• The korean journal of orthodontics
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• v.28 no.5 s.70
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• pp.803-812
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• 1998

The purpose of this study was to evaluate the shear bond strength and failure mode of ceramic brackets according to the surface treatment of porcelain. Sixty Porcelain samples were randomly divided into six groups of ten samples. Then they were treated as follows: Group 1(silane only), Group 2(etching+silane), Group 3(stone+silane), Group 4(sandblasting+silane), Group 5(stone +etching+silane), Group 6(sandblasting+etching+silane) After surface treatment of porcelain, sixty Transcend 6000 brackets were bonded to the prepared porcelain surface and they were stored in $37^{\circ}C$ saline for 24 hours. An Instron universal testing machine was used to test the shear bond strength of ceramic brackets to porcelain. After debonding, bases of ceramic brackets and porcelain surfaces were examined under scanning electron microscope(SEM) to determine failure mode. Statistical analysis of the data was carried out with one-way ANOVA and Duncan's multiple range test. The results were as follows : 1. The shear bond strength of surface-treated groups 2 to 6 was higher than that of only silane-treated group 1, and there was statistical significance. (P<0.05) 2. There was no significant difference among the groups 3 to 6. (P>0.05) 3. The shear bond strength of etching-surface treated group 2 was significantly lower than those of sandblasting-surface treated group 4, complex surface treated group 5 and group 6. 4. According to the scanning electromicroscopic images, the surface roughness of sandblasting-surface treated group 4 was less than those of the group 5 and 6, but there was no significant difference in the shear bond strength. (P>0.05) As a conclusion we can have a clinically adequate bond strength when an application of silane is done after the treatment of porcelain surface with more than one way to bond ceramic bracket on the porcelain. Also, it is considered that the sandblasting and application of silane is effective for the simplication and convenience of the treatment.

• Korean Journal of Remote Sensing
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• v.29 no.1
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• pp.123-135
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• 2013

The reflectance observed in the visible channels of a geostationary meteorological satellite can be used to calculate the amount of cloud by comparing the reflectance with the observed solar radiation data at the ground. Using this, the solar radiation arriving at the surface can be estimated. This study used the Meteorological Imager (MI) reflectance observed at a wavelength of 675 nm and the Geostationary Ocean Color Imager (GOCI) reflectance observed at similar wavelengths of 660 and 680 nm. Cloudy days during a typhoon and sunny days with little cloud cover were compared using observation data from the geostationary satellite. Pixels that had more than 40% reflectance in the satellite images showed less than 0.3 of the cloud index and blocked more than 70% of the solar energy. Pixels that showed less than 15% reflectance showed more than 0.9 of the cloud index and let through more than 90% of the solar energy to the surface. The calculated daily accumulated solar radiation was compared with the observed daily accumulated solar radiation in 22 observatories of the Korean Meteorological Administration. The values calculated for the COMS and MTSAT MI sensors were smaller than the observation and showed low correlations of 0.94 and 0.93, respectively, which were smaller than the 0.96 correlation coefficient calculated for the GOCI sensor. The RMSEs of MTSAT, COMS MI and GOCI calculation results showed 2.21, 2.09, 2.02 MJ/$m^2$ in order. Comparison of the calculated daily accumulated results from the GOCI sensor with the observed data on the ground gave correlations and RMSEs for cloudy and sunny days of 0.96 and 0.86, and 1.82 MJ/$m^2$ and 2.27 MJ/$m^2$, respectively, indicating a slightly higher correlation for cloudy days. Compared to the meteorological imager, the geostationary ocean color imager in the COMS satellite has limited observation time and observation is not continuous. However, it has the advantage of providing high resolution so that it too can be useful for solar energy analysis.

• Radiation Oncology Journal
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• v.20 no.1
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• pp.24-33
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• 2002

Purpose : In order to improve dose homogeneity and to reduce acute toxicity in tangential whole breast radiotherapy, we evaluated two treatment techniques using multiple static fields or universal compensators. Materials and Methods : 1) Multistatic field technique : Using a three dimensional radiation treatment planning system, Adac Pinnacle 4.0, we accomplished a conventional wedged tangential plan. Examining the isodose distributions, a third field which blocked overdose regions was designed and an opposing field was created by using an automatic function of RTPS. Weighting of the beams was tuned until an ideal dose distribution was obtained. Another pair of beams were added when the dose homogeneity was not satisfactory. 2) Universal compensator technique : The breast shapes and sizes were obtained from the CT images of 20 patients who received whole breast radiation therapy at our institution. The data obtained were averaged and a pair of universal physical compensators were designed for the averaged data. DII (Dose Inhomogeneity Index : percentage volume of PTV outside $95\~105\%$ of the prescribed dose) $D_{max}$ (the maximum point dose in the PTV) and isodose distributions for each technique were compared. Results : The multistatic field technique was found to be superior to the conventional technique, reducing the mean value of DII by $14.6\%$ (p value<0.000) and the $D_{max}$ by $4.7\%$ (p value<0.000). The universal compensator was not significantly superior to the conventional technique since it decreased $D_{max}$ by $0.3\%$ (p value=0.867) and reduced DII by $3.7\%$ (p value=0.260). However, it decreased the value of DII by maximum $18\%$ when patients' breast shapes fitted in with the compensator geometry. Conclusion : The multistatic field technique is effective for improving dose homogeneity for whole breast radiation therapy and is applicable to all patients, whereas the use of universal compensators is effective only in patients whose breast shapes fit inwith the universal compensator geometry, and thus has limited applicability.

• The Korean Journal of Nuclear Medicine
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• v.32 no.6
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• pp.482-489
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• 1998

Purpose: Radionuclide cisternography may be helpful in understanding pathophysiology of postural head-ache and low CSF pressure in patients with spontaneous intracranial hypotension. The purpose of this study was to characterize radionuclide cisternographic findings of spontaneous intracranial hypotension. Materials and Methods: The study population consists of 15 patients with spontaneous intracranial hypotension. Diagnosis was based on their clinical symptoms and results of lumbar puncture. All patients underwent radionuclide cisternography following injection of 111 to 222 MBq of Tc-99m DTPA into the lumbar subarachnoid space. Sequential images were obtained between 112 hour and 24 hour after the injection of Tc-99m DTPA. Radioactivity of the bladder, soft tissue uptake, migration of radionuclide in the subarachnoid space, and extradural leakage of radionuclide were evaluated according to the scan time. Results: Radionuclide cisternogram showed delayed migration of radionuclide into the cerebral convexity (14/15), increased soft tissue uptake (11/15), and early visualization of bladder activity at 30min (6/10) and 2hr (13/13). Cisternography also demonstrated leakage site of CSF in 4 cases and 2 of these were depicted at 30min. Epidural blood patch was done in 11 patients and headache was improved in all cases. Conclusion: The characteristic findings of spontaneous intracranial hypotension were delayed migration of radionuclide and early visualization of the soft tissue and bladder activity. These scintigraphic findings suggest that CSF leakage rather than increased CSF absorption or decreased production may be the main pathophysiology of spontaneous intracranial hypotension. Early and multiple imaging including the bladder and soft tissue is required to observe the entire dynamics of radionuclide migration.

• Journal of the Korean earth science society
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• v.31 no.6
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• pp.600-607
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• 2010

In 2008, multiple episodes of large-scale transport of natural airborne particles and anthropogenically affected particles from different sources in the East Asian continent were identified in the National Oceanic and Atmospheric Administration (NOAA) satellite RGB-composite images and the mass concentrations of ground level particulate matters. To analyze the aerosol size distribution during the large-scale transport of atmospheric aerosols, both aerosol optical depth (AOD; proportional to the aerosol total loading in the vertical column) and fine aerosol weighting (FW; fractional contribution of fine aerosol to the total AOD) of Moderate resolution Imaging Spectroradiometer (MODIS) aerosol products were used over the East Asian region. The six episodes of massive natural airborne particles were observed at Cheongwon, originating from sandstorms in northern China, Mongolia and the loess plateau of China. The $PM_{10}$ and $PM_{2.5}$ stood at 70% and 16% of the total mass concentration of TSP, respectively. However, the mass concentration of $PM_{2.5}$ among TSP increased as high as 23% in the episode in which they were flowing in by way f the industrial area in east China. In the other five episodes of anthropogenically affected particles that flowed into the Korean Peninsula from east China, the mass concentrations of $PM_{10}$ and $PM_{2.5}$ among TSP reached 82% and 65%, respectively. The average AOD for the large-scale transport of anthropogenically affected particle episodes in the East Asian region was measured at $0.42{\pm}0.17$ compared with AOD ($0.36{\pm}0.13$) for the natural airborne particle episodes. Particularly, the regions covering east China, the Yellow Sea, the Korean Peninsula, and the east Korean sea were characterized by high levels of AOD. The average FW values observed during the event of anthropogenically affected aerosols ($0.63{\pm}0.16$) were moderately higher than those of natural airborne particles ($0.52{\pm}0.13$). This observation suggests that anthropogenically affected particles contribute greatly to the atmospheric aerosols in East Asia.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.4
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• pp.144-159
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• 2014

Techniques for making a single panoramic image using multiple pictures are widely studied in many areas such as computer vision, computer graphics, etc. The panorama image can be applied to various fields like virtual reality, robot vision areas which require wide-angled shots as an useful way to overcome the limitations such as picture-angle, resolutions, and internal informations of an image taken from a single camera. It is so much meaningful in a point that a panoramic image usually provides better immersion feeling than a plain image. Although there are many ways to build a panoramic image, most of them are using the way of extracting feature points and matching points of each images for making a single panoramic image. In addition, those methods use the RANSAC(RANdom SAmple Consensus) algorithm with matching points and the Homography matrix to transform the image. The SURF(Speeded Up Robust Features) algorithm which is used in this paper to extract featuring points uses an image's black and white informations and local spatial informations. The SURF is widely being used since it is very much robust at detecting image's size, view-point changes, and additionally, faster than the SIFT(Scale Invariant Features Transform) algorithm. The SURF has a shortcoming of making an error which results in decreasing the RANSAC algorithm's performance speed when extracting image's feature points. As a result, this may increase the CPU usage occupation rate. The error of detecting matching points may role as a critical reason for disqualifying panoramic image's accuracy and lucidity. In this paper, in order to minimize errors of extracting matching points, we used $3{\times}3$ region's RGB pixel values around the matching points' coordinates to perform intermediate filtering process for removing wrong matching points. We have also presented analysis and evaluation results relating to enhanced working speed for producing a panorama image, CPU usage rate, extracted matching points' decreasing rate and accuracy.

• The korean journal of orthodontics
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• v.39 no.5
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• pp.300-309
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• 2009

Objective: The purpose of this study was to evaluate the correlation between menton deviation and dental compensation in facial asymmetry. Methods: Tooth axis and distance of first molar and canine to the reference plane were investigated by cone-beam computerized tomography. The subjects consisted of 50 patients with asymmetric mandibles (male 21, female 29, mean age 24.3 years). Control groups were also assessed (male 11, female 9, mean age 25.6 years). Nine measurements (5 linear measurements and 4 angular measurements) were measured in order to evaluate the correlation between menton deviation and the linear and angular difference of first molar and canine in the deviated and none-deviated sides using the defined MPR images. The differences between deviated and non-deviated side, according to menton deviation, were statistically analyzed using stepwise multiple regression analysis. Results: From the result, Menton deviation was negatively correlated with mandibular first molar's angular measurement (${\Delta\angle}LM6$-Mn plane (dev.-ndev.)) and positively with maxillary fist molar's angular measurement (${\Delta\angle}UM6$-FH plane (dev.-ndev.)) (p < 0.01). Two angular measurements (${\Delta\angle}LM6$-Mn plane (dev.-ndev.), ${\Delta\angle}UM6$-FH plane (dev.-ndev.)) explained the variability in menton deviation with a significant $r^2$ value of 0.589. Conclusions: This study suggests that the tooth axis of upper and lower first molars leans towards the deviated side of Menton when there is mandibular asymmetry with Menton deviation.

• Nuclear Medicine and Molecular Imaging
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• v.40 no.3
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• pp.148-154
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• 2006

Purpose: Although radionuclide cisternography (RNC) is an useful study to detect cerebrospinal fluid (CSF) leakage in the patient with spontaneous intracranial hypotension (SIH), it sometimes fails to demonstrate the site of CSF leakage. The aim of the study is to improve the detection of leakage site of CSF and to reduce time for the study in RNC using modified protocol (m-RNC). Materials & methods : The study consists of 8 studies of 7 patients ($38{\pm}8$ years, M:F=2:5) with SIH, who underwent m-RNC following administration of 185-222 MBq of $^{99m}Tc$-DTPA into the lumbar subarachnoid space. Sequential images were obtained the whole spine with the head including urinary bladder at 10 minute, 30 minute, 1 hour, 2 hour, 4 hour and 6 hour. Radioactivity of extradural space and urinary bladder was evaluated. Results: Leakage site of CSF was identified in all 8 cases by m-RNC. Leakage site was cervicothoracic junction (CTJ, n=3), CTJ with C1-2 (n=2), CTJ with thoracic spine, thoracolumbar spine and lumbar spine (each n=1). All cases presented leakage sites within 1 hour and multiple sites, where CTJ was included in 6 cases. Only one case presented additional site in 6 hour image. Early radioactivity within the urinary bladder was noted in 6 cases, but that was fellowing after identification of the leakage site. Conclusion: Radionuclide cisternography is sensitive to detect the leakage site of CSF and is expected to improve the detection of CSF leakage site and reduce time for the study using modified protocol.

• Progress in Medical Physics
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• v.14 no.2
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• pp.108-123
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• 2003

The purpose of this study is to evaluate the contribution of $^{18}$ F-FDG brain PET in the differentiating Idiopathic parkinson's diesease (IPD), progressive supranuclear palsy (PSP), and multiple system atrophy (MSA). We studied 24 patients with parkinsonism : 8 patients (mean age 67.9$\pm$10.7 y: M/F : 3/5) with IPD, 9 patients (57.9$\pm$9.2 y : M/F : 4/5) with MSA and 7 patients (67.6$\pm$4.8 y : M/F 3/4) with PSP. All patients with parkinsonism and 22 age-matched normal controls underwent $^{18}$ F FDG PET in 3D mode after the injection of 370 MBq $^{118}$ F FDG. The patients with IPD, MSh and PSP were compared with a normal control group by a two-sided t-test of SPM99 (uncorrected P<0.001, extent threshold>100 voxel). All three parkinsonism groups, showed significant hypometabolism in the cerebral neocortex compared to the normal control group. However, the three groups displayed different metabolism in the subcortical structure, brain stem, and cerebellum. In IPD, there was no significant hypometabolism in the putamen, brain stem and cerebellum. However, MSA patients showed significant hypometabolism in the striatum, pons, and cerebellum compared to the normal controls and IPD patients. In addition, PSP showed significant hypometabolism in the caudate nuclei, the thalamus, midbrain, and the cingulate gyrus compared to the normal controls, the IPD, and MSA groups (IPD vs Normal sensitivity/specificity : 75%/l00%, MSA vs Normal sensitivity/specificity :100%/87%, PSP vs Normal sensitivity/specificity : 86%/94%). Our results show that the regional metabolism of IPD, MSA, and PSP is different mainly in the striatum, thalamus, brain stem and cerebellum. An assessment of the $^{18}$ F-FDG PET scan images using SPM may be a useful adjunct to a clinical examination in making a differential diagnosis of Parkinsonism.

• Journal of Intelligence and Information Systems
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• v.22 no.4
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• pp.45-67
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• 2016

Given the recent development of smart devices, users are producing, sharing, and acquiring a variety of information via the Internet and social network services (SNSs). Because users tend to use multiple media simultaneously according to their goals and preferences, domestic SNS users use around 2.09 media concurrently on average. Since the information provided by such media is usually textually represented, recent studies have been actively conducting textual analysis in order to understand users more deeply. Earlier studies using textual analysis focused on analyzing a document's contents without substantive consideration of the diverse characteristics of the source medium. However, current studies argue that analytical and interpretive approaches should be applied differently according to the characteristics of a document's source. Documents can be classified into the following types: informative documents for delivering information, expressive documents for expressing emotions and aesthetics, operational documents for inducing the recipient's behavior, and audiovisual media documents for supplementing the above three functions through images and music. Further, documents can be classified according to their contents, which comprise facts, concepts, procedures, principles, rules, stories, opinions, and descriptions. Documents have unique characteristics according to the source media by which they are distributed. In terms of newspapers, only highly trained people tend to write articles for public dissemination. In contrast, with SNSs, various types of users can freely write any message and such messages are distributed in an unpredictable way. Again, in the case of newspapers, each article exists independently and does not tend to have any relation to other articles. However, messages (original tweets) on Twitter, for example, are highly organized and regularly duplicated and repeated through replies and retweets. There have been many studies focusing on the different characteristics between newspapers and SNSs. However, it is difficult to find a study that focuses on the difference between the two media from the perspective of supply and demand. We can regard the articles of newspapers as a kind of information supply, whereas messages on various SNSs represent a demand for information. By investigating traditional newspapers and SNSs from the perspective of supply and demand of information, we can explore and explain the information dilemma more clearly. For example, there may be superfluous issues that are heavily reported in newspaper articles despite the fact that users seldom have much interest in these issues. Such overproduced information is not only a waste of media resources but also makes it difficult to find valuable, in-demand information. Further, some issues that are covered by only a few newspapers may be of high interest to SNS users. To alleviate the deleterious effects of information asymmetries, it is necessary to analyze the supply and demand of each information source and, accordingly, provide information flexibly. Such an approach would allow the value of information to be explored and approximated on the basis of the supply-demand balance. Conceptually, this is very similar to the price of goods or services being determined by the supply-demand relationship. Adopting this concept, media companies could focus on the production of highly in-demand issues that are in short supply. In this study, we selected Internet news sites and Twitter as representative media for investigating information supply and demand, respectively. We present the notion of News Value Index (NVI), which evaluates the value of news information in terms of the magnitude of Twitter messages associated with it. In addition, we visualize the change of information value over time using the NVI. We conducted an analysis using 387,014 news articles and 31,674,795 Twitter messages. The analysis results revealed interesting patterns: most issues show lower NVI than average of the whole issue, whereas a few issues show steadily higher NVI than the average.