• Bulletin of the Korean Chemical Society
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• 제32권4호
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• pp.1253-1257
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• 2011

The surface structures, adsorption conditions, and thermal desorption behaviors of cyclopentanethiol (CPT) self-assembled monolayers (SAMs) on Au(111) were investigated by scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy (XPS), and thermal desorption spectroscopy (TDS). STM imaging revealed that although the adsorption of CPT on Au(111) at room temperature generates disordered SAMs, CPT molecules at $50^{\circ}C$ formed well-ordered SAMs with a $(2{\surd}3{\times}{\surd}5)R41^{\circ}$ packing structure. XPS measurements showed that CPT SAMs at room temperature were formed via chemical reactions between the sulfur atoms and gold surfaces. TDS measurements showed two dominant TD peaks for the decomposed fragments ($C_5H_9^+$, m/e = 69) generated via C-S bond cleavage and the parent molecular species ($C_5H_9SH^+$, m/e = 102) derived from a recombination of the chemisorbed thiolates and hydrogen atoms near 440 K. Interestingly, dimerization of sulfur atoms in n-alkanethiol SAMs usually occurs during thermal desorption and the same reaction did not happen for CPT SAMs, which may be due to the steric hindrance of cyclic rings of the CPT molecules. In this study, we demonstrated that the alicyclic ring of organic thiols strongly affected the surface structure and thermal desorption behavior of SAMs, thus providing a good method for controlling chemical and physical properties of organic thiol SAMs.

• 한국정보통신학회논문지
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• 제10권12호
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• pp.2132-2139
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• 2006

내포 병렬성을 포함하는 병렬 프로그램은 복잡한 수행 양상을 가지며, 태스크들은 병행적으로 수행되는 경향이 있다. 이러한 병행성은 대부분의 오류을 유발하는 근본적인 원인이 된다. 본 논문은 병렬 프로그램 수행양상을 영상화하여 두 태스크간의 병행성을 판별할 수 있는 새로운 방법을 제안한다. 기존의 방법들은 전역적인 구조를 보이는데 제약이 있고 과다한 추상화로 인하여 수행양상의 직관성을 저해하는 경향이 있다. 본 논문에서 제안한 기법은 영상 가시화에 적합한 레이블링 기법을 제안하고, 제안한 레이블링 기법을 적용하여 산출된 각 태스크의 레이블정보를 2차원 평면상에서 분할된 영역으로 표현한다. 이를 토대로 각 태스크의 순서화 관계를 식별할 수 있는 독립된 영상을 생성한다. 결과로 생성된 영상은 관련 태스크의 의미론적 분석을 간소화하고 전체 프로그램의 전역적 수행 구조의 개요를 사용자에게 효과적으로 제공한다.

• 한국도로학회논문집
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• 제20권3호
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• pp.47-57
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• 2018

PURPOSES : The permeable pavement type has been rapidly developed for solving problems regarding traffic noise in the area of housing complex and heavy rainwater drainage in order to account for the climate change. In this regards, the objective of this study is to figure out the characteristics of pavement types. METHODS : The laboratory test for deriving optimum asphalt content (OAC) was conducted using the mixtures of the permeable asphalt surface for the pavement surface from Marshall compaction method. Based on its results, the pavement construction at the test field was conducted. After that, the site performance tests for measuring the traffic noise, strength and permeability were carried out for the relative evaluation in 2 months after the traffic opening. The specific site tests are noble close proximity method (NCPX), Light falling deflectometer test (LFWD) and the compact permeability test. RESULTS : The ordered highest values of the traffic noise level can be found such as normal dense graded asphalt, drainage and porous structure types. In the results from LFWD, the strength values of the porous and drainage asphalt types had been lower, but the strength of normal asphalt structure had relatively stayed high. CONCLUSIONS :The porous structure has been shown to perform significantly better in permeability and noise reduction than others. In addition to this study, the evaluation of the properties and the determination of the optimum thickness for the subgrade course under the porous pavement will be conducted using ground investigation technique in the further research.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2011년도 임시총회 및 하계학술연구발표회
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• pp.129-129
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• 2011

The limited understanding of the surface properties of $Pt_3Ni$ for the oxygen reduction reaction (ORR) in polymer electrolyte membrane fuel cell (PEMFC) has motivated the study of properties and electronic structures of seven layered $Pt_3Ni$ (001), (110), and (111) surfaces. The first principle method based on density functional theory (DFT) is carried out. It is found that the bulk $Pt_3Ni$ has a ferromagnetic ground state with the ordered fcc type L12 structure, which is in good agreement with other results. Non magnetic Pt has the induced magnetic moment due to the strong hybridization between 3d Ni and 5d Pt. The magnetic moment of Pt and Ni enhanced on the surface of each due to surface effect however the magnetic moment of surface Pt in the Pt-segregated Pt3Ni (111) decreased and the magnetic moment of Ni in Ni rich subsurface increased significantly. The calculated d band centers of Pt explain the possibilities for oxygen absorption and play the important roles in altering the catalytic properties. The spin polarized densities of states are presented in order to understand physical properties of Pt in different surfaces in detail.

• Carbon letters
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• 제28권
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• pp.38-46
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• 2018

Modified pitch A (MPA) and modified pitch B (MPB) were prepared by oxidative polymerization and thermal polycondensation reaction with refined pitch as the raw material, respectively. The toluene soluble components (TS-1 and TS-2) were obtained by solvent extraction from MPA and MPB, separately. The Flynn-Wall-Ozawa method and Kissinger-Akahira-Sunose method were used to calculate the pyrolysis activation energy of TS. The Satava-Sestak method was used to investigate the pyrolysis kinetic parameters of TS. Moreover, the optical microstructure of the thermal conversion products (TS-1-P and TS-2-P) by calcination shows that TS-1-P has more contents of mosaic structure and lower contents of fine fiber structure than TS-2-P. The research result obtained by a combination of X-ray diffraction and the curve-fitting method revealed that the ratios of ordered carbon crystallite (Ig) in TS-1-P and TS-2-P were 0.3793 and 0.4417, respectively. The distributions of carbon crystallite on TS-1-P and TS-2-P were calculated by Raman spectrum and curve-fitting analysis. They show that the thermal conversion product of TS-2 has a better graphite crystallite structure than TS-1.

• KSBB Journal
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• 제28권6호
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• pp.356-365
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• 2013

The novel Aloe gels were prepared with dewatering and impregnation by soaking (DIS) processing of Aloe vera leaf slice at four different temperatures (25, 35, 45 and $55^{\circ}C$), using dehydration solution of 40% (w/v) polyethylene glycol (PEG4000). The PEG-impregnation to Aloe vera leaf slice during DIS was observed depending on immersion temperature, and the PEG-impregnated Aloe vera gel (PEG-i-AVG) obtained was characterized using $^1H$ NMR, FT-IR, GPC, XRD and TGA. The PEG-i-AVG had the higher levels of Aloe bioactives (glucomannan and O-acetyl contents) and better quality indices by $^1H$ NMR and FT-IR spectroscopy than those of native Aloe gel. Also, the obtained Aloe gel maintained the bimodal patterns in higher molecular weight region by GPC indicating no degradation of polysaccharide from native Aloe gel. The result observed by SEM confirmed a surface modification by forming the porous structure, and TGA result exhibited better thermal stability than that of native Aloe gel. XRD result revealed that the crystalline structure in Aloe gel was led by incorporation of PEG. Significant decrease of %insolubility and high enhancement of water solubility index were observed, respectively, and highly ordered conformation such as a helix structure was also indicated by Congo red reaction. We concluded that the modification effect for enhancing function of native Aloe gel was successfully obtained by DIS process using PEG as a dehydrating agent. These results suggested that this DIS process had a high potential for developing a new minimally processed product from Aloe vera leaf.

• 대한공간정보학회지
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• 제17권3호
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• pp.41-48
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• 2009

본 연구는 성장과정에서 나타나고 있는 공간적 확산 집중의 특성과 도시공간구조 변화를 측정하는데 목적을 두고 있다. 분석에 사용된 자료는 도시인구, 고용, 개발연면적, 지가를 이용하였다. 분석시기는 1995년이후 10년간으로 1995년, 2000년, 2005년을 기준으로 하였다. 연구방법은 먼저 도시성장 변화를 측정하기 위하여 중심점 이동과 표준편차거리를 산출하였다. 모란지수(Moran's I)분석결과 분산된 형태보다는 전반적으로 집중된 형태를 보이고 있었으나, 그 수준은 다소 미약하게 나타났다. 앞으로 시가화지역에서는 토지이용 등의 계획적인 도시관리가 요구된다고 볼 수 있다. 다음으로 윤곽도로 볼 때, 대체적으로 단핵구조에서 다핵화로 변화된 모습을 보이고 있다. 다만 중심지간에 상호연계축 발달은 미약하였다.

• 한국철도학회논문집
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• 제18권4호
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• pp.344-353
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• 2015

최근 BIM의 활용이 시각적인 3D모델링 이외에 일정 및 공사비 시뮬레이션, 시각적 공사현황관리, 증강현실적용 등으로 확장되면서, 이에 따른 다양한 BIM기능들이 개발되고 있다. 그러나 개발되는 기능들에 대해 명확한 분류기준과 지식정보가 부족하여, 공사프로젝트에 필요한 기능들을 파악하는데 어려움이 있다. 따라서 본 연구에서는 서로 다른 BIM기능의 특성을 반영하여 BIM기능요소 분류체계를 구성하고, 이를 기반으로 BIM기능을 발주할 수 있는 발주모형 구성 방안을 제시하고자 한다. 이로써, 철도시설사업에 적용할 수 있는 BIM기능을 분석하여 실무적 활용성을 높이고자 하였으며, 사례적용을 통해 활용성을 검증하고 있다.

• 한국자기학회지
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• 제21권2호
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• pp.43-47
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• 2011

Fe-Al 계의 전이금속 화합물은 구조적 안정성과 자성에 대한 이견이 많은 것으로 알려져 있다. 본 연구에서는 B2, $L1_2$, 및 $D0_3$ 구조를 갖는 Fe-Al 계 화합물의 자성과 원자구조의 상관관계를 논의하기 위해 전전자 총퍼텐셜선형보강평면파(all-electron fullpotential linearized augmented plane wave; FLAPW) 방법을 이용하여 일반기울기 근사(generalized gradient approximation; GGA) 하에서 계산하였다. 고려한 모든 구조에서 강자성이 비자성에 비해 안정한 것으로 계산되었다. Fe 원자의 계산된 스핀 자기모멘트는 B2, $L1_2$ 구조에서 각각 0.771 ${\mu}_B$, 2.373 ${\mu}_B$의 값을 얻었고, $D0_3$ 구조의 Fe(I) 및 Fe(II) 원자들은 각각 2.409 ${\mu}_B$, 1.911 ${\mu}_B$로 계산 되었다. $Fe_3Al$의 같은 조성을 갖는 $L1_2$와 $D0_3$ 구조간의 안정성을 조사하기 위하여 형성 엔탈피 계산을 통해 강자성 상태에서 16 meV/atom의 에너지 차이로 $D0_3$ 구조가 $L1_2$ 구조보다 더 안정함을 확인하였다. 이 결과는 실험연구와 잘 일치하며, 원자구조와 전자구조의 분석을 통해 구조적 안정성과 자성에 대해 이해하였다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2009년도 추계학술대회 논문집
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• pp.217-220
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• 2009

This paper presents fabrication method of nano-structured PMMA substrates as well as evaluations of their optical transmittance. For anti-reflective surface, surface coating method had been conventionally used. However, it requires high cost, complicated process and post-processing times. In this study, we suggested the fabrication method of anti-reflective surface by the hot embossing process. Using the nano patterned master fabricated by anodic aluminum oxidation process. Anodic aluminum oxide(AAO) is widely used as templates or a molds for various applications such as carbon nano tube (CNT), nano rod and nano dots. Anodic aluminum oxidation process provides highly ordered regular nano-structures on the large area, while conventional pattering methods such as E-beam and FIB can fabricate arbitrary nano-structures on small area. We fabricated a porous alumina hole array with various inter-pore distance and pore diameter. In order to replicate nano-structures using alumina nano hole array patterns, we have carried out hot-embossing process with PMMA substrates. Finally the nano-structured PMMA substrates were fabricated and their optical transmittances were measured in order to evaluate the charateristivs of anti-reflection. Anti-reflective structure can be applied to various displays and automobile components.