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Comparison of screw-in effect of three NiTi file systems used by undergraduates (학생들이 사용한 세 종류 NiTi file systems의 screw-in effect 비교)

  • Oh, Seung-Hei;Park, Jeong-Kil;Hur, Bock;Kim, Hyeon-Cheol
    • Restorative Dentistry and Endodontics
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    • v.31 no.6
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    • pp.477-484
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    • 2006
  • The purposes of this study were to compare the apical terminus width of simulated curved root canal prepared with three NiTi file systems used by undergraduates for evaluation the effects of flute angle and pitch or radial land on reducing screw-in effect and to determine more safe NiTi file system for inexperienced operators. Fifty inexperienced undergraduate students prepared 150 simulated curved root canals in resin blocks with three NiTi file systems ; ProFile$^{(R)}$, Hero Shaper$^{(R)}$, K3$^{TM}$. The electric motor set at a speed of 300 rpm and torque of 30 in a 16 : 1 reduction handpiece was used. The simulated root canal was prepared to ISO #25 sizes with each file system. The scanned images of pre- and post-instrumented canal of resin block were superimposed. To evaluate the screw-in effect of three NiTi file systems, apical terminus width of root canal was measured from superimposed images and statistical analysis was performed. There were significant differences in three NiTi flle systems. ProFile$^{(R)}$ had significantly smaller width than Hero Shaper$^{(R)}$ and K3$^{TM}$"" (P < 0.05), but no significant difference was observed between K3$^{TM}$ and Hero Shaper$^{(R)}$. Under the condition of this study, active file system (Hero SHaper$^{(R)}$, K3$^{TM}$) with variable pitch and helical angle had more screw-in effect than passive file system (ProFile$^{(R)}$) with constant pitch and helical angle. It seems that the radial lands play more important role in reducing screw-in effect.

Evaluation of the accuracy of two different surgical guides in dental implantology: stereolithography fabricated vs. positioning device fabricated surgical guides (제작방법에 따른 임플란트 수술 가이드의 정확성비교: stereolithography와 positioning device로 제작한 수술 가이드)

  • Kwon, Chang-Ryeol;Choi, Byung-Ho;Jeong, Seung-Mi;Joo, Sang-Dong
    • The Journal of Korean Academy of Prosthodontics
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    • v.50 no.4
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    • pp.271-278
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    • 2012
  • Purpose: Recently implant surgical guides were used for accurate and atraumatic operation. In this study, the accuracy of two different types of surgical guides, positioning device fabricated and stereolithography fabricated surgical guides, were evaluated in four different types of tooth loss models. Materials and methods: Surgical guides were fabricated with stereolithography and positioning device respectively. Implants were placed on 40 models using the two different types of surgical guides. The fitness of the surgical guides was evaluated by measuring the gap between the surgical guide and the model. The accuracy of surgical guide was evaluated on a pre- and post-surgical CT image fusion. Results: The gap between the surgical guide and the model was $1.4{\pm}0.3mm$ and $0.4{\pm}0.3mm$ for the stereolithography and positioning device surgical guide, respectively. The stereolithography showed mesiodistal angular deviation of $3.9{\pm}1.6^{\circ}$, buccolingual angular deviation of $2.7{\pm}1.5^{\circ}$ and vertical deviation of $1.9{\pm}0.9mm$, whereas the positioning device showed mesiodistal angular deviation of $0.7{\pm}0.3^{\circ}$, buccolingual angular deviation of $0.3{\pm}0.2^{\circ}$ and vertical deviation of $0.4{\pm}0.2mm$. The differences were statistically significant between the two groups (P<.05). Conclusion: The laboratory fabricated surgical guides using a positioning device allow implant placement more accurately than the stereolithography surgical guides in dental clinic.

THE EFFECTIVENESS OF TWO SEDATIVE REGIMEN USED FOR CHILD PATIENT WHO FAILED TO ORAL CHLORAL HYDRATE (Chloral hydrate 경구 진정에 실패한 소아환자를 대상으로 사용한 두 가지 진정요법의 효과)

  • Lee, Sang-Min;Kim, Jong-Soo;Kim, Yong-Kee
    • Journal of the korean academy of Pediatric Dentistry
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    • v.27 no.4
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    • pp.505-516
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    • 2000
  • Chloral hydrate is one of the most widely used sedative agents to control the difficult-to-treat young age group in the dental clinic. We are often frustrated to see the patient still awake and cry with agitation even after far more than the normal onset time of Chloral hydrate. In such a case, the patient has to be rescheduled for another sedation visit with different agents and/or routes which greatly disappoints the guardians. This study was designed to test the efficacy of one sedative regimen that can possibly help the clinician complete scheduled treatment without postponement. We have tried sleep induction with mixed gas of Enflurane(2vol%) and $N_2O(50%)-O_2(50%)$ for $60\sim120$ seconds to 35 patients of those who failed to respond properly to the dose(70mg/kg)of oral Chloral hydrate. The Result of this regimen was compare to those of two oral regimen of Chloral hydrate/Hydroxyzine and Chloral hydrate only Analyses of result on vital signs and behavior pattern were performed. The outcome of the study suggest that sleep induction by a short inhalation of low dose of $Enflurane/N_2O-O_2$ provide dentist with suitable condition for the completion of scheduled treatment in the patient who failed to oral Chloral hydrate. Evidence of adverse effect was not detected or reported during and/or after the procedures.

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Effects of Beverage Using Herbs on the Antimicrobial, Anticancer and Antiallergy Activities (약초 음료의 항균효과, 항암효과 및 알레르기 억제효과 검증)

  • Park, Eun-Mi;Ye, Eun-Ju;Kim, Soo-Jung;Kim, Sol-Ah;Bae, Man-jong
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.34 no.7
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    • pp.953-958
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    • 2005
  • This study was conducted to investigate the effect of beverage (beverage HC and beverage PG) using herbs on antimicrobial activity, proliferation of hepatic cancer cell (Hep3B) lines and sarcoma 180 (S-180) and antiallergy, respectively. Beverage PG showed higher antimicrobial activity than beverage HC against Staphylococcus aureus and Pseudomonas aeruginosa. Beverage HC and PG showed the tumor suppressive effect in mice injected with S-180 cells. The growth-inhibitoy ratio against tumor cells were $66\%\;for\;10\%$ beverage HC, $61\%\;for\;10\%$ beverage PG. In an anti-cancer test using Hep3B cells, beverage PG showed higher anti-proliferating effect than beverage HC. Beverage PG showed growth-inhibitory effect of $69.2\%\;at\;100\%$ beverage PG. Beverage PG inhibited histamine release from rat peritoneal mast cells (RPMC) activated by compound 48/80. In conclusion, these results suggest that beverage using herbs have an antimicrobial activity, anti-proliferating effect against Hep3B cell and S-180 tumor and will be beneficial in treatment of allergic reaction.

Comparison of Service Quality between Local and Global Coffee Brand Shops (국내와 국외브랜드 커피전문점의 서비스품질 비교)

  • Ryu, Si-Hyun;Lee, Ju-Young;Kim, Dong-Gun
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.40 no.8
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    • pp.1164-1171
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    • 2011
  • The purpose of this study was to compare service quality between local and global coffee brand shops and to investigate improvement. Of 350 questionnaires distributed to customers of six brand coffee shops (three local brands, three global brands) located in Daejeon, 330 complete questionnaires (94.3%) were analyzed. The questionnaire included a seven-point multiple-item scale for measuring service quality. The 21 items measuring service quality were grouped into four factors, and the mean scores for the levels of "representativeness", "coffee sensory and beverage features", "employee attitude" and "physical environment" were 5.42, 4.77, 4.74, and 4.13, respectively. The levels of "coffee sensory and beverage features" and "employee attitude" of the high income customers were significantly lower than those of the low income customers. The results showed that the levels of "employee attitude" of local coffee brand shops was significantly higher (p=0.050) than that of global coffee brand shops. Whereas, the levels of "representativeness" of global coffee brand shops was significantly higher (p=0.003) than that of local coffee brand shops. Based on the results, the global coffee brand shops should pay attention to internal marketing and the local coffee brand shops must strive to improve service quality through strategies such as improving brand awareness and developing representative beverages and foods.

Study on Climate Change Impacts on Hydrological Response using a SWAT model in the Xe Bang Fai River Basin, Lao People's Democratic Republic (기후변화에 따른 라오스인민공화국의 시방파이 유역의 수문현상 예측에 대한 연구: SWAT 모델을 이용하여)

  • Phomsouvanh, Virasith;Phetpaseuth, Vannaphone;Park, Soo Jin
    • Journal of the Korean Geographical Society
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    • v.51 no.6
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    • pp.779-797
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    • 2016
  • A calibrated hydrological model is a useful tool for quantifying the impacts of the climate variations and land use/land cover changes on sediment load, water quality and runoff. In the rainy season each year, the Xe Bang Fai river basin is provisionally flooded because of typhoons, the frequency and intensity of which are sensitive to ongoing climate change. Severe heavy rainfall has continuously occurred in this basin area, often causing severe floods at downstream of the Xe Bang Fai river basin. The main purpose of this study is to investigate the climate change impact on river discharge using a Soil and Water Assessment Tool (SWAT) model based on future climate change scenarios. In this study, the simulation of hydrological river discharge is used by SWAT model, covering a total area of $10,064km^2$ in the central part of country. The hydrological model (baseline) is calibrated and validated for two periods: 2001-2005 and 2006-2010, respectively. The monthly simulation outcomes during the calibration and validation model are good results with $R^2$ > 0.9 and ENS > 0.9. Because of ongoing climate change, three climate models (IPSL CM5A-MR 2030, GISS E2-R-CC 2030 and GFDL CM3 2030) indicate that the rainfall in this area is likely to increase up to 10% during the summer monsoon season in the near future, year 2030. As a result of these precipitation increases, the SWAT model predicts rainy season (Jul-Aug-Sep) river discharge at the Xebangfai@bridge station will be about $800m^3/s$ larger than the present. This calibrated model is expected to contribute for preventing flood disaster risk and sustainable development of Laos

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Predicting the Performance of Recommender Systems through Social Network Analysis and Artificial Neural Network (사회연결망분석과 인공신경망을 이용한 추천시스템 성능 예측)

  • Cho, Yoon-Ho;Kim, In-Hwan
    • Journal of Intelligence and Information Systems
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    • v.16 no.4
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    • pp.159-172
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    • 2010
  • The recommender system is one of the possible solutions to assist customers in finding the items they would like to purchase. To date, a variety of recommendation techniques have been developed. One of the most successful recommendation techniques is Collaborative Filtering (CF) that has been used in a number of different applications such as recommending Web pages, movies, music, articles and products. CF identifies customers whose tastes are similar to those of a given customer, and recommends items those customers have liked in the past. Numerous CF algorithms have been developed to increase the performance of recommender systems. Broadly, there are memory-based CF algorithms, model-based CF algorithms, and hybrid CF algorithms which combine CF with content-based techniques or other recommender systems. While many researchers have focused their efforts in improving CF performance, the theoretical justification of CF algorithms is lacking. That is, we do not know many things about how CF is done. Furthermore, the relative performances of CF algorithms are known to be domain and data dependent. It is very time-consuming and expensive to implement and launce a CF recommender system, and also the system unsuited for the given domain provides customers with poor quality recommendations that make them easily annoyed. Therefore, predicting the performances of CF algorithms in advance is practically important and needed. In this study, we propose an efficient approach to predict the performance of CF. Social Network Analysis (SNA) and Artificial Neural Network (ANN) are applied to develop our prediction model. CF can be modeled as a social network in which customers are nodes and purchase relationships between customers are links. SNA facilitates an exploration of the topological properties of the network structure that are implicit in data for CF recommendations. An ANN model is developed through an analysis of network topology, such as network density, inclusiveness, clustering coefficient, network centralization, and Krackhardt's efficiency. While network density, expressed as a proportion of the maximum possible number of links, captures the density of the whole network, the clustering coefficient captures the degree to which the overall network contains localized pockets of dense connectivity. Inclusiveness refers to the number of nodes which are included within the various connected parts of the social network. Centralization reflects the extent to which connections are concentrated in a small number of nodes rather than distributed equally among all nodes. Krackhardt's efficiency characterizes how dense the social network is beyond that barely needed to keep the social group even indirectly connected to one another. We use these social network measures as input variables of the ANN model. As an output variable, we use the recommendation accuracy measured by F1-measure. In order to evaluate the effectiveness of the ANN model, sales transaction data from H department store, one of the well-known department stores in Korea, was used. Total 396 experimental samples were gathered, and we used 40%, 40%, and 20% of them, for training, test, and validation, respectively. The 5-fold cross validation was also conducted to enhance the reliability of our experiments. The input variable measuring process consists of following three steps; analysis of customer similarities, construction of a social network, and analysis of social network patterns. We used Net Miner 3 and UCINET 6.0 for SNA, and Clementine 11.1 for ANN modeling. The experiments reported that the ANN model has 92.61% estimated accuracy and 0.0049 RMSE. Thus, we can know that our prediction model helps decide whether CF is useful for a given application with certain data characteristics.

Effect of Cognitive Affordance of Interactive Media Art Content on the Interaction and Interest of Audience (인터랙티브 미디어아트 콘텐츠의 인지적 어포던스가 관람자의 인터랙션과 흥미에 미치는 영향)

  • Lee, Gangso;Choi, Yoo-Joo
    • KIPS Transactions on Software and Data Engineering
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    • v.5 no.9
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    • pp.441-450
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    • 2016
  • In this study, we investigate the effect of the level of cognitive affordance which explains an explicit interaction method on the interest of viewers. Viewer's recognition of the interaction method is associated with cognitive affordance as a matter of visual-perceptual exposure of the input device and viewer's cognition of it. The final goal of the research on affordance is to enhance the audience participation rather than the smooth interation. Many interactive media artworks have been designed with hiding the explicit explanation to the artwork due to worry that the explicit explanation may also hinder the induction of impressions leading the viewer to an aesthetic experience and the retainment of interest. In this context, we set up two hypotheses for study on cognitive affordance. First, the more explicit the explanation of interaction method is, the higher the viewer' understanding of interaction method is. Second, the more explicit the explanation of interaction method is, the lower the interest of the viewer is. An interactive media art work was manufactured with three versions which vary in the degree of visual-perceptual information suggestion and we analyzed the participation and interest level of audience in each version. As a result of the experiments, the version with high explicitness of interaction was found to have long time spent on watching and high participation and interest of viewers. On the contrary, the version with an unexplicit interaction method was found to have low interest and satisfaction of viewers. Therefore, regarding usability, the hypothesis that a more explicit explanation of interaction would lower the curiosity and interest in exploration of the viewer was dismissed. It was confirmed that improvement of cognitive affordance raised the interaction of the work of art and interest of the viewer in the proposed interactive content. This study implies that interactive media art work should be designed in view of that the interaction and interest of audience can be lowered when cognitive affordance is low.

The Feasibility Study of MRI-based Radiotherapy Treatment Planning Using Look Up Table (Look Up Table을 이용한 자기공명영상 기반 방사선 치료계획의 타당성 분석 연구)

  • Kim, Shin-Wook;Shin, Hun-Joo;Lee, Young-Kyu;Seo, Jae-Hyuk;Lee, Gi-Woong;Park, Hyeong-Wook;Lee, Jae-Choon;Kim, Ae-Ran;Kim, Ji-Na;Kim, Myong-Ho;Kay, Chul-Seung;Jang, Hong-Seok;Kang, Young-Nam
    • Progress in Medical Physics
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    • v.24 no.4
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    • pp.237-242
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    • 2013
  • In the intracranial regions, an accurate delineation of the target volume has been difficult with only the CT data due to poor soft tissue contrast of CT images. Therefore, the magnetic resonance images (MRI) for the delineation of the target volumes were widely used. To calculate dose distributions with MRI-based RTP, the electron density (ED) mapping concept from the diagnostic CT images and the pseudo CT concept from the MRI were introduced. In this study, the look up table (LUT) from the fifteen patients' diagnostic brain MRI images was created to verify the feasibility of MRI-based RTP. The dose distributions from the MRI-based calculations were compared to the original CT-based calculation. One MRI set has ED information from LUT (lMRI). Another set was generated with voxel values assigned with a homogeneous density of water (wMRI). A simple plan with a single anterior 6MV one portal was applied to the CT, lMRI, and wMRI. Depending on the patient's target geometry for the 3D conformal plan, 6MV photon beams and from two to five gantry portals were used. The differences of the dose distribution and DVH between the lMRI based and CT-based plan were smaller than the wMRI-based plan. The dose difference of wMRI vs. lMRI was measured as 91 cGy vs. 57 cGy at maximum dose, 74 cGt vs. 42 cGy at mean dose, and 94 cGy vs. 53 at minimum dose. The differences of maximum dose, minimum dose, and mean dose of the wMRI-based plan were lower than the lMRI-based plan, because the air cavity was not calculated in the wMRI-based plan. These results prove the feasibility of the lMRI-based planning for brain tumor radiation therapy.

Theoretical Research for Unmanned Aircraft Electromagnetic Survey: Electromagnetic Field Calculation and Analysis by Arbitrary Shaped Transmitter-Loop (무인 항공 전자탐사 이론 연구: 임의 모양의 송신루프에 의한 전자기장 반응 계산 및 분석)

  • Bang, Minkyu;Oh, Seokmin;Seol, Soon Jee;Lee, Ki Ha;Cho, Seong-Jun
    • Geophysics and Geophysical Exploration
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    • v.21 no.3
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    • pp.150-161
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    • 2018
  • Recently, unmanned aircraft EM (electromagnetic) survey based on ICT (Information and Communication Technology) has been widely utilized because of the efficiency in regional survey. We performed the theoretical study on the unmanned airship EM system developed by KIGAM (Korea Institute of Geoscience and Mineral resources) as part of the practical application of unmanned aircraft EM survey. Since this system has different configurations of transmitting and receiving loops compared to the conventional aircraft EM systems, a new technique is required for the appropriate interpretation of measured responses. Therefore, we proposed a method to calculate the EM field for the arbitrary shaped transmitter and verified its validity through the comparison with analytic solution for circular loop. In addition, to simulate the magnetic responses by three-dimensionally (3D) distributed anomalies, we have adapted our algorithm to 3D frequency-domain EM modeling algorithm based on the edge-FEM (finite element method). Though the analysis on magnetic field responses from a subsurface anomaly, it was found that the response decreases as the depth of the anomaly increases or the flight altitude increases. Also, it was confirmed that the response became smaller as the resistivity of the anomaly increases. However, a nonlinear trend of the out-of-phase component is shown depending on the depth of the anomaly and the used frequency, that makes it difficult to apply simple analysis based on the mapping of the magnitude of the responses and can cause the non-uniqueness problem in calculating the apparent resistivity. Thus, it is a prerequisite to analyze the appropriate frequency band and flight altitude considering the purpose of the survey and the site conditions when conducting a survey using the unmanned aircraft EM system.