• 대한산업공학회지
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• 제33권2호
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• pp.237-245
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• 2007

In this paper, a modified PCF (Point Coordination Function) MAC (Medium Access Control) Protocol is proposed to support the multiple direct link communication between STAs (STAtions) in infrastructure mode IEEE 802.11 wireless LANs. By the proposed MAC protocol, the direct link communication between STAs, which are located within the communication range of each other, is allowed without the use of AP (Access Point) as a relay. Moreover, when multiple direct data communication between STAs can be simultaneously performed with a sufficiently small interference, multiple simultaneous direct link communication is allowed for the efficient use of radio bandwidth. AP polls STAs to grant the transmission opportunities using the direct link communication by transmitting the polling frames to STAs. An efficient polling method for granting the transmission opportunities to STAs is proposed to reduce the number of the polling frame transmissions and enhance the PCF MAC performance.

• 가정과삶의질연구
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• 제31권6호
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• pp.23-38
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• 2013

The purpose of this study was to investigate the effects of family differentiation from the family of origin, marital communication, and marital intimacy on the family strengths of married women in their twenties and thirties. The subjects were 237 married women in their twenties and thirties who live in D city. The questionnaire was consisted of measures on the family differentiation from the family of origin, marital communication, marital intimacy, and family strengths. Structural equational models were conducted with Amos 18.0. The major findings were as follows. 1) Family differentiation from the family of origin had both direct and indirect influences on the perceived family strengths of married women in their twenties and thirties. 2) Family differentiation from the family of origin had a direct effect on marital communication but no direct effect on marital intimacy. 3) Marital communication had a direct effect on marital intimacy but no direct effect on married women's perceived family strengths. 4) Marital intimacy had a direct effect on married women's perceived family strengths.

• 아동학회지
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• 제37권5호
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• pp.65-82
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• 2016

Objective: The main purpose of this study was to examine the direct and indirect effects of parent-adolescent communication (through adolescent optimism) on adolescent conflict-coping styles. Methods: A total of 337 high school students participated in this study. They completed questionnaires about communications with their parents and their own optimism and conflict-coping styles. Data were analyzed using t-tests, correlations, and SEM. Results: Neither father- nor mother-adolescent communication had direct effects on adolescent conflict-coping styles. However, mother-adolescent communication had an indirect effect on conflict-coping styles, mediated by adolescent optimism. Adolescents who had open communication with mothers displayed higher levels of optimism, which led to more positive conflict-coping styles. In addition, multigroup analyses revealed that there were significant gender differences in direct and indirect effects. For boys, mother-adolescent communication directly influenced adolescent conflict-coping styles; however, father-adolescent communication did not directly or indirectly affect adolescent conflict-coping styles. For girls, neither father- nor mother-adolescent communication had direct effects on conflict-coping styles; only optimism had a significant effect on conflict-coping styles. Conclusion: The findings from this study suggest that communication with mothers and fathers have different effects on adolescents' conflict-coping styles. These findings have implications for future research and practice by emphasizing the importance of parent-adolescent communication and optimism in designing conflict-coping programs for adolescents.

• 아동학회지
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• 제38권2호
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• pp.149-164
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• 2017

Objective: The purpose of the study was to examine the direct effects of parent-adolescent communication and its indirect effects through adolescent friendship quality on happiness among both middle and high school students. Methods: Participants in this study were 1,126 adolescents (667 middle school students and 459 high school students) in Seoul and Gyoung-gi Do. Data were collected through self-report questionnaires for adolescents, which included measures of parent-adolescent communication, friendship quality and happiness. Data were analyzed by t-tests, correlations, and SEM using SPSS 22.0 and Mplus 6.0. Results: For middle school students, father-adolescent communication had direct and indirect effects on happiness. However, mother-adolescent communication did not directly or indirectly affect adolescent happiness. Specifically, only father-adolescent communication had an significant indirect effect through friendship quality on adolescent happiness. For high school students, father-adolescent communication had direct effects on happiness, while mother-adolescent communication had significant indirect effects on adolescent happiness via friendship quality. Conclusion: This study underscores the importance of parent-adolescent communication and friendship quality in predicting adolescent happiness with differences in direct and indirect paths between middle and high school students. These findings emphasize the role of parent-adolescent communication and friendship quality in developing programs to improve the happiness of adolescents.

• 한국정보통신학회논문지
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• 제5권4호
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• pp.668-675
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• 2001

최근, 상업적인 pcs시스템은 매우 발전되어 있으며, 결국 차세대 이동통신은 멀티미디어 서비스를 제공하는 IMT-2000에 의해 실현될 것이다. 그러므로 , 새로운 형태의 수신 시스템 연구가 활발히 진행되고 있고, 이중하나가 Direct conversion 방식이다 Direct conversion은 차세대 이동통신 시스템에 필요한 저전력, 소형, MMIC, 저가에 적합한 방식이다. 이 시스템을 사용할 경우 DC-offset의 문제가 발생하게 된다. DC-offset은 시스템에서 주파수 합성기의 누설신호에 의해 원하는 신호의 증폭을 억압한다. 본 논문에서 DC-offset을 제거하는 방법에 대해 고려한다. DC-offset의 제거법에는 AC-coupling, 대용량 capacitor, DC-feedback loop, DC-free coding의 4가지 방법이 있다. 이중에서 AC-coupling법은 가장 간단하며, DC-feedback법은 최고의 성능을 가진다. AC-coupling법과 DC-feedback법을 HP사의 ADS를 사용하여 시뮬레이션 하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.310-313
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• 2003

This paper is proposed new fuzzy controller for high performance of interior permanent magnet synchronous motor (IPMSM) drive New fuzzy controller take out appropriate amounts of accumulated control input according to fuzzy described situations in addition to the incremental control input calculated by conventional direct fuzzy controller. The structures of the proposed controller is motivated by the problems of direct fuzzy controller. The direct controller generally give inevitable overshoot when one tries to reduce rise time of response especially when a system of order higher than one is under consideration. The undesirable characteristics of the direct fuzzy controller are caused by integrating operation of the controller, even though the integrator itself is introduced to overcome steady state error in response. Proposed controller fuzzy clear out integrated quantities according to situation. This paper attempts to provide a thorough comparative insight into the behavior of IPMSM drive with direct and new fuzzy speed controller. The validity of the comparative results is confirmed by simulation results for IPMSM drive system.

• 한국인터넷방송통신학회논문지
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• 제14권3호
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• pp.13-19
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• 2014

노트북, 태블릿, 스마트폰 등 모바일 기기들의 성능 향상으로 인하여 임의의 장소에서의 그룹 회의를 진행하는 사람들이 많아지고 있다. 그러나 회의 참석자들이 근거리에 위치하고 있음에도 불구하고 참석자들 간의 데이터의 교환은 셀룰러 망을 이용하여 이루어지고 있다. 이는 불필요하게 셀룰러망에 부하를 가중시키는 원인이 되어 데이터의 송수신 지연을 발생시키고 원활한 회의의 운영 및 일반 모빌 통신 사업자의 통화 품질을 저하시키는 원인이 된다. 이러한 문제를 해결하기 위하여 본 논문에서는 Wi-Fi Direct 기술을 이용하여 근거리 통신기기들 간의 셀룰러 망을 사용하지 않고 회의 참석자들간 직접 통신을 수행할 수 있는 안드로이드 어플리케이션을 개발하고 그 방법에 대하여 소개한다.

• 대한가정학회지
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• 제48권7호
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• pp.33-48
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• 2010

The purpose of this study was to explore the effects of family structure(parentral marital status and socioeconomic status), parental communication, academic problems, and peer relationship on juvenile delinquency. The participants were 1009 middle school and high school students in Seoul city and Gyeonggi Province. The major results were as follows: 1) Parental marital status(divorced/seperated) had both direct and indirect positive effects and lower class in socioeconomic status had an indirect positive effect on academic problems and peer relationship on juvenile delinquency rates. 2) Open maternal communication had a direct negative effect on juvenile delinquency rates. However, open paternal communication had both direct and indirect negative effects. 3) Academic problems had both direct and indirect positive effects on juvenile delinquency rates. 4) Peer relationship had a direct positive effect on juvenile delinquency rates. 5) The level of effects that each variable had differed by delinquency types. Based on these results, implications for preventing juvenile delinquency were discussed.

• Human Ecology Research
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• 제53권5호
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• pp.531-542
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• 2015

This study examined the structural relationships among 4- and 5-year-old children's playfulness, communication skills, and creative characteristics. This research analyzed the direct and indirect influence of child's playfulness on communication skills and creative characteristics. The study subjects were 249 children who attend kindergartens located in the Seoul and Gyeonggi-do area. A survey questionnaire was distributed to the children's mothers and teachers. The sample was analyzed using SPSS 21.0 and AMOS 21.0 program. The parameters were estimated by maximum likelihood method. The significance of indirect effect was tested by bootstrapping at .05 level. The results of this study were: (1) in both ages 4 and 5, playfulness had a direct and positive influence on communication skills, (2) in both ages, communication skills had a direct and positive effect on creative characteristics, and (3) the 5-year-old children's playfulness had a direct effect on creative characteristics, the 4-year-old children's playfulness did not exert direct influence onto creative characteristics. Communication skills 5-year-old children were seen to precipitate a partial mediation effect between playfulness and creative characteristics. At age 4, communication skills played a full mediation variable role between playfulness and creative characteristics. Discussions include suggestions to prosper creative characteristics through enhancing a child's playfulness and communication skills.

• Journal of information and communication convergence engineering
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• 제6권1호
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• pp.91-93
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• 2008

To realize high-speed over GHz bps, it is needed to reduce and suppress the pulse width because of dispersion effect in fiber. We analyzed the performance and waveform due to chirping effect in fiber.