• Journal of The Korean Society of Agricultural Engineers
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• v.46 no.1
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• pp.27-34
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• 2004

A model test is carried out to investigate flow-induced vibration of a Tainter gate in estuary sulices. The gate model scaled with the ratio of 1：25 is made of acryl panel dimensioned 0.66m in width, 0.5m in height in the concrete test flume. Firstly, natural frequencies of the model gate are measured and the results are compared with the numerical results in order to verify the model. The amplitudes of the vibration are measured under the different gate opening and water level conditions in flow from the gate outside to the gate inside. Also 5 revised gate models with bottom width increased 0.5 cm each are tested under the different gate opening and water level. The results are analyzed to study the characteristics of the gate vibration. These test results are assessed in comparison with formerly test results, as a result, presents a design method of Tainter gate to reduce the gate vibration and a basic data for the guide manuals of gate management.

• Korean Journal of Human Ecology
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• v.19 no.6
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• pp.1053-1062
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• 2010

To assist the further development of hight-visibility clothing this study compared the visibility and subjective wear sensation of commercial protective vests with retro-reflecting materials or LEDs. Nine subjects compared high-visibility vests to evaluate how easy they were to see when exposed to the headlight of a car at night, and the subjects assessed the wear sensation of the vests also. The intensity and visibility of five different colored LEDs assembled on the five substrates separately were also evaluated to select the suitable LED color for night protective clothing. The intensity of illumination was measured by an illuminometer, and the visibility was evaluated by 11 participants both in a dark room and in front of a car outdoors at night. Results showed, the most effective LEDs were high intensity LEDs which shift blinking red and white were most effective. However, excessively high intensity of illumination could decrease the working efficiency. In subjective wear evaluation, the most favorable vest had a front opening, were adjustable at the sides, and had an electric power switch on the front of the vest.

• Journal of Korean Society of Steel Construction
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• v.17 no.4 s.77
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• pp.499-509
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• 2005

The excessive wind-induced motion of tall buildings most frequently result from vortex-shedding-induced across-wind oscillations. This form of excitation is most pronounced for relatively flexible, lightweight, and lightly damped high-rise buildings with constant cross-sections. This paper discusses the aerodynamic means ofmitigating the across-wind vortex shedding induced in such situations. Openings are added in both the drag and lift directions in the buildings to provide pressure equalization. Theytend to reduce the effectiveness of across-wind forces by reducing their magnitudes and disrupting their spatial correlation. The effects of buildings with several geometries of openings on aerodynamic excitations and displacement responses have been studied for high-rise buildings with square cross-sections and an aspect ratio of 8:1 in a wind tunnel. High-frequency force balance testshave been carried out at the Kumoh National University of Technology using rigid models with 24 kinds of opening shapes. The measured model's aerodynamic excitations and displacement were compared withthose of a square cylinder with no openings to estimate the effectiveness of openings for wind-induced oscillations. From these results, theopening shape, size, and location of buildings to reduce wind-induced vortex shedding and responses were pointed out.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.37 no.4
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• pp.285-295
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• 2001

This study describes the analysis on the dynamic characteristics of model as a fundamental studies for the horn fish Hemiramphus sajor surface pair trawl gear. The model experiments were carried out in a flume tank by using model net for the horn fish surface par trawl gear. The model net was made to the scale of 1/40 by scaling down two surfce par trawl boats of 6.67 and 9.98 ton used for sea experiment in the coast of Jeju Island. Dimensions of the model net were 1.2m for stretch length of net, 1.3m for float line, 1.0m for sinker line, 2.5g for floats, and 0.86g for sinkers. Experiments were conducted in the observation channel of a flume tank with experimental equipments used to change the distance between paired boats and towing velocity. Motion of model net during towing was recorded by two sets of digital camera which were placed in the top and side of the model net. The leading coordinate of net height and net mouth width was captured by the photograph analysis system. Through the experiment, we obtained the following results: 1. The relationship between the net hight(Nh) and towing velocity(Vt) during towing was found to be Nh=(2.39Db-$^{0.62})Vt^{0.56}$ and the relationship between the net mouth width (Nw) and towing velocity during towing was Nw=(0.96Db^{0.62})Vt^{0.11}$, where Db is the distance between paired boats. 2. The relationship between the net tension(Nt) and towing velocity during towing was found to be Nt=106.94Vt+1.43 and the model net becomes parallel to the water surface at the towing velocity larger than 1.5 Knot. 3. The relationship between the net opening area(Na) and towing velocity during towing was found to be Na=(2.28Db0.37)Vt.-0.45, and the relationship between the filtering volume(Fv) and towing velocity during towing was Fv=(69.9Db$^{0.37})Vt^{0.55}$. The net opening area and filtering volume reach maximum value at the distance of 25m between paired boats.