• 한국통신학회논문지
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• 제21권3호
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• pp.771-783
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• 1996

8단자 가변임피던스 전자파 발생장치(8P-VWIG:8Ports-Variable Wave Impedance Generator)에 대한 설계 기술에 대해 나타내고, 내부에서 유기뇌는 전자기장 및 특성임피던스에 대한 수치해석, 일정한 특성임피던스를 갖는 구조에 대해 간단하게 추적할 수 있는 수치알고리즘에 대해 나타내었다. 또한 특정 구조에 대한 균일도 평가결과와 내부 전자계 분포, 그리고 그 응용으로서 EMS 측정시스템에 대한 간단한 소개를 나타내었다. 8P-VWIG는 기존 간이 EMI/EMS 시설들에 비해 시험공간의 활용도가 좋고, 수직 수평 분극 조성이 자유로운 장점을 가지고 있다. 제작된 8P-VWIG는 정재파비로 측정된 제 1공진이 152.1MHz에서 발생하고, $50{\Omega}$ 임피던스 정합 시스템으로 동작하도록 한 8채널의 다중전송선로 구조를 갖는다.

• 소음진동
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• 제6권5호
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• pp.679-684
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• 1996

The Instrumental Variable Method(IVM), modified from least square algorithm, is applied to parameter identification of a noise contaminated bearing test rig. The signal to noise ratio included in Frequency Response Function(FRF) can cause significant errors in parameter identification. Therefore, among several candidates of parameter identification method, results of the applied IVM were compared with noise-contaminated least square method. This study shows that the noise-contaminated least square method can have indonsistent accuracy depending on the degree of noise level, while the IVM has robuster performance to signal to noise ratio than least square method.

• 대한가정학회지
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• 제51권2호
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• pp.195-206
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• 2013

This study was conducted in order to investigate the variables that relate and affect the internalizing and externalizing problems of multicultural children. 159 multicultural children in the $3^{rd}{\sim}6^{th}$grade were selected from elementary schools in Gwangju and the Jeollanamdo area. The data was analyzed by using the frequency, Cronbach's ${\alpha}$, t-test, ANOVA, Pearson's correlation and hierarchical regression by SPSS 12.0 program. The results were as follows: first, the internalizing problems were different according to the socio-demographic variable: (gender, subjective economic level), multicultural characteristic variable: (mother's communication ability, likability of mother's nationality, etc.), parent-child relationship variable: (relationship with mother, relationship with father) and social support variable: (peer support, teacher support). Further, the externalizing problems were different according to the socio-demographic variable: (gender), multicultural characteristic variable: (mother's nationality, mother's communication ability, etc.), parent-child relationship variable: (relationship with mother, relationship with father) and social support variable: (peer support, teacher support). Second, the influential variables regarding the internalizing problems were children's stress from cultural adaptability and the likability of the mother's nationality of the multicultural characteristic variable group, peer support of the social support variable group and the subjective economic-level of the socio-demographic variable group. Moreover, the influential variable on the externalizing problems was children's stress from the cultural adaptability of the multicultural characteristic variable group. The most influential variable of such variables was children's stress from cultural adaptability of the multicultural characteristic variable group. The results of this study will provide information for the development of educational and therapeutic intervention program for multicultural children.

• Journal of Biosystems Engineering
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• 제26권2호
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• pp.105-114
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• 2001

Modulus of elasticity, modulus of rigidity, damping ratio, and natural frequency of three varieties of boxthorn (Lycium chinense Mill) (Cheongyang #2, Cheongyang gugija, and Cheongyang native) branches were analyzed. Modulus of elasticity and modulus of elasticity and modulus of rigidity of the boxthorn branch was determined using standard formula after simple beam bending and torsion test, respectively, using an universal testing machine. Damping ratio and natural frequency of branches were determined using a system consisted of an accelerometer, a PC equipped with A/D converter, and a software for data analysis. Relationship between the elastic modulus and branch diameter in overall varieties and branch types showed a good correlation (r -0.81). There was, however, no correlation between torsional rigidity and branch diameter. The internal damping results were highly variable and the overall range of the damping ratio of the boxthorn branch was 0.014-0.087, which indicated that the branch was a lightly damped structure. The natural frequency of the boxthorn branch was in the range of 89-363 rad/s for the overall varieties and branch types. A good correlation (r 0.82) existed between the natural frequency and branch diameter in overall varieties and branch type.

• 소음진동
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• 제8권4호
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• pp.683-689
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• 1998

A control algorithm for multi-stage dampers is developed based on the mode skyhook control concept, and implemented on the full vehicle system environment. The test vehicle system is equipped with the real time controller, four-stage variable dampers and sensors. The real time controller is developed using a digital signal processor(DSP), digital I/O, A/D and D/A converters. The dampers are driven by the electromagnetic actuators of less than 20 msec response time. The sensors include accelerometers, relative displacement transducers, and steering wheel rate sensors, etc. Through a series of tests in laboratory and proving ground, the performance of the semi-active suspension system is evaluated and it is shown that the vehicle dynamic characteristics is improved with the developed damping system. Futhermore, the parameter tuning methods to enhance vehicle dynamic performance are propsoed.

• 한국의상디자인학회지
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• 제4권2호
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• pp.31-45
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• 2002

The purpose of this study was designed to investigate if self-monitoring variable among various individual trait theories and demographic variable would be variables which can explain about the importance differences of consumer service level of retailing in the garment product. The survey was conducted from Feb, 6 to 16, 2002. For this survey, the 118 data were analysed with spss window 9.0 version and Cronbach's, Factor analysis, one-way ANOVA, Duncan test, Frequency, mean, percentage were applied. The results of this study were as follows; 1. Consumer service was classified in attitude/confidence/expert knowledge of salesperson, product display, product information, product assortment, shopping environment, lighting setup. 2. As a result of analyzing the importance differences per consumer service dimension depending on self-monitoring levels, it was not significant differences. 3. As a result of analyzing the importance differences per consumer service dimension depending on demographic variables, it was not significant differences.

• 가족자원경영과 정책
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• 제5권1호
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• pp.1-13
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• 2001

The purpose of this study was not only to identify real-life conditions of Korean-Chinese in Korea(clothing habits, eating habits, housing habits, economic life and leisure activities) but also to reveal the related variables that shall affect life quality. The subjects were selected from Korean-Chinese in Korea related to ‘Compatriots House’. The survey was conducted from June 20th to July 5th, 2000. A total of 225 questionnaires out of 350 were used as the final data analysis. All data were analyzed using the SAS/PC for frequency, percentage, F-test and Regression analysis. The study revealed the following results. 1. Significant differences were found in life quality of Korean-Chinese in Korea according to age(p<.05), optimum income (p<.001), health condition(p<.001), education level(p<.005), and entry motivation(p<.05). 2. Variable such as optimum income(β=.334) education level(β=-.190), monthly income(β=.170), health condition(β=.151), and self-esteem(β=.133) affected life quality of Korean-Chinese in Korea. Korean-Chinese’s life quality was explained by these variable(35%). The optimum income variable was the primary influential factor.

• International Journal of Advanced Culture Technology
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• 제10권3호
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• pp.85-92
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• 2022

In previous private education expenses were concentrated only on expenses for elementary, middle, and high school students. Therefore, it is difficult to understand the actual condition of preschool children's private education expenses. To solve this problem, we analyze the 2013 and 2020 data of the Korea Welfare Panel to confirm the private education expenditures of pre-school children. Also, we examine the differences and changes in private education expenditures according to household variables. We selected the household variable as the socio-demographic variable of the study subject. We defined the household variable as the area and income of the household. We show the actual results of private education expenses for household variables using frequency analysis, descriptive statistical analysis, t-test, and one-way ANOVA of SPSS 27.

• 한국항행학회논문지
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• 제25권5호
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• pp.363-369
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• 2021

본 논문에서는 텔레메트리 시스템을 위한 가변 컷 오프 주파수 및 가변 샘플레이트 특성을 지니는 저면적 다채널 디지털 필터구조를 제안한다. 제안하는 디지털 필터는 임의의 컷 비율에 대해 필터 뱅크의 추가적인 설계 없이 컷 오프 주파수와 샘플레이트를 가변적으로 사용할 수 있는 필터 뱅크를 구현함으로써 하드웨어 면적을 줄일 수 있었다. 또한, 멀티플렉서 (MUX; Multiplexer) 컨트롤을 통해 통과하는 필터의 개수에 따라 샘플레이트를 가변적으로 선택할 수 있는 구조를 제안한다. 제안하는 디지털 필터는 Quartus의 FIR (finite impulse response) IP (intellectual property)의 TDM (time division multiplexing)을 이용함으로써, TDM을 사용하지 않았을 때보다 면적이 큰 DSP (digital signal processing) 블록을 80개에서 1개로 줄일 수 있었다. Kaiser 창 함수를 이용하여 Matlab을 통해 필터의 차수와 계수를 계산하였으며, VHDL (very high speed integrated circuits hardware description language)을 통해 하드웨어로 구현하였다. 텔레메트리 시스템에 적용 후, 실험 결과를 통해 제안하는 디지털 필터가 정상적으로 동작하고 있음을 확인하였다.

• 해양환경안전학회지
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• 제25권1호
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• pp.117-121
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• 2019

본 연구에서는 국내외적으로 환경문제 및 에너지절감의 일환으로 직류배전시스템을 선박에 적용하려는 연구 및 실증이 활발히 수행되고 있으며, 발전기를 직류배전시스템에 적용하기 위해서는 가변속 엔진을 적용하여 저부하 영역에서 발전기의 엔진 회전수를 줄여 연료소모량을 절감할 수 있는 방안이 제시되고 있다. 본 논문에서는 기존의 디젤발전기를 이용하여 발전기 컨트롤러, 가버너, AVR을 이용하여 직류배전용 가변속발전기를 구성하였으며, 발전기의 시스템 구성 방법, 가변속 발전에 따른 전력품질 시험(전압 및 주파수 변동특성, 부하변동 특성)을 통해 가변속 발전기의 전력특성을 분석 하였다. 가변속 발전기의 전압(250 ~ 440 VAC) 및 주파수(34 ~ 60 Hz)는 정격의 60 ~ 100 %로 구성하였으며, 엔진은 1100 ~ 1800 rpm 범위에서 운전되도록 설정 하였다. 부하변동에 따라 발전기의 엔진속도를 변경시켜서 발전기 출력의 전압, 전류, 주파수가 전력량에 따라 안정적으로 변동되는 것을 확인하였다.