• 한국전산구조공학회:학술대회논문집
• /
• 한국전산구조공학회 1997년도 봄 학술발표회 논문집
• /
• pp.89-96
• /
• 1997

Most civil engineering structures, such as highway bridges, towers, power plants and offshore structures suffer structural damages over their service lives caused by adverse loading such as heavy transportation loads, machine vibrations, earthquakes, wind and wave forces. Especially, if excessive load would be acted on the structure, general or partial stiffness should be degraded suddenly and service lives should be shortened eventually For realistic damage assessment of these civil structures, System Identification method using only structure dynamic response data with unknown input excitation is required and thus becoming more challenging problem. In this paper, an improved Iterative Least Squares method is proposed, which seems to be very efficient and robust method, because only the dynamic response data such as acceleration, velocity and displacement is used without input data, and no information on the modal properties is required. The efficiency and robustness of the proposed method is proved by numerical problems and real single span beam model test.

• Wind and Structures
• /
• 제4권4호
• /
• pp.353-366
• /
• 2001

With respect to serviceability, antenna masts should be designed so that wind-induced motion will not cause unacceptable lack of transmission for broadcasting users and wireless communication. For such antenna masts with directional radio transmission the serviceability limit state is predominantly governed by the tolerable change of the broadcasting angle of the mounted antenna assembly and therefore by the tip distortion of the mast. In this paper it will be shown that refinements of the present state of design of antenna masts are possible by using the statistics of extremes applied to extreme wind situations and by consideration of the statistical and reliability requirements given by the operator such as frequency and return period of passing the serviceability limit.

• 동굴
• /
• 제86호
• /
• pp.1-7
• /
• 2008

지질구조는 카르스트의 층위와 구조상의 배열에 있어서 다양한 카르스트의 지형을 결정한다. 카르스트의 발달은 조산 및 조륙운동, 석회암층의 두께, 구성물질의 유형, 단층 및 습곡의 다양성, 주향 및 절리면의 빈도, 기후변화 및 기상환경, 수문 및 유수의 유형, 토지이용 현황 외 환경오염 등에 따라서 차별성을 나타낸다. 특히 지질구조에 따른 카르스트의 발달은 석회암 등이 유수의 작용에 커다란 용해작용의 영향을 받으므로 지질구조의 요인인 단층과 습곡현황과 절리와 균열 등에 의한 카르스트의 발달에 가장 큰 기여를 한다. 지질구조에 의하여 카르스트 지표지형에는 karren과 hum, mogotes, doline와 uvala, towers, springs, 구조적 유역, Closed Systems 등이 형성되고, 지하지형에는 Phreatic 동굴, Vados 동굴, Chambers, Multileveling cavities, Vertical shafts 등이 형성되는 다양성을 가진다. 한반도에서는 습곡구조에 의한 동공의 발달이 탁월하며, 다단계 및 급사면형 동굴의 유형이 다양하게 분포되고 있다.

• 대한기계학회논문집
• /
• 제13권3호
• /
• pp.554-560
• /
• 1989

본 연구에서는 실제 운행시에 발생할 수 있는 최악의 경우를 모든 반기의 무게를 집중질량으로 고려한 충실한 해석을 통하여 구해보고자 하였다. 이를 위하여 하나의 구간에 여러 개의 집중질량이 달린 경우에 대한 선로방정식을 유도하였고, 최소반력을 구하기 위한 문제를 최적설계 문제로 정의한 다음, 이를 체험적 최적설계 기법(heuristic optimization technique)을 통하여 해결하였다. 또한 예재해석을 통하여 최악의 상태가 발생하게 될 일반적인 조건을 구하였다.

• 한국주거학회:학술대회논문집
• /
• 한국주거학회 2005년도 추계학술대회 논문집
• /
• pp.283-286
• /
• 2005

In the modern city in which the high-density and complex land use is needed, high-rise residential-commercial buildings appeared as a scheme to arrange a metropolitan residence with multiple high-techs and to induce activation of the city with leading the settled population to flow into the city. And the need of the times is to actively apply the eco-friendly notion to the architecture. In this study, the works of Ken Yeang who is regarded as an eco-friendly architect to make high-rise residential-commercial buildings ecological should be focused on with analyses of eco-friendly characteristics in inside, intersection between inside and outside, and outside of his works. The result o the study would be the suggestion to design eco-friendly high-rise buildings which make the city rise in quality.

• 콘크리트학회논문집
• /
• 제11권3호
• /
• pp.161-170
• /
• 1999

The KLCC Petronas Tower 2, one of the world tallest twin reinforced concrete towers constructed in Kuala Lumpur, Malysia, was instrumented during construction for the measurement of vertical time-dependent deformation of columns and corewall. Field measurements were made by means of vibrating wire strain gauges at the corewall, tower and bustle perimeter columns at selected floor levels of the building. Parallel to this observation, laboratory tests were performed on concrete cylinders made in the field in order to obtain the variations of concrete compressive strengths, elastic moduli, strains of creep and shrinkage with time. Monitored vertical deformations are in a good agreement with the prediction based on actual construction sequence and concrete properties from laboratory tests, as well as the analytical results reflected in actual column compensation of the building.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 1999년도 추계학술대회 논문집
• /
• pp.582-585
• /
• 1999

Electroluminescence is occurred when phosphor is located in electric field. In this paper, we made powder electroluminescent device (PELD) with structured ITO film/Phosphor/Insulator/Silver paste. The transparent electrode was ITO film and green(2704-01) and orange(2702-02) and blue-preen(2703-01) were used as phosphor. The insulator was BaTiO$_3$ and $Y_2$O$_3$, bark electrode was silver paste. To investigate electrical and optical properties of PELDs, EL spectrum, Brightness . Transferred charge density using Sawyer-Towers circuit was measured.

• Wind and Structures
• /
• 제16권5호
• /
• pp.457-476
• /
• 2013

This paper presents theoretical background for a semi-empirical, mathematical model of critical vortex excitation of slender structures of compact cross-sections. The model can be applied to slender tower-like structures (chimneys, towers), and to slender elements of structures (masts, pylons, cables). Many empirical formulas describing across-wind load at vortex excitation depending on several flow parameters, Reynolds number range, structure geometry and lock-in phenomenon can be found in literature. The aim of this paper is to demonstrate mathematical background of the vortex excitation model for a theoretical case of the structure section. Extrapolation of the mathematical model for the application to real structures is also presented. Considerations are devoted to various cases of wind flow (steady and unsteady), ranges of Reynolds number and lateral vibrations of structures or their absence. Numerical implementation of the model with application to real structures is also proposed.

• 산업공학
• /
• 제13권4호
• /
• pp.717-724
• /
• 2000

In this paper, an integrated system of optimal design, performance evaluation, and die design and manufacturing of axial fans for cooling tower is presented. The design and performance evaluation are developed based on three dimensional flow analysis so as to ensure low noise and high efficiency. The methodologies are implemented on computer as a GUI system including 3-D surface modeling and 2-D drawing file output modules. The CAD/CAM system is engaged to design the die and generate NC tool path, but the processes are also automated and integrated into the system by means of a part program coded from the design data. It is shown that the newly developed fans have superior performance and shortened lead-time compared to the existing dead-copied fans.

• 한국안전학회지
• /
• 제16권2호
• /
• pp.97-102
• /
• 2001

Anchors are often used in construction of foundations such as transmission towers to resist uplifting forces. When plate anchors are embedded in soft clay, they may undergo a deformation under the pressure of sustained load. In soft saturated clays, the suction force can be a large par of the ultimate uplift capacity. This study is to present recent laboratory model test results conducted to evaluate the nature of variation of the suction force for plate anchors with shear strength and embedment ratio. The ratio of F$_{s}$Q$_{n}$ versus H/D in bentonite decreases with the increase of the embedment ratio.o.o.