• Journal of Korean Physical Therapy Science
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• v.13 no.3
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• pp.15-25
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• 2006

The purpose of this study was to investigate effects of different chair type (with backrest chair and without backrest chair) and pelvic position (anterior pelvic tilting and posterior pelvic tilting) on three abdominal muscles (upper rectus abdominis, external oblique, internal oblique) and back extensor activation during lower extremity exercise. The four different conditions during bilateral knee extension exercise were: (1) leaning on backrest chair with anterior pelvic tilting, (2) leaning on backrest chair with posterior pelvic tilting, (3) anterior pelvic tilting without backrest chair, and (4) posterior pelvic tilting without backrest chair. Fifteen healthy male subjects with no history of neuromusculoskeletal disease voluntarily participated in this study. Electromyography (EMG) was used to collect muscle activation data, and muscle activation data was expressed as a percentage of maximal voluntary isometric contraction (%MVIC). One-way repeated analysis of variance (ANOVA) was used to determine the statistical significance, and Bonferroni comparison was used as a post hoc test. The results of this study were the following: (1) Erector spinae activation was significantly lower in posterior pelvic tilting without backrest compared with that in leaning on backrest chair with anterior pelvic tilting. (2) Upper rectus abdominis activation was significantly lower than erector spinae in all four different chair type and pelvic tilting conditions.

• Journal of Power System Engineering
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• v.18 no.6
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• pp.45-50
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• 2014

In the previous paper, we have reported on the development of foaming sponge seat with the auxiliary spring member and suggested new possibility of the special seat with the auxiliary plastic member for movie theater chair. In this study, we have examined the major design parameters needed in the development of a foaming sponge seat in which the mesh type plastic member are inserted to improve the vibration transfer effect of a chair seat. Through analyzing several prototypes by applying experimentation as well as the experimental modal analysis method, it was confirmed that the effect of vibration transfer can be improved through the use of a mesh type plastic member and applied to the design of practical chair seat.

• Journal of Korea Game Society
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• v.10 no.6
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• pp.47-55
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• 2010

In this research, a chair type game controller has been developed. We implement pressure sensors on a chair so that user's whole body movements can be signalized. The signals linked to a game system. This process occurs a meaningful exercise effect. Because users can play exergame setting on the chair type game controller, it is reduces risk of physical injury such as falling down and the Joint pressure compared existing exergame controllers. Based on the advantages of seating, elderly and obese can be provided appropriate exergame.

• Journal of the Korea Furniture Society
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• v.18 no.4
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• pp.296-306
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• 2007

As life style changes, the demand for stacking chairs are increasing as the use of event halls or outside furniture where people gather in crowd is increasing. Early stacking chairs were mainly made to pile up a great amount and store, but in modern days it also has a decorative purpose. Besides, the development of various new materials and applied technology of furniture manufacture, the structure and design of stacking chair is becoming more interesting. Basically, according to the structure of the leg, the form and method of piling up is decided. The structure of the leg means the location of the leg connected to the seat, and according to the location, it can be piled up as upper, front, or rotational type. Such is the way how stacking chairs are classified according to the location of the leg, with its basis; the structure of stacking chair is reviewed. Now, chair for piling up is overcoming its simple function, which aesthetic beauty or arrangement of color after piling up is being considered. Also, according to storing, moving, and the place of use, various designs are demanded. As people's interest in stacking chair is increasing, various research regarding design should continue.

• Korean Institute of Interior Design Journal
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• v.18 no.6
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• pp.36-43
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• 2009

Structure is one of the most important components in designing chairs, since a chair should support the weight of users and make them feel comfortable. However, previous studies have focused on examining the materials and the techniques of processing of chairs, but less on studying the structures to facilitate human friendly use enough to influence the change of the current chair design. The purpose of this study is to analyze the composition element in structure of the chair design specifically from 2000 to 2008 the fundamentals to achieve quality chair design. This study examined 386 chairs which the most reputable furniture fair, the Milan International Furniture Fair exhibited from 2000 to 2008. 386 chairs were chosen from 72 companies which passed the popularity and ranks. 24 Components of the structure of chairs were used to annalize the 386 chairs. The structural types of chair design included 51 kinds. Among them, the most representative types appeared to be 5 kinds. Particularly, the single structure chair was comprised of 25%, its productivity has increased steadily since 2004 which indicated that the structure of chair has become simplified. According to the components of chair, classified structure types were analyzed into (1) a single structure consisting of one component, (2) a simple structure with two components, (3) a complex structure with three components, and (4) a multiple structure with four components. The majority of chair types followed the order of the single structure, simple structure, complex structure, and multiple structure. The results of the analysis on the structure of chairs indicated that the structure of chairs has been changed toward single type No. 24 and simple type No. 6+13.

• Journal of the Ergonomics Society of Korea
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• v.33 no.2
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• pp.143-153
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• 2014

Objective: The aim of this study is to investigate the effects of trunk-forearm supported sitting on trunk flexion angle, trunk extensor fatigue and seat contact pressure. Background: The relationship between sitting posture and musculoskeletal disorders of the trunk extensor fatigue and seat contact pressure has been documented. The trunk-forearm support type ergonomic chair was devised from the fact that trunk-forearm support has been reported to reduce trunk extensor activity and discomfort. Method: Using three different sitting postures, upright ($P_1$), trunk-forearm supported ($P_2$) and normal sitting ($P_3$), six healthy subjects participated in the study. Motion capture system was used to collect head and trunk flexion angle, and surface electromyography (sEMG) was used to collect myoelectric signal of upper trapezius, lower trapezius, erector spinae, multifidus, and pressure mat system was used to measure seat contact pressure. Results: When trunk and forearm were supported by the ergonomic chair, higher head flexion angle showed upright > trunk-forearm supported > normal in order, and muscle fatigue showed less than upright and normal sitting. Mean seat contact pressure decreased 19% than upright sitting. But muscle fatigue was not affected by each condition. Conclusion: Trunk-forearm supported sitting of the ergonomic chair showed positive effect in respect of trunk and head flexion angle, trunk extensor fatigue, seat contact pressure. To acquire comprehensive understanding of the effectiveness of the ergonomic chair, further studies such as anatomical effects from measurement of external applied loading effect to the body from interface pressure analysis are required. Application: The results of the publishing trend analysis might help physiological effects of trunk-forearm support type chair.

• Journal of the Society of Naval Architects of Korea
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• v.54 no.5
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• pp.361-367
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• 2017

A membrane type LNG cargo tank is equipped with a pump tower and a liquid dome for loading and unloading of LNG. However, the membrane running continuously on the tank wall to prevent leakage of LNG is interrupted by the liquid dome, hence care should be taken in the design of liquid dome and its substructures. In case of GTT NO96 membrane type cargo containment system, chair structure is arranged along the periphery of the liquid dome targeting to support the membrane which is exposed to the both hull girder and thermal load. This paper proposes a new and simple chair structure, which outperforms traditional design from productivity point of view maintaining same level of structural safety. Strength assessment on the new design was performed to guarantee the structural safety of the new design, which includes strength, fatigue and crack propagation analysis.

• Journal of Power System Engineering
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• v.17 no.6
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• pp.40-46
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• 2013

This paper describes the suggestion of the special seat with the auxiliary plastic member for movie theater chair. In the previous paper, we have reported on the development of foaming sponge seat with the auxiliary spring member. And we have confirmed that it was more effective on vibration transfer than the chair seat of foaming sponge only. In this study, we have examined the major design parameters needed in the development of a foaming sponge seat in which the mesh type plastic member are inserted to improve the vibration transfer effect of a chair seat. By applying experimentation to the prototype as well as the experimental modal analysis method, we made sure that the effect of the vibration transfer could be improved through the use of a mesh type plastic member as similar as the auxiliary spring member.

• The Journal of Korea Assosiation for Disability and Oral Health
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• v.10 no.2
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• pp.78-83
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• 2014

The objective of this study was to confirm the validity of classification of dental disability by measuring the dental treatment time required for disabled patients and identify the disability type that requires more of chair time. As a result of measuring a total of 123 patients who were admitted to the Seoul dental hospital for the disabled on Oct. 2014, I was able to make the following conclusions: 1. For dental counseling and check-up, the chair time did not show significant differences between the different types of disability. 2. For periodontal treatment, restorative treatment, root canal treatment, and surgical treatment, the difference of the chair time for dentally disabled patients was significantly longer than that of non-dentally disabled patients. 3. The difference in the total chair time for prosthetic treatment was statistically insignificant. However, each of the prosthetic treatment steps did show statistically significant differences.

• 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.