• Journal of the Korean Institute of Gas
• /
• v.17 no.1
• /
• pp.73-80
• /
• 2013

This study presents sealing behavior and endurance safety of V-grooved o-rings as functions of a strain, compression stress, and contact normal stress using a FEM technique. The FEM results on the sealing behavior and endurance safety show that the maximum strain, maximum compression stress, and maximum contact normal stress of V-grooved o-rings are approximately 1.2 times higher than those of conventional solid o-rings. This is why that an o-ring has a V-groove in the center between two overlapped circles, which is very effective in sealing for ball valves, pressure vessels, and gas equipment. And the extrusion failure in V-grooved o-rings does not take place under an increased gas pressure due to a V-groove. This may extend sealing life compared with that of a conventional solid o-ring.

• Journal of Advanced Marine Engineering and Technology
• /
• v.35 no.4
• /
• pp.379-387
• /
• 2011

Research and development of LP EGR system for the performance improvement and emission reduction on diesel engine is proceeding at a good pace. LP EGR system seems to be helpful method to further reduce$NO_x$ emissions while maintaining PM emissions at a low level because the boost pressure is unchanged while varying EGR rate. This study is experimentally conducted on a 2.0L common rail DI engine at the medium load condition (2000 rpm, BMEP 1.0 MPa, boost pressure 181.3 kPa) that difficult to use large amount of EGR gas because of deteriorations of performance and fuel consumption. And we investigated the characteristics of performance and fuel consumption while varying EGR systems. The overall results using LP EGR system equipped with ETC identified benefits on reduction of PM and improvement of fuel consumption and thermal efficiency while keep the $NO_x$ level compared to HP EGR and LP EGR with back pressure valve.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.14 no.6
• /
• pp.53-59
• /
• 2010

This research aims in finding a more optimal ejector size for evacuating engine exhaust gasses and 20% of the cell cooling air. The remaining 80% of cell cooling air pumped into the test chamber is separately exhausted from the test chamber via a discharge port fitted with flow control valves and vacuum pump. Unlike its predecessor this configuration utilizes a smaller capture area to improve pressure recovery. The modified ejector size has a diameter of 1100mm enough to evacuate 66kg/s jet engine exhaust in addition to about 20%, 24kg/s of the cell cooling air tapped from the sterling chamber. This configurations has an area ratio of the engine exit and ejector inlet of about 1.2. Simulation results of the proposed ejector configuration, indicates improved pressure recovery.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.12 no.1
• /
• pp.147-154
• /
• 2017

This paper aims to build a home security system based on IoT to monitor a home on a mobile phone. The system consists of data gathering sensors, camera, gateway and Xively platform. The Raspberry Pi collects data from the three sensors and sends the data to Xively, and sends the video stream of home to a client in a smart phone through a internet. The servers are composed of Xively, socket server in Raspberry Pi and E-mail server in Google. The proposed system transmits e-mail, text message, and video stream when there are motion, fire, and gas leakage, and can control the gas valve through Raspberry Pi. The experimental results show that a user gets 'emergency E-mail' and text message and watches the video stream of the home through WIFI or LTE on a smart phone.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.11 no.5
• /
• pp.60-71
• /
• 2007

The startup characteristic of liquid propellant rocket engine should be focused on the stable ignition of combustion chamber and gas generator. Also, to lessen the propellants consumption during this period which doesn't contribute to the flight thrust, the engine has to be transferred to the nominal mode quickly. Because of the risk of test, it is impossible to develop all the startup cyclogram or the specifications of engine by test, so the precedent numerical approach is quite necessary. In this study we developed a mathematical model for the startup phenomena in a liquid rocket engine driven by gas generator-turbopump system based on the commercial 1-D flow system analysis program, Flowmaster. Using this program we proposed a methodology to obtain the specifications of turbine starter and the opening time of shutoff valves for the stable startup of the engine. To verify this methodology we qualitatively compared the analysis results to the typical startup curve of the published engine, then found it is quite well matched.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.46 no.9
• /
• pp.774-781
• /
• 2018

In this investigation, a gas gun is proposed driven by carbon dioxide gas and installed on a quadcopter-type small unmanned drone for the purpose of cattle vaccination, and we developed a launcher and its connection unit. The system consists of a commercial drone, a gas gun, a solenoid valve, and the remote communication controller, etc. The velocity of launched projectile is measured, and the full system is finally validated through ground test and flight examination loaded for the real aircraft. The feasibility is checked if this technology is applicable to various disease abatement and hazard mitigation in the fields of agriculture and fire-fighting with the present research and development.

• Journal of the Korean Institute of Gas
• /
• v.14 no.1
• /
• pp.47-54
• /
• 2010

In order to reduce the number of installation processes and the cost, a unified ball valve and polyethylene-steel pipe is proposed and tested. An integrated design approach is carried out such that a virtual manufacturing based on finite-element analysis is first performed in order to examine contact conditions under exaggerated temperature variations (${\Delta}T\;=\;60^{\circ}C$ and $-50^{\circ}C$ for summer and winter, respectively). From the final design configuration, it was predicted that the maximum contact pressures are 71 and 8.1 MPa for summer and winter, respectively, at relatively larger contact surface. Based on this observation, a prototype model is fabricated to go through an actual leakage test. The prototype pipe passed a hydrostatic strength test successfully, showing no leakage at even much higher (54 MPa) than the operational pressure (0.25 MPa).

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.37 no.11
• /
• pp.1349-1354
• /
• 2013

Sealing structure to prevent flowing hot gas into the driving device, located between the driving shaft and the liner of On-Off valve for controlling the hot gas flow path was studied. Wear occurs due to the constant movement of the driving shaft controlled by actuator on graphite as the sealing material. In this paper, the dynamic wear behavior in high temperature of graphite(HK-6) to be used as sealing material was evaluated. Reciprocating wear test was carried out for the graphite(HK-6) to the relative motion between shaft materials(W-25Re). The results of friction coefficient and specific wear rate according to contact load, sliding speed at room temperature and $485^{\circ}C$ considering the actual operating environment were evaluated. Through the SEM analysis of the worn surface, third body as lubricant films were observed and lubricant effect of third body was considered.

• Applied Chemistry for Engineering
• /
• v.20 no.4
• /
• pp.391-395
• /
• 2009

For the conversion of domestic waste-wood into energy, a fixed bed gasifier ($0.9 m{\times}2.4 m$) having the capacity of 2 ton/day was designed and constructed. The dual knife valve was used to feed waste-wood of which size was 3~5 cm and a rotary stoker system was installed in the bottom of gasifier. The pilot gasification system consisted of feeding system, fixed bed gasifier, gravity fine particle collector, heat exchanger for syngas cooling, ID fan, and cooling tower. The operation temperatures of gasifier were $700{\sim}1000^{\circ}C$ and the concentrations of syngas were CO: 25~40 vol%, $H_2$: 7~12 vol%, $CH_4$: 2~4 vol%, $CO_2$: 12~24 vol%. The calorific value of syngas was $1100{\sim}1500kcal/Nm^3$ and was enough to be applied in the industrial combustor. Also the gas engine was operated by using syngas from biomass gasifier and produced 1~4 kW of power.

• Journal of the Korean Institute of Gas
• /
• v.21 no.5
• /
• pp.16-26
• /
• 2017

In chemical industry plants, the raw material, intermediate and final products can leak from unstable joints of flanges and valves as well as cracks of storage tanks. From the safety and economic standpoints, it is very important to understand whether leaks or not and leakage rate. The OGI(optical gas image) technique can tell gas leakages, but cannot give the leakage rate. Some special OGI devices can show the kind of gas in different color concentration in different darkness. Therefore the research on quantification of OGI is necessary. In this research, we have developed the practical method to quantify OGI of methane leakage. To estimate 3-dimensional gas leakages distribution from 2-dimensional OGI, the Monte Carlo Probability technique was applied. First the number of points in the area of width(2.54 cm) and length(2.54 cm) in OGI was counted. Total no of each experiment was compared with the measured flow rate. The correlation average between total points and measured flow rate was found to be 0.980. Reversely we estimated the leakage rate of OGI by use of the correlation table. The results showed good agreement between the estimation value and the measured value.