• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2008.10a
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• pp.183-187
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• 2008

This paper describes a power control scheme to improve the performance of a fuel cell battery hybrid power source for residential application. The proposed power control scheme includes a power control strategy to control the power flow of the fuel cell hybrid power system and a digital control technique for a front-end dc-dc converter of the fuel cell. The power control strategy enables the fuel cell to operate within the high efficiency region defined by the polarization curve and efficiency curve of the fuel cell. A dual boost converter with digital control is applied as a front-end dc-dc converter to control the fuel cell output power. The digital control technique of the converter employs a moving-average digital filter into its voltage feedback loop to cancel the low frequency harmonic current drawn from the fuel cell and then limits the fuel cell output current to a current limit using a predictive current limiter to keep the fuel cell operation within the high efficiency region as well as to minimize the fuel cell oxygen starvation.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.30 no.3
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• pp.143-148
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• 2018

In this study the performance and humidity variation for 2 unit cells connected in series were experimentally measured. The relative flow direction of hydrogen and air was changed from parallel flow to counter flow. Internal humidity distribution was then measured by 5 embedded sensors on each channel. In all experimental conditions, the former unit cell showed a better performance and the gap is noted to be higher when counter flow is applied. The performance was noted to be higher at high humidification case in the parallel flow. However, in the counter flow, the difference of performance according to the humidification is negligible. Hydrogen and air are discharged from the PEMFC unsaturated with water vapor at parallel flow/low humidification condition, which explains lower performance of the PEMFC than other conditions. The humidities in hydrogen and air streams of counter flow were noted to increase rapidly even at low humidification condition and the consequential even hydration of membrane is the reason of higher performance.

• Transactions of the Korean hydrogen and new energy society
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• v.30 no.2
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• pp.147-154
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• 2019

In this study, effects of flow types and size of molten carbonate fuel cells (MCFCs) were investigated using CFD simulation. In the simulation, the current collector of MCFCs were assumed to be an porous media. With the area of $0.09m^2$, the effect of flow types such as Co-flow, Counter-flow, Cross-flow were studied. After that the effect of the size and flow direction was studied. Among three-flow types, MCFCs with co-flow type shows more uniform distribution and current density distribution.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.58 no.4
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• pp.609-614
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• 2009

A fuel-cell power system among various alternative power sources has many advantages such as comparatively independable circumstances, high-efficient, and heat-recyclable, thus it is now able to be up to hundreds MWh-scaled through improving feasibility and longevity of it. During the last few decades, numerous research results has been investigated to expand interest in fuel-cell technology. This study presents pressure distribution on the geometrical manifold structures, which are U-type and Z-type, of a planar-type fuel-cell stack by simulated with computational fluid dynamics(CFD). Then, electrical performance of a 200W fuel-cell stack, which is U-type, was diagnosed after pre-conditioning operation. The stack has electrical characteristics ; 22V, 10A, 220W, and current density $200mA/cm^2$.

• Journal of the Korean Operations Research and Management Science Society
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• v.22 no.2
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• pp.99-123
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• 1997

Performance analysis of NTT/BT protocol is investigated, which is a GFC (Generic Flow Control) ptotocol in ATM (Asynchronous Transfer Mode ) network and is based on cyclic reset mechanism. THe mean cell delay time is proposed as a performance measure of NTT/BT protocol. The mean cell delay time is defined as the duration from the instant the cell arrives at the transmission buffer until the cell is fully transmitted. The process of cell transmission can be described as a single server queueing modle with two dependent services. By utilizing this model, mean cell delay time is obtained and sensitivity of the factors such as window size and reset period is also analysed.

• IMMUNE NETWORK
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• v.9 no.4
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• pp.138-146
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• 2009

Background: The MHC region of the chromosome contains a lot of genes involved in immune responses. Here we have investigated the mouse NG29/Cd320 gene in the centrometrically extended MHC region of chromosome 17. Methods: We cloned the NG29 gene by RT-PCR and confirmed the tissue distribution of its gene expression by northern blot hybridization. We generated the NG29 gene expression constructs and polyclonal antibody against the NG29 protein to perform the immunofluorescence, immunoprecipitation and flow cytometric analysis. Results: The murine NG29 gene and its human homologue, the CD320/8D6 gene, were similar in the gene structure and tissue expression patterns. We cloned the NG29 gene and confirmed its expression in plasma membrane and intracellular compartments by transfecting its expresssion constructs into HEK 293T cells. The immunoprecipitation studies with rabbit polyclonal antibody raised against the NG29-NusA fusion protein indicated that NG29 protein was a glycoprotein of about 45 kDa size. A flow cytometric analysis also showed the NG29 expression on the surface of Raw 264.7 macrophage cell line. Conclusion: These findings suggested that NG29 gene in mouse extended MHC class II region was the orthologue of human CD320 gene even though human CD320/8D6 gene was located in non-MHC region, chromosome 19p13.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.128.2-128.2
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• 2010

For stationary 1kW-class fuel cell systems to be used widely, it is essential to achieve dramatic improvements in system durability as well as cost reduction. In order to address this engineering challenge, it is important to develop innovative technologies associated with BOP components. According to this background, in 2009, the Korean Government and "Korea Institute of Energy Technology Evaluation and Planning(KETEP)" launched into the strategic development project of BOP technology for practical applications and commercializations of stationary fuel cell systems, named "Technology Development on Cost Reduction of BOP Components for 1kW Stationary Fuel Cell Systems to Promote Green-Home Dissemination Project". The objectives of this project are to develop fundamental technologies to meet these requirements, and to improve the performance and functionality of BOP components with reasonable price. The project consortium consists of Korea's leading fuel cell system manufacturers, BOP component manufacturers which technologically specialized, and several research institutions. This paper is to provide a summary of the project, as well as the achievements made through the 1st period of the project(2009~2010). Several prototypes of BOPs - Cathode air blowers, burner air blowers, preferential oxidation air blowers, fuel blowers, cooling water pumps, reformer water pumps, heat recovery pumps, mass flow meters, valves and power conditioning systems - had been developed through this project in 2010. As results of this project, it is expected that a technological breakthrough of these BOP components will result in a substantial system cost reduction.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.6
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• pp.2883-2888
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• 2014

Background: Realgar which contains arsenic components has been used in traditional Chinese medicine (TCM) as an anticancer drug. However, neither Realgar nor its formula are soluble in water. As a result, high dose of Realgar has to be administered to achieve an effective blood medicine concentration, and this is associated with adverse side effects. The objective of the present study was to increase the solubility of a formula using hydrometallurgy technology as well as investigating its effects on in vitro and in vivo cell proliferation and apoptosis in Sarcoma-180 cell line. Materials and Methods: Antiproliferative activity of Realgar Bioleaching Solution (RBS) was evaluated by MTT assay. Further, effects of RBS on cell proliferation and apoptosis were studied using flow cytometry and transmission electron microscopy. Kunming mice were administered RBS in vivo, where arsenic specifically targeted solid tumors. Results: The results indicated that RBS extract potently inhibited the tumor growth of Sarcoma-180 cell line in a dose-dependent manner. Flow cytometry and transmission electron microscopy further indicated that RBS significantly induced cell apoptosis through the inhibition of cell cycle pathway in a dose-dependent manner. Further, on RBS administration to mice, arsenic was specifically targeted to solid tumor.s Conclusions: RBS could substitute for traditional Realgar or its formula to work as a potent tool in cancer treatment.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.12
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• pp.7137-7141
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• 2013

Several studies have shown that nemo-like kinase (NLK) plays a vital role in apoptosis of cancer cells. The present research concerned effects and mechanisms of Taxol on NLK knockdown human laryngeal cancerHep-2 cell lines in vitro. Using RNAi, methyl-thiazoltetrazolium (MTT) assays, real-time RT-PCR, Western blotting and flow cytometry analysis, growth and the cell cycle progression of NLK knockdown Hep-2 cells and expression of downstream molecules were observed. Cell growth was obviously suppressed in the Taxol treated group (P<0.001, 48 hours). Cell numbers of combined Taxol-based chemotherapy with lentivirus mediated RNAi treatment group (Lv-shNLK+Taxol goup) were significantly different from NLK-specific siRNA lentivirus infected group (Lv-shNLK group) (p<0.001). Flow cytometry analysis revealed that Lv-shNLK+Taxol caused the G0/G1-phase DNA content to decrease from 44.1 to 3.33% (p<0.001) and the S-phase DNA content to increase from 38.4 to 82.0% (p<0.001), in comparison with the Lv-shNLK+Taxol group. Immunoblot analysis showed that knockdown of NLK led to significant reduction in the levels of cyclin D1, PCNA and PARP, whereas cyclin B1 was elevated in. Cell growth was also obviously suppressed in the Hep-2 cell line, knockdown of NLK making them more sensitive to Taxol treatment. NLK is expected to become a target of new laryngeal cancer gene therapies.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.6
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• pp.1085-1094
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• 1994

We propose a traffic flow control scheme of B-NT with temporary cell buffering and selective cell discarding to prevent congestion state of the network nodes in B-ISDN systems to reduce or suppress output cell strams towards T interface. We define the states of the network nodes as normal, pre-congestion, and congestion. In a pre-congestion state, the loss-sensitive traffic is temporarily buffered to slow down the rate of the output traffic streams. In a congestion state, the delay-sensitive traffic is selectively discarded to suppress the output traffic streams as possible in addition to the cell buffering. We model the input cell streams and the states of the network nodes with Interrupted Bernoulli Process and 3-state Markov chain to analyze the performance of the proposed scheme in the B-NT system. The appropriate size of the cell buffer is explored by means of simulation and the influence on the performance of the proposed scheme by the network node state is discussed. As results, more than 2,00 cells of buffer size is needed for the control of medium of lower than the medium, degree of congestion occurrence in the network node while the control of high degree of congestion occurrence is nearly impossible.