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        검색결과 232

        41.
        2018.05 구독 인증기관·개인회원 무료
        Dynamic modulus of Asphalt Concrete (|E*|) is one of the most important input parameters is used to design pavement structure according to mechanical-empirical Pavement design of the United State of America. Because of its importance, there has been a lot of research on predictive models of (|E*|) as well as sensitive analysis of input parameters influences dynamic modulus in order to find out which one is the most influence on (|E*|), basing on that, the most reasonable quality control and quality assurance can be applied to ensure quality of work is under control. This paper presents sensitive analysis of input parameters influence (|E*|) of dense asphalt concrete in Viet Nam according to some predictive models of dynamic modulus of the United State of America by applying Monte Carlo simulation method.
        42.
        2018.05 구독 인증기관·개인회원 무료
        In Vietnam, reclaimed asphalt pavement technology is considered as the key to reduce the cost of pavement construction, and decrease the industrial waste from flexible pavement rehabilitation. Ministry of Transportation has concentrated to develop RAP technology since 2008. As a result, there are three trademark of recycling technologies applied in Vietnam such as Wirtgen (Germany), Hall Brothers (U.S.), and Sakai (Japan). This paper is focused on asphalt pavement investigation of field and laboratory tests from Cold In-place recycling technology. The laboratory tests carried out on the material were conventional tests including Marshall stability, indirect tensile strength... Field data was collected using a Benkelman beam and core specimens for indirect tensile strength test.
        43.
        2018.05 구독 인증기관·개인회원 무료
        When piles adjacent to deep excavations (i.e. tunnel operation), pile for slope stabilization, highway embankments near abutment piles in soft soil, the load generates lateral soil movement on pile. The lateral soil movement leads to develop the horizontal pressure between the pile and soil, also increase deflection as well as bending moment in the pile. In order to investigate a single pile subjected to horizontal loads due to the movement of the upper soil layer, the pile and soils are modelled by using 3D finite element analysis in this paper. The finite element analysis software used in this study is ANSYS. Furthermore, the soil's elastic behaviour follows the Mohr-Coulomb model and the pair of contact elements is used to simulate the pile-soil contact. A good correlation between laboratory and predicted results is observed in the validation analysis. The parametric study also demonstrates that soil Young's modulus and soil movement profile are key factors in predicting the behaviour of the pile.
        44.
        2018.05 구독 인증기관·개인회원 무료
        Rice husk, in large quantities, is released to the environment due to rice production in Vietnam. If this material can be utilized, it can solve not only the economic issues but also the environmental problems and sustainable development of the country. Laboratory evaluation of asphalt mixture using Nano silica made from rice husk to improve rutting resistance of asphalt mixtures was presented in this study. A 60/70 bitumen was used as control asphalt binder. The ratio of Nano SIO2 used in this study was 0.3%, 0,6%, 0,9%, 1,2%, and 1,5% by weight of powder. A dense gradation with nominal maximum aggregate size of 12.5mm was used for the asphalt mixtures. Marshall stability (MS) test and wheel tracking (WT) test were conducted to evaluate the rutting resistance of asphalt mixtures. It was found that the asphalt mixtures using 0.5%, 1.0%, and 1.5% Nano SIO2 have the rut depths of 5.35mm, 5.39mm, and 5.45mm, respectively, which is 30%, 31% and 29% lower than the control asphalt mixtures at 15,000 load cycles. Moreover, the static modulus of asphalt mixtures using 0.9% Nano SIO2 at 60oC is higher than the control mixtures. Based on the results of this study, it can be concluded that the addition of Nano SIO2 into asphalt mixtures can enhance the rutting performance of asphalt concrete under high temperatures significantly. It is noted that these conclusions were based on only on a limited number of samples and conditions. Further studies must be conducted to investigate the effect of Nano SIO2 on fatigue cracking and moisture damage of asphalt pavement in the field.
        45.
        2018.05 구독 인증기관·개인회원 무료
        This document gives a result of experiments on concrete using admixture Sikament® R4 combine with Sikacrete PP1. In developing countries, the development guides to build and set up a new infrastructure. In this case, the schedule of works is very important, which depends on the setting time of concrete structure. Specially, in tropical monsoon climate country, we need to use admixtures to increase the life time of constructions, especially concrete structures. Today, there are thousands of building, roads and bridges will be made. By using admixture, it not only helps to save the waiting time on the work site, but also increase quality of concrete structure. By using these good effects of admixtures, it’s necessary to find an optimal ratio of them in the mix design ingredient of concrete. The concrete strength can be controlled by changing a range of variety ratio of admixture in the mix design. This topic will find out the role of admixture and its relationship with the compressive strength of concrete.
        46.
        2017.04 구독 인증기관·개인회원 무료
        UHI rises when urban area becomes warmer than its surrounding and is considered as one of the main reasons for cicada abundance in urban areas. Two cicada species, Cryptotympana atrata and Hyalessa fuscata, are more abundant in urban areas with high urban heat island intensities (UHI) than in areas with low UHI. Thermal responses are a measure of cicada adaptation to thermal conditions in the habitat. Hence, we hypothesized that cicadas inhabiting high UHI areas exhibited elevated thermal responses compared to those occupying in low UHI areas. We measured minimum flight temperature (MFT), maximum voluntary temperature (MVT), and heat torpor temperature (HTT) of C. atrata and H. fuscata in metropolitan Seoul. For each species, there were three treatments: high UHI, low UHI, and suburb populations. We discovered that MFT and MVT were similar across all thermal treatments for each species. There was no difference in HTT across three treatments in C. atrata, meanwhile the HTT estimate was significantly higher in H. fuscata with high UHI than in those with low UHI. These results may suggest that H. fuscata in areas of high UHI may have developed thermal adaptation to high temperatures.
        47.
        2016.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Nanosized hollow silica was prepared by Stӧber method in the presence of aluminum isopropoxide. The mixture of polyelectrolytes such as poly(sodium 4-styrene sulfonate)(PSS) and polyacrylic acid(PAA) were used as templates. Tetraethylorthosilicate(TEOS) and aluminum isopropoxide were used as precursors for silica and alumina, respectively. The function of aluminum isopropoxide is to increase the porosity of silica shell. The characterizations of hollow silica were examined by TEM(transmission electron microscopy), TGA(thermogravimetric analysis), BET(Brunauer Emmett Teller), Energy-dispersive X-ray spectroscopy(EDS), and FT-IR spectrum. It was found that the shell thickness of hollow silica was around 8 nm and the core diameter was around 20 nm by TEM.
        4,000원
        48.
        2016.07 구독 인증기관 무료, 개인회원 유료
        Although country-of-origin has been a controversial topic in literature, there has been little research effort to explain the nature linkage between country-of-origin and perceived quality from consumers in emerging markets. Drawing on the notion of country-of-origin, this study proposes the concept of product-country-image which is operationalized with the three components of cognitive, affective and conative. Structural equation modeling is employed to explore the relationship between the product-country-image and perceived quality. The findings indicate that only ‘affective components’ are positively related to ‘conative components’ among three pairs. What is more, structural equitation modeling demonstrated that the influence of product-country image on perceived quality is simultaneously regardless of the level of consumers’ familiarity with a foreign country’s product. Using data collected from 348 Vietnamese consumers, this study generates new insights for academics and practitioners.
        4,500원
        49.
        2016.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Quoc su di bien is a historical book written in Sino language which recorded the events taking place under Nguyen dynasty, from the reign of Gia Long King to the reign of Thieu Tri, and was compiled by Phan Thuc Truc around the 4th to 5th years of Tu Duc title (1851-1852). The work at present has two variants: one of them is the handwritten version code A.1045/1-2 stored in the Institute of Sino – Nom Studies and the other was printed from microfilm, code A.1045/1-2 of the Old French School of the Far East, which was edited by researchers in the Institute of New Asian Studies, Chinese University of Hong Kong and whose Sino language version was produced by Tran Kinh Hoa and printed in 1965 in Hong Kong. When reproducing, Mr. Tran Kinh Hoa tried his best to restore the special Nom and Sino characters of Vietnam and all the unclear cases were marked O for further inspection. However, due to use of scanned materials, there remained a lot of mistakes. The work provided a deep analysis on the mistakes and errors of the version QSDB printed in Hong Kong in order to show that Vietnamese, like some other people influenced by Chinese culture such as Japan and Korea, had created their own Sino character system different from China’s. For proper explanation about the unique Sino character system of each country, the researchers should facilitate themselves with the sound knowledge of national culture, history, language and psychology of such country. Therefore, we may avoid the mistakes due to insufficient knowledge.
        6,900원
        50.
        2016.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The traditional writing of the Vietnamese nation – Nom characters – is a kind of “Sino style” (or so called “Chinese-character-shaped”) “square-shaped” writing system. For more than 100 years, many Vietnamese and foreign scholars have been interested in this writing, discussing and engaging in studying it from different angles. Starting from the philology point of view, the author tries to reveal the issues surrounding “Nom character” studies. They can be attributed to three big topics: 1. The origin of Nom characters and how it became a writing system lasting throughout different historical periods; 2. The internal structures of Nom characters and their evolution; 3. Different stages of Vietnamese philology and the social functions of “Nom characters”. This paper is going to discuss the above-mentioned topics, at the same time as introducing some of the authors’ observations on these topics as references for colleagues.
        4,500원
        51.
        2016.04 구독 인증기관·개인회원 무료
        In Korea, Cryptotympana atrata and Hyalessa fuscata are the most abundant cicada species, and their population densities were 2.8-9.5 times higher in urban areas than in rural areas. It has been suggested that the urban heat island effect (UHI), which is higher temperatures in urban areas than in surrounding areas due to human activities, underlied the population density differences between urban and rural areas. To elucidate the relationship between UHI and cicada population density, we compared cicada population densities in three groups: areas of high and low UHI in metropolitan Seoul as well as areas in the vicinity of Seoul. C. atrata and H. fuscata constituted almost 30% and 70% of the exuviae, respectively, collected across all sampling localities. Moreover, no difference in species composition was observed among groups. The densities of C. atrata and H. fuscata were 14 and 41 times higher in high UHI areas than in low UHI areas. Furthermore, the degree of UHI was significantly correlated with densities of both C. atrata and H. fuscata. In summary, these results support that higher temperatures during the development may cause population increases of C. atrata and H. fuscata.
        52.
        2015.12 구독 인증기관 무료, 개인회원 유료
        This research bases on primary sources written in Sinograph and Nôm (vernacular Vietnamese script) by scholars in premodern Vietnam, to make a pedagogical analysis on the role of the Sanzijing (三字經) in Literary Sinitic education in premodern Vietnam. Thus, this paper claims, the study of the civil service examination in premodern Vietnam should be covered from its starting point, the primary level, to fill the gap of a partial concern by modern scholars of the high level.
        5,800원
        53.
        2015.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The Milky Way did not form in isolation, but is the product of a complex evolution of generations of mergers, collapses, star formation, supernovae and collisional heating, radiative and collisional cooling, and ejected nucleosynthesis. Moreover, all of this occurs in the context of the cosmic expansion, the formation of cosmic laments, dark-matter haloes, spiral density waves, and emerging dark energy. This paper summarizes a review of recent attempts to reconstruct this complex evolution. We compare simulated properties with various observed properties of the Local Group. Among the generic features of simulated systems is the tendency for galactic halos to form within the dark matter filaments that define a super- galactic plane. Gravitational interaction along this structure leads to a streaming ow toward the two dominant galaxies in the cluster. We analyze this alignment and streaming flow and compare with the observed properties of Local-Group galaxies. Our comparison with Local Group properties suggests that some dwarf galaxies in the Local Group are part of a local streaming ow. These simulations also suggest that a significant fraction of the Galactic halo formed at large distances and arrived later along these streaming ows.
        3,000원
        54.
        2015.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        We consider a late decaying dark matter model in which cold dark matter begins to decay into relativistic particles at a recent epoch (z ≤ 1). A complete set of Boltzmann equations for dark matter and other relevant particles particles is derived, which is necessary to calculate the evolution of the energy density and density perturbations. We show that the large entropy production and associated bulk viscosity from such decays leads to a recently accelerating cosmology consistent with observations. We determine the constraints on the decaying dark matter model with bulk viscosity by using a MCMC method combined with observational data of the CMB and type Ia supernovae.
        4,000원
        55.
        2015.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this article, I give a brief description of Bicep2 experiment, and a summary of its result.
        4,000원
        56.
        2015.07 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We present an excellent detection for nitrogen monoxide (NO) gas using polycrystalline ZnO wire-like films synthesized via a simple method combined with sputtering of Zn metallic films and subsequent thermal oxidation of the sputtered Zn nanowire films in dry air. Structural and morphological characterization revealed that it would be possible to synthesize polycrystalline hexagonal wurtzite ZnO films of a wire-like nanostructure with widths of 100-150 nm and lengths of several microns by controlling the sputtering conditions. It was found from the gas sensing measurements that the ZnO wirelike thin film gas sensor showed a significantly high response, with a maximum value of 29.2 for 2 ppm NO at 200 oC, as well as a reversible fast response to NO with a very low detection limit of 50 ppb. In addition, the ZnO wire-like thin film gas sensor also displayed an NO-selective sensing response for NO, O2, H2, NH3, and CO gases. Our results illustrate that polycrystalline ZnO wire-like thin films are potential sensing materials for the fabrication of NO-sensitive high-performance gas sensors.
        4,000원
        57.
        2015.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        말라카해협의 해상교통 안전 확보는 우리나라를 비롯하여 중국, 일본을 포함한 극동아시아의 경제 발전에 직접적인 영향을 미치므로 세계적으로 중요한 해역이다. 이러한 의미에서 이 해역의 해상교통안전을 분석하는 것은 중요한 의미가 있다. 이 연구에서는 말라카해협을 대상으로 TOAIS 프로그램에 의한 선박 AIS 데이터를 1개월 동안 수집하였고, EasyFit 프로그램을 이용하여 해상교통의 통항분포를 통계적으로 분석하였다. 그 결과, 현재까지 해상교통공학 분야에서 선박통항의 분포는 정규분포라고 알려져 사용되고 있었지만, 말라카해협의 해상교통조사 결과 그 통항분포가 정규분포와 상이하다는 것을 확인하였다. 이러한 상이한 해상교통 분포 모델을 적용한 IWRAP모델을 이용하여 이 해역을 평가하였고, 그 결과 추월과 횡단상황이 가장 위험한 것으로 분석되었다. 또한 말라카해협의 충돌위험이 가장 높은 해역은 말라카해협과 포트클랑 해협간 횡단지점으로 분석되었다.
        4,000원
        59.
        2014.09 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Light scattering enhancement is widely used to enhance the optical absorption efficiency of dye-sensitized solar cells. In this work, we systematically analyzed the effects of spherical voids distributed as light-scattering centers in photoanode films made of an assembly of zinc oxide nanoparticles. Spherical voids in electrode films were formed using a sacrificial template of polystyrene (PS) spheres. The diameter and volume concentration of these spheres was varied to optimize the efficiency of dye-sensitized solar cells. The effects of film thickness on this efficiency was also examined. Electrochemical impedance spectroscopy was performed to study electron transport in the electrodes. The highest power conversion efficiency of 4.07 % was observed with 12μm film thickness. This relatively low optimum thickness of the electrode film is due to the enhanced light absorption caused by the light scattering centers of voids distributed in the film.
        4,000원
        60.
        2014.09 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We developed a high-performance methane gas sensor based on a SnO2 hollow hemisphere array structure of nano-thickness. The sensor structures were fabricated by sputter deposition of Sn metal over an array of polystyrene spheres distributed on a planar substrate, followed by an oxidation process to oxidize the Sn to SnO2 while removing the polystyrene template cores. The surface morphology and structural properties were examined by scanning electron microscopy. An optimization of the structure for methane sensing was also carried out. The effects of oxidation temperature, film thickness, gold doping, and morphology were examined. An impressive response of ~220% was observed for a 200 ppm concentration of CH4 gas at an operating temperature of 400˚C for a sample fabricated by 30 sec sputtering of Sn, and oxidation at 800˚C for 2 hr in air. This high response was enabled by the open structure of the hemisphere array thin films.
        4,000원
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