• 한국산업정보학회논문지
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• 제22권1호
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• pp.23-32
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• 2017

본 논문에서는 이산시간 마코비안 도착과정(discrete-time Markovian arrival process, 이하 이산시간 MAP)을 갖는 대기행렬시스템의 주요성능척도들을 분석하기 위한 통합적 접근방법을 제시한다. 기존의 이산시간 MAP/G/1 대기행렬시스템의 연구들을 보면 동일한 시스템에 대하여 시스템 내 고객수와 대기시간 등을 분석할 때 서로 다른 방법으로 접근하였기에 이 둘을 동시에 살펴보고자 할 때는 추가적인 시간과 노력이 뒤따랐다. 따라서 하나의 시스템을 여러 방면에서 포괄적으로 분석할 수 있는 통합적인 접근방법은 시스템을 설계하고 관리하는 입장에서 볼 때 중요한 분석의 틀이 된다. 본 논문에서는 이산시간 MAP/G/1 시스템의 안정상태 일량 분포를 유도하고 이를 이용하여 임의고객의 대기시간, 체재시간 분포를 유도한다. 체재시간 분포로부터 이탈시점 고객수 분포를 구하고 이탈시점 고객수와 임의시점 고객수와의 관계로부터 고객수 분포를 유도한다.

• Communications for Statistical Applications and Methods
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• 제9권3호
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• pp.649-663
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• 2002

We consider an unlimited fluid queueing model which has Fractional Brownian motion(FBM) as an input and a single server of constant service rate. By using the result of Duffield and O'Connell(6), we investigate the asymptotic tail-distribution of the stationary work-load. When there are multiple homogeneous FBM inputs, the workload distribution is similar to that of the queue with one FBM input; whereas for the heterogeneous sources the asymptotic work-load distributions is dominated by the source with the largest Hurst parameter.

• Journal of Information Processing Systems
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• 제16권1호
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• pp.132-144
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• 2020

Cloud computing is an emerging technology based on the concept of enabling data access from anywhere, at any time, from any platform. The exponential growth of cloud users has resulted in the emergence of multiple issues, such as the workload imbalance between the virtual machines (VMs) of data centers in a cloud environment greatly impacting its overall performance. Our axis of research is the load balancing of a data center's VMs. It aims at reducing the degree of a load's imbalance between those VMs so that a better resource utilization will be provided, thus ensuring a greater quality of service. Our article focuses on two phases to balance the workload between the VMs. The first step will be the determination of the threshold of each VM before it can be considered overloaded. The second step will be a task allocation to the VMs by relying on an improved and faster version of the meta-heuristic "simulated annealing (SA)". We mainly focused on the acceptance probability of the SA, as, by modifying the content of the acceptance probability, we could ensure that the SA was able to offer a smart task distribution between the VMs in fewer loops than a classical usage of the SA.

• 한국데이터정보과학회:학술대회논문집
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• 한국데이터정보과학회 2005년도 춘계학술대회
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• pp.25-29
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• 2005

We analyze an M/G/1 queueing system under $P_{\lambda,\tau}^M$ service policy. By using the level crossing theory and solving the corresponding integral equations, we obtain the stationary distribution of the workload in the system explicitly.

• 중환자간호학회지
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• 제2권1호
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• pp.48-57
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• 2009

Purpose: The purpose of this study is to establish reliability and validity and to identify the conversion index. Method: The WMSCN for ICU was revised from Workload Management System for Nurses(WMSN) of Walter Reed Army Hospital. Reliability of the WMSCN was evaluated interrater reliability between head nurses and staff nurses at 124 patients in April 2008. Validity through the correlation between direct nursing care hours and WMSCN score was conducted at 20 ICUs of 10 hospitals. Finally the conversion index was identified by total nursing hours and it divided by WMSCN score. Results: The scores by nurses were highly correlated with head nurses’(p=.967), and also scores of the WMSCN were highly correlated with the direct nursing care hours(p<.001). The distribution of patient classification ranks into class V(61.3%), class IV(24.2%) and class VI(11.3%). The scores of the WMSCN were no differences between MICU and SICU. Finally, the conversion index was 8.2 minutes. Conclusion: WMSCN is available to classify the nursing workload for critical care patients. The repeated evaluation of validity and reliability are requisite to use WMSCN effectively. And the conversion index should be adjusted to estimate the appropriate staffing in Korea.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회 1995년도 추계학술대회발표논문집; 서울대학교, 서울; 30 Sep. 1995
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• pp.113-118
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• 1995

본 연구는 폐쇄형 대기행렬망(CQN:Closed Network of Queue)으로 표시되는 FMS 시스템의 최적 성능을 산정하는 방법과 각 작업장의 작업 부하 (Workload)를 최적화하기 위한 방법에 관한 연구이다. FMS 생산 시스템의 성능 (Performance)을 기존의 생산률(Production Rate)외에 기대생산률 (Expected Production Rate), 평균 대기작업량(Mean Queueue Length), 및 기대 투자이용률(Expected Investment Utilization Rate)과 이들 각각의 분산 (Variance)들을 고려하였다. 이러한 성과측정 문제를 수리 모델링하고 이를 이용하여 각 작업장에서의 가공 장비의 그룹(Machine Group)별 최적 작업배 분(Workload) 조건을 보였다. 또한 위의 과정을 최근의 FMS 전용 Simulator인 FACTOR/AIM을 이용한 분석 결과와 비교하여 보였다.

• Journal of Information Processing Systems
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• 제7권3호
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• pp.435-446
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• 2011

Microprocessors are becoming increasingly vulnerable to soft errors due to the current trends of semiconductor technology scaling. Traditional redundant multi-threading architectures provide perfect fault tolerance by re-executing all the computations. However, such a full re-execution technique significantly increases the verification workload on the processor resources, resulting in severe performance degradation. This paper presents a pro-active verification management approach to mitigate the verification workload to increase its performance with a minimal effect on overall reliability. An anomaly-speculation-based filter checker is proposed to guide a verification priority before the re-execution process starts. This technique is accomplished by exploiting a value similarity property, which is defined by a frequent occurrence of partially identical values. Based on the biased distribution of similarity distance measure, this paper investigates further application to exploit similar values for soft error tolerance with anomaly speculation. Extensive measurements prove that the majority of instructions produce values, which are different from the previous result value, only in a few bits. Experimental results show that the proposed scheme accelerates the processor to be 180% faster than traditional fully-fault-tolerant processor with a minimal impact on overall soft error rate.

• 한국군사과학기술학회지
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• 제13권6호
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• pp.958-966
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• 2010

In this paper, we have proposed a integrated dynamic control architecture in 6WD(wheel drive)/6WS(wheel steering) vehicle for military applications. Since 6WD/6WS vehicle has inherent redundancy, the input variables to make any desired vehicle motion can not be determined uniquely. Therefore, optimal distribution method of tire forces is introduced, which is based on workload of each tire. Simulation result shows that this is effective for the energy minimization and dynamic performance enhancement. We also suggest how the integrated control with any failure mode should be reconstructed.

• Journal of Nutrition and Health
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• 제37권8호
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• pp.701-711
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• 2004

This study investigated elementary, middle, and high school teachers' satisfaction, nutrition education, workload changes, and demands in school foodservice programs (SFPs). The subjects were 630 teachers at 12 elementary, 9 middle, and 9 high school within the nation. Ninety five percent of the teachers felt that there was a necessity for SFPs. Middle school teachers (MTs) and high school teachers (HTs) thought that it was necessary in order to reduce the students' burden of carrying lunch boxes. The teachers were relatively satisfied with their school's foodservice management types, food distribution types, meal quality, and sanitation. Elementary teachers (ETs) and HTs had a higher satisfaction than MTs. Teachers thought that SFPs had positive effects on their students' nutrition and health, enhancing desirable eating habits, and socialization. ETs had more positive opinions than MTs or HTs. ETs and MTs thought that their workload had been increased by SFPs more than HTs, but they had relatively positive opinions on the workload change. ETs taught nutrition and health through SFPs more frequently than MTs or HTs. Many teachers thought that there was a lack of appropriate teaching materials. Some teachers thought that the problems in the present SFPs were: a lack of cafeteria facilities, poor quality of meals, and management of leftovers. Their demands for SFPs were a improvement of meal quality and the establishment of cafeterias. In conclusion, MTs had more negative opinions than ETs or HTs. ETs perceived that SFPs had a function as an important educational activity as well as the supply of nutritional meals. MTs or HTs tended to consider only a meal. It is suggested that teachers, especially MTs and HTs, should modify their attitudes and recognize the educational functions of SFPs. Training programs should be developed under government auspices.

• 한국컴퓨터정보학회논문지
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• 제13권1호
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• pp.109-116
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• 2008

고화질 입체 영상의 효과적인 재생을 위해 PC클러스터를 활용한 여러 형태의 병렬화 기법이 제안되었지만, 영상을 구성하는 객체의 분포가 균일하지 않은 경우 충분한 성능을 발휘하지 못하였다. 본 연구에서는 POV-Ray 렌더러를 채택한 PC클러스터 기반의 병렬 렌더링 시스템을 구축하고, 병렬화 성능을 높이기 위한 효과적인 부하 균형 기법을 개발하였다. 특히 애니메이션을 구성하는 연속 프레임 작업에서 프레임간의 연관성(coherence)이 높다는 사실에 근거하여, 임의 프레임의 각 분할 영역에 소요된 계산량을 바탕으로 다음 프레임의 부하 분포를 예측하고 이에 맞게 각 프로세서의 작업 영역을 재조정하는 기법을 제안하였다. 제안 기법의 성능을 평가하기 위해, 충분하지는 않지만 2개의 실제 애니메이션 데이터에 대한 적용 결과, 정적 분할에 비해 약 40% 가량의 성능 향상을 보였다. 또한 다양한 부하 분포에 대한 각 기법의 성능을 추정하기 위해 수행한 모의실험에서, 정적 분할 기법에 대해 부하균형, 확장성 측면에서 우월한 것으로 예측되었다.