Self-etching primer를 이용하여 접착된 교정용 브라켓의 전단결합강도

안윤표,김효영,전영미,김정기 대한치과교정학회 2003 대한치과교정학회지 Vol.33 No.1

본 연구는 6세대 교정용 접착 시스템인 Transbond Plus Self-Etching Primer(3M/Unitek Dental Products, Monrovia, Calif)를 이용하여 법랑질면에 브라켓을 접착하는 방법과, 통상적인 산부식 방법에 의해 브라켓을 접착한 경우의 전단결합강도 차이를 비교·평가하고, self etching primer를 이용하여 브라켓을 접착할 때 치면에 존재하는 수분이 브라켓의 전단결합강도에 미치는 영향에 관하여 조사하였다. 37% 인산용액과 Self-Etching Primer를 잉용하여 법랑질을 표면 처리하고 Transbond XT를 이용하여 브라켓을 치면에 부착하였다. 또한 수분의 존재에 따른 전단결합강도의 차이를 평가하기 위해 인공타액을 치면에 도포후 Self-Etching Primer를 사용하여 브라켓을 부착한 후 30분과 24시간에 따른 전단결합강도를 비교 평가하여 다음과 같은 결론을 얻었다. 1. Self-etching primer군에서 건조군과 습윤군의 전단결합강도는 37%인산처리군의 결합강도보다 낮았다(p<0.05). 그러나 Self-etching primer군의 전단결합강도는 임상적으로 유용한 수준의 이상이었다. 2. 모든군에서 24시간군의 전단결합강도가 30분군의 전단결합강도보다 높았으며(p<0.05), 이는 브라켓 접착후 일정시간의 경과가 결합강도를 증가시켜 줌을 알 수 있었다. 3. Self-etching primer군에서 습윤군의 전단결합강도는 건조군보다 높은 경향이었으나 통계적 유의성은 인정되지 않았다(p<0.05). 4. ARI 점수의 비교결과 인산처리군에서는 0점과 1점의 빈도가 높았으며, Self-etching primer 건조군과 습윤군에서는 2점과 3점의 빈도가 높아(p<0.05) Self-etching primer군이 인산처리군보다 법랑질-레진 접착계면부위에서의 파절이 많이 일어남을 알 수 있었다. The purpose of this study was to evcaluate the effects of a self-etching primer on the shear bond strength of orthodontic brackets and on the failure pattern of bracket-adhesive interfaces in dry or wet condition. Brackets were bonded to extracted human teeth according to one of three experimental protocols. In the Group P, teeth were etched with 37% phosphoric acid. After the Transbond XT Primer was applied onto the etched surfaces, the brackets were bonded with Transbond XT(3M, Unitek, Monrovia, Calif) and light cured for 40 seconds. In the Group SD, a self-etching primer(3M, Unitek, Monrovia, Calif) was placed on the enamel for 3 seconds and gently evaporated with air, as suggested by the manufacturer. The brackets were then bonded with Transbond XT as in the Group P. In the Group SW, artificial saliva was applied to the enamel surface for 10 seconds to allow complete hydration of the surface before application self-etching primer. The brackets were then bonded following the procedures of Group SD. Each group was divided into 2 sub-groups(0.5h, 24h) according to debonding time shear bond strengths were measured by Instron universal testing machine. After debonding, the teeth and brackets were examined under scanning electron microscope and assessed with the adhesive remnant index. The result obtained were summarized as follows ; 1. The shear bond strengths were high enough to use clinically in all testing groups, but the shear bond strengths of group SD and SW were significantly lower than Group P(p<0.05). 2. With respect to comparison of debonding time, 24h debonding samples exhibited heigher shear bond strength than 0.5h debonding samples in Group P, SD and SW(p<0.05). 3. In the self etching primer groups(Group SD and Group SW), there was no significant difference in mean shear bond stredifference in mean shear bond strength between under dry and wet state(p>0.05). 4. There was a greater frequency of ARI score of 0 and 1 with the Group P. On the other hand, there was a higher frequency of ARI scores of 2 and 3 with Group SD and Group SW(p<0.05).,

所得에 따른 餘暇와 일의 態度 硏究

金榮學,金振杓,全成春 龍仁大學校 1994 용인대학교 논문집 Vol.10 No.-

The purpose of this study is to analyse the work and the leisure attitude based on the income. The subjects participated in the study were 594 as a adult : 302 male, 292 female. On the basis of positivistic are sociological analysis, the conclusions are as follow. First, as the leisure attitude based on the income, the group of low income estimated the leisure attityde the most positively, in the next place, the group of middle, high in order, but there was statistically no significant differened. Thus, The leisure attitude of the korean people was not different from group in terms of the income relation. Second, as the Work attitude based on the income, the group of low income estimated the work attitude the most positively, in the next place, the group of high, middlem in order. There was statistically significant difference in the P,.05 level. Thus, the work attitude of the korean people was different from group in terms of the income relation. Third, all the three groups estimated leisure more positive than work. The leisure view of the korean people was gradually changing in the comparing with the last times. Thus, we must practise the leisure education on the purpose of the effective use of leisure time and build up of sound leisur culture.

新農村建設(定住生活圈開發)을 위한 理論的 考察 및 開發需要調査

金鴻允,李弘柱,鄭禮杓,全禹亭,趙興洙,李信昊,全榮吉 안성산업대학교 1992 論文集 Vol.24 No.-

Rural of Koreas has rapidly changed through the process of industrialization and urbanization. During past 30 years, development differences between urban and rural, metroplitan area and area derived from a highly economic growth, bring about dual specialization that deepens overpopulation and sparsity. Therefore, with a new concern about rural, necessity of rural development policy that developes a settlement and life area for settlement for ensuing stablized settlement and living activity of rural people, has been drived step by step. For rural welfare establishment that is settled and good hereafter, this study aims at attempting a theoretical approach about the way of development for rural settlement as a new rural development strategy through examination of today's rural reality, under assumption that rural people must be able to obtain stable jobs and to be pleasant without leaving rural area, and rural settlement to be able to enjoy urban advantages must be realized. Therefore, items that must be obtained basically rural area to be a human settlement space are equipment connected with a dwelling house, production, consumption, job relaxation, infrastructure connected with transportation or communication network and environment. By the way, the best function of a human settlement space makes a basic pleasant settlement area to be in the middle of that. Then rationalization of land use must be realized as being a best condition for human life around space of a dewelling house. Besides, spacial accessibility about all equipment of inhabitants must be easy. That is, economic distance, social distance and cultural distance as well as spacial distance must be included. Also, those spacial functions must be realized on a basis of suitable enironment for a human settlement life. At the same tiem, the upper area must be connected with the lower area as the system of spacial settlement in settlement space. But truely, as rural people can't satisfy with services of the surrounding rural areas, they desire better city or metroplitan. The these problems bring about inequality between urban and rural. Therefore, here are urgent reasons that must be done rearing of rural central town and rural integrated development of unit area. So, these dys, to correct maldistribution of land use and inequality of settlement space that Korean society faces on, new strategies of rural integrated development for lift area for settlement than gives the meaning. That rural areas become like a place for human settlement life will be able to be chosen in the view of humanism. The say of thinking of rural residents(Jukans-myun, Anseong-gun, Kyeonggi-do) was surveyed in order to develop new rural settlement planning. From the data collected in this survey, rural life-style, view on traditional rural life, agriculture, farming, agri-policy, social attitude, and degree of satifaction of rural life, etc, were analyzed. Firstly, most of rural residents interviewed in this survey have the opinion of not leaving their home village if living conditions improved to a reasonable level in the near future. In decision-making process of village affairs, they want to participate actively and equally. Secondly, in spite of their acceptance of agriculture as a vital sector destined to national security, most of them think that framing should be little of promise. Thirdly, they have the negative attitude to urban-oriented social valued and also to the agricultural policy, while seeking consolation through human and traditional viewing of rural life style. Therefore, in the development of new rural settlement model, idea-making should be directed to the betterment of communal value of village life, stability of rural economy, rationalization of rural life style and enhancement of rural-type happiness.

Effect of the pre‑treated pyrolysis fuel oil: coal tar pitch ratio on the spinnability and oxidation properties of isotropic pitch precursors and the mechanical properties of derived carbon fibers

Jinchang Liu,Hiroki Shimanoe,Jong‑Eun Choi,Seunghyun Ko,Young‑Pyo Jeon,Koji Nakabayashi,Jin Miyawaki,Seong‑Ho Yoon 한국탄소학회 2019 Carbon Letters Vol.29 No.2

Pitch precursors affording excellent spinnability, high-level oxidation-resistance, and good carbonization yields were prepared by bromination–dehydrobromination of various ratios of pyrolyzed fuel oil and coal tar pitch. The pitches exhibited spinnabilities that were much better than those of pitches prepared via simple distillation. A pitch prepared using a 1:2 ratio of fuel oil and coal tar pitch exhibited the best tensile strength. Pitch fibers of diameter 8.9 ± 0.1 μm were stabilized at 270 °C without soaking time after heating at a rate of 0.5 °C/min and carbonized at 1100 °C for 1 h after heating at 5 °C/min. The resulting carbon fibers exhibited a tensile strength, elongation, Young’s modulus, and average diameter of 1700 ± 170 MPa, 1.6 ± 0.1%, 106 ± 37 GPa, and 7.1 ± 0.2 μm, respectively.

Blue phosphorescent organic light-emitting devices based on carbazole/thioxanthene-S,S-dioxide with a high glass transition temperature

Jeon, Young Pyo,Kim, Kyu Sung,Lee, Kyeong Kyun,Moon, In Kyu,Choo, Dong Chul,Lee, Jun Yeob,Kim, Tae Whan The Royal Society of Chemistry 2015 Journal of materials chemistry. C, Materials for o Vol.3 No.24

<▼1><P>A bipolar host material for blue organic light-emitting devices was synthesized by incorporating electron-donating carbazole and electron-accepting thioxanthene-<I>S</I>,<I>S</I>-dioxide into one molecule using a solventless green reaction.</P></▼1><▼2><P>Carbazole/thioxanthene-<I>S</I>,<I>S</I>-dioxide (EBCz-ThX) bipolar molecules were synthesized by incorporating electron-donating carbazole and electron-accepting thioxanthene-<I>S</I>,<I>S</I>-dioxide into one molecule at 85 °C using a solventless green reaction method. The EBCz-ThX bipolar molecule exhibited a high glass transition temperature of 227 °C and a high triplet energy of 2.94 eV. The highest occupied molecular orbital (HOMO, −5.95 eV) and lowest unoccupied molecular orbital (LUMO, −2.63 eV) energy levels of the molecule matched the HOMO energy level of the hole transporting layer and the LUMO energy level of the electron transporting layer, respectively, which facilitated the injection of holes and electrons. Phosphorescent organic light-emitting devices (PHOLEDs) were fabricated with EBCz-ThX as a blue host material and with bis((4,6-difluorophenyl)-pyridinate-N,C2′)picolinate as a blue dopant, and the doping ratio was controlled to optimize the performance of the blue PHOLEDs. Blue PHOLEDs with a 15% doping ratio at 100 cd m<SUP>−2</SUP> showed excellent performances and low operation voltages with quantum and current efficiencies of about 12% and 24 cd A<SUP>−1</SUP>, indicating that the EBCz-ThX acted as an excellent host for the blue PHOLEDs. The external quantum efficiency at 1000 cd m<SUP>−2</SUP> was improved up to 30% in comparison with that of a conventional PHOLED with an mCP of 8% doping ratio.</P></▼2>

Efficiency Enhancement of Tandem Organic Light-Emitting Devices Fabricated Utilizing an 1,4,5,8,9,11-Hexaazatriphenylene-Hexacarbonitrile Charge-Generation Layer

Jeon, Young Pyo,Kim, Tae Whan American Scientific Publishers 2015 Journal of nanoscience and nanotechnology Vol.15 No.10

Transparent and flexible photodetectors based on CH₃NH₃PbI₃ perovskite nanoparticles

Jeon, Young Pyo,Woo, Sung Jun,Kim, Tae Whan Elsevier 2018 APPLIED SURFACE SCIENCE - Vol.434 No.-

<P><B>Abstract</B></P> <P>Transparent and flexible photodetectors (PDs) based on CH<SUB>3</SUB>NH<SUB>3</SUB>PbI<SUB>3</SUB> perovskite nanoparticles (NPs) were fabricated by using co-evaporation of methyl ammonium iodide and lead iodide. X-ray diffraction patterns and high-resolution transmission electron microscopy images demonstrated the formation of perovskite NPs. The optical transmittance of the perovskite NPs/glass was above 80% over the entire range of visible wavelengths, indicative of high transparency. The PDs based on CH<SUB>3</SUB>NH<SUB>3</SUB>PbI<SUB>3</SUB> perovskite NPs were sensitive to a broad range of visible light from 450 to 650nm. The currents in the PDs under exposure to red, green, and blue light-emitting diodes were enhanced to 5, 10, and 20 times that of the PD in the dark, respectively. The rise and the decay times of the PDs were 50 and 120μs. The current in the perovskite NP PD on a polyethylene terephthalate substrate was enhanced by approximately 69% when the NP PD was exposed to a blue LED emitting at a wavelength of 459nm. Despite multiple bending, the transparent and flexible PDs based on methyl ammonium iodide and lead iodide NPs showed reproducibility and high stability in performance.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Transparent and flexible photodetectors (PDs) based on CH<SUB>3</SUB>NH<SUB>3</SUB>PbI<SUB>3</SUB> perovskite nanoparticles (NPs) were fabricated. </LI> <LI> Optical transmittance of the perovskite NPs/glass was above 80% over the entire range of visible wavelengths. </LI> <LI> Currents in the PDs under exposure to blue LEDs were enhanced to 20 times that of the PD in the dark. </LI> <LI> Rise and decay times of the PDs were 50 and 120μs. </LI> <LI> Performances of the transparent and flexible PDs were very stable and reproducible. </LI> </UL> </P>

Highly flexible triboelectric nanogenerators fabricated utilizing active layers with a ZnO nanostructure on polyethylene naphthalate substrates

Jeon, Young Pyo,Park, Jae Hyeon,Kim, Tae Whan Elsevier 2019 APPLIED SURFACE SCIENCE - Vol.466 No.-

<P><B>Abstract</B></P> <P>Atomic force microscopy images showed that layers with a ZnO nanostructure were regularly formed on polyethylene naphthalate (PEN) substrates coated with indium tin oxide. The output voltage of triboelectric nanogenerators (TENGs) containing layers with the ZnO nanostructure and operating in the vertical contact-separation mode was approximately 20 V, which indicated that the power was enhanced by a factor of 2 compared to that of the TENG without such layers. Bending endurance tests on the TENGs demonstrated high stability under the stress caused by bending at an angle of 90°. The average open-circuit voltage of the TENGs operating in the ambient atmosphere was reduced by only 22% after 2000 bendings. This endurance of the TENGs under bending in air could be attributed to the presence of the layers with the ZnO nanostructure.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Flexible TENGs based on ZnO nanostructural layer were fabricated on PEN substrates. </LI> <LI> V<SUB>OC</SUB> of flexible TENGs were observed after various bending stresses up to 2000 bendings. </LI> <LI> The average V<SUB>OC</SUB> values show the bending endurance of the flexible TENGs. </LI> </UL> </P>

Functional modification of Drosophila intestinal stem cells by ionizing radiation.

Pyo, Jung-Hoon,Park, Joung-Sun,Na, Hyun-Jin,Jeon, Ho-Jun,Lee, Shin-Hae,Kim, Joong-Gook,Park, So-Young,Jin, Young-Woo,Kim, Young-Shin,Yoo, Mi-Ae Academic Press 2014 Radiation research Vol.181 No.4

<P>Although the diverse effects of ionizing radiation on biological and pathological processes at various levels ranging from molecular to whole body are well studied, the effects on adult stem cells by ionizing radiation remain largely unknown. In this study, we characterized the functional modifications of adult Drosophila midgut intestinal stem cells after ionizing radiation treatment. A dose of 10 Gy of radiation decreased the proliferative capacity of intestinal stem cells. Interestingly, after irradiation at 2 Gy, the intestinal stem cells exhibited increased proliferative activity, misdifferentiation and γH2AvD and 8-oxo-dG levels. In addition, the guts irradiated with 2 Gy showed increased JNK and AKT activities. Furthermore, we showed that 2 Gy of ionizing radiation induced centrosome amplification in intestinal stem cells of adult midguts. Our data gives molecular insights into the effects of ionizing radiation on functional modifications of stem cells. The adult Drosophila midgut intestinal stem cells offer a potentially rich new system for the exploration of the biological effects of ionizing radiation.</P>

Flexible white organic light-emitting devices with a porous red polymer layer and a blue small molecular layer utilizing a phase separation of blended polymer.

Jeon, Young Pyo,Ko, Yo Sub,Choo, Dong Chul,Kim, Tae Whan American Scientific Publishers 2012 Journal of nanoscience and nanotechnology Vol.12 No.4

<P>Flexible white organic light-emitting devices (WOLEDs) with an emitting layer consisting of a porous red poly(2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylenevinylene) (MEH-PPV) polymer layer and a blue 4,4'-bis(2,2'-diphenylvinyl)-1,1'-biphenyl (DPVBi) small molecular layer were fabricated on polyethylene terephthalate substrates. The current density of the flexible WOLEDs fabricated with a blend layer formed with a higher spincoating speed was significantly higher than that of a device fabricated with a lower spincoating speed, due to the higher pore density. The ratio between the red and the blue color peak intensities of the electroluminescence spectra for the flexible WOLEDs with a porous red MEH-PPV polymer layer and a blue DPVBi small molecular layer was controlled by the spincoating speed of the blend layer.</P>