• Journal of Korean Physical Therapy Science
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• v.26 no.1
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• pp.9-14
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• 2019

Background: Pes planus, or flat foot, causes lower limb malalignment and foot pain during walking or exercise. Therefore, a highly reliable evaluation method to accurately diagnose flat feet is necessary. This study investigated the intra-and inter-rater reliability of the navicular drop test in different postures. Design: Cross sectional study. Methods: Forty healthy volunteers performed the navicular drop test in three different combinations of non-weight-bearing and weight-bearing postures (standing/standing, sitting/sitting, and sitting/standing). Two examiners alternately performed the measurements five times in each subject, and in each posture. Significant differences in measurements were obtained among the three postures, with the highest navicular drop being observed in the sitting/standing posture. Results: Inter-rater reliability was high in the sitting/standing and sitting/sitting postures. Intra-rater reliability was high in all three postures. In the sitting/sitting and sitting/standing postures, large navicular drop values and high inter- and intra-rater reliability were observed. Conclusion: Therefore, the sitting/standing and sitting/sitting postures are recommended for use in navicular drop tests to diagnose flat feet.

• Journal of the Ergonomics Society of Korea
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• v.28 no.3
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• pp.81-85
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• 2009

Work related musculoskeletal disorders(WMSDs) was a leading cause of sick leave and injuries in the industries of our country. Posture was an important consideration in the design of work method and workplaces, because it affected the ability of workers to use various equipments and influenced how long they could perform their job without feeling discomfort, fatigue, and musculoskeletal disorders. Imbalanced lower limb postures such as a squatting posture were awkward working postures common to the shipbuilding shops, farms, automobiles assembly lines in our country. Different awkward working postures were known to be associated with specific musculoskeletal disorders. Eight postures in lower limb postures divided into balanced and imbalanced postures were evaluated by electromyographic(EMG) activity for lower limb muscles. Twelve male subjects participated in this study. This paper was to analyze the effects of lower limb muscles workload according to lower limb postures(knee angle) and working time. The ANOVA results showed that most EMG root mean square(RMS) values were statistically significant effect according to lower limb postures(knee angle) and working time. Therefore, the results of this study will provide the basis to evaluate workload of lower limb postures correctly adopted by workers in various jobs and the ergonomic reference to prevent WMSDs.

• Journal of the Ergonomics Society of Korea
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• v.22 no.1
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• pp.43-56
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• 2003

Observational methods such as OWAS, RULA, and REBA have been widely used to identify posture-related risks of musculoskeletal disorders in industry, since they are useful and efficient in evaluating postural stresses. However. there are few studies comparing the methods and providing guidelines for selecting and using the methods. They have been developed based on different backgrounds and with different application areas. Each method has its own characteristics. which must be considered in selecting and using them. In this study. 17 male subjects evaluated 42 different working postures that frequently assumed in the automobile assembly line using a psychophysical method. The postures were then evaluated by different observational methods. The results of the observational methods were compared with psychophysically evaluated stresses. The observational methods resulted in different values of stresses for certain postures. For some postures showing high values of perceived discomfort. the observational methods showed different values of stresses. These results showed that the observational methods should be used differently according to application area and they have some weak points to be improved.

• Journal of the Ergonomics Society of Korea
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• v.34 no.2
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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.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.2737-2742
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• 2003

Kinematic calibration enhances absolute accuracy by compensating for the fabrication tolerances and installation errors. Effectiveness of calibration procedures depends greatly on the measurements performed. While the Cartesian postures are measured completely, all of the geometric parameters can be identified to their true values. With partial pose measurements, however, few geometric parameters may not be identifiable and effectiveness of the calibration results may vary significantly within the workspace. QR decomposition of the identification Jacobian matrix can reveal the non-identifiable parameters. Selecting postures for measurement is also an important issue for efficient calibration procedure. Typically, the condition number of the identification Jacobian is minimized to find optimum postures. This paper investigates identifiable parameters and optimum postures for four different calibration procedures - measuring postures completely with inverse kinematic residuals, measuring postures completely with forward kinematics residuals, measuring only the three position components, and restraining the mobility of the end-effector using a constraint link. The study is performed for a six degree-of-freedom fully parallel HexaSlide type paralle manipulator, HSM. Results verify that all parameters are identifiable with complete posture measurements. For the case of position measurements, one and for the case of constraint link, three parameters were found non-identifiable. Optimal postures showed the same trend of orienting themselves on the boundaries of the search space.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1476-1481
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• 2003

Kinematic calibration enhances absolute accuracy by compensating for the fabrication tolerances and installation errors. Effectiveness of calibration procedures depends greatly on the measurements performed. This paper investigates identifiable parameters and optimum postures for four different calibration procedures - measuring postures completely with inverse kinematic residuals, measuring postures completely with forward kinematics residuals, measuring only the three position components, and restraining the mobility of the end-effector using a constraint link. The study is performed for a six degree-of-freedom fully parallel HexaSlide type parallel manipulator, HSM. Results verify that all parameters are identifiable with complete posture measurements. For the case of position measurements, one and for the case of constraint link, three parameters were found non-identifiable. Selecting postures for measurement is also an important issue for efficient calibration procedure. Typically, the condition number of the identification Jacobian is minimized to find optimum postures. Optimal postures showed the same trend of orienting themselves on the boundaries of the search space.

• The Journal of Korean Physical Therapy
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• v.34 no.1
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• pp.12-17
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• 2022

Purpose: Ankle dorsiflexion is an essential element of normal functions, including walking, activities of daily living and sport activities. The tibialis anterior (TA) muscle functioned as a dorsiflexor and as a dynamic stabilizer of the ankle joint during walking and jumping. This study aimed to compare TA muscle thickness using ultrasonography according to the four different toe and ankle postures for the selective TA strengthening exercise. Methods: This study were recruited 26 (males: 15, females: 11) aged 20-30 years, with no injury ankle and calf in the medical history, had normal dorsiflexion and inversion range of motion (ROM). The thickness of the TA muscle was measured by ultrasonography in the four different toe and ankle postures: 1. Ankle dorsiflexion with all toe extension and ankle inversion (ITEDF); 2. Ankle dorsiflexion with all toe flexion and ankle inversion (ITFDF); 3. Ankle dorsiflexion with all toe extension and neutral position (NTEDF); 4. Ankle dorsiflexion with all toe flexion and neutral position (NTFDF). One-way repeated analysis of variance (ANOVA) and Bonferroni correction were used to confirm the significant difference among conditions. The level of statistical significance was set at α=0.01. Results: TA muscle thickness with ITFDF was significantly greater than in any other ankle positions, including ITEDF, NTFDF, and NTEDF (p<0.01). Conclusion: Among the four toe and ankle postures, isometric contraction in ITFDF postures showed the greatest increase in thickness of TA rather than ITEDF, NTEDF, and NTFDF postures. Based on these results, ITFDF can be recommended in an efficient way to selectively strengthen TA muscle.

• Korean Journal of Occupational Health Nursing
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• v.11 no.2
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• pp.121-131
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• 2002

Objective: The purpose of this study was to determine the physical load by identifying harmfully working postures and to develop recommendations for improving the existing situation with nurses in ICU, thereby to provide the basis for development of work-related musculoskeletal preventive program. Method: Various types of tasks were recorded with a video camera to chart and analyze different postures by OWAS(Ovako Working Posture Analysing System). Collected data showed that poor postures were adopted, not only for lifting or repositoning a patient, but also for other tasks. Data Analysis: The performed activities were then divided into Nursing Intervention Classification. Altogether 128 postures were selected for analysis. Then they were classified into different OAC (OWAS Action Categories). From all the observation, unhealthy postures, for which corrective measures had to be considered immediately (i.e., 75% classified as OACII+III+IV) were found. Collected data were analyzed in terms of percentage, 2-tail Mann-Whitney U test. Result: Poor postures mainly occur during 'positioning the patient' and 'airway suctioning' in NIC. No difference was found (p=0.060) between the percentage of harmful posture adopted during the patient handling tasks and non-patient handling tasks. Conclusion: This study shows, that in the nursing profession with ICU not only occur during patient handling, but also during other activities. The OWAS method was useful in determining the physical load by locating potential activities due to harmfully working postures, providing a detailed description with analysis, and suggesting successful means to reduce postural load.

• 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.

• Journal of the Ergonomics Society of Korea
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• v.28 no.1
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• pp.9-19
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• 2009

Repetitive movement, inadequate working posture, overuse of force, physical contact with sharp edge, vibration and temperature were well known risk factors of WMSDs (Work-related Musculoskeletal Disorders). Many researchers have investigated the relationship between inadequate working postures and incidences of WMSDs of the upper extremities, whereas relatively few researchers have tried to evaluate workload associated with the lower-body postures. The effects of lower-limb postures including various knee flexion angles on the subjective discomfort, heart rate and EMG of lower-limb muscles were investigated in this study. Thirty graduate students were asked to maintain thirteen different body postures, and heart rate and EMG data of five muscle groups (electro spine, biceps femoris, vastus medialis, gastrocnemius and tibialis anterior) from each posture were collected during fifteen minutes sustaining tasks. All participants were also asked to report their discomfort ratings of body parts. Results showed that high subjective discomfort ratings and heart rates were reported at the postures of knee angles of $60^{\circ}$ and $90^{\circ}$, whereas low discomfort ratings were founded at the postures of chair heights with 20cm, 40cm, and sitting with crossed legged. The change of median frequency for each muscle group during fifteen minutes tasks was investigated for each body posture to evaluate the relationship between muscle fatigue and body posture. It was found that the trends of changes of median frequency were different based on muscle group as well as lower-limb body posture from this study.