• Imaging Science in Dentistry
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• 제46권1호
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• pp.9-16
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• 2016

Purpose: To evaluate the upper airway dimensions of obstructive sleep apnea (OSA) and control subjects using a cone-beam computed tomography (CBCT) unit commonly applied in clinical practice in order to assess airway dimensions in the same fashion as that routinely employed in a clinical setting. Materials and Methods: This was a retrospective analysis utilizing existing CBCT scans to evaluate the dimensions of the upper airway in OSA and control subjects. The CBCT data of sixteen OSA and sixteen control subjects were compared. The average area, average volume, total volume, and total length of the upper airway were computed. Width and anterior-posterior (AP) measurements were obtained on the smallest axial slice. Results: OSA subjects had a significantly smaller average airway area, average airway volume, total airway volume, and mean airway width. OSA subjects had a significantly larger airway length measurement. The mean A-P distance was not significantly different between groups. Conclusion: OSA subjects have a smaller upper airway compared to controls with the exception of airway length. The lack of a significant difference in the mean A-P distance may indicate that patient position during imaging (upright vs. supine) can affect this measurement. Comparison of this study with a future prospective study design will allow for validation of these results.

• 한국산학기술학회논문지
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• 제10권7호
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• pp.1621-1630
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• 2009

최근에 P2P 기반의 분산 환경에서 동적인 분산 콘텐츠 서비스를 제공하기 위한 많은 연구가 수행되고 있다. 그러나 콘텐츠 객체들의 분산 서비스를 위해서는 QoS 문제와 세그먼트의 동적 관리 문제가 발생되고 있다. 본 논문에서는 P2P 기반의 분산 콘텐츠 서비스를 위한 새로운 세그먼트 관리기법을 제안한다. 제안된 기법은 SGM(Segment Group Manager)를 통하여 그룹을 관리하게 되며, 이 구조는 P2P상에서 서비스가 수행되는 세그먼트들을 결정하여 스트리밍을 효율적으로 관리하게 된다. 이때 같은 그룹으로 구성된 세그먼트들은 비슷한 네트워크 조건하에서 효율적인 QoS를 수행하기 위하여 상호 협력한다. 이러한 기능은 거리기반 관리구조와 관계성 기반 관리구조에 의해서 수행된다. 거리기반 관리구조는 검색효율을 개선하기 위한 관리 기법이고, 관계성 기반 관리구조는 세그먼트의 서비스율을 개선하기 위한 기법이다. 제안된 기법의 시뮬레이션 결과 평균 검색시간이 TPD(Truncated Pareto Distribution)기법에 비해서 8%, 랜덤 기법에 비해서는 30%가 개선되었고, 세그먼트의 서비스율은 10% ${\sim}$30% 개선되었음을 알 수 있다.

• The Journal of Advanced Prosthodontics
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• 제14권1호
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• pp.32-44
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• 2022

PURPOSE. Mandibular flexure is a crucial phenomenon that may affect the success of rigid bilateral mandibular prosthetic treatment. The aim of this study was to determine the amount of median mandibular flexure (MMF) that occurs during mouth opening from anterior to posterior mandible in seven different regions, in different age and gender groups of both dentulous and edentulous subjects, using an intraoral digital scanner. MATERIALS AND METHODS. In this study, the mandibular arch of 56 dentulous and 35 edentulous individuals were scanned with an intraoral scanner at both the minimum mouth opening (MnMO) and the maximum mouth opening (MxMO). MMF values were calculated by subtracting the distance value at the MxMO from the distance between the reference points at the MnMO at seven different mandibular regions of dentulous and edentulous subjects. In addition, the left and right side MMF values were measured. All data were analyzed statistically (α = .05). RESULTS. MMF value increased linearly from anterior to posterior mandible in both dentulous and edentulous individuals. The differences in MMF values were not statistically significant according to side (left/right), age, or gender (P > .05). No significant differences were found between the mean MMF values of the same region in both dentulous and edentulous individuals (P > .05). CONCLUSION. MMF was seen in different regions of the mandibles of both edentulous and dentulous individuals measured at the MxMO. Mandibular flexure should be considered for the success and prognosis of the long-span and rigid prostheses.

• 유통과학연구
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• 제14권1호
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• pp.67-74
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• 2016

Purpose - In this paper, the degree of similarity and dissimilarity between pairs of 50 major cities in China can be shown on the basis of three evaluation variables(internet businessman index, internet shopping index and e-commerce development index). Dissimilarity distance matrix is used to analyze both similarity and dissimilarity between each fifty city in China by calculating dissimilarity as distance. Higher value signifies higher degree of dissimilarity between two cities. Cluster analysis is exploited to classify 50 cities into a number of different groups such that similar cities are placed in the same group. In addition, multidimensional scaling(MDS) technique can obtain visual representation for exploring the pattern of proximities among 50 major cities in China based on three development performance attributes. Research design, data, and methodology - This research is performed by the 2013 report provided with AliResearch in China(1/1/2013~11/30/2013) and utilized multivariate methods such as dissimilarity distance matrix, cluster analysis and MDS by using CLUSTER, KMEANS, PROXIMITIES and ALSCAL procedures in SPSS 21.0. Results - This research applies two types of cluster analysis and MDS on three development performances based on the 2013 report of Aliresearch. As a result, it is confirmed that grouping is possible by categorizing the types into four clusters which share similar characteristics. MDS is exploited to carry out positioning of both grouped locations of cluster and 50 major cities belonging to each cluster. Since all the values corresponding to Shenzhen, Guangzhou and Hangzhou(which belong to cluster 1 among 50 major cities) are very large, these cities are superior to other cities in all three evaluation attributes. Twelve cities(Beijing, ShangHai, Jinghua, ZhuHai, XiaMen, SuZhou, NanJing, DongWan, ZhangShan, JiaXing, NingBo and FoShan), which belong to cluster 3, are inferior to those of cluster 1 in terms of all three attributes, but they can be expected to be the next e-commerce revolution. The rest of major cities, in particular, which belong to cluster 4 are relatively inferior in all three attributes, so that this automatically evokes creative innovation, which leads to e-commerce development as a whole in China. In terms of internet businessman index, on the other hand, Tainan, Taizhong, and Gaoxiong(which belong to cluster 2) are situated superior to others. However, these three cities are inferior to others in an internet shopping index sense. The rest of major cities, in particular, which belong to cluster 4 are relatively inferior in all three evaluation attributes, so that this automatically evokes innovation and entrepreneurship, which leads to e-commerce development as a whole in China. Conclusions - This study suggests the implications to help e-governmental officers and companies make strategies in both Korea and China. This is expected to give some useful information in understanding the recent situation of e-commerce in China, by looking over development performances of 50 major cities. Therefore, we should develop marketing, branding and communication relevant to online Chinese consumers. One of these efforts will be incentives like loyalty points and coupons that can encourage consumers and building in-house logistics networks.

• 유통과학연구
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• 제14권6호
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• pp.81-87
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• 2016

Purpose - In recent, a research finds that advanced selling can influence a consumer's choice(Kim et al., 2013). Advanced selling is defined as the new product launching strategy which company allows consumers to preorder new product before its release(Chu & Zhang, 2011). Prior researches have focused on the benefits of advanced selling(e.g., information gathering for demand prediction, an advantage for pricing strategy, and so on) for companies using this strategy(Chen, 2001; Chu & Zhang, 2011; Li & Zhang, 2013; Tang et al., 2004; Xie & Shugan, 2009). However, Kim et al.(2013) find it can also influence a consumer's choice. In detail, they suggest that when consumers use advanced selling, they are likely to prefer high-performance options rather than low-price options based on construal level theory(Trope & Liberman, 2003). In this paper, we tried to expand the prior researches for finding the mechanism of the influence of advanced selling on a consumer's choice. The purpose of this research is to test the mediating effect on the influence of advanced selling. Research design, data, and methodology - To find the mechanism of the influence of advanced selling, we designed an experiment for testing mediation effect. we recruited 93 students from a university. We assigned participants into one of two groups using randomization method. The participants with each group were given a scenario describing the sales strategy. Finally, they made a choice between high-performance option and low-price option. Sequentially, they also responded some questions for testing mediation effect. Results - First, we replicated prior research to test the influence of advanced selling. As a result, we could find that consumers prefer the high-performance option when they preorder it to purchase at the time of consumption. Thus, the replication result is the same as prior research. Second, we tested that advanced selling can influence the perception of temporal distance. The results confirmed that consumers perceived longer temporal distance in advanced selling condition(β = 1.575, SE = 0.272, p < 0.001). Third, we predicted that temporal distance can increase the importance of desirable attributes and decrease the importance of feasible attributes. The results suggested that temporal distance decreased significantly the importance of attributes related to feasibility(β = -0.19, SE = 0.07, p < 0.01), however, it had non-significant effect on increasing the importance of desirable attributes. Finally, we used Sobel-test for testing mediation effect, and it confirmed that the importance of feasible attributes had mediating role of the influence of advanced selling(Sobel test statistic = -2.110, SE = 0.111, p < 0.05). Conclusions - In this paper, we tried to find the mechanism of the influence on advanced selling from a consumer's choice. With an experiment, we confirmed that the importance of feasible attributes could mediate the effect on advanced selling. Therefore, we suggested some theoretical and practical contributions from this research. Finally, we discussed research limitations and suggested future research topics.

• Computers and Concrete
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• 제18권3호
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• pp.337-354
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• 2016

To study the influence on fracture properties of reinforced concrete wedge splitting test specimens by the addition of reinforcement, and the restriction of steel bars on crack propagation, 7 groups reinforced concrete specimens of different reinforcement position and 1 group plain concrete specimens with the same size factors were designed and constructed for the tests. Based on the double-K fracture criterion and tests, fracture toughness calculation model which was suitable for reinforced concrete wedge splitting tensile specimens has been obtained. The results show that: the value of initial craking load Pini and unstable fracture load Pun decreases gradually with the distance of reinforcement away from specimens's top. Compared with plain concrete specimens, addition of steel bar can reduce the value of initial fracture toughness KIini, but significantly increase the value of the critical effective crack length ac and unstable fracture toughness KIun. For tensional concrete member, the effect of anti-cracking by reinforcement was mainly acted after cracking, the best function of preventing fracture initiation was when the steel bar was placed in the middle of the crack, and when the reinforcement was across the crack and located away from crack tip, it plays the best role in inhibiting the extension of crack.

• International Journal of Oral Biology
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• 제41권4호
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• pp.225-230
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• 2016

Inflammation from chronic and acute infections of distal organs and tissues such as periodontitis is a risk factor for atherosclerotic vascular processes. Recently, a new model of atherosclerosis with vascular pathologies was developed in the Mongolian gerbil. In this study, we attempted to develop a model of ligature-induced periodontitis in gerbils and compared the characteristics of that periodontitis model with that in rats and mice. Each gerbil, rat, and mouse was randomly assigned to groups of control and periodontitis. A thread was placed around the cervix of the right and left first molars in the mandible with knots placed on the mesial side of each molar. At day 14 after the ligation, the animals were sacrificed and their mandibles were dissected. To measure alveolar bone loss along with inflammation, histopathological and micro-CT analyses were carried out. Gerbils showed tooth characteristics of deeper gingival crevice, longer cusp, longer root trunk and shorter root than those of rats and mice. The increased CEJ-ABC distance in distal and PDL area in furcation was also observed in ligated gerbils. An inflammatory response in the connective tissue under the junctional epithelium was also shown in all the animals. As a result, we confirmed the induction of periodontitis by ligature in the gerbils. We therefore consider the gerbil to be a useful model for investigating relationship between periodontitis and vascular disease in the same animal.

• 대한기계학회논문집
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• 제12권1호
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• pp.81-94
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• 1988

본 연구에서는 표면상태가 다양한 고온면을 충돌온류에 의하여 냉각하는 방식이 광범위하게 응용되고 있는 점에 유의하여 표면조도, 노즐직경 및 분류속도를 변화시키고 노즐끝에 전열면의 직경과 동일한 원형판을 부착하여 비철액체를 막고 문극내에 온류액체를 강제유동시킴으로써 열전달에 미치는 모든 영향을 실험에 의해 고찰하고 고찰하고 포화수온류에 의한 열류속의 무차원관계식을 도출하는 것을 본 연구의 목적으로 하였다.

• 말소리와 음성과학
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• 제7권3호
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• pp.79-88
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• 2015

English vowels are difficult to teach and learn because both teachers and learners cannot show or see shapes of vocal tract inside their own mouth cavities. The aim of this study is to examine what kind of changes occur in production and perception of English vowels by college students before and after lessons in order to provide fundamental materials for teaching students English vowels. Fifteen volunteer female students attending an English phonetics course participated in the lessons for one and half a month period. Formant values of vowels produced and perceived before and after the lessons were obtained using Flying Popcorn and Praat. Results showed that a produced vowel space after the lessons was greater than that before the lessons with no significant difference. Distances between some adjacent corner vowels were too close to be distinguished. Secondly, perceived vowels before and after the lessons were almost the same. Here again, some adjacent vowels were closely spaced. Thirdly, three groups which were divided by the length of the distance between the vowel /i-${\ae}$/ showed similar patterns in their perception and production. Generally the vowel space expanded from [u] to [${\ae}$]. The author concluded that there was no drastic improvement of vowel perception and production within a short period of time. Further studies would be desirable to examine how successful any long-term English vowel lessons would be and which methods should be taken to evaluate students' achievements proposed here.

• 천문학논총
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• 제30권2호
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• pp.469-471
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• 2015

How galaxies are affected by their neighboring galaxies during galaxy-galaxy interactions is a long-standing question. We investigate the role of neighbors in galaxy pairs based on the SDSS data release 7 and the KIAS value-added galaxy catalog. Three groups of galaxies are identified: (a) galaxies with an early-type neighbor, (b) with a late-type neighbor, and (c) isolated ones with no neighbor. We compare their UV + optical colors and $H{\alpha}$ emission as indicators of the recent star-formation rate (SFR). Given that galaxies show systematic differences in SFR as functions of morphology, luminosity, and large-scale environments, we construct a control sample in which the galaxies have the same conditions (in terms of morphology, luminosity, and large-scale environment) except for the neighbor's properties (i.e., morphology, mass, and distance). The results are as follows. (1) Galaxies with a late-type companion demonstrate more enhanced SFR than those with an early-type companion. (2) Galaxies with an early-type neighbor show NUV- and u-band derived SFRs that are even lower than that of isolated galaxies, while they have similar or slightly higher $H{\alpha}$-based SFR compared to isolated ones.