 위치 기반 서비스의 질 향상에 기여함을 확인할 수 있었다.

• Proceedings of the KIPE Conference
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• 2020.08a
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• pp.215-217
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• 2020

본 논문은 배터리 팩 내부 셀 파라미터의 불균일도에 대한 분석을 실시하고 이를 기반으로 과방전을 사전에 진단할 수 있는 방법을 제안한다. 이를 위해서 배터리 팩 내부 셀간 편차가 발생하는 셀을 선정하여 두 셀간 특성 분석을 실시하였으며, 이를 기준으로 예측 모델을 구성하였다. 예측 성능을 통해 배터리 전압 예측 성능에 영향을 미치는 인자를 분석하였으며, 배터리 전기적 등가회로 모델을 기반으로 예측 모델을 제안한다. 예측 모델은 실제 과방전이 발생한 셀을 기준으로 실험데이터와 비교하여 예측 성능을 검증하였다.

• Journal of the Korean Geotechnical Society
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• v.36 no.12
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• pp.87-97
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• 2020

Recently, interest in Tie-cell wave-dissipating blocks that can compensate for the disadvantages of block-type breakwaters and provide economically effective design is increasing. Tie-cell wave-dissipating block has high activity resistance due to its structure in which each block is held together by a pile. In this study, through the laboratory model experiments, it was possible to confirm the increase in lateral resistance of the Tie-cell wave-dissipating blocks due to the penetration of the piles. The lateral resistance of the piles appeared almost constant regardless of the overburden load of the blocks. The lateral resistance shared by the piles changed depending on the increase or decrease in the lateral resistance of the friction between blocks. In the experiment in which two piles were penetrated, the overall lateral resistance was larger than the case a single pile was used, but the resistance behavior of the piles was different.

• Tunnel and Underground Space
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• v.32 no.3
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• pp.219-230
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• 2022

The Geo-Reservoir Experimental Analogue Technology (GREAT) cell was designed to recreate the thermal-hydro-mechanical conditions of deep subsurface in the laboratory. This apparatus can generate a polyaxial stress field using lateral loading elements, which rotate around the longitudinal axis of a sample and is capable of performing a fluid flow test for samples containing fractures. In the present study, numerical simulations were carried out for triaxial compression tests using the GREAT cell and the mechanical behavior of samples under different conditions of lateral loading was investigated. We simulated an actual case, in which triaxial compression tests were conducted for a polymer sample without fractures, and compared the results between the numerical analysis and experiment. The surface strain (circumferential strain) of the sample was analyzed for equal and non-equal horizontal confining pressures. The results of the comparison showed a good consistency. Additionally, for synthetic cases with a fracture, we investigated the effect of the friction and type of fracture surface on the deformation behavior.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.9B
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• pp.591-595
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• 2005

In this paper, we propose the fairness improvement leaky bucket (PILB) algorithm as a traffic policing mechanism. In the proposed algorithm, there is a cell buffer for every ATM connection in order to store date cells. Network decides whether an ATM connection obeys the contracted traffic parameter, and stores data cells in the cell buffer if the connection obeys but is considered as violated the contract due to temporary lack of network resource. By using the proposed algorithm, we can obtain the statistical multiplexing gain that is the superiority of packet switching network. Moreover, when a connection tries to transmit more data cells by violating the contracted traffic parameters, the connection is prevented from using excess network resource, which incurs all connections sharing network resource fairly. The performance of the proposed FILB algorithm is investigated by using the simulation. The result shows that the proposed algorithm provides superior performance and all connections within a group share network resource fairly. The proposed algorithm can be applied not only the ATM network but also IP network.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.4A
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• pp.371-376
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• 2008

In this paper, we explain the unified inter-cell interference avoidance and cancellation in OFDM mobile cellular systems. Interference avoidance is used for cell-interior or two-cell-edge users, and interference cancellation is applied to three-cell-edge users. The performance of the unified scheme is evaluated by simplified system simulation. Link simulation results are used in the interpretation of system simulation output. We compare three schemes which are "no interference management," "only interference avoidance," "both avoidance and cancellation." Primary performance measures are the data rate of the 5th percentile user and the mean data rate. Simulation results show that interference management schemes greatly improve the cell edge performance, but slightly reduce the mean data rate. Use of both avoidance and cancelaltion is better than that of only avoidance in terms of the cell edge throughput and the mean data rate.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.22 no.4
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• pp.230-234
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• 2010

This study examined the effect of wall friction on deformation characteristics of the cellular bulkhead, in terms of artificial wall friction based on the results of model tests according to the existing penetration ratio and loading height. 1. The effect of wall friction on deformation characteristics of the cellular bulkhead turned out to be less as the loading height decreases and the penetration ratio increases. The yield load also becomes less as wall friction decreases. 2. The ratio of the rotational displacement to the horizontal displacement of the cellular bulkhead becomes less as the loading height decreases and the penetration ratio increases. Hence it is concluded that the effect of wall friction has close relationship with the rotational displacement.

• Journal of IKEEE
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• v.23 no.1
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• pp.1-8
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• 2019

In this paper, the electrical characteristics with various C-rates are tested with a high power series battery pack comprised of 18650 cylindrical nickel cobalt aluminum(NCA) lithium-ion battery. The electrical characteristics of discharge capacity test with 14S1P battery pack and electric vehicle (EV) cycle test with 4S1P battery pack are compared and analyzed by the various of C-rates. Multiple linear regression is used to estimate voltage imbalance of 14S1P and 4S1P battery packs with various C-rates based on experimental data. The estimation accuracy is evaluated by root mean square error(RMSE) to validate multiple linear regression. The result of this paper is contributed that to use for estimating the voltage imbalance of discharge capacity test with 14S1P battery pack using multiple linear regression better than to use the voltage imbalance of EV cycle with 4S1P battery pack.

• Journal of KIISE
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• v.42 no.10
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• pp.1239-1246
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• 2015

Cell counting is extensively used to analyze cell growth in biomedical research, and as a result automated cell counting methods have been developed to provide a more convenient and means to analyze cell growth. However, there are still many challenges to improving the accuracy of the cell counting for cells that proliferate abnormally, divide rapidly, and cluster easily, such as cancer cells. In this paper, we present an automated cell counting method for HeLa cells, which are used as reference for cancer research. We recognize and classify the morphological conditions of the cells by using a cell segmentation algorithm based on cell membrane extraction, and we then apply a cell back-tracking algorithm to improve the cell counting accuracy in cell clusters that have indistinct cell boundary lines. The experimental results indicate that our proposed segmentation method can identify each of the cells more accurately when compared to existing methods and, consequently, can improve the cell counting accuracy.

• Journal of Bio-Environment Control
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• v.15 no.4
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• pp.346-351
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• 2006

This study was carried out to investigate the effect of application concentration and period of sodium selenate ($Na_2SeO_4$) in the soil on the growth of garlic. Fresh weight were decreased with the application of higher concentration and longer period of Se compared with the control. The treatment of higher concentration and longer period of Se increased the content of Se in leaf sheath than bulb of garlic after 3 weeks. But, the Se content of garlic was higher in order of bulb, stem, root after 6 weeks of selenium treatment. Se was also detected also in control, the non-treated plot, but the amount was negligible. The content of selenium in the soil was not affected by the concentration and period of selenium application.