• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권6호
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• pp.2644-2657
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• 2018

To utilize the energy of sensor nodes efficiently and extend the network lifetime maximally is one of the primary goals in wireless sensor networks (WSNs). Thus, designing an energy-efficient protocol to optimize the determination of cluster heads (CHs) in WSNs has become increasingly important. In this paper, we propose a novel energy-efficient protocol based on an improved Grey Wolf Optimizer (GWO), which we refer to as Fitness value based Improved GWO (FIGWO). It considers a fitness value to improve the finding of the optimal solution in GWO, which ensures a better distribution of CHs and a more balanced cluster structure. According to the distance to the CHs and the BS, sensor nodes' transmission distance are recalculated to reduce the energy consumption. Simulation results demonstrate that the proposed approach can prolong the stability period of the network in comparison to other algorithms, namely by 31.5% in comparison to SEP, and even by 57.8% when compared with LEACH protocol. The results also show that the proposed protocol performs well over the above comparative protocols in terms of energy consumption and network throughput.

• 디지털산업정보학회논문지
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• 제12권3호
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• pp.231-257
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• 2016

Several efforts to replace the use of existing fossil energy resources have already been made around the world. As a result, a new industry of renewable energy has been created, and efficient energy distribution and storage has been promoted intensively. Among the newly explored renewable energy sources, the most widely used one is solar energy generation, which has a high market potential. An energy storage system (ESS) is a system as required. In this paper, the design and implementation of an ESS for the efficient use of power in stand-alone street lights is presented. In current ESS applied to stand-alone street lights, either 12V~24V DC (from solar power) or 110V~220V AC (from commercial power) is used to recharge power in systems with lithium batteries. In this study, an ESS that can support both solar power and commercial power was designed and implemented; it can also perform emergency recharge of portable devices from solar powered street lights. This system can maximize the scalability of ESSes using lithium batteries with efficient energy conversion, with the advantage of being an eco-friendly technology. In a ripple effect, it can also be applied to smart grids, electric vehicles, and new, renewable storage markets where energy storage technology is required.

• 인터넷정보학회논문지
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• 제9권3호
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• pp.79-90
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• 2008

본 논문은 전문가시스템 기법인 전향추론 기법을 이용하여 프로야구의 효율적인 선발 라인업 시스템을 설계 및 구현한다. 지식베이스는 선수 286명 148개 평가 항목으로 구성되어 있으며, 선수들의 경쟁력을 포인트로 평가하였다. 1차 포인트는 정적인 정보에 의해 산출된 포인트이며, 2차 포인트는 동적인 정보에 의해 산출된 포인트이다. 1, 2차 포인트를 통해 종합 포인트가 산출된다. 이를 이용하여 주어진 환경과 상대에 대한 효율적인 라인업 시스템 구현한다.

• 한국항해항만학회지
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• 제36권9호
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• pp.741-751
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• 2012

This article analyzes the interdependency between nonrenewable marine sand resources and renewable fishery resources by the developed dynamic bioeconomic model. The developed bioeconomic model is applied to a case study of efficient sustainable management for marine sand mining, which adversely affects a valuable blue crab fishery and its habitat in Korea. The socially-efficient extraction plan for marine sand and the time-variant environmental external costs to society in terms of diminished harvest rate of blue crab are determined. To take into account long-term effects from destroyed fishery habitat, a Beverton-Holt age structure model is integrated into the bioeconomic model. The illustrative results reveal that the efficient sand extraction plan is dynamically constrained by the stock size of the blue crab fishery over time. Thus, the dynamic environmental external cost is more realistic resource policy option than the classical fixed external cost for determining socially optimal extraction plans. Additionally, the economic value of bottom habitat, which supports the on- and off-site commercial blue crab fishery is estimated. The empirical results are interpreted with emphasis on guidelines for management policy for marine sand mining.

• 드라이브 ㆍ 컨트롤
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• 제20권4호
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• pp.92-99
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• 2023

Autonomous vehicles should recognize and respond to the specified speed to drive in compliance with regulations. To recognize the specified speed, the most representative method is to read the numbers of the signs by recognizing the speed signs in the front camera image. This study proposes a method that utilizes YOLO-Labeling-Labeling-EfficientNet. The sign box is first recognized with YOLO, and the numeric digit is extracted according to the pixel value from the recognized box through two labeling stages. After that, the number of each digit is recognized using EfficientNet (CNN) learned with the virtual environment dataset produced directly. In addition, we estimated the depth of information from the height value of the recognized sign through regression analysis. We verified the proposed algorithm using the virtual racing environment and GTSRB, and proved its real-time performance and efficient recognition performance.

• 한국정보과학회논문지:정보통신
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• 제29권4호
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• pp.368-374
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• 2002

UMTS와 같은 제 3세대 이동 통신 시스템에서의 value-added 서비스를 위한 중요한 점은 이동 사용자로부터의 지불을 받을 수 있는 지의 여부를 검사하는 것이다. 기존의 value-added 서비스를 위한 인증 및 지불 프로토콜은 사용자의 인증 기관의 역할을 해주는 온-라인(on-line) TTP에 의존하고 있다. 그러나 3 세대 이동 통신 시스템에서의 수많은 서비스 제공자들, 다양한 종류의 서비스들, 그리고 넓은 사용자 계층 등을 고려할 때 온-라인 TTP에 기반한 인증과 지불 기법은 실용적이지 못하다. 본 논문에서는 3 세대 이동 통신 시스템에서의 value-added 서비스를 위하여 티켓(ticket)을 이용하여 인증 및 지불 프로토콜을 제안한다. 제안한 티켓 기반 인증 및 지불 프로토콜은 온-라인 TTP와의 통신 없이 사용자의 비용 지불 여부를 확인할 수 있는 효율적인 방법을 제공한다. 또한 티켓에 기반한 제안된 프로토콜은 이동 사용자의 서비스 사용에 대한 익명성을 보장 할 수 있다.

• 한국산학기술학회논문지
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• 제19권9호
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• pp.446-453
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• 2018

본 연구는 특수관계자간 거래가 기업가치에 미치는 영향을 패널자료회귀모형을 이용하여 분석하였다. 즉 한국기업의 특수관계자간 거래가 효율적 거래가설과 이해상충의 가설을 지지하는가를 검증하였다. 특수관계자간 거래의 유형은 장기공급계약, 자산 및 영업양수도, 대여금, 지분출자, 신용공여 등 다섯 가지를 고려하였다. 특수관계자간 거래가 기업의 효율성을 증가시키기 위한 목적으로 이루어진다면 특수관계자간 거래는 기업가치에 긍정적인 영향을 미치게 된다. 반면에 지배주주의 사익을 추구하기 위해 터널링 목적으로 이루어진다면 기업가치에 부정적인 영향을 나타내게 된다. 본 연구의 실증분석 결과를 요약하면 다음과 같다. 첫째, 다섯 가지 특수관계자간 거래 형태 중에서 대여금, 지분출자, 신용공여는 기업가치에 부정적인 영향을 미치는 것으로 나타나서 이해상충의 가설을 지지하는 결과를 보였다. 즉 대여금이나 지분출자, 신용공여 등과 같은 특수관계자와의 재무적 거래는 지배주주의 사익추구 목적으로 이루어질 가능성이 높은 것으로 이해되었다. 둘째, 장기공급계약과 자산 및 영업양수도 형태의 특수관계자간 거래는 기업가치와 유의한 영향관계를 확인할 수 없었다. 따라서 장기공급계약이나 자산 및 영업양수도 형태의 특수관계자간 거래는 효율적 거래 목적으로 이루어지는 것인지 혹은 지배주주의 사익추구 목적으로 이루어지는 것인지 명확하지 않았다.

• 한국경영과학회지
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• 제12권2호
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• pp.42-50
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• 1987

This objective of this paper is to develop an efficient method with small memory requirement for a feed-mixing problem on a micro computer. First this method uses the decomposition principle to reduce the memory requirement. Next, the decomposition principle is modified to fit the problem. Further four different variations in solving subproblems are designed in order to improve efficiency of the principle. According to the test with respect to the processing time, the best variation is such that the dual simplex method is used, and the optimal basis of a previous subproblem is used as an initial basis, and the master problem is (M +1) dimensional. In general, the convergence of solution becomes slower near the optimal value. This paper introduces a termination criterion for a sufficiently good solution. According to the test, 5%-tolerence is acceptable with respect to the relation between the processing time and optimal value.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2005년도 International Meeting on Information Displayvol.II
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• pp.1092-1095
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• 2005

The effect of the dielectric constant (${\varepsilon}$) of bonding materials in screen-printed carbon nanotube cathode on field enhancement factor was investigated using the ANSYS software for high-efficient CNT-cathodes. The field enhancement factor increased with decreasing the dielectric constant and reaching a maximum value when the dielectric constant is 1, the value for a vacuum. This indicates that the best bonding materials for screen-printing CNT cathodes should have a low dielectric constant and this can be used as criteria for selecting bonding materials for use in CNT pastes for high-efficient CNT-cathodes

• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제18권1호
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• pp.61-74
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• 2014

This paper presents accurate and efficient numerical methods for calculating the sensitivities of two-asset European options, the Greeks. The Greeks are important financial instruments in management of economic value at risk due to changing market conditions. The option pricing model is based on the Black-Scholes partial differential equation. The model is discretized by using a finite difference method and resulting discrete equations are solved by means of an operator splitting method. For Delta, Gamma, and Theta, we investigate the effect of high-order discretizations. For Rho and Vega, we develop an accurate and robust automatic algorithm for finding an optimal value. A cash-or-nothing option is taken to demonstrate the performance of the proposed algorithm for calculating the Greeks. The results show that the new treatment gives automatic and robust calculations for the Greeks.