• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2005년도 International Meeting on Information Displayvol.I
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• pp.121-124
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• 2005

A field-sequential color projection system can display color images using panel. However, it suffers from a characteristic trichromatic separation known as "color breakup". The viewing of images exhibiting color breakup may cause visual fatigue and mental stress. In this study, the authors examine, from the standpoint of human factors, the objective and subjective symptoms that can result from the viewing of images with color breakup.

• 반도체디스플레이기술학회지
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• 제1권1호
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• pp.29-33
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• 2002

In the flip-chip process, the problem like electric defect or fatigue crack caused by the difference of CTE, between chip and substrate board had occurred. Underfill of flip chip to overcome this defects is noticed as important work developing in whole reliability of chip by protecting the chip against the external shock. In this paper, we introduce the underfill methods using mold and plunge and improvement of process and reliability, and the advantage which can be taken from embodiment of device.

• 대한인간공학회지
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• 제30권1호
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• pp.195-202
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• 2011

Objective: The aim of this study is to investigate and review the previous researches about objective measuring fatigue caused by visual stimuli. Also, we analyze possibility of alternative visual fatigue measurement methods using facial expression recognition and gesture recognition. Background: In most previous researches, visual fatigue is commonly measured by survey or interview based subjective method. However, the subjective evaluation methods can be affected by individual feeling's variation or other kinds of stimuli. To solve these problems, signal and image processing based visual fatigue measurement methods have been widely researched. Method: To analyze the signal and image processing based methods, we categorized previous works into three groups such as bio-signal, brainwave, and eye image based methods. Also, the possibility of adopting facial expression or gesture recognition to measure visual fatigue is analyzed. Results: Bio-signal and brainwave based methods have problems because they can be degraded by not only visual stimuli but also the other kinds of external stimuli caused by other sense organs. In eye image based methods, using only single feature such as blink frequency or pupil size also has problem because the single feature can be easily degraded by other kinds of emotions. Conclusion: Multi-modal measurement method is required by fusing several features which are extracted from the bio-signal and image. Also, alternative method using facial expression or gesture recognition can be considered. Application: The objective visual fatigue measurement method can be applied into the fields of quantitative and comparative measurement of visual fatigue of next generation display devices in terms of human factor.

• 한국통신학회논문지
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• 제38C권11호
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• pp.990-999
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• 2013

기존의 연구들에서 이론적 근거를 바탕으로 3D 영상 시청에 대해 시각피로도와 연관이 있는 요소와 영향을 주는 요소들에 대해 경험적 데이터를 기반하여 지속적으로 밝혀내고 있다. 하지만, 이러한 영향을 미치는 요소와 맞물려 실제로 시청자가 느끼는 피로감과 연계하여 측정된 자료는 미비한 상태이다. 본 연구에서는 시청자가 느끼는 자각적 피로도에 따른 시기능적 데이터인 IPD, AC/A비, 그리고 사위도와 그 변화량에 미치는 영향 및 상관관계를 알아보고자 하였다. 자각적 피로도의 기술통계량 점수 $6.00{\pm}3.88$점에 기초하여 피로도 점수 합계 0 ~ 6점을 피로 미호소 그룹, 7 ~ 16점을 피로 호소 그룹으로 분류하였다. 실험 결과 자각적 피로도별 영상 만족도, IPD, 원거리 사위도에서는 차이를 나타내지 않았다. 피로 미호소 그룹에서 AC/A비가 높게 나타났고, 피로 호소 그룹에서는 근거리 사위도가 높게 나타났다. 3D 영상 시청 이후에서는 피로 미호소 그룹에서 더 높은 외사위도 증가 경향을 나타냈다. 본 실험에서 나타난 상관관계에서 AC/A비와 근거리 사위도가 3D 영상 시청 시 느끼는 자각적 피로도와 밀접한 관련이 있는 것으로 나타났다. 3D 영상 시청 시 두 데이터에 기반하여 피로도를 예측할 수 있을 것으로 보이며 콘텐츠 제작 시에도 피로도 경감 차원의 주요한 근거 데이터로 사용될 것으로 판단된다.

• 반도체디스플레이기술학회지
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• 제20권2호
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• pp.43-50
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• 2021

The properties of materials which are widely used in industry fields like automobile, shipbuilding, casting, and electronics are strongly needed to have higher surface hardness, lower surface roughness, and higher compressive residual stress. As mentioned above, for the purpose of satisfying three factors, a variety of researches with respect to surface improvement have been actively studied and applied to every industry. SKD61 which is mostly used for die casting process of cold chamber method must meet a countless number of problems which are thermal, mechanical and chemical from highly specific working environment at high temperature over 600℃. Above all, in case of plunger sleeves used for die casting process, thermal fatigue has a bad effect on the surface of an inlet where molten metal is repeatedly injected. On account of it, plunger sleeves cause manufacturers to deteriorate quality of products. Therefore, in this paper, to improve the surface of an inlet of plunger sleeve, multilayer PVD coating using Ti, Cr and Mo is suggested. Furthermore, The surface characteristics such as surface roughness(Rsa, Rsq), surface hardness(HRB, HRC) and residual stress using XRD(X-ray diffractometer) of coated samples and specimens are studied and discussed.

• 대한인간공학회지
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• 제22권3호
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• pp.27-44
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• 2003

An experiment was carried out to compare the suitability in visual tasks between flat and conventional (convex) cathode-ray tube (CRT) displays. The subjects performed visual search tasks during 2-h for detecting target words among distracters presented on the screen. The subjects' visual performance was evaluated with average time and number of errors made to complete the tasks. Visual fatigue after the search tasks was also evaluated in terms of degradations in accommodative power and subjective ratings. Difference was not found in task time between the two displays, but flat CRT showed a lower number of errors than conventional CRT. The difference in number of errors was statistically significant at 0=0.05. Although there was no difference between the displays in degradations of accommodative power, results from the subjective ratings showed that flat CRT yields less fatigue than conventional CRT. The results partially support the hypothesis that panel convexity of CRT displays has a significant effect on the performance and fatigue during visual tasks and thus flat CRT is the better display than conventional one.

• 대한인간공학회지
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• 제32권3호
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• pp.273-278
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• 2013

Objective: This study aims to analyze and evaluate fatigue in upper trapezius muscles of adults when inputting text on a smart phone, thereby examining the risk of cumulative trauma disorders in the musculoskeletal system of the upper extremity. Method: Forty-five healthy adults were divided equally into three groups: a smartphone group, a notebook group, and a desktop group. A surface electromyogram was placed on the upper trapezius muscle of each participant, after which they inputted text for ten minutes within an ergonomic setting; their side posture was recorded on video and analyzed. Results: The spectral edge frequency values for the smartphone group, as recorded from the upper right trapezius muscles on the surface electromyogram, showed a significant decrease(p<.05). Regarding the RULA, all three groups had results indicating "action level 2". Conclusion: All three groups had results indicating "action level 2" according to the RULA, which means that additional research on the posture of the participants while performing tasks is necessary, and their posture needs to be corrected. In particular, the smartphone group has the highest levels of fatigue in the upper trapezius muscles, suggesting that the task of inputting text on a smartphone is a high risk for causing cumulative trauma disorders.

• Journal of Preventive Medicine and Public Health
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• 제24권3호
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• pp.305-313
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• 1991

In order to investigate industrial fatigue due to visual display terminal (VDT) work of banking operations the questionnaire survey for subjective symptoms of fatigue was carried out on 470 bank clerks who had been engaged in VDT work for various length of work hours. The questionnaires comprised three groups of 10 items each, representing dullness and sleepiness (level of cerebral activation), difficulty in concentration (level of motivation) and bodily projection of fatigue. The results were as follows : 1. Of the 30 items of questionnaires, the highest percentage was accounted for by 'eye strain' (51.5% ), followed by 'feel stiffness in the neck or the shoulders'(33.4%), 'feel a pain in the low back'(26.8%), 'whole body feels tired'(19.6%) and 'feel headache'(17.9%) in the order of sequence. 2. The average weighted score for the first group of questionnaire items (dullness and sleepiness) was the largest among three groups and was followed by 'the third cup (bodily projection of fatigue) and the second item group (difficulty in concentration) in the order of sequence, suggesting the heavier mental stress of VDT work in banking operations rather than physical burden. 3. In terms of the age and sex of workers, work duration and VDT work percentage, the difference in average weighted score was noted only between sex, the score of female being larger than that of male. 4. The complaint rates of subjective symptoms showed close associations with the subjective optimums of room temperature, ventilation, illumination and noise level. 5. The significant correlation was showed between age, work duration and item of 'whole body feels tired', between VDT work percentage and items of 'eye strain' and 'feel stiffness in the neck or shoulders' and between all items of subjective symptoms.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2005년도 춘계종합학술대회
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• pp.1145-1148
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• 2005

본 논문에서는 다양한 시각적 정보와 일정한 관련 정보를 통합하여 인간의 피로도를 추론하기 위하여 베이지안 네트워크를 기반으로 한 확률 모델을 제안하고자 한다. 먼저 눈꺼풀의 움직임, 시선, 머리의 움직임, 그리고 얼굴 표정 같은 개인의 상태를 특성 지을 수 있는 시각적 매개변수를 측정하였다. 그러나 각각의 시각적 정보와 일정한 관련 정보만으로 인간의 피로도를 결정하기에는 충분하지 않으므로, 본 논문에서는 인간의 피로도를 모니터링 하기 위하여 가능한 많은 관련 정보와 시각 정보를 융합하여 베이지안 네트워크 모델을 개발하였다. 실험 결과, 피로 예측과 모델링을 위해 제안된 베이지안 네트워크의 유용함을 확인 할 수 있었다.

• 디지털융복합연구
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• 제16권10호
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• pp.531-536
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• 2018

본 연구는 젊은 성인에서 근업시간에 따른 눈 피로도의 정도를 파악하고, 시각적 불편함의 종류를 분석하였다. 평균 연령 25.37세의 347명(남 142명, 여 205명)을 대상으로 눈 피로도와 관련 요인에 대해 설문하였다. 눈 피로도는 Conlon 등이 개발한 시각적 불편함에 관한 설문 도구를 이용하였고, 근업시간은 일일 컴퓨터와 스마트폰 사용을 조사하였다. 대상자의 눈 피로도는 근업시간이 2시간미만, 2~4시간, 4~6시간, 그리고 6시간 이상일 때 각각 $13.65{\pm}7.11$점, $16.83{\pm}6.77$점, $18.88{\pm}6.60$점, 그리고 $18.83{\pm}5.62$점으로 증가하였다(p=0.001). 또한 근업시간에 따라 두통(p<0.030)과 함께 다시 읽기(p<0.036), 안구운동과 탈색(p<0.001)과 같은 시각활동에서 불편함을 느꼈다.