• Proceedings of the Korean Institute of Building Construction Conference
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• 2012.11a
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• pp.177-180
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• 2012

Korea residential housing generally use wet floor heating system 'Ondol' which consist of insulation cushioning, lightweight foamed concrete, hot water pipe and mortar on top of reinforced concrete slab. Wet floor heating system's installation process is too complicate and difficult to supervise field for continuing assurance quality. Also, this method has a huge impact on the progress of construction because it take a long time to cure finishing mortar and lightweight foamed concrete. Therefore, it is considered a disturbance factor of reduction of construction duration for enhancing competitiveness. In this study, we conducted an experiment about the radiant heat performance and temperature difference on upper panel of rolled dry floor heating systems which is jointly developed by Kolon global and Sumisho Metalex for remodeling housing, studio apartment and the urban-life housing.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1997.10a
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• pp.316-321
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• 1997

The purpose of this study is to reduce the vibration noise of differential gear by reducing torque fluctuation of drive pinion shaft which causes vibration noise of differential gear in rear wheel drive vehicles. For this we developed multi-degree of freedom analysis model in which mass moment of inertia and torsional spring combined, the validity of the simulation model was checked by the field test and we examined the influence of torsional vibration of driveline elements by performing forced vibration analysis of engine excitation torque. We studied the methods for reducing torsional vibration of driveline according to the design factor of propeller shaft and examined the effects reducing vibration differential gear by applying flexible coupling.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1998.04a
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• pp.27-33
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• 1998

The powertrain is a system of exciters which are connected by vibration transmitters and noise radiators. The powertrain has infinite natural frequencies. If the engine explosion, excites a certain natural frequency, then the powertrain system seriously vibrates. The torsional vibration arises from here. Torsional vibration like this can cause various noises as rattle and booming. In this study, the simulation models of multiple degrees of freedom were developed to reduce the torsional vibration of the powertrain. These models are combined mass moment of inertias with torsional springs. The free and forced vibration analyses were carried out by these models; and the validity of the simulation models were checked by the field test. The reduction effect of the torsional vibration along the driveline design factor is presented by the analytical results.

• 한국연소학회:학술대회논문집
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• 2002.06a
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• pp.46-51
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• 2002

The measurement of velocity and stain rate field has been conducted in opposed impinging jet combustion. When a smaller diameter (5mm) orifice of pre-chamber was used, previous studies had reported that the combustion phase showed a shift from weak turbulent combustion to moderate turbulent combustion in the modified Borghi Diagram. In the case with smaller orifice diameter (5mm), NOx emission was substantially reduced by a factor 1/2 while the combustion pressure remains at the same as that in the conventional combustion. Hence, in this study, the experiment setup using PIV technique was designed to identify the relation of the strain rate distribution and NOx reduction associated with moderate turbulent combustion.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.16 no.4
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• pp.13-21
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• 2007

This paper presents characteristics of steady flow by variation of a combustion chamber and an intake port. Gas flow field inside a combustion chamber is the important factor in improving combustion stability and reduction of emission level. The flow characteristics such as flow coefficient, tumble ratio and swirl ratio are measured by the steady flow rig test with an impulse meter in this study. In the measuring, the valve lifts are varied between 1mm to 10mm. The three combustion chambers and two intake ports were applied to the steady flow apparatus in order to investigate the effect of swirl and tumble on the in-cylinder flow. As a result, tumble ratio were found to be different by variation of the combustion chambers and the intake ports. The data from the present study can be applied to design of a similar engine as basic data.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2012.05a
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• pp.197-200
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• 2012

Concrete has cracks from shrinkage that necessarily result from in hardening process. Shrinkage-reduced concrete developed for crack reduction was utilized at a sample construction project. As a result, it is confirmed that crack initation ratio was remarkably reduced when compared to the case of normal concrete utilization. Additional sample project is supposed to use delay joints as well as srinkage-reduced concrete. Subsequently, the result will be reported. The greatest factor which affects in drying shrinkage is unit quantity of water. However, there are a lot off difficulties in field supervision because proper measuring means is not presented in present standard. Therfore, problems depending on ready-mixed concrete concrete companies should be improved by preparing the related standard assoon as possible.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1996.03b
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• pp.23-30
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• 1996

The purpose of this study was to investigate changes in thewall thickness of tube sinking and working forces by the upper bound method and ABAQUS code. The independent variables were : Workpiece material, original wall thickness of tube, die angle, friction, and diameter reduction. The results indicated that of these five variables were a factor in wall-thickness increase and working forces. Three variables, a inner tube wall angle and two angles of the velocity discontinuous surfaces, are optimized in this proposed velocity field by the upper bound method. In this method, we can estimate the working forces and final tube thicknesses whcih are similar to acturla forming process. Optimized process variables which are obtained by upper bound method are used in ABAQUS pre-model . In ABAQUS analysis, the stress and the strain contours which are considered to be heat generation occured by the friction during forming process are observed.

• Journal of KSNVE
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• v.7 no.5
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• pp.853-860
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• 1997

For this study, the multi-degree of freedom analysis model of torsional vibration was developed. This model is combined with mass moment of inertia and torsional spring in two wheel drive and four wheel drive vehicle. We compared and analyzed torsional vibration characteristics by natural frequencies and mode shapes which are obtained by free vibration analysis of this model. And we studied torsional vibration contribution of driveline elements by performing the forced vibration analysis of engine excitation torque. The validity of this model is demonstrated by the field test. The reduction effect of the torsional vibration along the driveline design factor is presented by the analytical results.

• Journal of the Korean Society for Railway
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• v.7 no.3
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• pp.223-231
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• 2004

The accumulated BMS data have made it easy to make reasonable decision-making for bride maintenance and repair work. In the developing period of BMS, the bridge management was not easy due to the lack of understanding of BMS and low credibility of the data. In recent years, it has been possible to enhance the credibility of the data and to expand the application scopes of BMS with the efforts of Local Road Construction Offices. The reasonable decision making for bridge management can improve the performance of bridges under the practical constraints such as limited budget. It can then result in the reduction of bridge maintenance budget. This study provides the methodology for the application of mobile internet-based KOBMS for bridge management. The data flow for BMS is the most important factor for decision-making on budget allocation, and this study establishes the basic scheme of the data flow for BMS. The implementation of PDA for BMS may suggest a new paradigm of 'Mobile' in the field of construction management.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.7
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• pp.644-650
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• 2010

Among various elements to affect customer's evaluation of vehicle quality, BSR(Buzz, Squeak, Rattle) are considered to be a mostly contributing factor. In this paper, we provide the test method which can be used to reduce the BSR noise of instrument panel in a vehicle. First, potential source regions of the instrument panel for BSR are localized by using the vibration-excitor and near-acoustic field visualization system. Then, subjective evaluation of BSR noise from the detected potential noise source regions is made with the Zwicker's loudness and time-varying loudness methods. This illustrative analysis reveals that current experimental methods can be used as a test procedure to systematically tackle BSR issues in early stage of the vehicle development cycle, which can result in the reduction of the production cost.