• Journal of the Korean Vacuum Society
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• v.21 no.5
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• pp.242-248
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• 2012

Valence band of a vacuum-reduced $TiO_2$ (001) surface has been carefully examined using synchrotron x-ray photoelectron spectroscopy to investigate variation of the gap state upon oxidation and thermal diffusion of $Ti^{3+}$ interstitials from the bulk. We compare our results with that obtained from $TiO_2$ (110) and aim to address a crystal-face dependency in the oxidation and diffusion rates of $Ti^{3+}$ interstitials. We find very similar behaviors in the oxidation and thermal diffusion rate of $Ti^{3+}$ interstitials between the two crystal faces suggesting a negligible crystal-face dependency in this case.

• The Journal of Korean Society for School & Community Health Education
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• v.13 no.2
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• pp.77-91
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• 2012

배경 및 목적: 성병 감염, 조기 성경험, 다수의 성관계 파트너 등과 같은 위험 성행동은 여성의 건강 전반을 위협하는 결과를 초래할 수 있다. 하지만, 이러한 심각성에 비하여, 미국의 청소년기 및 청년기 여성의 위험 성행동을 소수인종 집단별 특성을 고려한 연구는 부족한 실정이다. 그러므로 본 연구는 미국 소수인종 여성 청소년의 위험 성행동에 대한 실태를 조사하고자 한다. 방법: 본 연구는 2차 자료 분석의 결과물로써, 원자료인 미국의 National Longitudinal Study of Adolescent Health (Add Health)의 1기 (1995년)와 3기 (2001년)의 자료 중 여성 청소년의 자료를 바탕으로 분석되었다. 다양한 위험 성행동을 인종별로 분석함과 더불어 본 연구의 특징은 종단적 성병 감염 행태를 인종별로 분석한 점이다. 결과: 본 연구는 소수인종 여성의 위험 성행동에 관한 핵심적인 결과를 제시한다. 성병 감염, 조기 성경험, 다수의 성관계 파트너 등과 같은 위험 성행동의 분포는 흑인과 아시아계 여성이 타인종의 여성에 비하여 높은 위험해 쳐해 있는 것으로 나타났다. 본 연구의 흑인 여성들은 전반적인 성행동을 망라하여 고위험군으로 분류되고 있다. 아시아계 여성 역시 고위험 군으로 분류되는데, 특히, 청소년기에 성병에 한번 감염된 경험이 있는 아시아계 여성은 가장 위험한 성병 감염 행태를 보이고 있는 것으로 나타났다. 결론: 본 연구의 결과는 소수인종 여성의 위험 성행동이 백인보다 전반적으로 높은 편으로 나타나지만, 적절한 보건의료 서비스에서는 소외되는 현실을 지적하고 있다. 이러한 인종별 성건강의 불균형 문제해소를 위하여 청소년들에게 인종적 특성과 서비스 접근성의 고려가 절실히 필요하다고 사료된다.

• Korean Journal of Materials Research
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• v.11 no.8
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• pp.664-664
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• 2001

The mechanical alloying (MA) effect in $\sigma$-VFe intermetallic compound was studied by neutron and X-ray diffraction. The structure of MA $\sigma$-VFe powders were characterized by the X- ray diffraction with Cu- $K\alpha$ radiation and neutron diffraction with monochromatic neutrons of $1.835\AA$ using a high resolution powder diffractometer (HRPD). Mechanical alloying of $\sigma$-VFe compound gives rise to a dramatic structural change. After 60 hours of MA, the Fe-Fe distribution of the $\sigma$- phase VFe tetragonal structure with 30 atoms in a unit cell is found to change into that of the $\sigma$-(V,Fe) solid solution with bcc structure, which is a stable phase at elevated temperature above $1200^{\circ}C$. A comparison of X-ray diffraction data for the $\alpha$-phase has been also made with the corresponding neutron diffraction data. The (101) and (111) diffraction peaks of the $\sigma$-phase was clearly observed only in neutron diffraction pattern, which is believed to be a characteristic feature due to the chemical atomic ordering of $\sigma$- VFe phase.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.7
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• pp.731-736
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• 2012

A new method for producing boron-containing nanoparticles is described. Boron trichloride ($BCl_3$) and methane ($CH_4$) are dissociated through injection into a thermal plasma followed by a nucleation process producing boron or boron carbide nanoparticles. X-ray photoelectron spectroscopy was used to detect B-C bonds related to the carbide state and to probe the ratio of boron to carbon in the B-C bond structure. In addition, nanoparticles were characterized with scanning transmission electron microscopy and electron energy loss spectroscopy. It was found that nanoparticles were in the range 30-70 nm and a boron to carbon ratio in the B-C bond structure of up to 2 can be reached when $BCl_3$ of 20 sccm and $CH_4$ of 25 sccm were used.

• Korea journal of population studies
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• v.26 no.1
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• pp.143-170
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• 2003

During the last few decades dramatic expansion of education occurred for women as well as men in Korea. Taking into account such a rapid expansion of education, this study examines trends in the effects of education on first occupational attainment among Korean women. Using the data from "the 4th Survey on Women's Employment," conducted by Korean Women's Development Institute in 2001, this study investigates the trends across three cohorts classified on the basis of the year of labor force entry after schooling: before 1980, 19801989, and 1990 or later. First, log-linear models are applied to the data to detect the temporal change in the overall association between education and first occupational attainment controlling for marginal distribution. The log-linear analysis shows that the strength of association between education and first occupation has declined over time. An additional analysis of OLS regression is conducted to see how the effects of each level of educational attainment on occupational prestige have changed across the three cohorts. The results of OLS regression suggest that the differences in prestige scores between the lowest and each of other educational levels are narrower in recent cohorts.t cohorts.

• The Journal of the Petrological Society of Korea
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• v.10 no.3
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• pp.233-245
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• 2001

With the advent of super-conducting magnet, NMR spectroscopy becomes a very important tool in geology as well as in chemistry. $^{29}Si$ and $^{27}Al$ which are the main components of minerals and contain structural informations, are useful major targets for the NMR study in geology, but some other elements including alkali cations such as $^{23}Na$ are also one of them. NMR can be applied to many different fields. For example, it can be applied to study smaller range of structure (in molecular level) than XRD and TEM. NMR provides us with structural informations such as order-disorder in Al and Si distribution, oxygen coordination number, and distribution of other cations. Another important information that we can obtain from NMR is not only the static structural informations, but also the molecular dynamics. This dynamic informations of molecules also enable us to figure out the frequency of molecular motion and activation energy. Structure of amorphous minerals and chemistry and structure of natural organic materials are also studied by NMR.

• Applied Chemistry for Engineering
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• v.31 no.4
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• pp.347-351
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• 2020

A material changes its physical and chemical properties through the interaction with radiation and also the neutrons, which is electronically neutral so that the penetration depth is relatively deeper than that of other radioactive way including alpha or beta ray. Therefore, the radiation damage by neutron irradiation has been intensively investigated for a long time with respect to the safety of nuclear power plants. The damage induced by neutron irradiation begins with the creation of point defects in atomic scale in the unit of picoseconds, and their progress pattern can be characterized by microstructural defects, such as dislocation loops and voids. Their morphological characteristics affect the properties of neutron-irradiated materials, therefore, it is very important to predict the microstructure at a given neutron irradiation condition. This paper briefly reviews the evolution of radiation damage induced by neutron irradiation and introduces a phase-field model that can be widely used in predicting the microstructure evolution of irradiated materials.

• Journal of the Korean Chemical Society
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• v.54 no.4
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• pp.363-373
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• 2010

Computational studies were carried out on the opiates morphine, heroin, codeine, pentazocine, and buprenorphine, under the density functional theory. The geometric parameters of the pharmacophore and substituents were evaluated at the B3LYP/6-31+G(d) level of theory. The electronic structure calculations were performed using the same hybrid functional at the B3LYP/6-311++G (d,p) level of theory. The atomic charges were obtained by Mulliken population analysis. Given the reported biological activity, calculated partition coefficients, and electronic and geometric analysis, pentazocine and buprenorphine were chosen as models for proposed analogues. These analogues were then studied and compared with the model molecules. The study reveals that the geometry and electronic structure of the pharmacophore remains consistent in the presence of different substituents. Because the proposed analogues preserve the studied properties of the model molecules, it is likely that these analogues display biological activity.

• Korean Journal of Crystallography
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• v.1 no.1
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• pp.49-56
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• 1990

The crystallizied Inactions of the two metastable phases in the glasses of plagioclase compositions were estimated by x-ray diffraction method. The orthorhombic metastable phase is easily drystaliized in the composition range of 70 to 80 mol% of albite, whereas the hexagonal metastable phase is mostly crystallized in the anonhite-rich side. For the purpose of refining the orthorhombic metastable structure some single crystal fragments of the composition Na,17ca‥‥All Isi2 nn were separated Som the crystallized glasses. The cell parameters of this crystal are a=8.237(1)A. b=8.644(1)A c=4.818(1)A. The space group of this crystal is Pn,2, Final atomic coordinates give R value of 0.040 and Rw of 0.028 with anisotropic thermal parameters. The position of Na and Ca atoms statistically distributed is splitted in two points with the occupancy of 0.5. The Si and Al atoms are statistically distributed in the six-membered ring of the Immm-type framework.

• Nuclear Engineering and Technology
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• v.16 no.4
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• pp.202-216
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• 1984

The success of coarse-mesh nodal solution methods provides strong motivation for finding homogenized parameters which, when used in global nodal calculation, will reproduce exactly all average nodal reaction rates for large nodes. Two approximate theories for finding these ideal parameters, namely, simplified equivalence theory and approximate node equivalence theory, are described herein and then applied to the PWR benchmark problem. Nodal code, ANM, is used for the global calculation as well as for the homogenization calculation. From the comparative analysis, it is recommended that homogenization be carried out only for the unique type of fuel assemblies and for core boundary color-sets. The use of approximate homogenized cross-sections and approximate discontinuity factors predicts nodal powers with maximum error of 0.8% and criticality within 0.1% error relative to the fine-mesh KIDD calculations.