• Journal of the Earthquake Engineering Society of Korea
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• v.11 no.5
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• pp.11-21
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• 2007

Currently in the country, the necessity of seismic analyses is increasing due to the increase of demand and interest in seismic design. Especially, shear wall apartments are constructed mostly for a residental building so seismic analyses for the apartment are actively executed. For the seismic analysis of the shear wall apartment, it may be not efficient in time and effort to model the entire structure by a finite element mesh. Therefore, an equivalent model is needed to simulate the dynamic behavior of the structure by decreasing the number of degrees of freedom. In this study, a method to form an equivalent model that is simple and easy to use was proposed utilizing effective mass coefficient that is highly correlated to mode shape of the structure. This equivalent model was obtained by replacing a shear wall structure with an equivalent frame structure having beams and columns. This model can be used very effectively when excessive seismic analyses are necessary in a short period because it can be operated in any commercial program and reduce the analysis time. Also, it can model floor slabs so it can represent the actual behavior of shear wall apartments. Furthermore, it is very excellent since it can represent the asymmetry of the structure.

• The Journal of Korean Society for Radiation Therapy
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• v.29 no.1
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• pp.93-101
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• 2017

Purpose: In breast cancer radiotherapy, brass mesh bolus has been recently studied to overcome disadvantage of conventional bolus. The purpose of this study is to investigate the stability of first introduced the brass mesh in the country, and evaluate the skin surface dose of that. Materials and Methods: The measurement of skin surface dose was evaluated to verify similar thickness of the Brass mesh bolus that compared conformal tissue equivalent bolus with 5 mm thickness. We used 6 MV photons on an ELEKTA VERSA linear accelerator and optically stimulated luminescent dosimeter (OSLD). In addition, two opposed beam using IMRT phantom was applied to comparative study of brass mesh bolus between tissue equivalent bolus. Results: The results showed that similar thickness of the Brass mesh bolus was 3 mm compared with 5 mm tissue equivalent bolus by measuring the skin surface dose of solid phantom. The surface dose for IMRT thorax phantom using 3 mm brass mesh bolus was about 1.069 times greater than that using tissue equivalent bolus. Conclusion: In this study, we found that the brass mesh bolus improved better reduction of skin sparing effect and dose uniformity than tissue equivalent bolus. However evaluation for various clinic cases should be investigated.

• Korean Journal of Optics and Photonics
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• v.23 no.1
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• pp.17-22
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• 2012

An equivalent lens is a lens which has the same total power of refraction and the same paraxial imaging characteristics for the marginal rays as another lens, but has a different axial thickness. In this study, an analytic lens conversion from a thick lens to its equivalent lens is investigated, then it is shown that the equivalent lens is a solution of a quadratic equation. Every thick lens corresponds to one of two real roots of this quadratic equation. Therefore, except in the case of a unique solution, the equation has a conjugate solution, the other of the two roots. The conjugate solution has the same axial thickness, power, and paraxial imaging characteristics, but it has different shape and aberration characteristics. The characteristics of an equivalent lens and its conjugate solution are examined by using a sample lens.

• Magazine of the Korea Concrete Institute
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• v.10 no.3
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• pp.143-152
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• 1998

본 연구에서는 콘크리트 강도에 미치는 양생온도의 영향이 양생시점에 따라 어떻게 변하는지에 대한 실험과 기존의 모델식을 이용하여 분석을 수행하였으며, 양생시점의 영향을 고려한 수정된 등가재령식을 제시함으로써 새로운 강도예측식을 개발하기 위한 기초연구이다. 이를 위해 2종류의 물.시멘트비에 대하여 각각 11종류의 양생이력을 고려한 실험을 수행하였다. 실험변수로는 3종류의 양생온도 (5 $^{\circ}C$, 20 $^{\circ}C$, 4$0^{\circ}C$)와 4종류의 양생시점(0~1일. 1~2, 2~3, 6~7일)을 선정하였다. 또 기존의 Saul 및 Arrhenius 모델식을 이용하여 실험결과를 분석하여 양생시점의 영향을 도입한 각각 수정된 등가재령식을 제시하였다. 실험결과에서 초기재령에서 고온 양생한 경우에는 초기에는 높은 강도를 나타내지만 재령이 증가할수록 오히려 낮은 강도를 나타내었다. 또 초기에 저온으로 양생한 콘크리트는 그 반대의 경향을 보였다. 기존의 등가재령식에서는 같은 등가재령에서도 압축강도는 양생시점에 따라 달라짐을 알 수 있었다. 기존의 모델식은 특히 초기재령에서의 강도예측결과가 실험결과와 잘 맞지 않았으나 이 논문에서 제시된 수정된 등가재령식은 실험결과와 잘 일치하는 결과를 보여 주었다.

• Aerospace Engineering and Technology
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• v.9 no.2
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• pp.73-79
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• 2010

In this study, the equivalent elastic modulus of flexible textile composites was predicted by nonlinear finite element analysis. The analysis was carried out considering the material nonlinearity of fiber tows and the geometrical nonlinearity during large deformation using commercial analysis software, ABAQUS. To account for the geometrical nonlinearity due to the large shear deformation of fiber tows, a user defined material algorithm was developed and inserted in ABAQUS. In results, nonlinear stress-strain curve for the flexible textile composites under uni-axial tension was predicted from which effective elastic modulus was obtained and compared to the test result. The effective elastic moduli were calculated for the various finite element models with different waviness ratio of fiber tow.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.9A
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• pp.1434-1441
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• 1999

This paper presents an equivalent circuit of the hairpin line filter for accurate analysis and design. Its validity was verified by computer simulations and filter design experiments. Though the various design equations for a hairpin line filter have been proposed, there has not been a practically simplified equivalent circuit because it is hard to effectively represent interconnection effects between non-adjacent elements. In this paper, all the open ports of the hairpin line filter circuit are changed to the short ports using circuit duality, and the resulting circuits are transformed to graph model. The further simplified circuit model is obtained from boundary conditions, and then the final equivalent circuit of the hairpin line filter is derived in a dual structure of the filter.

• Korean Journal of Optics and Photonics
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• v.15 no.1
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• pp.56-62
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• 2004

We present a diffraction grating interferometer of large equivalent wavelength specially designed for flatness testing of rough surfaces. Two transmission diffraction gratings are illuminated on the object under test by use of two measurement beams with different angles of incidence, which yields a large equivalent wavelength. This interferometer design minimizes unnecessary diffraction rays and the systematic error caused by the diffraction gratings, and provides a large working distance and easy alignment. To improve the measurement accuracy, phase shifting technique is applied and the equivalent wavelength error caused by defocus is calibrated. Test results obtained from mirror surfaces and machined rough surfaces are discussed.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.1 s.92
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• pp.78-83
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• 2005

LTCC filters have been widely used to wireless terminals. They generally adopt the multilayer structure. Some of multilayer LTCC filters are made of symmetrical parallel-coupled lines and anti-symmetrical parallel-coupled lines to reduce the length of resonators. The equivalent circuit of parallel-coupled lines was analyzed and applied to bandpass filters using multilayer parallel-coupled line resonators. The three-pole bandpass filter with the center frequency of 2.45 GHz is designed by using the proposed equivalent circuit and the measured results have good agreement with the design results.

• Korean Journal of Ichthyology
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• v.12 no.1
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• pp.54-61
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• 2000

Feeding habits of Zoarces gilli collected in the coastal water off Gadeok-do, Korea from March 1998 to February 1999 were studied. Z. gilli was a carnivore and consumed mainly shrimps, gammarid amphipods, fishes, bivalves and cumaceans. Its diets also included small quantities of copepods, caprellid amphipods, ostracods, crabs, squids, gastropods, ophiuroids and polychaetes. It showed ontogenetic changes in feeding habits. Individuals of small size (10~15 cmSL) fed mainly on small prey organisms such as gammarid amphipods, bivalves, cumaceans and ostracods. However, larger shrimps and fishes were heavily selected with increasing fish size.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.10
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• pp.1121-1127
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• 2010

This paper describes the equivalent circuit of $45^{\circ}$ layer, one of $11.25^{\circ}$, $22.5^{\circ}$, and $45^{\circ}$ phase shift layers, which are needed for X-band Radant lens 4-bit phase shifter. The equivalent circuit is extracted by comparing the CST's MWS results with the Agilent's ADS results for $45^{\circ}$ phase shift layer. The simulated result is compared with the measured one. Using the extracted equivalent circuit, the phase bit simulation results of 4-bit Radant lens are also presented.