• Computers and Concrete
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• 제18권2호
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• pp.179-199
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• 2016

The aim of this study is to investigate arrival direction effects of travelling waves on non-linear seismic response of arch dams. It is evident that the seismic waves may reach on the dam site from any direction. Therefore, this study considers the seismic waves arrive to the dam site with different angles, ${\theta}=0^{\circ}$, $15^{\circ}$, $30^{\circ}$, $45^{\circ}$, $60^{\circ}$, $75^{\circ}$, and $90^{\circ}$ for non-linear analysis of arch dam-water-foundation interaction system. The N-S, E-W and vertical component of the Erzincan earthquake, on March 13, 1992, is used as the ground motion. Dam-water-foundation interaction is defined by Lagrangian approach in which a step-by-step integration technique is employed. The stress-strain behavior of the dam concrete is idealized using three-dimensional Drucker-Prager model based on associated flow rule assumption. The program NONSAP is employed in response calculations. The time-history of crest displacements and stresses of the dam are presented. The results obtained from non-linear analyses are compared with that of linear analyses.

• Geomechanics and Engineering
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• 제7권2호
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• pp.149-164
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• 2014

One of the most advanced classes of techniques for ground response analysis is based on the use of Transfer Functions. They represent the ratio of Fourier spectrum of amplitude motion at the free surface to the corresponding spectrum of the bedrock motion and they are applied in frequency domain usually by FFT method. However, Fourier spectrum only shows the dominant frequency in each time step and is unable to represent all frequency contents in every time step and this drawback leads to inaccurate results. In this research, this process is optimized by decomposing the input motion into different frequency sub-bands using Wavelet Multi-level Decomposition. Each component is then processed with transfer Function relating to the corresponding component frequency. Taking inverse FFT from all components, the ground motion can be recovered by summing up the results. The nonlinear behavior is approximated using an iterative procedure with nonlinear soil properties. The results of this procedure show better accuracy with respect to field observations than does the Conventional method. The proposed method can also be applied to other engineering disciplines with similar procedure.

• 한국전자통신학회논문지
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• 제11권9호
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• pp.893-900
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• 2016

극점의 위치와 제동비의 변화에 따른 출력응답을 해석하였다. RLC 회로의 시스템 모델링과 출력응답을 단위계단함수와 정현파 입력에 따라 해석하였다. 프로그램으로 확인한 내용들이 이론을 이해하는데 도움이 되었는지를 설문으로 평가하였다. 조사에서 시스템의 전달함수를 해석하는 능력은 이해도가 높게 나타났다. 또한 매개변수 변화에 따른 출력응답 파형을 이해하는 능력도 높게 나타났다. 시간영역의 출력응답을 계산할 수 있다는 응답이 다소 낮게 나왔으며, 이는 부분분수의 조합이 어려웠던 것으로 분석된다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 D
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• pp.2206-2208
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• 2002

In this paper, using the communication port between PC(Personal Computer) and DC/STEP MOTOR DEVICE that movement and measurement of motor. Communication port used serial port and movement order transmits by communication port. Consequence of motor device movement displays to tile DC/STEP MOTOR DEVICE APPLICATION. This connection is using the serial port instead of parallel port faster than response time And this application is easier than existing application.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 춘계학술대회 논문집 센서 박막재료 반도체재료 기술교육
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• pp.51-54
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• 2002

Recently, due to its better photosensitivity in X-ray, the amorphous selenium based photoreceptor is used on digital direct method conversion material. Compared to other photoconductive material, amorphous selenium has good X-ray response characteristic and low leakage current. It has many parameters of detecting X-ray response on selenium. Among of them, it is well known that manufacture of a-Se is the most basic element. In this paper, we fabricated two types of amorphous selenium sample which had time variable. The one was fabricated continuous deposition sample and the other was step by step sample. Thickness of sample was $300{\mu}m$ and top electrode was evaporated gold. We investigated the leakage current and photo current of them and analysed their electrical characteristics. For analyzing morphology of samples, SEM and surface was pictured. We found that step by step deposition method could be applied for novel fabricating amorphous selenium film.

• 전기전자학회논문지
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• 제23권1호
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• pp.9-13
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• 2019

본 논문에서는 원가 절감을 위한 개선된 $165^{\circ}$ 12 스텝 제어를 고려한 브러시리스 DC 전동기의 최적화 설계에 대하여 논한다. 개선된 12 스텝 제어는 기존 제어의 도통각 $150^{\circ}$을 확장시켜 전동기의 출력을 향상 시킬 수 있다. 향상된 전동기 출력을 고려한 반응 표면법을 이용한 최적화 설계를 통해서 회전자, 고정자 및 영구자석의 부피를 감소시켜 원가절감이 가능한 설계를 제시한다. 제안된 설계는 기존 전동기의 요구 사양 및 효율 향상을 만족하고 기존 전동기 중량의 약 3.5%를 저감하였다. 유한요소법을 이용한 전자계 해석을 통해 최적화 설계의 타당성을 입증하였다.

• 한국해양공학회지
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• 제35권4호
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• pp.257-265
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• 2021

Many studies have been performed to predict a reliable and accurate stress-range distribution and fatigue damage regarding the Gaussian wide-band stress response due to multi-peak waves and multiple dynamic loads. So far, most of the approximation models provide slightly inaccurate results in comparison with the rain-flow counting method as an exact solution. A step-by-step study was carried out to develop new approximate spectral moments that are close to the rain-flow counting moment, which can be used for the development of a fatigue damage model. Using the special parameters and bandwidth parameters, four kinds of parameter-based combinations were constructed and estimated using the R-squared values from regression analysis. Based on the results, four candidate empirical formulas were determined and compared with the rain-flow counting moment, probability density function, and root mean square (RMS) value for relative distance. The new approximate spectral moments were finally decided through comparison studies of eight response spectra. The new spectral moments presented in this study could play an important role in improving the accuracy of fatigue damage model development. The present study shows that the new approximate moment is a very important variable for the enhancement of Gaussian wide-band fatigue damage assessment.

• 한국재난정보학회 논문집
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• 제9권4호
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• pp.503-510
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• 2013

최근 기후변화로 국지성 집중호우가 증가하고 있으며 이로 인한 산사태 발생도 증가하고 있는 추세이다. 또한 도시주거지역에서 발생한 산사태로 인하여 인명 및 재산피해가 증가하고 있다. 그러나 이러한 산사태를 대비하기 위한 표준매뉴얼은 작성되어 있지 않으며, 산림청에서 작성한 예방 대응 행동매뉴얼도 미흡한 실정이다. 이에 본 논문에서는 산사태 발생 및 피해 특징을 알아보고 방재 관련 전문가들을 대상으로 산사태 대비 SOP 작성을 위해 산사태 SOP 필요도와 활용도를 조사하였으며 활용 시 문제점을 알아보았다. 또한 산사태 주요 세부항목의 중요도를 알아보고, 산사태 SOP 활용을 위한 요구사항을 조사하였다. 조사결과는 대부분의 전문가들이 산사태 SOP의 필요도는 높다고 응답하였으나 활용도는 낮았으며 산사태 SOP 활용시의 문제점은 다양한 피해상황의 미반영과 기관의 역할별 재난관리 단계별 규정의 어려움이 나타났다. 또한 산사태 SOP 작성 시 주요 세부항목 중요도에서는 산사태 발생에 따른 비상대응계획, 대피 및 행동요령에 대한 지침, 산사태 재난 대비 훈련 및 교육, 산사태 재난 방송 실시 및 정보 제공에 대한 절차 수립, 유관기관 및 민간단체와의 협조 및 지원체계 등이 가장 중요하다고 응답되었다. 마지막으로 산사태 SOP 활용을 위한 요구사항은 이를 사용할 수 있는 전문 인력의 확충, 법 제도적 강화, SOP 습득을 위한 교육 및 훈련 등 2차적인 요소에 대한 중요성이 나타났다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.780-785
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• 2004

The work presented here deals with controller design by graphical method based on proportional control ramp response. The design aims at the improvement of transient response, disturbance rejection capability, steady-state error reduction with stability preservation. The first step is to generate tracking-error curve with proportional control only and decide the added error signal shape on the error curve. The effectiveness of the proposed controller is confirmed through the simulation and experiment.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.756-761
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• 2007

This papered is concerned with the crashworthiness characteristics analysis of the non-step bus when it is crashed or roll-over analysis. Computer simulations is implemented using LS-Dyna explicit code which can effectively analysis dynamic response with the lapse of time. We construct a FEM model of the non-step bus under development according to the safety rules used in Europe for composite non-step buses. The crash energy and absorption rate are evaluated to understand crashworthiness characteristic of the composite non-step bus. Body deformation is also examined whether the survival space is secured for passengers.