• Tunnel and Underground Space
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• v.5 no.1
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• pp.48-56
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• 1995

Recently, most of the underground excavation works are adopting heavy duty mobile diesel equipments which have outstanding merits in view of efficiency. However, these equipments are causing hygienic problems to the workers due to the various hazardous exhaust contaminants. Considering that there are always dead end workings in underground excavation sites, it is very important how to supply enough airflow to the workings to dilute diesel exhaust contaminants. This paper introduced the theoritical mechanism and actual trends of exhaust contaminants of diesel equipments under operation at local mines and suggested the design method of intake air volume in underground excavation workings using diesel equipments.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.10a
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• pp.602-606
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• 2011

In this study, operational vibration experiment and analysis have been conducted for the 4-blade small vertical-axis wind turbine (VAWT) including the effect of tower elastic behavior. Computational structural dynamics analysis method is applied to obtain Campbell diagram for the VAWT with elastic tower. An open type wind-tunnel is used to change and keep the wind velocity during the ground test. Equivalent reduced elastic tower is supported to the VAWT so that the elastic stiffness effect of the tower can be reflected to the present vibration experiment. Various excitation sources with aerodynamic forces are considered and the dominant operating vibration phenomena are physically investigated in detail.

• Wind and Structures
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• v.3 no.4
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• pp.255-266
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• 2000

Wind-induced interference effects on a building are the result of one or more adjacent buildings modifying the flow of wind around it, which may result in a significant increase or decrease in wind loads on the building. Wind loading standards and codes of practice offer little guidance to the designer for assessing the effects of interference. Experimental results on interference effects indicate that code recommendations may be significantly low (unsafe) or uneconomically conservative. The paper presents results of an extensive experimental program to study the wind flow mechanisms and to quantify the extent of wind load modifications on buildings due to interference effects. These results have been simplified and presented from the point-of-view of design and codification for the case of two buildings. Based on these results, general guidelines and limiting conditions defining wind interference are formulated and discussed.

• Proceedings of the Korean Geotechical Society Conference
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• 2002.03a
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• pp.205-212
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• 2002

Carbonate rocks such as limestone are susceptible to solution and show numerous solution cavities. For the construction of the structures such as bridge foundations and tunnel on the limestone cavities, the geological unconformities developed in the bed rocks, cavity systems and the filling types of solution deposits should be surveyed and analyzed. And also, the stability of structures on the limestone cavities must be taken into consideration in the view of the geotechnical engineering. As a result of analysis of the foundation settlement, an economic and effective reinforcement method is to be proposed and the construction by the proposed method is to be accompanied with verification of reinforcement effect. This paper is a case study of design and construction for the reinforcement of bridge foundations on the limestone cavity covered with thick bedded colluvial soils.

• Proceedings of the Korean Geotechical Society Conference
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• 2002.03a
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• pp.711-716
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• 2002

When judging the ground by core-logging, depth of coring might be stopped by coming into view of the moderately weathered rock and also considered as bedrock line. However, highly weathered rock may appear again, if coring more, because there are core-stones in the residual soil and highly weathered rock by the effect of hydraulic-thermal differentiation and does the irregular rock weathering or metamorphic rock region. Therefore, there are room for misunderstanding of diagnosing the moderately weathered rock. Even though the irregular ground where the corestones were come out will show clear geotechnical differences between the ground and the gradually weathered bedrock, nowadays, the construction sites do not take into account the characteristic of core-stone region. In conclusion, to study the failure-strength characteristics of soil layers containing core-stones, we made artificial core-stones and varied percentage of corestones, and measured cohesion and friction factors to adjust them to construction sites containing corestones such as slope, tunnel, and underground.

• Journal of The Korean Digital Architecture Interior Association
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• v.12 no.2
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• pp.33-38
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• 2012

The purpose of luminance measurement in lighting design of urban scale is to prevent light trespass and light pollution, caused by over-bright. Specially, the illumination of road, tunnel and sports complex as urban infrastructure is measured by international standard for illuminance and luminance. It has been used the spot luminance meter and the image photometer to define the characteristics of qualitative and quantitative in exterior lighting. This study introduced the concept of HDR Image, procedure of HDR Image creation and analysis. Applications of HDR Image, particularly within the apartment building exterior lighting design analysis, have been demonstrated. The procedure proposed in this study is a affordable method that is useful for the assessment of luminance distribution in the scene with electric light. It also provides a measurement capability with the high resolution luminance data within a large field of view efficiently and quickly, which is not possible to achieve with a luminance meter.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.6 s.123
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• pp.498-506
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• 2007

Using wind tunnel, experimental approaches were employed to investigate fluidelastic instability of tube bundles, subjected to uniform cross flow. There are several flow-induced vibration excitation mechanisms, such as fluidelastic instability, periodic wake shedding resonance, turbulence-induced excitation and acoustic resonance, which could cause excessive vibration in shell-and tube heat exchanges. Fluidelastic is the most important vibration excitation mechanism for heat exchanger tube bundles subjected to cross flow. The system comprised of cantilevered flexible cylinder(s) and rigid cylinders of normal square array, In order to see the characteristics of flow in tube bundles, particle image velocimetry was used. From a practical design point of view, Fluidelastic instability may be expressed simply in terms of dimensionless flow velocity and dimensionless mass-damping. The threshold flow velocity for dynamic instability of cylinder rows is evaluated and the data for design guideline is proposed for the tube bundles of normal square array.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.10a
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• pp.416-421
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• 2021

In case of the road slips due to heavy snow and the temperature drops below 0 degrees, black ice which mainly occurs on the road, bridges for vehicles, and tunnel entrances, is not recognized by the driver's view because the image of the asphalt is transmitted through it. So cars' slip situation occurs, which leads to a big traffic accident and a large amount of loss of life and property. This study proposes a method to check the road condition using an infrared camera and to identify black ice through deep learning.

• Journal of Korean Society of Steel Construction
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• v.9 no.2 s.31
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• pp.259-267
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• 1997

Wind tunnel test results and their interpretations focused on the behavior of girder, which were performed to study the aerodynamic stability of a self-anchored suspension bridge with lateral sag of main cable, are presented in this paper The shape of the girder which has the best aerodynamic stability was selected based on the section model test under uniform and turbulent flow conditions. Good performance of the selected section was confirmed in the full bridge model test. Measured flutter derivatives are presented for further study. Buffeting response was investigated to check the fatigue problem and serviceability of the bridge but it was found to be acceptable from the engineering point of view. Even though the drag coefficient of the girder had high value, the amplitude of the lateral vibration was found to be very low. This may be due to the restraint provided by the lateral sag of the cables.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.705-708
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• 2008

To obtain tunnel concrete safety in case of fire, this study analyzed fire proof characteristics by fire proof method change, and the results are as follows. As a fire proof characteristics by RABT temperature heating curve, plain concrete experienced severe spalling by initial extremely high temperature. In view of fire proof method, in the cases of organic fiber mixing method and board method, spalling was prevented, and in the case of spray method, severe spalling of over 100mm depth occurred along with exposure of structural concrete including spray coat by heat stress, etc while metal lath, the stiffener, falls off. As for fire proof characteristics by RWS temperature heating curve, in case of organic fiber inclusion, concrete surface experienced fusion of within 5mm, while in the case of spray method, spray coat was severely spalled to a depth of over 100mm causing structural body concrete to expose its reinforcement, and also in the case of board method, board was fused by high temperature, causing structural body concrete be directly exposed to high temperature, which triggered overall fall-off phenomenon, so in such extraordinary high temperature heating condition, establishment of special fire proof measures is needed.