• Journal of Conservation Science
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• v.36 no.6
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• pp.562-577
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• 2020

In this study, to conserve the clay seated Vairocana Buddha triad in Seonunsa temple, Gochang (Treasure 1752), the primary materials employed for creating the clay Buddha statues were scientifically analyzed. By analyzing the soil layer constituting the Buddha statues, it is observed that the said layer comprises sand having particle size greater than that of medium sand and soil having particle size smaller than that of fine sand, which were used in a ratio of 7:3, along with the bast fibers of paper mulberry (Broussonetia kazinoki). Hence, the aforementioned soil layer is composed of a mixture of sand and weathered soil, along with bast fibers to prevent scattering. By analyzing the tree species, it is found that the wooden materials constituting the bottom board and the interior of Buddha's sleeves of the Amitabha Buddha statue, Vairocana Buddha statue, and Medicine Buddha statue are hard pines (Pinus spp.). Additionally, three layers are found in the cross section of the gold layer. Furthermore, each of the hair sections of the Buddha statues is composed of earthy materials such as quartz, albite, microcline, mica, and magnetite, and the hair surface was painted by incorporating black materials containing magnetite.

• Journal of the Korean Applied Science and Technology
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• v.35 no.4
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• pp.1260-1268
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• 2018

To improve fuel performance and specific characteristics of long storage and moving through fuel systems additives should be added in kerosene type aviation turbine fuel (AVTUR) such as antioxidant, fuel system icing inhibitor (FSII), electric conductivity improvers and so on. The dosage of additives has to be analyzed qualitatively and quantitatively due to inspect the quality of abnormal fuel and distinguish other petroleum products. Multi-dimensional GC-MS (MDGC-MS) with Deans switching technique are applied the determination of antioxidant and FSII, which are added with AVTUR containing complex mixture of hydrocarbons. Antioxidant and FSII in the range of 2.5-20 mg/L was quantitatively and qualitatively analyzed using MDGC-MS and the detection limit was about twice as low as that of the 1-dimensional GC-MS results. The method in this study has been higher peak resolution compared with GC-MS and could be simultaneously analyzed different two additives without sample pre-treatment.

• 한국노년학
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• v.37 no.1
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• pp.15-32
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• 2017

The current study aims to identify the heterogeneous changes of functional disabilities in old age rather than to identify an average longitudinal pattern and to explore the effect of health status and social status as risk factors in functional disability trajectories. The sample consisted of a representative sample of community dwellers aged 65 and older from the Korean Longitudinal Study of Ageing (2006 - 2012) was the focus of the study. Latent Class Growth Analysis was used to identify the functional disability trajectory groups. Variables regarding health status and social status changes by class were identified using multinomial logistic regression. The results showed various change patterns in functional disability, which include independent (78%), stable high (4.4%), steeply increasing (7.1%), slightly increasing (5.5%), and moderate to low (4.7%). Aggravation in depressive symptoms and cognitive functions as well as decline in social participations and social engagements were significant predictors of membership in increasing group of functional disability. The findings provide important initial empirical information to target clinical practice and have implications in the importance of conducting research on groups with different characteristics.

• Journal of the Korean Applied Science and Technology
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• v.36 no.2
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• pp.572-580
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• 2019

Recently, it has been reported that benzyl alcohol (BzOH) as an additive in cosmetics, food, and medicine lead to toxicity and allergy problem. Then, to circumvent this hurdle, we carried out the synthesis of benzyl alcohol galactoside (BzO-gal). Previously, it was confirmed that BzO-gal was synthesized by transgalactosylation reaction using Escherichia coli (E. coli) ${\beta}$-galactosidase (${\beta}-gal$). Meanwhile, in this study, two peaks of BzO-gal as sodium adduct ion (m/z=293.1004) and protonated ion (m/z=271.1180) were detected in the reaction mixture by liquid chromatography/electrospray ionization mass spectrometry (LC/ESI-MS). In addition, the amount of ${\beta}-gal$ and BzOH concentration, temperature, pH, and lactose concentration, respectively, were optimized (${\beta}-gal$, 0.75 U/mL; BzOH, 185 mM; temperature, $40^{\circ}C$, pH, 7.5; lactose, 350 g/l). Under these optimal conditions, 185 mM BzOH was converted into about 131 mM BzO-gal, in which the conversion yield was about 72%. In the future, BzO-gal will be applicable as a substitute for BzOH as a less toxic preservative for the cosmetic, pharmaceutical, and food industries, and we are planning to investigate the characteristics of BzO-gal as a preservative.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.2
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• pp.1-9
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• 2019

GGBFS(Ground Granulated Blast Furnace Slag), one of the representative concrete mineral admixtures, improves the long-term durability and engineering performance of concrete by latent hydraulic activity. In this study, considering 3 levels of W/B(0.37, 0.42, 0.47) and GGBFS replacement ratio(0 %, 30 %, 50 %), durability performances for chloride attack are evaluated, and equations which predict behavior of accelerated chloride diffusion are proposed. Also, the relationship between accelerated chloride diffusion coefficient and passed charge is evaluated. In target curing day, accelerated chloride diffusion tests(Tang's method, ASTM C 1202) and compressive strength(KS F 2405) are performed. In the 730 day's results of accelerated chloride diffusion coefficient, GGBFS concrete has up to 28 % of decreasing ratio compared to OPC concrete, and in those of passed charge, GGBFS concrete has up to 29 % of decreasing ratio compared to OPC concrete. Also, it is deemed that the impact of variation of W/B is less in GGBFS concrete than in OPC concrete. The equations which predict accelerated chloride diffusion coefficient and passed charge are drawn, based on the characteristics of mixture and test results. The equation which predicts passed charge shows slightly higher coefficient of determination than that which predicts accelerated chloride diffusion coefficient.

• Korean Journal of Heritage: History & Science
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• v.52 no.3
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• pp.240-251
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• 2019

This study examined the manufacturing technology used for the flat iron axes excavated from Ulsan Hadae. Their microstructures were analyzed using metallurgical methods. In addition, a variety of manufacturing technologies were examined and compared using existing research materials on flat iron axes. As a result of analyzing ten flat iron axes, which were excavated in the order that they were laid out in a row in one of the wooden coffin tombs at Ulsan Hadae, Tomb No. 44, it was possible to classify the flat iron axe manufacturing technology and system into three types: 'pure iron - shape processing', 'pure iron - shape processing - carburizing', and 'pure iron - shape processing - carburizing - decarburizing.' All of the flat iron axes were produced by forging, and most of them were made by beating the pure iron into their shapes. In particular, a number of the flat iron axes were reinforced through a carburizing process after shaping the iron. This appears as steel products forming the basis of the steel industry at the time were commonly used as an intermediary material or currency. On the other hand, it was commonly found in all samples that the hardening was not performed after shaping or carburizing. Since the microstructure of the flat iron axes made of pure iron contained a large number of impure inclusions and the result of analyzing the components of the non-metal inclusions showed characteristics of slag which contains a mixture of glass phase and wustite, it is possible that low-temperature reduction was used in the refining process.

• Journal of Medicine and Life Science
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• v.15 no.2
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• pp.95-100
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• 2018

We conduct this study to compare the difference in duration of labor in nulliparous women received epidural analgesia or non-epidural analgesia for labor pain. This retrospective, observational study based on the review of the medical records from February 2014 to July 2017. Epidural analgesia was initiated with a 10 mL epidural bolus of 1% lidocaine and was maintained with a 0.1% mixture of ropivacaine with fentanyl. Non-epidural analgesia was initiated with pethidine 12.5 mg bolus, followed by additional boluses as needed. The primary outcome was the duration of the labor. 149 healthy nulliparous women at term pregnancies with no evidence of fetal distress were enrolled in this study. 92 women received non-epidural analgesia (Group NE) and 57 women received epidural analgesia (Group E). There were no significant differences between the two groups in maternal demographic characteristics. Using a Kaplan-Meier survival analysis, there was no significant difference in the overall duration of the labor(P=0.233). The duration of the first stage of labor was $187.6{\pm}167.3min$ in Group NE, $248.6{\pm}168.7min$ in Group E (Mean${\pm}$SD, P=0.032). The duration of the second stage of labor was $67.1{\pm}57.8min$ in Group NE, $64.1{\pm}47.5min$ in Group E (Mean${\pm}$SD, P=0.693). Epidural analgesia delayed the first stage of labor in this study. But there were no significant differences between the two groups in the duration of the second stage and the total duration of labor.

• Korean Journal of Food Science and Technology
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• v.51 no.2
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• pp.97-102
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• 2019

Wheat germ, which is rich in nutrients and phytochemicals, is a by-product during the milling process of wheat kernel. In this study, we aimed to increase the amount of bioactive 2,6-dimethoxy-1,4-benzoquinone (2,6-DMBQ) in wheat germ using the cell-wall-degrading enzyme cellulase (Celluclast 1.5L). The amounts of organic acids, free sugars, and 2,6-DMBQ in wheat germ treated with Celluclast 1.5L were evaluated at various reaction times and temperatures. The results of reversed-phase high-performance liquid chromatography of Celluclast 1.5L-treated wheat germ revealed 2,6-DMBQ, four organic acids (tartaric, acetic, lactic, and succinic acids), and three free sugars (sucrose, fructose, and glucose). As reaction time and temperature of the mixture of wheat germ and Celluclast 1.5L increased, the contents of four organic acids, glucose, fructose, and 2,6-DMBQ increased, but that of sucrose decreased. Taken together, these results suggest that Celluclast 1.5L-treated wheat germ containing increased amounts of 2,6-DMBQ serves as a source of functional ingredients in food industry.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.4
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• pp.503-509
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• 2019

The demand for smaller, faster, and multi-functional mobile devices in increasing at a rapidly increasing rate. In response to these trends, Stacked Chip Scale Package (SCSP) is used widely in the assembly industry. A film type adhesive called die attach film (DAF) is used widely for bonding chips in SCSP. The DAF requires high flowability at high die attachment temperatures for bonding chips on organic substrates, where the DAF needs to feel the gap depth, or for bonding the same sized dies, where the DAF needs to penetrate bonding wires. In this study, the mixture design of experiment (DOE) was performed for three raw materials to obtain the optimized DAF recipe for low elastic modulus at high temperature. Three components are acrylic polymer (SG-P3) and two solid epoxy resins (YD011 and YDCN500-1P) with different softening points. According to the DOE results, the elastic modulus at high temperature was influenced greatly by SG-P3. The elastic modulus at $100^{\circ}C$ decreased from 1.0 MPa to 0.2 MPa as the amount of SG-P3 was decreased by 20%. In contrast, the elastic modulus at room temperature was dominated by YD011, an epoxy with a higher softening point. The optimized DAF recipe showed approximately 98.4% pickup performance when a UV dicing tape was used. A DAF crack that occurred in curing was effectively suppressed through optimization of the cure accelerator amount and two-step cure schedule. The imizadole type accelerator showed better performance than the amine type accelerator.

• Journal of the Korean Society for Environmental Technology
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• v.19 no.6
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• pp.493-502
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• 2018

The purpose of this study was to develop EM media for water treatment and to remove nitrogen and phosphorus which cause water algae boom in water system. The ideal mixing ratio of raw material such as clay: zeolite: vermiculite: activated carbon for manufacturing the EM media was 10: 2.5: 0.1: 2, and the calcination temperature was $700^{\circ}C$. The comparison of the physical properties of manufactures using distilled water and EM activated liquid as the material mixture are as follows. Porosity and density of EM media were 39.98 % and $1.13kg/m^3$, adsorption efficiencies of nitrogen and phosphorus were 69.3 % and 38.9 %. In contrast, porosity and density of distilled water media were 37.80 % and $1.11kg/m^3$, and adsorption efficiencies of nitrogen and phosphorus were 62.5 % and 37.8 %. The adsorption rate of nitrogen and phosphorus in the EM media was higher than that of the distilled water made one by 6.8 % and 1.1 %, respectively. The adsorption characteristics of the media to nitrogen and phosphorus could be expressed by the Freudlich adsorption isotherm. The change of calcination time did not affect the adsorption efficiency of phosphorus and nitrogen when EM media was formed, but it was considered that it affects the strength of media. Nitrogen removal efficiency was the best record in 4 hours of calcination time and 3 hours of calcination time in phosphorus removal efficiency.