• Wind and Structures
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• v.10 no.6
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• pp.543-554
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• 2007

The suspension bridge is situated in an area of complex topography with both open sea and overland turbulence characteristics, and it is subject to frequent typhoon occurrences. This paper investigates experimentally the possible vortex shedding events of the structure under high wind and typhoon conditions. A single-degree-of-freedom model for the vibration of a unit bridge deck section is adopted to determine the amplitude of vibration and to estimate the parameters related to the lifting force in a vortex shedding event. The results of the studies are presented in a companion paper (Law, et al. 2007). In this paper, statistical analysis on the measured responses of the bridge deck shows that the vibration response at the first torsional mode of the structure has a significant increase at and beyond the critical wind speed for vortex shedding as noted in the wind tunnel tests on a section model of the structure.

• Wind and Structures
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• v.21 no.1
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• pp.63-84
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• 2015

The shape of a tall building has significant impact on wind force generation and wind-induced dynamic response. To study the effect of recessed cavities, wind excitations on a wind-tunnel model of an H-section tall building were compared with those on a square-section building model. Characteristics of the fluctuating wind pressures on the side faces of the two tall buildings and their role in the generation of crosswind forces on the buildings were investigated with the space-time statistical tool of proper orthogonal decomposition (POD). This paper also compares the use of different pressure data sets for POD analysis in situations where pressures on two different surfaces are responsible for the generation of a wind force. The first POD mode is found to dominate the generation of crosswind excitation on the buildings.

• Journal of the Korean Society for Nondestructive Testing
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• v.23 no.6
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• pp.616-621
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• 2003

There are various Non-Destructive Evaluation (NDE) techniques used for measurement of residual stresses in material, such as magnetic methods, X-ray diffraction, Ultrasonic velocity measurement etc. The capabilities, applications and limitations of these techniques for evaluation of cold work/plastic deformation were studied and compared. Mild steel plates were subjected to different degree of cold deformation and were analyzed by Magneto-mechanical Acoustic Emission (MAE), Barkhausen Noise (BN) and magnetic properties (hysteresis loop parameters analysis). Further, these specimens were analyzed by X-ray diffraction and ultrasonic velocity measurements. The microhardness measurement and microstructure studies of these cold worked plates were also carried out. The results of all these studies and comparison of different techniques are discussed in this paper.

• Korean journal of applied entomology
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• v.1
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• pp.47-50
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• 1962

Ripe rot, caused by Glomerlla cingulata is the most destructive disease of grapes in korea. this experiment was to determine the most effective control teratment for ripe rot of grapes. The variety, Campbell Early, was used in the trials planted on land managed by the Pomology Section of the Horticultural Experiment Station. This experiment indicated that Tuzet and Delan-wp were most effective in the control of ripe rot of grapes either with or without bagging in 1962.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.34D no.1
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• pp.41-48
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• 1997

Design rules of directional coupler optical switches are discussed in consideration of parasitic couplings in the bending section. The parasitic coupling phenomenon is analyzed based on the coupled-mode theory and the solutions are represented in the form of the transfer matrix. The modified switching conditions due to the parasitic coupling are derived and the resultant switching diagrams are illustrated. It is revealed that the parallel section's length needs to be adjustd less than the coupling length $l_c(=\pi/2\textsc{k}o)$ to obtain the desired crosstalk and that the adjustment depends on the strength of the parasitic coupling. However, it is discovered that, for weak parasitic coupling, the switching voltage does not need to be altered but may maintain the same value as if no parasitic coupling is taken into account.

• Structural Engineering and Mechanics
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• v.13 no.1
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• pp.1-16
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• 2002

This paper presents the findings of an investigation carried out to determine the most appropriate connections, in terms of rotational stiffness, to use for the optimum design of cold-formed Zed section sleeve joint purlin system. Experiments and parametric studies were conducted to investigate the effects of geometric variables on the behavior of the sleeve-purlin and cleat-purlin connections of the sleeve joint purlin system. The variables considered were purlin size and thickness, sleeve size, thickness, length and bolt position. The test results were used to verify the empirical expressions, developed herein, employed to determine the rotational stiffness of connections. With the predicted connection stiffness, the most suitable sleeve-purlin and cleat-purlin connections can be selected so as to produce an optimum condition for the sleeve joint purlin system.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.34 no.3
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• pp.283-286
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• 1998

For the systematic study on the resistance characteristics of the planing hull, the experimental studies on the correlation between geometrical characteristics of the subject hull forms and their hydrodynamic characteristics are carried out. This study is the first stage to develop the advanced planing hull type fishing boat and involves the followings; -Resistance characteristics for typical four different section types, -Resistance characteristics for different length-beam ratio

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.57 no.3
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• pp.332-337
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• 2008

We analyzed carbonization pattern and crystal structure of polyvinyl chloride wire by thermal stress. Copper that is oxidized at normal temperature is a reddish brown. If under the thermal stress range of 500 to 700 [$^{\circ}C$], carbonization and exfoliation occurrence. Section structure of electric wire is same as arrangement of particle in metallograph analysis. But, as thermal stress increases, size of particle is enlarged. Electric wire displays elongation structure in SEM image analysis and elongation structure collapses when receive thermal stress at 300 [$^{\circ}C$]. In EDX analysis, we get the spectra of CuL, CuK, OK, and ClK. FT-IR analysis was shown new spectra with in range of $1,440{\sim}1,430\;[cm^{-1}]$, 1,340 [$cm^{-1}$], 1,240 [$cm^{-1}$].

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.601-604
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• 2008

The flow pulsation of two parallel channels is investigated using RANS and URANS approaches. The parallel channels are connected with a small gap and have different cross section areas. The ratio of a right side area and a left side area ($A_R$ / $A_L$) is 0.5. Computations are conducted using a CFX code. Turbulence models adopted for RANS are Reynolds stress model and Shear Stress Transport (SST) model. The bulk Reynolds number is 60,000. Predicted results are compared with the experimental result of Lee et al. and show the flow pulsation with the frequency of about 100 Hz at the center of the gap.

• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.5
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• pp.173-180
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• 2000

European side impact analysis of an electric vehicle was done using robust design. Locations and section properties of some of the vehicle structure components which influence the european side impact characteristics were chosen as the main factors for the robust design. Eight factors were considered for the analysis: one with two level and seven with three level combinations comprising the L18(21$\times$37) orthogonal array. It is shown that the sensitivities of the factors and the best combination of the factors can be obtained, and that the location of the main components were as much sensitive as the section properties of those. Also it is shown that the interactions were existed between some factors.