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        검색결과 553

        162.
        2017.10 구독 인증기관·개인회원 무료
        In recent 10 years, mushroom cultivation area and number of cultivators have decreased, but mushroom production tends to increase. This shows that mushroom cultivation is being transformed from log and bed cultivation to bottle cultivation using automated facilities with high productivity per unit area. The bottle cultivation is possible to mechanized and automated, which can save manpower, less damage to pests, can be cultivated throughout the year, and is uniform in quality and advantageous for mass production. However, the investment in production facilities and farm materials is very large compared to the production of logs and bed cultivars, which can lead to large losses in the case of failure to grow. Therefore, it is necessary for the farmers who want to start the bottle cultivation to make careful management decisions by carefully examining the investment cost, the operating cost, and the expected income that are put into the bottle cultivation system. This study was conducted to analyze the management performance of bottle cultivation in mushroom farm and use it as farming decision making data. As a result of analysis of the management performance through farmers' survey, it was found that such as cost of spawn, substrate materials, other material, employment effort, and fuels & electricity power cost accounted for a large proportion of the cost of bottle cultivation.
        163.
        2017.07 구독 인증기관 무료, 개인회원 유료
        This study aims to examine how the mobile social network service experience affects value co-creation and customer lifetime value. The mobile social network service experience includes mobile convenience, social compatibility, social risk, and cognitive effort. The research hypotheses with structural equation modeling are tested. In mobile SNS context, value co-creation behaviors essentially determine customer lifetime value of mobile shopping apps. Value co-creation behaviors have received little attention in mobile shopping. The mobile SNS experience strongly influences value co-creation behaviors. This study is based on a sample of mobile SNS users nationwide in Korea. Therefore, the generalizability of the findings has to be tested. Furthermore, the study examines customer lifetime value, which is good sales predictor of mobile shopping apps. Moreover, the research model included the positive and negative determinants on mobile SNS experience. Future researches examine other use intentions of mobile SNS. Value co-creation behaviors substantially affect customer lifetime value. Mobile shopping apps should increase customer lifetime value from mobile SNS experience and value co-creation. This study shows how individual mobile SNS user provides mobile shopping apps with profit through value co-creation. This study is the first to examine how mobile SNS users enhance value co-creation and how value cocreation behaviors affect customer lifetime value of mobile SNS users.
        4,000원
        164.
        2017.07 구독 인증기관·개인회원 무료
        The advanced information technology leads to network age, making existing competitive advantages such as differentiation and cost leadership powerless in B2B context. The competitiveness of individual firm plays a significant role in enhancing the competitive advantage of a business network that a firm belongs to. The competitiveness of a business network depends on value co-creation, the interaction among firms in a network. Value co-creation has desirable and risky aspects. The increases in profits, brand reputation, and time and cost efficiency, client and supplier learning, etc. are positive aspects. But role conflicts, role ambiguity, and tension, etc. are negative outcomes. How can the industrial firm succeed in value co-creation with its partners in B2B context? The study focuses on the firm’s strategic marketing orientations as an antecedent of value co-creation. Strategic marketing orientations as the values and beliefs of the firm affect the collaboration with other firms during value co-creation. Previous literature assumes that a firm pursues one single strategic orientation. However, the study assumes that an industrial firm has entrepreneurial orientation, market orientation, long-term orientation, and relationship orientation. The study mostly focused on the relationships among those strategic marketing orientations. Based on these inter-relationships, the study proposed a set of value co-creation activity criteria such as information seeking, information sharing, personal interaction, responsible behavior, feedback, helping, advocacy, tolerance. Value co-creation has been evaluated by relationship performance such as trust and commitment. The study examined the relationships between strategic marketing orientations and value co-creation. Data was collected from 159 Korean manufacturers in B2B context and analyzed through structural equation modeling. The study provides evidence that entrepreneurial orientation affects market orientation positively and market orientation has positive effects on long-term orientation and relationship orientation, and long-term orientation and relationship orientation influence value co-creation directly. Value co-creation has a positive effect on relationship performance. The results of the study provide valuable implications to the mangers of industrial firms in B2B context. To succeed the value co-creation, the firm first has to look at the difference between strategic marketing orientations that the value co-creation partners pursue. In terms of selecting value co-creation partner, industrial firm with long-term orientation and relationship orientation will be more effective. Six activities of interactions during value co-creation play an important role in enhancing trust and commitment. The study contributes to the value co-creation literature by identifying strategic marketing orientations as independent variable influencing the value co-creation in B2B context. The study has several limitations that call for future research.
        165.
        2017.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The compressive strength and electrical resistance of pitch-based carbon fiber (CF) in cementitious materials are explored to determine the feasibility of its use as a functional material in construction. The most widely used CFs are manufactured from polyacrylonitrile (PAN-based CF). Alternatively, short CFs are obtained in an economical way using pitch as a precursor in a melt-blown process (pitch-based CF), which is cheaper and more eco-friendly method because this pitch-based CF is basically recycled from petroleum residue. In the construction field, PAN-based CFs in the form of fabric are used for rehabilitation purposes to reinforce concrete slabs and piers because of their high mechanical properties. However, studies have revealed that construction materials with pitch-based CF are not popular. This study explores the compressive strength and electrical resistances of a cement paste prism using pitch-based CF.
        4,000원
        167.
        2017.04 구독 인증기관·개인회원 무료
        Entomopathogenic fungi have been used as important part of integrated pest management program to control aphid. In particular, Beauveria bassiana was distributed throughout the world including temperate and tropical area, various habitats from alpine soil, desert soil to running water and both insect and plant. Especially the fungus has also been isolated from the surface and the interior of plants and act as natural control agent. Viability of fungi on the plant surface may be influenced by temperature, humidity, sunlight and plant type as well as fungal isolate. Persistence of treated fungal control agent on phylloplane and control efficacy may differ from environmental conditions and isolates. In this study, we investigated the persistence of an B. bassiana which is developing as prototype wettable powder to control cotton aphid, and the residual efficacy of the prototype on cucumber under three different greenhouse conditions.
        168.
        2017.03 구독 인증기관 무료, 개인회원 유료
        Background: Periodontitis is an inflammatory disease characterized by the breakdown of tooth-supporting tissues, leading to tooth loss. Aggregatibacter actinomycetemcomitans are major etiologic bacterium causing aggressive periodontitis. Ursodeoxycholic acid (UDCA), a hydrophilic gall bladder acid, has been used as an effective drug for various diseases related to immunity. The aim of this study was to investigate the effect of UDCA on the inflammatory response induced by A. actinomycetemcomitans. Methods: A human acute monocytic leukemia cell line (THP-1) was differentiated to macrophage- like cells by treatment with phorbol 12-mystristate 13-acetate (PMA) and used for all experiments. The cytotoxic effect of UDCA was examined by MTT assay. THP-1 cells were pretreated with UDCA for 30 min before A. actinomycetemcomitans infection and the culture supernatant was analyzed for various cytokine production by ELISA. The effect of UDCA on bacterial growth was examined by measuring optical densities using a spectrophotometer. Results: UDCA showed no cytotoxic effect on THP-1 cells, up to 80 μM Ed highlight: Please confirm technical meaning. UDCA pretreatment inhibited the A. actinomycetemcomitansinduced IL-1β, TNF-⍺, and IL-17A secretion in a dosedependent manner. UDCA also inhibited IL-21 production at 60 μM. The production of IL-12 and IL-4 was not influenced by A. actinomycetemcomitans infection. Conclusion: These findings indicate that UDCA inhibits the production of inflammatory cytokines involved in innate and Th17 immune responses in A. actinomycetemcomitansinfected THP-1- derived macrophages, which suggests its possible use for the control of aggressive periodontitis.
        4,000원
        169.
        2017.03 구독 인증기관 무료, 개인회원 유료
        Background: Periodontitis is generally a chronic disorder characterized by the breakdown of tooth-supporting tissues. P. gingivalis, a Gram-negative anaerobic rod, is one of the major pathogens associated with periodontitis. Frequently, P. gingivalis infection leads to cell death. However, the correlation between P. gingivalis–induced cell death and periodontal inflammation remains to be elucidated. Among cell deaths, the death of immune cells appears to play a significant role in inflammatory response. Thus, the aim of this study was to examine P. gingivalis–induced cell death, focusing on autophagy and apoptosis in THP-1 cells. Methods: Human acute monocytic leukemia cell line (THP-1) was used for all experiments. Autophagy induced by P. gingivalis in THP-1 cells was examined by Cyto ID staining. Intracellular autophagic vacuoles were observed by fluorescence microscopy using staining Acridine orange (AO); and 3-methyladenine (3-MA) was used to inhibit autophagy. Total cell death was measured by LDH assay. Cytokine production was measured by an ELISA method. Results: P. gingivalis induced autophagy in an MOI-dependent manner in THP-1 cells, but 3-MA treatment decreased autophagy and increased the apoptotic blebs. P. gingivalis infection did not increase apoptosis compared to the control cells, whereas inhibition of autophagy by 3-MA significantly increased apoptosis in P. gingivalis-infected THP-1 cells. Inhibition of autophagy by 3-MA also increased total cell deaths and inflammatory cytokine production, including IL-1β and TNF-⍺. Conclusion: P. gingivalis induced autophagy in THP-1 cells, but the inhibition of autophagy by 3-MA stimulated apoptosis, leading to increased cell deaths and pro-inflammatory cytokines production. Hence, the modulation of cell deaths may provide a mechanism to fight against invading microorganisms in host cells and could be a promising way to control inflammation.
        4,000원
        170.
        2016.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Free radicals originate due to the radiolysis of cytoplasmic water with low “Linear Energy Transfer” (LET) radiations. Naringenin (Ng) is a natural antioxidative compound found in citrus fruits. This study revealed that Naringenin (Ng) reduced the radiation damage of critical organs by scavenging oxidative free radicals. In the study, Ng was orally administrated to rats daily for 7 consecutive days, prior to whole body exposure to gamma-rays. The scavenging efficacy was evaluated biochemically by measuring the concentration of cytotoxic byproducts and the activity of enzymes relevant to oxidative free radicals, after extracting the organs from the exposed rat. We observed increased levels of malondialdehyde (MDA) concentration, and decrease in the activities of superoxide dismutase (SOD) and catalase (CAT) in the exposed control group. However, pretreatment with Ng significantly reduced the MDA concentration, and increased the activities of SOD and CAT, as compared to the control group, due to the free radical scavenging by Ng. The results indicate that Ng administration prior to irradiation could protect critical organs from radiation damage.
        4,000원
        171.
        2016.12 구독 인증기관 무료, 개인회원 유료
        Interleukin-1b (IL-1β), a proinflammatory cytokine, regulates the innate immune responses against bacterial infection. Mature IL-1β is produced from pro-IL-1β by activated caspase-1, which in turn is activated by the inflammasome complex formation. In this study, we compared the inflammasome mRNA expression induced by S. sanguinis, S. oralis, F. nucleatum and P. intermedia. Among the tested bacteria, S. sanguinis induced the highest IL-1β secretion. S. oralis, F. nucleatum and P. intermedia induced very weak IL-1β secretion. S. sanguinis mostly induced the NLRP3 mRNA expressions. Although F. nucleatum did not induce high IL-1β secretion, it induced high expression levels of AIM2, NLRP2, and NLRP3. No specific inflammasomes were induced by S. oralis and P.intermedia. Studying the inflammasome complex activation induced by oral bacteria may thus enhance our understanding of the pathogenesis of oral diseases.
        4,000원
        179.
        2016.10 구독 인증기관·개인회원 무료
        We investigated pollination and foraging activities of honeybee (Apis mellifera L.) and bumblebee (Bombus terrestris L.) during flowering season of the asian pear (Pyrus pyrifolia N.) under different weather conditions. There was no significant statistical difference about the pollination activities of two species. However, the pollination activities of bumblebee were more active than those of honeybee under low temperature and rainfall period. The activities of honeybee and bumblebee were more influenced by temperature than other factors (i.e. illumination and wind velocity). Honeybee was more sensitive to temperature and illumination than bumblebee. At low temperatures (<20℃) on cloudy days (<30,000 lux) with a certain wind velocity (>4.0 m/s), the pollination activity of the honeybee was lower twice than that of bumblebee.
        180.
        2016.10 구독 인증기관·개인회원 무료
        Cotton aphid, Aphis gossypii Gloever is one of the major pests on a wide range of economically important crops in the world. The sustained use of chemical insecticides to control the aphid has led to the emergence of resistant strains to numerous used insecticides. As an alternative strategy entomopathogenic fungi have been used as part of integrated pest management program to control aphid, especially insecticide-resistance population. In particular, Beauveria bassiana-based commercial bio-insecticide has been used to reduce the pest population under greenhouse conditions in various countries. In this study, we investigated the control efficacy of a prototype of commercial mycopesticide using an B. bassiana (wettable powder) against cotton aphid on potted cucumber plant in greenhouse conditions.