• Journal of Korean Society of Coastal and Ocean Engineers
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• v.32 no.1
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• pp.55-68
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• 2020

In order to investigate the hydraulic characteristics of a boundary layer streaming over the beach cusps appeared in swells prevailing mild seas, we numerically simulated the shoaling process of Edge waves over the beach cusp. Synchronous Edge waves known to sustain the beach cusps could successfully be duplicated by generating two obliquely colliding Edge waves in front of beach cusps. The amplitude A_B and length L_B of Beach Cusp were elected to be 1.25 m and 18 m, respectively based on the measured data along the Mang-Bang beach. Numerical results show that boundary layer streaming was formed at every phase of shoaling process without exception, and the maximum boundary layer streaming was observed to occur at the crest of sand bar. In RUN 1 where the shortest waves were deployed, the maximum boundary layer streaming was observed to be around 0.32 m/s, which far exceeds the amplitude of free stream by two times. It is also noted that the maximum boundary layer streaming mentioned above greatly differs from the analytical solution by Longuet-Higgins (1957) based on wave Reynolds stress. In doing so, we also identify the recovery procedure of natural beaches in swells prevailing mild seas, which can be summarized such as: as the infra-gravity waves formed in swells by the resonance wave-wave interaction arrives near the breaking line, the sediments ascending near the free surface by the Phase II waves orbital motion were carried toward the pinnacle of foreshore by the shoreward flow commenced at the steep front of breaking waves, and were deposited near the pinnacle of foreshore due to the infiltration.

• Archives of Plastic Surgery
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• v.36 no.5
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• pp.531-537
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• 2009

Purpose: Alveolar bone grafting has become an essential process in the treatmemt of alveolar cleft patient for stabilization of the maxillary arch, elimination of oronasal fistula, the reconstruction of the soft tissue nasal base support, and creation of bony support for tooth eruption for implant. The use of Autologous iliac cancellous bone is preferable because of the adequate quantity and high osteoinductive potential. However, even with iliac bone, insufficient osteoregeneration and absorption occur due to several factors such as the patient's age, cleft width, functional stress, and others. In order to increase osteoregeneration where the iliac bone is placed, the present study is associated with bone marrow aspirate (BMA). The experimental study evaluated the efficacy of osteoregeneration in normal cleft rabbits when alveolar bone grafting was performed with autologous iliac corticocancellous bone. Methods: Twenty - four New Zealand White rabbits were divided randomly into 2 groups (BMA, control). All animals underwent harvesting of corticocancellous bone graft from the right posterior iliac crest via standard surgical technique. $1m{\ell}$ of BMA were obtained by scraping the needle and aspirate with $10m{\ell}$ syringe from the contralateral iliac bone wall. The muco - periosteal flap on the palate was elevated. A mixture of Equal bone's volumes with BMA and saline as its control was inserted into the cleft. Animals were sacrificed at 2, 4, and 8 weeks and maxilla was harvested for dental peri - apical X-ray, bone matrix density (BMD),and histologic analysis. Result: BMD of regenerated bone to the cleft in the rabbits was higher than that of the control rabbits. X-ray, histologic analysis showed that increased osteoregeneration and low absorption rate were observed in the BMA group. Conclusion: Our experimental study showed BMA enhanced the osteoregeneration and survival rate of alveolar bone grafting. BMA is easy to extract & cost - time effective. So it can be an effective enhancers for bone grafting mixtures.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.42
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• pp.32.1-32.4
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• 2020

Background: Le Fort I osteotomy is a highly effective treatment for skeletal jaw deformities and is commonly performed. High Le Fort I osteotomy is a modified surgical procedure performed for improving the depression of the cheeks by setting the osteotomy higher than the conventional Le Fort I osteotomy. Developments in three-dimensional (3D) technology have popularized the use of 3D printers in various institutions, especially in orthognathic surgeries. In this study, we report a safe and inexpensive method of performing a high Le Fort I osteotomy using a novel 3D device and piezosurgery, which prevent tooth root injury without disturbing the operation field for patients with a short midface and long tooth roots. Results: A 17-year-old woman presented with facial asymmetry, mandibular protrusion, a short midface, and long tooth roots. We planned high Le Fort I osteotomy and bilateral sagittal split ramus osteotomy. Prevention of damage to the roots of the teeth and the infraorbital nerve and accurate determination of the posterior osteotomy line were crucial for clinical success. Le Fort I osteotomy using 3D devices has been reported previously but were particularly large in size for this case. Additionally, setting the fixing screw of the device was difficult, because of the risk of damage to the roots of the teeth. Therefore, a different surgical technique, other than the conventional Le Fort I osteotomy and 3D device, was required. The left and right parts of the 3D device were fabricated separately, to prevent any interference in the surgical field. Further, the 3D device was designed to accurately cover the bone surface from the piriform aperture to the infra-zygomatic crest with two fixation points (the anterior nasal spine and the piriform aperture), which ensured stabilization of the 3D device. The device is thin and does not interfere with the surgical field. Safe and accurate surgical performance is possible using this device and piezosurgery. The roots of the teeth and the infraorbital nerve were unharmed during the surgery. Conclusions: This device is considerably smaller than conventional devices and is a simple, low-cost, and efficient method for performing accurate high Le Fort I osteotomy.

• Journal of Periodontal and Implant Science
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• v.49 no.3
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• pp.171-184
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• 2019

Purpose: To evaluate the effects of intra-alveolar socket grafting, subepithelial connective tissue grafts, and individualized abutments on peri-implant hard and soft tissue outcomes following immediate implant placement. Methods: This randomized experimental study employed 5 mongrel dogs, with 4 sites per dog (total of 20 sites). The mesial roots of P3 and P4 were extracted in each hemimandible and immediate dental implants were placed. Each site was randomly assigned to 1 of 4 different treatment groups: standardized healing abutment (control group), alloplastic bone substitute material (BSS) + standardized healing abutment (SA group), BSS + individualized healing abutment (IA group), and BSS + individualized healing abutment + a subepithelial connective tissue graft (IAG group). Clinical, histological, and profilometric analyses were performed. The intergroup differences were calculated using the Bonferroni test, setting statistical significance at P<0.05. Results: Clinically, the control and SA groups demonstrated a coronal shift in the buccal height of the mucosa ($0.88{\pm}0.48mm$ and $0.37{\pm}1.1mm$, respectively). The IA and IAG groups exhibited an apical shift of the mucosa ($-0.7{\pm}1.15mm$ and $-1.1{\pm}0.96mm$, respectively). Histologically, the SA and control groups demonstrated marginal mucosa heights of $4.1{\pm}0.28mm$ and $4.0{\pm}0.53mm$ relative to the implant shoulder, respectively. The IA and IAG groups, in contrast, only showed a height of 2.6mm. In addition, the height of the mucosa in relation to the most coronal buccal bone crest or bone substitute particles was not significantly different among the groups. Volumetrically, the IA group ($-0.73{\pm}0.46mm$) lost less volume on the buccal side than the control ($-0.93{\pm}0.44mm$), SA ($-0.97{\pm}0.73mm$), and IAG ($-0.88{\pm}0.45mm$) groups. Conclusions: The control group demonstrated the most favorable change of height of the margo mucosae and the largest dimensions of the peri-implant soft tissues. However, the addition of a bone substitute material and an individualized healing abutment resulted in slightly better preservation of the peri-implant soft tissue contour.

• The Journal of Korean Academy of Prosthodontics
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• v.57 no.3
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• pp.304-311
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• 2019

After the teeth were extracted, maxillary and mandibular alveolar ridges show the opposite resorption pattern and as a result, the mandibular arch is enlarged than maxillary arch relatively. In this situation, we should evaluate both alveolar ridge relationship and arrange the artificial teeth properly for stability of removable prosthesis. This case is a 77 years old male patient who wishes to make removable prosthesis and has atrophic alveolar ridge. By use of model scanner and CAD software, the angle between interalveolar crest line and occlusal plane was easily measured. Depending on the measurement, the artificial teeth are arranged in unilateral cross bite and after completion, patient was satisfied with the denture which showed proper stability, retention, support.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.32 no.6
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• pp.446-457
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• 2020

Crescentic sand bar in the coastal zone of eastern Korea is a common morphological feature and the rhythmic patterns exist constantly except for high wave energy events. However, four consecutive typhoons that directly and indirectly affected the East Sea of Korea from September to October in 2019 impacted the formation of longshore uniform sand bar and overall shoreline retreats (approx. 2 m) although repetitive erosion and accretion patterns exist near the shoreline. Widely used XBeach to predict storm erosions in the beach is utilized to investigate the morphological response to a series of storms and each storm impact (NE-E wave incidence). Several calibration processes for improved XBeach modeling are conducted by recently reported calibration methods and the optimal calibration set obtained is applied to the numerical simulation. Using observed wave, tide, and pre & post-storm bathymetries data with optimal calibration set for XBeach input, XBeach successfully reproduces erosion and accretion patterns near MSL (BSS = 0.77 (Erosion profile), 0.87 (Accretion profile)) and observed the formation of the longshore uniform sandbar. As a result of analysis of simulated total sediment transport vectors and bed level changes at each storm peak Hs, the incident wave direction contributes considerable impact to the behavior of crescentic sandbar. Moreover, not only the wave height but also storm duration affects the magnitude of the sediment transport. However, model results suggest that additional calibration processes are needed to predict the exact crest position of bar and bed level changes across the inner surfzone.

• Journal of the Korean GEO-environmental Society
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• v.12 no.6
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• pp.53-60
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• 2011

The purpose of this study is to propose a method that can reliably evaluate the fundamental period of a rockfill dam using the micro-earthquake records, which were obtained at the domestic dam sites. For total 20 micro-earthquake records obtained at 7 domestic rockfill dam sites against 6 earthquake events which recently occurred, the fundamental periods of seven rockfill dams were evaluated by two kinds of methods; one is a method using acceleration amplification ratio and the other is a method using acceleration response spectrum ratio. Applicability of each method to evaluation of fundamental periods of domestic rockfill dams was examined. In the moderate seismicity region like our country, the method using acceleration response spectrum ratio, which could evaluate the fundamental period of the rockfill dam using the ratio between the response spectrum for acceleration observed at the dam crest and that observed at the dam base or abutment, proved to be reliable and was proposed in this study. From the results of analyses, it was found that the proposed method could consistently evaluate the fundamental period of the rockfill dam and the results obtained by the proposed method were very similar to the results by the existing method which was proposed from the analysis for the earthquake records observed at Japanese dam sites.

• (The)Study of the Eastern Classic
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• no.63
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• pp.43-82
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• 2016

The purpose of this paper is to study the image of the 16th Century Honam Chinese poetry. for that, Park Sang, Im Eokryeong, Ko Gyeongmyeong in this study. This paper identified the characteristics of Ho Nam poetry is two things. First of all, is "literary talent does not acknowledge" consciousness and image of army. Park Sang, Im Eokryeong, Ko Gyeongmyeong was advanced to the center politics with excellent literary talent to the talents our 16th century Honam. However, at that time, the ruling layer was time to lead the politics. Therefore, the three people to frustration. Yet three people were criticizing the reality. And they thought that they were unhappy. It is unfortunate that they did because of their literary talent to be recognized. Three people were very sensitive to not be recognized literary talent. This is because they were subject to the management by the literary ability. It does not recognize the literary consciousness appears as sword, spear, admiral image. Second, The HwaIbulryu consciousness and image of integrity. Park Sang, Im Eokryeong, Ko Gyeongmyeong thought it not right politics. Yet continued to politics. This is not behavior that is typical scholar. What they did so because we follow a man named Yuhahye. A man named yuhahye pursue life, be it a dirty political reality was to continue the crest. But that never lose their integrity. Three people who will follow the life of this Yuhahye. This is a life attitude graft Japanese apricot flower, oriole, rock of pillar, appears as an image.

• Journal of Dental Rehabilitation and Applied Science
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• v.36 no.4
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• pp.211-221
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• 2020

The typical biomechanical properties of an internal conical connection (ICC) are axial displacement and loss of preload. The axial displacement of an ICC without a vertical stop can cause the loss of preload and a lowered occlusion. The stress of an ICC is concentrated on the contact interface of the abutment and not on the screw, and during placement, it is important to choose a wider coronal wall thickness as much as possible. The ICC should also be placed below the level of the bone crest. During the restoration of an ICC, care should be taken to ensure an appropriate abutment shape and an accurate connection. To get the best clinical results, it is important to select its wall thickness and place it in the appropriate position to restore it adequately.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.33 no.4
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• pp.168-178
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• 2021

Numerical simulations were implemented to look into the modified seabed topography due to the presence of breakwaters of varying reflection characteristics. The numerical model was composed of OlaFlow, an OpenFoam-based tool box, and a physics-based morphology model [Seoul Foam]. In doing so, the interaction between the seabed, which undergoes deformation due to siltation and scouring, and the incoming waves was described using Dynamic Mesh. The rubble-mound, vertical, and curved slit caisson breakwaters with varying reflection characteristics resulted in standing waves that differ from each other, shown to have a significant influence on the seabed topography. These results are in line with Nielsen's study (1993) that sands saltated under the surface nodes of standing waves, where the near-bed velocities are most substantial, convected toward the surface antinodes by boundary-layer drift. Moreover, the crest of sand waves was formed under the surface antinodes of standing waves, and the trough of sand waves was formed under the surface antinodes. In addition, sand wave amplitude reaches its peak in the curved slit caisson with a significant reflection coefficient, and the saltation of many grains of sand would cause this phenomenon due to the increased near-bed velocity under the nodes when the reflection coefficient is getting large.