• 한국인터넷방송통신학회논문지
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• 제8권4호
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• pp.59-65
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• 2008

본 논문은 휴대용 멀티미디어를 위한 저전력 H.264 디블록킹 필터를 제안하였다. H.264 디블록킹 필터는 총 8개의 입력 픽셀에 대한 각각의 필터링 연산 과정을 필요로 하며, 각 필터링 과정에서 p, q 픽셀에 대해 공통 구조를 가지고 있다. 이 때 쓰이는 공통의 필터계수와 레지스터를 공유함으로써, 적은 게이트로 구현하였다. 또한 많은 연산을 필요로 하는 필터링 연산을 특정한 조건을 이용하여, 조건에 만족하면 일부 또는 전체의 필터링을 수행하지 않음으로써 저전력의 효율적인 구조를 설계할 수 있다. 제안한 H.264 디블록킹 필터 구조는 기존 논문들의 핵심 필터링부분과 비교하여 각각 33.31%와 10.85%의 게이트 감소효과를 나타내었다. 또한 본 논문의 전체 블록은 삼성 0.35um 표준 셀 라이브러리 공정을 사용하여 구현하였으며, 최대 동작 주파수는 108MHz, 최대 처리능력은 CCIR601 형식에서 33.03 frame/s이다.

• 천문학논총
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• 제22권4호
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• pp.183-187
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• 2007

The detection and measurement of faint features in cometary image is generally troublesome due to the high value of the ratio of the brightness of the nucleus to the tail, the large size and low surface brightness of the coma and tail and the disturbing presence of field stars trails. The image processing is based on background removal by median filtering. Sample results are shown for the case study of comet 73P/Schwassmann-Wachmann 3.

• 한국물환경학회지
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• 제18권4호
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• pp.401-409
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• 2002

In this study, to evaluate the applicability of ORP and pH as process control parameters for an intermittent aeration process, a 200L/d bench-scale plant was installed and operated for 90 days. It was fed with synthetic wastewater which contained $COD_{Cr}$ : 400mg/L, TN : 40mg/L and TP : 7mg/L. ORP & pH were measured on-line and compared with the variation of nutrient concentrations. As the results, both of the ORP and pH were able to monitor successfully nitrification and denitrification. Bending-points on the ORP curve and peak points on the pH curve corresponded to the termination of nitrification and denitrification. For P uptake and release, pH was the best indicator for performance evaluation. The aerobic pH apex was appeared when P uptake was accomplished and there was a relationship between the P release and pH variation. But the pH curve needed filtering because there were many noises on it. In this study, the shape of the ORP & pH curves were varied as the operating conditions such as aeration rates and organic loads were changed. It allowed the operating states of biological systems to be effectively evaluated. If it is properly managed to show the bending points and peak points clearly, the on-line monitoring of ORP & pH will be a reliable and effective technique for process control of intermittent aeration processes.

• 대한전기학회논문지:시스템및제어부문D
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• 제53권12호
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• pp.827-833
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• 2004

In active noise control (ANC) systems, the error-reduction performance of the conventional Filtered-X Least Mean Square (FXLMS) algorithm may be affected by nonlinear distortions in the secondary path such as in the power amplifiers, loudspeakers and transducers. In this paper, a nonlinear FXLMS algorithm with high error-reduction performance is proposed to compensate for undesirable nonlinearities in the secondary-path of ANC systems by employing the inverse Volterra filtering approach. In particular, the proposed approach is based on the utilization of the conventional P-th order inverse approach to nonlinearity compensation in the secondary path of ANC systems. Finally, the simulation results showed that the proposed approach yields a better nonlinearity compensation performance for the ANC systems with a nonlinear secondary path than the conventional FXLMS.

• Earthquakes and Structures
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• 제23권2호
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• pp.169-181
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• 2022

To research the dynamic response of the high-rise structure under the rocking ground motion, which we believed that the effect cannot be ignored, especially accompanied by vertical ground motion. Theoretical analysis and shaking table seismic simulation tests were used to study the response of a high-rise structure to excitation of a H-V-R ground motion that included horizontal, vertical, and rocking components. The use of a wavelet analysis filtering technique to extract the rocking component from data for the primary horizontal component in the first part, based on the principle of horizontal pendulum seismogram and the use of a wavelet analysis filtering technique. The dynamic equation of motion for a high-rise structure under H-V-R ground motion was developed in the second part, with extra P-△ effect due to ground rocking displacement was included in the external load excitation terms of the equation of motion, and the influence of the vertical component on the high-rise structure P-△ effect was also included. Shaking table tests were performed for H-V-R ground motion using a scale model of a high-rise TV tower structure in the third part, while the results of the shaking table tests and theoretical calculation were compared in the last part, and the following conclusions were made. The results of the shaking table test were consistent with the theoretical calculation results, which verified the accuracy of the theoretical analysis. The rocking component of ground motion significantly increased the displacement of the structure and caused an asymmetric displacement of the structure. Thus, the seismic design of an engineering structure should consider the additional P-△ effect due to the rocking component. Moreover, introducing the vertical component caused the geometric stiffness of the structure to change with time, and the influence of the rocking component on the structure was amplified due to this effect.

• Agricultural and Biosystems Engineering
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• 제3권2호
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• pp.59-64
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• 2002

Odor generated during composting of livestock manure is mainly due to ammonia emission. Biofiltration is a desirable method to control composting odor. This study was conducted to analyze the efficiency of using fresh compost as a biofilter. A mixture of cattle manure and recycled compost was composted in a bin equipped with a suction-type blower. The exhaust gas was filtered through the fresh compost. Residence time was controlled by the flow rate of exhaust gas and the depth of filtering materials. At the aeration rate of 30 L/min(experiment I), ammonia reduction rate varied from 100% to -15% for biofilter A(residence time 56.5 s) and almost 100% for biofilter B(residence time 113 s). At the aeration rate of 30 L/min, the cumulative ammonia reduction rate was 80.5% for biofilter A and 99.9% for biofilter B. At the aeration rate of 50 L/min(experiment II), the lowest reduction rate showed a negative value of -350% on the 8th and 9th day for biofilter A(residence time 33.9 5), and 50% on the loth day for biofilter B(residence time 67.8s). At the aeration rate of 50 L/min, the cumulative ammonia reduction rate was 82.5% fur biofilter A and 97.4% for biofilter B. Filtering efficiency was influenced by residence time. The moisture content(MC) and total nitrogen(T-N) of the filtering material were increased by absorbing moisture and ammonia included in the exhaust gas, while pH was decreased and total carbon(T-C) remained unchanged during the filtering operation.

• 대한의용생체공학회:의공학회지
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• 제32권3호
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• pp.245-250
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• 2011

Parallel imaging technique can provide several advantages for a multitude of MRI applications. Especially, in SENSE technique, sensitivity maps were always required in order to determine the reconstruction matrix, therefore, a number of difference approaches using sensitivity information from coils have been demonstrated to improve of image quality. Moreover, many filtering methods were proposed such as adaptive matched filter and nonlinear diffusion technique to optimize the suppression of background noise and to improve of image quality. In this study, we performed SENSE reconstruction using computer simulations to confirm the most suitable method for the feasibility of filtering effect and according to changing order of polynomial fit that were applied on variation of spatial resolution of sensitivity map. The image was obtained at 0.32T(Magfinder II, Genpia, Korea) MRI system using spin-echo pulse sequence(TR/TE = 500/20 ms, FOV = 300 mm, matrix = $128{\times}128$, thickness = 8 mm). For the simulation, obtained image was multiplied with four linear-array coil sensitivities which were formed of 2D-gaussian distribution and the image was complex white gaussian noise was added. Image processing was separated to apply two methods which were polynomial fitting and filtering according to spatial resolution of sensitivity map and each coil image was subsampled corresponding to reduction factor(r-factor) of 2 and 4. The results were compared to mean value of geomety factor(g-factor) and artifact power(AP) according to r-factor 2 and 4. Our results were represented while changing of spatial resolution of sensitivity map and r-factor, polynomial fit methods were represented the better results compared with general filtering methods. Although our result had limitation of computer simulation study instead of applying to experiment and coil geometric array such as linear, our method may be useful for determination of optimal sensitivity map in a linear coil array.

• 한국결정성장학회지
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• 제1권1호
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• pp.100-106
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• 1991

pH에 따른 Ba.Fe 수산화물의 용해도를 용해도적(Ksp)을 가지고 계산하여 침전물을 얻었으며 침전물은 $750^{\circ}C$에서 결정화하여 $BaFe_12O_19$ 단일상을 형성한다. 공침물을 각기 다른 Process를 사용하여 filtering과 sintering하였다. 즉 공침전물을 filter cake drying과 일반적인 grinding한 후 pressing하는 방법으로 소결시켰으며 각각 $950^{\circ}C$와 $1,100^{\circ}C$ 2시간 열처리에 의해 이론밀도의 98%에 이르는 치밀한 소결체를 얻을 수 있었다. 또한 freezing process에 서는 colloid상태의 침전물이 수십$\mu\textrm{m}$의 분말을 형성하여 Filtering 효율을 크게 증진시킬 수 있었다.

• 한국광물학회지
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• 제13권4호
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• pp.186-195
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• 2000

To study phosphate adsorption on kaolinite, $^{31}$ P MAS NMR(magic angle spinning nuclear magnetic resonance spectroscopy)has been used for kaolinite reacted in 0.1 M phosphate solutions at pH’s from 3 to 11. There are at least 3 different forms of phosphate on kaolinite. One is the phosphate physically adsorbed on kaolinite surface (outer-sphere complexes) or species left after vacuum-filtering. The second is the phosphate adsorbed by ligand exchange (inner-sphere complexes), and the third is Al-phosphate precipitates which are pH dependent. Most of the inner-spherer complexes and surface precipitates are mainly on hydroxided Al(aluminol) rather than hydroxided Si(silanol). These are pertinent with the results obtained from the phosphate adsorption experiments on silica gel and ${\gamma}$-Al$_2$O$_3$ as model compounds, respectively. The two peaks with more negative chemical shifts(more shielded) than the ortho-phosphate peak (positive chemical shift) are assigned to be the inner-sphere complexes and surface precipitates. The $^{31}$ P chemical shifts of the Al-phosphate precipitates are more negative than those of inner-sphere complexes at a given pH due to the larger number of P-O-Al linkages per tetrahedron. The chemical shifts of both the inner-sphere complexes and surface precipitates are more negative than those of inner-sphere complexes at a given pH due to the larger number of P-O-Al linkages per tetrahedron. The chemical shifts of both the inner-sphere complexes and surface precipitates become progressively less shielded with increasing pH. For the inner-sphere complexes, decreasing phosphate protonation combined with peak averaging by rapid proton exchange among phosphate tetrahedra with different numbers of protons is though to be the reason for the peak change. The decreasing shielding with increasing pH for surface precipitates is probably due to the decreasing average number of P-O-Al linkages per tetrahedron combined with decreasing protonation like inner-sphere complexes.

• 한국결정성장학회:학술대회논문집
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• 한국결정성장학회 1996년도 제11차 KACG 학술발표회 Crystalline Particle Symposium (CPS)
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• pp.259-279
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• 1996

최근 정보·전자산업의 발전으로 고 신뢰성 전자재료에 대한 수요가 증대되고 있으며 이러한 첨단산업의 기반의 될 신소재 중 전자세라믹스가 차지하는 비중이 그 대부분을 차지하고 있으며 이에 대한 수요와 기대가 점점 커지고 있다. 이러한 전자세라믹스는 유전재료, 자성재료, 압전재료, 도전성 재료 등으로 나뉘게 된다. 어떠한 분류에 들어가든 그 조성은 금속의 산화물 형태가 일반적이며 미세한 분말의 성형체를 소결(sintering) 함으로써 최종제품으로 완성된다. 이러한 전잣라믹스가 최근 요구되는 고 신뢰성, 고 밀도화를 달성하기 위해선 원료 분말 제조단계부터 제어가 필요하다. 원료분말의 균일·균질성과 그 입도는 소결특성 뿐만아니라 전기적 특성에도 큰 영향을 미치기 때문이다. 세라믹스의 분말제조 방법 중 일반적으로 사용되는 방법으로는 고상 산화물을 혼합하여 하소(calcination)한 후 분쇄하는 '고상합성법'과 금속의 염 또는 alkoxide 용액을 이용하여 화학적으로 제조하는 '습식 화학적 합성법'이 있다. 고상합성법은 합성온도가 높고 기계적 분쇄와 혼합에 의존하므로 균일·균질성이 떨어지고 분말크기를 1㎛ 이하로 만들기 힘들다. 반면에 습식화학적 합성법은 기계적인 분쇄와 혼합에선 얻을 수 없는 원자 혹은 분자단위의 균일한 혼합과 submicron 이하의 미세한 분말을 얻을 수 있다. 따라서 이러한 습식 화학적 합성으로 얻은 분말을 사용하면 미세한 입자의 특성으로 인해 소결온도를 낮출 수 있으며 균일한 미세구조와 균질한 조성을 갖게되어 기계적·전기적 물성증진도 가져올 수 있게 된다. 습식 화학적 분말합성법은 전술하였듯이 alkoxide의 가수분해를 이용하는 sol-gel 법과 금속의 염(salt) 용액을 이용하여, 화학적으로 화합물 침전을 얻거나 또는 공침전물(coprecipitate) 형태의 분말을 얻는, 침전법으로 나뉠 수 있다. 침전법의 근본원리는 pH 및 pCO3 등에 따른 이온종의 용해도 차이를 이용하는 것으로써 각 이온종에 따른 solubility product(ksp)를 이용하여 설명된다. 본 연구에서는 침전법을 사용한 Ba-, Pb-계 전자세라믹스의 분말합성에 대한 이론적 고찰과 공정개발 및 실험을 통한 물성증진 효과에 대해 알아보았다. 본 실험상의 전자세라믹스 조성은 강유전체, 세라믹반도체, 압효과에 대해 알아보았다. 본 실험상의 전자세라믹스 조성은 강유전체, 세라믹 반도체, 압전재료로 널리 사용되는 BaTiO3, PZT(PbZrO3-PbTiO3)와 수직 자기기록매체로 큰 가능성이 있으며 hard ferrite로 널리쓰이는 Ba-feerite(BaFe12O19)로써 수산화물 형태의 침전에 대한 기구(mechanism)와 물성에 대해 살펴보았다. 이러한 침전법에 의한 분말합성 과정에는 소결체의 물성에 영향을 미치는 pH 조절제나 원료에서 혼입될 수 있는 Na+, K+, Cl-, SO4- 등의 제거(washing 혹은 filtering)가 필수적이다. 그러나 침전법에서 얻게 되는 분말은 매우 미세하여 colloid를 형성하게 되며, 이러한 colloid 상태의 미세한 침전입자가 filtering media에 끼이게 되어 견고하면서도 상당한 부피를 가지는 filter cake을 형성하기 때문에 filtering에 많은 시간과 다량의 filtering agent (본 실험의 경우엔 증류수)가 필요하게 된다. 따라서 이러한 문제점을 해결하기 위하여 colloid 상태의 침전물을 얼렸다 녹이는 freezing process를 개발, 적용하여 그 원리 및 효과, 그로인한 분말형태를 관찰하여 보았다.