• Journal of the Optical Society of Korea
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• 제14권4호
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• pp.351-356
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• 2010

We investigated the combined effect of fiber chromatic dispersion and self-phase modulation (SPM) in multi-channel subcarrier multiplexed (SCM) optical transmission systems. We theoretically analyzed the transmission characteristics of the SCM signals with the effect of SPM and chromatic dispersion in a single-mode optical fiber by numerical simulations based on the nonlinear Schrodinger equation. The numerical simulation results revealed that the effect of fiber dispersion and SPM could occur independently between subcarrier channels in two-channel SCM systems for small optical modulation index (OMI) and large channel spacing. However, for large OMI, small channel spacing, and large fiber launching power, we found a performance degradation of the two-channel system compared to that of a single-channel system. These parameters are therefore important for the optimization of multi-channel SCM systems applicable to radio over fiber networks.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1997년도 가을 학술발표회 논문집
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• pp.679-684
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• 1997

In this study, compressive strengths of reinforced concrete compression members rehabilitated with C.F.L. were analyzed from the test. Test parameters are spacing, spliced length, and section area of rehabilitation material. Displacement, failure load were measured during test. The failure mode and ultimate load were analyzed from these measured data. Test result shows that closer spacing of C.F.L. is more effective. strengthening with 1-ply C.F.L. is more effective than that of specimen with 2-ply C.F.L. The compressive capacity of specimen spliced ($\pi$.D)/2 shows almost similar strength to that of non-spliced specimen. The ultimate load carrying capacity of specimen strengthened with C.F.L. is increased to 1.11~1.68 times of that of non-rehabilitation specimen.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2004년도 추계학술대회논문집
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• pp.89-92
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• 2004

This paper is concerned with the drawing process of Al-Si wire. In this study, the finite-element model established in previous work was used to analyze the effects of various forming parameters, which included the reduction in area, the semi-die angle, the aspect ratio and the inter-particle spacing of the Si in drawing processes. The finite-element results gave the consolidation condition. From the results of analysis, the effects of each forming parameter were determined. It is possible to obtain the important basic data which can be guaranteed in the fracture prevention of Al-Si wire by using FEM simulation.

• 반도체디스플레이기술학회지
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• 제16권1호
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• pp.65-69
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• 2017

This paper presents a Technology-CAD (TCAD) simulation of the characteristics of crystalline Si pillar array solar cells. The junction depth and the surface concentration of the solar cells were optimized to obtain the targeted sheet resistance of the emitter region. The diffusion model was determined by calibrating the emitter doping profile of the microscale silicon pillars. The dimension parameters determining the pillar shape, such as width, height, and spacing were varied within a simulation window from ${\sim}2{\mu}m$ to $5{\mu}m$. The simulation showed that increasing pillar width (or diameter) and spacing resulted in the decrease of current density due to surface area loss, light trapping loss, and high reflectance. Although increasing pillar height might improve the chances of light trapping, the recombination loss due to the increase in the carrier's transfer length canceled out the positive effect to the photo-generation component of the current. The silicon pillars were experimentally formed by photoresist patterning and electroless etching. The laboratory results of a fabricated Si pillar solar cell showed the efficiency and the fill factor to be close to the simulation results.

• 한국통신학회논문지
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• 제21권9호
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• pp.2526-2532
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• 1996

In this paper, the efficient algorithm for design of waveguide grating router(WGR) composed of star couplers is proposed. It is well demostrated that a star coupler design can be easily adjusted to the optimumstate using the proposed design method, which analyzes relations between various parameters. This method enables designers to estimate the spectral properties of waveguide grating router at the initial design level of the star coupler. A 5*5 WGR with 2.75nm(343GHz) channel spacing is designed using the proposed scheme. The BPM(Beam Propagation Method) simulation results show that the channel spacing of the WGR agrees very well with the design, the excess loss is smaller than 2.5dB, and the crosstalk is less than -21dB.

• Journal of Mechanical Science and Technology
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• 제20권10호
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• pp.1541-1547
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• 2006

An efficient procedure to obtain the optimal stacking sequence and the minimum weight of stiffened laminated composite curved panels under several loading conditions and stiffener layouts has been developed based on the finite element method and the genetic algorithm that is powerful for the problem with integer variables. Often, designing composite laminates ends up with a stacking sequence optimization that may be formulated as an integer programming problem. This procedure is applied for a problem to find the stacking sequence having a maximum critical buckling load factor and the minimum weight. The object function in this case is the weight of a stiffened laminated composite shell. Three different types of stiffener layouts with different loading conditions are investigated to see how these parameters influence on the stacking sequence optimization of the panel and the stiffeners. It is noticed from the results that the optimal stacking sequence and lay-up angles vary depending on the types. of loading and stiffener spacing.

• Journal of Advanced Marine Engineering and Technology
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• 제25권4호
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• pp.857-868
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• 2001

The aerodynamic forces and wake structures of the non-rotating downstream cylinder which is located behind the spinning upstream cylinder in tandem and staggered arrangement have been investigated by experimental method at Re= $1.32{\times}10^4$. The measurements of wake flow and pressure distributions of downstream cylinder are carried out in various spin parameters by combination of both longitudinal spacing rations L/d=1.5, 3.0, 4.5 and transverse spacing ratios T/d =0.0, -0.5, 0.5. For the present experiment, it has been found that the spin parameter of spinning upstream cylinder affect more easily the downstream cylinder in tandem arrangement than that in staggered arrangement.

• Earthquakes and Structures
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• 제22권1호
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• pp.39-51
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• 2022

The axial compression behavior of nine self-compacting concrete columns confined with CFRP-PVC spirals was studied. Three parameters of spiral reinforcement spacing, spiral reinforcement diameter and height diameter ratio were studied. The test results show that the CFRP strip and PVC tube are destroyed first, and the spiral reinforcement and longitudinal reinforcement yield. The results show that with the increase of spiral reinforcement spacing, the peak bearing capacity decreases, but the ductility increases; with the increase of spiral reinforcement diameter, the peak bearing capacity increases, but has little effect on ductility, and the specimen with the ratio of height to diameter of 7.5 has the best mechanical properties. According to the reasonable constitutive relation of material, the finite element model of axial compression is established. Based on the verified finite element model, the stress mechanism is revealed. Finally, the composite constraint model and bearing capacity calculation method are proposed.

• Communications for Statistical Applications and Methods
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• 제30권2호
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• pp.191-213
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• 2023

Unit distributions are frequently used in probability theory and statistics to depict meaningful variables having values between zero and one. Using convenient transformation, the unit inverse exponentiated weibull (UIEW) distribution, which is equally useful for modelling data on the unit interval, is proposed in this study. Quantile function, moments, incomplete moments, uncertainty measures, stochastic ordering, and stress-strength reliability are among the statistical properties provided for this distribution. To estimate the parameters associated to the recommended distribution, well-known estimation techniques including maximum likelihood, maximum product of spacings, least squares, weighted least squares, Cramer von Mises, Anderson-Darling, and Bayesian are utilised. Using simulated data, we compare how well the various estimators perform. According to the simulated outputs, the maximum product of spacing estimates has lower values of accuracy measures than alternative estimates in majority of situations. For two real datasets, the proposed model outperforms the beta, Kumaraswamy, unit Gompartz, unit Lomax and complementary unit weibull distributions based on various comparative indicators.

• 화약ㆍ발파
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• 제35권4호
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• pp.1-9
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• 2017

본 연구는 인공절리를 이용한 발파효과 검토를 위해 인공절리 수, 인공절리 간격, 인공절리 경사에 따른 발파속도의 영향 및 기여도를 평가 분석한 연구이다. 인공절리 상태 변화에 따른 발파속도는 동적해석 프로그램인 AUTODYN을 이용하여 획득하였다. 수치해석 결과에 대해 정규화 분석을 수행하였고, 각 인자의 기여도 분석을 위해 강건설계 실험계획법을 이용하여 설계 인자를 분석하였다. 각 인자는 3수준으로 설정하였고, 분석에 직교 배열표 $L_9(3^4)$를 사용하였다. 정규화 분석을 통해 수치해석 결과를 분석한 결과 인공절리 경사가 증가함에 따라 발파속도는 감소하는 경향을 보였다. 또한, 인공절리 간격과 인공절리 경사에 대해 발파속도를 분석한 결과 발파속도는 경사가 수직일 때 인공절리 간격이 증가함에 따라 감소는 경향을 보였다. 강건설계를 이용한 기여율 분석결과 발파속도에 가장 큰 영향을 미치는 것은 인공절리 경사이며, 이어서 인공절리 수, 인공절리 간격 순으로 기여율이 평가되었다.