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Eu<sup>2+</sup>/Dy<sup>3+</sup> 이온이 도핑된 Sr<sub>2</sub>MgSi<sub>2</sub>O<sub>7</sub> 분말 합성 및 발광 특성
박재한,김영진,Park, Jaehan,Kim, Young Jin 한국재료학회 2014 한국재료학회지 Vol.24 No.12
$Eu^{2+}/Dy^{3+}$-doped $Sr_2MgSi_2O_7$ powders were synthesized using a solid-state reaction method with flux ($NH_4Cl$). The broad photoluminescence (PL) excitation spectra of $Sr_2MgSi_2O_7:Eu^{2+}$ were assigned to the $4f^7-4f^65d$ transition of the $Eu^{2+}$ ions, showing strong intensities in the range of 375 to 425 nm. A single emission band was observed at 470 nm, which was the result of two overlapping subbands at 468 and 507 nm owing to Eu(I) and Eu(II) sites. The strongest emission intensity of $Sr_2MgSi_2O_7:Eu^{2+}$ was obtained at the Eu concentration of 3 mol%. This concentration quenching mechanism was attributable to dipole-dipole interaction. The $Ba^{2+}$ substitution for $Sr^{2+}$ caused a blue-shift of the emission band; this behavior was discussed by considering the differences in ionic size and covalence between $Ba^{2+}$ and $Sr^{2+}$. The effects of the Eu/Dy ratios on the phosphorescence of $Sr_2MgSi_2O_7:Eu^{2+}/Dy^{3+}$ were investigated by measuring the decay time; the longest afterglow was obtained for $0.01Eu^{2+}/0.03Dy^{3+}$.
UV/H<sub>2</sub>O<sub>2</sub>를 이용한 2,4-DCP의 산화에 NO<sub>3</sub><sup>-</sup> 이온이 미치는 영향
박재한,이지영,안윤희,문태훈,임성균,고광백,Park, Jae Han,Lee, Ji Yong,Ahn, Yoon Hee,Moon, Tae Hoon,Yim, Sung Kyun,Ko, Kwang Baik 한국물환경학회 2007 한국물환경학회지 Vol.23 No.3
The Advanced Oxidation Process (AOP) is being increasingly used to oxidize complex organic constituents in treated effluents from domestic wastewater treatment plants. Generally, ${NO_3}^--N$ concentrations ranges between 5 and 8 mg/L for biologically well-treated effluents. However, nitrate ions, ${NO_3}^-$, affects on oxidation as not only a well-known strong absorber of UV light below 250 nm of wavelength but also as an OH radical scavenger. The objective of this study was to evaluate the AOP systems for degradation of 2,4-DCP, and to delineate the effect of nitrate ions on UV oxidation of 2,4-DCP by conducting a bench-scale operation at various reaction times and initial concentrations of $H_2O_2$. The experimental results indicated that 2,4-DCP could be completely oxidized by $UV/H_2O_2$ process with an initial $H_2O_2$ concentration of 20 mg/L at a retention time of 1.0 min or longer. Nitrate ions did not show any adverse effect on 2,4-DCP oxidation at this high $H_2O_2$ concentration, and the practical initial $H_2O_2$ concentration and reaction time for the 80% oxidation turned out to be 5 mg/L and 1.0 min, respectively.
Ti-6Al-4V 합금의 알칼리 및 열처리가 인산칼슘 침착에 미치는 영향
박재한,임기정,김상목,김병옥,한경윤,Park, Jae-Han,Lim, Ki-Jung,Kim, Sang-Mok,Kim, Byung-Ock,Han, Kyung-Yoon 대한치주과학회 2000 Journal of Periodontal & Implant Science Vol.30 No.1
The precipitation of calcium phosphate on implant surface has been known to accelerate osseointegration and to enhance osseous adaptation. The present study was performed to examine whether the precipitation of calcium phosphate on Ti-6Al-4V alloy could be affected by the immersion in NaOH solution and heat treatment. Ti-6Al-4V alloy plates of $15{\times}3.5{\times}1mm$ in dimension were polished sequentially from #240 to #2,000 emery paper and one surface of each specimen was additionally polished with $0.1{\mu}m$ alumina paste. Polished specimens were soaked in various concentrations of NaOH solution(0.1, 1.0, 3.0, 5.0, 7.0, 10.0 M) at $60^{\circ}C$ for 24 hours for alkali treatment, and 5.0 M NaOH treated specimens were heated for 1 hour at each temperature of 400, 500, 600, 700, $800^{\circ}C$. After the alkali and heat treatments, specimens were soaked in the Hank's solution with pH 7.4 at $36.5^{\circ}C$ for 30days.The surface ingredient change of Ti-6Al-4V alloy was evaluated by thin-film X-ray diffractometer(TF-XRD) and the surface microstructure was observed by scanning electron microscope(SEM), and the elements of surface were analyzed by X-ray photoelectron spectroscopy(XPS). The results were obtained as follows ; 1. The precipitation of calcium phosphate on Ti-6Al-4V alloy was accelerated by the immersion in NaOH solution and heat treatment. 2. In Alkali treatment for the precipitation of calcium phosphate on Ti-6Al-4V alloy, the optimal concentration of NaOH solution was 5.0 M. 3. In heat treatment after alkali treatment in 5.0 M NaOH solution, the crystal formation on alloy surface was enhanced by increasing temperature. In heat treated alloys at $600^{\circ}C$, latticed structure and prominences of calcium phosphate layer were most dense. On heat treated alloy surface at the higher temperature(${\geq}700^{\circ}C$), main crystal form was titanium oxide rather than apatite. The above results suggested that the precipitation of calcium phosphate on the surface of Ti-6Al-4V alloy could be induced by alkali treatment in 5.0 M-NaOH solution and by heat treatment at $600^{\circ}C$.
국내외 친환경 건축물 인증제도의 변천과정 고찰을 통한 G-SEED의 평가 체계 개선방안 연구 - 공동주택을 중심으로 -
박재한,차기욱,홍원화,Park, Jae-Han,Cha, Gi-Wook,Hong, Won-Hwa 한국주거학회 2013 한국주거학회 논문집 Vol.24 No.5
The seriousness of greenhouse gas exhaustions and energy use of the building has increased, the world is making an effort with many requests and the consultation for sustainable development. For this reason, Green Building Certification Criteria has been implemented to reduce environmental load, high-performance and environmentally friendly in the United States, the United Kingdom and Germany. In response to the global trend like this, the Korean Government has induced the eco-friendly construction and sustainable development to implement the G-SEED (Green Building Certification Criteria of Korea) in 2002. However, in spite of the many authentication result, G-SEED has been pointed out that it needs for improve in the evaluation system of Apartment sector which accounts for more than 40% of the authentication. Therefore, the purpose of this study is to suggest improvements in the evaluation system. To achieve this, this study have selected for LEED, BREEAM, DGNB of comparison target, drawn improvements through comparing transition process in G-SEED.
치주낭 탐침깊이와 치은연하치태내 Trypsin-like activity와의 관계
박재한,한경윤,Park, Jea-Han,Han, Kyung-Yoon 대한치주과학회 1993 Journal of Periodontal & Implant Science Vol.23 No.3
In order to determine the relationship between probing pocket depth and trypsin-like activity in subgingival plaque, probing pocket depth and loss of attachment were measured by Michigan-O probe on mandibular incisors of 30 patients with adult periodontitis. And the trypsin-like activity of Treponema denticola, Porphyromonas gingivalis, and Bacteroides forsythus was evaluated by the hydrolysis of N-Benzoyl-DL-Arginine-2-Naphthyla-mide (BANA) using PerioScan reagent cards(Oral-B Laboratories, Redwood City, CA). The obtained data were statistically analyzed by Microstat program. The results were as follows. 1. The number of teeth showing negative trypsin-like activity was more in shallow periodontal pocket groups, but the number of teeth showing positive trypsin-like activity was more in deep periodontal pocket groups. 2. There was a significant positive correlation between probing pocket depth and trypsin-like activity in subgingival plaque(y=0.413X - 0.955, r = 0.7024, p<0.001). 3. There was no consistent relationship between loss of attachment and trypsin-like activity in subgingival plaque(p>0.01).
미소운동 변환방법을 이용한 몇가지 이동로봇의 기구학 모델
박재한(Jae-Han Park),김순철(Soon-Chul Kim),이수영(Soo-Yeong Yi) 제어로봇시스템학회 2013 제어·로봇·시스템학회 논문지 Vol.19 No.12
Kinematic modeling is a prerequisite for motion planning and the control of mobile robots. In this paper, we proposed a new method of kinematic modeling for a type of mobile robot based on differential motion transformation. The differential motion implies a small translation and rotation in three-dimensional space in a small time interval. Thus, transformation of the differential motion gives the velocity relationship, i.e., Jacobian between two coordinate frames. Since the theory of the differential motion transformation is well-developed, it is useful for the systematic velocity kinematic modeling of mobile robots. In order to show the validity for application of the differential motion transformation, we obtained velocity kinematic models for a type of exemplar mobile robot including spherical ballbots.