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        검색결과 784

        141.
        2018.10 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        This study investigates the effect of fatigue stress on the damping capacity in a damaged Fe-22Mn-12Cr-3Ni-2Si- 4Co damping alloy under fatigue stress. α’ and ε-martensite forms by fatigue stress in the damaged Fe-22Mn-12Cr-3Ni-2Si- 4Co damping alloy under fatigue stress. The α’ and ε-martensite forms with the specific direction and surface relief, or they cross each other. With an increasing fatigue stress, the volume fraction of α’-martensite and ε-martensite increases. With an increasing fatigue stress, the damping capacity increases with an increase in the volume fraction of ε-martensite. The increase in the damping capacity in the damaged Fe-22Mn-12Cr-3Ni-2Si-4Co alloy under fatigue stress strongly affects the increase of ε-martensite formed by fatigue stress, but the damping capacity of the damaged Fe-22Mn-12Cr-3Ni-2Si-4Co damping alloy under fatigue stress is strongly controlled by a large amount of α’-martensite.
        4,000원
        142.
        2018.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        막 결합형 축전식 탈염공정에서 이온교환막의 이온교환용량이 염 제거 효율에 미치는 영향을 알아보기 위해 poly(vinyl alcohol)(PVA) 수용성 고분자에 sulfosuccinic acid (SSA) 가교제를 첨가하고 poly(4-styrene sulfonic acid-co-maleic acid)(PSSA_MA)를 PVA 질량대비 10, 50, 90 wt%로 달리 첨가하여 제조하였다. PSSA_MA의 함량이 증가함에 따라 함수율과 이온교환용량이 증가하는 경향을 나타내었으며 막 결합형 축전식 탈염공정에서 염 제거 효율도 상승되었다. PSSA_MA 90 wt%, 100 mg/L NaCl의 공급액과 유속 15 mL/min에서 흡착 1.4 V/5분의 조건에서 가장 높은 65.5%의 염 제거 효율을 나타내었다.
        4,000원
        143.
        2018.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        최근 밭농업의 기계화와 생력화에 대한 연구와 개발이 활성화되고 있다. 그러나 밭농업의 기계화율은 비교적 낮을 뿐 아니라, 농작업이 단계별로 기계화되고 있기 때문에 밭농업의 생력화에 기여하지 못하고 있다. 따라서 본 연구의 목적은 밭농업을 생력화하기 위하여 구현한 일관작업 복합기의 포장능률 및 비용분석을 통하여 생력화율을 평가하는데 있다. 경운·정지, 두둑성형, 방제, 멀칭 및 파종·정식모듈을 포함하여 다섯 작업모듈을 일관화한 복합기의 이론작업시간은 0.56hr/10a으로 관행과 비교하여 67%의 생력화율을 보였다. 유효포장능률은 0.09ha/hr로서 관행에 비하여 2.95배 우수하였고 부담면적은 9.07ha로 평가되었다. 비용분석에서는 복합기의 초기구입비가 43% 절감되는 것으로 평가되었으며 시간당 비용과 단위면적당(10a) 비용은 관행에 비하여 각각 68% 및 58% 정도 절감되었다. 따라서 트랙터 복합작업기를 이용한 일관화된 밭작업은 관행에 비하여 생력화에 상당히 기여하는 것으로 평가된다.
        4,500원
        144.
        2018.10 구독 인증기관·개인회원 무료
        Orius minutus (L.) (Hemiptera: Anthocotidae) is a native predator of mites, thrips, and aphids whereas Orius laevigatus (Fieber) is a commercialized predator were assessed against O. metasequiae in laboratory and field. Adult females of both predator predated equally O. metasequiae adult after 3 hours of exposure in the laboratory on no choice assay. Orius minutus and O. laevigatus released with Portulaca oleracea plant in Metasequouia glyptostroboides tree reduced O. metasequiae population equally by 48.3% and 42.7% on first week after exposure. But O. laevigatus released without P. oleracea plant reduced 52.4% on the first week whereas O. minutus reduced only 6.2% of O. metasequiae population. We found only 3 O. minutus eggs on M. glyptostroboides leaves where 22 O. laevigatus eggs were found when treated without P. oleracea plant. Orius laevigatus laid 160.0 eggs on P. oleracea plant where as O. minutus laid only 25.7 eggs per plant. These result demonstrate that O. laevigatus can be applied for conservation biological control to suppress O. metasequiae population.
        145.
        2018.10 구독 인증기관·개인회원 무료
        소나무재선충병의 매개충인 북방수염하늘소의 체내 선충보유량에 따른 비행능력의 차이를 구명하기 위하여 춘천시 지내리의 잣나무림에서 어리소나무재선충(Bursaphelenchus mucronatus)에 감염이 확인된 북방수염하늘소 암·수 각 20마리를 채집, 실내사육 후 우화-섭식 1 주일이 지난 시점부터 1주 간격으로 Flight mill을 이용하여 비행실험을 진행하였다. 동시에 사육통 바닥에 여과지와 섭식한 잣나무 신초를 3~4일 마다 교체 후 Baermman funnel법으로 소나무 재선충을 분리하여 그 수를 조사, 비행능력과 선충보유량의 관계를 조사하였다. 그 결과 약 50,000마리 이상 선충을 체내에 보유시 비행능력이 급감하는 것을 확인 할 수 있었으나, 전체적으로 선충의 체내 보유량에 따른 비행능력의 차이는 상관관계가 없는 것으로 확인 되었다.
        146.
        2018.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This paper is to investigate the micro-behavior of the double-span beams with WUF-W seismic connection under combined axial tension and moment and to propose the rational rotational capacity of it for progressive collapse-resistant analysis and design addressing the stress and strain transfer mechanism. To this end, the behavior of the double-span beams under the column missing event is first investigated using the advanced nonlinear finite element analysis. The characteristics of fracture indices of double-span beams with WUF-W connection under combined axial tension and flexural moment are addressed and then proposed the rational rotational capacity as the basic datum for the progressive collapse-resistant design and analysis. The distribution of fracture indices related to stress and strain for the double-span beams is investigated based on a material and geometric nonlinear finite element analysis. Furthermore, the micro-behavior for earthquake and progressive collapse is explicitly different.
        4,000원
        147.
        2018.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        단면증대공법은 경제성과 시공상 보편적으로 사용되는 공법으로 우리나라의 철근콘크리트 기둥을 보강하기 위한 공법으로 널리 사용되어 왔다. 이와 관련하여 단면증대된 부재의 성능에 관한 실험적 또는 해석적 연구는 수행된 사례가 있으나, 휨성능과 단면증대 부분의 표면거칠기 범위의 상관관계에 대한 연구는 수행되지 않았다. 따라서, 본 연구에서는 단면증대된 보의 휨성능을 평가하기 위해 표면거칠기의 범위를 변수로 한 단면증대보의 휨실험을 수행하였다. 그 결과는 다음과 같다. (1) 시공에서 사용되는 방법에 따라 거칠기 처리가 된 표면의 거칠기 이력을 분석한 결과 인접 산과 골의 차이는 6mm를 초과하였다. (2) 거칠기 이력이 측정된 거리가 600mm를 초과하연, 거칠기 지표는 일관된 결과를 나타내었다. (3) 표면거칠기처리를 하지 않은 보의 휨성능과 비교할 때, 표면거칠기가 된 보의 휨강성은 25%증가하고, 항복강도는 9%, 최대강도는 6%증가하였다. (4) 모든 시험편은 표면거칠기 처리의 유무에 상관없이 단면해석결과 나타난 항복강도보다 높은 강도를 나타내었다.
        4,000원
        149.
        2018.07 구독 인증기관·개인회원 무료
        The restaurant industry is more engaged in innovation now. Many entrepreneurs realized that the restaurant sector faces major challenging market environments: changing needs of customers, high competition, low barriers to entry, high labor costs, and innovation technology. The market orientation drives business learning about customers. Engaged customers can assist firms to improve performance by getting involved with the firm’s product innovation. Innovation could help restaurants to improve the products and service quality, cut costs, increase sales and profits; it is the basic condition for the survival of restaurant entrepreneurs. However, studies about how the innovation affects restaurant performance were still limited to describe the overview of products innovation process (Ivkov et al., 2016). Resource-based theory takes the internal resources and capabilities of a firm as valuable sources of competitive advantage. How to combine internal resources and quickly respond to market needs to create performance of innovation entrepreneurship that still unclear and worth exploring in depth discussion. Based on the above, This study personal interview with twelve restaurant entrepreneur, government experts and scholars reveal how absorptive capacity could strengthen the link between positional advantage and innovation for entrepreneurship restaurants with the influence of customer engagement. The positional advantages can make enterprise differentiate with their competitors, that including entrepreneurial orientation, human capital and market orientation (Jogaratnam,2017). The experts believe that innovation entrepreneurs need to adopt an open mind, seek new opportunities in the catering market, acquire or develop new technologies and launching new products / services in the market, using high returns and high risk strategies in search of success in market. Training and educating team members are effective way to improve their innovation entrepreneurship.
        150.
        2018.07 구독 인증기관·개인회원 무료
        Prior research found a firm’s strategic orientation has a key impact on product innovativeness performance (Ozkaya et al., 2015). Both marketing orientation and learning orientation help firms to develop new product designs, generate innovative ideas, and achieve a better business performance (Narver & Stanley, 1990; Chuang, Morgan & Robson, 2015; Calantone et al, 2002). In line with prior studies, the purpose of this research is to investigate the mediating role of absorptive capacity (ACAP) (Cohen & Levinthal, 1990) on the effect of a firm’s strategic orientation (i.e., marketing orientation and learning orientation) on product innovativeness. We further investigated how environmental uncertainty moderates the effects of market orientation and learning orientation on product innovativeness. Survey method is adopted to collect data from Chinese manufacturer SMEs in the IT industry. 318 questionnaires were collected and analysed. CFA result shows that all constructs meet minimum requirements for reliability and discriminant validity test. Structural Equation Model (SEM) test reveals that both learning orientation and competitor orientation have significant impacts on product innovativeness, and ACAP plays partial meditation roles to effects from learning orientation to product innovativeness, and competitor orientation to product innovativeness. Customer orientation does not show a direct effect on product innovativeness, but is fully mediated by ACAP. We further tested whether the model is moderated by environmental uncertainty (EU) and result shows that EU only moderates the impact from learning orientation to product innovativeness. By developing a model of strategic orientation– absorptive capacity- product innovativeness, we contribute to the extant literature in strategic marketing.
        151.
        2018.07 구독 인증기관·개인회원 무료
        In tourism industry, tourists at the post-fordist era have overlooked tangible aspects of consumption by focusing on tourists’ experience and satisfaction. Recently, many scholars have employed the marketing concepts to investigate tourists’ need, want, and demand, especially, value co-creation. However, there is a little interest to focus on value co-creation in tourism industry, in spite of the fact that tourists in the digital age have decided to travel by intangible aspect of consumption – emotional and experience. Additionally, we also employ the concept of psychological carrying capacity to understand how tourist value relates to psychological carrying capacity. A total of 380 completed questionnaires are collected and the data were analyzed using Pearson’s correlation analysis. The correlations between tourist value and psychological carrying capacity were examined in order to understand the relationship of tourist value toward environmental concern in the settings of island area. The results show that there is the direct relationship between tourist value, perceived crowding, interactions between tourists, perceived physical environment, overall satisfaction, and returning intention.
        152.
        2018.06 구독 인증기관 무료, 개인회원 유료
        Recently, Oil spill incidents from maritime activities and port operation have been causing the serious ocean environment pollution, these problems are said to be the negative effects on the natural environment, social economy, marine species, and human health. Due to the high costs of treating oil spills and oil slick in comparison with a low-income country like Vietnam, many incidents related to the oil spill and oil slick have not been thoroughly processed. Cellulose components from Vietnamese agricultural residues used to produce the absorbent materials are one of the most urgent issues and this is the research object of this work. In this study, two types of structural lengths of cellulose added into PU matrix foam are used to measure how much crude oil, fuel oil, diesel oil and kerosene can be absorbed. The absorbent materials are designed after adding cellulose with 5%, 15%, 25% of mass, respectively. The achieved results show that the oil absorption capacity of PU-cellulose implemented 5% cellulose with 500μm of cellulose structure length and 25% cellulose with 3000μm of cellulose structure length are highest for crude oil. These study results from this work provide a reasonable price for the protection of the marine environment in the strategies of recovery and treatment of oil spill and oil slick on the seawater surface.
        4,000원
        153.
        2018.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        깨다시 꽃게(Ovalipes punctatus)는 갑각류로서 우리나라에서 잡히는 매끈 꽃겟속, 주름 꽃 겟속, 톱날 꽃겟속, 민 꽃겟속, 두갈래 민꽃겟속 들 중에 하나이다. 대부분의 꽃게는 가공되지 않은 상태로 찜 또는 찜육 등 반 가공 형태로 산업화 되었지만 최근에 게로부터 생리활성을 나타내는 펩타이드를 생산하는 연구가 발표되고 있다. 본 연구는 항산화 기능성을 나타내는 펩타이드를 선별하고 생산 최저공정 확립에 연구를 수행 하였다. 사용된 효소 alcalase, bromelain, flavourzyme, neutrase, papain, protamex들 중에서 bromelain으로 생산된 꽃게육 단백질 가수분해물이 가장 높은 활성을 보여 주었다. 꽃게육 단백질의 bromelain 가수분해물의 펩타이드들의 분자량 분포는 500-3,200 Da로서 7 종류의 이상의 펩타이드들로 구성되었다. 가수분해물의 구성아미노산 분포는 항산화 기능성에 관련된 소수성 아미노산은 전체 42.54%를 차지하였다. 가수분해물의 최적 생산 수율 조건을 확립하기 위하여 공정 조건, 효소 반응 온도 40-60℃, pH 6-8, 효소의 농도 1–3%(w/v)로 표면반응 분석법을 수행한 결과 효소 반응온도 55℃, 반응 pH 6.5, 효소의 양은 3%(w/v)에서 결정되었다. 최적 조건에서 단백질 가수분해도는 최대 71.60%에 도달하였다.
        4,200원
        154.
        2018.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The push-out tests have been conducted on the specimens which consist of the steel beam with U-shape section and the cap-type shear connectors with constant intervals. Existing equations for the evaluation of shear connector strength have been investigated on the basis of test results. The reinforcing bars for longitudinal reinforcement and the penetrative bars for transverse reinforcement didn’t have much effect on the shear capacity of the cap-type shear connector. The larger the width of cap-type shear connector was profiled, the greater the shear strength turned. The shear capacities of cap-type shear connectors with constant intervals were evaluated on the basis of push-out test results, and those were possible to be determined with proper safety margin using the Eurocode 4. The slip capacity of cap-type shear connector was shown to exceed the limit value of 6mm for sufficiently ductile behavior.
        4,000원
        158.
        2018.05 구독 인증기관·개인회원 무료
        Subsurface cavities in the asphalt pavement which can cause road depression and cave-in accidents influence on the safety of pedestrians and vehicle drivers in the urban area. The existence of subsurface cavity can increase the tensile strain at the bottom of asphalt layer which is an indicator of fatigue cracking potential, and leads to the weakening of the pavement structural capacity. In this study, the finite element (FE) analysis was conducted to examine the relationship between the critical pavement responses and influencing factors, such as cavity depth and size, asphalt layer thickness, and asphalt concrete modulus. The surface deflections and tensile strains calculated from the ABAQUS FE program were compared to those from ILLIPAVE. It is found from this comparison that there are a good relationship between two analysis results. A three dimensional finite element model which is essential to simulate the hexahedral cavity were used to generate the synthetic database of critical pavement responses. To validate the developed model, the deflection data obtained from field Falling Weight Deflectometer (FWD) testing in four different locations were compared to FE deflections. It is found that the center deflections obtained from the FWD testing and FE analysis are similar to each other with an error values of 2.7, 4.4, 5.5, and 11.9 % respectively. The FE model developed in this study seems to be acceptable in simulating actual field cavity condition. On the basis of the data in the database, various analyses were conducted to estimate the effect of influencing factors on the critical pavement responses. It was found that the tensile strain at the bottom of asphalt layer is affected by all the factors but the most affected by the cavity depth and asphalt concrete modulus. Further studies are recommended to properly account for the effect of cavity’s geometry to pavement response.
        159.
        2018.05 구독 인증기관·개인회원 무료
        본 연구에서는 막 결합형 축전식 탈염공정의 단수를 10단 형태의 모듈로 설계하여 처리용량을 증대하고자 하였다. MCDI에 사용된 이온교환고분자로는 아민기가 함유된 폴리설폰(APSf)과 술폰기가 함유된 폴리이서이서케톤(SPEEK)을 합성하여 캐스팅법으로 탄소전극에 제조하였다. 공정변수는 흡착전압 및 시간, 탈착전압 및 시간, 공급액의 유속과 농도 등을 달리하여 염 제거효율을 측정하였다. 대표적으로 Nacl 100 mg/L, 유속 100 mL/min, 흡착조건 1.2 V/3 min, 탈착조건 -0.5 V/5 min에서 98.3%의 염 제거효율을 보였다.
        160.
        2018.04 구독 인증기관·개인회원 무료
        In this paper, four point bending tests were carried out to analyse flexural strengthening effect by CFRP (Carbon Fiber Reinforced Polymer) layers for I shape PFRP (Pultruded Fiber Reinforced polymer) flexural member retrofitted with CFRP sheet. Comparing load-displacement relation and sectional stress distribution, the flexural strengthening effect by the number of CFRP layers was founded.