• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.544-549
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• 2009

The purpose of this study is to investigate the field Operation Characteristics of a sea water heat source cascade heat pump system and system applicable to Building. Cascade heat pump system is composed R410A compressor, R134a compressor, EEV, cascade heat exchanger, Plate heat exchanger etc. Building area is $890m^2$ and has five floors above ground. R410A is used for a low-stage working fluid while R134a is for a high-stage. The system could runs at dual mode. One is mode of general R410A refrigeration cycle in summer and the other is cascade cycle. In order to gain a high temperature supply water in winter season, the system is designed to perform a cascade cycle. The filed test results show that the sea water heat source heat pump system exhibits a COP of about 5.5 in cooling mode along with a heating COP of about 4.0 in 1-stage heating mode. Cascade 2-stage heat pump system is enough to supply $60^{\circ}C$ water and heating COP is about 3.0

• Korean Journal of Digital Imaging in Medicine
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• v.9 no.2
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• pp.11-16
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• 2007

We have evaluated and compared of gradient echo and spin echo EPI for compensating about deeply distortion aspect in case of post-operation patients in magnetic resonance image. A total of 100 patients were performed on 3.0 T(GE Signa Excite E2, USA) with 8ch head coil. As a result of analysis, The SNRs of whiter and gray matter areas were 36.74 $\pm$ 06 and 39.96 $\pm$ 09 in the gradient echo EPI, the SNRs which white and gray matter areas were slightly higher than gradient echo EPI(P<0.005, paired student t-test). It was 46.24 $\pm$ 11 and 51.38 $\pm$ 13 in gradient and spin echo EPI, respectively. The signal intensity in the whiter and gray matter areas also were 87.33 $\pm$ 15.24 and 140.66 $\pm$ 13.45 in the gradient echo EPI techniques, The signal intensity of gradient echo EPI showed higher values compared to spin echo EPI. Otherwise, gradient echo EPI technique is distortion enough to operation wound and edge of the image, while spin echo EPI technique did not appear almost. In this point, the spin echo EPI technique, after surgical operation according to patient state beside gradient echo EPI techniques that signalbeside gradient echo EPI techniques that signal intensity is high and patient's case which image distortion is serious by metal etc, will be provide the useful information in adults and pediatric patients.

• Journal of the Korean institute of surface engineering
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• v.41 no.2
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• pp.57-62
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• 2008

Electrochemical properties of Ti-30Ta-$(3{\sim}15)$Nb alloys coated by HA/Ti compound layer have been studied by various electrochemical method. Ti-30Ta binary alloys contained 3, 7, 10, and 15 wt% Nb contents were manufactured by the vacuum furnace system. The specimens were homogenized for 24 hrs at $1000^{\circ}C$. The samples were cut and polished for corrosion test and coating. It was coated with HA/Ti compound layer by magnetron sputter. The HA/Ti non-coated and coated morphology of Ti alloy were analyzed by x-ray diffractometer(XRD) and filed emission scanning electron microscope(FE-SEM). The corrosion behaviors were investigated using potentiodynamic method in 0.9% NaCl solution at $36.5{\pm}1^{\circ}C$. The homoginazed Ti-30Ta-$(3{\sim}15wt%$)Nb alloys showed the ${\alpha}+{\beta}$ phase, and ${\beta}$ phase peak was predominantly appeared with increasing Nb content. The microstructure of Ti alloy was transformed from needle-like structure to equiaxed structure as Nb content increased. HA/Ti composite surface showed uniform coating layer with 750 nm thickness. The corrosion resistance of HA/Ti composite coated Ti-alloys were higher than those of the non-coated samples in 0.9% NaCl solution at $36.5{\pm}1^{\circ}C$. Especially, corrosion resistance of Ti-Ta-Nb system increased as Nb content increased.

• KIPS Transactions on Software and Data Engineering
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• v.3 no.9
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• pp.349-354
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• 2014

Since Hadoop which is the Big-data processing platform was announced, SQL-on-Hadoop is the spotlight as the technique to analyze data using SQL on Hadoop. Tajo created by Korean programmers has recently been promoted to Top-Level-Project status by the Apache in April and has been paid attention all around world. Despite a sensible change caused by Hadoop's appearance in DW market, researches of those performance is insufficient. Thus, this study has been conducted to help choose a DW solution based on SQL-on-Hadoop as progressing the test on comparison analysis of RDBMS and Tajo. It has shown that Tajo based on Hadoop is more superior than RDBMS if it is used with accurate strategy. In addition, open-source project Tajo is expected not only to achieve improvements in technique due to active participation of many developers but also to be in charge of an important role of DW in the filed of data analysis.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.10A
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• pp.796-806
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• 2009

This paper presents the method of emergency warning system operation based on T-DMB and the design of T-DMB AEAS receiver model. The proposed receiver model compares the geographical location of emergency with the location of DMB transmitting station from T-DMB broadcasting signal and classifies the receiver location into alert region, neighboring region and non-alert region and transmits the emergency alert message according to each region. The geographical location of emergency can be obtained from FIG 5/2 EWS data field for AEAS message and the location of DMB transmitting station can be estimated from either the latitude and the longitude in main identifier and sub identifier in FIG 0/22 data filed for TII(Transmitter Identification Information) or TII distribution database. In our experiment, we implemented the proposed receiver model with display section, storage section, DMB module for receiving broadcasting signal and control section and performed test emergency alert broadcasting using T-DMB signal generator.

• The Journal of the Korea Contents Association
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• v.13 no.9
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• pp.392-399
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• 2013

The purpose of this study is to identify the manufacturing possibility of non-cement mortar using blast furnace slag and alkali accelerator. In this experimental study, the blast furnace slag which is the by-product of the steel industry substitute for cement, and the potassium hydroxide(KOH), calcium hydroxide ($Ca(OH)_2$) and sodium hydroxide(NaOH) as stimulus were added to each specimen. And the analysis on reaction property of non-cement mortar was conducted by measurement such as flexural and compressive strength, XRD, EDS and SEM. From the test results, it can be founded that $SiO_2$ and CaO included in the blast furnace slag are released and make the calcium silicate hydrate like the hydration reaction of the cement. Also, the continued study is need to reduce emission of $CO_2$ because of major content in filed of the building construction.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.169-170
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• 2006

In this study, ultra thin films of ferroelectric vinylidene fluoride-trifluoroethylene (VF2-TrFE) copolymer were fabricated on degenerated Si (n+, $0.002\;{\Omega}{\cdot}cm$) using by spin coating method. A 1~5 wt% diluted solution of purified vinylidene fluoride-trifluoroethylene (VF2:TrFE=70:30) in a dimethylformamide (DMF) solvent were prepared and deposited on silicon wafers at a spin rate of 2000~5000rpm for 30 seconds. After annealing in a vacuum ambient at $200^{\circ}C$ for 60 min, upper gold electrodes were deposited by vacuum evaporation for electrical measurement. X-ray diffraction results showed that the VF2-TrFE films on Si substrates had $\beta$-phase of copolymer structures. The capacitance on $n^+$-Si(100) wafer showed hysteresis behavior like a butterfly shape and this result indicates clearly that the dielectric films have ferroelectric properties. The typical measured remnant polarization (2Pr) and coercive filed (EC) values measured using a computer controlled a RT-66A standardized ferroelectric test system (Radiant Technologies) were about $0.54\;C/cm^2$ and 172 kV/cm, respectively, in an applied electric field of ${\pm}0.75\;MV/cm$.

• International Journal of Highway Engineering
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• v.15 no.5
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• pp.111-122
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• 2013

PURPOSES : The purpose of this system (Rear Lighting System) is to provide illumination for the driver to operate the commercial vehicle safely after dark in highway, to increase the conspicuity of the vehicle, and especially be suggesting the finest observable improvement method, depending on color and pattern of rear lighting system of truck for midnight highway traffic. METHODS : Rear lightning system as an improving way for forward commercial vehicles lighting the securing sight from human factors and the surrounding environment in midnight driving. For this one, basic materials were collected from the data analysis about many types of problems, and filed investigation for establishing Driving Simulator. also taking statistic test to human volunteers after finding recognizable distance of them. RESULTS : As a result, color with the highest visuality is amber followed by green-red-blue as in order for all road types. Especially almost no difference is found between red and green, also when the light is turn off, recognizable distances is wide difference compared to turn on the light. One more thing about study per pattern, upper and entire lighting have similar recognizable distances, but under lighting shows short distance with difficulty securing sight from medians. And straight section shows similar recognizable distances. By finding visuality improvement method depending on color and pattern of supplement taillight, it is expected to suggest quantitative judgement standard for introducing regulation and improvement of supplement taillight. CONCLUSIONS : Night time vehicle conspicuity to the rear is provided by rear position lamps. this study is showed that the color of light ramp is not important to be safe driving, most important is to turn on the light, recognizable distances is big different compared to turn off the rear light, so when the drivng dark in highway, have to turn on the light for reducing risk.

• Journal of Sericultural and Entomological Science
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• v.35 no.1
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• pp.11-16
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• 1993

Field experiment and silkworm rearing were conducted for 4years in an attempt to reduce phosphorus fertilizer in mulberry field with high levels of phosphate. Experiments consisted of four treatments; normal recommended P application(13kg P2O5/10a), half, null and no fertilizer on each of 3 mulberry fields, two fields with 300ppm and one filed begining with 450ppm of aviable P2O5 content in soil. One of 300ppm fields was used for leaf quantity and one for leaf quality test by silkworm rearing. Leaf yield in the 300ppm field decreased after the 3rd spring in the no phosphorus treatment and in the 4th fall in the half phosphorus treatment. No yield decrease occurred in 450ppm field for 4 years. Yield decrease did occur in the next rearing season after soil phosphate content in the 10~20cm zone dropped below 150ppm. Phosphorus fertilizer should be applied at this time. Though P2O5 concentration in leaves of no phosphorus treatment was 0.18% lower that that of conventional treatment, there were no difference in cocoon quality.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.10
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• pp.1290-1297
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• 2019

The paper proposes a distance estimation technique for ultra-wideband (UWB) systems using convolutional neural network (CNN). To estimate the distance from the transmitter and the receiver in the proposed method, 1 dimensional vector consisted of the magnitudes of the received samples is reshaped into a 2 dimensional matrix, and by using this matrix, the distance is estimated through the CNN regressor. The received signal for CNN training is generated by the UWB channel model in the IEEE 802.15.4a, and the CNN model is trained. Next, the received signal for CNN test is generated by filed experiments in indoor environments, and the distance estimation performance is verified. The proposed technique is also compared with the existing threshold based method. According to the results, the proposed CNN based technique is superior to the conventional method and specifically, the proposed method shows 0.6 m root mean square error (RMSE) at distance 10 m while the conventional technique shows much worse 1.6 m RMSE.