• 대한인간공학회지
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• 제21권3호
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• pp.47-58
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• 2002

The similarity of shape of shape of interface between human cognitive map and real product is the important factor to determine the human performance. Nevertheless, the degree of similarity between these has not been defined quantitatively in recent studies. Therefore, in this study, the cognitive map and the mental workload were measured by SMM(Sketch Map Method) and RNASA-TLX(Revision of NASA-Task Load Index). And the numerical expression of the accuracy point was suggested for the quantitative calculation of relative positional similarity between cognitive map and real product. In the experiment, nine subjects were participated and two kinds of vehicles were used. Mental workload was mental workload was measured immediately after the road test. The result of analysis on the relationship between accuracy and mental workload shows that the negative correlation exists on each vehicle, and the lower score of mental workloads id measured on the vehicle that has the higher score of accuracy between two vehicles.

• 한국ITS학회 논문지
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• 제16권4호
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• pp.107-121
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• 2017

본 연구에서는 군집주행환경에서 비자율차의 행태분석을 위해 영상기반의 조사를 통해 피실험자의 인적특성과 군집주행 인지여부를 조사하고, 주행 시뮬레이션 실험을 통해 비자율차의 차량거동을 수집했다. 또한, 주행 시뮬레이션 실험 후 NASA-TLX 설문조사를 통해 작업부하점수를 조사했다. 영상기반 인지특성 조사 결과 피실험자 대부분이 군집주행 중인 차량들을 인지하고 군집 차량군으로 인해 부담감을 느끼는 것으로 나타났다. 군집주행환경에서의 평균속도가 비군집주행환경일 때보다 낮게 나타났고, 평균속도의 표준편차는 군집주행환경일 때 더 높게 나타났다. 인적특성과 작업부하점수를 연계분석한 작업부하평가 결과 군집, 비군집주행환경 시 인적특성별로 작업부하점수가 통계적으로 유의한 차이가 나타나는 결과들을 확인했다. 인적특성과 차량거동을 연계분석한 차량거동평가 결과에서도 군집, 비군집주행환경 시 통계적으로 유의한 차이가 나타나는 결과들을 확인했다. 본 연구의 결과를 고령운전자, 여성 등 고위험군 운전자의 안전성 증대, 비자율차 운전자에게 주변 군집주행차량에 대한 정보 제공 방안 모색 등의 비자율차 운전자를 위한 교통관리전략을 수립하는데 활용할 수 있을 것이라 판단된다.

• 대한교통학회지
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• 제35권4호
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• pp.332-347
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• 2017

자율주행기술이 교통류에 미치는 영향을 분석하기 위해서는 자율차와 비자율차 간의 상호작용을 분석하는 것이 중요한 이슈이다. 특히 자율주행기술을 활용한 유용한 서비스 중의 하나인 군집주행은 주변의 비자율 차량의 주행행태에 영향을 미칠 수 있다. 본 연구의 목적은 군집주행 환경에서 비자율차의 차로변경행태 분석하는 것이며, 3단계의 실험 및 조사를 수행하였다. 1단계 영상기반 인지특성 분석을 통해 군집주행 환경에서 어떠한 반응행태를 보일 것인지를 조사하였으며, 2단계 주행시뮬레이션 실험을 통해 비자율차의 차로변경행태를 분석하였다. 차로변경행태를 분석하기 위해 차로변경시간과 교통류의 안전성을 나타낼 수 있는 지표인 가속소음을 이용하였으며, 자율차의 시스템 보급률(Market Penetration Rate, MPR)과 피실험자 인적요소에 따른 비자율차의 주행행태 차이를 비교 분석하였다. 마지막 단계인 NASA-TLX(NASA Task Load Index)를 통해 비자율차 운전자의 작업부하를 평가하였다. 분석결과 군집차량군 주변의 비자율차 운전자는 심리적인 부담감을 느끼며, MPR이 증가할수록 차로변경시간이 길어지고 30-40대 운전자 또는 여성 운전자의 경우 안전성이 낮아지는 것으로 나타났다. 본 연구에서 도출된 결과는 자율차와 비자율차의 상호작용을 반영한 보다 현실성 높은 교통시뮬레이션 실험 시 기초자료로 활용될 수 있고, 이를 기반으로 자율협력주행 환경에서 적용 가능한 교통운영관리전략 수립을 효과적으로 지원할 것으로 기대된다.

• Journal of Minimally Invasive Surgery
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• 제21권4호
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• pp.168-176
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• 2018

Purpose: Robotic-associated minimally invasive surgery is a novel method for overcoming some limitations of laparoscopic surgery. This study aimed to evaluate the outcomes (postoperative pain, cosmesis, surgeon's workload) of single-incision robotic cholecystectomy (SIRC) vs. single-incision laparoscopic cholecystectomy (SILC) vs. conventional three-port laparoscopic cholecystectomy (3PLC). Methods: 134 patients who underwent laparoscopic or robotic cholecystectomy at a single center during 2016~2017 were enrolled. Prospectively collected data included demographics, operative outcomes, questionnaire regarding pain and cosmesis, and NASA-Task Load Index (NASA-TLX) scores for surgeon's workload. Results: 55 patients underwent SIRC, 29 SILC, and 50 3PLC during the same period. 3PLC patient group was older than the others (SIRC vs. SILC vs. 3PLC: 48.1 vs. 42.2 vs. 54.1 years, p<0.001). Operative time was shortest with 3PLC (44.1 vs. 38.8 vs. 25.4 min, p<0.001). Estimated blood loss, postoperative complications, and postoperative stay were similar among the groups. Pain control was lowest in the 3PLC group (98.2% vs. 100% vs. 84.0%, p=0.004), however, at 2 weeks postoperatively there were no differences among the groups (p=0.374). Cosmesis scores were also worst after 3PLC (17.5 vs. 18.4 vs. 13.3, p<0.001). NASA-TLX score was highest in the SILC group (21.9 vs. 44.3 vs. 25.2, p<0.001). Conclusion: Although SIRC and SILC take longer than 3PLC, they produce superior cosmetic outcomes. Compared with SILC, SIRC is more ergonomic, lowering the surgeon's workload. Despite of higher cost, SIRC could be an alternative for treating gallbladder disease in selected patients.

• 대한산업공학회지
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• 제43권3호
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• pp.176-183
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• 2017

In recent years, studies about multitasking becomes more important. During multitasking, operators can feel frustration when they are interrupted during the task and frustration can affect operator's emotional state and performance. However there is no research on measuring the frustration quantitatively in multitasking environment. In this paper, we suggested quantitative measurement of frustration during multitasking. In order to measure the frustration, we made a mathematical representation with emotional decay model and the initial intensity of frustration based on cognitive closure theory. The amount of initial intensity could be represented as the ratio of actual remaining time to expected remaining time. By the experiment, we measured the frustration during the experiment and compared this values with values of frustration dimension of NASA-TLX. Finally we got the linear regression model with a good accuracy ($R^2=0.986$). This study contributes to measuring the emotion quantitatively by the relation of expected and actual remaining time in multitasking environment.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 춘계학술대회 논문집
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• pp.1204-1208
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• 2007

In order to prevent railway accidents due to human errors which have been recognized to be the most important cause in the railway accidents, human errors should have been controlled based on systematical analysis of the human errors, and countermeasures should be derived to reduce human error probability. Among several factors inducing human errors, task load (or task complexity) is representative. In order to reduce the human error, a systematic analysis should be undertaken to evaluate task load. In this study, task load according to task types of railway worker who are a safety critical staff have been quantitatively analyzed based on NASA-TLX(Task Load Index).

• 대한인간공학회:학술대회논문집
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• 대한인간공학회 1997년도 추계학술대회논문집
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• pp.277-285
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• 1997

본 연구에서는 운전 중에 빈번히 나타나는 부작업을 모의 운전 실험하에서 선정하여 그때의 운전 수행 도와 운전자의 심리적 작업부하에미치는 영향에 대해 연구하였다. 운전의 수행도는 브레이크 작동시의 시간의 적절성을 사용하였으며, 이를 측정하기 위해도로교통안전협회에 설치되어있는 운전기능검사기기를 사용하였다. 또한 운전자의 심리적 작업부하를 측정하기 위해 심리적 작업부하 측정 방법의 하나인 NASA- TLX를 사용하였다. 다양한 운전 상황을 설정하기 위해도로의 형태를 골목길과 일반도로로 나누었으며, 부작업의 종류는 전화 걸기, 라디오 조작, 대화로 선정하였다. 실험에는 17명의 피실험자가 참가하였고 결과에 대한 통계분석(SAS)이 이루어졌다. 본 연구 결과, 운전시 전화 걸기와 라디오 조작의 경우가 다른 부작업에 비해 운전 수행도를 통계적으로 유의한 정도 저하시키는 것이 조사되었다. 부작업에따라서 3 . approx. 22%의 수행도의 저하가 나타났으며, 42 .approx. 59%의 심리적 작업부하의 증가가 나타났다. 본 연구에서는 부작업이 정도의 차이는 있으나 수행도의 감소와 심리적 작업부하의 증가를 유발시키는 것이 정량적으로 입증되었다. 차후 보다 실제상황에 가가운 모의 실험과 다양한 수행도 측정지수를 사용한 연구 를 통해 운전시 부작업이 사고에 미치는 영향이 검증될 것으로 기대된다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 추계학술대회 논문집
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• pp.1722-1730
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• 2007

According to the result of recent studies, it was revealed that the error of safety-related personnel still plays a significant role in the accidents and/or incidents of a railway system. Accordingly, in order to reduce as well as prevent human errors, it is necessary to: (1) identify the root cause of accidents/incidents, and (2) conduct a research that can provide a systematic as well as an effective way to deal with the identified human errors. To this end, it is essential to suggest appropriate countermeasures based on the result of a task load analysis, which can soundly reduce a high level of the task load put on safety-related personnel. In the light of this concern, about the tasks of railway traffic signallers, a detailed task analysis was conducted in this study. After that, the associated task load scores were quantified by NASA-TLX technique that is one of the most well-known subjective workload measurement techniques. As a result, a set of significant tasks that could put a high task load on railway traffic signallers was identified.

• 산업경영시스템학회지
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• 제21권45호
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• pp.145-154
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• 1998

The effects of secondary task on driving performance and subjective workload were investigated during a simulated driving. The driving performance was determined by the appropriateness of break timing. The driving simulator was provided by the Korea Road Traffic Safety Association. The subjective workload was tested by using a multidimensional measure such as NASA-TLX. Road was categorized into two types: narrow alley and wide street. The secondary task included pushing the number on the cellular phone, pushing radio channel, and conversing with a passenger. Seventeen subjects volunteered in the study. The data were analyzed by using SAS. Results showed that using the cellular phone and pushing channel during driving caused 3∼22% decline of driving performance and 42∼59% increase of subjective workload respectively. These results indicated that the secondary task could be potentially dangerous although there was not a significant performance decrease due to the notable increase of mental workload. In the future, if we can use a more sensitive and realistic driving simulator, the effects of secondary task under a dynamic driving situation can be investigated.

• Nuclear Engineering and Technology
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• 제51권2호
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• pp.453-462
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• 2019

Mental workload (MWL) is a major consideration for the user interface design in nuclear power plants (NPPs). However, each MWL evaluation method has its advantages and limitations, thus the evaluation and control methods based on multi-index methods are needed. In this study, fuzzy comprehensive evaluation (FCE) theory was adopted for assessment of interface designs in NPP based on operators' MWL. An evaluation index system and membership functions were established, and the weights were given using the combination of the variation coefficient and the entropy method. The results showed that multi-index methods such as performance measures (speed of task and error rate), subjective rating (NASA-TLX) and physiological measure (eye response) can be successfully integrated in FCE for user interface design assessment. The FCE method has a correlation coefficient compared with most of the original evaluation indices. Thus, this method might be applied for developing the tool to quickly and accurately assess the different display interfaces when considering the aspect of the operators' MWL.