• Journal of Magnetics
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• v.19 no.2
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• pp.185-191
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• 2014

In this study we evaluated that flow rate changes affect the (time of flight) TOF image and contrast-enhanced (CE) in a three-dimensional TOF angiography. We used a 3.0T MR System, a nonpulsatile flow rate model. Saline was used as a fluid injected at a flow rate of 11.4 cm/sec by auto injector. The fluid signal strength, phantom body signal strength and background signal strength were measured at 1, 5, 10, 15, 20 and 25-th cross-section in the experienced images and then they were used to determine signal-to-noise ratio and contrast-to-noise ratio. The inlet, middle and outlet length were measured using coronal images obtained through the maximum intensity projection method. As a result, the length of inner cavity was 2.66 mm with no difference among the inlet, middle and outlet length. We also could know that the magnification rate is 49-55.6% in inlet part, 49-59% in middle part and 49-59% in outlet part, and so the image is generally larger than in the actual measurement. Signal-to-noise ratio and contrast-to-noise ratio were negatively correlated with the fluid velocity and so we could see that signal-to-noise ratio and contrast-to-noise ratio are reduced by faster fluid velocity. Signal-to-noise ratio was 42.2-52.5 in 5-25th section and contrast-to-noise ratio was from 34.0-46.1 also not different, but there was a difference in the 1st section. The smallest 3D TOF MRA measure was $2.51{\pm}0.12mm$ with a flow velocity of 40 cm/s. Consequently, 3D TOF MRA tests show that the faster fluid velocity decreases the signal-to-noise ratio and contrast-to-noise ratio, and basically it can be determined that 3D TOF MRA and 3D CE MRA are displayed larger than in the actual measurement.

• The Korean Journal of Pesticide Science
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• v.11 no.2
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• pp.59-66
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• 2007

Three dimensional quantitative structure-activity relationships (3D-QSARs) on the fungicidal activity of N-phenyl-O-phenylthionocarbamate analogues against resistant and sensitive gray mold (Botrytis cinerea) (RBC & SBC) were studied quantitatively using CoMFA and CoMSIA methods. The correlation coefficient and predict- ability of optimized CoMFA model with the atom based fit alignment were better ($r^2$ & $q^2=CoMFA{\gg}CoMSIA$) than that of CoMSIA model. And statistical values of the models on the fungicidal activity against SBC were showed higher ($r^2=SBC{\gg}RBC$) than that of RBC. In CoMFA models, steric field on the activity was more influenced than electrostatic field. And in case of CoMSIA models, the influence of CoMSIA field on the activity against RBC and SBC was differ from each other but the influence of H-bond donor field was same to the two fungi. It is revealed that the selectivity factor with CoMFA model on the fungicidal activity between the two fungi was caused on the difference of steric field. Therefore, it is predicted that the large steric field with meta- and para-substituents on the N-phenyl ring will be improved to the fungicidal activity with SBC.

• Journal of Korean Foot and Ankle Society
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• v.7 no.2
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• pp.208-217
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• 2003

Introduction: Soft-tissue impingement syndrome is now increasingly recognized as a significant cause of the chronic ankle pain. As a method to detect soft-tissue ankle impingement, a characteristic history and physical examination, routine MR imaging, and direct MR arthrography were used. The efficacy of routine MR imaging has been controversial for usefulness because of low sensitivity and specificity. Direct MR artrhography was recommaned for diagnosis because of the highest sensitivity, specificity and accuracy, but it requires an invasive procedure. The purpose of this study is to investigate the diagnostic accuracy of Fat suppressed, contrast enhanced, three-dimensional fast gradient recalled acquisition in the steady state with rediofrequency spoiling magnetic resonance imaging(CE 3D-FSPGR MRI) and to evaluate the clinical outcome of the arthroscopic treatment in assessing soft-tissue impingement associated with trauma of the ankle. Materials and Methods: We reviewed 38 patients who had arthroscopic evaluations and preoperative magnetic resonance imaging studies(3D-FSPGR MRI) for post-traumatic chronic ankle pain between January 2000 and August 2002. Among them, 24 patients had osteochondral lesion, lateral instability, loose body, malunion of lateral malleoli, and peroneal tendon dislocation. The patient group consisted of 23 men and 15 women with the average age of 34 years(16-81 years). The mean time interval from the initial trauma to the operation was 15.5 months(3 to 40 months), The mean follow-up duration of the assessment was 15.6months(12-48 months). MRI was simultaneously reviewed by two radiologists blinded to the clinical diagnosis. The sensitivity, specificity and accuracy of MRI was obtained from radiologic and arthroscopic finding. Arthroscopic debridement and additional operation for associated disease were performed. We used a standard protocol to evaluate patients before the operation and at follow-up which includes American Orthopedic Foot and Ankle Society Ankle-Hindfoot Score. Results: For the assessment of the synovitis and soft tissue impingement, fat suppressed CE 3D-FSPGR MR imaging had the sensitivity of 91.9%, the specificity of 84.4 and the accuracy of 87.5%. AOFAS Ankle-Hindfoot Score of preoperative state was 69.2, and the mean score of the last follow-up was 89.1. These were assessed as having 50% excellent(90-100) and 50% good(75-89). The presence of other associated disease didn't show the statistically significant difference(>0.05). Conclusion: Fat suppressed CE 3D-FSPGR MR imaging is useful method comparable to MR arthrography for diagnosis of synovitis or soft-tissue impingement, and arthroscopic debridement results in good clinical outcome.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.220-220
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• 2013

Surface-normal transmission electro-absorption modulator (EAM) are attractive for high-definition (HD) three-dimensional (3D) imaging application due to its features such as small system volume and simple epitaxial structure [1,2]. However, EAM in order to be used for HD 3D imaging system requires uniform modulation performance over large area. To achieve highly uniform modulation performance of EAM at the operating wavelength of 850 nm, it is extremely important to remove the GaAs substrate over large area since GaAs material has high absorption coefficient below 870 nm which corresponds to band-edge energy of GaAs (1.424 eV). In this study, we propose and experimentally demonstrate a transmission EAM in which highly selective backside etching methods which include lapping, dry etching and wet etching is carried out to remove the GaAs substrate for achieving highly uniform modulation performance. First, lapping process on GaAs substrate was carried out for different lapping speeds (5 rpm, 7 rpm, 10 rpm) and the thickness was measured over different areas of surface. For a lapping speed of 5 rpm, a highly uniform surface over a large area ($2{\times}1\;mm^2$) was obtained. Second, optimization of inductive coupled plasma-reactive ion etching (ICP-RIE) was carried out to achieve anisotropy and high etch rate. The dry etching carried out using a gas mixture of SiCl4 and Ar, each having a flow rate of 10 sccm and 40 sccm, respectively with an RF power of 50 W, ICP power of 400 W and chamber pressure of 2 mTorr was the optimum etching condition. Last, the rest of GaAs substrate was successfully removed by highly selective backside wet etching with pH adjusted solution of citric acid and hydrogen peroxide. Citric acid/hydrogen peroxide etching solution having a volume ratio of 5:1 was the best etching condition which provides not only high selectivity of 235:1 between GaAs and AlAs but also good etching profile [3]. The fabricated transmission EAM array have an amplitude modulation of more than 50% at the bias voltage of -9 V and maintains high uniformity of >90% over large area ($2{\times}1\;mm^2$). These results show that the fabricated transmission EAM with substrate removed is an excellent candidate to be used as an optical shutter for HD 3D imaging application.

• Journal of the Korea Society of Computer and Information
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• v.25 no.6
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• pp.109-117
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• 2020

An edutainment system aims to help learners to recognize problems effectively, grasp and classify important information needed to solve the problems and convey the contents of what they have learned. Edutainment contents can be usefully applied to education and training in the both scientific and industrial areas. Our present work proposes an edutainment system that can be applied to a drug discovery process including virtual screening by using intuitive multi-modal interfaces. In this system, a stereoscopic monitor is used to make three-dimensional (3D) macro-molecular images, with supporting multi-modal interfaces to manipulate 3D models of molecular structures effectively. In this paper, our system can easily solve a docking simulation function, which is one of important virtual drug screening methods, by applying gaming factors. The level-up concept is implemented to realize a bio-game approach, in which the gaming factor depends on number of objects and users. The quality of the proposed system is evaluated with performance comparison in terms of a finishing time of a drug docking process to screen new inhibitors against target proteins of human immunodeficiency virus (HIV) in an e-drug discovery process.

• Korean Journal of Heritage: History & Science
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• v.46 no.2
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• pp.26-45
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• 2013

Sudden increase exceeding 30million in the number of smart phone users, and rising interest in the technology of augmented reality, is now trying to combine it with AR technology in other areas very much. The field of cultural heritage, which has been constructed by the Internet and 3D technology, is not unusual and this field is now rapidly changing thanks to the AR technology which can make users experience cultural heritage with high reality. The Palaces in Seoul, however, use fragmentary tools of information - lack of heritage commentators, leaflet, etc, even though the number of visitors is gradually increasing. Therefore, three-dimensional and comprehensive cultural heritage information service is needed with the guidance in the mobile era. This study utilizes the AR technology for building the Deoksugung Tourist Information Service Application(App.) applying the markerless-based recognition technology which is a more advanced tool than the location-based AR technology. This new AR technology can switch perceived real images such as the tablet of the King in the Palace of in the real world, patterns and pedestals into virtual world, which can reproduce the damaged cultural assets as 3D. This also composes photos of the past with the current buildings, which can increase people's interest and absorption of the contents, and helps them understand and be aware of Korean traditional culture and cultural heritage effectively. In addition, convergence between IT new technology, Augmented Reality(AR) and humanities through storytelling based implementation of cultural heritage in smart phone is attempted to demonstrate that there is strength in which augmented reality technique exerts infinite creativity based on actual reality world.

• Journal of radiological science and technology
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• v.34 no.4
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• pp.341-349
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• 2011

This study was to measure the patient dose difference between 3D treatment planning CT and 4D respiratory gating CT. Study was performed with each 10 patients who have lung and liver cancer for measured patient exposure dose by using SOMATON SENSATION OPEN(SIMENS, GERMANY). CTDIvol and DLP value was used to analyze patient dose, and actual dose was measured in the location of liver and kidney for abdominal examination and lung, heart and spinal cord for chest examination. Rando phantom were used for the experiment. OSLD was used for in-vitro and in-vivo dosimetry. Increasing overall actual dose in 4D respiratory gated CT-simulation using OSLD increase the dose by 5.5 times for liver cancer patients and 6 times for lung cancer patients. In CT simulation of 10 lung cancer patients, CTDIvol value was increased by 5.7 times and DLP 2.4 times. For liver cancer patients, CTDIvol was risen by 3.8 times and DLP 1.6 times. The accuracy of treatment volume could be increased in 4D CT planning for position change due to the breaths of patient in the radiation therapy. However, patients dose was increased in 4D CT than 3D CT. In conclusion, constant efforts is required to reduce patients dose by reducing scan time and scan range.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.33 no.1
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• pp.31-43
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• 2015

This study had been aimed to conduct the camera calibration on VLBI antenna in the Space Geodetic Observation Center of Sejong City with a low-cost digital camera, which embedded in a mobile phone to determine the three-dimension position coordinates of the VLBI antenna, based on stereo images. The initial values for the camera calibration have been obtained by utilizing the Direct Linear Transformation algorithm and the commercial digital photogrammetry system, PhotoModeler $Scanner^{(R)}$ ver. 6.0, respectively. The accuracy of camera calibration results was compared with that the camera calibration results, acquired by a bundle adjustment with nonlinear collinearity condition equation. Although two methods showed significant differences in the initial value, the final calibration demonstrated the consistent results whichever methods had been performed for obtaining the initial value. Furthermore, those three-dimensional coordinates of feature points of the VLBI antenna were respectively calculated using the camera calibration by the two methods to be compared with the reference coordinates obtained from a total station. In fact, both methods have resulted out a same standard deviation of $X=0.004{\pm}0.010m$, $Y=0.001{\pm}0.015m$, $Z=0.009{\pm}0.017m$, that of showing a high degree of accuracy in centimeters. From the result, we can conclude that a mobile phone camera opens up the way for a variety of image processing studies, such as 3D reconstruction from images captured.

• Restorative Dentistry and Endodontics
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• v.34 no.1
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• pp.69-79
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• 2009

The purpose of this study was to evaluate the influence of elastic modulus of restorative materials and the number of interfaces of post and core systems on the stress distribution of three differently restored endodontically treated maxillary second premolars using 3D FE analysis. Model 1, 2 was restored with a stainless steel or glass fiber post and direct composite resin. A PFG or a sintered alumina crown was considered. Model 3 was restored by EndoCrown. An oblique 500 N was applied on the buccal (Load A) and palatal (Load B) cusp. The von Mises stresses in the coronal and root structure of each model were analyzed using ANSYS. The elastic modulus of the definitive restorations rather than the type of post and core system was the primary factor that influenced the stress distribution of endodontically treated maxillary premolars. The stress concentration at the coronal structure could be lowered through the use of definitive restoration of high elastic modulus. The stress concentration at the root structure could be lowered through the use of definitive restoration of low elastic modulus.

• Geophysics and Geophysical Exploration
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• v.8 no.4
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• pp.262-269
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• 2005

Since the buried cultural relics are three-dimensional (3-D) objects in nature, 3-D survey is more preferable in archeological exploration. 3-D Ground Penetrating Radar (GPR) survey based on very dense data in principle, however, might need much higher cost and longer time of exploration than other geophysical methods commonly used for the archeological exploration, such as magnetic and electromagnetic methods. We developed a small-scale continuous data acquisition system which consists of two sets of GPR antennas and the precise positioning device tracking the moving-path of GPR antenna automatically and continuously. Since the high cost of field work may be partly attributed to establishing many profile lines, we adopted a concept of data acquisition at arbitrary locations not along the pre-established profile lines. Besides this hardware system, we also developed several software packages in order to effectively process and visualize the 3-D data obtained by the developed system and the data acquisition concept. Using the developed system, we performed 3-D GPR survey to investigate the possible historical remains of Baekje Kingdom at Buyeo city, South Korea, prior to the excavation. Owing to the newly devised system, we could obtain 3-D GPR data of this survey area having areal extent over about $17,000m^2$ within only six-hours field work. Although the GPR data were obtained at random locations not along the pre-established profile lines, we could obtain high-resolution 3-D images showing many distinctive anomalies, which could be interpreted as old agricultural lands, waterways, and artificial structures or remains. This cast: history led us to the conclusion that 3-D GPR method is very useful not only to examine a small anomalous area but also to investigate the wider region of the archeological interests.