• The Journal of the Acoustical Society of Korea
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• v.29 no.4
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• pp.229-236
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• 2010

Phase coherent modulation techniques in underwater acoustic channel can improve bandwidth efficiency and data reliability, but they are made difficult by time-varying intersymbol interference. This paper proposes an adaptive equalizer combined with phase estimator which compensates distortions caused by time-varying multipath and phase variation. The experiment in the East sea demonstrates phase coherent signals are distorted by time-varying multipath propagation and the proposed scheme equalizes them. Bit error rate of BPSK and QPSK are 0.0078 and 0.0376 at 300 meter horizontal distance and 0.0146 and 0.0293 at 1000 meter respectively.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1994.06a
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• pp.447-452
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• 1994

• KIPE Magazine
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• v.13 no.6
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• pp.39-46
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• 2008

• Journal of the Korean Institute of Intelligent Systems
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• v.23 no.3
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• pp.196-201
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• 2013

In this paper, we propose an asynchronous and adaptive message passing scheme based on S-MAC for handling with the problem on energy efficiency in wireless sensor networks. The proposed scheme consists of a policy that differentiate transmission errors caused by packet collision or radio interference from congestion errors caused by buffer overflow and a method that adaptively controls the size of a fragment according to the variance of traffic loads. Especially, it presents a method that highly reduce the energy consumption by keeping the size of fragment not being excessively smaller than the one that may result in rapid increment of the total transfer time. Finally, with the simulation results we show that network throughput and delay are improved by using the proposed message passing scheme.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2004.04a
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• pp.29-33
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• 2004

본 논문에서는 인간과 엔터테인먼트 로봇의 상호작용을 위해, 동기(motivation)와 계층화된 감정(hierarchical emotion)에 기반한 행동결정 모델을 설계하였다. 감정모델은 계층화되고 학습 가능하도록 하여, 인간의 행동결정과 유사하게 동작하도록 하였다. 감정모델을 통해 로봇의 행동에 대한 인간의 반응이 학습되는데, 그 결과가 행동결정에 영향을 주어 로봇의 행동에 반영되도록 하였다. 감정모델과 함께 동기가 행동결정에 영향을 주는데, 초기에는 외부에서 주어지는 동기가 주로 행동을 결정하고, 감정모델이 학습될수록 점차 감정의 영향이 증가하여 동기와 계층화된 감정을 함께 고려하여 행동을 결정하도록 하였다. 그럼으로써, 인간과의 상호작용을 통해 정보를 축적하고 인간의 반응에 적응해나갈 수 있게 하였다

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.11
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• pp.104-113
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• 2016

This study was conducted to describe the relationship and influencing factors among college life adaptation, academic self-efficacy, and department satisfaction of freshman nursing students. There were 345 345 nursing freshman between November 30 and December 4 who participated in this study. The mean score of the college life adaptation, academic self-efficacy, and department satisfaction was $2.91({\pm}0.52)$, $2.79({\pm}0.60)$, and $3.55({\pm}0.47)$. The college life adaptation related with male group (p=.004), entering motivation (p=.027), friendship satisfaction (p<.001), first semester grade (p=.005), and academic self-efficacy related with male group (p=.040), entering motivation (p=.047), desired work (p=.015), friendship satisfaction (p=.014), first semester grade(p<.001), and department satisfaction related with entering motivation (p=.004), friendship satisfaction (p<.001), and first semester grade (p=.002) all showed statistical significance. There was a significant positive correlation among college life adaptation, academic self-efficacy (r=.223, p<.001), and department satisfaction (r=.342, p<.001). A significant and positive correlation was found between academic self-efficacy and department satisfaction (r=.218, p<.001). Department satisfaction was largely influenced by the college life adaptation. The regression model explained 23.1% of college life adaptation. In conclusion, this study showed that college life adaptation of freshman nursing students was correlated with academic self-efficacy and department satisfaction. Moreover, to increase the college adaptation of nursing freshman, it is necessary to develop educational programs to improve academic self-efficacy and department satisfaction.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.3C
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• pp.83-91
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• 2005

We analyze the performance of an adaptive hybrid search code acquisition algorithm for direct-sequence code division multiple access (DS-CDMA) systems under slowly-moving mobile environments. The code acquisition algorithm is designed to provide the desired feature of constant false alarm rate (CFAR) to cope with nonstationarity of the interference in CDMA forward links. An analytical expression for the mean acquisition time is first derived and the probabilities of detection, miss, and false alarm are then obtained for frequency-selective Rayleigh fading environments. The fading envelope of a received signal is assumed to be constant over the duration of post-detection integration (PDI), considering slow fading environments. Finally, the performance of the designed code acquisition algorithm shall be evaluated numerically to examine the effect of some design parameters such as the sub-window size, size of the PDI, decision threshold, and so on, considering cdma2000 environments.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.10A
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• pp.922-929
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• 2005

This paper proposes an adaptive pilot beacon equipment for mobile communication systems based on direct spread spectrum technology which generates the pilot channel for handoff between base stations by using the information acquired from the downstream wireless signal regarding the overhead channel information. Such an adaptive pilot beacon equipment will enable low power operation since among the wireless signals, only the pilot channel will be generated and transmitted. The pilot channel in the downstream link of the CDMA receiver is used to acquire time and frequency synchronization and this is used to calibrate the offset for the beacon, which implies that time synchronization using GPS is not required and any location where forward receive signal can be received can be used as the installation site. The downstream link pilot signal searching within the CDMA receiver is performed by FPGA and DSP. The FPGA is used to perform the initial synchronization for the pilot searcher and DSP is used to perform the offset correction between beacon clock and base station clock. The CDMA transmitter the adaptive pilot beacon equipment will use the timing offset information in the pilot channel acquired from the CDMA receiver and generate the downstream link pilot signal synchronized to the base station. The intermediate frequency signal is passed through the FIR filter and subsequently upconverted and amplified before being radiated through the antenna.

• Journal of the Korean Society of Child Welfare
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• no.54
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• pp.173-197
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• 2016

This study aims to examine developmental trajectories and predictor variables of problem behaviors and school adjustment trajectories among children from low-income families using latent growth modeling. The data was collected from the 2nd year to the 4th year (2012-2014) of a community child center child panel survey conducted by the National Youth Policy Institute. The major findings are as follows. First, as the grade went up, the problem behaviors of children from low-income families increased while school adjustment decreased. Second, multi-level domains, such as individual, school, and family variables influenced school adjustment trajectory, while only individual variables, such as depression, isolation, and motivation for achievement influenced problem behavior trajectory. Third, common protective factors between problem behaviors and school adjustment trajectories were motivation for achievement in and satisfaction of the community child center. Common risk factors between problem behaviors and school adjustment trajectories were isolation and aggression. Based on the results, the implications for child welfare practices were discussed.

• Journal of the Korea Society of Computer and Information
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• v.26 no.3
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• pp.137-142
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• 2021

The goal of this study is to investigate how YouTube use motivation such as perceived usefulness and perceived enjoyment affect the compulsive YouTube usage and academic adjustment of college students. To this end, a research model was established and 113 response data obtained by conducting a questionnaire survey on college students in Seoul were used for structural model analysis. The results of this study can be summarized as following. First, perceived usefulness has a positive effect on academic adjustment. Second, compulsive YouTube usage has a negative effect on academic adjustment. Third, perceived enjoyment was identified as a factor that plays a role like pharmakon. The findings suggest the necessity of learning strategies that control the degree of perceived enjoyment as well as the instrumental use of perceived usefulness in order to improve the academic adjustment of college students.