• Title/Summary/Keyword: 재현 정확도

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A selective sparse coding based fast super-resolution method for a side-scan sonar image (선택적 sparse coding 기반 측면주사 소나 영상의 고속 초해상도 복원 알고리즘)

  • Park, Jaihyun;Yang, Cheoljong;Ku, Bonwha;Lee, Seungho;Kim, Seongil;Ko, Hanseok
    • The Journal of the Acoustical Society of Korea
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    • v.37 no.1
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    • pp.12-20
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    • 2018
  • Efforts have been made to reconstruct low-resolution underwater images to high-resolution ones by using the image SR (Super-Resolution) method, all to improve efficiency when acquiring side-scan sonar images. As side-scan sonar images are similar with the optical images with respect to exploiting 2-dimensional signals, conventional image restoration methods for optical images can be considered as a solution. One of the most typical super-resolution methods for optical image is a sparse coding and there are studies for verifying applicability of sparse coding method for underwater images by analyzing sparsity of underwater images. Sparse coding is a method that obtains recovered signal from input signal by linear combination of dictionary and sparse coefficients. However, it requires huge computational load to accurately estimate sparse coefficients. In this study, a sparse coding based underwater image super-resolution method is applied while a selective reconstruction method for object region is suggested to reduce the processing time. For this method, this paper proposes an edge detection and object and non object region classification method for underwater images and combine it with sparse coding based image super-resolution method. Effectiveness of the proposed method is verified by reducing the processing time for image reconstruction over 32 % while preserving same level of PSNR (Peak Signal-to-Noise Ratio) compared with conventional method.

Manikin Model Study on Reproducibility and Accuracy of Maxillofacial Measurements Determined by Stereocamera: Comparative Study of Direct Anthropometry, Digitizer and Stereophotogrammetery (스테레오 카메라를 이용한 안면부 측정의 재현성과 정확도에 대한 마네킨을 이용한 연구: 직접 인체계측, Digitizer, Stereophotogrammetry의 비교 연구)

  • Jeoung, Youn-Wook;Yang, Ji-Woong;Chung, Kwang;Kook, Min-Suk;Oh, Hee-Kyun
    • Maxillofacial Plastic and Reconstructive Surgery
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    • v.34 no.1
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    • pp.17-25
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    • 2012
  • Purpose: Recently, a three dimensional approach to hard and soft tissues of the maxillofacial area has been widely used. This study was to evaluate the reproducibility and accuracy of a stereocamera compared to actual measurement methods using a digital caliper and digitizer. Methods: The stereoscopies of 7 head dummies with different sizes and shapes were obtained using a Di3D system (Dimensional Imaging, Glasgow, UK) after marking reference points on facial areas. From the obtained stereoscopy, 10 measurements representing the width, height and depth of each of the facial sections of the dummy were measured twice using a three dimensional reverse engineering software program (RapidForm$^{TM}$ 2006, Inus, Seoul, Korea). The x, y, and z coordinates of each of the three dimensional measurements were obtained and distances between two points were calculated. All procedures were repeated twice. The actual measurement method was performed twice, directly on dummies, using a digital caliper and values were compared with the previously determined values. Results: The results were as follows. In the ANOVA analysis, there were no significant statistical differences among the three measurement methods. In the Bonferroni analysis, with adjustments applied for multiple comparisons, there was no difference between actual measurement methods using a digitizer and a digital caliper. However, there was some difference between using a stereocamera and actual measurement methods using a digitizer and a digital caliper in values of $Ex_{Rt}-Ex_{Lt}$, $En_{Rt}-En_{Lt}$, $Ala_{Rt}-Ala_{Lt}$, $Ch_{Rt}-Ch_{Lt}$, G-Pg', $Ala_{Rt}$-Prn, $Ala_{Rt}$-Prn. The mean value for technical error in measurement (TEM) in Di3D (0.98 mm) was slightly higher than for a digital caliper (0.17 mm) and a digitizer (0.30 mm). In an intraclass correlation coefficient (ICC) there were no significant differences among the three measurement methods, but the Di3D system with the stereocamera showed relatively lower reproducibility compared to actual measurement methods using a digitizer and a digital caliper. Conclusion: These results indicate that some complementary measures may be needed to improve accuracy and reproducibility in the Di3D system with stereocamera.

A Study on Fashion Design Using Geometric Pattern (기하학적 패턴을 활용한 패션디자인 연구)

  • 김신우;금기숙
    • Journal of the Korean Society of Costume
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    • v.52 no.1
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    • pp.53-67
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    • 2002
  • 자연을 분석함으로써, 얻어진 기하학적 패턴은 이미 자연의 질서를 포함하고 있는 논리적이고 합리적인 기본형이기 때문에 간결하며 시각적으로 명쾌감을 준다. 이러한 기하학적 패턴은 복식 디자인에 있어서 20 세기 이후 여러 디자이너의 작품을 통해 재구성되어 현대적 이미지를 나타내는 중요한 모티브가 되고 있으며, 다양한 기법과 재료로 형성화하여 도입되고 있다. 이에 본 연구는 복식의 문양, 실루엣, 디테일에 사용되고 있는 기하학적 패턴을 연구함으로써 기하학적 패턴의 새로운 조형가치를 고찰하였다. 먼저 기하학의 용어 정의를 하였고 기하학적 패턴의 유형과 표현 기법을 분석하고 정리하여 현대 패션에 나타난 기하학적 패턴의 조형미와 그것을 바탕으로 패션 이미지를 추론해 보았다. 현대 패션에 나타난 기하학 패턴을 분석해 보면 유형으로는 첫째, 기하하적 문양으로 복식디자인에 있어서 주로 평면적인 형태로 많이 나타나지만, 크기가 다르고 동일한 기하학적 패턴을 조합시킴으로서 평면적인 형태에 공간감을 부여하기도 하며, 같은 기하학적 패턴의 표면이라도 배치구조에 의해 직선 혹은 사선으로 지각되므로 전혀 다른 이미지를 주었다. 또한 현대 패션에 나타난 기하학적 패턴이 종류는 세로 스트라이프, 가로 스트라이프, 격자 문양, 원, 사선 스트라이프, 마름모, 사각형, 삼각형 등의 순서로 많이 나타났다. 둘째, 색채는 단색의 복식에 강한 대비가 이루어지는 색상으로 표현되어 역동감과 유연한 운동감을 나타났다. 셋째, 기하학적 실루엣으로 단순한 라인의 형태를 나타내거나 입체적이고 부조적인 형태로 구성되어 전체적인 실루엣으로 사용되어 강한 조형감각을 보여주는데 원형을 이용한 실루엣이 가장 많았으며 사각형을 이용한 실루엣, 삼각형을 이용한 실루엣 순서로 나타났다. 넷째, 기하학적인 디테일로 복식의 어느 한 부분에 장식적으로 사용되거나 입체적 형태로 부출 되어 부조적인 느낌을 주는데 소매에 가장 많이 나타났으며 앞여밈, 칼라, 밑단, 주머니 순서로 장식되었다. 다섯째, 현대 패션에 표현된 기하학적 패턴의 표현기법으로는 프린팅, 퀼팅, piece기법, 패치워크, 엮기, 꼴라쥬, 아플리케 순서로 많이 나타났다. 위의 분석을 토대로 기하학 패턴을 활용한 디자인에 내재된 조형의지는 다음과 같이 정리되었다. 첫째, 기하학적 패턴이 지닌 단순성과 경직성을 완화하기 위하여 여러 가지 패브릭을 조합시켜 입체적인 표면효과로 시각적인 착시효과를 극대화하였다. 둘째, 표현기법은 입체파적 표현주의의 특성의 하나로 복시에 사용되는 소재의 왜곡으로 설명할 수 있으며, 새롭고 실험적인 소재의 도입으로 인해 의외성과 부조화를 유발시키는 통시에 유희직인 일면도 지니는 일종의 그로테스크를 나타냈다. 이상에서 정립된 조형의지를 바탕으로 현대 패션에 나타란 기하학 패턴은 절제된 단순함과 명확성으로 단순미가 유추되었고 강한 색상대비로 인한 시각적 집중효과로 주목성을 가지며 재현이 가능하므로 반복성이 유추되었다. 그리고 표준영역이 없는 창의적 표현으로 풍부한 독창성을 보여주고 있다. 또한 내재된 패션 이미지를 분석해 보면 정확함과 차가움의 의미를 지닌 이지적 이미지와 우주의 질서를 반영하는 상징적 이미지, 복잡한 자연으로부터 간결한 형태로의 경향성이 이루어낸 인공적 이미지를 느낄 수 있었으며, 미래적 이미지와 전통적 이미지의 상반된 개념의 이미지를 같이 내포하고 있음을 추론할 수 있었다. 이와 같이 현대 패션에 표현된 기하학적 패턴은 복식을 조형예술 분야로 확실히 인식시키고 발전시키는 데 중요한 촉매제 역할을 담당하고 있으며 또한 많은 디자이너들에게 창조적 욕구를 불러일으키고 영감을 주는데 중요한 모티브를 제공하고 있다.

Application of Chiu's Two Dimensional Velocity Distribution Equations to Natural Rivers (Chiu가 제안한 2차원 유속분포식의 자연하천 적용성 분석)

  • Lee, Chan-Joo;Seo, Il-Won;Kim, Chang-Wan;Kim, Won
    • Journal of Korea Water Resources Association
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    • v.40 no.12
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    • pp.957-968
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    • 2007
  • It is essential to obtain accurate and highly reliable streamflow data for quantitative management for water resources. Thereafter such real-time streamflow gauging methods as ultrasonic flowmeter and index-velocity are introduced recently. Since these methods calculate flowrate through entire cross-section by measuring partial velocities of it, rational and theoretical basis are necessary for accurate estimation of discharge. The purpose of the present study lies in analysis on the applicability of Chiu#s(1987, 1988) two dimensional velocity distribution equations by applying them to natural rivers and by comparing simulated velocity distributions with observed ones obtained with ADCP. Maximum and mean velocities are calculated from observed data to estimate entropy parameter M. Such isovel shape parameters as h and $\beta_i$ are estimated by object function based on least squares criterion. In case optimized parameters are applied, Chiu#s velocity distributions fairly well simulate observed ones. By using 14 simulated data sets which have relatively high correlation coefficients, properties of parameters are analyzed and h, $\beta_i$ are estimated for velocity-unknown river sections. When estimated parameters are adopted for verification, simulated velocity distributions well reproduce real ones. Finally, calculated discharges display rough agreement with measured data. The results of the present study mean that if parameters related are properly estimated, Chiu#s velocity distribution is likely to reproduce the real one of natural rivers.

Anlaysis of the Effects Resulting from Hydraulic Structure on River Flow (수공구조물이 하천흐름에 미치는 영향분석)

  • Kwon, Taek-Hoon;Choi, Seung-Yong;Nam, Ki-Young;Han, Kun-Yeun
    • Proceedings of the Korea Water Resources Association Conference
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    • 2011.05a
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    • pp.164-164
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    • 2011
  • 우리나라는 하상의 평균경사가 급하고 하상계수가 크게 나타나며, 소하천에서의 돌발홍수가 빈발하게 일어나 국내 실정에 적합한 하천 해석 기술을 이용한 바람직한 하천 거동해석이 매우 중요하다고 할 수 있다. 홍수 시 하천의 만곡부나 협착부에서의 흐름은 기본적으로 2차원 흐름으로 서 이 경우 하천 흐름의 수위와 유속 분포는 1차원 하천 모형으로 모의할 수 없다. 특히 우리나라와 같이 하천에 하구둑, 보, 기타 하천 구조물이 많은 경우에는 2차원적인 흐름 해석은 경우에 따라 필수적이다. 본 연구에서는 개발모형인 RAM2 모형을 4대강 살리기 사업이 진행되고 있는 실제유역인 낙동강유역에 적용하여 모형의 적용성을 검증을 위해 그 결과를 실측치와 기존의 법용 프로그램인 RMA-2 모형과 비교하여 모형의 적용성을 입증하였다. 또한 보와 교각과 같은 수공구조물의 설치에 따른 하천흐름의 양상을 파악하기 위하여 RAM2 모형을 달성보 구간에 적용하여 보의 설치 전 후에 대하여 모의를 실시함으로써 모형의 적용성을 입증하였다. 본 연구에 적용된 달성보 구간은 낙동강 살리기 22공구 사업구간으로 중심부에 다기능보가 위치하고 있다. 하천 준설 후, 대상구간 내 보를 설치함으로 인하여 보설치 전 후의 대상구간의 상 하류 하도의 홍수위와 유속분포 등 하천흐름의 양상을 검토하였다. 4대강 살리기 사업에 따라 실제하천의 준설 후 구간내의 전체하도 및 주요 시설물 주위의 하천 흐름을 정확하게 재현하기 위하여 요소망을 조밀하게 구성하고, 안정적인 해를 구하기 위하여 사각형과 삼각형의 복합망으로 낙동강하천정비계획의 측량자료와 GIS프로그램과 SMS를 이용하여 수치모형을 위한 2차원 유한요소망을 구성하였다. 본 연구에서는 보설치 전 후의 대상구간의 상 하류의 홍수위 영향과 유속분포 등 하천흐름의 양상을 연구하기 위하여 대상구간에 대하여 100년 빈도, 500년 빈도의 홍수사상에 대하여 모의를 실시하고 결과를 분석하였다. 하천에서의 흐름, 유사, 오염물 해석을 위한 2차원 유한요소모형은 수자원의 지속적 확보기술의 초석이 될 뿐만 아니라, 필요에 따라서는 하천생태계 보존 및 관리를 위해서도 적용될 수 있어, 수생태계 개선과 친수환경 조성에 크게 기여할 수 있겠다. 또한 하천에서의 흐름, 유사, 오염물 해석을 위한 2차원 유한요소모형을 활용하여 적절한 하천개발 및 관리가 이루어질 경우, 하천의 홍수, 갈수, 환경오염에 따른 사회적인 손실을 방지할 수 있을 것이다.

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Structural Analysis of Power Transmission Mechanism of Electro-Mechanical Brake Device for High Speed Train (고속열차용 전기기계식 제동장치의 동력전달 기구물에 대한 구조해석)

  • Oh, Hyuck Keun;Beak, Seung-Koo;Jeon, Chang-Sung
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.20 no.12
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    • pp.237-246
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    • 2019
  • The Electro-Mechanical Brake (EMB) is the next generation braking system for automobiles and railway vehicles. Current brake systems for high-speed trains generate a braking force using a pneumatic cylinder, but EMB systems produce that force through a combination of an electric motor and a gear. In this study, an EMB operation mechanism capable of generating a high braking force was proposed, and structural and vibration analyses of the gears and shafts, which are the core parts of the mechanisms, were performed. Dynamic structural analysis confirmed that the maximum stress in the analysis model was within the yield strength of the material. In addition, the design that maximizes the diameter of the motor shaft was found to be advantageous in strength, and large shear stress could be generated in the bolt fixing the gear and eccentric shaft. In addition, a test apparatus that can reproduce the mechanism of the analytical model was fabricated to measure the strain of the fixed bolt part, which is the most vulnerable part. The strain measurement results showed that the error between the analysis and measurement was within 10%, which could verify the accuracy of the analytical model.

Optical Fiber-Based Hybrid Nerve Measurement System for Static and Dynamic Behavior of Structures (구조물의 정적 및 동적 거동 모니터링을 위한 광섬유 기반 하이브리드 신경망 계측 시스템)

  • Park, Young-Soo;Song, Kwang-Yong;Jin, Seung-Seop;Park, Young-Hwan;Kim, Sung-Tae
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.24 no.2
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    • pp.33-40
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    • 2020
  • Various studies have been conducted on the structural health monitoring using optical fiber. Optical fibers can be used to measure multiple and distributed strain. Among the optical fiber sensors, FBG sensor has advantages of dynamic response measurement and high precision, but the number of measurement points is limited. Distributed fiber sensors, represented by distributed Brillouin sensors, usually have more than 1000 measurement points, but the low sampling rate makes dynamic measurements impossible. In this study, a hybrid nerve sensor system using only the advantages of the FBG sensor and the distributed Brillouin sensor has been proposed. Laboratory experiments were performed to verify the proposed system, and the accuracy and reproducibility were verified by comparing with commercial sensors. Applying the proposed system, dynamic response ambient measurements are used to evaluate the global state of the structure. When an abnormal condition is detected, the local condition of the structure is evaluated by static response measurement using the distributed measurement system. The proposed system can be used for efficient structural health monitoring.

Re-establishing the Antecedent Moisture Condition of NRCS-CN Method Considering Rainfall-Runoff Characteristics in Watershed Based on Antecedent 5-Day Rainfall (유역의 강우-유출 특성을 고려한 NRCS-CN 방법의 선행토양함수조건의 재설정: 선행5일강우량을 기준으로)

  • Yoo, Ji-Young;Moon, Geon-Woo;Ahn, Jae-Hyun;Kim, Tae-Woong
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.34 no.3
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    • pp.849-858
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    • 2014
  • The mount of antecedent 5-day rainfall (P5) is usually used to determine the antecedent soil moisture condition for estimating effective rainfall using the NRCS-CN method. In order to re-establish the threshold of P5 considering basin characteristics, this study investigated the sensitivity of the threshold of P5 to effective rainfall by comparing the corresponding observed direct runoff. The overall results indicate that the direct runoff estimated using the re-establihed threshold of P5 has smaller mean error (RMSE of 27.3 mm) than those using the conventional threshold (RMSE of 35.2 mm). In addition, after evaluating the effectiveness of threshold of P5 using the improvement index, the threshold re-established in this study improved the ability to estimate the direct runoff by 30% on average. This study also suggested to employ regression models using topographic indices to re-establish the threshold for ungauged basins. When using the re-established threshold from the regression model, the RMSE decreased ranging from 0.4 mm to 15.1 mm and the efficiency index of Nash and Sutcliffe increased up to 0.33.

Analysis of Endotoxin Using Analytical Conditions of Optical Density in Metalworking Fluid Sample (금속가공유 시료에서 일부 Optical Density 설정값에 따른 엔도톡신의 정량)

  • Park, Dong-Uk;Han, In-Young;Yoon, Chung-Sik;Park, Doo-Yong
    • Analytical Science and Technology
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    • v.15 no.5
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    • pp.459-465
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    • 2002
  • This study was performed to identify the proper analytical conditions of endotoxins regarding optical density in the workplace where metalworking fluids are used. This study found that "onset time method" was more accurate than "time to $V_{max}$ method". Reproducibility and accuracy analyzed by "onset time method" was greatly higher than the "time to $V_{max}$". The optical density of "0.03" was the most appropriate analytical condition among "onset time method". In this analytical condition, linearity of 0.998 was obtained and recovery rate ranged from 88% to 105% at the endotoxin concentrations below 5 EU/mL. No significant difference of endotoxins was observed between the optical densities of "0.03" and "0.05". However, correlation coefficients were different with statistical significance (p<0.01). This study confirmed that either the optical densities "0.03" or "0.05" should be used to analyze endotoxin. Of these optical density values, OD with correlation coefficient higher than 0.98 should be used to analyze endotoxin in environmental samples.

Computation of Tides in the Northeast Asian Sea by Blending the Topex/Poseidon Altimeter Data (Topex/Poseidon 고도계 자료를 이용한 북동 아시아 해역의 조석 산정)

  • Kim, Chang-Shik;Matsumoto, Koji;Ooe, Masatsugu;Lee, Jong-Chan
    • The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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    • v.6 no.1
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    • pp.1-12
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    • 2001
  • Tidal computations of $M_2,\;S_2,\; K_1$ and $O_1$ constituents in the northeast Asian sea are presented by blending the Topex/Poseidon (T/P) altimeter data into a hydrodynamic model with $5'{\times}5'$ resolution. A series of sensitivity experiments on a weighting factor, which is the control parameter in the blending method, are carried out using $M_2$ constituent. The weighting factor is set to be in inverse proportion to the square root of water depth to reduce noises which could occur in data-assimilative model by blending T/P data. Model results obtained by blending the T/P-derived $M_2,\;S_2,\; K_1$ and $O_1$ constituents simultaneously are compared with all T/P-track tidal data; Average values of amplitude and phase errors are close to zero. Standard deviations of amplitude and phase errors are approximately 2 cm and less than 10 degrees respectively. The data-assimilative model results show a quite good agreement with T/P-derived tidal data, particularly in shallow water region (h<250m). In deep water regions, T/P-derived tidal data show unreasonable spatial variations in amplitude and phase. The data-assimilative model results differ from T/P-derived data, but are improved to show reasonable spatial variations in amplitude and phase. In addition, the T/P-blended model results are in good agreement with coastal tide gauge data which are not blended into the model.

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