• Applied Chemistry for Engineering
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• v.28 no.1
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• pp.125-131
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• 2017

We report organically functionalized Ag nanoparticles spontaneously form two-dimensional (2D) novel superstructures at the air-water interface. Analysis of the superstructures suggests that the 2D assembly of Ag nanoparticles originates from a subtle interplay between characteristic inter-particle interactions that can be readily controlled by changing the sizes of nanoparticle metal core and surfactants. Such structures have potential uses in nanostructured functional materials, catalysis, and device applications.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2011.05a
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• pp.65-66
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• 2011

금속:유전체 나노복합체 박막에서 발현되는 국소 표면 플라즈몬 공진특성을 효과적으로 제어하기 위해 코어-쉘 구조를 갖는 나노입자 형성 공정이 물리기상증착법을 이용하여 시도되었다. 선택적 증착 현상에 착안하여 Au와 강한 결합력을 나타내는 sulphur를 포함하는 ZnS 반도체 재료를 모델시스템으로 선정하였다. 교번증착법의 상대적 순서를 변화시켜 가며 Au입자 및 Au-ZnS 코어-쉘 입자의 형성거동을 광흡수 곡선과 TEM 분석을 통해 관찰하였다. Au단일입자에 비해 Au-ZnS 코어-쉘 나노입자는 ZnS 층의 상대적 두께조절에 의해 공진파장의 광범위한 제어가 용이해지고 국부전기장 증폭현상도 강화되는 것으로 확인되었다.

• Journal of Soil and Groundwater Environment
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• v.13 no.5
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• pp.47-56
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• 2008

Temporal changes of metal solubility have been repeatedly observed in soils equilibrated with metal salt solutions. This phenomenon is known as aging, yet factors that affect the degree of metal aging remain largely unexamined. In this study, we compared the extent of aging on metal partitioning depending on soil, metal, and metal loading. Five soils spiked with four levels of Cd (2.5-20 mg ${kg}^{-1}$), Cu, and Zn (50-400 mg ${kg}^{-1}$) salt solutions were aged in the laboratory up to 1 year. The partitioning coefficient ($K_d$) of each metal was calculated from the ratio of total to dissolved metal concentration in samples collected at times ranging from 1 day to 1 year. The highest $K_d$ values for Cd, Cu and Zn were recorded in a Histosol, Andisol, and fine-textured Alfisol, respectively, whereas the lowest $K_d$ was recorded for an Oxisol and coarsetextured Alfisol. For all soils, a pattern of increasing Kd with aging was evident for Cd and Zn, but not Cu. Rapid Cu sorption was limited when dissolved organic matter was high in soils. In highly-retentive soils, $K_d$ values seemed to be insensitive to metal loading, although a longer period was required for the higher metal loadings to reach the same degree of metal aging as the lower loadings. In soils with low sorption capacity, the $K_d$ values were determined more by metal loading than by aging. Therefore, marked differences can be expected in the degree of metal aging in spiked soils by the soil type, metal and amount of metal added.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2000.11a
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• pp.279-280
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• 2000

대기 중 금속부식은 SO$_2$와 부유먼지, $O_3$, 산성비 등의 대기오염물질 및 농도와 그 밖의 이술, 빗물, 해수입자, 온도, 습도, 강우빈도 및 산도 등의 여러 가지 요인에 의해서 영향을 받지만, 특히 SO$_2$와 습도와 관련하여 금속부식에 영향을 미치고 있다. 금속 부식이란 금속의 산화상태 즉 산화ㆍ환원 반응으로 대기오염물질의 금속부식에 미치는 영향은 오염물질 자체가 부식에 직접관여 하는 것 외에 촉매 역할로써의 간접적 요인이 더욱 중요시되고 있으며, 오염물질의종류 및 농도와 지역적 특성에 의한 영향이 크다. (중략)

• Proceeding of EDISON Challenge
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• 2016.03a
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• pp.32-36
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• 2016

단일금속 나노입자에 비해 나노합금입자는 발광이나 촉매력과 같은 여러 특징들이 더 뛰어나게 나타난다고 잘 알려져 있다. 이에 따라 실험적인 연구뿐 아니라 이론적으로도 나노합금입자의 특성과 구조를 밝히려는 노력이 이루어지고 있다. 그러나 대부분의 연구는 자유공간을 상정하여 진행되고 있어, 갇힌 공간 속의 입자에 대한 연구는 부족한 실정이다. 이러한 배경으로 본 연구에서는 Sutton-Chen (SC) 포텐셜을 주요 이론으로 하여, 복제교환분자동력학(replica exchange molecular dynamics, REMD) 모의실험을 통해 가두는 공간의 크기에 따라 금-팔라듐 나노합금입자(Au17Pd17)의 구조와 특성이 어떻게 달라지는지 EDISON에 등록된 metal_alloy 프로그램(molecular dynamics simulation of metal alloy nano-cluster)을 사용해 살펴보았다. 결과적으로 입자가 상전이 이전의 낮은 온도에서 존재하면, 둘러싼 공간의 크기와 무관하게 안정한 구조의 중심에 항상 팔라듐 원자가 위치한다는 것이 확인되었다. 또, 가두는 공간의 크기마다 상전이가 일어나는 온도 구간의 차이가 나타났으며, 작은 공간에 갇힌 입자일수록 입자의 최대 직경이 작아지면서 상대적으로 높은 에너지를 가지는 구조를 형성하였다. 이는 입자가 존재하는 공간이 좁을수록 에너지의 증가를 통하면서 최대한 공간을 활용할 수 있는 구조를 선택하는 것으로 보인다.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.331-331
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• 2012

InGaN/GaN 양자우물 LED소자의 내부양자효과 및 외부양자효과를 높이기 위해 많은 연구자들이 노력을 하고 있다. InGaN/GaN 양자우물 전광소자의 효율을 높이는 방법으로는 무분극 박막성장을 이용한 양자우물의 운반자 파동함수의 분리를 감소시키는 방법, 양자우물 위에 전자 차단층을 성장시키는 방법, 박막의 비발광 결함을 감소시키는 방법, 나노박막 또는 나노 입자를 이용한 표면 플라즈몬 효과를 이용하는 방법 등이 있다[1-3]. 본 연구에서는 은(Ag) 나노입자를 이용하여 InGaN/GaN 양자우물과 p-GaN 덮개층을 패턴에칭한 후, 그 위에 Ag 나노입자를 도포하여 표면 플라즈몬 효과를 이용한 InGaN/GaN 양자우물의 발광효율을 높이고자 하였다. c-면 방향의 사파이어에 유기화학금속증착법(MOCVD)으로 n-형 GaN를 2.0 ${\mu}m$ 성장한 후 그 위에 InGaN/GaN 양자우물 5층을 성장하였다. 또한 전자 차단층으로 AlGaN를 7 nm 증착한 후, p-type GaN를 100 nm 성장하였다. p-type GaN를 패턴하기 위해 포토리소그래피 와 유도결합 플라즈마 에칭공정을 거쳐 선 패턴을 형성하였는데, 이 때 에칭된 p-GaN 깊이는 약 90 nm 이었다. 에칭한 패턴크기가 LED소자의 전기적 및 광학적 특성에 미치는 영향을 알아보기 위해 전류-전압 측정과 photoluminescence 측정을 하였다. 그 후 급속열처리방법을 이용한 Ag 나노입자 형성과 표면플라즈몬이 소자의 발광효율에 미치는 영향에 대해 조사하였다.

• Applied Chemistry for Engineering
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• v.34 no.2
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• pp.121-125
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• 2023

Casein is a milk protein and one of the most important nutrients in milk. The composition is over 80% in cow's milk and about 20~45% in human's milk. Casein is highly biocompatible and biodegradable, so it has been studied for various biomedical materials applications as well as drug delivery systems. It is widely known that casein can be prepared as nanoparticles in the presence of the Ca²⁺ metal ion. Because casein is amphiphilic, hydrophobic drugs could be loaded inside to form a protein-based drug delivery system. In this study, we studied the optimum conditions for casein nanoparticle formation using natural metal ions present in the body, such as calcium, magnesium, zinc, and iron. It was confirmed that nanoparticles have a uniform size of around 150 nm and negative zeta potential values. In addition, it was demonstrated that casein nanoparticles have a cell viability of more than 80% and efficient intracellular uptake properties using confocal microscopy. From the results, it was also shown that the casein nanoparticles prepared using various metal ions have the potential to be biocompatible drug delivery carriers.

• Korean Chemical Engineering Research
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• v.54 no.2
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• pp.200-205
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• 2016

A drug transport carrier could be used for safe send of drugs to the affected region in a human body. The chitosan is adequate for the drug delivery carrier because of adaptable to living body. The gold, a metallic nanoparticles, tends to form a nano complex at rapidly when it combined with chitosan because of its negative charge. having energy from the other, outer gold nano-complex make heat due to its property to release the contained drugs to the target area. Silver could be also formed an useful biocompatible nano-composites with chitosan which should be used as an useful drug transfer carrier because its special ability to protect microbial contamination. Being one of the oxidized nano metals, $Fe_3O_4$ is nontoxic and has been used for its magnetic characteristics. In this study, the control of catalyst, reducing agent, and solvent amount. The chitosan-$Fe_3O_4$-gold & silver nanoshell have been changed to form about 100 nm size by ionic bond between the amine group, an end group of chitosan, and the metal. It was observed the change in order to seek for its optimum reaction condition as a drug transfer carrier.

• Journal of the Korean Society of Propulsion Engineers
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• v.15 no.6
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• pp.15-25
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• 2011

One dimensional combustion modeling of aluminum combustion behavior is proposed. Combustion model is assumed that region consists as follows ; preheat, reaction, post reaction region. Flame speed as a function of particle size, equivalence ratio for unitary particles and fraction ratio of micro to nano particle size for binary particles were investigated for lean burn condition at 1 atm. Results were compared with experimental data. For unitary particles, flame speed increase as particle size decreases, but opposite trend with equivalence ratio. For binary particles, flame speed increases proportionally as nano particle fraction increases. For flame structure, separated or overlapping flames are observed, depending on the fraction of nano sized particles.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2012.05a
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• pp.429-434
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• 2012

Ignition delay of micro/nano aluminum particles is caused by aluminum oxide shell. The method of minimizing this ignition delay is proposed in the study. Generating and heating of particles are processed at the same time. As soon as heated particles are produced, they immediately contact with oxygen. Chemical reaction is induced on the contact surface instead of crystallization of oxide shell. Finally particles are ignited. Aluminum particles are generated by laser ablation on an aluminum plate using Nd:YAG pulse laser. Injected particles are confirmed through visualization of particles using scattering method. $CO_2$ continuous laser supplies heat to aluminum plate and generated particles. Trace of burning particles is observed in the experiment.