• Journal of the Ergonomics Society of Korea
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• v.33 no.2
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• pp.167-174
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• 2014

Objective: This research focuses on the working environment of office workers and aims to propose an ideal seating posture and chair design. Background: Generally, office workers having to seat in a fixed posture for long periods of time tend to suffer from an increased rate of musculoskeletal disorders. Method: The measurement and survey of 123 office workers on their working conditions and literature survey will lead to a suggestion of an ideal seating posture and workstation design theory. Results: Work environment satisfaction appeared low for chair and desks. Work-related pain over the last year was experienced among 47.2% of the respondents in shoulder (34.2%), neck (30.9%). Observation of working posture revealed that only 27.6% of workers utilize backrest during work. Conclusion: Office work embodies many situations where risks of musculoskeletal disorders may be high. Thus, the seated workplace must be set up to allow proper seating posture for workers. Application: The results of this study can be applied as baseline data for preventing musculoskeletal disorders of office workers.

• Proceedings of the KSR Conference
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• 2000.11a
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• pp.210-218
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• 2000

It is absolutely important to design passenger seat so that train passengers can satisfy because passenger seat is one of the most important parts in tile determination of passenger's satisfaction for train.. So, it is necessary to consider passengers' characteristics, requirements, and dissatisfactions in seat design. However, passengers' dissatisfactions for the seat of Mugunghwa-ho train have been often raised through various routes. It is necessary to resolve their dissatisfactions to provide comfortable trip to passengers. So, we designed a seat of new Mugunghwa-ho train that resolved passengers' dissatisfactions. Our focusing design parts were the seat pan and the backrest of passenger seat. We investigated passengers' dissatisfactions for the seat of Mugunghwa-ho train through various methods and the human factors design guidelines of passenger seat through literature survey. We designed a new seat on the basis of investigated results. For newly designed seat, we evaluated comfort, sensible satisfaction, and fitness in comparison with the existing seat. An experimental method and a subjective method were used in this evaluation. In all aspects, new seat was superior to the existing.

• Proceedings of the KSME Conference
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• 2000.11a
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• pp.381-386
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• 2000

Simple spring-damper-mass models have been widely used to understand whole-body vertical biodynamic response characteristics of the seated vehicle driver. However, most previous models have not considered about the non-rigid masses(wobbling masses). A simple mechanical model of seated human body developed in this study included the torso represented by a rigid and a wobbling mass. Within the 0.5-20Hz frequency range and for excitation amplitudes maintained below $5ms^{-2}$, this 4-degree-of-freedom driver model is proposed to satisfy the measured vertical vibration response characteristics defined from a synthesis of published data for subjects seated erect without backrest support. The parameters are identified by using the combinatorial optimization technique, simulated annealing method. The model response was found to be provided a closer agreement with the response characteristics than previously published models.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.2
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• pp.193-200
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• 2002

Simple spring-damper-mass models have been widely used to investigate whole-body vortical biodynamic response characteristics of the seated vehicle driver. Most previous models have not considered the effect of wobbling masses; i.e. heart, lungs, liver, intestine, etc. In this study, 4 -DOF seated driver model including one non-rigid mass representing wobbling visceral mass, 5-DOF model including intestine, and 10-DOF model including five lumbar vertebral masses were proposed. The model parameters were identified by a combinatorial optimization technique. simulated annealing method. The objective function was chosen as the sum of error between model response of seat-to-head transmissibility and driving point mechanical impedance and those of experimental data for subjects seated erect without backrest support. The model response showed a good agreement with the experimental response characteristics. Using a 10-DOF model, calculated resonance frequency of lumbar spine at 4Hz was matched well with experimental results of Panjabi et al.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.241-245
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• 2003

When considering the effects of whole-body vertical vibration, it is valuable to have an understanding of the mechanical characteristics (mechanical impedance and apparent mass) of the body. This paper addresses experimental results carried out to investigate the characteristics of apparent masses fer 41 Korean. The apparent masses of the seated human body in vertical direction were measured during different experimental conditions, such as vibration excitation level (0.5-2 ms$\^$-2/ r.m.s). frequency range (1-50Hz), and upper body posture (relaxed, normal and backrest-upright). We showed the average of all subjects and all conditions and compared the results with ISO5982/DIS (2000).

• IE interfaces
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• v.14 no.2
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• pp.210-217
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• 2001

Because passenger seat is one of the most important parts in the determination of passengers' satisfaction for train, it is absolutely important to design the passenger seat so that train passengers can satisfy. So, in the seat design it is necessary to consider passengers' characteristics, requirements, and dissatisfactions. However, passengers' dissatisfactions for the seat of Mugunghwa-ho train have been often raised through various routes. It is necessary to resolve their dissatisfactions to provide comfortable trip to passengers. So, we designed a new seat of Mugunghwa-ho train that resolved passengers' dissatisfactions. Our focusing design parts were the seat pan and the backrest of passenger seat. We investigated passengers' dissatisfactions for the seat of Mugunghwa-ho train through various methods and the human factors design guidelines through literature survey. We designed a new seat on the basis of investigated results. For newly designed seat, we evaluated comfort and sensible satisfaction in comparison with the existing seat. An experimental method and subjective methods were used in this evaluation. In all aspects, the new seat was superior to the existing.

• Journal of Drive and Control
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• v.20 no.2
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• pp.1-6
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• 2023

This study aims to develop a Korean dental chair hydraulic circuit by improving the existing equipment in order to localize foreign leading companies' products. The suggested Hydraulic circuit can be applicable to varied sectors where height and backrest angle control of chair-type equipment are required. The study followed the steps below. First, three kinds of foreign hydraulic circuits were analyzed and three kinds of Korean dental chair hydraulic circuits were suggested. Second, it was determined whether the three kinds of Korean hydraulic circuits operate normally through SimulationX, a software specialized in multi domain analysis, and the effectiveness of each circuit was examined.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.11
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• pp.1581-1586
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• 2010

Haptic-aided design (HAD) involves the use of a haptic simulator in place of physical prototypes in the design and development of products with which human beings interact physically. The development time and cost can be significantly reduced by adopting this HAD scheme. Although both physical and emotional factors are equally important, only the emotional factors were taken into consideration in the previous HAD process. Consequently, the design of the products was sometimes unsatisfactory from the viewpoint of ergonomics, even though users were emotionally satisfied with the products. To overcome this problem, in this study, we propose a new human-oriented design methodology that is enhanced by taking the physical factors into consideration. The HAD scheme was verified by using a haptic chair simulator to design a tilt mechanism of an office chair for which the stiffness of the backrest can be adjusted; then, the design was simulated using MADYMO. The results show that the proposed method can reflect both the physical and emotional factors to modify the design in real-time.

• Journal of the Korean Society of Physical Medicine
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• v.11 no.3
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• pp.119-124
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• 2016

PURPOSE: The aim of this study was to evaluate activation of accessory respiratory muscles using electromyography during chest expansion upper extremity flexion, abduction, and external rotation exercises with an elastic band in children with cerebral palsy. METHODS: The subjects were 10 children with cerebral palsy. The inclusion criterion for participation was a Gross Motor Function Classification System level of I to III. The subjects were instructed to perform upper extremity flexion, abduction, and external rotation exercises with inspiration, and extension, adduction, and internal rotation exercises with expiration while seated on a chair without a backrest. PM (Pectoralis major), SCM (sternocleidomastoid), RA (rectus abdominis), and EO (external oblique) muscle activities were measured using electromyography. RESULTS: All tested muscles showed a statistically significant increase in activity after elastic band exercise. There were significant differences in PM, SCM, RA, and EO results after chest expansion exercise using elastic band. SCM showed the largest increase in activity after use of elastic bands, at $52.37{\pm}45.88$%, followed by the RA ($50.56{\pm}79.31$), EO ($35.42{\pm}35.45$), and PM ($31.72{\pm}25.64$). The increase in the SCM was greatest, followed by increases in the RA, EO, and PM CONCLUSION: These finding suggest that activity of accessory respiratory muscles increases with use of elastic bands during chest expansion exercise in cerebral palsy.

• Journal of Korean Institute of Industrial Engineers
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• v.25 no.1
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• pp.100-110
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• 1999

The objectives of this study are twofold: (1) to evaluate the cockpit of three Korean air force fighters such as F-4, F-5, and F-16 in an ergonomic perspective and (2) to measure the musculoskeletal discomfort of the fighter pilots. For the study, 369 air force pilots from 7 squadrons were surveyed. The study shows that the cockpit design of F-16 is superior to the others. However, F-4 is the worst among them. Statistical analyses reveal that the seat in the cockpit raised the most complaints, regardless of types of fighter planes. The main problems with the seat included inappropriate designs of the backrest angle, seat cushioning, and parachute harness. Also frequently cited are various control switches, control stick, rudder pedal, and the throttle. That these items lack human integration is found in remote positions and improper dimensions. The implications of these findings are discussed. The self-reported musculoskeletal complaints show that the main discomfort is on the back and neck. Also, the buttocks, shoulders, and the legs/knees are common sites of discomfort. A stepwise regression analysis shows that the back discomfort, is mainly caused by the use of the seat, rudder pedal, control stick, and switches. A Spearman rank correlation coefficient test also reveals that job dissatisfaction of the pilots is related to the complaints with the cockpit and musculoskeletal discomfort. These findings suggest that more comprehensive studies for cockpit design in the aspects of functional anthropometry of Korean pilots are needed to reduce the musculoskeletal discomfort.