• 대한가정학회지
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• 제42권4호
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• pp.99-118
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• 2004

This study examined different individual and environmental factors that affect children's game addiction tendency. As individual variables, game user' motivation, self-control, and self-esteem were included in the analysis. As family variables, communications with mothers, parental control of children's computer use and parental internet use were examined, as school variables, school adjustment and teacher's supervision of children's computer use, and as peer variables, peer group's attitude toward computer games were used. The sample consisted of 994 fifth and sixth grade children. Statistics and methods used for the data analysis were Cronbach's alpha, frequency, percentage, two way ANOVA, Pearson's correlation and Hierarchical Regression. Several major results were found from the analysis. First, boys were addicted more than girls. No difference was found in the addiction tendency between the 5th graders and the 6th graders. Second, game users' motivation, that is, their interest-amusement motive, avoidance motive and aggressive motive, had a positive correlation with their game addiction tendency. However, self-control and self-esteem had a negative correlation with children's game addiction tendency. Third, problematic communications with mothers and parental control of children's computer use had a positive correlation with children's game addiction tendency. Open communications with mothers had a negative correlation with children's game addiction tendency. Fourth, school adjusaent had a negative correlation with children's game addiction tendency. And peer group's attitude towards computer games had a positive correlation with children's game addiction tendency. Fifth, low self-control, peer group's attitude towards computer games, children's interest-amusement motive, avoidance motive, aggressive motive, school lesson adjustment, parental control of children's computer use and school nile adjustment were important predicting variables of boy's game addiction tendency. Avoidance motive, low self-control, interest-amusement motive, peer group's attitude towards computer games, and parental control of children's computer use were important predicting variables of girl's game addiction tendency.

• 한국터널지하공간학회 논문집
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• 제11권1호
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• pp.71-83
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• 2009

숏크리트는 터널에서 적용되는 요요한 주지보재이다. 숏크리트의 품질평가는 터널의 안전한 시공과 효과적인 운영을 위한 핵심 요소이다. 숏크리트가 암반에 적절히 타설되었다 하더라도, 막장 및 벤치부에서의 발파, 수축, 지반의 변형 등으로 인해 숏크리트 균열발생 및 배면공동 등의 문제를 야기한다. 본 논문에서는 비파괴 시험인 충격 반항 기법(Impact-Echo) 및 지하레이다 탐사(GPR)를 이용하여 경임에 타설된 숏크리트 배면의 접착상태를 평가하고자 하였다. 기존의 수치해석 연구에 대한 검증과 더불어 현장 적용성에 대한 검토를 위해 실험적 연구를 수행하였다. 숏크리트의 접착상태는 완전 접착, 접착력 상실 및 공동 조건으로 구분할 수 있다. 실내 실대형 시험체에 이 세 가지 숏크리트 접착상태를 조사하였다. 충격반향시험으로부터 획득된 신호는 시간영역, 주파수 영역, 및 시간-주파수 영역에서 각각 분석되었다. 능동적 신호 처리 기법인 Short-Time Fourier Transform(STFT)을 이용하여 숏크리트 배면의 접착상태를 효과적으로 예측할 수 있었으며, 그 결과는 기존의 수치해석 연구로부터 획득한 신호특성과 잘 부합하였다. 숏크리트 배면의 접착상태가 불량할수록 다음과 같은 특징들을 나타낸다. 즉, 주파수 영역에서 자기스펙트럼밀도가 커지며, 기하학적 감쇠비는 감소하고, 시간-주파수 영역에서 윤곽선은 시간축에 평행한 형상을 나타내며, 숏크리트 두께가 얇을수록 그 공진시간이 길어진다. 또한 본 연구에서 제시한 상관계수를 이용하여 숏크리트의 접착상태를 정량적으로 평가할 수 있다. 본 연구 결과를 바탕으로 숏크리트의 접착상태를 평가할 수 있는 평가 기법 및 평가 기준을 제안하였다.

• 한국융합학회논문지
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• 제11권4호
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• pp.49-54
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• 2020

국가대표 여자 유도선수를 대상으로 스포츠 손상 발생률과 심박변이도 간의 상관관계를 알아보고자 하였다. 연구 참여자들은 자율신경 진단기(SA-6000)를 사용하여 심박변이도를 측정하였다. 평균 손상 발생률을 기준으로 스포츠 손상 발생률의 상위그룹과 하위그룹으로 분류하였으며, 두 그룹 간의 심박변이도를 알아보기 위해 독립표본 T-test와 스포츠 손상 발생 횟수와 심박변이도의 상관관계를 알아보기 위해 Pearson의 적률상관관계를 시행하였다. 심박변이도는 총 파워와 저주파에서 유의한 차이가 있었으며, 스포츠 손상 발생 횟수에 따른 심박변이도의 상관관계 분석에서도 총 파워와 저주파에서 유의한 차이가 있었다. 이러한 자료들은 향후 선수들의 스포츠 손상 예방프로그램을 만드는데 유용한 기초자료로 제공될 것으로 사료된다.

• 한국생활과학회지
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• 제15권1호
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• pp.31-44
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• 2006

This study examined relationships between children's aggression and the variables such as individual, family, and school adjustment. For this study, individual variables included age, self-esteem, and game-addiction tendency. Family variables included mother's controlling parenting, child-abuse, parents' marital conflict. As for school adjustment, teacher relations, peer relations, classroom and rule adjustment in school were examined. The sample consisted of 642 children of the fifth and sixth grade in Busan. Statistics and methods used for data analysis included frequency, percentage, Cronbach's alpha, factor analysis, two-way Anova, Pearson's correlation, and Hierarchical Regression. Several major results were found from the analysis: First, boys' aggression was higher than girls'. But no age difference was found in children's aggression. Second, game-addiction tendency had a positive correlation with children's aggression. In addition, self-esteem had a negative correlation with boys' aggression. Third, mother's controlling parenting had a positive correlation with children's aggression. Child abuse had a positive correlation with boys' aggression, and parents' marital conflict with girls' aggression. Fourth, teacher relations, peer relations, classroom and rule adjustment in school had a negative correlation with boys' aggression. In addition, rule adjustment in school had a negative correlation with girls' aggression. Fifth, game-addiction tendency, rule adjustment in school, self-esteem, mother's controlling parenting and teacher relations in school were important variables predicting boys' aggression. On the other hand, game-addiction tendency and rule adjustment in school were important variables predicting girls' aggression.

• 가정과삶의질연구
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• 제24권5호
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• pp.161-174
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• 2006

This study examined different individual and parental factors that affect children's achievement motivation. For an analysis, perceived competence, intrinsic locus of control were included in individual variables. For parental variables, parental support and achievement pressure and marital conflict were examined. The sample consisted of 561 fifth and sixth grade children. Statistics and methods used for the data analysis were Cronbach's alpha, Factor analysis, frequency, percentage, Pearson's correlation, and Hierarchical Regression. Several major results were found from the analysis. First, girl's achievement motivation was higher than boys. No age difference was found between fifth and sixth grade. Second, boy's and girl's achievement motivation had a positive correlation with perceived competence, intrinsic locus of control, parental support and achievement pressure but a negative correlation with parental marital conflict. Third, important variables predicting boy's and girl's achievement motivation were perceived academic competence, parental achievement pressure and perceived social competence. Important variables predicting boy's individual and social oriented achievement motivation were perceived academic competence and parental achievement pressure. On the other hand, important variables predicting girl's individual oriented achievement motivation were perceived social competence, perceived academic competence, intrinsic locus of control and parental achievement pressure. Important variables predicting girl's social oriented achievement motivation were parental achievement pressure, perceived academic competence and mother's support.

• Journal of Positioning, Navigation, and Timing
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• 제7권3호
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• pp.147-153
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• 2018

Jamming countermeasures are used to decrease or prevent the impact of intentional jamming applied to degrade the quality of information provided by a global navigation satellite system (GNSS) receiver. The maximum performance of jamming countermeasure can be obtained only when a proper technique is applied according to the type of jammer. This paper suggests a jamming identification technique for providing information regarding the type of jamming. The center frequency and bandwidth of jammer signal are inconsistent and may change according to time, and thus a spectral correlation function and wavelet coherence were considered in order to analyze the signal in the time and frequency space. Because the two characteristics derive different analysis results, two different identification techniques were suggested and the performances thereof were analyzed. Numerical results show that the two identification techniques have relative advantages and disadvantages as to time consumed and performance. The suggested methods can sufficiently identify the jammer before the GNSS receiver becomes inoperable because of jamming.

• Interaction and multiscale mechanics
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• 제1권1호
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• pp.53-81
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• 2008

The theory of microlocal analysis of hyperbolic partial differential equations shows that the energy density associated to their high-frequency solutions satisfies transport equations, or radiative transfer equations for randomly heterogeneous materials with correlation lengths comparable to the (small) wavelength. The main limitation to the existing developments is the consideration of boundary or interface conditions for the energy and power flow densities. This paper deals with the high-frequency transport regime in coupled heterogeneous structures. An analytical model for the derivation of high-frequency power flow reflection/transmission coefficients at a beam or a plate junction is proposed. These results may be used in subsequent computations to solve numerically the transport equations for coupled systems, including interface conditions. Applications of this research concern the prediction of the transient response of slender structures impacted by acoustic or mechanical shocks.

• 한국환경과학회지
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• 제9권5호
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• pp.385-388
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• 2000

Visibility reduction is a barometer of air pollution which people can notice easily. First of all we need to measure quantified visibility continuously in order to examine visibility reduction. Prevailing visibility is not practical to measure visibility depending on observer's expertness. Scattering visibility using Forward Scattering Meter(Belfort Visibility Sensor 6230) has been measured at Kwangan-Dong in Pusan and analysed since July 1998. According to the analysis the correlation coefficient(R) between prevailing visibility and scattering visibility was 0.7235. The visibility appeared that each frequency of poor visibility(under 6km) and good visibility(over 25km) was 10.6%, 9.7% on summertime in Pusan and the visibility range from 10km to 20km ranked high frequency as a half of whole ranges. The order of correlation coefficients between visibility an air pollutants are ranking CO. PM10 and NO2 that values are 0.5878, 0.5369,l 0.5284 respectively. In meteorolgical factor the case of poor visibility presented more weakly wind speed and higher relative humidity than the case of good visibility. The correlation coefficient between calculated visibility of multiple linear regression model and observed visibility was 0.7215. But the trend of calculated and observed visibility variation was similar with the exception of several good visibility cases.

• 대한안전경영과학회지
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• 제13권1호
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• pp.69-73
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• 2011

Questionnaire survey has been made for the above study. First, 65 question sheets have been distributed to railway operators and 55 sheets of them have been collected from them. SPSS 12.0 program package has been used to analyze those sheets concerning age, experience, school, background as a frequency analysis and t-test has been made to find out recognition level difference of a cheer response, depending on the operator's experience. T-verification has been made for two groups such as less than 10 years, and 10 years or more experience. Result from correlation analysis showed that there was no difference due to operators' experience.

• 대한전기학회논문지:시스템및제어부문D
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• 제54권9호
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• pp.521-530
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• 2005

In this paper, a new high resolution reflectometry scheme, time-frequency domain reflectometry(TFDR), isproposed to detect and estimate a fault in a transmission line. Traditional reflectometry methodologies have been achieved either in the time domain or in the frequency domain only. However, the TFDR can jump over the performance limits of the traditional reflectometry methodologies because the acquired signal is analyzed in time and frequency domain simultaneously. In the TFDR, the new reference signal and the novel TFDR algorithm are proposed for analyzing the acquired signal in the time-frequency domain. Because the reference signal of Gaussian envelop chirp signal is localized in the time and frequency domain simultaneously, it is suitable to the analysis in the time-frequency domain. In the proposed TFDR algorithm, the time-frequency distribution function and the normalized time-frequency cross correlation function are used to detect and estimate a fault in a transmission line. That algorithm is verified for real-world coaxial cables which are typical transmission line with different types of faults by the TFDR system composed of real instruments. The performance of the TFDR methodology is compared with that o( the commercial time domain reflectomeoy(TDR) experiments, so that concludes the TFDR methodology can detect and estimate the fault with smaller error than TDR methodology.