• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.6 no.2
• /
• pp.220-228
• /
• 1996

CdTe single crystals were grown by vertical Bridgman method using double furnace with two siliconit heating elements. When the peak temperature of the upper furnace was fixed at $1150^{\circ}C$ and that of the lower furnace was $800^{\circ}C$, the temperature gradient was about $22.5^{\circ}C$/cm. The lattice constant $a_0$ was $6.482\AA$ from the X-ray diffraction and the band gap energy obtained from the optical absorption experiment at room temperature was 1.478 eV. PL spectrum showed that the bound exciton emission peak was resolved into ($A^0,X$) (1.5902, 1.5887 eV), ($h\;D^0$) (1.5918 eV) and ($D^0,X$ (1.5928, 1.5932 eV), and we have also calculated binding energy and ionization energy of the neutral donor and acceptor.

• Journal of Navigation and Port Research
• /
• v.34 no.3
• /
• pp.205-211
• /
• 2010

Effects of operating parameters on electrical properties and ozone generation of Plasma Gun for ballast water treatment were investigated in a laboratory scale experiment. Electrical discharges and ozone generation initiated with applying voltages higher than discharge onset value. Ozone concentration was almost linearly increased with the increase of applied voltage. The optimum electrode gap distance which gave the optimum energy efficiency of ozone generation was 1.95 mm in the experimented apparatus. The effect of inner electrode material on the electrical energy transfer was negligible, however, the difference of electrical and thermal conductivities between electrode materials significantly influenced the ozone generation. In a constant geometrical structure, the electrical energy density played an important role in the ozone generation. The increase of oxygen content in the feeding gas enhanced the ozone generation by lowering ionization potential and promoting ozone source.

• The Journal of Korean Society for Radiation Therapy
• /
• v.10 no.1
• /
• pp.11-22
• /
• 1998

The absolute absorbed dose can be determined according to the measurement conditions ; measurement material, detector, energy and calibration protocols. The purpose of this study is to compare the absolute absorbed dose due to the differences of measurement condition and calibration protocols for photon beams. Dosimetric measurements were performed with a farmer type PTW and NEL ionization chambers in water, solid water, and polystyrene phantoms using 6MV photon beams from Siemens linear accelerator. Measurements were made along the central axis of $10{\times}10cm$ field size for constant target to surface distance of 100cm for water, solid water and polystyrene phantom. Theoretical absorbed dose intercomparisons between TG21 and IAEA protocol were performed for various measurement combinations on phantom, ion chamber, and electrometer. There were no significant differences of absorbed dose value between TG2l and IAEA protocol. The differences between two protocols are within $1\%\;while\;the\;average\;value\;of\;IAEA\;protocol\;was\;0.5\%$ smaller than TG2l protocol. For the purpose of comparison, all the relative absorbed dose were nomalized to NEL ion chamber with Keithley electrometer and water phantom, The average differences are within $1\%,\;but\;individual\;discrepancies\;are\;in\;the\;range\;of\;-2.5\%\;to\;1.2\%$ depending upon the choice of measurement combination. The largest discrepancy of $-25\%$ was observed when NEL ion chamber with Keithley electrometer is used in solid water phantom. The main cause for this discrepancy is due to the use of same parameters of stopping power, absorption coefficient, etc. as used in water phantom. It should be mentioned that the solid water phantom is not recommended for absolute dose calibration as the alternative of water, since absorbed dose show some dependency on phantom material other than water. In conclusion, the trend of variation was not much dependent on calibration protocol. However, It shows that absorbed dose could be affected by phantom material other than water.

• Radiation Oncology Journal
• /
• v.1 no.1
• /
• pp.21-24
• /
• 1983

The thickness of the part being irradiated is finite. Percent depth dose tables being used routinely are generally obtained from dosimetry in a phantom much thickner than usual patient. At or close to exit surface, the dose should be less than that obtained from the percent depth dose tables, because of insufficient volume for backscattering. To know the difference between the true absorbed dose and the dose obtained from percent depth dose table, the doses at or close to the exit surface were measured with plate type ionization chamber with volume of 0.5ml. The results are as follows; 1. In the case of $^{60}Co$, percent depth dose at a given depth increases with underlying phantom thickness up to the 5cm. 2. In the case of $^{60}Co$, the dose correction factor at exit surface which is less than 1, increases with part thickness and decreases with field size. 3. Exposure time may not be corrected when the part above 10cm in thickness is treated by $^{60}Co$. 4. In the case of 10MV x-ray, the dose correction factor is nearly 1 and constant for the underlying phantom thickness and field size, so the correction of monitor unit is not necessary for part thickness.

• Journal of Nutrition and Health
• /
• v.10 no.1
• /
• pp.34-37
• /
• 1977

Quantitative analysis of the fatty acids contained in Duck meat was carried out by the Gas Chromatography with Flame ionization Detector, The general components and chemical constants have been performed with A.O.A.C. methods. The results art summarized as follows : 1. General composition of Duck meat come out to be 64.87% moisture, 19.06% protein, 17.05% fat, and 1.02% ash. 2. It was investigated that extraction of lipids were performed by Soxhlet extractor for 12 hours. Amounts of lipids were extracted 79.57% in ethylether, 70.15% in chloroform, and 72.35% in n-hexane. 3. Chemical constants of lipids in Duck meat were obtained as follows : Saponification number 201.5, Acid number 5.01, Iodine number 50.1 and Carbonyl number 4.5 4. It was investigated that the fatty acid component were quantitatively determined by the gas chromatography : Linolenic acid 1.6%, Linoleic acid 19.9%, Oleic acid 45.9%, Stearic acid 3.1% Palmitic acid 17.2% and Myristic acid 0.12% in leg portion. Linolenic acid 1.7% Linoleic acid 17.2%, Oleic acid 51.2%, Stearic acid 3.3%, Palmitic acid 17.1% and Myristic acid 0.17% in breast portion. 5. Cholesterol of blood, breast and leg portion fat in Duck were obtained as follows : Total cholesterol 200 mg%, 260 mg% , and 400 mg% respectively; cholesterol ester 120mg%, 151 mg%, and 240mg% respectively.

• Bulletin of the Korean Chemical Society
• /
• v.34 no.8
• /
• pp.2419-2424
• /
• 2013

Guanosine-5'-diphosphate 3'-diphosphate (ppGpp) serves as alarmone in bacterial stringent responses. In this study, an affinity column was constructed by immobilizing ppGpp to NHS-Sepharose for isolating ppGpp-binding proteins. A novel ppGpp-binding protein, YjgA, was isolated and characterized by MALDI-TOF MS (matrix-assisted laser desorption ionization-time-of-flight mass spectrometry) coupled with two-dimensional gel electrophoresis. YjgA and truncated forms of YjgA were cloned and over-expressed in BL21 (DE3). The binding affinity of YjgA to ppGpp was determined by equilibrium dialysis. The interaction of YjgA with ppGpp was very specific, considering that the dissociation constant of YjgA with ppGpp was measured as $5.2{\pm}2.0{\mu}M$, while the affinities to GTP and GDP were about 60 and 30 times weaker than ppGpp. Expression of yjgA gene in Escherichia coli K-12 MG1655 was examined by reverse transcription polymerase chain reaction (RT-PCR). RT-PCR results revealed that yjgA was expressed from early to late stationary phase. The yjgA deletion mutant exhibited decreased cell number at stationary phase compared to parent strain and the over-expression of YjgA increased the cell number. These results suggested that YjgA might stimulate cell division under stationary phase. In most prokaryotic genome, about half of the protein candidates are hypothetical, that are expected to be expressed but there is no experimental report on their functions. The approach utilized in this study may serve as an effective mean to probe the functions of hypothetical proteins.

• Clean Technology
• /
• v.22 no.2
• /
• pp.89-95
• /
• 2016

The nanotoxicity of ZnO nanoparticles used in cosmetics and tire industry is one of emerged issues. Herein, the removal of ZnO nanoparticles dispersed in aqueous phase and its ecotoxicity were investigated. In the short-term exposure for fertilized eggs (O. latipes), the deformity was observed at 5 mg L⁻¹ of ZnO nanoparticles in some individuals and delayed hatching of eggs by retarded growth was observed at 10 mg L⁻¹ of ZnO nanoparticles. This result show that ZnO nanoparticles have cytotoxic effect to the organisms lived in water phase. Therefore, herein, the removal of ZnO nanoparticles in aqueous phase by chemical precipitation was investigated. After addition of Na₂S and Na₂HPO₄, the precipitated ZnO was transformed to ZnS and Zn₃(PO₄)₂ particles, respectively. The removal efficiency of ZnO was reached to almost 100% for two cases. In addition, the toxicity tests about ZnS and Zn₃(PO₄)₂ particles showed no acute toxicity for D. magna. This implies that transformation of ZnO to ZnS and Zn₃(PO₄)₂ particles with very low ionization constant might decrease effectively the toxicity of ZnO.

• Progress in Medical Physics
• /
• v.8 no.2
• /
• pp.87-102
• /
• 1997

The absolute absorbed dose can be determined according to the measurement conditions; measurement material, detector, energy and calibration protocols. The purpose of this study is to compare the absolute absorbed dose due to the differences of measurement condition and calibration protocols for photon beams. Dosimetric measurements were performed with a farmer type PTW and NEL ionization chambers in water, solid water, and polystyrene phantoms using 6MV photon beams from Siemens linear accelerator. Measurements were made along the central axis of 10cm $\times$ 10cm field size for constant target to surface distance of 100cm for water, solid water and polystyrene phantom. Theoretical absorbed dose intercomparisons between TG21 and IAEA protocol were performed for various measurement combinations of phantom, ion chamber, and electrometer. There were no significant differences of absorbed dose value between TG21 and IAEA protocol. The differences between two protocols are within 1％ while the average value of IAEA protocol was 0.5％ smaller than TG21 protocol. For the purpose of comparison, all the relative absorbed dose were nomalized to NEL ion chamber with Keithley electrometer and water phantom, The average differences are within 1％, but individual discrepancies are in the range of - 2.5％ to 1.2％ depending upon the choice of measurement combination. The largest discrepancy of - 2.5％ was observed when NEL ion chamber with Keithley electrometer is used in solid water phantom. The main cause for this discrepancy is due to the use of same parameters of stopping power, absorption coeficient, etc. as used in water phantom. It should be mentioned that the solid water phantom is not recommended for absolute dose calibration as the alternative of water, since absorbed dose show some dependency on phantom material other than water. In conclusion, the trend of variation was not much dependent on calibration protocol. However, it shows that absorbed dose could be affected by phantom material other than water.