• Proceedings of the Korean Information Science Society Conference
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• 2012.06a
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• pp.194-196
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• 2012

본 논문은 비행체를 위한 실시간 운영체제의 태스크 스케줄링 기법을 제안한다. 기존의 기법은 다음 수행할 태스크를 선택하는 작업을 수행할 때 메모리 오버헤드 또는 일정한 시간 오버헤드가 발생하게 되며 일반적으로 이 둘은 트레이드 오프 관계로 고려된다. 제안하는 태스크 스케줄링 기법은 메모리 오버헤드를 최소화하면서도 우선 순위가 제일 높은 태스크를 찾는 작업을 별다른 연산 없이 수행함으로써 자주 발생하는 작업의 시간을 줄여 스케줄러 시간 오버헤드의 절약을 도모한다. 또한 이 방식은 태스크의 수가 많지 않으며 일정한 파티션된 OS를 주로 사용하는 비행체에 특히 적합하다.

• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.7
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• pp.846-853
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• 2016

This study prioritizes Noxious Liquid Substances (NLS) transported by sea via a risk-based database containing 596 chemicals to prepare against NLS incidents. There were 158 chemicals transported in Korean waters during 2014 and 2015, which were prioritized, and then chemicals were grouped into four categories (with rankings of 0-3) based on measures for preparedness against incident. In order to establish an effective preparedness system against NLS spill incidents on a national scale, a compiling process for NLS chemicals ranked 2~3 should be carried out and managed together with an initiative for NLS chemicals ranked 0-1. Also, it is advisable to manage NLS chemicals ranked 0-1 after considering the characteristics of NLS specifically transported through a given port since the types and characteristics of NLS chemicals relevant differ depending on the port. In addition, three designated regions are suggested: 1) the southern sector of the East Sea (Ulsan and Busan); 2) the central sector of the South Sea (Gwangyang and Yeosu); and 3) the northern sector of the West Sea (Pyeongtaek, Daesan and Incheon). These regions should be considered special management sectors, with strengthened surveillance and the equipment, materials and chemicals used for pollution response management schemes prepared in advance at NLS spill incident response facilities. In the near future, the risk database should be supplemented with specific information on chronic toxicity and updated on a regular basis. Furthermore, scientific ecotoxicological data for marine organisms should be collated and expanded in a systematic way. A system allowing for the identification Hazardous and Noxious Substances (HNS) should also be established, noting the relevant volumes transported in Korean waters as soon as possible to allow for better management of HNS spill incidents at sea.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.2
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• pp.137-143
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• 2018

As the elderly population grows, the use of assistive products that facilitate independent living by the elderly is increasing. Assistive product specialists are important to selecting the correct assistive products. Therefore, it is necessary to grasp the needs of assistive product users. This study was conducted to identify the key tasks that should be prioritized through analysis of the needs of assistive product users of assistive product specialist's job competence Questionnaires were administered to 84 assistive product users in person and by mail. The questionnaire was designed to investigate the importance of work and educational needs based on the job of the assistive product specialist. Based on the results, the priorities of five duties and 12 key tasks were derived. The key tasks are highly demanded by assistive product users and must be included in the performance of the job of the assistive product specialist. Based on this study, it is expected that elderly people will gain independence and improve their quality of life in their homes and communities through an individualized approach.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.49 no.2
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• pp.63-70
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• 2012

The collision-free flight planning method based on the extended collision map is proposed for cooperation of multiple unmanned aerial vehicles (UAVs) in a common 3-dimensional workspace. First, a UAV is modeled as a sphere, taking its 3-D motions such as rolling into consideration. We assume that after entering the common workspace, the UAVs move along their straight paths until they depart from the workspace, and that the priorities of the UAVs are determined in advance. According to the assumptions, the collision detection problem between two spheres in $R^3$ can be reduced into the collision detection problem between a circle and a line in $R^2$. For convenience' sake and safety, the collision regions are approximated by collision boxes. Using the collision boxes, the entrance times of the UAVs are scheduled for collision avoidance among the UAVs. By this way, all UAVs can move in the common workspace without collisions with one another. For verifying the effectiveness of the proposed flight planning method, the simulation with 12 UAVs is carried out.

• Journal of Navigation and Port Research
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• v.35 no.8
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• pp.657-665
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• 2011

This study deals with an integrated problem for deciding sequencing and storage location of export containers together at its receiving operation in the container terminal with a perpendicular layout. The preferred storage location of an export container varies with the priority of the corresponding loading operation and the waiting time of an external truck depends on its storage time. This paper proposes the mixed integer programming model considering the expected arrival time and expected finish time of an external truck and the preferred storage location for its loading operation. And we suggest the heuristic algorithm based on a simulated annealing algorithm for real world adaption. We compare the heuristic algorithm with the optimum model in terms of the computation times and total cost and the performance of the heuristic algorithm is analyzed through a numerical experiment.

• The Journal of Society for e-Business Studies
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• v.24 no.3
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• pp.99-110
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• 2019

As the 4th industrial revolution progressing, manufacturers are trying to apply intelligent information technologies such as IoT(internet of things) and machine learning. In the semiconductor/LCD/tire manufacturing process, schedule plan that minimizes setup change and due date violation is very important in order to ensure efficient production. Therefore, in this paper, we suggest the deep learning based scheduling generation model minimizes setup change and due date violation in parallel machines. The proposed model learns patterns of minimizing setup change and due date violation depending on considered order using the amount of historical data. Therefore, the experiment results using three dataset depending on levels of the order list, the proposed model outperforms compared to priority rules.

• Korean Journal of Construction Engineering and Management
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• v.5 no.2 s.18
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• pp.136-143
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• 2004

This study presents a risk management methodology using fuzzy theory for early construction stage and is focused on risk identification and risk analysis. This study identifies various risk factors associated with activities clearly construction stage, then establishes the Risk Breakdown Structure(RBS) by classifying the risks into the three groups; Common risks, risks for Earth works, and risks for Foundation works. The risk analysis method presented in this study is based on the RBS that has two levels such as upper level and lower level. The risk exposure of lower level risk factors is assessed by fuzzy inference. The weight of risks is estimated by fuzzy measure. Then, the estimated risk exposures and weights are aggregated to assess the risk exposure of upper level risks by Choquet fuzzy integral. The risk exposure of upper level risks determine the priority of risk factors in view of risk management. This study performs case study to validate the proposed method. The result of case study shows that the methodology suggested in this thesis would be utilized well in evaluating risk exposure.

• Proceedings of the Korea Society for Simulation Conference
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• 1992.10a
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• pp.2-2
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• 1992

최근 여러 분야에서 컴퓨터의 용도가 확산되고 더 높은 computing power에 대한 요구가 증가함에 따라, 컴퓨터의 성능을 향상시키기 위하여 프로세서의 고속화와 함께 시스템 구조의 개선을 위한 많은 연구가 진행되고 있다. 한 시스템내에 여러 개의 CPU들이 존재하는 다중프로세서 시스템(multiprocessor system) 구조를 가진 슈퍼미니급 중형 컴퓨터들은 상호연결망으로서 버스(bus) 방식을 많이 채택하고 있다. 버스 구조는 하드웨어가 간단하여 구현이 용이하지만, 여러 개의 시스템 지원들(프로세서들, 기억장치 모듈들 및 입출력 모듈들)이 버스를 공유하기 때문에 경합으로 인한 지연 시간이 발생하게 된다. 이러한 지연 시간으로 인한 성능 저하를 개선하는 방법으로는 버스 수의 증가와 최적 통제 프로토콜의 설계가 있다. 본 연구에서는 여러 개의 버스를 가진 다중프로세서 시스템에서 4가지 대표적인 버스 중재 프로토콜들에 대해 성능을 분석, 비교하여 최적 프로토콜을 제시하고자 한다. 이러한 대규모 하드웨어에 의하여 구현되는 시스템에서 주요 설계 요소들에 따른 시스템 성능 분석과 비교는 설계 단계에서 필수적인 과정이다. 그러나 하드웨어를 만들어서 분석하는 방법은 시간과 비용이 많이 소요되기 때문에 소프트웨어 시뮬레이션 방법이 널리 사용되고 있다. 본 연구팀에서는 시뮬레이션 전용언어인 SLAM II를 이용하여 다중프로세서 시스템의 시뮬레이터를 개발하고, 버스중재 프로토콜(bus arbitration protocol)을 용이하게 변경할 수 있도록 하여 각각의 성능을 비교하였다. 이 연구에서 비교된 프로토콜들은 고정-우선순위 방식(fixed-priority scheme), FIFO(first-in first-out) 방식, 라운드-로빈 방식(round-robin scheme), 및 회전-우선순위 방식(rotating-priority scheme) 등이다. 실험은 시스템의 주요 요소들인 프로세서와 기억장치 모듈 및 버스의 수들을 변경시킴으로써 다양한 시스템 환경에 대한 분석을 시도하였다. 작업 부하가 되는 기하장치 액세스 요구간 시간가격(inter-memory access request time interval)은 필요에 따라서 고정값 또는 확률 분포함수를 사용하였다. 특히, 실행될 프로그램의 특성에 따라 각 프로토콜의 성능이 다르게 나타날 수 있음을 검증하였으며, 기억장치의 지역성(memory locality)에 대한 프로토콜들의 성능도 비교하였다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.6
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• pp.2021-2029
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• 2010

This paper suggested the method to design and analyze FMC robot's dispatching rule using the Simulation and Sequential Patterns. To do this, first of all, we built FMC using simulation and then, extracted signals that facilities call a robot, saved it as the log type. Secondly, we built robot's optimal path using the Sequential Pattern Mining with the results of analyzing the log and relationship between machine and robot actions. Lastly, we adapted it to the A corp.'s manufacturing line for verifying its performance. As a result of applying the new dispatching rule in FMC, total throughput and total flow time decrease because of decreasing material loss time and increasing robot utility. Furthermore, because this method can be applied for every manufacturing plant using simulation, it can contribute to advance total FMC efficiency as well.

• Journal of Korea Multimedia Society
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• v.5 no.4
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• pp.372-385
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• 2002

In this paper, we propose an efficient buffer replacement method for the real-time multimedia data. The proposed method has multi level priority to consider the real-time characteristics. Each priority level is divided into a cold data set that is likely to be referenced for the first time and a hot data set that is likely to be re-referenced. An operation to select the victim data is sequentially executed from the cold set with the minimum priority level to the hot set with the maximum Priority level. It is chosen only at the lower level than or equal to the priority of the transaction that requests a buffer allocation. In the cold set, our method selects a media that has the maximum size in the level for a target of victim first of all. And in the hot set, our method selects a medium that has the maximum interval of the reference first of all. Since it maintains many popular media in the limited buffer space, the buffer hit ratio is increased. It also manages many service requests. As a result, our method improves the overall performance of the system. We compare the proposed method with the Priority-Hints method in terms of the buffer hit ratio and the deadline missing ratio of transactions. It is shown through the performance evaluation that our method outperforms the existing methods.