• Korean Chemical Engineering Research
• /
• v.54 no.2
• /
• pp.152-156
• /
• 2016

Experimental research on the preparation of photocatalyst for the decomposition of brilliant blue FCF ($C_{37}H_{31}O_9N_2S_3Na_2$) was performed. $TiO_2$ and ZnO powders were prepared from titanium (IV) sulfate and zinc acetate at low reaction temperature and atmospheric pressure by hydrothermal precipitation method without calcination. In addition, $TiO_2$ was prepared with cationic surfactant CTAB (Hexadecyltrimethyl ammonium bromide) at the same conditions. The physical properties of prepared $TiO_2$ and ZnO, such as crystallinity, average particle size and absorbance, were investigated by XRD, Zeta-potential meter and DRS. And, the photocatalytic degradation of brilliant blue FCF has been studied in the batch reactor under UV radiation. For the photocatalysts prepared without CTAB, $TiO_2$ has smaller particle size and larger absorbance and photocatalytic reaction rate than ZnO. And $TiO_2$, prepared with CTAB whose concentration is 1/10 of that of precursor, shows 15% higher than that prepared without CTAB in final photocatalytic degradation ratio of brilliant blue FCF.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.16 no.4 s.95
• /
• pp.366-372
• /
• 2005

This paper presents analysis of a slot array antenna having a low side lobe level and high front-to-back ratio for a repeater system of a satellite DMB(Digital Multimedia Broadcasting) service. Antennas for this repeater system require a high gain and enough isolation to reduce interferences between signals in system. Therefore, it is necessary to suppress a side lobe level and to increase front-to-back ratio. Unlike a structure 134 by lossy microstrip lines, in this work a single cavity-backed slot antenna array using a single waveguide feed is proposed to obtain the reliability for high power handling and high radiation efficiency. The side lobe level and front-to-back ratio are enhanced with tapered array technique and an optimized vertical reflector. The measured side lobe levels in H- and E-plane are under $-33.24\;\cal{dB}$ and $-35.78\;\cal{dB}$, respectively. The front-to-back ratio over $37.84\;\cal{dB}$, and the peak gain of over $17\;\cal{dBi}$ are measured.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.17 no.11 s.114
• /
• pp.1021-1029
• /
• 2006

In this paper, we designed and implemented a dual wideband dipole type antenna for the reception of S-DMB (Satellite Digital Multimedia Broadcasting) and 2.4/5 GHz WLAN(Wireless Local Area Network) signals. The proposed antenna based on conventional monopole type dual band antenna was implemented as planar wideband dipole type antenna with the volume of $8{\times}33.8{\times}1.68mm^3$. The proposed antenna is printed type on FR4 substrate of 1.6 mm thick and composed of a dipole type antenna for low frequency band and two symmetric structured resonance elements for high frequency band. We confirmed antenna area with dense surface current for each frequency band with simulation. By varying the length of the antenna area with dense surface current, we could vary resonance frequency of each frequency band separately. Impedance bandwidths$(VSWR{\leq}2)$ are 362 MHz(14.23 %) for 2 GHz band and 1188 MHz(22.13, %) for 5 GHz band which show wideband characteristic. Measured maximum gains were 4.33 dBi for 2 GHz band and 5.48 dBi for 5 GHz band which showed improved performance. And the implemented antenna has a good omni-directional radiation pattern characteristic.

• Journal of Bio-Environment Control
• /
• v.21 no.4
• /
• pp.348-353
• /
• 2012

This study was conducted to figure out the possibility of non-drainage in muskmelon (Cucumis melo L.) hydroponics culture. Plants were grown under 3 different levels of drainage, standard (20~40%, SD), minimum (5~10%, MD), and non-drainage (ND). Throughout cultivation periods, constant water content and electrolyte conductivity changes in root zone were observed in SD in the range of 60~70% and $1.5{\sim}2.5dS{\cdot}m^{-1}$, respectively. ND treatment caused the fluctuation in water content and electrolyte conductivity of root zone and its change ranges were 30~50% in water content and $2{\sim}6dS{\cdot}m^{-1}$ in electrolyte conductivity, but ND treatment did not decrease fruit quality. Even if fruit fresh weight was slightly lower in ND with 1,863 g, than in SD with 1,990 g, the fruit weight in ND meets standard market size, 1,800~2,000 g. Higher soluble solids content was observed in fruit in ND than in SD and MD. Total amount of drainage per plant was 27,718, 15,769 and 2,346 mL in SD, MD and ND, respectively. SD showed $83.2m^3$ drainage, 34.5% drainage of irrigation amount whereas required total irrigation amount in ND was very low with $7m^3$.

• Korean Journal of Environmental Agriculture
• /
• v.22 no.4
• /
• pp.284-289
• /
• 2003

Titanium mesoporous materials have received increasing attention as a new photocatalyst in the field for photocatalytic degradation of organic compounds. The photocatalytic degradation of chlorothalonil by mesoporous titanium oxo-phoswhate (Ti-MCM) was investigated in aqueous suspension for comparison with $TiO_2$, (Degussa, P25) using as an effective photocatalyst of organic pollutants. Mesoporous form of titanium Phosphate has been prepared by reaction of sulfuric acid and titanium isopropoxide in the presence or n-hexadecyltrimethylammonium bromide. The XRD patterns of Ti-MCM are hexagonal phases with d-spacings of 4.1 nm. Its adsorption isotherm for chlorothalonil reached at reaction equilibrium within 60 min under dark condition with 28% degradation efficiency. The degradation ratio of chlorothalonil after 9 hours under the UV radiation condition (254 nm) exhibited 100% by Ti-MCM and 88% by $TiO_2$. However, these degradation kinetics in static state showed a slow tendency compared to that of stirred state because of a low contact between titanium matrices and chlorothalonil. Also, degradation efficiency of chlorothalonil was increased with decreasing initial concentration and with increasing pH of solution. As results of this study, it was clear that mesoporous titanium oxo-phosphate with high surface area and crystallinity could be used to photo- catalytic degradation of various organic pollutants.

• The Journal of Engineering Geology
• /
• v.16 no.4 s.50
• /
• pp.403-409
• /
• 2006

This study was performed to assess the clay impact on alga growth which was a primary producer, in view of food chain in ecosystem. As clay minerals caused turbidity, a low sedimentation, high adsorption capacity with organic matter, adsorption - desorption effect with ionic chemicals, clay minerals were supposed to have a significant effect on the aquatic system. In study we tried to turn out NOAEL (No-observed-adverse-effect-level) of clay materials on the algae growth inhibition using such as kaolinite, sericite and montmorillonite. This study was indicated. (1) In both of kaolinite and sericite, the $72hr-EC_{50}$ of them shows 2,752 mg/L and 2,775 mg/L, respectively. (2) On the other hand, in the case of montmorillonite, the $72hr-EC_{50}$ is not shown a significant difference to that of control samples. (3) It can be explained that is also a very important parameter in an alga growth. Because an alga growth was increased when the permeability of W visible radiation was increased in all clay cases. (4) It is demonstrated alga growth was affected by the characteristics of clay materials. Hence we can assess the $\ulcorner$water environmental risk assessment caused clay materials$\lrcorner$ using the alga growth inhibition level indirectly.

• Journal of radiological science and technology
• /
• v.20 no.2
• /
• pp.49-55
• /
• 1997

This study was carried out to investigate radiographical and operating conditions of X-ray units and exposure doses to patients during chest radiography, so that the results could provide basic data used for reducing the exposure dose and for providing the diagnostic information with better quality. The conditions and exposure doses of 100 X-ray units mainly used for chest radiography were examined and also 100 radiological technologists mainly handling those apparatus at 76 medical facilities in Pusan were surveyed using a questionnaire from October 1 to December 31 in 1995. The following results were obtained from the study : 1. It was found that most units were capable of taking a high tube voltage radiography by showing 67% of the units equipped with the maximum tube voltage of 150 kV, 94% with more than 500 mA for the rating capacity and 85% with the full wave type of a signal phase. 2. For actual chest radiographical conditions, however, 80% of the units were operated at $60{\sim}100\;kVp$ and only 14% at 100 kVp and over for the high tube voltage. 3. The average exposure time was less than 0.1 second, and eighty four percent of the units adapted the X-ray tube currents ranging from 200 to 300 mA, 80% the focus-film distances between 180 and 210 cm, and 63% the focus sizes of more than 2.0 mm. 4. Most units(98%) employed additional filters made of aluminum, 75% the thickness of filters less than 2.0 mm, and only 2 units the compound filters. 5. Ortho chromatic system was only adopted in 13% of screen film system for the units, and 73% used the grid ratio at 8 : 1 for the low tube voltage during chest radiography. 6. The average exposure dose of all X-ray units during chest radiography was $371\;{\mu}Sv$ with a difference of about 16 times between the minimum to the maximum, and $386\;{\mu}Sv$ both at hospitals and at health centers, followed by $380\;{\mu}Sv$ at general hospitals and $263\;{\mu}Sv$ at university hospitals without showing any statistically significant differences. In conclusion, since patients during chest radiography at medical facilities in Pusan exposed to high levels of radiation, it is recommended that appropriate added filters and grids necessary for the high tube voltage radiography and high-speed screen systems should be adopted and used as soon as possible in order to reduce exposure dose to the patients.

• Journal of radiological science and technology
• /
• v.40 no.4
• /
• pp.595-603
• /
• 2017

The study is to produced a brain phantom simulating corpus striatum, which can evaluate the progression of parkinson's disease, to investigate possibility of reducing the brain exposure dose to CT while maintaining optimal image quality during PET-CT examinations. CT scans were performed by varying tube voltage (100, 120 kVp) and tube current (80, 140, 200 mAs) with $^{18}F$ FP-CIT injected into the phantom's hot sphere and background (radioactivity ratio 3:1)(reference condition; 120 kVp, 140 mAs). Estimated effective dose was calculated by using conversion factor according to each condition, and image quality was evaluated by setting SNR and CRChot image evaluation factors. Experimental results showed that the predicted effective dose below the CT imaging reference condition was reduced by at least 10% and by up to 60%, and the predicted effective dose beyond the reference condition was increased by 40%. In addition, there was no significant difference between SNR and CRChot of PET images, and it was confirmed that brain dose decreased with decrease of tube voltage and tube current. At the same time, there was no significant change in the quality of the image in terms of SNR and CRChot despite the change in scan conditions. This fact suggests that the quality of the images acquired under the existing dose conditions can be obtained even at low dose conditions and it is expected that it will be possible to use the brain PET-CT scan as a basic data for the research on reduction of dose and improvement of image quality.

• Journal of the Korean Society of Radiology
• /
• v.1 no.3
• /
• pp.35-40
• /
• 2007

The purpose of this study was to investigate in S city of Chung-Nam using direction radiation Cervical spine among patient enforcing AP view, lateral view, total 113 subjects(40-year-old low)by target examine and got following as: 1) Distribution of age 14~40 years old 57 men (50.4%), woman 56subjects(49.6%)be, and age group 30~40year old 80subjects(70.8 %), 20~29year old 27subjects(23.9%). 2) It appeared most by 81subjects(71.7%) that can not know cause though traffic accident, misstep, cause ignorantness were investigated to revealed by the chronic 87subjects(77%) appeared by thing which statistical significance is with occurrence cause. 3) 20 Among whole 113subjects 20~29years old 27 subjects(23.9%), 30~40years old 80 subjects(70.8%) manifestationacute form of a disease, the chronic all high distributionsee. 4) This investigator left shoulder region pain among 39 subjects whole 113 subjects (left to direction that could know that is each main pain in 34.5 %), cervical vertebral portion upside 31 subjects(27.4%), both shoulder region pain 20 subjects(17.7%), and becomes left side scoliosis 62 subjects(54.9%)by the most frequencies appear. 5) Appeared antespondylolisthesis by all curve 48 subjects(42.5 %) in curve direction and at Systolic blood pressure from 160mmHg to all 19 subjects (before total 69 subjects (61.0 %) at 16.8 %), Diastolic blood pressures curve 31 subjects(27.4 %) by 100 mmHg appear.

• Fire Science and Engineering
• /
• v.26 no.4
• /
• pp.55-62
• /
• 2012

The suppression mechanisms of carbon dioxide ($CO_2$) as a representative fire suppression agent were revisited using a counterflow diffusion flame which could be applied the concept of a local application system. To end this, the low strain rate $CH_4$/air counterflow diffusions with $CO_2$ addition in either fuel or oxidizer stream were examined numerically using detailed-kinetic chemistry. Radiative heat loss due to radiating gas species including $CO_2$ added was considered by the optically thin model (OTM). As a result, the critical $CO_2$ volume fractions in the oxidizer stream required to extinguish the flame were in good agreement with the experimental data reported in the literature, while somewhat under-prediction was observed with $CO_2$ added in the fuel stream. The surrogate agents were adopted to estimate the quantitative contribution with changing in global strain rate ($a_g$) on the flame extinguishment among pure dilution effect, thermal effects including radiation heat loss and chemical effect due to the $CO_2$ fire suppression agent.