• The Journal of the Acoustical Society of Korea
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• v.21 no.3
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• pp.264-273
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• 2002

Adaptive filters cannot exactly estimate the echo path of the receiving room because of the cross-correlation of stereo signals. In this paper, a new pre-processing method reducing the cross-correlation without degradation of stereophony is proposed to enhance the performance of stereophonic acoustic echo canceller. To reduce the cross-correlation, absolutes of two orthogonal signals derived from each channel signals are added to original channel signals. Assuming that the power of each channel signal is larger than that of the cross-correlation, the computation of pre-processing can be reduced. As results of simulations, it is shown that the performance of stereo acoustic echo canceller with the proposed pre-processing method is better than that of conventional ones.

• 한국방재학회:학술대회논문집
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• 2007.02a
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• pp.133-136
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• 2007

Cross correlation of seismic-background motions (Campillo and Paul, 2003; Shapiro et al., 2005) is applied to observations from the Korean Meteorological Administration seismic network to estimate the short-period Rayleigh and Love wave dispersion characteristics of the region. Standard processing procedures are applied to the cross correlation, except that signal whitening is used in place of one-bit sampling to equalize power in signals from different times. Multiple-filter analysis is used to extract the group velocities from the estimated Green's functions, which are then used to image the spatially varying dispersion at periods between 0.5 and 20 sec. The tomographic inversion technique used inverts all periods simultaneously to provide a smooth dispersion curve as a function of period in addition to the usual smooth spatial image for a given period. The Gyeongsang Basin in the southeastern part of the peninsula is clearly resolved with lower group velocities.

• Journal of the Economic Geographical Society of Korea
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• v.12 no.2
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• pp.179-194
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• 2009

The spatial distribution of crime incidences in urban neighborhoods is a reflection of their socio-economic environment and spatial inter-relations. Spatial interactions between offenders and victims lead to spatial autocorrelation of the crime incidences. The spatial autocorrelation among the incidences biases the interpretation of the ecological model in OLS framework. This research investigates residential crimes using residential burglaries and robberies occurred in the city of Columbus, Ohio, for 2000. In particular, the spatial distribution of incidence rates of residential crimes are accounted in OLS framework using eigenvectors, which reflect spatial dependence in crime patterns. Result presents that handling spatial autocorrelation enhanced model estimation, and both economic deprivation and crime opportunity are turned out significant in estimating residential crime rates.

• Korean Journal of Childcare and Education
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• v.2 no.2
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• pp.111-128
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• 2006

The goal of this study was to examine the relationship between teachers' efficacy belief and interactions between teachers and children of childcare teachers, and utilize the results as the basic data to educate of teachers. The subjects were 205 teachers at 48 childcare centers located in the Jeonlabukdo area. The results of this study are as follows: First, personal teaching efficacy and factors of interactions between teachers and children were significantly different by the types of childcare institution. Second, personal teaching efficacy was correlated positively with teachers' experiences. General teaching efficacy, personal teaching efficacy and factors of interactions between teachers and children were correlated positively with teachers' age. Third, factors of interactions between teachers and children were correlated positively with personal teaching efficacy. Lastly, personal teaching efficacy was the most powerful variable influencing interactions between teachers and children.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.5B
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• pp.645-652
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• 2001

본 논문에서는 일반적인 코드분할 다중화 시스템을 위해 저자가 제안하였던 유사 역상관기 (Pseudo-Decorrelator)를 변형하여 WCDMA 시스템에 적합한 원근 저항성 (near-far resistant) 수신기를 설계하고, 임펄스 채널 환경에서 성능을 분석하고 있다. 설계된 수신기에서는 판단변수 (decision statistics)에 포함되어 있는 다중사용자 간섭신호를 분석하여, 송신된 신호의 각 비트에 대응되는 상호상관 행렬을 얻게 된다. 이 상호상관 행렬을 역변환 시킨 후, 기존의 수신기에서 얻어진 판단변수에 적용한다. 이렇게 해서 수신기의 성능을 향상시킬 수 있다. 제안된 수신기는 연속해서 3비트를 받은 후에 바로 검출과정 (detection process)을 수행할 수 있다는 잇점이 있다. 임펄스 채널에서의 여러 가지 시뮬레이션을 통해서 수신기의 성능이 향상됨을 확인할 수 있었다.

• Proceedings of the Acoustical Society of Korea Conference
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• autumn
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• pp.227-230
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• 2000

본 논문에서는 외부방사 문제에 널리 사용되는 음향경계 요소 법(Acoustic Boundary Element Method)을 확장하여 저주파수 대역은 기존의 방법을 이용하고 고주파수 대역에서는 경계요소의 특성길이에 의한 고주파수 상한을 극복할 수 있는 방법을 제시한다. 밴드를 대표하는 음압 레벨을 직접 계산하도록 상호상관도 가정을 통하여 간략화 하였다. 간단한 음향방사 모델인 배플이 있는 빔과 평판에 대하여 Rayleigh 적분식의 계산결과와 제안된 방법을 비교하여 적용효능성을 검토하였다. 적용을 위한 조건으로는 방사면 진동의 상호상관도가 작아야 하므로, 이를 만족시키기 위한 일반적인 조건식을 제시하여 이로부터 경계요소의 특성길이를 정하는 기준을 제시하였다.

• Proceedings of the KAIS Fall Conference
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• 2010.11b
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• pp.897-900
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• 2010

본 연구에서는 해부학 실습 교육과정에 해부설명회를 도입에 따른 의학전문대학원생들의 자기평가요인(만족도, 전공 연계성, 운영 적절성, 의사소통)과 학업성취도와의 상관관계를 분석하였다. 2008-2009학년도 1학기 해부학 실습 교육을 받은 의학전문대학원생들(n=102)이 일부 수업시간을 활용하여 해부설명회에 참가하였고, 보건 의료 계통의 학부생들에게 사체를 활용하여 인체 구조에 대한 설명과 토론을 마친 후 설문지와 소감문을 작성하게 하였다. 이를 바탕으로 자기 평가 요인들을 분석하였고, 2008-2009 학년도 해부학 성적과의 상관관계를 조사하였다. 설문 대상자의 일반적 특성에 따른 자기 평가 요인을 분석한 결과, 성별, 연령, 과거 경험 유무 등의 일반적 특성과 상관없이 만족도, 전공 연계성, 운영 적절성, 언어적 및 비언어적 커뮤니케이션 모두에서 높은 수치를 나타내었다. 자기 평가 요인 중 학업성취도와 높은 상관관계를 갖는 요인은 언어적 커뮤니케이션이었다(p<0.05). 또한 언어적 커뮤니케이션은 비언어적 커뮤니케이션과도 높은 상관관계를 가졌다(r=0.580, p<0.01). 결론적으로 커뮤니케이션 기법을 활용한 해부설명회의 도입은 의전원 학생들에게 심화 학습의 기회를 제공하였고 학습동기를 유발시키며, 적극적인 학습태도를 갖게 하였다. 아울러 커뮤니케이션에 대한 중요성을 깨닫게 되었고, 타 전공자와의 상호교류를 통한 학문적 이해의 폭이 확대되었음을 확인하였다. 본 연구 결과를 바탕으로 진행과정에 나타난 문제점을 보완하고 개선한다면 해부학 실습의 개선 방안으로서 해부설명회의 활용가치가 충분하다고 판단되었다.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.5
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• pp.47-53
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• 2007

The purpose of IEEE 802.16j is to extend coverage and to enhance throughput by using relay station additionally to conventional IEEE 802.16e . The cellular system experiences performance degradation at the cell edge due to pathloss, shadow and multipath fading. We can get advantage of spatial diversity gain by using relays more than two cooperatively in the IEEE 802.16j system. Cooperative relaying using space-time code provides better performance under multipath fading and has more robustness against the shadow fading than single relaying. In this paper, we investigate the performance of IEEE 802.16j using cooperative relaying by link level simulation. We also show that the cooperative relaying system achieves better performance than the conventional single relaying system. We apply realistic shadow model considering correlations between shadow fadings of different relaying paths. It is shown that the performance of the system depends highly on the spatial location of relay stations.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.6
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• pp.231-239
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• 2018

This study was conducted to examine the influence of personal characteristics of infant-toddler and mother, social support and mother-child interaction on mother-child attachment. A descriptive study was implemented, and data were gathered from March 1 to September 30, 2016. The subjects were 215 mothers whose children were in infancy or toddlers. A survey was conducted with self-administered questionnaires regarding general characteristics, social support, mother-child interaction and attachment. SPSS 24.0 was used for descriptive statistics, intergroup comparisons of average scores, correlation analysis and multiple regression analysis. Statistically significant differences in average attachment scores according to gender (t=3.200, p<0.002), age (t=4.037, p<0.001) and temperament (F=4.614, p<0.011) were observed among the characteristics of infant-toddlers, as well as according to age (F=18.028, p<0.001) and academic credentials (F=4.241, p<0.016) among the characteristics of mother. Attachment was correlated with social support (r=0.507, p<0.001) and with mother-child interaction (r=0.571, p<0.001). The factors that affected attachment were mother-child interaction (${\beta}=0.361$, p<0.001), social support (${\beta}=0.309$, p<0.001), age (under the age of 30)(${\beta}=-0.370$, p<0.001) and marriage duration (less than 10 years)(${\beta}=-0.179$, p<0.033). Overall, the results indicate that interaction programs that bolster social support and mother-child interactions that exert a crucial influence on attachment should be developed.

• Proceedings of the Acoustical Society of Korea Conference
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• autumn
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• pp.135-138
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• 2001

오늘날 오디오 포맷의 대부분은 마스킹 효과를 이용한 손실 압축 기법(lossy coding)이다. 그러나 고음질을 요구하는 매니아가 있고 DVD등 차세대 멀티미디어 포맷으로 무손실 오디오 압축기법이 요구되고 있고 이를 위해 일반적인 무손실 데이터 압축방법인 PkZip 등으로 압축할 경우 압축비가 약 1.07:1 밖에 되지 않으므로 적절하지 못하여, 디지털 오디오 데이터를 위한 무손실 압축 알고리즘의 연구가 필요하게 되었다. 본 논문에서는 플래이밍(Framing), 상호상관제거(intrachannel decorrelation), 엔트로피 코딩(Entropy coding) 의 세가지 단계로 구성되는 일반적인 오디오 무손실 압축 기법을 효율적으로 압축하기 위해 wavelet transform을 적용한 알고리즘은 제안한다.