• Journal of Sensor Science and Technology
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• v.18 no.3
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• pp.245-250
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• 2009

The paper presents the wireless wind chill temperature measurement system that is composed of IEEE 802.15.4 standard wireless communication devices, hot film anemometer and serial communication temperature sensor. It's sometimes very difficult for a person, who lives in a high-rise apartment, to see the outside wind chill temperature due to harsh outside weather. The wind chill temperature is calibrated from an air velocity and air temperature. IEEE 802.15.4 standard wireless communication is ZigBee compatible, and consumes low power in communication. Under the air temperature of 5 $^{\circ}C$ and air velocity ranging from 0 to 50 km/h, the experimental result of wind chill temperature shows good accuracy within 5%.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.22 no.6
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• pp.397-407
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• 1990

Surface phytoplankton biomass was measured at approxinately one month intervals from July 1986 to August 1987. There was a peak phytoplankton biomass in the very low salinity region during summer and autumn when river discharge was low. The peak biomass occurred independent of the tidal state, location of nutrient input, nutrient concentration and temperature. The peak biomass are probably caused by the hydrodynamic trapping, density-seletive retention of particles by esturarine circulation.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.11a
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• pp.260-265
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• 2004

LTCC(Low temperature co-fired ceramic) is being recognized as a significant packaging material of electrical devices for the advantages such as relatively low temperature being needed for process, low conductor resistance and high printing resolution. In the process of LTCC electrical devices, the punched via-hole quality is one of the most important factors on the performance of the device. However, its mechanism is very complicated and optimization of the process seems difficult. In this paper, to clarify the process, via-hole punching experiments were carried out and the punched holes were examined in terms of their burr formation. The effects of thickness of PET sheet and ceramic sheet and punch-to-die clearance on via-hole quality were also discussed. Optimum process conditions are proposed and a factor k is introduced to express effect of the process variables.

• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.1646-1648
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• 2000

This paper investigated structural and electrical properties of $Y_{2}O_3$ as a buffer layer of sin91r transistor FRAM (ferroelectric RAM). $Y_{2}O_3$ buffer layers were deposited at a low substrate temperature below 400$^{\circ}C$ and then RTA (rapid thermal anneal) treated. Investigated parameters are substrate temperature, $O_2$ partial pressure, post- annealing temperature, and suppression of interfacial $SiO_2$ layer generation. for a well-fabricated sample, we achieved that leakage current density ($J_{leak}$) in the order of $10^{-7}A/cm2$, breakdown electric field ($E_{br}$) about 2 MV/cm for $Y_{2}O_3$ film. Capacitance versus voltage analysis illustrated dielectric constants of 7.47. We successfully achieved an interface state density of $Y_{2}O_3$/Si as low as $8.72{\times}10^{10}cm^{-2}eV^{-1}$. The low interface states were obtained from very low lattice mismatch less than 1.75%.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.47-50
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• 2000

This paper investigated structural and electrical properties of $Y_2$ $O_3$ as a buffer layer of single transistor FRAM (ferroelectric RAM). $Y_2$ $O_3$ buffer layers were deposited at a low substrate temperature below 40$0^{\circ}C$ and then RTA (rapid thermal anneal) treated. Investigated parameters are substrate temperature, $O_2$ partial pressure, post-annealing temperature, and suppression of interfacial $SiO_2$ layer generation. For a well-fabricated sample, we achieved that leakage current density ( $J_{leak}$) in the order of 10$^{-7}$ A/$\textrm{cm}^2$, breakdown electric field ( $E_{br}$ ) about 2 MV/cm for $Y_2$ $O_3$ film. Capacitance versus voltage analysis illustrated dielectric constants of 7.47. We successfully achieved an interface state density of $Y_2$ $O_3$/Si as low as 8.72x1010 c $m^{-2}$ e $V^{-1}$ . The low interface states were obtained from very low lattice mismatch less than 1.75%.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.55 no.1
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• pp.35-40
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• 2006

Heat-pump system has a special feature that provides heating operation in winter season and cooling operation in summer season with a single system. It also has a merit that absorbs and makes use of wastewater heat, terrestrial heat, and heat energy from the air. Because heat-pump system uses midnight electric power, it decreases power peak load and is very economical as a result. By using the property that energy source is converted to low temperature when losing the heat, high temperature energy source is used to provide heating water and low temperature energy source is used to provide cooling water simultaneously in summer season. This study made up a heat-pump system with 4 air heat sources and a water heat source and implemented the optimal operation algorithm that works with numbers of heat pumps to operate them efficiently. With the heat-pump system, we applied it to cooling and heating operation in summer season operation mode in a real building.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.207-207
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• 2003

Uncooled infrared(IR) detectors that use a microbolometer with a large focal-plane array(FPA) have been developed with surface micromachining technology. There are many materials for microbolometers, such as metals, vanadium oxide, semiconductors and superconductors. Among theses, vanadium oxide is a promising material for uncooled microbolometers due to it high temperature coefficient of resistance(TCR) at room temperature. It is, however, is very difficult to deposit vanadium oxide thin films having a high TCR and low resistance because of the process limits in microbolometer fabrication. In general, vanadium oxides have been applied to microbolometer in mixed phases formed by ion beam deposition methods at low temperature with TCR in the range from -1.5 to -2.0%K.

• Journal of ILASS-Korea
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• v.1 no.4
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• pp.24-31
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• 1996

This study addresses the behavior characteristics of diesel spray injected on the impinging disk with the room temperature. The models of impinging spray are the stick, the reflect and the wall jet model In the initiative of the fuel injection the impinging spray was the reflect model. because the momentum of droplets was very large. This model developed to the wall jet model according to the time approaches. On the low temperature disk the fuel film was made by the attachment of the droplets with low Weber number. The thickness of impinging spray was increased when the disk approached to the nozzle tip. Mathematical analysis for calculation with the behavior of impinging spray have to consider the reflecting effect and the influence of the fuel film.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.24 no.10
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• pp.724-732
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• 2012

The microchannel evaporator with louver fin using carbon dioxide are analyzed according to the frost growth. To predict the performance of microchannel evaporator with the frost growth under low temperature, the simulation condition of previous studies was applied. As a result, the frost thickness increases and its increasing rate is reduced when the operating time increases. Frost thickness increases gradually below the quality of 0.74, and then it decreases rapidly. In addition, the frost growth of present model under same surface temperature is very similar trends with Moallem's test results. In case of low temperature application, the dimensionless frost thickness increases dramatically and it is about 0.86 after 10 minutes.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1025-1029
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• 2003

We studied the cross-sectional profiles of deformed thermoplastics in hot embossing process and compared with melt flow index for various embossing conditions such as embossing temperature, embossing pressure and initial thickness of the thermoplastics. The fastest embossing times for complete penetration of the cavities were obtained at temperature greater than $60^{\circ}C$ above glass transition temperature (Tg). When the melt flow index of polymer is low, the penetration ratio does not become large even if the embossing pressure increases. The complete occupation of the cavities was easier obtained with high melt flow index polymer than low melt flow index polymer at the same process condition. We believe these results can be very useful for optimizing nanostructured hot embossing also known nanoimprinting process conditions.