• Journal of Species Research
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• 제9권3호
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• pp.273-279
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• 2020

We describe a newly recorded brittle star to South Korea, Amphiura (Amphiura) digitula (H.L. Clark, 1911), that was collected from Geoje Island, at a depth of 47 m. The species is characterized by a small disk, covered by numerous fine scales, small radial shields that are wider than long, a small stumpy hook at the distal end of the radial shield, two tooth papilla, two adoral shield spines, 2nd adoral shield spine longer than other, tapered dramatically toward dull tip, five arms with four proximal arm spines, and two tentacle scales. We also obtained a 657 bp sequence from COI gene and the amplified sequence matched the general DNA barcoding region. The NJ and ML phylogenetic analyses revealed A. (A.) digitula as monophyletic in the Amphiura clade. This species is clearly distinguished from other Amphiura species by morphological characteristics and the mitochondrial COI sequence, and thus represents the sixth Amphiura species reported to occur in Korea.

• Nuclear Engineering and Technology
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• 제48권3호
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• pp.785-794
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• 2016

The Argonne National Laboratory of the United States and the Kharkov Institute of Physics and Technology of the Ukraine have been collaborating on the design, development and construction of a neutron source facility at Kharkov Institute of Physics and Technology utilizing an electron-accelerator-driven subcritical assembly. The electron beam power is 100 kW using 100-MeV electrons. The facility was designed to perform basic and applied nuclear research, produce medical isotopes, and train nuclear specialists. The biological shield of the accelerator building was designed to reduce the biological dose to less than 5.0e-03 mSv/h during operation. The main source of the biological dose for the accelerator building is the photons and neutrons generated from different interactions of leaked electrons from the electron gun and the accelerator sections with the surrounding components and materials. The Monte Carlo N-particle extended code (MCNPX) was used for the shielding calculations because of its capability to perform electron-, photon-, and neutron-coupled transport simulations. The photon dose was tallied using the MCNPX calculation, starting with the leaked electrons. However, it is difficult to accurately tally the neutron dose directly from the leaked electrons. The neutron yield per electron from the interactions with the surrounding components is very small, ~0.01 neutron for 100-MeV electron and even smaller for lower-energy electrons. This causes difficulties for the Monte Carlo analyses and consumes tremendous computation resources for tallying the neutron dose outside the shield boundary with an acceptable accuracy. To avoid these difficulties, the SOURCE and TALLYX user subroutines of MCNPX were utilized for this study. The generated neutrons were banked, together with all related parameters, for a subsequent MCNPX calculation to obtain the neutron dose. The weight windows variance reduction technique was also utilized for both neutron and photon dose calculations. Two shielding materials, heavy concrete and ordinary concrete, were considered for the shield design. The main goal is to maintain the total dose outside the shield boundary less than 5.0e-03 mSv/h during operation. The shield configuration and parameters of the accelerator building were determined and are presented in this paper.

• Animal Systematics, Evolution and Diversity
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• 제25권2호
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• pp.189-195
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• 2009

Two new species of the genus Nesodillo Verhoeff, 1926, N. kimi and N. philippinensis, are described from Philippines. For the shape of frontal shield, Nesodillo kimi resembles N. monticola (Vandel, 1973) from New Guinea, but differs from it in the shape of male pleopod 1 exopod. N. philippinensis is distinguished from N. kimi by the shape of frontal shield not depressed in the middle of upper border, and of telson with broadly rounded distal margin.

• 방사성폐기물학회지
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• 제15권4호
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• pp.355-367
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• 2017

2017년 6월에 영구정지 된 고리 1호기의 해체는 한국의 상업 원전에 대한 첫 해체 사례가 될 것이다. 해체 과정 중에 발생하는 폐기물에 대한 처분은 전체 해체 비용의 많은 부분을 차지한다. 따라서 방사화 및 오염된 콘크리트 구조물은 적절한 해체전략을 수립하여 경제적이고 안전하게 해체되어야 한다. 본 논문에서는 생물학적 차폐체에 대한 최적화된 해체 및 처분 시나리오를 연구하였다. 해체사례, 폐기물 처분 규정 및 처리 기술을 분석하였다. 그리고 생물학적 차폐체 제거 과정의 폐기물 발생량을 최소화하기 위해서, 최적 해체 시나리오를 제시하였고 폐기물 처분 방안을 도출하였다.

• Nuclear Engineering and Technology
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• 제50권6호
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• pp.989-995
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• 2018

Argonne National Laboratory of the United States and Kharkov Institute of Physics and Technology (KIPT) of Ukraine have cooperated on the development, design, and construction of a neutron source facility. The facility was constructed at Kharkov, Ukraine, and its commissioning process is underway. The facility will be used for researches, producing medical isotopes, and training young nuclear specialists. The neutron source facility is designed with a provision to include a cryogenically cooled moderator system-a cold neutron source (CNS). This CNS provides low-energy neutrons, which will be used in the scattering experiment and material structures analysis. Cold neutron guides, coated with reflective material for the low-energy neutrons, will be used to transport the cold neutrons to the experimental site. The cold neutron guides would keep the cold neutrons within certain energy and angular space concentrated inside, while most of the gamma rays and high-energy neutrons are not affected by the cold neutron guides. For the KIPT design, the cold neutron guides need to extend several meters outside the main shield of the facility, and curved guides will also be used to remove the gamma and high-energy neutron. The neutron guides should be installed inside a shield structure to ensure an acceptable biological dose in the facility hall. Heavy concrete is the selected shielding material because of its acceptable performance and cost. Shield design analysis was carried out for the CNS guide hall. MCNPX was used as the major computation tool for the design analysis, with neutron and gamma dose calculated separately. Weight windows variance reduction technique was also used in the shield design. The goal of the shield design is to keep the total radiation dose below the $5.0{\mu}Sv/hr$ guideline outside the shield boundary. After a series of iterative MCNPX calculations, the shield configuration and parameters of CNS guide hall were determined and presented in this article.

• 디지털융복합연구
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• 제10권1호
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• pp.271-276
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• 2012

최근 전파의 이용이 급증하면서 전파가 인체에 미치는 영향에 대한 관심이 높아지고 있다. 전파가 인체에 미치는 영향에 관한 많은 연구 결과 많은 것이 밝혀졌으나, 실제 전자계 환경에서 인체 보호에 관한 연구는 찾아보기 어렵다. 실험을 위해서 강한 전파를 다루는 연구자들에게 직접적인 보호 방법은 아주 중요한 문제이다. 본 논문에서는 간단한 구조의 차폐를 통한 인체 내 전력 흡수율(SAR) 저감시키기 위한 보호 방법을 제안하고, 2개의 원통형 인체모델을 이용하여 완전도체로 구성한 차폐판 크기와 조사방향에 따른 SAR의 저감효과를 계산하여 그 유효성을 확인하였다.

• Safety and Health at Work
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• 제5권1호
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• pp.23-26
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• 2014

Background: The purpose of this study was to compare the concentration of total airborne bacteria (TAB) in biosafety cabinets (BSCs) at universities and hospital microbial laboratories to assess the performance of BSCs. Methods: TAB was determined by using the single-stage Anderson sampler (BioStage Viable Cascade Impactor). The samples were obtained three times (with the BSC turned off and the shield open; with the BSC turned off and the shield closed; and with the BSC tuned on and operating) from the areas in front of 11 BSCs. Results: TAB concentrations of accredited and nonaccredited BSCs were determined. No significant differences were observed in the TAB concentrations of the accredited BSCs and the nonaccredited BSCs for the areas outside the BSCs in the laboratories (p > 0.05). TAB concentrations for the BSCs sampled with the shield open and the instrument turned off showed differences based on the sampling site outside the BSC in each laboratory. Conclusion: These results imply that TAB concentration is not altered by the performance of the BSCs or TAB itself and/or concentration of TAB outside the BSC is not a good index of BSC performance.

• Journal of Ecology and Environment
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• 제35권4호
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• pp.301-306
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• 2012

Determination of the minimum population size is an important component for the ex situ conservation of an endangered species. Here, we present the identification of collection strategies that most efficiently captured the genetic diversity of Brasenia schreberi J.F. Gmelin (water-shield) in natural populations from the mainland (MGC) and Jeju Island (JNS) of South Korea, using amplified fragment length polymorphism (AFLP) markers. A total of 313 and 383 polymorphic bands were detected in the MGC and JNS populations, respectively. All of the 140 sampled ramets were distinguishable by the presence of distinct AFLP phenotypes. According to the simulation of the individual sampling by maximization sampling, 25 and 28 individuals captured all of the genetic diversity in the MGC population (mainland of South Korea) and the JNS population (Jeju Island), respectively. The level of genetic diversity of the core collections was similar to the entire collection, indicating that the core collections very well represent the diversity of the entire collection. We therefore suggest a management unit of B. schreberi based on the genetic information for assessing the minimum population size for its ex situ conservation.

• Nuclear Engineering and Technology
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• 제2권3호
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• pp.149-161
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• 1970

국내에서 산출되는 광물골재를 사용하여 방사선 차폐용 중차폐 콘크리트를 제조하고 감마선에 대한 차폐효능을 규명하는 동시에 방사선 차폐체로서의 활용가능성을 검토하였다. 10여종의 각기 다른 광물골재를 수집하여 방사선 차폐용 골재로서의 사용타당성을 검토하기 위한 물리시험과 화학분석이 실시되었고 이 결과를 토대로 최적한 골재를 선택하여 중차폐 콘크리트가 제조되었다. 차폐용 콘크리트를 제조하는데 골재의 배합비, 물-세멘트 비율, 세골재, 조골재 비율 등을 달리해주므로써 방사선 차폐효과가 달라지는 현상을 실험적으로 구해 보았고 그 결과 차폐체의 비중이 높고 균질성이 좋은 중차폐체의 설계 조건을 유도해 낼수 있었다. 각기 다른 중차폐체에 대한 차폐효능 실험은 60Co 감마선원을 사용한 방사선 투과시험법으로 구했다. 실험을 통하여 중차폐체에 대한 방사선 차폐능과 차폐콘크리트의 비중, 차폐가격등을 분석하므로써 차폐설계상 최적의 공간배치로서 가장 경제적으로 차폐치를 설계할 수 있는 최적의 조건을 얻을 수 있었다.

• 한국전자파학회지:전자파기술
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• 제2권3호
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• pp.17-25
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• 1991

자기부상열차 시스템에서의 자속 누설은 주로 부상용 전자석과 리니어 모터, 안내용 전자석으로 부터 발생하 여 intra - system 및 inter - system EMI 현상과 biological effect을 야기할 수 있다. 본 논문에서는 누설 자속의 크기에 영향을 주는 각종 요소들을 고려하여 열차 주위에 분포하는 자기장의 세기를 계산하였으며, 여기서 얻어진 결과를 이용하여 차제 바닥과 측면에 사용되는 구조물의 재질과 위치에 따른 최소 두께를 계산하여 자기장 차폐를 위해 차체 무게가 증대되는 것을 최소로 할 수 있는 방법을 제시하였다. 이 결과를 한국해사기술연구소에서 설계제작한 2인승 자기부상열차 모형에 적용하여 열차 모형 주위의 자속 밀도에 대한 등자위선을 구하고, 이때의 최소 차폐 두께를 제시함으로써 차폐 재료의 무게에 대해 50% 이상의 감량이 가능하였다.