• 한국산학기술학회논문지
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• 제15권6호
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• pp.3435-3441
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• 2014

차량의 시트 재질로 사용되는 폴리우레탄 폼의 모델링 및 동특성 예측은 승객의 승차감 향상을 위해 매우 중요하다. 본 연구에서는 폴리우레탄 폼의 정특성 시험을 통해 비선형 강성과 점탄성 특성의 시간변수 파라미터를 구하였다. 다항식과 컨벌루션 적분법을 이용하여 폴리우레탄 폼의 비선형 특성과 점탄성 특성을 수학적으로 모델링하였다. 이와 같은 비선형 진동 모델에 대하여 수치적분 방법을 이용하여 시트 바닥 변위에 대한 진동 응답을 계산하였다. 폴리우레탄 폼의 비선형 특성과 점탄성 특성이 진동계에서 미치는 영향을 단순 1자유도계와 인체모델을 이용하여 분석하였다. 결과적으로 폴리우레탄 폼의 점탄성 특성이 승차감을 위한 설계파라미터로 고려되어야 하는 것으로 나타났다.

• 소음진동
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• 제10권5호
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• pp.811-818
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• 2000

This paper deals with the design of a car seat for enhancing dynamic ride quality using a Biomechanical Model that was developed from the measured whole-body vibration characteristic. For evaluation of seat ride quality, the z-axis acceleration of floor as an input of biomechanical model was measured on a driving passenger car at highway and national road. Form the floor signal and the estimated biomechanical model, overall ride value evaluated by parameter study of seat stiffness and damping. The result shows that overall ride value decreases as the seat damping increases and the sear stiffness decreases. A lot of polyurethane foams were manufactured and tried to evaluate dynamic ride quality of a seat. It is found that stiffness and damping of a seat show a linear relationship, which means the stiffness and damping are not independent each other, So the optimal seat parameters within practically achievable space are determined.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 춘계학술대회논문집
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• pp.138-145
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• 2005

• 재활복지공학회논문지
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• 제8권3호
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• pp.205-211
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• 2014

본 연구는 휠체어 좌석의 재질 중 하나로 국내에서 주로 사용되는 폴리우레탄 폼의 경도에 따른 압력 분석을 통하여 압력 분산이 적절하게 이루어지는 재질을 제시하는 것에 목적이 있다. 이러한 연구의 목적을 달성하기 위해 폴리우레탄 폼의 경도 $13kg/cm^2$, $18kg/cm^2$, $25kg/cm^2$, $45kg/cm^2$로 구성된 전방웨지 6cm 시트를 총 4개를 설계 및 제작하였다. 실험에는 비장애인 10명이 참여하였으며, 측정도구로는 XSENSOR를 사용하였고 휠체어 시뮬레이션에 시트를 올려 실험하였다. 각 시트마다 착석압력 측정은 5분간 실시하였으며 획득한 데이터 중 평균압력, 최대압력, 접촉면적 분석을 통해 경도에 따른 영향을 살펴보았다. 이에 본 실험을 통해 얻은 결과는 다음과 같다. 폴리우레탄 재질의 경도에 따라 평균압력, 최대압력 및 접촉면적은 경도 $45kg/cm^2$에서 높게 나타났고, 13, $18kg/cm^2$에서 낮게 나타났다(p< .05). 이러한 결과를 통해 폴리우레탄 재질의 경도는 착석 시 압력변화에 영향이 있음을 알 수 있었으며, 향후 자세유지기구의 시트 재질로 폴리우레탄 폼을 사용한다면 경도 $18kg/cm^2$가 체압을 분산하기에 적절한 재질로 파악되었다.

• Elastomers and Composites
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• 제50권2호
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• pp.81-86
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• 2015

In this study, natural rubber latex foam was prepared in order to replace commercialized polyurethane foams as a car seat material. Physical properties of the latex foam were investigated and the light stability was improved. The latex foam was mixed in an aqueous solution state, and the degree of foaming and the accelerator ratios were appropriately controlled. Tensile properties, hysteresis and dynamic mechanical properties of the latex foam were measured to compare with those of polyurethane foams. UV light absorbers and radical scavengers were added for improving light stability of the latex foam. Xenon lamp test was conducted to investigate the effects of the reagents on light stability. Our results revealed that the prepared latex foam including a light absorber with an antioxidant showed excellent light stable performances.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 추계학술대회 논문집
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• pp.994-995
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• 2014

Supporting stiffness of seats is an important component affecting dynamic characteristics cognized by a passenger. To analyze dynamic characteristic of a seat for vehicles operating on various road conditions, the seat vibration from road irregularity should be understood and compared. In this study, the seat is analyzed as distributed supporting system. The dynamic stiffness is measured using masses. The characteristic of the seats is analyzed by measuring distributed dynamic stiffness. The distributed dynamic stiffness of the seat is estimated on various locations and the effects of each component such as spatial distribution, compression level and vibration amplitude are analyzed. The influence of seat cover, elastic support and flexible polyurethane foam on the measured stiffness was analyzed.

• 환경정보
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• 제18권3호
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• pp.60-66
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• 1996

• Elastomers and Composites
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• 제58권1호
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• pp.32-43
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• 2023

The worldwide use of polyurethane foam products generates large amounts of waste, which in turn has detrimental effects on the surroundings. Hence, finding an economical and environmentally friendly way to dispose of or recycle foam waste is an utmost priority for researchers to overcome this problem. In that sense, the glycolysis of waste flexible polyurethane foam (WFPF) from automotive seat cushions using different industrial-grade glycols and potassium hydroxide as a catalyst to produce recovered polyol was investigated. The effect of different molecular weight polyols, catalyst concentration, and material ratio (PU foam: Glycols) on the reaction conversion and viscosity of the recovered polyols was determined. The obtained recovered polyols are obtained as single or split-phase reaction products. Besides, the foaming characteristics and physical properties such as cell morphology, thermal stability, and compressive stress-strain nature of the regenerated flexible foams based on the recovered polyols were discussed. It was observed that the regenerated flexible foams displayed good seating comfort properties as a function of hardness, sag factor, and hysteresis loss compared to the reference virgin foam. With the growing demand for a sustainable and circular economy, a global valorization of glycolysis products from polyurethane scraps can be realized by transforming them into profitable substances.

• 대한기계학회논문집A
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• 제28권11호
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• pp.1672-1684
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• 2004

In this paper, an active vibration control with the use of an air-cell seat for passenger cars is investigated. The roles of the air-cell inserted between the polyurethane foam of the seat and seat cover are first to extend the seat's capability to adopt various shapes of human body and to improve the ride-comfort against road disturbances. The air-cell seat is modeled as a 1-d.o.f. spring-damper system. Because an exact modeling of the air-cell itself is alomost impossible, its dynamic characteristics are analyzed through experiments. A road-adaptive gain-scheduled sky-hook control for the air-cell seat system is proposed. The skyhook gains are scheduled in such a way that the acceleration level transmitted to human body on various road conditions is minimized. Simulations and experimental results are provided.

• 인간식물환경학회지
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• 제22권2호
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• pp.159-165
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• 2019

The purpose of this study was to examine the effects of repetitive horticultural activities on the dexterity and out of seat behaviors of 5 years old children. Horticultural activities were conducted from March 3 to April 21, 2017, once a week for 20 minutes per session, a total of 8 sessions. The program was divided into first half (Sessions 1-4) and second half (Sessions 5-8) and horticultural activities were repeatedly carried out. In Sessions 1 and 5, kindergarteners transplanted succulent plants into pots, and observed and managed the plants daily. From Session 2 to 4 and from Session 6 to 8, kindergarteners watered and observed the succulent plants planted in Sessions 1 and 5 and they put flowers on a floral foam (10 × 10 × 10 cm). This study conducted the O'Connor Tweezer Dexterity Test in which the number of pins subjects inserted for 30 seconds was counted, and there was a significant difference (p =.000) in the dexterity of the kindergarteners after performing horticultural activities in the result of the repeated measures design ANOVA. The time kindergarteners left their seat for the first time while participating in horticultural activities for 20 minutes was measured using a stopwatch in each session. There was a significant difference (p =.000) in the ANOVA test in changes in their out of seat behavior in Session 8. In addition, there was no significant difference in the dexterity and out of seat behavior of kindergarteners from Session 2 (p =.364, p =.975, respectively) to Session 3 (p =.055, p =.283), but there was a significant difference from Session 4 (p =.042, p =.009) to Session 8 (p =.000, p =.000) as sessions were repeated.