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        검색결과 204

        141.
        2001.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 논문은 도로의 선형이 곡선일때, 곡선상에 설치되는 곡선교를 해석함에 있어 에너지법에 기초하여 휨과 순수비틂 효과를 고려한 탄성방정식을 이용한다. 이 탄성방정식은 부정정 구조인 연속곡선박스거더의 정역학적 부정정력을 최소 일의 원리를 적용하여 구한다. 곡선박스거더에 수직단위하중과 단위토크를 작용시켜 전단력, 휨모멘트, 순수비틂모멘트, 그리고 처짐과 회전각에 대한 영향선을 구하며, 실제 하중이 작용할 때 곡선박스거더의 부재력을 구할 수 있도록 하였다.
        4,300원
        142.
        2000.07 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Fe-Ni-Cr 합금의 용융염 부식거동을 650~850˚C 온도범위에서 조사하였다. 용융염 LiCl에서 Cr을 포함하지 않는 KSA(Kaeri Superalloy)-1 합금은 Fe의 내부산화가 발생하고, Cr을 포함한 KSA-4, Incoloy 800H와 KSA-5는 LiCrO2의 치밀한 보호막이 형성되었다. 혼합용융염 LiCl-LiO2O에서 KSA-1은 Fe의 내부산화, KSA-4는 Cr의 내부산화가 발생하였고, Cr 농도가 높은 Incoloy 800H와 KSA-5는 LiCrO2의 다공성 피 이 형성되었다. 혼합용융염 LiCl-Li2O 에서는 Cr 농도의 증가에 따라 부식속도가 증가하였으며, 부식속도는 시간의존선을 8%Cr 이하의 합금에서는 포물선법칙, 8%Cr 이상의 합금에서는 직선법칙을 나타내었다. 이러한 현상은 Li2O에 의한 보호성 산화물 Cr2O3의 염기성 용해기구로 설명할 수 있다.
        4,000원
        143.
        2000.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This experiment was undertaken to investigate the effect of administration of Agyoju or Mokhyang on the maintenance of pregnancy, delivery and sex ratio in the mice in different gestation periods. Adult female mice were administered orally at three different periods, from ovulation to implantation (Exp.1), from post-implantation to organogenesis (Exp.2), and from fetal growth to parturition (Exp.3). In Experiment 1, number of fetus implanted and mean body weight were not significantly different. However, the delivery of male offspring was significantly increased in Agyoju and Mokhyang administrated groups than control group. In Experiment 2, the number of fetuses implanted, live offsprins and their body weight at delivery were significantly increased in the Agyoju administered group than Mokhyang and control groups. In Experiment 3, the number of live offspring and sex ratio were not different in both treatments and control group. However, mean body weight at delivery was significantly increased in both treatment groups than that of control group. These results suggest that 1) Agyoju and Mokhyang have beneficial effects in maintenance of pregnacy, and that 2) The action of unknown component(s) in Agyoju may be related to selection of male spermatozoa for fertilization in vivo, and that 3) the administration of Agyju of Mojhyang during mid-and late-pregnance periods were shown the increment of body weight of live offspring without decrease of litter size.
        4,000원
        144.
        1999.10 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Incoloy 800H, KSA (Kaeri Superalloy)-6, Inconel 600 및 Hastelloy C-276 합금의 용융염에서의 부식거동을 650~850˚C 온도범위에서 조사하였다. LiCl-Li2O혼합용융염에서의 부식은 Li2O에 의한 염기성 용해 기구에 의해 진행되며, 부식속도가 LiCl에서보다 훨씬 빠르게 나타났다. 혼합용융염 LiCl-Li2O에서는 Ni기 합금의 부식속도가 Fe기 합금보다 빠르고, Mo와 W의 함량이 높은 Hastelloy C-276이 가장 빠른 부식속도를 나타내었다. 용융염 LiCl에서는 LiCrO2의 단일 부식층이 형성되고, LiCl-Li2O 혼합용융염에서는 산화물과 Ni의 2상구조의 다공성 부식층이 형성되었다.
        4,000원
        146.
        1998.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        본 연구에서는 졸-겔공정에 의해 금속 alkoxide용액을 이용하여 강유전성 PMN분말 및 박막을 제조하였다. PMN박막은 dip coating 방법으로 Pt가 피복된 Si 기판 위에 제조하였다. 열처리에 따른 gel 분말의 유기물 분해거동과 제조된 분말 및 박막의 열처리 온도변화에 따른 결정상 발달과정을 열분석, 적외선 및 Rarnan 분광분석과 X-선회절분석을 통하여 규명하였다 또한 과잉의 PbO와 MgO 첨가가 PMN박막의 Perovskite 결정상 생성에 미치는 영향을 고찰하였다. Pt가 피복된 Si기판 위에 5회 코팅으로 제조된 PMN박막의 820˚C에서 1분간 열처리 후 두께는 약 3000 이였다 PMN 박막 제조시, 15% 과잉의 PbO를 첨가하고 1분간 820˚C에서 열처리한 경우에 단일상의 Perovskite상을 얻을 수 있다. 고상반응에서와 같이 액상반응인 sol-gel공정에서도 과잉의 MgO (10mo1% ) 첨가가 Perovskite상의 생성을 증가시키는 것을 확인하였다 Pt가 피복된 Si기판 위에 제조된 PM N박막을 820˚C에서 1분간 열처리하였을 경우에 제조된 PM N박막의 유전상수 값과 손실계수는 10kHz주파수에서 각각 2200~2700 및 -0.33의 값을 나타내었다.
        4,000원
        147.
        1997.01 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        급냉응고법을 이용하여 고용한도 이상으로 Mn량을 첨가할 때 Mn량에 따른 인장특성의 변화와 시효특성을 조사하였다. 원심분무법으로 AI-4.7%Zn-2.5%Mg-0.2%Zr합금에 Mn량을 각기 달리 첨가한 급냉응고 분말을 제조 하였다. 이 분말을 냉간압축, 진공 탈가스처리를 한 후 15:1로 압출하여 봉상 시편을 만들었다. 분말의 미세조직은 α-AI수지상과 수지상간 편석부로 이루어져 있으며 Mn첨가에 따라 조직의 변화는 관찰되지 않았다. 빠른 냉각속도로 인하여 2.0%Mn을 첨가한 경우에도 초정 Mn상을 발견할 수 없었다. 압출재의 미세조직은 아결정립으로 이루어져 있으며 약간의 제2상들이 관찰되었다. 대부분의 Mn 분산상은 압출후 용체화처리 과정에서 형성되었으며 시효경화량은 Mn양에 관계없이 일정하였다. 460˚C에서 1시간 용체화처리하고 120˚C에서 24시간 시효처리한 경우 최대의 시효경도값을 나타내었다. 인장강도는 Mn첨가량에 따라 증가 하였는데 이것은 Mn분산상의 밀도증가에 의한 것으로 확인되었다. 2.0%Mn을 첨가한 합금의 시효후 인장강도는 590MPa, 연산율은 4%를 보였다.
        4,000원
        148.
        1996.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Sprague-dawley 흰쥐를 고지방식이로 6주간 식이하면서 영지열수추출액을 경구투여하여 혈장, 간장 및 부고환조직에서 지방성분, 지단백질의 분포, 변 중의 담즙산과 중성스테롤들의 배출량을 측정하여 다음과 같은 결과을 얻었다. 고지방식이와 영지(GL군)열수추출액을 투여한 흰쥐의 혈청 중 총콜레스테롤, 중성지질 및 유리지방산의 농도는 고지방식이로만 사육한 대조군(CON군)에 비해 낮았다. 한편 인지질과 HDL-cholesterol의 농도는 다소 높았다. 또한 간장과 부고환의 지방성분들을 조사한 경우에도 위와 같은 결과를 얻었다. Low density lipoprotein(LDL)과 very low density lipoprotein(VLDL)은 고지방식이가 급여되는 동안 정상군 보다 대조군에서 증가하였고 영지투여군은 대조군에 비하여 LDL과 VLDL은 감소하였으나 HDL은 증가하였다. 그리고 분변을 통한 답즙산과 중성스테롤의 배설량이 증가하였다. 이상의 결과를 종합해 보면 영지 투여군이 지방축적 및 고지혈증의 완만한 개선경향을 나타내고 있음을 알 수 있다.
        4,000원
        151.
        2020.03 KCI 등재 서비스 종료(열람 제한)
        Alternative navigation in underwater environments is essential to prevent accumulating drift error of dead reckoning. In case of using an external positioning system, the installation and management process of the transmission station is cumbersome, and the operation range of underwater vehicle is limited. In order to solve this problem, navigation using geophysical information such as terrain, geomagnetic field and gravity can be used. Unlike the terrain, geomagnetic field and gravity are composed of 3-D information, so continuation process is required. In this paper, we present a integrated navigation algorithm using multiple geophysical information for long-term operation of UUV. The proposed algorithm is verified through numerical simulation in an artificially generated environments. As a result, integrated navigation showed higher navigation accuracy than single alternative navigation.
        152.
        2019.10 서비스 종료(열람 제한)
        본 연구는 직물섬유의 배치에 따른 직물섬유 보강 콘크리트의 휨 특성을 알아보기 위하여 세 가지 변수에 대하여 휨 실험을 수행하였다. 복합체의 인장부에 근접한 위치에 직물섬유가 배치될 경우 극한하중이 증가하는 것으로 나타났다.
        153.
        2019.03 KCI 등재 서비스 종료(열람 제한)
        Purpose - With the economic development in China, the lifestyle of Chinese customers has changed dramatically. Chinese customers are more likely to have coffee in a shop with the ability to make them happy than those with high quality coffee in a nice physical environment. Happiness becomes a critical driver of customers’ intention to purchase a cup of coffee in a specific coffee shop again and again. As a result, happiness becomes an important factor for managers to make strategies for attracting customers. Although managers and scholars pay more attention to emphasize the importance of happiness in customers’ consumption, little research has been conducted to investigate the relationship between happiness and coffee shop’s continuous usage intention in the Chinese coffee industry. Research design, data, and methodology – A research model is made to explain the impact of happiness on customer’s behavior. To understand the influence of happiness better, we consider two dimensions of happiness which are subjective well-being and psychological well-being. In order to confirm the relationships of the variables in the research model, the online survey is constructed in China. Customers who have experienced the services in a coffee shop are asked to do the questionnaire. With 453 reliable questionnaires, structural equation modeling is used to analyze the causal relationships of the coffee quality, physical environment, subjective well-being, psychological well-being, and continuous usage intention. Results - Results indicate that coffee quality and physical environment are not the direct factors that influence customers’ continuous usage intention. However, good coffee quality and physical environment are the significant predictors of Chinese customers’ happiness associated with subjective well-being and psychological well-being, which in turn affects customers’ continuous usage intention. Conclusions - In this study, it is proposed that coffee quality and physical environment may be the key factors influencing customers’ happiness. Happiness, including subjective well-being and psychological well-being matters in decision making process. More importantly, happiness increases the continuous usage intention when the coffee shop can serve customers with higher quality coffee at a good atmospheric place. Managers should consider happiness as an important factor in making marketing strategies to compete in this industry.
        154.
        2018.10 서비스 종료(열람 제한)
        In this paper, a tuned mass damper is applied to improve the seismic performance of the lighting tower. The light tower has a high slenderness ratio, low lateral stiffness and top mass is large structure so this has weak for vibration characteristics. The optimized damping coefficient and stiffness were applied to the four lighting tower models analyzed. As a result, the light tower with TMD showed a tendency to reduce the displacement response significantly against the earthquake.
        155.
        2018.10 서비스 종료(열람 제한)
        The paper presents the damage estimation of bridge structures in Daegu city based on the scenario-based earthquakes. Since the fragility curves for domestic bridge strucures are limited, the Hazus methodology is employed to derive the fragility curves and estimate the damage. A total of four earthuquake scenarios near Daegu city are assumed and structure damage is investigated for 81 bridge structures. The seismic fragility function and damage level of each bridge had adopted from the analytical method in HAZUS and then, the damage probability using seismic fragility function for each bridge was evaluated.
        156.
        2018.10 서비스 종료(열람 제한)
        The paper presents the experimental investigation on the flexural behavior of Textile Reinforced Concrete (TRC) composite pannel. This new composite material has been developed to improve the structural performance of RC columns. The mechanical behavior under static loading of the composite elements is evaluated through the flexural testing. The first set of specimens was a normal concrete element without the textile. The second set of specimens was strengthened by 3D textile fabric. Testing data are analyzed to investigate the performance of the 3D textile reinforced concrete specimens compared to the performance of the normal elements.
        157.
        2018.06 KCI 등재 서비스 종료(열람 제한)
        Purpose - With the rapid economic development, great changes have happened in the Chinese beer market. The scale of imported beer is increasing. However, the sales of native Chinese beer decrease in recent years. It is because more Chinese customers prefer beer with unique attributes than those with lower prices. In order to take an advantage in this market, practitioners should develop new products to satisfy Chinese customers. Scholars have also focused on beer characteristics to estimate consumers’ behavior for improving the development of beer industry. However, most studies are theoretically centered on marketing strategy management or general understanding of the market. It is not enough for us to explain customers’ consumption patterns. Some empirical research did attempt to find out beer attributes that may influence their choice behavior. However, they failed to verify what can increase customers’ utility through a new product. More importantly, few evidences can be found in the literature. Therefore this study explores the major characteristics of imported beer which may associate with customers’ preferences. Research design, data, and methodology - With the results of literature review and focus group interview, we found out four main imported beer attributes and the levels of each factor. A pre-test is constructed to check the problems in the questionnaire protocol. With the results of pre-test, the revised questionnaire is processed among customers who have purchased and had imported beer in China regions such as Beijing, Shanghai, Jiangsu, Guangdong and so on. The choice-based conjoint analysis is applied to analyze the useful data of 205. Results - Results indicate that choice-based conjoint analysis is the effective method to estimate customers’ choice behavior. Results also indicate that country of origin, price, taste, and package affect customers’ preference and the importances of imported beer attributes are significantly different. Conclusions - Country of origin, price, taste, and package are important for customers to make an imported beer choice decision. Marketers should consider these determinants and their importance to develop new products. Moreover, choice-based conjoint analysis should be the useful method for practitioners to develop a new product of imported beer for sustainable business in the competitive industry.
        158.
        2018.04 서비스 종료(열람 제한)
        The target in the design of base isolated structures is the selection of isolation system properties so that optimal performance is achieved among seismic levels and performance metrics. To withstand very rare ground motions, isolation system are frequently designed with significant strength or damping, and as a result such devices provide reduced isolation effect for more frequent seismic events. To investigate improvements to the design of isolated structures, a lot of research program is performed. Experimental investigations are presented to characterize smart base isolation capable of progressively exhibiting different hysteretic properties at different stages of response. Shear tests are conducted along the ISO standard, including harmonic characterizations tests. These tests included various input intensities, multi-component excitation. Behavior of the new smart base isolation system is compared with that of linear isolation systems with both nonlinear viscous and bilinear hysteretic energy dissipation mechanisms.
        160.
        2018.02 KCI 등재 서비스 종료(열람 제한)
        This study analyzes the management performance of environmentally-friendly rice farms using GCM method based on the multifaceted approach. This approach compares the management performance of GCM farms before and after the introduction of GCM, as well as the performance of GCM farms with the performance of conventional farms. It also compares the technical and managerial competence level of surveyed GCM farms with that of conventional farms based on the standard diagnosis table developed by Rural Development Adminstration. Results showed that average income has increased after the introduction of the GCM method and the average income of GCM farms was higher than that of conventional farms, while the level of rice production in farms using GCM method was lower than that of conventional farms. In addition, the technical and managerial competence score of surveyed farms using GCM method was higher than that of conventional farms. These results implies that the higher management performance of GCM farms compared to the conventional farms is attributed to not only the GCM method but also the competence level of farms using GCM method.