• 대한인간공학회지
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• 제16권2호
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• pp.29-38
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• 1997

The research on the factors which effect on legibility is mainly utilized as the basic data of selecting the standard guideline of VDT screen. But the research on Korean is scarcer than that of English. Furthermore, it is unreasonable to apply the results of the foreign language to Korean, beause of the difference between the typography of English and that of Korean. Therefore, more systematic and ergonomic research of the Korean typography on VDT screen is needed. In this paper, an experimental study on search speed and error rate is designed and performed according to different Korean letter size and font on search task with VDT. The experimental screen based on popular Ming and Gothic style is made up of total 12 artificial screens, each 6 different font size. As the criteria of the performance, searching speed(s.s.) and error rate (e) are selected, and CFF value is measured to evaluate user's visual fatigue. The results of experiment in font show that the Korean Gothic style is superior to the Korean Ming style in user's visual performance. The letter size that gives user the optimal performance ranges from the visual angle 39.8' to 55.5' in Ming style, from the visual angle 39.8' to 52.6' in Gothic systle. In visual fatigue experiment, the better performance of letter size is, the less tired user feels. And the smaller letter size is, the more tired user feels. There is no relationship between font and user's visual fatigue.

• Journal of Mechanical Science and Technology
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• 제16권8호
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• pp.1053-1063
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• 2002

This paper presents a robust nonlinear controller for a f degree of freedom (DOF) parallel manipulator in the task space coordinates. The proposed control strategy requires information on orientations and translations in the task space unlike the joint space or link space control scheme. Although a 6 DOF sensor may provide such information in a straightforward manner, its cost calls for a more economical alternative. A novel indirect method based on the readily available length information engages as a potential candidate to replace a 6 DOF sensor. The indirect approach generates the necessary information by solving the forward kinematics and subsequently applying alpha-beta-gamma tracker With the 6 DOF signals available, a robust nonlinear task space control (RNTC) scheme is proposed based on the Lyapunov redesign method, whose stability is rigorously proved. The performance of the proposed RNTC with the new estimation scheme is evaluated via experiments. First, the results of the estimator are compared with the rate-gyro signals, which indicates excellent agreement. Then, the RNTC with on-line estimated 6 DOF data is shown to achieve excellent control performance to sinusoidal inputs, which is superior to those of a commonly used proportional-plus-integral-plus-derivative controller with a feedforward friction compensation under joint space coordinates and the nonlinear controller under task space coordinates.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제4권3호
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• pp.324-340
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• 2010

Video streaming service over wireless networks is a challenging task because of the changes in the wireless channel conditions that can occur due to interference, fading, and station mobility. To provide an efficient wireless video streaming service, the rate adaptation scheme should improve wireless node performance and channel utilization. Moreover, the quality adaptation scheme should be considered at the streaming application. To meet these requirements, we propose a new cross-layer design for video streaming over wireless networks. This design includes the rate and quality adaptation schemes. The rate adaptation scheme selects the optimal transmission mode and resolves the performance anomaly problem. Based on performance improvement by the proposed rate adaptation scheme, our quality adaptation scheme improves the quality of video streaming. Through performance evaluations, we prove that our cross-layer design improves the wireless channel utilization and the quality of video streaming.

• 말소리와 음성과학
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• 제5권3호
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• pp.95-101
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• 2013

Aging is related to anatomical and physiological changes in respiratory and phonation organs. These changes influence articulation which leads to inaccurate speech and slow articulatory diadochokinesis(DDK). DDK indicates the range, rate, regularity, accuracy, and agility of articulation that reflect motor speech function. The purpose of this study is to investigate the rates and regularities of DDK in healthy Korean elderly through passive acoustic analysis (Praat). Thirty subjects between the ages of 65 and 94 participated in this study. Rate was observed for 5 seconds, while regularity was calculated based on the standard deviation on the following: 1) syllable duration of each task; 2) gap duration between syllables. Then, simple regression analysis was conducted in order to examine the effect of age on performance. The result showed that the slow rate was not a significant factor in terms of advancing age. Furthermore, regularity indicated a significant difference in the following: 1) /pʌ/, /kʌ/ and /pʌtʌkʌ/ in syllable duration; 2) /kʌ/ duration in the gap between syllables. In conclusion, articulatory coordination is reduced with the onset of aging. In particular, /kʌ/ would be a sensitive task for articulatory coordination.

• 대한인간공학회지
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• 제28권3호
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• pp.73-79
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• 2009

Driving is a complex psychomotor task often interrupted by secondary activities that increase cognitive workload and divert attention away from the roadway. The risk of inattentive driving is known to vary with age. To assess the characteristics of advancing age on driver's cognitive workload under dual task condition, we evaluate the performance of 96 drivers divided into three age groups: 20's, 40's, and 60's. This study considers driver's cognitive workload in the context of urban and highway driving. Error rate & Dual task cost are used to measure driver's cognitive workload. Results indicate that age impacts cognitive workload during dual task driving conditions.

• 감성과학
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• 제26권4호
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• pp.29-40
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• 2023

불안은 주의 시스템의 균형을 깨트려 목표 지향 시스템보다 자극 주도 시스템을 우선하게 만드는 것으로 알려져 있으나, 자기 교시는 자기 조절의 효과로 목표 지향적 행동을 유도하게 한다. 본 연구는 가상현실 환경에서 현직 조종사를 대상으로 기상 및 자기 교시 조건이 조종사에게 발생하는 불안과 비행 과제의 수행에 미치는 영향을 검증하였다. 기상 조건은 시계비행 기상 상황과 악기상 상황으로 구분하였고 자기 교시의 수행 여부를 달리하여 비행 과제를 수행하게 하였다. 실험 결과 악기상 상황에서 불안과 심박수가 더 높고 비행 과제의 수행도가 더 낮은 것으로 나타났으나, 자기 교시를 수행하는 조건에서는 불안과 심박수가 더 낮고 비행 과제의 수행도가 더 높은 것으로 나타났다. 이 결과는 불안의 영향으로 비행에 어려움을 겪어 사고로 연결될 가능성이 증가할 수 있으나, 자기 교시에 의한 비행 수행의 향상으로 사고로 연결될 가능성이 감소할 수 있음을 시사한다.

• 산업공학
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• 제18권1호
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• pp.82-87
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• 2005

Most of virtual reality systems ask users to control 3D objects or to navigate 3D world using 3D controllers. To maximize the human performance in the control, the design of virtual reality system and its input and output devices should be optimized. In this study, an experiment was designed to investigate the effects of three resolution factors of a virtual reality system on the human performance. Six subjects conducted the experiment for the factors; two frame rates, three spatial resolutions, and three pictorial contents. The result showed that the greater the spatial resolution was, the higher the human performance was. For the temporal resolution, fixed frame rate at 18 Hz was better than the varied maximized frame rate. For the pictorial contents, the virtual space with orientation cues marked the greatest performance than the other two conditions; the virtual space without any orientation cue and the virtual space like real world. These results could be applied for the design of virtual reality systems.

• 대한인간공학회:학술대회논문집
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• 대한인간공학회 1997년도 춘계학술대회논문집
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• pp.56-60
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• 1997

The study of human erroneous actions has traditionally taken place along two different lines of approach. One has been concerned with finding and explaining the causes of erroneous actions, such as studies in the psychology of "error". The other has been concerned with the qualitative and quantitative prediction of possible erroneous actions, exemplified by the field of human reliability analysis (HRA). Another distinction is also that the former approach has been dominated by an academic point of view, hence emphasising theories, models, and experiments, while the latter has been of a more pragmatic nature, hence putting greater emphasis on data and methods. We have been developing a method to make predictions about error modes. The input to the method is a detailed task description of a set of scenarios for an experiment. This description is then analysed to characterise thd nature of the individual task steps, as well as the conditions under which they must be carried out. The task steps are expressed in terms of a predefined set of cognitive activity types. Following that each task step is examined in terms of a systematic classification of possible error modes and the likely error modes are identified. This effectively constitutes a qualitative analysis of the possibilities for erroneous action in a given task. In order to evaluate the accuracy of the predictions, the data from a large scale experiment were analysed. The experiment used the full-scale nuclear power plant simulator in the Halden Man-Machine Systems Laboratory (HAMMLAB) and used six crews of systematic performance observations by experts using a pre-defined task description, as well as audio and video recordings. The purpose of the analysis was to determine how well the predictions matiched the actually observed performance failures. The results indicated a very acceptable rate of accuracy. The emphasis in this experiment has been to develop a practical method for qualitative performance prediction, i.e., a method that did not require too many resources or specialised human factors knowledge. If such methods are to become practical tools, it is important that they are valid, reliable, and robust.

• 한국감성과학회:학술대회논문집
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• 한국감성과학회 2011년도 춘계학술대회
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• pp.89-90
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• 2011

• 한국감성과학회:학술대회논문집
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• 한국감성과학회 2012년도 춘계학술대회
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• pp.105-106
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• 2012