• 한국대기환경학회지
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• 제29권3호
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• pp.307-316
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• 2013

The sensitivity of ozone to $NO_x$ and volatile organic compounds (VOCs) emission rates under different ventilation rates and $NO_2-to-NO_x$ emission ratios in a street canyon is investigated using a chemistry box model. The carbon bond mechanism IV (CBM-IV) with 36 gaseous species and 93 chemical reactions is incorporated. $NO_x$ and VOCs emission rates considered range from 0.01 to $0.30ppb\;s^{-1}$ with intervals of $0.01ppb\;s^{-1}$. Three different ventilation rates and three different $NO_2-to-NO_x$ emission ratios are considered. The simulation results show that the ozone concentration decreases with increasing $NO_x$ emission rate but increases with increasing VOCs emission rate. When the emission ratio of VOCs to $NO_x$ is smaller than about 4, the ozone concentration is lower in the street canyon than in the background. On average, the magnitude of the sensitivity of ozone to $NO_x$ emission rate is significantly larger than that to VOCs emission rate. As the $NO_x$ emission rate increases, the magnitude of the sensitivity of ozone to $NO_x$ and VOCs emission rates decreases. Because the ozone concentration is lower in the street canyon than in the background, the increased ventilation rate enhances ozone inflow from the background. Therefore, the increase in ventilation rate results in the increase in ozone concentration and the decrease in the magnitude of the sensitivity of ozone to $NO_x$ and VOCs emission rates when the emission ratio of VOCs to $NO_x$ is smaller than about 4. On the other hand, the increase in $NO_2-to-NO_x$ emission ratio results in the increase in ozone concentration because the chemical ozone production due to the $NO_2$ photolysis is enhanced. In the present experimental setup, the contribution of the change in $NO_2-to-NO_x$ emission ratio to the change in the sensitivity of ozone to $NO_x$ emission rate is larger than that of the change in ventilation rate.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집D
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• pp.66-70
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• 2001

The combustion characteristics have been investigated to develop the low $NO_{x}$ gas turbine combustor. The lean premixed combustion technology was applied to reduce the $NO_{x}$ emission. Also, the conventional combustor was designed and tested for the baseline of low $NO_{x}$ combustor performance. The test was conducted at the condition of high temperature and ambient pressure. The combustion air which has the temperature of 500K were supplied to the combustor through the air preheater. The temperature and emissions of $NO_{x}$ and CO were measured at the exit of combustor. The premixing chamber can be operated very lean condition of equivalence ratio around 0.35. The $NO_{x}$ was decreased with decreasing the equivalence ration. The CO was decreased with decreasing the equivalence ratio, but the CO was increased with decreasing the equivalence ratio below 0.45. But, at the very lean condition of equivalence ratio below 0.35 both NOx and CO were increased because of the flame unstability. The $NO_{x}$ was decreased slightly and CO was increased with increasing inlet air flowrate. This results can be used to determine the size of combustor. The low $NO_{x}$ combustor has lower values of $NO_{x}$ and CO compared with conventional one. Consequently the performance of combustor shows the possibility of the application to the gas turbine system.

• 한국안전학회지
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• 제31권5호
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• pp.22-27
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• 2016

The Electrostatic Charge Prevention Technology is a core factor that highly influences the yield of Ultra High Resolution Flat Panel Display and high-integrated semiconductor manufacturing processes. The corona or x-ray ionizations are commonly used in order to eliminate static charges during manufacturing processes. To develop such a revolutionary x-ray ionizer that is free of x-ray radiation and has function to control the volume of ion formation simultaneously is a goal of this research and it absolutely overcomes the current risks of x-ray ionization. Under the International Commission on Radiological Protection, it must have a leakage radiation level that should be lower than a recommended level that is $1{\mu}Sv/hour$. In this research, the new generation of x-ray ionizer can easily control both the volume of ion formation and the leakage radiation level at the same time. In the research, the test constraints were set and the descriptions are as below; First, In order not to leak x-ray radiation while testing, the shielding box was fully installed around the test equipment area. Second, Implement the metallic Ring Electrode along a tube window and applied zero to ${\pm}8kV$ with respect to manage the positive and negative ions formation. Lastly, the ion duty ratio was able to be controlled in different test set-ups along with a free x-ray leakage through the metallic Ring Electrode. In the result of experiment, the maximum x-ray radiation leakage was $0.2{\mu}Sv/h$. These outcome is lower than the ICRP 103 recommended value, which is $1{\mu}Sv/h$. When applying voltage to the metallic ring electrode, the positive decay time was 2.18s at the distance of 300 mm and its slope was 0.272. In addition, the negative decay time was 2.1s at the distance of 300 mm and its slope was 0.262. At the distance of 200 mm, the positive decay time was 2.29s and its slope was 0.286. The negative decay time was 2.35s and its slope was 0.293. At the distance of 100 mm, the positive decay time was 2.71s and its slope was 0.338. The negative decay time was 3.07s and its slope was 0.383. According to these research, the observation was shown that these new concept of ionizer is able to minimize the leakage radiation level and to control the positive and negative ion duty ratio while ionization.

• Journal of Korean Vacuum Science & Technology
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• 제4권4호
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• pp.112-121
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• 2000

The paper investigates electrical discharge properties in neon gas mixed with xenon. The breakdown temperature T$\sub$b/ and voltage V$\sub$b/ are obtained in terms of the gas mixture ratio X. It is shown that the breakdown voltage decreases, reaches the minimum value at X=0.02 and then increases again, as the mixture ratio X increases from zero to unity. Therefore, mixing the neon gas with a few percent of xenon is the most beneficial to reduce the breakdown voltage. Plasma density at breakdown in neon gas mixed with xenon is described in terms of the gas mixture ratio. The optimum value of mixture ratio for highest plasma density is found to be Xm=0.03. A preliminary experiment of AC-PDP is carried out for neon gas mixed with a few percent of xenon to verify some of the theoretical models. The experimental data agree qualitatively well with theoretical predictions.

• Nuclear Engineering and Technology
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• 제53권11호
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• pp.3816-3823
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• 2021

The mechanical features evaluated theoretically using Makishima-Mackenzie's model for glasses xBaO-(50-x) PbO-50P₂O₅ where x = 0, 5, 10, 15, 20, 30, 40, and 50 mol%. Wherefore, the elastic characteristics; Young's, bulk, shear, and longitudinal modulus calculated. The obtained result showed an increase in the calculated values of elastic moduli with the replacement of the PbO by BaO contents. Moreover, the Poisson ratio, micro-hardness, and the softening temperature calculated for the investigated glasses. Besides, gamma and neutron shielding ability evaluated for the barium doped lead phosphate glasses. Monte Caro code (MCNP-5) and the Phy-X/PSD program applied to estimate the mass attenuation coefficient of the studied glasses. The decrease in the PbO ratio has a negative effect on the MAC. The highest MAC decreased from 65.896 cm²/g to 32.711 cm²/g at 0.015 MeV for BPP0 and BPP7, respectively. The calculated values of EBF and EABF showed that replacement of PbO with BaO contents in the studied BPP glasses helps to reduce the number of photons accumulated inside the studied BPP glasses.

• Nuclear Engineering and Technology
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• 제53권6호
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• pp.2000-2010
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• 2021

Mechanical moduli, such as Young's modulus (E), Bulks modulus (B), Shear modulus (S), longitudinal modulus (L), Poisson's ratio (σ) and micro Hardness (H) were theoretically calculated for (100-x)TeO₂+x MgO glasses, where x = 10, 20, 30, 40 and 45 mol%, based on the Makishima-Mackenzie model. The estimated results showed that the mechanical moduli and the microhardness of the glasses were improved with the increase of the MgO contents in the TM glasses, while Poisson's ratio decreased with the increase in MgO content. Moreover, the radiation shielding capacity was evaluated for the studied TM glasses. Thus, the linear attenuation coefficient (LAC), mass attenuation coefficient (MAC), transmission factor (TF) and half-value thickness (𝚫_0.5) were simulated for gamma photon energies between 0.344 and 1.406 MeV. The simulated results showed that glass TM10 with 10 mol % MgO possess the highest LAC and varied in the range between 0.259 and 0.711 cm^-1, while TM45 glass with 45 mol % MgO possess the lowest LAC and vary in the range between 0.223 and 0.587 cm^-1 at gamma photon energies between 0.344 and 1.406 MeV. Furthermore, the BXCOM program was applied to calculate the effective atomic number (Z_eff), equivalent atomic number (Z_eq) and buildup factors (EBF and EABF) of the glasses. The effective removal cross-section for the fast neutrons (ERCSFN, ∑_R) was also calculated theoretically. The received data depicts that the lowest ∑_R was achieved for TM10 glasses, where ∑_R = 0.0193 cm² g^-1, while TM45 possesses the highest ERCSFN where ∑_R = 0.0215 cm² g^-1.

• 한국잠사곤충학회지
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• 제39권2호
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• pp.174-179
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• 1997

The larval head capsule width, larval weight and length of mulberry longicorn beetle, Apriona germari Hope were measured when the larvae were exuviated in artificial diet rearing. The larval head capsule width from the 1st to the 12th instar was ranged from 0.12 to 0.69 cm, and growth ratio of each instar was significantly high between the 1st and the 2nd instars. The fitness to Dyar's law for the larval head capsule width was 87.6%. When the logarithum of the larval head capsule width is plotted against the number of instars, the calculated regression line was LogY=0.12086+0.06998X and Dyar's constant was 1.18. The larval weight was increased with larval developmental stages, and the coefficient of variation of larval weight was apparently high. But the calculated regression line was LogY=-0.91592+0.25959X and Dyar's constant was 1.25. The growth ration of the larval length was clearly high between the 2nd and the 3rd instars, and that of larvae from the 4th instar was decreased. The calculated regression line was LogY=-0.16932+0.09841X and Dyar's constant was 1.25. In conclusion, our results suggested that the larvae growth of mulberry longicorn beetle appeared to be highly related in the larval head capsule width, larval weight and length.

• 대한전기학회논문지
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• 제41권5호
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• pp.525-532
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• 1992

Fluorine-doped YBaS12TCuS13TOS17-xTFS1yT superconducting materials with y varing two orders of magnitude form 0.02 to 2.0 have been prepared by a sol-gel process by using metal nitrate salts, sodium hydroxide and sodium fluoride. Fluorine contents have been measured using an ion-selective electrode. All fluorine doped as reactant were found to be present in the resulted samples. From the observation of XRD it has been concluded that the samples with y 0.2 formed simply the single phase of perovskite structure, whereas those with y 0.5 yielded together some compounds such as BaFS12T, YFS13T and CuO in the resulted samples. The observation of solid state S019TF NMR has been carried out in order to check whether fluorine was actually incorporated into the lattice sites, and the experimental results revealed that the mole ratio of fluorine incorporated into the lattice sites of YBaS12TCuS13TOS17-xT was approximately 0.2 per mole of the compound. Also electrical resistivity measurement indicated that onset transition temperature has the tendency to increase slightly with increasing y in the dilute region as y 0.2.

• 태양에너지
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• 제20권2호
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• pp.43-54
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• 2000

동시 진공증발법을 이용하여 coming glass, soda-lime glass, Mo가 증착된 soda-lime glass 위에 $Cu(In_{1-x}Ga_x)Se_2$ 박막을 증착하였다. Soda-lime glass 위에서 제조된 $Cu(In_{0.5}Ga_{0.5})Se_2$ 박막의 전기비저항값과 정공농도는Cu/(In+Ga)비에 큰 영향을 받지 않았다. Soda-lime glass위에서의 $Cu(In_{1-x}Ga_x)Se_2$ 박막내부와 표면에는 Na이 검출되었고, 표면의 Na는 산소와 결합하고 있었으며, Cu가 부족한 조성에서 이차상이 형성되었다. Ga/(In+Ga)비가 증가할수록 $Cu(In_{1-x}Ga_x)Se_2$ 박막은 회절 peak들의 큰 회절각으로 이동, 초격자 peak등의 분리, 결정립 크기의 감소가 관찰되었다. $Cu_{0.91}(In_{1-x}Ga_x)Se_2$ 박막은 Ga/(In+Ga)비에 무관하게 전기적으로 p-type을 나타내었다. Ag/n-ZnO /i-Zno/CdS/$Cu_{0.91}(In_{0.7}Ga_{0.3})Se_2$/Mo/glass구조의 태양전지를 제조하였으며, 태양전지변환효율(Eff.) = 14.48%, 단락전류밀도(Jsc) = $34.88mA/cm^2$, 개방전압(Voc) =581.5 mV, 충실도(F.F) = 0.714을 나타내었다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 C
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• pp.1493-1495
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• 2001

$(Ba_{0.6-x}Sr_{0.4}Ca_x)TiO_3+yAl_2O_3$ wt% (x=0.10, 0.15, 0.20, y=0.5 $\sim$ 3.0) specimens were fabricated by the mixed-oxide method and then the structural properties as a function of the composition ratio and $Al_2O_3$ contents were studied. All BSCT specimens showed dense and homogeneous structure without the presence of the seconds phase. The sintered density was decreased with increase ad $Al_2O_3$ content. The Curie temperature and dielectric constant at room temperature decreased with increasing $Al_2O_3$ content. The dielectric constant and dielectric loss of the doped-0.5 wt% $Al_2O_3$ BSCT(50/40/10) specimen were about 3131 and 0.932% at 1KHz, respectively.