• 제목/요약/키워드: $^{137}C_{s}$

검색결과 351건 처리시간 0.03초

Measurement of 137Cs in Ice Core Samples from Antarctica

  • Lim, S.I.;Kim, D.H.;Huh, J.Y.;Lee, J.;Hahn, I.S.;Han, Y.C.;Hur, S.D.;Hwang, H.J.;Kang, W.G.;Kim, Y.D.;Lee, E.K.;Lee, M.H.
    • Journal of the Korean Physical Society
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    • 제73권9호
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    • pp.1263-1268
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    • 2018
  • Three different ice core samples from Antarctica were analyzed to identify activity concentrations of radioactive isotopes. Tracking migration of radioactive isotopes to Antarctica can provide a key clue to understand global environmental changes caused by radiation exposures because the Antarctic ice cores can preserve unique characteristics of various environmental conditions. We are particularly interested in the $^{137}Cs$ nucleus, because it is closely related to radiation exposure from nuclear power plant accidents and nuclear bomb tests. With its half life of $30.17{\pm}0.03$ years, $^{137}Cs$ can also be used to assess the age of sedimentation occurring after around the year 1945. We selected three ice core samples, called Tarn8, Styx27, and H25, from different time periods; the Tarn8 sample is known to be from earlier than ~ 1000 AD, the Styx27 sample is approximately from the year 1945, and the H25 sample is from the year 2012. Radioactive isotope measurements of the ice core samples were performed using a 100% HPGe detector at Cheongpyeong Underground Radiation Laboratory (CURL). We measured the activity of $^{137}Cs$ in the H25 sample to be $0.98{\pm}0.82mBq/kg$. Although the activity has a large uncertainty mainly due to the limited sample quantity, the $^{137}Cs$ isotopes in the Antarctic ice core were measured for the first time in Korea.

P.C. Anchoring 공법을 활용한 사면안정대책 (The Slope Stability Establishment with P.C. Anchoring Method)

  • 박철숙;손재호;인영길;장두희
    • 대한지질공학회:학술대회논문집
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    • 대한지질공학회 2002년도 정기총회 및 학술발표회
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    • pp.61-73
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    • 2002
  • 울산광역시 울주군 두동면 천전리 306번지 일대에 건설되는 대곡댐은 높이 52m, 길이 190m의 표면차수벽형 석괴댐이다. 대곡댐 건설사업과 관련하여 여수로 좌안사면 굴착공사를 시행 중 2000. 7. 23 13:00~7. 24. 04:00 67.0mm의 강우가 있은 후 Sta. No. 1~2, EL. 137~134m 지점에 균열이 발생하였다. 안정대책을 수립하고자 지표지질조사 및 평사투영법에 의한 안정성을 검토하고 굴착 후 예상되는 불안정 요소를 고려하여 사면의 부분적인 추가절취 및 Pre-stress가 가능한 SSL PC Anchoring에 의한 억지공법을 수립, 시공하였다.

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PPM 부적합품률의 샘풀링 검사 계획의 고찰 (Review of Acceptance Sampling Plans for Parts Per Million Fraction of Defectives)

  • 최성운
    • 대한안전경영과학회지
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    • 제9권4호
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    • pp.137-142
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    • 2007
  • This paper is to introduce attribute acceptance sampling plan based on statistical inference of binomial proportions such as PPM or PPB. In addition, this paper presents three variable sampling acceptance sampling plans based on $C_{pm},\;C_{pmk}$, and Taguchi's loss function. Producers are able to consider as not only external vendors but also internal customers.

$^{137}$ Cs으로 조사된 베타-유크립타이트의 열자극발광 특성 (The Characteristics of Thermoluminescence from $^{137}$ Cs Irradiated Beta-Eucryptite)

  • 김태규;이병용;박영우;추성실;황정남
    • 한국의학물리학회지:의학물리
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    • 제3권2호
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    • pp.23-31
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    • 1992
  • 베타-유크립타이트를 제조하고, $^{137}$Cs의 포톤으로 조사된 베타-유크립타이드의 열자극발광 스펙트럼을 측정하였다. 200cGy-20000Gy의 조사선량에 따른 300K-600K 온도구간의 전체 열자극발광 세기는 50Gy 선량까지 선형성이 유지되지만, 그 이상의 영역에서는 supralinearity가 나타난다. 2000Gy 조사선량에서 supralinearity된 량이 최대로 나타나며, 약 17100Gy 영역에서 소멸된다. 포톤 조사에 의해 순수하게 형성된 trapping centers에 의한 supralinearity된 량이 부가된 전체 열자극발광 세기는 supralinearity가 나타나는 50Gy 영역을 제외한 supralinearity의 모든 영역에서 실험결과와 잘 일치한다.

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비정질 Pb-Sb-Au합금의 결정화 과정에 관한 연구 (A Study on the Crystallization of Amorphous Pb-Sb-Au Alloys)

  • 김종오
    • E2M - 전기 전자와 첨단 소재
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    • 제2권2호
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    • pp.137-142
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    • 1989
  • Piston and anvil법으로 제작한 (P $b_{0.75S}$ $b_{0.25}$)$_{45}$A $u_{55}$ 비정질의 결정화 과정을 시차열분석(DTA), X-선 회절, 전기저항의 온도 및 시간변화를 측정하여 결정화과정을 조사하였다. 두단계의 상변태를 거쳐 결정화가 되는데 첫번째 변태온도는 52.deg.C이며 A $u_{2}$Pb의 결정상이 나타난다. 두번째 변태온도는 253.deg.C이며 AuS $b_{2}$의 결정상이 나타난다. 일차변태는 핵생성 및 성장 반응에 의하여 이루어졌으며 이때의 활성화 에너지는 1.38Kcal/mol이다.다.

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Numerical analysis of a new SMA-based seismic damper system and material characterization of two commercial NiTi-alloys

  • Olsen, J.S.;Van der Eijk, C.;Zhang, Z.L.
    • Smart Structures and Systems
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    • 제4권2호
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    • pp.137-152
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    • 2008
  • The work presented in this paper includes material characterisation and an investigation of suitability in seismic dampers for two commercially available NiTi-alloys, along with a numerical analysis of a new damper system employing composite NiTi-wires. Numerical simulations of the new damper system are conducted, using Brinson's one-dimensional constitutive model for shape memory alloys, with emphasis on the system's energy dissipation capabilities. The two alloys tested showed some unwanted residual strain at temperatures higher than $A_f$, possibly due to stress concentrations near inclusions in the material. These findings show that the alloys are not ideal, but may be employed in a seismic damper if precautions are made. The numerical investigations indicate that using composite NiTi-wires in a seismic damper enhances the energy dissipation capabilities for a wider working temperature range.

Breeding of Productive Bivoltine Hybrid, CSR16${\times}$CSR17 of Silkworm Bombyx mori L.

  • Reddy, N.Mal;Basavaraja, H.K.;Kumar, N.Suresh;Joge, P.G.;Kalpana, G.V.;Dandin, S.B.;Datta, R.K.
    • International Journal of Industrial Entomology and Biomaterials
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    • 제8권2호
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    • pp.129-133
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    • 2004
  • The breeding work was initiated by utilizing two Japanese hybrids namely C135${\times}$N134 and N137${\times}$C146 along with two evolved Indian breeds, J14 and A24. The breed CSR16 which is characterized with marked larvae and white dumbbell cocoons was evolved from the Japanese hybrid C135${\times}$N134 by crossing with J14, while the breed CSR17 which is characterized with plain larvae and white oval cocoons was evolved from the Japanese hybrid N137${\times}$C146 by crossing with A24. The hybrid of these evolved breeds i.e., CSR16${\times}$CSR17 has shown superior over control hybrid $KA{\times}{NB_4}{D_2}$ and on par with the ruling hybrid of CSR2${\times}$CSR4. The hybrid CSR16${\times}$CSR17 was authorized during 1999 by Central Silk Board, Bangalore, Government of India for commercial exploitation during favourable months based on national level race authorization test.

슬러리 분무열분해에 의한 초미립 티탄산 바륨 분말 제조 (Preparation of Ultrafine Barium Titanate Powder by Slurry Spray Pyrolysis)

  • 이종호;허강헌;이정수
    • 한국세라믹학회지
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    • 제46권2호
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    • pp.137-145
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    • 2009
  • A remarkable improvement of the productivity in barium titanate by slurry spray pyrolysis process was realized by supplying solid source slurry into the rector. The produced barium titanate powders showed uniform powder properties, and reproducibility with higher tetragonality in the range of 80$\sim$200 nm, case by case. The secondary calcination experiments of the as-prepared powders by spray pyrolysis revealed that the powders as-prepared over 700$^{\circ}C$ showed perfectly different behavior with the lower temperature's ones and the solid state reaction’s case. The result was discussed in terms of the reaction mechanism based on the activation energy analysis.