• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.98.2-98.2
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• 2011

For optimal performance of a proton exchange membrane fuel cell (PEMFC), the membrane electrode assembly (MEA) requires hydration, and the membrane's conductivity depends on water content. A humidifier is required to ensure that the reactant gas, usually hydrogen and air, is hydrated before entering the fuel cell. Dry membrane operation or improper hydration causes performance degradation. Typically, the humidification of a fuel cell is carried out by means of an internal or external humidifier. A membrane humidifier is applied to the external humidification of transportation or residential power generation fuel cell due to its convenience and high performance. In this study, The experiments were constructed with a plate-type membrane humidifier in terms of geometric parameters and operating parameters. The results show that the temperature and pressure, the channel length, the membrane thickness and gas flow rate are critical parameters affecting the performance of the humidifier.

• International Journal of Aeronautical and Space Sciences
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• v.15 no.1
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• pp.44-53
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• 2014

A lightning strike to the aircraft seriously affects the aircraft and its components in various ways. As one of the most critical threats to the flight safety of an aircraft, fuel vapour ignition by lightning can occur through various means, notably through hot spot formation on the fuel tank skins. In this study, a coupled thermal-electrical approach using the commercial software ABAQUS is used to study the effects of a lightning strike on aircraft fuel tanks. This approach assumes that the electrical conductivity of a material depends on temperature, and that a temperature rise in a material due to Joule heat generation depends on electrical current. The inter-dependence of thermal and electrical properties-the thermal-electrical coupling-is analyzed by a coupled thermal-electrical analysis module. The analysis elucidates the effects of different material properties and thicknesses of tank skins and identifies the worst case of lightning zones.

• Journal of Sensor Science and Technology
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• v.28 no.6
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• pp.414-419
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• 2019

An ultrasonic based magnetostrictive position sensor (MPS) provides an indication of real target position. It determines the real target position by multiplying the propagation speed of ultrasonic wave and the time-of-flight between the receiving signals; one is the initial signal by an excitation current and the other is the reflection signal by the ultrasonic wave. The propagation speed of the ultrasonic wave depends on the temperature of the waveguide. Hence, the change of the propagation speed in various environments is a critical factor in terms of the positioning accuracy in the MPS. This means that the influence of the changes in the waveguide temperature needs to be compensated. In this paper, we presents a novel way to improve the positioning accuracy of MPSs using temperature compensation for waveguide. The proposed method used the inherent measurement blind area for the structure of the MPS, which can simultaneously measure the position of the moving target and the temperature of the waveguide without any additional devices. The average positional error was approximately -23.9 mm and -1.9 mm before and after compensation, respectively. It was confirmed that the positioning accuracy was improved by approximately 93%.

• Journal of Powder Materials
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• v.15 no.3
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• pp.196-203
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• 2008

The densification behavior of Al-20Si-5.5Fe-1.2Mg-0.5Mn powders was investigated through micro-structure analysis of sintered specimens. The specimens sintered in vacuum or in high purity (99.999%) nitrogen showed porous near-surface microstructures. The densification of near-surface part was enhanced by means of ultra-high purity (99.9999%) nitrogen atmosphere. The relationship between slow densification and oxide surfaces of Al alloy powders was discussed. And the effects of Mg addition, nitrogen gas, and humidity on densification were discussed. In addition, the rapid growth of primary Si crystals above the critical temperature was reported.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.10
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• pp.92-98
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• 2006

An 1 lbf of NASA standard monopropellant thruster, MRE-1, is used for KOMPSAT (Korea Multi-Purpose Satellite) which is launched in 2006 and provides reliable and cost-effective means for attitude and maneuvering control system. The monopropellant thruster obtains required thrust by thermal decomposition process of propellant through catalyst bed. During firing, the decomposition plays a role of a heat source that may occur an excessive radiation heat transfer to peripheral structures and electronics in relatively low temperature condition.Therefore, the radiation heat shield is needed to prevent the critical radiative heat exchange between thruster and satellite during firing. This paper summarizes an overall development process of radiation heat shield from the design engineering up to the manufacturing.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2000.04a
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• pp.212-217
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• 2000

The purpose of this study was to develop a design process for a functional and sensible brassiere for muddle - aged women. As a methodology, an engineering design process QFD (Quality Function Deployment) was adopted to translate the consumer's needs into product design parameters. the customer needs for the wear comfort of brassieres were extracted from a survey of 100 women aged 30 - 40. To select which items were critical and which could be traded off for other attributed or benefits. the importance ratings for the customer needs were determined. Customer needs were translated into technical language by various physical test methods and wear tests. The customer competitive assessment was generated by wear tests of 10 commercial brassieres under controlled environmental conditions of 28${\pm}$1$^{\circ}C$, 65${\pm}$3% RH. The relationship matrix between the customer needs and the means of delivering the needs was developed. Using the QFD methodology, design elements for developing a brassiere for middle-aged women could be analyzed and organized efficiently.

• Korean Institute of Interior Design Journal
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• v.23 no.5
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• pp.41-50
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• 2014

In relation to spatial expression, the remediation theory of Jay David Bolter & Richard Grusin shows a sufficient possibility of providing extended idea and experience through the space of critical representation. The remediation theory discussed in the scope of new media says about the existence method and the development process of media through immersion into media and awakening, and one attribute of remediation which aims at the extension of another realistic experience and recognition through various media, contains common denominators which display diversity and complexity of installation space, and use the audience as expression elements. Therefore, this study aims to apply the remediation theory in order to interpret space using more diverse and multisensory expression methods. For achieving this purpose, this study found the connection among characteristics of hypermediacy which is an axis of installation and remediation theory, and analyzed diverse cases regarding installation space and characteristics of hypermediacy, depending on external aspects of form and expression and internal aspects of experience and cognition. The method of hypermediation expression in installation space converts the recognition about the basic custom of new experience, space and representation. This means that the logic of remediation could approach space by leading to more extended form and recognition. In conclusion, the characteristics of space and the possibility of extended expression revealed in the relationship between installation space and hypermediacy logic would provide another developmental significance for research on space design.

• Journal of the Korean Society of Safety
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• v.27 no.5
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• pp.203-210
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• 2012

Traffic accident risk of young drivers(less than 25) is reported to have 8 times as high as that of middle aged drivers(between 30 and 49). Despite the rise of traffic accident risk, few have been attempted to take a look into driving characteristics of young drivers. The purpose of this paper is to analyze age-specific risks of young driver by means of database of insurance and vehicle inspection, thereby collecting data such as age, vehicle mileage, injuries and so on. We conducted Data-Mining(CART) and Portfolio analysis according to age groups(every 10 years). The conclusions which can be drawn from this empirical study are as follows: (1) Despite the fact that young drivers have low vehicle mileage, the rate of fatality is relatively high. (2) Being concerned of vehicle mileage, 24,000km of driving experience is thought to be critical in differing in fatality rate. Having annual average mileage fewer than 24,169 km, accident frequency is relatively lower than that exceeding 24,169 km(1,571 cases). Backed upon these, some recommendations about driver's license system for young driver to improve are given.

• Korean Management Science Review
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• v.19 no.2
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• pp.1-23
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• 2002

It has been considered as a means for sustaining a competitive advantage for companies to build and maintain long-term relationships with customers. It is without any doubt that many companies have tried to initiate Customer Relationship Management (CRM). For the effective management of customer relationships, it is critical that they acquire. share and use customer information and knowledge. In this paper, we deduced 9 important factors affecting the qualify of customer information and knowledge from the literature reviews on CRM, and developed the questionnaire to measure these factors. The factors are again categorized into organizational system, employees and IT. We analyzed data collected from 30 companies in service industries such as the finance. distribution and communication industries. The result of data analysis demonstrates that the employees' analytical shills and appraisal and reward systems are closely related to the quality of customer information, and analytical skills and IT support for communications with customers are associated with the quality of customer knowledge. implications of findings and future research directions are discussed.

• The Journal of Industrial Distribution & Business
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• v.11 no.10
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• pp.39-48
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• 2020

Purpose: Management of water is a crucial issue globally and is becoming more critical due to climate change. The purpose of this study is to explore water resource management by considering price and water usage based on river basins and to suggest more efficient residential water demand management in South Korea. Research Design, data, and methodology: This study applied data of water usage and water price of 15 regions in four major river basins by considering up and downstream locations from 1997 to 2017 collected by Ministry of Environment in Korea. This study applied regression analyses, ANOVA, and 2-Way ANOVA to verify its claims. Results: The results found that effects of price on water usage showed significant in many cities. The results also showed that means of water usages differ based on location (upstream and downstream) and river basins. Conclusion: The findings provide important policy and management implications for the improvement of water resource management in terms of demand. The results also indicate that water price should be reconsidered by comparing water price levels with those of OECD countries. Furthermore, the results imply that water management in Korea needs to improve in terms of supply to cope with climate change.