• Journal of the Korean GEO-environmental Society
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• v.21 no.5
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• pp.23-33
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• 2020

As the scale of the economy expands, the number of cases of damage in enclosed spaces such as tunnels is increasing due to the accident of transportation vehicles of dangerous substances such as explosive flammable materials that have increased rapidly. In the case of road tunnels in particular, in the aspect of protection against the long-winding trend and the environment in the downtown area, the number of cases of passing through the downtown area increases, and securing the safety of structures against unexpected extreme disasters such as explosions during tunnel passage is very urgent. For this reason, developed countries are already conducting a review of internal bombardment, but there are almost no evaluation and countermeasures for explosion risk in Korea. Therefore, in this study, in order to evaluate the explosion safety of road tunnels, a boiling liquid explosive explosion (BLEVE), which is considered to have the greatest explosion load among vehicles driving on the road, is set as a reference explosion source, and the equivalent TNT explosion load is used for simulation of the explosion. A method of conversion was presented. In addition, by applying the derived explosion load, dynamic behavior simulation was performed by assuming various variables for the tunnel, and the explosion safety of the tunnel was analyzed.

• Journal of the Korean Chemical Society
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• v.33 no.3
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• pp.326-331
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• 1989

Superconducting fiber of high Tc $YBa_2Cu_3O_{7-{\sigma}}$ was successfully prepared by the sol-gel method. The stoichiometric mixture of Y, Ba and Cu nitrates was dissolved in water, to which citric acid solution was added. Then ammonium hydroxide was added to the mixture in order to increase the pH to a value between 5.8 and 6.2. The mixture was heated carefully to form a homogeneous colloid sol at 358 K. The solution was viscous enough to draw a long gel fiber, which was then heated at 1223K for 8 hrs. under oxygen partial pressure of $Po_2$ = 1 atm., cooled slowly and annealed at 723K for 13 hrs.. The reacted superconducting sample maintained a fiber form with some shrinkage of its volume. The superconducting transition temperatures (Tc, onset and Tc, offset) of $YBa_2Cu_3O_{7-{\sigma}}$ have been determined to be approximately 95K and 82K, respectively. The superconducting phase was also confirmed by Meissner effect at liquid nitrogen boiling temperature.

• Journal of the Korean Wood Science and Technology
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• v.27 no.3
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• pp.17-22
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• 1999

The effect of microwave irradiation on wood bending was investigated in this study. The specimens irradiated with microwave were bent around a form by using pedestal-steel and clamps. The specimens, korea red pine (Pinus densiflora), for this test were water-soaked for 78 hours. Saturated specimens were boiled in water for an hour. The size of specimens was 350mm(L) by 20mm(R) by 10mm(T). These specimens were heated by microwave of 2,450MHz. The most suitable time for microwave irradiation seems to range from 60 to 90 seconds. Wood moisture content decreased remarkably with the increase of irradiation time. When a softened wood piece is bent, its convex side was stretched while the concave side was compressed. It can be compressed considerably, but stretched very little. Therefore the failure will be governed by the tensile breaking strain and occur mainly on the convex face. So we obtained results from three different bending process methods as follows : 1) When bending with a pedestal-steel, convex face had not tensile breakings, but concave face had compression fails. 2) When bending with a clamp, bending time increased more than pedestal-steel and occurred tensile breaking. 3) Bending with a pedestal-steel and a clamp was found to be the most excellent operation method in this study.

• The Korean Journal of Food And Nutrition
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• v.16 no.4
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• pp.296-302
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• 2003

First. the purification and analysis of alliin in garlic from different origins by alliin-HPLC determination method were studied. Allinase in garlic was inactivated by heating in boiling water followed by extraction of alliin in garlic with 80% methanol. To remove free amino acids and alliin homologs in garlic, garlic extract was separated by cation exchange column which was packed with amberlite CG-120 resin using 40L d-water as eluent. Alliin in garlic extract was crystallized in a mixture of acetone (50$^{\circ}C$)：H$_2$O：acetic acid=70:29:1 and then recrystallized in a mixture of acetone (50$^{\circ}C$)：H$_2$O：acetic acid=75:24:1. Obtained alliin was identified by melting point. TLC, microscope observation and mass spectrometry. High performance liquid chromatography (HPLC) following pre-column derivatization of cystein derivatives with o-phthaldialdehyde/2-mercaptoethanol has succeessfully been applied to the analysis of various garlics. Each alliic of standard solution and garlic extract was derivatized to isoindole derivative by o-phthaldialdehyde /2-mercaptoethanol and then analyzed by HPLC. Six point calibration was done by using alliin peak area. Lineality was observed at 0 ∼ 1.0mg/ml of alliin concentration. Weighted regression line function was Y=6254X - 256077. By this function, alliin contents in various garlics were 0.34 ∼ 0.73% fresh weight. Second study was designed to evaluate the effects of garlic extracts of various concentrations on the growth of various pathogenes (Eubacterium limonsum, Bacteroides fragilis, Salmonella typhimurium, Salmonella typhi, Shigella sonnei, Kiebsiella pneumoniae, Enterobacter cloacae, Pserdomonas aeruginosa, Escherichia coli). For antimicrobial effects against microorganism, totally minimal inhibition concentrations (MIC) of alliin were from 5,000 to 20,000ppm. MIC of ethanol extract were 1,250 to 10,000ppm.

• Journal of the Korean Society of Food Science and Nutrition
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• v.8 no.1
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• pp.31-36
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• 1979

As a preliminary study to estimate the amount of daily calcium intake of Korean people, the present study was conducted investigating the kinds and amount of food among ordinary Korean food considered to be sources of calcium. The author sampled arbitrarily a total of 165 apartment households in Pusan City which were distributed in seven administration sections. Duration of this study was eight months, from June, 1975 to February, 1976. During summer vacation in this period twenty trained students visited these households where they measured the calcium source food at dinner, and three times this amount was regarded as the total daily intake. Also questionairs itemizing the various kinds of food which were considered to be sources of calcium were given to housewives and collected about two months later. The results are summarized as follows: The major sources of calcium food were milk and anchovy, and the total calcium content taken daily was an average 195.06 mg which was far smaller than the recommended standard. Cooking methods varied according to the kinds of food; for anchovy, the boiled water extract or the part remaining after removing bone and head was used, and for chopped cattle bone, the broth from boiling foe 5 to 6 hours was used. For boiled water extract, during extraction the amount of calcium was increased in the water but smaller than foe fresh anchovy. It is, therefore, desirable to cook and eat edible fish bone instead of discarding it after extraction. The amount of calcium of shrimp and whitebait consumed was considerably less than that of milk or anchovy. Most housewives, about 71%, discarded fish bones which contained a lot of calium before or after cooking them. So, it was considered necessary to find a good method of preparing fish so that it can be eaten palatably together with the bones.

• Journal of the Korean Institute of Gas
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• v.7 no.1 s.18
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• pp.19-23
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• 2003

The purpose of this thesis is to investigate the BLEVE probability of LP gas storage tanks which are relatively more dangerous, by the deductive calculating method using the results of Birk's pilot tank test and the required heat capacity of BLEVE. The result that BLEVEs can occur in only above 43.68 percent of liquid filling level under $600^{\circ}C$ of tank pate temperature and $53^{\circ}C$ of inner liquid temperature, was obtained and will be useful for preventing the BLEVE of LP gas storage tanks in fire sites. In addition, this research showed conditions of external leak and fire causing BLEVE, based on 15ton capacity of LP gas tank which has the same specifications as those in Puchon LP gas filling station accident. The result of the calculation is that the minimum pool fire conditions of BLEVE are above 7.2mm equivalent diameter under a liquid release condition and above 17.6mm equivalent diameter under a two-phase release condition. In the end, the result of calculating the pool size corresponding the above conditions using EFFECTS version 2.1, concludes that a minimum of 3.3 meters of diameter and 10.4 meters of height should be needed for BLEVE outbreak.

• Journal of the Society of Disaster Information
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• v.15 no.4
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• pp.634-647
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• 2019

Purpose: Currently, many chemicals are used in industrial and real life, and many substances are used in the form of a single substance, but most of them are used in the form of a mixture, and there is a need for a criterion for judging the danger of these substances. Method: Therefore, this study aims to confirm the risk criteria of the mixture through experimental studies on flammable mixtures in order to secure the effectiveness of the details of the existing Dangerous Goods Safety Management Act angerous Goods Judgment Criteria and to ensure the reliability and reproducibility of the dangerous goods judgment. Result: Experimental results show that alcohol flash point is mixed with water, which is a non-flammable liquid. Similar flash point trends occurred around 60% on an alcohol basis. In addition, in the case of flammable-combustible mixtures, there was little change in flash point if the flash point difference of the two materials was not large, and if the flash point difference of the two materials was low, the flash point tended to increase with the increase of the high flash point material. Conclusion: In the future, the test results may provide reference data on the experimental criteria for the flammable liquids that are cracked at the fire site.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.8 no.3
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• pp.181-188
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• 2010

Metal surface decontamination characteristics were investigated by using a laser ablation method. A second harmonic generation of a Q-switched Nd:YAG laser with a wave length of 532 nm, a pulse energy of 150 mJ and a pulse width of 5 ns was employed to assess the decontamination performance for metal surfaces contaminated with $CsNO_3$, $Co(NH_4)_2(SO_4)_2$, $Eu_2O_3$ and $CeO_2$. The ablation behavior was investigated for the decontamination variables such as a number of laser shots, laser fluence and an irradiation angle. Their optimum values were found to be 8, 13.3 J/$cm^2$ and $30^{\circ}$, respectively. The decontamination efficiency was different depending on the kinds of the contaminated ions, due to their different melting and boiling points and was in the order: $CsNO_3>Co(NH_4)_2(SO_4)_2>Eu_2O_3>CeO_2$. We also evaluated a correlation between the metal ablation thickness and the number of laser shots for the different laser fluences.

• Journal of the Korean Institute of Gas
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• v.24 no.1
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• pp.17-22
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• 2020

Light Naphtha is distillated from crude oil unit and separated into the methane, ethylene and propylene by boiling point difference in sequence. This separation is conducted using a series of binary-like columns. This separation method is known that the energy consumed in the reboiler is used to separate the heaviest components and most of this energy is discarded as vapor condensation in the overhead cooler. In this study, the first two columns of the separation process are replaced with the Petlyuk column. A structural design was exercised by the stage computation with ideal tray efficiency in equilibrium condition. Compared with the performance of a conventional system of 3-column model, The design outcome shows that the procedure is simple and efficient because the composition of the liquid component in the column tray was designed to be similar to the equilibrium distillation curve. The performance of the new process indicates that an energy saving of 12.1% is obtained and the cost savings of 44 million won per day based on gross domestic product is reduced under same total number of trays and the initial investment cost is saved.

• Nuclear Engineering and Technology
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• v.27 no.4
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• pp.562-570
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• 1995

The recent ABB/CE(Asea Brown Boveri Combustion Engineering) type pressurized oater reactor-s have the on-line monitoring system, i.e., the COLSS(core operating limit supervisory system), to prevent the specified acceptable fuel design limits from being violated during normal operation and anticipated operational occurrences. One of the main functions of COLSS is the on-line monitoring of the DNB(departure from nucleate boiling) overpower margin by calculating the MDNBR(mini-mum DNB ratio) for the measured operating condition at every second. The CETOP-D model, used in the MDNBR calculation of COLSS, is benchmarked conservatively against the TORC mod-el using an inlet flow factor of hot assembly in CETOP-D as an adjustment factor for TORC. In this study, a technique to optimize the CETOP-D inlet flow factor has been developed by elim-inating the excessive conservatism in the ABB/CE's. A correlation is introduced to account for the actual variation of the CETOP-D inlet flow factor within the core operating limits. This technique was applied to the core operating range of the YongGwang Units 3&4 Cycle 1, which results in the increase of 2％ in the DNB overpower margin at the normal operating condition, compared with that from the ABB/CE method.