• Journal of Korea Water Resources Association
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• v.48 no.10
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• pp.845-855
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• 2015

Studies of optimizing pump operation in water distribution networks (WDN) are receiving spotlight in recent days. However, the water networks are quite complex including thousands of or even tens of thousands of nodes and pipes, thus simulation time is an issue. In some cases, implementing a computer model for pump operation decisions is restrictive due to intensive computation time. To that end, it is necessary to reduce the simulation time of water networks by simplifying the network layout. In this study, WDN skeletonization approaches were suggested and applied to a real water transmission network in South Korea. In skeletonizing the original network, it was constrained to match the water pressure and water age in the same junction locations to maintain the hydraulic and water quality characteristics in the skeletonized network. Using the skeletonization approaches suggested in this study, it is expected to reduce the simulation time of WDN and apply for developing a computer module of WDN real-time optimal operation.

• The korean journal of orthodontics
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• v.46 no.5
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• pp.323-330
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• 2016

Objective: The purpose of this study was to determine whether the results of fractal analysis can be used as criteria for midpalatal suture maturation evaluation. Methods: The study included 131 subjects aged over 18 years of age (range 18.1-53.4 years) who underwent cone-beam computed tomography. Skeletonized images of the midpalatal suture were obtained via image processing software and used to calculate fractal dimensions. Correlations between maturation stage and fractal dimensions were calculated using Spearman's correlation coefficient. Optimal fractal dimension cut-off values were determined using a receiver operating characteristic curve. Results: The distribution of maturation stages of the midpalatal suture according to the cervical vertebrae maturation index was highly variable, and there was a strong negative correlation between maturation stage and fractal dimension (-0.623, p < 0.001). Fractal dimension was a statistically significant indicator of dichotomous results with regard to maturation stage (area under curve = 0.794, p < 0.001). A test in which fractal dimension was used to predict the resulting variable that splits maturation stages into ABC and D or E yielded an optimal fractal dimension cut-off value of 1.0235. Conclusions: There was a strong negative correlation between fractal dimension and midpalatal suture maturation. Fractal analysis is an objective quantitative method, and therefore we suggest that it may be useful for the evaluation of midpalatal suture maturation.

• Imaging Science in Dentistry
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• v.40 no.3
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• pp.123-129
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• 2010

Purpose : To evaluate the effect of surgical treatment of ligature-induced peri-implantitis in dogs using fractal analysis. Also, the capabilities of fractal analysis as bone analysis techniques were compared with those of histomorphometric analysis. Materials and Methods : A total of 24 implants were inserted in 6 dogs. After a 3-months, experimental periimplantitis characterized by a bone loss of about 3 mm was established by inducing with wires. Surgical treatment involving flap procedure, debridement of implants surface with chlorhexidine and saline (group 1), guided bone regeneration (GBR) with absorbable collagen membrane and mineralized bone graft (group 2), and $CO_2$ laser application with GBR (group 3) were performed. After animals were sacrificed in 8 and 16 weeks respectively, bone sections including implants were made. Fractal dimensions were calculated by box-counting method on the skeletonized images, made from each region of interest, including five screws at medial and distal aspects of implant, were selected. Results : Statistically significant differences in the fractal dimensions between the group 1($0.9340{\pm}0.0126$) and group 3($0.9783{\pm}0.0118$) at 16 weeks were found (P<0.05). The fractal dimension was statistically significant different between 8($0.9395{\pm}0.0283$) and 16 weeks in group 3 (P<0.05). These results were similar with the result of the evaluation of new bone formation in histomorphometric analysis. Conclusions : Treatment of experimental peri-implantitis by using $CO_2$ laser with GBR is more useful than other treatments in the formation of new bone and also the tendency of fractal dimension to increase relative to healing time may be a useful means of evaluating.

• The KIPS Transactions:PartB
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• v.19B no.2
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• pp.99-106
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• 2012

The purpose of this study was to determine the evaluation parameters' osteoporosis predictability in accordance with measuring regions by analyzing the correlations between bone mineral density and trabecular patterns derived from different measuring regions. Experimental subjects were a total of 40 female patients after menopause aged over 40 years, and were classified into 20 control and 20 osteoporotic groups according to the T-score. Bone mineral density was measured on femoral neck, trochanter and ward's triangle by DEXA(Dual Energy X-ray Absorptiometry). We designated ROI(Region of Interest) with $50{\times}50$ pixel size on each measuring regions, and extracted trabecular patterns by using existing image processing method. We also selected a total of eight evaluation parameters that are categorized into structural(mean gray level, area, perimeter, thickness and terminal distance), skeletonized parameters(number, length) and fractal dimension. As a result, it was observed that area, perimeter, thickness, terminal distance, number, length and fractal dimension reflected the bone mineral density with high statistical validity(p<0.003). We also confirmed that the evaluation parameters could predict the osteoporosis more efficiently.

• Journal of Chest Surgery
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• v.48 no.1
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• pp.33-39
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• 2015

Background: This study aimed to investigate sternal healing over time and the incidence of poor sternal healing in patients undergoing coronary artery bypass graft (CABG) surgery using bilateral internal thoracic arteries. Methods: This study enrolled 197 patients who underwent isolated CABG using skeletonized bilateral internal thoracic arteries (sBITA) from 2006 through 2009. Postoperative computed tomography (CT) angiography was performed on all patients at monthly intervals for three to six months after surgery. In 108 patients, an additional CT study was performed 24 to 48 months after surgery. The axial CT images were used to score sternal fusion at the manubrium, the upper sternum, and the lower sternum. These scores were added to evaluate overall healing: a score of 0 to 1 reflected poor healing, a score of 2 to 4 was defined as fair healing, and a score of 5 to 6 indicated complete healing. Medical records were also retrospectively reviewed to identify perioperative variables associated with poor early sternal healing. Results: Three to six months after surgery, the average total score of sternal healing was $2.07{\pm}1.52$ and 68 patients (34.5%) showed poor healing. Poor healing was most frequently found in the manubrium, which was scored as zero in 72.6% of patients. In multivariate analysis, the factors associated with poor early healing were shorter post-surgery time, older age, diabetes mellitus, and postoperative renal dysfunction. In later CT images, the average sternal healing score improved to $5.88{\pm}0.38$ and complete healing was observed in 98.2% of patients. Conclusion: Complete sternal healing takes more than three months after a median sternotomy for CABG using sBITA. Healing is most delayed in the manubrium.

• Journal of Korean Tunnelling and Underground Space Association
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• v.24 no.6
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• pp.513-524
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• 2022

Recently, detecting damages of civil infrastructures from digital images using deep learning technology became a very popular research topic. In order to adapt those methodologies to the field, it is essential to explain robustness of deep learning models. Our research points out that the existing pixel-based deep learning model evaluation metrics are not sufficient for detecting cracks since cracks have linear appearance, and proposes a new evaluation methodology to explain crack segmentation deep learning model more rationally. Specifically, we design, implement and validate a methodology to generate tolerance buffer alongside skeletonized ground truth data and prediction results to consider overall similarity of topology of the ground truth and the prediction rather than pixel-wise accuracy. We could overcome over-estimation or under-estimation problem of crack segmentation model evaluation through using our methodology, and we expect that our methodology can explain crack segmentation deep learning models better.

• Journal of Chest Surgery
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• v.36 no.10
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• pp.728-733
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• 2003

Background: The aim of the current study was to assess the effects of total arterial myocardial revascularization (TAMR) with bilateral internal mammary arteries. Material and Method: 139 consecutive patients who underwent off pump coronary artery bypass surgery from January 2000 to December 2001 were included in the current retrospective study. Patients were divided into those receiving bilateral internal mammary artery, BITA (n=85) and those receiving single internal mammary artery, SITA (n=54). Result: There was only one death in each group. No significant differences were noted in the total ICU and hospital stay; 2.4$\pm$1.7 and 11.2$\pm$17.7 days, in the BITA group, respectively and 2.8$\pm$2.7 and 9.7$\pm$7.1 days in the SITA group, respectively (P>0.05). The mean number of distal anastomosis of 3.9$\pm$0.7 was slightly higher in the SITA group compared to the SITA group, which was 3.1$\pm$0.8. Myocardial infarction occurred in 7 patients (BITA group: 2, SITA group: 5) and deep sternal infection necessitating reoperation occurred in 4 patients (BITA group: 3, SITA group: 1). Coronary angiogram was performed in the immediate postoperative period in 104 patients (BITA group: 64/85, SITA group: 40/54). Of these patients, stenosis in the LAD anastomosis site occurred in 4 patients (BITA group: 2, SITA group: 2). A total of 8 anastomotic sites were stenotic in the entire series of which percutaneous intervention was performed in 3 patients and none required reoperative coronary artery bypass. Conclusion: The results of the current data did not show a significant difference in patiency rate with bilateral internal mammary artery use for CABG supporting the feasibility of its use as a viable alternative method for TAMR.

• (The) Research of the performance art and culture
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• no.37
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• pp.157-186
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• 2018

Ulsan Soeburi song was reenacted in the 1980s based on the testimony and songs of late Choi Jae man (1987 death), the last blacksmith of the iron production plant at Dalcheon dong, Ulsan in August 1981. The purpose of this study is to analyze Soeburi song from the musical perspective based on 13 kinds of data including video in 1981, and confirm the changing patterns in the tradition process. The derived results are summarized as follows. In the results of examining Soeburi Song data in 2017, the percussion instruments consist of kkwaenggwari 2 (leading small gong 1, follow small gong 1), jing 2 (large gong 2), buk 4 (drum 4), janggu 4 (double headed drum 4), taepyongso 1 (Korean shawm 1), and Jangdan (rhythm) consists of five such as Jilgut, Jajinmori, Dadeuraegi, Deotbaegi, Jajin Deotbaegi. The vocal songs are sung accompanied by the Deotbaegi Jajin Deotbaegi (beat) of quarter small triplet time, or without accompaniment. The scale is mostly Mi La do's third note or Mi La do re's fourth note, and the range does not exceed one octave. All the cadence tones are the same as La. From the results of observing Soeburi song performance until today after the excavation in 1981, it is found that there are four major changes. First, the composition of the music is differentiated into 'long Jajin (slow fast)', and , , and are added. Second, the singing method is based on 'single cantor + multi post singers' since 1980's reenactment, and a single post singer was also specified from time to time. In addition, , which was performed in 2013, became the foundation of . Third, a melodic change of was observed. All beat structures are quarter small triplet time, but the speed gets slow, Mi La do's three notes are skeletonized to be corrected with high re and low sol, and then the characteristics of Menari tori (the mode appeared in the eastern province of the Korean peninsula) are to be clear. Lastly, the four percussion instruments such as kkwaenggwari, jing, janggu, and buk are frequently used, and depending on the performance, sogo (hand drum), taepyongso, yoryeong (bell) are also added. Jangdan played Jajinmori, Dadeuraegi, Deotbaegi and Jajin Deotbaegi from the beginning, and thereafter, the Jilgut Jangdan was added. Through these results as above, it is confirmed that at the time of the first excavation, a simple form of such as has been changed into a male labor song, the purpose of which has changed, and that the playability has become stronger and changed into a performing arts.