• Korean Journal of Environment and Ecology
• /
• v.30 no.4
• /
• pp.793-799
• /
• 2016

This study examined Platanus orientalis and Ulmus davidiana planted in downtown parks to identify the correlations among microclimatic factors such as temperature in the crown, air flow, and wind speed. For the field survey, measurements were taken at 1 hour intervals from 09:00 am to 06:00 pm in August. For the measurement of microclimatic factors, data on temperature, light intensity, air flow, and wind speed were collected using a quantum sensor (PAR Quantum Sensor SKP215), a precision thermometer (Pt1000-Sensor), and a combination anemometer (1467 G4 & HG4). The results of the analysis demonstrated that both Platanus orientalis and Ulmus davidiana, showed a greater cooling effect inside the crown as compared with the outside temperature. The cooling effect inside the crown was more evident with air flow and wind speed factors. With relation to wind, the inner temperature of the crown of Platanus orientalis decreased due to air flow while that of Ulmus davidiana decreased due to wind speed. With no wind, the average variation in temperature inside the crown was $-0.9^{\circ}C$ for Ulmus davidiana and $-0.958^{\circ}C$ for Platanus orientalis, indicating that Platanus orientalis was relatively more effective in lowering the temperature of the planting space than Ulmus davidiana. This study is significant because it shows that different tree species have different effects on the microclimate and that factors affecting the formation of the microclimate of trees may vary with species. Further studies on species other than broad leaf trees, such as evergreen trees and shrubs, are required in order to plan the distribution of landscaping trees that are effective in regulating the microclimate within urban green spaces.

• Electrical & Electronic Materials
• /
• v.8 no.3
• /
• pp.278-284
• /
• 1995

Thin fihn SnO$_{2}$ Gas Sensor was fabricated by electron-beam evaporation system and the target made by general firing method for the purpose of detecting gas components in air, especially methane gas. SnO$_{2}$ thin film was prepared on the polished alumina substrate which Pt interdigital electrode was precoated. The effects of annealing temperature and substrate temperature on the structural properties of SnO$_{2}$ thin film on glass were investigated using the X-ray diffraction. The good crystalline structure is formed when substrate temperature is 150[.deg. C] and annealing condition is 550[.deg. C], 1[hour]. And the sensing properties at various thickness of the SnO$_{2}$ thin film and the effects of PdCI$_{2}$ addition were also investigated. The good result is showed when the thickness is below 1000[.angs.] and the quantity of PdCI$_{2}$ addition is 4[wt%]. The thickness of SnO$_{2}$ thin film was measured by .alpha.-step and Elliopsometer.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.14 no.12
• /
• pp.994-1000
• /
• 2001

In this paper, using micro-stereolithography technology, I fabricated a liquid analyzer to measure ion concentration of a solution. Micro-stereolithography is a technology to fabricate 3-dimensional structure by applying laser beam on liquid photo-polymer. This technology makes it possible to do preassemble fabrication without any extra assembling step after the process. So, the liquid analyzer could be fabricated at very low cost with very simple process by micro-stereolithography technology. The liquid analyzer consists of a chamber for containing the solution, a pump using piezoelectric effect of PZT disk, a static mixer and a sensor for measuring ion concentration using Pt electrodes.

• Journal of Sensor Science and Technology
• /
• v.15 no.3
• /
• pp.168-172
• /
• 2006

Potentiometric $CO_{2}$ sensors were fabricated using a NASICON ($Na_{1+x}Zr_{2}Si_{X}P_{3-X}O_{12}$, 1.8 < x < 2.4) thick film and auxiliary layers. The powder of a precursor of NASICON with high purity was synthesized by a sol-gel method. By using the NASICON paste, an electrolyte was prepared on the alumina substrate by screen printing and then sintered at $1000^{\circ}C$ for 4 h. A series of $Na_{2}CO_{3}-CaCO_{3}$ auxiliary phases were deposited on the Pt sensing electrode. The electromotive force (emf) values were linearly dependent on the logarithm of $CO_{2}$ concentration in the range between 1,000 and 10,000 ppm. The device attached with $Na_{2}CO_{3}-CaCO_{3}$ (1:2 in mol.%) showed good sensing properties in the low temperatures.

• Transactions of the Korean hydrogen and new energy society
• /
• v.15 no.4
• /
• pp.317-323
• /
• 2004

We fabricated a MISFET using Pd/NiCr gate for the detecting of hydrogen gas in the air and investigated its electrical characteristics. To improve stability and high concenntration sensitivity and remove the blister generated by the penetration of hydrogen atoms Pd/NiCr catalyst gate metal are used as dual gate. To reduce the gate drift voltage caused by the inflow of hydrogen, the gate insulators of sensing and reference FFET were constructed with double insulation layers of silicon dioxide and silicon nitride. The hydrogen response of MISFET were amplified with the difference of gate voltages of both MISFET. To minimize the drift and the noise, we used a OP177 operational amplifier. The sensitivity of the Pd/NiCr gate MISFET was lower than that of Pd/Pt gate MISFET, but it showed good stability and ability to detect high concentration hydrogen up to 1000ppm.