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        검색결과 18

        1.
        2023.11 구독 인증기관·개인회원 무료
        Activated carbon (AC) is used for filtering organic and radioactive particles, in liquid and ventilation systems, respectively. Spent ACs (SACs) are stored till decaying to clearance level before disposal, but some SACs are found to contain C-14, a radioactive isotopes 5,730 years halflife, at a concentration greater than clearance level concentration, 1 Bq/g. However, without waste acceptance criteria (WAC) regarding SACs, SACs are not delivered for disposal at current situation. Therefore, this paper aims to perform a preliminary disposal safety examination to provide fundamental data to establish WAC regarding SACs SACs are inorganic ash composed mostly of carbon (~88%) with few other elements (S, H, O, etc.). Some of these SACs produced from NPPs are found to contain C-14 at concentration up to very-low level waste (VLLW) criteria, and few up to low-level waste (LLW) criteria. As SACs are in form of bead or pellets, dispersion may become a concern, thus requiring conditioning to be indispersible, and considering VLL soils can be disposed by packaging into soft-bags, VLL SACs can also be disposed in the same way, provided SACs are dried to meet free water requirement. But, further analysis is required to evaluate radioactive inventory before disposal. Disposability of SACs is examined based on domestic WAC’s requirement on physical and chemical characteristics. Firstly, particulate regulation would be satisfied, as commonly used ACs in filters are in size greater than 0.3 mm, which is greater than regulated particle size of 0.2 mm and below. Secondly, chelating content regulation would be satisfied, as SACs do not contain chelating chemicals. Also, cellulose, which is known to produce chelating agent (ISA), would be degraded and removed as ACs are produced by pyrolysis at 1,000°C, while thermal degradation of cellulose occurs around 350~600°C. Thirdly, ignitability regulation would be satisfied because as per 40 CFR 261.21, ignitable material is defined with ignition point below 60°C, but SACs has ignition point above 350°C. Lastly, gas generation regulation would be satisfied, as SACs being inorganic, they would be targeted for biological degradation, which is one of the main mechanism of gas generation. Therefore, SACs would be suitable to be disposed at domestic repositories, provided they are securely packaged. Further analysis would be required before disposal to determine detailed radioactive inventories and chemical contents, which also would be used to produce fundamental data to establish WAC.
        2.
        2023.11 구독 인증기관·개인회원 무료
        Domestic waste acceptance criteria (WAC) require flowable or homogeneous wastes, such as spent resin, concentrated waste, and sludge, etc., to be solidified regardless of radiation level, to provide structural integrity to prevent collapse of repository, and prevent leaching. Therefore, verylow level (VLL) spent resin (SR) would also require to be solidified. However, such disposal would be too conservative, considering IAEA standards do not require robust containment and shielding of VLL wastes. To prevent unnecessary cost and exposure to workers, current WAC advisable to be amended, thus this paper aims to provide modified regulation based on reviewed engineering background of solidification requirement. According to NRC report, SR is classified as wet-solid waste, which is defined as a solid waste produced from liquid system, thus containing free-liquid within the waste. NRC requires liquid wastes to be solidified regardless of radiation level to prevent free liquid from being disposed, which could cause rapid release of radionuclides. Furthermore, considering class A waste does not require structural integrity, unlike class B and C wastes, dewatering would be an enough measure for solidification. This is supported by the cases of Palo Verde and Diablo Canyon nuclear power plants, whose wet-solid wastes, such as concentrated wastes and sludge, are disposed by packaging into steel boxes after dewatering or incineration. Therefore, dewatering VLL spent resin and packaging them into structural secure packaging could satisfy solidification goal. Another goal of solidification is to provide structural support, which was considered to prevent collapse of soil covers in landfills or trenches. However, providing structural support via solidification agent (ex. Cement) would be unnecessary in domestic 2nd phase repository. As the domestic 2nd phase repository is cementitious structure, which is backfilled with cement upon closure, the repository itself already has enough structural integrity to prevent collapse. Goldsim simulation was run to evaluate radiation impact by VLL SR, with and without solidification, by modelling solidified wastes with simple leaching, and unsolidified wastes with instant release. Both simulations showed negligible impact on radiation exposure, meaning that solidifying VLL SR to delay leaching would be irrational. Therefore, dewatering VLL SR and packaging it into a secure drum (ex. Steel drum) could achieve solidification goals described in NRC reports and provide enough safety to be disposed into domestic repositories. In future, the studied backgrounds in this paper should be considered to modify current WAC to achieve efficient waste management.
        4.
        2022.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        A total of 31 bacterial strains were isolated from the Geum River basin in the Republic of Korea during our investigation of indigenous prokaryotic species. The isolated bacterial strains had high 16S rRNA gene sequence similarity (>98.7%) with those of validly published bacterial species, which have not been reported in Republic of Korea. The 31 bacterial strains were phylogenetically diverse and assigned to 4 phyla, 8 classes, 18 orders, 21 families, and 27 genera. At the genus level, the unreported species were affiliated with Kineococcus, Pedococcus, Rhodoluna, Salinibacterium, Rhodoluna, Arthrobacter, Williamsia, Nakamurella, Nocardioides of the class Actinobacteria, Patulibacter of the class Thermoleophilia, Pontibacter, Hymenobacter of the class Cytophagia, Flavobacterium of the class Flavobacteriia, Geomicrobium of the class Bacilli, Brevundimonas, Gellertiella, Rhizobium, Paracoccus, Taonella, Sphingomonas of the class Alphaproteobacteria, Burkholderia, Polaromonas, Hydrogenophaga, Chitinilyticum, Azospira, Zoogloea of the class Betaproteobacteria, and Pseudomonas of the class Gammaproteobacteria. The unreported bacterial species were further characterized by examining their morphological, cultural, physiological, and biochemical properties. The detailed descriptions of the 31 bacterial strains were provided.
        4,500원
        5.
        2022.10 구독 인증기관·개인회원 무료
        Glass fiber (GF) insulation is a non-combustible material, light, easy to transport/store, and has excellent thermal insulation performance, so it has been widely used in the piping of nuclear power plants. However, if the GF insulation is exposed to a high-temperature environment for a long period of time, there is a possibility that it may be crushed even with a small impact due to deterioration phenomenon and take the form of small particles. In fact, GF dust was generated in some of the insulation waste generated during the maintenance process. In the previous study, the disposal safety assessment of GF waste was performed under the abnormal condition of the disposal facility to calculate the radiation exposure dose of the public residing/ residents nearby facilities, and then the disposal safety of GF waste was verified by confirming that the exposure dose was less than the limit. However, the revised guidelines for safety assessment require the addition of exposure dose assessment of workers. Therefore, in this study, accident scenarios at disposal facilities were derived and the exposure dose to the workers during the accident was evaluated. The evaluation was carried out in the following order: (1) selection of accident scenario, (2) calculation of exposure dose, (3) comparison of evaluation results with dose limits, and confirmation of satisfaction. The representative accident scenarios with the highest risk among the facility accident were selected as; (a) the fire in the treatment facility, (b) the fire in the storage facility, and (c) fire after a collision of transport vehicles. The internal and external exposure doses of the worker by radioactive plume were calculated at 10m away from the accident point. In evaluation, the dose conversion factors ICRP-72 and FGR12 were used. As a result of the calculation, the exposure dose to workers was derived as about 0.08 mSv, 0.20 mSv, and 0.10 mSv, due to fire accidents (vehicle collision, storage facilities, treatment facilities). These were 0.2%, 0.4%, and 0.2% of the limit, and the radiation risk to workers was evaluated to be very low. The results of this study will be used as basic data to prove the safety of the disposal of GF waste. The sensitivity analysis will be performed by changing the radiation source and emission rate in the future.
        14.
        1996.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        배관을 구속시키기 위한 원동형 배관 지지대 (Trunnion Pipe Support) 까 부착된 uß 간의 응-딱해석플 위하 여 유한요소해석을 사용하였다. 해석션파로 부터 얻어진 응역은 두께에 대한 평칸(막응역) 넷 선행 응→박( ""," 힘응력) 으로 분류 되었므며, 분류된 응벽값은 암략에 악한 언차응략겨l 수 (B 1 ) 와 이자응역겨l 수 (C 1 ) , 보멘트에 의한 일차응력계수 (B" , Bιr) 와 이차응략셰수 (C객, C!T) 플- 추성하시 위하여 ASME Code 에 성의뭔것파 일치 하게 해석되었다 무차원의 함수로써 응력 세수에 대한 경험식 얀 새만히기 위하여 여서 ~i~ l;'l 의 해삭 2~ 수행하 였다.
        4,000원
        15.
        2016.05 서비스 종료(열람 제한)
        Background : This study was conducted to developed the propagation method by cutting for mass cultivation of Vitex roundifolia. We were pitched the cutting two times and treated plant growth regulators to enhance the rooting percentage. Vitex roundifolia is live in beach sandy soil south of Hwanghae-Do and Gangwon-Do. Vitex roundifolia have been used to bath foam. It is good for aromatic plant. It has 0.8% essential oil content in leaf and flower. Major components of essential oil were alpha-Pinene, Sabinene, beta-Pinen, 1,8-cineole, d-Limone. Despite the superior usability, it had not yet been made by the artificial cultivation Methods and Results : We were pitched the cutting of a first-year branch on June 5, which was greenwood cutting and July 17, which was semi-hardwood cutting at Kwangseung-ri beach, Gochanggun, Jeonbuk. The length of cutting was 10cm. It had 3~4 nodes, we stuck a cutting remain 2 nodes above ground on ordinary raise seedling soil. Rooting percentage was measured at 60 days after stuck a cutting. Rooting percentage was higher greenwoody cutting(95%) than semi-hardwood cutting(57.6%). In green wood cutting, there was no significance with plant growth, but chemical injury was occurred in IBA 5,000ppm. In semi-hardwood cutting, there was significance with plant growth regulators. The rooting percentages of all the treat were higher than control(no treatment). Rooting percentage was the highest in NAA 5,000ppm treated. Conclusion : Greenwood cutting method was more proper to propagation for Vitex roundifolia than semi-hardwood cutting. The optimum time to cutting for Vitex roundifolia propagation was the early in June. If miss a time to propagation Rooting percent was elevated by plant growth regulator.
        17.
        2003.06 KCI 등재 서비스 종료(열람 제한)
        “Surabyeo” is a new japonica rice cultivar developed from a backcrossed combination between the F1 of “Suweon 345/ Kanto PL4” and “Suweon 345” of lodging tolerant, semi-dwarf, high-quality rice line by the rice breeding team of National Crop Experiment St
        18.
        1995.10 KCI 등재 서비스 종료(열람 제한)
        본 실험은 온실과 포장에서 재배한 알팔파를 잎, 줄기, 뿌리, 꽃 부분으로 나누어 수확, 건조,하여 물 추출한 후 이 추출물들이 알팔파 발아와 생육에 미치는 영향을 조사 비교하였으며 포장상태에서 자란 알팔파 지상부 전체를 수확,건조, 추출하여 이를 농도별로 처리 알팔파 발아율을 검정하였고, pot실험을 통하여 알팔파 품종간 biomass 분배율 검정과, 알팔파 autotoxicity를 해결하기 위한 방법으로 추출물을 adsorbent로 처리하여 이들이 알팔파 독성성분을 변형시키는지를 검토하였다. 1. 온실과 포장에서 자란 알팔파의 추출물로 알팔파 발아 및 생육에 대한 영향을 비교한 결과 포장에서 자란 추출물질이 발아와 생육에 더 억제적으로 작용하였고, 특히 포장에서 생육한 꽃 추출물 처리가 가장 억제적으로 작용하였다. 2. 농도처리에 따르는 추출물 처리는 농도가 증가 할수록 발아율이 억제되었고, biomass분배율에 대한 pot실험에서는 LWR 과 SLA의 산물인 LAR은 품종간 유의성을 보였다. 3. 알팔파 추출물에 대한 absorbents처리는 추출물의 독성을 변형시키지 못하였다.