• 터널과지하공간
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• 제16권4호
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• pp.326-333
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• 2006

본 연구에서는 측정된 진동파형을 토대로 다른 발파공들로부터 간섭을 받지 않은 단일공의 진동파형을 분리 하였고 이를 FFT 주파수 분석을 통하여 우세 주파수를 분석하였다. 또한 진동의 지속시간과 발파공수가 PPV에 미치는 영향을 검토하기 위해 분리된 진동파형을 $2{\sim}15$공으로 발파공수를 조절하면서 $1{\sim}80ms$까지 1 ms의 간격으로 지연시차에 변화를 주며 발파진동에 중첩 모델링을 실시하였다. 그 결과 진동의 지속시간이 길어질수록 다른 발파공들로부터 간섭받지 않기 위한 지연시차 또한 길어졌고 동일 지연시차 내에서의 발파공 수에 관한 영향은 크게 나타나지 않았다.

• 터널과지하공간
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• 제18권4호
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• pp.280-288
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• 2008

발파진동은 암반 및 인근 구조물에 심각한 문제를 야기할 수 있기 때문에 시공 전 발파진동의 예측과 안전성 평가가 반드시 선행되어야 한다. 최근 발파진동 영향평가를 위하여 시추공이나 시험발파를 통해 획득한 실측진동파형을 이용한 동적수치해석이 증가하고 있다. 하지만 시추공 발파 진동파형은 실제 발파현장에서 측정된 진동파형과 진동수준이나 진동지속시간에서 다소 차이가 있으며 이는 단일공 파형과 유사한 특성을 가진다. 따라서 본 연구에서는 단일공 파형의 중첩모델링을 통해 발파조건 변화에 따른 진동파형을 획득하고 이 파형을 이용한 동적수치해석을 수행하였다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.301-304
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• 2002

Powertrain simulation is important fur the analysis of a vehicle performance. Automotive powertrain has been considered as the unified system and should be remodeled, whenever a powertrain system is changed. In this study, a new method is proposed for the synthetic modeling for the automotive powertrain. Components are separated from the powertrain system and constructed the matrix through dynamic relationships. The dynamic equation of the total powertrain system can be driven from the combination of each component. In order to combine each component, the superposition method is modified for the powertrain composition.

• 터널과지하공간
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• 제17권6호
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• pp.484-492
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• 2007

국내에서는 주로 환산거리 진동예측식에 의한 발파진동 예측 방법이 사용되고 있다. 그러나 이러한 환산거리방식은 실규모의 발파가 시행되어져야 할 필요성이 있다. 최근 국내에서는 터널 등의 공사 시행 전 사전 조사단계에서 발파진동의 영향권을 예측하려는 시도로서 지질 조사용 시추공 등에 장약 발파하여 지반진동을 측정하고 본 발파의 발파 진동을 예측하는 방법이 사용되고 있다. 그러나 이러한 발파진동 예측 방법은 본 발파시의 진동의 전달 특성을 완전하게 반영하지는 못한다. 이러한 발파진동 예측방법의 결점을 보완하기 위하여 본 연구에서는 사전 조사 단계의 단일공 파형 중첩 모델링을 통하여 발파진동을 예측하는 방법을 개발하였다.

• 터널과지하공간
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• 제20권2호
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• pp.112-118
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• 2010

도심지 발파와 같이 인체나 구조물에 직접적인 영향을 미칠 수 있는 발파 작업 시에는 지반진동의 영향성 평가 작업이 필수적으로 선행되어야 한다. 이로 인해 주파수가 지반진동의 특성에 관하여 미치는 영향과 피해여부를 판단하는 중요한 요소로 인식되고 있다. 주파수의 영향에 대해서 많은 연구가 이뤄지고 있지만, 이러한 연구들은 지반진동의 발생과 전파에 있어서 지연시차에 따른 주파수 특성을 연구한 것은 아니었다. 따라서 본 연구에서는 Langefors의 시차이론에 근거한 단일공 파형에 의한 중첩모델링으로 얻어진 지연시차를 통하여 지반 진동의 간섭에 있어 보강과 상쇄간섭이 반복되는 각각의 지연시차에 따른 주파수의 관계를 고찰하였다.

• 대한기계학회논문집A
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• 제27권10호
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• pp.1623-1629
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• 2003

In this paper, the arc beam is considered as a moving disc heat source with a pseudo-Gaussian distribution of heat intensity. The solution for temperature distribution on welds is derived by using the image heat source method and the superposition method. It is general solution in that it can determine the temperature-rise distribution in and around the arc beam heat source, as well as the width and depth of the melt pool (MP) and the heat-affected zone (HAZ) in welding short lengths, where quasi-stationary conditions may not have been established. As a comparative study, the results of this analytical approach has been compared with that of the finite-element modeling. As a result, The theoretical analysis presented here has shown good consistency and is more time/cost-effective method compared with FEM.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 추계학술대회 논문집
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• pp.439-442
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• 2002

Powertrain simulation is important far the analysis of a vehicle performance. Automotive powertrain has been considered as the unified system and should be remodeled, whenever a powertrain system is changed. In this study, a new method is proposed far the synthetic modeling for the automotive powertrain. Components are separated from the powertrain system and constructed the matrix through dynamic relationships. The dynamic equation of the total powertrain system can be driven from the combination of each component. In order to combine each component, the superposition method is modified for the powertrain composition.

• 한국시뮬레이션학회논문지
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• 제14권4호
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• pp.55-68
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• 2005

The advancement in semiconductor technology is leading toward smaller critical dimension designs and larger wafer manufactures. Due to such phenomena, semiconductor industry is in need of an accurate control of the process. Photolithography is one of the key processes where the pattern of each layer is formed. In this process, precise superposition of the current layer to the previous layer is critical. Therefore overlay parameters of the semiconductor photolithography process is targeted for this research. The complex relationship among the input parameters and the output metrologies is difficult to understand and harder yet to model. Because of the superiority in modeling multi-nonlinear relationships, neural networks is used for the simulator modeling. For training the neural networks, conjugate gradient method is employed. An experiment is performed to evaluate the performance among the proposed neural network simulator, stepwise regression model, and the currently practiced prediction model from the test site.

• Structural Engineering and Mechanics
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• 제43권1호
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• pp.71-87
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• 2012

This paper extends a single equation, semi-analytical approach for three-span bridges to multi-span ones for the rapid and precise determination of natural frequencies and natural mode shapes of an orthotropic, multi-span plate. This method can be used to study the dynamic interaction between bridges and vehicles. It is based on the modal superposition method taking into account intermodal coupling to determine natural frequencies and mode shapes of a bridge deck. In this paper, a four- and a five-span orthotropic roadway bridge deck are compared in the first 10 modes with a finite element method analysis using ANSYS software. This simplified implementation matches numerical modeling within 2% in all cases. This paper verifies that applicability of a single formula approach as a simpler alternative to finite element modeling.

• 한국의학물리학회:학술대회논문집
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• 한국의학물리학회 2002년도 Proceedings
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• pp.119-120
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• 2002

The aim is to urge the need of elaborate commissioning of 3D RTP system from the firsthand experience. A 3D RTP system requires so much data such as beam data and patient data. Most data of radiation beam are directly transferred from a 3D dose scanning system, and some other data are input by editing. In the process inputting parameters and/or data, no error should occur. For RTP system using algorithm-bas ed-on beam-modeling, careless beam-data processing could also cause the treatment error. Beam data of 3 different qualities of photon from two linear accelerators, patient data and calculated results were commissioned. For PDD, the doses by Clarkson, convolution, superposition and fast superposition methods at 10 cm for 10${\times}$10 cm field, 100 cm SSD were compared with the measured. An error in the SCD for one quality was input by the service engineer. Whole SCD defined by a physicist is SAD plus d$\sub$max/, the value was just SAD. That resulted in increase of MU by 100${\times}$((1_d$\sub$max//SAD)$^2$-1)%. For 10${\times}$10 cm open field, 1 m SSD and at 10 cm depth in uniform medium of relative electron density (RED) 1, PDDs for 4 algorithms of dose calculation, Clarkson, convolution, superposition and fast-superposition, were compared with the measured. The calculated PDD were similar to the measured. For 10${\times}$10 cm open field, 1 m SSD and at 10 cm depth with 5 cm thick inhomogeneity of RED 0.2 under 2 cm thick RED 1 medium, PDDs for 4 algorithms were compared. PDDs ranged from 72.2% to 77.0% for 4 MV X-ray and from 90.9% to 95.6% for 6 MV X-ray. PDDs were of maximum for convolution and of minimum for superposition. For 15${\times}$15 cm symmetric wedged field, wedge factor was not constant for calculation mode, even though same geometry. The reason is that their wedge factor is considering beam hardness and ray path. Their definition requires their users to change the concept of wedge factor. RTP user should elaborately review beam data and calculation algorithm in commissioning.