• 한국산학기술학회논문지
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• 제9권4호
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• pp.918-923
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• 2008

본 논문에서는 전극들이 동일한 평면상에 놓이고, Gap에 의하여 유전간격을 형성한 새로운 구조의 임베디드 캐패시터(EC)를 제안하였다. 제안된 EC의 이름을 Gap type EC라고 하고, 유한요소법으로 그 특성을 평가하였다. Cap type EC의 공진주파수는 기존의 EC에 비하여 고주파 대역으로 이동되었다. 또한 공진주파수는 전극의 크기와 두께에 따라 변화되었다. Gap type EC는 Gap size가 $50{\mu}m$일 때 $55pF/cm^2$의 정전용량을 나타내었다. 이 값은 기존의 EC가 나타내는 $25pF/cm^2$에 비하여 높은 값이다. 따라서 본 논문에서 제안한 Gap type EC는 고주파 디커플링 용도로 충분히 사용될 수 있을 것이다.

• 한국전자파학회논문지
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• 제29권2호
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• pp.142-145
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• 2018

본 논문에서는 전원보드의 공통모드 노이즈 감쇠를 위한 디커플링 커패시터 회로를 효율적으로 시뮬레이션할 수 있는 구조분할 해석기법을 제시한다. 제시하는 구조분할 해석기법이 적용된 전원보드 설계에서는 보드를 두 부분으로 구조분할하였으며, 분할된 구조와 커패시터 회로의 임피던스 파라미터를 재결합하기 위한 방법을 제시하였다. 구조분할 해석기법을 적용함으로써 공통모드 노이즈 감쇠 시뮬레이션에 수행되는 시간을 46 % 이상 단축하였다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2006년도 춘계학술대회
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• pp.387-390
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• 2006

We report here that under strong attacksof external $CH_4$ guest molecules the sII and sH methane hydrates are structurally transformed to the crystalline me framework of sI, leading to favorable change of the lattice dimension of the host-guest networks. The High Power Decoupling $^{13}C$ NMR and Raman spectroscopies were used to identify structure transitions of the mixed $CH_4+C_2H_6$ hydrates (sIIl) and hydrocarbons (methylcyclohexane, isopentane) + $CH_4$ hydrates (sH). The resulting spectra indicate that most of the synthesized sII and sH hydrates were transformed to methane hydrate of sl under 110 bar and particularly the coexistence of sl with sII or sH appear according to the surrounding methane-rich gas conditions. The present findings might be expected to Provide rational evidences regarding the preponderant occurrence of naturally-occurring sI methane hydrates in marine sediments.

• Structural Engineering and Mechanics
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• 제83권6호
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• pp.729-744
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• 2022

In this paper, an analytical formulation is proposed to predict the vertical vibration response due to the pedestrian walking on a footbridge considering the human-structure interaction, where the footbridge and pedestrian are represented by the Euler beam and linear oscillator model, respectively. The derived coupled equation of motion is a nonlinear fourth-order partial differential equation. An uncoupled solution strategy based on the combined weighted residual and perturbation method) is proposed to reduce the tedious computation, which allows the separate integration between the bridge and pedestrian subsystems. The theoretical study demonstrates that the pedestrian subsystem can be treated as a structural system with added mass, damping, and stiffness. The analysis procedure is then applied to a case study under the conditions of single pedestrian and multi pedestrians, and the results are validated and compared numerically. For convenient vibration design of a footbridge, the simplified peak acceleration formula and the idea of decoupling problem are thus proposed.

• 한국전자통신학회논문지
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• 제11권12호
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• pp.1209-1218
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• 2016

4대의 전동실린더를 이용하여 대형 유리판과 같은 부하를 신속하고 안전하게 이송하기 위해서는 동기오차가 허용된 범위 내에서 지속적으로 유지되어야 한다. 본 연구에서는 4대 이상의 전동실린더 간의 동기화에 적용 가능한 동기제어기법이 제안된다. 이 동기제어시스템은 디커플링 구조에 기반을 두고 있으며, 기준모델, 위치제어기 그리고 동기제어기로 구성된다. 기준모델은 각각의 실린더에 대해 상호 분리된 동기오차와 제어입력의 계산이 가능하도록 한다. I-PD형의 위치제어기는 각 실린더가 오버슈트와 입력포화를 일으키지 않고 지령을 추종하도록, 그리고 진상보상기형의 동기제어기는 루프정형을 통해 안정적으로 정밀한 동기가 되도록 설계 된다. 끝으로 토크외란이 인가된 상태에서도 4개의 실린더가 신속하고 안정적으로 동기를 유지하면서 목표지점에 도달됨을 시뮬레이션으로 검증한다.

• 소음진동
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• 제9권4호
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• pp.822-827
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• 1999

The reduction of booming noise level and improvement of sound quality in the vehicle interior have been major fields of vehicle NVH for many years. In order to reduce the booming noise this paper proposed a system variable, which takes account of mode shapes and natural frequencies of the structural-acoustic system, measurement points and excitation frequency. By simplifying the system variable, the major contributors of panels inculding roof, roof lining, wind shield glasses, doors and floor to booming noise at a specific frequency was experimentally found. Also the relationships between structural modes of roof lining, one of the major contributors, and acoustic modes of compartment cavity were investigated from the viewpoint fo structure-borne noise. In addition, the roof lining was modified structurally by applying marble sponge to the gap between roof and roof lining. Asthe result of structural modification, the booming noise was reduce at target frequency.

• International Journal of Precision Engineering and Manufacturing
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• 제7권2호
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• pp.56-59
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• 2006

A vibrational model of powder transfer equipment based on the lumped parameter method was developed, in which the operating motion consists of surging, bouncing, and pitching. After decoupling the equation of motion, the vibrational excitation source of the pitching motion was removed. So the designers are able to plan the optimum design to adjust the motion trajectory of the powder transfer equipment. That is, a procedure to adjust the motion trajectory of powder transfer equipment by changing design specifications such as the installation position, the direction of the motor, the driving speed, the mass unbalance, the stiffness coefficient, and the installation position of the support spring, is presented in this paper. The powder transfer equipment manufactured according to the results of this study did not suffer fatigue destruction, since the maximum stress on the basket structure was sufficiently small.

• International Journal of Naval Architecture and Ocean Engineering
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• 제12권1호
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• pp.680-690
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• 2020

In ocean environment, the sound speed gradient of seawater has an important influence on far field sound propagation. The FEM/BEM is used to decouple the vibroacoustic radiation of the spherical shell, and the Green function of the virtual source chain is adopted for decoupling. For far field radiated Sound Pressure Level (SPL), the Beam Displacement Ray normal Mode (BDRM) is employed. The vibration and near-/far-field radiated SPL of spherical shell is analyzed in shallow sea uniform layer, negative/positive gradient, negative thermocline environment, and deep-sea sound channel. Results show that the vibroacoustic radiation of spherical shell acted at 300Hz can be analogous to dipole. When the radiated field of the spherical shell is dominated by large-grazing-angle waves, it can be analogous to vertically distributed dipole, and the far field radiated SPL is lower; while similar to horizontally distributed dipole if dominated by small-grazing-angle waves, and the far field SPL is high.

• Journal of Advanced Marine Engineering and Technology
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• 제34권8호
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• pp.1128-1134
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• 2010

본 논문은 수중 로봇용 새로운 구조의 300W급 BLDC모터 기반의 수중 추진시스템의 개발에 대한 것이다. FEM을 통한 수중추진체의 구조해석, 유동해석을 통한 프로펠러 설계 등의 구조설계를 하였다. 또한, 수중추진체의 커플링이 없고, 무감속기 형태의 새로운 구조에 대해 설명하였다. 설계 및 제작한 수중추진체의 성능시험을 육상 및 수중에서 수행하였고 그 결과를 기존의 고성능 제품과 성능을 비교하였다. 그 결과 개발한 시스템이 전방 및 후방 추력성능에서 각각 16%, 및 12%를 개선한 우수한 성능을 나타냄을 확인하였다.

• Advances in aircraft and spacecraft science
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• 제7권3호
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• pp.251-269
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• 2020

Euclid is an optical/near-infrared survey mission of the European Space Agency (ESA) to investigate the nature of dark energy, dark matter and gravity by observing the geometry of the Universe and the formation of structures over cosmological timescales. The Euclid spacecraft mechanical architecture comprises the Payload Module (PLM) and the Service Module (SVM) connected by an interface structure designed to maximize thermal and mechanical decoupling. This paper shortly illustrates the mechanical system of the spacecraft and the mechanical verification philosophy which is based on the Structural and Thermal Model (STM), built at flight standard for structure and thermal qualification and the Proto Flight Model (PFM), used to complete the qualification programme. It will be submitted to a proto-flight test approach and it will be suitable for launch and flight operations. Within the overall verification approach crucial mechanical tests have been successfully performed (2018) on the SVM platform and on the sunshield (SSH) subsystem: the SVM platform static test, the SSH structure modal survey test and the SSH sine vibration qualification test. The paper reports the objectives and the main results of these tests.