• 한국연소학회:학술대회논문집
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• 2014.11a
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• pp.107-109
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• 2014

Through the economic development, people enjoying the camping and demand of camping goods are increasing since they have free time. So they use portable butane gas range outdoor. In addition to that, many restaurants that offer hotpot or meat in Korea use portable butane gas ranges for their convenience. But 19% of gas accidents are using portable butane gas range, 13.7% of them are using oversized cookware. Despite the high accident rate, there is no safety standards about portable butane gas range using oversized cookware. Therefore we conducted to measure temperature and pressure of portable butane gas ranges for reforming safety standards. As a result. we confirmed relation between bottom temperature of the portable butane gas barrel and pressure of the butane gas. Also we confirmed that portable butane gas ranges operate safely when bottom temperature of the portable butane gas barrel is bellow $50^{\circ}C$.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.634-637
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• 2005

Multichannel seismic data acquired in Ulleung Basin of East Sea for gas hydrate exploration. The seismic sections of this area show strong BSR(bottom simulating reflections) associated with methane hydrate occurrence in deep marine sediments. Very limited information is available from deep sea drilling as the risk of heating and destabilizing the initial hydrate conditions during the processing of drilling is considerably high. Not so many advanced status of gas hydrate exploration in Korea, the most of information of gas hydrate characteristics and properties are inferred from seismic reflection data. In this study, The AVO analysis using the long offset seismic data acquired in Ulleung Basin used to explain the characteristics and structure of gas hydrate. It is used primarily P-wave velocity accessible from seismic data. To make a good quality of AVO analysis input data, seismic preprocessing including 'true gain correction', 'source signature deconvolution', twice velocity analysis and some kinds of multiple rejection and enhancing the signal to noise ratio processes is carried out very carefully. The results of AVO analysis, the eight kinds of AVO attributes are estimated basically and some others of AVO attributes are evaluated for interpretation of AVO analysis additionally. The impedance variation at the boundary of gas hydrate and free gas is estimated for investing the BSR characteristics and properties. The complex analysis is performed also to verifying the amplitude variation and phase shift occurrence at BSR. Type III AVO anomaly appearance at saturated free gas area is detected on BSR. It can be an important evidence of gas hydrate deposition upper the BSR.

• Membrane Journal
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• v.24 no.5
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• pp.341-349
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• 2014

Molecular dynamics (MD) computer simulation is a very useful tool to calculate the trajectory and velocity of particles (generally, atoms), and thus to analyze the various structures and kinetic properties of atoms and molecules. For gas separation membranes, MD has been widely used for structure analysis of polymers such as free volume analysis and conformation search, and for the study of gas transport behavior such as permeability and diffusivity. In this paper, general methodology how to apply MD on gas separation membranes will be described and various related researches will be introduced.

• Journal of Welding and Joining
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• v.11 no.1
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• pp.52-61
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• 1993

Laser welding of ASTM no. 1060 Al plate with a pulsed Nd: YAG laser of 200W average power was performed for end capping of KMRR nuclear fuel elements In this research, we performed basic welding experiments. Firstly, laser output parameters which affect laser welding parameters were studied by changing laser input parameters for effective welding of 1060 Al plates. We found that laser power density and pulse energy are important parameters for smooth bead shape. Secondly, welding parameters which affect weld width-to-depth ratio were studied by changing power density and pulse energy, shielding gas, and defocusing. We found that power density must be higher than 0.3 Mw/cm$^{2}$ pulse energy must be higer than 3 J. travel speed must not exceed 200mm/sec, laser focus must be existed beneath 2-3mm from plate surface and helium is proper shielding gas. Thirdly, we studied the weld defects of Al-1060 such as crack and porosity in lap-joint welding. We designed new welding geometry for crack free welding of Al-1060 plates, and obtained crack free weldment but with lack of fusion. However, with Ti, Zr grain refiner elements, we can weld Al plates without solidification hot crack. Finally, we studied the origin of porosity by changing shielding gas. And we found that porosity was resulted from entrapment of shielding gas by the collapsing keyhole.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.233-233
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• 2010

Magnetic random access memory (MRAM), based on magnetic tunnel junction (MTJ) and CMOS, is a prominent candidate among prospective semiconductor memories because it can provide nonvolatility, fast access time, unlimited read/write endurance, low operating voltage and high storage density. The etching of MTJ stack with good properties is one of a key process for the realization of high density MRAM. In order to achieve high quality MTJ stack, the use of CoFeB and IrMn magnetic films as free layers was proposed. In this study, inductively coupled plasma reactive ion etching of CoFeB and IrMn thin films masked with Ti hard mask was investigated in a $Cl_2$/Ar gas mix. The etch rate of CoFeB and IrMn films were examined on varying $Cl_2$ gas concentration. As the $Cl_2$ gas increased, the etch rate monotonously decreased. The effective of etch parameters including coil rf power, dc-bais voltage, and gas pressure on the etch profile of CoFeB and IrMn thin film was explored, At high coil rf power, high dc-bais voltage, low gas pressure, the etching of CoFeB and IrMn displayed better etch profiles. Finally, the clean and vertical etch sidewall of CoFeB and IrMn free layers can be achieved by means of thin Ti hard mask in a $Cl_2$/Ar plasma at the optimized condition.

• Geophysics and Geophysical Exploration
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• v.17 no.4
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• pp.216-230
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• 2014

Based on the interpretation of 3D seismic profiles acquired in the northwestern area of the Ulleung Basin, East Sea, the shallow sediments consist of five seismic units separated by regional reflectors. An anticline is present in the study area that documents activity of many faults. Bottom simulating reflectors are characterized by high RMS amplitude. Acoustic blanking with low RMS amplitude is distinctively recognized in the gas hydrate stability zone. Seismic attribute analysis shows that if gas hydrates are underlain by free gas, the high reflection strength and the low instantaneous frequency are displayed below the boundary between them. Whereas, if not, the reflection strength is low and instantaneous frequency is high continuously below the gas hydrate zone. Based on the spectral decomposition of the bottom simulating reflector, the high envelope at the specific high frequency range indicates the generation of the tuning effect due to the lower free gas content. Four models for the occurrence of the gas hydrate are suggested considering the slope of sedimentary layers as well as the presence of gas hydrate or free gas.

• Laser Solutions
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• v.4 no.3
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• pp.30-39
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• 2001

This work was tamed out to apply a laser welding technique in joining between a Zn coated low carbon steel plate(SECC) and a free cutting carbon steel shaft(SUM24L) with or without W coating. Experiments were carried out and analysed by applying the FD(factorial design)method to obtain the optimum Laser welding condition. Optical microscopy, SEM, TEM and XRD analyses were performed in order to observe the microstructures in the fusion zone and the HAZ. Mechanical properties of the welded specimens were examined by microhardness test, tensile test and twist test. There was no flawed Zn in the fusion zone by EDS analysis. This means that during the welding process, Zn gas could be eliminated by appropriate shielding gas flow rate and butt welding gap. Ni coating itself did not influence on the tensile strength and hardness. However, twist bending strength and the weld depth of the Ni-coated free cutting carbon steel were lower as compared with those of the uncoated free cutting carbon steel. It was attributed to a lower absorbance of laser beam to the shin Ni surface. According to the results of the factorial design tests, the twist bending strength of welded specimens was primarily affected by pulse width, laser power, frequency and speed.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.15 no.2
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• pp.31-37
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• 2016

In the steam system, a stream trap valve discharges a condensate and a non-condensable gas. It also prevents stream from being leaked. The free float stream trap valve is a mechanical type of stream trap. The valve is opened when a hallow ball is floated due to the density of the condensate through the condensate flows into the valve. On the other hand, when the flow of the condensate is completed, the valve is closed as the float subsides due to the weight of the structure and the stream is blocked. In addition, the bimetal lifts the hallow ball, which discharges the non-condensable gas. In this study, the performance of the properties of the free float stream trap valve, the method of support for three points, and the orifice design are researched. Moreover, the condensate discharge capacity of the free float stream trap valve is calculated from the experiment.

• 한국전기화학회:학술대회논문집
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• 2005.07a
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• pp.173-176
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• 2005

• Bulletin of the Korean Chemical Society
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• v.26 no.4
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• pp.589-593
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• 2005

The solvation free energy of proton in methanol was calculated by B3LYP flavor of density functional calculations in combination with the Poisson-Boltzmann continuum solvation model. In order to check the adequacy of the computation level, the free energies of clustering in the gas phase were compared with the experimental data. The solvents were taken into account in a hybrid manner, i.e. one to five molecules of methanol were explicitly considered while other solvent molecules were represented with an implicit solvation model.