• Journal of Powder Materials
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• v.22 no.4
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• pp.289-297
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• 2015

As recognized by all scientific and industrial groups, carbon dioxide($CO_2$) capture and storage(CCS) could play an important role in reducing greenhouse gas emissions. Especially carbon capture technology by dry sorbent is considered as a most energy-efficient method among the existing CCS technologies. Patent analysis has been considered to be a necessary step for identifying technological trend and planning technology strategies. This paper is aimed at identifying evolving technology trend and key indicators of dry sorbent from the objective information of patents. And technology map of key patents is also presented. In this study the patents applied in korea, japan, china, canada, US, EU from 1993 to 2013 are analyzed. The result of patent analysis could be used for R&D and policy making of domestic CCS industry.

• Bulletin of the Korean Chemical Society
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• v.34 no.2
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• pp.426-432
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• 2013

The mechanisms concerning C-Cl activation of $CCl_4$ by $CHBr^{{\cdot}-}$ and $CBr{_2}^{{\cdot}-}$ have been comparatively investigated in theory. Optimized geometries and frequencies of all stationary points on PES are obtained at the BhandHLYP/aug-cc-pVTZ level of theory, and then the energy profiles are refined at the QCISD(T) method with the aug-cc-pVTZ basis by using the BhandHLYP/aug-cc-pVTZ optimized geometries. Our calculated findings suggest that in the title reactions the major mechanisms consist of both Cl-abstraction and $S_N2$ substitution reactions. Also, a succeeding pathway described by electron transfer was revealed before the initial Cl-abstraction products separate. Those are consistent with relevant experimental results.

• Geomechanics and Engineering
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• v.17 no.6
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• pp.515-525
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• 2019

The calculation of active earth pressure behind retaining wall is a typical three-dimensional (3D) problem with spatial effects. With the help of limit analysis, this paper firstly deduces the internal energy dissipation power equations and various external forces power equations of the 3D retaining wall under the nonlinear strength condition, such as to establish the work-energy balance equation. The pseudo-static method is used to consider the effect of earthquake on active earth pressure in horizontal state. The failure mode is a 3D curvilinear cone failure mechanism. For the different width of the retaining wall, the plane strain block is inserted in the symmetric plane. By optimizing all parameters, the maximum value of active earth pressure is calculated. In order to verify the validity of the new expressions obtained by the paper, the solutions are compared with previously published solutions. Agreement shows that the new expressions are effective. The results of different parameters are given in the forms of figures to analysis the influence caused by nonlinear strength parameters.

• Transactions of the Korean Society of Automotive Engineers
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• v.17 no.2
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• pp.159-164
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• 2009

Cooled EGR system is an effective method for the reduction of $NO_x$ emission and PM emission from a diesel engine. Proper choice of wavy cooling fins and gas tubes is a key factor of cooled EGR system. As a part of solutions for energy crisis and environmental problems, hybrid vehicles mounted with diesel engines are under development globally. This study investigates the cooled EGR systems for hybrid diesel engine with the specifications of both optimized wavy cooling fins and improved shape of structure to verify the heat exchange efficiency, outlet temperature and gas pressure drop of cooler by means of numerical analyses and rig performance tests. The output of this study will be applied to a 2.0L hybrid diesel engine which is being developed for domestic and overseas market.

• Corrosion Science and Technology
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• v.4 no.6
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• pp.236-241
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• 2005

Hydrogen induced cracking (HIC) is one of the hydrogen degradation phenomena of linepipe steels caused by $H_2S$ gas in the crude oil or natural gas. However, NACE TM0284-96 standard HIC test method is hard to satisfy the steel requirements for sour service application since it uses more severe environmental conditions than actual conditions. Therefore, in order to use steels effectively, it is required to evaluate HIC resistance of steels in the practical range of environmental severity. In this study, HIC resistance of two high strength low alloy (HSLA) steels being used as line pipe steels was evaluated in various test solutions with different $H_2S$ pressures and pH values. The results showed that the key parameter affecting crack area ratio (CAR) is $H_2S$ partial pressure of test solution when the pH value of test solution is not over 4. Hydrogen diffusivity was not a constant value, but it was rather affected by the hydrogen ion concentration (pH value) in the solution.

• ETRI Journal
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• v.32 no.3
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• pp.440-446
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• 2010

Array-based gas sensors now offer the potential of a robust analytical approach to odor measurement for medical use. We are developing a fast reliable method for detection of microbial infection by monitoring the headspace from the infected wound. In this paper, we present initial results obtained from wound-state monitoring for burn patients using an electronic nose incorporating an automated solid-phase microextraction (SPME) desorption system to enable the system to be used for clinical validation. SPME preconcentration is used for sampling of the headspace air and the response of the sensor module to variable concentrations of volatiles emitted from SPME fiber is evaluated. Gas chromatography-mass spectrometry studies prove that living bacteria, the typical infectious agents in clinical practice, can be distinguished from each other by means of a limited set of key volatile products. Principal component analysis results give the first indication that infected patients may be distinguished from uninfected patients. Microbial laboratory analysis using clinical samples verifies the performance of the system.

• Bulletin of the Korean Chemical Society
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• v.35 no.4
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• pp.1029-1035
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• 2014

The protolytic dissociation process of hydrochloric acid (HCl) and hydrofluoric acid (HF) is studied using the B3LYP and MP2 methods with the 6-311+G(d,p) basis set in the gas phase and in aqueous solution. To study the phenomena in detail, discrete and discrete/continuum models were applied by placing water molecules in various positions around the acid. The dissociation process was studied using the thermodynamic cycle involving the structures optimized both in the gas phase and in aqueous solution and was analyzed with two key energy factors, relaxation free energy (${\Delta}G_{Rex(g)}$) and solvation free energy (${\Delta}G_s$). Based on the results, we could understand the dissociation mechanism and wish to propose the best way to study acid dissociation process using the CPCM methodology in aqueous solution.

• Journal of Sensor Science and Technology
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• v.22 no.5
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• pp.315-320
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• 2013

In this paper, the properties of strain sensors made of spin-capable multi-walled carbon nanotubes (MWCNTs) were characterized and their sensing mechanisms analyzed. The key contribution of this paper is a new fabrication technique that introduces a simpler transfer method compared to spin-coating or dispersion CNT. Resistance of the MWCNT sheet strain sensor increased linearly with higher strain. To investigate the effect of CNT concentration on sensitivity, two strain sensors with different layer numbers of MWCNT sheets (one and three layers) were fabricated. According to the results, the sensor with a three-layer sheet showed higher sensitivity than that with one layer. In addition, experiments were conducted to examine the effects of environmental factors, temperature, and gas on sensor sensitivity. An increase in temperature resulted in a reduction in sensor sensitivity. It was also observed that ambient gas influenced the properties of the MWCNT sheet due to charge transfer. Experimental results showed that there was a linear change in resistance in response to strain, and the resistance of the sensor fully recovered to its unstressed state and exhibited stable electromechanical properties.

• Structural Engineering and Mechanics
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• v.68 no.1
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• pp.95-101
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• 2018

The low rate of penetration and short lifetime of drilling bit served as the most common problems encountered in hard formation drilling, thus leading to severe restriction of drilling efficiency in oil and gas reservoir. This study developed a new local impact drilling method to enhance hard formation drilling efficiency. The limitation length formulas of radial/lateral cracks under static indentation and dynamic impact are derived based on the experimental research of Marshall D.B considering the mud column pressure and confining pressure. The local impact rock breaking simulation model is conducted to investigate its ROP raising effect. The results demonstrate that the length of radial/lateral cracks will increase as the decrease of mud pressure and confining pressure, and the local impact can result in a damage zone round the impact crater which helps the rock cutting, thus leading to the ROP increase. The numerical results also demonstrate the advantages of local impact method for raising ROP and the vibration reduction of bit in hard formation drilling. This study has shown that the local impact method can help raising the ROP and vibration reduction of bit, and it may be applied in drilling engineering.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.03a
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• pp.828-836
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• 2008

To develop an engineering-model of hydrogen-fueled ultra-micro combustor for Ultra Micro Gas Turbine(UMGT), we reviewed and summarized the problems in downsizing combustors, and determined a suitable burning method. The key issue to actualize practical ultra-micro combustors is reducing heat loss from the combustor to compressor and turbine. The reduction of heat loss was discussed from 3 different viewpoints; heat-insulation material, high-space-heating-rate combustion, and combustor-insolated gas turbine structure. Use of heat-insulation material induced the heat loss reduction to the surroundings. The heat loss ratio decreased substantially in reverse proportion to space heating rate, leading the idea that it could be reduced by burning at a high space heating rate. By settling the combustor insolated from the compressor and turbine, the heat transfer from the combustor to the compressor and turbine becomes smaller. For a selection of the suitable burning method, comparison between 2 burning methods, flat-flame and swirling-flamer types, was conducted. Synthetically the flat-flame burning method was confirmed to be more suitable for ultra-micro combustors than latter one. Base on them, an engineering-model of hydrogen-fueled flat-flame ultra-micro combustor was developed. To obtain high overall heat-insulation, heat-resistant and strength, the engineering-model combustor had triple layer structure with an advanced ceramic, a heat insulation material and a stainless steel. To simplify heat transfer issue in the combustor, it was isolated from the other components. Furthermore it was designed by considering structure, size, material, velocity, pressure loss and prevention of flashback.