• Journal of Convergence Society for SMB
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• v.2 no.1
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• pp.69-75
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• 2012

As the global warming and climate change cause the various social problems, such as disasters, abnormal temperature and diseases, technologies and studies for energy conservation and efficiency are increased. Energy use in buildings accounted for 22% of national energy use, so energy saving technology is promoted for residence, commercial and public buildings. Existing methods for energy conservation are passive ways, in that they consider heat loss and low-energy equipment. In recent years, active technologies emerge by converging with ICT, which detect and remove the energy waste situation by measuring, monitoring and controlling the energy use. In this paper, we describe technology trends for building energy optimization and investigates issues for active energy savings.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.8
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• pp.17-23
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• 2008

We have investigated the properties of the novel rectangular ring lasers containing active and passive regions in a InP material system. The rectangular ring laser consists of four low loss total internal reflection mirrors and a directional coupler made out of passive three waveguide. Two different lasers haying active lengths of 250 and $350{\mu}m$ and total cavity lengths of 580 and $780{\mu}m$ are fabricated, respectively. For both devices lasing thresholds of 38 mA is obtained at room temperature and under continuous wave operation. Lasing is predominantly single mode with the side mode suppression ratio better than 20 dB.

• Journal of Information Display
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• v.10 no.1
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• pp.33-36
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• 2009

A new hybrid silicon thin-film transistor (TFT) fabrication process using the DPSS laser crystallization technique was developed in this study to realize low-temperature poly-Si (LTPS) and a-Si:H TFTs on the same substrate as a backplane of the active-matrix liquid crystal flat-panel display (AMLCD). LTPS TFTs were integrated into the peripheral area of the activematrix LCD panel for the gate driver circuit, and a-Si:H TFTs were used as a switching device of the pixel electrode in the active area. The technology was developed based on the current a-Si:H TFT fabrication process in the bottom-gate, back-channel etch-type configuration. The ion-doping and activation processes, which are required in the conventional LTPS technology, were thus not introduced, and the field effect mobility values of $4\sim5cm^2/V{\cdot}s$ and $0.5cm^2/V{\cdot}s$ for the LTPS and a-Si:H TFTs, respectively, were obtained. The application of this technology was demonstrated on the 14.1" WXGA+(1440$\times$900) AMLCD panel, and a smaller area, lower power consumption, higher reliability, and lower photosensitivity were realized in the gate driver circuit that was fabricated in this process compared with the a-Si:H TFT gate driver integration circuit

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.11 s.102
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• pp.1114-1122
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• 2005

In this paper, the study of a design, fabrication and measurement of the receiver MMIC LNA, mixer for S-band application is described. The LNA is designed by 2-stage common source. The mixer is composed of active LO and RF balun to integrate on a chip and applied a newly proposed bias circuit to compensate the process variations of active devices. The LNA has 15.51 dB-gain and 1.02dB-Noise Figure at 2.1 GHz. The conversion gain of the mixer is -12 dB, IIP3 is approximately 4.25 dBm and port-to-port isolation is over 25 dB. The newly proposed bias circuit is composed of a few FETs and resistors, and can compensate the variation of the threshold voltage by the process variations, temperature changes and etc. The designed chip size is $1.2[mm]\times1.4[mm]$.

• Journal of the Korean Chemical Society
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• v.59 no.6
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• pp.488-492
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• 2015

In this study, the effective preparation method of (S)-(+)-pranidipine, the active component of antihypertensive drug as a calcium channel blocker, was developed using optical resolution. The racemic monocarboxylic acid 5 obtained by the hydrolysis of (±)-pranidipine was mixed with optically active quinidine to form salts, and the insoluble diastereomeric salt was collected and successive treatment with base and acid furnished (R)-(-)-carboxylic acid 7. (S)-(+)-Pranidipine was prepared by esterification of this acid with cinnamyl alcohol, and the analysis by chiral HPLC showed 100% enantiomeric excess (ee). This process would be industrially very useful to prepare chiral (S)-(+)-pranidipine, since the use of strong base and anhydrous solvents, and ultra-low temperature condition were excluded in this process.

• Carbon letters
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• v.8 no.4
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• pp.280-284
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• 2007

Samples of active carbon of $1150\;m^2/g$ surface area were impregnated with ammoniacal salts of copper, chromium and silver, with and without triethylenediamine. The samples of impregnated carbon were aged at $50^{\circ}C$, with and without 90% RH (relative humidity), for a little more than one year and chemically evaluated periodically. Initially copper (II) and chromium (VI) reduced very fast in the samples in humid atmosphere to the extent of 30% and 60% respectively in four months. These values were found to be unaffected by the presence of triethylenediamine (TEDA) indicating that the chemical did not retard the reduction process of chromium (VI) and copper (II). However, in the absence of humidity the reduction of the impregnants was significantly less (10-12%, w/w) in four months. It was quite evident; therefore, that the moisture was mainly responsible for the reduction of chromium (VI) and copper (II) species in impregnated carbons. The prolonged ageing of the samples with and without triethylenediamme after four months with and without humid atmosphere showed that the extent of reduction of chromium (VI) was very low, i.e. 5-10% and of copper (II) was 2-25%. Silver is not reduced due to carbon, as it remained unchanged in concentration on storage. The impregnated carbon samples (100 g) without triethylenediamine, which were aged at room temperature for 5 years in absence of humidity and unaged when evaluated against cyanogen chloride (CNCl) at a concentration of 4 mg/L and airflow rate of 30 lpm showed a high degree of protection (80- 110 minutes).

• Korean Journal of Materials Research
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• v.20 no.5
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• pp.235-240
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• 2010

We investigated the carbon monoxide (CO) gas-sensing properties of nanostructured Al-doped zinc oxide thin films deposited on self-assembled Au nanodots (ZnO/Au thin films). The Al-doped ZnO thin film was deposited onto the structure by rf sputtering, resulting in a gas-sensing element comprising a ZnO-based active layer with an embedded Pt/Ti electrode covered by the self-assembled Au nanodots. Prior to the growth of the active ZnO layer, the Au nanodots were formed via annealing a thin Au layer with a thickness of 2 nm at a moderate temperature of $500^{\circ}C$. It was found that the ZnO/Au nanostructured thin film gas sensors showed a high maximum sensitivity to CO gas at $250^{\circ}C$ and a low CO detection limit of 5 ppm in dry air. Furthermore, the ZnO/Au thin film CO gas sensors exhibited fast response and recovery behaviors. The observed excellent CO gas-sensing properties of the nanostructured ZnO/Au thin films can be ascribed to the Au nanodots, acting as both a nucleation layer for the formation of the ZnO nanostructure and a catalyst in the CO surface reaction. These results suggest that the ZnO thin films deposited on self-assembled Au nanodots are promising for practical high-performance CO gas sensors.

• Korean Chemical Engineering Research
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• v.51 no.4
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• pp.432-437
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• 2013

The CO preferential oxidation reaction (PROX) has been done using Cu catalytic active species supported on some of mesoporous silica materials which can facilitate the diffusion of the reactants in order to prevent the poisoning of anode active materials by CO molecules during driving polymer electrolyte fuel cells (PEMFC) in this study. As a result when SBA-15 with large pore used as a support showed excellent CO oxidation activity, especially the activity increased in proportion to the amount of supported Cu. Ti components which was inserted to increase the degree of dispersion of Cu, contributed to improving the performance for CO oxidation at low-temperature. The degree of dispersion of Cu ingredients was the best in the catalyst inserted 20 mol-% Ti into the framework of SBA-15, and CO oxidation activity was also improved.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.75.2-75.2
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• 2013

Atomic layer deposition (ALD), utilizing self-limiting surface reactions, could offer promising perspectives for future efficient energy conversion devices. The capabilities of ALD for surface/interface modification and construction of novel architectures with sub-nanometer precision and exceptional conformality over high aspect ratio make it more valuable than any other deposition methods in nanoscale science and technology. In the context, a variety of researches on fabrication of active materials for energy conversion applications by ALD are emerging. Among those materials, one-dimensional nanotubular titanium dioxide, providing not only high specific surface area but also efficient carrier transport pathway, is a class of the most intensively explored materials for energy conversion systems, such as photovoltaic cells and photo/electrochemical devices. The monodisperse, stoichiometric, anatase, TiO2 nanotubes with smooth surface morphology and controlled wall thickness were fabricated via low-temperature template-directed ALD followed by subsequent annealing. The ALD-grown, anatase, TiO2 nanotubes in alumina template show unusual crystal growth behavior which allows to form remarkably large grains along axial direction over certain wall thickness. We also fabricated dye-sensitized solar cells (DSCs) introducing our anatase TiO2 nanotubes as photoanodes, and studied the effect of blocking layer, TiO2 thin films formed by ALD, on overall device efficiency. The photon convertsion efficiency ~7% were measured for our TiO2 nanotubebased DSCs with blocking layers, which is ~1% higher than ones without blocking layer. We also performed open circuit voltage decay measurement to estimate recombination rate in our cells, which is 3 times longer than conventional nanoparticulate photoanodes. The high efficiency of our ALD-grown, anatase, TiO2 nanotube-based DSCs may be attributed to both enhanced charge transport property of our TiO2 nanotubes photoanode and the suppression of recombination at the interface between transparent conducting electrode and iodine electrolytes by blocking layer.

• Journal of Korean Society on Water Environment
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• v.37 no.6
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• pp.531-538
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• 2021

In this study, the TOC in six estuarine reservoirs in the West Sea (Ganwol, Namyang, Daeho, Bunam, Sapkyo, and Asan) was estimated using optically-active water quality factors by the water environment monitoring network. First, specification data and land use maps of each estuarine reservoir were collected. Subsequently, water quality data from 2013 to 2020 were collected. The data comprised of 11 parameters: pH, dissolved oxygen, BOD, COD, suspended solids (SS), total nitrogen, total phosphorus, water temperature, electrical conductivity, total coliforms, and chlorophyll-a (Chl-a). The TOC in the estuarine reservoirs was 4.9~7.0 mg/L, with the highest TOC of 7.0 mg/L observed at the Namyang reservoir, which has a low shape coefficient and high drainage density. The correlation of TOC with water quality factors was also analyzed, and the correlation coefficients of Chl-a and SS were 0.28 and 0.19, respectively, while the correlation coefficients of these factors in the Namyang reservoir were 0.42 and 0.27, respectively. To improve the estimation of TOC using Chl-a and SS, the TOC was averaged in 5 mg/L units, and Chl-a and SS were averaged. Correlation analysis was then performed and the R² of Chl-a-TOC was 0.73. The R² of SS-TOC was 0.73 with a non-linear relationship. TOC had a significant non-linear relationship with Chl-a and SS. However, the relationship should be assessed in terms of the spatial and temporal variations to construct a reliable remote sensing system.