• Earthquakes and Structures
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• 제7권1호
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• pp.83-99
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• 2014

This study is devoted to estimate higher-mode effects for multi-story structures with considering soil-structure interaction subjected to decomposed parts of near-fault ground motions. The soil beneath the super-structure is simulated based on the Cone model concept. Two-dimensional structural models of 5, 15, and 25-story shear buildings are idealized by using nonlinear stick models. The ratio of base shears for the soil-MDOF structure system to those obtained from the equivalent soil-SDOF structure system is selected as an estimator to quantify the higher-mode effects. The results demonstrate that the trend of higher-mode effects is regular for pulse component and has a descending variation with respect to the pulse period, whereas an erratic pattern is obtained for high-frequency component. Moreover, the effect of pulse component on higher modes is more significant than high-frequency part for very short-period pulses and as the pulse period increases this phenomenon becomes vice-versa. SSI mechanism increases the higher-mode effects for both pulse and high-frequency components and slenderizing the super-structure amplifies such effects. Furthermore, for low story ductility ranges, increasing nonlinearity level leads to intensify the higher-mode effects; however, for high story ductility, such effects mitigates.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2006년도 공동학술대회 논문집
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• pp.51-59
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• 2006

서해안 조간대에서 24 channel 탐사기로 획득한 표면파 자료의 위상속도와 군속도를 구한다음, 이를 역산하여 그 결과를 비교하였다. 위상속도의 분산곡선은 tau-p stacking 방법에 의하여, 군속도의 분산곡선은 wavelet analysis와 Multiple Filtering Technique의 두가지 방법을 사용하여 구하였다. 위상속도의 오차가 군속도의 오차보다 더 큰 것을 확인하였다. 군속도의 경우, wavelet analysis가 Multiple Filtering Technique 보다 fundamental mode와 higher mode를 구분하는데 더 효과적이었다. 역산결과, 군속도의 fundamental mode와 1st higher mode 를 동시에 사용했을 때, 공간적 해상도가 가장 좋았다. 이연구는 천부 지반의 S파 속도 구조를 구하는데, 군속도의 higher mode를 포함한 군속도 분산곡선을 사용하는 것이 효과적임을 시사한다.

• 한국통신학회논문지
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• 제39C권4호
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• pp.380-386
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• 2014

본 논문은 Ku대역 모노펄스 위성추적을 위한 동축구조 도파관 고차모드 커플러를 제안하였다. 제안된 고차모드 커플러는 이동체 탑재용 위성추적시스템에 적용 가능하도록 소형/경량화를 위하여 동축구조의 도파관을 이용하였다. 기본모드 신호 추출을 위해 내측 원형도파관을 이용하였고, 고차모드 신호 추출을 위해 외측 원형도파관에 내어진 4개의 슬롯과 스텝 구조의 직사각형 도파관을 이용하였다. 제안된 고차모드 커플러의 모의실험 결과는 반사손실 및 삽입손실이 약 250 MHz의 대역폭(12.75~13.00 GHz)을 만족하며, 모노펄스 추적에 적용 가능한 기본모드 패턴 및 고차모드 패턴이 만족스럽게 생성된 결과를 확인하였다. 제안된 Ku대역 동축구조 도파관 고차모드 커플러는 고속 정밀추적이 요구되는 모노펄스 위성추적시스템에 이용될 것으로 기대된다.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2005년도 학술발표회 논문집
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• pp.153-160
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• 2005

A new nonlinear static analysis method, Effective Modal Pushover Analysis (EMPA) which can evaluate earthquake responses such as story drift and plastic rotation of plastic hinges addressing higher mode effects was developed. Unlike existing nonlinear static procedure based on properties of fundamental vibration mode, the EMPA performs nonlinear static analysis using multiple effective modes constructed by direct combination of natural vibration modes. Therefore higher mode effects can be efficiently considered. In the present study, procedures of the EPMA evaluating inelastic earthquake responese were established and the results were verified by nonlinear time history analysis. The EMPA can be applied to seismic evaluation of high-rise buildings and irregular buildings where higher mode effects become conspicuous.

• International Journal of Contents
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• 제16권1호
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• pp.44-56
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• 2020

The purpose of this study was to examine how the presentation mode (sequential- vs. simultaneous-mode) of information influences its evaluation. Three experiments revealed the interaction effect between the presentation mode and the valence of the product information. When respondents read about the positive aspects of the product, the evaluation was higher in the simultaneous presentation mode than in the sequential presentation mode. For negative product information, respondents' evaluation was higher in the sequential presentation mode than in the simultaneous presentation mode. The simultaneous presentation mode intensified the impact of the information valence on evaluation. This study proposed that the sequential and the simultaneous presentation modes prime high and low construal levels, respectively. The mediation analysis provides support for such a prediction. Finally, the mediating effect of construal levels in evaluation was shown to disappear when respondents focused on the product information for a longer duration, while the mediation effect remained when the response time was short.

• 대한기계학회논문집A
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• 제24권5호
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• pp.1314-1322
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• 2000

The acoustic property of reactive type single expansion chamber can be analyzed by traditional plane wave theory. This theory can be applied in low frequency range and has good performance. But this theory can't include higher order modes, therefore another method is essential to analyze acoustic filter in high frequency range. Many researcher suggested the method that can concern higher order modes, and their methods are using mode matching technique. But there is no method that can be applied to the analysis of single expansion chamber with arbitrary inlet/outlet duct position and numbers of higher order modes of inlet/outlet duct and middle chamber. In this paper, the method which can analyze single expansion chamber with arbitrary inlet/outlet duct position and numbers of higher order modes of inlet/outlet duct and middle chamber using fundamental mode matching technique, was suggested and the predictions by this method was compared with those by the finite element method, and the influence of inlet/outlet location to acoustic performance of single expansion chamber is investigated and explained by higher order mode effects.

• Computers and Concrete
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• 제25권3호
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• pp.273-282
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• 2020

A new seismic design methodology for precast concrete diaphragms has been developed and incorporated into the current American seismic design code. This design methodology recognizes that diaphragm inertial forces during earthquakes are highly influenced by higher dynamic vibration modes and incorporates the higher mode effect into the diaphragm seismic design acceleration determination using a first mode reduced method, which applies the response modification coefficient only to the first mode response but keeps the higher mode response unreduced. However the first mode reduced method does not consider effects of diaphragm flexibility, which plays an important role on the diaphragm seismic response especially for the precast concrete diaphragm. Therefore this paper investigated the effect of diaphragm flexibility on the diaphragm seismic design acceleration for precast concrete shear wall structures through parametric studies. Several design parameters were considered including number of stories, diaphragm geometries and stiffness. It was found that the diaphragm flexibility can change the structural dynamic properties and amplify the diaphragm acceleration during earthquakes. Design equations for mode contribution factors considering the diaphragm flexibility were first established through modal analyses to modify the first mode reduced method in the current code. The modified first mode reduced method has then been verified through nonlinear time history analyses.

• Journal of Advanced Marine Engineering and Technology
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• 제23권6호
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• pp.748-754
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• 1999

The acoustic performance of reactive type single expansion chamber can be calculated theoretically by plane wave theory. But higher order modes should be considered to widen the frequency range. Munjal has suggested the method for analyzing the acoustic properties of simple expansion chamber with taking into consideration of higher order mode of inlet/outlet. But his method cannot predict the acoustic properties exactly when the dimensions of inlet/outlet and expansion chamber have not integer multiples. In this paper the new method was suggested to overcome the shortcomings of Munjal's method The predictions by this method were also compared with those by the finite element method.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권11호
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• pp.5360-5376
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• 2017

In this paper, we study the cross-layer design for the AMC/HARQ-based wireless networks, and propose a new dynamic transmission-mode selection scheme to improve system spectrum efficiency. In the proposed scheme, dynamic thresholds for transmission-mode selection in each packet transmission and retransmission are jointly designed under the constraint of the overall packet error rate. Comparing with the existing schemes, the proposed scheme is inclined to apply higher modulation order at the first several (re)transmissions, which corresponds to higher-rate transmission modes thus higher average system spectrum efficiency. We also extend the cross-layer design to MIMO (Multi-input Multi-output) communication scenarios. Numerical results show that the proposed new dynamic transmission-mode selection scheme generally achieves higher average spectrum efficiency than the conventional and existing cross-layer design.

• 소음진동
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• 제9권2호
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• pp.340-347
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• 1999

The acoustic performance of reactive type single expansion chamber can be calculated theoretically by plane wave theory. But higher order model should be considered to widen the frequency range. Mode matching method has been developed to consider higher order modes, but very complicated algebra should be used. Munjal suggested a numerical collocation method, which can overcome the shortcomings of mode matching method, using the compatibility conditions for acoustic pressure and particle velocity at the junctions of area discontinuities. But the restriction of Munjal's method is that the ratio between the area of inlet(or outlet) pipe and that of chamber must be natural number. In this paper, the new method was suggested to overcome the shortcomings of Munjal's method. The predictions by this method was also compared with those by the finite element method and Munjal's method in order to demonstrate the accuracy of the modified method presented here.