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        검색결과 15

        1.
        2023.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this paper, the key assembly of the recently developed light machine gun-Ⅱ sighting device was identified as prone to experiencing horizontal noise caused by unstable voltage fluctuations under high-temperature conditions during the defense environmental stress screening test. The primary objective ot this study is to address the issue of horizontal noise through circuit analysis and device parameter tuning, aiming to eliminate its presence.
        4,000원
        2.
        2022.10 구독 인증기관·개인회원 무료
        Currently, Hanul NPP packages glass fiber classified as particulate waste in plastic packaging bags and stores them in 200 L drums. KORAD’s Waste Acceptance Criteria (WAC) presents that very low-level soil can be immobilized by loading it in a soft bag and then packaging it in a 200 L or 320 L steel drum. As currently accepted method of packaging with soft bag applies to only very low-level soils among the wastes with a risk of dispersion, it is necessary to develop a non-dispersible treatment suitable for the characteristics of other particulate waste in the future. Therefore, in order for Hanul packaging pack to be approved as an alternative method for immobilization of dispersible substances, it is necessary to verify the suitability of the packaging bag. In this paper, whether the glass fiber packaging bag used in Hanul NPP satisfies the characteristic of the soft bag presented in the WAC and the possibility of being considered as a non-dispersible measure for particulate are examined. The soft bag must meet the following requirements: material and structure, shape, drop test, and immersion test. The results of the review are as follows. First, since the glass fiber is already packaged in the drum, only the role of the inner layer, made of polyethylene, having a watertight function may be required. Second, when packaging a drum, the packaging bag is compressed into a shaped frame having an inner size of a 200 L drum, so it is packaged with little empty space in the drum. Third, as a result of a drop test of a packaging pack containing 20 kg of contents from a height of 1.2 m, it was confirmed that there was no leakage of contents. Fourth, the packaging bag was immersed in a 1-m depth water tank for 30-minutes, and the performance corresponding to the IPX7 was satisfied. As a result of reviewing the soft bag characteristic of Hanul glass fiber packaging bag, it is considered that the bag can be used as one of the non-dispersible measures because it meets almost the characteristics required by the WAC. In addition, the acceptance criteria of overseas disposal sites present various secure packaging methods in place of immobilization as a non-dispersible measure for waste containing particulate matter. It is necessary to reflect these overseas cases in the establishment of non-dispersible measures for domestic waste acceptance in the future.
        6.
        2020.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 논문에서는 해양플랜트에 주로 사용되는 알루미늄 사다리의 독자 모델을 개발하기 위하여, 개량형 알루미늄 합금(6082-T6) 을 적용하고 국제 기준에 부합한 구조강도 설계를 하였다. 국제기준은 ISO, NORSOK, Austria Standard를 참고하였으며, 모든 조건이 만족할 수 있도록 하중 조합을 하였다. 설계된 모델은 유한요소법 [Finite elements method]을 근간으로 하는 해양플랜트 전용 해석프로그램인 SACS를 사용하여 구조 안전성을 검증하여 응력 및 처짐이 모두 허용기준 이내에 만족함을 확인하였다. 개발모델은 모든 허용기준을 만족하면서도 가볍고, 생산성이 향상되어 향후 많은 분야에서 사용이 될 것으로 기대해본다.
        4,000원
        7.
        2020.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        선박 및 해양구조물에서 사용하고 있는 고강도 알루미늄 합금들은 스틸과 비교해서 많은 이점을 가지고 있다. 최근 고강도 알루미늄 합금들은 육상 및 해양에 폭넓게 사용되고 있으며, 특히, 특수목적 선박의 선체 외판구조에 많이 이용되고 있고, 교량 구조물에 사용되는 상자 구조물, 그리고 고정식 해양플랫폼의 상부구조에서 소비율이 증가하고 있다. 알루미늄 재료는 스틸보다 1/3의 중량 구성비를 통하여, 구성 중량을 줄이게 하여 연비 절감을 가능하게 한다. 일반적인 강구조물의 응력-변형률 관계와 비교하면, 용접가공에 따라 발생하는 열영향부의 존재로 인하여 상당히 다르게 나타난다. 왜냐하면, 강구조물과 비교하면 열전도율이 높아서, 열영향부(heat affected zone, HAZ)가 남아 있어 구조 강도 저하를 가져온다. 본 논문에서는 MIG(Metal inert gas) 용접 때문에 발생하는 열영향부를 고려하고, 종방향 압축 하중에 대한 알루미늄 보강판의 좌굴 및 최종강도 특성을 분석하였다. MIG 용접에 따른 열영향부를 고려한 경우, 좌굴 및 최종강도 모두 감소하며, 열영향부의 범위가 15 mm부터 항복 이후 에너지 소실률이 크게 나타나며, 25 mm 이상부터는 그 차이가 크지 않다. 따라서, 알루미늄 합금재료를 적용한 보강판의 구조 거동을 파악하기 위해서는 열영향부 영향에 대한 검토 및 분석이 중요하다.
        4,000원
        8.
        2019.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Nb-Si-B alloys with Nb-rich compositions are fabricated by spark plasma sintering for high-temperature structural applications. Three compositions are selected: 75 at% Nb (Nb0.7), 82 at% Nb (Nb1.5), and 88 at% Nb (Nb3), the atomic ratio of Si to B being 2. The microstructures of the prepared alloys are composed of Nb and T2 phases. The T2 phase is an intermetallic compound with a stoichiometry of Nb5Si3-xBx (0 ≤ x ≤ 2). In some previous studies, Nb-Si- B alloys have been prepared by spark plasma sintering (SPS) using Nb and T2 powders (SPS 1). In the present work, the same alloys are prepared by the SPS process (SPS 2) using Nb powders and hypereutectic alloy powders with composition 67at%Nb-22at%Si-11at%B (Nb67). The Nb67 alloy powders comprise T2 and eutectic (T2 + Nb) phases. The microstructures and hardness of the samples prepared in the present work have been compared with those previously reported; the samples prepared in this study exhibit finer and more uniform microstructures and higher hardness.
        4,000원
        9.
        2018.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study investigated the characteristics of obesity induced by a high-fat diet (HD) over 13 weeks in Rhbdf2 gene knockout (KO) mice. Forty 7-week-old Rhbdf2 wild and KO mice were used and the mice were divided into 4 groups: Wild-ND (n=10, Rhbdf2 wild mice, normal diet (ND)), Wild-HD (n=10, Rhbdf2 wild mice, HD), KO-ND (n=10, Rhbdf2 KO mice, ND) and KO-HD (n=10, Rhbdf2 KO mice, HD). The relative epididymal fat weight in KO-HD was significantly increased compared with that in KO-ND (P<0.01). The relative liver and spleen weights in KO-HD were decreased compared with those in Wild-HD (p < 0.05) and KO-ND (p < 0.01). The mRNA expression of SOD1 in KO-ND was significantly reduced compared with that in Wild-ND (p < 0.05). In Wild-ND and HD, the mRNA expressions of TNF-α and IL-6 in epididymal fat were significantly increased compared with those in KO-ND and HD (p < 0.01). A significant increase of TNF- α and IL-6 mRNA expression was observed in KO-HD compared with KO-ND (p < 0.01). These results indicated that Rhbdf2 genes may regulate high fat diet-induced obesity damage by anti-inflammatory and anti-oxidative roles in fat tissue of mice.
        4,000원
        10.
        2018.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Red meats are important animal foods because of their nutritional aspects, but the over-consumption of red meat produces reactive oxygen species (ROS) caused by heme iron and induces colorectal cancer. The effect of orally administered hemin and calcium provided in drinking water for 6 weeks on colon carcinogenesis was observed in male ICR mice. After the mice were acclimated for 1 week, they received three subcutaneous azoxymethane (AOM, 10 mg/kg b.w.) injections weekly and were provided with 2% dextran sodium sulfate (DSS) via drinking water for the next week. The mice were divided into three groups: the control, hemin, and hemin + calcium groups. The orally administered daily dose of hemin was 2 g/kg b.w., and 0.05% calcium was provided daily via drinking water. Colonic mucosa samples were stained with methylene blue, and then, the numbers of aberrant crypt (AC) and aberrant crypt foci (ACF) were counted. Lipid peroxidation in feces was estimated by thiobarbituric acid-reactive substances (TBARS) assay. The total numbers of AC and ACF per colon in the hemin group were significantly higher than those in the control group. Calcium treatment significantly decreased the numbers of ACF and AC in the colon of mice. The TBARS value in the feces of the hemin + calcium group was significantly lower than that in the feces of the hemin group. These results showed that hemin enhances the formation of pre-neoplastic lesions in the colon of mice and that calcium decreases the risk of colon carcinogenesis.
        4,000원
        11.
        2011.11 구독 인증기관 무료, 개인회원 유료
        국민 소득수준 향상과 주 5일제 정착 및 해양으로 접근성 개선 등으로 해양에 관한 국민 관심이 지 속적으로 고조되고 있는 추세이며, 특히 최근 우리나라 주요 해안의 경우 레저와 여가를 위한 친수와 휴식공간으 로 지속적으로 개발함에 따라 이를 이용하려는 이용객이 점차적으로 늘어나고 있다. 그러나 이러한 수변영역 에는 다양한 재해ㆍ재난사고 발생 가능성이 산재하고 있음에도 불구하고 안전관리시스템의 부재로 안타까운 인명 및 재산피해가 끊이질 않고 발생하고 있다. 따라서, 본 연구에서는 해양활동 이용객 및 안전사고 위협 및 수 변영역 안전관리 실태 및 문제점 분석하고, 그에 따른 수변영역 안전관리시스템 설계 방안에 연구하고자 한다.
        4,000원
        12.
        2010.04 구독 인증기관 무료, 개인회원 유료
        2014년 해양경찰이 전담하게 될 해안경계 임무를 원활히 수행하기 위한 해안경계 위협요소 및 리스크를 분석하여 군사적ㆍ 비군사적 해안경계 위협의 특성을 도출하였다. 또한 우리나라의 해안경계 자원의 분석과 선진국의 해안경계시스템에 대한 비교를 통한 우리나라 해양안전ㆍ보안환경에 부합하는 미래 지향적 리스크 기반 해안경계시스템을 고찰하였다.
        4,000원
        13.
        2009.06 KCI 등재 구독 인증기관·개인회원 무료
        Human recombinant IL-32 induces the production of large amounts of several proinflammatory cytokines and chemokines, even in macrophage cell lines by activation of NF-κB and MAPK. The ability of IL-32 to potentiate inflammation is not the sole action of this cytokine. IL- 32 stimulates prostaglandin (PG)E2 in human PBMCs, which are pivotal in inflammation. The development of recombinant protein consisting of IL-32 is of great medical and industrial importance. Agrobacterium strains GV3101 harboring pCAMBIA1304 include IL- 32 vectors were used to infect the mushroom fruiting body pieces. For transformation experiments, fruiting body gill tissue pieces were vacuum infiltrated with the suspension of induced bacteria until the air had been completely purged. Mushroom mycelium appeared at the margins of the tissue pieces after 9 to 14 days on selection medium with hygromycin at 50㎍/㎖. Transformants PCR analyses confirmed that the IL-32 gene was into the genome of Pleurotus eryngii. The present results demonstrating the usefulness of the transgenic technique s in the genetic manipulation and improvement of mushroom.
        14.
        2009.06 KCI 등재 구독 인증기관·개인회원 무료
        Human GH (hGH) has been available over 40 years for the treatment of children with GH deficiency. Human growth hormone (hGH) is mainly produced in the somatotrophic cells of the pituitary in brain and is the product of the GH-N gene. Among the edible mushrooms, the king oyster mushroom (Pleurotus eryngii ) is one of the most popular mushrooms in Asia, Europe and North America. The increasing popularity of P. eryngii among consumers is due to its flavor, texture and shelf life. We report a modified Agrobacteriummediated method for the efficient transformation of hGH2 in Pleurotus eryngii . The binary vector pCAMBIA1304 was used for the initial transformation and detected by GUS and GFP. Infiltrated samples transformed with pCAMBIA1304 showed a wider GUS response than the co-cultivated in the 50㎍/㎖ hygromycin selection medium. This transformation technique offers new prospects for the production of useful protein in the genetically improved mushroom.