• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.278-281
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• 2003

The p-CIn2Te4 single crystal was grown in the three-stage vertical electric furnace by using Bridgman method. The quality of the grown crystal has been investigated by the x-ray diffraction and the photoluminescence measurements. From the photoluminescence spectra of the as-grown CdIn2Te4 crystal and the various heat-treated crystals, the (Do, X) emission was found to be the dominant intensity in the photoluminescence spectrum of the CdIn2Te4:Cd, while the (Ao, X) emission completely disappeared in the CdIn2Te4:Cd. However, the (Ao, X) emission in the photoluminescence spectrum of the CdIn2Te4:Te was the dominant intensity like an as-grown CdIn2Te4 crystal. These results indicated that the (Do, X) is associated with VTe acted as donor and that the (Ao, X) emission is related to VCd acted as acceptor, respectively. The p-CdIn2Te4 crystal was found to be obviously converted into the n-type after annealing in the Cd atmosphere. The origin of (Do, Ao) emission and its TO phonon replicas is related to the interaction between donors such as VTe or Cdint, and accepters such as VCd or Teint. Also, the In in the CdIn2Te4 was confirmed not to form the native defects because it existed in the stable form of bonds.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.6
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• pp.1083-1088
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• 2016

25.8kV GIS part generated by sensors to measure contact an inflow of noise depending on the extent of the measured discharge occurs often not easy. Partial discharge signal measurement sensor suitable for developing a more useful measurements at the scene to this, partial discharge waveform analysis developed a sensor, and to utilize forSensor on the development of the most important is VSWR decided to (voltage standing wave ratio) voltage standing-wave ratio less than 1.5 and decided less than at the full spectrum bands that are measured, this time Return loss, as measured value by absolute criteria 14.0 dB produced the sensor, designed to or more. UHF 1.5~0.5 GHz bandwidth spectrum to be measured in GIS. UHF bands were designed to be able to measure the best signal. Recently, 25.8kV GIS production company has been increasing variety of GIS were made open spacer in partial discharge in accordance with the not very easy to detect the signal. The sensor is designed height of four cm external spacer is attachment GIS in an influx of outside noise measurement, and be so manufactured as to facilitate the least we've done. Also, since partial discharge which occur can measure the frequency of the 170kV GIS external partial-discharge signals that occur at the scene of insulation applied to the spacer. Features, and also derived good results using global positioning. Also measured discharge point about sensors that are stable and the reliability of the development and local substation equipment failure occurring signal analysis through the discharge for the prevention of widely. There should be to believe that used.

• Journal of Radiation Protection and Research
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• v.41 no.3
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• pp.185-190
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• 2016

Background: In order to measure neutron energy spectra, the conventional Bonner Sphere Spectrometers (BSS) are widely used. In this spectrometer, several measurements with different size Bonner spheres are required. Operators should, therefore, place these spheres in several times to a measurement point where radiation dose might be relatively high. In order to reduce this effort, novel neutron energy spectrometer using an onion-like single Bonner sphere was proposed in our group. This Bonner sphere has multiple sensitive spherical shell layers in the single sphere. In this spectrometer, a band-shaped thermal neutron detection medium, which consists of a LiF-ZnS mixed powder scintillator sheet and a wavelength-shifting (WLS) fiber readout, was looped to each sphere at equal angular intervals. Amount of LiF neutron converter is reduced near polar region, where the band-shaped detectors are concentrated, in order to uniform the directional sensitivity. The LiF-ZnS mixed powder has an advantage of extremely high light yield. However, since it is opaque, scintillation photons cannot be collect uniformly. This type of detector shows no characteristic shape in the pulse height spectrum. Subsequently, it is difficult to set the pulse height discrimination level. This issue causes sensitivity fluctuation due to gain instability of photodetectors and/or electric modules. Materials and Methods: In order to solve this problem, we propose to replace the LiF-ZnS mixed powder into a flexible and Transparent RUbber SheeT type $LiCaAlF_6$ (TRUST LiCAF) scintillator. TRUST LiCAF scintillator can show a peak shape corresponding to neutron absorption events in the pulse height spectrum. Results and Discussion: We fabricated the prototype detector with five sensitive layers using TRUST LiCAF scintillator and conducted basic experiments to evaluate the directional uniformity of the sensitivity. Conclusion: The fabricated detector shows excellent directional uniformity of the neutron sensitivity.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.37 no.5
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• pp.9-15
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• 2000

The 3 ${\mu}{\textrm}{m}$-thick PVDF (polyvinylidene fluoride) thin film have been prepared using physical vapor deposition with electric field, and its FT-IR spectrum, dielectric property and electric conduction phenomenon have been investigated. Since the characteristic peaks are detected at 509.45 ［$cm^{-1}$ /］ and 1273.6 ［$cm^{-1}$ /］in the FT-IR spectrum, we are confirmed that the $\beta$ -phase is dominant in the PVDF thin film. In the results of dielectric properties, the PVDF thin film shows anomalous dispersion, i.e. gradual decrease of dielectric constant with increase of frequency, and also that the dielectric absorption point changes from 200 Hz to 7000 Hz with increasing temperature of thin film, which is consistent with the Debye's theory. The activation energy ( $\Delta$H) obtained from temperature dependence of dielectric loss is 21.64 ㎉/mole. We confirm that the electric conduction mechanism of PVDF thin film is dominated by ionic conduction by investigating the dependence of the leakage current of the thin film on the temperature and the electric field.

• Journal of Radiation Industry
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• v.11 no.3
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• pp.157-165
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• 2017

In this paper, we calculate the light photons collection efficiency of large-volume plastic scintillation detector mainly used for radiation portal monitor (RPM). A Monte Carlo light photon transport code, DETECT2000, were used to quantitatively evaluate light collection efficiency of plastic scintillation detector. DETECT2000 calculated the placement of light collection efficiency based on the energy spectrum. We calculated the light collection efficiency relative to the position of the energy spectrum that proportional to the placement of the source. The $850{\times}285{\times}65mm^3$ size of polyvinyl toluene (PVT) scintillator was used for measurements. Through DETECT2000 simulation, the light collection efficiency of $5{\times}5$ arrays were calculated and verification was performed by comparing with experimentally measured. And then, the corrected MCNP simulation by applying the light collection efficiency in $21{\times}13$ arrays was compared and analyzed. Comparing the Monte Carlo simulation with measured results, it shows an average difference of 10.1% in $5{\times}5$ arrays. Particularly, about twice of the difference was found in the edge of first column, which coupled with PMT. In whole $5{\times}5$ array, the overall ratio was the same except for the first column. And then comparing the energy spectra of the $21{\times}13$ array with and without the light collection efficiency, it shows a difference of 6.69% in Compton edge area. The DETECT2000 based light collection efficiency simulation showed well agreement with the point source experiment. And comparing with measured energy spectra, we could compare the differences according to whether or not the light collection efficiency was applied. As a results, it is possible to increase the accuracy and reliability of Monte Carlo simulation results by pre-calculating the light collection efficiency according to the PVT geometry by using the DETECT2000.

• Korean Journal of Materials Research
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• v.13 no.3
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• pp.195-199
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• 2003

The $p-CdIn_2$$Te_4$single crystal was grown in the three-stage vertical electric furnace by using Bridgman method. The quality of the grown crystal has been investigated by the x-ray diffraction and the photoluminescence measurements. From the photoluminescence spectra of the as-grown $CdIn_2$$Te_4$crystal and the various heat-treated crystals, the ($D^{\circ}$, X) emission was found to be the dominant intensity in the photoluminescence spectrum of the $CdIn_2$T $e_4$:Cd, while the ($A^{\circ}$, X) emission completely disappeared in the $CdIn_2$T $e_4$:Cd. However, the ($A^{\circ}$, X) emission in the photoluminescence spectrum of the $CdIn_2$T $e_4$:Te was the dominant intensity like an as-grown $CdIn_2$T $e_4$crystal. These results indicated that the ($D^{\circ}$, X) is associated with $V_{Te}$ acted as donor and that the ($A^{\circ}$, X) emission is related to $V_{cd}$ acted as acceptor, respectively. The $p-CdIn_2$T $e_4$crystal was found to be obviously converted into the n-type after annealing in the Cd atmosphere. The origin of ( $D^{\circ}$, $A^{\circ}$) emission and its TO phonon replicas is related to the interaction between donors such as $V_{Te}$ or $Cd_{int}$, and accepters such as $V_{cd}$ or T $e_{int}$. Also, the In in the $CdIn_2$X$CdIn_4$was confirmed not to form the native defects because it existed in the stable form of bonds.

• Journal of Sensor Science and Technology
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• v.15 no.6
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• pp.379-385
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• 2006

Single crystal of p-$CdIn_{2}Te_{4}$ was grown in a three-stage vertical electric furnace by using Bridgman method. The quality of the grown crystal has been investigated by x-ray diffraction and photoluminescence measurements. From the photoluminescence spectra of the as-grown $CdIn_{2}Te_{4}$ crystal and the various heat-treated crystals, the ($D^{o}$, X) emission was found to be the dominant intensity in the photoluminescence spectrum of the $CdIn_{2}Te_{4}$:Cd, while the ($A^{o}$, X) emission completely disappeared in the $CdIn_{2}Te_{4}$:Cd. However, the ($A^{o}$, X) emission in the photoluminescence spectrum of the $CdIn_{2}Te_{4}$:Te was the dominant intensity like in the as-grown $CdIn_{2}Te_{4}$ crystal. These results indicated that the ($D^{o}$, X) is associated with $V_{Te}$ which acted as donor and that the ($A^{o}$, X) emission is related to $V_{Cd}$ which acted as acceptor, respectively. The p-$CdIn_{2}Te_{4}$ crystal was obviously found to be converted into n-type after annealing in Cd atmosphere. The origin of ($D^{o},{\;}A^{o}$) emission and its to phonon replicas is related to the interaction between donors such as $V_{Te}$ or $Cd_{int}$, and acceptors such as $V_{Cd}$ or $Te_{int}$. Also, the In in the $CdIn_{2}Te_{4}$ was confirmed not to form the native defects because it existed in a stable bonding form.

• Journal of KIISE:Computer Systems and Theory
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• v.37 no.3
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• pp.184-193
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• 2010

This paper proposes a biological iridescence BRDF(Bidirectional Reflectance Distribution Function) compression and rendering method. In the graphics technology, iridescence sometimes is named structure colors. The main features of these symptoms are shown transform of color and brightness by varying viewpoint. Graphics technology to render this is the BRDF technology. The BRDF methods enable realistic representation of varying view direction, but it requires a lot of computing power because of large data. In this paper, we obtain reflection map from iridescence BRDF, analyze color of reflection map and propose representation method by several colorfully concentric circle. The one concentric circle represents beam width of reflection ray by one normal vector. In this paper, we synthesize rough concentric by using several virtually optical normal vectors. And we obtain spectrum information from concentric circles passing through the center point. The proposed method enables IBR(image based rendering) technique which results is realistic illuminance and spectrum distribution by one texture from reduced BRDF data within spectrum.

• Journal of the Earthquake Engineering Society of Korea
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• v.15 no.4
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• pp.23-31
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• 2011

To investigate the performance of apartment buildings which were built in the 1990s and which have RC bearing wall systems with coupling beams, construction drawings of 13 buildings were collected and analyzed. To evaluate the seismic performance, FEMA 356 and FEMA 440 were selected as guidelines. For the demand curve, the seismic design spectrum in KBC 2009 is used. For each building, the performance points for life safety and the collapse prevention state are calculated. It was found that 9 out of 13 buildings (about 70%) showed damage more severe than the collapse prevention level at the performance point and more damage could be seen at the coupling beams than the walls. However, the story drift limit of FEMA 356 was satisfied for all buildings. Through the analysis of performance points, it was shown that the spectral acceleration has an inverse relationship with the natural period.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.21 no.2
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• pp.154-163
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• 2009

Incident wave angles are conventionally estimated by the directional spectrum analysis of wave data collected from in-situ sensors. The in-situ measurements are limited in monitoring incident wave angles in the wide surf zone, since the techniques are typically expensive, labor-intensive, and point-measuring. In this study, estimation of incident wave angles using wave crest features captured in digital video imagery is proposed to observe incident wave directions over the surf zone. Line signatures of wave crests having high image pixel intensities are extracted by moving an interrogation window to identify high intensity pixels in sequential video images. Wave angles are computed by taking the first derivative of the extracted crest signatures, i.e. local slope of the crest signatures in the two-dimensional physical plane. Compared to the wave angle estimates obtained by the directional spectrum analysis, video-based wave angle estimates show good agreements in general.