• 대한산업공학회지
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• 제21권4호
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• pp.541-553
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• 1995

An efficient algorithm is proposed for a buffer allocation in a continuous flow line. The problem is formulated as a non-linear programming with linear constraints. The concept of pseudo gradient and gradient projection is employed in developing the algorithm. Numerical experiments show that the algorithm gives the actual optimal solutions to the problems with single linear constraint limiting the total buffer capacity. Also, even in longer production lines, it gives quite good solutions to the problems with the general linear resource constraints within a few seconds.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권10호
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• pp.4738-4758
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• 2017

Resource allocation plays a crucial role in multiuser multiple input multiple output orthogonal frequency division multiplexing (MIMO-OFDM) systems to improve overall system performance. While previously proposed resource allocation algorithms are mainly designed from the point of view of the information-theoretic, we formulate the resource allocation problem as an average bit error rate (BER) minimization problem subject to a total power constraint when considering employing realistic MIMO detection techniques. Subsequently, we derive the optimal subcarrier and power allocation algorithms for three types of well-known MIMO detectors, including the maximum likelihood (ML) detector, linear detectors, and successive interference cancellation (SIC) detectors. To reduce the complexity, we also propose a two-step suboptimal algorithm that separates subcarrier and power allocation for each detector. We also analyze the diversity gain of the proposed suboptimal algorithms for various MIMO detectors. Simulation results confirm that the proposed suboptimal algorithm for each detector can achieve a comparable performance with the optimal allocation with a much lower complexity. Moreover, it is shown that the suboptimal algorithms perform better than the conventional algorithms that are known in the literature.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권12호
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• pp.5943-5962
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• 2017

A resource allocation algorithm based on simultaneous wireless information and power transfer (SWIPT) to maximize the system throughput is proposed in orthogonal frequency division multiplexing (OFDM) relay networks. The algorithm formulates the problem under the peak power constraints of the source and each subcarrier (SC), and the energy causality constraint of the relay. With the given SC allocation of the source, we give and prove the optimal propositions of the formulated problem. Then, the formulated problem could be decomposed into two separate throughput maximization sub-problems by setting the total power to transfer energy. Finally, several SC allocation schemes are proposed, which are energy priority scheme, information priority scheme, balanced allocation scheme and exhaustive scheme. The simulation results reveal that the energy priority scheme can significantly reduce computational complexity and achieve approximate performance with the exhaustive scheme.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2012년도 추계학술대회
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• pp.1012-1014
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• 2012

집적 영상 (integral imaging) 기술은 렌즈배열을 이용하여 3D 영상을 공간상에 표시할 수 있어서 차세대 유망 3D 디스플레이 기술 중에 하나이다. 집적 영상 시스템의 성능은 디스플레이 장치, 렌즈 배열, 이미징 광학 장비 등에 매우 의존적이다. 본 논문에서는 제한된 리소스에서 집적 영상 시스템의 해상도 분석을 수행하는 해석 방법을 제안한다. 제안하는 방법을 통하여 해상도 측면에서 최적화된 집적 영상 시스템 설계를 수행할 수 있다. 제안하는 방법의 유용함을 위하여 Monte Carlo 시뮬레이션을 수행하고 그 결과를 보고한다.

• 정보과학회 컴퓨팅의 실제 논문지
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• 제22권1호
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• pp.1-7
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• 2016

동일하지 않은 주기와 시작 시간을 가지는 여러 개의 어플리케이션을 멀티프로세서 시스템에서 동시에 수행하면 어플리케이션 간의 간섭이 발생하게 되고, 이에 따라 각 어플리케이션이 실시간 시간 제약을 만족시키는지에 대한 보장이 어려워진다. 본 연구에서는 데이터 플로우 어플리케이션을 대상으로 하여, 주어진 시간 제약 조건을 지키면서 프로세서를 공유할 수 있도록 하는 간섭 분석 모델을 제안하였다. 그리고 이 기법을 바탕으로 여러 개의 어플리케이션들이 프로세서 공유를 통하여 자원사용량을 최소화하는 스케줄링 방법을 제안하였다. 그리하여 태스크 그래프를 실시간 태스크로 변환하여 스케줄 하는 최근의 동시 스케줄링 기법과 비교해보았을 때, 어플리케이션의 반응시간 제약이 빠듯할 때 제안한 기법이 더 적은 자원을 사용하는 스케줄을 생성함을 실험을 통해 확인하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권5호
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• pp.2177-2193
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• 2018

This paper studies resource allocation schemes for the relay-aided cooperative system consisting of multiple source-destination pairs and decode-forward (DF) relays. Specially, relaying selection, multisubcarrier pairing and assignment, and power allocation are investigated jointly. We consider a combinatorial optimization problem on quality of experience (QoE) and energy consumption based on relay-aided cooperative system. For providing better QoE and lower energy consumption we formulate a multi-objective optimization problem to maximize the total mean opinion score (MOS) value and minimize the total power consumption. To this end, we employ the nondominated sorting genetic algorithm version II (NSGA-II) and obtain sets of Pareto optimal solutions. Specially, two formulas are devised for the optimal solutions of the multi-objective optimization problems with and without a service priority constraint. Moreover, simulation results show that the proposed schemes are superior to the existing ones.

• 인터넷정보학회논문지
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• 제23권2호
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• pp.1-7
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• 2022

Machine learning (ML) algorithms have been intended to seamlessly collaborate for enabling intelligent networking in terms of massive service differentiation, prediction, and provides high-accuracy recommendation systems. Mobile edge computing (MEC) servers are located close to the edge networks to overcome the responsibility for massive requests from user devices and perform local service offloading. Moreover, there are required lightweight methods for handling real-time Internet of Things (IoT) communication perspectives, especially for ultra-reliable low-latency communication (URLLC) and optimal resource utilization. To overcome the abovementioned issues, this paper proposed an intelligent scheme for traffic steering based on the integration of MEC and lightweight ML, namely support vector machine (SVM) for effectively routing for lightweight and resource constraint networks. The scheme provides dynamic resource handling for the real-time IoT user systems based on the awareness of obvious network statues. The system evaluations were conducted by utillizing computer software simulations, and the proposed approach is remarkably outperformed the conventional schemes in terms of significant QoS metrics, including communication latency, reliability, and communication throughput.

• 가족자원경영과 정책
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• 제4권2호
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• pp.57-73
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• 2000

The Purpose of this study is to scrutinize the time structure and time use pattern of North Korean and to identify the differences of time use patterns between South and North Korean Societies. To carry out this Purpose in-depth interviews with ten people who escaped from North Korea after 1990 and empirical survey with 158 subjects were conducted. The findings are as follows. The characteristics of time life of North Korean are uniform time use pattern in tightly scheduled daily life and shortage of disposable time and constraint of free time due to job related labor, extra job activities including learning, meeting and evaluation, and labor mobilization. Women are faced with heavy burden of doing job and housework in the continuing patriarchal way of thinking and in the circumstances of poor housing environment. In North, Leisure time is constraint and leisure facilities are poor and the concept of leisure is totally different as that of South. North Korean think leisure as connecting with work and education and as public sphere, not private sphere. I this context leisure is considered as means for the strengthening of the communist society. Differences in the perception of time life through defectors are as follows. In South, there are plenty of leisure time and man can control his own time. Man spend his free time for various activities, especially for cultural activities such as sports, recreation, eating out with families and spend time till late in the outdoors. This study revealed differences in many aspects of time life between South and North Korean societies. These results will provide useful informations for the overcome of differences of cultural life of South and North Korean societies and accomplishment of the real integration of two societies.

• 한국통신학회논문지
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• 제39B권10호
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• pp.654-663
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• 2014

셀 커버리지 향상과 단위 면적당 무선 용량의 증대를 위해 셀룰러 이동 통신 시스템에 다양한 크기와 전송전력을 갖는 다수의 네트워크이 혼재하는 이기종 네트워크의 개념이 도입되고 있다. 본 논문에서는 이기종 네트워크의 하향링크에서 모든 셀이 동일한 무선 자원을 공유하고, 일부 소형 셀에서는 백홀 링크의 용량에 제한이 있는 경우를 고려한다. 이 때 모든 사용자의 주어진 트래픽을 정해진 시간 내에 전송해야 하는 QoS요구 사항을 만족시키면서 동시에 전체 시스템에서의 무선 자원 사용량을 최소화 시킬 수 있는 셀 선택 문제를 정식화하고, 그 최적 해를 찾기 위한 분산 알고리즘을 제안한다. 해당 알고리즘은 일부 소형셀의 백홀 링크에서 병목현상이 발생하였을 경우, 백홀 용량에 여유가 있는 인접 셀로 사용자를 오프로딩 하도록 동작함으로써 기존 방식과 대비할 때 제한된 무선 자원 및 백홀 링크 용량에 맞추어 더 많은 사용자의 QoS를 지원할 수 있음을 확인한다.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2023년도 학술발표회
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• pp.30-30
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• 2023

This study aims to establish the multi-reservoir operation system model in the Upper Mun River Basin which includes 5 main dams namely, Mun Bon (MB), Lamchae (LC), Lam Takhong (LTK), Lam Phraphoeng (LPP), and Lower Lam Chiengkrai (LLCK) Dams. The knowledge and AI technology were applied aiming to develop innovative prototype for SMART dam-reservoir operation in future. Two different sorts of reservoir operation system model namely, Fuzzy Logic (FL) and Constraint Programming (CP) as well as the development of rainfall and reservoir inflow prediction models using Machine Learning (ML) technique were made to help specify the right amount of daily reservoir releases for the Royal Irrigation Department (RID). The model could also provide the essential information particularly for the Office of National Water Resource of Thailand (ONWR) to determine the short-term and long-term water resource management plan and strengthen water security against flood and drought in this region. The simulated results of base case scenario for reservoir operation in the Upper Mun from 2008 to 2021 indicated that in the same circumstances, FL and CP models could specify the new release schemes to increase the reservoir water storages at the beginning of dry season of approximately 125.25 and 142.20 MCM per year. This means that supplying the agricultural water to farmers in dry season could be well managed. In other words, water scarcity problem could substantially be moderated at some extent in case of incapability to control the expansion of cultivated area size properly. Moreover, using AI technology to determine the new reservoir release schemes plays important role in reducing the actual volume of water shortfall in the basin although the drought situation at LTK and LLCK Dams were still existed in some periods of time. Meanwhile, considering the predicted inflow and hydrologic factors downstream of 5 main dams by FL model and minimizing the flood volume by CP model could ensure that flood risk was considerably minimized as a result of new release schemes.