• Journal of Astronomy and Space Sciences
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• v.24 no.2
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• pp.99-110
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• 2007

A total of 824 observations (206 in ${\Delta}B$, 206 in ${\Delta}V$, 206 in ${\Delta}R$, 206 in ${\Delta}I$ for CC Com were made on 3 nights from March 3 to April 3 in 2002 using the 61cm telescope with 2K CCD camera of the Sobaeksan Optical Astronomy Observatory of KASI. From our observations 9 times of minimum light were newly determined. Combined analysis of our new BVRI light curves with the double-lined radial velocity curves of Pribulla et al. (2007) were made with the 2004 Wilson-Devinney(WD) binary model code to yield new physical parameters of the CC Com system. Small asymmetries in light curves were explained with the adoption of two hot spots on the cool secondary.

• Journal of the Korean Society of Radiology
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• v.12 no.3
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• pp.289-295
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• 2018

Most diagnostic devices in the medical field use X-ray sources, which emit energy spectra. In radiological diagnosis, the quantitative and qualitative analyses of X-rays are essential for maintaining the image quality and minimizing the radiation dose to patients. This work aims to obtain the X-ray energy spectra used in diagnostic imaging by Monte Carlo simulation. Various X-ray spectra are simulated using a Monte Carlo simulation tool. These spectra are then compared to the reference data obtained with a tungsten anode spectral model using the interpolating polynomial (TASMIP) code. The X-ray tube voltages used are 50, 60, 80, 100, and 110 kV, respectively. CdTe and a-Se detector are used as the detectors for obtaining the X-ray spectra. Simulation results demonstrate that the various X-ray spectra are well matched with the reference data. Based on the simulation results, an appropriate X-ray spectrum, in accordance with the tube voltage, can be selected when generating an image for diagnostic imaging. The dose to be delivered to the patient can be predicted prior to examination in the diagnostic field.

• Journal of Korean Ophthalmic Optics Society
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• v.8 no.2
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• pp.77-83
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• 2003

To investigate the influence of the variation of conic coefficient of the front surface on the RMS SD(Root Mean Square Spot Diameter) in a back focal plane, we use programs which are Cove V and LOSA 2.0. We consider a spectacle lens with back vertex power of -4.00D, diameter of 70 mm, the front surface powers which are 2.00D, 4.00D, 6.00D, and 8.00D, and the indices which are $n_d$=1.498, 1.523, 1.586, and 1.660, respectively. The RMS SD in the back focal plane and the thickness of an aspherical tens having the optimized conic constant are smaller than those of a spherical lens. The RMS SD in the back focal plane decreases as the front surface power decreases. From these results, we determine the optimized conic constant to improve the optical image quality and decrease RMS SD in the back focal plane.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.11
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• pp.2480-2486
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• 2012

The design of low voltage LC-VCO(LC Voltage Controlled Oscillator) has been presented to optimize the phase noise and power consumption for the block of frequency synthesis to satisfy WCDMA system specification in this paper. The parameters for minimum phase noise has been obtained in the region of design, using the lines of the tuning range and the excess gain in the plane of the inductance and the transconductance of MOS transistor to compensate the loss of LC-tank. As a result of simulation, the phase noise characteristics is -113dBc/Hz for offset of 1MHz. The optimum designed LC-VCO has been fabricated using the process of 0.25um CMOS. As a result of measurement for fabricated chip, the phase noise characteristics is -116dBc/Hz for offset of 1MHz. The power consumption is 15mW, and Kvco is 370MHz/V.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.11A
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• pp.1244-1252
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• 2004

In this paper, we derive some properties of linear detectors (zero forcing or minimum mean square error) at spatial multiplexing systems with alamouti's space-time block code. Based on the derived properies, this paper proposes low-complexity receivers. Implementing MMSE detector adaptively, the number of weight vectors to be calculated and updated is greatly reduced with the derived properties compared to the conventional methods. In the case of recursive least square algorithm, with the proposed approach computational complexity is reduced to less than the half. We also identify that sorted QR decomposition detector, which reduces the complexity of V-Blast detector, has the same properties for unitary matrix Q and upper triangular matrix R. A complexity reduction of about 50%, for sorted QR decomposition detector, can be achieved by using those properties without the loss of performance.

• Journal of the Korean Solar Energy Society
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• v.25 no.3
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• pp.37-45
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• 2005

Higher requirement of advanced building design code and the development of construction technique have resulted in more thermal and air tight buildings. This has caused the sick building syndrome in a indoor air quality has been relatively getting worse. A new concept with a solar fresh air heating and electrostatic precipitator or called as STCC(Solar Transpired Collector and Cyclone) has been proposed to solve this IAQ issue. This paper describes the assessment study of STCC system under different outdoor airflow rates. The experiment was carried out under real condition with 30CMM STCC system test facility. Incense smoke was used to study the particle concentration decay trends under outdoor airflow rates 0CMM, 10CMM, 20CMM, 30CMM, with applied voltages of 5kV and 15kV for collecting and discharging electrodes of an Electrostatic Precipitator. Result shows that the particle decay increases by increasing the outdoor airflow rates. The collection efficiency, dust cleaning effectiveness(P) and application area calculation result comparisons have also been studied. This factors could be used to estimate how a dust of indoor air quality(IAQ) and removed for a building space with a STCC system.

• Nuclear Engineering and Technology
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• v.52 no.3
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• pp.568-574
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• 2020

The feasibility of the particle-in-cell (PIC) method is assessed to simulate the non-collective phenomena like non-collective Thomson scattering (TS). The non-collective TS in the laser-plasma interaction, which is related to the single-particle behavior, is simulated through a 2D relativistic PIC code (XOOPIC). For this simulation, a non-collective TS is emitted from a 50-50 DT plasma with electron density and temperature of n_e = 3.00 × 10¹³ cm^-3 and T_e = 1000 eV, typical for the edge plasma at ITER measured by ETS system, respectively. The wavelength, intensity, and FWHM of the laser applied in the ETS system are λ_i,0 = 1.064 × 10^-4 cm, I_i = 2.24 × 10¹⁷ erg=s·㎠, and 12.00 ns, respectively. The electron density and temperature predicted by the PIC simulation, obtained from the TS scattered wave, are n_e,TS = 2.91 × 10¹³ cm^-3 and T_e,TS = 1089 eV, respectively, which are in accordance with the input values of the simulated plasma. The obtained results indicate that the ambiguities rising due to the contradiction between the PIC statistical collective mechanism caused by the super-particle concept and the non-collective nature of TS are resolved. The ability and validity to use PIC method to study the non-collective regimes are verified.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.11
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• pp.48-55
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• 2009

This paper presents a high-speed Forward Error Correction (FEC) architecture based on three-parallel Reed-Solomon (RS) decoder for next-generation 100-Gb/s optical communication systems. A high-speed three-parallel RS(255,239) decoder has been designed and the derived structure can also be applied to implement the 100-Gb/s RS-FEC architecture. The proposed 100-Gb/s RS-FEC has been implemented with 0.13-${\mu}m$ CMOS standard cell technology in a supply voltage of 1.2V. The implementation results show that 16-Ch. RS-FEC architecture can operate at a clock frequency of 300MHz and has a throughput of 115-Gb/s for 0.13-${\mu}m$ CMOS technology. As a result, the proposed three-parallel RS-FEC architecture has a much higher data processing rate and low hardware complexity compared with the conventional two-parallel, three-parallel and serial RS-FEC architectures.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.5
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• pp.31-40
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• 2010

This paper describes a LDPC decoder for IEEE 802.11n wireless LAN standard. The designed processor supports parity check matrix for block length of 1,944 and code rate of 1/2 in IEEE 802.11n standard. To reduce hardware complexity, the min-sum algorithm and layered decoding architecture are adopted. A novel memory reduction technique suitable for min-sum algorithm was devised, and our design reduces memory size to 25% of conventional method. The LDPC decoder processor synthesized with a $0.35-{\mu}m$ CMOS cell library has 200,400 gates and memory of 19,400 bits, and the estimated throughput is about 135 Mbps at 80 MHz@2.5v. The designed processor is verified by FPGA implementation and BER evaluation to validate the usefulness as a LDPC decoder.

• Nuclear Engineering and Technology
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• v.48 no.3
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• pp.785-794
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• 2016

The Argonne National Laboratory of the United States and the Kharkov Institute of Physics and Technology of the Ukraine have been collaborating on the design, development and construction of a neutron source facility at Kharkov Institute of Physics and Technology utilizing an electron-accelerator-driven subcritical assembly. The electron beam power is 100 kW using 100-MeV electrons. The facility was designed to perform basic and applied nuclear research, produce medical isotopes, and train nuclear specialists. The biological shield of the accelerator building was designed to reduce the biological dose to less than 5.0e-03 mSv/h during operation. The main source of the biological dose for the accelerator building is the photons and neutrons generated from different interactions of leaked electrons from the electron gun and the accelerator sections with the surrounding components and materials. The Monte Carlo N-particle extended code (MCNPX) was used for the shielding calculations because of its capability to perform electron-, photon-, and neutron-coupled transport simulations. The photon dose was tallied using the MCNPX calculation, starting with the leaked electrons. However, it is difficult to accurately tally the neutron dose directly from the leaked electrons. The neutron yield per electron from the interactions with the surrounding components is very small, ~0.01 neutron for 100-MeV electron and even smaller for lower-energy electrons. This causes difficulties for the Monte Carlo analyses and consumes tremendous computation resources for tallying the neutron dose outside the shield boundary with an acceptable accuracy. To avoid these difficulties, the SOURCE and TALLYX user subroutines of MCNPX were utilized for this study. The generated neutrons were banked, together with all related parameters, for a subsequent MCNPX calculation to obtain the neutron dose. The weight windows variance reduction technique was also utilized for both neutron and photon dose calculations. Two shielding materials, heavy concrete and ordinary concrete, were considered for the shield design. The main goal is to maintain the total dose outside the shield boundary less than 5.0e-03 mSv/h during operation. The shield configuration and parameters of the accelerator building were determined and are presented in this paper.