• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.7
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• pp.31-36
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• 2004

In comparison with in-plane lasers, predicting the output power and differential quantum efficiency of Vertical-Cavity Surface-Emitting Lasers(VCSELs) is very difficult due to the distributed Bragg reflector(DBR) layers. Therefore, effective cavity model and transfer matrix method have been adapted in order to calculate the output power and differential quantum efficiency The effective cavity model is inappropriate to calculate output power and differential quantum efficiency while it is practically adequate to calculate the threshold gain and threshold current density The reason is that the effective cavity model can not take account of the absorption in GaAs stack layer right below the metal aperture. In this paper, we have compared the threshold current and differential quantum efficiency calculated by using transfer matrix method with effective cavity model and we have made a study of the validity of the effective cavity model. Finally, we have confirmed the versatility of the transfer matrix method with these studies.

• Journal of the Korea institute for structural maintenance and inspection
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• v.7 no.4
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• pp.109-120
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• 2003

The state-of-art of curved box girder bridge with cross section design has advanced in various area. In these days, several analytical techniques for behaviors of curved box girder bridges cross section are available to engineers. The transfer matrix method is extensively used for the structural analysis because its merit in the theoretical background and applicability. The technique is attractive for implementation on a numerical solution by means of a computer program coded in Fortran language with a few elements. To demonstrate this fact, it gives good results which compare well with finite element method. Therefore, this paper proposed the static analysis method of curved box bridge with cross section by transfer matrix method based on pure-torsional theory and the optimal span ratio/variable cross section ratio of 3 span continuous curved box girder bridge.

• Korean Journal of Optics and Photonics
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• v.31 no.2
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• pp.59-70
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• 2020

We discuss a modified numerical model based on the Monte Carlo radiative transfer (MCRT) method, i.e., the MCRT matrix method, for the analysis of atmospheric scattering effects in three-dimensional flash LIDAR systems. Based on the MCRT method, the radiative transfer function for a LIDAR signal is constructed in a form of a matrix, which corresponds to the characteristic response. Exploiting the superposition and convolution of the characteristic response matrices under the paraxial approximation, an extended computer simulation model of an overall flash LIDAR system is developed. The MCRT matrix method substantially reduces the number of tracking signals, which may grow excessively in the case of conventional Monte Carlo methods. Consequently, it can readily yield fast acquisition of the signal response under various scattering conditions and LIDAR-system configurations. Using the computational model based on the MCRT matrix method, we carry out numerical simulations of a three-dimensional flash LIDAR system operating under different atmospheric conditions, varying the scattering coefficient in terms of visible distance. We numerically analyze various phenomena caused by scattering effects in this system, such as degradation of the signal-to-noise ratio, glitches, and spatiotemporal spread and time delay of the LIDAR signals. The MCRT matrix method is expected to be very effective in analyzing a variety of LIDAR systems, including flash LIDAR systems for autonomous driving.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.1
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• pp.35-46
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• 2004

In comparison with edge-emitting lasers(EELs), predicting the output power and slope efficiency of Vertical-Cavity Surface-Emitting Lasers(VCSELs) is very difficult due to the absorption loss in DBR layers. However, by using transfer matrix method(TMM), we've made possible to calculate such parameters of multi-layer structures like VCSELs. In this paper, we've calculated the threshold gain, threshold current and slope efficiency through the methodology based on TMM. Also TMM is the way of customizing the VCSEL structure for the desired threshold current and slope efficiency by changing the number of DBR mirror layers.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.8
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• pp.1777-1783
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• 2013

We do research on the simulation of Doppler effect from a target's moving under the sea by Transmission Line Matrix modeling which is one of numerical methods on time domain. To implement the effect, the input signal was entered at a moving node according to a moving target's moving speed. The result had maximum 2.47% error compared with the theoretical value. And from simulation results with speed control of a moving target, we could also obtain resonable results within 0.63% error range.

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.5
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• pp.1426-1432
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• 1991

본 연구에서는 Timoshenko보이론과 전달행렬법에 의해서 얻어지는 베어링의 반력들과 주축계의 불완전진동모드간의 선형관계를 이용하여 원리적으로 반복계산없이 반경방향과 굽힘모멘트방향의 선형등방성 베어링계수들을 규명하는 방법을 제안하였다. 제안된 규명방법은 주축계에 사용된 베어링의 수보다 진동모드에 대한 측정점의 수가 2배 이상 많아야 한다는 조건을 가지고 있다. 또한 선형 연립방정식으로 부터 직접 규명된 베어링계수들의 일부가 정보의 부정확성에 의해서 물리적으로 타당성이 없는 음수로 나타나는 경우에는 측정결과와의 차이를 최소화시키면서, 물리적으로 타당성이 있는 양수의 베어링계수들을 규명할 수 있는 방법이 제안조건들을 가진 최적화문제의 형태로 제시되었다. 그리고 제시된 최적화문제의 해는 선형화방법(linearization method)를 통해서 얻었다. 아울러서 주축계의 실험모델에 대한 가진실험결과를 이용 하여 제안된 규명방법의 유용성을 평가하였다.

• Journal of KSNVE
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• v.8 no.3
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• pp.504-512
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• 1998

For analyzing the torsional vibration of a multiple stepped gear system containing a pair of triple gears, a transfer matrix model based on Hibner's branch method is developed and the natural properties of the branched rotor system are calculated with using the $\lambda$-matrix formulation. A Campbell diagram, in which the excitation sources caused by the mass unbalances of the rotors and the transmitted errors of thegearings are considered, shows that, at the neighborhood of the operating speed, there are the four critical speeds amplifying the first mode and the fifth mode. For the surpression of the gear box vibration, two ways are suggested by referring the mode shapes.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.4
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• pp.118-126
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• 2008

A new approach to the critical speed calculation of general multi-mesh gear chain system included bevel gear is presented. A transfer matrix mode! based on Hibner's branch method is developed and the natural properties of the branched rotor system are calculated with using the ${\lambda}$-matrix formulation. A Campbell diagram, in which the excitation sources caused by the mass unbalance of the rotors, misalignment and the transmitted errors of the gearing are considered, shows that, at the neighborhood of the operating speed, there are the two critical speeds amplifying the first mode and the eighth mode.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.774-781
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• 2006

This paper presents a study on the analytical prediction of vibration transmission from helical gears to the bearing. The proposed method is based on the application of the three dimensional helical gear behaviors and complete description of shaft by the spectral method. Helical gear system used in this paper consists of the driving element, helical gears, shafts, bearings, couplings and load element. In order to describe all translation and rotation motion of helical gears twelve degree of freedom equations of motion by the transmission error excitation are derived. Using these equations, transfer matrix for the helical gear is derived. For the detail behavior of shaft motion, the $12{\times}12$ transfer matrix for the shaft is derived. Transfer matrix for the bearing, coupling, driving element, and load is also derived. Application of the boundary conditions in the assembled transfer matrix produces the forces and displacements in each element of the helical gear system. The effect of the proposed method is shown by numerical example.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.14 no.2
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• pp.95-107
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• 1989

This paper proposes a realization method of multidimensional digital filters that has high modularity, regularity and parallelism enjoying the attributes for efficient VLSI implementation. The method shows that multidimensional transfer functions can be treated as two-dimensional transfer functions modifying the decomposition method of multidimensional transfer functions proposed by Venetsanopoulos etal, and then be displayed by multiplications and additions of one-dimensional transfer functions by applying the griangular decomposition theorem to the coefficient matrices of the two-dimensional transfer functions.