• 한국기계가공학회지
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• 제21권9호
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• pp.50-55
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• 2022

Acceleration performance, maximum velocity, urban driving energy consumption, and high-way driving energy consumption are important characteristics of electric vehicle driving. This study analyzes the effect of a gear ratio on these characteristics for a front wheel drive electric vehicle. The normalized sensitivity metric is used to compare the sensitivity of these scaled characteristics to the changes in the gear ratio. The sensitivity analysis results show that the normalized values are 0.95 for maximum velocity, 0.91 for acceleration performance, 0.51 for urban driving energy consumption, and 0.24 for high-way driving energy consumption. Therefore, the maximum velocity was affected the most by the changes in the gear ratio. These results can be used to determine the gear ratio of a front wheel drive electric vehicle to optimize the driving characteristics simultaneously.

• 대한인간공학회지
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• 제32권2호
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• pp.167-177
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• 2013

Objective: This study aims to compare the usefulness of subjective measures which are comprised of existing methods like NASA-TLX, Bedford-scale and ZEIS and newly developed method like DALI in measuring drivers' mental workload in terms of validity, sensitivity and diagnosticity. Background: Nowadays, with the development of intelligent vehicle and HMI, mental workload of driver has become more and more important. For this reason, the studies on drivers' mental workload about driving situation and the use of information technology equipment such as mobile phones and navigations were conducted intensively. However, the studies on measuring drivers' mental workload were rarely conducted. Moreover, most of studies on comparison of subjective measures were used with performance based measure. However, performance based measures can cause distraction effect with subjective measures. Method: Participants (N=19) were engaged in a driving simulation experiment in 2 driving contexts (downtown driving and highway driving context). The experiment has 2 sessions according to driving contexts. The level of difficulties by driving contexts were adjusted according to existence of intersections, traffic signs and signals, billboards and the number of doublings. Moreover, as criteria of concurrent validity and sensitivity, the EEG data were recorded before and during the sessions. Results: The results indicated that all subjective methods were correlates with EEG in high-way driving. On the contrary to this, in downtown driving, all subjective methods were not correlates with EEG. In terms of sensitivity, multi-dimensional scales (NASA-TLX, DALI) were the only ones to identify differences between high way and downtown driving. Finally, in terms of diagnosticity, DALI was the most suitable method for evaluating drivers' mental workload in driving context. Conclusion: The DALI as newly developed method dedicated to evaluate driver's mental workload was superior in terms of sensitivity and diagnosticity. However, researchers should consider the characteristics of each subjective method synthetically according to research objective by selecting the method in subjective measures. Application: The results of this study could be applied to the intelligent vehicle and next generation of HMI design to decrease mental workload of driver and for the development of new subjective method in vehicle domain.

• 드라이브 ㆍ 컨트롤
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• 제17권4호
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• pp.38-45
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• 2020

The purpose of this study was to analyze the design sensitivity of an independent driving system for disaster response. The research procedure was as follows. First, an analysis model based on the circuit diagram of the driving system was developed. Second, to ensure the reliability of the analytical model, the load-free test results and analysis results were compared. Even if different loads acted on four independent motors, the system was confirmed to be implemented according to the design intent. Finally, the design variables of the analysis model were analyzed to obtain design variables with a significant impact on system performance and stability. The analysis program used simulation X.

• Journal of the Korean Data Analysis Society
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• 제20권6호
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• pp.3185-3199
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• 2018

본 연구에서는 운전장면 개별요소들에 대한 중년 및 고령운전자의 작업기억의 특성을 반응민감도, 반응편파 및 반응시간을 통해 비교하였다. 본 연구의 결과를 요약하면 다음과 같다. 첫째, 고령운전자 집단은 중년운전자 집단에 비해 민감도가 낮았고 특히 중년운전자 집단의 경우는 중심자극과 주변자극에 대한 민감도에서의 차이가 유의하지 않았던 반면, 고령운전자 집단의 경우는 중심자극에 비해 주변자극에 대한 민감도가 현저하게 더 낮았다. 둘째, 중년운전자 집단은 전반적으로 보수적으로 반응한 반면 고령운전자 집단은 대체적으로 관대한 방향으로 반응하는 경향이 상대적으로 더 컸다. 셋째, 중년운전자들에 비해 고령운전자들의 반응시간이 더 느렸고, 중심자극보다는 주변자극에 대한 반응시간이 더 느렸으며, 반응의 유형에 따라서는 적중의 반응시간이 가장 빨랐던 반면 헛경보의 반응시간이 가장 느렸다. 특히, 탈루과 정기각 반응에 대해서는 두 집단 사이의 반응시간 차이가 더 증가하였다. 이러한 결과는 중년운전자들에 비해 고령운전자들은 운전장면 개별요소에 대한 작업기억에서의 파지가 상대적으로 더 불완전하고, 이에 따라 작업기억에 기초한 신속한 판단에서 어려움이 증가할 수 있음을 시사한다.

• 대한교통학회지
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• 제25권2호
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• pp.95-105
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• 2007

과속과 음주운전 행동은 운전자로 하여금 교통상황에 잠재된 위험을 발견하고 적절하게 대처하지 못하도록 하여 교통사고 발생 확률을 높일 뿐만 아니라 사고 발생시 피해정도가 심하고 이 행동들에 내포하고 있는 위법성은 심각한 사회적 문제라고 할 수 있다. 사고 및 음주운전자 집단과 일반운전자들의 운전행동결정요인과 운전행동을 비교한 결과, 사고 및 음주운전자들의 '과속운전행동 점수와 '음주운전행동 점수가 일반운전자들보다 높았다. 또 사고 및 음주운전자들은 실제 운전행동에서도 일반운전자들보다 과속운전과 음주운전을 더욱 많이 하고 있었으며, 교통사고에서 가해자가 된 경험도 더 많았다. 경로모형 결과에서는 사고 및 음주운전자 집단의 위험감수성 부족 요인과 상황적응성 부족 요인, 과속운전행동 요인이 교통사고 가해경험에 미치는 영향이 일반운전자 집단에 비하여 더욱 크게 나타났고, 사고 및 음주운전자들의 운전행동결정요인들 가운데 위험감수성과 상황적응성의 수준이 교통사고 가해경험을 더 잘 설명하였다.

• 대한통합의학회지
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• 제8권2호
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• pp.89-95
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• 2020

Purpose : This study aims to evaluate the correlation of cognitive function, activities of daily living (ADL), and driving performance in stroke hemiplegic patients residing in Korea. Methods : Subjects of the study were 18 stroke hemiplegic patients admitted to hospitals situated in Seoul. A clock drawing test (CDT), a modified Barthel index (MBI), and a virtual reality driving simulator (Eca faros-driving simulator) were used to examine their cognitive function, their ADL ability, and their driving skills, respectively. Results : Driving skills of stroke hemiplegic patients were shown to be associated with the CDT evaluation tool (r=-.777) (p<.001), but they were found to have any correlation with MBI (r=-.022) (p>.05). Additionally, an individual's CDT showed that the driving simulator evaluation result (pass/fail) could be discriminated with a sensitivity of 100.0 %, a specificity of 40.0 %, and an accuracy of 66.7 %. The result confirmed that the CDT is a useful evaluation tool for screening driving ability in people with stroke. But the MBI did not show any significant results (sensitivity of 62.5 %, specificity of 40.0 %, and predicted the results of the simulator with 50.0 % of accuracy) (p>.05). Conclusion : This study shows that cognitive function influences the driving performance in people with stroke. Driving skills of stroke hemiplegic patients are seen to be highly related to CDT. In the field of driving rehabilitation, these findings could be useful for evaluating driving skills relating to CDT. Furthermore, the study results will set a guideline for domestic occupational therapists to use the evaluation tool for assessing driving abilities in people with stroke.

• 대한산업공학회지
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• 제30권1호
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• pp.58-64
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• 2004

In order to determine the level of safety on highway driving, the relationship between the psychophysiological signal and driving condition was investigated. In particular, a Demand-Effort model was conceptualized and used in this study to diagnose the suitability of driving by reading the patterns of psychophysiological signals. To run the model, threshold values were determined to categorize the high, moderate and low level of effort. To examine the sensitivity of the model, a cross-validation process was performed by collecting additional data. Further investigation need to be conducted to improve the sensitivity of the model for practical application.

• 한국시뮬레이션학회논문지
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• 제22권3호
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• pp.81-87
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• 2013

본 논문은 컴퓨터 해석프로그램인 SimulationX를 이용하여 굴삭기 주행모터의 내부에서 발생하는 서지압력의 저감 방법에 대하여 분석하는 연구이다. 설계민감도 해석을 통하여 설계상의 문제점을 파악하고 해결책에 접근하는 방법을 다룬다. 진행순서는 다음과 같다. 우선 현재 설계 된 주행모터에 장착된 밸브들의 동적거동을 분석하여 설계의 문제점을 찾아낸다. 그 후 많은 설계변수들 중 동적성능향상에 민감하다고 판단되는 변수를 도출하고 설계치수를 조정하여 동적성능 안정화의 경향을 살펴본다. 마지막으로 민감한 변수가 다수 일 경우 변수조합을 통해 효과적인 튜닝방법을 제안한다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회B
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• pp.3159-3162
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• 2008

A sensitivity analysis of the liquid rocket engine has been made. A mode analysis program is used to predict the performance change due to the variation of rocket engine operating environment. The propellant supply pressure and density are the major variables of the operating condition. The material properties of the turbine driving gas is assumed as the function of mixture ratio. The discrepancies of performance change between constant turbine driving gas properties and variable properties are greater for the case of fuel pump inlet pressure change than the oxidizer pump inlet pressure change.

• 한국자기공명학회논문지
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• 제21권1호
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• pp.1-6
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• 2017

Enhancements in NMR sensitivity have been the main driving force to extend the boundaries of NMR applications. Recently, techniques to shift the thermally populated nuclear spin states are employed to gain high NMR signals. Here, we introduce a technique called photochemically induced dynamic nuclear polarization (photo-CIDNP) and discuss its progresses in enhancing the solution-state NMR sensitivity.