• Journal of the Korean Society for Railway
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• v.18 no.6
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• pp.552-557
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• 2015

Ballast gravel in a railroad field is often polluted by grease and heavy metals. In this paper, the performances of a dry cleaning method for polluted ballast gravel in which pollutants on the gravel surface can be physically removed was extensively studied. A polluted ballast cleaning device able to shoot emery blasting media onto the surface using compressed air was prepared. Polluted ballast gravel was put into this device for cleaning, with the treatment time varied from 1 to 10 min. The cleaning efficiency of the total petroleum hydrocarbons and heavy metals were studied. The total petroleum hydrocarbon removal efficiency was 70-80% for gravels sampled from a locomotive waiting line, while it was 40-60% for gravels sampled from a turnout area. The heavy metal removal efficiency exceeded 90% for copper and lead, while it was 65-80% for nickel and zinc. This system was found to be effective for the remediation of polluted ballast gravels.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.537-540
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• 2010

An Enhanced Huels Type Plasma Torch that generates over $5000^{\circ}C$ plasma arc flow is the core equipment of arc-jet wind tunnel. It is applied to the high-tech areas such as a new materials development and eco-friendly industry. Although the Enhanced Huels Type Plasma Torch produce uniform flow of high purity, its complicated structure and operating condition makes the commercialization of it to be difficult. The 400kW arc-jet generator using the enhanced Huels type plasma torch was tested. The result of this study showed that the torch was operated in the range of 280~320 A and 250~1350 V.

• Journal of the Korean Institute of Gas
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• v.22 no.4
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• pp.74-81
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• 2018

The Korean Government has proceeded petroleum gas pipeline construction business since 2014 for rural districts. The operating pressure of petroleum gas pipeline are from 25kPa to 75kPa which are different from that of natural gas pipeline. Petroleum gas pipeline pressure is ten or forty times higher than natural gas operating pressure. For this reason, petroleum gas pipeline has higher probability of accident occurrence from massive gas leakage. Korea Gas Safety Corporation begins to development excess flow valves and their performance testing equipment since 2017. The excess flow valves stop the gas flow when a overflow happened in gas pipeline. The excess flow valves are generally not installed in main pipeline, because that may block massive gas supply. So, the valves are installed in starting points of branch pipes. According to the number of house and amount of gas use, a shut-off point of exxcess flow valve is determined called as Trip Flow. The trip point is the most important thing of excess flow valve, so, it is required a equipment testing the performances of excess flow valve as trip point.

• Journal of the Korean Society of Radiology
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• v.8 no.3
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• pp.105-110
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• 2014

Diagnostic radiation equipment diagnosis and treatment of disease of recent plays a central role, but this is based on the assumption of an appropriate balance of benefits and risks of diagnostic. If balance is not maintained has the potential to give an adverse effect on the health of the public. In the case of an overseas, the importance of (QA) quality assurance of medical equipment is growing, but evaluation criteria of quality assurance has not been clearly presented in domestic. Therefore, the modernization of medical equipment from the point at which the degree of cycle-by-cycle management system of foreign national to be suitable for diagnostic radiation generator entry and quality control standards by introducing a tailoring is necessary. In this study the most frequently used diagnostic radiation generator X-ray imaging apparatus of the general three-year periodic inspections at any time between the periodic inspection items and quality control methods and standards for the establishment of the United States, Canada and abroad, and international electronic literature search Technical Committee (International Electro-technical Commission, IEC) were compared with the provisions of item. Based on the national quality control items when opening frequent inspection items and standards presented as a basis for setting up study.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.1
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• pp.179-188
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• 1990

The characteristic of volumetric efficiency considering gas exchange process in a reciprocating engine is presented in this paper. The characteristic method is used for solving gas exchange problems of engine system in theoretical studies. The validity of the simulation is investigated by a comparison with the results obtained by the experiment which have been performed on the practical 4-cycle, 4-cylinder gasoline engine. The relationship between the volumetric efficiency and the intake pressure variation according to configuration of intake pipe, position of branch point, valve timing, compression ratio is clarified through simulation and experiment. The results predicted by the simulation are found to be in approximate agreement with those obtained by the experiment.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.27 no.6
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• pp.293-299
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• 2015

In Korea, it is the law that an apartment building which consists of over 100 households must have a ventilation system installed, either natural or mechanical. The heat recovery ventilator (HRV) is great way to reduce energy consumption. In this research we confirmed that based on site's construction plan and existing diffuser form, performed purpose CFD which simulates operation in temperatures below $-5^{\circ}C$ to circumstances of installation of an HRV in an apartment. As a result of this research we found that when the diffuser's aperture area was adjusted, the distribution of air temperature and residence time of air was more equally distributed and air temperature was higher, compared to when the diffuser has an identical aperture area. We also found that we are able to increase even more air temperature and air distribution of air temperature and residence time of air was even more equally distributed when run in parallel with a splitter damper.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.5
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• pp.391-399
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• 2011

The purpose of this paper is to predict the shock absorbing characteristics of the aluminum honeycomb in a lunar lander. Aluminum honeycomb has been used for shock absorbers of lunar lander due to its characteristics such as light weight, high energy absorption efficiency and applicability under severe space environments. Crush strength of the honeycomb should have strength to endure during shock energy absorbing process. In this paper, the crush strength, which depends on the shape of honeycomb and impact velocity, is estimated using FEM. Ls-dyna is used for finite element analysis of the honeycomb shock absorber. The unit cells of the honeycomb shape are modeled and used for the finite element analysis. Energy absorption characteristics are decided considering several conditions such as impact velocity, foil thickness and branch angle of the honeycomb.

• Journal of the Korean Institute of Gas
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• v.21 no.1
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• pp.80-86
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• 2017

In this paper, it is proposed to solve the problem of the harmful exhaust gas reduction device DPF. The exhaust gas is effectively guided through the control of the exhaust gas flow path which is separated in both directions. Through cross control of two DPF units, it helps to improve the purification and regeneration combustion characteristics of harmful emissions. It is possible to prevent an increase in internal pressure caused by deposition of particulate matter in the DPF. It is also an object of the present invention to provide an automobile harmful exhaust gas reduction device capable of solving the problem of lowering the output and lowering the fuel consumption.

• Fire Science and Engineering
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• v.29 no.1
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• pp.53-59
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• 2015

Water hammering created by an unsteady flow in pipeline systems can cause excessive change in pressure, vibration, and noise. So, water hammer analysis is very important for limiting the damage caused to pipeline, pump and valve systems by operation conditions. On the other hand, water hammer arrester has been manufactured and used in order to minimize the damage caused by water hammering phenomenon in domestic, and it has been produced and installed as the low cost-oriented because of being no separate standard in the meanwhile. Therefore, our research team investigated about the standardization of water hammer arrester performance through the various methods, such as test methods for verification of one pipe, assuming the occurrence of water hammer in a water-based fire extinguishing system, separated for opening impact pressure and shut off impact pressure and for a branch pipe in order to make guideline for water hammer arrester performance. And finally, verified the performance of the water hammer pressure as the simple mechanical way using the U-shaped pipe and a test weight, so KFI standards for the water hammer arrester could be established.

• Journal of the Korean Society of Propulsion Engineers
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• v.26 no.3
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• pp.54-65
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• 2022

We are developing a compact ignition device that can provide a multi-ignition capability for an upper stage methane engine of a two staged small satellite launch vehicle. Firstly, the multi-ignition device is designed and built as an integral part of an additively manufactured mixing head. Secondly, the ignition device requires no separate high-pressure vessels to store ignition propellants as they are branched out from the main feed lines for the mixing head. We performed experiments at various levels, including igniter autonomous tests, thrust chamber ignition and combustion tests on the new compact ignition device which is integrated in the thrust chamber of one-tonf class liquid oxygen/liquid methane engine, and confirmed stable ignition performance.