• Bulletin of the Korean Chemical Society
• /
• 제35권10호
• /
• pp.2974-2978
• /
• 2014

$Mn_3O_4$/multi-walled carbon nanotube (MWCNT) composites are prepared by chemically synthesizing $Mn_3O_4$ nanoparticles on a MWCNT film at room temperature. Structural and morphological characterization has been carried out using X-ray diffraction (XRD) and scanning and transmission electron microscopies (SEM and TEM). These reveal that polycrystalline $Mn_3O_4$ nanoparticles, with sizes of about 10-20 nm, aggregate to form larger nanoparticles (50-200 nm), and the $Mn_3O_4$ nanoparticles are attached inhomogeneously on MWCNTs. The electrochemical behavior of the composites is analyzed by cyclic voltammetry experiment. The $Mn_3O_4$/MWCNT composite exhibits a specific capacitance of $257Fg^{-1}$ at a scan rate of $5mVs^{-1}$, which is about 3.5 times higher than that of the pure $Mn_3O_4$. Cycle-life tests show that the specific capacitance of the $Mn_3O_4$/MWCNT composite is stable up to 1000 cycles with about 85% capacitance retention, which is better than the pure $Mn_3O_4$ electrode. The improved supercapacitive performance of the $Mn_3O_4$/MWCNT composite electrode can be attributed to the synergistic effects of the $Mn_3O_4$ nanoparticles and the MWCNTs, which arises not only from the combination of pseudocapacitance from $Mn_3O_4$ nanoparticles and electric double layer capacitance from the MWCNTs but also from the increased surface area, pore volume and conducting property of the MWCNT network.

• 한국화재소방학회논문지
• /
• 제28권2호
• /
• pp.48-53
• /
• 2014

본 연구에서는 운동장과 건물의 옥상 등 실외에 설치되고 있는 인조잔디에 대해 국내 기준에 의한 화재위험성을 평가하고자 한다. 현재 인조잔디에 대한 국내 기준은 실외에 한하고 있으며 특히 학교체육시설이라고 국한하여 KS M 3888-1에 강제하고 있고, 실내 기준은 소방방재청고시(2012-35호)에 권장사항으로 규정하고 있다. 이에 본 연구는 강제규정하고 있는 실외에 설치되는 인조잔디에 국한하여 연소시험을 진행하였다. $45^{\circ}$ 방염시험을 진행하여 분석한 결과, 현재 설정되어 있는 기준이 화재의 위험성을 판단하기에 매우 미흡함을 확인하였다. 이에 바닥재로 통용되고 있는 방염처리된 카페트의 연소시험을 통해 그 특징을 비교한 후 분석하였다. 45o 방염시험기를 이용하여 착화성을 시험한 후 평가한 결과, 해당기준에서 크게 벗어난 인조잔디와 달리 카페트는 방염성능기준을 만족하였다. 이에 추가로 인조잔디에 대해 콘칼로리미터시험을 진행하여 착화 이후의 연소특성을 분석 및 평가함으로써 실외 적용되는 인조잔디의 기준 강화를 위한 대책을 제안하였다.

• 건축역사연구
• /
• 제20권1호
• /
• pp.61-75
• /
• 2011

This study aims to investigate the changing aspects about research methodology of stone pagoda from the period of Japanese colonial to now. There were the differences in purpose, method and analysis of the research according to each period. In Japanese colonial period, the purpose of research was to make lists of almost stone pagodas in Korea. Following this, Japanese researchers conducted detailed research for academic purpose. They took measurements of stone pagodas and made drawings. After liberation the research was focused on the relics contained in pagodas. They proceeded to investigate the inner relics in order to attract the attention of the people. In the late 1900's, the repair works of cultural heritages were increased. Many reports of the repair works were released and sent to administration offices. The reports contained the change aspects of situation between before work and after with drawings or simple investigation documents. In the 1990's, the restoration works for important stone pagodas were started by the National Research Institute of Cultural Heritage. Since then, researches from various way - architectural and conservational researches about historical interpretation, shape, structure, proportion, technique, etc. - progressed for careful restoration and accurate study. In Recent years, various professional organizations(in the field of structure, physics, chemistry, biology, lithology, etc.) started to join the researches. Researches conducted studies directly with the stone pagodas, as well as conducting indirect studies with the stone pagodas, such as the structural stability of stone pagodas, the characteristics of rock, and conservation chemicals. Today the research project 'The preservation project of stone cultural property' is being conducted by the National Research Institute of Cultural Heritage. The purpose of this project is to gain more detailed and accurate investigation documents to be provided for the people. In conclusion, researches from various fields must be included in the research. Furthermore, a synthetic study should be done through comparing similar characteristics or different characteristics among many research results.

• 대한지리학회지
• /
• 제38권1호
• /
• pp.70-86
• /
• 2003

이 연구는 안동의 이른바 음택명당 풍수 경관에 대하여 조사하여 그 형태와 특징을 살펴보고자 한다. 안동문화원에서 펴낸 $\ulcorner$안동의 분묘$\lrcorner$에 나오는 분묘와 예천의 일부 묘지를 대부분 야외조사하고, 이 중에서 형기론적 입장에서 나타난 다양한 명당의 특징을 1:25,000지형도 상에서 기술한다. 안동지역은 낙동강, 반변천, 길안천의 수많은 지류가 흐르고 그 주위에 낮은 구릉, 완만한 사면 및 높은 배후 산지가 전개되며 수많은 명당이 입지한다고 알려져 왔다. 연구 결과는 다음과 같다. 안동의 경우는 날짐승(봉, 학, 꿩), 꽃(모란, 연꽃, 칡넝쿨), 길짐승(닭), 들짐승(거북, 뱀). 물건(등잔, 가마솥, 밥상), 용, 달 등의 형기론적 명당이 나타나며, 이들 형태는 크게 낙동강 본류 이북 쪽에 집중한다. 이들 명당은 고도 상으로 해발고도 100m∼400m 부근에 대부분 입지한다. 이들 명당의 공통된 형태적 특징은 반개방성, 중첩성. 안정성. 조화성, 균형성이다. 형태 상의 이러한 특징은 풍수지리의 원리를 오늘날의 입지 선정에 적용할 수 있는 근거를 갖게 하는 것이다.

• Corrosion Science and Technology
• /
• 제2권2호
• /
• pp.68-74
• /
• 2003

The effects of Niobium on the structure and properties(especially electric properties) of passive film of Zirconium alloys in pH 8.5 buffer solution are examined by the photo-electrochemical analysis. For Zr-xNb alloys (x = 0, 0.45, 1.5, 2.5 wt%), photocurrent began to increase at the incident energy of 3.5 ~ 3.7 eV and exhibited the $1^{st}$ peak at 4.3 eV and the $2^{nd}$ peak at 5.7 eV. From $(i_{ph}hv)^{1/2}$ vs. hv plot, indirect band gap energies $E_g{^1}$= 3.01~3.47 eV, $E_g{^2}$= 4.44~4.91 eV were obtained. With increasing Nb content, the relative photocurrent intensity of $1^{st}$ peak significantly increased. Compared with photocurrent spectrum of thermal oxide of Zr-2.5Nb, It was revealed that $1^{st}$ peak in photocurrent spectrum for the passive film formed on Zr-Nb alloy was generated by two types of electron transitions; the one caused by hydrous $ZrO_2$ and the other created by Nb. Two electron transition sources were overlapped over the same range of incident photon energy. In the photocurrent spectrum for passive film formed on Zr-2.5Nb alloy in which Nb is dissolved into matrix by quenching, the relative photocurrent intensity of $1^{st}$ peak increased, which implies that dissolved Nb act as another electron transition source.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
• /
• pp.75.2-75.2
• /
• 2013

Atomic layer deposition (ALD), utilizing self-limiting surface reactions, could offer promising perspectives for future efficient energy conversion devices. The capabilities of ALD for surface/interface modification and construction of novel architectures with sub-nanometer precision and exceptional conformality over high aspect ratio make it more valuable than any other deposition methods in nanoscale science and technology. In the context, a variety of researches on fabrication of active materials for energy conversion applications by ALD are emerging. Among those materials, one-dimensional nanotubular titanium dioxide, providing not only high specific surface area but also efficient carrier transport pathway, is a class of the most intensively explored materials for energy conversion systems, such as photovoltaic cells and photo/electrochemical devices. The monodisperse, stoichiometric, anatase, TiO2 nanotubes with smooth surface morphology and controlled wall thickness were fabricated via low-temperature template-directed ALD followed by subsequent annealing. The ALD-grown, anatase, TiO2 nanotubes in alumina template show unusual crystal growth behavior which allows to form remarkably large grains along axial direction over certain wall thickness. We also fabricated dye-sensitized solar cells (DSCs) introducing our anatase TiO2 nanotubes as photoanodes, and studied the effect of blocking layer, TiO2 thin films formed by ALD, on overall device efficiency. The photon convertsion efficiency ~7% were measured for our TiO2 nanotubebased DSCs with blocking layers, which is ~1% higher than ones without blocking layer. We also performed open circuit voltage decay measurement to estimate recombination rate in our cells, which is 3 times longer than conventional nanoparticulate photoanodes. The high efficiency of our ALD-grown, anatase, TiO2 nanotube-based DSCs may be attributed to both enhanced charge transport property of our TiO2 nanotubes photoanode and the suppression of recombination at the interface between transparent conducting electrode and iodine electrolytes by blocking layer.

• 정보처리학회논문지D
• /
• 제16D권1호
• /
• pp.43-54
• /
• 2009

본 연구의 목적은 모바일 광고에 대한 사용자의 광고가치 인식과 실제 응답의도에 영향을 미치는 변수들을 탐색하고, 인과관계를 분석하는 것이다. 종속변수인 사용자 응답의도와 독립변수 간의 관계적 유의성을 검증하기 위해, Ducoffe(1996)의 광고효과 모형을 기저모형으로 채택하여 연구모형 및 가설을 설정하였다. 주요 독립변수는 유희성, 조작편리성, 정보유용성, 경제성이며, 매개변수로 사용자 광고가치를 개념화 하였다. 특히, 구조모형 경로분석과 조절집단 차이검증 분석을 통해 최적의 연구모형을 도출하였고, 연령별 집단 특성을 규명하기 위해 연령을 조절변수로 선정하여 평가하였다. 본 연구는 모바일 광고의 고유한 특성에 대해, 지금까지 비중 있게 다루지 않았던 광고가치라는 매개변수의 역할과 연령별 차이검증을 실시하였다는 점에서 학술적 그리고 실용적 가치가 있다. 345개 표본을 대상으로 한 설문조사를 바탕으로 실증 분석을 수행하여 연구가설을 검증한 결과, 조작편리성을 제외한 모든 변수의 유의성이 판명되었고, 연령별 집단 간 상이한 결과가 도출되었다.

• Smart Structures and Systems
• /
• 제7권5호
• /
• pp.379-392
• /
• 2011

This paper presents a multi-functional system, consisting of a magnetorheological (MR) damper and an electromagnetic induction (EMI) device, and its applications in stay cables. The proposed system is capable of offering multiple functions: (1) mitigating excessive vibrations of cables, (2) estimating cable tension, and (3) harvesting energy for wireless sensors used health monitoring of cable-stayed bridges. In the proposed system, the EMI device, consisting of permanent magnets and a solenoid coil, can converts vibration energy into electrical energy (i.e., induced emf); hence, it acts as an energy harvesting system. Moreover, the cable tension can be estimated by using the emf signals obtained from the EMI device. In addition, the MR damper, whose damping property is controlled by the harvested energy from the EMI device, can effectively reduce excessive cable vibrations. In this study, the multi-functionality of the proposed system is experimentally evaluated by conducting a shaking table test as well as a full-scale stay cable in a laboratory setting. In the shaking table experiment, the energy harvesting capability of the EMI device for wireless sensor nodes is investigated. The performance on the cable tension estimation and the vibration mitigation are evaluated using the full-scale cable test setup. The test results show that the proposed system can sufficiently generate and store the electricity for operating a wireless sensor node twice per day, significantly alleviate vibration of a stay cable (by providing about 20% larger damping compared to the passive optimal case), and estimate the cable tension accurately within a 2.5% error.

• 동양고전연구
• /
• 제36호
• /
• pp.85-104
• /
• 2009

본 연구는 "논어(論語)"라는 커뮤니케이션 텍스트에서 커뮤니케이터, 수용자, 메시지 등 세 가지 커뮤니케이션 요소를 축으로 하여, 커뮤니케이션 속성의 근거를 찾고자 한 것이다. 여기에는 기존 논어 관련 커뮤니케이션학적 연구의 한계 극복과 학제간 연구의 당위성 및 필요성 제고 의도 또한 포함되고 있다. "논어"가 커뮤니케이션 텍스트인 이유는 문답이라는 인간의 대표적인 커뮤니케이션 방식 사용, 학문 정치 도덕 등과 같은 생활세계의 커뮤니케이션 현상이라는 콘텐츠 특성, 후세에 끼친 영향력이 매우 크기 때문이다. 기존 논어 관련 커뮤니케이션 학적 연구의 문제들은 연구 대상과 연구틀 간 학문적 정합성 논의가 미흡하고, 시론적 속성 기축성(基軸性) 배제 등이 있다. 때문에 본 연구방식을 사용하면 특정 주제 중심의 텍스트 발췌 및 그 재해석을 통해 해결 가능할 것이다. "논어"속에서의 커뮤니케이션 속성은 신실한 윤리성과 논리 및 실천력 등 커뮤니케이터의 요건이 있고, 그리고 이를 토대로 한 도덕적 인간의 이상형으로서 군자(君子) 등이 있다. 또한 어떠한 상황에서도 적절한 메시지 구사 능력 및 선별 판단 능력 그리고 상호 커뮤니케이션 상황의 주도력 등과 같은 수용자 필요조건, 윤리와 이치에 맞으면서 반드시 실천되어야 하는 커뮤니케이션 윤리 실천의 객체인 메시지의 덕목 등이 있다.

• Advances in nano research
• /
• 제13권1호
• /
• pp.97-111
• /
• 2022

In the present article, silica nanoparticles (SNPs) were exploited to improve the tribological and mechanical properties of vinyl ester/glass fiber composites. To the best of our knowledge, there hasn't been any prior study on the wear properties of glass fiber reinforced vinyl ester SiO₂ nanocomposites. The wear resistance is a critical concern in many industries which needs to be managed effectively to reduce high costs. To examine the influence of SNPs on the mechanical properties, seven different weight percentages of vinyl ester/nano-silica composites were initially fabricated. Afterward, based on the tensile testing results of the silica nanocomposites, four wt% of SNPs were selected to fabricate a ternary composite composed of vinyl ester/glass fiber/nano-silica using vacuum-assisted resin transfer molding. At the next stage, the tensile, three-point flexural, Charpy impact, and pin-on-disk wear tests were performed on the ternary composites. The fractured surfaces were analyzed by scanning electron microscopy (SEM) images after conducting previous tests. The most important and interesting result of this study was the development of a nanocomposite that exhibited a 52.2% decrease in the mean coefficient of friction (COF) by augmenting the SNPs, which is beneficial for the fabrication/repair of composite/steel energy pipelines as well as hydraulic and pneumatic pipe systems conveying abrasive materials. Moreover, the weight loss due to wearing the ternary composite containing one wt% of SNPs was significantly reduced by 70%. Such enhanced property of the fabricated nanocomposite may also be an important design factor for marine structures, bridges, and transportation of wind turbine blades.