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        검색결과 14

        1.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        OWEC(Overtopping Wave Energy Converter)는 월파된 파도를 이용한 파력발전시스템이라한다. OWEC의 성능 및 안전성은 파고, 주기 등 파도의 특성에 의해 영향을 받는다. 따라서 해역 특성에 따른 OWEC의 최적 형상과 구조안전성에 관한 연구가 필요하다. 본 연구 에서는 울릉읍 연안 해양 환경 데이터를 이용하였으며, SPH(Smoothed Particle Hydrodynamics) 입자법 해석을 통해 기존 케이슨 하부 구조에 변화를 준 모델 4개를 비교하여 월파 효율을 분석하였다. 그 결과, 하부 구조의 변경 및 경량화가 가능함을 확인하였다. 최적화 해석을 통 해 설계 하중에 내하력을 가지는 하부 구조인 새로운 트러스형 구조를 제안하였다. 이후 부재 직경 및 두께를 설계변수로 하는 사례 연구 를 통해 허용응력조건 하에서 구조 안전성의 확보를 확인하였다. 주기적인 파랑 하중을 받기 때문에 제안하는 구조의 고유 진동수와 해 당 해역의 파주기를 비교하였으며, 1년 재현 주기의 파랑을 하중으로 한 조화응답해석을 수행하였다. 제안하는 하부 구조는 동일 가진력 에서 기존 설계 대비 응답의 크기가 감소하였으며, 기존 대비 32% 이상의 중량 절감을 수행하였다.
        4,000원
        2.
        2022.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study aimed to examine the cause and consequence of emotional labor strategies based on the emotional labor framework. To investigate the boundary condition of the current research model, the study proposed that job autonomy would moderate the effects of emotional labor on employees' well-being. To achieve the purpose of the study, it was first tested whether neuroticism and extroversion of employees predicted the focal outcomes (i.e., burnout and work engagement) via distinct emotional labor strategies. Second, the moderation effects of job autonomy were tested for each emotional labor strategy in predicting the focal outcomes. Third, the conditional indirect effects of job autonomy on the mediation process were examined. The results revealed that surface acting partially mediated the relationship between neuroticism and burnout, whereas deep acting fully mediated the relationship between extraversion and work engagement. Regarding the moderating effects of job autonomy, it significantly moderated the relationship between surface acting and burnout and between deep acting and work engagement. In addition, from the moderated mediation effects, the conditional indirect effects of job autonomy were significant. Finally, theoretical and practical implications are discussed and limitations and future research directions were suggested.
        5,200원
        3.
        2022.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        월파된 파도를 이용한 파력발전시스템을 월파수류형 파력발전기 OWEC(Overtopping Wave Energy Converter)라고 한다. OWEC의 성능은 발전 시스템은 특성상 파도의 파고와 주기의 영향을 받는다. 파도는 해양에 따라 파고, 주기, 파도 방향 등의 특성이 다르고 이러 한 파도의 다양한 특성 때문에 OWEC는 안정적인 전력을 생산하기 어렵다. 따라서 각 바다의 특성에 따른 OWEC의 적절한 형상에 관한 연구가 필요하다. 본 연구에서는 SPH(Smoothed Particle Hydrodynamics) 입자법을 사용하여 OWEC의 램프 설계가 hydraulic efficiency에 미치 는 영향을 확인했다. 총 10개의 모델을 설계하였으며, 선택된 매개변수에 따라 램프의 설계 파라미터를 선택하고 사면의 형상을 변경하여 시뮬레이션을 수행하였다. 해석 결과로부터 구한 유량을 기초로 hydraulic efficiency를 산출하였다. 계산된 hydraulic efficiency를 바탕으로 각 변수가 사면의 형상에 따른 월파 성능에 미치는 영향을 확인하였다. 본 연구에서는 특정 해역에 따른 OWEC 램프의 적절한 형상에 대한 방향을 제시하였다.
        4,000원
        4.
        2016.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구에서는 LNG-FPSO 선박에 탑재되어 있는 장비들의 운영효율을 최대화하기 위한 상태기반유지보수(CBM) 활동을 지원하는 보전시스템을 개발하였다. 개발된 보전시스템에서는 상태기반유지보수를 수행할 주요 장비들을 식별하여 이를 PWBS(Product Work Breakdown Structure)로 정의하였고 식별된 장비들로부터 실시간 수집되는 센서데이터를 이용하여 장비들의 고장분석과 최적 유지보수 방안을 결정하기 위한 경제성평가 등을 수행하며, 이들을 수행하기 위해 필요한 입출력 데이터를 저장, 관리하는 고장사례 및 유지보수데이터베이스를 구축하였다. 개발시스템의 성능검증을 현재 개발 중인 LNG-FPSO 선박의 Inlet 시스템의 Compressor와 화물창의 Pump Tower 등과 같은 주요 장비들을 대상으로 실시하였고 이를 바탕으로 상태기반유지보수의 가능성을 확인하였다.
        4,000원
        7.
        2016.03 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        To achieve the fabrication of high-quality Ag-coated Cu particles through a wet chemical process, we reported herein pretreatment conditions using an ammonium-based mixed solvent for the removal of a Cu2O layer on Cu particles that were oxidized in air for 1 hr at 200 oC or for 3 days at room temperature. Furthermore, we discussed the results of post-Ag plating with respect to removal level of the oxide layer. X-ray diffraction results revealed that the removal rate of the oxide layer is directly proportional to the concentration of the pretreatment solvent. With the results of Auger electron spectroscopy using oxidized Cu plates, the concentrations required to completely remove 50-nm-thick and 2-nm-thick oxides within 5 min were determined to be X2.5 and X0.13. However, the optimal concentrations in an actual Ag plating process using Cu powder increased to X0.4 and X0.5, respectively, because the oxidation in powder may be accelerated and the complete removal of oxide should be tuned to the thickest oxide layer among all the particles. Back-scattered electron images showed the formation of pure fine Ag particles instead of a uniform and smooth Ag coating in the Ag plating performed after incomplete removal of the oxide layer, indicating that the remaining oxide layer obstructs heterogeneous nucleation and plating by reduced Ag atoms.
        4,000원
        8.
        2013.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        이 연구는 자돈의 분변에서 분리된 Enterococcus faecim 193이 생산한 박테리오신을 부분정제하고 그 특성을 파악하여 천연 식품보존제 또는 첨가제로서의 이용가능성을 알아보고자 실시되었다. Enterococcus faecium 193의 배양시간에 따른 항균활성을 측정한 결과 항균활성은 3시간째부터 나타나기 시작하여 12시간째에 1280 AU/ml로 최대 활성을 나타내었다. Enterocin 193은 단백질 분해효소(trypsin, pepsin, 및 proteinase K)의 처리에 의해 항균활성이 소실되었으나 넓은 범위의 pH (1-11)와 열처리(121℃, 15분)에 비교적 안정하였다. 또한 50% 농도의 acetone, acetonitrile, chloroform 및 ethanol 등 유기용매에 안정하였으나, 50% methanol을 처리할 경우 항균활성이 50% 감소하였다. 이 박테리오신은 황산암모늄 침전, 소수성 크로마토그래피와 젤 여과 크로마토그래피에 의해 정제되었고 specific activity는 14.8배 증가하였다. SDS-PAGE에 의해 측정한 이 단백질의 분자량은 약 5 kDa이었다.
        4,000원
        9.
        2012.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Sulgidduk is a kind of basic steamed rice cake in Korea. Multifunctional portable grinder was used for making sulgidduk and investigated the characteristic changes of rice powder for deciding the proper particle size of rice powder. Operation times for grinding the water absorbed swelled rice were 10, 20, 30 and 40 seconds. Moisture contents of rice powder and sulgidduk showed an increasing tendency with an increase of operation times for grinding. Springiness showed significant differences according to the operation times. Cohesiveness was decreased severely after 40 seconds grinding. Chewiness showed high after 20 seconds grinding in all groups; however, decreased after 40 seconds grinding and showed similar chewiness of the control group. Fracturability also showed severe increased tendency after 20 seconds grinding and decreased after 30 seconds grinding. Strength and hardness showed significant differences; they were increased until 30 seconds and severely decreased after 40 seconds grinding. L values showed significant differences in all the groups (p≤0.05). The a and b values did not show any differences in all groups. Overall sensory evaluations, such as colors, flavors and texture, were increased with operation times for grinding and showed significant differences among the groups (p<0.05). As a result of this study, 40 seconds grinding times were the best condition for making sulgidduk, using by multifunctional grinder.
        4,000원
        12.
        2017.06 KCI 등재 서비스 종료(열람 제한)
        Barbaloin is a major component of Aloe vera, which has been used for a laxative. Also, barbaloin is C-glucoside of aloe emodin anthrone which is founded in Aloe vera. Barbaloin has varieties of pharmacological activity such as inhibitory effects on inflammation, histamine release, cancer and microbial infection. But the effect of barbaloin on lipopolysaccharide (LPS)-stimulated macrophages has not been understood. In this study, we evaluated the effects of barbaloin against LPS-stimulated production of nitric oxide (NO), inflammatory cytokines and MAPKs activation in macrophage. We treated barbaloin (0.1 , 1 , 10 , 100 μM) in LPS-stimulated mice peritoneal macrophage. Our results showed that barbaloin significantly inhibited production of NO and cytokines of tumor necrosis factor (TNF)-α, interleukin (IL)-6, interleukin (IL)-1β in LPS-stimulated peritoneal macrophage. Moreover, barbaloin inhibited the phosphorylation of ERK and JNK in a dose dependent manner. These results indicated that barbaloin could be useful for inflammatory diseases.
        13.
        2012.07 서비스 종료(열람 제한)
        Scientific studies have shown that essential fatty acidintake can have a dramatic impact on human health. Soybean [Glycine max(L.) Merr.] oil from current commercial cultivars typically containsaround 8%linolenic acid (18:3) known as omega-3 fatty acid. Omega-3 fatty acid plays an important role to prevent cardiovascular disease and cancer. Relatively high 18:3 content in seed oil is a trait of the wild soybean (Glycine soja Sieb. and Zucc.) ancestor of modern soybean cultivars. Wild soybean is native to Korean peninsula and recently thousands of wild soybeans collected by soybean researchers in Korea. The objective of this study were to determine the linolenic acid content for wild soybean collection and to determine the stability of linolenic acid content derived from wild soybean over environments. Fatty acid profile for 1,806 wild soybean accessions collected from South Korea was determined by GC. The range of linolenic acid was 7.3 to 23.7% with an average 15.6%. We developed a recombinant inbred population from a cross PI483463 (wild soybean with 15% 18:3) and Hutcheson (cultivar with 8% 18:3). Three RILs, RIL156, RIL159 and RIL166, with high linolenic acid content (over 14%), parents and Williams 82 as checks were grown in nine environments over 2008-2011. Results showed that the content of linolenic acid for the PI483463, Hutcheson, and Williams 82 ranged from 14.8 to 17.1, 8.5 to 9.7, and 6.9 to 8.4 % and averaged 15.4, 9.2 and 8.0%, respectively. However selected RILs 156, 159, and 166 ranged from 10.7 to 15.7, 14 to 15.8, and 14.8 to 15.8, and averaged 13.9, 14.9, and 15.2, respectively. Among the tested accessions, RIL166 was the most stable with the lowest range and CV, and had a relatively lower stability coefficient value than other genotypes. Genes related to high linolenic acid from wild soybean may be useful in developing higher linolenic acid soybean genotypes and would broaden the use of soybean in food applications to improve human nutrition and health.
        14.
        2011.09 KCI 등재 서비스 종료(열람 제한)
        It is important to understand the trajectory of structure in launching process because of the short time of launching process may result in unexpected accidents or damage to structures. The high risk of structural failure is not avoidable without the fully comprehension of changing forces in launching procedure. The commercial software can evaluate the motion of launching event in calm water condition but there is the limitation of research application because of the programmed commercial software. The launching process of the spar hull is suggested with stage concept that is divided into 10 stages in time domain. A force equilibrium diagram is derived for each stage where the changes of force vector and motion characteristics take place. In particular, the effects of changes in buoyancy and drag force due to the progressive submergence of the spar hull are taken into account by means of a touch length concept. The results contained in this paper provide the valuable information of the trajectory motion evaluation with suggested methods in spar launching process with sliding barge. Furthermore, the presented stage concept and touch length concept will provide basic knowledge for understanding launching process and help to develop further research area for launching analysis.