• The Journal of the Acoustical Society of Korea
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• v.12 no.4
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• pp.39-46
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• 1993

조화집중이동하중을 받는 무한보에서의 음향방사에 대한 연구는 선박, 비행기, 타이어 트레드 밴느 등과 같은 계의 설계시 계의 구조물로부터 발생하는 소음에 대한 해결방안을 제시해 준다. 구조물 표면에 발생하는 음향파워는 svktnqusghks방법을 이용하여 보의 전길이에 분포된 음향 인텐시티를 적분하여 구한다. 보의 표면에서 발생하는 음향파원는 미하수, 장력, 감쇠계수, 기초강성계수, 그리고 파수비에 의해서 결정된다. 각 인자에 따른 음향파워에 대한 정성적인 분석을 수행하기 위해 심프슨 적분방법을 이용하여 수치적분을 하였다. 무한보에 작용하는 유체하중에 3다라 진동에너지가 음향에너지로 변환되는 비율이 달라진다. 밀도가 큰 유체는 등가감쇠로 작용하여 보로부터 방사된 음향에너지는 빠르게 감소된다. 하중의 이동에 의하여 도플러이동효과가 발생하여 무한보의 공진부근에서의 음향파워 파크가 분리되고 보의 기초감쇠의 영향으로 음향에너지는 감소된다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2010.10a
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• pp.162-163
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• 2010

• Proceedings of the Korean Nuclear Society Conference
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• 2001.05a
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• pp.492-492
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• 2001

• Journal of Korea Spatial Information System Society
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• v.11 no.3
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• pp.1-8
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• 2009

In this study the concepts on the elongation, compactness and equivalent ellipse of catchment plan-forms are applied to the real basins considering their theoretical frameworks. The catchment plan-forms and corresponding equivalent ellipses, obtained from GIS, are inspected on downstream directions. As a result the catchment plan-forms seem to be the population of the basin shapes which come from the random interaction between two conjectures on Hack's law being controversial recently. The ratio of the maximum and minimum inertia moments of the catchment plan-form Ri is more sensitive to evaluate the elongation of the basin shapes than the ratio of the main channel length and diameter of circle which has the same area as the catchment plan-form E. The catchment plan-forms compactness measures show distinct aspects according to their different definitions. These results are caused by the difficulties to quantification of the shapes and the composite consideration with more than two compactness measures and the fractal analysis are therefore required to recover them.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.11
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• pp.1105-1111
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• 2015

The exhaust system is one of the major sources of vibrations, along with the suspension system and engine. When the exhaust system is connected directly to the engine, it transfers vibrations to the vehicle body through the body mounts. Therefore, in order to reduce the vibrations transmitted from the exhaust system, the vibration characteristics of the exhaust system should be predicted. Thus, the dynamic characteristics of the bellows, which form a key component of the exhaust system, must be modeled accurately. However, it is difficult to model the bellows because of the complicated geometry. Though the equivalent beam modeling technique has been applied in the design stage, it is not sufficiently accurate in the case of the bellows which have complicated geometries. In this paper, we present an improved technique for modeling the bellows in a vehicle. The accuracy of the modeling method is verified by comparison with the experimental results.

• Journal of the Korea Convergence Society
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• v.11 no.9
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• pp.169-173
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• 2020

The structural analysis was performed at this study when the axle was loaded by using a total of three automotive support beam models, models A, B and C. Comparing with three models A, B, and C, the equivalent stress is considered to be good for its durability because model C is less than the yield stress of the material. The maximum equivalent stresses happening at models A and B are 1.8 times and 2.5 times higher than the yield stress, respectively, indicating that the material is fractured. So, it does not seem to be efficient as a support beam. Model C can be applied efficiently to the improvement design of axle support beams in terms of durability compared to models A and B. The strength of automotive support beam can be evaluated by applying this research result to the automotive part. And it is seen that this study is adequate at the efficient design and aesthetic convergence practically.

• Journal of the Korean Geotechnical Society
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• v.25 no.8
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• pp.57-64
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• 2009

In this study, a method using equivalent transformation for estimation of the axial load capacity of tapered piles is proposed. While preexistent methods for estimating the axial load capacity of tapered piles have been based on the effect of soil state and taper angle, a new design method is proposed considering cone resistance $q_c$ and equivalent transformation in sand. Through tapered pile simplified by using equivalent transformation, a new method fur quick and easy estimation of the axial load capacity of tapered pile is proposed for practical use. In order to verify the proposed method, calibration chamber test and field test were conducted. In calibration chamber test, comparison of estimated axial load capacity with measured one showed that the standard deviation and COV (Coefficient Of Variation) of estimated $Q_t$ is $0.05{\sim}0.121$, $0.04{\sim}0.05$ respectively. For field test, axial load capacity by proposed method shows 2.5% under-estimation in comparison with measured value. As a result, it is found that proposed method produces satisfactory predictions for tapered piles.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.36 no.11
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• pp.826-835
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• 1987

In this paper, the horizontal output and flyback transformer (FBT) stages during the retrace time are represented by a new simplified equivalent circuit. The circuit analysis is performed by means of this equivalent circuit and the computed results are compared with those of experiment The results show that for fixed other circuit parameters, the high voltage regulation depends upon the coupling factor of transformer, the V-I characteristics and the charge storage of the high voltage rectifying diodes. The computed output voltages are found to be about 3.9 to 5.8% higher than the measurements and these are probably due to the neglection of the transformer losses. These acceptable errors show that the newly suggested equivalent circuit is reasonable.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.5C
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• pp.403-412
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• 2008

This paper presents the methods which obtain the solution of Wiener-Hopf equation by LMS algorithm and get the coefficient of TDL filter in lattice filter directly. For this result, we apply an orthogonal input signal generated by lattice filter into an equivalent Wiener-Hopf equation and shows the scheme that can obtain the solution by using the MMSE algorithm. Conventionally, the method like aforementioned scheme can get an error and regression coefficient recursively. However, in this paper, we can obtain an error and the coefficients of TDL filter recursively. And, we make an theoretical analysis on the convergence characteristics of the proposed algorithm. Then we can see that the result is similar to conventional analysis. Also, by computer simulation, we can make sure that the proposed algorithm has an excellent performance.

• Composites Research
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• v.33 no.6
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• pp.377-382
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• 2020

The free vibration characteristics of corrugated laminated composite plates with axial stiffeners is investigated using the Rayleigh-Ritz method. The plate is stiffened by beams with open cross-section area. The equivalent homogenization model is used for the corrugated laminated composite plates. This homogenization model is treated a corrugated plate as an orthotropic plate that has different material properties in two perpendicular directions. The motion of equivalent plate is represented on the basis of the first order shear deformation theory (FSDT) to account for the effect of rotary inertia and transverse shear deformation. Stiffeners are considered as discrete elements to predict the local vibration mode to be generated by the presence of stiffeners. To validate the proposed analytical approach, natural frequencies and vibration mode shapes from the analytical method are compared with those from the FEA by ANSYS.