• Korean Journal of Optics and Photonics
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• v.3 no.4
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• pp.244-251
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• 1992

Buried Bragg filters of single mode $Si_{3}N_{4}$ rib waveguide with a cover layer of $SiO_{2}$ and grating at the interface of $Si_{3}N_{4}$ and $SiO_{2}$ are designed and fabricated. Etching of the grating on $Si_{3}N_{4}$ waveguide core by buffered HF showed uniform etching with good control up to 1 nm. This buried type of Bragg filters are immune to contamination of the surface of device. The mode index and bandwidth of filters are determined by measurements of the transmission spectrum of Bragg filters and compared with that of calculation. Waveguide Bragg filters loaded with the micro-heater of Cr film and the cladding of silicone rubber are made to control the Brag wavelength of the filter. As a result the filter wavelength of the device moved by 0.41 nm for 10 mA current to the shorter side of wavelength proportional to the square of the current.

• Korean Journal of Optics and Photonics
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• v.6 no.4
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• pp.310-316
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• 1995

We designed the $1.3/1.55\mum$ WDM directional coupler and its coupling length was calculated with the variation of the two waveguide's core separation and other variables by the Fourier transformed scalar wave equation. We deposited the PSG films for optical waveguide by low pressure chemical vapor deposition and fabricated the WDM coupler using the laser lithography and $CF_4/O_2$ reactive ion etching process. A V -groove which was made to support and fix the optical fiber is fabricated on Si substrate by chemical etching. The WDM coupler and the V-groove are connected using UV curing epoxy. We found that propagation mode of each port of WDM coupler is single mode and maximum extinction ratio between two out ports is 6 dB for $1.3.\mum$, and 12 dB for $1.55\mum$. /TEX>.

• Korean Journal of Optics and Photonics
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• v.16 no.4
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• pp.340-344
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• 2005

Microlens cells of Ge-doped BPSG (Boro-Phospho-Silicate Glass) are fabricated by dicing the film produced by FHD (Flame Hydrolysis Deposition). Microlens arrays of $53.4{\mu}m$ square unit are produced by the thermal reflow of the diced unit cells at $1200^{\circ}C$. The gap between the microlenses was about $70{\mu}m,$ and the thickness of the produced lens was about $28.4{\mu}m$. We analyzed the reflowed shape of the microlens cell by an image-process technique, and the focal length was about $62.2{\mu}m$. This method of fabricating a microlens is simple and inexpensive compared to the conventional method using the photolithographic process. Also, the control of the radius of curvature of the microlens is easier and a more precise microlens way of various types can be fabricated using this method.

• Korean Journal of Optics and Photonics
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• v.8 no.3
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• pp.223-229
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• 1997

A source code is developed on the basis of Berreman's 4$\times$4 matrix formalism for the analysis of polarization transmission characteristics of twisted nematic liquid crystal display. By using the program, the polarization transmission characteristics of liquid crystal cells and polarizers are analyzed. For a normally white twisted nematic liquid crystal cell, we obtained a family of iso-contrast contours which helps to understand the viewing angle characteristics of the liquid crystal display device by using the cell. The program also help us to understand the variation of the degree of polarization as well as the deviation of the state of polarization of the light transmitted through the polarizer commonly used in the LCD according to the change in incidence angle. This result suggests the contrast of the images appearing on the LCD can be limited by the characteristics of the polarizer in addition to the liquid crystal cell.

• Korean Journal of Optics and Photonics
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• v.6 no.3
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• pp.233-238
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• 1995

'#65279;We made $P_2O_5-SiO_2$ films on silicon for integrated optics application by low pressure chemical vapor deposition using TEOS(tetraethylorthosilicate), TMPite(trimethylphosphite) and phosphine($PH_3$). And We studied and compared between TMPite and PH, as a dopant of P in PSG films in the aspect of the de,position characteristics. Deposition rate of TMPate-PSG films was $55 \AA/min$ which was smaller than 90 A/min , that of $PH_3-PSG$ films. Thickness deviation of TMPate-PSG films was 2% and that of PH3-PSG was 4.5%. So TMPate-PSG films had a good quality in thickness uniformity. The range of refractive index was controlled from 1.445 to 1.468 at 633 nm in TMPate-PSG films and it was controlled from 1.456 to 1.476 in $PH_3-PSG$ films.

• Parasites, Hosts and Diseases
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• v.32 no.3
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• pp.149-156
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• 1994

An epidemiological study fur the Intestinal trematode infection of the villagers was done In Koje-myon, Kochang-gun, Kyongsangnam-do, Korea in March, 1994. Of 116 stool specimens examined, total helmlnthic ova positive cases were 13 (11.2%) and cumulative ova positive cases 21 (18.1%): Echinostoma hortense 11 cases (9.5%), Metngonimus sp. 6 cases (5.2%), and Clonorchis sinensis 4 cases (3.4%). After the treatment and purgation, variable numbers of E. hokene, 6 to 227 per person, were collected from 7 echlnostome egg Positive cases, together with M. tokohoshii In 6 cases. Three adult flukes of E. cinetorchis were collected from one person and one Stellantchasmw jnlcatus was recovered from another case. This mountainous village was proved to be one of the endemic foci of echlnostomlasis In Korea.

• The Journal of the Korean bone and joint tumor society
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• v.11 no.2
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• pp.111-117
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• 2005

Purpose: We evaluate the results of treatment of pathologic femur fractures secondary to bone tumors in children. Materials and Methods: Between January 1995 and June 2004, 18 patients(20 cases) were evaluated. Their mean age of the first episode of fracture was 10.2 years and mean follow-up period is 42.5 months. Primary bone tumors, the location of fracture, time to union and complications were evauated. Results: Fractures occurred at proximal portion in 14 cases, shaft 3 cases and distal portion 3 cases. The bone tumors causing pathologic fracture were fibrous dysplasia(9 c ases), simple bone cyst(4 cases), aneurysmal bone cyst(4 cases), nonossifying fibroma(2 cases) and eosinophilic granuloma(1 case). In the treatment for fractures, cast was in 11 cases, internal fixation 8 cases and external fixation in 1 case. In the treatment for tumors, observation was in 11 cases, curettage & bone graft in 8 cases and resection in 1 case. In polyostotic fibrous dysplasia, all cases were treated by cast initially but deformity developed in all cases. Fracture prevention and deformity correction were obtained with intramedullary nailing. Conclusion: Adequate choice of treatment of bone tumor and fracture will result in good prognosis.

• Korean Journal of Plant Taxonomy
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• v.42 no.4
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• pp.253-259
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• 2012

The genetic variation in populations of Eranthis byunsanensis, an endemic and rare species of Korea, was studied using starch gel electrophoresis. All five known populations were sampled for allozyme electrophoresis of nine enzymes coded by 10 loci. The overall genetic variation of E. byunsanensis population was shown to be considerably high within the populations (A = 2.4, P = 90.0, $H_E$ = 0.311). A positive $F_{IS}$ value of E. byunsanensis indicated an overall deficiency of heterozygotes, and a low $F_{ST}$ value (0.131) showed little differentiation among populations. The high genetic variation, less genetic differentiation among populations, and a significant amount of heterozygote deficiency propose the hypothesis that they have an experience of recent isolation and fragmentation of their habitat. Thus, the rate of gene flow has been drastically reduced, and the rate of inbreeding in E. byunsanensis populations has increased. Current habitats in Mai-san and Naro-do are vulnerable due to their small population size and the levels of anthropogenic activity in the region constantly threatening survival of this species. Because of the high genetic variation and low levels of differentiation among populations in E. byunsanensis, it is not issue which populations have a priority for protection, but we may concern the plan to maintain population continuously and diminish the rate of inbreeding.

• Journal of Ecology and Environment
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• v.29 no.3
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• pp.247-252
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• 2006

For the spring ephemeral and myrmecochorous perennia, Corydalis filistipes Nakai (Fumariaceae), rare and narrow endemic to Ullung Island in Korea, genetic diversity and structure of 4 subpopulations of the species were investigated with allozyme markers. Levels of genetic diversity (A=1.73, $P_{95%}$=61..2%, Ho=0.201, He=0.167) were relatively lower than those of other endemic species with widespread distribution range, but considerably higher than other endemic species with similar life history traits isolated in island. The moderate level of genetic diversity within subpopulations in C. filistipes is characteristic of the species with predominantly outcrossing, myrmecochorous seed dispersal by dual function of the elaisome and mode of sexual and asexual reproduction by the cleistogamy. The analysis of fixation indices showed an overall excess of heterozygotes (mean $F_{IS}=-0.1889,\;F_{IT}=-0.1226$) relative to H-W expectations. About 5.6% of the total genetic variation was found among subpopulations ($F_{ST}$=0.0557). The strategies of reasonable conservation and management, and the maintenance mechanism of genetic diversity of Corydalis filistipes Nakai, endemic plant species in Korea were discussed.

• Korean Journal of Materials Research
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• v.9 no.5
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• pp.478-483
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• 1999

The effects of the composition on the consolidation temperature and refractive index of the glass thin film fabricated by aerosol flame deposition method in SiO$_2$-B$_2$O$_3$-CaO-P$_2$O\ulcorner system were investigated. When the amount of CaO was constant in SiO$_2$-B$_2$O$_3$-CaO system the consolidation temperature of glass thin film decreased with increasing the amount of B$_2$O$_3$. Also, when the amount of SiO$_2$ and B$_2$O$_3$ was constant the consolidation temperature of glass thin film increased with increasing the amount of CaO. P$_2$O\ulcorner was added to 72.5SiO$_2$-25B$_2$O$_3$-2.5CaO in order to decrease its consolidation temperature. As the amount of P$_2$O\ulcorner increased its consolidation temperature decreased and the refractive index linearly increased from 1.4649 to 1.4684. When the amount of CaO and P$_2$O\ulcorner was constant in SiO$_2$-B$_2$O$_3$-CaO-P$_2$O\ulcorner system the consolidation temperature of glass thin film decreased with increasing the ratio of SiO$_2$/B$_2$O$_3$.