• Resources Recycling
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• v.23 no.2
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• pp.3-16
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• 2014

Car exhaust $CO_2$ gas reduction and fuel efficiency of the car lighter for the current era is a big challenge. The developments of high-performance Nd magnets, Li-ion secondary battery and exhaust gas purification performance of PGM catalysts used in the lightweight EV and HEV are activated. Country in order to improve the car lighter and function that use the resources of rare metals are ubiquitous imported from China because of export supply control, as soaring prices have unstable supply and demand. Compared to the emissions from the next-generation automotive recycling, waste scarce resources need to be. This study investigated the recycling technology analysis and development of the information technology, or delivered to the researchers by giving national car industry aims to contribute to the development. Findings, pulmonary high-performance motor vehicle emissions in the exhaust gas purification PGM Catalysts, Li-ion battery and Nd magnets recycling technology, such as pre- and post-processing techniques to classify technology, pre-urban mining technology mechanical separation by screening techniques under development, the study and post-processing technology has, pyro and hydro metallurgical smelting technology is established. Waste Recycling in terms of economic efficiency of mechanical components for the intensive study of screening techniques is needed.

• Resources Recycling
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• v.23 no.1
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• pp.17-24
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• 2014

Solvent extraction experiments have been performed to separate Nd and Pr from chloride leaching solution of monazite sand using PC88A and D2EHPA. For this purpose, the effect of the saponification of PC88A and D2EHPA on the extraction and separation of the two metals were studied by varying the pH of aqueous solution. In the experimental ranges conducted in this study, the distribution coefficients of Nd were higher than those of Pr and separation factor value increased with the increase of solution pH. Saponification of PC88A enhanced the distribution coefficients of Nd and Pr as well as the separation factor. Saponification of D2EHPA had some effect on the extraction of the two metals but little effect on the separation factor.

• Applied Chemistry for Engineering
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• v.17 no.4
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• pp.369-374
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• 2006

$Rh-Pt/Al_{2}O_{3}$ catalysts were used for the first time to study its reaction characteristics in the asymmetric hydrogenation of ethyl pyruvate. The catalysts were prepared either by impregnation of Rh on a commercial $Pt/Al_{2}O_{3}$ or by sequential impregnation of Rh followed by impregnation of Pt on $Al_{2}O_{3}$. Reaction rate and enantiomeric excess (ee%) were compared according to the preparation method, Rh contents, and the reduction temperature of the catalyst. The physical characteristics of the catalysts were analyzed using XRD and TEM. Bimetallic $Rh-Pt/Al_{2}O_{3}$ catalysts showed an improved reaction rate and optical purity (63.6 ee%) with increasing the reduction temperature. The variation of the Rh contents as well as the preparation method elicited a big difference on the reaction rate, while enantiomeric excess (ee%) was lower (56~60%) with all bimetallic catalysts than with monometallic $Pt/Al_{2}O_{3}$ catalyst.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.11
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• pp.84-91
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• 2006

Recently, all the electrical parts for satellite application are required more strong against cosmic rays, because spacecraft's life time and function are depending on the their conditions. Also, a TID effect test was undertaken with units and/or subsystems which are already assembled on the PCB in past time. However, it is very hard to know and analyze that some abnormal states are appeared after launch. Moreover, it is necessary to perform a test of TID effects based on the parts level for preparing preliminary data in cosmic rays. Therefore, this paper presents a test-bed to perform a TID effect test of Metal-Oxide Semiconductor Field Effect Transistor (MOSFET) which is a fundamental element for electronics.

• Applied Chemistry for Engineering
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• v.5 no.6
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• pp.925-934
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• 1994

Nickel recovered from the spent oil-hydrogenation catalysts was used in hydrogenation catalyst preparation. The spent catalyst contains approximately 21.8% Ni, 0.7% Mg, and small quantities of Al, Fe, and Zn. Nickel recovery was obtained by inorganic acid digestion in the order of HCI>$NHO_3$>$H_2SO_4$. For $HNO_3$, 3hour extraction with 3N solution was satisfactory. In the PH range of 6.5~9.0, Ni recovery was higher, but metallic impurities were found to be coprecipitated. The PH in the range of 7.0~9.0 seems to be the optimum condition for separation to obtain acceptable Ni precipitates without the decrease of purity. The catalysts prepared with reclaimed nickel by wet reduction methods showed catalytic activities close to those prepared using reagent nickel in the oil hydrogenation reaction. The surface areas of the support do not seem to affect the catalytic activity.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.260-260
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• 2012

최근 IT산업의 급속한 발달로 모바일 제품과 반도체 및 IC 패키지 등의 전자제품의 소형화, 경량화 및 고성능화되어 가고 있다. 따라서 반도체 공정에서 단위소자의 고속화를 구현하기 위한 금속배선공정에 사용되는 금속재료가 최근에 최소 선폭을 갖는 디바이스에서는 구리를 배선 재료로 전환하고, 향후에는 모든 디바이스가 구리를 주요 배선재료로 사용할 것으로 예측되고 있다. 반도체 소자 공정 중 시료 표면 위에 형성되는 오염물은 파티클, 유기오염물, 금속 불순물 그리고 자연 산화막으로 나눌 수 있다. 구리 표면에 생성되는 부식생성물의 종류에는 CuO, $Cu_2O$, $Cu(OH)_2$, $CuCO_3{\cdot}Cu(OH)_2$와 같은 생성물들이 있다. 이러한 부식생성물이 구리박막 표면에 형성이 되면 성장된 구리박막의 특성을 저하시키게 된다. 이러한 다양한 오염물들을 제거하기 위해서 여러 가지 전처리 공정에 대한 연구가 보고되고 있다. 본 연구에서, 스퍼터 방식으로 구리를 증착한 웨이퍼 (Cu/Ti/Si) 를 대기 중에 노출시켜 자연 산화막을 성장시키고, 이 산화막과 대기로부터 흡착된 불순물을 제거하기 위해 계면 활성제인 TS-40A와 $NH_4OH$ 수용액을 사용하여 이들 수용액이 구리 표면층에 미치는 영향에 대해 조사 분석하였다. 사용된 TS-40A는 알칼리 탈지제로서 웨이퍼 표면의 유기물을 제거하는 역할을 하며, $NH_4OH$는 구리를 제거하는 부식액으로 산업현장에서 널리 사용되고 있다. 다양한 표면 전처리 조건에 따른 구리박막 표면의 형상 및 미시적 특성변화를 SEM과 AFM을 이용하여 관찰하였고, 표면의 화학구조 및 성분 변화를 관찰하기 위해 XPS를 측정하였으며, 전기적 특성변화를 관찰하기 위해 4-point prove를 사용하여 박막의 면저항을 측정하였다.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.322-322
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• 2013

최근 전자제품들의 소형화, 경량화, 다기능화가 활발히 진행됨에 따라, 고성능의 고출력용 인쇄회로기판(PCB)의 개발이 요구되고 있다. PCB는 전자제품의 각 부품을 전기적으로 연결하는 통로로서 전자제품의 소형화, 다기능화에 따라 고집적화가 요구되고 있다. 하지만 모든 전자장비의 고장의 85% 정도가 발열에 의한 것으로, PCB의 고집적화에 따른 발열문제가 매우 중요한 이슈가 되고 있다. 최근에는 이러한 문제점을 해결하기 위해 PCB의 방열층으로 양극 산화막을 금속 기판 위에 형성하고 이 절연층 위에 금속층을 회로로서 형성하는 방열 PCB 기판에 대한 연구가 활발히 진행되고 있다. 최근까지, 금속층 회로 형성을 위해 무전해 Ni 도금에 대한 연구가 활발히 이루어져 왔다. 하지만 주로 화학적, 전기화학적 관점에서 많은 연구자들에 의해 조사 연구되어 왔다. 본 실험에서는 anodized Al 절연층 위의 회로전극 부분으로 스크린 방법으로 Ag paste를 패턴 인쇄한 뒤, 무전해도금 방식으로 저렴한 Ni 전면 회로전극을 형성하여 전기전도도를 높이고, 저항을 낮출 수 있는 회로로서 기판의 손상을 최소화하고 선택적으로 Ag 패턴에만 Ni 전극회로를 형성시키는 것을 목표로 연구하였다. Ni-B 무전해 도금시 도금조의 온도는 $65^{\circ}C$, 무전해 도금액의 pH는 ~7 (중성)로 유지하였다. Al2O3 기판을 이용한 Ag Paste 패턴 위에 증착된 Ni-B 박막의 특성을 분석하기 위해 X-ray diffraction (XRD), AFM (Atomic Force Microscopy), SEM (Scanning Electron Microscope), XPS (X-ray Photoelectron Spectroscopy)을 이용하여 Ni-B 박막의 특성을 분석하였다.

• Journal of the Korean Chemical Society
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• v.66 no.6
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• pp.442-450
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• 2022

Diverse pyrrolo[3,2-d]pyrimidines that are expected to exhibit bioactivity were synthesized through O-arylation and Suzuki coupling reactions. Microwave-assisted O-arylation was successfully performed using a Cu metal catalyst, so that 4 position of pyrrolo[3,2-d]pyrimidine could be substituted with phenol group. In addition, 4-aryl substituted pyrrolo[3,2-d]pyrimidines were synthesized with good to excellent yields by microwave-assisted Suzuki coupling reaction using a Pd metal catalyst. By using microwaves as reaction conditions for diversification of derivatives, it was possible to dramatically overcome the disadvantages of traditional heat reactions of long reaction times and heat transfer efficiency problems. The result of this study can be used to be diversify pyrrolo[3,2-d]pyrimidine derivatives, which are expected to play an important role in the drug discovery research.

• Korean Journal of Food Science and Technology
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• v.29 no.2
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• pp.320-325
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• 1997

Transglucosidase (TG) from Aspergillus niger was immobilized on various carriers by several immobilization methods such as ionic binding, adsorption, entrapment, covalent linkage and metal chelation to improve the process performance. The covalent linkage with CNBr-activated sepharose 4B was found as the best method for immobilization of TG based on the immobilization yield which was 61.3%. The immobilization through ionic binding and adsorption gave 33.1% and 22.5% yield respectively but both methods were not selected due to lower yield than covalent linkage using CNBr-Sepharose 4B. Internal diffusion resistance in beads developed by entrapment were not suitable factor in producing final target products. Covalent linkage of TG on magnesium silicate, silica gel and glass bead and metal chelation method didn't result in higher yield than the selected one, either.

• Korean Chemical Engineering Research
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• v.57 no.4
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• pp.455-460
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• 2019

Hydrotreating catalysis refers to a various hydrogenation which saturate an unsaturated hydrocarbon, together with removing heteroatoms such as sulfur, nitrogen, oxygen, and trace metals from different petroleum streams in a refinery. Most refineries include at least three hydrotreating units for upgrading naphtha, middle distillates, gas oils, intermediate process streams, and/or residue. Among them, hydrotreating catalysis for residue are the core of the process, because of its complexity. This article reviews recent progress in tackling the issues found in the upgrading residues by hydrotreating, focusing on the chemistry of hydrodemetallization (HDM) and hydrodesulfurization (HDS). We also discuss the composition and functions of hydrotreating catalysts, and we highlight areas for further improvement.