• KSCE Journal of Civil and Environmental Engineering Research
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• v.42 no.2
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• pp.197-208
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• 2022

The existence of shallow bedrock and the desire to use underground space necessitate the use of blasting methods. The standard blasting method under water after drilling is associated with certain technical difficulties, including reduced detonation power, the use of a fixed charge per delay, and decoupling. However, there is no blasting method to replace the existing blasting method. In this paper, a dry hole charged with ANFO blasting is assessed while employing a dry hole pumping system to remove water from the drill borehole. Additional standard blasting is also utilized to compare the blasting performances of the two methods. The least-squares linear regression method is adopted to analyze the blasting vibration velocity quantitatively using the measured vibration velocity for each blasting method and the vibration velocity model as a function of the scaled distance. The results show that the dry hole charged with ANFO blasting will lead to greater damping of the blasting vibration, more energy dissipation to crush the surrounding rock, and closer distances for the allowable velocity of the blasting vibration. Also, standard blasting shows much longer influencing distances and a wider range of the blasting pattern. The pilot test confirms the blasting efficiency of dry hole charged with ANFO blasting.

• Elastomers and Composites
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• v.37 no.4
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• pp.224-233
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• 2002

This study has investigated the flame retardant properties of EPDM rubber with the addition of various flame retardants. Carbon black, stearic acid, zinc oxide cross-linking agent were mixed with EPDM rubber to produce the base rubber E0 without the addition of flame retardants. Phosphorus flame retardant Tricrecyl phosphate(TCP) was added to E0 in 0.5, 1, 1.5, 2 phr to make E1~E4 samples and red phosphorus was added in 3, 6, 9, 12 phr to make E5~E8 samples. A flame retardant of the bromine family Decabromodiphenyloxide(DBDPO), and a chlorinated paraffin retardant of the chlorine family was added to E0 in 3, 6, 9, 12 phr to make E9~E12 and E13~E16 samples, repectively. Basic physical properties such as tensile strength, tear strength and hardness were measured for all the rubber samples with various flame retardant additions. There was no substantial differences. On the other hand, Oxygen index and UL94 were measured to study flame retardant properties. From oxygen index measurements E0 sample showed a value of 23.5%, indicating the improvement of flame retardant properties. Also from UL94 measurements, it was found that addition of red phosphorus resulted in maximum flame retardant effect. It was found that increasing the amount of addition resulted in decreasing combustion rate and improving flame retardant effect regardless of the kind of flame retardant.

• Analytical Science and Technology
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• v.19 no.2
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• pp.142-148
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• 2006

To determine malachite green and leuco-malachite green residues in sea food, a liquid chromatographic method has been optimized. The target compounds were extracted in the homogenized edible tissues with a mixture of McIlvaine buffer-acetonitrile and partitioned against dichloromethane. After concentrating the lower layer, the resulting residues were re-dissolved in methanol and analyzed by the HPLC with visible detector at 620 nm using acetonitrile-acetate buffer. For the analysis of leuco-malachite green with malachite green simultaneously, post-column packed with lead(IV) oxide was used for oxidizing leuco-malachite green to malachite green. The correlation coefficients($r^2$) was 0.9989 for malachite green, and 0.9995 for leuco-malachite green. The limit of detection was 0.005 mg/kg for the combined of malachite green and leuco-malachite green at signal/noise${\geq}3$. The recovery rate was within a reliable range of 84~98% (CV 3~16%). Leuco-malachite green were detected in carp and crusian carp.

• Analytical Science and Technology
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• v.19 no.3
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• pp.239-243
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• 2006

This method is used for the determination of itraconazole in human plasma by liquid-liquid extraction and high performance liquid chromatography. Felodipine was used as an internal standard. After extraction of the plasma with diethyl ether, the centrifuged upper layer was then transferred. The supernantant was evaporated and then reconsituted with mobile phase. The mobile phase was composed of 10 mM ammonium acetate adjusted to pH 7 by phosphoric acid with a flow rate of 0.2 mL/min. A C18 reversed-phase column with a pre-column was used as the analytial column. Linear detection responses were obtained for itraconzole concentration range for 2~1,000 ng/mL. The correlation coefficient of linear regression($R^2$) was 0.9991, limit of quantification (LOQ) was 2 ng/mL, reproducibility was less than 10.8 %, and accuracy was 97.2~108.2%. This method has been successfully applied to the pharmacokinetic study of itraconazole in human plasma.

• Analytical Science and Technology
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• v.21 no.6
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• pp.543-552
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• 2008

This paper described the relatively sensitive and simultaneous analytical method for 3-monochloropropane-1,2-diol (3-MCDP, $C_3H_7ClO_2$, MW. 110) as well as 1,3-dichloropropan-2-ol (1,3-DCP, $C_3H_6Cl_2O$, MW. 128) in various foods. Food samples were homogenized in 5M NaCl solution, mixed with aluminum oxide and eluted with dichloromethane. The extracted chloropropanols were concentrated by rotary evaporator and $N_2$ blow serially were derivatized with HFBA (Heptafluorobutyric anhydride, $C_8F_{14}O_3$, MW. 410) and were determined by GC/MS using isotope dilution method. The characteristic molecular ions at m/z 253, 275, 289, 291, and 453 for HFBA derivatives of 3-MCPD (MW. 502) and 110, 275, and 277 for HFBA derivatives of 1,3-DCP (MW. 325) were chosen in selected ion mode. The method validation data showed sufficiently good properties of LOD (0.003 mg/kg), LOQ (0.010 mg/kg), linearity ($R^2{\geq}0.999$ at 0.010~1.000 mg/kg), and recovery rate (${\approx}97%$). The levels of chloropropanols in soy sauce, sauces, processed meat products, fishery products, and seasonings (n=56/157) determined by the presented method were 0.0~0.3 mg/kg.

• Analytical Science and Technology
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• v.22 no.3
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• pp.219-227
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• 2009

The steroid compounds in Rhodiola sachalinensis were determined with adsorption column chromatographic purification and GC/MS. Sterols were extracted by sonication and Soxhlet with ethanol and dichloromethane, respectively. The extract was partitioned with chloroform and water using liquid-liquid extraction, and purified with a silica column after the sterols had been converted to the corresponding silyl derivatives with BSTFA. Eighteen free sterols, including $\beta$-sitosterol, stigmasterol and cycloartenol, and nine sterol conjugates were found from Rhodiola sachalinensis by GC/MS. Among them, cholest-5-ene-3-ol, cholesterol, stigmasterol, $\beta$-sitosterol were confirmed and quantified with sterol standards. Most sterols were presented in the chloroform part, with $C_{29}$ being the most abundant group in this sterol group. $\beta$-sitosterol was the most abundant compound with a relative content of 45.94% followed by ergost-7-ene-3-ol (11.33%), 4,14-dimethyl-ergosta-8,24(28)-diene-3-ol (7.07%), stigmasterol (6.09%), cycloartenol (5.43%) and 4-methyl-cholest-5-ene-3-ol (5.39%).

• Analytical Science and Technology
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• v.21 no.3
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• pp.191-200
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• 2008

Pharmaceuticals and personal care products (PPCPs) are emerging contaminants in aquatic environmental samples. Therefore, it required rapidly and certainly analytical method for pharmaceuticals which are existed in environment. In this study, Liquid chromatography/tandem mass spectrometry (LC-MS/MS) with electrospray ionization (ESI) was used to measure the concentrations of 7 pharmaceuticals (quinoxaline-2-carboxylic acid, acetylsalicylic acid, diclofenac-Na, naproxen, ibuprofen, mefenamic acid, talniflumate) from environmental water or aquatic samples simultaneously. Effective sample clean-up by solid-phase extraction (SPE) prior to LC-MS/MS analysis is necessary. For further purification, Mixed Cation eXchange (MCX) and Hydrophilic-Lipophilic Balance (HLB) solid-phase extraction (SPE) cartridges were used to eliminate the remaining interferences. LODs (Limits of Detection) and MDLs (Method Detection Limits) for the spiked sample in fresh water were in the range of 0.05~1.50 pg/mL and 0.17~4.90 pg/mL, respectively. The absolute recovery in the concentration of 1.0 ng/mL were between 81.9 and 116.3%. The acidic pharmaceuticals were detected in concentrations of 0.018~16.925 ng/mL in aquatic environmental samples.

• Korean Journal of Psychosomatic Medicine
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• v.31 no.2
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• pp.50-62
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• 2023

Objectives : This study aimed to identify unmet needs and influencing factors for patients who have breast cancer, colorectal cancer, lung cancer, and thyroid cancer. Methods : We reviewed the SCIE publications on unmet need of four prevalent cancer patients published after 2010 through a web search. Results : The measurement tools primarily used were Cancer Survivors' Unmet Needs and Supportive Care Needs Survey questionnaire. Lung cancer patients reported a relatively higher rate of unmet needs. Breast cancer patients frequently reported unmet needs in the healthcare system and information, while thyroid cancer patients in post-treatment management and psychological issues. Colorectal cancer patients reported unmet needs in psychological and comprehensive care domain, and lung cancer patients reported unmet needs in physical and daily life management. Younger age, a shorter time since diagnosis or treatment, and higher levels of anxiety, depression, distress, and reduced quality of life were associated with more significant unmet needs. Conclusions : Unmet needs and influencing factors vary by cancer type. Considering the characteristics of each patient group and unmet needs can help in development of more effective treatment and support programs.

• The Journal of the Convergence on Culture Technology
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• v.9 no.5
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• pp.837-842
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• 2023

This study analyzed the awareness and actual condition on metaverse utilization in education for design major students. An online survey was conducted for 14 days from May 10 to 23, 2023, targeting 120 students majoring in design at D University. The evaluation method of the questionnaire was a nominal scale and a 5-point scale, and the questionnaire results were analyzed through SPSS 29.0. First, it is necessary to sufficiently share the advantages of metaverse utilization in education with students, and to provide basic literacy programs utilizing the characteristics of metaverse and supporting class activities. Second, students' response will be higher in studio classes where practical training is conducted rather than information delivery or understanding-oriented lectures. Third, in order for the metaverse to become a means of education in the digital transformation era rather than just a temporarily medium in COVID-19 era, specific and systematic design education programs reflecting the characteristics of the metaverse need to be continuously developed. In addition, it is important for instructors to actively review the use of the metaverse and search for various ways to utilize it.

• Journal of the Korean Institute of Gas
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• v.27 no.3
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• pp.123-133
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• 2023

Commercial hydrogen fuel cell vehicles are charged by compressing gaseous hydrogen to high pressure and storing it in a storage tank in the vehicle. This process causes the temperature of the gas to rise, to ensure the safety to storage tanks, the temperature is limited. Therefore, a heat transfer model is needed to explain this temperature rise. The heat transfer model includes the convective heat transfer phenomenon, and accurate estimation is required. In this study, the convective heat transfer coefficient in the hydrogen fueling process was calculated and compared using various correlation equations considering physical phenomena. The hydrogen fueling process was classified into the fueling line from the dispenser to the tank inlet and the storage tank in the vehicle, and the convective heat transfer coefficients were estimated according to process parameters such as mass flow rate, diameter, temperature and pressure. As a result, in the case of the inside of the filling line, the convective heat transfer coefficient was about 1000 times larger than that of the inside of the storage tank, and in the case of the outside of the filling line, the convective heat transfer coefficient was about 3 times larger than that of the outside of the storage tank. Finally, as a result of a comprehensive analysis of convective heat transfer coefficients in each process, it was found that outside the storage tank was lowest in the entire hydrogen fueling process, thus dominated the heat transfer phenomenon.