• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2004년도 하계학술대회 논문집 C
• /
• pp.2014-2016
• /
• 2004

In order to obtain a low-loss ferroelectric phase shifter, the reflection-type phase shifter with ferroelectric defected ground structure (DGS) resonators has been designed in this paper. The proposed phase shifter is consist of a 3-dB $90^{\circ}$ branch-line hybrid coupler and terminated reflective circuit with tunable ferroelectric DGS resonator. The ferroelectric DGS unit structure can provide high Q resonator characteristic at high frequencies. The design parameters of equivalent circuit for the tunable DGS resonator are derived by using simple circuit analysis method and three-dimensional full wave finite element method. The fabricated phase shifter has an insertion loss of better than 3.4dB at 13.5GHz.

• Journal of electromagnetic engineering and science
• /
• 제14권1호
• /
• pp.15-24
• /
• 2014

A compact dual-band three-way metamaterial power divider is proposed that has three in-phase outputs. Fully printed composite rightand left-handed (CRLH) unequal and equal power dividers are first implemented for 900-MHz and 2.4-GHz bands with the power-division ratios of 2:1 and 1:1, respectively. An initial 1:1:1 power divider is then achieved by incorporating the input of the two-way equal block into an output of the unequal block, and trimming the interconnection parameters. The condition of an identical phase at the three outputs of the power divider is then met by devising a hybrid CRLH phase-shift line to compensate for the different phase errors at the two frequencies. This scheme is confirmed by predicting the performance of the power divider with circuit analysis and full-wave simulation and measuring the fabricated prototype. They results show agreement; the in-phase outputs as well as the desirable power-division are accomplished and outdo the conventional techniques.

• JSTS:Journal of Semiconductor Technology and Science
• /
• 제1권4호
• /
• pp.209-215
• /
• 2001

In this paper a method for analysis and modelling of coplanar transmission interconnect lines that are placed on top of silicon-silicon oxide substrates is presented. The potential function is expressed by series expansions in terms of solutions of the Laplace equation for each homogeneous region of layered structure. The expansion coefficients of different series are related to each other and to potentials applied to the conductors via boundary conditions. In the plane of conductors, boundary conditions are satisfied at $N_d$ discrete points with $N_d$ being equal to the number of terms in the series expansions. The resulting system of inhomogeneous linear equations is solved by matrix inversion. No iterations are required. A discussion of the calculated line admittance parameters as functions of width of conductors, thickness of the layers, and frequency is given. The interconnect capacitance and conductance per unit length results are given and compared with those obtained using full wave solutions, and good agreement have been obtained in all the cases treated

• 한국항공우주학회지
• /
• 제33권5호
• /
• pp.79-86
• /
• 2005

기체-액체형 분사기를 사용하는 고성능 로켓엔진을 위하여 공명기로서의 분사기의 역할을 연구하였다. 단일 분사기가 장착된 연소기에서의 음향 거동을 상온 선형 음향해석을 통해 조사하였다. 음향감쇠 효과는 분사기 길이에 따른 감쇠인자를 통해 정량화되었다. 계산 결과, 분사기는 음향 감쇠에 있어 큰 역할을 하며, 최적의 분사기 길이는 감쇠시키고자 하는 음향 주파수에 대한 반파장 길이에 해당함을 알 수 있었다. 배플이 장착된 연소기에서, 상온 조건과 실제 연소 상황의 조건을 설정하여 각 조건에 대해서 배플길이에 따른 최적 분사기 길이의 변화를 계산하여 제시하였다.

• 한국지반공학회지:지반
• /
• 제13권3호
• /
• pp.53-62
• /
• 1997

주파수영역 표면파기법 (SASW)을 수중지반탐사에 적용하기 위한 일련의 해석적 연구가 실시되었다. SASW실험으로 지반강도분포를 정밀히 예측하기 위해서는 실험조건, 고차모드의 영향, 응답파의 정리 기법 등, 실험결과에 영향을 미치는 모든 제반 요소들을 고려한 정확하고도 경제적인 이론분산곡선을 결정해야만 한다. 따라서, 본 논문에서는 수중 표면파의 이론분산곡선을 구하기 위한 해석기법들을 개발하고 그 이론적 배경을 설명하였다. 또한, 개발된 해석기법들을 수중지반에서 실제로 실시된 SASW실험결과의 분석에 적용하여 수중지반의 강도특성을 예측하는 예를 보였다. 이 결과로부터 개발된 해석기법들과 더불어서 수중지반탐사를 위한 SASW 실험방법의 적용성이 검토되었다.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2002년도 추계학술대회논문집
• /
• pp.62-67
• /
• 2002

It has been shown that the vibrational response of a tire can be represented by a set of decaying waves, each associated with a particular cross-sectional mode shape in the region near the contact patch. Thus, it can be concluded that tires can be effectively modeled as lossy waveguides. It has also been shown that the sound radiation from tires is mainly from the region close to the contact patch. In consequence, it may be computationally efficient to analyze tire vibration and sound radiation in the region close to the contact patch by using a hybrid finite element model in which the cross-section of a tire is approximated by 2-D finite elements while an analytical wave solution is assumed in the circumferential direction of the tire. In this article. a hybrid finite element was formulated based on a composite shell model. The dispersion relations for sample structures obtained by using the hybrid FE model were then compared with those obtained by using a full, three-dimensional FE model. It has been shown that the FE analysis made using the hybrid 2-D finite elements yields results in close agreement with the three-dimensional model.

• 복식문화연구
• /
• 제17권1호
• /
• pp.90-104
• /
• 2009

If people want to project a successful personal style, hair style might play a big role as well as clothing. The purpose of this study was to observe hair behavior according to demographic variables, and to analyze correlation between desired hair image and clothing image sought. Questionnaires were distributed to 600 females aged $20s{\sim}40s$, using a convenient sampling method. Only 556 reliable questionnaires were selected for statistical analysis. Correlation r, ANOVA and Chi-square were used to analyze the data, using the SPSS program. There was a significant association between hair style and occupation. Career woman preferred roll straight perm treated hair, students preferred general perm treated hair and full time house wives preferred general wave perm treated. The medium layer cut was the most preferred cut style. People want to give different accents in hair styling with occupation and age variable. Certain desired clothing image had a high correlation with desired hair style image. Those who people want to express sexy, and bohemian image through clothing, they also want to create those image in hair styling with a high correlation(r=0.683, r=0.704).

• 대한전자공학회논문지SD
• /
• 제41권4호
• /
• pp.29-40
• /
• 2004

본 논문에서는 유한 차분 시간 영역(FDTD, Finite Differential Time Domain)법과 완전 정합층(PML, Perfectly Matched Layer) 방법을 이용하여 반도체 다층 배선이 평행하게 인접하거나, 교차하면서 인접하는 구조뿐 아니라. 평행하게 인접하면서 다른 평면상에 두 배선이 존재하는 3차원 다층 배선 구조에 대한 컴퓨터 수치 분석 방법을 보고한다. 평행한 인접 배선 구조에서는 수평 거리를 변화시키면서 출력 결과를 비교하였으며, 교차한 인접 배선 구조에서는 수직 거리를 변수로 하여 시간 영역과 주파수 영역에서의 출력 결과를 정량적으로 비교하였다. 또한, 평행하게 인접하면서 다른 평면상에 두 배선이 존재하는 3차원 다층 배선 구조에 대해서는 수평 거리와 수직 거리를 각각 변화시켜 가면서 출력되는 누화 특성을 측정하고 비교하였다.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2011년도 제41회 하계 정기 학술대회 초록집
• /
• pp.142-142
• /
• 2011

Microwave diagnostics method for plasma science and engineering is vigorous research area for its good characteristics such as high sensitivity, reliability, and broad measurement spectrum from low density plasma to high density. We investigate mechanism of microwave probes (hairpin, impedance and absorbtionf probe) and apply it for interpretation of full transmitted spectrum of cutoff probe. Mechanism of the spectrum having same key roles of I-V curve of Langmuir probe is not exactly revealed yet in spite of its importance. This study elucidates physics behind it using a circuit model and E/M wave simulation. Circuit model reveals exact cut-off peak frequency taking account of a collision frequency and a plasma frequency and it enable precise diagnostics of plasma densty from low pressure to high pressre. Cut-off like peaks have been obstacle for choosing cut-off peak is analyzed by E/M simulation and one of cutoff like peaks made by probe holder used for acquire plasma density with cutoff peak applying the hairpin relation. Furthermore, phase difference method for plasma density is conducted. This method uses a single microwave frequency source and it is low-priced.

• Human Ecology Research
• /
• 제56권5호
• /
• pp.461-472
• /
• 2018

Using a sample of third grade middle school students from the forth wave of Children and Youth Panel Survey in 2012, the mediation effects of private educational expenditure between parenting styles and children's academic performance were investigated by applying factor, cluster, tobit, and two stage regression analysis. The major results were as follows. First, four types of parenting style were identified. The most frequent parenting style was ambivalent parenting (tiger parenting) which was followed by authoritative parenting. Second, compared to permissive parenting style, ambivalent, authoritative, and authoritarian parenting styles were significantly associated with more private educational expenditures. Third, more private educational expenditures were significantly associated with higher academic performance of children. I found both a full mediation effect of private educational expenditure for ambivalent and authoritarian parenting styles, and a partial mediation effect for authoritative parents. Authoritative parenting style has a negative moderating effect on the relationship between household income and private educational expenditure, along with a positive direct effect on the academic performance of children. The results suggested that an authoritative parenting style was related with higher academic performance of children with less private educational expenditures compared to other parenting styles. The results also implied that the public policies to enhance authoritative parenting style among parents would be effective to reduce household's private educational expenditures.