• 한국지반공학회논문집
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• 제25권4호
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• pp.69-75
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• 2009

본 연구에서는 수평하중을 받는 파일벤트(pile-bent) 구조의 변단면에 따른 거동특성을 분석하기 위하여 beam-column 모델을 적용하여 수평변위 및 모멘트, 부재력(응력)을 단일단면 파일벤트 구조의 수평거동과 비교하였다. 분석결과 지표면에서 변단면 파일벤트 구조의 수평변위량이 동일하중 재하시 단일형 파일벤트 구조의 수평변위량보다 커지는 경향을 보였으나, 동일지반, 동일하중조건의 경우에는 변단면 존재유무에 관계없이 최대휨모멘트 발생위치는 일정한 경향을 보였다. 또한 말뚝재료의 부재력 검토 결과 파일벤트 구조의 변단면 부분에서의 부재력이 최대침모멘트 발생 깊이에서의 부재력보다 큰 것으로 나타났다. 이는 일체형 말뚝의 구조적 특성으로 최대침모멘트 발생위치보다 변단면 부분의 단면축소로 인해 취약해지기 때문에 변단면 발생부분에 대한 보강이 필수적으로 요구됨을 알 수 있었다.

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2005년도 종합학술발표회 논문집 Vol.15 No.1
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• pp.217-220
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• 2005

In this paper describes novel m antenna using aperture matched type slot structure. It substitutes edge diffractions by curved-surface diffractions which have a tendency to provide an undisturbed energy flow across the junction, around the curved surface, and into free-space. The proposed antenna is composed of a CPW feed structure, exponential tapered slot and the curved sectional at the edge. experimental resulte show that aperture matched type slot improve the performance of the UWB antenna.

• 전기학회논문지
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• 제59권6호
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• pp.1126-1130
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• 2010

Speech production can be viewed as a filtering operation in which a sound source excites a vocal tract filter. The vocal tract is modeled as a chain of cylinders of varying cross-sectional area in linear prediction acoustic tube modeling. In this modeling the most common implementation assumes equal length of tube sections. Therefore, to model complex vocal tract shapes, a large number of tube sections are needed. This paper proposes a new vocal tract model with unfixed sectionlengths, which uses the reduced lattice filter for modeling the vocal tract. This model transforms the lattice filter to reduced structure and the Burg algorithm to modified version. When the conventional and the proposed models are implemented with the same order of linear prediction analysis, the proposed model can produce more accurate results than the conventional one. To implement a system within similar accuracy level, it may be possible to reduce the stages of the lattice filter structure. The proposed model produces the more similar vocal tract shape than the conventional one.

• 대한수학회논문집
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• 제29권1호
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• pp.131-140
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• 2014

In this paper we investigate (n+1)($n{\geq}3$)-dimensional contact CR-submanifolds M of (n-1) contact CR-dimension in a complete simply connected Sasakian space form of constant ${\phi}$-holomorphic sectional curvature $c{\neq}-3$ which satisfy the condition h(FX, Y)+h(X, FY) = 0 for any vector fields X, Y tangent to M, where h and F denote the second fundamental form and a skew-symmetric endomorphism (defined by (2.3)) acting on tangent space of M, respectively.

• Structural Engineering and Mechanics
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• 제8권4호
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• pp.401-410
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• 1999

A method of optimum design based on reliability for antenna structures is presented in this paper. By constructing the equivalent event, the formula is derived for calculating the reliability of reflector accuracy of antenna under the action of random wind load. The optimal model is developed, in which the cross sectional areas of member are treated as design variables, the structure weight as objective function, the reliability of reflector accuracy and the strength or stability of structural elements as constraints. The improved accelerated convergence gradient algorithm developed by the author is used. The design results show that the method in this paper is feasible and effective.

• 마이크로전자및패키징학회지
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• 제8권2호
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• pp.15-18
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• 2001

Magnetron sputtering 장비를 이용하여 극자외선 노광 공정용 Mo/Si 다층 박막을 증착하였다. 증착 파워로는 Mo의 경우 DC파워를, Si의 경우 RF파워를 이용하였다. 각각의 target에 인가되는 DC 또는 RF 파워의 시간 및 파워 조절을 통해서 원하는 구조인자를 가진 다층박막을 증착하였다. 증착된 다층박막을 단면 TEM, low/high angle XRD 등을 이용하여 박막의 미세구조와 interfacial layer의 거동을 살펴 보았으며, low angle XRD로부터 다층박막을 간접적으로 평가할 수 있었으며, 단면 TEM으로부터 Si위에 형성되는 Mo의 interfacial layer가 Mo위에 형성되는 경우보다 두꺼운 것을 알 수 있었다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계학술발표회 논문집(I)
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• pp.474-477
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• 2006

To predict thermal stress independent of uncertain material properties of early age concrete, such as elastic modulus and creep, thermal stress device is used. In order to verify the application of various degree of constraint in the thermal stress device, a series of experiments were performed on mass concrete followed by numerical simulation. The application of various degrees of constraint can be achieved by using constraint frame material with different thermal expansion coefficient, length, and cross sectional area. Temperature development in the real structure has been simulated using temperature and humidity control chamber. The results from experiments and numerical analysis show that the thermal stresses estimated from simulation agree well with the general stress variations in the real structure even though the properties of concrete are uncertain.

• 대한기계학회논문집B
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• 제29권5호
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• pp.561-567
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• 2005

The effect of triangular multi-tabs attached at the perimeter of jet nozzle on flow structure in the near field was investigated experimentally. A stereoscopic PIV(SPIV) system was employed to measure three orthogonal velocity components of the 3-D turbulent jet. In this study, two different types of sharp-edged jet nozzle having 4, 8 tabs were tested at the Reynolds number of Re=10,000. SPIV measurements were carried out at 5 cross-sectional planes. Six hundred instantaneous velocity fields were measured for each experimental condition and they were ensemble averaged to get spatial distributions of turbulent statistics such as mean velocity and turbulence intensity. Entrainment rate of surrounding fluid into the tabbed jets was estimated using the measured 3-D velocity field data. The strong vortex structure was induced for the jet flow with 4 tabs, increasing entrainment rate.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2002년도 추계 학술발표회 논문집
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• pp.274-281
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• 2002

In this study a analytical model for a structure with buckling-restrained unbonded knee-braces is proposed, and a performance-based seismic design procedure for such a system Is provided. The proposed structure system has advantage of simplifying the structural design procedure in that the hinge-connected main structural members, such as beams and columns, are designed only for gravity loads, and all the lateral seismic load is resisted by the braces. The design procedure is based on the concept of equivalent damping, and is implemented to the capacity spectrum method. Parametric study is performed with design variables such as yield stress and cross-sectional area of knee-braces to find out proper slope of the braces.

• 한국표면공학회지
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• 제28권6호
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• pp.376-385
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• 1995

Copper-chromium multilayers with a nominal bilayer thickness of about 400 $\AA$ (200 $\AA$ each) were prepared by dc magnetron sputtering and the evolution of microstructure during heat treatment was investigated by using x-ray diffractometry(XRD), Auger electron spectroscopy(AES) and transmission electron microscopy(TEM). It was observed that an amorphous phase with a thickness of about 40 $\AA$ was formed at the interfaces of the as-deposited Cu/Cr multilayered film using cross-sectional TEM. At elevated temperatures, the Cu(111) reflection showed increasing intensity and decreasing line-width as a result of copper grain growth. The intermixed amorphous phase disappeared after annealing at $250^{\circ}C$ for 1 h and the multilayer structure was stable up to $400^{\circ}C$ for 1 h annealing. At $600^{\circ}C$ annealing, it was observed that the multilayer structure was completely destroyed and copper and chromium phases were fully intermixed.