• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.5
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• pp.1790-1806
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• 2015

Utility-based routing is a special type of routing approach using a composite utility metric when making routing decisions in ad hoc and sensor networks. Previous studies on the utility-based routing all use fixed retry limit and a very simple distance related energy model, which makes the utility maximization less efficient and the implementation separated from practice. In this paper, we refine the basic utility model by capturing the correlation of the transmit power, the retry limit, the link reliability and the energy cost. A routing algorithm based on the refined utility model with adaptive transmit power and retry limit allocation is proposed. With this algorithm, packets with different priorities will automatically receive utility-optimal delivery. The design of this algorithm is based on the observation that for a given benefit, there exists a utility-maximum route with optimal transmit power and retry limit allocated to intermediate forwarding nodes. Delivery along the utility-optimal route makes a good balance between the energy cost and the reliability according to the value of the packets. Both centralized algorithm and distributed implementations are discussed. Simulations prove the satisfying performance of the proposed algorithm.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.1612-1615
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• 2009

Water supply reliability indexes (WSRI) is estimated for assessment of water supply capacity in the downstream for parallel reservoir system in Nakdong River, South Korea, using allocation rule (AR) according to the water supply capacity of each reservoir and the characteristic of parallel reservoir system. The result of the analyzing parallel reservoir system for Andong and Imha reservoir in Nakdong River does not include evidences available enough to decide whether the results of water supply analysis are excellent in the current reliability evaluation or not. However, AR (C) shows a good result in the water supply capacity for each reservoir based on the connected operation system and the total water supply capacity at the control point of downstream by the average water supply capacity and possible range of water supply capacity suggested by this study. The average water supply capacity is analyzed by the reliability of monthly average water supply capacity. Furthermore, the possible range of water supply capacity is estimated by the standard deviation when water deficit occurs. Therefore, AR (C) is useful to establish and estimate the planning water supply capacity according to the monthly water supply condition and the possible range of water supply capacity when the water supply capacity deficit occurs, South Korea.

• Journal of Applied Reliability
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• v.1 no.1
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• pp.1-8
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• 2001

Redundancy allocation problems have been considered at single-level systems and it may be the best policy in some specific situations, but not in general. With regards to reliability, it is most effective to allocate the lowest objects, because parallel-series systems are more reliable than series-parallel systems. However, the smaller and lower in the system an object is, the more time and accuracy are needed for duplicating it, and so, the cost can be decreased by using modular redundancy Therefore, providing redundancy at high levels like as modules or subsystems, can be more economical than providing redundancy at low levels or duplicating components. In this paper, the problem in which redundancy is allocated at all level in a series system is addressed, a mixed integer nonlinear programming model is presented and a genetic algorithm is proposed. An example illustrates the procedure.

• Proceedings of the KSR Conference
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• 2001.10a
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• pp.370-375
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• 2001

This paper is to suggest reliability modeling and analysis method of Electric Multiple Unit (EMU). It is necessary to identify subsystem/equipments of EMU and functional interfaces between subsystems in order to carry out reliability modeling of EMU properly. After identifying subsystem/equipments and functional interface, reliability allocation is performed using ARINC method. Reliability target of system/subsystems is verified in revenue service during the proper periods.

• Journal of Korean Institute of Industrial Engineers
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• v.41 no.4
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• pp.396-407
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• 2015

The literature about intelligence assets allocation focused on mainly single or partial assets such as TOD and GSR. Thus, it is limited in application to the actual environment of operating various assets. In addition, field units have generally vulnerabilities because of depending on qualitative analysis. Therefore, we need a methodology to ensure the validity and reliability of intelligence asset allocation. In this study, detection probability was generated using digital geospatial data in MGIS (Military Geographic Information System) and simulation logic of BCTP (Battle Commander Training Programs) in the R.O.K army. Then, the optimal allocation mathematical model applied concept of simultaneous integrated management, which was developed based on the partial set covering model. Also, the proposed GA (Genetic Algorithm) provided superior results compared to the mathematical model. Consequently, this study will support effectively decision making by the commander by offering the best alternatives for optimal allocation within a reasonable time.

• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.1176-1181
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• 2006

The purpose of this study was to estimate water supply analysis and reliability indicators by using allocation rule(AR) about Andong Dam and Imha Dam which have parallel reservoirs system. According to the analysis results of allocation rule, for Rule(A) and Rule(B), the contribution of water supply in Andong Dam was 60% more than in Imha Dam, and for Rule(C), the contributions in Andong Dam and Imha Dam were almost equal. In Rule(C), supply is allocated by the ratio which divides the sum of storage and inflow by the mean storage according to the storage state and supply capability state of Andong Dam and Imha Dam. This Rule(C) showed good results in the water supply capability analysis and reliability analysis of parallel reservoirs. In the analysis criteria of water supply in parallel reservoirs system, monthly water change quantity showed better results than monthly constant water quantity in water supply analysis. On the basis of this study, the new technique for water supply analysis was developed to be applied to parallel reservoirs, and this operation rule will establish the efficient operation measures in the application to several kinds of parallel reservoirs system.

• Proceedings of the Korean Reliability Society Conference
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• 2001.06a
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• pp.513-520
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• 2001

신규개발장비에 대하여 사용자가 제시한 RAM-D 요구조건을 만족하기 위한 하부 체계의 RAM-D 설계목표 설정 절차 및 방법에 대하여 기동무기체계의 대표적 장비인 전차를 대상으로 연구하여 RAM-D 요소별 할당 모델을 개발하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.16 no.10
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• pp.3256-3274
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• 2022

With the rapid development of information and communications technology, the construction of efficient, reliable, and safe Internet of Things (IoT) is an inevitable trend in order to meet high-quality demands for the forthcoming 6G communications. In this paper, we study a secure intelligent reflecting surface (IRS)-assisted IoT system where malicious eavesdropper trying to sniff out the desired information from the transmission links between the IRS and legitimate IoT devices. We discuss the system overall performance and propose a hybrid resource allocation scheme for maximizing the secrecy capacity and secrecy energy efficiency. In order to achieve the trade-off between transmission reliability, communication security, and energy efficiency, we develop a quantum-inspired marine predator algorithm (QMPA) for realizing rational configuration of system resources and prevent from eavesdropping. Simulation results demonstrate the superiority of the QMPA over other strategies. It is also indicated that proper IRS deployment and power allocation are beneficial for the enhancement of system overall capacity.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.4
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• pp.8-12
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• 2009

We propose BMPA(balanced multimedia packet allocation) scheme. This scheme considers the issue of optimal sub-carrier allocation in OFDMA multicast system. When RT(real time) packets and NRT(non-real time) packets arrive at the same time, BMPA scheme gives higher weight to RT packets than NRT packets and then, it allocates sub-carriers according to the total weight sum of packets in each user. This process acts as both packet scheduler and sub-carrier allocation. Therefore, each user receives multimedia packets with reliability. With simulation results, it shows that BMPA scheme ensures long-term system throughput and, in average RT packet delay, BMPA scheme greatly outperforms multi-user water-filling algorithm.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.3
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• pp.1111-1130
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• 2016

Cooperative communications can significantly improve the wireless transmission performance with the help of relay nodes. In cooperative communication networks, relay selection and power allocation are two key issues. In this paper, we propose a relay selection and power allocation scheme RS-PA-PSACO (Relay Selection-Power Allocation-Particle Swarm Ant Colony Optimization) based on PSACO (Particle Swarm Ant Colony Optimization) algorithm. This scheme can effectively reduce the computational complexity and select the optimal relay nodes. As one of the swarm intelligence algorithms, PSACO which combined both PSO (Particle Swarm Optimization) and ACO (Ant Colony Optimization) algorithms is effective to solve non-linear optimization problems through a fast global search at a low cost. The proposed RS-PA-PSACO algorithm can simultaneously obtain the optimal solutions of relay selection and power allocation to minimize the SER (Symbol Error Rate) with a fixed total power constraint both in AF (Amplify and Forward) and DF (Decode and Forward) modes. Simulation results show that the proposed scheme improves the system performance significantly both in reliability and power efficiency at a low complexity.