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Thermal Cycling 이 광중합형 글래스아이 오노머 수복재의 압축강도에 미치는 영향
박재한 朝鮮大學校 口腔生物學硏究所 1999 Oral Biology Research (Oral Biol Res) Vol.23 No.2
This study was performed to evaluate the effect of thermal cycling on the compressive set glass ionomer material(Fuji Ⅱ), two resin-modified glass-ionomer materials(Fuji Ⅱ LC, Vitremer), and two polyacid-modified composite resins(Compoglass, Dyract). The compressive test specimens were fabricated in a teflon mold giving 3 ㎜ in diameter and 6 ㎜ in length. All samples were divided into two groups. Group 1 was immersed in a 37℃ distilled water for 10 dsys. Group 2 was subjected to 10,000 thermal cycles between 5℃ and 55℃, and the immersion time in each bath was 15 seconds per cycle. Compressive test was subjected to a crosshead speed of 0.5㎜/min. The results obtained were summarized as follows; 1. The compressive strength values of the tested resin-modified glass ionomer materials and polyacid-modified resin composites were inferior to that of hybrid resin composite. 2. The compressive strength values of polyacid-modified resin composites were higher than those of resin-modified glass-ionomer materials, which were much higher than that of conventional glass-ionomer materials. 3. The highest compressive strength value of 45.4 MPa was observed in the DR group and the lowest value of 13.3 MPa was observed in the FL group after the thermal cyling test, and the strength of polyacid-modified composite groups were significantly higher than those of other groups(p<0.05). 4. The compressive strength of polyacid-modified resin composites showed that the DR group containing the crushed fillers was higher than that of the CG group containing the spherical fillers.
박재한 대한평형의학회 2016 Research in Vestibular Science Vol.15 No.4
According to the Barany Society classification of vestibular symptoms, positional dizziness or vertigo is defined as dizziness or vertigo triggered by and occurring after a change of head position in space relative to gravity. Thus, positional dizziness or vertigo should be differentiated from orthostatic dizziness or vertigo, which is triggered by and occurs upon rising. Benign paroxysmal positional vertigo (BPPV) is the most common positional vertigo and accompanied by a characteristic paroxysmal positional nystagmus. But a problem occasionally encountered in clinical practice is the presence of a positive history of BPPV with a negative diagnostic maneuver for positional nystagmus. Orthostatic hypo-tension may be dependent upon various neurogenic and non-neurogenic disorders and conditions. Combination of non-pharmacological and pharmacological treat-ment improve orthostatic tolerance.Res Vestib Sci 2016;15(4):107-111
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 $600^{\circ}C$.
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 $0.01Eu^{2+}/0.03Dy^{3+}$.
박재한,강신 한국모델콘텐츠학회 2022 한국모델콘텐츠학회지 Vol.3 No.1
The purpose of this paper is to identify how body comparison influences on the body cathexis of students majoring in modeling and whether the gender and agency contract status influence on the body comparison and body cathexis. This paper targeted on the college students majoring in modeling, conducted online and offline survey, and used total of 244 results for the analysis. To analyze the collected data, this paper used SPSS 20.0 and carried out the frequency analysis, factor analysis, reliability analysis, multiple regression analysis, and independent samples t-test. The analysis results were as follows. First, body comparison had a negative influence on the body cathexis to some degree. Secondly, the subjects showed significant difference in body comparison and body cathexis depending on the gender. Third, the subjects showed significant difference in body comparison and body cathexis depending on whether the subjects signed a contract with agency or not. As the body comparison and body cathexis may act as the predisposing factors of selfesteem, confidence, learning motive, frustration, depression, disordered eating behavior, and other elements, there needs to be multidisciplinary researches on the body comparison and body cathexis.