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집합 유사 시퀀스 매칭의 성능 향상을 위한 인덱스 기반 검색 방법
이주원,임효상,Lee, Juwon,Lim, Hyo-Sang 한국정보처리학회 2017 정보처리학회논문지. 소프트웨어 및 데이터 공학 Vol.6 No.11
집합 유사 시퀀스 매칭 방법은 유사한 정도를 나타내는 척도로 교집합을 기반으로 한 유사도를 사용한다. 그러나 교집합 크기를 계산하는 과정에 시간이 오래 걸릴 뿐만 아니라, 유사한 시퀀스를 찾기 위해서 수많은 집합 간 교집합 크기를 구해야 하므로 수행 시간이 오래 걸리는 성능상의 문제가 있다. 본 논문에서는 이러한 성능상의 문제를 해결하기 위해 인덱스 기반의 검색 방법을 사용하여 집합 기반 유사 시퀀스 매칭을 빠르게 수행하는 방법을 제안한다. 제안하는 방법은 크게 두가지로 구분된다. 첫 번째로 집합 시퀀스 유사도 문제를 교집합의 크기 비교 문제로 정형적으로 변환하고, 교집합의 크기를 빠르게 찾을 수 있는 인덱스 구조를 제안한다. 두 번째로 제안한 인덱스 구조를 사용하여 집합 기반 유사 시퀀스 매칭을 효율적으로 수행할 수 있는 방법을 제안한다. 성능 평가 결과, 제안하는 방법이 기존 방법에 비해 최대 30배에서 50배의 수행 시간 단축이 있음을 보인다. 또한 데이터 시퀀스의 개수가 증가할수록 수행시간의 차이가 점점 커지므로, 대용량 데이터 처리에 적절함을 보인다. The set-based similar sequence matching method measures similarity not for an individual data item but for a set grouping multiple data items. In the method, the similarity of two sets is represented as the size of intersection between them. However, there is a critical performances issue for the method in twofold: 1) calculating intersection size is a time consuming process, and 2) the number of set pairs that should be calculated the intersection size is quite large. In this paper, we propose an index-based search method for improving performance of set-based similar sequence matching in order to solve these performance issues. Our method consists of two parts. In the first part, we convert the set similarity problem into the intersection size comparison problem, and then, provide an index structure that accelerates the intersection size calculation. Second, we propose an efficient set-based similar sequence matching method which exploits the proposed index structure. Through experiments, we show that the proposed method reduces the execution time by 30 to 50 times then the existing methods. We also show that the proposed method has scalability since the performance gap becomes larger as the number of data sequences increases.
수치해석과 모형실험을 통한 매립배관에서의 유도초음파 감쇠 분석 및 예측
이주원(Juwon Lee),나원배(Won-Bae Na),신성우(Sung-Woo Shin) 대한조선학회 2012 대한조선학회 학술대회자료집 Vol.2012 No.5
In this paper, we analyze guided waves attenuation that propagates on buried steel pipe. For the investigation, we performed numerical analysis and model experiment. Soil properties of numerical analysis were decided by soil model, determined by the degree of saturation. From the attenuation dispersion curves, obtained from DISPERSE, we decide excitation mode of model experiment. For the attenuation of model experiment, embedment length and existence of soil moisture were considered. From the results, it is shown that numerical result has higher attenuation that the experimental result. In addition, we found that linear extrapolation predicts higher attenuation than exponential extrapolation.
매립배관에서 전파되는 유도초음파 특성 분석을 위한 기초실험
이주원(Juwon Lee),신성우(Sung Woo Shin),나원배(Won-Bae Na) 대한조선학회 2011 대한조선학회 학술대회자료집 Vol.2011 No.6
This study investigates the effect of buried conditions on signal intensity of guided waves. Excitation mode and frequency were selected using dispersion curve analysis of guided waves modes. Guided waves were generated by the angle beam probe method and the signals were excited and received through the pitch-catch method. For the investigation, buried length and soil condition were considered as experiment parameters. The signal from unburied pipe was decided as an criterion and compared with other signals from buried conditions. From the experimental results, it is shown that the signal intensities of guided waves are largely affected by the buried length and soil condition.
주변 흙의 특성이 물이 찬 매립된 배관에서 전파되는 기본 유도 종파 모드 감쇠에 미치는 영향
이주원(Juwon Lee),나원배(Won-Bae Na),신성우(Sung Woo Shin),김재민(Jae-Min Kim) 한국해양공학회 2010 韓國海洋工學會誌 Vol.24 No.4
This study presents the attenuation characteristics of the first guided longitudinal wave mode propagating in water-filled, buried steel pipes in order to investigate the effects of soil saturation and compaction on the attenuation patterns. For numerical calculation of attenuation, 10 different combinations of S-wave velocity, P-wave velocity, and soil densities were considered. From the attenuation dispersion curves, which were obtained using Disperse software, we determined that the attenuation decreases as saturation increases, whereas it increases as compaction increases. Over the frequency range from 0.2 to 0.4 ㎒, the first longitudinal wave mode has attenuations that are relatively lower than for other ranges, is faster than the first flexural wave mode, and is sensitive to defects aligned in the axial direction. Hence, the first longitudinal wave mode over the mentioned frequency range would be the proper choice for long-range buried pipelines that transport water.