• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.9 no.5
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• pp.59-66
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• 2010

Korea have experienced a very rapid increase in police-reported collisions between bicycle and motor vehicles over the past decade. Even though cycling accidents are increasing, efforts to make urban areas more accomodating to cyclists are seldom formed. Clearance intervals(including both the yellow change and all-red clearance intervals) at signalized intersections that are of inadequate lengths for bicycles may cause accidents. Data on bicycling speed, acceleration and deceleration were tested and analyzed on the flat. Using the results of the analysis and based on the AASHTO's equation of the bicycle clearance interval, a methodology is got for calculation safe clearance intervals for bicycle riders. The clearance interval call for bicycles will be larger or same than for vehicles because of the speed, acceleration and deceleration difference. Adequate bicycle speed, acceleration and deceleration for korean bicycle users is presented in this paper. It is hoped that traffic engineers to provide safe intersection clearance time for bicycles use the results of this paper.

• Wind and Structures
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• v.30 no.2
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• pp.181-198
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• 2020

In the traditional buffeting response analysis method, the spanwise incomplete correlation of buffeting forces is always assumed to be same as that of the incident wind turbulence and the action of the signature turbulence is ignored. In this paper, three typical bridge decks usually adopted in the real bridge engineering, a single flat box deck, a central slotted box deck and a two-separated paralleled box deck, were employed as the investigated objects. The wind induced pressure on these bridge decks were measured via a series of wind tunnel pressure tests of the sectional models. The influences of the wind speed in the tests, the angle of attack, the turbulence intensity and the characteristic distance were taken into account and discussed. The spanwise root coherence of buffeting forces was also compared with that of the incidence turbulence. The signature turbulence effect on the spanwise root coherence function was decomposed and explained by a new empirical method with a double-variable model. Finally, the formula of a sum of rational fractions that accounted for the signature turbulence effect was proposed in order to fit the results of the spanwise root coherence function. The results show that, the spanwise root coherence of the drag force agrees with that of incidence turbulence in some range of the reduced frequency but disagree in the mostly reduced frequency. The spanwise root coherence of the lift force and the torsional moment is much larger than that of the incidence turbulence. The influences of the wind speed and the angle of attack are slight, and they can be ignored in the wind tunnel test. The spanwise coherence function often involves several narrow peaks due to the signature turbulence effect in the high reduced frequency zone. The spanwise coherence function is related to the spanwise separation distance and the spanwise integral length scales, and the signature turbulence effect is related to the deck-width-related reduced frequency.

• Journal of Biosystems Engineering
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• v.12 no.4
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• pp.31-43
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• 1987

This study was performed to develop a hot water boiler system with small scale automatic rice hull furnace for the multi-purpose use in the farm. For the experiment a prototype hot water boiler system with rice hull furnace was fabricated, which was equipped with automatic hull feeder, igniter and ash removal device. Optimum operational conditions of the prototype: system were analyzed. The results arc summarized as follows. 1. The temperature measured right above the burning surface should be higher than $500^{\circ}C$ combustion. 2. The top zone of the combustion chamber was the most suitable location of the thermocouple to pick up the control temperature for the automatic operation of the rice hull furnace. 3. The content of carbon monoxide in the flue gas was increased with the filling height of burning material but it was less than 0.3 percent in volume in this experiment. When the filling height was expressed as the ratio of rice hull feed rate to the volume of the combustion chamber above the burning surface, the optimum ratio was about $150kg/m^3-h$. 4. The combustion efficiency of the prototype was higher than 95 percent when the feed rate was 1.1 to 2.3 kg/h and moisture content of rice hull was 22.4 percent (w.b.) or less. 5. It was estimated that the optimum operational conditions of the system were 1.3 to 2.0 kg/h in feed rate, 70 to 100 percent in excess air and 500 to $510^{\circ}C$ in control temperature. 6. The efficiency of coil heal exchanger increased with a decrease in feed rate of rice hull. When the rice hull feed rates were 1.1, 1.7 and 2.3 kg/h, the efficiencies of coil heat exchanger were about 34, 30 and 25 percent and heat transfer rates were 5.7, 7.6 and 8.8 MJ/h, respectively. When the flat plate heat exchanger was used in addition to the coil heat exchanger, the efficiency of the heat exchanger system increased to 48 percent.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.8 no.3
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• pp.169-175
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• 2014

In this study, it is intended to provide a slip detector is an important function in the research on the slip control can be addressed uncontrollably path withdrawal might during driving of the power wheelchair, slip phenomenon occurs. By detecting and electric wheelchairs, the state of the motor during running, the detection of the slip, slip detection information calculated using an encoder that is connected to the left and right motor with six-axis IMU sensor for the electric wheelchair using an algorithm to calculate the slip ratio. Slip rate calculated in this way is used as control variable for improving the safety of the electric wheelchair. It was confirmed from the slip phenomenon of the path the proposed experiments slim detector proposed in this study. The maximum slip ratio detection zone during the experiment, can occur during turning of the electric wheelchair has been confirmed.

• Transactions of Materials Processing
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• v.27 no.1
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• pp.37-47
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• 2018

In this paper, a double spot welding process, utilizing electric resistance heating dies, is suggested for the spot welding of dissimilar metal plates for drawing and concurrent spot welding. This double welding process has two heating methods for the fusion welding at the interfacial zone between steel and aluminum plates, such as heating method by thermal conduction of electric resistance by welding current induced to heating dies, and heating method by electric resistance between contacted surfaces of two plates by welding current induced to copper electrode. This double welding process has welding variables such as each current induced in heating dies and in copper electrode, outer diameters of heating dies, and edge shape of copper electrode. Experiments for current conditions in welding process should be demanded in order to get successful welding strength. It was known that the welding strength could be reached to the value demanded on industry fields under such welding conditions as heating dies of outer ring dia.12mm contacted on steel plate, as heating dies of outer ring dia. 14mm contacted on aluminum plate, and as copper electrode of dia. 6.0mm, and as 3 times continuous heating method by $1^{st}$ current of 11 kA(9cycle), $2^{nd}$ current 11 kA(60cycle), $3^{rd}$ current 7 kA(60cycle) applied in steel heating dies and copper electrodes, flat edge of copper electrode, for double spot welding process of dissimilar metal plates of steel and aluminum of 1.0 mm thickness.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.16 no.2
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• pp.75-81
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• 1983

The studies on the age determination of the spottybelly greenling, Agrammus agrammus, caught in the shore of Tongbaeksom were done by the articulative fossae of the vertebra through a stero-dissecting microscope. For determining annunli the vertebra had been cleaved lengthwise in the dorsoventral direction. Half of the vertebra had been fixed on Canada balsam with the flat side directed upwards. The alternation of two zones on the vertebra was observed. One is wide and light-colored, and the other is narrow and dark-colored. The annual layer, where the dark-colored zone shifts to the light-colored one, was appeared extending from July to August once a year. Study of the growth of A. agrammus was carried out by the method of back calculation from the vertebra.

• Journal of Environmental Impact Assessment
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• v.19 no.2
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• pp.127-140
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• 2010

This study investigates the relation between the location of a habitat and the ecological connections according to the habitat type in the riparian zone at the Nonsan Stream and Yanghwa Stream. Stream habitat is classified into nine types for the aquatic insects and fish. For vegetation and birds, habitat is classified into two types of medium-scale streams, including both physical and chemical streams are analyzed accordingly. Nowadays, The fundamental goal of the river environment restoration enterprise is the rehabilitation or the restoration of the characteristic the river scenic or environment. For instance, The Channel habitats which has physical nature environment such as flat, speedy rapids, or closed-channel wetland, pool are constructed by artificial, Consequently, make them autogenesis smoothy eco-environment. However, the river environment are controlled not only physical environment, but it also need reasonable the quality of the water to compose smoothly. Finally, understanding what influence are effecting on physical habitat environment which are made by natural factors to water quality are very important factor for the river environment restoration enterprise Therefore, In this research, we are targeting to a basin to investigate the environment of the physical channel habitat and evaluate the changing of the water quality. This results will be a important characteristic that can judge the physical habitat and reciprocality connected to the water quality or adequacy of restoration technology. Therefore in this study, as a step to quantify functions and values of habitats and definite factors to perform habitat, we selected a representative stream of sand-stream, gravel-stream to classify habitat characteristics and quantified the physical, chemical, biological characteristics.

• Journal of the Korean Society for Marine Environment & Energy
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• v.6 no.2
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• pp.16-27
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• 2003

For the last decade, some 400 small and large oil spill accidents have occurred every year. Such accident blow a serious damage to the marine resource and ecosystem, which can't be estimated in terms of economic and environmental losses. The physical/chemical methods used currently may be effective at the initial stage of accidents, but they can't serve to remove the spilled oil completely. Moreover, the dispersant may lead to a secondary contamination detrimental to the lives inhabiting wet lands, beaches and tidal zone. Thus, a new decomposing technology Is required for the environmentally sensitive areas. Bioremediation is the active use of biological techniques to mitigate the consequences of a spill using biological processes and refers both of stimulation of pollutant biodegradation and/or to enhance ecosystem recovery Bioremediation is an economically attractive method for the clean-up of oil-contaminated area. Bioremediation has been demonstrated to be an effective oil spill countermeasure for use in cobble, sand beach, salt marsh, and mud flat environment.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.53-53
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• 2015

Basin-scale motions in a stratified lake rely on interactions of spatially and temporally varying wind force, bathymetry, density variation, and earth's rotation. These motions provide a major driving force for vertical and horizontal mixing of inorganic and organic materials, dissolved oxygen, storm water and floating debris in stratified lakes. In Lake Tahoe, located between California and Nevada, USA, basin-scale circulations are obviously important because they are directly associated with the fate of the suspended particulate materials that degrade the clarity of the lake. A three-dimensional hydrodynamic model, ELCOM, was applied to Lake Tahoe to investigate the underlying mechanisms that determine the characteristics of basin-scale circulations. Numerical experiments were designed to examine the relative effects of various mechanisms responsible for the horizontal circulations for two different seasons, summer and winter. The unique double gyre, a cyclonic northern gyre and an anti-cyclonic southern gyre, occurred during the winter cooling season when wind stress curl, stratification, and Coriolis effect were all incorporated. The horizontal structure of the upwelling and downwelling formed due to basin-scale internal waves found to be closely related to the rotating direction of each gyre. In the summer, the spatially varying wind field and the Coriolis effect caused a dominant anti-cyclonic gyre to develop in the center of the lake. In the winter, a significant wind event excited internal waves, and a persistent (2 week long) cyclonic gyre formed near the upwelling zone. Mechanism of the persistent cyclonic gyre is explained as a geostrophic circulation ensued by balancing of the baroclinc pressure gradient (or baroclinic instability) and Coriolis effect. Topographic effect, examined by simulating a flat bathymetry with constant depth of 300m, was found to be significant during the winter cooling season but not as significant as the wind curl and baroclinic effects.

• Advances in Computational Design
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• v.7 no.3
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• pp.229-251
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• 2022

In 2017, an intraplate earthquake of Mw 7.1 occurred 120 km from Mexico City (CDMX). Most collapsed structural buildings stroked by the earthquake were flat slab systems joined to reinforced concrete (RC) columns, unreinforced masonry, confined masonry, and dual systems. This article presents the simulated response of an actual six-story RC frame building with masonry infill walls that did not collapse during the 2017 earthquake. It has a structural system similar to that of many of the collapsed buildings and is located in a high seismic amplification zone. Five 3D numerical models were used in the study to model the seismic response of the building. The building dynamic properties were identified using an ambient vibration test (AVT), enabling validation of the building's finite element models. Several assumptions were made to calibrate the numerical model to the properties identified from the AVT, such as the presence of adjacent buildings, variations in masonry properties, soil-foundation-structure interaction, and the contribution of non-structural elements. The results showed that the infill masonry wall would act as a compression strut and crack along the transverse direction because the shear stresses in the original model (0.85 MPa) exceeded the shear strength (0.38 MPa). In compression, the strut presents lower stresses (3.42 MPa) well below its capacity (6.8 MPa). Although the non-structural elements were not considered to be part of the lateral resistant system, the results showed that these elements could contribute by resisting part of the base shear force, reaching a force of 82 kN.