• New Physics: Sae Mulli
• /
• v.69 no.10
• /
• pp.1107-1114
• /
• 2019

Producing extremely stable high temperature and pressure condition is crucial in order to synthesize novel materials with various functions and to investigate their static and dynamic properties. Already a high pressure in the Mbar range, which is necessary to make novel materials, can be acquired by using a Diamond Anvil Cell (DAC), In this study, a laser-heating system combined with the DAC was designed and installed using two 1064-nm, 100-W fiber lasers on different sides of the DAC to heat the sample and three spectrometers to measure the temperature, pressure, and Raman spectra. A stainless-steel gasket, which is generally used as a sample chamber in high-pressure experiments, was heated to make a thermal radiation source, and the temperature of the heated gasket was obtained by measuring the spectrum of the radiation. By applying this technique, we were able to make various materials and to investigate their physical properties under extreme conditions.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.24 no.12
• /
• pp.969-976
• /
• 2014

Nowadays, it is required for naval ships to estimate 3D underwater radiated noise pattern in all direction at peak frequencies of hull vibration for the reduction of being detected and doing the effective operation. For this purpose, the numerical method has to be developed to calculate 3D underwater radiated noise pattern with experimental data. It is very difficult to obtain the experimental data for the real ship. Alternative to get the experimental results is to use NAH(near-field acoustic holography) in acoustic tank with experimental model. Application of NAH in acoustic tank for the experimental model needs some investigation of reflection wave from the wall of the acoustic tank and unmeasured zone of the experimental model due to the supporting structure for it. In this study, the effect of reflection wave in the acoustic tank and unmeasured area of the experimental model when using the NAH was investigated with experiment and numerical model. From these, it is known for the error due to reflection wave can be reduced when the distance between the measurement plane and source is being shorten. Also, unmeasured area of the experimental model gives rise to some error in the estimation of the far-field acoustic pressure.

• Journal of Advanced Navigation Technology
• /
• v.22 no.2
• /
• pp.123-132
• /
• 2018

In this paper, we design and fabricate a dual liner polarization sinuous antenna with improved cross polarization isolation (XPI). The proposed antenna is composed of four arm radiators for generating dual linear polarization and excited by wideband microstrip balun with Klopfenstein taper structure. Also, two-step cylindrical cavity structure is applied to reduce back radiation. Honeycomb-typed absorbing material is inserted into the cavity to reduce performance degradation by reflected wave. To enhance cross polarization isolation in low frequency band, resistors are adapted between outer arm and the rim of cavity. We confirmed that the fabricated antenna can be applied for polarization measurement due to improved XPI in the low band.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.20 no.7
• /
• pp.625-630
• /
• 2009

In this paper, we introduce the analysis and counter-measure of signal distortion of search radar equipped on the ship. Using ShipEDF program, the search radar's main antenna and ship structures are modeled in the view of electromagnetism. Ray tracing method is used for analysis of the search radar's radiation patterns in free space and ship condition. From analyzed radiation patterns, we can conclude that the search radar's signal distortion is due to radiation pattern distortion. We also analyze the surface current distribution of the mast to propose the counter-measure to reduce electro-magnetic field reflection of mast.

• Journal of Radiation Protection and Research
• /
• v.46 no.3
• /
• pp.112-119
• /
• 2021

Background: This work aims to develop a new imaging system based on a pulse shape discrimination-capable Cs₂LiYCl₆:Ce (CLYC) scintillation detector combined with the rotational modulation collimator (RMC) technique for dual-particle imaging. Materials and Methods: In this study, a CLYC-based RMC system was designed based on Monte Carlo simulations, and a prototype was fabricated. Therein, a rotation control system was developed to rotate the RMC unit precisely, and a graphical user interface-based software was also developed to operate the data acquisition with RMC rotation. The RMC system was developed to allow combining various types of collimator masks and detectors interchangeably, making the imaging system more versatile for various applications and conditions. Results and Discussion: Operational performance of the fabricated system was studied by checking the accuracy and precision of the collimator rotation and obtaining modulation patterns from a gamma-ray source repeatedly. Conclusion: The prototype RMC system showed reliability in its mechanical properties and reproducibility in the acquisition of modulation patterns, and it will be further investigated for its dual-particle imaging capability with various complex radioactive source conditions.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.18 no.5
• /
• pp.343-354
• /
• 2017

This study was designed to identify the knowledge, perception, self-efficacy, and performance on radiation protection among perioperative workers in terms of radiation protection. The factors affecting the performance of radiation protection were identified, and provide basic data for the development of an effective radiation protection education program. The sample was comprised of 166 perioperative workers who agreed to participate in this descriptive study. Data analysis was performed using the t-test, analysis of variance, Pearson's correlation, and multiple regression analyses on the SPSS 23.0 Program. The average time of radiation exposure was 3-4hoursThe radiation protection education experience was 11.4%. The average score of radiation protection knowledge was $8.61{\pm}2.51$; the perception was $4.59{\pm}0.64$; and the performance was $2.99{\pm}0.90$ There was a significant difference in the degree of radiation defense knowledge and performance among the general characteristics (p <001). Knowledge of radiation protection was correlated with the perception. The performance of radiation protection was correlated with the knowledge. The knowledge and perception of radiation protection behaviors should be increased to improve radiation protection performance. Therefore, it is important to promote the performance of radiation protection behaviors by improving the perioperative workers' knowledge of radiation protection through reinforcing radiation-related education.

• Toxicological Research
• /
• v.32 no.2
• /
• pp.123-132
• /
• 2016

The impact of mobile phone (MP) radiation on the brain is of specific interest to the scientific community and warrants investigations, as MP is held close to the head. Studies on humans and rodents revealed hazards MP radiation associated such as brain tumors, impairment in cognition, hearing etc. Melatonin (MT) is an important modulator of CNS functioning and is a neural antioxidant hormone. Zebrafish has emerged as a popular model organism for CNS studies. Herein, we evaluated the impact of GSM900MP (GSM900MP) radiation exposure daily for 1 hr for 14 days with the SAR of 1.34W/Kg on neurobehavioral and oxidative stress parameters in zebrafish. Our study revealed that, GSM900MP radiation exposure, significantly decreased time spent near social stimulus zone and increased total distance travelled, in social interaction test. In the novel tank dive test, the GSM900MP radiation exposure elicited anxiety as revealed by significantly increased time spent in bottom half; freezing bouts and duration and decreased distance travelled, average velocity, and number of entries to upper half of the tank. Exposed zebrafish spent less time in the novel arm of the Y-Maze, corroborating significant impairment in learning as compared to the control group. Exposure decreased superoxide dismutase (SOD), catalase (CAT) activities whereas, increased levels of reduced glutathione (GSH) and lipid peroxidation (LPO) was encountered showing compromised antioxidant defense. Treatment with MT significantly reversed the above neurobehavioral and oxidative derangements induced by GSM900MP radiation exposure. This study traced GSM900MP radiation exposure induced neurobehavioral aberrations and alterations in brain oxidative status. Furthermore, MT proved to be a promising therapeutic candidate in ameliorating such outcomes in zebrafish.

• Journal of radiological science and technology
• /
• v.40 no.4
• /
• pp.557-565
• /
• 2017

This study was conducted to investigate the radiation protection, awareness, and attitude of radiological technologists in the mammography room due to the low energy use of breast imaging. Data collection was performed by 222 independent radiological technologists in the breast and breast clinic of six hospitals except Jeju Island. The independent sample t-test and oneway variance analysis were performed. As a result, it was found that the lower the number of men(p<0.05), the age of 30s(p<0.05), the marriage(p<0.05), the work experience of more than 10 years(p<0.05), the working hours of 8 hours(p<0.01), the less the impact of radiation(p<0.01), the more important it was to radiation defense. appear. This is thought to be influenced by the work specificity and work environment of the mammography room, and it will be used as a basic data to raise awareness and act on the exposure through analysis with other factors.

• Journal of the Korean Society of Radiology
• /
• v.16 no.4
• /
• pp.463-470
• /
• 2022

The purpose of this study was to investigate the perception of Air Force human resources (Civilian defense manpower, Officer, Noncommissioned officer, Solder) for the radiation perception. The subjects were 259 men and women who visited at the Aerospace Medical Center. As for the method, a survey study was conducted using a questionnaire with a total of 14 questions about radiation perception (risk, benefit, management). For statistical analysis, an independent sample T-test and one-way analysis of variance (ANOVA) were used to compare the average of confirm a significant difference among groups. The correlations between variables were tested with Pearson and Spearman correlation coefficients. As a result, in the air force human resources, perception of radiation risk of females had a significantly higher awareness than male. Radiation benefits had a significantly higher awareness among married people, military officers, officers, and non-commissioned officers. Radiation control was significantly higher in men, married men, and those with more than 16 years of military experience.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.17 no.1
• /
• pp.57-63
• /
• 2014

In this paper, we have proposed a wide band antenna for manpack SDR(Software Defined Radio). The proposed antenna consists of feeding post, flexible gooseneck and two radiating elements composed of a upper and lower radiators. The upper radiator has a longer electrical length than the lower radiator in order to operate in the lower frequency. Also, the resonant frequency and impedance characteristics of the antenna can be adjusted independently for two radiators. Therefore, the proposed antenna can be achieved wide impedance bandwidth by the combination of two independent resonance modes. To analyze the characteristics of the antenna in the design process is employed the equivalent circuit theory and EM(Electro-Magnetic) simulation. The measurement results show that the proposed antenna have the sufficient wide bandwidth, above -3.4dBi of the gain and fairly good radiation pattern over the wide bandwidth.