• The KIPS Transactions:PartB
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• v.15B no.4
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• pp.259-268
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• 2008

In an effort to increase the data capacity of one-dimensional symbology, 2D barcodes have been proposed a decade ago. In this paper, we present an effective 2D barcode detection algorithm from gray-level images, especially for the handheld 2D barcode recognition system. To locate the symbol inside the image, a criteria based on the block contrast is adopted, and a gray-scale projection with sub-pixel operation is utilized to segment the symbol precisely from the region of interest(ROI). Finally, the segmented ROI is normalized using the inverse perspective transformation for the following decoding processes. We also introduce the post-processing steps for decoding the QR-code. The proposed method ensures high performances under various lighting/printing conditions and strong perspective deformations. Experiments shows that our method is very robust and efficient in detecting the code area for the various types of 2D barcodes in real time.

• Journal of Korea Multimedia Society
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• v.7 no.10
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• pp.1378-1388
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• 2004

This paper proposes method to improve the image quality degradation that show when reconstructing compressed images at low bit rate by using wavelet transform. The image quality distortion is blocking artifacts and noise in DCT's compression but blocking artifacts of wavelet transform does not appear and ringing artifacts was appeared near the edge. This proposed technique is classified to part which is ringing artifacts of the edge vicinity appears which is not, apply adaptive filter to each region improved image. A edge region which is harsh to the eye is applied by Canny mask and finding strong edge region, search the neighborhood classify the flat region and the texture region, and apply to each region suitable filter, As experiment result, PSNR value of method that is proposed in that low bit rate compression image that ringing artifact appears became low about 0.05db, but 0.023db degree rose strong edge region and nat region's image. Also, showed picture quality improved more than ringing artifacts in nat region when see from subjective viewpoint of human.

• Journal of Broadcast Engineering
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• v.18 no.1
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• pp.10-20
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• 2013

Nowadays, video technology has been successfully improved creating tremendous results. As video technology improve, multimedia devices and demands from users are diversified. Therefore, a video codec used in these devices should support various displays with different resolutions. The technology to generate a higher resolution image from the associated low-resolution image is called interpolation. Interpolation is generally performed in either the spatial domain or the DCT domain. To use the advantages of both domains, we have proposed the new adaptive interpolation algorithm based on edge direction, which adaptively exploits the advantages of both domains. The experimental results demonstrate that our algorithm performs well in terms of PSNR and reduces the blocking artifacts.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.10C
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• pp.963-972
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• 2002

An 8192-point pipelined FFT/IFFT processor core is designed, which can be used in multi-carrier modulation systems such as DUf-based VDSL modem and OFDM-based DVB system. In order to improve the signal-to-quantization-noise ratio (SQNR) of FFT/IFFT results, two-step convergent block floating-point (TS_CBFP) scaling is employed. Since the proposed TS_CBFP scaling does not require additional buffer memory, it reduces memory as much as about 80% when compared with conventional CBFP methods, resulting in area-and power-efficient implementation. The SQNR of about 60-㏈ is achieved with 10-bit input, 14-bit internal data and twiddle factors, and 16-bit output. The core synthesized using 0.25-$\mu\textrm{m}$ CMOS library has about 76,300 gates, 390K bits RAM, and twiddle factor ROM of 39K bits. Simulation results show that it can safely operate up to 50-㎒ clock frequency at 2.5-V supply, resulting that a 8192-point FFT/IFFT can be computed every 164-${\mu}\textrm{s}$. It was verified by Xilinx FPGA implementation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.2C
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• pp.113-123
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• 2007

In Ubiquitous communication environment, various conversions of images are essential, and most digital images are compressed by standard methods such as the Joint Photographic Expert Group (JPEG) and Motion Picture Expert Group (MPEG) which are based on the discrete cosine transform (DCT). In this paper, various image resizing algorithms in the DCT domain are analyzed, and a new image resizing algorithm, which shows superior performance compared with the conventional methods, is proposed. For arbitrary-ratio image resizing in the DCT domain, several blocks of $8{\times}8$ DCT coefficients are converted into one block using the conversion formula in the proposed algorithm, and the size of the inverse discrete cosine transform (IDCT) is decided optimally. The performance is analyzed by comparing the peak signal to noise ratio (PSNR) between original images and converted images. The performance of the proposed algorithm is better than that of the conventional algorithm, since the correlation of pixels in images is utilized more efficiently.

• Journal of the Institute of Convergence Signal Processing
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• v.19 no.4
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• pp.199-205
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• 2018

So many fast motion estimation algorithms for prediction quality and computational reduction have been published due to tremendous computations of full search algorithm. In the paper, we suggest an algorithm that reduces computation effectively, while keeping prediction quality as almost same as that of the full search. The proposed algorithm based on multiple threshold filter calculates the sum of partial block matching error for each candidate, selects the candidates for the next step, compares the stability of optimal candidates with minimum error, removes impossible candidates, and calculates optimal motion vectors by determining the progress of the next step. By doing that, we can find the minimum error point as soon as possible and obtain the better performance of calculation speed by reducing unnecessary computations. The proposed algorithm can be combined with conventional fast motion estimation algorithms as well as by itself, further reduce computation while keeping the prediction quality as almost same as the algorithms, and prove it in the experimental results.

• Proceedings of the Korean Information Science Society Conference
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• 2003.04a
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• pp.383-385
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• 2003

침입 탐지 시스템에 이상 탐지 기법(anormal detection)을 적용할 때 정상적인 시스템호출 순서에 대한 훈련이 필요하다. 이 때 발생하는 가장 큰 문제점중 하나는 침입 없는 훈련 데이터의 확보이다. 훈련 데이터에 침입이 있으면 이 침입을 정상으로 간주해서 이후에 같은 침입이 일어나도 이를 탐지해 내지 못하기 때문이다. 하지만, 침입 없는 훈련 데이터를 얻는 것은 매우 어렵다. 본 논문에서는 훈련 데이터에 침입이 포함되어 있더라도 효과적으로 침입을 탐지할 수 있는 시스템 호출 기반 침입 탐지 기법을 제안한다. 제안 기법은 훈련 데이터에 침입이 존재할 경우 침입 부분에서 빈도가 매우 적은 데이터들이 연속적으로 나타나는 성질을 이용한다. 이를 위해 훈련 데이터를 일정 개수씩 블록으로 묶은 뒤 평균 빈도를 계산해서 그 값이 임계치보다 작은 경우 이를 침입 데이터로 간주하여 훈련 데이터에서 제외하는 방법을 사용하였다. 실험 결과 블록 크기를 적절하게 잡았을 경우 기존의 Eskin 기법보다 향상된 결과를 얻을 수 있었다.

• Proceedings of the Korea Information Processing Society Conference
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• 2000.10a
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• pp.175-178
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• 2000

본 논문에서는 공간영역에서 수행한 영상의 영역분류와 웨이브렛 변환대역 사이의 상관 관계를 이용한 새로운 점진적 영상 부호화 전송기법을 제안한다. 제안한 방법은 원 영상을 $2^n{\times}2^n$ 블록으로 분할 한 뒤 각 블록의 표준편차에 따라 저주파수 영역, 중간주파수 영역, 고주파수 영역으로 분류하고 각 영역의 특성에 따른 부호화 방식을 적용하여 부호화 효율을 증가시켰다. 실험의 결과 제안한 부호화 전송기법은 EZW 방식에 비해 복원화질 및 전송 비트율에서 좋은 결과를 나타내었으며, 사용자의 요구조건과 응용분야에 따라 점진적 전송이 가능함을 확인하였다.

• Proceedings of the Korean Information Science Society Conference
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• 2001.10c
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• pp.55-57
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• 2001

본 논문에서는 최근 이슈가 되고 있는 Fibre Channel과 같은 네트워크를 이용한 공유 디스크 시스템에서 다수의 호스트가 소프웨어 RAID\ulcorner 4 흑은 5를 이용할 때, 디스크 공유에 의해 발생하는 패리티 블록 일관성 문제를 다룬다. 본 논문에서는 XDWRITE을 이용해 Software HAID에서의 일관성 문제 해결과 디스크 1/0수 감소에 대해 설명한다. 또한, 버퍼캐쉬에서 파일 블록 쓰기 발생시 원본의 복사본을 이용하여 패리티 계산을 위한 디스크 읽기의 수를 감소 시키는 방법에 대해 제안한다. 본 논문에서 제안한 방식은 기존의 방식인 보다 1.5배에서 2배 디스크 1/0의 수를 감소시키는 것을 알 수 있다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.10a
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• pp.148-151
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• 2018

Software-Defined Networking, called SDN is a next-generation network technology that allows a centralized SDN controller to manage multiple switches and easily apply any network requirements, unlike traditional network devices. However, as the research on SDN has progressed rapidly in recent years, the security of SDN is also considered to be important. Therefore, in this paper, we investigate the major security problems in SDN and introduce a methodology to apply blockchain technology to SDN as a solution to solve them.