• Korean Chemical Engineering Research
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• v.58 no.4
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• pp.581-587
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• 2020

In this study, a new reaction system is proposed to solve the problems of the existing 2,3-Butanediol (2,3-BDO) dehydration reaction system. It was confirmed that the reaction system did not wok as it should operate properly when using a furnace, which is commonly used in commercial processes, to raise the reactant, 2,3-BDO, to the reaction temperature, 360 ℃, at near atmoshperic pressure. It is because of the substance considered to be oligomers of 2,3-BDO. It can lead to safety problems, such as blockages inside the furnace's tube and explosions, as well as tricky maintenance issues in the reaction system. To solve it, the temperature of reactant can be brought down by using a heat exchanger with High Pressure (HP) steam instead of the furnace, which has a hot spot problem through the vacuum operation and reduce the reaction temperature. It can be seen that the reactor performance is almost similar under the vacuum operation and the lower reaction temperature, 330 ℃, by using a reaction kinetics. This result explains why the new reaction system is proposed.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.5
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• pp.549-554
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• 2011

Recently, technical advances have been made in high efficiency gas turbine power plants. In domestic gas turbine facilities, the material properties of the blade and vane are degraded by the daily start-stop operations arising from the thermo mechanical cycle. We surveyed the time dependent degradation of the HP blade and vane to gather basic data for life assessment and damage analysis. The EOH(equivalent operating hours) of the blades were 23,686, 27,909, and 52,859 and the EOH of the vanes were 28,714 and 52,859, respectively. With increased operating hours, the shape of the primary ${\gamma}$' precipitate transformed from cubic to spherical, and its average size also increased. The leading edge area of the blades and the center of the vanes had the worst morphology, and this tendency agrees with the microhardness results. The thickness of the thermally grown oxide at the outer surface of the bond coat increased with increased operating hours.

• Tunnel and Underground Space
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• v.19 no.2
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• pp.77-85
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• 2009

Flexible and lined segment air-tight tunnelling technology for Compressed Air Energy Storage-Gas Turbine(CAES-G/T) power generation was introduced. The distinguished characteristics of the air-tight tunnel system can be summarized by two facts. One is that the high inner pressure due to compressed air is sustained by surrounding rock mass with allowing sufficient displacement of lining segment. The other is that the air-tightness of storage tunnel was enhanced by adopting a specially designed rubber sheet. The flexible lined air-tight underground tunnel can be constructed at a comparatively shallow depth and near urban area so that the locally distributed CAES-G/T power generation can be accomplished. In addition, this air-tight tunnelling technology can be applied to a variety of energy underground storage tunnels such as Compressed Natural Gas(CNG), Liquifed Petroleum Gas(LPG), DeMethyl Ether(DME) etc.

• Korean Journal of Materials Research
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• v.3 no.5
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• pp.521-528
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• 1993

Ni-graphi~e composite powders were prepared by reduct ion of $Ni^{++}$ from arnmoniacal nickel sulfate solution on graphite core by hydrogen gas at elevated temperature and pressure. Effect of coating catalyst. Anthraquinone $(C_6H_4COC_6H_4 CO)$, on the reduction rate and the properties of nickel layer were investigated by SEM, X-ray, size and chemical analysis. 1nduct.ion period, a time lag between the ~njection of hydrogen gas and the start of the reduction, was 22 to 70 mins and was affected by the size and amount of Anthraquinone. Kickel layer deposited on the surface of graphite core material was composed of nickel nodules whose sizes were different with vari~ ous reduction conditions. Minimum diameter of nickel nodules was about 2-3$\mu \textrm m$.

• Journal of the Korean Ceramic Society
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• v.49 no.6
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• pp.608-613
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• 2012

We investigated the property changes of MgO powders sintered at temperatures ranging from $700^{\circ}C$ to $1900^{\circ}C$ for 5minutes at a pressure of 2.7 GPa for a high-pressure high-temperature(HPHT) diamond synthesis process. The physical properties of the sintered MgO powders were characterized by optical microscopy, field emission scanning electron microscopy (FE-SEM), Vickers hardness tests, and by the apparent density, and X-ray diffractometry. An optical micro-analysis showed that white MgO powders became black after sintering due to carbon contamination from the graphite heat source. FE-SEM revealed the growth in the grain size of the MgO powders from $0.3{\mu}m$ to $50{\mu}m$ after sintering at $1700^{\circ}C$. The hardness and apparent density increased to $1800^{\circ}C$ while the samples were dedensified at $1900^{\circ}C$ due to the growth of isolated pores. According to the XRD analysis, no phase transformation occurred in the MgO powders. These results suggest that HPHT-sintered MgO powders can show an accelerated sintering process characterized by grain neck growth, pore connections, isolated pore growth and dedensification in 5 minutes, while these processes with the conventional sintering process take at least 5 hours.

• Applied Chemistry for Engineering
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• v.25 no.1
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• pp.113-115
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• 2014

Lab scale simulated steam assisted gravity drainage (SAGD) process devices were used to investigate the effect of inorganic additives for the bitumen recovery from oil sand. An extra heavy oil similar with bitumen and 1.5 mm diameter of the glass bead instead of clay was mixed to simulate the oil sand. In addition, $FeO_X$ synthesized from the inorganic process was introduced as an inorganic additive for improving the recovery. Finally, the steam heat transfer rate of approximately 40% following the introduction of inorganic additives which also increased the recovery rate by about 30%.

• Journal of the Korean Institute of Gas
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• v.2 no.3
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• pp.25-36
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• 1998

Explosion and fires can occur in all segments of chemical and petroleum industries because of complexity of process, usage and storage of flammable and reactive chemicals, and operating conditions of high pressure and temperatures. Especially chemical plants have high possibility of the occurrence of BLEVE(Boiling Liquid Expanding Vapor Explosion)and Fireball. In this study, a computer program was developed for the effect assessment of BLEVE and Fireball. BLEVE was analysed by three explosion models of physical explosion model, isothermal expansion model and adiabatic expansion model and Fireball using solid model. The parametric sensitivity analysis has been done for the models of BLEVE and Fireball. The damage by BLEVE and Fireball of Benzene and Toluene and m-Xylene were estimated.

• Food Science and Industry
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• v.53 no.3
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• pp.277-283
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• 2020

Microbial disinfection is essential to increase the preservation and safety of food. In general, thermal sterilization technology is most frequently used, but it often causes nutrient denaturation, and deterioration of food quality. Accordingly, non-thermal sterilization using a novel technology is emerging as an alternative technology. Among them, ultrasonic technology produces a disinfection effect by promoting the destruction of microorganisms by cavitation. Ultrasound technology alone has a low effect, so research is being actively conducted to develop an effective technology by applying as a hurdle technology with various other technologies. Ultrasound can be treated with various processes including traditional sterilization methods such as heating, high pressure, and chemical treatment, as well as novel technologies such as ultraviolet irradiation. Ultrasound assisted sterilization technology still remains at the laboratory level, requiring additional research such as the development of equipment for industrial application and establishment of an optimal process.

• Journal of the Korean Society of Food Science and Nutrition
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• v.36 no.6
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• pp.773-778
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• 2007

This study was performed to develop a more simple and convenient heat treatment process for increasing heating temperature than the traditional 9-times steaming process for Rehmanniae radix Preparata (R. radix P.). The R. radix was heated to various temperatures (110, 120, 130, 140 and $150^{\circ}C$) for different lengths of time (1, 2, 3, 4 and 5 hr). Chromaticity, free sugar, amino acid, catalpol and 5-HMF (5-hydroxy-methyl-2-furaldehyde) content of water extracts of R. radix P. were analysed. With increasing heating temperature and time, the L, a and b-value of samples gradually decreased. Fructose and glucose contents were increased to $120^{\circ}C$ for 5 hr (5.21 and 6.67%, respectively) with no changes afterward. Sucrose content was not detected after $130^{\circ}C$. Total amino acid was increased to $140^{\circ}C$ and decreased afterward. The maximum total amino acid content was 4,172 mg/100 g at $140^{\circ}C$ for 2 hr (R. radix L.: 3,029 mg/100 g). The catalpol was decreased to $130^{\circ}C$ for 1 hr and not detected afterward. The 5-HMF content increased with increasing heating temperature and time. The maximum content of 5.HMF was 2.5% in $150^{\circ}C$ for 5 hr. Hence, it can be suggested that the heat treatment at $130^{\circ}C$ for 2 hr or more is the most optimum processing conditions, instead of the traditional 9.times steaming process.

• Tunnel and Underground Space
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• v.19 no.6
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• pp.498-506
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• 2009

The stability assessment of a concrete liner of a compressed air storage tunnel should be performed by an approach which is different from that commonly used for the liners of road tunnels, since the liner is exposed to high air pressure. In this study, the stability analysis method for the liner of compressed air storage tunnel is proposed based on the elastic and elasto-plastic solutions of the thick-walled cylinder problem. In case of elastic analysis, the yield initiation condition at the inner boundary is considered as the failure condition of the liner, while the condition which results in the extension of yielding zone to a certain depth is taken as a failure indicator of the liner in the elasto-plastic analysis taking Mohr-Coulomb criterion. The application of the proposed method revealed that the influence of the relative magnitude of boundary loads on the stability of liner is considerable. In particular, noting that the estimation of the outer boundary load may be relatively difficult, it is thought that the precise prediction of outer boundary load is very important in the analysis. Accordingly, the emphasis is put on the selection of the liner installation time, which may govern the magnitude of outer boundary load.