• International Journal of Precision Engineering and Manufacturing
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• v.9 no.1
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• pp.39-46
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• 2008

The end plates of fuel cell assemblies are used to fasten the inner stacks, reduce the contact pressure, and provide a seal between Membrane-Electrode Assemblies (MEAs). They therefore require sufficient mechanical strength to withstand the tightening pressure, light weight to obtain high energy densities, and stable chemical/electrochemical properties, as well as provide electrical insulation. The design criteria for end plates can be divided into three parts: the material, connecting method, and shape. In the past, end plates were made from metals such as aluminum, titanium, and stainless steel alloys, but due to corrosion problems, thermal losses, and their excessive weight, alternative materials such as plastics have been considered. Composite materials consisting of combinations of two or more materials have also been proposed for end plates to enhance their mechanical strength. Tie-rods have been traditionally used to connect end plates, but since the number of connecting parts has increased, resulting in assembly difficulties, new types of connectors have been contemplated. Ideas such as adding reinforcement or flat plates, or using bands or boxes to replace tie-rods have been proposed. Typical end plates are rectangular or cylindrical solid plates. To minimize the weight and provide a uniform pressure distribution, new concepts such as ribbed-, bomb-, or bow-shaped plates have been considered. Even though end plates were not an issue in fuel cell system designs in the past, they now provide a great challenge for designers. Changes in the materials, connecting methods, and shapes of an end plate allow us to achieve lighter, stronger end plates, resulting in more efficient fuel cell systems.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.535-541
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• 2004

For housing estate of a new administrative capital city, Noise reduction method is a important design factor. As measuring a noise level of traffic noise according to separation from road, it can be created a quite housing estate. Analyzing of merits and demerits in sound barrier walls and tunnels can be proposed environment friendly soundproofing facilities. Number of measurement was performed to know what kind of layout of housing estate is good for noise reduction. Through this measurement, ㄷ shaped layout or parallel layout has the advantage of sound insulation rather than right angled layout. In this case (ㄷ shaped layout or parallel layout) buildings neighboring to the road should be designed to insulate sound. Evergreen trees should be planted between housing estate and road more than 30m (at least 7～8m) in order to reduce noise and have masking effects. If broad-leaved trees are planted more than 30m, approximately 10dB noise is reduced and 2～4dB if 7～8m. Roads in the estate should be designed considering pedestrians first, and special roads for moving and ambulance should be designed as skew road, if possible. The result shows that 15$^{\circ}$-sloped‘S’road reduces 1～2dB noise and 30$^{\circ}$-sloped road reduces 4～7dB. If noise barrier is inevitably installed, it should be designed to go well wit neighboring environment so as to install Environment Friendly Noise Barrier using materials and trees including wood and soil. Through this study the results are used to guideline for construction of environment friendly housing estate

• Journal of Information Technology Applications and Management
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• v.26 no.6
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• pp.103-117
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• 2019

Demand for high power motors is rapidly increasing as the 4th industry and convergence technology has recently emerged. In order to produce high-strength permanent magnets, the magnets used for magnetization have been increased from DC 300V in the 1970s to DC 2.5kV in the 2010s, Up to DC 10kV in the 2030s, It is expected that higher voltage will be used to magnetize. However, in the case of a magnetizer using an existing electric signal control device, it is necessary to use a control device with a high-voltage insulation function in case a high voltage used for magnetization is leaked to the control device. If a short circuit accident occurs, the controller must be shut down and serious problems such as excessive repair costs arise. In this study, a control system adopting optical communication method instead of electric signal control method is proposed to prevent leakage currents in high-voltage magnetizer. We design a transmitter(Tx) and a receiver(Rx) device for the optical communication control device and implemented a prototype connecting the optical cable. In order to demonstrate the utility of high-voltage magnetizer using the optical communication control device, we analyzed the initial cost and the yearly cost for the years to analyze the net present value. As a result, In the case of the low-voltage magnetizer, the electric signal control method cost less, As the operating voltage of the magnetizer becomes higher. It is confirmed that it takes less cost when the optical communication control device is used.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.44 no.1
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• pp.12-18
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• 2007

As an arc fault interrupter, the AFCI mentioned in this paper has been designed to detect and interrupt arc faults due to wire deterioration, insulation, wire damage, loose connection, and excessive mechanical damage. Since AFCI is digital and uses mechanical and electric stress, the length of interruption against overload and over-current is much shorter than the current bi-metal method. Therefore, the risk of electrical fires has been reduced.

• Geotechnical Engineering
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• v.12 no.2
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• pp.59-70
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• 1996

The EPS has the unit weight of only 20~30kg/m3 and is used as one of the methods of reducing road embankment loads. Parts of it's applications are for backfill materials of structures like abutment, retaining wall, etc., to reduce horizontal earth pressure and for banking materials to secure the safety of settlement and bearing capacity by minimizing the stress Increment. However, the Korean Standards (KS) has not yet proposed any testing method for use of EPS as a engineering banking material. Only its testing and quality ordinance as a heat insulation material has been standardized. Therefore, in Korea, EPS is used as banking material without any systematic testing data as a civil engineering material. In this point of view, this paper deals with the engineering characteristics of EPS through many laboratory tests on strength, strain, absorption, and creep. from the results achived through tests, this paper proposes the enactment of a suitable quality testing ordinance and the criteria of unconfined design strength of EPS for use as engineering material.

• Journal of the Korean Institute of Gas
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• v.18 no.2
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• pp.69-72
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• 2014

If LNG is leaked from 9% Ni steel inner tank by damage, LNG is retained by outer concrete tank. Then large tensile stress can be caused at cylindrical bottom of outer tank by temperature difference between outer and inner surface of outer tank. Therefore, in order to reduce the tensile stress is caused by temperature difference, corner-protection is installed with insulation and 9% Ni steel as a second barrier. In this paper, using finite element method, structural analysis was performed for rectangular and circular shape of knuckle and based on the results, fatigue life of welds of corner protection was predicted. As a consequence of structural analysis, safety factor of circular knuckle shows 33% bigger than rectangular one shows, and circular knuckle has 25% bigger fatigue life time than rectangle has. These results can be applied to life time assessment and design optimization in the future.

• Fashion & Textile Research Journal
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• v.4 no.3
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• pp.248-253
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• 2002

The purpose of this study was to improve consumer sleeping life in quality and to suggest producers meet new consumer needs and demands, by examining the nationwide use of bedding, analyzing consumer sleeping life by category and age group, comparing the results with the findings of the nationwide studies by Sung Su-kwang (1992) and Lee Song ja (1995), and identifying the major trend of consumer sleeping life. Results and Discussion The findings of this study were as below: 1. The General Characteristics of the Subjects : Most of the housewives investigated were in their 30s and 40s, with 41.7% and 50.8% respectively. 2. Bedroom : When it comes to bedroom style, 47.8% put beds in their rooms with the Korean under-floor heating system, and 45.4% didn't place beds in their rooms with the same heating system. 3. The Purchase of Bedding : 49.0%, approximately half the homemakers, bought their current bed-clothes at bedding shops, and just 3.2% made them on their own at home. 4. The Use of Bedclothes : In summer, yam (flax, ramie fabric) and a single-layer bed sheet (41.9%) were in use most, followed by a single-layer quilt (34.5%). 5. Bedding Management The most common frequency of bedding disinfection by sunning was once a month (29.4%), followed by once per two weeks (23.9%) and once a week (19.0%) in the order named.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.529-532
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• 2003

Quench behavior of resistive superconducting fault current limiters (SFCLs) with various pattern shapes was investigated. The pattern shapes employed were meander, bi-spiral, and spiral shapes of identical line width, gap and margin. SFCLs were fabricated from YBCO thin films grown on two-inch diameter $Al_2O_3$ substrates under the same conditions. Resistance rise of current limiting elements was low at a spiral shape before the whole quench completion, which may act as a disadvantage for simultaneous quench in serial connection between current limiting elements, but the temperature tended to have similar values at higher voltages. On the other hand, bi-spiral shape was severe at insulation level between current limiting lines. When these aspects were considered, we concluded that a meander shape was appropriate to design for a resistive SFCL based on thin films except the concentration of electric field at edge areas of strip lines.

• Fashion & Textile Research Journal
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• v.18 no.2
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• pp.184-193
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• 2016

This study investigates the recognition and preference of functional textile material about outdoor clothing widely used in the current fashion market. The study targeted 216 males and females in their 20s to 50s who wear outdoor clothing as casual wear. To analyze data, frequency analysis, cross tabulation analysis and ANOVA were conducted with the SPSS 21.0 statistical package. The results are as follows. First, recognition of functional textile material of outdoor clothing showed that 20s was the lowest preference and all age groups preferred lightweight textile material. In information recognition of functional outdoor clothing, 40s showed the highest recognition, while 20s showed the lowest recognition. Second, 40s and 50s preferred functional material to 20s and 30s. In particular, 40s and 50s preferred clothing items with water vapor permeability & water repellent material to 20s and 30s. All age groups preferred insulation material jumpers, water vapor permeability & water repellent material jumpers and stretch pants. Third, reasons for purchasing functional material clothing was: design for the age group 20s and 30s versus health and function for the age group 40s and 50s. It is necessary to develop functional clothing products based on exact consumer information and preferences.

• Journal of Energy Engineering
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• v.28 no.4
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• pp.103-110
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• 2019

The domestic innovative power reactor named iPOWER will employ the passive molten corium cooling system(PMCCS) to cool down and stabilize the core melt in the severe accident. The final design concept of the PMCCS is yet to be determined, but the in-vessel retention through external reactor vessel cooling has been also considered as a viable strategy to cope with the severe accident. In this study, the two-phase natural circulation flow established between the reactor vessel and the insulation was simulated using a thermal-hydraulic system code, MARS-KS. The flow path of cooling water was modeled with one-dimensional nodes, and the boundary condition of the heat load from the molten core was defined to estimate the naturally-driven flow rate. The evolution of major thermal-hydraulic parameters were also evaluated, including the temperature and the level of cooling water, the void fraction around the lower head of the reactor vessel, and the heat transfer mode on its external surface.