• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.233-236
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• 2003

수소 가스발생을 위한 마이크로 수소 발생기 개발에서 MEMS 공정을 이용하여 기판에 반응 유로를 위해 HAR(High Aspect Ratio) 구조물을 형성하고 Ru(ruthenium) 박막을 증착하여 수소 발생량을 측정하였다. Pyrex glass 기판상에 sand blast 방법으로 반응 구조물을 만들었으며, 그 위에 sputter system을 이용하여 Ru 박막을 $5500{\AA}$었다. 수소 발생량은 촉매 박막이 증착된 기판 재질과 기판의 표면 상태 그리고 마이크로 수소 발생기에 두께로 증착하였다. 반응 구조물의 전체 크기가 가로 2.0 cm, 세로 2.0cm의 면적에서 약 12.3 ml/min의 수소가 측정되 형성한 구조물의 형상에 의존하였다. Pyrex glass 기판을 사용하여 HAR로 반응 구조물을 형성한 경우에 단위 면적당 Ru 박반응 막의 반응 표면적이 증가되어 기존에 구조물을 형성하지 않은 평면 기판에 비교하여 약 5.5배 이상의 수소 발생이 증가하였다.

• Nuclear Engineering and Technology
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• v.33 no.4
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• pp.423-440
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• 2001

For sodium cooling liquid metal reactors during the last 25 years, it was most important to verify the safety of the steam generator, which absolutely requires a water leak detection system with fine sensitivity and response. This study describes the structure and leak classification of the HAMMER (Korea Advanced Liquid Metal Reactor) steam generator, compared with other classifications, and explains the effects of leak development. The requirements and experimental situations for the development of the KALIMER acoustic leak detection system (KADS) which detects micro leaks, not intermediate leaks, are introduced. We proposed four frequency bands, 1∼8kHz, 8∼20kHz, 20∼40kHz and 40∼200kHz, split effectively for analyzing the detected acoustic leak signals obtained from the sodium-water reaction model or water model in the mock-up system.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.611-612
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• 2005

Fuel cells is proved that potential energy is greater than the existing power generation. In this paper, we describe a principle of fuel cell which is used for next generation portable battery and brief characteristic of direct methanol fuel cells (DMFCs) that used for portable appliances by miniaturization of polymer electrolyte fuel cell. Lastly we describe about research investment for fuel cells.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2002.05a
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• pp.38-38
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• 2002

Kinetic indentation technique was studied and a method to evaluate wear and fatigue behaviors of irradiated small specimen was suggested. The method is based on both the proportion of elastic and plastic deformation and values obtained by micro-hardness test. The parameters obtained from the diagram of load-indentation depth-time are required to evaluates wear and fatigue properties. Considering the irradiated test specimen, it is one of possible and useful methods to estimate the irradiated wear and fatigue behaviors of the small size specimen. This article briefly describes the status of irradiated material study in domestic research reactor.

• Applied Chemistry for Engineering
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• v.34 no.1
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• pp.23-29
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• 2023

Microfluidic reactors have been made to achieve significant development for the generation of new functional materials to apply in a variety of fields. Over the last decade, microfluidic reactors have attracted attention as a user-friendly approach that is enabled to control physicochemical parameters such as size, shape, composition, and surface property. Here, we develop a centrifugal microfluidic reactor that can control the flow of fluid based on centrifugal force and generate multifunctional particles of various sizes and compositions. A centrifugal microfluidic reactor is fabricated by combining microneedles, micro- centrifuge tubes, and conical tubes, which are easily obtained in the laboratory. Depending on the experimental control param- eters, including centrifuge rotation speed, alginate concentration, calcium ion concentration, and distance from the needle to the calcium aqueous solution, this strategy not only enables the generation of size-controlled microparticles in a simple and reproducible manner but also achieves scalable production without the use of complicated skills or advanced equipment. Therefore, we believe that this simple strategy could serve as an on-demand platform for a wide range of industrial and academic applications, particularly for the development of advanced smart materials with new functionalities in biomedical engineering.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.180-180
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• 2012

Heteroepitaxial GaN nano- and micro-rods (NMRs) are one of the most promising structures for high performance optoelectronic devices such as light emitting diodes, lasers, solar cells integrated with Si-based electric circuits due to their low dislocation density and high surface to volume ratio. However, heteroepitaxial GaN NMRs growth using a metal-organic vapor phase epitaxy (MOVPE) machine is not easy due to their long surface diffusion length at high growth temperature of MOVPE above $1000^{\circ}C$. Recently some research groups reported the fabrication of the heteroepitaxial GaN NMRs by using MOVPE with vapor-liquid-solid (VLS) technique assisted by metal catalyst. However, in the case of the VLS technique, metal catalysts may act as impurities, and the GaN NMRs produced in this mathod have poor directionallity. We have successfully grown the vertically well aligned GaN NMRs on Si (111) substrate by means of self-catalystic growth methods with pulsed-flow injection of precursors. To grow the GaN NMRs with high aspect ratio, we veried the growth conditions such as the growth temperature, reactor pressure, and V/III molar ratio. We confirmed that the surface morphology of GaN was strongly influenced by the surface diffusion of Ga and N adatoms related to the surrounding environment during growth, and we carried out theoretical studies about the relation between the reactor pressure and the growth rate of GaN NMRs. From these results, we successfully explained the growth mechanism of catalyst-free and mask-free heteroepitaxial GaN NMRs on Si (111) substrates. Detailed experimental results will be discussed.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.25 no.6
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• pp.252-256
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• 2015

Nitrogen oxides ($NO_X$) was emitted from flue gas of stationary sources and exhaust gas of mobile sources, can leads to various environments problems. Selective Catalysts Reduction (SCR) is the most effective $NO_X$ removal system. Commercial $V_2O_5-WO_3/TiO_2$ catalysts, usually containing $V_2O_5$ 0.5~3 wt%, $WO_3$ 5~10 wt%, and $V_2O_5$ is active in the reduction of $NO_X$ but also in the desired oxidation of $SO_2$ to $SO_3$. To reduce the amount of vanadium, using graphene matrix supported vanadium to synthesize nanocomposite. Then, we fabricated to 1 inch honeycomb type of SCR catalysts adding graphene-vanadium nanocomposite. The chemical-physical characteristics and the catalytic activity were performed by XRD, XRF, BET and Micro-Reactor (MR). As a result, the De-NOX performance was showed, similar to the commercial catalyst activity as 77.8 % and using nanocomposite catalyst as 77.1 % at $350^{\circ}C$.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.10
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• pp.4672-4678
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• 2013

Aluminum dross is formation at the surface of the molten metal as the latter reacts with the furnace atmosphere and it was an unavoidable by-product of the aluminum production process. However aluminum dross was usually landfilled or disposed without treatment, causing much environmental damage. The purpose of this study is to investigate the possibility of ceramic catalyst support using recycled Al dross. The recycled Al dross was made into SCR catalyst by mixing with $WO_3$, $V_2O_5$ and $TiO_2$. The $V_2O_5-WO_3/TiO_2-Al_2O_3$ SCR catalyst was observed with XRF, XRD and BET. $V_2O_5-WO_3/TiO_2-Al_2O_3$ SCR strength was measured by Universal Testing Machine(UTM). As the added $Al_2O_3$, streagth is increased. And the NOx removal activity was observed by MR(Micro-Reactor). The temperatures ranging from $350^{\circ}C$ and $400^{\circ}C$, $V_2O_5-WO_3/TiO_2-Al_2O_3$ SCR catalyst De-NOx performance result of showed excellent activity over 90% at application condition.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.41 no.6
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• pp.381-387
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• 2017

Dehydrogenation from the hydrolysis of a sodium borohydride ($NaBH_4$) solution has been of interest owing to its high theoretical hydrogen storage capacity (10.8 wt.％) and potentially safe operation. An experimental study has been performed on the catalytic reaction rate and pressure drop of a $NaBH_4$ solution over both a single microchannel with a hydraulic diameter of $300{\mu}m$ and a staggered array of micro pin fins in the microchannel with hydraulic diameter of $50{\mu}m$. The catalytic reaction rates and pressure drops were obtained under Reynolds numbers from 1 to 60 and solution concentrations from 5 to 20 wt.％. Moreover, reacting flows were visualized using a high-speed camera with a macro zoom lens. As a result, both the amount of hydrogenation and pressure drop are 2.45 times and 1.5 times larger in a pin fin microchannel array than in a single microchannel, respectively.

• Korean Journal of Environmental Agriculture
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• v.28 no.4
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• pp.371-377
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• 2009

In this study, simultaneous nitrification and denitrification (SND) from synthetic wastewater were performed to evaluate dissolved oxygen(DO) effects on chemical oxygen demand(COD) and nitrogen removal in a single membarne bio-reactor(MBR). DO levels in MBR at Run 1, 2, and 3 were 1.9~2.2, 1.3~1.6, and 0.7~1.0 mg/L, respectively. Experimental results indicated that DO had an important factor to affect COD and total nitrogen(TN) removal. SND were able to be accomplished in the continuous-aeration MBR by controlling ambient DO concentration. It is postulated that, because of the oxygen diffusion limitation, an anoxic micro-zone was formed inside the flocs where the denitrification might occur. From the results of this study, 96% of COD could be removed at DO of 0.7mg/L. At run 2 72.92% of nitrogen was removed by the mechanisms of SND (7.75mg-TN/L in effluent). In this study, SND was successfully occurred in a MBR due to high MLSS that could help to form anoxic zone inside microbial floc at bulk DO concentrations of 1.3~1.6mg/L.