• 한국전자통신학회논문지
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• 제8권4호
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• pp.541-547
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• 2013

레이더에서 거리분해능은 정확한 목표물 구분을 위해 판단하는 중요한 성능 파라미터이다. 기존의 아날로그 방식의 레이더시스템의 한계를 극복하기 위해, 현대 레이더 시스템 설계 목표는 적은 전송전력으로 거리분해능을 향상시키는 것으로 펄스압축기술에 대한 연구가 활발히 이루어지고 있다. 수신단에서 목표물 구분을 위해 펄스압축기술에 사용되는 송신신호의 변조방식은 크게 FM방식과 PM방식으로 나뉠 수 있다. 본 논문에서는 PM방식인 Barker Code를 이용하여 펄스압축 신호처리모듈을 구현하고 분석하였다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.1131-1134
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• 2003

Unknown parameters of a nonlinear system were estimated using a signal compression method. The estimated parameters were natural frequency and tile damping coefficient. This study applied a algorithm using tile comparison of the cross-correlation coefficient between the impulse response from a model and it from the signal compression method. The impulse through linear element included in a nonlinear system could be obtained by the signal compression method. The unknown parameters of the linear element could be estimated by comparing the Bode plots of system's impulse response with them of model's response. In this study, a LSCM(LabVIEW-Signal-Compression-Method) was developed to identify a nonlinear system. The LSCM consisted of National Instrument's (NI) Data Acquisition (DAQ) Board (Model PCI-1200), a monitoring program using LabVIEW software package, DAQ Signal Accessory Board, and 2nd-order electric circuits. The designed electric circuits consisted of resistors, inductors and capacitors. To evaluate the performance of the LSCM, the response from model with known parameters is compared with the response from the real system using the monitoring program. The results from simulation of experiment showed that the developed LSCM provided a reliable estimation performance.

• International Journal of Automotive Technology
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• 제7권6호
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• pp.675-680
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• 2006

In the direct injected gasoline engine, atomized spray is desired to achieve efficient mixture formation needed to good engine performance because the injection process leaves little time for the evaporation of fuels. Therefore, substantial understanding of global spray structure and quantitative characteristics of spray are decisive technology to optimize combustion system of a GDI engine. The combustion and emission characteristics of gasoline-fueled stratified-charge compression ignition(SCCI) engine according to intake temperature and compression ratio was examined. The fuel was injected directly to the cylinder under the high temperature condition resulting from heating the intake port. With this injection strategy, the SCCI combustion region was expanded dramatically without any increase in NOx emissions, which were seen in the case of compression stroke injection. Injection timing during the intake temperature was found to be an important parameter that affects the SCCI region width. The mixture stratification and the fuel reformation can be utilized to reduce the required intake temperature for suitable SCCI combustion under each set of engine speed and compression ratio conditions.

• Journal of Electrical Engineering and Technology
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• 제7권2호
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• pp.264-272
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• 2012

In the field of medical diagnostics, interested parties have resorted increasingly to medical imaging. It is well established that the accuracy and completeness of diagnosis are initially connected with the image quality, but the quality of the image is itself dependent on a number of factors including primarily the processing that an image must undergo to enhance its quality. This paper introduces an algorithm for medical image compression based on the quincunx wavelets coupled with SPIHT coding algorithm, of which we applied the lattice structure to improve the wavelet transform shortcomings. In order to enhance the compression by our algorithm, we have compared the results obtained with those of other methods containing wavelet transforms. For this reason, we evaluated two parameters known for their calculation speed. The first parameter is the PSNR; the second is MSSIM (structural similarity) to measure the quality of compressed image. The results are very satisfactory regarding compression ratio, and the computation time and quality of the compressed image compared to those of traditional methods.

• 한국식품과학회지
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• 제48권5호
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• pp.521-524
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• 2016

쌀밥의 조직감 측정시 가장 보편적으로 사용되는 텍스처 프로파일 분석(TPA)에 있어서, 모방적기기인 texture analyser를 사용하여 측정조건, 즉 압착율과 탐침이동속도를 달리하면서 4종류의 즉석쌀밥 시료들에 대한 경도, 점착성, 응집성, 씹힘성 및 탄성을 측정하였다. 4종류의 즉석쌀밥 시료들은 압착율과 탐침이동속도가 달라짐에 따라, 각각의 조직감 특성에 있어서 시료들 사이에 유의적인 차이를 보이거나 보이지 않는 변화를 보였다. 또한, 다섯가지 조직감 특성을 모두 고려하여 군집분석을 수행했을 경우에도 측정조건에 따라서 4종류 시료들이 서로 다르게 그룹화되는 것을 볼 수 있었다. 더불어, 쌀밥의 조직감 평가시 사용되는 '점착성/경도'값도 측정조건에 따라 4종류 시료들이 서로 다른 값을 보여주었다. 이들 결과를 토대로, 쌀밥의 조직감 측정시 쌀밥의 관능적 조직감 특성을 객관적으로 언급할 목적으로 기기적 측정을 수행한다면, 여러 분석을 통해 관능검사 결과와 가장 부합하는 측정 조건을 선택하는 것이 필요하며, 특정한 기기적 측정조건을 설정할 경우 실험목적에 따라 여러 특성을 고려하여 적합한 측정조건을 설정하는 것이 매우 중요하다 하겠다.

• Advances in nano research
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• 제9권2호
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• pp.69-82
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• 2020

In this paper, a new explicit analytical formula is derived for the critical buckling load of Double Walled Carbon Nanotubes (DWCNTs) embedded in Winkler elastic medium without taking into account the effects of the nonlocal parameter, which indicates the effects of the surrounding elastic matrix combined with the intertube Van der Waals (VdW) forces. Furthermore, we present a model which predicts that the critical axial buckling load embedded in Winkler, Pasternak or Kerr elastic medium under axial compression using the nonlocal Donnell shell theory, this model takes into account the effects of internal small length scale and the VdW interactions between the inner and outer nanotubes. The present model predicts that the critical axial buckling load of embedded DWCNTs is greater than that without medium under identical conditions and parameters. We can conclude that the embedded DWCNTs are less susceptible to axial buckling than those without medium.

• 한국정보과학회:학술대회논문집
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• 한국정보과학회 2010년도 한국컴퓨터종합학술대회논문집 Vol.37 No.1(A)
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• pp.242-243
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• 2010

Reducing compression artifacts such as ringing and blocking is one of important issues to improve a visual quality of a JPEG compressed image. In this paper, we propose a new post processing technique based on bilateral filtering (BF), which is one of the techniques that are used to reduce compression artifacts. An important issue with the application of the BF is the selection of the filter parameters, which affects the result significantly. In this work, we suggest a new method to select the filter parameter automatically. In addition to artifact reduction using the BF, a contrast enhancement is performed to overcome the contrast loss problem due to compression. The experimental result shows that the proposed approach can alleviate the artifacts efficiently.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -2
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• pp.864-867
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• 2002

Introduction of digital communication network such as Integrated Services Digital Networks(ISDN) and digital storage media have rapidly developed. Due to a large amount of image data, compression is the key techniques in still image and video using digital signal processing for transmitting and storing. Digital image compression provides solutions for various image applications that represent digital image requiring a large amount of data. in this paper, the proposed DWT(Discrete Wavelet Transform) filter bank is consisted of simple architecture, but it is efficiently designed that a user obtains a wanted compression rate as only input parameter. If it is implemented by FPGA chip, the designed encoder operates in 12MHz.

• 한국공작기계학회논문집
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• 제10권2호
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• pp.115-123
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• 2001

In recent years, compression molding of long fiber-reinforced thermoplastics has been increased in commercial aspects. In the process of compression molding of composites, the flow analysis must be developed in order to accurately predict the finished part properties as a function of the molding process parameters. In this model FRTP is assumed to be nonisothermal fluid, which has different viscosities in extensional and in shear. For verification of the model, the formation of a knit line in the L-shaped parts is compared with that of experiments results. In this paper we will discuss the effects of extensional & shear viscosity ratio and slip parameter $\alpha$ on the other modle fill-ing parameters.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 추계학술대회논문집 I
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• pp.444-449
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• 2001

The purpose of the work is to improve comfort of a car seat, especially dynamic comfort which affects driver's discomfort during the long time driving. Definition of dynamic comfort was made before the investigation of which parameter affects seat comfort. In order to optimize design parameters so as to maximize seat comfort as well as to know the cause of discomfort, benchmarking on a target vehicle and competitive vehicles was performed, which showed both the vibration transmission characteristics and the compression set due to dynamic loading should be reduced. As a solution ball rebounds was increased by about 10％ of the original foam, which showed reduction of S.E.A.T. value by 10％ and of compression set by 60％.