• 제목/요약/키워드: cumulative deposition

검색결과 24건 처리시간 0.032초

Inventory of Pu-238 and Pu-239,240 in the Soil of Korea

  • Lee, Myung-Ho;Lee, Chang-Woo;Park, Yong-Ho;Kim, Sang-Bok;Kim, Sam-Rang
    • 한국원자력학회:학술대회논문집
    • /
    • 한국원자력학회 1995년도 추계학술발표회논문집(2)
    • /
    • pp.893-898
    • /
    • 1995
  • The cumulative deposition of Pu-238 and Pu-239,240 by the end of 1994 in undisturbed for the last 40 years, was determined at 9 sites in Korea. The cumulative deposition of Pu-238 and Pu-239 ranged from 0.76 to 3.77 and from 18.42 to 101.84 $Bqm^{-2}$, respectively. The mean values of the cumulative deposition of Pu-238 and Pu-239,240 were 2.16 and 54.75 $Bqm^{-2}$, respectively. These values are close to the value of worldwide fallout. No significant contribution to the cumulative deposition of Pu-238 and Pu-239,240 originating from the Chernobyl accident was found at my site.

  • PDF

A study of characteristics of cumulative deposition of fallout Pu in environmental samples

  • Lee, Myung Ho;Song, Byoung Chul;Jee, Kwang Yong;Park, Yeong Jae;Kim, Won Ho
    • 분석과학
    • /
    • 제19권1호
    • /
    • pp.18-30
    • /
    • 2006
  • This paper describes the cumulative deposition of fallout Pu in soil and lichen at the present time and give the characteristics of fallout Pu deposits in the soil. In the soil of the forest, the accumulated depositions of $^{239,240}Pu$ were estimated to be in the range of 34.0 to $101.2Bq\;m^{-2}$ with an average value of $65.3{\pm}21.6Bq\;m^{-2}$. The average inventory of $^{239,240}Pu$ in the forest was calculated to be two times higher than that in the hill. Also, the deposited activities of $^{239,240}Pu$ in cultivated soil were significantly lower than those in the hill or forest. However, the cumulative depositions of fallout Pu in the volcanic ash soil on Cheju Island were much higher than those in the forest and hill soils. The measured activity concentrations of Pu isotopes in lichens and mosses showed large variations, due to characteristics of species and life span of lichen and moss colonies. From depth profiles, it was found that most of the fallout Pu has been accumulated in upper 10 cm layer of soil. Except for a few cases, the concentrations of $^{239,240}Pu$ in soil tended to decrease exponentially with increasing soil depth. Among parameters affecting the cumulative deposition of fallout Pu, organic substances and rainfall play an important role in the retention and relative mobility of fallout Pu in the soil. However, pH showed a weak correlation with the deposition of fallout Pu in the soil. From sequential leaching experiments, Pu was found to be associated predominantly with the "organic" and "oxy-hydroxy" fractions. Both the activity ratios of $^{238}Pu/^{239,240}Pu$ and $^{241}Pu/^{239,240}Pu$ in soils, lichens and mosses and the atomic ratios of $^{240}Pu/^{239}Pu$ in soils are close to those observed in the cumulative deposit global fallout from nuclear weapon testings. The results obtained from this research make it possible to interpret and predict the behavior of fallout Pu under natural conditions.

Fabrication of Composite Drug Delivery System Using Nano Composite Deposition System and in vivo Characterization

  • Chu, Won-Shik;Jeong, Suk-Yong;Pandey, Jitendra Kumar;Ahn, Sung-Hoon;Lee, Jae-Hoon;Chi, Sang-Cheol
    • International Journal of Precision Engineering and Manufacturing
    • /
    • 제9권2호
    • /
    • pp.81-83
    • /
    • 2008
  • The Rapid Prototyping (RP) technology has advanced in many application areas. In this research, two different types, cylinder and scaffold, of implantable Drug Delivery System (DDS) were fabricated using Nano Composite Deposition System (NCDS), one of the RP systems. The anti-cancer drug (5-fluorouracil, 5-FU), biodegradable polymer (PLGA(85: 15)), and bio ceramic (Hydroxyapatite, HA) were used to form drug-polymer composite material. Both types of DDS were evaluated in vivo environment for two weeks. For evaluation, the cumulative drug release and shape stability were measured. Test results showed that the scaffold DDS provide higher cumulative drug release and has better stability than cylinder DDS.

Analysis and Estimation of Reservoir Sedimentation Using Remote Sensing and GIS

  • Sungmin Cho
    • International Journal of Internet, Broadcasting and Communication
    • /
    • 제15권4호
    • /
    • pp.199-204
    • /
    • 2023
  • Periodic assessment of reservoir capacity is essential for better water resources management and planning for the future water use. Reservoirs and water storage structures raised on the rivers are subjected to sedimentation and he sedimentation is caused by deposition of eroded sediment particles carried by the streams. Knowledge of reservoir sedimentation is important to estimate avaliable storage capacity for optimum reservoir operation and scheduling water release. In recent years, remote sensing and GIS techniques have emerged as an important tool in carrying out reservoir capacity analysis and water management. The reduction in storage capacity as compared to the original capacity at the time of reservoir impounding is indicative of sediment deposition. In this study, the application of GIS and remote sensing techniques were applied to assess the sediment deposition, losses in the reservoir storage and the revised cumulative capacity. Satellite images covering Pyodongdong reservoir were analyzed using Erdas Imagine and ArcGIS softwares.Cumulative capacities at different levels were also calculated and we estimated that the revised live storage was 84.2Mft3 in 2021 and 64.3Mft3 in 2022 while the original capacity was 22.8 and 53.6Mft3 in 2021 and 2022.

한국토양에 존재하는 $^{137}Cs$ 방사능 분포 (Cumulative Deposition of $^{137}Cs$ in the Soil of Korea)

  • 이명호;최용호;신현상;김상복;이창우
    • Journal of Radiation Protection and Research
    • /
    • 제23권2호
    • /
    • pp.97-102
    • /
    • 1998
  • 한국 토양에 존재하는 $^{137}Cs$ 방사능 분포에 관한 연구를 수행하였다. $^{137}Cs$ 방사능 농도를 결정하기 위하여 남한지역 17개 지점에 대하여 20cm 깊이로 토양을 채취한 후 감마스펙트로메타를 이용하여 $^{137}Cs$ 방사능 농도를 결정하였다. 야산지역과 숲속에 대한 $^{137}Cs$의 평균 농도는 각각 $1,058{\pm}322$ Bq $m^{-2}$$2,501{\pm}499$ Bq $m^{-2}$로, 숲속의 $^{137}Cs$의 농도가 야산지역보다 약 두배정도 높은 수치를 보였다. 인위적 교란이 없는 지역에서 토양깊이 변화에 따른 $^{137}Cs$ 분포는 토양깊이가 증가할수록 지수함수적으로 감소경향성을 나타내었다. $^{137}Cs$ 농도 분포에 영향을 미치는 여러인자를 조사한 결과 유기물 함량이 $^{137}Cs$의 토양 침적에 중요한 작용을 함을 알 수 있었고 강수량, 점토의 함량 및 pH과 같은 인자들은 $^{137}Cs$의 토양 침적과 상관관계가 거의 없슴을 발견 할 수 있었다.

  • PDF

Hafnium Oxide Nano-Film Deposited on Poly-Si by Atomic Layer Deposition

  • Wei, Hung-Wen;Ting, Hung-Che;Chang, Chung-Shu
    • 한국정보디스플레이학회:학술대회논문집
    • /
    • 한국정보디스플레이학회 2005년도 International Meeting on Information Displayvol.I
    • /
    • pp.496-498
    • /
    • 2005
  • We reported that high dielectric hafnium oxide nano-film deposited by thermal atomic layer deposition on the poly-silicon film (poly-Si). The poly -Si film was produced by plasma enhanced chemical vapor deposition and excimer laser annealing. We used the hafniu m chloride ($HfCl_4$) and water as the precursors and analyzed the hafnium oxide film by transmission electron microscope and secondary ion mass spectrometer. Hafnium oxide produced by the ALD method showed very good coverage on the rough surface of poly-Si film. While deposited with 200 cycles, these hafnium oxide films revealed a relatively smooth surface and good uniformity, but the cumulative roughness produced by the incomplete reaction was apparent when the amount of deposition cycle increased to 600 cycles.

  • PDF

대기를 통하여 한반도 지표면으로 공급되는 방사성 핵종( $^137Cs$$^210Pb$)에 관한 연구 (A Study on the Atmospheric Deposition of Radionuclides($^137Cs$ and $^210Pb$) on the Korean Peninsula)

  • 이윤구;김석현;홍기훈;이광우
    • 한국대기환경학회지
    • /
    • 제11권4호
    • /
    • pp.351-359
    • /
    • 1995
  • In order to investigate geochemical behaviors of artificial radionuclide($^{137}$ Cs), the fallout deposition of arificial radioisotope($^{137}$ Cs) was measured from May to October in 1994 at the Korea Ocean Research & Development Institute(KORDI), Ansan, Kyunggido, Korea. And to study radioisotopic behavior and cumulative action in soil, soil samples were collected from Kwang-Leung Forest, Kyunggidom and artificial radioisotope ($^{137}$ Cs) and natural radioisotope($^{210}$ Pb) were identified. The amount of $^{137}$ Cs in atmosphere collected by wet deposition process in May was found to be 4.95 to 11.96mBq m$^{-2}$ whereas the amounts of $^{137}$ Cs by dry deposition process in May and October were found to be 4.0mBq g$^{-1}$ and 3.0mBq g$^{-1}$ , respectively. The amount of $^{137}$ Cs accumulated in soil was measured to be 311mBq cm$^{-2}$ , which contained 83% of the total inputs from atmospheric fallout (374 mBq cm$^{-2}$ ) since 1960s. In addition, the accumulation rate and the annual flux of $^{210}$ Pb into soils were 0.32cm yr$^{-1}$ and 34 mBq cm$^{-2}$ yr$^{-1}$ , respectively. Conclusively, it was found that arificial radioisotopes were mainly from the stratosphere and soil resupension of continental China through the troposphere.

  • PDF

관악산에서 공중화분의 비산시기와 비산량의 변화 (Variation of Deposition Time and Amount of Airborne pollens in Mt. Kwan-ak)

  • Chang, Nam-Kee;Nam-Il Kim;Jae-Geun Kim
    • The Korean Journal of Ecology
    • /
    • 제11권3호
    • /
    • pp.123-130
    • /
    • 1988
  • The airborne pollens were studied by Durhan's pollen trap in Mt. Kwan-ak from March 1, 1984 to October 15, 1986. Most airborne pollens were found from late-March to late-September and few of them from early-November to late-February. Peak times of airborne pollens were found for one year as follows; First, from late-March to early-April, Second, middle-May, third, from late-August to middle-September. Peak day of airborne pollens of each species was related with cumulative temperature. The total amount of airborne pollen during one year had fluctuation in each year. Year by year, the amount of airborne pollens from tree was increaed, but airborne pollens of grasses was decreased. Among tree airborne pollens, the deposition rate of pinus pollen was steady, bur Quercus was relatively increased.

  • PDF

Modified melt-textured growth 법으로 제작한 타겟을 사용한 YBCO 박막의 펄스레이저 증착 (Pulsed laser deposition of YBCO thin films using modified melt-textured grown targets)

  • 김창훈;김인태;홍국선;김영환;최상삼;한택상
    • 한국초전도학회:학술대회논문집
    • /
    • 한국초전도학회 1999년도 High Temperature Superconductivity Vol.IX
    • /
    • pp.115-119
    • /
    • 1999
  • Ba$_2Cu_3O_{7-{\delta}}$ (YBCO) thin films were deposited by pulsed laser deposition using differently prepared targets: One was a conventionally solid-state sintered (SSS) target and the other was a modified melt-textured grown (MTC) target. Compared with SSS targets, MTG targets showed a well-connected microstructure consisting of much larger grains and the surface was Bess roughened with the cumulative laser incidence. YBCO films deposited from MTC targets showed a denser and smoother surface of the basal film than the case of SSS targets. The investigations of ${\alpha}$-axis outgrowths in the films indicated that the deposition using MTG targets would result in a more homogeneous and stable film growth as compared to the SSS targets. Also, TEM analysis revealed that the film deposited from MTG targets had a less granular microstructure that would reduce weak-link effects in the film.

  • PDF

Evaluation of along-channel sediment flux gradients in an anthropocene estuary with an estuarine dam

  • Figueroa, Steven M.;Lee, Guan-hong;Chang, Jongwi;Schieder, Nathalie W.;Kim, Kyeongman;Kim, Seok-Yun;Son, Minwoo
    • 한국수자원학회:학술대회논문집
    • /
    • 한국수자원학회 2022년도 학술발표회
    • /
    • pp.86-86
    • /
    • 2022
  • While estuarine dams can develop freshwater resources and block the salt intrusion, they can result in increased sediment deposition in the estuary. The mechanism of increased sediment deposition in an estuary with an estuary dam is not well understood. To fill this knowledge gap, 7 ADCP measurements of flow and suspended sediment concentration (SSC) were collected along-channel in an estuary with an estuarine dam over a neap-spring cycle. Flow and SSC were used to calculate the sediment flux and sediment flux gradients. The results indicated that the cumulative sediment fluxes at all stations were directed landward. The along-channel sediment flux gradient was negative, which indicated deposition along the channel. The landward mean-flow fluxes were dominant in the deep portion of the channel near the estuary mouth, whereas landward correlation fluxes were dominant in the shallow portion of the channel near the estuarine dam. The tides were the dominant forcing driving the sediment fluxes throughout the estuary.

  • PDF