• 한국측량학회지
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• 제30권1호
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• pp.39-48
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• 2012

수치표고모델(DEM : Digital Elevation Model)을 생성하거나 지상의 객체를 추출하기 위해서 라이다 자료에서 지면점과 비지면점을 분리하는 필터링(filtering) 과정은 중요하다. 본 연구에서는 라이다 자료에서 지면점을 추출하는 데 사용되는 기존의 필터링 방법을 대상으로 정성적 분석과 정량적 분석을 통해 가장 효과적인 필터링 알고리즘을 선정하는 것을 목적으로 하였다. 이를 위해 Adaptive TIN, Perspective Center Based Filtering Algorithm, Elevation Threshold with Expand Window, Progressive Morphology의 4가지 필터링 방법을 산악지역, 도시지역, 건물과 산이 공존하는 3가지 지역에 적용하여 각각의 방법에 대한 특징을 분석하였다. 실험에 사용된 4가지 필터링 방법의 정성적인 비교는 음영기복도를 생성한 후 시각적인 방법을 적용하였고 정량적인 비교는 GPS로 관측한 검사점을 이용한 절대적인 비교와 국토지리정보원의 수치표고모델을 이용하여 상대적인 비교를 수행하였다. 라이다 필터링 실험을 통하여 Adaptive TIN 알고리즘은 산악지역과 도시지역에서 지면점을 가장 효율적으로 추출하였고 건물과 산이 공존하는 지역에서는 Progressive Morphology 알고리즘이 가장 양호한 결과를 나타내었다. 또한 정성적, 정량적 비교 결과 전반적으로 지역적 특성에 관계없이 적용가능한 필터링 알고리즘은 ATIN 알고리즘으로 나타났다.

• 한국환경과학회지
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• 제17권10호
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• pp.1147-1154
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• 2008

Road runoff, one of non-point source pollutants, contains various heavy metals, most of which flow into discharge waters without being treated. The mechanism of removing the heavy metals in water is similar to that of removing micro-particles. Therefore, it is considered that it is possible to remove a lot of the heavy metals contained in the road runoff by filtering or absorbing them. In this paper, performed has been a basic study on the characteristics of UNFS (Up Flow Non-Point Source Filtering System) using carbide pellet and zeolite pellet as double-layer filtering mediums to treat the road runoff. The removal rate with filtering and absorption time has been shown as follows: 29.0% for Cr; 27.8% for Cd; 25.7% for Fe; 25.4% for Co; 21.2% for Pb; ]9.6% for Zn; 18.2% for Al; 17.0% for Mn; 11.3% for Ni; 7.5% for Cu. The overall removal rate according to influx change has been shown to be approximately 30%, and the load of heavy metals flowing out in initial precipitation could be reduced by using carbide as a recycling filtering medium. When the removal as coarse particles settle is added up, it is expected that UNFS will result in a higher removal rate.

• 한국콘텐츠학회:학술대회논문집
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• 한국콘텐츠학회 2009년도 춘계 종합학술대회 논문집
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• pp.648-651
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• 2009

다양한 통신시스템 설계에 사용되는 다중 스텁 도파관 구조가 주파수 필터링 특성을 가진 것을 모드정합법을 이용해 보인다. 주파수 필터링 특성을 가진 다중 스텁 도파관 구조의 통과 대역과 차단 대역을 자동으로 설계하기 위해 적합도 함수를 정의하고 유전 알고리즘으로 구현 가능함을 보인다. 스텁 도파관 구조가 주파수 필터링 특성을 가진 것을 수치해석적으로 보이고 다양한 매개변수에 대한 특성변화를 관찰한다.

• Journal of electromagnetic engineering and science
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• 제5권3호
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• pp.140-145
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• 2005

In this paper, an experimental investigation for return loss and a software-based prediction for interference level of single-packaged filtering antenna composed of dielectric waveguide filter and PCB(Printed Circuit Board) slot antenna in transceiver module have been carried out with several different feeding structures in millimeter-wave regime. The implementation and embedding method of the existing air-filled waveguide filters working at millimeter-wave frequency on general PCB substrate have been described. In a view of the implementation of each components, the dielectric waveguide embedded in PCB and LTCC(Low Temparature Co-fired Ceramic) substrates has employed the via fences as a replacement with side walls and common ground plane to prevent energy leakage. The characteristics of several prototypes of filtering antenna embedded in PCB substrate are considered by comparing the wideband and transmission characteristics as a function of bent angle of transmission line connecting two components. In addition, as an essential to the packaging of transceiver module working at millimeter-wave, miniaturization technology maintaining the performances of independent components and the important problems caused by integrating and connecting the different components in different layers are described in this paper.

• 한국방사선학회논문지
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• 제2권4호
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• pp.33-40
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• 2008

의료영상 시스템을 통해 볼 수 있는 모든 X-선 영상은 피사체 본래의 특성만이 표현된 영상이 아닌 그 영상시스템 고유의 특성이 반영된 영상이라 할 수 있다. 영상화질에서 시스템에 의한 열화는 시스템응답함수인 변조전달 함수(modulation transfer function; MTF)로 설명되며 잡음력 스펙트럼(noise power spectrum; NPS)으로 설명할 수 있다. 이 때, 열화된 영상은 영상시스템의 MTF와 NPS를 정확하게 측정함으로써 그 시스템의 특성에 따라 설계된 필터에 의해 원영상에 가깝게 복원(restoration)될 수 있다. 본 논문에서는, 영상복원 시뮬레이션을 통해 기존의 직접 역필터링(direct-inverse filtering), 제한된 역필터링(limited-inverse filtering), 위너 필터링(Wiener filtering) 기법을 바탕으로 열화된 영상을 원 영상에 가깝도록 복원하고 복원영상의 화질을 정량적으로 평가하였다.

• Journal of applied mathematics & informatics
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• 제28권1_2호
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• pp.439-450
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• 2010

In this paper, we propose a new idea to evaluate the prediction accuracy of user's preference generated by memory-based collaborative filtering algorithm before prediction process in the recommender system. Our analysis results show the possibility of a pre-evaluation before the prediction process of users' preference of item's transaction on the web. Classification functions proposed in this study generate a user's rating pattern under certain conditions. In this research, we test whether classification functions select users who have lower prediction or higher prediction performance under collaborative filtering recommendation approach. The statistical test results will be based on the differences of the prediction accuracy of each user group which are classified by classification functions using the generative probability of specific rating. The characteristics of rating patterns of classified users will also be presented.

• 말소리와 음성과학
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• 제2권1호
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• pp.77-85
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• 2010

This paper proposes an efficient feature vector processing technique to guard the Speech Emotion Recognition (SER) system against a variety of noises. In the proposed approach, emotional feature vectors are extracted from speech processed by comb filtering. Then, these extracts are used in a robust model construction based on feature vector classification. We modify conventional comb filtering by using speech presence probability to minimize drawbacks due to incorrect pitch estimation under background noise conditions. The modified comb filtering can correctly enhance the harmonics, which is an important factor used in SER. Feature vector classification technique categorizes feature vectors into either discriminative vectors or non-discriminative vectors based on a log-likelihood criterion. This method can successfully select the discriminative vectors while preserving correct emotional characteristics. Thus, robust emotion models can be constructed by only using such discriminative vectors. On SER experiment using an emotional speech corpus contaminated by various noises, our approach exhibited superior performance to the baseline system.

• 전자공학회논문지B
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• 제33B권8호
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• pp.60-67
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• 1996

In this paper, we propose a new temporal interpolation method based on spatial filtering. Compared with the conventional method, the proposed one may use a few adjacent frames and apply temporal lowpass filtering. To develop this method, we follow the basic approach of sampling rate conversion. Additionally, we use some assumption of video sequence : moving object has constant velocity rigid translational motion. From them, spatial filtering for temporal sampling rate conversion is described. This method has a lot of noise immunity on a motion vector and doesn't make a great difference from the original frame. The interpolated frame shows moderate change even there is a great time difference. This method has exactly same description of motion adaptive spatial filter which has an efficient temporal band-limiting characteristics. It imposes the possibility to make video sequence with good pictural quality.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 추계학술대회 논문집 학회본부 B
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• pp.481-483
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• 1998

In general, spatial filtering method was proposed to simplify measurement system through parallel Processing hardware. Spatial filtering is a method of detection that we can get a spatial pattern information, as we process a special space pattern, to say, as we process spatial parallel process by using the spatial weighting function. The important processing characteristics will be depended in according to how ire design a spatial weighting function, a spatial sensitive distribution. The form of the weighting function which is realized from the generally used spatial filtering is fixed and the weighting value was already became a binary-value. In this paper, we propose a new method in order to construct adaptive measurement systems. This method is a weighting function design to make multi-valued and variable.

• 한국컴퓨터정보학회논문지
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• 제21권11호
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• pp.121-126
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• 2016

In recommender systems based on collaborative filtering, measuring similarity is very critical for determining the range of recommenders. Data sparsity problem is fundamental in collaborative filtering systems, which is partly solved by Jaccard coefficient combined with traditional similarity measures. This study proposes a new coefficient for improving performance of Jaccard coefficient by compensating for its drawbacks. We conducted experiments using datasets of various characteristics for performance analysis. As a result of comparison between the proposed and the similarity metric of Pearson correlation widely used up to date, it is found that the two metrics yielded competitive performance on a dense dataset while the proposed showed much better performance on a sparser dataset. Also, the result of comparing the proposed with Jaccard coefficient showed that the proposed yielded far better performance as the dataset is denser. Overall, the proposed coefficient demonstrated the best prediction and recommendation performance among the experimented metrics.