• 한국진공학회지
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• 제5권1호
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• pp.39-47
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• 1996

The segregation of S in electrotransport-purified polycrystaline $\alpha$-Ti and Ti-aluminide alloys has been studied by Auger electron spectroscopy(AES), Ion scattering spectroscopy(ISS) and Secondary ion mass spectrometry(SIMS) in the temperature range extending from 20 to $1000^{\circ}C$. The chemisorbed oxygen and carbon on Ti were observed to disappear at T>$400^{\circ}C$ after which the S signal increased to levels approaching 0.5 monolayer. At lower temperatures the presence of the surface oxygen and carbon appeared to inhibit the segregation, presumably because there were no available surfaces sites for the S emerging from the bulk. The activation energy for the S segregation in pure polycrystaline Ti was determined to be 16.7 kcal/mol, which, when compared to S segretation from single-crystal Ti, is quite small and suggests grain boundary or defect diffusion segregation kinetics. In the Ti-aluminide alloys, the presence of Al appeared to enhance the retention of surface oxygen which, in turn, substantially reduced the S segretation. The $\gamma$ alloy, with its high Al content, exhibited the greatest retention of surface oxygen and the smallest quantity of the S segregation(T$\simeq1000^{\circ}C$).

• Bulletin of the Korean Chemical Society
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• 제14권6호
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• pp.722-726
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• 1993

Organotin(IV) complexes of ylidenemalonates $(R_xSn)_{x-1}(O_2C)_2C=C(SR')_2\;(R=n-C_4H_9,\;C_6H_5,\;cyclo-C_6H_{11},\;CH_3OOCCH_2CH_2;\;x=2,3;\;R'=CH_3,\;R_2'=-CHCH-,\;-CH_2CH_{2^-})$ have been synthesized and characterized by means of various spectroscopic methods. The X-ray crystal structure of $(Ph_3Sn)_2(O_2C)_2C=C(SCH_3)_2$ has been determined (Pi; a= 9.704(2) ${\AA}$, b= 14.412(1) ${\AA}$, c= 14.760(3) ${\AA}$, ${alpha}$=74.26(1)$^{\circ}$, ${beta}$=99.38(l)$^{\circ}$, ${\gamma}$=79.09(1)$^{\circ}$, $V= 1950.7(7){\AA}^3$) and refined to R= 0.045. The crystal structure discloses a discrete molecule with bidentate-like carboxylate ligand. For diorganotin analogues, the structures are discussed in terms of IR, $^1H-NMR,\;^{13}C-NMR$, and FAB mass spectrometry. The mass spectrum indicates that the diorganotin complexes of ylidenemalonates are dimeric.

• Nuclear Engineering and Technology
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• 제49권3호
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• pp.562-568
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• 2017

Background: The chemical characterization of metallic alloys and oxides is conventionally carried out by wet chemical analytical methods and/or instrumental methods. Instrumental neutron activation analysis (INAA) is capable of analyzing samples nondestructively. As a part of a chemical quality control exercise, Zircaloys 2 and 4, nimonic alloy, and zirconium oxide samples were analyzed by two INAA methods. The samples of alloys and oxides were also analyzed by inductively coupled plasma optical emission spectroscopy (ICP-OES) and direct current Arc OES methods, respectively, for quality assurance purposes. The samples are important in various fields including nuclear technology. Methods: Samples were neutron irradiated using nuclear reactors, and the radioactive assay was carried out using high-resolution gamma-ray spectrometry. Major to trace mass fractions were determined using both relative and internal monostandard (IM) NAA methods as well as OES methods. Results: In the case of alloys, compositional analyses as well as concentrations of some trace elements were determined, whereas in the case of zirconium oxides, six trace elements were determined. For method validation, British Chemical Standard (BCS)-certified reference material 310/1 (a nimonic alloy) was analyzed using both relative INAA and IM-NAA methods. Conclusion: The results showed that IM-NAA and relative INAA methods can be used for nondestructive chemical quality control of alloys and oxide samples.

• Nuclear Engineering and Technology
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• 제51권2호
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• pp.384-393
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• 2019

An experimental validation of a nuclear forensics methodology for the source reactor-type discrimination of separated weapons-useable plutonium is presented. The methodology uses measured values of intra-element isotope ratios of plutonium and fission product contaminants. MCNP radiation transport codes were used for various reactor core modeling and fuel burnup simulations. A reactor-dependent library of intra-element isotope ratio values as a function of burnup and time since irradiation was created from the simulation results. The experimental validation of the methodology was achieved by performing two low-burnup experimental irradiations, resulting in distinct fuel samples containing sub-milligram quantities of weapons-useable plutonium. The irradiated samples were subjected to gamma and mass spectrometry to measure several intra-element isotope ratios. For each reactor in the library, a maximum likelihood calculation was utilized to compare the measured and simulated intra-element isotope ratio values, producing a likelihood value which is proportional to the probability of observing the measured ratio values, given a particular reactor in the library. The measured intra-element isotope ratio values of both irradiated samples and its comparison with the simulation predictions using maximum likelihood analyses are presented. The analyses validate the nuclear forensics methodology developed.

• Nuclear Engineering and Technology
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• 제55권7호
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• pp.2650-2655
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• 2023

In the process of growth and development, plants not only absorb essential nutritional elements, but also absorb radioactive and non-essential elements from the environment, and their distribution varies in different parts of the plant. In this study, neutron activation analysis and gamma spectrometry were performed on stems, roots, and leaves of vegetables. The results indicate that the accumulation of radionuclides and multi-elements depends on the plant type and plant parts. Activity concentrations of ²²⁶Ra and ²³²Th in plants were accumulated in the following order: Roots > Stems > Leaves. The highest concentrations of ⁴⁰K and ²¹⁰Pb were observed in the stems and leaves of plants, respectively. Essential nutrient requirements of plants are in the following order: K > Ca > Mg > Fe > Zn > Mn. Among the nonessential metals, the concentration of Na in the vegetable sample was much greater than those of the other elements. The K/Na ratio in the plant depends on the type of plant and the translocation within the plant.

• 방사성폐기물학회지
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• 제21권4호
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• pp.481-487
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• 2023

Concerning the apprehensions about naturally occurring radioactive materials (NORM) residues, the International Atomic Energy Agency (IAEA) and its member nations have acknowledged the imperative to ensure the radiation safety of NORM industries. Residues with elevated radioactivity concentrations are predominantly produced during NORM processing, in the form of scale and sludge, referred to as technically enhanced NORM (TENORM). Substantial quantities of TENORM residues have been released externally due to the dismantling of NORM processing factories. These residues become concentrated and fixed in scale inside scrap pipes. To assess the radioactivity of scales in pipes of various shapes, a Monte Carlo simulation was employed to determine dose rates corresponding to the action level in TENORM regulations for different pipe diameters and thicknesses. Onsite gamma spectrometry was conducted on a scrap iron pipe from the titanium dioxide manufacturing factory. The measured dose rate on the pipe enabled the estimation of NORM concentration in the pipe scale onsite. The derived action level in dose rate can be applied in the NORM regulation procedure for on-site judgments.

• 한국식품영양과학회지
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• 제34권4호
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• pp.513-518
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• 2005

본 연구에서는 감마선 조사에 의한 부추의 휘발성 유기화합물의 변화를 관찰하였다. 조사되지 않은 부추와 20 kGy의 선량으로 조사된 부추를 SDE방법으로 유기화합물을 추출한 후 정유를 GC/MS로 분석하였다. 비조사 시료와 조사시료에서 각각 56종 ,54종의 화합물이 분리 동정되었으며, alcohol류, aldehyde류, ester류, ketone류, 함질소화합물과 함황화합물을 포함하고 있는 것이 확인되었다. 조사된 부추에 함유된 특징적인 휘발성 유기성분은 조사되지 않은 부추에서의 결과와 유사하였으나, 그 농도에 있어서는 눈에 띄는 차이를 보였다. 두 시료 모두에서 함황화합물이 다량 검출되어 주요 화합물임을 알 수 있었다. 성분들 중에서 다량의 dimethyl trisulfide와 methyl-(Z)-1-propenyl trisulfide가 함황화합물의 상대적 농도에 크게 기여하고 그 외 dimethyl disulfide, 3-ethyl-1,2-dithi-1,2-ene, methyl allyl disulfide와 (E)-2-hexanal도 휘발성 유기성분의 조성에 큰 비중을 차지하였다. 그 중 주된 화합물로 확인된 dimethyl trisulfide와 methyl-(Z)-propenyl trisulfide는 조사된 후 크게 감소된 것이 확인되었으며, 이외에도 (E)-2-hexanal과 3-ethyl-1,2-dithi-5-ene, diallyl trisulfide 역시 눈에 띄게 감소하였다. 이에 반하여 dimethyl disulfide는 조사 후 그 함량이 크게 증가하여 앞의 화합물들과는 다른 경향을 보였으며, 이외에도 diallyl sulfide와 allyl methyl sulfide, pyridine 등도 크게 증가하였다.

• 한국식품과학회지
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• 제36권2호
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• pp.196-201
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• 2004

식품재료 및 약리 효과로 인한 약용재료로서 사용범위가 확대되고 있는 홍화꽃 및 홍화씨의 휘발성 성분을 분석 동정하였다. 그 결과, 홍화꽃의 주요 휘발성 성분으로는 테르펜류인 p-cymene, limonene, ${\alpha}-phellandrene$, ${\gamma}-terpinene$, camphor, 4-terpineol, selinene, ${\beta}-caryophyllene$, torreyol, ${\beta}-eudesmol$ 등이 검출되었다. 또한, phenylacetaldehyde, 2-phenylethylalcohol, 4-terpineol, ${\beta}-caryophyllene$, ${\gamma}-terpinene$, ${\alpha}-phellandrene$ 등 통상의 꽃향기 성분과 알데히드류인 3-methylbutanal, 2-methylbutanal, pentanal, hexanal, octanal, nonanal 및 decanal, 알코올류인 2-pentanol 및 heptanol, 케톤류의 3-penten-2-one, 2-heptanone, 2,6,6-trimethyl cyclohexanone 등이 함유되어 있었다. 그 이외 산류인 acetic acid, heptanoic acid, 2-methylbutanoic acid 및 rancid-cheese odor를 띄는 3-methylbutanoic acid(isovaleric acid) 등의 생성이 확인되었다. 특히, 홍화꽃에서의 이들 산류의 생성은 다른 꽃류에 비해 종류나 함량이 많았으며, 홍화꽃이 다른 꽃에 비해 좋지 않은 냄새를 내는 특징적인 요인으로 생각되었다. 한편, 홍화씨의 경우는 hexanal, (E)-2-heptenal, (E,Z)-2,4-decadienal 및 (E,E)-2,4-decadienal등의 알데히드류가 주요 휘발성 성분으로 동정되었다. 일반성분 중 전체 함량의 약 30%의 지질을 함유하는 홍화씨는, 방향성과 관계된 torreyol, ${\beta}-eudesmol$ 등의 terpene alcohol류, 달콤한 향과 관계가 있는 3-methylbutanal 및 2-methylbutanal과 함께 산류의 생성도 있었으나, 지방산 산화 분해생성물인 (E,Z)-2,4-decadienal 및 (E,E)-2,4-decadienal이 전체 휘발성 함량의 약 75%를 차지하였다.

• Restorative Dentistry and Endodontics
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• 제19권1호
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• pp.1-26
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• 1994

The purpose of this study was to investigate the dissolution components during corrosion of amalgams and to identify surface corrosion products in the modified Fusayama artificial saliva. Four type of amalgam alloys were used: low copper lathe cut amalgam alloy (Cavex 68), low copper spherical amalgam alloy (Caulk Spherical Alloy), high copper admixed amalgam alloy (Dispersalloy) and high copper single composition amalgam alloy (Tytin). Each amalgam alloy and Hg were triturated according to the manufacturer's direction by means of mechanical amalgamator (Capmaster, S.S.White), and then the triturated mass was inserted into the cylindrical metal mold which was 10mm in diameter and 2.0mm in height and condensed with compression of 150kg/$cm^2$ using oil pressor. The specimens were removed from the mold and stored at room temperature for 7 days and cleansed with distiled water for 30 minutes in an ultrasonic cleaner. The specimens were immersed in the modified Fusayama artificial saliva for the periods of 1 month, 3 months and 6 months. The amounts of Hg, Cu, Sn and Zn dissolved from each amalgam specimen immersed in the artificial saliva for the periods of 1 month, 3 months and 6 months were measured using Inductivity Coupled Plasma Atomic Emission Spectrometry (ICPQ-1000, Shimadzu, Japan) and amount of Ag dissolved from amalgam specimen was measured using Atomic Absorption Spectrophotometry (Atomic Absorption/Flame emission spectrophotometer M-670, Shimadzu, Japan). A surface corrosion products of specimens were analysed using Electron Spectroscopy Chemical Analyser (ESCA PHI-558, PERKIN ELMER, U.S.A.). The secondary image and back scattered image of corroded surface of specimens was observed under the SEM, and the corroded surface of specimens was analysed with the EDX. The following results were obtained. 1. The dissolution amount of Cu was the most in high copper admixed amalgam(Dispersalloy) and the least in high copper single composition amalgam(Tytin). 2. Sn and Zn were dissolved during all the experiment periods, and dissolution amounts were decreased as the time elapsed. 3. Initial surface corrosion products were ZnO and SnO. 4. Corrosion of ${\gamma}$ and ${\gamma}_2$ phase in low copper amalgams was observed and Ag-Cu eutectic alloy phase was corroded in low copper spherical amalgam(Caulk Sperical Alloy). 5. Corrosion of ${\gamma}$ and $\eta$' phase in high copper amalgams was observed and Ag-Cu eutectic alloy phase was corroded in high copper admixed amalgam(Dispersalloy). 6. Sn-Cl was produced in the subsurface of low copper amalgams and high copper admixed amalgam.

• 방사성폐기물학회지
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• 제17권3호
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• pp.321-328
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• 2019

본 연구에서는 원자력 사고 또는 방사선 비상 시 지표면에 침적될 수 있는 감마선방출 핵종의 방사능을 신속하게 평가하기 위해 이용될 수 있는 NaI(Tl), $LaBr_3$(Ce) 및 $CeBr_3$ 섬광검출기의 성능을 비교 평가하였다. 검출성능은 최소검출가능방사능(MDA, Minimum Detectable Activity)을 통해 평가하였으며, 각 검출기의 지표면 침적 감마선방출 핵종에 대한 검출효율은 수학적 모델링과 점선원을 이용하여 반실험적으로 산출하였다. MDA 평가를 위한 백그라운드 감마선에너지스펙트럼은 비교적 넓고 평탄한 초지에서 측정되었으며, 원자력 사고 시 방출될 수 있는 주요 핵종에 대한 각 검출기의 MDA를 산출하였다. 그 결과 일반 환경방사능 준위에서 지표면 침적 감마핵종에 대한 각 검출기의 MDA 크기는 대체로"NaI(Tl)> $LaBr_3$(Ce)> $CeBr_3$"로 평가되었으며, 백그라운드 준위가 유사한 에너지 영역에서는 분해능이 가장 우수한 $LaBr_3$(Ce)에서 최소 값을 보였다. 이는 관심 핵종의 감마선에너지 영역에 대한 각 검출기의 자체 및 측정 환경 백그라운드, 측정 효율, 그리고 에너지 분해능 특성을 바탕으로 비교 분석되었다.