• 공업화학
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• 제22권1호
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• pp.114-118
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• 2011

미네랄 오일을 결합재로 사용하는 탄소반죽전극은 효소의 특성 연구 분야에서 효과적으로 활용되고 있으나 전극이 기계적 경도가 없으므로 실용화의 가능성은 없다. 본 실험실에서는 톨루엔에 녹인 고무 용액이 탄소가루의 결합재로 사용될 때 탄소반죽의 기계적 물성이 얻어지는 것을 확인하였다. 클로로프렌 고무 용액을 이용하여 만든 전극이 정량적인 전기화학적 행동을 보이는지 확인하기 위하여 여러 가지 속도론적 파라메터 즉 대칭인자($\alpha$, 0.28), 교환전류밀도 ($i_0$, $4.06{\mu}A/cm^2$), 이중층의 축전용량($C_d$, $2.11{\times}10^{-3}F$), Michaelis 상수($K_M$, $2.45{\times}10^{-3}M$), 시간상수(${\tau}_B$, 0.077 sec) 등을 구하였다. 이 실험적 사실들은 클로로프렌 고무가 탄소반죽전극의 실용화에 전망 좋은 결합재임을 입증하였다.

• 공업화학
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• 제22권5호
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• pp.518-521
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• 2011

전극면적 $25cm^2$ 고체고분자형 연료전지를 이용하여 수소극의 수분관리에 관한 연구를 진행하였다. 수분관리는 연료전지의 운전에 있어서 가장 핵심적인 인자 중의 하나이다. 본 연구에서는 연료극의 flooding의 위험성이 가장 높은 작동전류밀도 $200mA/cm^2$에서 수소극의 가습 및 온도 등의 운전조건의 변화, 그리고 유로 형상의 영향성을 평가하였다. 또한 연료극과 공기극의 양론비를 변화시킴과 동시에 유로의 형상에 따른 영향성을 파악하기 위한 실험을 실시하였다. 연료전지의 운전에 있어서 연료극과 공기극의 양론비에 따른 수분관리의 영향성을 확인할 수 있었고 또한 온도변화 및 가습조건의 변화에 따른 성능의 변화 역시 관찰할 수 있었다.

• International Journal of Computer Science & Network Security
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• 제22권3호
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• pp.37-44
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• 2022

Plug-in Hybrid electric vehicles (PHEV) show great potential to reduce gas emission, improve fuel efficiency and offer more driving range flexibility. Moreover, PHEV help to preserve the eco-system, climate changes and reduce the high demand for fossil fuels. To address this; some basic components and energy resources have been used, such as batteries and proton exchange membrane (PEM) fuel cells (FCs). However, the FC remains unsatisfactory in terms of power density and response. In light of the above, an electric storage system (ESS) seems to be a promising solution to resolve this issue, especially when it comes to the transient phase. In addition to the FC, a storage system made-up of an ultra-battery UB is proposed within this paper. The association of the FC and the UB lead to the so-called Fuel Cell Battery Electric Vehicle (FCBEV). The energy consumption model of a FCBEV has been built considering the power losses of the fuel cell, electric motor, the state of charge (SOC) of the battery, and brakes. To do so, the implementing a reinforcement-learning energy management strategy (EMS) has been carried out and the fuel cell efficiency has been optimized while minimizing the hydrogen fuel consummation per 100km. Within this paper the adopted approach over numerous driving cycles of the FCBEV has shown promising results.

• Current Photovoltaic Research
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• 제11권3호
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• pp.67-74
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• 2023

The earth-abundant element-based Cu₂ZnSn(S,Se)₄ (CZTSSe) thin film solar cells (TFSCs) have attracted greater attention in the photovoltaic (PV) community due to their rapid development in device power conversion efficiency (PCE) >13%. In the present work, we demonstrated the fine-tuning of the bandgap in the CZTSSe TFSCs by altering the sulfur (S) to the selenium (Se) chalcogenide ratio. To achieve this, the CZTSSe absorber layers are fabricated with different S/(S+Se) ratios from 0.02 to 0.08 of their weight percentage. Further compositional, morphological, and optoelectronic properties are studied using various characterization techniques. It is observed that the change in the S/(S+Se) ratios has minimal impact on the overall Cu/(Zn+Sn) composition ratio. In contrast, the S and Se content within the CZTSSe absorber layer gets altered with a change in the S/(S+Se) ratio. It also influences the overall absorber quality and gets worse at higher S/(S+Se). Furthermore, the device performance evaluated for similar CZTSSe TFSCs showed a linear increase and decrease in the open circuit voltage (V_oc) and short circuit current density (J_sc) of the device with an increasing S/(S+Se) ratio. The external quantum efficiency (EQE) measured also exhibited a linear blue shift in absorption edge, increasing the bandgap from 1.056 eV to 1.228 eV, respectively.

• Journal of Ceramic Processing Research
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• 제13권spc2호
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• pp.260-264
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• 2012

We have investigated the effect of ambient gases on the structural, electrical, and optical characteristics of IZO thin films intended for use as anode contacts in the organic light emitting diodes (OLED) devices. These IZO thin films were deposited on the PES film by radio frequency (RF) magnetron sputtering under different ambient gases (Ar, Ar + O2, and Ar + H2) at room temperature. In order to investigate the influences of the ambient gases, the flow rate of oxygen and hydrogen in argon has been changed from 0.1 sccm to 0.5 sccm, respectively. All the IZO thin film has an (222) preferential orientation regardless of ambient gases. The electrical resistivity of the IZO film increased with increasing O2 flow rate, whereas the electrical resistivity decreased sharply under an Ar + H2 atmosphere and was nearly similar regardless of the H2 flow rate. The change of electrical resistivity with changes in the ambient gas composition was mainly interpreted in terms of the charge carrier concentration rather than the charge carrier mobility. All the films showed the average transmittance over 85% in the visible range. The OLED device was fabricated with different IZO substrates made with the configuration of IZO/α-NPD/DPVB/Alq3/LiF/Al in order to elucidate the performance of the IZO substrate. The current density and the luminance of OLED devices with IZO thin films deposited in 0.5 sccm H2 ambient gas are the highest amongst all other films.

• 천문학회보
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• 제45권1호
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• pp.61.4-62
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• 2020

We present H I gas kinematics and star formation activities of NGC 6822, a dwarf galaxy located in the Local Volume at a distance of ~490 kpc. We perform profile decomposition of the line-of-sight velocity profiles of the high-resolution (~42.4" × 12") spatial; ~1.6 km/s spectral) H I data cube taken with the Australia Telescope Compact Array (ATCA). For this, we use a new tool, the so-called BAYGAUD (BAYesian GAUssian Decompositor) which is based on Bayesian Markov Chain Monte Carlo (MCMC) techniques, allowing us to decompose a line-of-sight velocity profile into an optimal number of Gaussian components in a quantitative manner. We classify the decomposed H I gas components of NGC 6822 into kinematically cold, warm or hot ones with respect to their velocity dispersion: 1) cold: < 4 km/s, 2) warm: 4 ~ 8 km/s, 3) hot: > 8 km/s. We then derive the Toomre-Q parameters of NGC 6822 using the kinematically decomposed H I gas maps. We also correlate their gas surface densities with the surface star formation rates derived using both GALEX far-ultraviolet and WISE 22 micron data to examine the impact of gas turbulence caused by stellar feedback on the Kennicutt-Schmidt (K-S) law. The kinematically cold component is likely to better follow the linear extension of the Kennicutt-Schmidt (K-S) law for molecular hydrogen (H2) at the low gas surface density regime where H I is not saturated.

• 한국재료학회지
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• 제33권10호
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• pp.377-384
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• 2023

Exploring earth-abundant, highly effective and stable electrocatalysts for electrochemical water splitting is urgent and essential to the development of hydrogen (H₂) energy technology. Iron-cobalt layered double hydroxide (FeCo-LDH) has been widely used as an electrocatalystfor OER due to its facile synthesis, tunable components, and low cost. However, LDH synthesized by the traditional hydrothermal method tends to easily agglomerate, resulting in an unstable structure that can change or dissolve in an alkaline solution. Therefore, studying the real active phase is highly significant in the design of electrochemical electrode materials. Here, metal-organic frameworks (MOFs) are used as template precursors to derive FeCo-LDH from different iron sources. Iron salts with different anions have a significant impact on the morphology and charge transfer properties of the resulting materials. FeCo-LDH synthesized from iron sulfate solution (FeCo-LDH-SO₄) exhibits a hybrid structure of nanosheets and nanowires, quite different from other electrocatalysts that were synthesized from iron chloride and iron nitrate solutions. The final FeCo-LDH-SO₄ had an overpotential of 247 mV with a low Tafel-slope of 60.6 mV dec^-1 at a current density of 10 mA cm^-2 and delivered a long-term stability of 40 h for the OER. This work provides an innovative and feasible strategy to construct efficient electrocatalysts.

• 한국분말재료학회지
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• 제31권1호
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• pp.43-49
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• 2024

In this study, a core-shell powder and sintered specimens using a mechanically alloyed (MAed) Ti-Mo powder fabricated through high-energy ball-milling are prepared. Analysis of sintering, microstructure, and mechanical properties confirms the applicability of the powder as a sputtering target material. To optimize the MAed Ti-Mo powder milling process, phase and elemental analyses of the powders are performed according to milling time. The results reveal that 20 h of milling time is the most suitable for the manufacturing process. Subsequently, the MAed Ti-Mo powder and MoO₃ powder are milled using a 3-D mixer and heat-treated for hydrogen reduction to manufacture the core-shell powder. The reduced core-shell powder is transformed to sintered specimens through molding and sintering at 1300 and 1400℃. The sintering properties are analyzed through X-ray diffraction and scanning electron microscopy for phase and porosity analyses. Moreover, the microstructure of the powder is investigated through optical microscopy and electron probe microstructure analysis. The Ti-Mo core-shell sintered specimen is found to possess high density, uniform microstructure, and excellent hardness properties. These results indicate that the Ti-Mo core-shell sintered specimen has excellent sintering properties and is suitable as a sputtering target material.

• 유기물자원화
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• 제17권2호
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• pp.101-111
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• 2009

본 연구에서는 강원지역의 도시 생활 쓰레기의 성상 및 물리 화학적 조성을 연구하였다. 생활 쓰레기 자원화시설 설치 및 자료확보 차원, 매립장 관리차원에서 본 연구는 필요한 연구이다. 폐기물의 평균 밀도는 $101.8{\sim}199.8kg/m^3$ 범위내의 결과를 얻었다. 생활 쓰레기는 30.7%의 음식물류, 36.3% 의 종이류, 15.８%의 플라스틱 및 비닐류, 1.9%의 섬유류, 3.2%의 목재류 1.５%의 고무 및 가죽류 등으로 구성되어 있다. 생활쓰레기의 대부분은 음식물, 종이류, 플라스틱류 등으로 이루어져 있으며 9０% 정도가 가연 성분이다. 삼성분 분석에서는 44.6%의 수분 및 47.4%의 가연분 그리고 7.7% 의 회분으로 이루어져 있었다. 원소분석결과는 탄소, 산소, 수소 순으로 많았다. 생활쓰레기의 저위 발열량은 2,631kcal/kg 이며 고위 발열량은 3,310 kcal/kg 이었다.

• 한국환경농학회지
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• 제5권1호
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• pp.1-10
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• 1986

제지(製紙)슬러지가 논 토양(土壤)의 화학성(化學性)에 미치는 영향(影響)을 검토(檢討)코자 슬러지를 600 ㎏/10a시용(施用)하여 pot시험(試驗)을 실시(實施)함으로써 토양중(土壤中) 유기물(有機物) 및 부식(腐植)의 형태변화(形態變化)와 부식산(腐植酸)의 자외부(紫外部) 및 가시부령역(可視部領域)에서의 흡수(吸收) spectra, infrared spectra 및 작용기함량(作用基含量)을 경시적(經時的)으로 조사(調査)한 결과(結果)는 다음과 같다. 1) 토양중(土壤中) ether 가용물질(可溶物質), resins, 수용성(水溶性) polysaccharides, hemicellulose, cellulose, ligno-protein, 부식산(腐植酸) 및 폴보산의 함량(含量)은 3요소구(要素區)에 비(比)하여 슬러지구(區)가 높았다. 2) 부식산(腐植酸)의 자외부(紫外部) 및 가시부령역(可視部領域)에서의 흡수(吸收) spectra는 모든 처리구(處理區)가 극대(極大)나 극소(極少)가 없는 일정(一定)한 흡수곡선(吸收曲線)을 나타내면서 파장(波長)이 길어질수록 optical density는 감소(減少)하는 경향(傾向)이었다. 부식산(腐植酸)의 작용기중(作用基中) phenolic-OH/alcoholic-OH는 슬러지구(區)가 3요소구(要素區)에 비(比)하여 약간 증가(增加)하는 경향(傾向)이었다. 부식산(腐植酸)의 형태(形態)는 모든 처리구(處理區)가 주로 P형(型) 및 Rp형(型)이었다. 3) 부식산(腐植酸)의 infrared spectra의 공통적(共通的)인 주요(主要) 흡수(吸收) band는 $3,400cm^{-1}$, $2,900cm^{-1}$, $1,600cm^{-1}$ 및 $1,050cm^{-1}$부근(附近)이었으며 $3,400cm^{-1}$부근(附近)의 넓은 흡수(吸收) band는 hydrogen-bonded OH에 기인(基因)되었고 $2,900cm^{-1}$부근(附近)의 흡수(吸收)는 aliphatic C-H stretching에 의한 것이었으며 $1,630cm^{-1}$부근(附近)의 흡수(吸收)는 aromatic C=C외에 hydrogen-bonded C=O로 추측(推測)되었으며 $1,050cm^{-1}$부근(附近)의 강(强)한 흡수(吸收) band는 규산(珪酸) 부순물(不純物)의 Si-O결합(結合)에 기인(基因)된 것으로 해석(解釋)되었다.