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        검색결과 1,655

        661.
        2014.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study empirically examines how much effect levels of fatigue and stress of a construction worker have on disaster risks from the perspective of human factors concerning construction disaster risks. To achieve the purpose of this study, a survey was conducted with respect to construction workers working at large construction sites within the metropolitan area. The retrieved survey data were analyzed by using the statistical software programs, SPSS 18.0 and AMOS 8.0. The results of this study do not definitively lead to the conclusion that the level of fatigue or stress of construction workers result in disaster risks. However, it does show that the results vary depending upon the individual approach and treatment of stress and fatigue. In particular, this study revealed that disaster risk levels could increase through unsafe behavior intentions which were established as a mediator variable. Also, with respect to unsafe behavior intentions of construction workers leading to disaster risks, when examining the results that the level of mental fatigue, occupational stress and social-psychological stress of construction workers had a greater significant effect than the level of physical fatigue, this study demonstrates the importance of psychological and mental issues that could be easily overlooked with respect manual labor workers.
        4,000원
        662.
        2014.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Due to rapid urbanization and industrialization, water supply and sewer line systems are also developed relevantly. Manhole is an essential component structure of the pipeline system. Manhole is a structure constructed to accommodate the direction, dimension, differences in level, and easy of maintenance in the pipeline system. In this paper we present the result of investigations pertaining to the structural behavior of PVC sewer manhole buried underground. In the paper mechanical properties of PVC material are reported. In addition, by the finite element analysis (FEA), we confirmed that a PVC double-wall corrugated pipe manhole, when it is buried underground, is safe for the stress as well as buckling strength if the manhole is constructed within the suggested limit of buried depth.
        4,000원
        663.
        2014.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study investigates area and size of stress part appeared when the continuous loads are applied at artificial joint. Upper and lower parts composed with polyethylene shock absorber and titanium alloy are applied with the loads. The configurations of stress distribution near the hole of support to fix the frame are investigated and secured as through this study. As the result of this study, the stress is concentrated from the edge end of upper artificial joint. The crack is initiated at this point. This analysis result is similar with the instance of tissue corruption due to the damage of artificial joint.
        4,000원
        666.
        2014.07 구독 인증기관 무료, 개인회원 유료
        Market potential for a line of retail trade within a geographic market has been defined as the difference between (i) actual sales of the line of trade in the geographic market and (ii) potential sales based on the marketing environment, current retailers’ marketing efforts, and competition from related lines of trade and nearby geographic markets (Ingene and Takahashi 2012). In this current research we examine the rate of change of retail market potential in Japan over a sixteen year span (1991-2007).We theoretically address, and empirically estimate, key factors that affect the rate of change of retail sales per household in four major lines of retail trade: frequently purchased consumables (food and drink), less frequently bought non-durables (apparel, shoes and dry goods), and infrequently acquired durable goods that range from moderately costly (furniture) to truly expensive (autos). Information on these lines is drawn from the Japanese Retail Trade Censuses of 1991 and 2007 at the Industrial Classification (IC) level. We examine Dry Goods, Apparel and Accessory stores (largely clothing, shoe, linen and accessories (IC 56; Share of retail trade in 2007: 8%)); Food and Beverage stores (primarily grocery, liquor, and specialty food stores (IC 57; Share of retail trade: 30%)); Furniture, Household Utensils, and Appliances (IC 59; Share of retail trade: 9%); and Motor Vehicles and Bicycle stores (IC 58; Share of retail trade: 12%). Note that because our measure is sales, autos dominate in the IC 58 category. These four lines of trade collectively comprise about 60% (1991: 62%, 2007: 58%) of all retail sales. We previously explored determinants of the absolute value of retail sales per household in these lines of retail trade (Ingene and Takahashi 2013). However, this research deals with the rate of change of retail sales per household. Thus, we explain differences in change of retail market potential among 528 Japanese cities, in all 47 prefectures, that are home to over 75% of Japan’s people. According to our previous study (Ingene and Takahashi 2013), retail sales are determined by three fundamental factors: the Market Environment (which is beyond the control of retail managers), Intertype Competition (which is influenced, but not controlled, by managers in the line of trade), and the Marketing Mix in each line of trade (which is set by managers). The essence of our argument is that the Market Environment determines a base level of rate of change in sales per household. Intertype Competition takes sales away from the focal lines of trade. Finally, the Marketing Mix in each line of trade augments sales (a) by appealing to customers and (b) by countering the negative impact of Intertype Competition.Turning to our empirical model (Figure 1), we include seven variables in the Market Environment that are measured by their rate of change between 1991 and 2007: per capita income, home size in square meters (a proxy for household wealth), population growth, daytime population relative to residential population, auto ownership per capita (a proxy for mobility), distance to the prefecture’s capital city (a proxy for out-shopping), and newspapers per capita. We expect each of these independent variables to increase our dependent variable: retail sales per household.For the Marketing Mix we measure three variables in terms of their rate of change in the same time period: average square meters of selling space per store (a proxy for assortment), employees per square meter of selling space (a proxy for service), and number of stores per 1000 people (a proxy for locational convenience); each of them should increase retail sales per household in its line of trade, but not in other lines (e.g., the marketing mix for Food stores should only affect food sales per household).For Intertype Competition we use General Merchandise Stores (largely department stores and supercenters (IC55; Share of retail trade in 2007: 12%)) that, in Japan, directly compete with Clothing, Furniture and Food stores. We focus on the same three variables (assortment, service, and access); they are expected to be inversely related to the rate of change in sales per household in the lines with which they compete. There is no intertype competition in our Motor Vehicle regressions. In the first stage of our analysis we use the change of the Market Environment to explain the variation in the rate of change in retail sales per household and four lines of trade (i.e., four regressions). The Market Environment generates adjusted R2’s of 2% (Clothing) to 25% (Autos).In our second-stage analysis our dependent variable is the residuals from the first-stage regressions. Here we include the Marketing Mix and Intertype Competition variables as explanatory; they account for 2% (Autos) to 43% (Clothing) of the variation in the first-stage residuals. Taking the two stages together, we are able to explain26% (Autos) to 54% (Food) of the variation in retail sales per capita across the four lines of trade. We make four contributions with our empirical research. First, we investigate data from two censuses that span a sixteen year period; few previous studies have examined changes in retail structure over time (e.g., Hall, et al. 1961). Second, we demonstrate the time-variant stability of the Marketing Mix variables. Third, we show the importance of intertype competition – although in our data it appears that only the Food and Beverage category experiences significant intertype competition. Fourth, we examine retailing in Japan; the world’s third largest economy has rarely been the focus of retail trade studies.
        4,000원
        667.
        2014.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Recently, there are a lot of fires breaking out at special structures. To suppress this fire break down at early stage is very important because it leads to bigger damage in case of special structures. For early suppression, outer wall of building has to be destroyed and need waterproofing for Ignition temperature. So far there is no equipment developed local and all of them are imported from a broad. In this study, In this study, The CAE analysis was the Leading-in of the boom conditions for the development of demolition fire according to the environment of Korea. As a result of this, could be confirmed that decreases stress reduction. maximum 51% to 12% depending on the part. It was possible structural integrity and design. about Telescopic Boom and Outrigger on the basis of this result.
        4,000원
        668.
        2014.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        ‘In structural system, a certain amount of uncertainties always persists in material properties, geometric parameters and applied loads. In this study, the structure is designed to withstand the uncertainties which are caused by either measurement inaccuracy or system complexity. Random structures are modelled by using ANSYS probabilistic design module. It can be applied easily to any structural system with random parameters. The aim of this paper is to make optimal design for the beam with random input variables due to width and height and response parameters due to displacements and stresses. The probabilistic design is also carried out with ANSYS APDL and then the optimal design is sequentially solved. As the total volume of beam, stresses and displacements at the beam are treated as random parameters, the numerical results are obtained.'
        4,000원
        669.
        2014.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 논문에서는 노심용융사고 시 관통노즐이 제거된 원자로용기 하부헤드의 구조 건전성 평가를 수행하였다. 열응력, 노심용융물의 질량 그리고 내압조건의 해석결과를 고려할 때, 하부헤드의 열응력에 의한 영향이 가장 크게 나타났다. 손상 가능성은 파손기준에 따라 평가하였으며, 등가소성변형률이 임계변형률 파손기준보다 낮은 수준으로 평가되었다. 열-구조물 연성해석 결과 하부헤드의 두께 중간층에서 항복강도보다 낮은 응력이 발생한 탄성영역 구간을 확인하였다. 내압이 커지면서 탄성영역 범위가 점차 좁아지면서 탄성영역이 내벽으로 이동하는 결과를 확인하였고, 노심용융사고 시 구조적 건전성을 만족하는 것으로 평가되었다.
        4,000원
        670.
        2014.06 구독 인증기관 무료, 개인회원 유료
        우리나라 농가용 도정기의 구조요인과 도정성능을 분석하기위하여, 판매되고 있는 농가용 도정기 29개 모델을 이용하여제현장치와 정미장치로 분류하였고, 각 장치별로 구조적 특징을 조사하였고 그 결과를 바탕으로 성능요인을 분석하였다.제현장치는 임펠러 회전속도가 주요 구조적 요인으로 조사되었으며, 4,800rpm의 임펠러 회전속도가 65.5%로 가장 많이사용하고 있는 것으로 나타났다. 이 회전속도에서 탈부율이99.45%로 가장 높게 나타났고, 현미동할립율이 가장 낮게 나타나 제현성능에 가장 좋은 임펠러의 회전속도는 4,800rpm인것으로 분석되었다(p<0.05). 정미장치는 로터 선속도가 주요구조적 요인으로 조사되었으며, 2m/s의 로터 선속도가 60.1%로 가장 많이 사용하고 있는 것으로 나타났다. 이 선속도에서도정수율이 75.07%로 가장 높게 나타났고, 유실곡비율과 싸라기율이 각각 0.02%, 7.06%로 가장 낮게 나타나 정미성능에가장 좋은 로터의 선속도는 2 m/s인 것으로 분석되었다(p<0.05).
        4,000원
        671.
        2014.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The stone pagoda of Mireuk temple site is currently restoring through the repairing process. This stone pagoda has the various construction types in the inner and outer space. Therefore, the stress concentration and structural behavior need to be considered through the analysis of various construction patterns. To this end, this study presents the structural modelling and analysis considering the discrete element analysis technique to solve the discontinuum behavior between the stone elements. Also, this study performs the structural performance evaluation through the various design variables for the safety of stone pagoda. Through the analysis results, we can find out the small stress concentration in the several members. But, because the stresses and displacements are relatively small, we can secure the safety of the whole structure.
        4,000원
        672.
        2014.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Main topics in this study is a new structural detail for connection between H-Steel or SRC column and flat plate slab. We carried out to evaluate the punching shear performance of H-steel or SRC column + RC slab system for vertical load and lateral load. From the test results structural characteristics - yield moment, yield rotation, maximum moment, deformation capabilities ect. - are obtained and evaluated. In this paper as a shear reinforcement for supporting region of plate closed stirrup type and shear band are used, and their test results are compared.
        4,000원
        675.
        2014.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Double walled carbon nanotubes (DWCNTs) are considered an ideal model for studying the coupling interactions between different concentric shells in multi-walled CNTs. Due to their intrinsic coaxial structures they are mechanically, thermally, and structurally more stable than single walled CNTs. Geometrically, owing to the buffer-like function of the outer tubes in DWCNTs, the inner tubes exhibit exciting transport and optical properties that lend them promise in the fabrication of field-effect transistors, stable field emitters, and lithium ion batteries. In addition, by utilizing the outer tube chemistry, DWCNTs can be useful for anchoring semiconducting quantum dots and also as effective multifunctional fillers in producing tough, conductive transparent polymer films. The inner tubes meanwhile preserve their excitonic transitions. This article reviews the synthesis of DWCNTs, their electronic structure, transport, and mechanical properties, and their potential uses.
        4,300원
        676.
        2014.04 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Metallic Cr film coatings of 1.2μm thickness were prepared by DC magnetron sputter deposition method on c-plane sapphire substrates. The thin Cr films were ammoniated during horizontal furnace thermal annealing for 10-240 min in NH3 gas flow conditions between 400 and 900˚C. After annealing, changes in the crystal phase and chemical constituents of the films were characterized using X-ray diffraction (XRD) and energy dispersive X-ray photoelectron spectroscopy (XPS) surface analysis. Nitridation of the metallic Cr films begins at 500˚C and with further increases in annealing temperature not only chromium nitrides (Cr2N and CrN) but also chromium oxide (Cr2O3) was detected. The oxygen in the films originated from contamination during the film formation. With further increase of temperature above 800˚C, the nitrogen species were sufficiently supplied to the film's surface and transformed to the single-phase of CrN. However, the CrN phase was only available in a very small process window owing to the oxygen contamination during the sputter deposition. From the XPS analysis, the atomic concentration of oxygen in the as-deposited film was about 40 at% and decreased to the value of 15 at% with increase in annealing temperature up to 900˚C, while the nitrogen concentration was increased to 42 at%.
        4,000원
        677.
        2014.04 구독 인증기관 무료, 개인회원 유료
        Recently, environmental problems associated with the excessive use of fossil fuel are hot issue throughout the world. As an alternative energy resource, the importance of renewable energy is continuously rising. Especially, growth rate of photovoltaic energy generation is one of the best. In this paper, floating PV generation system made of pultruded fiber reinforced polymeric plastic (PFRP) is discussed. It is well known that PFRP has many advantages such as high corrosion resistance, high specific strength/stiffness, etc. Compared with conventional construction materials. To investigate the structural behavior under flow induced dynamic loading, members and connections of members are tested under cyclic loading. It was found that the structural system is strong enough to resist such a cyclic loading.
        3,000원
        678.
        2014.04 구독 인증기관·개인회원 무료
        To inject CO2 in geological formations, deep wells that penetrate the formations need to be constructed. The seal integrity of deep wells for CO2 leakage are enhanced by annulus cements. By injecting CO2, brine in formations can be carbonated and the potential degradation of annulus cement in the carbonated brine has been brought up. In this paper, Type G oil well cement (OWC) pastes are hydrated for 28 days. Conditions of geosequestration in a sandstone formation at a depth of roughly 1 km, was simulated by bubbling CO2 into a heated vessel containing brine. The hydrated OWC cylindrical specimens were exposed to this environment. Slices of the cement specimen were taken periodically, during and after exposure to quantify degradation progression. The elastic modulus of the specimens was examined prior to and after exposure. After 28 days of exposure, the degraded depth of specimen was measured as 4.137 mm. The elastic modulus of the specimens was measured as 2.2 GPa and 3.2 GPa prior to and after exposure respectively. Considering a composite action in the partially degraded specimen, the elastic modulus of degraded part can be extracted. The results indicated that the difference of elastic modulus in the partially degraded annulus cements could occur a composite action of deep wells subject to axial load and shear cracks would be generated due to the composite action.
        679.
        2014.04 구독 인증기관·개인회원 무료
        Risers are often exposed to harsh ocean environments, and vulnerable to various damages. The riser failure may cause serious economical losses as well as environmental problems. Therefore, maintaining the structural integrity of the riser is very important. This paper deals with the methodology for monitoring structural integrity of the riser using dynamic characteristic changes such as mode shapes. The damage index method, which has been proved its usefulness in many applications, is applied to a numerical study to test its feasibility of identifying damage in a riser. The numerical study is performed using OcraFlex 9.4, specialized program for analyzing marine structures. The numerical study shows that the damage index method can identify damage in the riser.
        680.
        2014.04 구독 인증기관·개인회원 무료
        Acetylcholinesterase (AChE) plays a pivotal role in the synaptic transmission in the cholinergic nervous system of most animals, including insects. Most insects possess two AChEs (i.e., AChE1 vs. AChE2), which are encoded by two paralogous loci originated from the duplication that occurred before the radiation of insects. The phylogenetic analysis suggested that the last common ancestor of ace1 and ace2 shared its origin with those of Platyhelminthes. In addition, ace1 lineage showed a lower evolutionary rate (d and dN/dS ratio) compared to ace2 lineage, suggesting that the ace1 lineage has maintained relatively more essential functions following duplication. Furthermore, structural modeling of AChEs revealed that consistent structural alteration in their active-site gorge topology was caused by amino acid substitution, likely leads to functional differentiation between two AChEs. The functional transition of ace in some hymenopteran insects appears to have occurred by only a few mutations resulting in dramatic alteration of AChE activity. Taken together, our findings provide basic information on when the ace duplication occurred and what structural features have been associated with the differentiation of two AChEs during evolution.