검색결과

검색조건
좁혀보기
검색필터
결과 내 재검색

간행물

    분야

      발행연도

      -

        검색결과 86

        1.
        2023.11 구독 인증기관·개인회원 무료
        Alpha activities can be used for categorization, transportation, and disposal of radioactive waste generated from the operation of nuclear facilities including nuclear power plants. In order to transport and dispose of such low- and intermediate-level radioactive waste (LILW) to the Wolsong LILW Disposal Center (WLDC) at Gyeongju, the gross alpha concentration of an individual drum should be determined according to the acceptance criteria. In addition, when the gross alpha concentration exceeds 10 Bq/g, the inventory of the comprising alpha emitters in the waste is to be identified. Gross alpha measurements using a proportional counter are usually straightforward, inexpensive, and high-throughput, so they are broadly used to assay the total alpha activity for environmental, health physics, and emergency-response assessments. However, several factors are thoughtfully considered to obtain a reliable approximate for the entire alpha emitters in a sample, which include the alpha particle energy of a particular radionuclide, the radionuclide that is used as a calibration standard, the uniformity of film in a planchet, time between sample collection and sample preparation, and time between sample preparation and counting. Korea Atomic Energy Research Institute (KAERI) have evaluated the inventory of radionuclides in low-level radioactive waste drums to send every year hundreds of them to the WLDC. In this presentation, we revisit the gross alpha measurement results of the drums transported to WLDC in the past few years and compare them with the concentrations of alpha emitters measured from alpha spectrometry and gamma spectrometry. This study offers an insight into the gross alpha measurement for radioactive waste regarding calibration source, self-absorption effect, composition of alpha emitters, etc.
        2.
        2022.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        The decommissioning of nuclear facilities produces various types of radiologically contaminated waste. In addition, dismantlement activities, including cutting, packing, and clean-up at the facility site, result in secondary radioactive waste such as filters, resin, plastic, and clothing. Determining of the radionuclide content of this waste is an important step for the determination of a suitable management strategy including classification and disposal. In this work, we radiochemically characterized the radionuclide activities of filters used during the decommissioning of Korea Research Reactors (KRRs) 1 and 2. The results indicate that the filter samples contained mainly 3H (500–3,600 Bq·g−1), 14C (7.5–29 Bq·g−1), 55Fe (1.1– 7.1 Bq·g−1), 59Ni (0.60–1.0 Bq·g−1), 60Co (0.74–70 Bq·g−1), 63Ni (0.60–94 Bq·g−1), 90Sr (0.25–5.0 Bq·g−1), 137Cs (0.64–8.7 Bq·g−1), and 152Eu (0.19–2.9) Bq·g−1. In addition, the gross alpha radioactivity of the samples was measured to be between 0.32–1.1 Bq·g−1. The radionuclide concentrations were below the concentration limit stated in the low- and intermediatelevel waste acceptance criteria of the Nuclear Safety and Security Commission, and used for the disposal of the KRRs waste drums to a repository site.
        4,300원
        3.
        2022.10 구독 인증기관·개인회원 무료
        We established pretreatment method of solidified cement ion-exchange resin samples generated before 2003 in nuclear power plants for measurement of non-volatile radionuclide activity. A microwave digestion system (MDS) with mixed acid (HCl-HNO3-HF-H2O2) was used to dissolve cement and to desorb non-volatile elements such as Ce, Co, Cs, Fe, Nb, Ni, Re, Sr and U from mixed ion-exchange resin. The content of Ce, Co, Fe, Nb, Ni, Re, Sr, U and Cs after pretreatment of cement plus mixed ion-exchange resin was measured by ICP-AES and ICP-MS, respectively. As iron and strontium are also present in cement, their content after dissolving a certain amount of cement was measured by ICP-AES. All elements except Nb were quantitatively recovered. Especially since the Nb recovery was low at 72.0±2.5%, the MDS following addition of the mixed acid to the resin was operated once more for desorbing Nb from it. Finally the recovery of Nb was over 95%. This sample pretreatment method will be applied to solidified cement ion-exchange resin samples generated in nuclear power plants for assessment of radionuclide inventory.
        9.
        2019.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The aim of this study was to investigate effect of heat stress on expression levels of plasminogen activators (PAs) related mRNAs and proteins, and changes of PAs activity in porcine endometrial explants. The endometrial explants (200 ± 50 mg) were isolated from middle part of uterine horn at follicular phase (Day 19-21) and were pre-incubated in serum-free culture medium at 38.5oC in 5% CO2 for 18 h. Then, the tissues were transferred into fresh medium and were cultured at different temperature (38.5, 39.5, 40.5 or 41.5oC) for 24 h. The expression level of urokinase-type PA (uPA), type-1 PA inhibitor (PAI-1), type-2 PAI (PAI-2), and heat shock protein-90 (HSP-90) mRNA were analysis by reverse-transcription PCR and proteins were measured by western blotting. The supernatant were used for measurement of PAs activity. In results, mRNA and protein levels of HSP-90 was higher in 41.5oC treatment groups than other treatment groups (p < 0.05). The expression of uPA, PAI-1, and PAI-2 mRNA were slightly increased by heat stress, however, there were no significant difference. Heat stress condition suppressed expression of active uPA and PAI-2 proteins (p < 0.05), whereas PAI-1 protein was increased (p < 0.01). Although PAI-1 protein was increased and active uPA was decreased, PAs activity was greatly enhanced by exposure of heat stress (p < 0.05). These results suggest that heat stress condition could change intrauterine microenvironment through regulation of PAs activity and other factors regarding with activation of PAs might be regulate by heat stress. Therefore, more studies regarding with regulatory mechanism of PAs activation are needed.
        4,000원
        10.
        2018.11 구독 인증기관·개인회원 무료
        In our previous study, exogenous plasminasminogen activators (PAs) influenced to fertility of boar spermatozoa via reduction of zona pellucida (ZP) resistance against protease and number of sperm binding ZP. plasminasmin (plasmin), is converted by PAs, is an important enzyme to degrade extracellular matrix and it is closely associated with fertilization process. Therefore, the aim of present study was to confirm changes of sperm penatration and ZP solubility by plasmin during in vitro fertilization (IVF). The cumulus-oocyte complasminexes (COCs) were aspirated from the antral follicles 3-6 mm in diameter and matured for 44 hours. Then, the cumulus cells were removed and denuded oocytes were co-incubated with spermatozoa for 18-20 hours in IVF medium containing 100 ng/ml plasmin. The number of sperm binding ZP and ZP solubility were measured using hoechst 33342 and 0.5% (w/v) pronase, respectively. Aceto-orcein stain was used to assess fertilization parameters. In results, sperm penetration did not affect by plasmin treatment during fertilization. Hoewever, treatment of plasmin decreased monospermic fertilization and IVF efficiency compared with control group (p<0.05). Furthermore, the number of penetrated sperm and pronucleus formation per zygote in plasmin group was significantly increased compared with control group (p<0.05). Despite of reduced monospermic fertilization by plasmin treatment, the number of sperm binding ZP was significantly higher in non-treated zygote than plasmin-treated zygote (p<0.05). Similar with previous study, ZP digestion time was reduced by plasmin treatment (p<0.05). These findings shown that plasminasmin during fertilization enhance the penetration of spermatozoa into ZP via increasing of ZP solubility and it was correspond with our previous results that fertility of spermatozoa during IVF was increased by exogenous urokinase-type PA treatment via sperm-ZP binding and increase of ZP solubility. Therefore, during the fertilization process, plasmin that is converted by PAs from oviduct epithelial cells might be closely associated with degradation of ZP proteins for penetration of sperm. This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (Ministry of Education) (2016R1D1A1B03931746).
        11.
        2018.07 구독 인증기관·개인회원 무료
        This paper investigates a theoretical and experimental evidence for a niche strategy for small and medium online shopping malls to survive against large famous shopping malls dominating the E-commerce market. The present study explored both theoretically and empirically how consumers’ preferences for alternatives in online shopping context are affected by their construal level and concentrated its efforts on the verification of the phenomenon under various frames and regarding various categories(Liberman and Trope 1998; Liberman, Trope, and Stephan 2007, Liberman Trope, and Wakslak 2007). For this, this study demonstrates how chronic construal levels of consumers may affect their alternative choice for online shopping via various contexts (Experiment 1-3) and categories (Experiment 3-5). This series of experiments suggests that consumers with high construal level can be defined as a group that is relatively less susceptible to reputation of the shopping malls. Thus, strategically targeting this group of consumers will help small online malls lacking store reputation to mitigate their competitive disadvantage. Based on both existing literature and the experimental results as above, this research discusses possible methods for small online shopping malls to target high-construal segmentation.
        12.
        2017.06 구독 인증기관 무료, 개인회원 유료
        A stable supply of seafarers is an important issue for Korean maritime industries and related business activities. After four years of their role on a ship, Korean maritime officers are increasingly being separated from their fellow sailors. The present paper reviews the trend and characteristics in the separation rate of maritime officers, and examines the main factors affecting the separation rate through panel data models. The paper collects the panel data of maritime officers from 2007 to 2014. The main results of panel data models show us that the separation rate is affected mainly by the duration (period) after graduation. The unemployment rate in all industries and the relative wage level of seafarers affect negatively the separation rate. The dummy variable for the completion year of military services shows positive coefficients. We can conclude that the labour market of seafarers is affected by the employment situation in all industries.
        4,000원
        14.
        2016.07 구독 인증기관·개인회원 무료
        The purpose of this study is to present theoretical and experimental evidence for a niche strategy for small and medium online shopping malls to run business against large famous shopping malls prevailing the E-commerce market. For this, the present study demonstrates how chronic construal levels of consumers may affect their alternative choice for online shopping via various contexts (Experiment 1-3) and categories (Experiment 3-5). This series of experiments suggests that consumers with high construal level can be defined as a group that is relatively less susceptible to reputation of the shopping malls. Thus, strategically targeting this group of consumers will help small and medium-sized online malls lacking store reputation to mitigate their competitive disadvantage. Based on both existing literature and the experimental results as above, this research discusses possible methods for small and medium-sized online shopping malls to target high-construal segmentation.
        15.
        2016.06 구독 인증기관 무료, 개인회원 유료
        As a one of unsaturated fatty acid, polyunsaturated fatty acids (PUFAs) have multiple actions: as precursor of prostaglandins (PGs), steroid hormone synthesis and energy production in animal reproduction. PUFAs, which include omega-3 (n-3) and omega-6 (n-6), are derived from the diet and changed by diet, species, breed and season. The plasma membrane of spermatozoa in mammals contain various PUFAs. These composition of PUFAs regulate the membrane fluidity and cause lipid peroxidation via generation of reactive oxygen species (ROS). Induced lipid peroxidation by ROS decreased viability and motility of spermatozoa, and it is reduced by addition of antioxidant and low concentration of PUFAs. Because oocytes of animal have a high lipid components, process of oocyte maturation and embryo development are influenced by PUFAs. In in vitro study, oocyte maturation, embryo development, intracellular cAMP and MAPK activity were increased by treatment of n-3 α-linolenic acid (ALA) during maturation, whereas n-6 linoleic acid (LA) negatively influenced. Also, inhibition of fatty acid metabolism in oocyte influenced blastocyst formation of cattle. PGs are synthesized from PUFAs and various PUFAs influence PGs via regulation of PG-endoperoxide synthase (PTGS). Steroid hormone synthesis from cholesterol is regulated by expression of steroid acute regulator (StAR) protein and mRNA. Exogenous n-3 and n-6 PUFAs altered sex hormone in animal through stimulate or inhibit StAR activity. Because PUFAs altered PG and steroid hormone synthesis, follicular development was influenced by PUFAs. This effect of unsaturated fatty acid could provide information for improvement of reproductive ability in animals.
        4,000원
        17.
        2014.06 구독 인증기관 무료, 개인회원 유료
        Plasminogen activators (PAs) are serine proteases that convert plasminogen to plasmin. Two type of PAs are urokinase-type PA (uPA) and tissue-type PA (tPA). Plasminogen is present in most extracellular fluids. PAs play in various reproductive processes including implantation, ovulation and fertilization. In the spermatozoa, PAs and PAIs play a role in sperm motility and fertilization. PAs in the sertoli cell are stimulated spermatozoa maturation and sperm activation through the phospholipase A2. The oocyte maturation is the process for fertilization and implantation. PAs in cumulus-oocyte complexes (COCs) are related to oocyte maturation by protein kinase A and C. In the ovulatory process, PAs activity are changed and it are related to reducing the tensile strength of ovarian follicle wall. The uterine environment is important for reproduction and the uterus undergo tissue remodeling. In the uterus and oviduct of mammals, expression and activity of PAs are changed during estrous cycle. Thus, expression and activity of PAs are concerned to many reproductive functions. Therefore, PAs seem to important factor of regulator in reproductive events.
        4,000원
        18.
        2013.10 구독 인증기관·개인회원 무료
        F. occidentalis causes to decrease the yield of chrysanthemum flower economically because it is the major crop pest injuring the flower directly at flowering period in chrysanthemum artificial houses. The control of it with chemicals is very difficult because the resistance of it to chemicals is so high. F. occidentalis began to occur at early-May and increased rapidly mid-May after in standard chrysanthemum artificial houses, Yesan, Chungcheongnam-do. In case of a farm, the density of it increased continuously in spite of chemical control . The times of chemical control to depress the density of it was 6 or 7th for cultivation period of chrysanthemum. We put the flowering yellow pot-mum already (trap plant attracting F. occidentalis) in standard chrysanthemum PVC-houses and set the yellow sticky cards up at an interval of 5m from trap plant(TP). The more yellow sticky trap near to trap plant, the more F. occidentalis was attracted to yellow sticky trap. TP was more attractive to adult F. occidentalis up to distances of 10m. The numbers of it attracted to yellow sticky traps at different distance from TP was not different significantly when standard chrysanthemum bloomed. We put the TP in standard chrysanthumum PVC-house at an distance of 20m and released the natural enemies (Orius laevigatus) on TP at 3 times, an interval of 7 days. And then we set yellow sticky traps up at an distance of 5m from TP and compared the plot with TP+natural enemy(NE) to the plot without them. The density of F. occidentalis was rather lower at TP+NE plot than the plot without at the formative period of flower bud of standard chrysanthemum. Therefore, The yellow flowering chrysanthemum possesses great value of TP attracting F. occidentalis in chrysanthumum PVC-house up to flowering period of cultivating chrysanthemum, and if it is used with natural enemy and chemicals simultaneously, farmers can minimize the quantity of chemicals used.
        19.
        2013.04 구독 인증기관·개인회원 무료
        Myanmar is located in the Southeastern region of Asia. It lies between latitudes 9° and 29°N, and longitudes 92° and 102°E. The bordering countries are China on the northern side, Thailand and Laos on the eastern region, Bangladesh on the western side and India on the northwestern region. Myanmar has a total area of 678,500 square kilometers (262,000 sq mi). The rainy season exists primarily during the months between June and September. Whiledry season stays during the months between December and April. Northern regions of the country are the coolest, with average temperatures of 21 ℃ (70 ℉). Coastal and delta regions have an average temperature of 32 ℃ (86.9 ℉). This expedition was conducted four times for three years. Among them we explored three area including Popa Mountain, Alaungdaw Kathapa National Park and Nat Ma Taung National Park[Popa Mountain(8.7~8.17, 2011; 7.24~8.3 2012; 2.18~2.28 2013), Alaungdaw Kathapa National Park(2.2~2.9, 2012) and Nat Ma Taung National Park(2.18~2.28 2013)]. Collecting methods was sweeping net, lignt trap, burket trap, pitfall trap with other method, and collected especially mainly Coleoptera and Lepidoptera. As the result, totally about 30 families in Coleoptera and 7 families in Lepidoptera were collected, among them Carabidae and Nymphalidae was revealed most diversity species. Main collect specimens, expedition activities and collections data etc. were provided herein.
        20.
        2012.10 구독 인증기관·개인회원 무료
        Many bumblebee species have declined in number in recent decades, particularly in developing regions. Widespread declines of bumblebee species threaten the pollination levels of both wildflowers and crops. Here, we investigated the body weight and colony-developmental characteristics of Korean native bumblebee (B. ignitus) queens collected from 2000 to 2010 for conservation of native bumblebees for breeding. The average weight of 6,852 queens was 0.77 ± 0.44 g. The weight of B. ignitus queens collected in 2005 was the greatest, 0.87 ± 0.12 g, which was 1.0–1.3-fold heavier than any other year. The average oviposition rate was 81.6 ± 10.7%, and 2004 showed the highest rate, 95.0%. This value corresponded to 1.1-1.6-fold increases over the queens collected in the other years. The average rate of colony foundation was 60.9 ± 11.0%. Queens in 2008 exhibited the best performance, 75.4%, which was 1.0-1.9-fold higher than the other years. The rate of progeny-queen production averaged 27.0 ± 9.4% (Fig. 5) and peaked in 2001 at 43.2%; this value was 1.1–4.7-fold higher than other years. The average number of queens produced and number of generations begotten by queens was 27.6 ± 10.1% and 4.8 ± 2.0, respectively. Queens in 2000 averaged 9 generations of offspring, which was 1.1-3.1-fold greater than other years. These results indicate that the colony-developmental characteristics of the collected queens changed significantly between 2000 and 2010. In addition, there was no correlation between body weight and number of queens collected, although body weight was affected by collection year. Since 2008, the colony- developmental characteristics of queens have worsened.
        1 2 3 4 5