• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.4
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• pp.50-58
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• 2014

Due to the cost burden of new construction, the necessity of repair and retrofitting of aged structures is sharply increasing as the domain of repair and retrofitting construction is expanding. Because of the necessity, new technologies for repair and retrofitting are continuously studied in Korea and foreign countries. Steel adhesive method, fiber reinforced plastic (FRP) surface adhesive method, and external prestressing method are used to perform the repair and retrofitting works in Korea. In order to consider a repair method using steel mesh reinforced cement mortar (SMCM), 3-point flexural member test was conducted considering repair area and layer number of SMCM. Five types of specimens including ordinary reinforced concrete (RC) specimen with dimensions of $1400{\times}500{\times}200$ (mm) were cast for testing the deflection measurement, a LVDT was installed at the top center of the specimens. Also, a steel strain gauge and a concrete strain gauge were placed at the center of the specimens. A steel strain gauge was also installed on the shear reinforcement. The 3 point flexural member test results showed that the maximum load of SMCM reinforced specimen was higher than that of basic RC specimen in all of the load-displacement curves. Also, the results showed that, when the whole lower part of the basic RC specimen was reinforced, the maximum load and strain were 1.18 and 1.37 times higher than that of the basic RC specimen, respectively. Each specimen showed a slightly different failure behavior where the difference of the results was caused by the difference in the adhesive level between SMCM and RC. Particularly, in SM-B1 specimen, SMCM spalled off during the experiment. This failure behavior showed that the adhesive performance for RC must be improved in order to utilize SMCM as repair and retrofitting material.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.35 no.3
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• pp.161-166
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• 2013

Purpose: This study was intended to perform a cephalometric comparison between the patients with and without obstructive sleep apnea (OSA). The factors influencing the OSA in the lateral cephalogram were also investigated. Methods: Fifty patients who had visited the Sleep Disorder Clinic at the Ajou University Hospital and evaluated with the polysomnograph (PSG) and cephalogram, were included in the study. The patients had the apnea-hypopnea episode over 5 times per hour (apnea-hypopnea index $[AHI]{\geq}5$) were diagnosed as OSA after the overnight PSG. To evaluate the hard and soft tissue profiles, the cephalometric radiograms were taken at the maximal intercuspation. The correlation between the patient's age, height, weight, body mass index (BMI) and AHI was inspected in the OSA and control group. The difference between the OSA and control group was evaluated (Mann-Whitney U Test). The cephalometric influencing factors to OSA were analyzed (Pearson's correlation coefficient) statistically using SPSS statistics. Results: The OSA Group had a significantly higher BMI than the control group. The mean lower facial height (ANS-Me) was longer in the OSA group; however, statistically significant difference was not detected in the anteroposterior craniofacial measurements. The distance between mandibular plane and hyoid bone of the OSA group was significantly longer than that of the control group. The hyoid position (MP-Hyoid) had a positive correlation between AHI (P<0.001). However, the measurements of oropharyngeal airway were not different between the two groups. The hypothesis, that the antero-posteriorly narrow oropharyngeal airway may aggravate the airway resistance and give rise to a higher AHI, was rejected in the study. Conclusion: We suggest that the lateral cephalogram may be utilized as a useful method to evaluate OSA. The patients with a lower hyoid position can be expected to have higher risks of OSA. However, a comprehensive intraoral inspection, including the soft palate and tonsilar hypertrophy, is emphasized, as the lateral cepahlogram cannot visualize the oropharyngeal status completely.

• Asian-Australasian Journal of Animal Sciences
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• v.27 no.7
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• pp.1044-1049
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• 2014

This study was conducted in order to investigate whether the presence of light or different colors of light would influence the energy expenditure and behavior of broiler chickens. Eight 8-week-old broiler chickens were adapted to a respiration chamber (Length, 28.5 cm; Height, 38.5 cm; Width, 44.0 cm) for one week prior to the initiation of the experiment. In experiment 1, energy expenditure and behavior of the chickens were analyzed in the presence or absence of light for four days. Chickens were exposed to 6 cycles of 2 h light/2 h dark period per day. In experiment 2, the broiler chickens that had been used in experiment 1 were used to evaluate the effect of 4 different wavelength light-emitting diodes (LEDs) on the energy expenditure and behavior of broiler chickens. The LEDs used in this study had the following wavelength bands; white (control), red (618 to 635 nm), green (515 to 530 nm) and blue (450 to 470 nm). The chickens were randomly exposed to a 2-h LED light in a random and sequential order per day for 3 days. Oxygen consumption and carbon dioxide production of the chickens were recorded using an open-circuit calorimeter system, and energy expenditure was calculated based on the collected data. The behavior of the chickens was analyzed based on following categories i.e., resting, standing, and pecking, and closed-circuit television was used to record these behavioral postures. The analysis of data from experiment 1 showed that the energy expenditure was higher (p<0.001) in chickens under light condition compared with those under dark condition. The chickens spent more time with pecking during a light period, but they frequently exhibited resting during a dark period. Experiment 2 showed that there was no significant difference in terms of energy expenditure and behavior based on the color of light (white, red, green, and blue) to which the chickens were exposed. In conclusion, the energy expenditure and behavior of broiler chickens were found to be strongly affected by the presence of light. On the other hand, there was no discernible difference in their energy expenditure and behavior of broiler chickens exposed to the different LED lights.

• Journal of Dental Rehabilitation and Applied Science
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• v.33 no.2
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• pp.114-118
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• 2017

Purpose: The aim of this study was to investigate the effects of a titanium component for the zirconia abutment in the internal connection implant system on screw loosening under thermocycling conditions. Materials and Methods: Internal connection titanium abutments and external connection zirconia abutments with titanium sockets were connected respectively to screw-shaped internal connection type titanium implants with 30 Ncm tightening. These implant-screw-abutment assemblies were divided into two groups of five specimens each; titanium abutments as control and zirconia abutments with titanium sockets as experimental group. The specimens were subjected to 2,000 thermocycles in water baths at $5^{\circ}C$ and $55^{\circ}C$, with 60 seconds of immersion at each temperature. The removal torque values (RTVs) of the abutment screws of the specimen were measured before and after thermocycling. RTVs pre- and post-thermocycling were investigated in statistics. Results: There was not screw loosening identified by tactile and visual inspection in any of the specimens during or after thermocycling. The mean RTV difference for the control group and the experimental group were $-1.34{\pm}2.53Ncm$ and $-1.26{\pm}2.06Ncm$, respectively. Statistical analysis using an independent t-test revealed that no significant differences were found in the mean RTV difference of the groups (P > 0.05). Conclusion: Within the limitations of this in vitro study, the titanium socket for the zirconia abutment did not show a significant effect on screw loosening under thermal stress compared to the titanium abutment in the internal connection implant.

• The Korean Journal of Food And Nutrition
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• v.21 no.4
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• pp.562-571
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• 2008

The principal objective of this study was to assess dietitian's awareness and performance with regard to food suppliers' selection guidelines and purchase guidelines for the receipt of safe food materials. A questionnaire was administered to 203 dietitians working at an elementary school in Gyeonggi North province, and 190 responses were ultimately returned. Excluding responses with incomplete answers and significant missing data, 161 responses(79.3%) were ultimately utilized for data analysis. We determined that meat/poulty and seafood were purchased mainly by manufacturer's branch(59.8% and 78.3%), and processed food and kimchi were generally purchased by producer's cooperatives(47.7% and 44.9%). 78.3% of the contracts were made via informal purchasing and the frequency of contracts was less than 3 times per year(53.4%). Market studies were conducted individually(54.7%), and by group(47.2%). Dietitian and parents volunteered(50.3%) or dietitians, and school and foodservice staffs(45.3%) participated - together in receiving and inspection. School contracted with $4{\sim}5$(39.1%) and $6{\sim}8$ food suppliers(29.8%). Dietitians(42.3%) or school councils(40.2%) evaluated food suppliers once per semester(60.2%). The majority of dietitians(96.3%) conducted sanitary education for food suppliers once per semester (68.3%). All 13 guidelines which were usually used to evaluate food suppliers were thought to be important(more than 4) based on a 5 scale(1: never important, 5: very important). Among them, 'sanitary storage status of food products(4.85)', 'have a chill car(4.83)' and 'proper control of refrigerator, freezer and storage room(4.81)' were the most crucial guidelines. As dietitians evaluated food supplier's-observances of 13 guidelines, 'have a chill car(4.89)', 'hold medical examination of employees(4.89)' and 'hold liability insurance for handling product(4.80)' were fulfilled relatively well. The guidelines for conducting education for their employees(4.45) and keeping their establishment and equipment sanitary(4.79) were important, but were not observed well(3.39 and 3.37). Additionally, the difference between the importance and the observance score of the 'HACCP certificate' were fairly significant(4.44 and 3.54). Dietitians tended to report that purchasing management related to the removal of foodborne illness factors(4.71), return confirmation(4.50) and purchase specification(4.32) were important. The difference between importance and performance was highest in the process of changing food suppliers when the contracts were violated more than three times. Dietitian's age, education work experience and employment type had no observable effects on how important they considered purchase management to be, but their work experience significantly affected performance in terms of the removal of foodborne illness factors(p<0.05). As supplier management is the most critical factor, it is clearly desirable to educate suppliers at specialized training centers and to supervise suppliers in accordance with the established sanitary guidelines.

• Korean Journal of Environment and Ecology
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• v.36 no.5
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• pp.535-549
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• 2022

Damage to forests, such as broken or falling trees, has increased due to the increased intensity and frequency of abnormal climate events, such as strong winds and heavy rains. However, it is difficult to respond to them in advance based on prediction since structural defects such as cavities and bumps inside trees are difficult to identify with a visual inspection. Non-invasive sonic tomography (SoT) is a method of estimating internal defects while minimizing physical damage to trees. Although SoT is effective in diagnosing internal defects, its accuracy varies depending on the species. Therefore, it is necessary to analyze the reliability of its measurement results before applying it in the field. In this study, we measured internal defects in wood by cross-applying destructive resistance micro drilling on old Pinus densifloraSiebold & Zucc. and Ginkgo bilobaL., which are representative tree species in Korea, to verify the reliability of SoT and compared the evaluation results. The t-test for the mean values of the defect measurement between the two groups showed no statistically significant difference in pine trees and some difference in ginkgo trees. Linear regression analysis results showed a positive correlation with an increase in defects in SoT images when the defects in the drill resistance graph increased in both species.

• Journal of Convergence for Information Technology
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• v.9 no.12
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• pp.141-146
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• 2019

Economic analysis predicts that the drone market will grow, and the growth of the toy and hobby drone market is expected to gradually expand. Drone expectations are rising due to the net economic function of drone market growth, but accidents due to improper management and operations are also increasing. The difference in toy drone performance is incomparably small compared to industrial drone performance, but the ordinary buyer can not know whether the difference can cause an accident during use. The toy drones used in this study were obtained from KC and CE certification, and 20 kinds of drones were used. The flight time ranged from a minimum of 3 minutes to a maximum of 12 minutes, and the control distance ranged from a minimum of 20m to a maximum of 380m. Therefore, it is necessary to secure product safety through sampling inspection of the radio wave output of toy drones, and it is also necessary to mount an algorithm that automatically lowers the altitude or hover when exceeding the limit flight distance. For future research, we will build data to establish toy drone safety standards through a altitude testing and impact testing of toy drone.

• Journal of Advanced Navigation Technology
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• v.28 no.3
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• pp.254-261
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• 2024

Accurate guidance during landing and take-off is important, and instrument landing system (ILS) has been used for stability and verification. Regular inspections are conducted for stable operation, and there is research to perform inspection using drones in addition to ground vehicles and measurement aircraft. Using SDR and single board computer, which can receive wide frequency range, we designed a small system that receives and processes localizer signals through GNU Radio. To check signal processing characteristics through GNU Radio, we simulated with MATLAB Simulink and confirmed the theoretical values. Difference in depth of modulation (DDM) and approach angle can be calculated when the aircraft enters the runway. And GNU Radio implemented real-time signal processing wirelessly using transmission control protocol (TCP). This gives the results within the error of 0.5% when the aircraft entered the runway center line and 0.27% for the angle of 1° degree. Compared to the inspecting and maintaining ILS signals using aircraft or ground vehicles, it is possible to implement a receiving system using small SDR that can be mounted for drone.

• Journal of KIISE:Software and Applications
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• v.37 no.4
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• pp.273-281
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• 2010

In this paper, we propose an automatic segmentation method of the endo- and epicardial boundary by using ray-casting profile based on intensity distribution and gradient information in CT images. First, endo-cardial boundary points are detected by using adaptive thresholding and seeded region growing. To include papillary muscles inside the boundary, the endo-cardial boundary points are refined by using ray-casting based profile. Second, epi-cardial boundary points which have both a myocardial intensity value and a maximum gradient are detected by using ray-casting based adaptive gradient profile. Finally, to preserve an elliptical or circular shape, the endo- and epi-cardial boundary points are refined by using elliptical interpolation and B-spline curve fitting. Then, curvature-based contour fitting is performed to overcome problems associated with heterogeneity of the myocardium intensity and lack of clear delineation between myocardium and adjacent anatomic structures. To evaluate our method, we performed visual inspection, accuracy and processing time. For accuracy evaluation, average distance difference and overalpping region ratio between automatic segmentation and manual segmentation are calculated. Experimental results show that the average distnace difference was $0.56{\pm}0.24mm$. The overlapping region ratio was $82{\pm}4.2%$ on average. In all experimental datasets, the whole process of our method was finished within 1 second.

• Journal of KIISE:Software and Applications
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• v.37 no.2
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• pp.110-119
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• 2010

In this paper, we propose an automatic segmentation of the prostate using intensity distribution and gradient information in MR images. First, active shape model using adaptive intensity profile and multi-resolution technique is used to extract the prostate surface. Second, hole elimination using geometric information is performed to prevent the hole from occurring by converging the surface shape to the local optima. Third, the surface shape with large anatomical variation is corrected by using 2D gradient information. In this case, the corrected surface shape is often represented as rugged shape which is generated by the limited number of vertices. Thus, it is reconstructed by using surface modelling and smoothing. To evaluate our method, we performed the visual inspection, accuracy measures and processing time. For accuracy evaluation, the average distance difference and the overlapping volume ratio between automatic segmentation and manual segmentation by two radiologists are calculated. Experimental results show that the average distance difference was 0.3${\pm}$0.21mm and the overlapping volume ratio was 96.31${\pm}$2.71%. The total processing time of twenty patient data was 16 seconds on average.