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        검색결과 29

        2.
        2022.10 구독 인증기관·개인회원 무료
        When decommissioning a nuclear power plant, the structure must be made to a disposable size. In general, the cutting process is essential when dismantling a nuclear power plant. Mainly, thermal cutting method is used to cutting metal structures. The aerosols generated during thermal cutting have a size distribution of less than 1 μm. The contaminated structures are able to generate radioactive aerosols in the decommissioning. Radioactive aerosols of 1 μm or less are deposited in the respiratory tract by workers’ breathing, causing the possibility of internal exposure. Therefore, workers must be protected from the risk of exposure to radioactive aerosols. Prior knowledge of aerosols generated during metal cutting is important to ensure worker safety. In this study, the physical and chemical properties of the aerosol were evaluated by measuring the number and mass concentrations of aerosols generated when cutting SUS304 and SA508 using the laser cutting method. High-resolution aerosol measuring equipment (HR-ELPI+, DEKATI) was used to measure the concentration of aerosols. The HR-ELPI+ is an impactor-type aerosol measuring equipment that measures the aerosol number concentration distribution in the aerodynamic diameter range of 6 nm to 10 um in real-time. And analyze the mass concentration of the aerosol according to the diameter range through the impactor. ICP-MS was used for elemental mass concentration analysis in the aerosol. Analytical elements were Fe, Cr, Ni and Mn. For the evaluation of physical and chemical properties, the MMAD of each element and CMAD were calculated in the aerosol distribution. Under the same cutting conditions, it was confirmed that the number concentration of aerosols generated from both materials had a uni-modal distribution with a peak around 0.1 um. CMAD was calculated to be 0.072 um for both SUS304 and SA508. The trend of the CMAD calculation results is the same even when the cutting conditions are changed. In the case of MMAD, it was confirmed that SUS304 had an MMAD of around 0.1 μm in size for only Fe, Cr and Mn. And SA508, Fe, Cr, Ni and Mn were all confirmed to have MMAD around 0.1 μm in size. The results of this study show that a lot of aerosols in the range of less than 1 μm, especially around 0.1 μm in size, are generated when metal is cut using laser cutting. Therefore, in order to protect the internal exposure of workers to laser metal cutting when decommissioning NPPs, it is necessary to protect from nano-sized aerosols beyond micron size.
        5.
        2020.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Behavioral response to a diel photoperiodicity (500 lx for 16 h, 5 lx for 4 h and < 0.5 lx for 4 h) and phototactic characteristics in dark conditions were examined with Siberian sturgeon Acipenser baerii (Chondrostei, Actinopterygii) prelarvae. Siberian sturgeon prelarvae represented both qualitative and quantitative changes in their behavioral patterns according to different light intensities in a diel photoperiodicity. Under daylight conditions (500 lx), prelarvae displayed saltatory changes of behavioral features with ages (Day 0-Day 9) in a general order of swimming-up/drifting, swimming in the upper water column, benthic swimming with rheotaxis, schooling and postschooling behavior. Compared to daylight conditions, prelarvae tended to show more benthic performances and quantitative reductions of schooling and postschooling behaviors under dimlight conditions (5 lx). Under dark conditions (< 0.5 lx), prelarvae exhibited a fairly uniform behavioral pattern characterized by the benthic swimming across the bottom of the tank. From phototaxis tests under dark conditions, navigational responses of prelarvae to a spotlight illumination were quantitatively changed as their ages increased. The phototactic responses reached the peak on Day 2, continued until Day 4, and then gradually decreased until Day 8. A partial recovery of positive phototaxis was observed on Day 9. Data from this study suggest that the diel light cycle as well as the light intensity of each interval in the cycle should be considered as important components of a practical guide for evaluating fitness and developmental states of artificially propagated Siberian sturgeon prelarvae.
        4,500원
        6.
        2020.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Karyotype analysis is a major work in the process of triploid abalone production for the purpose of productivity and quality improvement. However, the metaphase spreads for karyotype analysis have been prepared just from the larvae at trochophore stage, which has restricted the spectrum of sample correction inhibiting more efficient analysis. Here, we investigated the feasibility of preparing metaphase spreads from the larvae at veliger stage that is the next developmental stage of trochophore. For this, diploid and triploid larvae at trochophore and veliger stages from Pacific abalone (Haliotis discus hannai ) were subjected to metaphase spread preparation and its efficiencies were measured and compared each other. As the results, although the efficiencies of metaphase spread preparation were significantly lower in the larvae at veliger stage compared to the ones at trochophore stage regardless of ploidy status, we found that the preparation of metaphase spreads, which showed the clear chromosomal images containing the normal number of chromosomes, was possible from the veliger stage larvae. On the other hands, all larvae used in this study regardless of developmental stage and ploidy did not show colchicine sensitivity. Moreover, no significant difference was observed in cell cycle distribution of the cells comprising larvae between two developmental stages regardless of ploidy status. These suggested that the details of protocol to prepare metaphase spreads from abalone larvae should be optimized depending on its developmental stages. Taken together, we demonstrated the feasibility of preparing metaphase spreads from H. discus hannai veliger stage larvae for karyotype analysis.
        4,000원
        16.
        2015.10 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Bi0.5Na0.5TiO3 (BNT) based ceramics are considered potential lead-free alternatives for Pb(Zr,Ti)O3(PZT) based ceramics in various applications such as sensors, actuators and transducers. However, BNT-based ceramics have lower electromechanical performance as compared with PZT based ceramics. Therefore, in this work, lead-free bulk 0.99[(Bi0.5Na0.5)0.935Ba0.065](1-x)LaxTiO3-0.01SrZO3 (BNBTLax-SZ, with x = 0, 0.01, 0.02) ceramics were synthesized by a conventional solid state reaction The crystal structure, dielectric response, degree of diffuseness and electric-field-induced strain properties were investigated as a function of different La concentrations. All samples were crystallized into a single phase perovskite structure. The temperature dependent dielectric response of La-modified BNBT-SZ ceramics showed lower dielectric response and improved field-induced strain response. The field induced strain increased from 0.17% for pure BNBT-SZ to 0.38 % for 1 mol.% La-modified BNBT-SZ ceramics at an applied electric field of 6 kV/mm. These results show that Lamodified BNBT-SZ ceramic system is expected to be a new candidate material for lead-free electronic devices.
        4,000원
        17.
        2015.06 구독 인증기관 무료, 개인회원 유료
        Introduction 5 working days a week and wellness trends, that allows more consumers to actively enjoy outdoor activities, has led to a rapid growth in the outdoor clothing market. Buyers of outdoor clothing perceive them as causal and functional clothes that they can wear comfortably in daily life as well as for outdoor activities such as hiking and fishing (Park et al., 2002). There is an increased interest in outdoor activities by seniors who engage in various hobbies for health. Active seniors are energetic retirees who actively enjoy their retirement. They have emerged as a new consumer group in the inactive culture market (such as travel and the performing arts) due to their enjoyment of activities (such as language study, computer education, cosmetic/beauty treatments and sports) that is different from previous generations of older people (Korean Economic glossary, 2014). The most striking characteristic of active seniors is their generous investment in self-development based on secure assets and retirement income. Many studies have been done on senior citizens based on age that have examined body types (Ahn, 2003; Kim, 1995; Lee & Kim, 2007) and original clothing forms (Lee, 2003; Nam & Choi, 2002; Moon, 2008). However, these studies did not fully reflect the needs of active seniors interested in clothing. Additionally, most studies were conducted on female seniors with few studies on male seniors. It is necessary to accept and understand changes in the body types and physical functions of seniors body types and physical functions that accompany age and changing aesthetic sense with styles that are differentiated from existing elderly groups in regards to clothing for active seniors. A study on older men's body classification (Kim & Lee, 2003) indicated that the characteristics of older men's body types were not fully considered because a clothing sizing system was not separately established for older people. Most outdoor clothing companies produced patterns for a young generation. This study was conducted on the outdoor jacket wearing pattern of active male seniors. The results of this study can be used to design outdoor jackets that are produced at a reasonable price with a wearable function useful for outdoor activities and daily life.
        3,000원
        18.
        2015.06 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        New lead-free piezoelectric ceramics 0.96[{Bi0.5 (Na0.84 K0.16)0.5}1-xLax(Ti1-y Nby)O3]-0.04SrTiO3 (BNKT-ST-LN, where x = y = 0.00 ≤ (x = y) ≤ 0.015) were synthesized using the conventional solid-state reaction method. Their crystal structure, microstructure, and electrical properties were investigated as a function of the La and Nb (LN) content. The X-ray diffraction patterns revealed the formation of a single-phase perovskite structure for all the LN-modified BNKT-ST ceramics in this study. The temperature dependence of the dielectric curves showed that the maximum dielectric constant temperature (Tm) shifted towards lower temperatures and the curves became more diffuse with an increasing LN content. At the optimum composition (LN 0.005), a maximum value of remnant polarization (33 C/cm2) with a relatively low coercive field (22 kV/cm) and high piezoelectric constant (215 pC/N) was observed. These results indicate that the LN co-modified BNKT-ST ceramic system is a promising candidate for lead-free piezoelectric materials.
        4,000원
        19.
        2014.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Multiple starters consisting of two Bacillus amyloliquefaciens strains (MJ1-4 and EMD17), Pichiafarinosa SY80, and Rhizopus oryzae were used for Doenjang making. Bacillus strains were selected based on their abilities to inhibit toxinogenic fungi and Bacillus cereus, fibrinolytic activity, and their ability to confer good flavor to Cheonggukjang. P. farinosa SY80 and R. oryzae, previously isolated from soy sauce, were selected because they were not inhibited by two bacilli. Doenjang was prepared by inoculation of multiple starters (A1 Doenjang). Control Doenjang was prepared by inoculation of B. subtilis KACC 16750 (Natto strain) and Aspergillus oryzae KCCM 60166 (A2 Doenjang). Another control (A3 Doenjang) was prepared by inoculation of microorganisms present in rice straw. Doenjang samples were fermented for 70 days at 20℃. pH of 3 samples decreased from the initial value of 6.4 to 5.8~6.0 and titratable acidity (TA) increased from 0.6 to 1.1~1.3. The amount of amino-type nitrogen increased during fermentation. There were slight differences in moisture, crude-protein, and crude-fat contents after 70 days. Contamination of fungi was observed only in A3 Doenjang and B. cereus was not detected from all 3 samples. A1 Doenjang showed the highest fibrinolytic activity and A2 Doenjang the second. These results indicate that Doenjang made with carefully selected starters was functionally improved and microbially more safe.
        4,000원
        20.
        2005.12 구독 인증기관 무료, 개인회원 유료
        Resveratrol (3,4',5-trihydroxy-trans-stilbene), a naturally occuring polyphenol compound which present in the skin of grapes and red wine has been considered to posses chemopreventive and antioxidant properties. However, little is known about the cellular actions by which resveratrol mediates its therapeutic effects. In this study, the effect of resveratrol on cell proliferation and induction of apoptosis in human osteogenic sarcoma (HOS) cells was investigated. IC50 value was determined to be approximately 60μg/mℓ. Chromosomal DNA framgmentation analysis showed the appearance degraded DNA in time-and dose-dependent manner upon treatment of resveratrol. In order to observe the molecular mechanism involved in resveratrol-induced apoptosis, Western blot analysis was performed. We observed the decrease in the level of procaspase-3, the zymogen form of active caspase-3 in resveratrol-treated cells. This result implies that caspase-3 is activated upon treatment of resveratrol. The activation of caspase-3 was confirmed by the cleavage of poly(ADP-ribose) polymerase. Taken together, our data demonstrate that resveratrol has anti-proliferative effect on HOS cells and induced apoptosis through activation of caspase-3 and PARP cleavage.
        4,000원
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