• Journal of KIISE:Databases
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• v.31 no.4
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• pp.395-408
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• 2004

A conjunctive Boolean text query refers to a query that searches for tort documents containing all of the specified keywords, and is the most frequently used query form in information retrieval systems. Typically, the query specifies a long list of keywords for better precision, and in this case, the order of keyword processing has a significant impact on the query speed. Currently known approaches to this ordering are based on heuristics and, therefore, cannot guarantee an optimal ordering. We can use a systematic approach by leveraging a database query processing algorithm like the dynamic programming, but it is not suitable for a text query with a typically long list of keywords because of the algorithm's exponential run-time (Ο(n2$^{n-1}$)) for n keywords. Considering these problems, we propose a new approach based on a property called the join sequence separability. This property states that the optimal join sequence is separable into two subsequences of different join methods under a certain condition on the joined relations, and this property enables us to find a globally optimal join sequence in Ο(n2$^{n-1}$). In this paper we describe the property formally, present an optimization algorithm based on the property, prove that the algorithm finds an optimal join sequence, and validate our approach through simulation using an analytic cost model. Comparison with the heuristic text query optimization approaches shows a maximum of 100 times faster query processing, and comparison with the dynamic programming approach shows exponentially faster query optimization (e.g., 600 times for a 10-keyword query).

• Journal of KIISE:Databases
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• v.33 no.1
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• pp.12-31
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• 2006

The n-gram inverted index has two major advantages: language-neutral and error-tolerant. Due to these advantages, it has been widely used in information retrieval or in similar sequence matching for DNA and Protein databases. Nevertheless, the n-gram inverted index also has drawbacks: the size tends to be very large, and the performance of queries tends to be bad. In this paper, we propose the two-level n-gram inverted index (simply, the n-gram/2L index) that significantly reduces the size and improves the query performance while preserving the advantages of the n-gram inverted index. The proposed index eliminates the redundancy of the position information that exists in the n-gram inverted index. The proposed index is constructed in two steps: 1) extracting subsequences of length m from documents and 2) extracting n-grams from those subsequences. We formally prove that this two-step construction is identical to the relational normalization process that removes the redundancy caused by a non-trivial multivalued dependency. The n-gram/2L index has excellent properties: 1) it significantly reduces the size and improves the Performance compared with the n-gram inverted index with these improvements becoming more marked as the database size gets larger; 2) the query processing time increases only very slightly as the query length gets longer. Experimental results using databases of 1 GBytes show that the size of the n-gram/2L index is reduced by up to 1.9${\~}$2.7 times and, at the same time, the query performance is improved by up to 13.1 times compared with those of the n-gram inverted index.

• Journal of the korean academy of Pediatric Dentistry
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• v.48 no.1
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• pp.31-41
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• 2021

The aim of this retrospective study was to evaluate the correlation between the midpalatal suture maturation and skeletal maturation in growing children aged 7 - 15 years and predict the maturational stages of the midpalatal suture corresponding to skeletal maturity assessed by the skeletal maturation indicators (SMI) and middle phalanx of the third finger (MP3) stages. The group of this retrospective study was consisted of randomly selected 132 male and 135 female in age from 7 - 15 years. The maturation of the midpalatal suture was evaluated by using images from cone-beam computed tomography (CBCT) while the skeletal age was assessed by hand-wrist radiography. CBCT images and hand-wrist radiographs used in this study were obtained from all subjects for orthodontic diagnosis before orthodontic treatment. The maturational stages of the midpalatal suture showed strong correlations with both SMI and MP3 stages. The correlation between the midpalatal suture maturation and SMI (Spearman's correlation coefficient, ϒ_S = 0.905, p < 0.05) was slightly greater than that of MP3 stages (ϒ_S = 0.830, p < 0.05). There was a positive significant correlation between the midpalatal suture maturation and chronological age (ϒ_S = 0.868,p < 0.05). CBCT for evaluation of the midpalatal suture maturational stages may be unnecessary in every pediatric patients because SMI and MP3 stages were both replaceable useful methods for assessing maturation of the midpalatal suture before orthopedic treatment. In this retrospective study, the diagnostic reliability of the SMI method for estimating midpalatal suture maturation showed better reliability than the MP3 method.

• Korean Journal of Remote Sensing
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• v.38 no.6_2
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• pp.1663-1676
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• 2022

Recently, a number of deep-learning based land cover segmentation studies have been introduced. Some studies denoted that the performance of land cover segmentation deteriorated due to insufficient training data. In this study, we verified the improvement of land cover segmentation performance through data augmentation. U-Net was implemented for the segmentation model. And 2020 satellite-derived landcover dataset was utilized for the study data. The pixel accuracies were 0.905 and 0.923 for U-Net trained by original and augmented data respectively. And the mean F1 scores of those models were 0.720 and 0.775 respectively, indicating the better performance of data augmentation. In addition, F1 scores for building, road, paddy field, upland field, forest, and unclassified area class were 0.770, 0.568, 0.433, 0.455, 0.964, and 0.830 for the U-Net trained by original data. It is verified that data augmentation is effective in that the F1 scores of every class were improved to 0.838, 0.660, 0.791, 0.530, 0.969, and 0.860 respectively. Although, we applied data augmentation without considering class balances, we find that data augmentation can mitigate biased segmentation performance caused by data imbalance problems from the comparisons between the performances of two models. It is expected that this study would help to prove the importance and effectiveness of data augmentation in various image processing fields.

• Journal of Internet Computing and Services
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• v.23 no.4
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• pp.57-64
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• 2022

If the inside of a building collapses due to a disaster such as fire, collapse, or natural disaster, the physical security inside the building is likely to become ineffective. Here, physical security is needed to minimize the human casualties and physical damages in the collapsed building. Therefore, this paper proposes an algorithm to minimize the damage in a disaster situation by fusing existing research that detects obstacles and collapsed areas in the building and a deep learning-based object detection algorithm that minimizes human casualties. The existing research uses a single camera to determine whether the corridor environment in which the robot is currently located has collapsed and detects obstacles that interfere with the search and rescue operation. Here, objects inside the collapsed building have irregular shapes due to the debris or collapse of the building, and they are classified and detected as obstacles. We also propose a method to detect rescue requesters-the most important resource in the disaster situation-and minimize human casualties. To this end, we collected open-source disaster images and image data of disaster situations and calculated the accuracy of detecting rescue requesters in disaster situations through various deep learning-based object detection algorithms. In this study, as a result of analyzing the algorithms that detect rescue requesters in disaster situations, we have found that the YOLOv4 algorithm has an accuracy of 0.94, proving that it is most suitable for use in actual disaster situations. This paper will be helpful for performing efficient search and rescue in disaster situations and achieving a high level of physical security, even in collapsed buildings.

• Korean Journal of Veterinary Research
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• v.9 no.1
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• pp.23-62
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• 1969

Throughout the studies the following experimental results were obtained and are summarized: 1. Multiplication of agents in primary cell cultures of both GF classical and CR-64 acute strain of Marek's disease infected chicken kidneys was accompanied by the formation of distinct transformed cell foci. This characteristic nature of cell transformation was passaged regularly by addition of dispersed cell from infected cultures to normal chicken kidney cell cultures, and also transferred was the nature of cell transformation to normal chick-embryo liver and neuroglial cell cultures. No cytopathic changes were noticed in inoculated chick-embryo fibroblast cultures. 2. The same cytopathic effects were noticed in normal kidney cell monolayers after the inoculation of whole blood and huffy coat cells derived from both forms of Marek's disease infected chickens. In these cases, however, the number of transformed cell foci appearing was far less than that of uninoculated monolayers prepared directly from the kidneys of Marek's disease infected chickens. 3. The change in cell culture IS regarded as a specific cell transformation focus induced by an oncogenic virus rather than it plaque in slowly progressing cytopathic effect by non-oncogenic viruses, and it is quite similar to RSV focus in chick-embryo fibroblasts in many respects. 4. The infective agent (cell transformable) were extremely cell-associated and could not be separated in an infective state from cells under the experimental conditions. 5. The focus assay of these agents was valid as shown by the high degree of linear correlation (r=0.97 and 0.99) between the relative infected cell concentration (in inoculum) and the transformed cell foci counted. 6. No differences were observed between the GF classical strain and the CR-64 acute strain of Marek's disease as far as cell culture behavior. 7. Characterization of the isolates by physical and chemical treatments, development of internuclear inclusions in Infected cells, and nucleic acid typing by differential stainings and cytochemical treatments indicated that the natures of these cell transformation agents closely resemble to those described fer the group B herpes viruses. 8. Susceptible chicks inoculated with infected kidney tissue culture cells developed specific lesions of Marek's disease, and in a case of prolonged observation after inoculation (5 weeks) the birds developed clinical symptoms and gross lesions of Marek's disease. Kidney cell cultures prepared from those inoculated birds and sacrificed showed a superior recovery of cell transformation property by formation of distinct foci. 9. Electron microscopic study of infected kidney culture cells (GF agent) by negative staining technique revealed virus particles furnishing the properties of herpes viruses. The particle was measured about $100m{\mu}$ and, so far, no herpes virus envelop has been seen from these preparations. 10. No relationship of both isolates to avian leukosis/sarcoma group viruses and PPLO was observed.

• The Journal of the Korea Contents Association
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• v.10 no.6
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• pp.323-328
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• 2010

If a patient wearing arm sliding due to shoulder dislocation or fracture is impossible with abduction, the velpeau view is performed instead of superior-inferior axial projection view. However, it aggravates the patient's pain because it is difficult for the patient with dislocation or fracture to pull back the shoulders. Therefore, I suggest a new method of the 'modified velpeau view' that allows patients to lower their heads at examination. In order to investigate the easiness of fixing posture at examination and clinical utility, I conducted a study comparing the bone structures at the velpeau view and those at the modified velpeau view depending on wall-bucky and the patients' leaning forward angle ($30^{\circ},\;45^{\circ},\;60^{\circ}\;and\;75^{\circ}$), with the subjects of 20 velpeau view-prescribed patients amongst who had come to my hospital suspected of dislocation of shoulder or fracture and 30 healthy people from October of 2009 to January of 2010. Department of radiologists and orthopedics specialists evaluated the pictures for scales 0 to 5(best grade) under the given criteria. As a result of comparison in bone structures depending on wall-bucky and the leaning-forward angle in the group of healthy people, the velpeau view and the modified velpeau showed a similar diagnostic utility at $45^{\circ}$ and $60^{\circ}$. The picture evaluation result for proving diagnostic value showed that the anterior and posterior of shoulder heads and the anterior and posterior of glenoid fossa could be observed in the velpeau view; on the other hand, besides these areas acromioclavicular joint and coracoid process could be viewed in the modified velpeau view. This result verified that the modified velpeau view could replace the velpeau view for its diagnostic value as an examination method. This result, moreover, suggests that the modified velpeau view needs to be studied and improved from a variety of perspectives not only for an alternative for patients having troubles with the velpeau view position but also for clinical application of new test method for diagnosis of shoulder disorders other than dislocation of shoulder or fracture.

• Korean Journal of Microbiology
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• v.43 no.4
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• pp.298-303
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• 2007

Antithrombotic activities of water extract of cheongkookjang and cheongkookjang fermented with green tea or mugwort were evaluated on some antithrombosis related activities in vitro and thrombotic death inhibition in vivo. Cheongkookjang made of white soybean (Glycine max) or black small soybean (Rhynchosia nulubilis) showed potent antioxidative activities. Addition of green tea or mugwort during cheongkookjang fermentation increased the antioxidative activity, cheongkookjang with green tea showed more drastic increase compared with cheongkookjang with mugwort. Nitrite scavenging effects of the cheongkookjang extracts were prominent but the addition of green tea or mugwort seldom increased the scavenging effects. All the cheongkookjang extracts showed strong inhibitory activities on platelet aggregation. The inhibitory activities of cheongkookjang were increased considerably by addition of green tea or mugwort even with low concentration. Plasmin unit as fibrinolytic activity was not affected considerably by addition of green tea. Addition of mugwort decreased the activity transiently at low concentration ($0.3{\sim}1.0%$) but increased again slowly at higher concentration ($1{\sim}3%$). In vitro thrombotic death inhibition test, the antithrombotic activity of cheongkookjang made of black small bean with green tea was higher by about 1.5 times compared to that without green tea. As results, cheongkookjang might inhibit antithrombosis not only by fibrinolytic action but also by inhibition of platelet aggregation and antioxidative action. The addition of functional materials such as green tea or mugwort could increase the antithrombotic function, even at low concentration.

• Journal of Chest Surgery
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• v.34 no.12
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• pp.895-900
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• 2001

Background : This study aimed to evaluate the usefulness of preoperative placement of intraaortic balloon pump(IABP) in reducing operative risk and facilitating posterior vessel OPCAB in high risk patients with left main disease( 75％ stenosis), intractable resting angina, postinfarction angina, or left ventricular dysfunction(ejection fraction 35％). Material and Method : One hundred eighty- nine consecutive patients who underwent multi-vessel OPCAB including posterior vessel revascularization were studied. The patients were divided into group I(n=74) that received preoperative or intraoperative IABP and group II(n=115) that did not receive IABP. In group I, there were 39 patients with left main disease, 40 patients with intractable resting angina, 14 patients with left ventricular dysfunction and 7 patients with postinfarction angina. Ten patients received intraoperative IABP support due to hemodynamic instability during OPCAB. Result : There was one operative mortality in group I and two mortalities in group II. The average number of distal anastomoses was not different between group I and group II(3.5$\pm$0.9 vs 3.4$\pm$0.9, p=ns). There were no significant differences in the number of posterior vessel anastomosis per patient between the two groups. There were no differences in ventilator support time, length of hospital stay, and morbidity between the two groups. There was one case of IABP-related complication in group I. Conclusion : IABP facilitates posterior vessel OPCAB in high risk patients, with comparable surgical results to low risk patients