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        검색결과 51

        3.
        2022.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Recently, the necessity of designing and applying tool materials that perform machining of difficult-to-cut materials in a cryogenic treatment where demand is increasing. The objective of this study is to evaluate the performance of cryogenically treated WC-5 wt% NbC hard materials fabricated by a pulsed current activated sintering process. The densely consolidated specimens are cryogenically exposed to liquid nitrogen for 6, 12, and 24 h. All cryogenically treated samples exhibit compressive stress in the sintered body compared with the untreated sample. Furthermore, a change in the lattice constant leads to compressive stress in the specimens, which improves their mechanical performance. The cryogenically treated samples exhibit significant improvement in mechanical properties, with a 10.5 % increase in Vickers hardness and a 60 % decrease in the rupture strength compared with the untreated samples. However, deep cryogenic treatment of over 24 h deteriorates the mechanical properties indicating that excessive treatment causes tensile stress in the specimens. Therefore, the cryogenic treatment time should be controlled precisely to obtain mechanically enhanced hard materials.
        4,000원
        15.
        2020.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The present study investigated the intra-vitam larval migration of Anisakis pegreffii, which is naturally infected, from the intestine to the viscera and the musculature of live spotty-bellied greenling, Hexagrammos otakii, under the different seawater temperatures. The results showed that the increase in the ratio of larval migration from the intestine to the viscera correlated with the increase in the water temperature in the aquarium. The intra-vitam larval migration ratios from the intestine to the viscera were 60% (63/105) at 15°C, 1.64% (3/183) at 12°C, 1.16% (2/172) at 9°C and 1.42% (2/141) in the control group (7.5°C). The free larvae showed no, slight and strong movement at 9°C, 12°C and 15°C, respectively, in saline water, and the larvae were present in a coiled state at 9°C and 12°C. The results suggest that temperature plays an important role in the intra-vitam larval migration of A. pegreffii. In addition, the free larval behavior of A. pegreffii in vitro increased with increase in temperature. Therefore, to prevent human anisakiasis caused by the consumption of raw fish, it is important that the temperature of the aquarium must be maintained below 12°C, which is the critical temperature zone.
        4,000원
        17.
        2019.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        We studied the infection rate of and various metacercariocidal approaches to controlling Gymnophalloides seoi for prevention of human infection in cultured and natural oysters in Korea. The selected survey areas were Aphae-do (Shinan-gun, Jeollanam-do), which is an endemic area for G. seoi, and Tongyeong (Geonsangnam-do), which is the main production area of oysters in Korea. In the Tongyeong area, the metacercariae of G. seoi were not detected in cultured oysters (0/201) or wild oysters (0/134). Seventy-two G. seoi metacercariae were observed in 33 of 265 natural oysters collected from Aphae-do; however, metacercariae were not detected in the cultured oysters (0/1101) purchased from the Daejeon Fish Market. To investigate the viability of G. seoi metacercariae, various metacercariocidal treatments were used with 3.5% saline and oyster juice used as positive controls. The metacercariae survived for 75.4 h in 3.5% saline and 112.6 h in oyster juice. After the metacercariocidal treatment, G. seoi metacercariae were survived for 13.29 min in tap water, < 20 sec in 4.3% vinegar, no effect in a rinse of the whole oyster body in 70°C water for 1 sec, but 1 sec in a rinse of the whole oyster body in 90°C water for 1 sec. The greatest metacercariocidal effect on G. seoi was from rinsing oysters in 90°C water followed by those from treatment with 20% ethyl alcohol, 4.3% vinegar, and tap water. However, we suggest that the most actual prevention to G. seoi human infection is rinsing the oysters with tap water for at least 30 min.
        3,000원
        18.
        2018.11 구독 인증기관·개인회원 무료
        본 실험에서는 실제 원수와 모사 원수를 이용하여 유기막(PES, PVDF 및 PTFE)을 이용하여 재질에 따른 막오염 특성을 분석하고자 하였다. 먼저 원수를 운전압력 1kgf/cm2로 여과하였다. 재질별 소요된 여과 시간은 약 5분, 약 13분, 약 17분으로 각각 나타났다. 또한 모사 원수 실험을 진행하였고, 원수 실험과 동일한 결과를 나타냈다. Jucker 와 Clark(1994)에 따르면 소수성 재질의 막이 유기물 흡착에 의한 Flux 감소가 크다고 보고하였고, 본 실험에서도 소수성 재질의 막이 높은 Flux 감소율을 나타났다. 실험 결과를 통해 막 재질 특성이 조류 유입에 따른 Flux 감소율에 영향을 미치는 것을 확인하였다. 본 연구는 환경부의 “환경정책기반공공기술개발사업”으로 지원받은 과제입니다.
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