• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.1C
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• pp.138-144
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• 2009

This paper proposes an efficient scheme to estimate the channel parameters such as channel gain and delay for the IEEE802.15.4a LR-UWB systems. Sliding window (SW) method is generally used for the channel estimation of LR-UWB systems, which extracts the channel parameters by performing the cross-correlation with the repeatedly transmitted signal. However, the SW method experiences the severe performance degradation because the cross-correlation is performed just once for the received signal. In this paper, we propose a novel channel estimation scheme, which can achieve a great performance gain by performing the cross-correlation repeatedly with the repeated receive signal. In order to verify the performance gain of the proposed scheme, we performed the intensive simulation with the Saleh-Valenzuela channel model. Simulation results show that the proposed scheme has a performance improvement of 4dB compared to the conventional SW channel estimation scheme.

• The Journal of the Acoustical Society of Korea
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• v.21 no.2
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• pp.120-127
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• 2002

As a new type of a linear decorrelating receiver, the Pseudo-Decorrelator was presented for asynchronous code division multiple access systems by the author. In this paper, the concept of the Pseudo-Decorrelator is extended to derive a multiuser receiver for WCDMA uplink systems over a Rayleigh fading multipath channel. Starting with the analysis of the multiple access components of the decision statistics, a non-square cross-correlation matrix for each bit is obtained. This cross-correlation matrix is then inverted, and the inverted matrix is applied to the decision statistics obtained from a conventional receiver. This receiver is near-far resistant and outperforms conventional receivers even for the cases in which synchronization errors, such as time delay errors and phase errors exist.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.7
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• pp.2475-2482
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• 2010

This study aimed to evaluate correlation between self-evaluation factors(satisfaction, linkage with major, suitability of management, verbal and non-verbal communication) and academic achievement of medical students according to introduction of explanation meeting in cadaveric dissection. The study was carried out that medical students(n=57) explained cadaveric structure to health allied sciences students and discussed with each other. Just after the meeting,, medical students filled out a questionnaire on impact of self-evaluation factors and communication. We analyzed these factors and their scores using frequency analysis, T-test and analysis of variance. Regardless of their gender, age, previous experience, the majority of the students gave high scores in all of self-evaluation factors. Among them, only verbal communication factor was closely related to their academic achievement(p<0.05). The verbal and non-verbal communication also had a high correlation of 0.673(p<0.01). The explanation meeting provided chance to learn further with positive attitude to medical students and motivated them academically. Additionally, they realized that communication skill played a key role in transmitting medical knowledge to others. Therefore, introduction of communication-based explanation meeting would be very useful tool in improving educational efficiency.

• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
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• v.5 no.6
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• pp.317-325
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• 2015

The aim of this research was to investigate the relationship among team learning behavior, individual creativity, team shared mental model(TSMM), mutual performance monitoring on team creativity and then providing the fundamental data on the education. Also it intended to acknowledge relative predictive power on team creativity of independent variables. The total of 257 college students participated the team learning for 6 weeks in a semester. Pearson's product moment correlation and regression analysis were used for data analysis and testing of significance of verification, The main research results are summarized as follows; team learning behavior, TSMM, mutual performance monitoring had no significant effects on three subfactors of team creativity such as novelty, resolution, elaboration & synthesis. Therefore followed researches are needed about inter and intra processing of team creativity.

• The Journal of the Convergence on Culture Technology
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• v.9 no.3
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• pp.271-279
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• 2023

The purpose of this study was to investigate the effect of learning flow, problem solving ability, professor-student interaction of academic achievement in nursing students. Data were collected from 274 nursing students in B city and analyzed by t-test, ANOVA, Pearson correlation coefficient, and hierarchial multiple regression using SPSS/WIN 22.0. The degree of academic achievement in nursing students was 3.70±0.70. There were significant differences in academic achievement with grade(F=4.755, p=.003), campus life satisfaction(F=5.643, p=.004), major satisfaction(t=5.794, p=.003), adapting to COVID-19(F=7.961, p<.001), satisfaction to non-face-to-face environment class(F=18.353, p<.001). There was positive correlation between academic achievement and learning flow(r=.649, p<.001), problem solving ability(r=.333, p<.001), professor-student interaction(r=.479, p<.001). The factors affecting academic achievement of the study subjects were learning flow(β=.563, p<.001), professor-student interaction(β=.280, p<.001), with an explanatory power of 52.0%. Therefore, strategies increase the academic achievement of nursing students in untact lecture, and environment improvement to increase learning flow and professor-student interaction are needed.

• 한국해양학회지
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• v.20 no.2
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• pp.49-60
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• 1985

The interrelationships between distribution of phytoplankton and hydrographical conditions were studied from December 1983 to July 1984 in Yeongil Bay. The temporal variation of phytoplankton abundance seems to be mainly influenced by the vertical stability of water column and the freshwater run-off accompanied with possible nutrient input. The temporal progression of dominant species shows general succession pattern, especially skeletonema costatum was found a dominant species in each month. Although the differences between concentration of chlorophyll a and abundance of phytoplankton may be caused by cell size variation, during the study period they show felatively good linear manner. The phytohydrographic region based on multivariate analysis reflects the relationships between hydrographical condition and distribution pattern of phytoplankton.

• Journal of Distribution Research
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• v.10 no.2
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• pp.99-120
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• 2005

First, based on extant studies in the field, the author extracts environments, general and personalized interactions between an internet shopping mall and its customers, interactions among customers, and outcomes as 5 relevant dimensions of the service quality of an internet shopping mal She derives hypotheses on the relationships between each of the service quality dimensions and each of the three components of the relationship quality, satisfaction, trust, and commitment. She also investigates the moderating role of the relationship duration defined by the length of use in the relationships. She studies the relationships among the three relationship quality components and their effects on the future intentions of relationship maintenance, too. Through a survey on college students and adult consumers, she gathers 349 qualified questionnaires. Applying regression methods on the data, she finds out that most of the relationships between each of the service quality dimensions and each of the relationship quality dimensions are statistically significant but that the strengths of relationship are quite different dimension by dimension. The moderating effect of the relationship duration is not found except one case, the relationship between general interactions and trust. The author also finds out positive relationships between satisfaction and trust between satisfaction and commitment, and between trust and commitment. Positive relationships between trust and the future intention of relationship maintenance and between commitment and the future intention are found. But the data does not reveal any statistically significant relationship beetween satisfaction and the future intention. The author provides a few implications of the research results and future research agenda.

• 한국정보교육학회:학술대회논문집
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• 2007.08a
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• pp.108-113
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• 2007

온라인 학습 환경을 효율적으로 구성하는 것은 학습자의 학습 성공을 촉진할 뿐만 아니라 학습과정의 이해에 절대적으로 필요한 일이다. 만일 학습자와 교수자가 효율적으로 교류하면 학습자가 느끼는 심리적 거리감은 상당히 최소화될 수 있을 것이다. 이 연구는 학습자들의 온라인 학습에서 교류적 거리의 구조 지각은 성별에 따라 달라지는가를 알아보고 온라인 환경에서의 수업만족도, 지속성, 학업성취도에 가장 큰 영향을 미치는 구조의 하위영역이 무엇인지를 밝혀 학습자들의 학습효과를 체계적으로 높일 수 있는 온라인 환경의 요소를 탐색하는데 있다. 설문을 통해 수집된 자료는 연구 목적에 따라 다양한 분석을 실시하였다. 이 연구 결과 학습자의 일반적 특성인 성별에 따른 교류적 거리의 구조 지각수준은 의의있는 차이가 없었다(p>.05). 교류적 거리의 구조 지각수준과 학습자가 지각하는 수업만족도간에 의의있는 상관이 있었으며, 학습자의 학습 지속성과도 통계적으로 의의있는 상관이 있는 것으로 나타났다. 그러나 학업성취도와 교류적 거리의 구조 지각수준 간에는 유의의한 차이가 발견되지 않았다(p>.05). 교류적 거리의 구조 하위영역 중 수업만족도에 대한 영향력이 큰 하위영역은 과정 상호 작용이며, 학습 지속성에 대한 영향력이 큰 하위영역은 내용 구성요인으로 나타났다.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.171-171
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• 2015

자연 하천의 홍수 유량 측정은 매우 어렵고 많은 비용과 시간, 노력을 요하는 작업이다. 보다 안전하고 경제적인 유량 측정의 대안으로 제시된 것이 하천 표면의 영상 분석을 이용하는 표면영상유속계이다. 이처럼 영상유속계로 하천 유속을 측정할 때, 적절한 품질의 영상을 취득하는 것은 기본이며 매우 중요한 단계이다. 특히 홍수 첨두는 야간에 발생하는 경우가 많으므로, 야간에 영상 분석에 적절한 품질의 하천 표면영상을 취득하는 것은 매우 어려운 일이다. 야간 영상을 측정하기 위해 별도의 조명을 이용하거나 발광체를 이용하는 방법이 대안으로 제시되었으나 여전히 실용적인 차원의 적용에는 이르지 못하고 있다. 본 연구에서는 표면영상유속계의 영상 취득 장치로 원적외선 카메라를 이용할 수 있는가 시험하였다. 원적외선 카메라는 별다른 조명의 도움없이 야간의 하천 표면영상을 취득할 수 있다. 안동하천실험센터의 인공수로에서 주야간 촬영을 하고 영상 분석을 통해 원적외선 카메라의 적용성을 검토하였다. 비교를 위하여 일반적인 캠코더와 근적외선 카메라를 동시에 적용하였다. 세 종류의 카메라로 촬영된 영상은 시공간 영상의 상호상관 분석법을 통해 유속으로 환산하고, 미속계로 측정한 표면 유속과 비교하였다. 비교 결과 원적외선 카메라 영상은 주야간에 상관없이 적절한 유속을 분석해 낼 수 있음을 보였다. 다만, 공간 해상도가 높지 않아 영상 분석의 정확도는 최적의 조건에서 다른 카메라로 촬영된 영상에 비해 떨어진다.

• The Journal of the Acoustical Society of Korea
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• v.17 no.1
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• pp.86-97
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• 1998

본 논문은 스테레오 음향 반향 제거기에 적용되는 고속 Affine Projection 알고리듬 을 제안한다. 최근 스테레오 원격 회의 시스템은 보다 현실감 있는 원격 회의를 가능케 하 는 장점으로 인해 많은 관심을 끌고 있다. 그러나, 회의실의 원단화자와 마이크로폰사이의 상호교차(cross-coupling)로 인해 음향 반향이 발생하게 된다. 만약 이 반향 신호가 제거되 지 않은채 수신 룸으로 전달되면 결국 음성 통화 품질이 저하된다. 이를 방지하기 위하여 추정 반향 신호를 만들어 내고 통신 품질의 손실 없이 이 반향을 제거하는 음향 반향 제거 기가 필수적이다. 단 채널 음향 반향 제거기와 다르게 스테레오 환경하에서의 음향 반향 제 거기는 전송실의 환경변화로 인한 성능 저하와 각 반향 경로를 추정하기 위해 사용하는 각 적응 필터의 임펄스응답이 반향 경로와 일치하지 않는 등의 각종 문제점들이 발생하게 된 다. 본 논문에서는 서로 상관관계 없는 입력신호를 만들어내고 전송실의 환경변화로 인한 성능저하를 보완하기 위해 전처리단(pre-processing block)을 제안하여 일반적인 방법에 대 해 3-10dB정도의 향상된 성능을 보이며 적은 계산량으로 빠른 수렴성능을 갖는 새로운 형 태의 스테레오 음향 반향 제거기를 제안한다.