• 천문학회보
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• 제41권1호
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• pp.33.3-34
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• 2016

We explored the GALEX UV properties of optical red sequence galaxies in 4 rich Abell clusters at z ~ 0.1. In particular, we tried to find a hint of merger-induced recent star formation (RSF) in red sequence galaxies. Based on the NUV - r' colors of the galaxies, about 36% of the post-merger galaxies were classified as RSF galaxies with a conservative criterion (NUV - $r^{\prime}{\leq}5$), and that number was doubled (~ 72%) when using a generous criterion (NUV - $r^{\prime}{\leq}5.4$). Post-merger galaxies with strong UV emission showed more violent, asymmetric features on the deep optical images. Also it turned out that all massive RSF galaxies (Mr' < -22 and NUV - $r^{\prime}{\leq}5$) exhibited post-merger signatures. Our results suggested that only 30% of RSF red sequence galaxies show morphological hints of recent galaxy mergers. This implies that internal processes (e.g., stellar mass-loss or hot gas cooling) for the supply of cold gas to early-type galaxies may play a significant role in the residual star formation of early-type galaxies at a recent epoch.

• Journal of Electrical Engineering and Technology
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• 제13권2호
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• pp.892-901
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• 2018

Because of excellent electrical properties, epoxy resin is widely used in packaging and casting power equipment. Moisture and temperature in the environment are inclined to seriously affect the insulation tolerance of epoxy resin. This work focuses on the aging characteristics of epoxy resin in hygrothermal environment. Scanning electron microscopy images show that there are micro-crack, micro-slit and holes inside aged samples. The moisture absorption process undergoes three equilibrium stages and it does not follow the Fick's second law. Observing the change of hydrogen bonds in the infrared spectra of the dried samples, it is found that chemically moisture absorption immerges when the physical moisture absorption entered the third equilibrium stage. By Debye equation to fit the imaginary part of the dielectric constant, it is concluded that the uniformity of water molecule has a great influence on the electrical conductivity loss. Furthermore, the polarization loss can be more easily affected by water molecules than small free molecules. After the aged samples being dried, their real and imaginary part of the dielectric constant descend, but their original electrical properties cannot completely restored. After chemical moisture absorption appears inside the material, the residual space charges increase significantly and the charge dissipation rate slow down obviously.

• Structural Engineering and Mechanics
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• 제29권5호
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• pp.489-504
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• 2008

In piezoelectric flexible structures, the contribution of vibration modes to the dynamic response of system may change with the location of piezoelectric actuator patches, which means that the ability of actuators to control vibration modes should be taken into account in the development of modal reduction model. The spatial $H_2$ norm of modes, which serves as a measure of the intensity of modes to system dynamical response, is used to pick up the modes included in the reduction model. Based on the reduction model, the paper develops the state-space representation for uncertain flexible tructures with piezoelectric material as non-collocated actuators/sensors in the modal space, taking into account uncertainties due to modal parameters variation and unmodeled residual modes. In order to suppress the vibration of the structure, a dynamic output feedback control law is designed by imultaneously considering the conflicting performance specifications, such as robust stability, transient response requirement, disturbance rejection, actuator saturation constraints. Based on linear matrix inequality, the vibration control design is converted into a linear convex optimization problem. The simulation results show how the influence of vibration modes on the dynamical response of structure varies with the location of piezoelectric actuators, why the uncertainties should be considered in the reductiom model to avoid exciting high-frequency modes in the non-collcated vibration control, and the possiblity that the conflicting performance specifications are dealt with simultaneously.

• Steel and Composite Structures
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• 제41권6호
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• pp.887-898
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• 2021

This paper presents a simplified model to capture the nonlinear behavior of steel frames depending on the spread of plasticity method. New interaction formulae were derived to evaluate the plastic strength for I-shaped steel sections under uniaxial bending moment and axial compression load. Also, new empirical formulae were derived to evaluate the tangent stiffness modulus of steel I-shaped cross-sections considering the effect of the residual stresses suggested by the specifications in European Convention for Construction Steelworks (ECCS). The secant stiffness which depends on the tangent modulus is used to evaluate the internal forces. Based on stiffness matrix method, a finite element analysis program was developed for the nonlinear analysis of space steel frames using the derived formulae. Comparison between the proposed model results with those given by the fiber model shows very good agreement. Numerical examples were introduced to verify, check the accuracy, and evaluate the efficiency of the proposed model. The analysis results show that the new proposed model is accurate and able to minimize the solution time.

• 천문학회보
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• 제45권1호
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• pp.39.1-39.1
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• 2020

We examine how the mass assembly of central galaxies depends on their location in the cosmic web. The HORIZON-AGN simulation is analysed at z~2 using the DISPERSE code to extract multi-scale cosmic filaments. We find that the dependency of galaxy properties on large-scale environment is mostly inherited from the (large-scale) environmental dependency of their host halo mass. When adopting a residual analysis that removes the host halo mass effect, we detect a direct and non-negligible influence of cosmic filaments. Proximity to filaments enhances the build-up of stellar mass, a result in agreement with previous studies. However, our multi-scale analysis also reveals that, at the edge of filaments, star formation is suppressed. In addition, we find clues for compaction of the stellar distribution at close proximity to filaments. We suggest that gas transfer from the outside to the inside of the haloes (where galaxies reside) becomes less efficient closer to filaments, due to high angular momentum supply at the vorticity-rich edge of filaments. This quenching mechanism may partly explain the larger fraction of passive galaxies in filaments, as inferred from observations at lower redshifts.

• 구강회복응용과학지
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• 제27권4호
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• pp.437-447
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• 2011

오랜 기간 국소의치를 장착한 부분 무치악 환자에서, 치아가 결손된 부위는 점진적인 치조골의 흡수가 발생되는 반면, 잔존 지대치 부위는 치조골이 유지되어 있는 것을 볼 수 있다. 이는 차후 잔존 지대치를 상실한 후에도 치아 상실의 시점에 따라 수직적인 골 높이의 현저한 차이를 나타낸다. 이와 같이 전체 치아 발거 후 상하악 악간 거리가 좌우측 또는 전후방으로 다르게 나타나는 환자에서 임플란트를 이용한 고정성 보철물이나 임플란트 피개의치의 제작 시 여러 가지 보철적 문제가 야기될 수 있다. 본 논문은 구치부 결손으로 인해 오랫동안 국소의치를 사용했던 환자에서 치아 상실 후 잔존 치조골의 높이를 고려하여 임플란트 지지 국소의치를 제작한 증례로서 잔존 치조골 량이 많아 악간거리가 짧은 전치부는 임플란트를 식립하여 고정성 보철물로, 오랫동안 치조골의 흡수로 인해 악간거리가 긴 구치부는 국소의치로 수복하였다. 본 증례에서의 임플란트 지지 국소의치는 부가적인 수술이 없이 소수의 임플란트를 식립하고 환자에게 기존 보철물의 양식과 유사한 보철물을 제공함으로서 경제적이고 편안한 치료결과를 보여주었다.

• 구강회복응용과학지
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• 제39권4호
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• pp.214-221
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• 2023

잔존 치조제의 흡수가 심하게 진행된 환자에서 안정된 의치를 제작하기 위해서는 여러가지 요소를 고려해야 한다. 그 중 하나는 중립대(Neutral zone)로, 기능하는 동안 구강 안에서 밖으로 향하는 혀의 압력과 밖에서 안으로 향하는 볼과 입술의 압력이 평형을 이루는 잠재적인 영역으로 정의된다. 만약 치조제의 흡수가 심한 경우에 통상적으로 잔존 치조제 상방에 치아를 배열한다면 치아는 기존 위치보다 설측에 위치하게 된다. 따라서 혀의 기능공간을 침범하게 되어 혀가 후방으로 위치하게 되고, 설측 변연의 봉쇄가 깨져 의치를 탈락시키는 요인으로 작용하게 된다. 또한 상·하악의 치조제를 잇는 치조정간선을 상정하고 저작력을 치조정간선에 일치시키도록 상·하악 인공치를 배열하는 것 또한 의치의 안정에 중요하다. 따라서 불량한 잔존 치조제를 지닌 환자에게 중립대 인상 및 치조제 관계 분석을 이용해 의치를 제작하여 좋은 임상 결과를 얻었기에 보고하는 바이다.

• ETRI Journal
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• 제36권5호
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• pp.783-790
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• 2014

In this paper, we first analyze carrier-to-interference ratio performance of the space-frequency block coded orthogonal frequency-division multiplexing (SFBC-OFDM) system in the presence of phase noise (PHN) and residual carrier frequency offset (RCFO). From the analysis, we observe that conventional SFBC-OFDM systems suffer severely in the presence of PHN and RCFO. Therefore, we propose a new inter-carrier interference (ICI) self-cancellation method - namely, ISC - for SFBC-OFDM systems to reduce the ICI caused by PHN and RCFO. Through the simulation results, we show that the proposed scheme compensates the ICI caused by PHN and RCFO in Alamouti SFBC-OFDM systems and has a better performance than conventional schemes.

• 제어로봇시스템학회논문지
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• 제17권11호
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• pp.1145-1153
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• 2011

EMB (Electro-Mechanical Brake) systems can provide improved braking and stability functions such as ABS, EBD, TCS, ESC, BA, ACC, etc. For the implementation of the EMB systems, reliable and robust fault detection algorithm is required. In this study, a model-based fault detection algorithm is designed based on the analytical redundancy method in order to monitor current and force sensor faults in EMB systems. A state-space model for the EMB is derived including faulty signals. The fault diagnosis algorithm is constructed using the analytical redundancy method. Observer is designed for the EMB and the fault detectability condition is examined based on the residual analysis. The performance of the proposed model-based fault detection algorithm is verified in simulations. The effectiveness of the proposed algorithm is demonstrated in various faulty cases.

• Journal of applied mathematics & informatics
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• 제32권1_2호
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• pp.171-184
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• 2014

A higher order iterative method to compute the Moore-Penrose inverses of arbitrary matrices using only the Penrose equation (ii) is developed by extending the iterative method described in [1]. Convergence properties as well as the error estimates of the method are studied. The efficacy of the method is demonstrated by working out four numerical examples, two involving a full rank matrix and an ill-conditioned Hilbert matrix, whereas, the other two involving randomly generated full rank and rank deficient matrices. The performance measures are the number of iterations and CPU time in seconds used by the method. It is observed that the number of iterations always decreases as expected and the CPU time first decreases gradually and then increases with the increase of the order of the method for all examples considered.