• 한국지반환경공학회 논문집
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• 제24권10호
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• pp.41-49
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• 2023

산악지역 및 경사지반과 같은 비대칭지반에 설치된 교각과 같은 구조물은 바람, 온도, 지진등의 다양한 하중을 받게 된다. 비대칭지반에 설치된 교각과 같은 구조물을 안정적으로 지지하기 위해 보편적으로 말뚝기초가 많이 사용되고 있다. 교각을 지지하는 말뚝기초의 거동은 다양한 하중조건에 의해 변화하게 된다. 특히 지진과 같은 동적하중이 작용하는 교각을 지지하는 말뚝기초의 거동을 분석하기 위해서는 지반-말뚝-구조물 상호작용이 검토되어야 한다. 지진이 작용하는 비대칭지반에 설치된 말뚝기초는 지반경사, 진동방향에 따른 지반저항력 차이, 지반 변위 등에 의해 말뚝기초와 지반의 동적 상호작용은 매우 복잡해진다. 본 연구에서는 비대칭지반으로 경사사모래지반의 소단에 설치된 상부구조물을 지지하는 무리말뚝의 동적거동에 경사지반의 기울기가 미치는 영향을 확인하기 위해 1g 진동대 모형실험을 수행하였다. 그 결과, 경사지반의 기울기가 증가함에 따라 말뚝캡, 상부구조물의 가속도는 감소하는 것으로 확인되었으며, 말뚝의 동적 p-y 곡선의 할선기울기는 감소하는 것으로 확인되었다.

• Structural Engineering and Mechanics
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• 제53권5호
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• pp.957-979
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• 2015

The present paper investigates the influence of the orientation of the ground-motion reference axes, the seismic incident angle and the seismic intensity level on the inelastic response of asymmetric reinforced concrete buildings. A single storey asymmetric building is analyzed by nonlinear dynamic analyses under twenty bi-directional ground motions. The analyses are performed for many angles of incidence and four seismic intensity levels. Moreover three different pairs of the horizontal accelerograms corresponding to the input seismic motion are considered: a) the recorded accelerograms, b) the corresponding uncorrelated accelerograms, and c) the completely correlated accelerograms. The nonlinear response is evaluated by the overall structural damage index. The results of this study demonstrate that the inelastic seismic response depends on the orientation of the ground-motion reference axes, since the three individual pairs of accelerograms corresponding to the same ground motion (recorded, uncorrelated and completely correlated) can cause different structural damage level for the same incident angle. Furthermore, the use of the recorded accelerograms as seismic input does not always lead to the critical case of study. It is also shown that there is not a particular seismic incident angle or range of angles that leads to the maximum values of damage index regardless of the seismic intensity level or the ground-motion reference axes.

• Structural Engineering and Mechanics
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• 제40권4호
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• pp.489-500
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• 2011

The elastic seismic response of plan-asymmetric multi storey steel-frame buildings is investigated under earthquake loading with particular emphasis on forward-rupture directivity and fling records. Three asymmetric building systems are generated with different torsional stiffness and varying static eccentricity. The structural characteristic of these systems are designed according to UBC 97 code and their seismic responses subjected to a set of earthquake records are obtained from the response history analysis (RHA) as well as the linear static analysis (LSA). It is shown that, the elastic torsional response is influenced by the intensity of near-fault ground motions with different energy contents. In the extreme case of very strong earthquakes, the behaviour of torsionally stiff buildings and torsionally flexible buildings may differ substantially due to the fact that the displacement envelope of the deck depends on ground motion characteristics.

• Molecules and Cells
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• 제39권7호
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• pp.524-529
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• 2016

Controlling the production of diverse cell/tissue types is essential for the development of multicellular organisms such as animals and plants. The Arabidopsis thaliana root, which contains distinct cells/tissues along longitudinal and radial axes, has served as an elegant model to investigate how genetic programs and environmental signals interact to produce different cell/tissue types. In the root, a series of asymmetric cell divisions (ACDs) give rise to three ground tissue layers at maturity (endodermis, middle cortex, and cortex). Because the middle cortex is formed by a periclinal (parallel to the axis) ACD of the endodermis around 7 to 14 days post-germination, middle cortex formation is used as a parameter to assess maturation of the root ground tissue. Molecular, genetic, and physiological studies have revealed that the control of the timing and extent of middle cortex formation during root maturation relies on the interaction of plant hormones and transcription factors. In particular, abscisic acid and gibberellin act synergistically to regulate the timing and extent of middle cortex formation, unlike their typical antagonism. The SHORT-ROOT, SCARECROW, SCARECROW-LIKE 3, and DELLA transcription factors, all of which belong to the plant-specific GRAS family, play key roles in the regulation of middle cortex formation. Recently, two additional transcription factors, SEUSS and GA- AND ABA-RESPONSIVE ZINC FINGER, have also been characterized during ground tissue maturation. In this review, we provide a detailed account of the regulatory networks that control the timing and extent of middle cortex formation during post-embryonic root development.

• Journal of Power Electronics
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• 제18권2호
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• pp.343-355
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• 2018

A wide-voltage-conversion range bidirectional DC-DC converter is proposed in this paper. The topology is comprised of one typical LC energy storage component and a special common grounded asymmetric H-bridge with four active power switches/anti-parallel diodes. The narrow output PWM voltage is generated from the voltage difference between two normal (wider) output PWM voltages from the asymmetric H-bridge with duty cycles close to 0.5. The equivalent switching frequency of the output PWM voltage is double the actual switching frequency, and a wide step-down/step-up ratio range is achieved. A 300W prototype has been constructed to validate the feasibility and effectiveness of the proposed bidirectional converter between the variable low voltage side (24V~48V) and the constant high voltage side (200V). The slave active power switches allow ZVS turn-on and turn-off without requiring any extra hardware. The maximum conversion efficiency is 94.7% in the step-down mode and 93.5% in the step-up mode. Therefore, the proposed bidirectional topology with a common ground is suitable for energy storage systems such as renewable power generation systems and electric vehicles with a hybrid energy source.

• Structural Engineering and Mechanics
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• 제29권5호
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• pp.505-530
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• 2008

This paper proposes the application of active multiple tuned mass dampers (AMTMD) for translational and torsional response control of a simplified two-degree-of-freedom (2DOF) structure, able to represent the dynamic characteristics of general asymmetric structures, under the ground acceleration. This 2DOF structure is a generalized 2DOF system of an asymmetric structure with predominant translational and torsional responses under earthquake excitations using the mode reduced-order method. Depending on the ratio of the torsional to the translational eigenfrequency, i.e. the torsional to translational frequency ratio (TTFR), of asymmetric structures, the following three cases can be distinguished: (1) torsionally flexible structures (TTFR < 1.0), (2) torsionally intermediate stiff structures (TTFR = 1.0), and (3) torsionally stiff structures (TTFR > 1.0). The even distribution of the AMTMD within the whole width and half width of the asymmetric structure, thus leading to three cases of installing the AMTMD (referred to as the AMTMD of case 1, AMTMD of case 2, AMTMD of case 3, respectively), is taken into account. In the present study, the criterion for searching the optimum parameters of the AMTMD is defined as the minimization of the minimum values of the maximum translational and torsional displacement dynamic magnification factors (DMF) of an asymmetric structure with the AMTMD. The criterion used for assessing the effectiveness of the AMTMD is selected as the ratio of the minimization of the minimum values of the maximum translational and torsional displacement DMF of the asymmetric structure with the AMTMD to the maximum translational and torsional displacement DMF of the asymmetric structure without the AMTMD. By resorting to these two criteria, a careful examination of the effects of the normalized eccentricity ratio (NER) on the effectiveness and robustness of the AMTMD are carried out in the mitigation of both the translational and torsional responses of the asymmetric structure. Likewise, the effectiveness of a single ATMD with the optimum positions is presented and compared with that of the AMTMD.

• 전기학회논문지P
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• 제60권2호
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• pp.53-55
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• 2011

The printed wide band monopole antenna having characteristics of dipole by modified coplanar wave guide(CPW) ground plane is presented. We are called a slot-arm printed monopole antenna and investigated the effect of the surface currents of the radiator on ground plane. The proposed antenna is treated as two asymmetric dipoles with the included angle of $90^{\circ}$ degrees which lie along Z-direction symmetrically. It is observed that the effect of the surface currents on the radiation patterns is similar to that of the corresponding dipole. The length and width of the ground plane correspond the radius and length of the dipole respectively. This approach is also valid to general printed monopole antennas. The simulation impedance bandwidth of the proposed antenna the range of 2.4 to 4.6 [GHz] for a voltage stand wave ratio (VSWR)${\leq}$2 and got pick gain of 6 [dBi]. So the proposed antenna is satisfied the requirement of the industry science medical (ISM) band operation.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 춘계 학술발표회 초청강연 및 논문집
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• pp.1260-1268
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• 2008

In case of deep excavation analysis, the theory of beam on elasto-plastic geo-material (elasto-plastic theory) can not consider the inclined ground layers appropriately. It is frequently assumed that the soil layers are parallel to the surface. However, the soil layers are generally inclined and even asymmetric. The common modelling of the asymmetric half section of the excavation system using the elasto-plastic theory, can lead differences from the real behaviour of ground, which has critical significance in case of deep excavation in urban area. In this study, an attempt to find appropriate modelling methods was made by carrying out a comparative study between the FEM and the elasto-plastic analyses. It is shown that in case of the upward-inclined soil profile the elasto-plastic theory may underestimate the performance of retaining structures.

• 전기학회논문지
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• 제57권8호
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• pp.1416-1421
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• 2008

A 10 dB branch line hybrid coupler included with defected ground structure (DGS) is proposed. In this contribution, a contact between the grounded metal housing and DGS is avoided, which has been a serious problem in applying DGS to high frequency circuits. An isolation between the metal housing and the DGS pattern is provided by inserting additional substrate between DGS and the metal package. Therefore, it is possible to design branch line hybrid couplers having highly asymmetric power dividing ratio using these DGS structure, which is demonstrated in this paper. The designed and fabricated branch line hybrid coupler using DGS is well packaged in a metal housing without touching the ground metal directly. The measurement is performed under realistic practical operating situations because it is packaged in a metal housing. The measured performances of the fabricated 10dB coupler shows a 1:9 asymmetric power dividing ratio at output ports, as predicted. In addition, the measured performances in terms of matching, isolation, and phase difference are in excellent agreement with the simulated characteristics.

• 항공우주시스템공학회지
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• 제10권3호
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• pp.39-43
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• 2016

In this paper, a wind-tunnel test is accomplished to investigate the roll characteristics of a variable-span wing flying inside a channel. The factors that affect the roll characteristics of the wing were identified by analyzing the measured data; accordingly, when the wing is flying without both the ground and sidewall effects, the asymmetric wing extension causes the roll moment. Both the ground and the sidewall can increase the roll moment, but when the wing is affected by both the ground and the sidewall, the roll moment does not increase as much as the case where the wing is only affected by the ground. Also, the aerodynamic characteristics of the flying wing inside a channel are the nonlinear function of the wing height and the gap between the wingtip and the sidewall, both of which should be considered in a study of the stability and the flight control of the wing-in-ground effect of the vehicle flying inside a channel.