• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.368-368
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• 2016

그래핀(Graphene)은 탄소 원자가 6각 구조로 이루진 2차원 알려진 물질 중 가장 얇은(0.34 nm) 두께의 물질이며 그 밴드구로조 인해 우수한 전자 이동도($200000cmV^{-1}s^{-1}$)를 가지고 있며, 이외에도 기계적, 화학적으로 뛰어난 특성을 가진다. 대면적화 된 그래핀을 성장시키기 위한 방법으로는 화학적 기상 증착법(Chemical Vapor Deposition)이 있다. 하지만 실제 여러 전이금속에서 합성되는 그래핀은 다결정으로, 서로 다른 면 방향을 가진 계면에서 전자의 산란이 일어나며, 고유의 우수한 특성이 저하되게 된다. 따라서 전자소재로 사용되기 위해서는 단결정의 대면적화 된 그래핀에 대한 연구가 지속적으로 이루어지고 있다. 앞서의 두 문제점 중, 단결정의 그래핀 합성에 크게 영향을 미치는 요인으로는 크게 합성 온도, 촉매 기판의 탄소 용해도, 촉매 표면에서의 탄소 원자의 확산성이 있다. 본 연구에서는 구리, 니켈, 실리콘에 비해 탄소 용해도가 낮으며, 탄소 원자의 높은 확산성으로 인해 단결정의 단층 그래핀을 합성에 적합하다고 보고된 저마늄(Germanium) 기판을 사용하여 그래핀을 합성하였다. 단결정의 그래핀을 성장시키기 위해 메탄(Methane; $CH_4$)가스의 주입량과 수소 가스의 주입량을 제어하여 성장 속도를 조절 하였으며, 성장하는 그래핀의 면방향을 제어하고자 하였다. 표면의 산화층(Oxidized layer)을 제거하기 위하여 불산(Hydrofluoric acid)를 사용하였다. 불산 처리 후 표면의 변화는 원자간력현미경(Atomic force microscopipe)을 통하여 분석하였다. 합성된 그래핀의 특성을 저 에너지 전자현미경(Low energy electron microscopy), 광전자 현미경(Photo emission electron microscopy), 라만 분광법(Raman spectroscopy), 원자간력현미경(Atomic force microscopy)와 투과전자현미경 (transmission electron microscopy)을 이용하여 기판 표면의 구조와 결정성을 분석하였다.

• Journal of the Mineralogical Society of Korea
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• v.25 no.2
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• pp.77-84
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• 2012

Anatase, one of the $TiO_2$ polymorphs, is known to show different phase transition paths depending on its crystalline and shape. Particle size of 15~25 nm anatase has been subjected to high-pressure Raman spectroscopy and X-ray diffraction studies using a diamond anvil cell. We observe that the starting sample transforms to an amorphous phase above approx. 20 GPa, which is retained upon pressure release to ambient condition. This is in contrast to previously established transition to baddeleyite phase and we suspect difference in the particle distribution state trigger phase instability of nanoparticles and hence amorphization.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.660-662
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• 2005

본 연구에서는 미 인근 해저에서 ODP로 확인된 부존 하이드레이트 샘플을 다양한 분광학 및 실험적 분석 방법을 통해 시료의 물성 및 특성을 파악하여 부존된 하이드레이트 자원의 성분 파악을 목적으로 하고 있다. 일반적으로 가스 하이드레이트 연구에 있어서 X-ray diffractometer, NMR stectrometer, Raman spectrometer 등 분광학적 분석기기를 이용하여 가스 하이드레이트의 구조 및 성분을 규명한다. 본 연구에서는 실험실에서 인위적으로 만들어진 메탄 하이드레이트와 심해저 천연가스 하이드레이트 층에서 채취된 샘플의 비교 분석을 통하여 심해에 매장되어 있는 천연가스 하이드레이트의 구조 및 성분을 규명하였다 XRD 결과로부터 천연가스 하이드레이트는 sI의 구조를 가지며 NMR 및 Raman 결과에 의하면 하이드레이트 내에 포집되어 있는 가스의 주 성분은 메탄인 것으로 밝혀졌다. 또한 천연가스 하이드레이트를 이용한 이산화탄소의 치환 실험을 통하여 심해저 천연가스 하이드레이트 층의 이산화탄소 저장 매체로의 활용 가능성을 조사하였다.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.446-446
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• 2014

흑연(graphite)과 티타늄(titanum; Ti) 타겟이 양쪽에 부착되어 있는 비대칭 마그네트론 스퍼터링 장치를 이용하여 Ti이 도핑되어진 다이아몬드상 탄소박막(Ti doped Diamond-like carbon, DLC:Ti)을 증착하였다. 흑연과 티타늄 타겟의 파워는 고정하고 기판에 음의 DC 바이어스를 인가하여 DC 바이어스 변화에 따른 DLC:Ti 박막을 증착하였다. 증착되어진 박막의 음의 DC 바이어스의 변화에 따라 변화되어지는 경도와 마찰계수, 표면의 거칠기, 접촉각 등의 물리적 특성들을 분석하였으며, XPS와 라만등의 분석법을 이용하여 박막의 구조적 특성을 분석하였으며, 패시베이션 층을 위한 전기적 특성등을 평가하여 이들 특성들간에 관계를 고찰하였다.

• 보존과학연구
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• s.32
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• pp.89-98
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• 2011

It is quite difficult to identify its corrosion compound because they have a wide variety of crystal structures and they are mixed with two component. This study was conducted with the standard iron corrosion compounds through the analysis by Raman Micro-Spectroscopy, which aims to obtain standard Raman Data. To assess the reliability of standard iron corrosion compounds, SEM-EDS analysis and XRD analysis were conducted. Through SEM-EDS analysis, the elements of corrosion compound matched with those of standards iron corrosion compounds except Goethite. XRD analysis showed that the structures of corrosion compounds were identical to those of standard iron corrosion compounds, however, it was identified that Iron sulfate ($FeSO_4{\cdot}6H_2O$) is the Rozenite ($FeSO_4{\cdot}4H_2O$). Through Raman Micro-Spectroscopy analysis, the new peak was detected from the wavenumbers of hydroxide and iron oxide. It is considered that it is due to changes in the wavelength of the laser. As the wavenumbers of iron chloride and iron sulfate have been identified, eight kinds of Raman Data were obtained. It can be considered to contribute to cultral heritage for iron objects that Raman Micro-Spectroscopy analysis which is relatively easy to compare material properties and structures can be highly applicable to the research on cultural heritage with the limited amount of samples.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.12
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• pp.8455-8461
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• 2015

In this paper, we propose new search algorithms using SVD(Singular Value Decomposition) for fast search of Raman spectrum. In the proposed algorithms, small number of the eigen vectors obtained by SVD are chosen in accordance with their respective significance to achieve computation reduction. By introducing pilot test, we exclude large number of data from search and then, we apply partial distance search(PDS) for further computation reduction. We prepared 14,032 kinds of chemical Raman spectrum as the library for comparisons. Experiments were carried out with 7 methods, that is Full Search, PDS, 1DMPS modified MPS for applying to 1-dimensional space data with PDS(1DMPS+PDS), 1DMPS with PDS by using descending sorted variance of data(1DMPS Sort with Variance+PDS), 250-dimensional components of the SVD with PDS(250SVD+PDS) and proposed algorithms, PSP and PSSP. For exact comparison of computations, we compared the number of multiplications and additions required for each method. According to the experiments, PSSP algorithm shows 64.8% computation reduction when compared with 250SVD+PDS while PSP shows 157% computation reduction.

• Journal of the Korean Society for Nondestructive Testing
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• v.36 no.6
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• pp.443-450
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• 2016

In this study, we propose a novel fiber optic sensor to show the measurement feasibility of distributed temperature and strains in a single sensing fiber line. Distributed temperature can be measured using optical time domain reflectometry (OTDR) with a Raman anti-Stokes light in the sensing fiber line. Moreover, the strain can be measured by fiber Bragg gratings (FBGs) in the same sensing fiber line. The anti-Stokes Raman back-scattering lights from both ends of the sensing fiber, which consists of a 4 km single mode optical fiber, are acquired and inserted into a newly formulated equation to calculate the temperature. Furthermore, the center wavelengths from the FBGs in the sensing fiber are detected by an optical spectrum analyzer; these are converted to strain values. The initial wavelengths of the FBGs are selected to avoid a cross-talk with the wavelength of the Raman pulsed pump light. Wavelength shifts from a tension test were found to be 0.1 nm, 0.17 nm, 0.29 nm, and 0.00 nm, with corresponding strain values of $85.76{\mu}{\epsilon}$, $145.55{\mu}{\epsilon}$, $247.86{\mu}{\epsilon}$, and $0.00{\mu}{\epsilon}$, respectively. In addition, a 50 m portion of the sensing fiber from $30^{\circ}C$ to $70^{\circ}C$ at $10^{\circ}C$ intervals was used to measure the distributed temperature. In all tests, the temperature measurement accuracy of the proposed sensor was less than $0.50^{\circ}C$.

• Fire Science and Engineering
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• v.30 no.4
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• pp.27-38
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• 2016

The paper reports the development of a distributed temperature sensing (DTS) system, which is a fire detection system using optical sensor linear detectors that depends on foreign and domestic technologies. This study accordingly analyzed the electrical signal patterns of Raman scattering light mainly used for temperature sensing among back-scattered light generated in optical fiber by using an oscilloscope. Through the measurement results, it could be verified that the Stokes signal patterns had little change by the temperature increase, but the temperature-sensitive anti-Stokes patterns had relative increase of the changes. This study developed a K-DTS system, which is an optical sensor linear fire detection system composed of an optical repeater and a receiver that can detect fires using Raman scattering light. It could be verified that the developed K-DTS system satisfied the type approval standards through the sensitivity tests using the rate of rise type and fixed temperature type sensitivity testers. In addition, performance experiments have been performed for performance evaluation of the K-DTS system developed in comparison with S-DTS system which has been imported from abroad and widely used in Korea. It can be confirmed from the results of the performance experiments using model tunnels that comparable performances can be obtained in fire detection locations and the measurements of fire temperatures.

• Clean Technology
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• v.19 no.4
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• pp.401-409
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• 2013

BBiodegradable polymers have attracted great attention because of the increased environmental pollution by waste plastics. In this study, PLA (polylactic acid)/Clay-20 (Cloisite 20) and PLA (polylactic acid)/PBS (poly(butylene succinate)/Clay-20 (Cloisite 20) nanocomposites were manufactured in a twin-screw extruder. Specimens for mechanical properties of PLA/Clay-20 and PLA/PBS (90/10)/Clay-20 nanocomposites were prepared by injection molding. Thermal, mechanical, morphological and raman spectral properties of two nanocomposites were investigated by differential scanning calorimetry (DSC), tensile tester, scanning electron microscopy (SEM) and raman-microscope spectrophotometer, respectively. In addition, hydrolytic degradation properties of two nanocomposites were investigated by hydrolytic degradation test. It was confirmed that the crystallinity of PLA/Clay-20 and PLA/PBS/Clay-20 nanocomposite was increased with increasing Clay-20 content and the Clay-20 is miscible with PLA and PLA/PBS resin from DSC and SEM results. Tensile strength of two nanocomposites was decreased, but thier elongation, impact strength, tensile modulus and flexural modulus were increased with an increase of Clay-20 content. The impact strength of PLA/Clay-20 and PLA/PBS/Clay-20 nanocomposites with 5 wt% of Clay-20 content was increased above twice than that of pure PLA and PLA/PBS (90/10). The hydrolytic degradation rate of PLA/Clay-20 nanocomposite with 3 wt% of Clay-20 content was accelerated about twice than that of pure PLA. The reason is that degradation may occur in the PLA and Clay-20 interface easily because of hydrophilic property of organic Clay-20. It was confirmed that a proper amount of Clay-20 can improve the mechanical properties of PLA and can control biodegradable property of PLA.

• Journal of Conservation Science
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• v.37 no.5
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• pp.525-535
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• 2021

This study identified material properties through scientific analysis on Jikgeumdan(satin with gold threads) from Donggungbi-Wonsam and the gold threads used in the embroidery. The Donggungbi-Wonsam's base of gold threads were estimated to have used mulberry fiber's Korean paper(Hanji) because non-wood-based fibers were observed. The X-ray spectrometer showed that the Tongsuseulan of Donggungbi-Wonsam was a flat gold thread of pure gold and Jikgeumdan of flat silver thread of its Saekdong and Hansam. High sulfur levels were detected in the flat silver thread, which appeared to have formed silver sulfide by either manufacturing process using sulfur or conservation environment. he dragon insignia's embroidery is also described as two types twisted gold threads; pure gold and alloying-gold and silver. while dragon insignia's border line is decorated with a twisted gold thread of pure gold. In particular, it was investigated that adhesives such as an animal glue, a protein-based compound by gas chromatography mass spectrometry. Additionally, XRF and Raman spectroscopy analysis on the mixture substances between the metal surface and the base paper of gold threads identified talc and quartz in the gold threads and Seokganju(hematite) in the flat silver threads.