• Korean Journal of Digital Imaging in Medicine
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• v.3 no.1
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• pp.126-132
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• 1997

Purpose : To apply to Program of Auto processor quality control after comparison of Film density variations with amendments to Auto density by using Check density program and Adjust density program of calibration mode into the Laser imager. Methods : Observe Check and Adjust density variations on the Control chart with standard step and value during seven months from December, 1995 to June, 1956 extending twice a week. (1) Measure density value on the steps after printing out 17-step sensitometric pattern of the Check density program. (2) In the same way, measure density values after amending density by using Adjust density program If they are exceeding allowable error limit. Results : In case of Check density program, the exceeding limit rates of Density difference(DD) and Middle density(MD) are: FL-IM3543 DD=75%. MD=72.5%, FL-IMD DD=0%. MD=30.8%(14.5%) After amending density by using Adjust density program, the exceeding limit rates of all both Laser imager were zero percent. The standard deviations are show lower FL-IM D than FL-IM3543 on the Check density control chart, but higher on the Adjust density control chart. Conclusion : (1) Check density variations by printingout sensitometric pattern extending once a week at least for quality control of the Laser imager. (2) In case of a dusty place, check the Laser beam transmission after cleaning Laser optical unit extending once a month. (3) Be sure to measure and check density values by using adjust density program if they are exceeding allowable error limit. (4) Maintain much better film density by performing the adjust density program even if check density values are existed within normal limit.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.8
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• pp.52-59
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• 2007

In this paper, we analyzed and measured implant isolation characteristics for a 1.25 Gbps monolithic integrated hi-directional (M-BiDi) optoelectronic system-on-a-chip, which is a key component to constitute gigabit passive optical networks (PONs) for a fiber-to-the-home (FTTH). Also, we derived an equivalent circuit of the implant structure under various DC bias conditions. The 1.25 Gbps M-BiDi transmit-receive SoC consists of a laser diode with a monitor photodiode as a transmitter and a digital photodiode as a digital data receiver on the same InP wafer According to IEEE 802.3ah and ITU-T G.983.3 standards, a receiver sensitivity of the digital receiver has to satisfy under -24 dBm @ BER=10-12. Therefore, the electrical crosstalk levels have to maintain less than -86 dB from DC to 3 GHz. From analysed and measured results of the implant structure, the M-BiDi SoC with the implant area of 20 mm width and more than 200 mm distance between the laser diode and monitor photodiode, and between the monitor photodiode and digital photodiode, satisfies the electrical crosstalk level. These implant characteristics can be used for the design and fabrication of an optoelectronic SoC design, and expended to a mixed-mode SoC field.

• Korean Journal of Remote Sensing
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• v.34 no.3
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• pp.545-552
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• 2018

Grounding line is used as evidence of the mass balance showing the vulnerability of Antarctic glaciers and ice shelves. In this research, we utilized a high resolution digital elevation model of glacier surface derived by recently launched satellites to estimate the position of grounding line of Campbell Glacier in East Antarctica. TanDEM-X and TerraSAR-X data in single-pass interferometry mode were acquired on June 21, 2013 and September 10, 2016 and CryoSat-2 radar altimeter data were acquired within 15 days from the acquisition date of TanDEM-X. The datasets were combined to generate a high resolution digital elevation model which was used to estimate the grounding line position. During the 3 years of observation, there weren't any significant changes in grounding line position. Since the average density of ice used in estimating grounding line is not accurately known, the variations of the grounding line was analyzed with respect to the density of ice. There was a spatial difference from the grounding line estimated by DDInSAR whereas the estimated grounding line using the characteristics of the surface of the optical satellite images agreed well when the ice column density was about $880kg/m^3$. Although the reliability of the results depends on the vertical accuracy of the bathymetry in this study, the hydrostatic ice thickness has greater influence on the grounding line estimation.

• 한국해양학회지
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• v.27 no.1
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• pp.19-34
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• 1992

Marine seismic refraction surveys have been carried out by Korea Institute of Geology, Mining and Materials(KIGAM) since 1984. The recording of refraction data was based on analog instrumentation. Therefore the resolution of refraction data was not good enough to distinguish many layers. The objective of the interpretation of seismic refraction data is the determination of intervals and critically refracted seismic wave propagation velocities through the layers beneath the sea floor. To determine intervals and velocities precisely, the resolution of refraction data should be enhanced. The intent of the study is to improve the quality of shallow marine refraction data by the digital technique using microcomputer- based acquisition and processing system. The system consists of an IBM AT microcomputer clone, an analog-digital(A/D) converter. A mass storage unit and a parallel processing board. The A/D converter has 12 bits of precision and 250 kHz of conversion rate. The magneto-optical disk drive is used for the mass storage of seismic refraction data. Shallow marine seismic refraction surveys have been carried out using the system at 6 locations off Ulsan and Pusan area. The refraction data were acquired by the radio sonobuoy. The refraction profiles have been produced by the laser printer with 300 dpi resolution after the basic computer processing. 5-9 layers were interpreted from digital refraction profiles, whereas 2-4 layers were interpreted from analog refraction profiles. the propagation velocities of sediments were interpreted as 1.6-2.1 km/sec. The propagation velocities of acoustic basement were interpreted as 2.4-2.7 km/sec off Ulsan area, 4.8 km/sec off Pusan area.

• Journal of Korea Society of Industrial Information Systems
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• v.11 no.2
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• pp.79-85
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• 2006

As the portable information appliance is developed, the demand of flat panel display equipments and parts are steeply increased. Most of all, the applications of LCD such as LCD TV, monitor, digital camera, CNS(car navigation system) and game machine become diversified. With the result that the number of BLU production enterprise is increased and the research on the design of backlight with the superior optical properties is persistently in progress. In this study we developed the pattern design tools for CCFL(cold cathode flourescent lamp) backlight to improve the conventional pattern design environment in which the pattern is designed manually from the experience and the trial and error. For the verification of our research, we designed the light reflection surface patterns for a real model of backlight and we measured the brightness uniformity using the BM-7. From the brightness uniformity measurement, the BLU designed using the presented tool showed the tolerable performance only in the first try of pattern design rather than the fifth try of pattern design in case of the conventional pattern design.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.12
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• pp.1588-1594
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• 2020

In this paper, we discuss a data balancing method for learning a neural network that generates digital holograms using a deep neural network (DNN). Deep neural networks are based on deep learning (DL) technology and use a generative adversarial network (GAN) series. The fringe pattern, which is the basic unit of a hologram to be created through a deep neural network, has very different data types depending on the hologram plane and the position of the object. However, because the criteria for classifying the data are not clear, an imbalance in the training data may occur. The imbalance of learning data acts as a factor of instability in learning. Therefore, it presents a method for classifying and balancing data for which the classification criteria are not clear. And it shows that learning is stabilized through this.

• The Journal of Advanced Prosthodontics
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• v.13 no.4
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• pp.191-204
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• 2021

PURPOSE. The purpose of this study is to present a methodology to evaluate the accuracy of intraoral scanners (IOS) used in vivo. MATERIALS AND METHODS. A specific feature-based gauge was designed, manufactured, and measured in a coordinate measuring machine (CMM), obtaining reference distances and angles. Then, 10 scans were taken by an IOS with the gauge in the patient's mouth and from the obtained stereolithography (STL) files, a total of 40 distances and 150 angles were measured and compared with the gauge's reference values. In order to provide a comparison, there were defined distance and angle groups in accordance with the increasing scanning area: from a short span area to a complete-arch scanning extension. Data was analyzed using software for statistical analysis. RESULTS. Deviations in measured distances showed that accuracy worsened as the scanning area increased: trueness varied from 0.018 ± 0.021 mm in a distance equivalent to the space spanning a four-unit bridge to 0.106 ± 0.08 mm in a space equivalent to a complete arch. Precision ranged from 0.015 ± 0.03 mm to 0.077 ± 0.073 mm in the same two areas. When analyzing angles, deviations did not show such a worsening pattern. In addition, deviations in angle measurement values were low and there were no calculated significant differences among angle groups. CONCLUSION. Currently, there is no standardized procedure to assess the accuracy of IOS in vivo, and the results show that the proposed methodology can contribute to this purpose. The deviations measured in the study show a worsening accuracy when increasing the length of the scanning area.

• The Journal of Korean Academy of Prosthodontics
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• v.62 no.2
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• pp.95-103
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• 2024

Purpose. With the advancement of digital technology, 3D printing is being utilized in the fabrication of denture base. Nevertheless, increasing microbial adhesion to the surface of denture base has been reported as the disadvantage of 3D-printed denture base. The purpose of this study is to investigate the antifungal properties and flexural strength of 3D-printed denture base resin according to the different contents of titanium dioxide nanoparticles. Materials and methods. Titanium dioxide nanoparticles were mixed with the 3D printing resin at the ratios of 0.5, 1, 1.5, and 2 wt%. Twenty specimens per each group were printed in the form of cylindrical shape (diameter: 20 mm, height: 3 mm) to evaluate antifungal properties. Ten specimens from each group underwent polishing using autogrinder, while the remaining ten specimens did not. Candida albicans in hyphae form was inoculated onto each specimen, optical density and colony-forming unit were analyzed. The surface of the specimen was observed using scanning electron microscopy. To evaluate the flexural strength, twenty specimens per each group were 3D printed in the form of rectangular prism shape (length: 64 mm, height: 10 mm, width: 3 mm) and three-point bending tests were conducted using universal testing machine according to ISO 20795-1. Results. Colony-forming unit of C.albicans and optical density of culture medium showed no difference between non-polished groups, but decreased in the polished groups at concentration of 1, 1.5, 2 wt% titanium dioxide nanoparticles. Flexural strength increased with titanium dioxide nanoparticle at concentration of 0.5, 1, 1.5 wt%, but decreased at 2 wt% compared to 1.5 wt%. Conclusion. When 1.5 wt% of titanium dioxide nanoparticles were added to the 3D-printed denture base resin with polishing, antifungal properties were increased.

• Korean Journal of Remote Sensing
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• v.20 no.2
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• pp.91-102
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• 2004

This paper reflects the estimation of using the EOC(Electro-optical Camera) images supporting GIUH(geomorphological instantaneous unit hydrograph) approach. We have analyzed GIUH in its density and frequency distribution by creating a DEM(digital elevation model) for the sub basin produced from the EOC images and examined topographical and hydrological application possibility of the EOC images. In this process, we have topographical basin characteristic analysis that use the remote sensing technique analyzing the DEM creation process of the EOC stereo images by studying the basic topographical hydrology analysis about abstraction technique since it is flirty complex and is more time-consuming than other method. we executed statistical analysis of a basin size and river length using the frequency function after divided lattice spacing applied have to the sub river basin from the image data and the digital map into 10m intervals ranging from 10m to 100m. After comparing and examining the peak and time to peak of the GIUH, we proceeded with a comparative analysis by lattice concerning the topographical divergence rate, area ratio, length ratio. Accumulating the peak and time to peak of the GIUH is altered to non-linear form in accordance to lattice dimension as well as basin factor. It was proved that the lattice dimension is one of the important factors about the peak and time to peak of the GIUH.

• The Journal of Korean Academy of Prosthodontics
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• v.42 no.2
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• pp.192-209
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• 2004

Purpose : The purpose of this study was to evaluate the machining accuracy and consistency of implant/abutment/screw combination or internal connection type. Material and methods: In this study, each two randomly selected internal implant fixtures from ITI, 3i, Avana, Bicon, Friadent, Astra, and Paragon system were used. Each abutment was connected to the implant with 32Ncm torque value using a digital torque controller or tapping. All samples were cross-sectioned with grinder-polisher unit (Omnilap 2000 SBT Inc) after embeded in liquid unsaturated polyester (Epovia, Cray Valley Inc). Then optical microscopic and scanning electron microscopic(SEM) evaluations of the implant-abutment interfaces were conducted to assess quality of fit between the mating components. Results : 1) Generally, the geometry of the internal connection system provided for a precision fit of the implant/abutment into interface. 2) The most precision fit of the implant/abutment interface was provided in the case of Bicon System which has not screw. 3) The fit of the implant/abutment interface was usually good in the case of ITI, 3I and Avana system and the amount of fit of the implant/abutment interface was similar to each other. 4) The fit of the implant/abutment interface was usually good in the case of Friadent, Astra and Paragon system. The case of Astra system with the inclined contacting surface had the most Intimate contact among them. 5) Amount of intimate contact in the abutment screw thread to the mating fixture was larger in assembly with two-piece type which is separated screw from abutment such as Friadent, Astra and Paragon system than in that with one-piece type which is not seperated screw from abutment such as ITI, 3I and Avana system. 6) Amount of contact in the screw and the screw seat of abutment was larger in assembly of Friadent system than in asembly of Astra system of Paragon system. Conclusion: Although a little variation in machining accuracy and consistency was noted in the samples, important features of all internal connection systems were the deep, internal implant-abutment connections which provides intimate contact with the implant walls to resist micro-movement, resulting in a strong stable interface. From the results of this study, further research of the stress distribution according to the design of internal connection system will be required.