• Transactions of the Korean hydrogen and new energy society
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• v.22 no.2
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• pp.184-190
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• 2011

The membrane properties (membrane resistance and ion exchange capacity) of the five types of commercial anion exchange membrane, i.e. IOMAC, AHT, APS, AHA, AFN, were evaluated for the application in the alkaline electrolysis. The membrane resistance decreased in the order; in 1M KOH: AHT>IOMAC>AHA>AFN>APS; in 1M NaOH: AHT>IOMAC>AHA>APS>AFN. The ion exchange capacity decreased in the order: AFN>APS>AHT>AHA>IOMAC. The membrane life was determined from the change of membrane resistance in 1M KOH and NaOH with an increase of soaking time in 20 wt% KOH and 30 wt% NaOH solution. AHA membrane had a good membrane life in 20 wt% NaOH with its unchanged membrane resistance. And, AFN and AHA membrane had a good membrane life in 30 wt% NaOH with its unchanged membrane resistance.

• Transactions of the Korean hydrogen and new energy society
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• v.20 no.4
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• pp.323-330
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• 2009

Efficiency of a fuel cell is determined by the generated water. If water is not removed sufficiently, water will be accumulated at GDL, which causes flooding. Therefore, water control is regarded as a crucial factor to sustain fuel ell performance. In this study, PTFE coating on the surface of carbon paper was carried out to establish optimum process for hydrophobic treatment of GDL. Carbon paper was immersed at different concentrations of nano-sized PTFE coating solution. Their characteristics were analyzed systematically by FE-SEM, water contact angle, cyclic voltamogam, XRD and FT-IR. The quantitative correlation between the amount of coated-PTFE on a carbon paper and concentration of coating solution was carefully investigated. It is suggested that the amount of PTFE-coating on a carbon paper can be managed by means of controling concentration of coating solution.

• Journal of Korean Association for Spatial Structures
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• v.15 no.3
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• pp.51-60
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• 2015

Recently, the concept of damped outrigger system has been proposed for tall buildings. But, structural characteristics and design method of this system were not sufficiently investigated to date. In this study, the dynamic response control performance of outrigger damper has been analyzed. To this end, a simplified analysis model with outrigger damper system has been developed. An artificial wind of 1000 seconds with 0.1 second time steps was generated by using a Kaimal spectrum. Analysis results show that outrigger damper system is more effective up to 20-23% in the control of dynamic response compared to conventional outrigger system. The increase of outrigger damper capacity usually results in the improved control performance. However, it is necessary to select that proper stiffness and damping values of the outrigger damper system because, the outrigger damper having large capacity is result in heavy financial burden.

• Journal of Korean Association for Spatial Structures
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• v.16 no.1
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• pp.95-104
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• 2016

Recently, the concept of damped outrigger system has been proposed for tall buildings. But, structural characteristics and design method of this system were not sufficiently investigated to date. In this study, the dynamic response control performance of outrigger damper has been analyzed. To this end, a simplified analysis model with outrigger damper system has been developed. Use the El Centro seismic(1940, NS) analysis was performed. Analysis results, on the top floor displacement response to the earthquake response, did not have a big effect. However, acceleration response control effect was found to be excellent. The increase of outrigger damper capacity usually results in the improved control performance. However, it is necessary to select that proper stiffness and damping values of the outrigger damper system because, the outrigger damper having large capacity is result in heavy financial burden.

• Transactions of the Korean hydrogen and new energy society
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• v.27 no.4
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• pp.365-371
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• 2016

Cell performance of the Zn-Br redox flow battery (ZBRFB) using two different type's membrane (Nafion117 and SF-600) was evaluated at $20mA/cm^2$ of current density in 1M (mol/L) $ZnBr_2$ + 2M KCl + 0.3M EMPBr(1-ethyl-1-methyl pyrrolidinium bromide) electrolyte. The average energy efficiencies of ZBRFB were 74.9% and 74.7% for Nafion117 and SF-600, respectively. The electrolyte added the 1-ethyl-3-methylimidazolium dicyanamide (EMICA) as an additive was tested for the electrolyte in ZBRFB using SF-600 at $30mA/cm^2$ of current density. An average energy efficiency of the ZBRFB was 74.5% and 77.4% for the electrolyte non-added EMICA and added 1wt% of EMICA, respectively. ZBRFB using the electrolyte added EMICA was showed the higher performance than that using the electrolyte non-added EMICA.

• Transactions of the Korean hydrogen and new energy society
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• v.21 no.1
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• pp.35-41
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• 2010

Water management is an important issue of PEM fuel cell operation. Water is the product of the electrochemical reactions inside fuel cell. If liquid water accumulation becomes excessive in a fuel cell, water columns will clog the gas flow channel. This condition is referred to as flooding. A number of researchers have examined the water removal methods in order to improve the performance. In this paper, a new water removal method that investigates the use of vibro-acoutic methods is presented. Piezo-actuators which are devices to generate the flexural wave are attached at the end of a cathode bipolar plate. Flexural wave is used to impart energy to resting droplets and thus cause movement of the droplets in the direction of the traveling wave.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.776-779
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• 2002

A bellows diaphragm design program for mechanical seal was developed in this study. This program was written in AutoLISP on the AutoCAD system with a personal computer. Basic design concept used in this program is composition of a convolution that is tangent to two lines and five circles from given design parameters(initial radius, inner and outer diameter, thickness, pitch, etc.). The effects of altering some design parameters on stress distribution of bellows were estimated using commercial FEM code, NISAII. As a result, the bellows diaphragm for mechanical seal was successfully designed by the program. The FEM result shows that stress is dependent on straight line length and bellows diameter with same span.

• Proceedings of the Korean Society of Computer Information Conference
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• 2014.01a
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• pp.127-130
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• 2014

여행지에서 제공하고 있는 스탬프 투어링 서비스는 여행객들에게 특별한 기념이 되어주고 있지만, 스탬프를 받기 위한 장소를 찾기 어려운 점과 여행지의 주변 정보를 얻기 위해서는 여행자의 별도의 노력이 필요하다는 단점이 있다. 이러한 문제를 해결하기 위해 유명 관광지 및 추천 명소 등에 NFC 태그를 설치하고 간단한 태깅만으로 스탬프를 수집할 수 있는 어플리케이션을 제안한다. 또한 이 어플리케이션에 저장되는 정보와 평가를 이용해 사용자별 맞춤 여행 코스를 제공하고 사용자가 좀 더 편리하고 재미있는 여행을 즐길 수 있도록 돕고자 한다.

• Transactions of the Korean hydrogen and new energy society
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• v.27 no.1
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• pp.71-82
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• 2016

A fuel cell electric vehicle (FCEV) could be an alternative solution to gasoline powered vehicles. The Korean and Japanese governments have played the midwifery role in the development of the FCEV industry. This study explores the difference in policy goals for FCEV between the two countries. Koreans recognized that FCEV was innovative technology and put forward the notion of technology pre-occupancy. Whereas, the Japanese government discovered that FCEV was one way to apply hydrogen mechanisms, so they identified the supply of hydrogen as one of the industries of interest, and have played the demiurge role. This study suggests that the role of government is to introduce eco-friendly vehicles, using the cases of Korean and Japanese governments, who introduced FCEV to the world first.

• Transactions of the Korean hydrogen and new energy society
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• v.21 no.2
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• pp.98-103
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• 2010

In order to develop two-stroke free-piston hydrogen engine to obtain high thermal efficiency and low emission, backfire occurrence have to be prevented. In this research, backfire characteristics are analyzed as functions of the intake valve opening timing and compression chamber pressure under piston by using RICEM (Rapid Intake Compression Expansion Machine) that has reverse uni-flow scavenging. As the result, reverse uni-flow scavenging is advantage about back fire. but, it exists suitable intake valve opening timing and its timing become known that equivalence ratio 1 retard until the piston rises. Also, To rise chamber pressure of lower piston, this does not cause backfire occurs in equivalent ratio 0.6 observed back fire. Therefore, 2cycle hydrogen fueled free-piston engine is undesirable scavenging compression by compressing the piston.