• 대한화학회지
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• 제22권4호
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• pp.239-244
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• 1978

Stilbene 유도체인 trans-1,2-bispyrazylethylene에 대한 분광학적 연구를 행하였다. 보통의 자외선 흡수스펙트럼에서는 $n{\rightarrow}{\pi}^*$ 흡수밴드는 에너지가 비슷한 ${\pi}{\rightarrow}{\pi}^*$ 흡수밴드에 가려져서 나타나지 않는데 2차 미분 스펙트럼과 저온(77˚K)에서의 스펙트럼으로 부터 $n{\rightarrow}{\pi}^*$ 흡수 밴드를 확인할 수가 있었다. 또한 ${\pi}{\rightarrow}{\pi}^*$ 흡수밴드들의 전이에너지를 PPP-SCF-CI MO 방법으로 계산한 결과 스펙트럼에서 얻은 값과 잘 일치했다. 형광스펙트럼, 형광편광스펙트럼, 그리고 PPP-SCF-CI MO 방법에 의한 계산으로부터 형광을 내는 상태는 $^1({\pi},\;{\pi}^*)$ 상태임을 알 수가 있었으며 이것은 형광에 대한 alkaline salt effect의 결과와 일치한다.

• 소성∙가공
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• 제31권5호
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• pp.273-280
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• 2022

Although the mechanical properties of high-entropy alloys depend on the annealing conditions, limited works were established to investigate the annealing effect on the mechanical properties of Mo-added high-entropy alloys. Therefore, in the present work, the annealing effects on the microstructural evolution and mechanical properties of Mo-added high-entropy alloy were investigated. As a result, incomplete recrystallization from the limited annealing time not only suppresses deformation-induced phase transformation during cryogenic tensile test but also induces a deformation instability that results into the ductility reduction compare with the fully recrystallized sample. This result represents adjustment of annealing time is useful to control both transformation-induce plasticity and deformation instability of high-entropy alloys, and this can be applied to control the mechanical properties of metallic alloys by combining pre-straining and subsequent annealing.

• 공업화학
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• 제7권4호
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• pp.670-678
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• 1996

방사성 폐기물 소각로의 배기가스 중에 포함되어 있는 NOx를 제거하기 위하여 선택적 촉매 환원법에 활용되는 촉매들의 특성을 조사하였다. 촉매는 $V_2O_5$, $MoO_3$, 그리고 $SnO_2$를 하니컴 형태의 $TiO_2$ 담체에 담지시켜 제조하였으며 촉매의 종류, 반응온도, feed의 조성, $NH_3$/NO 몰비의 영향 등이 반응특성에 미치는 영향을 실험실 규모의 반응기에서 조사하였다. 10% $V_2O_5/TiO_2$ 촉매가 $350^{\circ}C$에서 94.4%의 높은 $NO{\rightarrow}N_2$ 전환율을 보였으며 열적 안정성이 좋은 $MoO_3$의 첨가는 높은 전환율을 보이는 온도범위를 확장시켜 주었다.

• 한국전기전자재료학회논문지
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• 제29권3호
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• pp.186-191
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• 2016

The effects of $Eu^{3+}$ doping on the structural, morphological, and optical properties of $MgMoO_4:Dy^{3+},Eu^{3+}$ phosphors prepared by solid-state reaction technique were investigated. XRD patterns exhibited that all the synthesized phosphors showed a monoclinic system with a dominant (220) diffraction peak, irrespective of the content of $Eu^{3+}$ ions. The surface morphology of $MgMoO_4:Dy^{3+},Eu^{3+}$ phosphors was studied using scanning electron microscopy and the grains showed a tendency to agglomerate as the content of $Eu^{3+}$ ions increased. The excitation spectra of the phosphor powders were composed of a strong charge transfer band centered at 294 nm in the range of 230~340 nm and two intense peaks at 354 and 389 nm, respectively, arising from the $^6H_{15/2}{\rightarrow}^6P_{7/2}$ and $^6H_{15/2}{\rightarrow}^4M_{21/2}$ transitions of $Dy^{3+}$ ions. The emission spectra of the $Mg_{0.85}MoO_4$:10 mol% $Dy^{3+}$ phosphors without incorporating $Eu^{3+}$ ions revealed a strong yellow band centered at 573 nm resulting from the $^4F_{9/2}{\rightarrow}^6H_{13/2}$ transition of $Dy^{3+}$. As the content of $Eu^{3+}$ was increased, the intensity of the yellow emission was gradually decreased, while that of red emission band located at 614 nm began to appear, approached a maximum value at 10 mol%, and then decreased at 15 mol% of $Eu^{3+}$. These results indicated that white light emission could be achieved by controlling the contents of the $Dy^{3+}$ and $Eu^{3+}$ ions incorporated into the $MgMoO_4$ host crystal.

• 지역사회간호학회지
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• 제32권4호
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• pp.430-444
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• 2021

Purpose: This study is an integrated literature review to analyze health problems and social determinants of multicultural adolescents in South Korea. Methods: An integrative review was conducted according to Whittemore & Knafl's guideline. An electronic search that included publications from 2018 to 2020 in the PubMed, EMBASE, Cochrane Library, CINAHL, RISS, and KISS databases was conducted. Of a total of 67 records that were identified, 13 finally met full inclusion criteria. Text network analysis was also conducted to identify keywords network trends using NetMiner program. Results: The health problems of multicultural adolescents were classified into mental health (depression, anxiety, suicide and acculturative stress) and health risk behaviors (smoking, risky drinking, smartphone dependence and sexual behavior). As social determinants affecting the health of multicultural adolescents, the biological factors such as gender, age, and visible minority, and the psychological factors such as acculturative stress, self-esteem, family support, and ego-resiliency were identified. The sociocultural factors were identified as family economic status, residential area, parental education level, and parents' country of birth. As a result of text network analysis, a total of 41 words were identified. Conclusion: Based on these results, mental health and health risk behaviors should be considered as interventions for health promotion of multicultural adolescents. Our findings suggest that further research should be conducted to broaden the scope of health determinants to account for the effects of the physical environment and health care system.

• 접착 및 계면
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• 제24권3호
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• pp.100-104
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• 2023

본 Van der Waals heterostructure 기반의 트랜지스터의 경우 표면에 불포화 결함(dangling bond) 없이 Van der Waals 힘으로만 결합되어 있어 우수한 전자특성을 보이기 때문에 최근 많이 연구되고 있다. 하지만, 트랜지스터에 사용되는 2차원 물질들은 대부분 스카치테이프(mechanical exfoliation) 방법을 기반으로 하는 기초 연구에 머물러 있다. 그렇기 때문에 이를 발전시키기 위해 반데르발스 수직이종접합 전계효과 트랜지스터를 제작하는 데 사용되는 모든 소재를 CVD (chemical vapor deposition)에서 성장된 소재를 사용하였다. 전극으로는 CVD로 성장된 그래핀을 포토리소그래피 공정을 통해 패터닝하여 사용하였으며, CVD로 성장된 MoSe₂를 픽업/전사하는 방식으로, 둘 사이의 반데르발스 이종접합 전계효과 트랜지스터를 제작하였다. 본 연구에서는 이를 통해 제작된 소자의 특성을 보았으며 MoSe₂의 결함 유무에 따라 트랜지스터의 특성에 변화가 있음을 확인하였다.

• Asian-Australasian Journal of Animal Sciences
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• 제21권4호
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• pp.547-554
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• 2008

In performance, digestibility and slaughter trials, a total of forty five male weaned lambs were used to examine the effects of monensin and live yeast supplementations on growth performance, nutrient digestibility, carcass characteristics and ruminal fermentation parameters when the lambs were fed steam-flaked corn-based diets. Animals were allotted to one of three treatment diets in a completely randomized design. The three treatment diets were: (1) basal diet (CON) with steam-flaked corn as a sole grain source, (2) basal diet supplemented with monensin (MO), and (3) basal diet supplemented with live yeast (LY). Total average daily intake (ADI) was unaffected by MO and LY supplementations. LY supplementation increased (p<0.05) average daily gain (ADG) by 13.1% compared with the CON diet. Both MO and LY supplementations resulted in a significant improvement (p<0.05) of feed efficiency over the CON diet (4.47, 4.68 vs. 5.05). Hemicellulose digestibility was higher (p<0.05) for lambs in the LY supplementation group (62.4%) as compared with the CON group (55.7%), but no differences were observed in digestibilities of dry matter (DM), organic matter (OM), crude protein (CP), neutral detergent fiber (NDF) and acid detergent fiber (ADF). All carcass traits were not influenced by dietary supplementations. Ruminal pH in lambs fed the LY supplemental diet was more stable than that with the CON diet (6.57 vs. 6.17). Neither MO nor LY supplementation influenced the concentration of ruminal ammonia-N and total volatile fatty acid (VFA), and molar percentages of individual VFA. Plasma urea-N concentration was decreased (p<0.05) by MO and LY supplementations, while plasma ${\beta}$-hydroxybutyrate (BHBA), glucose and other blood parameters were unaffected. In conclusion, while both MO and LY supplementations had a positive impact on feed efficiency and LY supplementation stabilized ruminal pH and improved fiber utilization, none of the supplements had the capacity to significantly enhance the carcass characteristics.

• 한국재료학회지
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• 제30권8호
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• pp.406-412
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• 2020

SrMoO₄:RE³⁺ (RE=Dy, Sm, Tb, Eu, Dy/Sm) phosphors are prepared by co-precipitation method. The effects of the type and the molar ratio of activator ions on the structural, morphological, and optical properties of the phosphor particles are investigated. X-ray diffraction data reveal that all the phosphors have a tetragonal system with a main (112) diffraction peak. The emission spectra of the SrMoO₄ phosphors doped with several activator ions indicate different multicolor emissions: strong yellow-emitting light at 573 nm for Dy³⁺, red light at 643 nm for Sm³⁺, green light at 545 nm for Tb³⁺, and reddish orange light at 614 nm for Eu³⁺ activator ions. The Dy³⁺ singly-doped SrMoO₄ phosphor shows two dominant emission peaks at 479 and 573 nm corresponding to the ⁴F_9/2→⁶H_15/2 magnetic dipole transition and ⁴F_9/2→⁶H_13/2 electric dipole transition, respectively. For Dy³⁺ and Sm³⁺ doubly-doped SrMoO₄ phosphors, two kinds of emission peaks are observed. The two emission peaks at 479 and 573 nm are attributed to ⁴F_9/2→⁶H_15/2 and ⁴F_9/2→⁶H_13/2 transitions of Dy³⁺ and two emission bands centered at 599 and 643 nm are ascribed to ⁴G_5/2→⁶H_7/2 and ⁴G_5/2→⁶H_9/2 transitions of Sm³⁺. As the concentration of Sm³⁺ increases from 1 to 5 mol%, the intensities of the emission bands of Dy³⁺ gradually decrease; those of Sm³⁺ slowly increase and reach maxima at 5 mol% of Sm³⁺ ions, and then rapidly decrease with increasing molar ratio of Sm³⁺ ions due to the concentration quenching effect. Fluorescent security inks based on as-prepared phosphors are synthesized and designed to demonstrate an anti-counterfeiting application.

• Nuclear Engineering and Technology
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• 제56권6호
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• pp.2282-2291
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• 2024

In this work we study the effects of different factors of dislocation loop on its obstacle strength when interacting with an edge dislocation. At first, the interaction model for dislocation and dislocation loop is established and the full and partial absorption mechanism is obtained. Then, the effect of temperature, size and burgers vector of dislocation loop are investigated. The relation between the obstacle strength and irradiation dose has been established, which bridges the irradiation source and microscale properties. Except that, the obstacle strength of C, Cr, Ni, Mn, Mo and P decorated dislocation loop is studied. Results show that the obstacle strength for dislocation loop decorated by alloy element decreases in the sequence of Cr, Ni, Mn, C, P and Mo, which could be used to help parameterize and validate crystal plasticity finite element model and therein integrated constitutive laws to enable accounting for irradiation-induced chemical segregation effects.

• 대한본초학회지
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• 제23권1호
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• pp.9-15
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• 2008

Objectives : This study was performed to investigate the effect of water extracts from Lagocephalus wheeled with several herbs(LW) on hyperlipemia and liver damage induced by alcohol. Methods : Except for the normal group, we fed rat on 25% alcohol for 55 days. And each extract was administrated for the same period. We measured the serum component in rat's blood, body weight and weight of liver. Results : At first, we observed effects of LW on hyperlipemia induced by alcohol. LW group didn't show significant increase of total cholesterol in comparison with those of the control group. LW group didn't show significant increase of HDL(High-Density lipoprotein) cholesterol in comparison with those of the control group. LW group showed significant decrease of triglyceride in comparison with those of the control group. LW group showed significant increase of body weight in comparison with those of the control group in 4weeks and 8weeks. LW group showed significant increase of liver weight in comparison with those of the control group. At second, we observed effects of LW on liver damage induced by alcohol. LW group showed significant decrease of ALP, GOT, GPT and LDH in comparison with those of the control group. Conclusions : Reviewing these experimental results, it appears that water extracts from Lagocephalus wheeleri with several herbs have pharmaceutical efficacy on hyperlipidemia and liver damage induced by alcohol. Therefore further additional study should be conducted to elucidate in depth the pharmaceutical efficacy of this.