• 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.

• Journal of the Korean Geotechnical Society
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• v.24 no.10
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• pp.33-43
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• 2008

In this study, for the purpose of evaluating the shear wave velocity in core zone, cross-hole test, down-hole test, MASW (Multi-channel Analysis of Surface Wave), and seismic reflection survey were carried out on the crest of the existing 'Y' dam. The results of field tests were compared one another. Furthermore, the field test results were compared with the result by the Sawada's empirical recommendation method. The purpose of this study is to compare the results of four kinds of field tests for evaluation of shear wave velocity in core zone of existing dam, to verify applicability of the empirical method which was recommended by Sawada and Takahashi, and to recommend a reasonable method for evaluation of shear wave velocity which is needed to evaluate tile maximum shear modulus of core zone. From the results of four kinds of field tests such as cross-hole test, down-hole test, MASW, and seismic reflection survey, it was found that the shear wave velocity distributions were similar within 18 m in depth and the results obtained by MASW and seismic reflection survey were almost the same by 30 m in depth. For evaluation of shear wave velocity in core zone of the existing dam, in consideration that it is not easy to bore the hole ill the core zone of existing dam, surface surveys such as MASW and seismic reflection method are recommended as realistic methods. On condition that it is impossible to conduct the field test and it is preliminary investigation, it is recommended that Sawada's low bound empirical equation be used.

• Journal of the Korean Geotechnical Society
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• v.39 no.7
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• pp.57-67
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• 2023

Slope failures during rainfall have been observed in mountainous areas of South Korea as a result of the presence of solar power facilities. The seepage behavior and pore pressure distribution differ from typical slopes due to the presence of impermeable solar panels, and the load imposed by the solar power structures also affects the slope behavior. This study aims to develop a method for evaluating the stability of slopes with solar power facilities and to analyze vulnerable points by considering the maximum slope displacement. To assess the slope stability and predict behavior while considering rainfall seepage, a combined seepage analysis and finite difference method numerical analysis were employed. For the selected site, various variables were assumed, including parameters related to the Soil Water Characteristic Curve, strength parameters that satisfy the Mohr-Coulomb failure criterion, soil properties, and topographic factors such as slope angle and bedrock depth. The factors with the most significant influence on the factor of safety (FOS) were identified. The presence of solar power facilities was found to affect the seepage distribution and FOS, resulting in a decreasing trend due to rainfall seepage. The maximum displacement points were concentrated near the upper (crest) and lower (toe) sections of the slope.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.1B
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• pp.95-109
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• 2008

We numerically analyzed the nonlinear shoaling, a plunging breaker and its accompanying energetic suspension of sediment at a bed, and a redistribution of suspended sediments by a down rush of preceding waves and the following plunger using SPH with a Gaussian kernel function, Lagrangian Dynamic Smagorinsky model (LDS), Van Rijn's pick up function. In that process, we came to the conclusion that the conventional model for the tractive force at a bottom like a quadratic law can not accurately describe the rapidly accelerating flow over a swash zone, and propose new methodology to accurately estimate the bottom tractive force. Using newly proposed wave model in this study, we can successfully duplicate severely deformed water surface profile, free falling water particles, a queuing splash after the landing of water particles on the free surface and a wave finger due to the structured vortex on a rear side of wave crest (Narayanaswamy and Dalrymple, 2002), a circulation of suspended sediments over a swash zone, net transfer of sediments clouds suspended over a swash zone toward the offshore, which so far have been regarded very difficult features to mimic in the computational fluid mechanics.

• Journal of Periodontal and Implant Science
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• v.54 no.2
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• pp.96-107
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• 2024

Purpose: Deproteinized bovine bone or synthetic hydroxyapatite are 2 prevalent bone grafting materials used in the clinical treatment of peri-implant bone defects. However, the differences in bone formation among these materials remain unclear. This study evaluated osteogenesis kinetics in peri-implant defects using 2 types of deproteinized bovine bone (Bio-Oss^® and Bio-Oss/Collagen^®) and 2 types of synthetic hydroxyapatite (Apaceram-AX^® and Refit^®). We considered factors including newly generated bone volume; bone, osteoid, and material occupancy; and bone-to-implant contact. Methods: A beagle model with a mandibular defect was created by extracting the bilateral mandibular third and fourth premolars. Simultaneously, an implant was inserted into the defect, and the space between the implant and the surrounding bone walls was filled with Bio-Oss, Bio-Oss/Collagen, Apaceram-AX, Refit, or autologous bone. Micro-computed tomography and histological analyses were conducted at 3 and 6 months postoperatively (Refit and autologous bone were not included at the 6-month time point due to their rapid absorption). Results: All materials demonstrated excellent biocompatibility and osteoconductivity. At 3 months, Bio-Oss and Apaceram-AX exhibited significantly greater volumes of formation than the other materials, with Bio-Oss having a marginally higher amount. However, this outcome was reversed at 6 months, with no significant difference between the 2 materials at either time point. Apaceram-AX displayed notably slower bioresorption and the largest quantity of residual material at both time points. In contrast, Refit had significantly greater bioresorption, with complete resorption and rapid maturation involving cortical bone formation at the crest at 3 months, Refit demonstrated the highest mineralized tissue and osteoid occupancy after 3 months, albeit without statistical significance. Conclusions: Overall, the materials demonstrated varying post-implantation behaviors in vivo. Thus, in a clinical setting, both the properties of these materials and the specific conditions of the defects needing reinforcement should be considered to identify the most suitable material.

• Journal of Korean Neurosurgical Society
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• v.67 no.3
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• pp.354-363
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• 2024

Objective : This study aims to determine the optimal dose of recombinant-human bone morphogenic protein-2 (rhBMP-2) for successful bone fusion in minimally invasive lateral lumbar interbody fusion (MIS LLIF). Previous studies show that rhBMP is an effective alternative to autologous iliac crest bone graft, but the optimal dose remains uncertain. The study analyzes the fusion rates associated with different rhBMP doses to provide a recommendation for the optimal dose in MIS LLIF. Methods : Ninety-three patients underwent MIS LLIF using demineralized bone matrix (DBM) or a mixture of rhBMP-2 and DBM as fusion material. The group was divided into the following three groups according to the rhBMP-2 usage : group A, only DBM was used (n=27); group B, 1 mg of rhBMP-2 per 5 mL of DBM paste (n=41); and group C, 2 mg of rhBMP-2 per 5 mL of DBM paste (n=25). Demographic data, clinical outcomes, postoperative complication and fusion were assessed. Results : At 12 months post-surgery, the overall fusion rate was 92.3% according to Bridwell fusion grading system. Groups B and C, who received rhBMP-2, had significantly higher fusion rates than group A, who received only DBM. However, there was no significant increase in fusion rate when the rhBMP-2 dosage was increased from group B to group C. The groups B and C showed significant improvement in back pain and Oswestry disability index compared to the group A. The incidence of screw loosening was decreased in groups B and C, but there was no significant difference in the occurrence of other complications. Conclusion : Usage of rhBMP-2 in LLIF surgery leads to early and increased final fusion rates, which can result in faster pain relief and return to daily activities for patients. The benefits of using rhBMP-2 were not significantly different between the groups that received 1 mg/5 mL and 2 mg/5 mL of rhBMP-2. Therefore, it is recommended to use 1 mg of rhBMP-2 with 5 mL of DBM, taking both economic and clinical aspects into consideration.