• Journal of Information Processing Systems
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• 제13권5호
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• pp.1183-1202
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• 2017

Image restoration has been carried out by texture synthesis mostly for large regions and inpainting algorithms for small cracks in images. In this paper, we propose a new approach that allows for the simultaneous fill-in of different structures and textures by processing in a wavelet domain. A combination of structure inpainting and patch-based texture synthesis is carried out, which is known as patch-based inpainting, for filling and updating the target region. The wavelet transform is used for its very good multiresolution capabilities. The proposed algorithm uses the wavelet domain subbands to resolve the structure and texture components in smooth approximation and high frequency structural details. The subbands are processed separately by the prioritized patch-based inpainting with isophote energy driven texture synthesis at the core. The algorithm automatically estimates the wavelet coefficients of the target regions of various subbands using optimized patches from the surrounding DWT coefficients. The suggested performance improvement drastically improves execution speed over the existing algorithm. The proposed patch optimization strategy improves the quality of the fill. The fill-in is done with higher priority to structures and isophotes arriving at target boundaries. The effectiveness of the algorithm is demonstrated with natural and textured images with varying textural complexions.

• 말소리와 음성과학
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• 제13권3호
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• pp.21-29
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• 2021

The present study investigated how one's cognitive resources are related to speech perception by examining Korean speakers' executive function (EF) capacity and its association with voice onset time (VOT) and f0 sensitivity in identifying Korean stop laryngeal categories (/t'/ vs. /t/ vs. /t^h/). Previously, Kong et al. (under revision) reported that Korean listeners (N = 154) in Seoul and Changwon (Gyeongsang) showed differential group patterns in dialect-specific cue weightings across educational institutions (college, high school, and elementary school). We follow up this study by further relating their EF control (working memory, mental flexibility, and inhibition) to their speech perception patterns to examine whether better cognitive ability would control attention to multiple acoustic dimensions. Partial correlation analyses revealed that better EFs in Korean listeners were associated with greater sensitivity to available acoustic details and with greater suppression of irrelevant acoustic information across subgroups, although only a small set of EF components turned out to be relevant. Unlike Seoul participants, Gyeongsang listeners' f0 use was not correlated with any EF task scores, reflecting dialect-specific cue primacy using f0 as a secondary cue. The findings confirm the link between speech perception and general cognitive ability, providing experimental evidence from Korean listeners.

• Nuclear Engineering and Technology
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• 제53권3호
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• pp.699-714
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• 2021

Supercritical CO₂ (S-CO₂) Brayton cycle has been applied to various heat sources in recent decades, owing to the characteristics of compact structure and high efficiency. Understanding the research development in this emerging research field is crucial for future study. Thus, a bibliometric approach is employed to analyze the scientific publications of S-CO₂ cycle field from 2000 to 2019. In Scopus database, there were totally 724 publications from 1378 authors and 543 institutes, which were distributed over 55 countries. Based on the software-BibExcel, these publications were analyzed from various aspects, such as major research areas, affiliations and keyword occurrence frequency. Furthermore, parameters such as citations, hot articles were also employed to evaluate the research output of productive countries, institutes and authors. The analysis showed that each paper has been cited 13.39 times averagely. United States was identified as the leading country in S-CO₂ research followed by China and South Korea. Based on the contents of publications, existing researches on S-CO₂ are briefly reviewed from the five aspects, namely application, cycle configurations and modeling, CO₂-based mixtures, system components, and experiments. Future development is suggested to accelerate the commercialization of S-CO₂ power system.

• Journal of Astronomy and Space Sciences
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• 제37권4호
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• pp.219-228
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• 2020

A CubeSat platform has become a popular choice due to inexpensive commercial off-the-shelf (COTS) components and low launch cost. However, it requires more power-efficient and higher-data rate downlink capability for space applications related to remote sensing. In addition, the platform is limited by the size, weight and power (SWaP) constraints as well as the regulatory issue of licensing the radio frequency (RF) spectrum. The requirements and limitations have put optical communications on promising alternatives to RF communications for a CubeSat platform, owing to the power efficiency and high data rate as well as the license free spectrum. In this study, we analyzed the performance of optical downlink communications compatible with CubeSat platforms in terms of data rate, bit error rate (BER) and outage probability. Mathematical models of BER and outage probability were derived based on not only the log-normal model of atmospheric turbulence but also a transmitter with a finite extinction ratio. Given the fixed slot width, the optimal guard time and modulation orders were chosen to achieve the target data rate. And the two performance metrics, BER and outage data rate, were analyzed and discussed with respect to beam divergence angle, scintillation index and zenith angle.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2007년도 추계학술발표대회
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• pp.113-116
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• 2007

In this paper, our proposed Nonlinear Autoregressive Exogenous (NARX) based on Least Square-Support Vector Regression (LS-SVR) is introduced and tested for producing natural sounds. This nonlinear synthesizer perfectly reproduce voiced sounds, and also conserve the naturalness such as jitter and shimmer, compared to LPC does not keep these naturalness. However, the results of some phonation are quite different from the original sounds. These results are assumed that single-band model can not afford to control and decompose the high frequency components. Therefore multi-band model with wavelet filterbank is adopted for substituting single band model. As a results, multi-band model results in improved stability. Finally, nonlinear speech modeling using NARX based on LS-SVR can successfully reconstruct synthesized sounds nearly similar to original voiced sounds.

• Wind and Structures
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• 제38권1호
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• pp.75-91
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• 2024

Reliable wind signal reconstruction can be beneficial to the operational safety of long-span bridges. Non-Gaussian characteristics of wind signals make the reconstruction process challenging. In this paper, non-Gaussian wind signals are converted into a combined prediction of two kinds of features, actual wind speeds and wind angles of attack. First, two decomposition techniques, empirical mode decomposition (EMD) and variational mode decomposition (VMD), are introduced to decompose wind signals into intrinsic mode functions (IMFs) to reduce the randomness of wind signals. Their principles and applicability are also discussed. Then, four artificial intelligence (AI) algorithms are utilized for wind signal reconstruction by combining the particle swarm optimization (PSO) algorithm with back propagation neural network (BPNN), support vector regression (SVR), long short-term memory (LSTM) and bidirectional long short-term memory (Bi-LSTM), respectively. Measured wind signals from a bridge site in a deep-cutting gorge are taken as experimental subjects. The results showed that the reconstruction error of high-frequency components of EMD is too large. On the contrary, VMD fully extracts the multiscale rules of the signal, reduces the component complexity. The combination of VMD-PSO-Bi-LSTM is demonstrated to be the most effective among all hybrid models.

• Advances in concrete construction
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• 제16권4호
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• pp.189-203
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• 2023

This study investigates the bending and stability properties of cylindrical constructions, with a focus on their use in the design and implementation of sporting equipment. The work focuses on a cylindrical construction resembling nanomotors, similar to components seen in sports equipment, using mathematical modeling based on high-order beam theory and nonlocal strain gradient theory. The analysis provides important insights into the dynamic behavior of these systems, revealing light on the impact of numerous factors such as rotational velocity, section change rate, and structural dimensions. The results show a relationship between angular velocity growth and section change rate, which leads to an increase in fundamental frequency values. Furthermore, the research emphasizes the effect of structural factors on dynamic deflection, giving critical information for increasing the stability and performance of sporting equipment. This study adds to the area of sports engineering by providing a more nuanced understanding of how cylindrical constructions react under diverse settings. The results will help to guide the design and manufacturing processes of sports equipment, assuring improved stability and performance for players across a wide range of sports.

• International Journal of Computer Science & Network Security
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• 제24권7호
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• pp.1-10
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• 2024

Software architecture are High-level design decisions shaping a software system's components, structure, and interactions. It can be a blueprint for development, evolution, and ongoing maintenance. This research investigates the communication practices employed by software architects and developers to ensure adherence to the designed software architecture. It explores the factors influencing the selection of follow-up methods and the impact of follow-up frequency on successful implementation. Findings reveal that formalized follow-up procedures are not yet a ubiquitous element within the software development lifecycle. While electronic communication, particularly email, appears to be the preferred method for both architects and developers, physical and online meetings are utilized less frequently. Interestingly, the study suggests a potential confidence gap, with architects expressing concerns about developers' ability to faithfully implement the architecture. This may lead to architects providing additional clarification. Conversely, while most developers reported confidence in their software knowledge, overly detailed architecture documentation may pose challenges, highlighting the need for architects to consider alternative communication strategies. A key limitation of this study is the sample size, restricting the generalizability of the conclusions. However, the research offers valuable preliminary insights into the communication practices employed for architecture implementation, paving the way for further investigation with a larger and more diverse participant pool.

• 한국과학교육학회지
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• 제35권5호
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• pp.919-929
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• 2015

본 연구에서는 지질구조에 대한 모델링기반 학습 프로그램을 개발하고 모델링기반 학습에서 나타나는 논증패턴과 학생들의 정신모형 수준과의 관계를 밝히고자 하였다. 고등학교 2학년 126명을 대상으로 대륙이동설, 해령, 변환단층, 단층의 특징에 대하여 4회의 모델링기반 학습을 실시하였다. 연구대상 중에서 2개 학급은 실험집단으로 모델링기반 학습을 실시하였고 나머지 2개 학급은 비교집단으로 교사중심 설명식 수업을 실시하였다. 모델링기반 학습 후 실험집단과 비교집단의 사후 성취도와 학생들의 정신모형 분포를 정량적으로 비교하였다. 실험집단 중 5개 조의 논증활동을 녹음 전사한 자료에 대하여 본 연구에서 설정한 분석틀을 근거로 정성적으로 분석하였다. 본 연구의 분석틀은 TAP의 5가지 요소와 학생들의 대안개념이 포함되는 요소 5가지 등 총 10가지의 코딩 요소로 구성하였다. 정신모형 유형을 조사한 결과, 실험집단에서 단면 인과모형과 입체형 모형의 비율이 높게 나타난 반면, 비교집단에서는 2차원 모형과 단면 단순모형의 비중이 높게 나타났다. 논증유형을 분석한 결과, 주장의 빈도가 높을수록 논증활동이 성공적으로 이루어졌고 정신모형의 수준이 높게 나타났다. 반박이 제기된 경우, 만든 모형을 다시 관찰하여 자료를 수정하고, 이에 따라 주장을 다시 전개하였다. 이로써 모델링기반 학습에서 모형이 학생들의 논증 과정에 긍정적으로 작용함을 확인할 수 있었다.

• 한국전자파학회논문지
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• 제20권9호
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• pp.974-982
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• 2009

주파수 안정성 이 우수한 밀리미터파 및 테라헤르츠파 대역 연속파(Continuous Wave: CW) 신호를 발생시키기 위하여 상관관계가 큰 서로 다른 두 파장의 광 신호를 비팅(beating) 시켜 광 혼합(photomixing) 방법에 관한 많은 연구가 진행되고 있다. 광 반송파가 억압된 양측 대역(Double Sideband-Suppressed Carrier: DSB-SC) 방식은 단일 파장 광 신호를 국부 발진기와 광 변조기를 이용하여 CW 변조함으로써 상관관계가 큰 서로 다른 두 파장의 광 신호를 생성하는 방법이다. 본 논문에서는 DSB-SC를 이용한 광 혼합 밀리미터파 및 테라헤르츠파 대역 CW신호 발생 방법에서 광 반송파 억압 레벨에 따른 밀리미터파 및 테라헤르츠파 대역 CW 신호의 파워 및 위상 잡음 특성을 수치적으로 분석하고 실험적으로 증명하였다. 측정 결과, 광 반송파의 억압 레벨에 따라서 밀리미터파 및 테라헤르츠파 대역 CW 신호의 파워와 위상 잡음이 각각 23.9 dB와 21 dBc/Hz(@ 1 MHz offset frequency) 개선됨을 확인하였다. DSB-SC 방법을 다룬 기존 문헌에서는 직관적으로 광 반송파 억제 레벨을 중요성을 언급하였으나, 본 논문에서는 수식 및 측정 데이터에 기반한 밀리미터파 및 테라헤르츠파 대역 CW신호의 특성 향상을 위한 광 반송파 억제 레벨의 중요성을 확인하였다. 따라서 본 논문의 결과는 광 혼합 방법을 이용한 밀리미터파 및 테라헤르츠파 대역 CW 신호 발생 연구를 위한 기본적인 데이터로서 활용 가치가 높다.