• Industrial Engineering and Management Systems
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• 제10권3호
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• pp.185-190
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• 2011

A driver interacts directly with the car seat at all times. There are ergonomic characteristics that have to be followed to produce comfortable seats. However, most of previous researches focused on either static or dynamic condition only. In addition, research on car seat development is critically lacking although Malaysia herself manufactures its own car. Hence, this paper integrates objective measurements and subjective evaluation to predict seat discomfort. The objective measurements consider both static and dynamic conditions. Steven's psychophysics power law has been used in which after expansion; ${\psi}\;=\;a+b{\varphi}_s^{\alpha}+c{\varphi}_v^{\beta}$ where ${\psi}$ is discomfort sensation, ${\varphi}_s^{\alpha}$ is static modality with exponent ${\alpha}$ and ${\varphi}_v^{\beta}$ is dynamic modality with exponent ${\beta}$. The subjects in this study were local and the cars used were Malaysian made compact car. Static objective measurement was the seat pressure distribution measurement. The experiment was carried out on the driver's seat in a real car with the engine turned off. Meanwhile, the dynamic objective measurement was carried out in a moving car on real roads. During pressure distribution and vibration transmissibility experiments, subjects were requested to evaluate their discomfort levels using vehicle seat discomfort survey questionnaire together with body map diagram. From subjective evaluations, seat pressure and vibration dose values exponent for static modality ${\alpha}$ = 1.51 and exponent for dynamic modality ${\beta}$ = 1.24 were produced. The curves produced from the $E_{q.s}$ showed better $R_{-sq}$ values (99%) when both static and dynamic modalities were considered together as compared to Eq. with single modality only (static or dynamic only R-Sq = 95%). In conclusion, car seat discomfort prediction gives better result when seat development considered both static and dynamic modalities; and using ergonomic approach.

• International Journal of Automotive Technology
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• 제6권4호
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• pp.383-390
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• 2005

This study proposes an innovative design guideline to assist the evaluation and improvement of the dynamic comfort of vehicle seating. The existing evaluation method for the comfort of vehicle seating was investigated to broach problems in evaluation. It was found that the currently existing evaluation method employs the resonance frequency of the vibration system composed of the seat and the human body and the maximum vibration transmissibility. This study proposes a design guideline aimed at the enhancement of vibration transmission characteristics above the resonance range, particularly within the range of 10-18 Hz. In order to meet this guideline, a seat was constructed out of foam having a low damping coefficient. It was then installed in a vehicle for a driving test. The driving test confirmed the improvement of the dynamic comfort of the seat. The result of evaluation of the improved seat using the SEAT index, an industry standard widely used to evaluate the dynamic comfort of a seat considering the perceptivity characteristics of the human body, showed that the perceptive vibration transmission had reduced by more than $11\%$. The effect of the modification of seat foam was also verified through a subjective assessment of dynamic comfort of the seats.

• Industrial Engineering and Management Systems
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• 제8권2호
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• pp.121-130
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• 2009

Subjective evaluation has always been regarded as a branch of social science research. Hence, in scientific and especially engineering points of view, its development is always taken for granted despite the importance of its effects on the design and development decisions. In the past, at least two automotive seat survey questionnaires have been developed with high statistical validity and reliability. Nonetheless, both were not local while subjective perception very much depends on demographic background factors. It is felt that since vehicle seat comfort is an important aspect in a seat design, a local sense should be put into the survey that is used as the subjective tool. The proposed vehicle seat discomfort survey questionnaire was developed in dual languages; English and Malay. Malay language is the national language of Malaysia, where the survey was tested. Beside inputs from literatures, key informant interviews helped in establishing the appropriate terms used as survey items. Three experimental runs on two different seats by 22 paid subjects showed that the developed questionnaire is reliable and valid. Furthermore, criterion validity analysis on the survey and previously developed survey showed significant correlation at 0.01 significance level.

• 한국자동차공학회논문집
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• 제22권6호
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• pp.104-112
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• 2014

Generally, numerical approaches of evaluation for vehicle seat comfort have been studied without considering time-dependent characteristics and the only seating moment have been considered in seat design. However, the comfort not only at the seating moment but also in the long-term should be evaluated because the passengers are sitting repeatedly on the seat to drive the vehicle for hours. So, the aim of this paper is to carry out a quantitative evaluation of the time-dependent mechanical characteristics of seat foams and to suggest a process for predicting the viscoelastic deformation of seat foam in response to long-term driving. To characterize the seat materials, uniaxial compression and tension tests were carried out for the seat foam and stress relaxation tests were performed for evaluating the viscoelastic behavior of the seat foam. A unit solid element model was used to verify the reliability of the material model with respect to the compression behavior of the seat foam. It is not straightforward to evaluate the time-dependent compression of foams using the explicit solver because the viscoelastic material model is limited. To use the explicit solver, the material model must be modified using stress-degradation data. Normalized stress relaxation moduli were added to the stress-strain curves obtained under static conditions to achieve a time-dependent set of stress-strain relations that were compatible with the implicit solver. There was good agreement between the analysis results and experimental data.

• 한국산학기술학회논문지
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• 제18권7호
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• pp.476-482
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• 2017

본 연구는 의자 좌면 높이가 척추 세움근과 배곧은근의 근 활성도에 어떠한 영향을 미치는지 알아보고자 실시하였다. 건강한 남녀 30명을 대상으로 세 가지 높이의 의자 좌면에 앉게 하고 양쪽 척추 세움근과 배곧은근의 근활성도를 표면 근전도 장비를 사용하여 측정하였다. 반복측정된 일요인 분산분석을 통해 세 가지 높이의 의자 좌면에 따른 근활성도의 차이를 비교하였고 유의수준(a)은 0.05로 설정하였다. 연구 결과 의자 좌면 높이에 따라 양쪽 배곧은근의 근활성도는 유의한 차이를 보였고 양쪽 척추 세움근의 근활성도는 유의한 차이가 없었다. 양쪽 배곧은근은 낮은 높이의 의자 좌면에서 정상 높이와 높은 높이의 좌면에 비해 근활성도가 유의하게 증가하였다. 본 연구결과를 통해 앉은 자세에서 의자 좌면의 높이는 배곧은근의 근 활성도에 영향을 줄 수 있으며 배곧은근의 근활성도 증가는 요통과 같은 근골격계 통증을 일으킬 수 있으므로 근골격계 통증을 예방하기 위해 바르게 앉은 자세와 함께 의자 좌면 높이는 중요하다.

• 한국자동차공학회논문집
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• 제14권5호
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• pp.155-163
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• 2006

Car seat is one the most important element to make comfortable drivability. It can absorb the impact or vibration during driving state. In addition to those factors, it is needed to have enough strength for passenger safety. From energy efficiency and environmental point of view lighter passenger car seat frame becomes hot issue in the auto industry. In this paper, weight optimization methodology is investigated for commercial car seat frame using CAE. Optimized designs for seat frame are developed using commercially available finite element code(ANSYS) and design of experiment method. At first, car seat frame is modelled using 3-D computer aided design tool(CATIA) and simplified for finite element modelling. Finite element analysis is carried out for the case of FMVSS 202 Head Restraint test to check the strength of the original seat frame. Two base brackets are selected as optimized elements that are the heaviest parts in the seat frame. After finite element analysis for the brackets with similar load condition to the previous test optimization technique is applied for 10% to 50% weight reduction. Design of experiment is utilized to obtain optimization design for the bracket based on the modified 50% weight reduction model in which outer shape of the bracket is conserved. Weight optimization models result in the decrease of the strength in spite of weight reduction. The more design points should be considered to get better optimized model. The more advanced optimization technique may be utilized for more parts of the seat frame to increase whole seat frame characteristics in the future.

• 동서간호학연구지
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• 제27권2호
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• pp.177-184
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• 2021

Purpose: Traffic accidents are the major cause of death in children. Car seat usage in children is important to reduce the risk of death or injury caused by traffic accidents. This study aims to analyze the trends of car seat use among children ages under 6. Methods: This study adopted a cross-sectional study utilizing the Korea National Health and Nutrition Examination Survey from 2015 to 2019. In total, 1,999 responses were included for the analysis. Factors associated with car seat use were age, sex, body weight, height, family type, household income, and monthly household income. Regression analysis was used to compare the car seat use before and after the revision of the Road Traffic Act (2015~2018 vs. 2019). Results: We found that car seat use was increasing by year, age, region, and household income. Car seat use was higher after fines increased in 2019. Age and body weight had negative association with car seat use, while height and household income had positive association with car seat use. Conclusion: Car seat use increased from 2015 to 2019 and is associated with different ages among children and household income. Further education and promotion that describes the safety benefits to children from car seat use are needed.

• 한국IT서비스학회지
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• 제22권6호
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• pp.87-102
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• 2023

Existing child car seats do not have a monitoring means for the driver or guardian to effectively recognize the status of whether the seat belt of car seat is fastened and whether the ISOFIX of the car seat is fastened to the inside device of the vehicle. In this paper, we propose a smart car seat system which can monitor in real time, whether the seat belt of a child seated in the car seat is fastened and whether the ISOFIX of the car seat is fastened. The proposed system has been developed with a prototype, in which a Hall sensor, magnet, Bluetooth, and display device are used to detect whether these are fastened and to display the detection results. The prototype system provides the detection results as texts and alarm signal to the display for driver or guardian' smartphone in the car in motion. With functional tests of the prototype system, it was confirmed that the detection functions are properly operated, and the detection results were transmitted to the display device and smartphone via Bluetooth within 0.5 seconds. It is expected that the development system can effectively prevent safety accidents of child car seats.

• 대한인간공학회지
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• 제12권2호
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• pp.15-28
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• 1993

Proper ergonomic design of a passenger seat for the highspeed train is one of the essential design components that is directly related to passenger comfort. This study investigated a systematic approach to the ergonomic passenger seat design and evaluation for the Korean highspeed train. To design an ergonomic passenger seat that improves passenger confort, Korean anthropometric data, pas- senger activities in the coach, body postures, body contours and seat dimensions were considered. By analyzing the interredlationship of such factors, resultant seat dimensions were suggested. To properly ecaluate the suggested dimensions, four prototypes were subsequently made and iteratively tested in the laboratory. It is expected that this approach is readily applicable to the passenger seat design of other transport vehicles as well as a train.

• 한국기계가공학회지
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• 제10권4호
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• pp.50-56
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• 2011

Injection molding process is one of the popular manufacturing methods to produce plastic parts with high efficiency and low cost. Ball seat for automobile suspension is made by an injection molding process as a part to support pivot function of ball joint consisted of ball stud and housing. It is necessary for a ball seat to have a dimensional stability in the three dimensional inner area to be contacted with ball stud. In this paper, the dimensional stability of inner surface is indirectly analyzed by checking the difference of inner diameter around the circumferential direction and the thickness variation at the top part of ball seat. Measurement was performed by using the coordinate measuring machine and the fixture to hold ball seat. Optimization of injection molding processes such as injection time, cooling time and temperatures of cylinder barrel was derived to reduce the difference of inner diameter and the thickness variation at the top part of ball seat based on the Taguchi method.