• 한국수소및신에너지학회논문집
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• 제19권6호
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• pp.467-473
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• 2008

This study is to investigate the influence of catalyst loading quantity on the direct methanol fuel cell (DMFC) performance. In this paper, Pt-Ru and Pt-black loading as the catalyst were varied from 1 to $4mg/cm^2$ at the anode and cathode, respectively. The experiment was conducted with single fuel cell consisted of $5cm^2$ effective electrode area, serpentine type flow pattern and Nafion 117 membrane. Also, AC impedance and methanol crossover current were measured to investigate the performance loss precisely. As a result, the performance of fuel cell was significantly increased with the increase of cathode catalyst loading. However, the performance did not increase further above a certain Pt-Ru catalyst loading as the increase of anode catalyst loading.

• 한국세라믹학회지
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• 제40권2호
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• pp.118-122
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• 2003

The performance evaluation on Pt loading in the self-humidifying polymer electrolyte membrane for Polymer Electrolyte Mem-Brane Fuel Cell(PEMFC) was investigated by using single cell test and measurement of membrane resistance. The self-humidifying membrane comprised two membranes made of perfluorosulfonylfluroride copolymer resin and fine Pt particles tying between them, coated by sputtering. From the results of performance characteristics of self-humidifying membrane cell with different Pt loading, a single cell using self-humidifying membrane with 0.15 mg/$\textrm{cm}^2$ Pt loading showed better performance than that with the others over entire current density. Also, a single cell with 0.15 mg/$\textrm{cm}^2$ Pt loading had a lower resistance value than the other cells under externally nonhumidifying condition. It is indicated that the water produced in the membrane cell with 0.15 mg/$\textrm{cm}^2$ Pt loading showed a higher provision to maintain ionic conductivity of the membrane than the other cells. The optimum amount of Pt particles embedded in the membrane for self-humidifying PEMFC was determined to be about 0.15 mg/$\textrm{cm}^2$.

• 한국정밀공학회지
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• 제27권2호
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• pp.153-159
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• 2010

Recently, it has been reported that mechanical stimulation takes a role in improving cell growth. Also, became generally known that skeletal system as bone or cartilage tissues take influence of compression loading. In this study, we fabricated a custom-made bioreactor and analyzed that conditions of compressive loading would influence cell growth. To compare the effect of intermittent compressive loading on cell-encapsulated agarose scaffold, we cultured preosteoblast cell (MC3T3-E1 cells) statically and dynamically. And dynamic culture conditions were produced by changing parameters such as the iteration time and interval delay time. Also, cellencapsulated agarose scaffold were subjected to 10 % dynamic compressive strain at 1㎐ frequency for 7 days. After cell culture, cell proliferation was assessed with PI stain assay for fluorescence images and flow cytometry (FACS).

• 대한의용생체공학회:의공학회지
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• 제45권1호
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• pp.43-48
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• 2024

The prevalence of obesity and its complications is steadily increasing worldwide. It is essential to understand cellular level metabolism and microenvironment to treat diseases related to lipid metabolism. Mechanical loading can activate signaling pathway by stimulating cells, especially vibration loading known to inhibit adipogenesis, so it has been studied as a treatment for obesity. Also, vibration loading can affect the inside of the human body non-invasively. Another clue to reducing adipose tissue is browning, which means that white adipocytes changes to brown adipocyte. In this study, we design and developed a device that that can control cell-cell contact, and vibration simulation device. Using these two devices, we investigated responses of cells to vibration loading. Protein expression associated with browning and adipogenesis were analyzed. In conclusion, vibration loading can be transmitted through cell contact and loading applied to the cells can induce browning and inhibit adipogenesis of preadipocytes. These results suggest the possibility that vibrations could be a treatment for obesity.

• Journal of Electrochemical Science and Technology
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• 제8권4호
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• pp.331-337
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• 2017

A simple strategy is proposed herein for attaining uniform current distribution in direct methanol fuel cells by varying the catalyst loading over the electrode. In order to use the same total catalyst amount for a serpentine flow field, three spatial variation types of catalyst loading were selected: enhancing the cathode catalyst loading (i) near the cathode outlet, (ii) near the cathode inlet, and (iii) near the lateral areas. These variations in catalyst loading are shown to improve the homogeneity of the current distribution, particularly at lower currents and lower air-flow rates. Among these three variations, increased loading near the lateral areas was shown to contribute most to achieving a homogenous current distribution. The mechanism underlying each catalyst loading variation method is different; very high catalyst-loading is shown to decrease the homogeneity of the distribution, which may be caused by water management in the thick catalyst layer thereof.

• 한국수소및신에너지학회논문집
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• 제23권2호
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• pp.125-133
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• 2012

Nafion ionomer located in electrode helps to increase the platinum utilization and proton conductivity. To achieve higher performance in PEMFCs, it is important an optimum Nafion content in the electrode. As the platinum loading and fabricated method depend on the optimum Nafion content. In this study, we have examined the interrelationship between platinum loading and Nafion content fabricated by decal transfer method. For electrodes with 0.25 and 0.4 mg/$cm^2$ Pt loading, best performance was obtained at 25 wt.% Nafion ionomer loading. It is also found that MEA with 0.25 mg/$cm^2$ Pt, the optimum Nafion content appears differently at low and high current density.

• Journal of the Korean Wood Science and Technology
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• 제20권4호
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• pp.57-64
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• 1992

The unique cell wall micropores of pulp fiber can be utilized as loading site in variety of important practical application which could be the basis of new papermaking technologies. One of these includes the manufature of paper containing higher levels of in situ filler precipitated. Hardwood pulp fiber were first impregnated with the solution of sodium carbonate($Na_2CO_3$). The micropores in cell wall of pulp fibers were filled with the liquid salt solution. The second calcium nitrate($Ca(NO_3)_2$) solution formed an insoluble calcium carbonate($CaCO_3$) precipitate within the cell wall micropores by interacting with the first sodium carbonate solution. The effects of chemical concentration and dryness of pulp fibers on the retention of cell wall micropore loaded filler were investigated. The paper properties of cell wall micropore loaded pulp fibers were compared with those of conventionally loaded and lumen loaded pulp fibers. Also the presense of the fillers within the cell wall micropore was observed by SEM. Increasing the chemical concentration to generate the calcium carbonate increased the retention of filler in cell wall micropore loaded pulp fibers. The particle size distribution of precipitated calcium carbonate ranged from $0.1{\mu}m$ to $80{\mu}m$. But, the average particle size of cell wall micropore loaded calcium carbonate was $4{\mu}m$. The paper made from never dried pulp fibers, the cell wall micropores which were filled with calcium carbonate, had better mechanical and optical properties than those of conventionally loaded or lumen loaded pulp fibers.

• 한국통신학회논문지
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• 제23권4호
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• pp.901-913
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• 1998

본 논문에서는 CDMA 셀룰러 망에서 셀 간의 간섭이 불균일한 경우에 역방향 링크에서의 간섭을 계산하기 위한 새로운 해석 방법을 제시한다, 특히, 제안된 방식에서는 역방향 링크 전력 제어의 동적 특성을 반영함으로써 셀 간의 불균일한 통화량이 시스템 용량에 미치는 영향을 정확하게 정량화할 수 있으며, 셰도잉과 소프트 핸드 오프에 따른 영향을 고려한 분석이 가능하다. 이와 같이 셀 간의 불균일한 통화량을 고려한 상황에서 역방향 링크 전력 제어의 동적 특성을 반영한 간섭 계산 방식은 기존 연구에서 제시되지 않은 부분이다. 제안된 방식으로 계산된 결과를 살펴보면, 인접한 모든 셀들의 통화량이 두배가 될 때 계산된 가입자 수는 전력 제어의 동적 특성을 고려하지 않고 계산된 결과에 비해 27%까지 감소하는 것을 알 수 있다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1996년도 봄 학술발표회 논문집
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• pp.348-353
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• 1996

This study addresses the evaluation of the durability of reinforced concrete marine structures subjected to fatigue loading. The laboratory investigation was carried out on full and half size reinforced concrete specimens with three different water cement ratios (0.3, 0.4, and 0.56), static and fatigue loading conditions, and epoxy-coated and regular black steel reinforcements. The marine tidal zone was simulated by alternate filling and draining of the tank (wet and dry cycled), and a galvanostatic corrosion technique to accelerate corrosion of reinforcement was used. Half-cell potentials and changes of crack width were measured periodically during the exposure and followed by ultimate strength testing. The significant findings include adverse effect of fatigue loading, existence of an explicit size effect, poor performance of epoxy coated steel, and negative effect of increasing water/cement ratio.

• 한국통신학회논문지
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• 제21권6호
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• pp.1576-1586
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• 1996

The subject of this paper is the analysis of a Wire-TEM cell(W-TEM cell) which has an inner wire array rather than a metallic septum;its basic structure is similiar to a NBS TEM cell. To verify improved performances of this W-TEM cell as a standard EM field generator, well-known quasi-static approximations are employed and their resultant ingegral equations are numerically analyzed by moment method. Although the electric field strength of a W-TEM cell is 1.4 dB lower than tht of a NBS TEM cell, the uniformity of EM field patterns in a W-TEM cell is improved. It is also shown that the EM field distortions resulting from loading by the conditing objects under test(loading effects), are decreased considerably. This paper also deals with the investigations about relationship between the EM field distributions and the number of wire composing the inner conductor. Finally, the experimental analysis is performed on the practical model which is built on the basis of the design variables brought out by the theoretical andnumerical analysis.