• 대한인간공학회지
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• 제34권2호
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• pp.135-143
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• 2015

Objective: The purposes of this study are to investigate ergonomic problems and to propose their improving measures in office environment of big general hospitals. Background: Office tasks have varying risk factors of work-related musculoskeletal disorders (WMSDs). The first symptom resulted from the office work was recognized as an occupational disease in Korea in 1986. Although the symptoms have increased since its first recognition, there has been few study on the effect of office work environment settings. Method: First, the author took pictures of working scenes performed in three big university hospitals. Next, the pictures were analyzed in view point of ergonomics. Based on the analysis, their improving measures were proposed for reducing work stress. Results: The results showed that most physical office environment settings such as dimensions of tables/desks and chairs, leg room, thigh, knee and foot clearances, and chairs used did not satisfy the ergonomically recommended design guidelines. In addition, some clerks placed personal belongings under their desks, put monitors in high position and did not lean against the backrest of chairs in seated tasks, which resulted in poor working postures of leg, back, neck etc. It is recommended that the hospital management should provide their clerks with ergonomically designed office furniture and continuously perform ergonomics training program for raising clerks' recognition for office ergonomics. Conclusion: Most office environment settings investigated in this study were not in good condition in view point of ergonomic design for the settings. Application: It would be useful as basic data for establishing ergonomically good office environment in hospitals.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.860-864
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• 2008

In modern society, people tend to spend their time on various types of chairs. However, it is not easy for a designer to design a comfortable chair, because satisfaction with the chair depends not only on the quantitative elements such as size, but also on the qualitative element such as the user's feeling. To deal with these problems, there have been many studies on designing an ergonomics chair. In this paper, the hapticaided design (HAD) system was adopted to design the ergonomics chair. Based on the HAD system, the designer can experience whether the chair is comfortable or not through the haptic device, and also can modify the design parameters instantaneously. The haptic chair capable of controlling the design parameters in real time was proposed as a haptic simulator. The controllable parameters such as the seat height, reclining angle, stiffness of the backrest, and so on were selected based on the previous researches related to ergonomics chairs. It will reduce the development cost and time by replacing the process of making the real mock-up and prototype with the haptic chair.

• 한국생산제조학회지
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• 제22권3_1spc호
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• pp.587-592
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• 2013

Until recently, the primary users of wheelchairs were people with lower body disabilities. However, the number of patients recovering from accidents or surgery, as well as the number of elderly people using wheelchairs, is constantly increasing. This study examined the design and manufacture of standing and gait assist wheelchairs that assist temporary gait disturbed patients to take rehabilitation training and elderly people to engage in walking exercise. A kinematic analysis was used to select a drive motor and design a four-bar linkage mechanism for lifting the backrest vertically. Using a multibody dynamic simulation, detailed design was performed taking into consideration the spatial motion and partial interference, and the necessary push force and stroke of the linear actuator were also calculated. To ensure structural safety, the von-Mises equivalent stresses of the upper and lower brackets of the linear actuator were verified through a finite element analysis. The manufactured wheelchair was shown to operate successfully as intended, using the developed controller for the drive motors and linear actuator.

• 대한인간공학회지
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• 제26권3호
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• pp.111-115
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• 2007

Design equations for anthropometric product design are developed by considering the geometrical relationships of design dimensions and anthropometric dimensions. The present study applied the design structure matrix (DSM) method to the development of design equations for a computer workstation, and compared design values from the design equations with corresponding design values of ergonomic recommendations and existing products. The relationships between design dimensions (e.g., legroom and worktable) were analyzed by a DSM, and then the application order of design equations (e.g., seatpan, backrest, armrest, legroom, and worktable in descending order) was determined. Next, design equations were developed by analyzing the geometric relationships between computer workstation design dimensions and anthropometric dimensions. Finally, design values for a computer workstation were determined by considering a standard posture defined and representative human models (5th, 50th, 95th %ile). The design values calculated using the design equations were similar with those of ergonomic recommendations found in literature and two commercial products measured in the study; however, some design values (e.g., seatpan height) were different due to discrepancy in standard posture. The DSM method would be utilized to systematically analyze the relationships between design dimensions for anthropometric product design.

• 한국정보전자통신기술학회논문지
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• 제8권1호
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• pp.59-64
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• 2015

연구의 목적은 트랙터와 운전자의 인터페이스에서 중요한 연결고리인 트랙터 시트에 대한 인간공학적 설계인자의 도출이다. 대상 인구집단은 한국과 미국의 성인남녀이며 앉은엉덩이오금수평길이, 앉은어깨뼈높이, 앉은팔꿈치 높이 등 7종의 인체측정변수를 사용했다. 시트 설계 인자로는 좌석면의 크기, 등받이의 크기 및 팔걸이의 위치를 도출했다. 척주의 형태와 피복 효과 또한 고려되어야 하며, 본 연구의 결과가 소형 트랙터에 적용되는 시트의 설계 과정에서 가이드라인으로 활용되기를 기대한다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 추계학술대회논문집
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• pp.369-374
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• 2004

This study aims to measure an apparent mass of a seated human body at the sitting posture in a passenger car in the frequency range from 1 to 20 Hz and to investigate the dynamic characteristics. Thirty subjects joined the test where eight levels of acceleration from $0.1m/s^2\;to\;2.0m/s^2$ were used to excite seated human body. Most of apparent mass curves showed two peaks in the frequency range of $4\sim9Hz$, first peak was clearer at the contact point of the seat and the hip, and the second one at the contact point of the backrest and the back. Both peak frequencies were found to move down to lower frequencies with increase of acceleration magnitude. Shapes of apparent mass curves were clearly different from those at erect posture especially in the frequency range around and above the second peak.

• The Journal of Korean Physical Therapy
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• 제34권4호
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• pp.155-160
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• 2022

Purpose: This study was to identify the effect of cervical stabilization exercise with visual feedback on the craniovertebral angle and foot pressure in subjects with forward head posture. Methods: Thirty healthy adults were recruited in the study. Participants were randomly assigned to the stabilization exercise with visual feedback (SE-VF) group (n=15) or stabilization exercise (SE) group (n=15). The SE-VF group performed cervical stabilization exercise while sitting on a chair without a backrest and checking their side profile in real time a monitor 3m away. The SE group performed the same cervical stabilization exercise as the SE-VF group accompanied by without visual feedback. Craniovertebral angle (CVA) was measured to quantify forward head posture, and the foot pressure of the subjects were evaluated. Results: The foot pressure showed statistically significant differences pre and post in both midfoot and left metatarsal only in SE-VF group (p<0.05). Conclusion: These findings of this study showed that the cervical stabilization exercise with visual feedback was effective for the foot pressure of subjects. In addition, based on the results of this study, it is suggested that visual feedback will be effective in cervical stabilization exercise.

• 대한인간공학회지
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• 제34권2호
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• pp.191-198
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• 2015

Objective: As a cue for desired mood, we attempted to identify types of sitting postures when people are involved in various tasks during their working hours. Background: Physical behaviors in reaction to user contexts were studied, such as automated posture analysis for detecting a subject's emotion. Sitting postures have high feasibility and can be detected robustly with a sensing chair, especially when it comes to an office. Method: First, we attached seven sensors, including six pressure sensors and one distance sensor, to an office chair. In Part 1, we recorded participants' postures while they took part in four different tasks. From the seven sensors, we gathered five sets of data related to the head, the lumbar, the hip, thigh pressure and the distance between the backrest and the body. We classified them into four postures: leaning forward, upright, upright with the lumbar supporting, and leaning backward. In part 2, we requested the subjects to take suitable poses for the each of the four task types. In this way, we compared the matches between postures and tasks in a natural setting to those in a controlled situation. Results: We derived four types of sitting postures that were mapped onto the different tasks. The comparison yielded no statistical significance between Parts 1 and 2. In addition, there was a significant association between the task types and the posture types. Conclusion: The users' sitting postures were related to different types of tasks. This study demonstrates how human emotion can interact with lighting, as mediated through physical behavior. Application: We developed a posture-based lighting system that manipulates the quality of office lighting and is operated by changes in one's posture. Facilitated by this system, color temperatures ranging between 3,000K and 7,000K and illuminations ranging between 300lx and 700lx were modulated.

• 대한인간공학회지
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• 제34권2호
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• pp.179-190
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• 2015

Objective and Background: Due to increase in Musculoskeletal Disorders (MSDs) relating to computer use, a number of ergonomics recommendations have been proposed in order to tackle this problem. However, some of these recommendations have been conflicting. Method: This study was to survey the VDT (Visual Display Terminal) use of office workers. The subjects were 452 workers at 13 places of business and the data were collected by self-administered questionnaire. Results: As a result, prevalence of self-reported MSDs of all VDT workers was 90.2% and shoulder took up 57.0% and neck 38.3% by symptom part of body. The population of computer use of more than 6h/day was 84.5%, and 33.8% also reported using the VDT 2~3h/day without the rest time. Desktop computer users were 95.6%, and a 17-inch monitor accounted for 42.0% among the desktop users. As a result of satisfaction survey on overall computer work, 21.1% of the total respondents said satisfied, desk complaint was about 24.6%, and chair complaint was 33.4%. Despite the importance of computer environment, satisfaction was from fair to uncomfortable. Conclusion and Application: In conclusion, office workers are prone to the MSDs due to their work environment. Additionally, this study found that task was a significant effect for the majority of dependent variables, and therefore, the improvement of computer workstations work environment is urgent, and the improvement of desk height adjustment, chair seat size (length, width), backrest condition, location of keyboard (mouse) and arm rest is required.

• 대한인간공학회지
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• 제33권2호
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• pp.125-134
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• 2014

Objective: The purpose of this study is to evaluate integral seat desk used in universities through comparison of real dimension values of the desk with KS/ISO standard and questionnaire survey. Background: School furniture that helps students sit comfortably for longer periods of time and allows for better concentration on learning is important. However, seat and desk have been generally designed based on the industry practice rather than user's anthropometry, and seats and desks used in universities of Korea have not been ergonomically evaluated. Method: Real 13 dimensions of the desk used in K University were measured using tape measure and inclinometer, and the dimension values were compared to the KS standard of desk and chair for lecture room (KS G 4210) and ergonomic design principles found in relevant references. Subjective appropriacies and preference for the desk were investigated based on questionnaire survey, in which 121 (male: 91, female: 30) college students participated. Results: Several dimensions for the desk and chair investigated except desk depth and width, leg room width, seat width have not met the KS standard, but all dimensions satisfied ergonomic design principles available in references. The questionnaire survey revealed that appropriacies for desk surface size, seat pan depth, seat pan cushion and backrest curvature were under middle point of 3.0, and that those for the other dimensions showed higher scores exceeding 3.0. Conclusion: The integral seat desk widely used in universities showed some design problems in terms of standards of KS G 2010 and KS G 4210, and ergonomic design principles. Compared to the general desk with separated desk and seat, subjective preference on the integral seat desk was low. Application: This would be used as a valuable guideline when designing or choosing new integral seat desk with high satisfaction of students.