• The Korean Journal of Applied Statistics
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• v.30 no.6
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• pp.993-1004
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• 2017

A stratified sampling method is generally used with a sample selected using the same sample weight in each stratum in order to improve the accuracy of the sampling survey estimation. However, the weight should be adjusted to reflect the response rate if the response rate is affected by the value of the variable of interest. It may be also more effective to adjust the weights by subdividing the stratum rather than using the same weight if the variable of interest has a linear relationship with the continuous auxiliary variables. In this study, we propose a method to increase the accuracy of estimation using an informative sampling design technique when the response rate is an exponential function of the variable of interest and the variable of interest has a linear relationship with the auxiliary variable. Simulation results show the superiority of the proposed method.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.9
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• pp.752-759
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• 2012

This paper presents a mission orbit design method for spacecraft which use the sun-synchronous and ground repeat orbits. In this work, we have proposed a new design procedure, "Nonlinear simulation-based numerical optimization technique" using the commercial S/W's such as STK (Satellite Tool kit) and Matlab, which are widely adopted S/W's in the area of orbital mechanics and engineering analysis. Inclusion of all the perturbation effects on the spacecraft not only can more precisely satisfy the mission requirements for sun-synchronicity and repeated ground track, and also operational requirements such as minimum change in the S/C local time, maximization of the contact time with a specified ground station, etc. can be appropriately considered. Design examples for LEO sun-synchronous mission are presented to demonstrate the usefulness of the proposed method in this paper.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.13 no.2
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• pp.1-11
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• 2014

In this paper, travel speed patterns were deducted based on historical DSRC travel speed data using Decision Tree technique to improve availability of the massive amount of historical data. These patterns were designed to reflect spatio-temporal vicissitudes in reality by generating pattern units classified by months, time of day, and highway sections. The study area was from Seoul TG to Ansung IC sections on Gyung-bu highway where high peak time of day frequently occurs in South Korea. Decision Tree technique was applied to categorize travel speed according to day of week. As a result, five different pattern groups were generated: (Mon)(Tue Wed Thu)(Fri)(Sat)(Sun). Statistical verification was conducted to prove the validity of patterns on nine different highway sections, and the accuracy of fitting was found to be 93%. To reduce travel pattern errors against individual travel speed data, inclusion of four additional variables were also tested. Among those variables, 'traffic condition on previous month' variable improved the pattern grouping accuracy by reducing 50% of speed variance in the decision tree model developed.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.45 no.5
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• pp.241-253
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• 2019

This study evaluated and compared the donor site morbidity following minimally invasive and conventional open harvesting of iliac bone for secondary alveolar bone grafting in cleft palate patients. A thorough electronic search of PubMed, Google Scholar, EMBASE, and an institutional library and manual search of various journals was done; Inclusion criteria: 1) full-text articles using a minimally invasive or conventional open harvesting technique for iliac bone for secondary alveolar grafting in cleft palate patients and 2) articles published between January 1, 2001 and June 30, 2017 and Exclusion criteria: 1) articles published in languages other than English, 2) case reports, case series, animal studies, in vitro studies, and letters to the editor, and 3) full-text article unavailable even after writing to the authors. Preliminary screening of 274 studies excluded 223 studies for not meeting the eligibility criteria. Of the remaining 51 studies, 19 were removed for being duplicates. Of the remaining 32 studies, 15 were excluded after reading the abstract. Of the 17 studies that were left, 2 were excluded because they were in a language other than English, and 2 were excluded because the study group did not mention cleft palate patients. Thus, 13 studies providing results for a total of 654 patients were included in this qualitative synthesis. Minimally invasive bone graft harvest techniques are better than the conventional open iliac bone harvest method because they offer shorter operative time, decreased requirement for pain medications, less pain on discharge, and a shorter hospital stay.

• Restorative Dentistry and Endodontics
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• v.47 no.2
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• pp.15.1-15.18
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• 2022

This review aimed to characterize the effect of direct restorative material types and adhesive protocols on marginal adaptation and the bond strength of the interface between the material and the proximal dentin/cementum. An electronic search of 3 databases (the National Library of Medicine [MEDLINE/PubMed], Scopus, and ScienceDirect) was conducted. Studies were included if they evaluated marginal adaptation or bond strength tests for proximal restorations under the cementoenamel junction. Only 16 studies met the inclusion criteria and were included in this review. These studies presented a high degree of heterogeneity in terms of the materials used and the methodologies and evaluation criteria of each test; therefore, only a descriptive analysis could be conducted. The included studies were individually evaluated for the risk of bias following predetermined criteria. To summarize the results of the included studies, the type of restorative material affected the test results, whereas the use of different adhesive protocols had an insignificant effect on the results. It could be concluded that various categories of resin-based composites could be a suitable choice for clinicians to elevate proximal dentin/cementum margins, rather than the open sandwich technique with resin-modified glass ionomers. Despite challenges in bonding to proximal dentin/cementum margins, different adhesive protocols provided comparable outcomes.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.49 no.3
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• pp.1-7
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• 2012

Recently, researches are studied in developing efficient techniques for accessing, querying, and managing XML documents which are frequently used in the Internet. In this paper, we propose a new method to cluster XML documents efficiently. An element of a XML document corresponds to a node of the corresponding tree and an inclusion relationship of the document corresponds to a relationship between parent and child node of the tree. Therefore, similar XML documents are similar to the node's name and level of the corresponding trees. We make evaluation function with this characteristic to cluster XML documents by genetic algorithm. The experiment shows that our proposed method has better performance than other existing methods.

• Structural Engineering and Mechanics
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• v.73 no.6
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• pp.715-724
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• 2020

The influence on flexural strength of Glass/Epoxy laminated composite curved panels of different geometries (cylindrical, spherical, elliptical, hyperboloid and flat) due to inclusion of nano cenosphere filler examined in this research article. The deflection responses of the hybrid structure are evaluated numerically using the isoparametric finite element technique and modelled mathematically via higher-order displacement structural kinematics. To predict the deflection values, a customised in-house computer code in MATLAB environment is prepared using the higher-order isoparametric formulation. Subsequently, the numerical model validity has been established by comparing with those of available benchmark solution including the convergence characteristics of the finite element solution. Further, a few cenosphere filled hybrid composite are prepared for different volume fractions for the experimental purpose, to review the propose model accuracy. The experimental deflection values are compared with the finite element solutions, where the experimental elastic properties are adopted for the computation. Finally, the effect of different variable design dependent parameter and the percentages of nano cenosphere including the geometrical shapes obtained via a set of numerical experimentation.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.5
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• pp.2027-2029
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• 2015

Background: Laparoscope-assisted gastrectomy in treating patients with gastric cancers developed with a background of highly invasive traditional surgery and is being increasingly performed in the Asian Pacific area. This study systemically investigated the technique and clinical results for comparison with traditional radical subtotal gastrectomy for gastric cancers. Methods: Clinical studies evaluating the effectiveness and side effects of laparoscope-assisted gastrectomy in treating patients with gastric cancers were identified using a predefined search strategy. Summary rates of effectiveness and side effects of laparoscope-assisted gastrectomy were calculated. Results: Thirteen clinical studies which including 1,412 patients with gastric cancer treated by laparoscope-assisted gastrectomy were considered eligible for inclusion. Systemic analysis showed that, for all patients, the pooled resection rate was 100%. Major adverse effects were anastomotic stenosis, abdominal abscess, abdominal bleeding, postoperative ileus. Treatment related death occurred in 0. 71% (10/1412). Conclusion: This systemic analysis suggests that laparoscope-assisted gastrectomy in treating patients with gastric cancers is associated with good curative rate and acceptable complications.

• Archives of Plastic Surgery
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• v.45 no.2
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• pp.158-164
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• 2018

Background During breast augmentation, the transaxillary approach provides the advantage of allowing the mammary prosthesis to be placed through incisions that are remote from the breast itself, thereby reducing the visibility of postoperative scars. For patients experiencing capsular contracture who do not want additional scars, the previous transaxillary scar can be used for site change and implant exchange. Methods This study analyzed 17 patients (34 breasts) with submuscular breast implants with grade III-IV capsular contracture who received treatment from 2010 to 2015. The mean age of the patients was 29 years (range, 20-38 years). The inclusion criterion was a pinch test of more than 3 cm at the upper pole of the breast. Previous axillary scars were used to expose the pectoralis fascia, and submuscular breast implants were removed carefully. The dissection underneath the pectoralis fascia was performed with endoscopic assistance, using electrocautery under direct visualization. Results The mean follow-up period was 14 months (range, 6-24 months). The entire dissection plane was changed from the submuscular plane to the subfascial plane. Round textured gel implants were used, with a mean implant size of 220 mL (range, 160-300 mL). Two patients developed grade II capsular contracture. There were no cases of malposition or asymmetry. Three patients complained of minor implant palpability. None of the patients required additional surgery. Conclusions Endoscopic subfascial conversion may be an effective technique for treating capsular contracture and avoiding scarring of the breast in selected patients.

• Advances in nano research
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• v.8 no.4
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• pp.265-276
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• 2020

A study that primarily focuses on nonlocal strain gradient plate model for the sole purpose of vibration examination, for graphene sheets under linearly variable in-plane mechanical loads. To study a better or more precise examination on graphene sheets, a new advance model was conducted which carries two scale parameters that happen to be related to the nonlocal as well as the strain gradient influences. Through the usage of two-variable shear deformation plate approach, that does not require the inclusion of shear correction factors, the graphene sheet is designed. Based on Hamilton's principle, fundamental expressions in regard to a nonlocal strain gradient graphene sheet on elastic half-space is originated. A Galerkin's technique is applied to resolve the fundamental expressions for distinct boundary conditions. Influence of distinct factors which can be in-plane loading, length scale parameter, load factor, elastic foundation, boundary conditions, and nonlocal parameter on vibration properties of the graphene sheets then undergo investigation.