• Restorative Dentistry and Endodontics
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• v.13 no.2
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• pp.337-348
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• 1988

The purpose of this study was to examine the fracture strength and characteristics of teeth with MOD cavity preparation. Freshly extracted sound maxillary premolars were cleaned and stored in normal saline solution $37^{\circ}C$ for 72 hours before experiments. The roots of teeth were embedded in a self-curing resin, and the exposed crown were maintained in a vertical position by a modelling wax in a brass ring. The MOD cavities were prepared with No. 57 carbide bur under high speed to a depth of 2.0mm and a width of 2.0mm(Fig.1). All the prepared teeth specimens were divided into 7 groups according to the mode of cavity form and restorative materials (Table 1, 2): Group I, unpreapred, intact teeth as control Group II, prepared cavity without restoration Group III, prepared teeth restored with amalgam Group IV, prepared teeth restored with composite resin (P-10) Group V, prepared teeth with beveled enamel margins restored with composite resin (P-10) Group VI, prepared teeth restored with light-cured composite resin (P-30) Group VII, prepard teeth with beveled enamel margins restored with light-cured composite resin (P-30) After placement of restorations, all of the specimens were stored in water at $37^{\circ}C$ for 72 hours before testing. All of the specimens were tested on the Instron Universal Testing machine (No. 6025) in order to evaluate the strength of fracture. One metal ball 5.0mm in diameter contacting the specimens parallel to the occlusal surface was used to in this study (Fig. 1). The fracture characteristics of the specimens were examined with naked eye and in the scanning electron microscope (JSM-20). The results obtained from this study were as follows: 1. The mean fracture strength was the highest in group VI and that in group II was the lowest. 2. The progress of crack of teeth propagated into the pulp cavity. 3. In case of the group of the restored teeth, the crack occurred to be accompanied with cuspal fracture. 4. The crack of restored teeth was initiated along the pulpo-axial line angle of the cavity.

• Journal of the Korean Institute of Intelligent Systems
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• v.20 no.6
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• pp.786-792
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• 2010

This paper presents a real-time lane detection method which can accurately find the lane-mark boundaries in complex road environment. Unlike many existing methods that pay much attention on the post-processing stage to fit lane-mark position among a great deal of outliers, the proposed method aims at removing those outliers as much as possible at feature extraction stage, so that the searching space at post-processing stage can be greatly reduced. To achieve this goal, a grid-based morphology operation is firstly used to generate the regions of interest (ROI) dynamically, in which a directional edge-linking algorithm with directional edge-gap closing is proposed to link edge-pixels into edge-links which lie in the valid directions, these directional edge-links are then grouped into pairs by checking the valid lane-mark width at certain height of the image. Finally, lane-mark colors are checked inside edge-link pairs in the YUV color space, and lane-mark types are estimated employing a Bayesian probability model. Experimental results show that the proposed method is effective in identifying lane-mark edges among heavy clutter edges in complex road environment, and the whole algorithm can achieve an accuracy rate around 92% at an average speed of 10ms/frame at the image size of $320{\times}240$.

• Journal of Technologic Dentistry
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• v.18 no.1
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• pp.95-115
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• 1996

The esthetic factor for the esthetic prosthesis were studied on 300 persons. The praaticipants were 150 students registered under the Deparment of Dental Laboratoy Technology, Jisan Junior College at the present day of June, 1995 and their mothers. The results were as follows; 1. The number of persons with 28 teeth in their oralcatity was highest(P<0.01). They complained that they have only 28 teeth bacaues of the loss(deficiency) fo teeth due to their impacted teeth and dental caries. 2. The presons with feelings of dissatisfaction were large in number(P<0.01). They were dissatisfied with an abnormal tooth form(33.5%), tooth position(31.7%), tooth color(31.1%), and tooth size(3.7%) in order(P<0.01). 3. In their facial form, the most numerous were men with square form and women with ovoid form(P<0.01). Among the whloe number fo facial forms it appeared to decresae in the order of ovoied(41.8%), square(32.7%), square+tapered(20.5%), and tapered form(5%)(P<0.01). In a profile form, the most numerous were men with A form and women with B. Among the whole participants the most numerous were persons with B form and persons with A and C form were next in oder of numbers(P<0.01). 4. In discoloration of teeth, the most numerous were persons who have no discoloration. 5. In the esthetic recovery of anterior prosthesis the color matching of proximal teeth was not correct, but the outline of proximal teeth was to be reproduced correctly. 6. In the diastema of teeth, the number of persons who have no diastema was higher than that of persons who have a disatema(P<0.01) Among the persons who have diastema the most numerous were persons who have a diastema, and next were 2, 4, 3 and 5 diastemas in order. 7. In a meeting point of the midline of the body and the tooth the number of person hanving a meeting point was higher than that of persons who did not fit each other(P<0.01). The bias direction of midline teeth appeared to be affected by chewing direction, prosthesis location, and posterior location. 8. The length and width of teeth in the tooth size were suitable(P<0.01). The number of persons who have central teeth longer than lateral teeth was high(P<0.0). 9. In the results of smile analysis, the line form connected with incisal edge of upper canine were parallel(P<0.01). When smile the location fo upper lips should be in accord with the central area of teeth(P<0.01) and lower lip should be atteched to the edge of anterior teeth in order to be esthetic. 10. Among the number of upper teeth we can see the most numerous were 8 teeth and next were 10, 6 and 12 in order.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.2
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• pp.156-163
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• 2014

In this paper, a compact circularly polarized metamaterial patch antenna using cross aperture-coupled feed is proposed. The CP antenna utilizes the -1 mode that is induced by the composit right-left handed(CRLH) transmission line. Since the -1 mode has the same properties with the $TM_{010}$ mode of the conventional patch antenna, the circular polarization(CP) can be realized. If two orthogonal modes are excited with $90^{\circ}$ phase difference, the CP property can be obtained. In order to obtain two orthogonal modes and $90^{\circ}$ phase difference, 4 mushroom structures having the shape of square are employed. The width and length of the cross aperture are optimized through the design algorithm. The fabricated antenna is based on RT/duroid5880 substrate and the total area of the 4 mushroom is $0.25{\lambda}_0{\times}0.25{\lambda}_0$. The center frequency of the LHCP(Left-Handed Circular Polarization) antenna is measured as 1.622 GHz and circular polarization bandwidth(3 dB) is measured as 3 MHz. The center frequency of the RHCP(Right-Handed Circular Polarization) antenna is measured as 1.609 GHz and circular polarization bandwidth (3 dB) is measured as 3 MHz, respectively. The measured radiation efficiency of LHCP antenna is 61.1 % and the measured radiation efficiency of RHCP antenna is 54.5 %.

• The Journal of Korean Academy of Prosthodontics
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• v.43 no.2
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• pp.191-203
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• 2005

Statement of problem. In Korea, the preliminary impression trays for dental and edentulous maxillae are manufactured on the base of the statistical value of Westerners. There had been less study on the dental and edentulous arches of Koreans. Purpose. The purpose of this study was to evaluate an average dental cast, preliminary impression trays, three-dimensional relation of dental and edentulous maxilla of Koreans Material and methods. The subjects for this study were 173 dental casts of maxilla (dental: 52, edentulous : 146) with ages $18\{\sim}60$ years old. Each of the master casts was measured 69 measuring points on the dental cast or maxilla, and 46 measuring points on the edentulous cast of maxilla with three-dimensional digital measuring machine. Each measuring points were analysed and were overlapped, that three dimensional dental graphic manufactured by CAD/CAM system. Results. 1. A standard of distribution to alveolar bone were width between left and right buccal border lines of the standard 3/4 line. The mean value of dental and edentulous casts were 67.27mm, 63.49mm respectively. 2. Morphological classification of dental casts were divided into three groups or V-shape, O-shape, U-shape, that proportion of distribution were 17%, 16%, 67%, respectively. Dimensional classification of the dental casts were divided into five groups of less than 63mm, 63 up to 65mm, 65 up to 67mm. 67 up to 69mm, more than 69mm, respectively. 3. Morphological classification of edentulous casts were divided into three groups or V-shape, O-shape, U-shape, that proportion of distribution were 18%, 17%, 65%, respectively Dimensional classification of the edentulous casts were divided into five groups of less than 57mm, 57 up to 61mm, 61 up to 65mm, 65 up to 69mm, more than 69mm, respectively. 4. Mean dental and edentulous cast of maxilla were overlapped, the proportion of bone resorption to alveolar bone is higher than that of palatal bone, its difference were higher anterior 2/4 area than posterior 3/4 area. Conclusion. It obtains information of preliminary impression trays for dental and edentulous maxilla of Koreans.

• Journal of Electrical Engineering and Technology
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• v.13 no.2
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• pp.936-942
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• 2018

The diagnostic multi-leaf collimator preventing unnecessary dose from entering into patients during the diagnostic examination was made in this study. The movement of the entire 50 leaves was embodied with the group of 25 ones thereof configured in a pair facing each other on the left and right of the median line. Dimensions of the length, width, and height of each shielding leaf were $5{\times}0.5{\times}0.5cm^3$ resulting in the maximum boost field of $10{\times}10cm^2$. The material of multi-leaf collimator had the excellence on the machinability with the use of the SKD-11 alloy tool steel having the high wear resistance against frequent movement, and it was devised to control both-side's shielding leaves by moving 2 motors unlike existing remedial multi-leaf collimator that use as many motors as the number of 50 shielding leaves. Thereafter, the transmission dose of leaves, cross-leaf leakage dose, and inter-leaf leakage dose were measured by the developed multi-leaf collimator attached to X-ray equipment. An ionization chamber was used to detect doses there from, and the comparative analysis was carried out by means of the radiographic film that was easy to detect the dose leakage in between each leaf. Results obtained from the test conducted in comparative analysis yielded approximately 98%, 96%, and 94% of shielding efficiency realized at each level of energy of 80kV, 100kV, and 120kV it was confirmed there was no dose leakage resulted from the varied level of irradiation energy. Thus the multi-leaf collimator to be developed based on this study is thought that it could fully reduce the unnecessary dose to patients in the diagnostic test and the shielding efficiency thereof is expected to be increasing if it is made in a miniaturized form with a way of increasing the thickness of each leaf later for an extended application to general diagnostic purposes.

• The Journal of the Petrological Society of Korea
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• v.23 no.1
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• pp.1-15
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• 2014

The Yeongam mineralized zone is located in the southwestern part of the Korean peninsula, including the Sangeun, Eunjeok and Baramjai mines. This zone is located in the northeastern part of the Mokpo-Haenam-Yeongam volcanic circular structure. The 13 sites of quartz vein with mineralization are developed in the Sangeun-Eunjeok-Baramjai area, within rhyolitic welded tuff, showing N-S or NNW trend with highly dipping to the west. The quartz veins occur as a single vein or a bundle of veins with width of 1-5 cm in each. The existence of faults parallel to the quartz veins indicates that the faulting occurred before and after the development of quartz veins and mineralization. The quartz veins and mineralized zone are displaced by NW-trending sinistral strike-slip faults. The extension of the Sangeun-Eunjeok mineralized belt is traced to the south, following a NNW-trending tectonic line, and the Au-Ag contents are analysed in the 12 sites of quartz veins. Contents of gold and silver are 12.3 g/t and 1,380.0 g/t in Eunjeok mine, 2.7 g/t, 23.5g in Sangeun mine, and <0.1 g/t, 5.7 g/t in Baramjai mine respectively. Therefore, a highly Ag-Au mineralized zone is not developed in the southern part of the studied area.

• Korean Journal of Environment and Ecology
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• v.26 no.4
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• pp.576-587
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• 2012

As being actual physiognomical vegetation on Daegwang sand dune in Imjado, the widest area is occupied by Pinus thunbergii community planted as windbreak forest whereas those communities such as Robinia pseudoacacia community, Elymus mollis community, Imperata cylindrica var. koenigii - Elymus mollis community, Carex kobomugi community, Ischaemum antephoroides community, Imperata cylindrica var. koenigii community, Phragmites communis community, Imperata cylindrica var. koenigii - Calamagrostis epigeios community occupy as band shape or patch. According to the result of the data collected and analyzed based on phytosociological method regarding 74 plots of survey area, the species composition of Daegwang sand dune vegetation is classified total 10 vegetation units comprises 7 communities and 5 groups. The 7 communities are classified into Pinus thunbergii community, Robinia pseudoacacia community, Rosa rugosa var. rugosa community, Ischaemum antephoroides community, Carex kobomugi community, Calamagrostis epigeios community, and the sub-units of Pinus thunbergii communities are classified into 3 groups of Pteridium aquilinum var. latiusculum group, Elymus mollis group, Pinus thunbergii topical group and the sub-units of Calamagrostis epigeios communities are classified into 2 groups of Phragmites communis group, Calamagrostis epigeios tipical group. The zonation of vegetation from coastal line indicated with the order of Elymus mollis - Carex kobomugi, Carex pumila, Lathyrus japonicus - Calystegia soldanella - Vitex rotundifolia, Lathyrus japonicus, Ischaemum antephoroides - Rosa rugosa var. rugosa. According to the analysis result of longitudinal section, it was found to be those types with wide width herbaceous vegetation of foredune, smooth slope of foredune, lots of dune ridges with no structure were less vulnerable to erosion of sand dune and advantageous to its recovery.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.39 no.9
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• pp.11-18
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• 2002

This paper presents a CPW phase shifter and shunt stub with air-bridge on a 10-${\mu}m$-thick oxidized porous silicon(OPS) substrate using surface micromachining. The line dimensions of the CPW phase shifter was designed with S-W-Sg = 100-30-400 ${\mu}m$. And the width and length of the air-bridge with "ㄷ“ shape were 100 ${\mu}m$ and 400-460-400 ${\mu}m$, respectively. In order to achieve low attenuation, stepped air-bridge CPW phase shift was proposed. The insertion loss of the stepped air-bridge CPW phase shift is more improved than that of no stepped air-bridge CPW phase shift. The measured phase characteristic of the fabricated CPW phase shifter is close to 180$^{\circ}$ over a very broad frequency range of 28 GHz. The measured working frequency of short-end series stub is 28.7 GHz and the return loss is - 20 dB. And the measured working frequency of short-end shunt stub is 28.9 GHz and the return loss is - 23 dB at midband. As a result, the pattering of stub in the center conductor of CPW lines can offer size reduction and lead to high density chip layouts.

• Journal of the Korean Chemical Society
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• v.55 no.4
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• pp.603-611
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• 2011

Ethoxylacetyl oxime ligands [HL, (1) and $H_2L^1$, (3)] react with copper(II) acetate monohydrate yield octahedral and square planar complexes, respectively. The complexes have been postulated due to elemental analyses, IR, UVVis. spectra, magnetic susceptibility, conductivity and ESR spectra. Molar conductance of the complexes in DMF indicates a non-ionic character. The ESR spectra of [$(L)_2Cu(H_2O)_2$], (2) complex at room temperature and 77K are characteristic of an axial symmetry ($d_{x2-y2}$) with covalent bond character and have a large line width typical of dipolar interactions. However, [$(L^1)Cu$], (4) complex in the solid state showed spectra of marked broadening and loss of hyperfine splitting confirming spinexchange interactions between the copper(II) sites. The spectrum of the doped copper(II) complex at room temperature showed super-hyperfine splitting from coordinated nitrogen atoms and it has an axial type ($d_{x2-y2}$) with covalent bond character and an essentially square-planar arrangement around the copper(II) ion. The spectrum of [$(L^1)Cu$], (4) in frozen methanol at 77K was characteristic of the triplet state of a dimer species and the distance found between the two copper(II) centers was calculated and is equal to 4.8 ${\AA}$.