• Journal of the Korea Society of Computer and Information
• /
• v.17 no.2
• /
• pp.113-118
• /
• 2012

In this paper, we discuss the design of the Digital Down Converters for the IEEE 802.11 wireless LAN receiver, which can be used for the customized receiver. The customized receiver can be used for special puropsed services which cannot be realized using the general custom chip. In the OFDM receiver, DDC receives the up sampled Inphase/Quadrature signal from the AD converter and process down sampling and filtering procedures using the Cascaded Intergrator Filter and FIR filters. We discuss the structure and design methodology of DDC's and analyze the simulation results.

• The Journal of the Acoustical Society of Korea
• /
• v.36 no.5
• /
• pp.345-352
• /
• 2017

We propose a methods which is reducing direction estimation error of sound source in the reverberant and noisy environments. The proposed algorithm divides speech signal into voice and unvoice using VAD. We estimate the direction of source when current frame is voiced. TDOA (Time-Difference of Arrival) between microphone array using the GCC-PHAT (Generalized Cross Correlation with Phase Transform) method will be estimated in that frame. Then, we compare the peak value of cross-correlation of two signals applied to estimated time-delay with other time-delay in time-table in order to improve the accuracy of source location. If the angle of current frame is far different from before and after frame in successive voiced frame, the angle of current frame is replaced with mean value of the estimated angle in before and after frames.

• Journal of the Institute of Electronics Engineers of Korea SP
• /
• v.37 no.5
• /
• pp.115-123
• /
• 2000

In this paper, a block FIR(Finite Impulse Response) filtering architecture is proposed for IF digital down converter. Digital down converter consists of digital mixers. decimation filters and down samplers. In this proposed structure, it is shown that a efficient parallel decimation filter architecture can be produced by cancellation of inherent up sampling of the block filter and following down sampler Furthermore. it is shown that computational complexity of the proposed architecture is reduced by exploiting the block FIR structure and zero values of the digital mixers.

• Proceedings of the Korean Society of Broadcast Engineers Conference
• /
• 2012.07a
• /
• pp.398-400
• /
• 2012

최근 3D에 대한 관심이 집중되면서 고품질의 3D영상을 얻기 위해 고품질의 깊이 영상이 필요하고 이를 구현하기 위한 연구가 활발히 진행되고 있다. 깊이 영상을 얻기 위해서 Time-of-Flight(ToF)방식의 깊이 센서가 활용되고 있는데 이 깊이 센서는 실시간으로 깊이 정보를 획득할 수 있지만 낮은 해상도와 노이즈가 발생한다는 단점이 있다. 따라서 깊이 센서로 생성된 저해상도 깊이맵을 고해상도로 변환해야 한다. 주로 깊이 영상의 해상도를 높이기 위해서 Joint Bilateral Upsampling(JBU) 방식이 사용되고 있다. 따라서 본 논문은 JBU 방식을 보강하여 블록단위로 분산에 따른 참조 영상의 가중치를 다르게 두어 깊이 영상의 품질을 향상시키는 방법을 제안한다.

• Journal of Broadcast Engineering
• /
• v.20 no.3
• /
• pp.414-420
• /
• 2015

The quality of depth images is important in the 3D video system to represent complete 3D contents. However, the original depth image from a depth camera has a low resolution and a flickering problem which shows vibrating depth values in terms of temporal meaning. This problem causes an uncomfortable feeling when we look 3D contents. In order to solve a low resolution problem, we employ 3D warping and a depth weighted joint bilateral filter. A temporal mean filter can be applied to solve the flickering problem while we encounter a residual spectrum problem in the depth image. Thus, after classifying foreground andbackground regions, we use an upsampled depth image for a foreground region and temporal mean image for background region.Test results shows that the proposed method generates a time consistent depth video with a high resolution.

• Journal of the Korea Computer Graphics Society
• /
• v.14 no.2
• /
• pp.19-25
• /
• 2008

We synthesize a texture with different structures at different scales. Our technique is based on deterministic parallel synthesis allowing real-time processing on a GPU. A new coordinate transformation operator is used to construct a synthesized coordinate map based on different exemplars at different scales. The runtime overhead is minimal because this operator can be precalculated as a small lookup table. Our technique is effective for upsampling texture-rich images, because the result preserves texture detail well. In addition, a user can design a texture by coloring a low-resolution control image. This design tool can also be used for the interactive synthesis of terrain in the style of a particular exemplar, using the familiar 'raise and lower' airbrush to specify elevation.

• Journal of the Korean Society of Radiology
• /
• v.15 no.2
• /
• pp.153-158
• /
• 2021

X-ray image analysis is a very important field to improve the early diagnosis rate and prediction accuracy of periodontal disease. Research on the development and application of artificial intelligence-based algorithms to improve the quality of such dental X-ray images is being widely conducted worldwide. Thus, the aim of this study was to design a super-resolution algorithm for predicting periodontal disease and to evaluate its applicability in dental X-ray images. The super-resolution algorithm was constructed based on the convolution layer and ReLU, and an image obtained by up-sampling a low-resolution image by 2 times was used as an input data. Also, 1,500 dental X-ray data used for deep learning training were used. Quantitative evaluation of images used root mean square error and structural similarity, which are factors that can measure similarity through comparison of two images. In addition, the recently developed no-reference based natural image quality evaluator and blind/referenceless image spatial quality evaluator were additionally analyzed. According to the results, we confirmed that the average similarity and no-reference-based evaluation values were improved by 1.86 and 2.14 times, respectively, compared to the existing bicubic-based upsampling method when the proposed method was used. In conclusion, the super-resolution algorithm for predicting periodontal disease proved useful in dental X-ray images, and it is expected to be highly applicable in various fields in the future.

• Journal of the Korea Computer Graphics Society
• /
• v.15 no.2
• /
• pp.1-8
• /
• 2009

This paper introduces a virtual dress up system, according to user's input model and garment image. At first step, we deform the garment image by using skeleton structures and ARAP method. Next step, sampling the boundary points and find their matching vertices which are used for optimizing the boundary fitting. In 2D rendering of the dress up, they have some unrealistic results, so we reconstruct the garment mesh to the 3D mesh. Rendering from the reconstructed 3D mesh, we can get the final dress up result. We present that our system produce a visually plausible and well-fitted virtual dress up results.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2017.05a
• /
• pp.89-89
• /
• 2017

유기농업은 저농약, 무농약, 자연농법과 함께 환경 친화적 농업으로 인식되어 세계적으로 유기농산물 생산량 및 재배면적이 급격하게 증가하고 있다. 국내 역시 안전한 먹거리 생산과 재배환경에서의 유해물질 관리방안 구축 등이 필요한 상황이다. 자가생산 유기농자재, 가축분을 이용한 축분 퇴비와 액비, 그리고 유박 등이 유기농업에 활용되고 있으나 사용 유기농자재의 양분가용화와 양분이용효율에 따른 비점오염원 형태로 토양 및 수질에 미치는 환경영향 등의 관측과 분석이 필요한 실정이다. 따라서 본 연구의 목적은 밭 포장에서의 유기농업 적용에 따른 유기농과 관행농에서의 대표적 비점오염원인 영양물질(T-N 및 T-P)에 대한 원단위를 평가하는데 있다. 시험포장은 전북 순장군 순창읍에 위치하고 있으며, 유기질비료시비 및 관행작물(고구마)의 3반복 1처리구(경사도 $6.6^{\circ}$)와 관행농관리 및 관행작물(고구마)의 1반복 1대조구(경사도 $6.8^{\circ}$)로 구성하였다. 현장에서 강우량과 유량을 실측하였으며, 강우 이벤트 시 T-N 및 T-P의 수질항목을 샘플링 후 분석하였다. 2016년 현재까지 총 6회의 강우 이벤트가 발생하였으며, 그 중 4회의 수질 샘플링을 실시하였다. 유출률은 평균 유기농에서 32%와 관행농에서 57%로 나타났다. 이는 토지피복 및 선행강우 등의 영향으로 다양한 분포를 보여주었다. 유기농 처리구에서 수질 부하량이 전체적으로 높게 나타났으며, T-N의 경우 4.4배와 T-P의 경우 1.8배로 나타났다. 이러한 경향은 유출수의 농도 영향보다 유출량의 영향이 큰 것으로 보인다. 유기농 처리구의 경우 제초제 등의 농작업이 제대로 이루어지지 않아 조도계수가 높았으며, 유기농 처리구에서 유출량이 31% 수준으로 상대적으로 낮게 나타났다. 본 연구의 경우 관행적으로 이루어지는 제초관리 형태를 벗어난 경우로 일반적인 결론 도출에는 한계가 있으나 유기농업 경작지에서 일반적으로 식생분포가 활발한 특성을 보여주고 있다. 향후 추가적인 모니터링 연구가 지속적으로 필요하며, 본 연구를 바탕으로 유기농업 최적관리방안 제시에 필요한 기초자료로 활용되기를 기대된다.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.31 no.6_1
• /
• pp.455-461
• /
• 2013

Kompsat-3 is an optical high-resolution earth observation satellite launched in May 2012. The AEISS sensor of the Korean satellite provides 0.7m panchromatic and 2.8m multi-spectral images with 16.8km swath width from the sun-synchronous near-circular orbit of 685km altitude. Kompsat-3 is more advanced than Kompsat-2 and the improvements include better agility such as in-track stereo acquisition capability. This study investigated the characteristic of the epipolar curves of in-track Kompsat-3 stereo images. To this end we used the RPCs(Rational Polynomial Coefficients) to derive the epipolar curves over the entire image area and found out that the third order polynomial equation is required to model the curves. In addition, we could observe two different groups of curve patterns due to the dual CCDs of AEISS sensor. From the experiment we concluded that the third order polynomial-based RPCs update is required to minimize the sample direction image distortion. Finally we carried out the experiment on the epipolar resampling and the result showed the third order polynomial image transformation produced less than 0.7 pixels level of y-parallax.