• 대한인간공학회지
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• 제24권2호
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• pp.9-15
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• 2005

The purpose of this study is to quantitatively investigate perceived discomfort of complex shoulder postures with external loads and to propose a preliminary evaluation scheme of shoulder postures. Twelve healthy male adults participated in an experiment to rate their perceived discomfort of shoulder postures. The independent variables were shoulder flexion angle(45, 90 and 150$^{\circ}$), adduction/abduction angle(-30, -10, 0, 30 and 60$^{\circ}$), and external load(0, 1.5 and 3.0kg). The results revealed that the flexion angle, external load and their interaction significantly affected the perceived discomfort(p$<$0.05) but the effect of adduction/abduction angle on the discomfort was not significant(p$>$0.05). The effect of external load was much larger than that of any other factor with explaining about 81% of the total variation of discomfort scores. Based on the experimental results a preliminary scheme was presented to evaluate the stress of shoulder postures with external loads.

• 대한인간공학회지
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• 제25권4호
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• pp.145-151
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• 2006

The objective of this study is to investigate the perceived discomfort for postures combined with shoulder flexion/extension and elbow flexion, and external load. 12 healthy male undergraduate and graduate students participated in this experiment. Experimental variables were the shoulder flexion/extension angle(-20°, 0°, 45°, 90°, 135°), the elbow flexion angle (0°, 45°, 120°), and the external load(0, 1.5Kg, 3Kg) as independent variables and a whole body perceived discomfort using Borg's CR10 as a dependent variable. The subjects maintained the given posture for 60 seconds and then rated the perceived discomfort. The ANOVA results showed that all main factors and two-way interactions were statistically significant at α=0.05. As a result of regression analysis to examine the effect of external load on the perceived discomfort, the perceived discomfort linearly increased as the level of external load increased. Then, the effect of external load on the perceived discomfort was quantitatively classified into three levels based on the result of regression analysis.

• 한국전문물리치료학회지
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• 제24권2호
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• pp.1-8
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• 2017

Background: Individuals with spinal cord injury (SCI) rely on their upper limbs for body-lifting activity (BLA). While studies have examined the electromyography (EMG) and kinematics of the shoulder joints during BLA, no studies have considered foot position during BLA. Objects: This study compared the effects of different foot positions during BLA on the shoulder muscle activities, peak plantar pressure, knee flexion angle, and rating perceived exertion in individuals with SCI. Methods: The study enrolled 13 mens with motor-complete paraplegic SCI, ASIA (American Spinal Injury Association) A or B. All subjects performed BLA with the feet positioned on the wheelchair footrest and on the floor independently. Surface EMG was used to collect data from the latissimus dorsi, pectoralis major, serratus anterior, and triceps brachii. The peak plantar pressure was measured using pedar-X and the knee flexion angle with Image J. Borg's rating perceived exertion scale was used to measure the physical activity intensity level. The paired t-test was used to compare the shoulder muscle activities, peak plantar pressure, knee flexion angle, and rating perceived exertion between the two feet positions during BLA. Results: The activity of the latissimus dorsi, pectoralis major, serratus anterior, and triceps brachii and rating perceived exertion decreased significantly and the peak plantar pressure and knee flexion angle increased significantly when performing BLA with the feet positioned on the wheelchair footrest compared with on the floor (p<.05). Conclusion: These findings suggest that individuals with SCI may perform BLA with the feet positioned on the wheelchair footrest for weight-relief lifting to decrease the shoulder muscle activities and the rating perceived exertion and to increase the peak plantar pressure and the knee flexion angle.

• 대한인간공학회지
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• 제32권6호
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• pp.541-547
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• 2013

Objective: The aim of this study is to find the influence on muscle fatigue by changing an angle of neck while Shaker exercise. Background: Shaker exercise is commonly applied to dysphagia patients for strengthen suprahyoid muscle(SHM) and relaxing upper esophageal sphincter. Method: Experiments were conducted by measuring muscle fatigue with surface electromyography(SEMG) in case of neck $15^{\circ}$ and $50^{\circ}$ flexion, in addition to original method. For the study 30 undergraduate students were participated as subjects. Muscle fatigue was measured with variations of median frequency(MF) and median frequency slope(MFS) by attaching SEMG to 3 muscles. At the same time, perceived exertion was measured by using Borg's rating of perceived exertion(RPE). Results: A MF was increased when low angle in SHM, both male and female. It means that muscle fatigue was significantly decreased(p<.05). RPE was significantly increased when low angle(p<.01). Perceived exertion explained 15.2% of the variation of MF in SHM. And regression equation was, MF in SHM = 59.918 + (4,910 * RPE). Conclusion: The outcome shows that it is possible to use the efficient method which makes muscle fatigue decrease by reducing the angle of neck flexion. Application: The results might contribute to develop the effective Shaker exercise method.

• 대한인간공학회:학술대회논문집
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• 대한인간공학회 1994년도 춘계학술대회논문집
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• pp.115-123
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• 1994

A man model can be used as an effective tool to design ergomonically sound products and workplaces, and subsequently evaluate them properly. For a man model to be truly useful, it must be integrated with a posture prediction model which should be capable of representing the human arm reach posture in the context of equipments and workspaces. Since the human movement possesses redundant degrees of freedom, accurate representation or prediction of human movemtn was known to be a difficult problem. To solve this redundancy problem, the psychophysical cost function can predict the arm reach posture accurately. But the joint discomfort that human feels at the joint can not be predicted since the effects of external factors on the joint discomfort is not known. In this study a psychophysical experi- ment using the magnitude estimation technique was performed to evaluate the effects of external factors such as joint, joint angle and Perceived Exertion Ratio on the joint discomfort. Results showed that the joint discomfort increased as the Perceived Exertion Ratio increased, but the relation is not linear and was affected not only by the joint but also by the joint angle for the same Perceived Exertion Ratio. The interaction effect of the joint and the joint angle was also significant. From the results it is needed to develope the cost function which can predict the joint discomfort considering the joint, joint angle and external load.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제39권
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• pp.4.1-4.7
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• 2017

Background: This study is a quantitative evaluation of the influence of the mentolabial angle on perceived attractiveness and threshold values of desire for surgery. Methods: The mentolabial angle of an idealized silhouette male Caucasian profile image was altered incrementally between $84^{\circ}$ and $162^{\circ}$. Images were rated on a Likert scale by pretreatment orthognathic patients (n = 75), lay people (n = 75) and clinicians (n = 35). Results: A mentolabial angle of approximately $107^{\circ}$ to $118^{\circ}$ was deemed the most attractive, with a range of up to $140^{\circ}$ deemed acceptable. Angles above or below this range were perceived as unattractive, and anything outside the range of below $98^{\circ}$ or above $162^{\circ}$ was deemed very unattractive. A deep mentolabial angle ($84^{\circ}$) or an almost flat angle ($162^{\circ}$) was deemed the least attractive. In terms of threshold values of desire for surgery, for all groups, a threshold value of ${\geq}162^{\circ}$ and ${\leq}84^{\circ}$ indicated a preference for surgery, although clinicians were least likely to suggest surgery. The clinician group was the most consistent, and for many of the images, there was some variation in agreement between clinicians and lay people as to whether surgery is required. There was even more variability in the assessments for the patient group. Conclusions: It is recommended that in orthognathic and genioplasty planning, the range of normal variability of the mentolabial angle, in terms of observer acceptance, is taken into account as well as threshold values of desire for surgery. The importance of using patients as observers in attractiveness research is stressed.

• 한방재활의학과학회지
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• 제15권2호
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• pp.169-181
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• 2005

Objectives : The 5th lumbar - 1st sacrum facet joint is unstable area from an anatomical viewpoint, so that it is clinically major causes of low back pain. The purpose of this study is to assess the difference of the Van Akkerveeken measurement and intervertebral disc angle, Ferguson angle between the 5th lumbar - 1st sacrum facet syndrome patients and sample group patients. Methods : Van Akkerveeken measurement, intervertebral disc angle and Ferguson angle were measured in 30 patients who had 5th lumbar - 1st sacrum facet syndrome and 31 sample group patients. Results : 1. Van Akkerveeken measurement of 5th lumbar - 1st sacrum facet syndrome patients is statistically larger that of than sample group patients. 2. Intervertebral disc angle of the 5th lumbar - 1st sacrum facet syndrome patients is statistically larger that of than sample group patients. 3. Ferguson angle is the 5th lumbar - 1st sacrum facet syndrome patients is statistically larger than that of sample group patients. Conclusions : These results suggest that Van Akkerveeken measurement and intervertebral disc angle is able to be used for diagnosis of facet syndrome.

• 한국포장학회지
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• 제11권1호
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• pp.1-10
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• 2005

Paper angle, environment friendly packaging material, has been mainly used as an edge protector. But, we have perceived its application to package design of heavy product such as strength reinforcement or unit load system (ULS) in the future. Above all, understanding of buckling behavior for angle itself and compression strength and quality standard have to be accomplished for the paper angle to be used for this purpose. The purpose of this study was to elucidate the buckling behavior through theoretical and finite element analysis, and to develop compression strength model by compression test for symetric and asymetric paper angle. Based on the result of theoretical and finite element analysis, increasing rate of buckling of asymmetric paper angle was higher as applied load level was bigger and/or the length of angle was longer than that of symmetric paper angle. Decreasing rate of minimum principal moment of inertia was remarkably increased as the extent of asymmetric angle is bigger, and buckling orientation of angle was open direction near the small web. Increasing rate of maximum compression strength (MCS) for thickness of angle was smaller as the web size was bigger in symmetric angle. MCS of asymmetric angle of $43{\times}57$ and $33{\times}67$ was decreased $15{\sim}18%$ and $65{\sim}78%$, and change of buckling was increased $12{\sim}13%$ and $62{\sim}66%$, respectively.

• 한국HCI학회논문지
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• 제7권1호
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• pp.1-10
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• 2012

본 연구는 3D 상영관 내의 각 좌석의 공간적 특징에 따라 3D 효과가 어떻게 나타나는지를 시각피로도, 프레즌스, 인지된 특징을 통해 살펴보았다. 연구결과 극장 좌석의 위치가 스크린으로부터 떨어진 거리와 시야각이 시각피로도와 인지된 특성에 유의미한 영향이 있음을 검증하였다. 연구 결과는 다음과 같다. 첫째, 좌석별 시각피로도와 스크린으로부터의 거리 평균지점으로 부터의 편차와 시야각은 정적 상관관계가 있었다는 점에서 3D 상영관에서 3D 품질을 보장하기 위한 좌석 배치에 유의해야 함을 알려준다. 둘째, 3D 상영관에서 좌석의 위치적 영향이 프레즌스에는 나타나지 않았다. 셋째, 좌석별 인지된 특성과 스크린으로부터의 거리 평균지점으로 부터의 편차와 시야각은 부적 상관관계가 있었다는 점에서 3D 상영관의 모든 좌석에서 3D에 대한 인지된 특성이 다르다는 것을 알 수 있다. 본 연구는 3D극장에서의 실증적인 연구를 통해 공간적 변인에 따른 3D효과를 검증했으며, 연구 결과는 3D극장 좌석의 표준을 제정하기 위한 기초자료로 삼을 수 있다. 또한 3D 영상의 성능지표 및 피로도 규제와 관련한 법 제정에 도움이 될 수 있을 것이다.

• 대한인간공학회지
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• 제21권1호
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• pp.81-93
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• 2002

This study aims to provide joint angles of comfort for females, based on the psychophysical scaling method. Ten female subjects participated in the experiment for measuring perceived discomfort for varying joint motions. The subjects were instructed to maintain given joint motions for a minute, and to rate their perceived discomfort for the motions during a minute's rest by using the free modulus method of the magnitude estimation. Joint angles of comfort were calculated from the regression equations based on the experimental results, in which levels of joint motions were used as independent variables and perceived discomforts as dependent variables. The results showed that joint angles of comfort for the joint motions investigated were much smaller than full range of motions for corresponding joint motions. The ratios of joint angle of comfort to its range motion for the hip were found to be smallest of all joint motions dealt with in this study, and those for the neck were the largest. In addition, comfortable joint angles for females were much smaller than those for males. It is recommended that when designing or evaluating workplaces ergonomically, different comfortable joint angles should be applied according to workers' or population's gender.