• Journal of Digital Contents Society
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• v.9 no.1
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• pp.17-26
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• 2008

This paper has for its object to propose AFOD(Adaptive First-Order Decimator) which sets a value of decimated element as an average of a value of neighbor intelligible component and a output value of FOD(First-Order Decimator) for the target pixel, and to analyze its performance in terms of subjective image quality and hardware complexity. In the proposed AFOD, a target pixel located at the center of sliding window is selected first, then the gradient amplitudes of its right neighbor pixel and its lower neighbor pixel are calculated using first order derivative operator respectively. Secondly, each gradient amplitude is divided by the summation result of two gradient amplitudes to generate each local intelligible weight. Next, a value of neighbor intelligible component is defined by adding a value of the right neighbor pixel times its local intelligible weight to a value of the lower neighbor pixel times its intelligible weight. Since the proposed method adaptively reflects neighbor intelligible informations of neighbor pixels on the decimated element according to each local intelligible weight, it can effectively suppress the blurring effect being the demerit of FOD. It also possesses the advantages that it can keep the merits of FOD with the good results on average but also lower computational cost.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.4 no.4
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• pp.391-397
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• 2003

This paper is about the digital image decimation algorithm which generates a value of decimated element by an average of a target pixel value and a value of neighbor intelligible element to adaptively reflect the merits of ZOD method and FOD method on the decimated image. First, a target pixel located at the center of sliding window is selected, then the gradient amplitudes of its right neighbor pixel and its lower neighbor pixel are calculated using first order derivative operator respectively. Secondly, each gradient amplitude is divided by the summation result of two gradient amplitudes to generate each intelligible weight. Next, a value of neighbor intelligible element is obtained by adding a value of the right neighbor pixel times its intelligible weight to a value of the lower neighbor pixel times its intelligible weight. The decimated image can be acquired by applying the process repetitively to all pixels in input image which generates the value of decimated element by calculating the average of the target pixel value and the value of neighbor intelligible element.

• Journal of the Korean Geotechnical Society
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• v.37 no.7
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• pp.5-12
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• 2021

When drilling investigations for Rock Slopes are not possible, it is often difficult to calculate the Ground Design Constants required for the Limit Equilibrium Analysis. Therefore, the outcrops or partially cutted Rock Slopes were analysed using JRC and JCS that can be easily and conveniently measured. In particular, the effect of the JRC on the Safety Factor or the Rock Slopes was analyzed intensively, and the results were presented as a relationship formula and Table. When the Rock slope was stable, the JRC increased by an average of 9.0% as the slope height increased, and increased by an average of 29.8% as the slope angle increased. JRC was more sensitive to slope angle changes. The Cohesion corresponding to JRC was calculated from JRC-Fs formula. JRC and Cohesion showed a nonlinear relationship, and the Cohesion was about 8.0% more sensitive to slope height changes than slope angle changes.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.1
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• pp.145-152
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• 2000

X-ray diffraction method detects change of crystal lattice distance under material surface using diffraction angle 2$\theta$. This technique can be applied to the behavior on slip band and micro crack due to material degradation. The relation between half-value breadth and number of cycle has three stages which constitute rapid decrease in initial number of cycles, slight decrease in middle number of cycles and rapid decrease in final number of cycles. The ratio of half-value breadth takes a constant value on B/B$_{0}$-N diagram with loading condition except early part of fatigue life. The ratio of half-value breadth B/B$_{0}$ with respect to number of cycle to failure N$_{f}$ has linear behavior on B/B$_{0}$-log N$_{f}$ diagram. Therefore, in this paper the estimation of fatigue life by average gradient method has much less estimated mean error than the estimation of fatigue life by log B/B$_{0}$-log N/N$_{f}$ relation.elation.ation.

• The Journal of the Acoustical Society of Korea
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• v.38 no.3
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• pp.283-289
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• 2019

RLS (Recursive-least-squares) algorithm is known to have good convergence and excellent error level after convergence. However, there is a disadvantage that numerical instability is included in the algorithm due to inverse matrix calculation. In this paper, we propose an algorithm with no matrix inversion to avoid the instability aforementioned. The proposed algorithm still keeps the same convergence performance. In the proposed algorithm, we adopt an averaged gradient-based step size as a self-adjusted step size. In addition, a variable forgetting factor is introduced to provide superior performance for time-varying channel estimation. Through simulations, we compare performance with conventional RLS and show its equivalency. It also shows the merit of the variable forgetting factor in time-varying channels.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.43 no.3 s.309
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• pp.50-58
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• 2006

This paper describes the implementation of an efficient Rate-Distortion Optimization algerian to speed up rate control in JPEG2000. While the conventional algorithm determines the rate constant by averaging maximum R-D slope and minimum R-D slope for entire image, the proposed algorithm determines it by using R-D slopes of coding passes located near truncation point. Moreover, the rate allocation in proposed algorithm is conducted about only coding passes excluded from the previous rate allocation. As a result, it can reduce the number of operations required for rate-distortion optimization. The proposed algorithm was implemented in C programing language and was executed on the Altera Excalibur(EPXA4) development board.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.1
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• pp.199-206
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• 2017

Environmental noise can degrade the performance of speech recognition system. This paper presents a procedure for performing cepstrum based feature compensation to make recognition system robust to noise. The approach is based on direct compensation of spectral tilt to remove effects of additive noise. The noise compensation scheme operates in the cepstral domain by means of calculating spectral tilt of the log power spectrum. Spectral compensation is applied in combination with SNR-dependent cepstral mean compensation. Experimental results, in the presence of white Gaussian noise, subway noise and car noise, show that the proposed compensation method achieves substantial improvements in recognition accuracy at various SNR's.

• Journal of the Society of Naval Architects of Korea
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• v.34 no.1
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• pp.41-49
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• 1997

Computational results from Navier-Stokes equations are presented for the Stokes-wave/flat-plate boundary-layer and wake for small wave steepness(Ak=0.01), including exact and approximate treatments of the viscous free-surface boundary conditions. The macro-scale flow indicate that the variations of the external-flow pressure gradients cause acceleration or deceleration of the streamwise velocity component and alternating direction of the cross flow. Remarkably, the wake displays a greater response, i.e., a bias with regard to favorable as compared to adverse pressure gradients. The micro-scale flow indicates that the free-surface boundary conditions have a profound influence over the boundary layer and near/intermediate wake. Order-of-magnitude estimates are conformed to the computational results. And appreciable errors are introduced through approximations to the free-surface boundary conditions.

• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.59-62
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• 2000

화상회의 및 인터넷폰을 목적으로 개발된 G.723.1은 CELP계열 보코더와 같이 화자의 개성정보를 위해 피치를 전송하고 있다. 하지만 안정구간과 비 안정구간의 차이를 두지 않고 처리를 하기 때문에 비 안정구간, 특히 전이구간에서 정확한 피치검출이 이루어지지 않는 이유로 음질의 열하가 발생하게 된다. 따라서 본 논문에서는 한 프레임 구간에서 에너지의 기울기로 대략적인 피치이득을 구한 다음 안정구간일 때와 프레임 내의 에너지의 기울기가 문턱 값을 넘을 때에는 기존의 방법으로 피치를 구하고 그런지 않은 경우에는 에너지를 조정하여 피치를 다시 구하는 방법을 사용하였다. 실제 음성시료에 대해 기존의 방법과 제안한 방법을 비교하기 위해 SegSNR 과 MOS를 비교하였을 때 각각 1.302(dB)와 평균 0.045 MOS가 향상되었다.

• Proceedings of the Korea Information Processing Society Conference
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• 2023.11a
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• pp.337-338
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• 2023

컨테이너 해상 유실 사고는 매해 적지 않은 수로 발생하고 있으나 기존에는 사후적 대응, 사전 대응 관점의 대응책들이 대부분이다. 그렇기에 항해 간 컨테이너 유실에 대한 모니터링이 필요한데, 선원들이 항해하는 선박에 적재된 수천 개의 컨테이너를 일일이 들여다보거나 모든 곳에 센서를 부착해 감지하는 것에는 물리적, 경제적 한계가 존재한다. 본 연구는 선박에 적재된 컨테이너들을 3차원 좌표 화하여 선박의 경사시험에서 모티브를 가져와 일정 정도의 기울기를 선박에 적용하였을 때, 기울기 중심을 기준으로 회전운동이 가장 큰 좌표에 해당하는 컨테이너들을 K-평균 군집화를 통해 최적화 위치로 선정하여 센서 위치를 최적화시켜 효율적인 컨테이너 유실 감지를 위한 기반을 마련한다.