• Korean Journal of Optics and Photonics
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• v.10 no.6
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• pp.500-506
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• 1999

We designed and fabricated a bidirectional optical transceiver module for low cost access network. An integrated chip forming a pin-PD on an 1.3 urn FP-LD was assembled by flip-chip bonding on a Si optical bench, a single mode fiber with an angled end facet was aligned passively with the integrated chip on V-groove of Si-optical bench. Gaussian beam theory was applied to evaluate the coupling coefficients as a function of some parameters such as alignment distance, angle of fiber end facet, vertical alignment error. The theory is also used to search the bottle-neck between transmittance and receiving coupling efficiency in the bi-directional optical system. Tn this paper, we confirmed that reduction of coupling efficiency by the vertical alignment error between laser beam and fiber core axis can be compensated by controlling the fiber facet angle. In the fabrication of sub-module, a'||'&'||' we made such that the fiber facet have a corn shape with an angled facet only core part, the reflection of transmitted laser beam from the fiber facet could be minimized below -35 dE in alignment distance of 2: 30 /J.m. In the same condition, transmitted output power of -12.1 dEm and responsivity of 0.2. AIW were obtained.

• Current Research on Agriculture and Life Sciences
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• v.22
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• pp.41-48
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• 2004

This study is performed in order to provide the basic information needed for the development of cutting blade for combine. By comparing the developed cutting blade of which were made groove of the surface with the common cutting blade. Friction force and cutting resistance by the cutter bar speed ratio and moisture content of rice stalk were shown as follows: 1. The friction force of the developed cutting blade is shown at the average value $0.12kg{\cdot}m$ as 25% lower than one of the common blade at the average value $0.16kg{\cdot}m$. 2. The cutting resistance of the developed cutting blade is shown as respectively 12%, 15% and 20% lower than one of the common blade at the moisture content of rice stalk of 14.2%, 55.3% and 84.2%. 3. The cutting resistance of cutting blade by two different driving types is shown that the one by double driving type is $0.2kg{\cdot}m$, and the one by single driving type is $0.24kg{\cdot}m$. 4. Optimum cutter bar speed ratio of cutting blade is shown as different according to the moisture content of rice stalk.

• Journal of Korean Ophthalmic Optics Society
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• v.18 no.3
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• pp.231-239
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• 2013

Purpose: To design and fabricate the auto pattern maker for the development. Methods: we got the necessary data, needed in design, by using CAD. Based on the these data, we fabricated the trial product for the development of the auto pattern maker. Results: The auto pattern maker were composed with combinations of many elements; pattern making assembly, control panel, frame attachment and prober unit. The pattern making assembly was comprised of the cutter, the pattern holder, pattern remover and silence cover which could minimize the sound during the cutting process. The control panel was designed to be connected and operated with the main printed circuit board. The prober could get the eye shape data by scanning of 1.8 degrees around the groove of the frame through the encoding data according to the address. After starting, scanning was carried out in two passes, i.e. one right-handed and one left-handed. Communication connector could send the eye shape data from auto pattern maker to outer system with the RS232C transmission system. By using the one-way analysis of variance, we got the error rate of cut pattern size for ${\Phi}22mm$, ${\Phi}55mm$ and ${\Phi}62mm$. Because F-value was 0.510 and p-value was 0.601, no statistically significant differences were found. Also, the mean cutting error of the auto pattern maker was 0.0274 mm. Conclusions: we could succeed in making the trial product by applying it to the development of the auto pattern maker. The role of this auto pattern maker is to find a exact required size of lens to fit the frame by measuring the frame. The acquired data are transferred to outer system for grinding and finishing with patternless process. Also, the trial product can produce pattern to fit the frame. Therefore, it was confidently expected that the optometrists could handily produce pattern to fit the frame with this trial product and dispense the ophthalmic lens because of its efficiency and convenience compared to the past.

• Journal of Korean Tunnelling and Underground Space Association
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• v.19 no.6
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• pp.1059-1075
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• 2017

The objective of this study was to evaluate the freezing and thawing resistance of the existing drainage system for leakage treatment of underground concrete structures operating in cold regions. The freezing and thawing test was conducted on 4 types of drainage system specimens to evaluate the freezing and thawing resistance of the drainage system. The freezing and thawing resistance was evaluated on 4 types of Hotty-gel, as a waterproofing material, connection methods and on two methods to fix the drainage board with Hotty-gel on the surface of cement concrete specimen. One cycle of the freeze-thaw testing was 48 hours (24 hours of freezing and 24 hours of thawing), and the temperatures of freezing and thawing were at $-18^{\circ}C$ and $10^{\circ}C$, respectively. Among the 4 types of Hotty-gel connection methods, leakage occurred after 28 cycles (8 weeks) of freeze-thawing only in the Hotty-gel connection method with the 'V' groove applied to the corner of the drainage board. No leakage occurred in the 3 types of Hotty-gel connection methods. In two fixing methods, leakage occurred in the method of fixing the drainage board on the cement concrete specimen using the washer, screw and plastic wall plug. Leakage occurred at one point after 10 cycles (3 weeks) of freezing and thawing. After 28 cycles (8 weeks) of freezing and thawing, leakage point increased to 5 points. As time passed, the leak point was not increased, but the amount of leakage was increased at each leak point. The Hotty-gel connection method with cross-sectional diagonal shape was evaluated to be the highest in the production efficiency considering the production time and manufacturing method of the Hotty-gel connection shape. In the construction efficiency considering the construction time and construction method, the fixing method of air nailer, fixed nail and washer was superior to that of the washer, screw and plastic wall plug.

• The Korean Journal of Zoology
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• v.39 no.4
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• pp.400-409
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• 1996

A study on the ultrastructural changes In the epithellum of the vas deferens by season was conducted for the spdng and summer specimens of a slug Incilarfa fruhstoiferl. The vas deferens of the spdng spedmen was muscular tube about 0.4mm in diameter. Its lumen was divided into three flat grooves and the each groove was subdivided into two subbranches. The luminal epithellal celis of the Vas deferens which were irregular In shape showed strong methylenophilla in a double stain of methylene blue and basic fuchsln. The lumen of the vas deferens was filled with components strongly stained by methylene blue. The circular muscle layers surrounding the luminal epithellum of the vas deferens contained numerous granules arranged at regular intervals. The vas deferens of the summer specimen also was a thick muscular tube showing 0.4 mm in diameter. Its lumen was divided into four grooves but, the each of the grooves was not subdivided to form certain branclees unlikely to the spdng spedmen. The lining epfthelium of the lumen was consisted of simple ciliated columnar cells, irregular columnar cells and conical cells. The histological features were quiet different from those of the spring spedmen which showed irregular cell arrangement. According to electron microscopy the epithelium of the vas deferens in the spring specimen was composed of irregular columnar cells which had irregular shaped nuclei. The nuclei of the epitheilal cells were relatively large in comparison to their cytoplasm. The overall electric density of the cytoplasm was relatively high. The lumen of the vas deferens in the summer specimen was lined by a epfthelium with tail ciliated columnar cells and irregular cells. The unclei of the epithellal cells were long ellipsoid or irregular in shape. Both of the cytoplasm and the nuclei were showed low electric density. in consideration with the observable cell organelles were only ndoplasmic reticulum, lysosomes and microtutules, the cell organelles were poorly developed. The apical surfaces of the epithelial cells possessed brush borders with numerous microvilli and cilia with 9+2 arrangement of microtubules. The circular muscle layers surrounding the epithelium are usually thick and the degree of development of the circular muscle layers seems to be even in the both of the spring and summer specimens.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.30 no.3
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• pp.111-120
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• 2012

This study regards a series of achievement on Wonlim(Garden) Cultural Properties Excavation Project, led by field of landscape architecture. It will mainly describe excavation results of Gwiam(龜巖: Turtle rock) and historical value of it in terms of Nakseojae(樂書齋) restoration in Bogil-do Yun,Seondo Wonlim(Scenic Sites, No.34). Gwiam(Turtle rock) was found 14.6m apart from the north of Nakseojae, and it covered with 10~15m topsoil tilted toward Nakseojae, The size of Gwiam, which was Granite, was 360cm length, 270cm width, 95cm high. The Edge of Gwiam's North west part was of triangular shape forming Turtle head. The back of the Turtle head was form of Tortoise-shell because of wide backboard with both side groove. The southeast part of Gwiam projected was Turtle's tail. This Granite was obvious Turtle shape artificially made, and there are less likely to relocate from place to place. This Turtle-shaped Gwiam is important landmark for Nakseojae, which is one of the four spiritual creatures written in Bogildoji(甫吉島識) and Gosanyugo(孤山遺稿) by Yunwi. According to Bogildoji, it is estimated that Gwiam were on the axis with Soeunbyung(小隱屛), Nakseojae and was buried when Yiguan(Gosan's grandson) reconstructed a building. Also, it was place for enjoying the moon. But, Even after three times excavation in Nakseojae, there was no way to identify further information regarding Gwiam, so it was a matter of mystification. As a result of this study, Gwiam is laid bare to light in at least 260 years, so it is good example for boosting importance of landscape architecture field and restoring Nakseojae. Furthermore, firm base-soil was discovered in 135m high Rock Mass below, so natural ground of Nakseojae can be estimated by this basis. To be conclusion, Preservation Process for Gwiam and Estimation Space through interpretation of four spiritual creatures(四靈) in Gosan's Poetry should be continue.

• Restorative Dentistry and Endodontics
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• v.28 no.1
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• pp.89-99
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• 2003

The purpose of this study was to investigate the bonding of resin- based root canal sealer, AH26 when the sealer was applied as a thin layer between dentine and gutta-percha surface. In this study forty non-caries extracted human molars and resin-based root canal sealer(AH 26, DeTrey/Dentsply, Germany) were used. Disks of gutta-percha, 6mm in diameter.6mm thick (Diadent/Dentsply, Korea) for thermoplastic obturation were used and dentin surfaces were treated with 2% NaOCl(Group 1) or 2%NaOCl+17% EDTA(Group 3). Disks of gutta-Percha, 6mm in diameter.6mm thick (Diadent/Dentsply, Korea) for conventional obturation were used and dentin surface were treated with 2% NaOCl(Group 2) or 2%NaOCl+17% EDTA(Group 4). Enamel was removed by a horizontal section 1mm below the deepest portion of the central occlusal groove by using a watercooled low speed diamond saw. A second horizontal section was done around cementoenamel junction. Exposed dentin surface was cut to approximately $8{\times}8{\;}mm$ rectangular shape and was ground against 320, 400, 600 grade silicon carbide abrasive paper serially. After grinding, the dentine surface were soaked in a solution of 2% NaOCl for 30 minutes and twenty of specimens were treated with 17% EDTA solution for 1 minute. The treated specimens were washed and dried, Root canal sealer, AH26 was prepared according to the manufacture's instructions The Gutta-percha and dentin surface were coated with a thin layer of the freshly mixed seal or. The specimens were left overnight at room temperature. After their initial set, they were transferred to an incubator at $37$^{\circ}C$ for 72 h. After 72 hours, resin blocks were made. The resin block was serially sectioned vertically into stick of $1{\cdot}1mm$. Twenty sticks were prepared from each group. After that, tensile bond strength f3r each stick was measured with Microtensile Tester Failure patterns of the specimens at the interface between gutta-percha and dentin were observed under the SEM(x1000) and Stereomicroscope (LEICA M42O, Meyer Inst., TX U.S.A) at 1.25 x25 magnification. The results were statistically analysed by using a One-way ANOVA and Tukey's test. The results were as follows; 1. Tensile bond strengths($mean{\pm}SD$) were expressed with ascending order as follows: Group 1, $3.09{\pm}$ 1.05Mpa : Group 2, $6.23{\pm}1.16MPa$ : Group 3, $7.12{\pm}1.07MPa$ : Group 4, $10.32{\pm}2.06MPa$. 2. Tensile bond strengths of the group 2 and 4 used disks of gutta-percha for conventional obturation were significantly higher than that of the group 1 and 3 used fir thermoplastic obturation. (p < 0.05). 3. Tensile bond strengths of the group 3 and 4 treated with 2% NaOC1+17% EDTA were significantly higher than that of the group 1 and 2 treated with 2% NaOCl. (p < 0.05). 4. In analysis of failure patterns at the interface between sealer and gutta-percha, there were observed 49 (61%)cases of adhesive failure patterns and 31 (39%) cases of mixed failures patterns.