• 한국통신학회논문지
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• 제40권9호
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• pp.1678-1685
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• 2015

본 논문에서는 신뢰도를 모르는 불완전한 채널 정보를 이용해 빔포밍 기법의 장점과 직교 시공간 블록 코딩 (Orthogonal Space-Time Block Coding, OSTBC) 기법의 장점을 결합해 주는 선형 프리코딩 기법을 제안한다. 먼저 다양한 값의 채널 정보의 신뢰도를 가정한 상태에서 각 신뢰도가 프리코딩 성능에 미치는 영향을 분석한다. 그 뒤, 효율적인 프리코더의 설계를 위하여 수신 SNR을 바탕으로 필요한 채널 정보의 신뢰도를 예측하는 방법을 제안한다. 시뮬레이션을 통해 제안된 프리코더 설계 기법의 효율성을 확인한다.

• 대한간호학회지
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• 제52권2호
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• pp.228-243
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• 2022

Purpose: The study aimed to translate the Couple Satisfaction Index (CSI 32) into Korean, to evaluate the reliability and validity of CSI 32 and short-form (CSI 16, 4) in the Korean context, and to determine a cut-off score for Korean couples. Methods: Korean Versions of the Couple Satisfaction Index (K-CSI) 32 was translated, back-translated, and reviewed by five bilingual experts. Confirmatory factor analysis (CFA) was conducted with data from a sample of 218 couples (N = 436) to test construct validity. Validity and reliability were evaluated. The receiver's operating characteristics curve analysis was used to obtain the cut-off score. Results: The construct validities of K-CSI 32, 16, and 4 were verified using one-factor structures. The results of CFA showed a slightly better fit for K-CSI 16 and 4 than for K-CSI 32. Convergent validity was supported by significant positive correlations of K-CSI with Kansas Marital Satisfaction Scale, Dyadic Adjustment Scale, and Family Relationship Assessment Scale. Moreover, the significant differences in K-CSI between normal and depressive group demonstrated known-group validity. Cut-off scores of 105.5 on K-CSI 32, 50.25 on K-CSI 16, and 13.25 on K-CSI 4 were validated to identify distressed couple relationships. Conclusion: For clinical practice, the reliable and valid K-CSI 32 has the potential to measure changes in couple satisfaction after couple therapy or interventions. Applying K-CSI 32 may facilitate research on couple and family relationships in nursing and contribute to the discussion on the role of couple satisfaction in mental health.

• 한국사회복지학
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• 제59권4호
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• pp.83-109
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• 2007

본 연구의 목적은 다양한 사회복지 실천현장에서 활용가능하고 신뢰도와 타당도가 검증된 Client Satisfaction Inventory(CSI)를 국내의 사회복지실천 현장에 적용할 수 있는지를 평가하는 것이다. 이를 위해 본 연구는 서울 경기지역의 종합사회복지관 6곳을 이용하는 259명의 사회복지서비스 이용자를 대상으로 한국어판 CSI(CSI-K)를 평가하였다. 문항분석을 통해 5개 문항이 부적절한 문항으로 나타나 이들 문항을 제외한 다음 탐색적 요인분석을 실시하였다. 분석한 결과 CSI-K는 2개 요인(서비스 공급자에 대한 만족과 서비스 결과에 대한 만족)으로 구성된 척도로 나타났으며 각 요인의 내적일관성 신뢰도는 .964와 .885로 매우 높았다. 타당도 평가에서도 CSI-K는 이론적으로 관련된 변인들과 통계적으로 유의미한 정적인 상관관계를 보였으며 인구사회학적 변인의 영향을 받지 않은 것으로 나타났다. 후속연구를 통해 CSI-K가 우리나라 실천상황에 더욱 적합한 도구로 개발되길 기대한다.

• 대한간호학회지
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• 제50권5호
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• pp.671-685
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• 2020

Purpose: The purpose of this study was to develop a Coping Scale for Infertility-Women (CSI-W). Methods: The initial items were based on an extensive literature review and in-depth interviews with seven infertile women. Forty-three items were derived from a pilot survey. Data were collected from 216 women who had experienced intrauterine insemination (IUI) and in-vitro fertilization (IVF) more than once. The data were analyzed to verify the reliability and validity of the scale. Results: Seven factors containing 28 items (four factors containing 17 items for active coping and three factors containing 11 items for passive coping) were extracted from the exploratory factor analysis to verify the construct validity. The four factors of active coping were confrontation, self-control, seeking social support (spouse), and seeking social support (colleagues and experts). The three factors of passive coping were distancing, escape, and avoidance. These items were verified through convergent, discriminant, and concurrent validity testing. The internal consistency reliability was acceptable (active coping: Cronbach's α = .78; passive coping: Cronbach's α = .81). Conclusion: As its validity and reliability have been verified through various methods, the CSI-W can contribute to assessing the coping strategies of infertile women.

• 품질경영학회지
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• 제31권3호
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• pp.85-97
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• 2003

There are various methods to assess to company's outcome. Among them, the customers satisfaction, which is assessed by customers, is the most important. If the customers satisfaction is measured by the CSI based on the proper reliability and validity, you can apply the result for various marketing methods. Therefore, this study develops a model to assess CSI for an industry, specifically, local automotive industry based on the SEM that is already proven valid through assessing models such as ACSI, KCSI and NCSI. Moreover, this research can be utilized for marketing strategy helping customers to decide as an AHP model, one of the decision making method.

• 한국통신학회논문지
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• 제31권12A호
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• pp.1182-1188
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• 2006

적응 변조 OFDM(Orthogonal Frequency Division Multiplexing) 전송 기법은 각 부반송파의 채널 상태에 따라 변조방식을 적절히 변화시켜 무선 채널의 다중 경로 페이딩에 의해 의한 영향을 최소화하여 시스템의 성능을 증가시키는 방식이다. 시스템이 적응적으로 전송하기위해서는 단말기에서 각 부반송파(subcarrier)별 채널 상태 정보 (Channel State Information : CSI)를 되먹임 채널을 통해 실시간으로 기지국으로 전송해 주어야한다. 하지만, 단말기에서 데이터를 처리할 때 걸리는 시간과, 단말기에서 기지국으로 CSI를 되먹임(feedback) 할 때 걸리는 시간으로 인한 되먹임 지연(feedback delay) d가 발생하게 된다. 이 되먹임 지연은 CSI 정보의 불일치를 발생시켜 적응 OFDM 시스템의 성능저하를 일으킨다. 본 논문에서는 CSI의 되먹임 지연 $d(\geq2)$를 적절히 보상하는 주파수 축 멀티 스탭 채널 예측기를 제안하고 이를 적응 전송 OFDM 시스템에 적용하고 모의실험을 통하여 기존의 OFDM 시스템, 기존의 채널 예측방식과의 성능을 MSE(mean square error), 비트오율(bit error rate : BER) 및 채널용량을 바탕으로 비교한다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권11호
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• pp.5305-5321
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• 2016

In wireless communication, the multiple-input multiple-output (MIMO) system is a well-known approach to improve the reliability as well as the data rate. In MIMO systems, channel state information (CSI) is typically required at the receiver to detect transmitted signals; however, in practical systems, the CSI is imperfect and contains errors, which affect the overall system performance. In this paper, we propose a novel maximum likelihood (ML) scheme for MIMO systems that is robust to the CSI errors. We apply an optimization method to estimate an instantaneous covariance matrix of the CSI errors in order to improve the detection performance. Furthermore, we propose the employment of the list sphere decoding (LSD) scheme to reduce the computational complexity, which is capable of efficiently finding a reduced set of the candidate symbol vectors for the computation of the covariance matrix of the CSI errors. An iterative detection scheme is also proposed to further improve the detection performance.

• Advances in Computational Design
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• 제9권3호
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• pp.187-211
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• 2024

WiFi sensing integration enables non-intrusive and is utilized in applications like Human Activity Recognition (HAR) to leverage Multiple Input Multiple Output (MIMO) systems and Channel State Information (CSI) data for accurate signal monitoring in different fields, such as smart environments. The complexity of extracting relevant features from CSI data poses computational bottlenecks, hindering real-time recognition and limiting deployment on resource-constrained devices. The existing methods sacrifice accuracy for computational efficiency or vice versa, compromising the reliability of activity recognition within pervasive environments. The lightweight Compact Convolutional Transformer (CCT) algorithm proposed in this work offers a solution by streamlining the process of leveraging CSI data for activity recognition in such complex data. By leveraging the strengths of both CNNs and transformer models, the CCT algorithm achieves state-of-the-art accuracy on various benchmarks, emphasizing its excellence over traditional algorithms. The model matches convolutional networks' computational efficiency with transformers' modeling capabilities. The evaluation process of the proposed model utilizes self-collected dataset for CSI WiFi signals with few daily activities. The results demonstrate the improvement achieved by using CCT in real-time activity recognition, as well as the ability to operate on devices and networks with limited computational resources.

• 전기의세계
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• 제30권1호
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• pp.41-46
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• 1981

In the current source inverters (CSI), which are widely used recently in many applications, in order to reduce the harmonic contents in the output line current, twelve-step waveform is synthesized usually by a phase-shifted addition of the output currents of two single CSI's. In this paper a new method of synthesis of the 12-step current waveform is suggested which employes a main and a new auxiliary inverters having lower capacity, and thus is economically advantageous over the conventional scheme. DC-side commutation and energy rebond circuit as described in Part I are also employed in this proposed twelve-step CIS for effective commutation and high reliability. Experimental results are also given in oscillgrams.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회/대한산업공학회 2003년도 춘계공동학술대회
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• pp.508-515
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• 2003

There are various methods to assess to company's outcome. Among them, the customers satisfaction, which is assessed by customers, is the most important. If the customers satisfaction is measured by the CSI based on the proper reliability and validity, you can apply the result for various marketing methods. Therefore, this study develops a model to assess CSI for an industry, specifically, local automotive industry based on the SEM that is already proven valid through assessing models such as ACSI, KCSI and NCSI. Moreover, this research can be utilized for marketing strategy helping customers to decide as an AHP model, one of the decision making method.