• 융합신호처리학회논문지
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• 제13권2호
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• pp.63-69
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• 2012

Noise is regarded as an unwanted component of the image because it significantly reduces image quality. And image is often corrupted by mixed noise. In this paper an efficient modified weighted filter algorithm which combines spatial weight and intensity weight is proposed for removing mixed noise. In the proposed method, the filtering mask is separated into the four sub-windows and the parameters of the weights are confirmed by calculating local standard deviation and the mean of four sub-windows' standard deviations. Considering the spatial information and intensity information, the proposed method has good performance on not only noise elimination but also preservation of details. Simulation results demonstrate that the proposed method performs better than conventional algorithms.

• 한국연초학회지
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• 제27권2호
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• pp.163-170
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• 2005

A theoretical model for predicting the capability curve of cellulose acetate filter is derived. The pressure drop is expressed as a function of the filter dimensions, the tow fiber characteristics, the filter weight, the fluid flow rate, and a filter fiber factor. Where, the filter fiber factor is affected by the distribution of the tow fibers within the filter, the relative orientations of the tow fibers, and their cross-sectional shapes. The minimum and maximum fraction of solids in capability curves determined from experimental data. Also, the filter fiber factor is expressed as a function of the filter length, tow fiber length, and tow fiber diameter. Capability curves predicted by the suggested model in this work correspond well with capability curves by experimental data.

• 센서학회지
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• 제25권1호
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• pp.8-12
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• 2016

A planar, light-weight, and low-cost notch filter structure is required for the KSTAR ECEI (Electron Cyclotron Emission Imaging) system to protect the mixer arrays from spurious plasma heating power. Without protection, this heating power can significantly degrade or damage the performance of the mixer array. To protect mixer arrays, a frequency selective surface (FSS) structure is the suitable choice as a notch filter to reject the spurious heating power. The FSS notch filter should be located between the lenses of the ECEI system. This paper presents a 170 GHz FSS notch filter for the KSTAR ECEI sensor application. The design of such an FSS notch filter is based on the single-sided square loop geometry, because that makes it relatively insensitive to the incident angle of incoming wave. The FSS notch filter exhibits high notch rejection with low pass-band insertion loss over a wide range of incident angles. This paper also reviews the simulated and measured results. The proposed FSS notch filter might be implemented in other millimeter-wave plasma devices.

• 융합신호처리학회논문지
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• 제11권3호
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• pp.238-243
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• 2010

A new implementation method for MPDSAP(Maximally Polyphase Decomposed Subband Affine Projection) adaptive filter is proposed. The affine projection(AP) adaptive filter achieves fast convergence speed, however, its implementation is so expensive because of the matrix inversion for a weight-updating of adaptive filter. The maximally polyphase decomposed subband filtering allows the AP adaptive filter to avoid the matrix inversion, moreover, by using a pipelining technique, the simple subband structured AP is suitable for VLSI implementations concerning throughput, power dissipation and area. Computer simulations are presented to verify the performance of the proposed algorithm.

• 전자공학회논문지A
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• 제33A권4호
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• pp.84-91
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• 1996

Input filter for satellite communication transponder is the interface between the antenna and the receiver. It is used to provide the selection of the uplink signals with minimum insertion loss and to prevent downlink signals form reaching the LNA. This paper is intended to provide a description of the input filter for KOREASAT communication transponder. Included are description for the electrical and mechanical design and the requirments of environmental test. In expecting the electrical performine the optimum electrical configuration ot meet all requirements are performed. Mechanical requirements are charactersed by several constraints for weight, size of the filter and its type of input output interface. The standardized environmental tests are performed to confirm satisfactory performance of the filter with respect to the requirements of vibration and thermal vacuum shocks.

• 한국연초학회지
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• 제23권1호
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• pp.77-81
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• 2001

This study was conducted to determine menthol migration from the tobacco to the filter and the change in percentage of menthol in pack for different mentholated cigarettes. Methanol was used to extract menthol from tobacco, filter and foil. A known weight of internal standard was added to each extract and then the extracts were analyzed by gas chromatography. After 4 days, 95% of the menthol applied to the foil was delivered into the tobacco and filter, but in case of menthol applied to the tobacco, the percentage of menthol that migrated from the tobacco to the filter was below 10%. After 100 days, 30-45% of the menthol in the tobacco had migrated into the filter. The amount of menthol in the pack decreased after 20 days of storage, however, the remaining menthol in cigarette treated with 0.30% propylene glycol was higher in amount than that with 0.12% propylene glycol In analysis on menthol transfer to mainstream smoke, the most efficient sample was the cigarette with menthol applied to the foil rather than to the tobacco.

• 한국산학기술학회논문지
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• 제4권3호
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• pp.164-167
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• 2003

본 연구에서는 무선부품의 일종인 cavity filter금형을 제작하여 도금용 ABS 수지와 PC/ABS alloy 수지를 사용하여 일반사출성형과 금형온도가 높은 MmSH방식, 두 타입으로 성형품을 제작하였다. 성형품의 수축률 변화는 MmSH 방식일 때 ABS 성형품의 단위캐비티 격막부분에서 수축률이 감소되었다. 중량변화는 ABS와 PC/ABS 성형품 모두 MmSH 방식일 때 증가하였고, 성형품 표면 거칠기는 MmSH 방식일 때 모두 거칠기가 감소되었다.

• 상하수도학회지
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• 제23권1호
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• pp.121-128
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• 2009

Objectives of this study were to investigate influencing factors of detention time, particle size distribution, and filter medium characteristics for waterworks sludge dewatering. The stepped pressure filtration was carried out with lab scale apparatus and the filter press pilot test for dewatering was conducted at the water treatment plant. Effects of filter medium and polymer dose were examined through observing water content and dewatering velocity and cyclic dewatering rate with filter press pilot test. Relationships among detention time, particle size distribution and filtration resistance were analyzed. Prolongation of sludge detention time was found to cause blinding phenomenon in cake and filter medium and to decrease dewatering process efficiency. The average specific resistance increased according to detention time. In pilot test of dewatering for thickened sludge with Nylon Multi-NY840D and Nylon Mono-100% filter media, dewatering velocities were 0.92 and $0.93kg\;DS/m^2{\cdot}hr$ according to 0.1% polymer dose of dried solids weight base. And cyclic dewatering rates were 2.45 and $2.50kg\;DS/m^2{\cdot}cycle$ cycle for the Nylon Multi-NY840D and Nylon Mono-100% media. Dewatering velocity of polymer dosed sludge was observed to be higher than that of non-polymer sludge.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2021년도 추계학술대회
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• pp.118-120
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• 2021

현대 사회는 IoT 기술의 발달에 따라 CCTV, 탐사로봇 등 폭넓은 분야에서 다양한 디지털 장비들이 보급되고 있다. 이에 데이터처리의 중요성이 커지고 있으며, 영상 분야에서도 데이터를 수신하는 과정에서 발생하는 잡음을 제거하기 위한 다양한 연구들이 진행되고 있다. 대표적인 잡음으로 AWGN(additive white Gaussian noise)이 있으며, 잡음을 제거하기 위한 기존의 필터로는 평균필터(AF : average filter), 알파 트림드 평균필터(A-TAF : alpha trimmed average filter), 메디안필터(MF : median filter) 등이 있다. 하지만 기존의 필터들은 고주파영역에서의 잡음 제거 특성이 다소 미흡한 성능을 보이는 단점이 있다. 따라서 본 논문에서는 고주파영역에 존재하는 AWGN을 효과적으로 제거하기 위해 표준편차를 기반한 거리에 따른 가중치필터를 제안한다.

• 한국자원식물학회지
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• 제33권1호
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• pp.33-39
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• 2020

본 연구는 동백나무의 대량번식 및 양묘를 위한 기초 정보를 제공하기 위하여 종자 무게와 저장방법에 따른 발아특성과 유묘생장을 조사하였다. 실온저장과 4℃건조저장의 발아율은 종자 무게에 따라 일정한 경향이 없었다. 4℃ 습윤모래저장의 발아율은 종자무게가 무거울수록 높아졌으나 저장 120일에 매우 낮은 발아율을 나타내었다. 4℃ 습윤여과지저장의 발아율은 60일, 90일, 120일 저장 모두 80% 이상으로 높았고, 종자 무게에 따른 발아율의 차이도 거의 나타나지 않았다. 평균발아일수는 실온저장과 건조저장에서 30일 내외의 긴 시간이 요구되었지만 습윤저장(모래, 여과지)은 13일 내외로서 짧았다. 엽수, 엽건물 중, 줄기직경, 뿌리건물중은 종자 무게 1.21 g 이상부터 평균치를 상회하였고, 줄기길이는 종자 무게 1.01 g, 식물체건물중은 종자 무게 0.81 g, 줄기건물중은 종자 무게 0.61 g부터 유묘의 평균치를 상회하였다. 유묘 생장은 종자 무게가 무거울수록 양호하였으며, T/R율은 종자가 무거울수록 낮아지는 경향이었다. 동백나무 유묘의 대량생산을 위해서는 종자 무게 및 크기를 구체화할 필요성이 있고, 파종을 위한 종자저장은 4℃ 습윤여과지저장이 가장 효율적인 방법으로 평가되었다.