• 자원리싸이클링
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• 제16권6호
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• pp.52-60
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• 2007

탈질 특허분석과 전해기초연구를 통하여 수용액으로부터 질소의 환원제거에 대하여 조사하였다. 세계적으로 수용액으로부터 질소를 제거하는 방법으로 생물학적 기술과 산화환원 기술이 개발되고 있으며, 최근 들어 전해기술에 대한 특허출원도 증가하고 있다. 전해법에서 Fe를 음극으로 Pt를 양극으로 채택한 정전류 전해법에 의하여 1시간동안 총질소를 47% 이상 제거할 수 있었다. 질소함유 폐수를 처리하는 효율적인 방법은 폐수 특성에 맞는 기술의 조합이라고 말할 수 있다. 예를 들어 고농도 질소 함유 폐수를 소량 배출하는 경우 화학적 처리와 전해법의 조합으로 질산성 질소를 아질산성 질소로 일차 전환시켜 전해효율을 극대화시키면서 2차 오염원인 용해 금속이온을 전해과정에서 음극에 환원 회수하는 방법 등이 실용화에 유리하다고 말할 수 있다.

• 자원리싸이클링
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• 제18권3호
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• pp.62-68
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• 2009

마그네슘 용융염 전해시 적정 조업조건을 확립하고자 자체 설계 제작한 150A급 mono-polar형 전해조를 사용하여 24시간 연속 전해 조업을 수행하였다. $MgCl_2$ 25%, NaCl 55%, $CaCl_2$ 19%, $CaF_2$ 1%의 전해욕 조성으로 전해온도 $720{\sim}740^{\circ}C$, 전해전압 7V, 음극 전류 밀도 $0.7-0.75A/cm^2$, 전극 간격 6cm의 운전조건에서 24시간 연속 조업을 수행하였으며, 전해 전압 및 전류 변화, 전해 욕 조성 변화, 전류 효율 등을 조사하였다. 시험결과 제작한 전해셀의 조업성이 양호하였으며, 순도 99% 이상의 금속 마그네슘을 회수하였고 전류효율 89%를 달성할 수 있었다. 본 연구를 통하여 마그네슘 용융염 전해장치 제작에 필요한 기초자료를 축적할 수 있었다.

• 분석과학
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• 제11권1호
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• pp.1-7
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• 1998

본 논문은 현장에서 미량 원소분석을 수행할 수 있는 휴대용 원자방출분광계인 HCGD-AES(Hollow Cathode Glow Discharge-Atomic Emission Spectrometer)1에 적용할 분석 및 제어용 프로그램의 제작에 관한 연구결과를 요약하였다. 단색화 장치의 부피를 최소화할 수 있도록 분석할 원소의 선 필터(line filter)를 사용하여 제작된 검출계에서 실시간 분석이 가능한 소프트웨어의 개발이 이루어 졌으며, 원소 분석 및 검량선 작성의 자동화를 바탕으로 쉽게 사용할 수 있는 노트북용 소프트웨어를 Windows 95 환경에서 구현하였다. 사용한 주 언어인 Delphi 2.0을 바탕으로 그밖의 프로그램 언어도 복합적으로 사용되었다. 특히 측정된 자료들은 데이터 베이스를 구축하여 최적 실험 환경 조건을 얻을 수 있도록 하였으며 보고서 작성 기능도 추가되었다. 본 프로그램은 분석 수행에 있어서 사용자 편의를 위해 디자인되었으므로 빠르게 배우고 분광분석의 다른 분야에도 적용할 수 있도록 개발되어 응용성과 활용성이 대폭 확대될 수 있다는 이점이 있다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.475-475
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• 2010

We have generated Ar plasma in dense plasma focus device with coaxial electrodes for extreme ultraviolet (EUV) lithography and investigated an emitted visible light for electro-optical plasma diagnostics. We have applied an input voltage 4.5 kV to the capacitor bank of 1.53 uF and the diode chamber has been filled with Ar gas of pressure 8 mTorr. The inner surface of the cylindrical cathode has been attatched by an acetal insulator. Also, the anode made of tin metal. If we assumed that the focused plasma regions satisfy the local thermodynamic equilibrium (LTE) conditions, the electron temperature and density of the coaxial plasma focus could be obtained by Stark broadening of optical emission spectroscopy (OES). The Lorentzian profile for emission lines of Ar I of 426.629 nm and Ar II of 487.99 nm were measured with a visible monochromator. And the electron density has been estimated by FWHM (Full Width Half Maximum) of its profile. To find the exact value of FWHM, we observed the instrument line broadening of the monochromator with a Hg-Ar reference lamp. The electron temperature has been calculated using the two relative electron density ratios of the Stark profiles. In case of electron density, it has been observed by the Stark broadening method. This experiment result shows the temporal behavior of the electron temperature and density characteristics for the focused plasma. The EUV emission signal whose wavelength is about 6 ~ 16 nm has been detected by using a photo-detector (AXUV-100 Zr/C, IRD). The result compared the electron temperature and density with the temporal EUV signal. The electron density and temperature were observed to be $10^{16}\;cm^{-3}$ and 20 ~ 30 eV, respectively.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.237.2-237.2
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• 2013

ReRAM cell, also known as conductive bridging RAM (CBRAM), is a resistive switching memory based on non-volatile formation and dissolution of conductive filament in a solid electrolyte [1,2]. Especially, Chalcogenide-based ReRAM have become a promising candidate due to the simple structure, high density and low power operation than other types of ReRAM but the uniformity of switching parameter is undesirable. It is because diffusion of ions from anode to cathode in solid electrolyte layer is random [3]. That is to say, the formation of conductive filament is not go through the same paths in each switching cycle which is one of the major obstacles for performance improvement of ReRAM devices. Therefore, to control of nonuniform conductive filament formation is a key point to achieve a high performance ReRAM. In this paper, we demonstrated the enhanced repeatable bipolar resistive switching memory characteristics by spreading the Ag nanocrystals (Ag NCs) on amorphous GeSe layer compared to the conventional Ag/GeSe/Pt structure without Ag NCs. The Ag NCs and Ag top electrode act as a metal supply source of our devices. Excellent resistive switching memory characteristics were obtained and improvement of voltage distribution was achieved from the Al/Ag NCs/GeSe/Pt structure. At the same time, a stable DC endurance (>100 cycles) and an excellent data retention (>104 sec) properties was found from the Al/Ag NCs/GeSe/ Pt structured ReRAMs.

• 대한금속재료학회지
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• 제48권7호
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• pp.667-673
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• 2010

Copper filling into TSV (through-silicon-via) and reduction of the filling time for the three dimensional chip stacking were investigated in this study. A Si wafer with straight vias - $30\;{\mu}m$ in diameter and $60\;{\mu}m$ in depth with $200\;{\mu}m$ pitch - where the vias were drilled by DRIE (Deep Reactive Ion Etching) process, was prepared as a substrate. $SiO_2$, Ti and Au layers were coated as functional layers on the via wall. In order to reduce the time required complete the Cu filling into the TSV, the PPR (periodic pulse reverse) wave current was applied to the cathode of a Si chip during electroplating, and the PR (pulse-reverse) wave current was also applied for a comparison. The experimental results showed 100% filling rate into the TSV in one hour was achieved by the PPR electroplating process. At the interface between the Cu filling and Ti/ Au functional layers, no defect, such as a void, was found. Meanwhile, the electroplating by the PR current showed maximum 43% filling ratio into the TSV in an hour. The applied PPR wave form was confirmed to be effective to fill the TSV in a short time.

• Journal of Electrochemical Science and Technology
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• 제14권1호
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• pp.75-84
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• 2023

The accumulation of spent carbide (YG8), not only pollutes the environment but also causes waste of tungsten, cobalt and other rare metal resources. To better address this issue, we proposed a combined electrochemical separation process of low-temperature aqueous solution and high-temperature molten salt for tungsten and cobalt. H₂WO₄ was obtained from spent carbide in an aqueous solution, and we calcined it to obtain WO₃, which was used as a raw material to obtain tungsten by using molten salt electrodeposition. The influence of the current efficiency and the electrochemical behavior of the discharge precipitation of W(VI) were also studied. The calcination results showed that the morphology of WO₃ was regular and there were no other impurities. The maximum current efficiency of 82.91% was achieved in a series of electrodeposition experiments. According to XRD and SEM analysis, the recovered product was high purity tungsten, which belongs to the simple cubic crystal system. In the W(VI) reduction mechanism experiments, the electrochemical process of W(VI) in NaCl-Na₂WO₄-WO₃ molten salt was investigated using linear scanning voltammetry (LSV) and chronoamperometry in a three-electrode system. The LSV showed that W(VI) was reduced at the cathode in two steps and the electrode reaction was controlled by diffusion. The fitting results of chronoamperometry showed that the nucleation mechanism of W(VI) was an instantaneous nucleation mode, and the diffusion coefficient was 7.379×10^-10 cm²·s^-1.

• Journal of Electrochemical Science and Technology
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• 제15권1호
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• pp.198-206
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• 2024

Given the high theoretical capacity (1,675 mAh g^-1) and the inherent affordability and ubiquity of elemental sulfur, it stands out as a prominent cathode material for advanced lithium metal batteries. Traditionally, sulfur was sequestered within conductive porous carbons, rooted in the understanding that their inherent conductivity could offset sulfur's non-conductive nature. This study, however, pivots toward a transformative approach by utilizing diatom shell (DS, diatomite)-a naturally abundant and economically viable siliceous mineral-as a sulfur host. This approach enabled the development of a sulfurlayered diatomite/S composite (DS/S) for cathodic applications. Even in the face of the insulating nature of both diatomite and sulfur, the DS/S composite displayed vigorous participation in the electrochemical conversion process. Furthermore, this composite substantially curbed the loss of soluble polysulfides and minimized structural wear during cycling. As a testament to its efficacy, our Li-S battery, integrating this composite, exhibited an excellent cycling performance: a specific capacity of 732 mAh g^-1 after 100 cycles and a robust 77% capacity retention. These findings challenge the erstwhile conviction of requiring a conductive host for sulfur. Owing to diatomite's hierarchical porous architecture, eco-friendliness, and accessibility, the DS/S electrode boasts optimal sulfur utilization, elevated specific capacity, enhanced rate capabilities at intensified C rates, and steadfast cycling stability that underscore its vast commercial promise.

• 한국안전학회지
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• 제39권2호
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• pp.38-43
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• 2024

Recently, with the expanding market for electronic devices and electric vehicles, secondary battery usage has been on the rise. Lithium-ion batteries are particularly popular due to their fast charging times and lightweight nature compared to other types of batteries. A secondary battery consists of four components: anode, cathode, electrolyte, and separator. Generally, the positive and negative electrode materials of secondary batteries are composed of an active material, a binder, and a conductive material. Acetylene Black (AB) is utilized to enhance conductivity between active material particles or metal dust collectors, preventing the binder from acting as an insulator. However, when recycling waste batteries that have been subject to high usage, there is a risk of fire and explosion accidents, as accurately identifying the characteristics of Acetylene Black dust proves to be challenging. In this study, the lower explosion limit for Acetylene Black dust with an average particle size of 0.042 ㎛ was determined to be 153.64 mg/L using a Hartmann-type dust explosion device. Notably, the dust did not explode at values below 168 mg, rendering the lower explosion limit calculation unfeasible. Analysis of explosion delay times with varying electrode gaps revealed the shortest delay time at 3 mm, with a noticeable increase in delay times for gaps of 4 mm or greater. The findings offer fundamental data for fire and explosion prevention measures in Acetylene Black waste recycling processes via a predictive model for lower explosion limits and ignition delay time.

• 전기화학회지
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• 제8권4호
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• pp.172-176
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• 2005

차세대 5V급 양극활물질로 각광받고 있는 $LiNi_{0.5}Mn_{1.5}O_4$는 기존의 $LiMn_2O_4$ spinel 물질의 $Mn^{3+}$을 $Ni^{2+}$으로 치환하여 5V 영역에서 $Ni^{2+}/Ni^{4+}$ 산화/환원 반응이 가능하게 한 물질이다. 기존의 $LiMn_2O_4$는 낮은 초기 용량과 충 방전에 따른 빠른 용량감소를 보이는 단점을 가지고 있어 이 문제를 극복하기 위해 Mn의 일부를 다른 금속으로 치환하여 $LiM_yMn_{2-y}O_4$ (M=Cr, Al, Ni, Fe, Co, Cu, Ca)을 만드는 방법이 활발히 연구되고 있다. 본 연구에서는 기계 화학적 합성법을 이용하여 합성한 $LiNi_{0.5}Mn_{1.5}O_4$의 전기화학적 특성에 대해 연구하였다. 이 물질은 기존의 $LiMn_2O_4$보다 에너지 밀도가 높으며 저가 및 친환경성 등으로 앞으로 HEV 등에서 그 활용성이 크게 기대된다. 볼밀을 이용하여 여러가지 조건(출발물질 조건, 볼밀조건, 열처리조건 등)에서 $LiNi_{0.5}Mn_{1.5}O_4$을 합성한 결과 기계화학적 방법으로는 $Ni^{2+}$가 $Mn^{3+}$를 완전히 치환하지 못하여 $4.0{\sim}4.1V$의 전압에서 $Mn^{3+}/Mn^{4+}$의 산화/환원과 관련된 peak가 발생하였다. Ni 원료 물질로써 수산화 물질을 사용하고 열처리 온도를 $800^{\circ}C$로 하였을 때 최상의 성능을 나타내었다.