• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2003.10a
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• pp.320-323
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• 2003

This paper presents the results of a series of performance tests for the Stilting cryocooler. A free piston and free displacer(FPFD) Stilting cryocooler for cooling infrared and cryo-sensors is currently under development at KIMM. Our coolers are specifically designed to work in the thermal imaging device and to meet requirements such as cooling capacity, COP and high reliability. In this work, Stilting cryocooler is designed, manufactured and fabricated, and performance characteristics for the cooling capacity / applied input power and cool down time are investigated. This cooler delivers approximately 0.9W cooling at 80K for 30W ~ 40W of input power. And, It takes approximately 2 minutes to cool down to 80K at the ambient temperature of 23$^{\circ}C$.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2003.10a
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• pp.167-170
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• 2003

This paper presents the results of a series of performance tests for the Stilting cryocooler. A free piston and free displacer(FPFD) Stilting cryocooler for cooling infrared and cryo-sensors is currently under development at KIMM. Our coolers are specifically designed to work in the thermal imaging device and to meet requirements such as cooling capacity, COP and high reliability. In this work, Stilting cryocooler is designed, manufactured and fabricated, and performance characteristics for the vibration, acoustic noise, EMI and leak rate are evaluated. Vibration outputs are measured to 20KHz for compressor and expander, respectively. And, the objective of noise test is a noise level, less than 30㏈ at 5 m. EMI tests are carried out according to the standard MIL-STD-461C tests RE01 and RE02. Leak test for the Stilting cryocooler is performed by bombing method.

• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.610-612
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• 2008

Piston cores retrieved from the eastern part of the deep-water Ulleung Basin were analyzed to access the potential of hydrocarbon gas generation and natural gas hydrate (NGH) formation. Seismic data acquired in the study area were also analyzed to determine the presence of hydrocarbon gas and/or NGH, and to map their distribution. Core analyses revealed high total organic carbon (TOC) contents which favor hydrocarbon generation. The cores recovered from the southern study area showed the sufficient residual hydrocarbon gas concentrations for the formation of significant NGH. These cores also showed the cracks developed parallel to the bedding that suggest significant gas content in situ. A number of seismic blanking zones were observed on seismic data. They are identified as vertical to sub-vertical chimneys caused by the upward migration of pore fluid or gas, and containing of free gas and/or NGH. Often, they are associated with velocity pull-up structures that are interpreted to be the result of high-velocity NGH. The seismic data also showed several bottom-simulating reflectors (BSRs) that are associated with overlying NGH and underlying free gas. The distribution of blanking zones and BSRs would be impacted by the lateral differences of upward methane fluxes.

• Progress in Superconductivity and Cryogenics
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• v.6 no.2
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• pp.46-51
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• 2004

This paper presents the results of a series of performance and reliability tests for the Stirling cryocooler. Infrared sensor systems incorporating cryocoolers are required to be qualified to the appropriate specification for the performance and reliability. FPFD Stirling cryocooler is currently under development for cooling infrared detector. Manufactured Stirling cryocooler delivers approximately 0.9W cooling at 80K for 30W∼40W of input power. It takes approximately 2 minutes to cool down to 80K at the ambient temperature of 23$^{\circ}C$. Performance characteristics for the vibration, acoustic noise, EMI and leak rate of the Stirling cryocooler are evaluated. We performed low and high temperature keeping test from -32$^{\circ}C$ to +52$^{\circ}C$ and operating test at high and low temperature cyclic range with acceptance tests performed at scheduled intervals. Cooling capacity is determined as a function of the temperatures at the compressor, hot end and cold tip at the expander. Finally, we describe the experimental facility for the MTTF evaluation and some typical results of the Stirling cryocooler.

• Journal of Korean Tunnelling and Underground Space Association
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• v.7 no.1
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• pp.13-25
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• 2005

In general, tunnel ventilation is analyzed with the assumption of equal vehicular speed for both directions in bidirectional traffic tunnels. This practice is likely to result in minimizing the piston effects and cannot take into consideration the effects of real situations, since in most cases, speeds of vehicles moving in opposite directions are not equal. Therefore, The ultimate goal of this study is to review the effects of unequal vehicular speeds on the planning of local bidirectional tunnel ventilation. To apply unequal vehicular speed for the bidirectional tunnel ventilation plan, the following requirements are necessary; (1) Adoption of strict smoke concentration standards for 'free-flow & congested' traffic conditions, (2) Selection of an appropriate ratio of heavy directional traffic volume, and (3) Selection of reasonable stepwised magnitude of speed difference. Based on the importance of research topic, this study aims at comparing the differences of the capacity of ventilation equipment for the cases with equal and unequal vehicular speeds in local bidirectional tunnels.

• 한국연소학회:학술대회논문집
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• 2003.05a
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• pp.35-39
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• 2003

A numerical study is carried out to investigate combustion phenomena in a model SCRamjet engine, which has been experimentally studied at the Australian National University using a T3 free-piston shock tunnel. The Mach number is 3.8, the static pressure 110kPa and the static temperature 1100K in the main air flow. The fuel is hydrogen, which is injected in the cavity. Equivalence ratio is set to either 0.25 or 0.5 to access its effect on the fuel-air mixing combustion phenomena. The results show that the cavity generates several recirculation zones, which increase the fuel-air mixing. Self ignition occurs near the point of fuel injection. The flame is anchored by the cavity and generates the precombustion shock on the step. For a high equivalence ratio, the recirculation zones are bigger and the flame is present throughout the combustor.

• Transactions of the Korean hydrogen and new energy society
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• v.16 no.1
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• pp.66-73
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• 2005

Hydrogen linear power system is estimated as the next generation power system which can obtain a performance as same as fuel cell. In order to develop Hydrogen combustion power system with high thermal efficiency, it is very important to understand the basic characteristics of hydrogen combustion and establish combustion stabilization technique of its system. In this study, RICEM(Rapid Intake Compression Expansion Machine) for researching of hydrogen combustion linear power system was manufactured and evaluated, and the basic characteristics of linear RICEM were analyzed.

• 한국연소학회:학술대회논문집
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• 2006.10a
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• pp.209-219
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• 2006

The supersonic combustion experiments are carried out using T3 free-piston shock tunnel. Different shock tube fill pressures have various inflow conditions. $15^{\circ}$ inclined hydrogen fuel injection is located before the cavity. Oblique shock is generated at the trailing edge of the cavity and reflects off the top and bottom wall. For non-reacting flow, static pressures in low equivalence ratio are similar to those in no fuel injection. As equivalence ratio is increased, static pressures are increased in the duct. In the similar equivalence ratio, static pressures are increased when total enthalpy is decreased. For reacting flow, the flame is occurred near the cavity. The combustion is weak locally in the middle of the duct. The up and down pressure distribution in the duct means that the supersonic combustion is generated.

• Ceramist
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• v.10 no.3
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• pp.55-66
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• 2007

Infrared Scanning Near-field Optical Microscopy (IR-SNOM) is an extremely powerful analytical instrument since it combines IR spectroscopy's high chemical specificity with SNOM's high spatial resolution. In order to do this in the infrared, specialty chalcogenide glass fibers were fabricated and their ends tapered to generate SNOM probes. The fiber tips were installed in a modified near field microscope and both inorganic and biological samples illuminated with the tunable output from a free-electron laser located at Vanderbilt University. Both topographical and IR spectral images were simultaneously recorded with a resolution of ${\sim}50\;nm$ and ${\sim}100\;nm$, respectively. Unique spectroscopic features were identified in all samples, with spectral images exhibiting resolutions of up to ${\lambda}/60$, or at least 30 times better than the diffraction limited lens-based microscopes. We believe that IR-SNOM can provide a very powerful insight into some of the most important bio-medical research topics.

• Transactions of the Korean hydrogen and new energy society
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• v.21 no.4
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• pp.321-327
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• 2010

Current rechargeable battery cannot provide high energy density and the operational durations required. But linear engine/generators provide high energy density for portable power applications because fuel is more high density. In this paper, we suggest that basic design of powerpack using linear engine for assisting power output. Efficiency is relatively high because linear engine don't have crank mechanism compared with rotary engine. We made prototype engine and had experiments to know moving characteristic about the Linear Engine. It was possible to operate velocity at 50 Hz at the firing and pressure in cylinder was 16bar.