• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.8 no.2
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• pp.151-158
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• 2010

In order to measure the deposition velocity of $I_2$ vapor for radish plants and its translocation factor for their roots, radish plants were exposed to $I_2$ vapor for 80 min. at different growth stages between 29 and 53 d after sowing. The exposure was performed in a transparent chamber during the morning time. Deposition velocities ($ms^{-1}$) were on the whole in the range of $1.0{\times}10^{-4}{\sim}2.0{\times}10^{-4}$ showing an increasing tendency with an increase in the biomass density. The results showed some agreement with existing reports that a higher relative humidity would lead to a higher deposition velocity. The acquired deposition velocities were lower than by factors of several tens than some field measurements probably due to a very low wind speed (about $0.2\;ms^{-1}$) in the chamber. Translocation factors (ratio of the total iodine in the roots at harvest to the total plant deposition), estimated in a more or less conservative way, were $1.3{\times}10^{-3}$ for an exposure at 29 d after sowing and $5.0{\times}10^{-3}$ for an exposure at 53 d after sowing. In using the present experimental data, meteorological conditions and chemical and physical forms of iodine need to be carefully considered.

• Journal of Radiation Protection and Research
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• v.29 no.3
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• pp.165-172
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• 2004

Rice plants were exposed to $I_2$ vapor for 80 min at different growth stages in an exposure box to investigate the parameters concerning direct plant contamination. Deposition velocity $(m\;s^{-1})$ of the $I_2$ vapor for the straws was in the range of $1.4{\times}10^{-5}-1.3{\times}10^{-4}$ depending on the exposure time, being comparatively low during the earlier part of the plant growth. Ear deposition velocity was in the range of $2.5{\times}10^{-5}-6.7{\times}10^{-5}$. Whole-plant deposition velocity was in the range of $1.4{\times}10^{-5}-1.8{\times}10^{-4}$ with the highest from the exposure performed on Aug. 18 (7 d after the start of heading). The time-dependent variation generally decreased when the deposition velocity was normalized to the biomass density No noteworthy tendency in the deposition velocity was observed with regard to the temperature, sunlight and humidity. Translocation factor for the hulled seeds was $3.3{\times}10^{-5}-4.7{\times}10^{-4}$ with the highest from the Aug. 23 exposure. It was found that a leaf deposition even before the ear emergence resulted in a considerable seed translocation.

• Nuclear industry
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• v.7 no.2 s.48
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• pp.8-32
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• 1987

• Journal of the Korean Institute of Gas
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• v.3 no.1
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• pp.14-20
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• 1999

This study describes the results of Coefficient of Performance(COP) analysis by cycle simulation for two types of absorption-compression hybrid cycle using the Water/Lithium Bromide solution pair. These types are basic hybrid systems introducing a mechanical compression process into the refrigerant vapor phase of the single effect absorption cycle. In absorption-compression hybrid cycles, coefficient of performance is improved compared with absorption cycle. Hybrid cycle Type 2 is considered as a key technology to support energy utilization system, given its capability of utilizing waste heat to drive system with a high level of efficiency.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.11a
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• pp.29.2-29.2
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• 2009

구리는 낮은 비저항, 높은 열전도도, 우수한 electromigration(EM)저항특성 등을 바탕으로 차세대 nano-scale집적회로의 interconnect application에 적합한 금속재료로서 각광받고 있다. copper interconnect는 damascene process 를주로 이용하는데 CVD를 이용하면 step coverage가우수한 seed layer얻을 수 있어 고집적 소자의 구현이 가능하다. 최근에 비 균등화 반응(disproportionationreaction)을 이용하여 고 순도 구리박막을 제조하기위해 $\beta$-diketonate Cu(I) Lewis-base의 전구체를 많이 이용하는데 그중에서 hexafluoroacetylacetonate(hfac)Cu(I)vinyltrimethylsilane (VTMS)가 널리 이용되고 있다. 그러나 (hfac)Cu(I)(VTMS) 또는 유사계열의 전구체들은 열적안정성및 보관안정성이 부족하여 실제 양산공정에 적합하지 못한 단점이 있었다. 본 연구에 이용된 2가 전구체Cu(dmamb)2는 높은 증기압($70^{\circ}C$, 0.9torr)을 가지며 종래에 주로 이용하던 1가 전구체 (hfac)Cu(VTMS)에 비해 높은 활성화 에너지(~113 kJ/mol)를가짐으로서 열적안정성 및 보관안정성이 우수하다. 다른 한편으로 2가전구체는 안정성이 우수한 만큼 낮은 증기압을 극복하기 위해 리간드에 플루오르를 주로 치환하여 증기압을 높이는데 플루오르는 성장하는 박막의 접착력을약하게 하는 단점을 가진다. 하지만 본 연구에 사용된 Cu(dmamb)2는 리간드에 플루오르를 포함하지 않으며, 따라서 고품질의 박막을 용이한성장환경에서 제조할 수 있는 장점들을 제공한다. 비활성가스 분위기에서 2가전구체는 열에너지에 의해 리간드의 자가환원에따라 금속-리간드 분해가 발생한다. 하지만 수소분위기에서는수소가 환원제로 작용하여 리간드의 분해를 용이하게 하는 특징을 가지며 따라서 비활성분위기일 때 비해 낮은 성장온도를 가진다. 또한 수소는 잔류하는 리간드 및 불순물과 결합하여 휘발성화학종들을 생성하여 고순도의 구리박막제조를 가능하게한다.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.11a
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• pp.37.1-37.1
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• 2009

몰리브덴 금속박막(Metal Mo)은 우수한 전기전도도로 인해 $CuInSe_2$로 대표되는 I-III-$VI_2$족 화합물 반도체 박막태양전지에서 후면전극으로 널리 이용되고 있는 재료로서 일반적인 증착방법으로CVD, PVD, Thermal evaporation, Sol-gel 등이 있으며, 이중에서 Sputtering에 의한 증착법이 주로 사용되고 있다. 이에 본 연구에서는 $MoO_3$분말의 수소 환원 과정 중에 발생하는 기상인 $MoO_3(OH)_2$ 기상의 화학증기수송(CVT)를 이용하여 $MoO_x$ 박막을 증착하고 다시 수소분위기에서 수소 환원하는 증착법을 통해 균일하고 부착성이우수한 Mo 박막을 제조 하였다. $550^{\circ}C$, 60min의 유지시간에서 약 900nm의 균일한 $MoO_x$ 박막을 증착하였으며, $650^{\circ}C$, 15min 의 환원조건에서 모두 금속 몰리브덴 박막으로 상변화 함을 XRD와 SEM을 통해 확인하였다. 본 연구에서 사용된 화학증기수송에 의한 박막 증착은 기존의 공정에 비해 매우 저렴하며, 반응중에 유해하지 않은 부산물로 인해 환경 친화적이며 또한 대형화가 가능한 공정으로 많은 응용이 기대된다.

• Nuclear Engineering and Technology
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• v.26 no.2
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• pp.257-264
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• 1994

Experimental studies hate been peformed to investigate vapor explosion phenomena which may threaten the containment integrity during severe accidents in nuclear power plants. In this study, experimental equipment is constructed for vapor explosion experiments, and the vapor explosion experiments were conducted using water/R22. During the experiments, water/R22 interaction phenomena were observed using the high speed camera, and the explosion pressure and released mechanical energy were measured with pressure transducer and pressure relief tube. And the effects of some important parameters-hot liquid temperature, hot liquid injection velocity, hot liquid injection velocity, hot liquid injection time, and cold liquid depth-were investigated on the vapor explosion. Also, the experiment with grid was conducted to study reactor -vessel-lower-structure effect on fuel/coolant interaction. Water/R22 explosion conversion ratios were measured between 0.5∼1.6%.

• Korean Journal of Crystallography
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• v.4 no.2
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• pp.100-104
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• 1993

Reduced glutathione (GSH) plays a vital role in the metabolism of all cells. Glutathions, a tripeptide cowfosed of glutamic acid, cysteane, and gtycina is synthesized by two synthesized reutions. The first is catalyzed by Y-glutamylcysteine synthetase (GSH-I) and the second by glutathione synthetase (GSH-ll). The glutathione biosynthetic pathway of E. coziis mainly controlled by nonallosteric feedback inhibition of GHS-I by GSH. Determination of the three-dimensional structure of GSH-I by X-ray crystallography is necessary in order to understand the structure-function relationship at the molecular level. As the (irst step toward its structure determination, crystallization of 5. coli V-glutamylcystfine synthetase (GSH-I) has been achived using the hanging drop vapor diffusion method and capillaw method. Crystals of GSH-I have been grown from ammonium sulfate solution. The crystals grew at room temperature within 10 days to dimensions of 0.2 m x 0.2 m x 0.2 ml by hanging drop vapor diffusion method and diffracted to about 4 A resolution using synchrotron X-rays. Another crystal, grown by the capillary method to dimensions of 0.25 mm x 0.25 mm x 0.3 mm within 40 days, diffracted to about 4 A resolution using X-rays from a rotating anode.

• Proceedings of the Korean Nuclear Society Conference
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• 1995.10a
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• pp.211-216
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• 1995

1994년 11월에 나타난 고리 1호기 증기발생기의 전열관 누설에 대한 원인을 조사하기 위하여 인출 전열관의 파손 분석과 슬러지 분석 및 pH 분석 등을 수행하였다. 손상원인은 국부적인 염기도 상승과 부식전위 상승에 따른 2차측 응력부식균열(ODSCC)로 밝혀졌다. 전열관 표면과 접한 관판 상부의 퇴적슬러지 끝단에 형성된 틈새에서 나타나는 비등현상으로 $Na^{+}$ 등의 양이온이 농축하게 되며, Cl$^{-}$ 등의 음이온 증발로 인하여 국부적으로 염기도의 상승현상이 야기되었다. 또한 재 가동시 전열관 표면에 침착된 잔류 구리와 용존산소의 결합으로 부식전위가 상승되었다. 이와 같은 ODSCC 발생환경은 1990년이래 지속적으로 형성된 것으로 판단된다.

• Applied Biological Chemistry
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• v.40 no.1
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• pp.71-75
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• 1997

Important physicochemical properties of captafol [N-(1,1,2,2-tetrachloro-ethylthio)cyclohex-4-ene-1,2-dicarboximide], water solubility, vapor pressure, hydrolysis and octanol/water partition coefficient(Kow) were measured based on the standard EPA and OECD methods. Water solubility of the chemical was 2.24 ppm at $25^{\circ}C$. Half-life by hydrolysis at $25^{\circ}C$ in the buffer solution of pH 3.0, pH 7.0, and pH 8.0 was 77.8 hr, 6.54 hr and 0.72 hr, respectively, demonstrating instability in alkaline solution. The half-life in acid condition was not significantly different by temperature change, however, that in neutral or alkaline solution became shorter at $40^{\circ}C$. Hydrolysis study with a reference compound, diazinon, proved that the experimental method of the present study is reliable. Vapor pressure of captafol, $8.27{\times}10^{-9}$ torr at $20^{\circ}C$, was calculated from the equation, log P=6.94-(4401.6/T) plotted on the experiment results under different temperature conditions, 40, 50, and $60^{\circ}C$. pressure of captafol, the contamination of captafol would not happen easily in environment by vaporization. High Kow value of 1,523 was observed and this might result in bioconcentration through food chain when captafol was exposed. However, affecting human health through aquatic bioaccumulation is not likely to occur due to its rapid hydrolysis in the environment.