• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.9 s.351
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• pp.1-5
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• 2006

In this paper, the EM wave absorber was designed and fabricated for the collision-avoidance radar as a basic sensor of ITS(Intelligence Transport System), because radar system has some problems including false image and system-to-system interference. We fabricated some samples in different composition ratio of Carbon and CPE, and defined that optimum composition ratio of Carbon and CPE was 20:80 wt%. The complex relative permittivity was calculated by the measured data. And absorption abilities were simulated according to different thickness of the EM wave absorbers using the complex relative permittivity. The EM wave absorber was manufactured based on the simulated design. Simulated and measured results agree very well. As a result, the developed EM wave absorber with the thickness of 2 mm has absorption ability over 20 dB in frequency range of $76{\sim}77$ GHz.

• The Journal of the Korea institute of electronic communication sciences
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• v.11 no.5
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• pp.441-450
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• 2016

The International Telecommunications Union(: ITU) Radio Regulations(: RR) and in which is defined as the frequency of electromagnetic waves below 3000GHz spread in space without artificial guidance, our country also follows the international definition. As radio waves are electromagnetic waves spreading in space without artificial induction means having a frequency within the range set by the ITU. Frequency distribution for dual-work is to inde 300GHz, among the divided frequency is our daily or less than 90% of the frequency band is in contact saenghwalyong 3GHz. Propagation, but can occur indefinitely without depleting that anyone can create only gatchumyeon transmission equipment, if the radio frequency to use at the same time and space, the soul is the interference occurs is not available radio resources. Due to the physical finiteness used in our country for the first time on such a propagation laws enacted in 1961 and to the state radio resource management, and rules to be used for propagation only if granted the rights.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.3
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• pp.187-194
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• 2020

In this study, computational analyses are carried out to investigate the interference flows and the aerodynamic characteristics of a hit-to-kill intercepter due to lateral jets at medium altitude. In addition, the analyses are performed for air and multi-species gas used in the side jet. The results indicate that the position of the barrel shock are shifted upstream and the structure of the shock wave are changed for the multi-species jet when compared to the air jet. As a result, the high pressure region with multi-species jet moves forward and the pitching moment is higher under the same flow condition. Moreover, the inclusion of high temperature effects makes drastic changes in pressure distribution. The jet width is much bigger, and the jet diffuses over wider range in medium altitude than in low altitude, because of the low density of the freestream.

• Journal of Korean Society for Geospatial Information Science
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• v.13 no.3 s.33
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• pp.53-57
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• 2005

The moors ecosystem is sensitive environment change and weak in artificial interference. These nature property are very important to people. It is necessary to preservation and protection the moors with a countermeasure. We really need to Environment-GIS(E-GIS) using Geographical Information System(GIS) and digital map including range, correct position and attribute data of moors. In this study, we take priority of making a database of moors management. Taking effect an environment assesment, we concentrate on a standard method of digital map production and a preservation of moors in our research using GIS. Especially, we have to preserve our important national heritage using GIS when Environment Assesment is conducting under construction. We suggest to pre-estimated model of hidden moors as analysing terrain, geological feature, a geographical distribution of plants and animals using GIS.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.5
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• pp.423-430
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• 2014

Noise and vibration, which occur in a pipe, are usually caused by the interaction between the turbulent flow and nearby wall. Although it can be estimated by a simple case of expanded pipes having complex turbulent flow, the radiated noise is highly dependent upon the size, shape, and thickness of the given model. In addition, the radiated noise propagates and has serious interference and destabilization effects on the surrounding systems, which can lead to fatigue fracture and failure. This study took advantage of the variety of commercial programs, such as FLUENT (flow solver), NASTRAN (dynamic motion solver of complex structures) and VIRTUAL LAB (radiated noise solver) based on the boundary element method (BEM), to understand the underlying physics of flow noise. The expanded pipe has separation and a high pressure drop because of the abrupt change in the cross-section. Based on the radiated noise calculations, the noise level was reduced to around 20 dB in the range of 100-500 Hz.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.12 no.6
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• pp.279-283
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• 2012

In is paper, we design and implement the low power, high speed touch screen controller that calculates and outputs the coordinate of touch point on the touch screen of mobile devices. The system clock is 10HMz, the number of input channels is 21, standby current is $20{\mu}A$, dynamic range of input is 140pF~400pF and the response time is 0.1ms/frame. It contains the power management unit for low power, automatic impedance calibration unit in order to adapt to humidity, temperature and evaluation board, adjacent key and pattern interference suppression unit, serial interface unit of I2C and SPI. The function and performance is verified by using FPGA and $0.18{\mu}m$ CMOS standard process. The implemented touch screen is designed for using in the double layer ITO(Indium Thin Oxide) module with diamond pattern and single layer ITO module for cost-effective which are applied to mobile phone or smart remote controller.

• Journal of the Korean Chemical Society
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• v.48 no.2
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• pp.137-143
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• 2004

The determination of 2-mercapto-1-methyl-imidazole (MMI) in 5.0${\times}10^{-2}$ M lithium perchlorate suporting electrolyte has been investigated by the differential pulse polarography. The optimum condition of MMI analysis was as follows; -0.9 volts initial potential, 0.08 mV pulse height, 2 mV/sec scan rate, and medium mercury drop size. Standard calibration curve showed a good linearlity in the range of 1.0${\times}10^{-7}M\;to\;8.0{\times}10^{-5}$ M and the detection limit has been (2.2${\pm}0.1){\times}0.1^{-9}$ M. This method was applicated for the determination of MMI in antithyroid drug without interference of additives.

• Journal of Digital Contents Society
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• v.15 no.3
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• pp.319-326
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• 2014

IEEE 802.11 WLAN uses CSMA/CA(Carrier Sense Multiple Access/Collision Avoidance) method in MAC(Media Access Control) protocol, and through the carrier sense checks whether other users use the channel during the data transmission to avoid the data collision. Currently, IEEE 802.11 standard recommends the use of a fixed threshold which gives an impact on carrier sensing range. However, the existing scheme using the fixed threshold causes the operation of network to be inefficiency owing to the mobility in MANET(Mobile Ad hoc NETwork). In this paper, we found the better network throughput to be obtained by applying the proposed scheme, which chooses properly the carrier sensing threshold and transmission rate considering SINR(Signal to Interference-plus-Noise Ratio), to the MANET.

• Current Optics and Photonics
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• v.3 no.6
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• pp.590-596
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• 2019

To improve the color gamut of a liquid-crystal display (LCD), we propose a bandpass filter that is added to the backlight unit to optimize the backlight spectrum. The bandpass filter can only transmit red, green and blue light in the visible range, while reflecting the unwanted light. We study the optical properties of the bandpass filter using the transfer-matrix method, and the effect of the bandpass filter on the color gamuts of LCDs is also investigated. When a bandpass filter based on a 5-layer configuration comprising low and high refractive indices ((HL)²H) is used in phosphor-converted white-light-emitting diode (pc-WLED), K₂SiF₆:Mn⁴⁺ (KSF-LED), and quantum-dot (QD) backlights, the color gamuts of the LCDs improve from 72% to 95.3% of NTSC, from 92% to 106.7% of NTSC, and from 104.3% to 112.2% of NTSC respectively. When the incident angle of light increases to 30°, the color gamuts of LCDs with pc-WLED and KSF-LED backlights decrease by 2.9% and 1% respectively. For the QD backlight, the color gamut almost does not change. When the (HL)²H structure is coated on the diffusion film, the color gamut can be improved to 92.6% of NTSC (pc-WLED), 105.6% of NTSC (KSF-LED), and 111.9% of NTSC (QD). The diffusion film has no obvious effect on the color gamut. The results have an important potential application in wide-color-gamut LCDs.

• Journal of Sensor Science and Technology
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• v.1 no.1
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• pp.85-92
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• 1992

A new potassium sensitive field effect transistor modified with 4'-aminobenzo-15-crown-5 was prepared and its response characteristics were evaluated. The response slope of $K^{+}-ISFET$ for pH was 30.0 mV/decade and the response time was mere than 3 minutes. And the response slope and time of the $K^{+}-ISFET$ for potassium ion as $19.5{\pm}0.2{\;}mV/decade$ and about 3 minutes, respectively. The linear response range of the sensor for potassium ion was $2.0{\times}10^{-4}{\sim}1.0{\times}10^{-2}M$. The selectivity coefficients of the $K^{+}-ISFET$ for the alkali and alkaline earth metal ions were also evaluated. Sodium, ammonium and calcium ions exhibited relatively significant interference. The long term stability of the sensor was remarkably improved and it could be used for more than 50 days.