• Korean Journal of Heritage: History & Science
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• v.42 no.3
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• pp.48-65
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• 2009

In order to understand the local vegetation history and the origin of rice cultivation, a phytoliths analysis was performed with sediments collected from archaeological site at Ga-dong in Gijang, Busan. From the analysis with the sediments of three sampling sites, fan-shape phytoliths of Oryza sativa were detected: sediment 8 ~ sediment 29 of sampling site 1, sediment 6 ~ sediment 20 of sampling site 2 and sediment 7 ~ sediment 33 of sampling site 3. On the bottom layers or near the bottom layers from the three sampling sites, high densities of Arundinoideae and Andropogoneae were detected. It indicates that these layers were wet soil environment when they were sedimented. From near bottoms up to surfaces, the densities of Arundinoideae and Andropogoneae were abruptly decreased, while the density of Oryza sativa was sharply increased. With these results, it should be considered that the rice cultivation was started from the Bronze Age on this region.

• Journal of Dental Rehabilitation and Applied Science
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• v.36 no.3
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• pp.183-195
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• 2020

Purpose: The purpose of this study is to compare the flexural strength of CAD/CAM denture base resins with conventional denture base resins based on their thicknesses. Materials and Methods: For the conventional denture base resins, Lucitone 199^® (C-LC) was used. DIOnavi - Denture (P-DO) and DENTCA Denture Base II (P-DC) were taken for the 3D printing denture base resins. For the prepolymerized PMMA resins, Vipi Block Gum (M-VP) and M-IVoBase^® CAD (M-IV) were used. The final dimensions of the specimens were 65.0 mm x 12.7 mm x 1.6 mm / 2.0 mm / 2.5 mm. The 3-point bend test was implemented to measure the flexural strength and flexural modulus. Microscopic evaluation of surface of fractured specimen was conducted by using a scanning electron microscope (SEM). After testing the normality of the data, one-way ANOVA was adopted to evaluate the differences among sample groups with a significance level of P = 0.05. The Tukey HSD test was performed for post hoc analysis. Results: Under the same thicknesses, there are significant differences in flexural strength between CAD/CAM denture base resins and conventional denture base resins except for P-DO and C-LC. M-VP showed higher flexural strength than conventional denture base resins, P-DC and M-IV displayed lower flexural strength than conventional denture base resins. Flexural modulus was highest in M-VP, followed by C-LC, P-DO, P-DC, M-IV, significant differences were found between all materials. In the comparison of flexural strength according to thickness, flexural strength of 2.5 mm was significantly higher than that of 1.6 mm in C-LC. Flexural strength of 2.5 mm and 2.0 mm was significantly higher than that of 1.6 mm in P-DC and M-VP. In M-IV, as the thickness increases, significant increase in flexural strength appeared. SEM analysis illustrates different fracture surfaces of the specimens. Conclusion: The flexural strength of different CAD/CAM denture base resins used in this study varied according to the composition and properties of each material. The flexural strength of CAD/CAM denture base resins was higher than the standard suggested by ISO 20795-1:2013 at a thickness of 1.6 mm or more though the thickness decreased. However, for clinical use of dentures with lower thickness, further researches should be done regarding other properties at lower thickness of denture base resins.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.21 no.6
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• pp.259-265
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• 2011

This research was performed to stabilize heavy metals in mine tailing using fly ash and clay. Fly ash-clay-mine tailing system were investigated using XRD (X-ray diffractometer), XRF (X-ray fluorescence spectrometer), TG-DTA, SEM (Scanning Electron Microscope), Dilatometer and UTM with various mine tailing contents (~15 wt%). The fly ash used in this research was mainly composed of $SiO_2$ (33.01 wt%), $Al_2O_3$ (28.54 wt%), $K_2O$ (3.32 wt%), $Fe_2O_3$ (1.47 wt%), CaO(9.97 wt%). $SiO_2$ and $Al_2O_3$ composition of the clay was over 61 wt%. And the mine tailing have high composition of $SiO_2$ (26.91 wt%), CaO (24.25 wt%), $Fe_2O_3$ (22.97 wt%). Therefore, it was estimated that fly ash-clay-mine tailing have enough sintering characteristics. The shrinkage of specimens started at around $850^{\circ}C$ and changed little up to $1100^{\circ}C$, but increased markedly at above $1100^{\circ}C$. The shrinkage rate is strongly related to the decarbonization amount of coal fly ash. As the result of SEM, structure of the specimens with mine tailing addition showed more close than the one without mine tailing. Compressive strength of the specimens with mine tailing was highly increased to approximately 200~420 kgf/$cm^2$, it satisfied the first grade criterion for clay brick by KS L 4201. The specification of leaching characteristics of the sintered specimens were within the Korean regulation standard.

• Journal of the Korean Geotechnical Society
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• v.39 no.10
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• pp.41-48
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• 2023

The presence of abnormalities in the subgrade of roads poses safety risks to users and results in significant maintenance costs. In this study, we aimed to experimentally evaluate the temperature distributions in abnormal areas of subgrade materials using infrared cameras and analyze the data with machine learning techniques. The experimental site was configured as a cubic shape measuring 50 cm in width, length, and depth, with abnormal areas designated for water and air. Concrete blocks covered the upper part of the site to simulate the pavement layer. Temperature distribution was monitored over 23 h, from 4 PM to 3 PM the following day, resulting in image data and numerical temperature values extracted from the middle of the abnormal area. The temperature difference between the maximum and minimum values measured 34.8℃ for water, 34.2℃ for air, and 28.6℃ for the original subgrade. To classify conditions in the measured images, we employed the image analysis method of a convolutional neural network (CNN), utilizing ResNet-101 and SqueezeNet networks. The classification accuracies of ResNet-101 for water, air, and the original subgrade were 70%, 50%, and 80%, respectively. SqueezeNet achieved classification accuracies of 60% for water, 30% for air, and 70% for the original subgrade. This study highlights the effectiveness of CNN algorithms in analyzing subgrade properties and predicting subsurface conditions.

• Journal of Korean Society of Forest Science
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• v.111 no.1
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• pp.115-124
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• 2022

This study was conducted to obtain basic data that could help prevent damage caused by slow-moving landslides (land-creep). Specifically, the geological, topographic, and physical characteristics of land-creep were analyzed in Jiphyeon-myeon, Jinju-si. The first and second analyzed land-creeps occurred in 1982 and 2019, respectively. The area damaged in the second land-creep was about 11.5-fold larger than that damaged in the first land-creep. The dominant constituent rock in the land-creep area was sedimentary rock, which seems to be weakly resistant to weathering. The areas that collapsed due to land-creep were related to the presence of separated rocks between the bedding plane in the estimated activity surface over the slope direction and the vertically developed joint surface. Thus, surface water and soil debris were introduced through the gaps of separated rocks. Additionally, the areas collapsed due to the combination of the bedding plane and joint surface shale and sandstone showed an onion structure of weathered outcrop from the edge to inner part caused by weathering from ground water. Consequently, core stones were formed. The study area was a typical area of land-creep in a mountain caused by ground water. Land-creep was classified into convex areas of colluvial land-creep. The landslide-risk rating in the study area was classified into three and five classes. The flow of ground water moved to the northeast and coincided with the direction of the collapse. Soil bulk density in the collapsed area was lower than that in ridge area, which was rarely affected by land-creep. Thus, soil bulk density was affected by the soil disturbance in the collapsed area.

• Journal of Gastric Cancer
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• v.7 no.4
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• pp.185-192
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• 2007

Purpose: RUNX3, a novel tumor suppressor, is frequently inactivated in gastric cancer. In the present study, we examined the pattern of RUNX3 expression in gastric cancer cells from gastric cancer specimens and the impact of its alteration on clinical outcome. Materials and Methods: A total of 124 samples of both gastric cancer and normal tissue were obtained from 124 patients who underwent curative gastrectomy at the Seoul Medical Center from January 2001 to December 2005. RUNX3 expression was determined by immunohistochemical staining, and the results were analyzed. Statistical analysis wabased on clinicopathological findings and differences in survival rates. Results: The mean age of the patients was 61 years, and the male:female ratio was 1.9:1. The expression rate of RUNX3 was 59.7% (74/124). The expression rate was higher in differentiated gastric cancers (nucleus: 9.1%, cytoplasm: 57.6%) than in the undifferentiated types (nucleus: 5.2%, cytoplasm: 46.6%) (P=0.133). The 5-year survival rates according to RUNX3 expression determined from cancer tissue were 88.9% for the nucleus $\pm$ cytoplasm(+) group of patients, 76.1% for the cytoplasm only (+) group of patients, and 65.3% for the RUNX3 negative expression group of patients (P=0.626). Only UICC TNM staging showed statistical significance related to the survival rate, as determined by multivariate analysis. Conclusion: The RUNX3 expression rate was higher in differentiated gastric cancer than in the undifferentiated types without significance. Although RUNX3 expression predicted better survival, based on multivariate analysis, the finding was not statistically significant. More cases should be further evaluated.

• Restorative Dentistry and Endodontics
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• v.31 no.3
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• pp.179-185
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• 2006

This study was conducted to evaluate canal configuration after shaping by $ProTaper^{TM}$ with various rotational speed in J-shaped simulated resin canals. Forty simulated root canals were divided into 4 groups, and instrumented using by $ProTaper^{TM}$ at the rotational speed of 250, 300, 350 and 400 rpm. Pre-instrumented and post-instrumented images were taken by a scanner and those were superimposed. Outer canal width, inner canal width, total canal width, and amount of transportation from original axis were measured at 1, 2, 3, 4, 5, 6, 7 and 8 mm from apex. Instrumentation time, instrument deformation and fracture were recorded. Data were analyzed by means of one-way ANOVA followed by Scheffe's test. The results were as follows 1. Regardless of rotational speed, at the $1{\sim}2mm$ from the apex, axis of canal was transported to outer side of a curvature, and at 3~6 mm from the apex, to inner side of a curvature. Amounts of transportation from original axis were not sienifcantly different among experimental groups except at 5 and 6 mm from the apex. 2. Instrumentation time of 350 and 400 rpm was significantly less than that of 250 and 300 rpm (p<0.01). In conclusion the rotational speed of $ProTaper^{TM}$ files in the range of $250{\sim}400rpm$ does not affect the change of canal configuration, and high rotational speed reduces the instrumentation time. However appearance of separation and distortion of Ni-Ti rotary files can occur in high rotational speed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.3
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• pp.694-702
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• 2017

In the case of an elevated railway station, structure borne noise and vibration due to structural limitations allow the load and vibration from railway vehicles to be directly transmitted to the station structure, resulting in an increase in the number of civil complaints from customers and staff of the station. The floating slab track system, which is well known as one of the solutions for reducing the noise and vibration from elevated railway stations, usually contains rubber mounts or rubber pads under the railway slab which act as a damper. These types of device have the disadvantage that is difficult to predetermine the exact stiffness and damping ratio under the nonlinear loads resulting from train services. In this study, an isolator with a friction type of wedge is introduced, which can be applied to floating slab track systems and to be designed with precisely the required stiffness. Furthermore, a comparative analysis of the stiffness between the designed and experimental values is carried out, while the damping ratio, which is closely related to the friction wedge blocks, is deduced according to the train load condition. The performance tests of the isolator were conducted in accordance with the DIN 45673-7 standard which includes both static and dynamic load tests. The load conditions for the performance tests are designed to conform to the DIN standard related to the weight of the train and rail track, in order to perform vertical and horizontal load tests, so as to ensure the secure structural safety of the railway. Also, by checking the change aspect of the friction coefficients of the friction elements according to the loading rate, the vibration reduction performance of the friction type isolator with variable loading rate conditions is examined.

• Journal of Korea Port Economic Association
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• v.26 no.3
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• pp.56-74
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• 2010

The overseas expansion of global logistics company (GLC) is increasing rapidly under the influence of international specialization of manufacturing, and the necessity of global logistics service is increasing, and then the logistics market is growing year to year. The purposes of this study are to investigate the growing factors and strategies making global logistics company and to suggest the best strategies for overseas expansion of domestic logistics company (DLC) by using imitation strategy. The major results are as follows ; Firstly, DLC has to imitate liner shipping company or terminal operator which has competitiveness rather than other part of logistics. Secondly, DLC has to build up competition through investigation the global logistics companies which have globalization, specialization, monopolization and public elements. Thirdly, DLC has to use 'coming from behind strategy' for the exiting market, the 'pioneer importer strategy' for the new emerging market or niche. Lastly, DLC has to make a road map or process for expanding the logistics service area without collision exiting business models.

• Journal of Conservation Science
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• v.27 no.3
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• pp.313-322
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• 2011

The floral wall of Lee Sang-beom's House and Atelier, which is No. 171 of the Registrated Cultural Heritage was conserved. In addition, materials characteristics and manufacturing technique have revealed through the scientific analysis. As a result of the analysis, samples were divided into three sections; the support layer that is made from block bricks, the paint layer and the cement mortar layer on the paint layer for the reinforcement of the construction. The higher layer lies, the finer grains it has. Furthermore, a little it was generated a small quantity of pores and calcium carbonates ($CaCO_3$) generated due to aeration of cement mortar. The patterns of letters, animals and plants pattern were expressed in the paint layer by relief and openwork. The results of qualitative analysis of the pigments of the paint layer were detected components of carbon black (C), Fe oxide ($Fe_2O_3$) and oyster shell white ($CaCO_3$, or quicklime). On the other hands, as the conservation of the floral wall, stainless frames were set up for the structural stability, the cement mortar were removed from the surface and the partly damaged and cracked areas were filled with KSE Filler A, B.