• The Journal of the Korea institute of electronic communication sciences
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• v.18 no.6
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• pp.1049-1056
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• 2023

The height of the atmospheric boundary layer indicates the peak developed when turbulence is generated by mixing heat and water vapor, and is generally determined through thermodynamic methods. Wind profilers produce atmospheric information from the scattering of signals sent into the atmosphere. A method for making the spectrum of turbulent components, turbulent kinetic energy dissipation rate, and refractive index structure coefficient was presented to determine the atmospheric boundary layer depth. Compared with the vertical distribution characteristics of potential temperature and specific humidity based on radiosonde data, the determination method of the atmospheric boundary layer height from wind profiler output was evaluated as very useful.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.8
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• pp.772-780
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• 2013

The high-altitude electromagnetic pulse(HEMP) conducted environment and the HEMP radiated environment are established as the consequences of a high-altitude nuclear explosion. The IEC 61000-2-10, the international standard, defines the HEMP conducted environment. The IEC 61000-5-5 defines how protective devices for conducted disturbance proposed for HEMP protection shall be specified. The IEC 61000-4-24 deals with methods for testing protective devices for HEMP conducted disturbance. The IEC 61000-4-24:1997 mainly describes the measurement method of small protective components. However, it does not provide the measurement method for a combination filter of a protective component and a filter which is widely used in recent. It is important to consider the characteristic of the measurement setup parameters like thickness and length of the cable and its height above ground plane etc. in establishing measurement setup because HEMP conducted disturbances include the frequency spectrum below 50 MHz. This paper deals with the optimized measurement method, considering the frequency spectrum of HEMP conducted disturbance, current waveform, and analyzing the effects of cables existing in the measurement setup.

• Journal of Sensor Science and Technology
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• v.23 no.1
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• pp.29-34
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• 2014

A dosimeter using tissue-equivalent scintillator by photon-counting method was developed and evaluated in its performance. The dosimeter is portable and can be operated by low power from lap-top computer. A data-acquisition software of the dosimeter system was developed by Labwindows/CVI based on Windows. The energy to channel ratio for energy calibration was 0.839 keV/ch. obtained from pulse height spectrum of $^{137}Cs$ and $^{60}Co$ gamma-ray. Using the dosimeter system, the absorbed dose of environmental radiation in Gyungju was 0.18 ${\mu}Sv/h$.

• Journal of Radiation Protection and Research
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• v.11 no.1
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• pp.3-14
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• 1986

A stud has been carried out for figuring out real photon spectrum from an observed gamma-ray spectrum by means of response matrix method, which is known one of the relatively convenient method for the estimation of exposure rate of a complex gamma ray field in comparison with graphical analysis and least square fitting of the measured spectrum. A 3'${\times}$3' cylindrical Nal(T1) scintillation detector in association with multichannel pulse height analyzer and six reference gamma ray sources covering the photon energy range of 0.05 to 2.0 MeV were used. In dividing the energy region for the construction of response matrix, two different approaches were attempted. One is dividing the entire energy region of interest into 20 bins, one of which corresponds to a width of 0.1 MeV to form $20{\times}20$ matrix, and another is dividing the 2 MeV region into 14 bins to form $14{\times}14$ matrix consists of $0.1(MeV)^{1/2}$ intervals assuming the resolution of the detector is dependent on square root of the incident photon energy. Inversion of thus constructed matrices was performed by a computor(P-E8/32) using the program attached to the end of this paper. The resultant exposure rates obtained by this method were in good agreement, within 10% with those calculated by ordinary formula widely used for a gamma-ray field of known energy and flux. It is concluded that the photen flux obtained by the response matrix constructed under the assumption of $E^{1/2}$ dependence is more realistic than that obtained by the matrix consist of identical energy bins in dosimetrical point of view.

• Journal of Radiation Protection and Research
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• v.37 no.2
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• pp.70-74
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• 2012

Silicon carbide (SiC) is a promising material for neutron detection at harsh environments because of its capability to withstand strong radiation fields and high temperatures. Two PIN-type SiC semiconductor neutron detectors, which can be used for nuclear power plant (NPP) applications, such as in-core reactor neutron flux monitoring and measurement, were designed and fabricated. As a preliminary test, MCNPX simulations were performed to estimate reaction probabilities with respect to neutron energies. In the experiment, I-V curves were measured to confirm the diode characteristic of the detectors, and pulse height spectra were measured for neutron responses by using a $^{252}Cf$ neutron source at KRISS (Korea Research Institute of Standards and Science), and a Tandem accelerator at KIGAM (Korea Institute of Geoscience and Mineral Resources). The neutron counts of the detector were linearly increased as the incident neutron flux got larger.

• Journal of Radiation Protection and Research
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• v.20 no.2
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• pp.129-136
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• 1995

In spite of the prescriptions on the reference X-ray fields given by the International Organization of Strandard(ISO) and American National Standard Institute(ANSI), the measurement of X-ray spectrum is not only time consuming but very difficult, paticularly when significant corrections have to be applied to the measured pulse-height distributions of the observed spectra. This paper describes the calculation method of ISO Narrow Series and ANSI X-ray filtered radiations by theoretical model which is modified framer's theory by target attenuation and backscatter correction. The X-ray spectra, average energies and conversion coefficients are calculated and compared with those obtained using the spectra prescribed by ISO and AMSI to assure good agreement.

• Restorative Dentistry and Endodontics
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• v.26 no.4
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• pp.263-272
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• 2001

The aim of this study was to investigate the influence of four different light curing modes on the marginal leakage of Class V composite resin restoration. Eighty extracted human premolars were used. Wedge-shaped class Y cavities were prepared on the buccal surface of the tooth with high-speed diamond bur without bevel. The cavities were positioned half of the cavity above and half beyond the cemento-enamel junction. The depth, height, and width of the cavity were 2 mm, 3 mm and 2 mm respectively. The specimens were divided into 4 groups of 20 teeth each. All the specimen cavities were treated with Prime & Bond$^{R}$ NT dental adhesive system (Dentsply DeTrey GmbH, Germany) according to the manufacturer's instructions and cured for 10 seconds except group VI which were cured for 3 seconds. All the cavities were restored with resin composite Spectrum$^{TM}$ TPH A2 (Dentsply DeTrey GmbH, Germany) in a bulk. Resin composites were light-cured under 4 different modes. A regular intensity group (600 mW/${cm}^2$, group I) was irradiated for 30 s, a low intensity group (300 mW/${cm}^2$, group II) for 60 s and a ultra-high intensity group (1930 mW/${cm}^2$, group IV) for 3 s. A pulse-delay group (group III) was irradiated with 400 mW/${cm}^2$ for 2 s followed by 800 mW/${cm}^2$ for 10 s after 5 minutes delay. The Spectrum$^{TM}$ 800 (Dentsply DeTrey GmbH, Germany) light-curing units were used for groups I, II and III and Apollo 95E (DMD, U.S.A.) was used for group IV. The composite resin specimens were finished and polished immediately after light curing except group III which were finished and polished during delaying time. Specimens were stored in a physiologic saline solution at 37$^{\circ}C$ for 24 hours. After thermocycling (500$\times$, 5-55$^{\circ}C$), all teeth were covered with nail varnish up to 0.5 mm from the margins of the restorations, immersed in 37$^{\circ}C$, 2% methylene blue solution for 24 hours, and rinsed with tap water for 24 hours. After embedding in clear resin, the specimens were sectioned with a water-cooled diamond saw (Isomet$^{TM}$, Buehler Co., Lake Bluff, IL, U.S.A.) along the longitudinal axis of the tooth so as to pass the center of the restorations. The cut surfaces were examined under a stereomicroscope (SZ-PT Olympus, Japan) at ${\times}$25 magnification, and the images were captured with a CCD camera (GP-KR222, Panasonic, Japan) and stored in a computer with Studio Grabber program. Dye penetration depth at the restoration/dentin and the restoration/enamel interfaces was measured as a rate of the entire depth of the restoration using a software (Scion image, Scion Corp., U.S.A.) The data were analysed statistically using One-way ANOVA and Tukey's method. The results were as follows : 1. Pulse-Delay group did not show any significant difference in dye penetration rate from other groups at enamel and dentin margins (p>0.05) 2. At dentin margin, ultra-high intensity group showed significantly higher dye penetration rate than both regular intensity group and low intensity group (p<0.05). 3. At enamel margin, there were no statistically significant difference among four groups (p>0.05). 4. Dentin margin showed significantly higher dye penetration rate than enamel margin in all groups (p<0.05).

• Journal of radiological science and technology
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• v.37 no.4
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• pp.253-259
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• 2014

Large volume of $6{\times}6{\times}12mm^3$ CdZnTe ${\gamma}$-ray detector was fabricated with CdZnTe single crystals grown by Traveling Heater Method (THM) to evaluate the energy resolution of 662 keV in $^{137}Cs$. Hole tailing effect which originated from the large mobility difference in electron and hole degrade energy resolution of radiation detector and its effects become more severe for a large volume detectors. Generally, single carrier collection technique is very useful method to remove/minimize hole tailing effect and thereby improvement in energy resolution. Virtual Frisch-grid technique is also one of single charge collection method through weighting potential engineering and it is very simple and easily applicable one. In this paper, we characterized CZT detector grown by THM and evaluated the effectiveness of virtual Frisch-grid technique for a high energy gamma-ray detector. The proper position and width of virtual Frisch-grid was determined from electric field simulation using ANSYS Maxwell ver. 14.0. Energy resolution of 2.2% was achieved for the 662 keV ${\gamma}$-peak of $^{137}Cs$ with virtual Frisch-grid CdZnTe detector.

• Journal of Radiation Protection and Research
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• v.18 no.1
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• pp.63-70
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• 1993

Double ionization of the K- shell accompanying K- shell electron capture of the 0.035 MeV transition of $^{125}I$ has been studied by counting coincidences between $K_{\alpha}$ hypersatellite X-rays and Ka satellite X-rays emitted when double vacancies are filled. The $^{125}I\;and\;^{125}Te^m$ source materials were used in the measurement. We obtained the coincidence spectrum using two NaI(T1) detectors and a Ge(Li) detector and TAC(Time-to-Amplitude Converter), and then analysed the measured coincidence number $N(K_{\alpha}^{II},\;K_{\alpha}^s)$, the total number $N(K_{\alpha})$ of K X-ray. The probability per K-shell electron capture that a double vacancy is formed, $P_{KK}$ is formed, $P_{KK}$ is found to be $2.15{\times}10^{-4}$.

• Journal of Sensor Science and Technology
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• v.12 no.1
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• pp.1-9
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• 2003

CsI single crystals doped with lithium, potassium or rubidium were grown by using Czochralski method at Ar gas atmosphere. The energy resolutions of CsI(Li:0.2 mole%), CsI(K:0.5 mole%) and CsI(Rb:1.5 mole%) scintillators were 14.5%, 15.9% and 17.0% for $^{137}Cs$(0.662 MeV), respectively. The energy calibration curves of CsI(Li), CsI(K) and CsI(Rb) scintillators were linear for $\gamma$-ray energy. The time resolutions of CsI(Li:0.2 mole%), CsI(K:0.5 mole%) and CsI(Rb:1.5 mole%) scintillators measured by CFT(constant-fraction timing method) were 9.0 ns, 14.7 ns and 9.7 ns, respectively. The fluorescence decay times of CsI(Li:0.2 mole%) scintillator had a fast component and slow one of ${\tau}_1=41.2\;ns$ and ${\tau}_2=483\;ns$, respectively. The fluorescence decay times of CsI(K:0.5 mole%) scintillator were ${\tau}_1=47.2\;ns$ and ${\tau}_2=417\;ns$. And the fluorescence decay times of CsI(Rb:1.5 mole%) scintillator were ${\tau}_1=41.3\;ns$ and ${\tau}_2=553\;ns$. The phosphorescence decay times of CsI(Li:0.2 mole%), CsI(K:0.5 mole%) and CsI(Rb:1.5 mole%) scintillators were 0.51 s, 0.57 s and 0.56 s, respectively.