• Journal of Aquaculture
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• v.8 no.3
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• pp.231-240
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• 1995

This study was conducted to examine early gonadogenesis by using a histological method for the appearance of primordial germ cells (PGCs), protrude of genital ridge, and formation of primitive gonads in diploid and triploid mud loach, Misgurnus mizolepis. The pattern of early gonadogenesis including appearance of PGCs, formation of genital ridge, and development of primitive gonad in both diploid and triploid were not different histologically. Characteristics of PGCs of triploid were also the same as those of diploid. However, gonadal length of diploid was significantly longer than that of triploid (P<0.05).

• Korean Journal of Fisheries and Aquatic Sciences
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• v.22 no.6
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• pp.415-423
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• 1990

In a laboratory model the response of the boundary layer flow over topography is studied in a rotating sliced cylinder by employing the source-sink analogy with Ekman layer dynamics. The boundary layer flow is produced by two different fluid. In the first experiment homogeneous fluid is used both for the source and the working fluid of the container. In the second experiment a denser fluid is used for the source with the same working fluid. For the homogeneous western boundary layer flow both the northward and the southward flow were affected by the topography(ridge) to produce a cyclonic motion near the ridge. When woughward moving heavy boundary flow of slower speed and the northward moving faster flow were present at the same time, the splitting of southward flow and the separating of the northward flow were observed with a cyclonic motion at the ridge. The most important factor that influence production of the cyclonic motion has been turned out to be the presence of the topography in the western boundary layer. In particular the role of the southward moving heavy flow over the interior flow pattern was found to be very significant.

• The Journal of Korean Academy of Prosthodontics
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• v.30 no.4
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• pp.541-564
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• 1992

The purpose of this experiment was to study the effect of implantation of the dense hydroxyapatite (HA) granules$(Apaceram^{(R)})$ in the fresh extraction sockets on the residual ridge resorption in normal and induced diabetic rabbits. Sixty-four white rabbits, weighing 3.0kg, were utilized in this study and they were divided into four group : group 1-sixteen normal rabbits without filling HA granules, group 2-sixteen normal rabbits with filling HA granules, group 3-sixteen diabetic rabbits without filling HA granules, group 4-sixteen diabetic rabbits with filling HA granules. HA granules were filled immediately after extraction in the extraction sockets of the mandibular left 1st, 2nd, and 3rd molar in group 2 and 4, and no HA granules were filled in group 1 and 3. The calculation of residual ridge resoption was done at 4th week, 8th week, 12th week, and 16th week after surgery, and histologic examination was performed to study healing process at 2nd week, 4th week, 8th week, and 16th week after surgery. The results were as follows : 1. The amount of residual ridge resorption was largest in group 3, and smallest in group 2 in every interval. There was no statistically significant difference between group 1 and 4. 2. In all groups, the amount of residual ridge resorption was high until 4th week after surgery, but the rate of residual ridge resolution slowly decreased after 4th week 3. There was more active healing process in group 1 and 2 than in group 2 and 4. 4. According to filling of HA granules, there was no difference in the amount of new bone formation, but direct contact could be observed between newly formed bone and HA granules in group 2 and 4. 5. Group 1 and 3 showed marked bone resorption and adipose marrow from 8th-16th week after surgery, but group 2 and 4 did not show maeked bone resolution, and showed fibrous tissue and a little adipose tissue among trabeculae from 8th week.

• FLOWER RESEARCH JOURNAL
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• v.16 no.4
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• pp.255-259
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• 2008

This study was conducted to investigate the effect of ridge height (10 cm, 20 cm, 30 cm, and 40 cm) on the soil physical property, the growth and flowering characteristics of Gypsophila paniculata (cv 'Bristol Fairy') in the subalpine area. As ridge height got higher, the daily soil temperature, the soil moisture content, soil hardness, bulk density, and solid phase ratio were decreased, but porosity ratio was a little increased. In summer and autumn cultivation the blooming of ridge height 30 cm and 40 cm was slightly delayed, but their root activity, cut flower width, and yield were better than those of 10 to 20 cm ridges. And the mortality ratio of plants, rosette formation rate, and nonpaniculata inflorescence rate became lower.

• Journal of Periodontal and Implant Science
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• v.29 no.3
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• pp.469-484
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• 1999

The purpose of this study was to evaluate new bone formation following guided bone regeneration by resorbable and nonresorbable membrane. Six adult mongrel dogs were used. The first, second, third, fourth premolars in the mandible of each dog were extracted. Two months after tooth extraction, a buccal dehiscence defect was surgically created on each edentulous area. The experimental sites were divided into three groups according to the treatment modalities ; Group I-a: surgical treatment only ; Group I -b: allogenic decalcified freezed dried bone grafting ; Group II-a : e- PTFE membrane placement only ; Group II-b : allogenic decalcified freezed dried bone grafting and e-PTFE membrane placement ; Group III-a : Vicryl(R) mesh placement only ; Group III-b : allogenic decalcified freezed dried bone grafting and Vicryl(R) mesh placement . The animals were sacrificed at 8 weeks after operation and the specimens were prepared for histologic and histometric examination. The results were as follows : Clinically, all defect sites were healed without exposure of barrier membrane after the eight weeks. In Group I-a, dense connective tissues were impinged in the bony defect area. Well vascularized and fibrous bone marrow indicated that bone formation was still taking place was found. In Group I-b, in areas closer to the periphery, lamellation of the newly formed bone would found. In Group II-a, beneath the e-PTFE membrane a dense layer of connective tissue covering the most external portions of the regenerated tissue was seen. The new bone surfaces were lined with osteoid and osteoblast. In Group II-b, a dense layer of connective tissue covering the most external portions of the regenerated tissue was observed beneath the e-PTFE membrane. A notable amount of alveolar ridge regeneration was seen with new rigdes with well-contoured form. In Group III-a, the new bone surface were lined with osteoid and osteoblast, indicating active bone formation. A clear demarcation could not be noted between the host bone and new bone. In Group III-b, a notable amount of alveolar ridge regeneration was seen with new ridges assuming wellcontoured form. In areas closer to the periphery, lamellation of the newly formed bone would found. As histometric examination, the amount of bone formation was gained from $12.8mm^2$ to $26.3mm^2$. It was significantly greater in group II-b and group III-b compared to other groups(p<0.05) . These results suggest that Vicryl(R) mesh after DFDB grafting used in guided bone regeneration could create and sustain sufficient space for new bone formation.

• Journal of the Speleological Society of Korea
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• v.36 no.37
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• pp.103-113
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• 1994

Slope soil formation and its attributes in southwestern Wisconsin are potentially important due to its origin, landscape position and karstic backgrounds (Oh, 1990). Since French explorers and missionaries reached in southwestern Wisconsin in the 1830's, the loess mantled karst upland surfaces, consisted of forests: timberland, oak openings, and prairie, had been cultivated. At present, nearly 90% of the ridge land is in farms. Karst soils are usually reddish clayey features (Oh and Day, 1989).(omitted)

• The Bulletin of The Korean Astronomical Society
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• v.45 no.1
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• pp.51.1-51.1
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• 2020

The Rosette Nebula is the most actively star-forming region in the Monoceros OB2 association. This region hosts more than three stellar groups, including the most populous group NGC 2244 at the center of the region and the smaller stellar groups around the border of the H II bubble. To trace their formation process, we investigate the kinematic properties of these groups using the Gaia astrometric data and high-resolution spectra taken from observation with Hectochelle on MMT. The proper motions of stars in NGC 2244 show a pattern of radial expansion. The signature of cluster rotation is also detected from their radial velocities. On the other hand, the small groups appear to be physically associated with some clouds at the ridge of the H II region. Among them, the group near the eastern pillar-like gas structure shows the signature of feedback-driven star formation. In this presentation, we will further discuss the formation process and dynamical evolution of the stellar groups in the Rosette Nebula, based on the observation and results of N-body simulations.

• Ocean and Polar Research
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• v.42 no.1
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• pp.49-61
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• 2020

We analyzed the morphological characteristics of OCC (Ocean Core Complexes) in the middle part of the Central Indian Ridge (MCIR) using high-resolution geophysical data recorded on the Deep-Tow SideScan Sonar IMI-30 system. In terms of slope-gradient variations calculated from the high-resolution bathymetry data, the normal faults formed by seafloor spreading were associated generally with slopes > 30° and resulted in high backscatter intensities, which reflect more topographic effects than acoustic medium variation. However, the areas associated with gentle slopes < 10° tend to show the backscatter intensities reflecting the acoustic characteristic of the medium. We show that the detachment faults exposing the OCCs were initiated with high-angle normal faults (58°) exhibiting outward and inward dips of a breakaway zone. In order to examine the spatial distribution of OCC structures, we characterized the transition from magmatic-dominant seafloor with abyssal hills to tectonic-dominant seafloor with OCC using the down-slope direction variation. The slope direction of the seafloor generally tends to be perpendicular to the ridge azimuth in the magmatic-dominant zone, whereas it becomes parallel to the given ridge azimuth near the OCC structures. Therefore, this spatial change of seafloor slope directions indicates that the formation of OCC structures is causally associated with the tectonic-dominant spreading rather than magmatic extension. These results also suggest that the topographical characteristics of seafloor spreading and OCC structures can be distinguished using high-resolution geophysical data. Thus, we propose that the high-resolution bathymetry and backscatter intensity data can help select potential areas of exploitation of hydrothermal deposits in MCIR effectively.

• Journal of Periodontal and Implant Science
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• v.40 no.5
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• pp.227-231
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• 2010

Purpose: The healing process following tooth extraction apparently results in a pronounced resorption of the alveolar ridge. As a result, the width of alveolar ridge is reduced and severe alveolar bone resorption occurs. The purpose of this experiment is to clinically and histologically evaluate the results of using horse-derived bone mineral for socket preservation. Methods: The study comprised 4 patients who were scheduled for extraction as a consequence of severe chronic periodontitis or apical lesion. The extraction was followed by socket preservation using horse-derived bone minerals. Clinical parameters included buccal-palatal width, mid-buccal crest height, and mid-palatal crest height. A histologic examination was conducted. Results: The surgical sites healed uneventfully. The mean ridge width was $7.75{\pm}2.75\;mm$ at baseline and $7.00{\pm}2.45\;mm$ at 6 months. The ridge width exhibited no significant difference between baseline and 6 months. The mean buccal crest height at baseline was $7.5{\pm}5.20\;mm$, and at 6 months, $3.50{\pm}0.58\;mm$. The mean palatal crest height at baseline was $7.75{\pm}3.10\;mm$, and at 6 months, $5.00{\pm}0.82\;mm$. There were no significant differences between baseline and 6 months regarding buccal and palatal crest heights. The amount of newly formed bone was $9.88{\pm}2.90%$, the amount of graft particles was $42.62{\pm}6.57%$, and the amount of soft tissue was $47.50{\pm}9.28%$. Conclusions: Socket preservation using horse-derived bone mineral can effectively maintain ridge dimensions following tooth extraction and can promote new bone formation through osteoconductive activities.

• Journal of Periodontal and Implant Science
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• v.37 no.2
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• pp.237-249
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• 2007

This study was performed to evaluate the effect of membrane exposure on new bone formation when guided bone regeneration with perforated titanium membrane on atrophic alveolar ridge. The present study attempted to establish a GBR model for four adult beagle dog premolar. Intra-marrow penetration defects were created on the alveolar ridge(twelve weeks after extraction) on the mandibular premolar teeth in the beagle dogs. Space providing perforated titanium membrane with various graft material were implanted to provide for GBR. The graft material were demineralized bovine bone(DBB), Irradiated cancellous bone(ICB) and demineralized human bone powder(DFDB). The gingival flap were advanced to cover the membranes and sutured. Seven sites experienced wound failure within 2-3weeks postsurgery resulting in membrane exposure. The animals were euthanized at 4 weeks postsurgery for histologic and histometric analysis. The results of this study were as follows: 1. There was little new bone formation at 4 weeks postsurgery. irrespectively of membrane exposure. 2. There was significant relationship between membrane exposure and bone graft resorption(P<0.05), but no relation between membrane exposure and infiltrated connective tissue. 3. There was much bone graft resorption on DFDB than ICB and DBB. 4. The less exposure was on the perforated titanium membrane, the more dense infiltrated connective tissue was filled under the membrane when grafted with ICB and DBB. but there was no relationship between the rate of membrane exposure and the percentage of infiltrated connective tissue area and no relationship between the percentage of the area in the infiltrated connective tissue and in the residual bone graft. Within the above results, bone formation may be inhibited when membrane was exposed and ICB and DBB were more effective than DFDB as a bone graft material when guided bone regeneration.