• Nuclear Engineering and Technology
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• 제54권1호
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• pp.301-309
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• 2022

This work aims to establish some X-ray qualities recommended by the International Standard Organization (ISO) using the half-value layer (HVL) and H_p(10) dosimetry approaches. The HVL values of the following qualities N-60, N-80, N-100, N-150 and N-250 were determined using various attenuation layers. The obtained results were compared to those of reference X-ray beam qualities and a good agreement was found (difference less than 5% for all qualities). The GAMOS (Geant4-based Architecture for Medicine-Oriented Simulations) radiation transport Monte Carlo toolkit was employed to simulate the production of X-ray spectra. The characteristics HVLs, mean energy and the spectral resolution of simulated spectra have been calculated and turned out to be conform to the ISO reference ones (difference less than the limit allowed by ISO). Furthermore, the conversion coefficients from air kerma to personal dose equivalent for simulated and measured spectra were fairly similar (the maximum difference less than 4.2%).

• 대한방사선기술학회지:방사선기술과학
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• 제20권2호
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• pp.44-48
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• 1997

For the efficient management of the diagnostic x-ray equipment, a nation-wide inspection of hospitals was performed by an inspection institute in Taejon in the first half of 1997. Among those hospitals inspected, 28 equipments(machines) which were over 500 mA were randomly selected according to their characteristics : 7 condenser type x-ray equipments, 7 three control phase of full wave rectification of type remote control x-ray equipments, 7 single phase of full wave rectification type for general radiography equipments, and 7 single phase of full wave rectification type of R/F equipments. We obtained the following results by conducting the experiment based on the efficiency of the equipments mentioned above. 1) When the equipments are analyzed, 2 out of 7 single phase of full wave rectification type of general radiography equipments(28.6%), 3 out of 7 single phase of full wave rectification type of R/F equipments(42.9%), 5 out of 7 three phase of full wave rectification type remote of control x-ray equipments(71.4%), and 4 out of 7 condenser type of x-ray equipments(57.1%) showed suitability. It proves the superiority of the three phase of full wave rectification type of remote control x-ray equipments. 2) From the overall analysis, only about 50% of the equipments(suitability of 14 out of 28) maintain the efficient management. Therefore, maintenance management of equipments is more necessary. If the efficiency of the x-ray equipment is uniformly maintained and managed to prevent the breakdown(trouble) beforehand especially through the continuous inspection of tube voltage, tube current, exposure time, and collimator, the financial loss and exposure dose to the patient, as well as the workers engaged in radiation, can be reduced for better medical service.

• International Journal of Safety
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• 제8권1호
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• pp.14-17
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• 2009

The $Co^{60}$ $\gamma$-ray irradiation effects on the electrical and thermal characteristics of low density polyethylene crosslinked by Dicumyl peroxide (DCP) were investigated. We experimented on electrical properties as following; electrical tree inception and growing type for applying AC step voltage, AC breakdown strength, volume resistivity with increasing dosage. Also, chemical analyses were performed TGA, gel fraction. These electrical properties changed depending upon its crosslinking degree and byproducts from crosslinking reactions. Crosslinking reactions were considered causing by $\gamma$-ray irradiation and DCP had contained in low density polyethylene.

• 전기의세계
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• 제23권3호
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• pp.67-69
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• 1974

The electric characteristics of all the instruments and materials used in atomic field is changed due to radiation damages by the effects of radio activities. In this study, when the condenser is radiated by Gamma-ray, variations in its electric properties have been investigated. The following results are obtained. (1) The capacitance in O.F paper condenser is exponentially increased as the quantity of irradiation by Gamma-ray is increased, but polyethylene, ceramic, chemical, neostyrene, mylar condenser are decreased. and in case of more than 10$^{7}$ of irradiation it has saturated state, (2) The breakdown voltage and the .delta. in condensers except the O.F paper condenser are exponentially increased as the quantity of irradiation by Gamma-ray is increased but in case of more than 10$^{7}$ .gamma. of irradiation it has decreased.

• Advances in materials Research
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• 제1권3호
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• pp.233-243
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• 2012

Thermal reactive diffusion coating of vanadium carbide on DIN 2714 steel substrate was performed in a molten borax bath at $950-1050^{\circ}C$. The coating formed on the surface of the substrate had uniform thickness ($1-12{\mu}m$) all over the surface and the coating layer was hard (2430-2700 HV), dense, smooth and compact. The influence of the kinetics parameters, temperature and time, has been investigated. Vanadium carbide coating was characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDX) and X-ray diffraction analysis (XRD). The corrosion resistance of the coating was evaluated by potentiodynamic polarization in 3.5% NaCl solution. The results obtained showed that decrease of coating microhardness following increasing time and temperature is owing to the coarsening of carbides and coating grain size.

• 대한수의학회지
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• 제16권1호
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• pp.7-10
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• 1976

An agglutinability between naturally infected positive chicken serum of pullorum disease and hyperimmumized rabbit antiserum was compared. And the following results were obtained and summarized. 1. On the agglutinability, Salmonella pullorum antigen which irradiated gamma-ray was more excellent than another both formalized and heated antigen. 2. Time of judgemented as positive titer in the tube agglutination test to the naturally infected positive chicken serum was it most suitable for 12 hours at $37^{\circ}C$. 3. Agglutination titer of positive immune chicken serum against gamma-ray irradiate Salmonella pullorum were as 320~640x.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 1996년도 International Conference on Agricultural Machinery Engineering Proceedings
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• pp.171-190
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• 1996

Quality evaluation of agricultural products has been a subject of interest to many researches for many years. As a results, several nondestructive techniques for quality evaluation of agricultural products have been developed. These methods are based on the detection of various physical properties that correlate well with certain quality factors of the products. This paper presents an overview of various quality evaluation techniques that are based on one of the following properties : density, firmness , vibration characteristic , X-ray and gamma ray transmission, optical reflectance and transmission , electrical properties, aromatic volatile emission, and nuclear magnetic resonance (NMR). The sophistication of nondestructive methods has evolved rapidly with modern technologies. The use of various modern image acquisition techniques, such as solid state TV camera, line-scan camera, X-ray scanning , ultrasonic scanning and NMR imaging, in conjunction with image-processing te hniques has provided new opportunities for researchers to develop many new and improved techniques for nondestructive quality evaluation of agricultural products.

• 한국정보통신학회논문지
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• 제5권4호
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• pp.645-652
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• 2001

본 논문은 근거리 차량간 통신(IVC)에서 첨단차량도로시스템(AVHS)의 플래툰 주행에 적합한 One-Ray Rician 채널 모델을 적용하여 간섭신호에 강한 장점을 지닌 60GHz 밑리미터파에서 패킷 오율 특성을 분석하였다. 차후에 사용자의 욕구 증대에 따른 멀티미디어 서비스를 만족시키기 위해서 Convolution 부호화 기법과 MRC 다이버시티 수신 기법을 동시에 적용하였으며 그에 따른 DS-CDMA/QPSK System의 패킷 오율 특성을 분석하였다.

• Current Applied Physics
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• 제18권11호
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• pp.1230-1234
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• 2018

We report a new method of measuring the non-radiative recombination rate in bulk Silicon. Synchrotron timeresolved x-ray scattering (TRXS) combines femtometer spatial sensitivity with nanosecond time resolution to record the temporal evolution of a crystal lattice following intense ultrafast laser excitation. Modeling this data requires an Auger recombination time that is considerably slower than previous measurements, which were made at lower laser intensities while probing only a relatively shallow surface depth. We attribute this difference to an enhanced Coulomb interaction that has been predicted to occur in bulk materials with high densities of photoexcited charge carriers.

• 한국약용작물학회지
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• 제25권5호
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• pp.290-295
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• 2017

Background: Senna tora is a flowering plant in the legume family Fabaceae. Its seeds are roasted and consumed as tea in Asia, to reduce inflammation in the liver and improve eyesight. Thus, it has been considered as an important medicinal crops in Asia. However, breeding trials to improve its genetic properties are rare. Mutation breeding by gamma ray is known to be an effective and highly successful approach for the generation of agronomically useful cultivars. Here we analyzed the effects of several dosages of gamma ray on the biological conditions of Senna tora seeds. Methods and Results: The germination rate and growth patterns of Senna tora were examined following irradiation with gamma ray at 100, 200, 300 and 400 Gy. The total phenolic compound contents and antioxidant activities of Senna tora were analyzed. Germination increased at 100 and 200 Gy in the M1 and M2 generations compared with that of the control (M0). The total phenolic compound contents and antioxidant activity of the seeds significantly decreased as the radiation dosage increased above 100 Gy in the M1 generation. Conclusions: Senna tora, irradiated with gamma ray at dosages 100, 200, 300, and 400 Gy, showed maximum germination rate at 200 Gy in the M2 generation. Plant height and leaf size gradually decreased with increasing gamma ray intensity in the M2 generation. The total phenolic compound contents decreased significantly at 400 Gy, and the related antioxidant activity was also decreased as the radiation dosage increased.