• Title, Summary, Keyword: Po-218

Search Result 17, Processing Time 0.03 seconds

Formation of Ultra fine Particle by the Polonium-218 Ions under Different Humidity Conditions (다른 습도조건하에서 Po-218 이온들의 극소입자형성에 관한 연구)

  • Yoon, Suk-Chul;Ha, Chung-Woo
    • Journal of Radiation Protection and Research
    • /
    • v.17 no.1
    • /
    • pp.1-10
    • /
    • 1992
  • A number of investigators have reported the formation of the radiolytic ultrafine particles produced by the interaction of ionizing radiation with water vapor. Previous studies have suggested that a very high localized concentration of the OH radical produced by the radiolysis of water can react with trace gas like organic vapors and produce lower vapor pressure compounds that can then nucleate. In order to determine water vapor dependence of the active, positively charged, first radon daughter(Po-218), an experiment was conducted using a well-controlled radon chamber. The activity size distribution of the radon daughter in the range of 0.5-100nm was measured using the parallel graded wire screens system. Measurements were taken for different relative humidity. The resultant activity size distributions were analyzed. The addition of water vapor to the radon carrier gases resulted in the formation of ultrafine particles by OH radicals formed by radon radiolysis. It may be due to the neutralization of charged Po-218 ion with water vapor through the radio lysis.

  • PDF

Theoretical Calculation on Alpha Track Density by Using an Electrostatic Ion Spectrometer (정전기분광분석방법에 의한 알파입자비적밀도의 이론적 계산연구)

  • Yoon, Suk-Chul;Ha, Chung-Woo
    • Journal of Radiation Protection and Research
    • /
    • v.18 no.1
    • /
    • pp.25-35
    • /
    • 1993
  • To develop a technique of theoretical alpha track density calculation for comparison with measured track density, an electrostatic ion spectrometer was specially designed and fabricated. The mobility spectrum of first radon daughter(Po-218) in the range of $0.07{\sim}5.0cm^2/V\;s$ from the radon chamber was measured using-the electrostatic ion spectrometer. Measurement was taken in a radon chamber operated using dry particle free air passed through silica gel, activated charcoal and molecular sieve filters. The mobility of a new-born Po-218 ion measured by the electrostatic ion spectrometer was determined to be $1.92cm^2/V\;s$. A comparison of the theoretical and measured alpha track densities was completed and uncertainties concerning the shape of the spectrum were analyzed. It was found that the discrepancies in track densities are primarily Que to the neglect of wall loss of ions in the theoretical track density calculation.

  • PDF

Proton-Conducting Electrolyte $CsH_2PO_4$ for Intermediate-Temperature Fuel Cell

  • Park, Chi-Yeong;Lee, Su-Yeon;Jeon, Min-Hyeon;Lee, Gwang-Se;Kim, Jae-Hyeong;Kim, Jeong-Bae
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
    • /
    • /
    • pp.218-218
    • /
    • 2007
  • 고체 전해질로서 $CsH_2PO_4$결정은 $230^{\circ}C$ 이상에서 전기전도도가 $10^{-2}\;{\Omega}^{-1}cm^{-1}$의 값에 도달하는 초양성자(Superprotonic) 상태로 상전이를 한다. 이러한 이유로 $CsH_2PO_4$ 결정은 $230^{\circ}C$ 부근에서 사용할 수 있는 연료전지로 개발되어왔다. 실용적인 면에서 단결정의 경우보다 다결정의 물성 및 응용 연구가 많았는데, 입자 크기에 따른 체계적인 연구는 잘 이루어지지 않았다. 본 발표에서는 $CsH_2PO_4$ 다결정을 합성하여 SEM 및 micro Raman spectra를 조사하였다. SEM의 결과 입자들의 평균 크기는 100 nm 이었으며, micro Raman spectra는 Bulk $CsH_2PO_4$의 spectra 와 큰 차이를 보이지 않았다. $PO_4$의 내부진동은 거의 같은 주파수대를 보여주나, $300\;cm^{-1}$이하의 저주파 수 영역에서는 광학적 포논의 픽이 잘 보이지 않았다. 그 원인이 micro Raman 장치의 측정 특성인지, 물리적 변화인지는 확실치 않다.

  • PDF

A Kinetics Study of Rn Daughter and Atmospheric Trace Gas Using Alpha Track Detection (알파비적검출방법에 의한 대기중 라돈딸핵종의 화학적 동특성연구)

  • Yoon, Suk-Chul;Ha, Chung-Woo
    • Journal of Radiation Protection and Research
    • /
    • v.20 no.2
    • /
    • pp.79-83
    • /
    • 1995
  • A number of investigators have reported formation of radiolytic ultrafine particles produced by the interaction of ionizing radiation with atmospheric trace gases. Previous studies have suggested that a very high localized concentration of the hydroxyl radical produced by the radiolysis of water can react with atmospheric trace gases such as $SO_2$ and produce lower vapor pressure compounds that can subsequently nucleate. To determine the trace gas and water vapor concentration dependence of the active, positively charged, first decayt product of radon (Po-218), a well-controlled radon chamber was used in this research. The mobility spectrum of the decay products in the range of $0.07-5.0cm^2/V\;sec$ from the radon chamber was measured using alpha track detector installed inside a specially-designed electrostatic spectrometer. Measurements were taken for different concentrations (0.5ppm to 5ppm) of $SO_2$ in Purified, Compressed air. A kinetics Study following the clustering of $SO_2$ around the $PoO_x^+$ ion in an excess of $SO_2$ for interpretation of the reaction processes was performed.

  • PDF

Measurement of Radon and its Daughters Concentration in Air (공기중 라돈 및 라돈 자핵종의 농도 측정)

  • Park, Y.W.;Ha, C.W.;Ro, S.G.
    • Journal of Radiation Protection and Research
    • /
    • v.14 no.2
    • /
    • pp.23-29
    • /
    • 1989
  • A Lucas cell was established and calibrated by using the double layer tube standard radon source. The calibration factors were 0.031$\pm$0.002 (pCi/l)/(cph/Cell) at room temperature, and 0.029$\pm$0.001 (pCi/l)/(cph/Cell) at $50^{\circ}C$. Radon and its daughters concentrations were measured in a room air for the demonstrating purpose. The concentrations of 222 Rn, $^{218}Po,\;224\;Pb,\;and\;^{214}Bi$ were 0.87, 0.53, 0.35 and 0.26 pCi/l. The total eqilibrium factor was around 0.40 and the WL is $3.33{\times}10^{-3}$, resulting in 30 mrem/yr at this place.

  • PDF

A Study on the comparison of shipbuilding technique of Unification Silla.Koryo Dynasty during he 8th and 9th Century

  • Hugh, Ihl;Lee, Chang-Euk
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
    • /
    • /
    • pp.205-218
    • /
    • 2000
  • Hull forms of Jiao Yi Ship for shipping and foreign trade in Silla and Tang Dynasty were transformed and developed in accordance to their voyage and rational routes. The trade ship was a sea ship, used by Chang Po Go's, the Silla great sea merchant ship, in the marine trade with China during the 8th and 9th century. It is not easy to presume the hull type and trade formal of Chang Po Go's Jiao Yi Ship of the 8th and 9th Century. Studying on the ship type of the trade ship is the urgent problem to be solved, in the sphere of leaning about the history of communication between China and Korea. The authors take the initial prove into this subjects, by researching Chang Po Go's marine activities, and point out that the trade ship's original type should be the Sha Ship which was the sea ship sailing th sea in northern China, in the Tang Dynasty. This study aims to present materials concerning hull forms of Chang Po Go's Jian Yi Ship by analysing ancient voyage history, foreign trade history, and ship history of Silla, Tang and Japan during the 8th and 9th century.

  • PDF

A Study on Distribution of Radon Concentration at Atmospheric in Seoul (서울 대기중 라돈농도의 분포에 관한 연구)

  • ;;;T. Iida
    • Proceedings of the Korea Air Pollution Research Association Conference
    • /
    • /
    • pp.279-281
    • /
    • 2000
  • 발암성 물질로 알려진 라돈($^{222}Rn$)은 원래 불활성기체로 자연계에 널리 존재하는 자연방사능으로 암석이나 토양 같은 지각물질에서 발생하는 우라늄($^{238}U$) 붕괴계열인 라듐($^{226}Ra$)의 붕괴과정에서 생성되는 방사성 가스이다. 라돈($^{222}R$)은 $\alpha$붕괴에 의하여 $^{218}Po$, $^{214}Po$등의 자핵종(Radon daughter)을 생성하며, 최종적으로 납($^{210}Pb$)으로 변한다 라돈이 폐에 흡입되면 붕괴하면서 $\alpha$방사선을 방출하는데, 이것이 인체의 세포를 죽이거나 염색체를 손상시킬 수 있으며, 폐암의 발생 위험률을 높이는 것으로 보고되었다. (중략)

  • PDF

A Study on Distribution of Particulate and Radon Concentrations in Indoor Environment in Seoul City (서울시 일부 실내환경 중 미세먼지와 라돈농도 분포에 관한 연구)

  • 김윤신;김현탁;이철민;장기석;안진호
    • Proceedings of the Korea Air Pollution Research Association Conference
    • /
    • /
    • pp.365-366
    • /
    • 2000
  • 라돈은 암석이나 토양 같은 지각물질에서 발생되는 우라늄($^{238}$ U) 붕괴계열인 라듐($^{226}$ Ra)의 붕괴과정에서 생성된다. 라돈($^{222}$ Rn)은 붕괴하면서 $\alpha$방사선을 방출한다. $\alpha$ 붕괴에 의하여 $^{218}$ Po, $^{214}$ Po, $^{214}$ Bi 등의 자핵종(Radon daughter)을 생성하며, 이 과정에서 인체의 세포를 죽이거나 염색체를 손상시킬 수 있으며, 폐암의 발생 위험률을 높이는 것으로 보고되었다$^{1)}$ . 라돈은 건물의 균열, 연결부위, 혹은 배수관이나 오수간, 주변의 틈을 통해서 실내로 유입된다. (중략)

  • PDF

Standardization Activity of ISO TC108/SC2 (Measurement and evaluation of mechanical vibration and shock as applied to machines, vehicles and structures) (ISO TC108/SC2 (기계.차량.구조물의 기계 진동.충격의 측정 및 평가) 규격 제정 동향)

  • Park, Jong-Po;Chung, Kyoon-Yang
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
    • /
    • /
    • pp.218-221
    • /
    • 2000
  • 1999년 5월 4일부터 5월 7일까지 덴마크 오덴스에서 개최되었던 18차 ISO TC108/SC2 (기계 차량 구조물의 기계 진동 충격의 측정 및 평가) 총회내용 및 결의사항과 최근 진행되고 있는 ISO TC108/SC2 산하 규격 제 개정 동향에 대하여 살펴본다.

  • PDF

Study on Reaction Behavior of Rigid Polyurethane Foam with Various Types and Contents of Gelling Catalysts (젤화 촉매의 종류 및 함량에 따른 경질 폴리우레탄 폼의 반응거동에 관한 연구)

  • Eom, Se Yeon;Lee, Hyeong Il;Lee, Kee Yoon
    • Polymer Korea
    • /
    • v.39 no.2
    • /
    • pp.210-218
    • /
    • 2015
  • The reaction behavior of rigid polyurethane foams were studied on the effects of gelling catalysts of amine type, such as; dimethylcyclohexyl amine (DMCHA) and of potassium type, such as; potassium octoate (PO). Rigid polyurethane foams were provided with polymeric 4,4'-diphenylmethane diisocyanate, polyester polyol, silicone surfactant, blowing agent and a few gelling catalysts. As the contents of catalyst, DMCHA increased from 0 to 2.0 g, the reaction time decreased from ca. 330 to ca. 35 sec and due to the exothermic reaction, the maximum temperature increased from ca. 217 to ca. $234^{\circ}C$, respectively. As the contents of PO increased from 0 to 2.5 g, the reaction time decreased from ca. 79 to ca. 38 sec and the maximum temperature increased from ca. 182 to ca. $271^{\circ}C$, respectively. The kinetic parameters were calculated and the conversions were based on the temperature rising method of adiabatic process. As the content of DMCHA increased, the rate constant $k_0$ increased. But in the case of PO catalyst, $k_0$ did hardly depend upon its amount, and showed us similar reaction rate constants.