• Journal of Periodontal and Implant Science
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• v.30 no.2
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• pp.241-257
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• 2000

Autogenous periosteal grafts are an attractive alternative to existing barrier membrane materials since they meet the reqiurements of an ideal material. But no histological data are available on the effectiveness of periosteal membranes in the treatment of periodontal defects. The purpose of this study was to evaluate effect of autogenous periosteal graft on periodontal regeneration histologically. Class II furcation defects were surgically created on the second, third and the fourth premolars bilaterally in the mandibules of six mongrel dogs. The experimental sites were divided into three groups according to the treatment modalities; control group - surgical debridement only; Group I- autogenous periosteal membrane placement after surgical debridement; Group II-autogenous periosteal membrane placement after surgical debridement and bone grafting. The animals were sacrificed at 2, 4 and 12 weeks after periodontal surgery and the decalcified and undecalcified specimens were prepared for histological and histometrical analysis. Clinically all treated groups healed without significant problems. Under light microscope, at 2 weeks, control group showed significant apical epithelial migration and bone remodelling only below the notch area. But for the group I, II with autogenous periosteal graft, less apical migration of epithelium appeared and large amount of osteoid tissue showed above the notch area. Grafted periosteal membrane was indiscernable at 4 weeks, so periosteal membrane might be organized to surrounding tissues. Histometrically, at 4 and 12 weeks, all the test and control groups didn't show significant change of epithelial zone but new attachment level tended to be gained in the test groups than control group. These results suggest that autogenous periosteal grafts should be a good alternative for guided tissue regeneration.

• Korean Journal of Optics and Photonics
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• v.18 no.5
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• pp.351-361
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• 2007

The samples composed of a GST thin film and the protective layers of $ZnS-SiO_2$ or $Al_2O_3$ coated on c-Si substrate were prepared by using the magnetron sputtering method. Samples of three different structures were prepared, that is, i) the GST single film on c-Si substrate, ii) the GST film sandwiched by the protective $ZnS-SiO_2$ layers on c-Si substrate, and iii) the GST film sandwiched by $Al_2O_3$ protective layers on c-Si substrate. The ellipsometric constants in the temperature range from room temperature to $700^{\circ}C$ were obtained by using the in-situ ellipsometer equipped with a conventional heating chamber. The measured ellipsometric constants show strong variations versus temperature. The variation of ellipsometric constants at the temperature region higher than $300^{\circ}C$ shows different behaviors as the ambient medium is changed from in air to in vacuum or the protective layers are changed from $ZnS-SiO_2$ to $Al_2O_3$. Since the long heating time of 1-2 hours is believed to be the origin of the high temperature variation of ellipsometric constants upon the heating environment and the protective layers, a PRAM (Phase-Change Random Access Memory) recorder is introduced to reduce the heating time drastically. By using the PRAM recorder, the GST samples are heated up to $700^{\circ}C$ decomposed preventing its partial evaporation or chemical reactions with adjacent protective layers. The surface image obtained by SEM and the surface micro-roughness verified by AFM also confirmed that samples prepared by the PRAM recorder have smoother surface than the samples prepared by using the conventional heater.

• The korean journal of orthodontics
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• v.30 no.3 s.80
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• pp.317-333
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• 2000

The purpose of this study was to determine the proliferative activity of the osteoblasts and fibroblasts in the midpalatal area and to investigate the adjacent periodontal tissues of individual tooth following rapid expansion of the palate. Ten young adult dogs, aged approximately ten months, were used in the experiment. The experimental design was consisted of 1 week expansion group(Group E1, 3 dogs), 2 week expansion group(Group E2, 3 dogs), 2 week expansion and 2 week retention group(Group E3, 3 dogs), and control group(Group C, 1 dog). For each group, expansion screw was activated one time per day(1/4 turn;$90^{\circ}$) following Hyrax-screw application. The experimental animals in each group were sacrificed at 1, 2 and 4 weeks following palatal expansion. Maxillary tissue blocks were obtained and prepared ior the histomorphologic and immunohistochemical studies. Light mcroscope, polarizing microscope, and soft X-ray apparatus were used in this study, and following results were obtained. 1. In polarizing microscopic study, the expansion groups(E1 & E2) showed blue color representing bone resorption and new bone formation in midpalatal suture area. E3 groups skewed less blue color compared to the E1 and E2 group. But yellow color increased by calcification in the E3 groups. 2. Immunohistochemical study revealed that positive responses of the osteoblasts to PCNA and undifferentiated fibroblasts to EGF in E1 group were somewhat increased. Positive response to PCNA and EGF were increased in fibroblasts and the osteoblasts forming new bone in E2 group. In E3 group, the positive response cell concentrated the periphery of edge of palatal process in both PCNA and EGF. 3. Throughout the expansion period(E1 & E2), light microscopic study showed the edges of the extensive resorption and new palatal processes, indicating bone remodeling within the suture. E3 group exhibited less remodeling of midpalatal suture area. E2 group and E3 group showed cementum formation and resorption at the apex of 3rd premolar and 1st molar E3 group exhibited extensive hyalinized zone on the cervical portion of buccal side of 1st molar. 4. Soft X-ray analysis of E1 group showed hypomineralized defect and microfractures in various parts of the suture areas when compared with control animals. There was no significant difference in the degree of mineralization in the midpalatal suture region between the C and E3 groups. Tooth axis showed tipping of 3rd premolar and 1st molar in the E2 group and E3 group. Based upon these experimental results, it is concluded that the undifferentiated mesenchymal cells always presented in midpalatal suture area following RPE. Differentiated osteoblasts and fibroblasts possess proliferating cellular activity until the 2 week retention period. The posterior teeth are tend to tip buccally as RPE force applied. Retention group exhibited irreversible response with severe hyalinized zone on the buccal surface of the first molar.

• Korean Journal of Remote Sensing
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• v.13 no.2
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• pp.99-120
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• 1997

Solar radiation is scattered and absorbed atmospheric compositions in the atmosphere before it reaches the surface and, then after reflected at the surface, until it reaches the satellite sensor. Therefore, consideration of the radiative transfer through the atmosphere is essential for the quantitave analysis of the satellite sensed data, specially at shortwave region. This study examined a feasibility of using radiative transfer code for estimating the atmospheric effects on satellite remote sensing data. To do this, the flux simulated by LOWTRAN7 is compared with CAGEX data in shortwave region. The CAGEX (CERES/ARM/GEWEX Experiment) data provides a dataset of (1) atmospheric soundings, aerosol optical depth and albedo, (2) ARM(Aerosol Radiation Measurement) radiation flux measured by pyrgeometers, pyrheliometer and shadow pyranometer and (3) broadband shortwave flux simulated by Fu-Liou's radiative transfer code. To simulate aerosol effect using the radiative transfer model, the aerosol optical characteristics were extracted from observed aerosol column optical depth, Spinhirne's experimental vertical distribution of scattering coefficient and D'Almeida's statistical atmospheric aerosols radiative characteristics. Simulation of LOWTRAN7 are performed on 31 sample of completely clear days. LOWTRAN's result and CAGEX data are compared on upward, downward direct, downward diffuse solar flux at the surface and upward solar flux at the top of the atmosphere(TOA). The standard errors in LOWTRAN7 simulation of the above components are within 5% except for the downward diffuse solar flux at the surface(6.9%). The results show that a large part of error in LOWTRAN7 flux simulation appeared in the diffuse component due to scattering mainly by atmispheric aerosol. For improving the accuracy of radiative transfer simulation by model, there is a need to provide better information about the radiative charateristrics of atmospheric aerosols.

• The Korean Journal of Zoology
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• v.32 no.3
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• pp.211-220
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• 1989

The fine structure of the aggregate glands-one of the capture thread producing organs-in the orb web spider, Nephila clavata L.Koch, is studied with light and electron microscopes. Gluey capture threads or sticky spirals of the orb web are originated from the silks of two flagelliform glands and four aggregate glands which are connected to the posterior spinnerets, and the arrangement fo their spigots(large spinning tubes) shows a charaterstic form called "triad". The aggregate galnd is composed of large and multilobed secretory portion and thick excretory duct surrounded by large irregular nodules. The excretory duct of the aggregate galnds basically consists of three superposed types of cells which are inner columnar epithelium, nodule-forming cells and outer connestives. The cuticles of the proximal duct near the secretory portion are composed of endocuticle and exocuticle, whereas ghe distal duct near the spinning tubes has a electron lucent subcuticle which had the functions of water removal and orientation of silk fibers. In the cytoplasmic process of the large and irregular nodule-forming cells surrounded by invaginations of the plasma membranes, numerous mitochondria and glycogen particles are contained. The maturational level of the nodule cells is perceived from the appearence of these cell inclusions. The secretory portion of the glands which porduce the secretory silk material shows two layers of the cells which are simple cuboidal epithelium and several connective layers. In the cytoplasm of the glandular epithelial cell, rough endoplasmic reticulums are well developed, and two types of secretory granules are observed. Between the adjacent epithelial cells, specialized septate junctions are formed along the plasma membranes.membranes.

• Journal of Korean Ophthalmic Optics Society
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• v.8 no.2
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• pp.111-117
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• 2003

We collected the domestic and foreign half-mirror coating lens for sunglasses. Their reflectance is measured using Spectrophotometer in order to analysis their optical property and the result which is calculated using Macleod program was compared with measured reflectance. In addition, we designed the new half-mirror coating lens with gold color using TiN material and investigated the optical property of the new half-mirror coating lens. The results obtained from analysis of half-mirror coating lenses are as follow : Two-tone half-mirror coating with silver color is fabricated with [air|$SiO_2$(or $Al_2O_3$)|Cr|glass]. The role of $SiO_2$(or $Al_2O_3$) on Cr improve the hardness of the lens and the thickness of the $Al_2O_3$ with 10 nm is good to show the lens silver color. Incase of color half-mirror coating lens. Blue system is designed by [air|$SiO_2$(66.3)|$TiO_2$(129.0)|$SiO_2$(62.9)|$SiO_2$(26.0)|$TiO_2$(120.3)|$SiO_2$(9.1)|glass], gold system [air|$SiO_2$(60.6)|$TiO_2$(86.2)|$SiO_2$(13.5)|$TiO_2$(86.8)|$SiO_2$(214.38)|glass], green system[air|$SiO_2$(74.3)|$TiO_2$(75.8)|$SiO_2$(44.3)|$TiO_2$(11.6)|$SiO_2$(160.8)|$TiO_2$(12.9)|$SiO_2$(183.3)|$TiO_2$(143.8)|glass], silver system[air|$SiO_2$(21.2)|$TiO_2$(49.7)|$SiO_2$(149.3)|glass]. White half-mirror coating lens has [air|$SiO_2$(17 nm)|$TiO_2$(43 nm)(or $ZrO_2$)|$SiO_2$(87 nm)|polysiloxane($4.46{\mu}m$|glass or CR-19]. It has half-mirror coaling lens which has about 19% reflectance and about 80% transmittance in the range of visible light(400~700nm). we designed the new half-mirror coating lens with gold color, the (x, y) value of the CIE is almost similar to the CIE value of [air|$SiO_2$(170 nm)|TiN(15 nm)|glass].

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.416-417
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• 2013

최근 질화물계 발광다이오드(light emitting diode, LED) 소자는 핸드폰, 스마트 TV 등의 디스플레이 분야와 실내외조명, 감성조명, 특수조명 등의 조명분야에 그 응용분야가 급속히 확대되고 있다. 이러한 LED 소자는 에너지 절감과 친환경에 장점을 가지고, 가까운 미래에 조명시장을 대체할 것으로 예상된다. 이를 만족하기 위해서는 현재보다 더 높은 효율을 갖는 LED 개발이 요구되어지고 있는 상황이다. 일반적으로 질화물계 LED 소자의 효율은 내부양자 효율, 광추출 효율 등으로 나타낼 수 있다. 내부 양자효율은 성장된 결정의 질의 개선 및 다층의 이종접합 또는 다중양자우물 구조와 같이 활성층의 캐리어 농도를 높이는 접합구조로 설계되어 80% 이상의 효율을 나타낸다. 그러나 광추출 효율은 이에 미치지 못하고 있다. 이는 반도체 재료의 높은 굴절률로 인하여 빛이 외부로 탈출하지 못하고 내부로 반사되거나 물질 안에서 흡수가 일어나기 때문이다. 따라서 이러한 문제를 해결하기 위해 많은 연구 그룹들은, 표면에 패턴 형성하여 빛의 전반사를 줄여 그 효율을 올리는 연구결과를 보고하고 있다. 대표적인 방법으로는 wet etching, 전자빔 리소그라피, 나노임프린트 리소그라피, 레이저 홀로 리그라피, 나노스피어 리소그라피 등이 사용되고 있다. 이 중, 나노스피어 리소그라피는 폴리스틸렌 혹은 실리카 등과 같은 나노 크기의 bead를 사용하여 반도체 기판 표면에 단일층으로 고르게 코팅한 마스크로 사용하여 패턴을 주는 방법이다. 이 방법의 장점으로는 대면적에 균일한 패턴을 형성할 수 있고, 공정비용이 저렴하여 양산하기에 적합하다는 특징이 있다. 나노스피어 리소그라피를 통해서 표면에 생성된 패턴 모양의 각도에 따라서, 식각되는 깊이에 변화에 따라 실험한 결과들은 있지만, 아직까지 크기가 다른 나노입자들의 마스크 이용하여 형성된 패턴 밀도에 따른 광 추출 효과에 대한 연구가 많이 미흡하다. 따라서 본 연구에서는 다양한 크기의 실리카로 패턴을 형성시켜 패턴 밀도에 대한 광추출 효율의 효과에 대해서 조사하였다. 실험 방법으론, DI, 에탄올, TEOS, 암모니아의 순서대로 그 혼합 비율을 조정하여 100, 250, 500 nm 크기의 나노입자를 합성하였고 이것을 질화물계 LED의 표면 위에 단일층으로 스핀코팅 방법을 통해 코팅을 하였다. 그 후 ICP-RIE 방법으로 필라 패턴을 형성하였는데, 그 결과 100 nm SiO2 입자를 이용한 경우 $4.5{\times}10^9$/$cm^2$, 250 nm의 경우 $1.4{\times}10^9$/$cm^2$, 500 nm의 경우 $0.4{\times}10^9$/$cm^2$의 패턴의 밀도를 보여주었다(Fig. 1). 패턴의 밀도에 따라 전계광학적 특성을 확인하여 보았는데, 그 결과는 평평한 표면과 비교하였을 때 100 nm에서 383%, 250 nm에서는 320%, 500 nm에서는 244% 상승하는 결과를 보여주었다(Fig. 2). 이번 실험을 통해서 LED의 광추출 효율은 표면 모양과 깊이 뿐 아니라 밀도가 커질수록 그 효율이 올라간다는 사실을 알 수 있었다.

• Journal of the Korean Vacuum Society
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• v.22 no.2
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• pp.79-85
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• 2013

Rare earth ions, either $Eu^{3+}$ or $Dy^{3+}$-doped $CaMoO_4$ phosphors were synthesized by using the solid-state reaction method. The crystalline structure of all the phosphor powders, irrespective of the type and concentration of activator ions, was found to be a tetragonal system with the main diffraction peak at (112) plane. For $Eu^{3+}$-doped $CaMoO_4$ phosphors, the grain particles showed an increasing tendency and the pebble-like patterns with a very homogeneous size distribution in the range of 0.01~0.10 mol of $Eu^{3+}$ ions concentration, and the excitation spectra were composed of a broad band centered at 311 nm and weak multiline peaked in the range of 360~470 nm. The dominant emission spectrum was the strong red emission centered at 618 nm due to the $^5D_0{\rightarrow}^7F_2$ transition of $Eu^{3+}$ ions. For $Dy^{3+}$-doped $CaMoO_4$ powders, excitation spectra showed a charge transfer band centered at 303 nm and relatively weak bands resulting from the transitions of $Dy^{3+}$ ions and the main yellow emission spectrum was observed at 578 nm, which was assigned to the $^4F_{9/2}{\rightarrow}^7H_{13/2}$ transition of $Dy^{3+}$ ions.

• Applied Chemistry for Engineering
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• v.35 no.4
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• pp.296-302
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• 2024

An ionic conjugated polymer-iron (III) chloride composite was prepared via in-situ quaternization polymerization of 2-ethynylpyridine (2EP) using iron (III) chloride. Various instrumental methods revealed that the chemical structure of the resulting conjugated polymer (P2EP)-iron (III) chloride composite has the conjugated backbone system having the designed pyridinium ferric chloride complexes. The polymerization mechanism was assumed to be that the activated triple bond of 2-ethynylpyridinium salt, formed at the first reaction step, is easily susceptible to the step-wise polymerization, followed by the same propagation step that contains the propagating macroanion and monomeric 2-ethynylpyridinium salts. The electro-optical and electrochemical properties of the P2EP-FeCl₃ composite were studied. In the UV-visible spectra of P2EP-FeCl₃ composite, the absorption maximum values were 480 nm and 533 nm, and the PL maximum value was 598 nm. The cyclic voltammograms of the P2EP-FeCl₃ composite exhibited irreversible electrochemical behavior between the oxidation and reduction peaks. The kinetics of the redox process of composites were found to be very close to a diffusion-controlled process from the plot of the oxidation current density versus the scan rate.

• Journal of Sericultural and Entomological Science
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• v.36 no.2
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• pp.138-146
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• 1994

The structural characteristics of Antheraea yamamai and Antheraea pernyi silk were investigated by using x-ray diffraction method, IR spectroscopy and polarizing microscopy. The amino acid composition, fiber density, thermal decomposition temperature and glass transition temperature were also measured for relating these physical properties to the structure in comparison with those of Bombyx mori silk fiber. There was no significant structural difference between A. yamamai and A. pernyi silk fiber on an examination of x-ray diffraction curve and IR spectrum. Both of these wild silk fibers showed double diffraction peaks at the Bragg angle 2Θ16.7˚ and 20.5˚by x-ray diffraction analysis as well as IR absorption peaks for the bending vibration of specific groups related to ala-ala amino acid sequence. On the other hand, the x-ray diffraction curve and IR spectrum of Bombyx mori silk fiber are different from those of wild silk fibers, indicating different crystal structure as well as amino acid sequences. It showed under the polarizing microscope examination that the birefringence and optical orientation factor of wild silk fibers are much lower than those of B. mori silk. Also, the surface of degummed wild silk fibers was characterized by the longitudinal stripes of microfibrils in the direction of fiber axies. The amino acid composition, which is strongly related to the fine structure and properties, was not significantly different between these two wild silk fibers. However, the alanine content was somewhat less and polar amino acid content more for A. yamamai. As a result of fiber density measurement, the specific gravities of B. mori, A. pernyi and A. yamamai were 1.355~1.356, 1.308~1.311, 1.265~1.301g/㎤ in the order, respectively. The calculated crystallinity(%) was 64% for B. mori and 51~52% for wild silk fibers, which showed same trend by IR method in spite of somewhat higher value. The thermal decomposition behaviour was examined by DSC and TGA, showing that the degradation temperature was in the order of B mori, A. prernyi and A. yamamai at around 350$^{\circ}C$. It was also observed by TGA that the decomposition seems to proceed step by step according to their specific regions in the fiber structure, resulting the difference in their thermal stabilities. The glass transition temperature was turned out to be 220$^{\circ}C$ for B. mori, 240$^{\circ}C$ A. yamamai and 255$^{\circ}C$ A. pernyi by the dynamic mechanical analysis. It is expected that the chemical properties are affected by the dynamic mechanical behavior in accordance with their structural characters.