• 한국수소및신에너지학회논문집
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• 제31권2호
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• pp.177-183
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• 2020

To utilize hydrogen energy, high-yield, high-purity hydrogen needs to be produced; therefore, hydrogen separation membrane studies are being conducted. The membrane reactor that fabricates hydrogen needs to have high hydrogen permeability, selective permeability, heatresistant and a stable mechanical membrane. Dense membranes of Pd and Pd alloys are usually used, but these have drawbacks associated with high cost and durability. Therefore, many researchers have studied replacing Pd and Pd alloys. Dense TiN membrane is highly selective and can separate high-purity hydrogen. The porous alumina has a high permeation rate but low selectivity; therefore, separating high-purity hydrogen is difficult. To overcome this drawback, the two materials are combined as composite reclamations to produce a separation membrane with a high penetration rate and high selectivity. Accordingly, TiN-alumina was manufactured using a high-energy ball mill. The TiN-alumina membrane was characterized by X-ray diffraction analysis, scanning electron microscopy, and energy dispersive spectroscopy. The hydrogen permeability of the TiN-alumina membrane was estimated by a Sievert-type hydrogen permeation membrane apparatus. Due to the change in the diffusion mechanism, the transmittance value was lower than that of the general TiN ceramic separator.

• 분석과학
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• 제13권4호
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• pp.474-483
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• 2000

사용후핵연료에 함유되어 있는 핵분열생성물을 분석하기 위하여 여러 원소를 동시에 분석할 수 있고, 분석감도가 커서 시료의 방사능과 폐기물의 양을 감소시킬 수 있는 유도 결합 플라스마 원자방출분광기/차폐 시스템을 구성하였다. 방사성 물질이 직접 접촉되는 플라스마 들뜸원과 시료용액 도입부를 스테인리스 스틸 재질의 글로브박스 내부에 설치하였으며, 고주파 들뜸전원, 분광기, 검출기 그리고 전기, 전자 및 아르곤 가스 공급 제어장치는 외부에 설치하였다. 분석능과 방사선 안전의 관점에서 시스템의 특성을 검증하였으며, 사용후핵연료 용해용액과 원자력발전소의 일차냉각수를 대상으로 핵분열생성물과 방사성 부식생성물 분석에 대한 적용성을 평가한 결과 $0.01-0.1mgL^{-1}$ 농도범위에서 상대표준편차는 5% 이하였다.

• 한국산학기술학회논문지
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• 제12권12호
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• pp.5405-5411
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• 2011

본 연구에서는 교량용 구조용 강재인 HSB600 강의 용접부에서 입열량 (1.5~3.6 kJ/mm)과 용접후 열처리(PWHT, $600^{\circ}C$, 40hr.)가 미세조직과 기계적 특성에 미치는 영향에 관해 연구하였다. HSB600 강재를 GMA용접을 실시하였다. 용접된 상태에서는 인장강도와 경도는 입열량이 증가할수록 저하되었으며 충격 흡수 에너지는 큰 차이를 보이지 않았다. 낮은 입열량인 1.5 kJ/mm에서 침상형 페라이트가 가장 많이 생성되었다. 용접후 열처리를 통해 경도와 인장강도가 저하되었고, 용착금속의 충격흡수에너지가 증가되었다.

• 한국전기전자재료학회논문지
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• 제32권1호
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• pp.78-85
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• 2019

The effect of various lithium sources such as LiCl, LiOH, and Li-metal on the microstructure and electrochemical properties of granulated $SiO_x$ powders were investigated. Various lithium sources were metallurgically added for a passive pre-lithiation of $SiO_x$ to improve its low initial coulombic efficiency. In spite of using the same amount of Li in various sources, as well as the same process conditions, different lithium silicates were obtained. Moreover, irreversible phases were formed without reduction of $SiO_x$, which might be from additional oxygen incorporation during the process. Accordingly, there were no noticeable electrochemical enhancements. Nevertheless, the $Li_4SiO_4$ phase changes the initial electrochemical reaction, and consequently the relationship between the microstructure and electrochemical properties of metallurgically pre-lithiated $SiO_x$ could provide a guideline for the optimization of the performance of lithium ion batteries.

• 대한금속재료학회지
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• 제46권10호
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• pp.646-651
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• 2008

The electrolytic reduction of spent oxide fuel involves the liberation of oxygen in a molten LiCl electrolyte, which results in a chemically aggressive environment that is too corrosive for typical structural materials. It is essential to choose the optimum material for the process equipment handling molten salt. IN713LC is one of the candidate materials proposed for application in electrolytic reduction process. In this study, yttria-stabilized zirconia (YSZ) top coat was applied to a surface of IN713LC with an aluminized metallic bond coat by an optimized plasma spray process, and were investigated the corrosion behavior at $675^{\circ}C$ for 216 hours in the molten salt $LiCl-Li_2O$ under an oxidizing atmosphere. The as-coated and tested specimens were examined by OM, SEM/EDS and XRD, respectively. The bare superalloy reveals obvious weight loss, and the corrosion layer formed on the surface of the bare superalloy was spalled due to the rapid scale growth and thermal stress. The top coatings showed a much better hot-corrosion resistance in the presence of $LiCl-Li_2O$ molten salt when compared to those of the uncoated superalloy and the aluminized bond coatings. These coatings have been found to be beneficial for increasing to the hot-corrosion resistance of the structural materials for handling high temperature lithium molten salts.

• Corrosion Science and Technology
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• 제20권3호
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• pp.158-168
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• 2021

Austenitic 316 stainless steel was irradiated with protons accelerated by an energy of 2 MeV at 360 ℃, the various defects induced by this proton irradiation were characterized with microscopic equipment. In our observations irradiation defects such as dislocations and micro-voids were clearly revealed. The typical irradiation defects observed differed according to depth, indicating the evolution of irradiation defects follows the characteristics of radiation damage profiles that depend on depth. Surface oxidation tests were conducted under the simulated primary water conditions of a pressurized water reactor (PWR) to understand the role irradiation defects play in surface oxidation behavior and also to investigate the resultant irradiation assisted stress corrosion cracking (IASCC) susceptibility that occurs after exposure to PWR primary water. We found that Cr and Fe became depleted while Ni was enriched at the grain boundary beneath the surface oxidation layer both in the non-irradiated and proton-irradiated specimens. However, the degree of Cr/Fe depletion and Ni enrichment was much higher in the proton-irradiated sample than in the non-irradiated one owing to radiation-induced segregation and the irradiation defects. The microstructural and microchemical changes induced by proton irradiation all appear to significantly increase the susceptibility of austenitic 316 stainless steel to IASCC.

• 한국표면공학회지
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• 제56권6호
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• pp.437-442
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• 2023

This research aims to enhance the efficiency of Pt/C catalysts due to the limited availability and high cost of platinum in contemporary fuel cell catalysts. Nano-sized platinum particles were distributed onto a carbon-based support via the polyol process, utilizing the metal precursor H₂PtCl₆·6H₂O. Key parameters such as pH, temperature, and RPM were carefully regulated. The findings revealed variations in the particle size, distribution, and dispersion of nano-sized Pt particles, influenced by temperature and pH. Following sodium hydroxide treatment, heat treatment procedures were systematically executed at diverse temperatures, specifically 120, 140, and 160 ℃. Notably, the thermal treatment at 140 ℃ facilitated the production of Pt/C catalysts characterized by the smallest platinum particle size, measuring at 1.49 nm. Comparative evaluations between the commercially available Pt/C catalysts and those synthesized in this study were meticulously conducted through cyclic voltammetry, X-ray diffraction (XRD), and field-emission scanning electron microscopy-energy dispersive X-ray spectroscopy (FE-SEM EDS) methodologies. The catalyst synthesized at 160 ℃ demonstrated superior electrochemical performance; however, it is imperative to underscore the necessity for further optimization studies to refine its efficacy.

• 대한기계학회논문집B
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• 제34권4호
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• pp.423-428
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• 2010

반도체 공정에서 배출되는 미세입자를 포집하기 위하여 전기집진장치가 적용되고 있으나, 배출가스 내 포함된 강부식성 오염원에 의한 전기집진장치 내부 오염 및 부식 문제가 심각하여, 이를 해결하기 위한 방안이 절실하다. 본 연구에서는 탄소섬유로 이루어진 하전부와 PET 필름 사이에 금속 박막이 삽입된 집진부로 이루어진 내부식 전기집진장치를 개발하여, 하전부 및 집진부 인가전압, 처리유량, 하전부 채널 수 등의 운전 조건에 따른 전기집진기의 초미세입자 집진 성능을 평가하였다. 평균입경이 100 nm인 KCl 입자를 시험입자로 사용하였으며, 전기집진기 전/후단 입자 농도 변화를 측정하기 위하여 SMPS를 사용하였다. 본 연구에서 개발된 9채널 하전부와 65 mm 집진부로 구성된 전기집진기의 성능평가 결과, $500\;m^3/hr$ 유량조건에서 하전부 및 집진부에 7 kV와 10 kV를 각각 인가하였을 때, 300 nm입자에 대한 포집효율이 90% 이상으로 높게 나타났다.

• 공업화학
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• 제21권3호
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• pp.328-332
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• 2010

본 연구에서는 다이에틸렌글리콜 용매 상에서 공침법을 이용하여 기공성 아연 구형 산화물과 구리-아연 복합 산화물을 합성하였다. 합성된 물질들의 물리화학적 특성은 전자현미경, X-선 회절분석, $N_2$ 흡착, $H_2$-TPR 방법을 통하여 분석되었고, 다양한 Cu 함량(0, 6.6, 21.3 36.4, 54.6, 77.8 wt%)을 포함한 Cu-ZnO 복합 산화물을 고정층 반응 장치에서 일산화탄소 산화 반응성을 고찰하였다. 합성된 산화물 중에서 Cu 함량이 증가할수록 Cu-ZnO의 비표면적과 미세 기공 부피는 감소하였으며, Cu (36.4 wt%)-ZnO이 가장 좋은 일산화탄소 산화 반응성을 나타내었다.

• 한국전기전자재료학회논문지
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• 제29권9호
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• pp.581-588
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• 2016

Piezoelectric thick films of a soft $Pb(Zr,Ti)O_3$ (PZT) based commercial material were produced by a conventional tape casting method. Thereafter, the interdigitated (IDT) Ag-Pd electrode pattern was printed on the $25{\mu}m$ thick piezoelectric film at room temperature. Co-firing of the 10-layer laminated piezoelectric thick films was conducted at $1,100^{\circ}C$ and $1,150^{\circ}C$ for 1 h, respectively. Piezoelectric cantilever energy harvesters were successfully fabricated using the IDT electrode pattern embedded piezoelectric laminates for 3-3 operation mode. Their energy harvesting characteristics were investigated with an excitation of 120 Hz and 1 g under various resistive loads (ranging from $10k{\Omega}$ to $200k{\Omega}$). A parabolic increase of voltage and a linear decrease of current were shown with an increase of resistive load for all the energy harvesters. In particular, a high output power of 3.64 mW at $100k{\Omega}$ was obtained from the energy harvester (sintered at $1,150^{\circ}C$).