• 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.

• Journal of Digital Contents Society
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• v.13 no.2
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• pp.225-233
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• 2012

The 3D stereoscopic image contents have been emerging as the blue chip of the contents market of the next generation since the . However, all the 3D contents created commercially in the country have failed to enter box office. It is because the quality of Korean 3D contents is much lower than that of overseas contents and also current 3D post production process is based on 2D. Considering all these facts, the 3D editing process has connection with the quality of contents. The current 3D editing processes of the production case of are using the way that edits with the system on basis of 2D, followed by checking with 3D display system and modifying, if there are any problems. In order to improve those conditions, I suggest that the 3D editing process contain more objectivity by visualizing the depth data applied in some composition work such as Disparity map, Depth map, and the current 3D editing process. The proposed process has been used in the music drama , comparing with those of the film . The 3D values could be checked among cuts which have been changed a lot since those of , while the 3D value of drew an equal result in general. Since the current process is based on an artist's subjective sense of 3D, it could be changed according to the condition and state of the artist. Furthermore, it is impossible for us to predict the positive range, so it is apprehended that the cubic effect of space might be perverted by showing each different 3D value according to cuts in the same space or a limited space. On the other hand, the objective 3D editing by applying the visualization of depth data can adjust itself to the cubic effect of the same space and the whole content equally, which will enrich the 3D contents. It will even be able to solve some problems such as distortion of cubic effect and visual fatigue, etc.

• Investigative Magnetic Resonance Imaging
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• v.7 no.2
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• pp.124-131
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• 2003

Purpose : To reveal clinical usefulness of functional MRI (fMRI) using sensorymotor and language stimuli for demonstrating anatomic relationship between sensorimotor or language cortices and lesions in the planning of brain tumor surgery. Materials and Methods : This study included 12 right-handed patients with brain tumors in or around sensorimotor or language cortices. Eleven patients were evaluated with primary motor and sensory stimuli. Of these patients, six patients were also evaluated with language stimuli. One patient was evaluated with language stimuli only. For fMR imaging, a 1.5T scanner was used and the EPI BOLD technique was employed. For postprocessing image, the SPM99 program and a program made by our department was utilized. We evaluated whether sensorimotor and language stimuli activate sensorimotor and language cortices. And also, clinical efficacy of revealing anatomic relationship between cerebral cortices and lesions for planning neurosurgical operation were evaluated. Finally, we compared post-operative neurologic function with pre-operative neurologic function in same patients. Results : The fMRI examination was successful in identifying the functional cortices and depicting anatomic relationship between functional cortices and lesions in all patients. In nine patients of 11 patients with identified sensorimotor cortices, postoperative grade of manual motor test was not changed, compared with preoperative grade. Whereas postoperative improved than preoperative grade in one patient of remaining two patients, postoperative aggravated than preoperative grade in the other. This result was due to atherosclerotic lacunar infarction, regardless of tumor resection. Postoperative deficit of language function was not found in seven patients with identified language cortices. Conclusion : fMRI could be a helpful method for determining the best approach to neurosurgical treatment in patients with brain tumors in or around sensorimotor or language cortices.

• The Journal of Korean Academy of Prosthodontics
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• v.46 no.2
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• pp.201-208
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• 2008

Statement of problem: A new implant impression technique which use abutments as impression coping, and use resin cement as a splinting material was described. Accuracy of this technique was compared with conventional closed tray and resin splinted open tray technique for a $15^{\circ}$ angled 3-implant model Material and methods: A dental stone master model with 3 linearly positioned implant analogue and a reference framework which was passively fitted to it were fabricated. The center analogue was perpendicular to the plane of model and the outer analogues had a $15^{\circ}$angulation forward or backward. 10 closed tray impressions, 10 resin splinted open tray impressions, 10 abutment-resin framework cementation impressions and 10 abutment-metal framework cementation impressions were made with additional silicone material and poured with dental stone. A light microscope with image processing was used to record the vertical gap dimension between reference framework and analogue of duplicated cast made with each 4 impression techniques. Statistical analysis used one-way ANOVA with post-hoc tests Tukey test of .05 level of significance Results: Significant difference in the vertical gap dimension was found between closed tray technique; 74.3 (${\pm}33.4$)${\mu}m$ and resin splinted open tray technique, and two other new technique. (P<.05) Abutment-metal framework cementation technique;42.5 (${\pm}11.9$)${\mu}m$ was significantly different from resin splinted open tray technique. (P<.05) Abutmentresin framework cementation technique;51.0 (${\pm}14.1$)${\mu}m$ did not differ significantly from resin splinted open tray technique;50.3 (${\pm}16.9$)${\mu}m$. (P>.05) Conclusion: Within limitations of this study, the accuracy of implant level impressions of resin splinted open tray technique was superior to that of closed tray technique. A new technique using abutment and metal framework cementation was more accurate than resin splinted open tray technique.

• Restorative Dentistry and Endodontics
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• v.30 no.4
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• pp.303-311
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• 2005

The purpose of this study was to evaluate which type of Ni-Ti files are able to maintain canal configuration better in the simulated canal with abrupt curvature near it's apex. Ninety six simulated root canals were made in epoxy resin and $\sharp$15 finger spreader was used as root canal templates. The simulated root canals were made with radius of curvature of 1.5mm, 3.0mm, 4.0mm, 6.0mm respectively and the angle of curvature of all simulated canals were adjusted to 90 degree. The simulated canals were instrumented by ProFile, ProTaper, Hero 642, and $K^3$ at a 300 rpm using crown-down pressureless technique. Pre-instrumented and post-instrumented images were taken by digital camera and were superimposed with Adobe Photos hop 6.0 program. Images were compared by image analysis program. The changes of canal width at the inner and outer side of the canal curvature. canal transportation were measured at 9 measuring point with 1 mm interval. Statistical analysis among the types of Ni-Ti files was performed using Kruskal-Wallis test and Mann-Whitney U-test. The result was that ProFile maintain original canal configuration better than other engine driven Ni-Ti files in the canals above 3.0mm radius of curvature, and in the 1.5mm radius of curvature, most of Ni-Ti flies were deformed or separated during instrumentation.

• Archives of design research
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• v.17 no.1
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• pp.339-346
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• 2004

Matrix, produced by Larry & Andy Wachowski, was relatively precisely dealt with the cyber world. After the movie was released, it had a mania for the movie and was adopted into a various forms of cultural products. It was remade not only into the parodies of the other movies and TV programs, but also the clothes and miscellaneous items of the movie were reincarnated as an unique cultural trend. The cause of the popularity is the fresh storyline as well as the sophisticated visual effects and good-looking actors. The agony of the protagonist was connected with the people outside the movie who are yearning for the ideal world. He was confused at the fact that his circumstances which were believed as the real world were not tortally true, complicated between the sensually phisical truth and the spiritual truth and had an will for the freedom that would ransack the truth and save the other people from the fictitious world. Consequently, the movie has got sympathies with many audiences suggesting the situation that has no a firm belief of the reality, the difference between the real and the cyber world is meaningless and the faked images of the high-technology are overturned This thesis tries to study the present that the real images are excessly duplicated and consumed, related to the Jean Baudrillard's theory, 'Hyperreel'. Replaced the real objects by a technical programming in the Matrix world, there happens the image-violence that the true nature is slaughterred by images. In the world where the reproducts are more actual than the reality and pretends to be real, only semiotics are consumed and produced. That is to say, the tortally programmed images has no references and aims, therefore should be produced in an 'impediment-strategy' like a faked crisis. That is the step of 'Simulation' that artificially reincarnates the real. Based upon the Baudrillard's theory, 'Simulacre', this study tries to research today's post-modern situation that the boundary of the real world and the faked copy is vague and vanishing, through the analysis of the cyber world of the movie 'Matrix'.

• Restorative Dentistry and Endodontics
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• v.35 no.2
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• pp.88-95
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• 2010

The purpose of this study was to compare the root canal shaping ability of 4 rotary NiTi instruments in simulated root canals. For the preparation of thirty two curved root canals, Mtwo instruments using "single length"technique, and Profile, ProTaper Universal, and K3 using crown-down technique (N = 8) were used. All canal samples were prepared by reaching an apical canal size of #30. Pre- and post-instrumentation digital images were recorded and an assessment of canal shape was determined using a computer image analysis program SigmaScan Pro (Systat Software Inc., San Jose, CA, USA). The changes of the dimension of inner walls of canals, (2) the changes of the dimension of outer walls of canals, and (3) the centering ratio were measured at 7 measuring points, and then data were statistically analyzed using one-way ANOVA and Duncan's test. The results were as below; 1. The root canal shaping ability of Profile was significantly faster than that of other rotary NiTi instruments (p < 0.05). 2. The deformation and fracture of all instruments used for this study were not experienced. 3. In the degree of changes of the dimension of inner walls of canals, Profile demonstrated the lowest changes of the dimension of inner walls of canals except at the measuring points of the 1 and 2 mm (p < 0.05). However, the ProTaper Universal showed the highest changes of the dimension of inner walls of canals at all measuring points (p < 0.05). 4. In the degree of changes of the dimension of outer walls of canals, Mtwo demonstrated the lowest changse of the dimension of outer walls of canals except at the measuring point of the 1 mm (p < 0.05). However, Profile exhibited the highest changes of the dimension of outer walls of canals at the measuring points of 3 and 4 mm and ProTaper Universal and K3 showed the largest changes of the dimension of outer walls of canals at the measuring points of 1, 2, 6, and 7 mm (p < 0.05). 5. In degree of centering ratio, Profile demonstrated the least centering ratio comparing with the centering ratio shown by other NiTi instruments at the measuring points of 1, 4, 5, and 6 mm. Results suggest that in the coronal part of canal preparation, active cutting files such as ProTaper Universal may efficiently flare the canal orifice and form a better taper, and in the apical part of the canal, files which have a better centering ability such as Profile may maintain the original canal curvature and reduce the shaping time.

• Restorative Dentistry and Endodontics
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• v.31 no.3
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• pp.179-185
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• 2006

This study was conducted to evaluate canal configuration after shaping by $ProTaper^{TM}$ with various rotational speed in J-shaped simulated resin canals. Forty simulated root canals were divided into 4 groups, and instrumented using by $ProTaper^{TM}$ at the rotational speed of 250, 300, 350 and 400 rpm. Pre-instrumented and post-instrumented images were taken by a scanner and those were superimposed. Outer canal width, inner canal width, total canal width, and amount of transportation from original axis were measured at 1, 2, 3, 4, 5, 6, 7 and 8 mm from apex. Instrumentation time, instrument deformation and fracture were recorded. Data were analyzed by means of one-way ANOVA followed by Scheffe's test. The results were as follows 1. Regardless of rotational speed, at the $1{\sim}2mm$ from the apex, axis of canal was transported to outer side of a curvature, and at 3~6 mm from the apex, to inner side of a curvature. Amounts of transportation from original axis were not sienifcantly different among experimental groups except at 5 and 6 mm from the apex. 2. Instrumentation time of 350 and 400 rpm was significantly less than that of 250 and 300 rpm (p<0.01). In conclusion the rotational speed of $ProTaper^{TM}$ files in the range of $250{\sim}400rpm$ does not affect the change of canal configuration, and high rotational speed reduces the instrumentation time. However appearance of separation and distortion of Ni-Ti rotary files can occur in high rotational speed.

• Korean Journal of Heritage: History & Science
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• v.57 no.1
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• pp.82-108
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• 2024

With the transition of archaeological recording method's transition from analog to digital, the 3D scanning technology has been actively adopted within the field. Research on the digital archaeological digital data gathered from 3D scanning and photogrammetry is continuously being conducted. However, due to cost and manpower issues, most buried cultural heritage organizations are hesitating to adopt such digital technology. This paper aims to present a digital recording method of relics utilizing open-source software and photogrammetry technology, which is believed to be the most efficient method among 3D scanning methods. The digital recording process of relics consists of three stages: acquiring a 3D model, creating a joining map with the edited 3D model, and creating an digital drawing. In order to enhance the accessibility, this method only utilizes open-source software throughout the entire process. The results of this study confirms that in terms of quantitative evaluation, the deviation of numerical measurement between the actual artifact and the 3D model was minimal. In addition, the results of quantitative quality analysis from the open-source software and the commercial software showed high similarity. However, the data processing time was overwhelmingly fast for commercial software, which is believed to be a result of high computational speed from the improved algorithm. In qualitative evaluation, some differences in mesh and texture quality occurred. In the 3D model generated by opensource software, following problems occurred: noise on the mesh surface, harsh surface of the mesh, and difficulty in confirming the production marks of relics and the expression of patterns. However, some of the open source software did generate the quality comparable to that of commercial software in quantitative and qualitative evaluations. Open-source software for editing 3D models was able to not only post-process, match, and merge the 3D model, but also scale adjustment, join surface production, and render image necessary for the actual measurement of relics. The final completed drawing was tracked by the CAD program, which is also an open-source software. In archaeological research, photogrammetry is very applicable to various processes, including excavation, writing reports, and research on numerical data from 3D models. With the breakthrough development of computer vision, the types of open-source software have been diversified and the performance has significantly improved. With the high accessibility to such digital technology, the acquisition of 3D model data in archaeology will be used as basic data for preservation and active research of cultural heritage.

• The Korean Journal of Nuclear Medicine
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• v.37 no.2
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• pp.83-93
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• 2003

Background: Lung-to-heart uptake ratio (LHR) in $^{201}Tl-chloride$ myocardial perfusion scan is believed to be a reliable marker for left ventricular (LV) dysfunction, but the clinical value of LHR is controversial for $^{99m}Tc-MIBI$ imaging. Furthermore, most of results suggesting lung uptake of $^{99m}Tc-MIBI$ as a potential marker for LV dysfunction used immediate post-stress images, instead of routine images acquired 1 hour after tracer injection. The goal of our study was to investigate whether LHR evaluated with routine gated $^{99m}Tc-MIBI$ imaging can reflect the degree of perfusion defect or left ventricular performance. Subjects and Methods: 241 patients underwent exercise $^{99m}Tc-MIBI$ myocardial SPECT were classified into normal myocardial perfusion (NP, n=135) and abnormal myocardial perfusion (AP, n=106) group according to the presence of perfusion defect. LHR was calculated from anterior projection image taken at 1-hour after injection. Two legions of interest (ROIs) were placed on left lung above LV and on myocardium showing the highest radioactivity. Subjects were classified by left ventricular ejection fraction (LVEF), as Gr-I: >50%, Gr-II: 36-50%, Gr-III: <36% and by summed stress score (SSS), as Gr-A: <4, Gr-B: 4-8, Gr-C: 9-13, Gr-D: >13, LHR was compared among these groups. Results: In NP group(n=135), LHR, were higher in men than women ($men:\;0.311{\pm}0.03,\;women:\;0.296{\pm}0.03,\;p<0.05$). Significant difference, in LHR were found between NP and AP groups both for men and women ($men:\;0.311{\pm}0.03\;vs\;.\;0.331{\pm}0.06,\;women:\;0.296{\pm}0.03\;vs.\;0.321{\pm}0.07.\;p<0.05$). There were weak negative correlation between LHR and LVEF (r=-0.342, p<0.05) and weak positive correlation between LHR and SSS (r=0.478, p<0.05) in men, but not in women (LVEF: r=-0.279, p=0.100, SSS: r=0.276, p=0.103). Increased LHR was defined when for more than mean + 2SD value ($men{\geq}0.38,\;women{\geq}0.37$) of the LHR of the subject with normal perfusion. Increased LHR were observed more frequently in subjects with lower LVEF (Gr-I: 11.1%, Gr-II: 27.0%, Gr-III: 35.4%, p<0.05) and higher SSS(Gr-A: 14.0%, Gr-B: 5.7%, Gr-C: 18.2%, Gr-D: 40.7%, p<0.05). Conclusions: LHRs obtained from routine $^{99m}Tc-MIBI$ gated SPECT images were weakly correlated with LVEF and perfusion defect. Although significant overlaps were observed between normal and abnormal perfusion group, LHRs could be used as an indirect marker of severe perfusion defect or reduced left ventricular function.