• 한국진공학회지
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• 제17권4호
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• pp.253-261
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• 2008

Programmable metalization cell (PMC) memory 소자로도 명명되는 고체 전해질 메모리 소자는 비휘발성, 고속 및 높은 ON/OFF 저항비 등을 갖고 있기 때문에, 차세대 비휘발성 메모리로서 각광받고 있는 소자 중의 하나이다. 본 논문에서는 고체 전해질 메모리 소자의 동작 원리를 먼저 소개하고자 한다. 또한, 메모리향 소자 개발을 진행 중인 미국 코지키 교수 그룹, 비메모리향 소자 개발을 진행 중인 일본 NEC 그룹 등의 해외 연구진과, Te 계열의 칼코게나이드 합금을 채택하여 소자를 제작한 한국전자통신연구원 및 충남대학교 등의 국내 연구진의 연구 성과를 소개하고자 한다.

• 한국세라믹학회지
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• 제53권5호
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• pp.511-520
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• 2016

Electrolyte-supported symmetric Ni-YSZ cermet electrodes of ca. $23{\mu}m$ were prepared by screenprinting and the impedance was measured as a function of humidity from 2% to 90% balanced in $H_2$ at a total flow rate of 50 sccm. The Ni felt current collector of 1 mm thickness exhibited a Gerischer-like gas concentration impedance in the low frequency range, which was similarly observed in the cermet-supported solid oxide cells, while the Pt paste collector exhibited only electrochemical polarization. The electrochemical polarization of both samples was modeled by a non-ideal diffusion-reaction transmission line model including CPEs with ${\alpha}$= 0.5. In the case of the Pt paste collector, all the Bisquert parameters exhibited humidity dependence to the -1/2 power, supporting a non-faradaic chemical reaction mechanism at three phase boundaries. Consequently, the surface diffusivity and reaction rate increased linearly with humidity. Less pronounced humidity dependence and somewhat lower utilization length with an Ni felt collector can be attributed to the diffusion-limited gas flow through the collector.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 추계학술대회 논문집
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• pp.575-578
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• 2000

In this work, all solid-state thin film supercapacitor(TFSC) was fabricated using tungsten trioxide (WO$_3$) with a structure WO$_3$/LiPON/WO$_3$/Pt/TiO$_2$/Si (substrate). After TiO$_2$ was deposited on Si(100) wafer by d.c. reactive sputtering, the Pt current collector films were grown on TiO$_2$glue layer without breaking vacuum by d.c. sputtering. Fabrication conditions of WO$_3$ thin film were such that substrate temperature, working pressure, gas ratio of $O_2$/Ar and r.f. power were room temperature, 5 mTorr, 20% (O$_2$(8sccm)/Ar(32sccm)) and 200W, respectively. LiPON electrolyte film were grown on the WO$_3$ film using r.f. magnetron sputtering at room temperature. The XRD pattern of the as-deposited WO$_3$ thin film were shown no crystalline peak (amorphous). The SEM image of as-deposited WO$_3$ thin film showed that the surface is smooth and uniform. The capacitiy of as-fabricated TFSC was 0$\times$10$^{-2}$ F/$\textrm{cm}^2$-${\mu}{\textrm}{m}$.

• 한국전기전자재료학회논문지
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• 제27권8호
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• pp.491-496
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• 2014

The resistive switching characteristics of resistive random access memory (ReRAM) based on amorphous $Ge_{0.5}Se_{0.5}$ thin films have been demonstrated by using Ti/Ag nanocrystals/$Ge_{0.5}Se_{0.5}$/Pt structure. Ag nanocrystals (Ag NCs) were spread on the amorphous $Ge_{0.5}Se_{0.5}$ thin film and they played the role of metal ions source. As a result, comparing the conventional Ag/$Ge_{0.5}Se_{0.5}$/Pt structure, this Ti/Ag NCs/$Ge_{0.5}Se_{0.5}$/Pt ReRAM device exhibits the highly uniform bipolar resistive switching (BRS) characteristics, such as the operating voltages, and the resistance values. At the same time, a stable DC endurance(> 100 cycles), and the excellent data retention (> $10^4$ sec) properties were found from the Ti/Ag NCs/$Ge_{0.5}Se_{0.5}$/Pt structured ReRAM device.

• 센서학회지
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• 제17권5호
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• pp.329-337
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• 2008

Simple, small and portable oxygen sensors were fabricated by tape casting technique. Yttria stabilized zirconia containing cordierite ceramics (YSZC) were used as a porous diffused layer of oxygen in pumping cell. Yttria stabilized zirconia (YSZ) solid electrolyte, YSZC porous diffusion layer and heater-patterned ceramic sheets were prepared by co- firing method. Limit current characteristics and the linear relationship of current to oxygen concentration were observed. Viscosity variation of the slurries both YSZ and YSZC showed a similar behavior, but micro pores in the fired sheet were increased with increasing of the cordierite amount. Molecular diffusion was dominated due to the formation of large pores in porous diffusion layer. The plateau range of limit current in porous-type oxygen sensor was narrow than the one of aperture-type oxygen sensor. However limit current curve was appeared in porous-type oxygen sensor even at the lower applied voltage. The plateau range of limit-current was widen as increasing the thickness of porous diffusion layer of the YSZ containing cordierite. Measuring temperature of $600{\sim}650^{\circ}C$ was recommended for limit-current oxygen sensor. Porous diffusion layer-type oxygen sensor showed faster response than the aperture-type one and was stable up to 30 days running without any crack at interface between the layers.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.2
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• pp.934-937
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• 2003

Glasses in the system $CuO-P_2O_5-V_2O_5$ were prepared by a press-quenching method on the copper plate. The glass-ceramics from these glasses were obtained by post-heat treatment, and the crystallization behavior and DC conductivities were determined. The conductivities of the glasses were range from $10^{-6}s.Cm^{-1}$ at room temperature, but the conductivities of the glass-ceramics were $10^{-3}s.Cm^{-1}$ increased by $10^3$ order. The crystalline product in the glass-ceramics was $CuV_2O_6$. Heat-treatment conditions influenced the crystal growth of $CuV_2O_6$ and conductivity. The linear relationship between in (${\sigma}T$) and $T^{-1}$ suggested that the electrical conduction in the present glass-ceramics would be due to a small polaron hopping(SPH) mechanism.

• 한국광학회지
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• 제1권1호
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• pp.73-86
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• 1990

The technique of Spectroscopic Ellipsometry (SE) has been examined with emphasis on its inherent sensitivity to the existence of thin films or surface equivalents. A brief review of related theories like the Fresnel reflection coefficients, the effect of a multilayer upon reflectivities, together with the validity of the effective medium theory and the modelling procedure, is followed by a short description of the experimental setup of a rotating polarizer type SE as well as the necessful expressions which lead to tan and cos. Out of its numerous, successful applications, a few are exampled to convince a reader that SE can be applied to a variety of research fields related to surface, interface and thin films. Specifically, those are adsorption and/or desorption on metals or semiconductors, oxidation process, formation of passivation layers on an electrode, thickness determination, interface between semiconductor and its oxide, semiconductor heterojunctions, surface microroughness, void distribution of dielectric, optical thin films, depth profile of multilayered samples, in-situ or in-vitro characterization of a solid surface immersed in electrolyte during electrochemical, chemical, or biological treatments, and so on. It is expected that the potential capability of SE will be widely utilized in a very near future, taking advantage of its sensitivity to thin films or surface equivalents, and its nondestructive, nonperturbing characteristics.

• Composites Research
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• 제31권6호
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• pp.355-364
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• 2018

Flexible energy-storage devices (FESDs) have been studied and developed extensively over the last few years because of demands in various fields. Since electrochemical performance and mechanical flexibility must be taken into account together, different framework from composition of conventional energy-storage devices (ESDs) is required. Numerous types of electrodes have been proposed to implement the FESDs. Herein, we review the works related to the FESDs so far and focus on free-standing electrodes and, especially substrate-based ones. The way to utilize carbon woven fabric (CF) or carbon cloth (CC) as flexible substrates is quite simple and intuitive. However, it is meaningful in the point of that the framework exploiting CF or CC can be extended to other applications resulting in multifunctional composites. Therefore, summary, which is on utilization of carbon-based material and conductive substrate containing CF and CC for ESDs, turns out to be helpful for other researchers to have crude concepts to get into energy-storage multi-functional composite. Moreover, polymer electrolytes are briefly explored as well because safety is one of the most important issues in FESDs and the electrolyte part mainly includes difficult obstacles to overcome. Lastly, we suggest some points that need to be further improved and studied for FESDs.

• 한국안전학회지
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• 제37권2호
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• pp.76-87
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• 2022

Lithium-ion batteries (LIBs) have attracted much interest for their high energy density (>150 mAh/g), high capacity, low self-discharge rate, and high coulombic efficiency. However, with the successful commercialization of LIBs, fire and explosion incidents are likely to increase. The thermal runaway is known as the major factor in battery-related accidents that can lead to a series of critical conditions. Considering this, recent studies have shown an increased interest in countering the safety issues associated with LIBs. Although safety standards for LIB use have recently been formulated, little attention has been paid to the safety around the manufacturing process for battery products. The present study introduces a risk assessment method suitable for assessing the safety of the LIB-manufacturing process. In the assessment method, a compensation parameter (Z-factor) is employed to correctly evaluate the process's safety on the basis of the type of material (e.g., metal anode, liquid electrolyte, solid-state electrolytes) utilized in a cell. The proposed method has been applied to an 18650 cell-manufacturing process, and three sub-processes have been identified as possibly vulnerable parts (risk index: >4). This study offers some crucial insights into the establishment of safety standards for battery-manufacturing processes.

• 한국수소및신에너지학회논문집
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• 제35권3호
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• pp.257-268
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• 2024

Hydrogen serves as a clean energy source with potential applications across various sectors including electricity, transportation, and industry. In terms of policy and economic support, governmental policy backing and economic incentives are poised to accelerate the commercialization and expansion of hydrogen energy technologies. Hydrogen energy is set to become a cornerstone for a sustainable future energy system. Additionally, when constructing hydrogen production plants, economic aspects must be considered. The essence of hydrogen production plants lies in the electrolysis of water, a process that separates water into hydrogen and oxygen using electrical energy. The initial capital expenditure (CAPEX) for hydrogen production plants can vary depending on the electrolysis technology employed. This study aims to provide a comprehensive understanding of hydrogen production technologies as well as to propose a method for predicting the CAPEX of hydrogen production plants.