• Bulletin of the Korean Chemical Society
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• 제26권12호
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• pp.2027-2032
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• 2005

This paper demonstrates details of thermal behavior of Langmuir-Blodgett (LB) film of poly(tert-butyl methacrylate) (PtBMA) by using the principal component analysis based two-dimensional correlation spectroscopy (PCA2D) through eigenvalue manipulating transformation (EMT). By uniformly lowering the power of a set of eigenvalues associated with the original data, the smaller eigenvalues becomes more prominent and the subtle contribution from minor components is now highlighted much more strongly than the original data. Thus, the subtle difference of thermal behavior of LB film of PtBMA from minor components, which is not readily detectable in the conventional 2D correlation analysis, is much more noticeable than the original data. PCA2D correlation spectra with EMT operation for the temperature-dependent IR spectra of LB film of PtBMA reveal the hidden property of phase transition processes during heating.

• 전기전자학회논문지
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• 제16권2호
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• pp.153-158
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• 2012

A new diversity combining scheme is proposed for time-of-arrival (TOA) estimation of chirp signal in dense multipath channel. In the multipath channel, the performance of TOA estimation using conventional correlation matrix-based diversity combining scheme is degraded due to the lack of de-correlation effect. To increase the de-correlation effect, the proposed diversity scheme employs interleaving method based on the property of de-chirped signal. As a result, the proposed scheme increases de-correlation effect and also reduces the noise of TOA estimation. Finally, the diversity achieved from the proposed scheme improves TOA estimation performance. The de-correlation effect is analyzed mathematically. The estimation accuracy of the proposed diversity scheme is superior to that of conventional diversity scheme in multipath channel.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2000년도 특별강연 및 춘계학술발표대회 개요집
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• pp.189-192
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• 2000

• 대한전자공학회논문지SP
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• 제38권4호
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• pp.344-352
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• 2001

본 논문에서는 퍼블릭 워터마킹(public watermarking)에서 영상 블록의 유효성에 기반을 둔 상호연관성(cross-correlation property)과 관련기법을 제안하였다. 이 과정에서 워터마크의 비인식성(imperceptibility)과 깨지기 쉬운 워터마크(fragile watermark)를 보장하기 위하여 DCT(Discrete Cosine Transformation) 도메인의 고주파 영역을 사용하였다. 여러 가지 실험을 통하여 에러가 보정된 원본 영상(original image)들과 워터마크된 이미지(watermarked image)들 사이에 유효한 블록들이 동일함을 확인하였다. 그리고 이러한 상호연관성이 추후의 퍼블릭 워터마킹을 위한 응용들에 적용될 수 있음을 입증하였다.

• 대한가정학회지
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• 제23권3호
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• pp.9-16
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• 1985

There are two standards for evaluation of fabric aesthetics, the feeling of fabric and the fabric sense of sight. Its drapalility with lustre is one of factors to decide the fabric sense of sight. This study was carried out to investigate the drape property property of fabrics. The fabric characteristics and the physisical properties of fabrics were tested. And the effect of the laundering on the drape properties was examined. RESULTS : 1. The drape coefficients of sampled fabrics were increasd as the thickness of fabrics were increased, excluding the fabric consisting of 60% polyester$\times$40% wool. 2. The drape coefficient of sampled fabrics were decreased as the cover faders of fabrics were increased, excluding the summer clothes and the fabrics of 100% wool. 3. The drape coefficients of fabrics other than sumer clothes were increased as the weight of fabrics were in creased. 4. Positive correlation was observed between the stiffness and the drape coefficient. 5. Negative correlation was observed between the fabric shrinkage and the drape coefficient. 6. The drape coefficient was decreased to a certain limit by laundering.But as the laundering was repeated up to certain number, the drape coefficient and the node number, a significant correlation was observed between the drape coefficient and the node shape.

• The Journal of Asian Finance, Economics and Business
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• 제8권12호
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• pp.465-471
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• 2021

The study investigates the dynamic correlation of cryptocurrencies and equity in Vietnam and tests the safe-haven property of them from the perspective of the stock market in Vietnam during the pandemic crisis by applying the dynamic conditional correlation (DCC) GARCH model and regression with a dummy variable, respectively. This study employs time series data on the daily dataset from September 2014 to September 2021 with the focus on the two most popular cryptocurrencies - Bitcoin and Litecoin. The results show that the dynamic conditional correlations between cryptocurrencies and equity in Vietnam increased during the pandemic, however, in most periods, positive dynamic correlations often dominate. Besides, the regression results also indicate that Bitcoin and Litecoin act as weak safe-haven investments for stocks in Vietnam during the COVID-19 turmoil. They are more suitable for diversification purposes although the dynamic correlations between them and the stock index in Vietnam vary stronger during the pandemic crisis than before. The findings of this study suggest that in the period of pandemic crisis, cryptocurrencies are not concerned as effective safe-haven assets for stock in Vietnam. Instead, cryptocurrencies are only playing a potential role in diversification benefit in this economy.

• Journal of Positioning, Navigation, and Timing
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• 제9권4호
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• pp.293-304
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• 2020

In this paper, various modulation techniques, including the legacy Global Navigation Satellite System (GNSS) signal modulation techniques, are introduced and the spectral characteristics and correlation characteristics of signals with various modulation techniques are analyzed based on numerical simulation. With the development of various GNSS services, the limited frequency band has become increasingly saturated, and issues of interoperability and compatibility have emerged in the new GNSS design. Since the efficient allocation of frequency resources is closely related to spectrum design, modulation techniques are one of the important signal design parameters of new signal design. Signal modulation techniques are closely related to various figure of merits (FoMs) as well as spectrum characteristic, and in some cases there is a complicated trade-off between FoMs. Thus, the FoMs associated with modulation technology should be analyzed and the best signal candidates should be chosen carefully via the trade-off analysis for FoMs. In this paper, we define the modulation technique based on Phase Shift Keying (PSK), Binary Offset Carrier (BOC) and Continuous Phase Modulation (CPM) for the design of KPS signals, and the FoMs of signals in terms of spectrum and correlation function are evaluated. Signals with various modulation techniques are implemented through a numerical simulation, and the relevant FoMs are analyzed.

• Journal of applied mathematics & informatics
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• 제27권3_4호
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• pp.673-683
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• 2009

We point out: to make Hermtian matrices A and B satisfy Styan matrix inequality, the condition "positive definite property" demanded in the present literatures is not necessary. Furthermore, on the premise of abandoning positive definite property, we derive Styan matrix inequality of Hadamard product for inverse Hermitian matrices and the sufficient and necessary conditions that the equation holds in our paper.

• 한국측량학회지
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• 제25권6_2호
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• pp.587-597
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• 2007

본 연구는 IKONOS Geo레벨 스테레오 영상으로부터 DEM을 제작하기 위한 토지피복 특성별 정합영역 크기를 결정하고자 한다. 사용된 매칭기법은 상관계수를 이용한 영역기반정합 기법을 적용하였고, 탐색영역을 최소화하기 위해 외부표정요소를 구한 후, 이로부터 정합선을 수립하여 정합하였다. 실험은 산림, 논 밭, 수계, 도심지의 4가지 토지피복 특성별로 수행되어졌으며, 토지피복별 평균 상관계수, 칼럼 라인의 시차영상을 분석한 후, 실험 영상에서 최적의 정합영역 크기를 선정하였다. 실험결과, 산림지역은 $119{\times}119$화소, 논 밭 지역은 $51{\times}51$화소, 물 지역은 $81{\times}81$화소, 도심지는 $21{\times}21$화소가 DEM 제작을 위한 가장 적절한 정합영역 크기로 선정되었다.

• 한국ITS학회 논문지
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• 제14권5호
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• pp.30-37
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• 2015

MIMO(Multiple Input Multiple Output) 시스템을 사용하여 주파수 선택적 페이딩 환경에서 동작하는 차세대 무선 통신 시스템의 데이터 전송 속도를 향상시키기 위한 연구가 현재 활발히 진행 중이다. 여러 개의 송신 안테나에서 송신된 시호들이 혼합되어 각 수신 안테나에 수신되는데 이렇게 혼합된 신호를 분리하기 위해서 직교 특성을 갖는 훈련신호가 필요하며, 이 훈련신호를 사용하여 신호의 동기화 및 채널 추정을 수행할 수 있어야 한다. 본 논문에서는 MIMO 통신 시스템에 사용 가능한 시퀀스들을 소개하고, 관심 영역에 대하여 우수한 자기 상관 특성을 갖는 변형된 WeCAN(weighted cyclic algorithm new) 시퀀스를 제안한다. 모의실험을 통해 각 훈련신호의 자기 상관도를 비교하였으며, 또한 도플러 주파수 변화와 다중경로 전달 페이딩 환경에서의 상관 특성을 비교하였다.