• 대한인간공학회지
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• 제26권2호
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• pp.45-59
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• 2007

The operating tasks of overhead crane have caused undue stress to the operators from physical, mental, and environmental workload. Existing workload assessment models for musculoskeletal disorders such as OWAS, RULA, and QEC have limited applicability to the crane operating tasks because they focus mainly on physical factors and do not consider the relative importance of each factor. The present study was to develop a workload assessment model customized to overhead crane operation, following a systematic process: (1) analyzing task characteristics, (2) selecting workload factors, (3) developing assessment methods, (4) establishing action levels, and (5) computerizing the assessment model. Based on literature review, worksite survey, and focus group interview, 4 physical factors (awkward posture, static posture, repetitive motion, and excessive force), 6 mental factors (visual demand, auditory demand, task complexity and difficulty, time urgency, work schedule related stress, and safety related stress), and 4 environmental factors (noise, vibration, dust, and temperature) were selected and their rating scales and relative weights were determined. Then, based on the workload assessment results of 8 overhead cranes operated at different workplaces, the action levels of each factor category were established. Finally, the crane operation assessment model was computerized for effective analysis and report preparation. The present approach is applicable to develop a customized workload assessment model for an operating task under consideration.

• 한국산업정보학회논문지
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• 제23권2호
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• pp.29-39
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• 2018

본 논문에서는 일량제어정책과 복수휴가정책이 혼합된 서버제어정책 하에서 운영되는 이산시간 대기행렬시스템을 다룬다. 고객들은 베르누이 도착과정으로 시스템에 도착하고, 서버는 한대가 운영되며 시스템 내 서비스할 고객이 없으면 유휴기간을 갖는 서버가 이산 확률변수 V만큼의 휴가를 떠났다가 돌아와서 대기 중인 고객들의 총 일량이 임계값 D를 넘길 때까지 휴가를 반복한다. 본 논문에서는 이산시간 시스템을 대상으로 하여 보다 현실적이며 유연한 혼합제어 정책 하에서 운영되는 대기행렬시스템의 안정상태 일량분포를 유도하고 평균일량을 계산하였다. 이는 시스템 내 고객수, 대기시간, 체재시간과 같은 시스템의 여러 성능척도를 분석하는데 기본이 된다.

• 대한산업공학회지
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• 제40권3호
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• pp.325-332
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• 2014

High cognitive workload decreases a driver's ability of judgement and response in traffic situation and could result in a traffic accident. Electrocardiography (ECG) has been used for evaluation of drivers' cognitive workload; however, individual differences in ECG response corresponding to cognitive workload have not been fully considered. The present study developed an evaluation method of individual driver's cognitive workload based on ECG data, and evaluated its usefulness through an experiment in a driving simulator. The evaluation method developed by the present study determined the optimal ECG evaluation condition for individual participant by analysis of area under the receiver operating characteristic curve (AUC) for various conditions (total number of conditions = 144) in terms of four aspects (ECG measure, window span, update rate, and workload level). AUC analysis on the various conditions showed that the optimal ECG evaluation condition for each participant was significantly different. In addition, the optimal ECG evaluation condition could accurately detect changes in cognitive workload for 47% of the total participants (n = 15). The evaluation method proposed in the present study can be utilized in the evaluation of individual driver's cognitive workload for an intelligent vehicle.

• 대한인간공학회지
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• 제29권5호
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• pp.735-739
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• 2010

Driving workload is increasing according to developing new in-vehicle devices and introducing driving information systems. In this research using a driving simulator, EFRP (Eye Fixation Related Potential) was measured for evaluating driving attention and distraction while tasking cognitive workload, n-back tasks. The result of EFRP was compared with driver behaviors. Results suggest that EFRP is able to use for a method of evaluating driving workload, however, the analysis of driver behavior is difficult to find driving attention and distraction in the case of free flow of traffic situation.

• 산업공학
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• 제9권3호
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• pp.257-268
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• 1996

This paper illustrates the process of developing and configuring the prototype Computer Analysis System for Controlling Occupational WORKload (CAS-COWORK). The software interface between the database and expert system was attempted. The database is used for storing and retrieving series of data entered by general users and the expert system is used for identifying and solving occupational problem areas. Two theories were applied in developing the algorithm base of CAS-COWORK that were used to calculate overall workload stress level. The fuzzy set theory was introduced to capture the subject‘s workload stress perception. The Analytic Hierarchy Process (AHP) was introduced to estimate the importance of the task and workplace variables. The purpose of the system development is for future prediction and problem solving which would be highly valuable to the industrial engineer.

• 산업경영시스템학회지
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• 제38권3호
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• pp.56-63
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• 2015

Several fields of science have demanded large-scale workflow support, which requires thousands of CPU cores or more. In order to support such large-scale scientific workflows, high capacity parallel systems such as supercomputers are widely used. In order to increase the utilization of these systems, most schedulers use backfilling policy: Small jobs are moved ahead to fill in holes in the schedule when large jobs do not delay. Since an estimate of the runtime is necessary for backfilling, most parallel systems use user's estimated runtime. However, it is found to be extremely inaccurate because users overestimate their jobs. Therefore, in this paper, we propose a novel system for the runtime prediction based on workload-aware clustering with the goal of improving prediction performance. The proposed method for runtime prediction of parallel applications consists of three main phases. First, a feature selection based on factor analysis is performed to identify important input features. Then, it performs a clustering analysis of history data based on self-organizing map which is followed by hierarchical clustering for finding the clustering boundaries from the weight vectors. Finally, prediction models are constructed using support vector regression with the clustered workload data. Multiple prediction models for each clustered data pattern can reduce the error rate compared with a single model for the whole data pattern. In the experiments, we use workload logs on parallel systems (i.e., iPSC, LANL-CM5, SDSC-Par95, SDSC-Par96, and CTC-SP2) to evaluate the effectiveness of our approach. Comparing with other techniques, experimental results show that the proposed method improves the accuracy up to 69.08%.

• 한국전문물리치료학회지
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• 제16권1호
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• pp.42-51
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• 2009

The purpose of this study was to develop a checklist of risk factors for quantitative assessment of musculoskeletal complaints in shipbuilding workers. A key point was to develop comprehensive a checklist including the worker's physical ability, as ergonomic and workload factors. ln the first, through correlation analysis between musculoskeletal complaints and physical abilities in shipbuilding workers, risk factors related to physical abilities were selected. In the second, after the development of a checklist was composed of physical, ergonomic and workload factors, factor analysis was used to test the validity of the developed checklist. Each factors selected finally showed that physical factors were hand grip strength, spinal curvature, and flexibility (sit to reach), ergonomic factors were posture, total exposed time, duration, and force of working, and workload factors were physical and psychological workload perceived by worker. The results showed that musculoskeletal complaints was associated with physical abilities (p<.05). The developed checklist had a reliability of .761 (Cronbach=.761) and a validity and explanation of 54.9%. The criterion of management was classified in 4 stages by relative weights of each factor. It is suggested that active intervention is needed to reduce musculoskeletal complaints in workers with more than a 14.31 score.

• 대한산업공학회지
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• 제26권1호
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• pp.54-65
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• 2000

The objective of this study is to evaluate the operator performance relating to hand switches with two or three buttons in the main control rooms of nuclear power plants. Based on the comparative analysis of the nuclear power plants, two different subjective workload-rating scales were used to evaluate the performance of 48 operators: the Overall Workload(OW) and National Aeronautics and Space Administration Task Load Index (NASA TLX). The survey questions consisting of the eight-items were asked to evaluate the operating experiences for the two different switch types. The OW scales ratings were applied to measure the workload of the switch-related tasks. The ratings revealed that signal detection tasks caused less workload in the three-buttoned-switch operators than the other switch group. However, in the switch operation tasks, the switch types did not show statistically significant effects on workload level. The NASA TLX scale ratings were performed based on detailed task scenarios that assumed the accident of small break loss of coolant, what we call, the small LOCH. The NASA TLX was administered to three different task groups: the reactor, the turbine, and the electric operator groups. Based on the NASA TLX, the two-buttoned switch groups showed higher workload than those with the three-buttoned switches. However, a statistically significant difference was found only in the reactor operator groups. When the current switch type was assumed to be changed for the other type, all of the three-buttoned switch groups were predicted to have higher workload than the other switch groups, respectively. The implications of these findings were discussed.

• 한국인터넷방송통신학회논문지
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• 제19권1호
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• pp.111-116
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• 2019

최근 GPU가 그래픽 처리뿐 아니라 다양한 분야의 병렬 처리로 그 영역을 넓혀가고 있다. 그러나, 현재 GPU는 워크로드의 다양성을 반영하기보다 간결한 제어 구조를 통한 개별 워크로드의 병렬성 극대화에 초점을 맞추고 있다. 본 논문은 워크로드 특성을 반영한 GPU 작업 배치를 위해 GPU에서 수행되는 워크로드의 자원 사용 특성을 컴퓨팅 바운드형, 메모리 바운드형, 실행종속 지연형으로 분류한 후, 각 분류에서 병목점이 되는 세부 자원을 규명한다. 예를 들어 컴퓨팅 바운드형의 경우 단정밀도 연산장치, 배정밀도 연산장치, 특수함수 연산장치 등 병목 자원이 무엇인지 분석한다. 본 논문의 분석 결과는 동일한 컴퓨팅 바운드형 워크로드라도 병목이 되는 세부 자원이 다를 경우 함께 배치하는 것이 성능 충돌을 일으키지 않는다는 점을 규명하여 GPU 작업배치의 효율화에 기여할 것으로 기대된다.

• 대한방사선기술학회지:방사선기술과학
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• 제45권3호
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• pp.213-223
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• 2022

Although the number of computed tomography(CT) is increasing every year, it is insufficient to establish appropriate workload calculation standards of radiologic technologist to provide optimal medical services to patients, such as patient safety management and infection management. The purpose of this study is to present guidelines for calculating the appropriate workload of radiologic technologist by analyzing the work flow of CT procedures and the time required for CT examination in major hospitals. As for the study subjects and methods, the appropriate process for each step of CT examination was investigated to systematically present the process and time required for the actual examination, and the CT procedure time of 104,105 adult patients and 465 pediatric patients under the age of 6 were analyzed. For the time required, data according to the use of contrast medium, procedure type, and adult/child were collected and compared. The test time of CT examination using contrast medium took about 13 minutes when one radiologic technologist worked and about 9 minutes when two radiologic technologists worked. The time required for the procedures were statistically significant depending on the presence or absence of contrast medium, multi-phase procedure, and patient age (considering pediatric patients). As a result, in order to thoroughly perform patient safety and infection management, the appropriate workload increased by about 40% when there were two radiologic technologists. The limit workload was an average of 32 people per day with one radiologic technologist per 15 minutes, and 48 people per day with two radiologic technologist per 10 minutes. This is a marginal workload, and in the case of procedures that require more time to acquire radiographic images, the interval between reservations should be widened.