• 한국결정성장학회지
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• 제33권2호
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• pp.78-82
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• 2023

The oxygen evolution reaction (OER) is the primary challenge in renewable energy storage technologies, specifically electrochemical water splitting for hydrogen generation. We report effects of Mo doping into Ni layered double hydroxide (Ni-LDH) microcrystal on electrocatalytic activities. In this study, Mo doped Ni-LDH were grown on three-dimensional porous nicekl foam (NF) by a facile solvothermal method. Homogeneous LDH structure on the NF was clearly observed. However, the surface microstructure of the nickel foam began to be irregular and collapsed when Mo precursor is doped. Electrocatalytic OER properties were analyzed by Linear sweep voltammetry (LSV) and Electrochemical impedance spectroscopy (EIS). The amount of Mo doping used in the electrocatalytic reaction was found to play a crucial role in improving catalytic activity. The optimum Mo amount introduced into the Ni LDH was discussed with respect to their OER performance.

• Nuclear Engineering and Technology
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• 제42권3호
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• pp.249-258
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• 2010

Recently, many utilities have considered interim dry storage of spent nuclear fuel as an option for increasing spent fuel storage capacity. Foreign nuclear regulatory committees have provided some regulatory and licensing requirements for relatively low- and medium-burned spent fuel with respect to the prevention of spent fuel degradation during transportation and interim dry storage. In the present study, the effect of cladding creep and hydride distribution on spent fuel degradation is reviewed and performance tests with high-burned Zircaloy-4 and advanced Zr alloy spent fuel are proposed to investigate the effect of burnup and cladding materials on the current regulatory and licensing requirements. Creep tests were also performed to investigate the effect of temperature and tensile hoop stress on hydride reorientation and subsequently to examine the temperature and stress limits against cladding material failure. It is found that the spent fuel failure is mainly caused by cladding creep rupture combined with mechanical strength degradation and hydride reorientation. Hydride reorientation from the circumferential to radial direction may reduce the critical stress intensity that accelerates radial crack propagation. The results of cladding creep tests at $400^{\circ}C$ and 130MPa hoop stress performed in this study indicate that hydride reorientation may occur between 2.6% to 7.0% strain in tube diameter with a hydrogen content range of 40-120ppm. Therefore, it is concluded that hydride re-orientation behaviour is strongly correlated with the cladding creep-induced strain, which varies as functions of temperature and stress acting on the cladding.

• 환경영향평가
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• 제21권3호
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• pp.353-365
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• 2012

This study is understanding characteristics and analyzing contributions of the odor causing compounds of complex-odor & major specified odor materials, and contribution analysis, caused pre-treatment facilities(input and storage) and post-treatment facilities(heating and drying). The target of this study is feeds-production-facilities, located in Seoul. The averaged complex-odor compounds on the boundary line is 21 times higher, and it is 15 times higher than emission standards. In cracking&collection(pre-treatment facilities), the concentration of compounds is 4,881 times, 2,080 times in drying, and 1,442 times in putting&storing facilities. Ammonia occupies the largest portion of the results of monitoring specified odor compounds in input&storage facilities, followed Acetaldehyde > Hydrogen sulfide > Methyl mercaptan. In cracking&collection, Ammonia also occupies most of odor compounds, followed Methyl mercaptan > Acetaldehyde > Dimethyl disulfide > Dimethyl sulfide > Hydrogen sulfide. Acetaldehyde > Methyl mercaptan in drying facilities. On the boundary line, however, the concentration of specified odor compounds stays below emission standards. The result of contribution analysis is that methyl mercaptan has the highest contribution in input & storage, as well as cracking&collection facilities, followed Acetaldehyde > Hydrogen sulfide > Dimethyl sulfide > Dimethyl disulfide. In the drying facilities, the contribution shows Methyl mercaptan > Acetaldehyde > i-Valeraldehyde and Butyraldehyde. Therefore, to decrease odor in foodwaste treatment facilities, proper prevention facilities need to be installed and operated, according to characteristics of individual odor compounds, based on monitored data.

• Journal of the Korean Wood Science and Technology
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• 제46권3호
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• pp.285-296
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• 2018

ISPM No. 15에 의거한 열처리 목재의 검증을 위한 연구로서 열처리 목재 표면의 분광학적 특성을 분석하였다. IR 스펙트럼 상에서는 다양한 작용기들이 확인되지만 수종간, 열처리 시간 및 보관 기간에 따른 특별한 차이를 발견하기 어려웠다. HBI(hydrogen-bonding intensity)는 보관 기간에 따른 열처리 목재의 변화는 관찰할 수 있지만 열처리 시간에 따른 변화는 관찰하기 어려웠다. 하지만 PCA score plot 상에서 수종 내에서 60분 혹은 90분의 열처리 시간에 따라 목재의 분류가 가능하였다. PCA에서 열처리 목재의 분류의 기준은 목재 내 리그닌의 방향족 환과 셀룰로오스의 C-H bending이었으며 이들 성분에 의해 ISPM No. 15로 열처리된 목재를 분류할 수 있었다.

• 한국수소및신에너지학회논문집
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• 제22권4호
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• pp.527-533
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• 2011

CNFs had been well addressed due to numerous promising applications in science and technology. Besides the same physicochemical properties of ordinary carbon materials such as active carbons and carbon black, they exhibit specific, e.g., tubular or fibrous structures, a large surface area, high electrical conductivity stability, as well as extremely high mechanical strengh and modulus, which make them a superior material for electrochemical capacitors. In this study, CNFs were pretreated by mechanical milling with different time in mortar and pestle. The milled CNFs were used as active material of electrode whose electrochemical property was tested to find physicochemical characterization variation. CNF electrode milled for 5 min has the highest electric capacitance. XPS spectrum were employed to explore changes in functional group induced from mechanical milling. Crystal size was calculated to analyze change of peak from different milling time by XRD. The CNF milled for 5 min has the largest crystal size and the highest electric capacitance.

• 소성∙가공
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• 제28권4호
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• pp.203-211
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• 2019

In this study, the weight of type IV pressure vessel is optimized through the burst pressure condition using the finite element analysis (FEA) based on the genetic algorithm (GA). The optimization design variables include the thickness of composite layers and the winding angles. The optimized design variables are validated using the numerical simulations for the pressure vessel. Consequently, the weight is decreased by about 6.5% as compared to the previously reported results for Type III pressure vessel. Additionally, a method which reduces the entire optimization time is proposed. In the original method, the population size is constant across all generations. However, the proposed method could reduce the workload through the reduction of the population size by half for every 25 generations. Thus, the proposed method is observed to increase the weight by about 0.1%, however, the working time for the optimization could be decreased by about 46.5%.

• 한국수소및신에너지학회논문집
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• 제31권6호
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• pp.530-545
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• 2020

This paper reviews and summarizes the fuel-cell-related studies those have been recently published in major Korean Citation Index journals, aiming at analyzing the research trend in fuel cell technologies. Six major journals are selected for the literature survey; 57 papers are chosen for the detailed analysis through a screening examination on the total 1,040 papers published during between 2018 and 2020. Papers are classified into six technical categories, such as i) electrode, ii) electrolyte, iii) bipolar plate and stack, iv) fuel cell system, v) balance of plant, and vi) diagnosis-related studies, and summarized by the experts in the relevant area. Through this paper, we provide a comprehensive review on the recent trends and progress in fuel-cell-related research work in Korea.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 추계학술대회 논문집
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• pp.120-121
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• 2007

Nano-floating gate memory (NFGM) devices were fabricated by using the low temperature poly-Si thin films crystallized by ELA and the $In_2O_3$ nano-particles embedded in polyimide layers as charge storage. Memory effect due to the charging effects of $In_2O_3$ nano-particles in polyimide layer was observed from the TFT NFGM. The post-annealing in 3% diluted hydrogen $(H_2/N_2)$ ambient improved the retention characteristics of $In_2O_3$ nano-particles embedded poly-Si TFT NFGM by reducing the interfacial states as well as grain boundary trapping states.

• The Journal of Advanced Prosthodontics
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• 제8권2호
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• pp.94-100
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• 2016

PURPOSE. To evaluate the effects of hydrogen peroxide pretreatment and heat activation of silane on the shear bond strength of fiber-reinforced composite posts to resin cement. MATERIALS AND METHODS. The specimens were prepared to evaluate the bond strength of epoxy resin-based fiber posts (D.T. Light-Post) to dual-curing resin cement (RelyX U200). The specimens were divided into four groups (n=18) according to different surface treatments: group 1, no treatment; group 2, silanization; group 3, silanization after hydrogen peroxide etching; group 4, silanization with warm drying at $80^{\circ}C$ after hydrogen peroxide etching. After storage of the specimens in distilled water at $37^{\circ}C$ for 24 hours, the shear bond strength (in MPa) between the fiber post and resin cement was measured using a universal testing machine. The fractured surface of the fiber post was examined using scanning electron microscopy. Data were analyzed using one-way ANOVA and post-hoc analysis with Tukey's HSD test (${\alpha}=0.05$). RESULTS. Silanization of the fiber post (Group 2) significantly increased the bond strength in comparison with the non treated control (Group 1) (P<.05). Heat drying after silanization also significantly increased the bond strength (Group 3 and 4) (P<.05). However, no effect was determined for hydrogen peroxide etching before applying silane agent (Group 2 and 3) (P>.05). CONCLUSION. Fiber post silanization and subsequent heat treatment ($80^{\circ}C$) with warm air blower can be beneficial in clinical post cementation. However, hydrogen peroxide etching prior to silanization was not effective in this study.

• 한국구조물진단유지관리공학회 논문집
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• 제27권6호
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• pp.152-161
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• 2023

일반적으로 대용량의 수소를 저장하기 위해 사용되는 수직형 원통 용기는 강재로 제작되며, 사용 환경을 고려하여 제작된 받침 콘크리트 상부에 기초 슬래브에 선 설치된 앵커로 고정하는 방식이 사용된다. 이와 같은 방식은 지진과 같은 외력이 작용될 시 정착부에 응력이 집중될 수 있으며, 앵커 및 콘크리트 손상으로 인한 구조물의 전도 피해가 발생할 수 있다. 본 연구는 현장 조사를 통한 실제 운용중인 수직형 수소 저장용기를 특정하여 3차원 유한요소로 모델링하였고, 비 구조 요소의 내진 성능 검토에 사용되는 ICC - ES AC 156의 인공 지진 및 규모 5.0 이상의 국내 기록지진을 적용하여 거동 특성을 분석하였다. 실제 규모로 제작된 구조물을 대상으로 실험을 진행하는 것이 타당하지만 현실적 제약으로 수행하기에 어려움이 있어 해석적 접근 방식을 통하여 대상 구조물의 안전성을 검토하였다. 거동 특성의 경우 지진동에 의해 발생된 구조물의 응답 가속도는 검토되는 지진 하중 대비 평균적으로 10 배 이상 크게 증폭이 되는 것으로 나타났으며, 무게 중심이 위치되는 지점으로 전달될수록 감소되는 경향을 보였다. 취약 부위로 예상되는 하부 시스템(지지 기둥 및 앵커 정착부)의 경우 허용 응력을 만족하는 것으로 나타났지만, 정착을 위한 받침 콘크리트의 쪼갬 및 인장 강도는 허용 응력 대비 약 5 % 정도의 여유만이 있어 이에 대한 대처 방안이 요구된다. 본 논문에서 제시된 연구 결과를 바탕으로 향후 진동대 시험을 통하여 수행이 되는 수소저장 용기 제작에 필요한 설계 하중 및 조건 등의 기초자료로 활용될 수 있을 것으로 사료된다.