• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.48 no.5
• /
• pp.379-384
• /
• 1999

Langmuir-Blodgett(LB) films which have high ordered orientation and ordering structure are fabricated by LB method which deposit the ultra-thin films of organic materials at a molecular level. The electrical characteristics of stearic acid LB ultra-thin films for the horizontal direction were investigated to develop the gas sensor using LB ultra-thin films. The optimal deposition condition to deposit the LB ultra-thin films was obtained from $\pi-A$ isotherms and the deposition status of stearic acid LB ultra-thin films was verified by the measurement of deposition ratio, UV-absorbance, and electrical properties for LB ultra-thin films. The conductivity of stearic acid LB ultra-thin films for horizontal direction was about $10_{-8}[S/cm]$. The activation energy for LB ultra-thin films with respect to variation of temperature was about 1.0[eV], which was correspond to semiconductor material. The response characteristics for organic gas were confirmed by measuring the response time, recovery time, and reproducibility of the LB ultra-thin to each organic gas. Also, the penetration and adsorption behavior of gas molecule were confirmed through the organic gas response characteristics of LB ultra-thin films with respect to temperature.

• Korean Chemical Engineering Research
• /
• v.49 no.1
• /
• pp.35-40
• /
• 2011

The low caloric LNG, which didn't meet the gas interchangeability of Korea, has been imported from 2005 winter season. Amount of this LNG imports has been increased from year to year. In the near future, very low caloric LNG (calorific value ${\leq}$ 9,500 kcal/$Nm^3$) such as CBM, Shale LNG will be imported large amounts. For this reason, we need a method for monitoring live calorific values(CV) of LNG in each storage tank to supply gasified LNG with interchangeable CV at LNG receiving terminal. This study was conducted to develope the method for measuring the live CVs of LNG in each storage tank using LNG densitometer. For this purpose, the accurate correlation between CV and density of LNG was derived and the uncertainty of this method was evaluated and also the measuring system for CVs was constructed at LNG receiving terminal. To verify this method, the results of measurement using this method were compared with the field data of LNG analysis and the results showed that the deviations were 0.17~0.47%.

• International conference on construction engineering and project management
• /
• 2013.01a
• /
• pp.204-208
• /
• 2013

CO2 emission makes up more than 80% of whole green gas. Therefore CO2 is recognized as the main culprit of global warming. IPCC (Intergovernmental Panel on Climate Change) is advising the 3 methods measuring CO2 emission. TIER1 is measured CO2 emission by criteria the energy consumption, TIER2 measure by criteria the emission factor according to the emission control technique each kind of vehicle, TIER3 is measured by criteria the distance each kind of vehicle. Currently, the most of CO2 emission measurement is used by TIER1. But it is not standardized that CO2 emission measurement method have the factor as work condition each distance. Specially, it is not suggest that methodology has the condition changing load of equipment according to site condition and the same position work as construction equipment. So, this study is suggested the CO2 emission measurement methodology of construction equipment.

• Journal of the Korean Ceramic Society
• /
• v.25 no.4
• /
• pp.341-348
• /
• 1988

Thin films of tin-oxide were prepared by chemical vapor deposition technique using the direct of SnCl4. Resistivity and carrier concentration of deposited SnO2 thin film were measured by 4-point probe method and Hall effect measurement. The results showed the remarkable dependence of electrical properties on the deposition temperature. As the deposition temperature increased, resistivity of deposited film initially decreased to a minimum value of ~10-3$\Omega$cm at 50$0^{\circ}C$, and then rapidly increased to ~10$\Omega$cm at $700^{\circ}C$. Electrical conductance of these films was measured in exposure to H2 gas. It was found that gas sensitivity was affected combination of film thickness and intrinsic resistivity of deposited film. Gas sensitivity increased with decrease of film thickness. Fairly high sensitivity to H2 gas was obtained for the film deposited at $700^{\circ}C$. Optimum operation temperature of sensing was 30$0^{\circ}C$ for H2 gas.

• 전기의세계
• /
• v.26 no.2
• /
• pp.104-110
• /
• 1977

This paper investigates temperature distribution of plasma jets which used argon gas, and nitrogen gas mixed with argon as working fluids in spectroscopic method, and studies correlations between them main results are as follows; 1) The temperature at the center of plasma jet increases with are current and gas flow, and decreases with magnetic flux density along the axial direction. 2) The changing rate of temperature of plasma jet in the radial direction decreases rapidly beyond 2mm from central axis. 3) Temperature drop rate of plasma jet in the central axis direction appears most apparant beyond 13mm above the nozzle exit. 4) When argon gas mixed with a small amount of nitrogen, plasma temperature increases at same are current compared with the case of argon gas only.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2008.11a
• /
• pp.41-44
• /
• 2008

In this paper, the gas generator using hydrogen peroxide catalytic decomposition was designed for turbine generator operation. The gas generator used 90wt% rocket-grade of hydrogen peroxide and manganese dioxide as a catalyst. Turbine generators utilizing gas generators were investigated and the prestudy was prepared using automobile turbocharger instead of turbine generator.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.29 no.8
• /
• pp.49-54
• /
• 2015

Molded Circucit Breaker(MCCB) is a most widely used device to protect loads from the over-current in low power level distribution system. When the MCCB interrupts the over-current, the arc discharge occurred between fixed contact and moving contact to create hot gas. By the Lorentz force due to arc current, the occurred arc is bent to the grids. The grids extend and cool and divide it for arc extinguish. In the majority cases, the MCCB protects loads by interrupting the over-current successfully but in some cases the re-ignition is occurred by hot-gas created during process of interruption. The re-ignition arises when the recovery voltage(RV) is more higher than the recovery strength between contacts and it leads to interruption fault. Therefore to find out the dielectric recovery characteristics of protecting device has a great importance for preventing interruption fault. In this paper, we studies measurement method of the dielectric recovery characteristics considering inherent attribute of the MCCB. To measure the dielectric recovery characteristic of MCCB, we makes an experiment circuit for applying the over-current and the randomly recovery voltage. The measurement methode to find out the dielectric recovery voltage of the MCCB was established and the result was based on experiment results.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2004.03a
• /
• pp.617-621
• /
• 2004

Miniaturization of subsystems including propulsion systems is recent trends in spacecraft technology. Small space vehicle propulsion is not only a technological challenge of a scaling system down, but also a combination of fundamental flow/combustion constraints. In this paper, physical constraints of micronozzle for cold gas micro-thruster are reviewed and discussed. Method to measure small thrust are also described.

• Elastomers and Composites
• /
• v.54 no.3
• /
• pp.209-219
• /
• 2019

It is important to analyze crosslink densities of rubber articles because the physical properties are dependent on the crosslink densities. In this paper, analytical techniques for the measurement of crosslink densities of rubber vulcanizates are described. The most widely used method to measure the crosslink density is a swelling method combined with the Flory-Rehner equation. Application of the interaction parameter (${\chi}$) of rubber and swelling solvent is critical because the crosslink density is absolutely dependent on the ${\chi}$ value. Methods for obtaining ${\chi}$ employ not only solubility parameters of the polymer and swelling solvent but also inverse gas chromatography (IGC). The solubilities of rubbers can be obtained using micro differential scanning calorimetry (${\mu}DSC$), intrinsic viscosity measurement, and UV-visible spectroscopy. Nuclear magnetic resonance (NMR) spectroscopy has been also used for the measurement of the crosslink density using the $T_2$ relaxation time, which is determined by spin-spin relaxation in solid-state NMR. For sulfur-cured rubber vulcanizates, crosslink densities according to the crosslink types of mono-, di-, and polysulfides are measured by treating the rubber samples with a chemical probe composed of thiol and amine compounds. Measurement methods of physical crosslinking by filler, crystallization, and ionic bonding have also been introduced.

• Tribology and Lubricants
• /
• v.35 no.3
• /
• pp.151-157
• /
• 2019

Insulated oil degradation produces charged by-products, such as acids and hydro-peroxides, which tend to reduce the insulating properties of the oil. In this study, UV-vis spectroscopy measurement technology is developed and experimentally compared with other measurement methods, such as the titration method and IR spectroscopy, to validate its ability to monitor the degradation of electrical insulating paper. The degradation characteristics of the insulating paper are appropriately represented through various types of measurement methods, such as the Tan (delta) method, $CO_2$ gas production measurement, the titration method, and IR spectroscopy. The results are demonstrated to be well comparable to a change in the fluorescence emission ratio (FER), which is defined as the shift in fluorescence intensity in the measured wavelength range, and also to the chromatic ratio, which is defined as a color shift to longer wavelength ranges. The results also show that, by using UV-vis spectroscopy, it is possible to detect the degradation of the insulating paper. This study suggests that UV-vis spectroscopy can be applied as an alternative to high-performance liquid chromatography, which is the internationally recognized measurement technology for cellulose paper degradation. The FER detector is also verified to be useful as an effective condition-monitoring device for power transformers.