• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.8
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• pp.1-7
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• 2010

The reliability of a power system has close relationship with the maintenance of the distribution systems. This paper presents the method of the maintenance planning of the distribution systems by minimizing the interruption cost. The interruption cost for the equipment failures is formulated using time varying failure rate and minimized by optimization of the object function. The proposed method provides the priority list for the investment of the maintenance subject to the limited investment budget by the economic analysis. In order to test the proposed method, the modified distribution system of a rural area is introduced for the testing system. Test results show that the proposed method is good enough by evaluating the improvement of the reliability of the power system.

• Proceedings of the Korea Multimedia Society Conference
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• 2000.11a
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• pp.45-48
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• 2000

본 논문은 현재 고성능 가역압축 부호화의 표준이 되는 JPEG-LS의 예측오차에 대한 확률분포를 결정하는 컨텍스트 모델링(context modelling)에서 컨텍스트 정수의 결정 방법에 관해 기술한다. 먼저, 압축률 향상을 위해 낮은 대비(low contrast)를 적용하는 전처리 과정을 도입한다. 둘째로, 낮은 복잡도(low complexity)를 위해 주목화소와 주변화소 사이의 차분을 양자화하고, 그 값 Q$_1$,Q$_2$, Q$_3$로부터 컨텍스트 정수(Q)의 결정을 위해 우선 순위를 정한 후, 3차원 가상좌표 위로의 할당을 고려한다. 또한, 제안 방법과 JPEG-LS의 near-lossless부분을 비교하여, 다양한 영상에 대하여 적용시켜 본 결과, 제안한 방법의 압축률과 손실이득이 훨씬 좋음을 보인다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.6
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• pp.648-653
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• 2011

In this paper, coordinated space division multiple access(SDMA) technology is proposed to mitigate inter-cell interference by using partial channel state information in cooperative wireless communications system with limited feedback. Each AT selects an optimal cluster transmission mode and sends it back to a cluster scheduler, and at the cluster scheduler, ATs are scheduled within a AT group with the identical cluster transmission mode, and the optimal transmission mode and the corresponding scheduled ATs are determined to maximize scheduling priority. Also, in order to enhance multiuser diversity gain, an extended transmission feedback method is proposed to feed back multiple preferred cluster transmission modes at each AT. It is shown that the proposed coordinated SDMA scheme outperforms existing non-coordinated SDMA schemes in terms of the average system throughput.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.4
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• pp.394-401
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• 2013

Recently there have been much interest in the performance improvement of maritime communication system. In the maritime communication system, the wireless channel is likely to be time-invariant and the retransmission scheme is not proper because it does not provide time diversity. For the improvement of reliability, we consider MIMO ARQ scheme using Alamouti-type signal which can provide space and time diversity. In this paper, we also propose the criterion of optimal retransmission order and provide its performance of error probability and packet throughput. The proposed MIMO ARQ scheme with optimal retransmission order has performance gain over random ordered MIMO ARQ and conventional Chase combining method. Therefore we expect that it can be adapted to the next generation maritime communication system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.2A
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• pp.191-197
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• 2008

For the efficient transmission of burst data in the time varying wireless channel, opportunistic scheduling is one of the important techniques to maximize multiuser diversity gain. In this paper, we propose a distributed opportunistic scheduling scheme for wireless LAN network. A proportional fair scheduling, which is one of the opportunistic scheduling schemes, is used for centralized networks, whereas we design distributed proportional fair scheduling (DPFS) scheme and medium access control with distributed manner. In the proposed DPFS scheme, each receiver estimates channel condition and calculates independently its own priority with probabilistic manner, which can reduce excessive probing overhead required to gather the channel conditions of all receivers. We evaluate the proposed DPFS using extensive simulation and simulation results show that DPFS obtains higher network throughput than conventional scheduling schemes and has a flexibility to control the fairness and throughput by controlling the system parameter.

• Proceedings of the Korean Professional Engineer Association Conference
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• 1996.12a
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• pp.76-102
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• 1996

북한은 전력부족난과 전기품질의 저하로 인하여 주요 생산기업에 지장을 주고 있으며, 노후 발전소의 성능저하도 함께 진행되고 있는 것으로 추정된다. 이에 대한 적절한 대책이 없는 한 그 상황은 더욱 악화될 전망이다. 한반도 에너지 개발기구(KEDO)가 추진하고 있는 경수로 원자력 발전기가 6～7년 후에 준공된다고 해도 이처럼 불안정한 전력계통에 병입되어 원활한 운전이 가능할런지 기대하기 곤란하다. 이러한 실정에서 \circled1 전력부족으로 주파수가 저하될 때 우선 순위가 낮은 부하를 제한하는 자동 부하제한 방식을 포함한 자동 주파수 제어 계통개선 \circled2 기존발전소 성능과 이용을 향상을 위한 재가동(Repowering) 등의 리 엔지니어링 \circled3 가스터빈 복합화력과 열병합발전(Co-generation) 등과 같이 건설기간이 짧고 비용이 적게 들며 송전 설비 건설도 불필요한 분산형 전원의 건설 \circled4 수력발전소와 조력발전소의 건설 \circled5 양수발전 등 전력에너지 저장설비의 개발 \circled6 송전전압격상과 배전방식개선 및 종합전력정보시스템 구축 \circled7 남ㆍ북한 전력계통 내지는 동북아시아 전력계통을 연계하는 평화망사업(Peace Network Project)등의 추진이 경수로 사업에 선행되어야 한다. 특히 러시아, 중국, 한국, 일본의 발전 에너지원 분포와 년간 부하곡선을 고려할 때 동북아시아 전력계통의 연계는 관련국 상호간에 에너지 환경과 경제적 측면에서 상당한 이득과 안정성을 강화해 줄 것이며, 기술발전과 평화공존에 크게 기여 할 것이다. 이를 위하여 관련국의 전력계통연계 전문가들이 참여하는 남\ulcorner북한전력 계통연계연합회(Co-Pia ; Co-rea Power Systems Interconnection Association)와 동북아지역전력 계통연합회(Near Pia=North-Eastern Asia Region Power Systems Interconnection Association)의 구성을 제안하는 바이다. 주요용어(Key Words): 자동주파수 제어(AFC), 리엔지니어링(Re-Engineering), 분산형 전원(Dispersed Generation System), 전력저장(Power Storage), 부하조절기(Load Conditioner), 수요관리(DSM) 연계(Interconnection), 인터시스템(Intersystem), 통합자원계획(IRP), 안전성 강화(Security Enhancement), 전력시장개방(Electricity Free Maket), 통일비용(Unification Expense, Unification Cost), 남ㆍ북한전력계통연계연합회(Co-Pia), 동북아지역전력 계통연계연합회(Nea,-Pia).

• Journal of KIISE:Computer Systems and Theory
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• v.31 no.5_6
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• pp.347-352
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• 2004

This thesis deals with a task scheduling on a message-passing system. Scheduling and allocation are very important issues since the inappropriate scheduling of tasks cannot exploit the true potential of the system and it can offset the grain from parallelization. It is difficult to apply previous schemes to message-passing system, because previous schemes assume the shared memory system. This thesis proposes an modified priority function and processor selection technique that consider the problems caused by the difference between previous models and message-passing environments. The priority function includes the cumulative communication cost which causes task execution to be delayed. The processor selection technique avoids the situation that a child task is assigned to the same Processor allocated to its parent task that has other unscheduled child tasks. We showed by some simulations that our modified features of task scheduling algorithm can make the better scheduling results than the previous algorithms.

• Journal of Internet Computing and Services
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• v.22 no.3
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• pp.75-83
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• 2021

With the development of the IT industry and the increase of cultural activities, the demand for works increases, and they can be used easily and conveniently in an online environment. Accordingly, copyright infringement is seriously occurring due to the ease of copying and distribution of works. Some special types of Online Service Providers (OSP) use filtering-based technology to protect copyrights, but they can easily bypass them, and there are limits to blocking all illegal works, making it increasingly difficult to protect copyrights. Recently, most of the distributors of illegal works are a certain minority, and profits are obtained by distributing illegal works through many OSP and majority ID. In this paper, we propose a profiling technique for heavy uploader, which is a major analysis target based on illegal works. Creates a feature containing information on overall illegal works and identifies major heavy uploader. Among these, clustering technology is used to identify heavy uploader that are presumed to be the same person. In addition, heavy uploaders with high priority can be analyzed through illegal work Distributor tracking and behavior analysis. In the future, it is expected that copyright damage will be minimized by identifying and blocking heavy uploader that distribute a large amount of illegal works.

• The Korean Journal of Air & Space Law and Policy
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• v.29 no.1
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• pp.199-236
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• 2014

This paper analyses from the perspective of distributive justice the legal mechanisms for international allocation of orbital slots, which are of co-owned nature and thereby limited natural resources in outer space. The allocative function is delegated to the International Telecommunication Union. The Radio Regulation, amongst such other legal instruments as the Constitution and Convention, by which the ITU and contracting States thereof abides, dictates how the orbital positions are distributed. Thus, the RR is thoroughly reviewed in the essay. The mechanisms are in a broad sense categorized into two systems: 'a posteriori system' where the 'first come, first served' principle prevails; and 'a priori system' designed to foster the utilisation of the slots by those who lack space resources and are, in especial, likely to be marginalised under the former system. The argument proceeds on the premise that a posteriori system places the under-resourced States in unfavourable positions in the securement of the slots. In contrast with this notion, seven factors were instantiated for an assertion that the degradation of the distributive justice derived from the 'first come, first served' rule, which lays the foundation for the system, could be either mitigated or counterbalanced by the alleged exceptions to the rule. However, the author of this essay argues for counterevidences against the factors and thereby demonstrating that the principle still remains as an overwhelming doctrine, posing a threat to the pursuit of fair allocation. The elements he set forth are as in the following: 1) that the 'first come, first served' principle only applies to assignments capable of causing harmful interferences; 2) the interoperability of the principle with the 'rule of conformity' with the all the ITU instruments; 3) the viability of alternative registrations, as an exception of the application of the principle, on the condition of provisional and informational purposes; 4) another reference that matters in deciding the priority: the types of services in the TFA; 5) the Rule of Procedure H40 proclaiming a ban on taking advantage of coming first to the Register; 6) the technical factors and equity-oriented norms under international and municipal laws along with; 7) the changes of 'basic characteristics' of registered assignments. The second half of this essay illustrates by examining the relevant Annexes to the Regulation that the planned allocation, i.e., a priori system, bear the structured flaws that hinder the fulfillment of the original purpose of the system. The Broadcasting and Fixed Satellite Systems are the reviewed Plans in which the 'first come, first served' principle re-emerges in the end as a determining factor to grant the 'right to international recognition' to administrations including those who has not the allotted portions in the Plan.