• Journal of the Korean Geotechnical Society
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• v.23 no.9
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• pp.29-37
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• 2007

The experiments have been conducted on Kaolinite in laboratory to investigate the development of shrinkage cracking and propose a simple model. Image analysis method consisting of control point selection(CPS) technique is used to process and analyze images of soil cracking captured by a digital camera. The distributions of crack length increment and crack area increment vary as a three-step process. These steps are regarded as stages of soil cracking. They are in turn primary crack, secondary crack and shrinkage crack stages. In case of crack area, the primary and secondary stages end at normalized gravimetric water content(NGWC) of 0.92 and 0.70 for different specimen thicknesses respectively. In addition, the primary stage in case of crack length also ends at NGWC of 0.92 while the secondary stage stops at NGWC of 0.79, 0.82, and 0.85 for the sample thicknesses of 0.5, 1.0, and 2.0 cm respectively Based on the experimental results, the distributions of crack length increment and crack area increment appear to be linear with a decrease of NGWC. Therefore, the development of shrinkage cracking is proposed typically by a simple model functioned by a combination of three linear expressions.

• Corrosion Science and Technology
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• v.22 no.2
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• pp.123-130
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• 2023

This study aimed to evaluate corrosion resistance of steel coated with GI and Zn-Al-Mg alloy using cyclic corrosion test (CCT) with electrochemical polarization and impedance measurements. Results showed that the Zn-Al-Mg alloy coated steel had a much higher corrosion rate than GI coated steel in early stages of corrosion. With prolonged immersion, however, the corrosion rate of the Zn-Al-Mg alloy coated steel greatly decreased, mainly owing to a significant decrease in the cathodic reduction reaction and an increase in polarization resistance at the surface. This was closely associated with the formation of protective corrosion products including Zn₅(OH)₈Cl₂·H₂O and Zn₆Al₂(OH)₁₆CO₃. Moreover, when the steel substrate was locally exposed due to mechanical damage, the kinetics of anodic dissolution from the coating layer and the formation of protective corrosion products on the surface of the Zn-Al-Mg alloy coated steel became much faster compared to the case of GI coated steel. This could provide a longer-lasting corrosion inhibition function for Zn-Al-Mg alloy coated steel used in plant farms.

• Journal of the Korean Society of Food Culture
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• v.22 no.4
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• pp.434-440
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• 2007

Yackwa is used as one of foods prepared for traditional rituals and holidays and enjoyed as snacks. Since Yackwas are fried, they contain oil, which can cause rancidity and undermines the freshness of Yackwas during distribution to retailers, not to mention a high level of calories. The study aims to develop baked Yackwas and analyze the quality in terms of calorie levels and characteristics by baking Yackwas in oven. Calorie level was 4.65 kcal/g in fried Yackwa, 3.96 kcal/g in baked Yackwa, and 2.95 kcal/g in baked peanut Yackwa prior to dip coating of grain syrup. baked Yackwa showed hardness of 13476.33 $g/cm^2$ before dipping in grain syrup, which was harder than 1912.56 $g/cm^2$ of fried Yackwa. After grain syrup coating, hardness of baked Yackwa reduced more significantly, compared with that of fried Yackwa, as grain syrup permeated through texture of Yackwa. And less hardness makes baked Yackwa tastier. Sensory evaluation was measured in a 5-point scale. Scores for texture and taste of baked Yackwa outpaced those of fried Yackwa. Score for the overall quality was 3.65 in baked Yackwa and 3.25 in baked peanut Yackwa, compared to 2.85 of fried Yackwa, indicating a higher potential of commercializing(p<0.05).

• Journal of the Korea Institute of Building Construction
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• v.23 no.5
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• pp.619-628
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• 2023

This study undertook a empirical analysis, delving into the association between the direct construction approach and the construction quality of general construction companies. The research hinged on corporate financial data to elucidate the premise that a reduced emphasis on direct construction approach by general construction companies correlates with a notable prevalence of building defects. Specifically, the analysis engaged with the top 100 construction companies based on their construction capability evaluation in 2022. This appraisal leveraged the Empirical Research Model(ERM) rooted in financial data-sets spanning 2017 to 2021. Findings underscored that as the ratio of direct construction approach diminishes, the incidence of building defects amplifies, signifying a consequential dip in construction quality. Moreover, the research reaffirmed that companies with elevated construction capability evaluations or larger organizational scales tend to register decreased defect rates. This study fortifies, from a theoretical perspective, the legislative imperatives championing direct construction approach, by empirically spotlighting the potential perils of over-reliance on subcontracting.

• Journal of The Korean Society of Agricultural Engineers
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• v.66 no.4
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• pp.27-39
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• 2024

Soil texture is determined by the proportions of sand, silt, and clay within the soil, which influence characteristics such as porosity, water retention capacity, electrical conductivity (EC), and pH. Traditional classification of soil texture requires significant sample preparation including oven drying to remove organic matter and moisture, a process that is both time-consuming and costly. This study aims to explore an alternative method by developing an AI model capable of predicting soil texture from images of pre-sorted soil samples using computer vision and deep learning technologies. Soil samples collected from agricultural fields were pre-processed using sieve analysis and the images of each sample were acquired in a controlled studio environment using a smartphone camera. Color distribution ratios based on RGB values of the images were analyzed using the OpenCV library in Python. A convolutional neural network (CNN) model, built on PyTorch, was enhanced using Digital Image Processing (DIP) techniques and then trained across nine distinct conditions to evaluate its robustness and accuracy. The model has achieved an accuracy of over 80% in classifying the images of pre-sorted soil samples, as validated by the components of the confusion matrix and measurements of the F1 score, demonstrating its potential to replace traditional experimental methods for soil texture classification. By utilizing an easily accessible tool, significant time and cost savings can be expected compared to traditional methods.

• Structural Engineering and Mechanics
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• v.89 no.3
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• pp.253-263
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• 2024

Slope stability is generally paid more attention to in slope protection works, especially for slope containing weak layers. Two indexes of safety factor and failure model are selected to perform slope stability. Moreover, the finite element limit analysis method comprehensively combines the advantage of the limit analysis method and the finite element method obtaining the upper and lower bounds of the safety factor and the failure mode under the slope stability limit state. In this study, taking a waste dump containing a weak layer as an engineering background, the finite element limit analysis method is adopted to explore the potential failure mode. Meanwhile, the sensitivity analysis of slope stability is performed on geometrical and geotechnical parameters of the waste dump. The results show that the failure mode of the waste dump slope is two wedges if the weak layer is located on the ground surface (Model A), while the slope can be observed as three wedges failure if the weak layer is below the ground surface (Model B). In addition, both failure modes are highly sensitive to the friction angle of the weak layer and the shear strength of waste disposal, and moderately sensitive to the heap height, the dip angle and cohesion of the weak layer, while the toe cutting has limited effect on the slope stability. Moreover, the sensitivity to the excavation of the ground depends on the location of the weak layer and failure mode.

• Journal of the Korean Wood Science and Technology
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• v.52 no.2
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• pp.157-174
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• 2024

This study investigates the influence of varying concentrations of boric acid (BA) preservative on the physical and mechanical properties of light red meranti (LRM) found in Sarawak. LRM or Shorea leprosula samples were treated with various concentrations of BA via the dip diffusion method using American Society for Testing and Materials (ASTM) standards. The physical property, particularly the retention rate and mechanical properties, bending strength, modulus of elasticity (MOE), tensile and compression strength parallel to grain of impregnated and control samples were tested to determine the effects of BA preservative. The retention rate was found to increase with increasing BA concentration and higher surface area to volume ratio. The mechanical properties in terms of the MOE and tensile strength parallel to grain were found to be greater than those of the control samples, whereas the bending strength and tensile strength parallel to grain were lower. Amongst the results, only the retention rate and MOE showed significant interaction effects at 5% level of significance between all factors tested (samples size and BA concentration for retention rate and BA concentration for MOE).

• Journal of the Korean Geotechnical Society
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• v.40 no.3
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• pp.101-108
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• 2024

A system with the ability to recognize potential key blocks during tunnel construction by analyzing the rock face was developed in this study. This system predicts the formation of key blocks in advance and evaluates their safety factors. A laser scanner was used to collect a three-dimensional point cloud of the rock face, which was then utilized to model the excavation surface and derive the joint surfaces. Because joint surfaces have specific strikes and dip angles, the key blocks formed by these surfaces are deduced through iterative calculations, and the safety factor of each key block can be calculated accordingly. The model experiments confirmed the accuracy of the system's output in terms of the joint surface characteristics. By inputting the joint surface information, the calculated safety factors were compared with those from the existing commercial software, demonstrating stable calculation results within a 1% error margin.

• The Journal of Korean Academy of Prosthodontics
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• v.51 no.4
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• pp.307-314
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• 2013

Purpose: The aim of this study was to evaluate the effect of immobilization of the recombinant human bone morphogenetic protein 2 (rhBMP-2) on anodized titaum implants coated with heparin to enhance the vertical alveolar ridge augmentation in the supraalveolar peri-implant defect region. Materials and methods: 18 pure titanium implants (7.0 mm in length, 3.5 mm in diameter) were manufactured for this study. All implants were anodized and designed insertion reference line marked with laser at the apical 2.5 mm from the fixture platform. Implantation of 6 noncoated anodized implants (Control group), 6 anodized implants physically adsorbed with rhBMP-2 by dip and dry method (BMP group) and 6 anodized implants chemically immobilized 3,4-dihydroxyphenylalanine (DOPA)-heparin/ rhBMP-2 (Hep-BMP group) was performed in the both mandibular of three male adult beagle dogs using split-mouth design. Radiologic examinations were performed immediately after implant placement and 4 and 8 weeks after implant placement. The amount of mesio-distal bone augmentation was evaluated by measuring the vertical distance from the platform to the marginal bone. Statistical analysis was performed using one-way analysis of variance (SPSS version 18.0) and multiple comparison analysis of The Kruskal-Wallis test and the Mann-Whitney U test. Statistical significance was established at the 5% significant level. Results: At the 4 weeks vertical alveolar ridge augmentation of Control group, BMP group and Hep-BMP group is $0.09{\pm}0.22mm$, $1.02{\pm}0.72mm$, and $1.29{\pm}0.51mm$, At the 8 weeks $0.11{\pm}1.26mm$, $1.11{\pm}0.58mm$, $1.59{\pm}0.79mm$ according to radiographic observations. The two experimental groups showed a significantly increasing in vertical bone height compared with the control group (P<.05). However, there is no significant difference between the BMP group and Hep-BMP group (P>.05). Conclusion: The rhBMP-2 coated implants were enhanced the vertical bone growth in the supraalveolar peri-implant defect area. However, there is no significant difference between chemically and physically coating method.

• Tuberculosis and Respiratory Diseases
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• v.51 no.3
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• pp.201-210
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• 2001

Background : Approximately 10-13% of patients with interstitial lung disease(ILD) die of lung cancer, and patients with ILD have been reported to have a 7 fold higher incidence of lung cancer compared to the normal population. Recently, overexpression of the p53 and p21 proteins were observed in the epithelial cells from pathologic specimens of ILD. Overexpression of these proteins may result from chronic or recurrent DNA damage by unknown causes of inflammation. However, these proteins may also contribute to oncogenesis if other genetic alterations such as K-ras are superimposed. Methods : Immunohistochemical stains for p53 and K-ras proteins were performed with pathologic specimens from 38 cases with ILD(M/F : 27/11, mean agea : $54{\pm}10$ years) and from 10 control subjects. Results : The p53 protein was expressed in 21.1% (8/38 ILD cases) and K-ras protein expression was observed in 65.8% (25/38 ILD cases). However, neither p53 nor the K-ras protein staining was observed in the control subjects. Conclusion : A significant proportion of cases with ILD expressed the p53 and K-ras proteins in their bronchial epithelial cells. These proteins may be potentially oncogenic with the addition of further genetic alterations. However, to clarify the significance of these findings, further studies looking for correlations with the incidence of lung cancer and other genetic changes are needed.