• Korean Journal of Digital Imaging in Medicine
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• v.5 no.1
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• pp.130-136
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• 2002

One of current trends of medical technology is analog to digital. Moreover, The Government put a premium on PACS(Picture Archiving and Communication System) for Medical Insurance in November, 1999. Therefore many hospitals are installing(or planning to install) PACS facilities on their buildings. However most of hospitals didn't consider PACS facilities in the beginning of construction. In particular, the Networking is one of the most difficult things for PACS installation. There is no space for network equipments, and no path for network lines, etc. To solve these problems, wireless network is proposed. The wireless network is divided to three parts mainly. One is the wireless communication for Local Area Network, another is the data transmission through a satellite for Tele-Radiology, and the last one is the technology using Bluetooth for each sub-system of PACS. But there are other problems in wireless systems, i.e., network bandwidth, system stability, interference with other devices. The purpose of this paper is to suggest the future and new trend of PACS including all the problems.

• Proceedings of the IEEK Conference
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• 2002.07c
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• pp.1571-1574
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• 2002

This paper describes a circuit and its operations of a programmable digital on-chip terminator designed with CMOS circuits which are used in high speed I/O interface. The on-chip terminator matches external reference resistor with the accuracy of ${\pm}$ 4.1％ over process, voltage and temperature variation. The digital impedance codes are generated in programmable impedance controller (PIC), and the codes are sent to terminator transistor arrays at input pads serially to reduce the number of signal lines. The transistor array is thermometer-coded to reduce impedance glitches during code update and it is segmented to two different blocks of thermometer-coded transistor arrays to reduce the number of transistors. The terminator impedance is periodically updated during hold time to minimize inter-symbol interferences.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.16 no.6
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• pp.498-508
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• 1991

This thesis presents a performance analysis algorithm that estimates erro performance of individual links, at the bit level, in an end-to-end digital connection using the model of 3-statte MarKov chain. The link model proposed the burst error behavior of each individual link. It also presents a method to concateante several individual links and extract a model for end-to-end digital connection. This resulting end-to-end model can be used to calculate performance parameters such as bit error rate(BER) and block error(BLER) for any block size.

• Proceedings of the KSR Conference
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• 2003.05a
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• pp.326-330
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• 2003

The purpose of this study was to develop railroad geotechnical management system using Web GIS and the DB used in system included railroad informations and digital maps. Digital maps are primarily based on a topographical map(NGIS, 1:5000) and by adding digital maps(KRRI, 1:5000) and their spatial database system to NGI code layer, the management system was developed. The system was connected to geotechnical database already developed. The system was able to separate three parts which were layer choice, geotechnical information view and geotechnical analysis and it was possible to save geotechnical and spatial informations using ZEUS DB simultaneously. ZEUS/X was used for usefulness of GIS operation and by offering GUI, user interface for facility was achieved. Geotechnical and spatial informations in this system will provide basic data for plans, design and construction of railway lines in practical use.

• Proceedings of the IEEK Conference
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• 2002.07a
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• pp.523-526
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• 2002

The crosstalk among coupled microstrip lines is the major limiting factors of signal qualities in the high-speed digital and communication equipment. In this paper, a three-dimensional finite difference time domain (FDTD) method is applied to analyze the crosstalk between the coupled microstrip lines. The proposed structures of the coupled microstrip lines are investigated to reduce the coupling in a simple way by modifying their ground plane with an optimum gap. The examples of these structures with the different sizes of the gaps on their ground plane are studied. These structures are considered as the four-port network to evaluate transmission efficiency, near- and far-end crosstalk. Gaussian pulse is excited to evaluate the frequency characteristics from dc to 30 ㎓. The transmission efficiency, near- and far-end crosstalk of each structure of the coupled microstrip lines are demonstrated. The numerical results of this study show that the majority of crosstalk is the far-end crosstalk. The usage of the optimum gap on the ground plane can reduce the far-end crosstalk of the coupled microstrip lines while the transmission efficiency is nearly equal.

• Journal of Astronomy and Space Sciences
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• v.34 no.2
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• pp.161-170
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• 2017

In this study, the characteristics of a horizontal sundial from the Joseon Dynasty were investigated. Korea's Treasure No. 840 (T840) is a Western-style horizontal sundial where hour-lines and solar-term-lines are engraved. The inscription of this sundial indicates that the latitude (altitude of the north celestial pole) is $37^{\circ}$ 39', but the gnomon is lost. In the present study, the latitude of the sundial and the length of the gnomon were estimated based only on the hour-lines and solar-term-lines of the horizontal sundial. When statistically calculated from the convergent point obtained by extending the hour-lines, the latitude of this sundial was $37^{\circ}$ $15^{\prime}{\pm}26^{\prime}$, which showed a 24' difference from the record of the inscription. When it was also assumed that a convergent point is changeable, the estimation of the sundial's latitude was found to be sensitive to the variation of this point. This study found that T840 used a vertical gnomon, that is, perpendicular to the horizontal plane, rather than an inclined triangular gnomon, and a horn-shaped mark like a vertical gnomon is cut on its surface. The length of the gnomon engraved on the artifact was 43.1 mm, and in the present study was statistically calculated as $43.7{\pm}0.7mm$. In addition, the position of the gnomon according to the original inscription and our calculation showed an error of 0.3 mm.

• Journal of the Korea Institute of Military Science and Technology
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• v.12 no.4
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• pp.452-459
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• 2009

A 6-bit MMIC digital attenuator applicable to X-band TR module has been developed by using $0.5{\mu}m$GaAs pHEMT processes. The Switched-T attenuator scheme and the switched-path attenuator scheme were adopted to obtain low insertion loss and small phase variation, respectively. Resistors and transmission lines are optimized to achieve the digital attenuator with high attenuation accuracy and small phase variation. The digital attenuator has RMS error of 0.4dB, resolution of 0.5dB and dynamic range of 31.5dB. The measurement results show that in-out VSWRs are less than 1.5, phase variation is from -7 to +2 degrees and IIP3 is 36.5dBm.

• Korean Journal of Computational Design and Engineering
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• v.10 no.3
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• pp.210-216
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• 2005

Digital manufacturing could be very effective in shipbuilding in order to estimate the process time, to improve the operation efficiency, and to prevent bottleneck processes in advance. The subassembly process having done research consists of piece arrangement, tack welding, robot welding, manual welding and so on. The robot welding of them was the focus of the simulation. The analysis and modeling were carried out by using UML (Unified Modeling Language) as well as $IDEF\phi$ (Integration DEFinition). The characteristics of the process resources were analyzed using the shipyard data, and the layout of the subassembly line was designed with the resources. Using the constructed resource and process model, the productivity and efficiency of changed robot welding stage were investigated. It was simulated how much the variations in the resource performance have influence on improvement of productivity. One of the important outputs in this simulation was the cycle time during a certain period's work. The cycle time prediction was also undertaken for the different torch and the different piece arrangement. The proposed model was established three-dimensionally in a digital environment so that interferences among objects and space allocations for the resources could be easily investigated.

• Journal of IKEEE
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• v.23 no.3
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• pp.873-877
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• 2019

In this paper, we analyze the degree of digital noise coupling for Inverted F Antenna (IFA) and Loop Antenna, which are representative types of portable terminal antenna, using characteristic mode. Firstly, the degree of coupling according to the direction of digital signal lines and characteristic mode current of the printed circuit board (PCB) including the antenna is compared and analyzed, and based on this result, the coupling between WiFi antenna and the front camera noise is analyzed. For analysis, the digital signal line and ground line of the FPCB of the camera module are modeled as a loop feeder that excites the characteristic mode of the PCB ground and the change of noise coupling according to the antenna types are analyzed.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.11 no.1
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• pp.33-40
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• 1981

The author studied on the effects of x-irradiation to the development of digital malformation in gestation rats. The time-matings occured between 6 p.m. and 8 a.m. and females with copulation. plugs at 8 a.m. were isolated and properly marked for evidence of copulation. The lower abdomen of mothers were exposed to x-irradiation on the 11½th day of gestation, the critical period developing digital malformation, respectively 100, 150, 200, 250, 300 and 350 rads. At 18½th day of post-conception total 50 pregnant females were dissected and the incidence of digital malformations were obtained. Rat embryos on the 12, 13, 14, 15, 16th day of gestation irradiated by 250 rads were examined for morphogenesis of digital malformation. Digital radiating lines were examined in water and histologically by H-E stain. Supra vital stain samples by Nile-blue sulfate in 37℃ normal saline were prepared for the observation of cell necrosis regions and morphogenesis of digits. The results obtained were as follows; 1. By x-irradiation on 11th day of gestation, digital malformations of Ectrodactylia, Syndactylia Polydactylia and Hematodactylia were developed. Ectrodactylia showed the effective relationship to the amount of irradiation, however Syndactylia ans Polydactylia did not. 2. By x-irradiation, cell necrosis of digital germ was appeared markedly, but in 48 hours after irradiation was depressed to the periphery of digital germ and in 72hours after irradiation was disappeared. Digital radiating line showed marked stage of malformation in 48hours after irradiation and continued to show the same amount of physiological cell necrosis as the compared control group in 72hours. after irradiaion. But in the Syndactylia, physiological cell necrosis was not able to be recognized. 3. Ectrodactylia induced by x-irradiation was considered as the direct resoult of cell necrosis of digital origin, however, Polydactylia and Syndactylia were considered as the resoult of some effect in repair process of x-irradiation damages.