• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
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• pp.211-211
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• 2012

Using spin-polarized density-functional theory calculations, we find that the existence of either Peierls instability or antiferromagnetic spin ordering is sensitive to hydrogen passivation near the step. As hydrogens are covered on the terrace, the dangling bond electrons are localized at the step, leading to step-induced states. We investigate the competition between charge and spin orderings in dangling-bond (DB) wires of increasing lengths fabricated on an H-terminated vicinal Si(001) surface. We find antiferromagnetic (AF) ordering to be energetically much more favorable than charge ordering. The energy preference of AF ordering shrinks in an oscillatory way as the wire length increases. This oscillatory behavior can be interpreted in terms of quantum size effects as the DB electrons fill discrete quantum levels.

• 한국세라믹학회지
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• 제43권1호
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• pp.1-3
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• 2006

Well-shaped NaA zeolite cubic crystals of a large size of $5-7{\mu}m$ were synthesized by a hydrothermal method in a mother solution having a $3.55Na_2O:Al_2O_3:1.6SiO_2:593\~2000H_2O$ composition. Thermal treatment of NaA zeolite crystals resulted in the formation of a crystalline phase of $NaAlSiO_4-Camegeite$ between 800 and $900^{\circ}C$. Even at $1000^{\circ}C,\;NaAlSiO_4$ phase was found as a major product. Environmental Scanning Electron Microscopy (ESEM), High Resolution Transmission Electron Microscopy (HRTEM), X-Ray powder Diffraction (XRD), Fourier Transform Infrared (FT-IR) spectroscopy, and DTA/TGA and BET analyses were used to characterize the initial materials and the obtained products after various heat treatments.

• 한국전기전자재료학회논문지
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• 제14권5호
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• pp.410-416
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• 2001

KLN thin films were fabricated on Pt coated Si(100) wafer using an rf-magnetron sputtering method. The grown KLN thin film consists of 4-fold grains. In this experiment, the structure of 4-fold grained thin film was investigated using XRD and SEM measurements. Pt layer was also deposited using the rf-magnetron sputtering method,. XRD measurement showed that he Pt thin film has Gaussian distribution form with strong (111) direction orientation. The KLN thin film has preferred-orientation of (001) direction, and the peak consists of 2 separate peaks; one with broad FWHM and the other with narrow FWHM. The sharp peak is due to single crystal, and combining with Em results, the 4-fold grain consists of singel crystals with c-axis normal to substrate.

• Transactions on Electrical and Electronic Materials
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• 제3권3호
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• pp.1-7
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• 2002

The developed patterns by direct writing of electron beam are measured by AFM, FESEM and optical profiler of WYKO NT3300. From different measurement methods, the measured linewidths of the patterns are shown a little bit wider than designed pattern size due to electrons scattering effect during direct writing of electron beam. The optimized conditions of these experiments are suggested and explained for the forming of structures below 0.1 ㎛ dimension size. Because of electron scattering effects from the different under layers such as Si, Si$_3$N$_4$ and aluminum, the developed pattern size is also influenced by the accelerated energy of electrons, dose, resist and soft and hard bake conditions in PMMA. The distributions of electron beam and calculations of backscattering coefficient are demonstrated by Monte Carlo simulation. From the measured results, the developed linewidth of PMMA/Al /silicon is shown a little bit wider than that of PMMA/Si$_3$N$_4$/silicon structure due to the backscattering effects.

• 가정∙방문간호학회지
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• 제27권1호
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• pp.42-52
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• 2020

Purpose: This study aimed to find grounds for the development of a health promotion program by examining the risk factors affecting children in low-income families. Methods: This was a cross-sectional study. The subjects were 288 children under 13 years of age in We-Start, W city. The tools used included a household information questionnaire and risk assessment tools. The data were analyzed using t-test, ANOVA, and multiple regressions. Results: Risk factors like disability problems (β=.38, p<.001), residential environment (β=.37, p<.001), parenting type (β=.27, p=.003), the foster's educational level (β=.22, p=.011), and the gender of the child (β=.19, p=.030) explained 51% (p<.001) of the preschoolers in crisis. For the schooler, academic achievement (β=.39, p<.001), disability problems (β=.24, p<.001), adaptation to school (β=.23, p<.001), noise from the environment (β=.20, p<.001), and the foster's job (β=-.15, p=.007) explained 50% (p<.001) of crisis of schooler. Conclusion: The study found that children (disability, gender), family (residential environment, type of parenting), and caregivers (educational level, economic competence) had a complex impact on crisis situations. In children of a school-going age, school life appeared to be an important influencing factor. Therefore, an integrated case management approach that considers children, carers, and the home environment is necessary.

• 한국재료학회지
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• 제13권1호
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• pp.1-5
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• 2003

Uniform polycrystalline $CoSi_2$layers have been grown in situ on a polycrystalline Si substrate at temperature near $625^{\circ}C$ by reactive chemical vapor deposition of cyclopentadienyl dicarbonyl cobalt, Co(η$^{5}$ -C$_{5}$ H$_{5}$ )(CO)$_2$. The growth behavior and thermal stability of $CoSi_2$layer grown on polycrystalline Si substrates were investigated. The plate-like CoSi$_2$was initially formed with either (111), (220) or (311) interface on polycrystalline Si substrate. As deposition time was increasing, a uniform epitaxial $CoSi_2$layer was grown from the discrete $CoSi_2$plate, where the orientation of the$ CoSi_2$layer is same as the orientation of polycrystalline Si grain. The interface between $CoSi_2$layer and polycrystalline Si substrate was always (111) coherent. The growth of the uniform $CoSi_2$layer had a parabolic relationship with the deposition time. Therefore we confirmed that the growth of $CoSi_2$layer was controlled by diffusion of cobalt. The thermal stability of $CoSi_2$layer on small grain-sized polycrystalline Si substrate has been investigated using sheet resistance measurement at temperature from $600^{\circ}C$ to $900^{\circ}C$. The $CoSi_2$layer was degraded at $900^{\circ}C$. Inserting a TiN interlayer between polycrystalline Si and $_CoSi2$layers improved the thermal stability of $CoSi_2$layer up to $900^{\circ}C$ due to the suppression of the Co diffusion.

• The Korean Journal of Ceramics
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• 제3권3호
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• pp.159-162
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• 1997

Diamond was uniformly nucleated on large area Si(001) substrate (3cm$\times$4cm) using the low pressure magnetoactive microwave plasma chemical vapor deposition. $CH_4/He$ gas mixture was used as source gas in order to obtain high radical density in the nucleation enhancement step. $CH_3$radical density was measured by means of infrared laser absorption spectroscopy. The effect of substrate bias voltage on diamond nucleation was examined. The results showed that a suitable positive bias voltage appled to the substrate with respect to the chamber could enhance diamond nucleation while a negative bias voltages leaded to deposition of only non-diamond phase carbon.

• Bulletin of the Korean Chemical Society
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• 제31권12호
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• pp.3579-3582
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• 2010

We studied the reaction of tri-methylaluminum (TMA) on hydroxyl (OH)-terminated Si (001) surfaces for the initial growth of aluminum oxide thin-films using density functional theory. TMA was adsorbed on the oxygen atom of OH due to the oxygen atom’s lone pair electrons. The adsorbed TMA reacted with the hydrogen atom of OH to produce a di-methylaluminum group (DMA) and methane with an energy barrier of 0.50 eV. Low energy barriers in the range of 0 - 0.11 eV were required for DMA migration to the inter-dimer, intra-dimer, and inter-row sites on the surface. A unimethylaluminum group (UMA) was generated at each site with low energy barriers in the range of 0.21 - 0.25 eV. Among the three sites, the inter-dimer site was the most probable for UMA formation.

• 한국재료학회지
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• 제21권1호
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• pp.1-7
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• 2011

Methods of producing hydrogen include steam reforming, electrochemical decomposition of water, and the SI process. Among these methods, the Sulfur iodine process is one of the most promising processes for hydrogen production. The thermochemical sulfur-iodine (SI) process uses heat from a high-temperature-gas nuclear reactor to produce $H_2$ gas; this process is known for its production of clean energy as it does not emit $CO_2$ from water. But the SI-process takes place in an extremely corrosive environment for the materials. To endure SI environments, the materials for the SI environment will have to have strong corrosion resistance. This work studies the corrosion resistances of the Fe-Si, Ni-Ti and Ni Alloys, which are tested in SI-process environments. Among the SI-process environments, the conditions of boiling sulfuric acid and decomposed sulfuric acid are selected in this study. Before testing in boiling sulfuric acid environments, the specimens of Fe-4.5Si, Fe-6Si, Ni-4.5Si, Ni-Ti-Si-Nb and Ni-Ti-Si-Nb-B are previously given heat treatment at $1000^{\circ}C$ for 48 hrs. The reason for this heat treatment is that those specimens have a passive film on the surface. The specimens are immersed for 3~14 days in 98wt% boiling sulfuric acid. Corrosion rates are measured by using the weight change after immersion. The corrosion rates of the Fe-6Si and Ni-Ti-Si-Nb-B are found to decrease as the time passes. The corrosion rates of Fe-6si and Ni-Ti-Si-Nb-B are measured at 0.056 mm/yr and 0.16 mm/yr, respectively. Hastelloy-X, Alloy 617, Alloy 800H and Haynes 230 are tested in the decomposed sulfuric acid for one day. Alloy 800H was found to show the best corrosion resistance among the materials. The corrosion rate of Alloy 800H is measured at -0.35 mm/yr. In these results, the corrosion resistance of materials depends on the stability of the oxide film formed on the surface. After testing in boiling sulfuric acid and in decomposed sulfuric acid environments, the surfaces and compositions of specimens are analyzed by SEM and EDX.

• 한국산학기술학회논문지
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• 제17권11호
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• pp.236-247
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• 2016

본 연구는 Y시 보건소의 고혈압 건강교실 프로그램이 대상자의 고혈압 관련 지식, 자가간호행위, 삶의 질 및 생리적 지수에 미치는 효과를 검증하기 위한 비동등성 대조군 전 후 시차 설계를 이용한 유사실험 연구이다. 프로그램에 참여한 대상자는 고혈압 환자 총 48명으로 이 중 실험군은 23명, 대조군은 25명이었으며, 연구기간은 2015년 8월 31일부터 10월 23일까지 8주간, 주 2회 고혈압 건강교실 프로그램을 운영하였다. 자료 분석은 SPSS/WIN 21.0 프로그램을 이용하여 t-test, ${\chi}^2$-test, Fisher's exact test 그리고 t-test로 분석하였다. 고혈압 건강교실 프로그램 적용 후 고혈압 관련 지식(t=-3.76, p<.001), 자가간호행위(t=-3.33, p<.002), 생리적 지수 중 수축기 혈압(t=6.27, p<.001)과 이완기 혈압(t=4.70, p<.001), 총 콜레스테롤(t=3.08, p=.003) 및 복부둘레(t=2.52, p=.015)는 차이가 있는 것으로 나타났으며, 두 군 간에 통계적으로 유의한 차이가 있었다. 따라서 지역사회 재가 고혈압환자를 위한 건강교실 프로그램이 고혈압환자의 질병관련 지식 및 자가간호행위를 향상시킬 수 있는 유용한 간호중재 프로그램임을 확인 할 수 있었다.