• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1278-1282
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• 2005

Air mattress is now used widely to prevent the pressure ulcer by reducing the localized pressure peaks. In this paper an air-cell mattress and its pressure control method based on an approximate anthropometric model are presented. The air-cell mattress has eighteen cylindrical air cells made of porous material allowing air leakage to contribute in reducing the development of pressure ulcer by lowering the pressure peak, temperature and humidity. To determine an optimal air-cell pressure appropriate for each user, we divide the parts of the body into four sections such as head, trunk, hip, and leg. Then, the pressure of each section is independently calculated from the weight of each part based on the individual body height and weight and the approximate anthropometric model. Air supply system for the air-cell mattress is implemented by using four electronic solenoid valves and an air compressor, and it is driven by a real-time micro-controller. The experimental results with seven subjects shows that the proposed air-cell mattress is effective for the prevention of the pressure ulcer.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.3
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• pp.159-169
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• 2004

In this study, integration control of air-cell seat and semi-active suspension is proposed to minimize the road-tyre force which can cause uncomfortable feeling to rider. The proposed integration control with sliding perturbation observer is consisted of air-cell seat control which uses the force generated by air-cell and the sky-hook control. The air-cell seat itself has been modeled as a 1 degree of freedom spring-damper system. The actual characteristics of the air-cell have been analyzed through experiments. In this paper, we introduces a new robust motion control algorithm using partial state feedback for a nonlinear system with modelling uncertainties and external disturbances. The major contribution of this work is the development and design of robust observer for the state and the perturbation. The combination skyhook controller and air-cell controller using the observer improves control performance, because of the robust routine called Sliding Observer Design for Integration Control of Air-Cell Seat and Semi-active Suspension. The simulation results show a high accuracy and a good performance.

• Journal of Institute of Control, Robotics and Systems
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• v.11 no.7
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• pp.578-586
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• 2005

Air mattress is now used widely to prevent the pressure ulcer by reducing the localized pressure peaks. The pressure control method based on the anthrophometric model of an air-cell mattress developed in this study is presented. The air-cell mattress has 18 cylindrical air cells made of porous material allowing air leakage. Even though the air leakage can contribute to reducing the development of pressure ulcer by lowering the pressure peak, temperature and humidity, the air pressure changes with time and the desired air-cell pressure has to be determined as an optimal value for each user. To select the desired air-cell pressure, we first divide the parts of the body into four sections such as head, trunk, hip, and leg. Then, the pressure of each section grouped with air-cells is calculated from the weight of each part estimated from the individual height and body weight. Air supply system for the air-cell mattress is implemented by using four electronic solenoid valves and an air compressor, and it is driven by a real-time microcontroller. We experimented with five subjects of the contact pressure on skin. The experimental results show that the proposed air-cell mattress is effective for the prevention of the pressure ulcer.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2834-2838
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• 2008

An free breathing proton exchange membrane fuel cell (PEMFC) was developed. This paper presents a study of the several effect on the performance of a fuel cell such as air flow rate, opening ratio, and cathode structures. Especially, an air flow rate is critical condition to improve the fuel cell performance. In this paper, we developed a synthetic jet micro air blower to supply high stoichiometric air. The synthetic jet actuation is usually generated by a traditional PZT-driven actuator, which consists of a small cylindrical cavity, orifices and PZT diaphragms. In comparison with free convection fuel cells, the forced-convection fuel cell which equipped synthetic jet micro air blower brings higher performance and stability for long term test. Also, power consumption of the synthetic jet micro air blower is under 0.3W. The results show that the maximum power density was $188mW/cm^2$ at $400mA/cm^2$. The maximum power density was higher 40% than power density of free convection fuel cell.

• Journal of the Korean Society of Clothing and Textiles
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• v.39 no.1
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• pp.55-62
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• 2015

This study investigated the thermal insulation of an air-cell pack embedded jacket and down jackets to understand the potential of air-cell pack as a filler for winter outdoor wear. A thermal manikin measured the thermal insulation of the following jackets: HD (heavy down jacket, total weight (Tw) 750g, goose down weight (Dw) 350g), LD (light down jacket, Tw 560g, Dw 140g), AF (air-cell pack embedded jacket, Tw 490g, trunk goose down in LD was replaced to air cell), F (film jacket, Tw 469g, but removed the air in the air-cell pack from the AF), and Control (control jacket, Tw 438g, removed the air-cell pack film from the F). Thermal insulations of each experimental condition were measured in a static standing posture. Total thermal insulations (IT) were 1.29clo (HD), 1.23clo (LD), 1.16clo (AF), 1.20clo (F), and 1.08clo (Control). Body regional thermal insulation was higher in the chest and back than in the abdomen and hip in all conditions. The results suggest that an economical and versatile outdoor jacket with superior thermal insulation will be feasible if the air volume is properly controlled in air-cell pack embedded jackets in consideration of regional different distribution and used in combination with film and down.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.561-564
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• 2007

FCEV uses electric energy which generated from the reaction between Hydrogen and Oxygen in fuel cell stack as driving force. As fossil fuels are exhausted, fuel cell is regarded as a potent substitute for next generation energy source, and thus, most of car-makers make every efforts to develop fuel cell electric vehicle (FCEV). In addition, fuel cell is also beneficial in aspect of environment, because only clean water is produced during chemical reaction process instead of harmful exhausted gas. Generally, Hydrogen is supplied from high-pressured fuel tank, and air blower (or compressor) supply Oxygen by pressurizing ambient air. Air blower which is driven by high speed motor consumes about $7{\sim}8$ % of energy generated from fuel cell stack. Therefore, the efficiency of an air blower is directly linked with the performance of FCEV. This study will present the development process of an air blower and its consisting parts respectively.

• 한국태양에너지학회:학술대회논문집
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• 2011.11a
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• pp.270-273
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• 2011

Water management is important in proton exchange membrane fuel cell because the water balance has a significant impact on the overall fuel cell system performance. In fuel cell vehicle, the vehicle's power demand is dynamic; therefore, the dynamic water management system is required. This present study proposes a method to control the humidity of the input air in cathode side of the fuel cell vehicle. The simulation using several driving cycles shows the proposed air humidification control obtains a relatively good result. The liquid saturation level is seen constant at the target level although still there are small deviations at driving cycles which having averagely high power demands.

• Journal of the Korean Society of Food Science and Nutrition
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• v.34 no.10
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• pp.1633-1637
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• 2005

Five different plant cell wall degrading enzymes were tested for their ability to release p -hydroxybenzoic acid from carrot alcohol insoluble residue (AIR) and cellulose fraction. Phenolics of AIR from cell wall materi민 (CWM) in carrot were found to consist primarily of p-hydroxybenzoic acid (1,977 $\mu$g/g AIR) with minor contribution from vanillin (55.9 $\mu$g/g AIR), ferulic acid (13.6 $\mu$g/g AIR) and p-hydroxybenzaldehyde (10.6 $\mu$g/g AIR). The contents of ferulic acid in Driselase, Cellulase, Macerozyme R-200, Macerozyme R-10 and Sumyzyme MC were 2,319, 2,060, 391, 95.2, 34.1 $\mu$g/g, respectively. Incubation of Driselase with AIR released only 2.8$\%$ of the total 4 M NaOH extractable p-hydroxybenzoic acid. These results indicate that commercial five plant cell wall dograding enzymes can not release P-hydroxybenzoic acid from carrot AIR and cellulose fraction.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.5
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• pp.118-126
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• 2007

A finite element simulation model was developed for the performance optimization of a closed type air-cell mattress used for the ulcer prevention. An H-model with material properties of human flesh and kinematic joints were used for the calculation of the body contact pressure. The material property of rubber air-cell was evaluated by tensile test of standard specimen. We evaluated the body contact pressure distribution after laying human model on the inflated air-cell mattress. It was found that the body contact pressure was dependent on cell height. but hardly affected by the thickness of the rubber in a cell.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.11
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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.