• Restorative Dentistry and Endodontics
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• v.2 no.1
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• pp.27-31
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• 1976

Eighty mandibular first premolars were injected with china ink, decalcified, cleared and used in an in vitro study to determine the number of root canals, the frequency and location of lateral canals, the location of apical foramens, the frequency of apical deltas, and the curvature of root canals. The results were as follows: 1. Most of the teeth demonstrated single canal, but 22.5% of the teeth were found to have bifurcated or trifurcated canals. 2. Of the 99 canals studied, 37.3% of the canals were found to have lateral canals and these ramifications were usually located in the apical third of the root. 3. 27 apical foramens were located directly on the root apex and 66 foramens laterally. 4. 6 canals showed mesial curvature, 49 canals distal curvature, 11 canals buccal curvature, and 25 canals lingual curvature.

• Restorative Dentistry and Endodontics
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• v.2 no.1
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• pp.32-37
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• 1976

The author has studied comparatively the sealing quality of polycarboxylate cement, one of the newest dental cement systems, and zinc oxide eugenol cement by means of penetration of 2% methylene blue solution through the root apex of human teeth in 72 cases as time elapsed. Followings are the results obtained from this study. 1) In all groups, there was no increase in penetration related to increased time of immersion in the dye. 2) In polycarboxylate cement groups, there was a significant difference in depth of dye penetration of each tooth, but in zinc oxide eugenol cement group, there was a slight difference. 3) The depth of dye penetration of zinc oxide eugenol cement group is slightly lower than that of poly carboxylate cement groups. 4) In polycarboxylate cement groups, Carbolit cement group showed comparatively lower grade of dye penetration than Carbo cement group.

• Restorative Dentistry and Endodontics
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• v.18 no.2
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• pp.463-468
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• 1993

The purpose of this study was to evaluate the effects of Vitapex on the periapical lesions. Thirteen single-rooted teeth from ten patients who visited the SNU hospital were endodontically treated with Vitapex and Gutta percha cone, and radiographically and clinically evaluated for a period of 1 to 6 months. The results were as follows : 1. The loss of clinical symtoms was observed in all 13 teeth. 2. The reduction of size of periapical lesions in radiographs was observed in 10 teeth. The periapical lesions of remaining 3 teeth also look better in the radiographs. 3. All 13 teeth showed the reduction of radiolucency. 4. The gradual resorption of Vitapex over the root apex was observed.

• Restorative Dentistry and Endodontics
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• v.8 no.1
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• pp.155-159
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• 1982

The author has studied comparatively the sealing quality of conventional Z.O.E. cement, chloropercha and FR cement by means of penetration of 2% methylene blue solution through the apex of human teeth in 112 cases as the time elapsed. The results were as follows; 1. All the specimen, of which dye immersion time is three days, showed dye penetration of low degree unrelated to the kinds of root canal cement and the degree of dye penetration was increased as the time elapsed. 2. Of all the experimental group, the Z.O.E. cement group showed the lowest degree of dye penetration and the FR filling group showed the highest degree of dye penetration. 3. The degree of dye penetration of FR cement group was higher than that of the Z.O.E. cement group but lower than that of the chloropercha group.

• Restorative Dentistry and Endodontics
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• v.8 no.1
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• pp.139-145
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• 1982

Eighty four human maxillary second premolars were injected with china. ink, decalcified, cleared and used in study, in vitro, to determine the number of root canals, the frequency and location of lateral canals, the frequency and location of transverse ansatomoses, the curvature of root canals, the location of apical foramens, and the frequency of apical deltas. The results were as follows: 1. Most of the teeth demonstrated one canals, but the only tooth was found to have two canal. 2. Of the 101 canals studied, 85.1% of the canals were found to have lateral canals and these ramifications were usually located in the apical third of the root. 3. Of the two root canals in one root, 25.4% of the canals were found to have transverse anastomoses and were usually located in the middle third of the root 4. 33.3% of apical foramens were located directly on the root apex and 66.7% of them laterally, and 46.5% of canals showed distal curvature.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.2
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• pp.84.2-84.2
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• 2011

A numerical simulation study of the solar coronal plasma reveals that a ballooning instability can develop in the course of flux rope merging. When magnetic field lines from different flux ropes reconnect, a new field line connecting farther footpoints is generated. Since the field line length abruptly increases, the field line expands outward. If the plasma beta is low, this expansion takes place more or less evenly over the whole field line. If, on the other hand, the plasma beta is high enough somewhere in this field line, the outward expansion is not even, but is localized as in a bulging balloon. This ballooning section of the magnetic field penetrates out of the overlying field, and eventually the originally underlying field and the overlying field come to interchange their apex positions. This process may explain how a field structure that has stably been confined by an overlying field can occasionally show a localized eruptive behavior.

• 한국정보디스플레이학회:학술대회논문집
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• 2000.01a
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• pp.49-50
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• 2000

5.2" microtip field emission displays (FEDs) with high voltage applications are fabricated. Nano-structural analysis on microtips is performed for the reliable operation of FEDs. Chemical compositions on the apex of microtips are fully analyzed. A charging mechanism on spacers is simulated and experimentally confirmed with micro-images. A gas-aging mechanism is also studied with integration step of FEDs. The brightness of more than 300 $cd/m^2$ is achieved. In addition, as a new concept, 9" color carbon nanotube FEDs (CNT-FEDs) are introduced using well-aligned carbon nanotubes on glass substrates by paste squeeze and surface treatment techniques. A number of carbon nanotubes, $5-10/{\mu}m2$, are uniformly distributed over a large area. The turn-on fields of 1 $V/{\mu}m$ and field emission currents of 1.5 mA at 3 $V/{\mu}m$ are acquired. Different mechanisms between microtip FEDs and CNT-FEDs are discussed.

• The Journal of the Korean dental association
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• v.11 no.4
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• pp.267-269
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• 1973

The authors had a case report of radicular cyst on left maxillary lateral incisor root apex region. Left maxillary central incisor, lateral incisor, canine was extracted, cyst was curetted. The prosthodontic treatment was good clinical results applying fixed bridge and the gum plate of resin in the case of massive alveolar bone loss.

• The Korean Journal of Malacology
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• v.3 no.1
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• pp.35-43
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• 1987

Morphological variations of six Korean and one Japanese populations of Parafossarulus manchouricus were observed. Mean length of shell was 9.36mm(n=376), and mean width was 8.0mm. Average aperture length and width were 4.72 and 3.78mm, respectively. Number of whorl ranged from 3.5 to 5.25(at most 4.5)in all popuiations . Yangsoori population had no spiral line or spiral keel, but ther populations had spiral lines. Number of spiral line on their penultimate shorls ranged 4 to 14.The lips of aperture were generally thickened, except in some Chongpyong, Haman and Fukuoka populations. The most of shell was eroded in only apex part and/ or in othker sculpture, especially Yangsoori population was heavily eroded.

• Proceedings of the Botanical Society of Korea Conference
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• 1996.07a
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• pp.4-9
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• 1996

The majority of plants sense environmental signals, such as day length or temperature, to select their transition timing from vegetative growth t flowering. Here, we report the identification of a regulatory gene, OsMADS1, that controls the photoperiod sensitivity of flowering time. Constitutive expression of OsMADS1 in a long-day flowering plant, Nicotiana sylvestris, resulted in flowering in both short-day long-day conditions. Similarly, ectopic expression of the gene in a short-day flowering plant, N. tabacum cv. Maryland Mammoth, also induced flowering regardless of the day length. The transition time was dependent on the level of the OsMADS1 transcript in transgenic plants. These suggest that OsMADS1 is a key regulatory factor that determines the transition from shoot apex to floral meristem and that it can be used for controlling flowering time in a variety of plant species.