• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 1997.11a
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• pp.140-145
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• 1997

A stuey to investigate the perception characteristics of color and brightness was conducted in a combined PC and TV monitor, The objective of this study is to suggest user's favorite color temperature in PC mode and user's favorite contrast in TV mode. Investigated factors were monitor coating(coatiog vs. non-coation)and screen brightness (30fL vs. 35fL)in first experiment and monitor coating and pucture movement(static vs. dynamic) in second experiment. The first experiment was conducted in TV mode. Twenty-three subjects (male 12, female 11) perticipated in this experiment. In first experiment, average color temperatures were about 8000K in all experimental conditions. In addition, there was significant difference between coating and non-coating screen at 0.1 level. In second experiment, average contrasts were obtained in all esperimental conditions. There was significant difference between coating and ndn-coating screen at 0.05 level, In addition, there was significant difference between static picture and dynamic picture at 0.1 level

• Journal of Korean Society for Atmospheric Environment
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• v.9 no.2
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• pp.132-139
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• 1993

TCM has been used for many environmental impact assessments and many case studies in Korea. TCM was applied to urbvan areas and rolling terrains. But original TCM was developed for rural area, and this model could not reflect the characteristcs of these study sites. This paper analyzed the characteristics of TCM, and modified the algorithm of area source, and modified the vertical wind speed profile exponents and diffusion parameter to make it applicable in urban area. In the process of modification, an important error in area source calculation of original TCM program was found. So that was corrected as follows. $$ Before modification $QC = 0.79788456^*(0.5^*GRID)^**BA/(U(IA, IRUN)^*AA^*BA TCM09310$ After modification $QC = 0.79788456^*(500^*GRID)^**BA/(U(IA, IRUN)^*AA*BA) modified$ $$ Then original TCM and modified TCM-urban mode were compared, and it was found that predicted mean value by original TCM was 7 times higher than observed mean value. But mean value by modified TCM-urban mode was very similar to observed value.

• Proceedings of the IEEK Conference
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• 2000.07b
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• pp.949-952
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• 2000

A low power 10bit current-mode folding and interpolating CMOS analog to digital converter (ADC) with arithmetic folding blocks is presented in this paper. A current-mode two-level folding amplifier with a high folding rate (FR) is designed not only to prevent ADC from increasing a FR excessively, but also to perform a high resolution at a single power supply of 3.3V The proposed ADC is implemented by a 0.6${\mu}$m n-well CMOS single poly/double metal process. The simulation result shows a differential nonlinearity (DNL) of ${\pm}$0.5LSB, an integral nonlinearity (INL) of ${\pm}$1.0LSB

• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.4
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• pp.625-635
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• 1989

Mixed mode fracture problem is analyzed for the finite orthotropic plate where an inclined crack parallel to the fiber direction is centrally placed. Modified mapping collocation method with both uniform stress and uniform displacement boundary conditions is utilized to calculate stress intensity correction factors for glass/epoxy and graphite/epoxy composites. Computed results are presented for selected combinations of crack length to width ratio L/W and plate aspect ratio H/W with various fiber orientations.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.325-329
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• 2017

In this study, the combustion experiment of hydrocarbon-kerosene fueled dual mode ramjet combustor was performed at mach number 3.5~6.0 conditions. Through the experiment, the temperature and the pressure distribution inside the combustion chamber were measured and the combustion characteristics inside the combustion chamber were investigated. In the mach number 3.5~5.0 range, it was able to identify subsonic combustion in the downstream combustion chamber. In the mach number 6.0 condition, the injected fuel from the injectors was naturally fired, and it was possible to confirm that supersonic combustion was successful in the upper chamber.

• Journal of the Korean Society of Safety
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• v.34 no.6
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• pp.1-6
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• 2019

Carbon fiber has excellent specific strength, corrosion resistance and heat resistance. And p-Aramid fiber has high toughness and heat resistance and high elasticity, and is used in various fields such as industrial protective materials, bulletproof helmets and vests, as well as industrial fields. However, carbon fiber is relatively expensive, and is susceptible to brittle fracture behavior due to its low fracture strain. On the other hand, the aramid fiber tends to decrease in elastic modulus and strength when applied to the epoxy matrix, but it is inexpensive and has higher elongation and fracture toughness than carbon fiber. Thus the twill hybrid carbonaramid fiber reinforced composite laminate composite was investigated for a delamination fracture toughness under Mode I loading by 2 kinds of MBT and MCC deduction. The specimen was fabricated with 20 hybrid fabric plies. The initial crack was made by inserting the teflon tape in the center plane with a₀/W=0.5 length. The results show that SERR(Strain Energy Release Rate) as the critical and stable delamination fracture toughness were 0.09 kJ/㎡, 0.386 kJ/㎡ by MBT deduction, and 0.192 kJ/㎡, 0.67 kJ/㎡ by MCC deduction, respectively.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.42 no.4
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• pp.864-870
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• 2017

This paper describes a Dual Buck Converter with mode control using variable Frequency to Voltage for portable devices requiring wide load current. The inherent problems of PLL compensation and efficiency degradation in light load current that the conventional hysteretic buck converter has faced have been resolved by using the proposed Dual buck converter which include improved PFM Mode not to require compensation. The proposed mode controller can also improve the difficulty of detecting the load change of the mode controller, which is the main circuit of the conventional dual mode buck converter, and the slow mode switching speed. the proposed mode controller has mode switching time of at least 1.5us. The proposed DC-DC buck converter was implemented by using $0.18{\mu}m$ CMOS process and die size was $1.38mm{\times}1.37mm$. The post simulation results with inductor and capacitor including parasitic elements showed that the proposed circuit received the input of 2.7~3.3V and generated output of 1.2V with the output ripple voltage had the PFM mode of 65mV and 16mV at the fixed switching frequency of 2MHz in hysteretic mode under load currents of 1~500mA. The maximum efficiency of the proposed dual-mode buck converter is 95% at 80mA and is more than 85% efficient under load currents of 1~500mA.

• Journal of the Korean Chemical Society
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• v.39 no.12
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• pp.902-909
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• 1995

Detection limit as well as calibration curves on organophosphorus pesticide(dimethoate, diazinon, parathion-methyl, fenitrothion, malathion) and BHCs were measured for evaluation of utility on qualitative or quantitative analysis of pesticides with ion Trap mass spectrometer and quadrupole mass spectrometer. As ionization source, EI and CI were adopted for qualitative analysis of pesticides by comparison of each fragmentation pattern. At the same time, the utility as trace analysis techniques through scan or selected ion monitoring(SIM) mode was evaluated. With ion trap for all pesticides, detection limit(DL, 1 ${\mu}L$ injection) on scan mode was ranged 0.008∼0.225 ng at signal to noise ratio 3. With quadrupole DL on scan mode was ranged 0.23∼3.1 ng over 0.032∼0.68 ng on SIM mode. The calibration curve with ion trap generated good linearity over 0.99 as correlation coefficient. As clean up procedure, Bio Beads S-X3 was used for the separation of oils from five organophosphorous pesticides in flour extractant showing more than 80% as recovery at most cases. In case of BHCs in jinseng with Florisil column, the recovery of pesticides has been 60% to 90%.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.7C
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• pp.681-686
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• 2009

In H.264/Ave, an intra prediction added to the P-frame coding slightly improves both of image quality and bit rate, but greatly increases an amount of computation. In order to reduce the increase in computation, this paper proposes an image contents based intra prediction coding using characteristics that the best intra block mode depends on the image content of a macro block. The proposed algorithm estimates the image content with image complexity and the best inter block mode, and then selects or excludes a intra block mode on the basis of it. The simulation results show that the proposed algorithm reduces average O.OldB in image quality, and increases average 0.38% in the bit rate, but reduces average 37.02% in computation time compared with the conventional algorithm.

• Korean Journal of Remote Sensing
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• v.33 no.4
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• pp.351-358
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• 2017

A new method to decompose the footprints of marine atmosphere boundary layer (MABL) on Synthetic Aperture Radar (SAR) imagery into characteristic spatial scales is proposed. Using two-dimensional Empirical Mode Decomposition (EMD) we obtain three Intrinsic Mode Functions (IMFs), which mainly present longitudinal rolls, three-dimensional cells and atmospheric gravity waves (AGW). The rolls and cells have spatial scales between 3.0 km and 3.8 km and between 5.3 km and 7.1 km, respectively. Based on previous observations and mixed-layer similarity theory, we estimated MABL's depths that vary from 0.95 km to 1.2 km over the rolls and from 3.0 km to 3.8 km over the cells. The AGW has maximum spectrum at 14.3 km wavelength. The method developed in this work can be used to decompose other satellite imageries into individual features through characteristic spatial scales.