• Journal of the Ergonomics Society of Korea
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• v.15 no.2
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• pp.51-62
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• 1996

This research utilized the psychophysical methodology, where secrw drivers are used, to determine the effects of i) the location and orientation of work objects, and ii) wearing gloves, on ratings of perceived exertion at various body parts. The validity of the psychophysical methodology in determining a preferred work pace was also studied. The subjects drove screws with a screw driver into thick wooden sheet at three vertical and three horizontal locations. They drove serews for 3 minutes at each location and assessed the condition using the psychophysical scale. The results showed that only the vertical location was a significant factor in determining the discomfort ratings. Driving screws at elbow height on the vertical surface and with the lower arm close to the body on the horizontal surface were the work locations with the smallest ratings of perceived discomfort. Wearing gloves had significant effects on reducing the pain of the hand. From the experiment in which a comfortable work pace was identified using 20 minute psychophysical adjustment, it was found that the psychophysical method is sensitive to workers perception of the physical stress when the upper limbs are employed. This was confirmend by the high correlation between the psychophysical results and EMG measurement.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.10 no.2
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• pp.73-82
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• 2004

Objectives : In order to develop the measuring tool of visual display terminal (VDT) syndrome and investigate the variables affecting the development of VDT syndrome. Methods : A questionnaire study accompanied with the evaluation of working environment was performed with 42 VDT users from banking operations. Results : As a results of analysis with data colleted by newly developed questionnaire, VDT syndrome included five factors named as eye-related component, and psychological component. general body discomfort component. musculoskeletal component, and skin-related component. The scores of eye-related symptoms was 15.17, scores of psychological symptoms was 7.36, scores of general body discomfort symptoms was 10.52, scores of musculoskeletal symptoms was 9.38, scores of skin-related symptoms was 3.67, and total scores was 46.10. Scores of 2.05 eye fatigue in the level of eye-related symptoms were higher significantly. Scores 50.52 of female was statistically higher than scores 41.67 of male. Conclusions : The subjective symptoms of VDT syndrome scores was significantly associated with gender and age.

• Journal of the Ergonomics Society of Korea
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• v.30 no.5
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• pp.671-681
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• 2011

Objective: The purpose of this study is to compare the workload level at each lower limbs posture and suggest the ergonomic workstation guideline for working period by evaluating the imbalanced lower limbs postures from the physiological and psychophysical points of view. Background: Many workers like welders are working in various imbalanced lower limbs postures either due to the narrow working conditions or other environmental conditions. Method: Ten male subjects participated in this experiment. Subjects were asked to maintain 3 different lower limbs postures(standing, squatting and bending) with 3 different working conditions(balanced floor with no scaffold, imbalanced floor with 10cm height of scaffold, and imbalanced floor with 20cm height of scaffold). EMG data for the 4 muscle groups(Retus Femoris, Vastus Lateralis, Tibialis Anterior, Gastrocnemius) from each lower limbs posture were collected for 20 seconds every 2 minutes during the 8 minutes sustaining task. Subjects were also asked to report their discomfort ratings of body parts such as waist, upper legs, lower legs, and ankle. Results: The ANOVA results showed that the EMG root mean square(RMS) values and the discomfort ratings(CR-10 Rating Scale) were significantly affected by lower limbs postures and working time(p<0.05). The correlation was analyzed between the EMG data and the discomfort ratings. Also, prediction models for the discomfort rating for each posture were developed using physical condition, working time, and scaffold height. Conclusion: We strongly recommend that one should not work more than 6 minutes in a standing or squatting postures and should not work more than 4 minutes in a bending posture. Application: The results of this study could be used to design and assess working environments and methods. Furthermore, these results could be used to suggest ergonomic guidelines for the lower limbs postures such as squatting and bending in the working fields in order to prevent fatigue and pain in the lower limbs body.

• Proceedings of the ESK Conference
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• 1997.04a
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• pp.90-94
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• 1997

Many workers like welders are working in squat sitting postures with te object on the ground for an entire work shift. It is suspected that such prolonged squat sitting without any supporting stool would gradually cause musculoskeletal injuries to workers. This study is to quantitatively evaluate the physical stress caused by the prolonged squat sitting and to recommend a safe work/rest schedule for the task with squat sitting posture based on the lab experiment. In this study, 8 healthy student subjects participated in the experiment. They maintained a squat sitting posture for 16 minutes with 4 different stool height conditions: no stool, 10cm hight, 15cm height, 20cm height. Every 2 minutes, the discomfort was subjectively assessed using the magnitude estimation method for the whole body, lower back, upper leg and lower leg. Based on discomfort rating, we found that 10cm height stool relieved the workload most. Discomfort rating results also indicated that 20cm height stool showed the heghest workload, and that there was no difference in workload between 15cm height and no stool. We recommend to provide the workers with 10cm height stool for prolonged squat sitting tasks.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.1260-1264
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• 2006

Shock-type vibrations are usually experienced in vehicles excited by impulsive forces. Fifteen subjects used magnitude estimation to judge the discomfort of vertical shock-type vibration generated on a rigid seat. The shocks had different frequencies and magnitudes and were produced from the response of a 1 degree-of-freedom model to a half-sine force input. The magnitudes of the shocks, expressed in terms of both peak-to-peak value and un-weighted vibration dose values, VDVs, were correlated with magnitude estimates of the discomfort. In this study, equivalent comfort contour of shock-type vibration were obtained. From the contour, it was investigated that shock-type vibration at frequency below 0.8 Hz and between 4.0 Hz and 10.0 Hz is highly sensitive to the discomfort than at other frequencies.

• Journal of the Korean Society of Safety
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• v.14 no.1
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• pp.185-192
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• 1999

The purpose of this study is to investigate the physical disorders of CTDs prevalent among dentists who are exposed to job risk factors. The average total work time per week of subjects(N=117) was 44$\pm$6 hours, work time with one patient was 20$\pm$10 minutes, and their daily tasks were consisted of extraction, filling, preparation, nerve amputation of tooth. The results of this study are as follows: 1) The discomfort test shows that dentists suffer from discomfort/pain in upper extremities. 2) The work environment test related to CTDs shows that female dentists feel more uncomfortable in the height of chairs than male dentists. 3) The symptom test shows that female dentists suffer from more pain in fingers or wrists at night than male dentists.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.24 no.65
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• pp.31-40
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• 2001

We Propose an improved shovel design to minimize physical discomfort and the risk of cumulative trauma disorder at shoveling tasks. The specifications of shovels in Korean standard data were scrutinized to check if they met the anthropometric specification of Korean population in 1997. We also applied "Body Map" pictograph and self-conscious checklist to field survey to analyze the discomfort of shoveling task. Thirty male subjects whose age were ranging from 18 to 65 voluntarily participated in the experiment. The measurement results show that shoveling workers were exposed to hazards of CTD's. Especially, when workers were involved in ditch digging and construction their trunk vend more than 120 degree. In order to compare the new designed shovel and the traditional K.S shovel, an analysis of variance was performed and we obtained very strong evidence that the new designed shovel was better in reducing physical discomfort. According to the results from electromyograrn experiment the new shovel contributed to improving subjective comfort level and reducing low back muscle fatigue. For futher study, the research may be extended to determine the relationship among shovel sharpness, type, digging motion and digging force.ing force.

• Journal of Korean Institute of Industrial Engineers
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• v.28 no.2
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• pp.216-222
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• 2002

The ergonomic human model can be considered as a tool for the evaluation of ergonomic factors in vehicle design process. The proper anthropometric data on driver's postures are needed in order to apply a human model to vehicle design. Although studies on driver's posture have been carried out for the last few decades, there are still some problems for the posture data to be applied directly to the human model due to the lack of fitness because such studies were not carried out under the conditions for the human model application. In the traditional researches, the joint angles were evaluated by the categorized data, which are not appropriate for the human model application because it is so extensive that it can not explain the posture evaluation data in detail. And the human models require whole-body posture evaluation data rather than joint evaluation data. In this study a postural evaluation function was developed not by category data but by the concept of the loss function in quality engineering. The loss was defined as the discomfort in driver's posture and measured by the magnitude estimation technique in the experiment using a seating buck. Four loss functions for the each joint - knee, hip, shoulder, and elbow were developed and a whole-body postural evaluation function was constructed by the regression analysis using these loss functions as independent factors. The developed postural evaluation function shows a good prediction power for the driver's posture discomfort in validation test. It is expected that the driver's postural evaluation function based on the loss function can be used in the human model application to the vehicle design process.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.14 no.4
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• pp.255-268
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• 1992

There are various modalities in the treatment of facial asymmetry, but in severe case with TMD by actively growing deformed condyle, the treatment choice is removing the condyle growth center and TMD symptom such as click or muscular discomfort. In our one case, the patient was complain of facial asymmetry. There are severe deformed condyle head with bird-head fashion and enlarged mandibular ramus and body vertically about 18 mm, overgrowthed Rt. mandible body horizontally about 20 mm. She had intermittent Lt. TMJ clicking and muscular discomfort. The author diagnosed it as Lt. hemimandibular hyper-plasia & R, hemimandibular elongation, a combination form with TMD. the condyle was in active growing state in scintigraphic analysis. So we extirpated the deformed condyle by intrasoral sagittal split ramus osteotomy and reshaped the condyle and mandibular distal fragment extraorally. The distal fragment was readapted in glenoid fossa and fixated. In Rt. mandibular body area, autogenous onlay bone graft on the inferior border of mandible was performed to correct the asymmetry. The clicking and facial asymmetry was corrected and we report this results with other literature findings.

• Journal of Fashion Business
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• v.5 no.3
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• pp.49-61
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• 2001

In this study, girdle wearing was surveyed on the female college students in Seoul and Seoul satellite cities. Data were collected by convenient sampling method, and sample size was 252 subjects in 18 to 29 years. Questionnaire was composed of 5 parts: experience of girdle wearing, the preference of girdle type, degree of dissatisfaction/discomfort in wearing girdle, wear sensation evaluation of girdle fabrics, including demographic and anthropometric data. The results of surveys are as follows: Experience of girdle wearing (season of wearing girdle, main intention of wearing girdle, frequency of wearing, body part to want to be shaped by girdle) was examined. Especially body parts to be shaped by girdle were in order of abdomen > hip > thigh > waist-hip sideline. Therefore, it would be considered that female college students want to care about the shape of abdomen or hip. The long leg panty type was most preferred among the girdle types. The reason of preference of long leg panty type was cost > easiness of putting on-and-off > shaping many body parts at once. For dissatisfaction/discomfort in wearing the commercial girdles, it showed in order of poor ventilation at sweating > static electricity with outer garment > difficult breathing due to pressure > deformation after laundering.