• Journal of Electrical Engineering and Technology
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• 제10권5호
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• pp.2120-2125
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• 2015

In this paper, a rectangular waveguide probe with a ridge-loaded straight slot (RLSS) is presented for a near-field scanning microwave microscope (NSMM). The RLSS is located laterally at the end wall of the cavity and is loaded on double ridges in a narrow straight slot to improve the spatial resolution compared with a straight slot. The probe consists of a rectangular cavity with an RLSS and a feed section of a WR-90 rectangular waveguide. When the proposed NSMM is located at distance of 0.1mm in front of a substrate without patches or strips, the simulated full width at half maximum (FWHM) of the probe improve by approximately 31.5 % compared with that of a straight slot without ridges. One dimensional scanning of the E-plane on a sample under test was conducted, and the reflection coefficient of the near-field scanning probe is presented.

• 대한전자공학회논문지
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• 제21권1호
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• pp.1-6
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• 1984

기하광학적 해석방법으로 입사조건에 따른 SCS(step-graded-step) 모드 스크램블러의 near field pattern, 모달 파우어 분포 및 far field pattern을 계산하고, 실험결과와 일치함을 보였다. 이로부터 SGS 모드 스크램블러에 의해 피측정 graded index 광섬유에서 stable mode launching이 이루어짐을 설명하였다. 또한 SGS 모드 스크램블러의 효과적 사용 방법으로는 입사 NA를 적게하는 것이 좋다는 것을 알았으며, 실험으로 확인하였다.

• 한국해안해양공학회지
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• 제5권2호
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• pp.91-98
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• 1993

본고는 정상류 가로흐름이 존재하는 천해역으로 방출되는 온수의 거동 예측을 위한 2차원 난류모형 개발을 기술한다. 모델 기본방정식은 수심적분된 연적 및 운동방정식, 에너지보존 방정식이 사용되며, SIMPLE로 알려진 교치기법으로 적분된다. 난류운동량 및 열확산항은 2차원 $ extsc{k}$-$\varepsilon$ 방정식으로부터 결정된다. 기존 실험결과와의 비교에서 천수역 Near-field 해역내 난류현상 재현에 유망한 기법임이 확인되었다.

• Earthquakes and Structures
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• 제20권1호
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• pp.87-96
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• 2021

Ground motions recorded in near-fault sites, where the rupture propagates toward the site, are significantly different from those observed in far-fault regions. In this research, finite element modeling is used to investigate the effect of pile cap stiffness on the seismic response of soil-pile-structure systems under near-fault ground motions. The Von Wolffersdorff hypoplastic model with the intergranular strain concept is applied for modeling of granular soil (sand) and the behavior of structure is considered to be non-linear. Eight fault-normal near-field ground motion records, recorded on rock, are applied to the model. The numerical method developed is verified by comparing the results with an experimental test (shaking table test) for a soil-pile-structure system. The results, obtained from finite element modeling under near-fault ground motions, show that when the value of cap stiffness increases, the drift ratio of the structure decreases, whereas the pile relative displacement increases. Also, the residual deformations in the piles are due to the non-linear behavior of soil around the piles.

• 한국전자파학회지:전자파기술
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• 제10권1호
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• pp.77-83
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• 1999

전파무반사실을 구축하기 위해서는 많은 비용이 요구되므로 하나의 전자파무반사실을 여러가지 용도로 사용되는 것은, 공간적, 경제적으로 매우 효율적이다. 본 논문에서는 현재 SK텔레콤에서 운용중인 안테나 및 EMC/EMI측정을 위한 다용도 전자파무반사실에 대하여 설명하고 그 성능에 대한 측정결과를 제시한다. 이 전자파무반사실은 150 MHz에서 40 GHz까지의 주파수 범위까지 Far Field와 Near field에 대한 안테나 측정이 가능한 안테나 측정시스템과 측정환경을 보유하고 있으며, EMC/EMI 측정을 위한 ANSI C63.4dhk CISPR 16.1의 요구조건을 모두 만족하고 있다.

• Geosystem Engineering
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• 제21권6호
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• pp.326-334
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• 2018

Underground water-sealed gas storage caverns have become the primary method for strategic storage of LPG. Previous studies of excavation blasting effects on large-scale underground water-sealed gas storage caverns are rare at home and abroad. In this paper, the blasting excavation for underground water-sealed propane storage caverns in Yantai was introduced and field tests of blasting vibration were carried out. Field test data showed that the horizontal radial velocity had a major controlling effect in the blasting vibration and frequencies would not cause the vibration velocity concentration effects. In terms of the influence of blasting vibration on adjacent caverns, the dynamic finite element model in LS-DYNA soft was established, whose reliability was verified by field test data. The numerical results indicated the near-blasting side was primary zone for the structural failure and tensile failure tended to occur in the middle of the curved wall on the near-blasting side. Meanwhile, the safety criterions for adjacent caverns based on stress wave theory and according to statistic relationship between peak effective tensile stress and peak particle velocities were obtained, respectively. Finally, with Safety Regulations for Blasting in China (GB6722-2014) taken into account, a final safety criterion was proposed.

• Structural Engineering and Mechanics
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• 제8권1호
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• pp.19-26
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• 1999

Superior performance of field consistent eight-node hexahedron element in static bending problems has already been demonstrated in literature. In this paper, its performance in free vibration is investigated. Free vibration frequencies of typical test problems have been computed using this element. The results establish its superior performance in free vibration, particularly in thin plate application and near incompressibility regimes, demonstrating that shear locking, Poisson's stiffening and volumetric locking have been eliminated.

• Journal of Electrical Engineering and Technology
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• 제13권1호
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• pp.406-412
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• 2018

In this paper, we propose a narrow resonant waveguide probe that can improve the measurement sensitivity in near-field scanning microwave microscopy. The probe consists of a metal waveguide incorporating the following two sections: a straight section at the tip of the probe whose cross-section is a double-ridged rectangle, and whose height is much smaller than the waveguide width; and a standard waveguide section. The advantage of the narrow waveguide is the same as that of the quarter-wave transformer section i.e., it achieves impedance-matching between the sample under test (SUT) and the standard waveguide. The design procedure used for the probe is presented in detail and the performance of the designed resonant probe is evaluated theoretically by using an equivalent circuit. The calculated results are compared with those obtained using the finite element method (Ansoft HFSS), and consistency between the results is demonstrated. Furthermore, the performance of the fabricated resonant probe is evaluated experimentally. At X-band frequencies, we have measured the one-dimensional scanning reflection coefficient of the SUT using the probe. The sensitivity of the proposed resonant probe is improved by more than two times as compared to a conventional waveguide cavity type probe.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2009년도 춘계 학술대회 제21권1호
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• pp.277-278
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• 2009

The building that supply tidal and splash zone was constructed near Seamangeum Gate Bridge. The specimens that will be tested for maintenance of gate bridge were exposed on the tidal and splash zone, totally about 650(Fig. 1). The characteristics of strength, salt penetration profile, field application of surface repair material and section recover material will be acquired by periodical test. The program was developed to obtain optimal maintenance strategy of gate bridge as a marine concrete structure and to deposit experimental data, lab. test result, field test result, on its D/B. On this paper, we hope to introduce two years exposure data as compressive strength, the modulus of elasticity, the modulus of dynamic elasticity, field adoption of repair and recover materials. As briefly speaking the results, possion's ratio, elasticity, strength was general, but the recover materials have some problems. There was crack between concrete and recover material and delamination figures.

• 한국방재학회:학술대회논문집
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• 한국방재학회 2008년도 정기총회 및 학술발표대회
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• pp.561-564
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• 2008

Rock slope had been slope failure due to geological and physical things over time. In this paper, it discusses rock slope stability analysis which was concerned about additional slope failure located near the Andong-si. Initially, achieved basic geological investigation and field test about rock slope, examine the stability of rock slope by doing limit equilibrium method and stereographic projection about 5 slopes.