• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.8
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• pp.61-67
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• 2010

A characterization procedure for analyzing symmetric coupled MIS(Metal-Insulator-Semiconductor) transmission line is used the same procedure as a general single layer symmetric coupled line with perfect dielectric substrate from the extraction of the characteristic impedance and propagation constant for even- and odd-mode. In this paper, an analysis for a new substrate shielding symmetric coupled MIS structure consisting of grounded crossbar at the interface between Si and SiO2 layer using the Finite-Difference Time-Domain (FDTD) method is presented. In order to reduce the substrate effects on the transmission line characteristics, a shielding structure consisting of grounded crossbar lines over time-domain signal has been examined. Symmetric coupled MIS transmission line parameters for even- and odd-mode are investigated as the functions of frequency, and the extracted distributed frequency-dependent transmission line parameters and corresponding equivalent circuit parameters as well as quality factor for the new MIS crossbar embedded structure are also presented. It is shown that the quality factor of the symmetric coupled transmission line can be improved without significant change in the characteristic impedance and effective dielectric constant.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.4
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• pp.297-305
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• 2018

The role of UCAV is to carry out various missions in hostile situations such as penetration and attack on the enemy territory. To this end, application of RF stealth technology is indispensable so as not to be caught by enemy radar. The X-47B UCAV with blended wing body configuration is a representative aircraft in which modern RCS reduction schemes are heavily applied. In this study, a model UCAV was first designed based on the X-47B platform and then an extensive RCS analysis was conducted to the model UCAV in the high-frequency regime using the Ray Launching Geometrical Optics (RL-GO) method. In particular, the effects of configuration of UCAV considering IR reduction on RCS were investigated. Finally, the effects of RAM optimized for the air intake of the model UCAV were analyzed.

• The Journal of the Korea Contents Association
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• v.9 no.12
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• pp.836-842
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• 2009

On April 14, 2008, National Human Rights Commission of Korea's recommendation led to severe argument that hiring qualification of religious school. it shall not be an unlawful employment practice for a school, college, university, or other educational institution or institution of learning to hire and employ employees of a particular religion if such organizations is, in whole or in substantial part, owned, supported, controlled, or managed by a particular religion or by a particular religious corporation, association, or society, or if the curriculum of such organizations is directed toward the propagation of a particular religion. An employer is a "religious organization" entitled to the exemption. So If the employer is a school, its history and mission, the religion of the faculty and students, and the religious focus of the curriculum must be examined. Consequently it is possible for religious educational institution to reject specific religionist.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.20 no.5
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• pp.629-640
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• 2007

In this paper an analytical study is carried out to improve the capacity of absorbing boundary using dashpot, one of the most widely used absorbing boundaries in FEM. Using 2-D harmonic plane wave equation, absorbing boundary condition is modified to maximize its capacity according to the incident angle. Validity of the absorbing boundary conditions which is modified is investigated by adopting the solution of Miller and Pursey. The Miller and Pursey's problem is then numerically simulated using the finite element method. The absorption ratios are calculated by comparing the displacements at the absorbing boundary to those at the free field without the absorbing boundary. The numerical study is carried out through comparison of displacement at the interior region and the boundary of the numerical model.

• Bulletin of the Society of Naval Architects of Korea
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• v.26 no.2
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• pp.1-12
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• 1989

This paper presents a method of minimizing the wave resistance components, due to the linear wave propagating to the far field and the breaking wave in the vicinity of the hull. This method consists of the linear optimization method for the linear wave resistance and the statistical optimization method for the breaking wave resistance through the analysis of the experimental data. For the purpose of the application, a wall-sided model with parabolic waterplane shape was selected as a basic hull form, and two modified hull forms with varied $C_p-curve$ of the fore-body were derived from the linear wave optimization method and the empirical method. The correlation between the linear wave resistance and the breaking wave resistance according to the $C_p-curve$ variation of the fore-body was investigated through the experimental and analytical results for the three hull forms. The fore-body shape optimized by the present method shows the reduction of the wave resistance by 47% comparing to the basic hull form at the design speed($F_n=0.26$).

• Geotechnical Engineering
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• v.14 no.3
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• pp.95-108
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• 1998

Downhole testing and seismic CPT (SCPT) have been widely used to evaluate stiffness profiles of the subgrade. Advantages of downhole testing and SCPT such as low cost, easy operation and a simple seismic source have got these testings more frequently adopted in site investigation. For the automated analysis of downhole testing and SCPT, the concept of interval measurements has been practiced. In this paper. a new inversion procedure to deal tilth the interval measurements for the automated downhole testing and SCPT (including a newlydeveloped continuous SCPT) is proposed. The forward modeling in the new inversion procedure incorporates ray path theory based on Snell's law. The formulation for the inversion analysis is derived from the maximum likelihood approach, which estimates the maximum likelihood of obtaining a particular travel time from a source to a receiver. Verification of the new inversion procedure was performed with numerical simulations of SCPT using synthesized profiles. The results of the inversion analyses performed for the synthetic data show that the new inversion analysis is a valid procedure which enhances Va profiles determined by downhole testing and SCPT.

• Journal of Korea Water Resources Association
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• v.34 no.1
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• pp.45-55
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• 2001

Transcritical flow is a term intended to denote the existence of both supercritical and subcritical flows within a computational domain. The major problems that need to be addressed while modeling transcritical flows include handling the differing features of signal propagation in subcritical and supercritical flow regions and maintaining conservation. The present study proposes the implicit ENO method as a high-resolution scheme for transcritical flow. This implicit ENO scheme is based on the ENO method, a new class of uniformly high-order-accurate essentially non-oscillatory implicit scheme, which has the advantage of unconditional stability. The implicit ENO scheme has not been used for the transcritical flow in open channel until now. As a result of application to the hypothetical dam-break flow, the implicit ENO scheme was ploved to produce accurate results with good robustness even though in the case of verb strong shock wave.

• Korean Journal of Materials Research
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• v.10 no.5
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• pp.321-327
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• 2000

Two kinds of $Al_2O_3/TZP$ composites were prepared using the liquid infiltration of 3Y-TZP and 12Ce-TZP precursors into hte sintered porous $Al_2O_3$. Small TZP additions(~11.0wt%) had increased the strength(19~59%) and fracture toughness(14~157%) of the sintered Al2O3 material($1600^{\circ}C$, 2h). The addition of 3Y-TZP was effective on case of the strength. By the way, in case of the fracture toughness that of 12Ce-TZP was effective. Infiltrated TZP was concentrated on the surface where its grain growth was enhanced and $Al_2O_3$ grain growth was effectively inhibit-ed, when compared to the inner region of the composite. The indentation crack was propagated through both intergranular modes and transgranular and the proportion if intergranular fracture was the larger in $Al_2O_3/12Ce-TZP$.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2011.03a
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• pp.97-97
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• 2011

현대사회에서 화재에 의한 물적 피해는 물론 인적피해가 현저하게 증가하고 있으며 희생자의 사망원인이 종래에는 화재시 발생한 열에 의한 화상을 중심으로 하는 소사였지만, 최근에는 화염보다 독성가스로 인하여 사망하는 경우가 많아졌고, 희생자는 거의 화상을 확인할 수 없거나 화상자이더라도 혈액 중에서 일산화탄소를 중심으로 한 유독가스가 확인되기 때문에 이들 유독가스의 흡입으로 인하여 행동불능상태 이후 열의 영향으로 사망한 것으로 추정되는 사례가 증가하는 추세이다. 따라서 대규모 건축물에 있어서는 화재발생시 유독가스가 건물 전체로 연소 확대되는 것을 방지하기 위하여 넓은 면적을 일정한 면적으로 구획하거나 계단실 등과 다른 부분 또는 층별 등으로 구획하고 있으며, 국내의 방화구획은 크게 다른 층으로 화재전파를 막기 위한 층간 방화구획, 연소면적을 제한하기 위한 면적별 방화구획, 다른 용도로 인한 화재 위험성 감소를 위해 용도별 방화구획으로 3가지를 법에서 채택하고 있다. 방화구획은 방화문 또는 자동방화셔터를 이용하거나, 내부구조의 바닥, 벽, 각종 방화문으로 구획할 것을 정하고 있다.(피난방화규칙 제14조) 본 연구에서는 철제방화셔터 대체용으로 직물방화셔터용의 실리카 소재를 이용하여 제직한 직물에 내열/차연 기능성 코팅의 공정 조건을 변화하여 최종 방화시험을 거치기 전 내열성 테스트중 하나인 불꽃열 통과량 실험을 실행하여 방화 직물의 내열성을 비교 분석하였다. 이러한 결과를 토대로 본 연구는 고내열/차연성 방화 제품 기술을 개발하는데 필요한 연구를 수행하는데 목적이 있다.

• Tunnel and Underground Space
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• v.11 no.4
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• pp.344-351
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• 2001

In the tunnelling by blasting, the calculations of charge weight and the estimations of blasting effect have been simply carried out by empirical formulas. Also, it has been rare to consider the impact energy of blasting in numerical analyses. Thus in this study a numerical modeling technique of blasting load is developed and used with the 2 dimensional distinct element method(DEM) to consider the nonlinear behaviour of discontinuous underground structures. TD examine and verify its applicability of the numerical model to actual problems, a blasting of tunnel under an embankment is numerically analysed with DEM. It is examined that the behavior of circumference structures, the displacements of above- and under-ground structures, and the propagation of particle velocities can be known by this numerical analysis. As a result, the blasting load model, proposed by this study, can be applied to actual problems. This model applied with DEM can be used in the examination of structural stability.