• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.951-956
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• 2008

The study is to develop a foundation design for a railway vehicle simulator using a scaled model. Although a scaled simulator is limited to manipulate the dynamics of a full-size railway vehicle, it has been known to have an advantage, since a scaled model could provide the fundamental dynamic behavior within a limited space of a laboratory facility and with a low operation cost while an experiment is conducted. This study is to propose a design strategy for a simulator so that a small scaled roller rig could be fabricated in a laboratory based on the design philosophy. The data obtained from the scale model is also experimentally investigated in conjunction with appropriate non-dimensional analysis so that the output results should be interpreted to the railway vehicle.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.12
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• pp.11-20
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• 2011

PSALI is referred to the supplementary lighting for the interior lighting under the daily lighting situation, and pursuant to the pertinent regulations in energy savings design standard and others in recent architecture works, the importance thereof has been increasing gradually coupled with the energy performance index (EPI), energy savings plan and the like as well as expansion of submittal and implementation policies. However, this type of PSALI studies indeed have a number of limitations since it has surrounding environmental conditions in direction, season, region, climate, time, opening rate, window area ratio, actual index, reflection rate of finishing materials and others in the architecture work as well as frequent changes in interior lighting environment for variables in daily light volume flowing into the interior, and others. Therefore, this study has analyzed existing advance research cases to produce the actual-sized model and scaled-down model, and installed the artificial lighting of LED light source possible to reproduce with same capability on both models. As a result of comparison and analysis of the artificial lighting with the key light, it has certain level of error rate from the scaled down lighting device in certain rate and actual model butit was noticeably significant within specific scope.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.25 no.5
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• pp.337-344
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• 2015

As many of armored vehicles are seriously exposed to threat of IEDs(Improvised Explosive Devices) in the Afghanistan war and the Iraq war. V-shaped military vehicles are deeply studied in order to protect crews and mounted soldiers against land mines. Generally the experiment on full-scaled V-shaped structure needs excessively high cost, which becomes a huge barrier to study. In this paper, we explore the possibility to make a half-scaled model of the V-shaped structure by using the geometric similarity scaling. We demonstrate the geometric similarity scaling between the original model and the half-scaled model is established on the momentum and deflections of structure via computer simulations and experiments. At this stage, we conduct only numerical analysis of predicting vibration of V-shaped structure because measuring vibration of structure is difficult in the mass-explosion experiment, which is remained as future work.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.11 no.2
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• pp.1-6
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• 2015

The horizontal earth-to-air heat exchanger (HEAHES) thermal performance is excellent on cooling and heating season in hot arid regions was reported. But the HEAHES thermal performance results is difficult to find on intermediate season. This paper was performed full scaled experiment to investigate HEAHES thermal performance on intermediate season (Oct. 10th ~ 12th Nov. 12th). When the air entering to HEAHES is the lowest $2.3^{\circ}C$, outlet air temperature from HEAHES is $15.95^{\circ}C$ through PVC pipe that buried length 60m and depth 3m. When the air entering to HEAHES is the highest $24.8^{\circ}C$, outlet air temperature from HEAHES is $22.05^{\circ}C$. During intermediate season, the HEAHES COP is 2.71 in daytime and 6.53 in evening.

• Nuclear Engineering and Technology
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• v.45 no.3
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• pp.347-360
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• 2013

This paper presents an experimental investigation of the small-break loss-of-coolant accident (SBLOCA) and the loss-of-feedwater accident (LOFW) in a scaled integral test facility of REX-10. REX-10 is a small integral-type PWR in which the coolant flow is driven by natural circulation, and the RCS is pressurized by the steam-gas pressurizer. The postulated accidents of REX-10 include the system depressurization initiated by the break of a nitrogen injection line connected to the steam-gas pressurizer and the complete loss of normal feedwater flow by the malfunction of control systems. The integral effect tests on SBLOCA and LOFW are conducted at the REX-10 Test Facility (RTF), a full-height full-pressure facility with reduced power by 1/50. The SBLOCA experiment is initiated by opening a flow passage out of the pressurizer vessel, and the LOFW experiment begins with the termination of the feedwater supply into the helical-coil steam generator. The experimental results reveal that the RTF can assure sufficient cooldown capability with the simulated PRHRS flow during these DBAs. In particular, the RTF exhibits faster pressurization during the LOFW test when employing the steam-gas pressurizer than the steam pressurizer. This experimental study can provide unique data to validate the thermal-hydraulic analysis code for REX-10.

• Transactions of The Korea Fluid Power Systems Society
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• v.7 no.2
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• pp.1-6
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• 2010

A new type fiber optic sensing system has been developed as a commercially available standard using the technique of hetero-core spliced fiber optic sensor, for the purposes of monitoring large scaled structures, preserving natural environments and measuring physical phenomenons. The sensing system has been tested and evaluated in a possible outdoor condition in view of the full scaled operation at actual sites to be monitored. Additionally, the developed system in this work conveniently provides us with various options of sensor modules intended to measure such physical quantities as displacement, distortion, pressure, binary states and liquid adhesion. The experiment study has been performed to examine the performance to a pseudo-cracking experiment in the outdoor situation, and to clarify temperature influences to the system in terms of the coupling of optical connectors and the OTDR stability. It has been verified that the sensing system is robust to the temperature change ranging from the general condition to the hard condition. Especially, in this study, the specification and performances of the pressure sensor have been demonstrated to show the capability of inspecting various physical quantities.

• Journal of the Korean Society for Railway
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• v.15 no.1
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• pp.9-16
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• 2012

The dynamic stability of railway vehicle has been one of the important issues in railway safety. The dynamic simulator has been used in the study about the dynamic stability of railway vehicle and wheel/rail interface optimization. Especially, a small scale simulator has been widely used in the fundamental study in the laboratory instead of full scale roller rig which is not cost effective and inconvenient to achieve diverse design parameters. But the technique for the design of the small scale simulator about the dynamic characteristics of the wheel-rail system and the bogie system has not been well developed in Korea. Therefore, the research using the small-scaled derailment simulator and the 1/5 scaled bogie has been conducted. In this paper, we did running stability test of 1/5 scaled bogie using small-scaled derailment simulator. Also, for the operation of the small scaled simulator, it is required to investigate the performance and characteristics of the simulator system. This could be achieved by a comparative study between an analysis and an experiment. This paper presented the analytical model which could be used for verifying the test results and understanding of the physical behavior of the dynamic system comprising the small- scaled derailment simulator and the 1/5 scaled bogie.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.2600-2608
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• 2011

The dynamic stability of railway vehicle has been one of the important issues in railway safety. The dynamic simulator has been used in the study about the dynamic stability of railway vehicle and wheel/rail interface. Especially, a small scale simulator has been widely used in the fundamental study in the laboratory instead of full scale roller rig which is not cost effective and inconvenient to achieve diverse design parameters. But the technique for the design of the small scale simulator for the fundamental study about the dynamic characteristics of the wheel-rail system and the bogie system has not been well developed in Korea. Therefore, the research about the development of the small scale simulator and the bogie has been conducted. As this paper, To predict the dynamic behavior of railway vehicle, we studied running stability test of 1/5 scaled bogie that similarity laws is applied using small scale derailment simulator. For the operation of the small scale derailment simulator, it is required to investigate the performance and characteristics of the system. This could be achieved by a comparative study between an analysis and an experiment. This paper presented the analytical model which could be used for verifying of the test results and understanding of the physical behavior of the dynamic system comprising the small scale bogie and the simulator.

• Tunnel and Underground Space
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• v.28 no.6
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• pp.692-705
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• 2018

Ground vibration is one of the remarkable issues in tunnel blasting. In recent studies, to improve the fragmentation with reduction of ground vibration in tunnel blasting, a vibration-controlled blasting method with artificial cutting slot near the center-cut holes has been suggested. This study examines the effect of the different arrangement of artificial cut-slot on the vibration reduction and fragmentation by performing the full-scaled concrete block blast experiments and the numerical simulations with 3D-DFPA. The results show that the existence of artificial slot contributes to the improvement of vibration reduction, blast fragmentation and the efficiency of the cutting slot blast. It can be explained that the artificial slot play a free surface role and should decrease the burden between the cut holes. Crater volumes of the blasted concrete blocks were measured by 3-dimensional digital image analysis and compared with the ideal standard crater volume which can be calculated by theoretical standard blast design method. As a result, the ratio of burden and hole diameter which should achieve the standard crater in the cut-hole blasting were suggested.

• Tunnel and Underground Space
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• v.16 no.1 s.60
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• pp.85-94
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• 2006

In this study, scaled model tests were carried out to decide the optimal critical velocity, to prevent back layering in the case of fire in a long traffic tunnel. Realistic estimates were made for the time required for people to escape ken the tunnel and far the time required by the ventilation operator to increase the system speed to full capacity. The analysis, predicts that the emergency ventilation will start about 240 seconds after the tunnel fire. It was also found that prevention of back layering would occur within 4 minutes after fan operation. To find out optimal critical velocity, a 1/50 scaled model tunnel(diameter : 0.2 m and length : 20 m) based on the Froude similarity technique was constructed. Changing $\beta$ values in the Tetzner's equation, smoke propagation was observed. From the experiment, it was concluded that using a $\beta$ value of 0.5 to prevent back layering successfully allowed time for safe evacuation.