• Journal of the Korean Society of Marine Environment & Safety
• /
• v.27 no.1
• /
• pp.179-186
• /
• 2021

In this study, we attempted to comparatively analyze the structural characteristics of soot generated from marine engines to review the possibility of recycling crankcase soot by classifying it as exhaust soot and crankcase soot. The annealing procedure was performed in an argon gas atmosphere at 2,000℃ and 2,700℃, and Raman spectroscopy and High-Resolution Transmission Electron Microscopy(HRTEM) were used to analyze the structural properties of the samples. Furthermore, digital image processing techniques were utilized to quantitatively analyze the acquired HRTEM images. The Raman analysis demonstrated a relatively high G/D ratio in the exhaust soot and annealing conditions at 2,700℃. In the HRTEM images, both soot were able to identify similar forms of graphite nanostructures, but there were limitations in that they could not quantitatively derive differences in the degree of graphite depending on the type of soot and annealing temperature. Thus, digital image processing quantitatively analyzed the length and tortuosity of the fringe of the HRTEM image, which is consistent with the Raman analysis. This meant that the exhaust soot had a more graphite structure than the crankcase soot, and that annealing at a higher temperature improved the graphite structure. This study confirmed that both the crankcase soot and exhaust soot can be recycled as a graphite materials.

• Journal of the Korean Chemical Society
• /
• v.48 no.1
• /
• pp.46-52
• /
• 2004

The effect of crystallinity on the structural stability of layered manganese oxide has been systematically investigated. While well-crystalline manganate was prepared by solid-state reaction-ion exchange method, nanocrystalline one was obtained by Chimie-Douce reaction at room temperature. According to micro-Raman and Mn K-edge X-ray absorption spectroscopic results, manganese ions in both the manganese oxides are stabilized in the octahedral sites of the layered lattice consisting of edge-shared MnO6 octahedra. The differential potential plot clarifies that the layered structure of nanocrystalline material is well maintained during electrochemical cycling, in contrast to the well-crystalline homologue. From the micro-Raman results, it was found that delithiation-relithiation process for well-crystalline material gives rise to the structural transition from layered to spinel-type structure. On the basis of the present experimental findings, it can be concluded that nanocrystalline nature plays an important role in enhancing the structural stability of layered manganese oxides.

• Proceedings of the Optical Society of Korea Conference
• /
• 2008.02a
• /
• pp.453-454
• /
• 2008

femtosecond laser를 광원으로 하는 optical tweezers는 광포획 뿐만 아니라 비선형 현상을 발생시킬 수 있다는 장점을 가지고 있다. 그러나 높은 첨두 출력에 의하여 포획된 세포는 쉽게 손상되어 질 수 있다. 본 논문에서는 LTRS(Laser Tweezers Raman Spectroscopy)를 통하여 femtosecond laser와 CW laser에 의한 optical tweezers 상에서의 optical damage를 비교, 분석하였다.

• Journal of the Korean Electrochemical Society
• /
• v.22 no.2
• /
• pp.53-59
• /
• 2019

To examine the solution structure of electrolytes, it is very important to understand ion-ion and ion-solvent interactions. In this review, we introduce the basic principle of dielectric relaxation spectroscopy (DRS) and studies of electrolyte structure. DRS is a type of impedance method, which measures the dielectric properties of electrolytes over a high frequency domain at levels of tens of GHz. Therefore, DRS provides information on the different polar chemical species present in the electrolyte, including the type and concentration of free solvents and ion pairs with dipole moments. The information of DRS is complementary to the information of conventional analytical techniques (Infrared/Raman spectroscopy, nuclear magnetic resonance (NMR), etc.) and thus enables a broad understanding of electrolyte structure.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2013.02a
• /
• pp.623-623
• /
• 2013

그래핀(graphene)의 라만 스펙트럼은 전하밀도(charge density)와 기계적 변형(strain)에 민감하여 수많은 연구에 활용되고 있다. 그러나 실제 시료에서 관찰되는 두 물질량의 복잡한 변이를 정량 분석하기 위해서는 기계적 변형뿐만 아니라 전하밀도의 영향에 대한 신뢰도 높은 검정곡선이 필요하다. 본 연구에서는 기계적 박리법으로 만들어진 그래핀에서 나타나는 기계적 변형과 황산 수용액이 미치는 p-형 화학도핑(chemical doping)의 영향을 라만 분광법을 이용하여 연구하였다. 농도 변화에 따른 G와 2D 피크의 진동수 변화는 정전기적 방법을 이용하여 보고된 결과보다 높은 재현성을 보여 검정곡선으로 활용되기에 적합함을 알 수 있었다. 본 연구에서는 514 nm 이외에도 널리 활용되는 몇 가지 파장에서 "전하밀도-변형" 검정곡선을 제시하고자한다.

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2007.11a
• /
• pp.164-165
• /
• 2007

Si(중간층)/DLC(diamond-like carbon)막은 스퍼터와 이온소스(ion source)법에 의한 복합방식(hybrid method)을 이용하여 3mTorr의 반응가스 벤젠($C_6H_6$)분위기에서 Si wafer에 기판온도 $130^{\circ}C$로 180분간 증착하였다. 평가는 표면과 단면에 대해 주사전자현미경(scanning electron microscopy, SEM)과 투자전자현미경(trasmission electron microsope, TEM)으로 관찰하였다. 경도와 마찰계수는 나노인텐터(nanoindetor)와 마모시험기를 이용하였으며, 박막의 구조는 라만스펙트럼으로 분석하였다. 그 결과 박막의 두께는 약 $0.9{\mu}m$, 표면조도는 약 $0.34{\sim}1.64nm$로 평탄한 표면을 가지며 경도는 약 $35{\sim}37GPa$, 마찰계수는 약 $0.02{\sim}0.07$로 관찰되었다. 라만분광법과 전자회절패턴에 의해 IG/ID의 함량비는 $0.54{\sim}0.59$로 $sp^2$와 $sp^3$가 혼재된 전형적인 비정질 구조임을 확인하였다.

• 한국신재생에너지학회:학술대회논문집
• /
• 2011.05a
• /
• pp.104.1-104.1
• /
• 2011

가볍고, 유연성(flexibility)을 갖는 박막(thin film)형 플랙서블 태양전지(flexible solar cell)는 상황에 따른 형태의 변형이 가능하여, 휴대가 간편하고, 기존 혹은 신규 구조물의 지붕(rooftop)등에 설치가 용이하여, 차세대 성장 동력 분야에서 각광받고 있다. 그러나 아직까지 플랙서블 태양전지는 제작시 열에 의한 기판의 변형, 기판 이송시 너울 현상, 대면적 패터닝(patterning) 기술 등 많은 어려움 등으로 웨이퍼나 글라스 기판에 제조된 태양전지 대비 낮은 광전환 효율을 갖는다. 따라서 본 연구에서는 플랙서플 태양전지 성능개선을 위해 3.5세대급 ($450{\times}450cm^2$) 스퍼터(sputter), 금속유기 화학기상장치 (MOCVD), 플라즈마 화학기상장치 (PECVD), 레이저 가공장치 (Laser scriber)를 이용하여 a-Si:H/a-SiGe:H 이중접합(tandem)을 갖는 태양전지를 제작하였고, 광 변환효율 특성을 평가하였다. 전도도(conductivity), 라만(Raman)분광 및 UV/Visible 분광 분석을 통하여 박막의 전기적, 구조적, 광학적 물성을 평가하여 단위박막의 물성을 최적화 했다. 또한 제작된 태양전지는 쏠라 시뮬레이터 (Solar Simulator)를 이용하여 성능 평가를 수행하였고, 상/하부층의 전류 정합 (current matching)을 위해 외부양자효율 (external quantum efficiency) 분석을 수행하였다. 제작된 이중접합 접이식 태양전지로 소면적($0.25cm^2$)에서 8.7%, 대면적($360cm^2$ 이상) 8.0% 이상의 효율을 확보하였으며, 성능 개선을 위해 대면적 패턴 기술 향상 및 공정 기술 개선을 수행 중이다.

• Journal of the Mineralogical Society of Korea
• /
• v.29 no.3
• /
• pp.131-139
• /
• 2016

Detailed knowledge on maskelynite, a glassy phase of plagioclase found in shocked meteorites and impact craters, is essential to understand a shock metamorphism. Here, we explore an inhomogeneous shock metamorphism in the lunar meteorite Mount DeWitt (DEW) 12007 with an aim to understand the formation mechanism of maskelynite. Most plagioclase grains in the DEW 12007 partially amorphized into maskelynite with a unidirectional orientation. Back-scattered electron (BSE) images of maskelynite show a remnant of planar deformation fracture possibly indicating that the maskelynite would be formed by solid-state transformation(i.e., diaplectic glass). Plagioclase with flow texture is also observed along the rim of maskelynite, which would be a result of recrystallization of melted plagioclase. Results of Raman experiments suggest that shock pressure for plagioclase and maskelynite in the DEW 12007 is approximately 5-32 GPa and 26-45 GPa, respectively. The difference in shock pressures between plagioclase and maskelynite can be originated from 1) external factors such as inhomogeneous shock pressure and/or 2) internal factors such as chemical composition and porosity of rock. Unfortunately, Raman spectroscopy has a limitation in revealing the detailed atomic structure of maskelynite such as development of six- or five-coordinated aluminum atom upon various shock pressure. Further studies using nuclear magnetic resonance spectroscopy are necessary to understand the formation mechanism of maskelynite under high pressure.

• Journal of the Korean Chemical Society
• /
• v.47 no.5
• /
• pp.447-459
• /
• 2003

Generalized 2D correlation spectroscopy has been applied extensively to the analysis of spectral data sets obtained during the observation of a system under some external perturbation. It is used in various fields of spectroscopy including IR, Raman, UV, fluorescence, X-ray diffraction, and X-ray absorption spectroscopy (XAS) as well as chromatography. 2D hetero-spectral correlation analysis compares two completely different types of spectra obtained for a system under the same perturbation. Because of the wide range of applications of this technique, it has become one of the standard analytical techniques for the analytical chemistry, physical chemistry, biochemistry, and so on, and for studies of polymers, biomolecules, nanomaterials, etc. In this paper, we will introduce the principle of generalized 2D correlation spectroscopy and its applications that we have studied.

• Journal of Conservation Science
• /
• v.28 no.4
• /
• pp.343-351
• /
• 2012

Excavated archaeological iron objects are prevented from being corroded going through desalination which slow down being corroded. However archaeological iron objects are liable to be corroded due to the high ionization tendency even though they are stored in environment restricted from corrosion factors. Iron objects could be deteriorated more than just excavated. Therefore this study investigated about the characteristic of re-corrosion and the effect on objects. In study, archaeological iron nails in storage for 4 years after conservation treatments were tested. Optical microscopy and X-ray photography for appearance, XRD, SEM-EDS, Raman spectroscopy for chemical composition, IC for chloride ions concentration inside iron nails were used. As results, iron nails carried out conservation treatments measured a high concentration of chloride ions after the long storage period. The form of objects were not in good condition such as broken or destroyed when the high chloride ions concentration was detected. In addition, the yellow and red powdery corrosion product were detected on the boundary between corrosion products and substrates and they were identified as akaganeite which is symptom of active corrosion.