• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.5
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• pp.39-49
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• 2013

The effect of the finite substrate size on the radiation characteristics of H-plane linear microstrip array antennas is investigated. The radiation characteristics versus scan angle are systematically analyzed for 5-element H-plane linear array antennas with various substrate sizes and element spacings for the substrates with different dielectric constants. The distance between the antenna center and the substrate edge on the E-plane for the enhancement of the radiation characteristics of the array antenna is presented.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.5
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• pp.150-156
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• 2017

This study tests the characteristics of heat radiation by applying the pin-height variables to 30-W LED floodlights. The angle of the heat sink enables us to identify the characteristics of the heat radiation based on the temperature distribution. The results of the study are as follows. When the heat sinks are set towards the ground, the heat transfer decreases in speed only to expands the temperature distribution, which adversely affects the characteristics of heat radiation and expands the temperature distribution of PCB with the LED chip. We verify that the characteristics of heat radiation are adversely affected when the height of the cooling pin decreases and the heat radiation area decreases, which impedes the heat transfer and increases the temperature distribution on the heat sink.

• Journal of Applied Biological Chemistry
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• v.51 no.1
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• pp.28-35
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• 2008

The physico-chemical properties of kapok fibers were altered via the combination processes of chlorite-periodate oxidation, in order to assess their efficacy as a heavy metal adsorbent. The chemically-oxidized kapok fibers were found to harbor a certain amount of polysaccharides, together with lowered lignin content. This alteration in lignin characteristics was clearly confirmed via FTIR and NBO yield. Moreover, chemically oxidized kapok fibers retained their hollow tube shape, although some changes were noted. The chemically oxidized kapok fibers evidenced elevated ability to adsorb heavy metal ions with the best fit for the Langmuir adsorption isotherm model. Three cycles of adsorption-desorption were conducted with in-between regeneration steps. Our experimental results indicated that chemically oxidized kapok fibers possessed excellent adsorption characteristics, and the modified kapok fibers could be completely regenerated with almost equimolar diluted sodium hydroxide. Pb, Cu, Cd and Zn ions evidenced adsorption rates of 93.55%, 91.83%, 89.75%, and 92.85% on the chemically oxidized kapok fibers. The regeneration efficiency showed 73.58% of Pb, 71.55% of Cu, 66.87% of Cd, and 75.00% of Zn for 3rd cycle with 0.0125N NaOH.

• Journal of the Korean Solar Energy Society
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• v.31 no.3
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• pp.133-144
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• 2011

The objective of this study is to analyze the characteristic of radiation environment in the urban and rural through the field observation in the summer. The radiation balance was compared through the measurement of the shortwave radiation and long-wave radiation in the urban, sub-urban, and rural. The following conclusion could be obtained from this research. (1)In the results of observation including the rain-day, it was found that the short wave radiance in the urban is lower about 10% than the rural. (2)The upper part of atmosphere layers in the urban are aabsorb much short wave radiation energies compared with the rural relatively. It can increase the temperature of the upper part of atmosphere layers and the emittance of long wave radiation. (3)The ratio of the downward short wave radiation to the downward long wave radiation was 1.24 for the urban, 1.28 for sub-urban and 1.35 for rural. It can be estimated that the atmosphere condition of the rural is better than that of other areas. (4)The net radiation of the rural was lower that of the urban. It was found that the energy in and outflow of the rural is easier than that of the urban. (5)The temperature variation for the long-wave radiation change of the rural showed more sensitive than that of the urban. It was came from the radiation characteristics of the surrounding environment and can be used as the important index to evaluate the thermal environment characteristic of urban.

• Journal of radiological science and technology
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• v.42 no.4
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• pp.271-277
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• 2019

CareDose 4D which is the Siemens's Automatic Exposure Control (AEC) can adjust the level of radiation dose distribution which is based on organ characteristic unlike other manufacturer's AEC. Currently, a wide scan range containing different organs is sometimes examined at once (defined as one scan). The purpose of this study was to figure out which organ characteristic option is suitable when one scan method is utilized. Two types of anthropomorphic phantoms were scanned in the same range which were from frontal bone to carina level according to three different organ characteristics such as Thorax, Abdomen, and Neck. All scans and image reconstruction parameters were equally applied and radiation dose were compared. Radiation dose with Thorax organ characteristic was lower than that with Neck. Also, that with Abdomen oran characteristic was lower than Thorax. There were significant differences in radiation dose according to different organ characteristics at the same parameters (P<0.05). Usage of Neck organ characteristic had a result of the highest radiation dose to all phantom. On the other hand, utilization of Abdomen organ characteristic showed the lowest radiation dose. As a result, it is desirable to set appropriate organ characteristic according to examined body part when you checkup patients. Also, when you implement one scan method, selection of Abdomen-based organ characteristic has reduced more radiation dose compared with two different organ characteristic.

• Journal of Radiation Industry
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• v.17 no.1
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• pp.75-82
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• 2023

This research was carried out to evaluate on microbiological (total aerobic bacteria, yeast and mold) and physicochemical (color, firmness, water content, water activity and weight loss) characteristics of 10MeV electron-beam irradiated(0, 0.5, 1, 2 and 3kGy) enoki mushroom during storage (0, 7, 14, 21 and 28 day) at 4℃ with 80% relative humidity. As compared to control, all irradiated samples exhibited dose-dependent decreases of microbial counts up to 28 days, and electron beam irradiation above 2 kGy kept below the microbiological safety threshold. Yellowness (b^*) which is associated with discoloration of mushrooms was significantly reduced by electron beam irradiation (2 kGy). Firmness, water content, water activity and weight loss showed no significant difference in all group up to 28 days. Thus, the appropriate electron-beam irradiation dose was confirmed as 2 kGy to inhibit the microbial growth and browning reaction in enoki mushroom.

• Journal of Radiation Protection and Research
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• v.30 no.1
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• pp.27-30
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• 2005

New possibilities are discussed for cholesteric liquid crystals (CLC) as sensor materials for detection of ionizing radiation, biologically active UV radiation, and the presence of hazardous vapors in atmosphere. A distinguishing property of CLC-based detectors is their 'bioequivalence', i.e., mechanisms of their response to external factors essentially imitate the corresponding mechanisms of biological tissues. Such detectors can ensure sufficiently high sensitivity to make feasible their use as alarm indicators or in biophysical studies. Specific examples ate given of sensor compositions and their response characteristics.

• Nuclear Engineering and Technology
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• v.50 no.5
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• pp.801-805
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• 2018

In this study, an underwater radiation detector was built using a GAGG(Ce) scintillator and silicon photomultiplier to establish an underwater radiation exposure monitoring system. The GAGG(Ce) scintillator is suitable for small radiation detectors as it strongly absorbs gamma rays and has a high light emission rate with no deliquescent properties. Additionally, the silicon photomultiplier is a light sensor with characteristics such as small size and low applied voltage. Further, a program and mobile app were developed to monitor the radiation coefficient values generated from the detector. According to the results of the evaluation of the characteristics of the underwater radiation monitoring system, when tested for its responsiveness to radiation intensity and reactivity, the system exhibited a coefficient of determination of at least 0.99 with respect to the radiation source distance. Additionally, when tested for its underwater environmental temperature dependence, the monitoring system exhibited an increase in the count rate up to a certain temperature because of the increasing dark current and a decrease in the count rate because of decreasing overvoltage. Extended studies based on the results of this study are expected to greatly contribute to immediate and continuing evaluation of the degree of radioactive contamination in underwater environments.

• Nuclear Engineering and Technology
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• v.55 no.1
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• pp.270-277
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• 2023

Exposure to ionizing radiation induces free radicals in human nails. These free radicals generate a radiation-induced signal (RIS) in electron paramagnetic resonance (EPR) spectroscopy. Compared with the RIS of tooth enamel samples, that in human nails is more affected by moisture and heat, but has the advantages of being sensitive to radiation and easy to collect. The fingernail as a biological sample is applicable in retrospective dosimetry in cases of localized hand exposure accidents. In this study, the dosimetric characteristics of fingernails were analyzed in fingernail clippings collected from Korean donors. The dose response, fading of radiation-induced and mechanically induced signals, treatment method for evaluation of background signal, minimum detectable dose, and minimum detectable mass were investigated to propose a fingernail-EPR dosimetry protocol. In addition, to validate the practicality of the protocol, blind and field experiments were performed in the laboratory and a non-destructive testing facility. The relative biases in the dose assessment result of the blind and field experiments were 8.43% and 21.68% on average between the reference and reconstructed doses. The results of this study suggest that fingernail-EPR dosimetry can be a useful method for the application of retrospective dosimetry in cases of radiological accidents.

• Journal of Electrical Engineering and Technology
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• v.10 no.4
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• pp.1738-1745
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• 2015

Radiation characteristics of a probe-fed rectangular microstrip patch antenna printed on a finite grounded high permittivity substrate are investigated systematically for various square grounded dielectric substrate sizes with several thicknesses and dielectric constants by experiment and full wave simulation. The effect of the substrate size on the radiation characteristics of a rectangular patch antenna is mainly determined by the effective dielectric constant of surface waves on a grounded dielectric substrate. As the effective dielectric constant of surface waves increases, the substrate sizes for the maximum broadside gain and the required onset for a large magnitude of squint angle decrease, while the variations of the broadside gain, the front-to-back ratio, and the magnitude of squint angle versus the substrate size increase due to the increase of the power of the surface wave.