• Proceedings of the KIEE Conference
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• 1991.07a
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• pp.3-12
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• 1991

Fuel cells are electrochemical devices that convert the chemical reaction energy directly into the electrical energy. In a typical fuel cell, gaseous fuel is fed continuously to the anode(negative electrode) compartment and the oxidant(i.e, oxygen from air) is fed continuously to the cathode(positive electrode) compartment; the electrochemical reactions take place at the electrodes to produce an electric current. Many of the operational characteristics of fuel cell systems are superior to those of conventional power generation system because of good efficiency, environmental protection, safty, modularity etc. From those reasons, the fuel cells are considered to be the solution to the future problem of energy conversion. The objective of this paper is to introduce the technical status of fuel cell technologies and our national project for the development of the phosporic acid fuel cell.

• Journal of the Microelectronics and Packaging Society
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• v.22 no.2
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• pp.1-4
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• 2015

Qualification includes all activities to demonstrate that a product meets and exceeds the reliability goals. Manufacturers need to spend time and resources for the qualification processes under the pressure of reducing time to market, as well as offering a competitive price. Failure to qualify a product could result in economic loss such as warranty and recall claims and the manufacturer could lose the reputation in the market. In order to provide valid and reliable qualification results, manufacturers are required to make extra effort based on the operational and environmental characteristics of the product. This paper discusses optimal interval censoring design for reliability prediction of electronic packages under limited time and resources. This design should provide more accurate assessment of package capability and thus deliver better reliability prediction.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.887-887
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• 2004

The areal density of the hard disk drive(HDD) has been increased due to technological advances recently. To achieve the high areal density magnetic recording requires an extremely small gap between the air-bearing surface (ABS) and disk. At the same time, the slider mass and size should be reduced to minimize the physical contact under the operational and environmental conditions. Almost all of 2.5＂HDD companies will get ready for adoption of FEMTO slider and already utilized the small slider. FEMTO and small size slider will be mainstream in the 2.5" and other small form factor HDD in the near future. In this study, the flying characteristic of FEMTO slider was examined. Based on the simulation, FEMTO slider is very stable in flying dynamic under the disk modulation, however the flying height sensitivity of the manufacturing tolerances is much bigger than PICO slider. And the other characteristics like impulse response and load/unload dynamic were also examined in this study.tudy.

• IE interfaces
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• v.11 no.1
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• pp.97-103
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• 1998

In these days many people have studied on the berthing problem. The operation rules differ from port so port and the problem is highly dependent on the environment of port. The purpose of this study is to develop a decision support system decision makers of the berthing problem for Inchon Port. The system is developed with graphic user interface(GUI) using user-interactive approach and some general and specific rules for Inchon Prot are considered. The system is composed of the following four parts ; the input/output part, the automatic berthing part by the system using rules, the manual berthing part by user, and the part for modifying results or handling exceptional events. The system is designed to assign ship to berths by matching the characteristics with environmental and operational constraints of Inchon Port. We expect that this system can provide decision makers with an efficient and fast way to berthing and can reduce wastes of time, space, and manpower in port operations.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.12 no.4
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• pp.21-26
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• 2016

In this study, the control strategies of indoor air temperature in floor radiant heating system were researched by computer simulation. The temperature difference based time control method using the difference of indoor set temperature and indoor temperature is compared with the existing On-Off control one for heating control performances. As a result, the temperature difference based time control method shows better thermal environmental characteristics in case of selected operational conditions in comparison with existing control one.

• Environmental and Resource Economics Review
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• v.10 no.4
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• pp.515-545
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• 2001

This paper introduces the least absolute deviations estimation of the contingent valuation model, which corresponds to the semi-parametric estimation of discrete choice models by Manski (1975, 1985) and Lee (1992). The least absolute deviations estimation is more robust to mis-specified distributional assumptions in the estimation of the contingent valuation model, compared to the maximum likelihood estimation. The full identification and strong consistency of the estimation are proved and its application to different formats of contingent valuation survey data is discussed. Simulation studies are designed to evaluate its operational characteristics including computational strategies, small sample properties and the efficiency gain of a follow-up question. The bias and efficiency of least absolute deviations and maximum likelihood estimation are compared in the presence of heteroskedasticity.

• 한국신재생에너지학회:학술대회논문집
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• 2008.10a
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• pp.47-50
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• 2008

The sub-zero cold is a major environmental consideration for the operational readiness of FCEVs because fuel cells produce water and utilize wet air with varying water content to generate electricity. Typical fuel cells thus have a fatal flaw in freezing conditions at startup. This drawback becomes more serious with the outsourced fuel cell that is entirely water-based for its internal humidification. In this background, the HMC's self-designed fuel cell was developed as an alternative and was employed in the Tucson-based FCEV in 2006 demonstrating its good cold-startup characteristics. The cold-startup capacity of the vehicle was validated through tests in the cold chamber and on the road, resulting in 50% stack power achieved in 250 seconds at $-15^{\circ}C$.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.10
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• pp.1081-1089
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• 2005

In order to examine the application feasibility of Orimulsion fuel in a commercial boiler using heavy fuel oil, a numerical and experimental research efforts have been made especially to figure out the fundamental combustion characteristics of this fuel in a small-scale boiler. One of the notable combustion features of Orimulsion fuel is the delayed appearance of flame location with the flame shape of rather broad distribution, which is found experimentally and confirmed by numerical calculation. This kind of flame characteristics is considered due to the high moisture content included inherently in the process of Orimulsion manufacture together with micro-explosion by the existence of fine water droplets. In order to investigate the effect on the combustion characteristics of Orimulsion, a series of parametric investigation have been made in terms of important design and operational variables such as injected amount of fuel, types of atomization fluid, and phonemenological radiation model employed in the calculation, etc. The delayed feature of peak flame can be alleviated by the adjustment of the flow rate of injected fuel and the generating features of CO, $SO_2$ and NO gases are also evaluated in the boiler. When the steam injection as atomizing fluid is used, the combustion process is stabilized with the reduced region of high flame temperature. In general, the calculation results are physically acceptable and consistent but some refinements of phenomenological models are necessary for the better resolution of pollutant formation. From the results of this small-scale Orimulsion boiler, it is believed that a number of useful information are obtained with the working computer program for the near future application of Orimulsion fuel to a conventional boiler.

• Journal of Korean Society for Atmospheric Environment
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• v.28 no.3
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• pp.316-324
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• 2012

This research shows the improved methodology which can be applied for universities which want to set up their GHG inventories. In other words, we tried to make guideline in problems due to the unique characteristics of universities. This guideline will help university to deal with the problems they are facing: For example university has less enforcement in operational control compared to the business sector. And it also has various usage of facilities, although these facilities are not maintained by same principal agent. The difference between owner and manager is an another reason for difficulty in setting group organization. The improved and adaptable methods responding to these problems were suggested from this research. The results of this research says the new definition of function for various actors in university for quality control and quality assurance. Because the suggestions made in this research which concerns with criteria for building of universities' GHG inventories were all read by current legislation, there is an anticipation that this can be an official guideline that can be applied to the universities right away.

• Journal of Environmental Impact Assessment
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• v.11 no.4
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• pp.289-309
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• 2002

Solutions of many landscape problems depend on area-wide assessment and interpretation of spatial and physical characteristics over the study area. The authors argue that the public awareness for an area-wide urban landscape appears to be very low due to limited chance to the information. Acknowledging these constraints, an operational, user-friendly information system has been developed by combining internet technology with GIS. In particular, integration among satellite data and digital maps takes advantage of each component, and enables the landscape structure to be visualized, interacted with and deployed all on the Web. The 1m resolution IKONOS data realistically identified the major type of landscape by large scale spatial precision while TM data revealed successfully the major parameters that influence an area-wide spatial structure in the study area. This system would play a crucial role in improving the public awareness for area-wide landscape information if it is operationally introduced into the Government since the highly user-friendly interface based on image maps provides a completely new means for disseminating information for area-wide landscape in a visual and interactive manner to the general public.