• Journal of the Korea Institute of Information Security & Cryptology
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• v.12 no.5
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• pp.87-93
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• 2002

SHACAL is based on the hash standard SHA-1 used in encryption mode, as a submission to NESSIE. SHACAL uses the XOR, modular addition operation and the functions of bit-by-bit manner. These operations and functions make the differential cryptanalysis difficult, i.e, we hardly find a long differential with high probability. But, we can find short differentials with high probability. Using this fact, we discuss the security of SHACAL against the amplified boomerang attack. We find a 36-step boomerang-distinguisher and present attacks on reduced-round SHACAL with various key sizes. We can attack 39-step with 256-bit key, and 47-step with 512-bit key.

• Tuberculosis and Respiratory Diseases
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• v.45 no.5
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• pp.1031-1038
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• 1998

Background: Most of malignant pleural effusions are serous but 8-33% of them are bloody. We wanted to evaluate the relationships between gross appearance and pleural CEA level or results of histocytology in malignancy associated pleural effusions. We also tried to reevaluate the meaning of CEA measurement in histocytologically proved or unproved malignancy associated pleural effusions. Methods: We studied 98 cases of malignancy associated pleural effusions, 50 cases of histocytologically proven malignant effusions and 48 cases of histocytologically unproven paramalignant effusions. We had observed gross appearance and conventional laboratory values and CEA levels for pleural effusions. Results: 44.9% of malignancy associated effusions were bloody(63.6% of bloody effusions were histocytologically proven malignant effusion). 65.0% of malignancy associated pleural effusions which have RBCs numbers over $100,000/mm^3$ were cytologically proven malignant effusions. 72.7% of cytologically proven malignant effusions had increased pleural fluid CEA level over 10 ng/ml. 58.2% of cases with pleural CEA over 10 ng/ml had positive results in pleural bistocytology. There was no definable relationships between pleural fluid CEA elevation and RBCs numbers and results of pleural fluid cytology. Conclusion: About half of the cases with malignancy associated pleural effusions were bloody. Histocytologically proven malignant effusions were more common in bloody effusion than non-bloody effusion(63.6% Vs 38.9%). But increased red blood cell numbers was not associated with positivity of pleural histocytology. Pleural fluid CEA elevation(over 10 ng/ml) was not correlated with positive pleural histocytology. But pleural fluid CEA elevation was rare in nonmalignant pleural effusions, and than pleural CEA measurement in uncertain pleural effusions maybe helpful to distinguishes its origin.

• Journal of Dental Rehabilitation and Applied Science
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• v.32 no.3
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• pp.194-201
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• 2016

Purpose: The purpose of this study was to evaluate of Zirconium Nitride (ZrN) coating on shear bond strength with denture base resin in Co-Cr and Ti-6Al-4V alloy. Materials and Methods: Co-Cr and Ti-6Al-4V alloy disks (10 mm in diameter, 2.5 mm in thickness; each other: n = 14) were prepared and divided with 2 groups each other by ZrN coating. After primer was applied to disks surface, denture base resin with diameter 6 mm, height 5 mm was bonded on metal disk surface. After surface roughness was measured by Profiler, shear bond strength was determined with Universal testing machine and analyzed with two-way ANOVA. The specimen surfaces and failure mode were examined using a scanning electron microscope. Results: ZrN coated groups showed significantly higher rough surface than non-coated groups (P < 0.05). Irrespective of alloy materials, shear bond strength of ZrN coated groups were lower than non-coated groups (P < 0.001). The scanning electron microscope (SEM) of ZrN coated groups showed mixed and adhesive fractures. Conclusion: ZrN coating weakened bonding strength between denture base resin and Co-Cr, Ti-6Al-4V alloy.

• Imaging Science in Dentistry
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• v.34 no.1
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• pp.25-30
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• 2004

Purpose: Several panoramic indices have been suggested to assess bone quality from the morphology and width of mandibular cortex on panoramic radiography. The purpose of this study was to compare dental implant failure group with control group in panoramic mandibular index (PMI), mandibular cortical index (MCI), and gonion index (GI) and to determine the effect of these panoramic indices on dental implant failure. Materials and Methods: A case-control study was designed. Test group (n=42) consisted of the patients who had their implants extracted because of peri-implantitis. Control group (n=139) consisted of the patients who retained their implants over one year without any pathologic changes and had been followed up periodically. They had dental implants installed in their mandibles without bone augmentation surgery from 1991 to 2001. The following measures were collected for each patients: 1) PMI, MCI, and GI were measured twice at one-week interval on preoperative panoramic views; and 2) age, sex, implant length, implant type, installed location, occluding dentition state, and complication were investigated from the chart record. Results: The PMI showed moderate level of repeatability. The intra-observer agreement of MCI and GI were good. There was statistically significant difference in PMI between two groups. There were significant different patterns of distribution of MCI and GI between two groups. Among the panoramic indices, PMI and MCI showed significant correlation with dental implant failure. Conclusion: Panoramic indices can be used as reference data in estimating bone quality of edentulous patients who are to have implants installed in their mandibles.

• Imaging Science in Dentistry
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• v.35 no.1
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• pp.15-23
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• 2005

Purpose : To compare cephalometric measurement between measuring methods in digital and conventional lateral cephalometric radiograph. Materials and Methods : Twenty digital and conventional lateral cephalometric radiographs were selected. In digital group, cephalometric measurements were performed manually using hardcopies and automatically using $V-Ceph^{TM}$ program on the monitor. In conventional group, the same measurements were performed manually on conventional films, and for automatic measurement conventional films were digitized by scanner. All measurements were performed twice by 4 observers, and 24 cephalometric variables were calculated and the time spent for each measurement was recorded. The differences in measurements data and the time spent for each measurement were compared within each group. Intra-observer and inter-observer comparisons were performed. Results : In both groups, no statistically significant difference between manual and automatic measurements was observed and most of the variables didn't show statistically significant differences between methods. The observer with less experience tended to show statistically significant differences of measurements between methods, and differences from other observers. The differences of measurements between methods in digital group were lesser than those of conventional group with statistical significance in 8 variables out of 24. With automatic method and in digital group, the spent time was shorter. Conclusion : With direct digital radiograph, automatic method using manually idenitified landmarks can be preferable in cephalometric analysis. (Korean J Oral Maxillofac Radiol 2005; 35 : 15-23)

• Imaging Science in Dentistry
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• v.36 no.1
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• pp.55-62
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• 2006

Purpose : To find the cause of root curvature by use of panoramic and lateral cephalometric radiograph. Materials and Methods : Twenty six 1st graders whose mandibular 1st molars .just emerged into the mouth were selected. Panoramic and lateral cephalometric radiograph were taken at grade 1 and 6, longitudinally. In cephalometric radio graph, mandibular plane angle, ramus-occlusal plane angle, gonial angle, and gonion-gnathion distance (Go-Gn distance) were measured. In panoramic radio graph, elongated root length and root angle were measured by means of digital subtraction radiography. Occlusal plane-tooth axis angle was measured, too. Pearson correlations were used to evaluate the relationships between root curvature and elongated length and longitudinal variations of all variables. Multiple regression equation using related variables was computed. Results : The Pearson correlation coefficient between curved angle and longitudinal variations of occlusal plane-tooth axis angle and ramus-occlusal plane angle was 0.350 and 0.401, respectively (p<0.05). There was no significant correlation between elongated root length and longitudinal variations of all variables. The resulting regression equation was $Y=10.209+0.208X_1+0.745X_2$ (Y: root angle, $X_1$: variation of occlusal plane-tooth axis angle, $X_2$: variation of ramus-occlusal plane angle). Conclusion : It was suspected that the reasons of root curvature were change of tooth axis caused by contact with 2nd deciduous tooth and amount of mesial and superior movement related to change of occlusal plane.

• Imaging Science in Dentistry
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• v.36 no.1
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• pp.25-32
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• 2006

Purpose : To investigate the validity of digital image processing on panoramic radiographs in estimating bone quality before endosseous dental implant installation by correlating bone quality in radiographic images with clinical bone quality classification. Materials and Methods : An experienced surgeon assessed and classified bone quality for implant sites with tactile sensation at the time of implant placement. Including fractal dimension eighteen morphologic features of trabecular pattern were examined In each anatomical sites on panoramic radiographs. Finally bone quality of 67 implant sites were evaluated in 42 patients. Results : Pearson correlation analysis showed that three morphologic parameters had weak linear negative correlation with clinical bone quality classification showing correlation coefficients of -0.276, -0.280, and - 0.289, respectively (p<0.05). And other three morphologic parameters had obvious linear negative correlation with clinical bone quality classification showing correlation coefficients of -0.346, -0.488, and -0.343 respectively (p<0.05). Fractal dimension also had a linear correlation with clinical bone quality classification with correlation coefficients -0.506 significantly (p<0.05). Conclusion : This study suggests that fractal and morphometric analysis using digital panoramic radiographs can be used to evaluate bone quality for implant recipient sites.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.28 no.1
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• pp.65-72
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• 2010

In this study, the performances of a medium grade IMU which is aimed for Mobile Mapping System and a low grade IMU for pedestrian navigation are analyzed through simulations under GPS signal blockage. In addition, an analysis on the accuracy improvement of barometer, electronic compass, or multi-sensor(combination of barometer and electronic compass) to correct medium grade or low grade IMU errors in the situation of GPS signal blockage is performed. With the medium grade IMU, the three dimensional positioning error from INS exceeds the demanded accuracy of 5m when the block time is over 30 seconds. When we correct IMU with barometer, compass, or multi-sensor, however, the demanded accuracy is maintained up to 60 seconds. In addition, barometer is more effective than the electronic compass when they are combined. In case of low grade IMU like MEMS IMU, the three dimensional positioning error from INS exceeds the demanded accuracy of 20m when the block time is over 15 seconds. When we correct INS with barometer, compass, or multi-sensor, however, the demanded accuracy is maintained up to 15 seconds in simulation results. On the contrary to medium grade IMU, electronic compass is more effective than the barometer in case of low velocity such as pedestrian navigation. It is expected that the analysis suggested a method to decrease position or attitude error using aided sensor integration when MMS or pedestrian navigation is operated under 1he environment of GPS signal blockage.

• Journal of Dental Rehabilitation and Applied Science
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• v.32 no.1
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• pp.60-69
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• 2016

Purpose: The objective of this study was to compare the accuracy of digital models from 3 dimentional (3D) optical scanner and cone beam computed tomography (CBCT). Materials and Methods: We obtained digital models from 11 pairs of stone casts using a 3D optical scanner and a CBCT, and compared the accuracy of the models. Results: The error range of average positive distance was 0.059 - 0.117 mm and negative distance was 0.066 - 0.146 mm. Statistically (P < 0.05), average positive distance was larger than $70{\mu}m$ and shorter than $100{\mu}m$, and that of negative distance was larger than $100{\mu}m$ and shorter than $120{\mu}m$. Conclusion: We concluded that the accuracy of digital models generated from CBCT is not appropriate to make final prostheses. However, it may be acceptable for provisional restorations and orthodontic diagnoses with respect to the accuracy of the digitalization.

• Journal of Korean Ophthalmic Optics Society
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• v.7 no.2
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• pp.79-87
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• 2002

To analyze the current status of contact-lens in domestic, we analyzed the data of "The Spectacles-wearing Rate Analysis in 1999 (Korea Gallup Research)", "Industry current status(Korea Medical Instruments Industrial cooperative}", "Export & Import current status (Korea Customs Service)", and finally reached the following conclusions. 1. The number of contact-lens wearers in domestic could be assumed 2.13 millions. 2. The size of contact lens market in domestic(on year 2000 basis) was about 25.3 billion Korean wons(\) in total ; 10.8 billion Korean wons on the basis of production unit price (Domestic Gross Production Amount-Export Amount : used the subtraction in math), 14.5 billion Korean wons on Import unit price basis. 3. According to the year 2001 data, the import amount of contact lens is 1.7 times greater than export amount of that. 4. The contact lens export status in year 2001 was Japan, Singapore, Taiwan, U.S.A, China, Hong Kong, Malaysia, Thai, - in order. Especially, the contact lens export of China has increased gradually every year since 1998, the first export year of contact lens. 5. The import status of contact lens was U.S.A, Japan, England, Indonesia, Argentina, Taiwan, Hong Kong, - in order. In addition, the consumption trend of contact lens consumers in domestic reflects that famous foreign contact lens brands were much preferred than lower price contact lens imported from several developing countries.