• Journal of IKEEE
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• v.19 no.2
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• pp.148-154
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• 2015

Automotive electronics system must alarm accurately in every moment. In order to apply vehicle's image recognition algorithms, it is necessary to preprocess the system quickly. In this paper, blurred image correction method that utilizes histogram equalization and bilateral filter using deviation for driver assist system's image processing is proposed. It forms 5-stage processes namely scaler, equalization, modified noise filter, blur decision and edge detector. Using the extracted proper, values in bilateral filter for driving environment occurred driver assist system, the proposed algorithm is much faster processing time compare to the previous methods in blurred within 10 pixel. Results of experiment which are run time and experimental PSNR results using MATLAB is obtained and verified that our proposed algorithm is more faster performance compare with the existing methods.

• Journal of Biosystems Engineering
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• v.14 no.3
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• pp.196-206
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• 1989

와권(渦券) 노즐에 작용(作用)되는 힘은 분두(噴頭)의 도구(導溝) 및 와실(渦室)의 기능(機能)에 의하여 축방향력(軸方向力)과 반경방향력(半徑方向力)으로 분류(分類)되고, 이 두 개의 힘은 미립화(微粒化)의 과정(過程)에 각각(各各)의 특성(特性)을 주고 있다. 반경방향(半徑方向)의 힘은 분두(噴頭)에서 분사(噴射)되는 입자(粒子)에 전단력(剪斷力)으로서 작용(作用)하지만 이 힘의 크기는 물방울의 직경(直徑) $100{mu}m$을 기준(基準)하여 2.4m/s의 속도(速度) 이내(以內)의 범위(範圍)이었으며, 그 속도범위(速度範圍)는 다음 유도된 식(式)으로 산출(算出)할 수 있었다. $$V_{ot}=(\frac{8g{\sigma}}{d{\gamma}})^{1/2}$$ 축방향력(軸方向力)은 아래 유도된 식(式)과 같이 분사액류(噴射液流)의 굴절각에 매우 민감하게 영향을 미치었고, 그 크기는 반경방향력(半徑方向力)에 비교(比較)하여 큰 값을 나타내었다. $$V_{\ell}={\sigma}[\frac{1}{2}{\rho}_{a}sin2{\theta}_d-4({\mu}+{\eta})\frac{\ell}{r_o}]^{-1}$$.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.4
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• pp.630-638
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• 2001

This paper has been proposed a structure composed of FIRs and IIR filters as digital decimation filter to compensate the drooping inband on the high precision AU chips. The area of chip has been reduced compared with the conventional structure because the RAM and MAC is reduced. The passband ripple$(\leq\; 0.4535 \times fs)$, passband attenuation(at $\; 0.4535 \times fs$ and stopband attenuation$(\geq\; 0.59\times fs)$ of the 6th-order $\Delta\Sigma$ modulator and digital decimation filter had $\pm0.0007[dB]$, -0.0013[dB] and -110[dB] respectively. Also the inband group delay, which was almost same compared with the conventional digital decimation filter structure, was 30.07/fs[s] band the error of group delay was 0.1672%.

• Journal of the Korean Society for Heat Treatment
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• v.19 no.2
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• pp.103-108
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• 2006

Microstructural evolution of Pt-aluminide coated Ni-based superalloy has been investigated with ductilization heat treatment. The Pt coat was prepared on the superalloy and then aluminide coating was conducted using a pack cementation process. Samples were heat-treated at $1050^{\circ}C$ for 2 hrs and the microstructure and element analysis were preformed. A various precipitated compounds were observed within the coating layer and the diffusion region in the Pt-aluminide coating and heat treatment, indicating that the bi-phase compounds of $PtAl_2$ and NiAl were performed during the Pt-aluminide coating, whereas $M_{23}C_6$, MC, $Ni_3Al$ and ${\sigma}$ phases were precipitated in the inter-diffusion region. The bi-phase compounds of $PtAl_2$ and NiAl were transformed into the single phase compound of $PtAl_2$ with the heat treatment, increasing the amount of carbide and ${\sigma}$ phase.

• Steel and Composite Structures
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• v.31 no.2
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• pp.187-199
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• 2019

This paper presents the semi-analytical development of the dynamic instability behavior and the dynamic response of functionally graded (FG) cylindrical shallow shell panel subjected to different type of periodic axial compression. First, in prebuckling analysis, the stresses distribution within the panels are determined for respective loading type and these stresses are used to study the dynamic instability behavior and the dynamic response. The prebuckling stresses within the shell panel are the same as applied in-plane edge loading for the case of uniform and linearly varying loadings. However, this is not true for the case of parabolic loadings. The parabolic edge loading produces all the stresses (${\sigma}_{xx}$, ${\sigma}_{yy}$ and ${\tau}_{xy}$) within the FG cylindrical panel. These stresses are evaluated by minimizing the membrane energy via Ritz method. Using these stresses the partial differential equations of FG cylindrical panel are formulated by applying Hamilton's principal assuming higher order shear deformation theory (HSDT) and von-$K{\acute{a}}rm{\acute{a}}n$ non-linearity. The non-linear governing partial differential equations are converted into a set of Mathieu-Hill equations via Galerkin's method. Bolotin method is adopted to trace the boundaries of instability regions. The linear and non-linear dynamic responses in stable and unstable region are plotted to know the characteristics of instability regions of FG cylindrical panel. Moreover, the non-linear frequency-amplitude responses are obtained using Incremental Harmonic Balance (IHB) method.

• The Bulletin of The Korean Astronomical Society
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• v.39 no.2
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• pp.106-106
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• 2014

SIGMA (Scientific cubesat with Instrument for Global Magnetic field and rAdiation)는 근 지구공간에서 우주방사선량 측정과 자기장 변화 검출의 과학적 목적과 교육적 목적을 가지고 개발하고 있는 초소형 큐브위성이다. $100mm{\times}100mm{\times}340.5mm$의 크기로 약 3.6 kg의 무게를 가지며, 탑재체는 방사선에 대하여 인체와 동일한 산란 흡수 특성을 가진 Tissue Equivalent Proportional Counter (TEPC)와 자기장 측정을 위한 Magnetometer (Mag)이다. 위성체는 구조계, 자세제어계, 전력계, 명령 및 데이터처리계, 통신계로 구성되어있다. 구조계는 위성의 뼈대인 Chassis와 Mag deployer로 이루어져있고, 위성의 안정적인 자세유지를 목적으로 Attitude Control System (ACS) Board와 Torque Coil이 자세제어계로 구성된다. 전력의 생산과 공급 및 충전은 태양전지판과 Electrical Power System (EPS), 리튬 배터리로 구성된 전력계에서 이뤄지며, 명령 및 데이터처리계는 On Board Computer (OBC)와 Instrument Interface board (IIB)를 중심으로 서브시스템의 명령체계와 데이터처리를 다룬다. 통신계는 Uplink인 VHF 안테나와 Downlink인 UHF, S-band 안테나로 구성되며 지상과 명령을 송수신한다. SIGMA는 타임인터럽트 기능을 활용한 Flight Software (FSW)로 운용되며 임무에 따른 6가지 모드의 시나리오로 위성을 운용한다. 이에 SIGMA의 개발과 테스트 결과를 소개한다. 본 큐브위성 개발기술을 바탕으로 향후 천문관측용 위성에도 활용할 예정이다.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.6
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• pp.60-67
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• 2008

A low-power 2.4GHz fractional-N frequency synthesizer has been designed for 2.4GHz ISM band applications such as Bluetooth, Zigbee, and WLAN. To achieve low-power characteristic, the design has been focused on the power optimization of power-hungry blocks such as VCO, prescaler, and ${\Sigma}-{\Delta}$ modulator. An NP-core type VCO is adopted to optimize both phase noise and power consumption. Dynamic D-F/Fs with no static DC current are employed in designing the low-power prescaler circuit. The ${\Sigma}-{\Delta}$ modulator is designed using a modulus mapping circuit for reducing hardware complexity and power consumption. The designed frequency synthesizer which was fabricated using a $0.18{\mu}m$ CMOS process consumes 7.9mA from a single 1.8V supply voltage. The experimental results show that a phase noise of -118dBc/Hz at 1MHz offset, the reference spur of -70dBc at 25MHz offset, and the channel switching time of $15{\mu}s$ over 25MHz transition have been achieved. The designed chip occupies an area of $1.16mm^2$ including pads where the core area is only $0.64mm^2$.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.26 no.3
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• pp.263-273
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• 2008

The precision of sensors' position is particularly important in the application of road extraction or digital map generation. In general, the various ranging solution systems such as GPS, Total Station, and Laser Ranger have been employed for the position of the sensor. Basically, the ranging solution system has problems that the signal may be blocked or degraded by various environmental circumstances and has low temporal resolution. To overcome those limitations a IMU/range integrated system could be introduced. In this paper, after pointing out the limitation of extended Kalman filter which has been used for workhorse in navigation and geodetic community, the two sampling based nonlinear filters which are sigma point Kalman filter using nonlinear transformation and carefully chosen sigma points and particle filter using the non-gaussian assumption are implemented and compared with extended Kalman filter in a simulation test. For the ranging solution system, the GPS and Total station was selected and the three levels of IMUs(IMU400C, HG1700, LN100) are chosen for the simulation. For all ranging solution system and IMUs the sampling based nonlinear filter yield improved position result and it is more noticeable that the superiority of nonlinear filter in low temporal resolution such as 5 sec. Therefore, it is recommended to apply non-linear filter to determine the sensor's position with low degree position sensors.

• Analytical Science and Technology
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• v.12 no.3
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• pp.235-242
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• 1999

It is impossible to measure the fraction of the precipitates which are neither plenty nor distiguishable on micrographs, using point counting method or image analyzer. In this study, phase fraction of sigma, carbide and boride which are important to mechanical properties of Ni base superalloy Udimet 720 has been measured using a quantitative X-ray diffraction technique combined with electrochemical extraction. The alloys had been exposed at $800^{\circ}C$ for various times up to 3000 hours to have a variation of the amount of the minor precipitates. The amount of sigma had increased exponentially with increasing exposure time up to 3000 hours before saturation. It can be argued that the finishing point of precipitation is around 5000 hours and maximum amount of sigma to be produced is about 5% in weight. The amounts of $M_{23}C_6$ and $M_3B_2$ were maintained constant at the level of 0.1~0.5% in weight, regardless of exposure time.

• Nuclear Engineering and Technology
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• v.17 no.3
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• pp.211-215
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• 1985

The effects of temperature and strain rate on the I-SCC behaviors of Zircaloy-4 were investigated by constant load test at 30$0^{\circ}C$ and constant elongation rate test at 300, 350 and 40$0^{\circ}C$ in 3.34mg $I_2$/㎤. The results showed that I-SCC susceptibility increased as the strain rate decreased or the temperature increased. The empirical relation between the stress and the time to failure at 30$0^{\circ}C$ was given by 1/ $t_{f}$∝exp (0.3$\sigma$/$\sigma$$_{UTS}$-31.5) When the I-SCC susceptibility was expressed by the ratio of fracture energy in iodine atmosphere to that in the inert atmosphere, severe I-SCC susceptibility was found near 7.6$\times$10$^{-6}$ sec at 30$0^{\circ}C$ and the maximum point of I-SCC susceptibility tended to shift to the higher strain rate with increasing the temperature. The quasi-cleavage fracture was observed in I-SCC fracture surface. From these results, it was certain that the film repture step was involved as an important process in the I-SCC mechanism of Zircaloy-4.4.