• 한국콘텐츠학회논문지
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• 제19권7호
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• pp.427-435
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• 2019

사운드스케이프(soundscape)는 소리를 통해 문화와 환경, 사회적 변화를 이해하는데 중요한 역할을 하는 자료이지만, 자료의 기록, 보존, 분류, 분석을 위한 체계적인 연구 프레임워크의 구축은 아직 초기 단계에 있다. 토픽 모델링(topic modeling)은 문서에 숨겨져 있는 테마 구조를 드러내주는 알고리즘으로 연구 동향 분석과 같이 대량의 문서에 내재된 주제어를 찾아내기에 적합한 기법이다. 본 연구에서는 사운드스케이프 연구 분야의 대표적 학술지인 의 논문을 토픽 모델링 기법으로 분석하여 사운드스케이프 연구 동향을 파악할 수 있는 주제어를 도출해 보고, 이를 사운드스케이프 온톨로지(Soundscape Ontology) 및 사운드 아카이브의 메타데이터 설계 시 활용할 수 있는 방안에 대해 살펴보고자 한다. 이는 향후 시맨틱 웹 기술인 링크드 데이터(Linked Data) 기반의 사운드스케이프 아카이브 구축을 위한 메타데이터 설계의 기초 연구가 될 것이다.

• 한국산학기술학회논문지
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• 제20권5호
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• pp.621-626
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• 2019

자동차의 과도한 차체 운동과 조종 불안정성을 유발하는 대표적인 외란 입력으로는 운전자에 의해 가해지는 조향 핸들 조작이다. 급격하고 과도한 핸들 조작은 SUV 차량처럼 기하학적 및 동역학적 특성에 따라 차량 전복 현상도 발생시킬 수 있다. 본 연구에서는 이에 대응할 수 있는 제어 시스템의 구조화에 대하여 다음과 같이 기초 연구를 수행하였다. 운전자 조종으로 유발되는 횡방향 거동에 대한 수학적 모델링을 수행하고, 이를 토대로 차체 운동을 제어할 수 있는 제어기를 설계하였다. 파라미터 불확실성으로 인한 모델링 오차에 대해 강건한 제어 성능을 확보하기 위하여 $H_{\infty}$ 알고리즘을 적용하였다. 비 연성화된 1/4 차량을 기반으로, 차체에 작용하는 모우멘트에 상응하는 동적 부하를 모사할 수 있는 모델을 제시하였다. 동적 시뮬레이션을 수행하여 부하 모사 모델의 타당성을 파악하였다. 차체- 차축- 서스펜션- 타이어로 조합되는 1/4 실험 차량 장치와 부하 모사 모듈, 서스펜션 제어 모듈 및 Hils 기술을 적용하는 차체 거동 제어 시스템에 대한 프레임워크를 제안하였다.

• Mass Spectrometry Letters
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• 제10권1호
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• pp.18-26
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• 2019

We developed a bioanalytical method for simultaneous determination of nine NBOMe derivatives (25H-NBOMe, 25B-NBOMe, 25E-NBOMe, 25N-NBOMe, 25C-NBOH, 25I-NBOH, 25B-NBF, 25C-NBF, and 25I-NBF) in human plasma using liquid chromatography tandem mass spectrometry (LC-MS/MS). Human plasma samples were pre-treated using solid-phase extraction. Separation was achieved on a C18 column under gradient elution using a mobile phase containing 0.1% formic acid in acetonitrile and 0.1% formic acid in water at a flow rate of 0.3 mL/min. Mass detection was performed in the positive ion mode using multiple reaction monitoring. The calibration range was 1-100 ng/mL for all quantitative analytes, with a correlation coefficient greater than 0.99. The intra- and inter-day precision and accuracy varied from 0.85 to 6.92% and from 90.19 to 108.69%, respectively. The recovery ranged from 86.36 to 118.52%, and the matrix effects ranged from 27.09 to 99.72%. The stability was acceptable in various conditions. The LC-MS/MS method was validated for linearity, accuracy, precision, matrix effects, recovery and stability in accordance with the FDA guidance. The proposed method is suitable for reliable and robust routine screening and analysis of nine NBOMe derivatives in forensic field.

• 한국컴퓨터정보학회논문지
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• 제24권1호
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• pp.73-83
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• 2019

In this paper, we propose the augmented reality(AR) based driving navigation based on robust lane detection method to dynamic environment changes. The proposed technique uses the detected lane position as a marker which is a key element for enhancing driving information. We propose Symmetrical Local Threshold(SLT) algorithm which is able to robustly detect lane to dynamic illumination environment change such as shadows. In addition, by using Morphology operation and Connected Component Analysis(CCA) algorithm, it is possible to minimize noises in the image, and Region Of Interest(ROI) is defined through region division using a straight line passing through several vanishing points We also propose the augmented reality aided visualization method for Interchange(IC) and driving navigation using reference point detection based on the detected lane coordinates inside and outside the ROI. Validation experiments were carried out to assess the accuracy and robustness of the proposed system in vairous environment changes. The average accuracy of the proposed system in daytime, nighttime, rainy day, and cloudy day is 79.3% on 4600 images. The results of the proposed system for AR based IC and driving navigation were also presented. We are hopeful that the proposed research will open a new discussion on AR based driving navigation platforms, and thus, that such efforts will enrich the autonomous vehicle services in the near future.

• Steel and Composite Structures
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• 제31권3호
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• pp.261-276
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• 2019

The study investigates the free vibration of a nano-scale sandwich beam by an extended high order approach, which has not been reported in the existing literature. First-order shear deformation theory for steel skins and so-called high-order sandwich panel theory for the core are applied. Next, the modified couple stress theory is used for both skins and cores. The Hamilton principle is utilized for deriving equations and corresponding boundary conditions. First, in the study the three-mode shapes natural frequencies for various material parameters are investigated. Also, obtained results are evaluated for two types of stiff and soft cores and isotropic, homogenous steel skins. In the research since the governing equations and also the boundary conditions are nonhomogeneous, therefore some closed-form solutions are not applicable. So, to obtain natural frequencies, the boundary conditions are converted to initial conditions called the shooting method as the numerical one. This method is one of the most robust approaches to solve complex equations and boundary conditions. Moreover, three types of simply supported on both sides of the beam (S-S), simply on one side and clamp supported on the other one (S-C) and clamped supported on both sides (C-C) are scrutinized. The parametric study is followed to evaluate the effect of nano-size scale, geometrical configurations for skins, core and material property change for cores as well. Results show that natural frequencies increase by an increase in skins thickness and core Young modulus and a decrease in beam length, core thickness as well. Furthermore, differences between obtained frequencies for soft and stiff cores increase in higher mode shapes; while, the more differences are evaluated for the stiff one.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권3호
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• pp.1078-1099
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• 2021

Traditional image steganography hides secret information by embedding, which inevitably leaves modification traces and is easy to be detected by steganography analysis tools. Since coverless steganography can effectively resist steganalysis, it has become a hotspot in information hiding research recently. Most coverless image steganography (CIS) methods are based on mapping rules, which not only exposes the vulnerability to geometric attacks, but also are less secure due to the revelation of mapping rules. To address the above issues, we introduced camouflage images for steganography instead of directly sending stego-image, which further improves the security performance and information hiding ability of steganography scheme. In particular, based on the different sub-features of stego-image and potential camouflage images, we try to find a larger similarity between them so as to achieve the reversible steganography. Specifically, based on the existing CIS mapping algorithm, we first can establish the correlation between stego-image and secret information and then transmit the camouflage images, which are obtained by reversible sub-feature retrieval algorithm. The received camouflage image can be used to reverse retrieve the stego-image in a public image database. Finally, we can use the same mapping rules to restore secret information. Extensive experimental results demonstrate the better robustness and security of the proposed approach in comparison to state-of-art CIS methods, especially in the robustness of geometric attacks.

• 한국해양공학회지
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• 제35권1호
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• pp.82-90
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• 2021

Owing to the advantages of assuring the best views and seawater exchange, submerged breakwaters have been widely installed along the eastern coast of Korea in recent years. It significantly contributes to promoting the advancement of shorelines by partially inhibiting incident wave energy. Observations were carried out by a pressure-type wave gauge in the Bongpo Beach to evaluate the coefficients of wave transmission via a submerged breakwater, and the results obtained were compared with those of existing conventional equations on the transmission coefficient derived from hydraulic experiments. After reviewing the existing equations, we proposed a transmission coefficient equation in terms of an error function. Although it exhibited robust relationships with the crest height and breaking coefficient, deviations from the observed data were evident and considered to be triggered by the difference in the incident wave climate. Therefore, in this study, we conducted a numerical experiment to verify the influence of wave period on the coefficients of wave transmission, in which we adopted a parabolic-type mild-slope equation model. Consequently, the deviation from calculated results appears to practically cover all deviation range in the observed data. The wave period and direction of the incident wave increased, the transmission coefficient decreased, and the wave direction was determined to demonstrate a relatively significant influence on the transmission coefficient. It was inferred that this numerical study is expected to be used practically in evaluating the design achievement of the submerged breakwater, which is adopted as a countermeasure to coastal beach erosion.

• 한국군사과학기술학회지
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• 제24권3호
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• pp.264-271
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• 2021

Raman spectroscopy is an equipment that is widely used for classifying chemicals in chemical defense operations. However, the classification performance of Raman spectrum may deteriorate due to dark current noise, background noise, spectral shift by vibration of equipment, spectral shift by pressure change, etc. In this paper, we compare the classification accuracy of various machine learning algorithms including k-nearest neighbor, decision tree, linear discriminant analysis, linear support vector machine, nonlinear support vector machine, and convolutional neural network under noisy and spectral shifted conditions. Experimental results show that convolutional neural network maintains a high classification accuracy of over 95 % despite noise and spectral shift. This implies that convolutional neural network can be an ideal classification algorithm in a real combat situation where there is a lot of noise and spectral shift.

• 국제지역연구
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• 제16권1호
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• pp.75-98
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• 2012

금융이해력의 측정과 분석에 대한 다양한 논의를 바탕으로 재일본 한국 고등학생의 금융이해력을 측정하고, 이를 기존의 한국, 일본, 미국의 측정 결과와 비교 분석했다. 청소년의 금융이해력에 대한 엄밀한 정의에 따라 금융이해력을 체계적으로 측정한다면, 학교와 지역사회에서 수행되고 있는 금융교육의 적절성을 효과적으로 평가할 수 있으며, 금융교육의 개선방안을 제시할 수 있다. 표준적인 금융이해력테스트를 통해 측정된 재일본 한국 고등학생과 기존의 한국, 일본, 미국의 결과를 비교분석한 결과를 요약하면, 첫째, 재일본 한국 고등학생의 금융이해력 문항에 대한 평균 정답률은 한국, 일본, 미국보다 낮은 수준이었다. 둘째, 금융이해력 문항 중 소득, 저축과 투자, 지출과 신용 영역에서는 일본 고등학생의 경우가 재일본 한국 고등학생이나 한국, 미국의 경우보다 높은 이해력을 보였으며, 금전 관리 영역에서는 한국의 경우가 미국보다는 다소 높아 보였으나 일본의 경우보다는 낮았다. 셋째, 재일본 한국 고등학생, 한국, 일본, 미국 고등학생 모두의 경우, 학업 준비에 대한 금융이해력은 높았으나 가계 관리에 대한 이해력은 상대적으로 낮은 수준으로 나타났다.

• 한국가족관계학회지
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• 제21권3호
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• pp.73-93
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• 2016

Objective: The purpose of the present study was to examine how children's transition to adulthood might be related to their parents' marital satisfaction and relationship satisfaction with children. Specifically, we investigated if the numbers of children who (1) graduated from 4-year college, (2) were employed, (3) were married, (4) moved out of parental homes and lived independently, and (5) had at least one child might be associated with better marital satisfaction and higher relationship satisfaction with children among midlife and older parents. We also evaluated if the associations might differ by gender of the children (sons vs. daughters) as well as by their gender and birth order (first-born son, later-born son, first-born daughter, later-born daughter). Method: The analytic sample was drawn from the 2006 Korean Longitudinal Study of Ageing. The sample consisted of 1,905 parents whose children were aged between 25 and 35. For analysis, regression models with robust standard errors were estimated using Stata. Results: Results suggest that sons' (especially first-born sons') transition to adulthood exerted more consistent impacts on parents. More specifically, first-born sons' completion of higher education, marriage, and independent living arrangement were associated with either higher levels of parental marital satisfaction or relationship satisfaction with children. With regard to later-born sons, their completion of college education was linked to higher levels of parental marital satisfaction and relationship satisfaction with children. Conclusion: Korean parents appear to place greater importance on first-born sons' successful transition to adulthood compared to those of other children. Overall, however, transition to adulthood may have limited influence on Korean parents.