• Journal of the Ergonomics Society of Korea
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• v.9 no.2
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• pp.55-63
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• 1990

School children sit long on chairs in their classrom. Their posture is closely related to their chairs. Study of this relationship is very imporant for the health and education of school children. This report presents the results of study condcuted to determine the present status of classroom chairs and solve any problems identifede. The study involved 125 teachers in Seoul and Pusan, 175 fourth graders in Seoul, and 109 fourth graders in Puasn. The body dimensions of the school children and the dimensions of their chairs and desks were measured, and their postures while they studied at their desk were photographed. The following problems were identified as a result of the investigation: (1) Chairs are allocated to pupils according to their stature. (2) The teachers are not satisfied with the chairs and the method by which the chairs are allocated to their pupils. (3) The pupils complain of low seat height, narrow seat, and hard backrest, among other conditions. (4) The pupils select a chair one size larger than that suggested by their body size. (5) The poor posture of the pupils is traced to the seat height and sasyaku$(sitting height {\times} 1/3-1)$ of their chairs, their habit, their way of holding pencils, and lack of instruction by their teachers. The following recommendations are made to solve these problems: (1) Adjust the seat height and desk height to accommodate the pupils. (2) Provide both teachers and pupils with adequate knowledge of chails. (3) Provided each pupil with one desk and make the desk adjustable to sit his or her body dimensions. (4) Allocate a chair and desk to each pupil for his or her exclusive use. (5) Reserch and develop conversion tables that help to find suitable chails for individual pupils. New values of sasyaku and desk height, not specified in Korean Industrial Standards(KS), are proposed.

• The Korean Journal of Physiology
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• v.4 no.1
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• pp.29-46
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• 1970

Measurement and analysis of the physical status (height, body weight, breast girth, sitting height. length of leg, length of thigh, thigh girth, crural length, length of arm, brachial length, antebrachial girth and skinfold thickness), physical types and the growth were made to the 360 Korean middle and high school boys aged between 12 and 17 years in Taegu City. The physical status was evaluated and expressed as dispersion and the Physical type as percentage of each status to height, and the growth was analysed by the growth formula. The results are as follows; 1) The increase of the volumes of Physical status was slowest between 12 and 13 years and fastest between 13 and 14 years in general. 2) The increase of the volumes of thigh girth and antebrachial girth showed a linear pattern until 16 years. 3) The coefficient of variation was largest in skinfold thickness $(16.3{\sim}28.4%)$ followed by body weight $(10.0{\sim}14.3%)$, antebrachial girth $(4.8{\sim}19.60%)$ and length of thigh$(6.3{\sim}13.6%)$. The coefficients of variation in all the other status were similar $(4{\sim}7%)$. 4)The physical indices of body weight, breast girth, sitting height, length of thigh, thigh girth, antebrachial girth and skinfold thickness increased as age increased while the others decreased except the brachial length, which showed no significant change. 5) Ratio of growth quantity was largest in body weight followed by skinfold thickness, and the others were all similar. 6) Growth rate and specific growth rate decreased in the all the status analysed as age increased except in the skinfold thickness in which an increase was noted. 7) Growth gradient was increased along the increase of age in breast girth, sitting height, crural length, brachial length and in skinfold thickness. However a decrease was observed in the other status except in the body weight which was decreased until 15 years of age and increased thereafter.

• Korean Journal of Applied Biomechanics
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• v.33 no.1
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• pp.25-33
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• 2023

Objective: The purpose of this study was to investigate the differences in static arch height and ankle stability according to the preference for insole height and hardness in the arch area. Method: The study participants were 20 adult males (age: 22.7 ± 1.8 yrs., height: 175.3 ± 4.3 cm, body weight: 72.5 ± 7.7 kg). First, the arch heights of all subjects were measured in static postures (sitting and standing). The inversion and eversion movements of the ankle joint were analyzed during walking (1.3 m/s & 1.7 m/s) and running (2.7 m/s & 3.3 m/s). The variables (static arch height, and inversion and eversion angle of ankle joint) were compared by classifying groups according to the preference for the height and hardness of the arch of the insole. First, it was divided into a high arch insole preference group (HAG, n=8) and a low arch insole preference group (LAG, n=12) according to the preference for the arch height of the insole. Second, it was divided into a high hardness insole preference group (HHG, n=7), medium hardness insole preference group (MHG, n=7), and low hardness insole preference group (LHG, n=6), according to the preference for the arch hardness of the insole. Results: First, the range of motion (ROM) of inversion-eversion at the ankle joint during walking was statistically smaller in HAG than in LAG (p<.05). Second, the arch height change of HHG was statistically greater than that of MHG and LHG (p<.05). Conclusion: In the case of flexible flat feet with a large change in arch height, providing a high hardness arch insole that can disperse foot pressure can improve comfort. It was found that people with high medial and lateral sway of the ankle joint preferred a low arch insole, but it is necessary to differentiate and compare the insole heights of the arch part in detail. In addition, in the case of fast motion such as running, the preference for the arch height and hardness of the insole was not related to the static arch height and ankle stability.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.8 no.3
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• pp.205-211
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• 2014

The purpose of this document is to provide basic data helpful in selecting seating device material by examining the affects of polyurethane foam material on seating pressure. In order to achieve this study objective, four seats, 6cm in height, were produced in hardness of: 13, 28, 25, and $45kg/cm^2$. To measure the sitting pressure distribution (depending on the characteristics of the produced seats), 10 healthy subjects participated in the experiment. XSENSOR was used a measuring device, and each seat was mounted on a wheelchair simulation. By analyzing the obtained data with Average Pressure(AP), Peak Pressure(PP,), and Contact Area(CA), the sitting pressure was measured for five minutes on each seat. This experiment showed the following results: There were significant differences between the AP, PP, and CA in the seat material (p<0.5). While the hardness of $18kg/cm^2$ showed low pressure, the hardness of $45kg/cm^2$ showed high pressure. This study also showed that seat material made of polyurethane should be considered when selecting seats. If polyurethane foam is used in seat recommendations, it will be recommended to use $18kg/cm^2$ for the proper hardness of the seat material.

• Journal of the Ergonomics Society of Korea
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• v.35 no.6
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• pp.595-609
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• 2016

Objective: The purpose of this study was to develop and validate the guidelines for Medic Work Table (MWT) based on the anthropometric data of medical technologists. Background: Users' anthropometric data such as sitting height, sitting elbow height, knee height, and so on are significant factors for designing comfortable and useful furniture. Thus, many guidelines for different types of desks and chairs based on the users' anthropometric data have been suggested to many researchers. However, few researches have been conducted to provide design guidelines for MWT for blood collecting task. Medical technologists often use their upper extremities to perform blood collecting task with high repetitions. These repeated motions could be a critical factor in the prevalence rate of Work-related Musculoskeletal Disorders (WMSDs). Therefore, a study on ergonomic design of MWT would be essential in preventing the WMSDs and improving the quality of the working environment of medical technologists. Method: This study suggested design guidelines for ergonomic MWT by focusing on the heights of the upper side and underside, depths of the inside and outside, and width of MWT through anthropometric studies and literature reviews. Afterwards, a new MWT was made using the suggested design guidelines for this study. Five healthy medical technologists participated to evaluate the original MWT and new MWT. All participants took part in the range of motion (ROM) test, electromyography (EMG) muscle activity test, and usability test to validate the suggested guidelines in this study. EMG signals of related muscles (Flexor Carpi Ulnaris, Extensor Carpi Ulnaris, Deltoid Anterior, and Biceps Branchii) were recorded through the surface electromyography system from both the original MWT and the new MWT. The ROM test of the shoulder and elbow flexion was also assessed using motion sensors. Results: The newly designed MWT showed decreased ROMs of the shoulder and elbow up to 22% and 18% compared to the original MWT. The muscle activities in the new MWT also showed a decrease of 13% in Anterior Deltoid, 6% in Biceps Brachii, 5% in Flexor Carpi Ulnaris, and 8% in Extensor Carpi Ulnaris muscle groups, compared to the original MWT. In the usability test, the satisfaction score of the new MWT was also 56.1% higher than that of the original MWT. Conclusion: This study suggested guidelines for designing MWT and validating the guidelines through qualitative and quantitative analyses. The results of motion analysis, muscle activity, and usability tests demonstrated that the newly designed MWT may lead to less physical stress, less awkward posture, and better physical user interface. Application: The recommended guidelines of the MWT would be helpful information for designing an ergonomic MWT that reduces physical loads and improves the performance of many medical technologists.

• Journal of Korea Society of Digital Industry and Information Management
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• v.13 no.4
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• pp.81-90
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• 2017

This paper presents a smart seat for correction of driver posture while driving. We introduce good postures with seat height, seat angle, head height, back of knees, distances of foot pedals, tilt of seat, etc. There have been some studies on correction of good posture while driving, effects of driving environment on driver's posture, sitting strategies based on seating pressure distribution, estimation of driver's standard postures, and others. However, there are a few studies on guide of good postures while driving for problem of driver's posture using machine leaning. Therefore, we suggest a smart seat for correction of driver's posture based on machine leaning, 1) developed the system to get postures by 10 piezoelectric effect element, 2) collect piezoelectric values from 37 drivers and 28 types of cars, 3) suggest 4 types of good postures while driving, 4) analyze test postures by kNN. As the results, we can guide good postures for bad or problems of postures while driving.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.19 no.2
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• pp.19-22
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• 2013

Background: Excessive pronation of the feet can cause excessive inner rotation of the femur, followed by increased stress in the gluteus maximum, increased front slope of the pelvis, and lumbar lordosis, which leads to lumbar pain. The aim of the present study was to use the navicular drop test to examine foot pronation that can cause lumbar lordosis and to determine whether the navicular drop is lower in patients diagnosed with lumbar disc than in patients without this diagnosis. Methods: The Navicular Drop score was set by subtracting the navicular height at a standing position from the navicular height in a sitting position. The Navicular Drop measurements for college student with and without Lumbar Herniated Intervertebral Disc were compared using an independent t-test. Results: The control group were measured right $7.44{\pm}2.96$ and left $8.04{\pm}3.23$. The experimental group were measured right $2.12{\pm}1.33$ and left $2.80{\pm}1.29$. Therefore significant difference was found between the two groups (p<0.05). Conclusions: The navicular drop affected lumbar herniated intervertebral disc.

• Clinical and Experimental Pediatrics
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• v.60 no.10
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• pp.327-332
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• 2017

Purpose: Short stature affects approximately 2%-3% of children, representing one of the most frequent disorders for which clinical attention is sought during childhood. Despite assumed genetic heterogeneity, mutations or deletions in the short stature homeobox-containing gene (SHOX ) are frequently detected in subjects with short stature. Idiopathic short stature (ISS) refers to patients with short stature for various unknown reasons. The goal of this study was to screen all the exons of SHOX to identify related mutations. Methods: We screened all the exons of SHOX for mutations analysis in 105 ISS children patients (57 girls and 48 boys) living in Taif governorate, KSA using a direct DNA sequencing method. Height, arm span, and sitting height were recorded, and subischial leg length was calculated. Results: A total of 30 of 105 ISS patients (28%) contained six polymorphic variants in exons 1, 2, 4, and 6. One mutation was found in the DNA domain binding region of exon 4. Three of these polymorphic variants were novel, while the others were reported previously. There were no significant differences in anthropometric measures in ISS patients with and without identifiable polymorphic variants in SHOX. Conclusion: In Saudi Arabia ISS patients, rather than SHOX, it is possible that new genes are involved in longitudinal growth. Additional molecular analysis is required to diagnose and understand the etiology of this disease.

• Physical Therapy Rehabilitation Science
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• v.11 no.2
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• pp.145-153
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• 2022

Objective: The purpose of this study was to evaluate the Electromyography (EMG) of the upper limb during reaching tasks according to two heights in the sitting position. Design: Cross sectional design Methods: Fifteen hemiplegia, fifteen elderly, and fifteen healthy subjects have participated in this study. The targets (90% length of the subject's arm) were located at the two heights (the eye and xiphoid process). We have recorded EMG signals of seven upper limb muscles (anterior deltoid (AD), posterior deltoid (PD), pectoralis major (Pec), infraspinatus (Inf), supraspinatus (Sup), biceps brachii (Bi), triceps brachii (Tri)). The dependent variables were movement time(s), modulation ratio, working ratio, and the co-contraction ratio of the hemiplegia, elderly, and healthy at the reaching task. Two-way repeated-measures ANOVA (2-heights) was analyzed with the LSD post hoc test. Results: The study results were as follows: (1) The movement time to the target during reaching movement was significantly longer for the hemiplegia and elderly groups compared to the healthy group. (2) The modulation rate was significantly higher at eye height than the xiphoid height in AD, PD, Pec, Inf, Bi muscles, and the hemiplegia group and elderly group were significantly lower than the healthy group. Additionally, the modulation ratio showed a significant interaction between heights and groups. Conclusions: It is expected that the variables using the muscle contraction characteristics, the evaluation method of this study, can be used as an electromyography-based feedback method that can be objectively evaluated and quantified in clinical practice.

• The Journal of Korean Physical Therapy
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• v.35 no.3
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• pp.83-88
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• 2023

Purpose: This study was to investigate the effect of forward head posture (FHP) and round shoulder posture (RSP) on changes in muscle activities according to shoulder flexion and abduction tasks. Methods: Twenty-two male subjects with no history of neurological, musculoskeletal surgery or injuries, or pain in the spine region within the previous 3-month periods were recruited for this study. Craniovertebral angle (CVA) and Scapula Index were measured before performing 90° abduction and flexion tasks holding a 3kg dumbbell. Muscle activities were measured during the tasks. All measurements except height of the acromion were carried out in a sitting position at the height of the subject's knee angle of 90 degrees, and two tasks were randomly performed with the arm that the subject mainly use to throw the ball. The abduction and flexion angles were checked by the examiner using a goniometer beside the subject. Results: Correlation coefficient analysis between Scapular Index and upper trapezius muscle activity during shoulder abduction task showed significant positive correlation. No significant correlation was observed between CVA, Scapular Index, and other muscle activities. Conclusion: FHP showed increased muscle activation, making it difficult to change muscle activity under lower loads, and RSP was correlated with UT activation in shoulder abduction. Therefore, in the RSP, the loaded shoulder abduction is considered a potential risk factor for increasing shoulder muscle tension. This paper proposes an approach to treating RSP before FHP.