• Journal of Korean Association for Spatial Structures
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• v.8 no.6
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• pp.95-100
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• 2008

The object of this paper is to verify possible to monitor the deformation of cable in the tensegrity structure. Also, always monitoring system of tensegrity structure using Fiber Bragg Grating Sensor is described. We carry out experiments with measuring deformation of cable in the tensegrity structure based on loading conditions. In the result of experiment, the Fiber Bragg Grating Sensors shows accurate response to the loading conditions. Therefore, we can make sure the possibility of Fiber Bragg Grating Sensor in health monitoring of the cable structure like tensegrity structure.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.7
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• pp.80-91
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• 1999

We present various optimal grating structures which give the low threshold gain, good modulation characteristics, small effective linewidth enhancement factor, and large fabrication tolerance in complex-coupled MQW DFB lasers with absorptive gratings. To obtain these, we calculate the complex coupling coefficients using the extended additional layer method and the threshold gain including the modal loss in the absorptive grating region for rectangular and trapezoidal gratings. Based on the comparison of the results for various possible absorptive grating structures, the design guidelines are presented to obtain the low threshold gain or large fabrication tolerance. Among the grating structures studied, the double grating structure consisting of the absorptive grating on the index grating has the largest fabrication tolerance for the threshold gain and the coupling strength. The fabrication tolerance for the coupling ratio is very large for all the grating structures studied.

• Composites Research
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• v.31 no.4
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• pp.156-160
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• 2018

In this paper, evaluation method of structural integrity for cone-type composite lattice structures with hexagonal cell was conducted. A finite element analysis was used to evaluate the structural integrity of cone-type composite lattice structure. The finite element model for evaluation of structural integrity was generated using solid element. In order to consider the difference in mechanical properties between intersection and non-intersection part, the mechanical properties were applied considering the fiber volume fraction of each part. Compression test of cone-type composite lattice structure were conducted for verification of evaluation method of structural integrity. The analysis result showed 2% errors in displacement and good agreement with test result.

• Electronics and Telecommunications Trends
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• v.4 no.4
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• pp.98-107
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• 1989

실제의 결정은 이상적인 결정과는 달리 결함(imperfection or defect)들을 포함하고 있다. 본고에서는 이들 여러가지 결함들 중 격자 결함들에 국한해서, 그 기본적인 특성과 Si 격자에서의 이들 결함들의 구조를 살펴보고, 이것들을 고분해능 전자현미경(High Resolution Transmission Electron Microscopy ; HRTEM or HREM)으로 관찰했을 때, HRTEM의 탈초점 (defocus)에 따른 결함 상(image)의 성질의 변화와 함께 상 특성과 격자구조와의 관계를 살펴보았다.

• Composites Research
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• v.31 no.2
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• pp.69-75
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• 2018

In this study, a grid panel structure in which the woven CFRP composites were stacked in the orthogonal array was proposed and the mechanical properties were analyzed and studied. The grid parts were fabricated by cutting prepregs and laminating them. The grid panel structure was fabricated by co-curing with lower laminate plate in auto-clave process. The behavior of the proposed grid panel structure was evaluated by tests under tensile, compressive, shear, and bending loads. The effect of increasing the stiffness of the orthogonal grid structure was verified through these tests. In addition, the finite element model was constructed and compared with the test results, confirming the validity and reliability of the test and analysis.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.5
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• pp.175-180
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• 2019

The optical characteristics and power transfers between guiding channels of blazed grating-assisted directional coupler (B-GADC) are evaluated in detail by using novel and rigorous modal transmission-line theory (MTLT) based on eigenvalue problem. To evaluate the coupling efficiency of B-GADC, the dispersion curves as a function of the grating period and wavelength are analyzed numerically for quasi-TE and quasi-TM modes. Furthermore, symmetric, sawtooth and asymmetric grating profiles are considered to know the effect of blazing characteristics on power transfer of GADC. The numerical results show that the grating period for minimum-gap condition to obtain maximum power transfer decreases gradually as the blazed structure changes from symmetric to asymmetric profile. On the other hand, the coupling length increases reversely.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1994.10a
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• pp.58-61
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• 1994

본 연구에서는 내부 외부 진동원(8-30Hz)에 따른 격자보 구조의 동적 응답을 효과적으로 제어하기 위해 격자보 구조의 동적 거동에 지배적인 영향을 미치는 철근비, 질량, 탄성계수 등 여러 인자들의 비교, 분석을 통해 동적 거동에 영향을 미치는 인자를 분석함으로써 격자보 구조의 설계시 인자의 변화에 따른 동적 거동 특성을 예측하여 이에 적절히 대응할 수 있도록 도모하였다. 이를 위해 국내에 건설된 반도체 공장의 격자보 구조 중에서 기본 해석 모델을 결정하고 이에 대해 실험적 모드 해석과 유한 요소 해석을 사용해서 기본 해석 모델의 모드 매개변수를 구하고, 기본 해석 모델에 사용되는 각 인자가 고유 진동수에 미치는 영향을 비교.분석하였다.

• Composites Research
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• v.30 no.6
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• pp.356-364
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• 2017

Composite lattice structures are tried to be used in various fields because of its benefit in physical properties. With increase of demand of the composite lattice structure, nondestructive testing technology is also required to certificate the quality of the manufactured structures. Recently, research on the development of the composite lattice structure in Republic of Korea was started and accordingly, fast and accurate non-destructive evaluation technology was needed to finalize the manufacturing process. This paper studied non-destructive testing methods for composite lattice structure using laser ultrasonic propagation imaging systems. Pulse-echo ultrasonic propagation imaging system was able to inspect a rib structure wrapped with a skin structure. To reduce the time of inspection, a band divider, which can get signal in different frequency bands at once, was developed. Its performance was proved in an aluminum sandwich panel. In addition, to increase a quality of results, curvature compensating algorithm was developed. On the other hand, guided wave ultrasonic propagation imaging system was applied to inspect delamination in a rib structure. To increase an area of inspection, multi-source ultrasonic wave propagation image was applied, and defects were successfully highlighted with variable time window amplitude mapping algorithm. These imply that ultrasonic propagation imaging systems provides fast and accurate non-destructive testing results for composite lattice structure in a stage of the manufacturing process.

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.7
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• pp.8-12
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• 1989

In this paper, dielectric waveguide gratings, which can be applied to the nonreciprocal devices such as isolators, are proposed. Those grating structures can be considered as cascade connections of step discontinuities between uniform dielectric waveguides and another uniform dielectric waveguides with a ferrite layer. Therefore, the nonreciprocal scattering characteristics of such gratings can be obtained form the scattering characteristics of step discontinuities and uniform dielectric wave guides. For the periodic grating structures, band-reject characteristics can be located inside or outside the frequency range of interest. Numerical analyses are performed at 35GHz and experimental results at X-band are also presented.

• The Journal of the Korea institute of electronic communication sciences
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• v.9 no.7
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• pp.767-772
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• 2014

As temporary network, ad-hoc network has been effected by structures and implemented environments of networks. In this paper, transmission performance of lattice structure ad-hoc network, which is expected to use in sensor network and IoT(Internet of Things), is analyzed in point of intrusions and countermeasure for intrusion is suggested. In this paper, computer simulation based on NS-2 is used for performance analysis, VoIP(Voice over Internet Protocol) as a widely used service is chosen for performance measure. MOS(Mean Opinion Score) and call connection rate is used as performance parameter. As results of performance analysis, it is shown that for MOS, random network is better then lattice network at intrusion environments, but for call connection rate, lattice network is better then random network.