• Food Science and Preservation
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• v.19 no.5
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• pp.727-734
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• 2012

For developing calcium supplement from the harmful marine organism starfish, the physiochemical property of the powdered starfish skeletal plate and the hydrolysis condition of the starfish digestive enzyme were studied. The optimal hydrolysis condition of the starfish digestive enzymes was at $55^{\circ}C$ for 12 h. The bulk densities of the powdered starfish skeletal plates of Asterias amurensis and Asterina pectinifera were $1.1{\pm}0.0$ and $1.2{\pm}0.0g/cm^3$, respectively. As for the median size, the values were 10.738 and $11.799{\mu}m$, respectively. According to the added concentration of sodium polyacrylate, the dispersibility rate of the powdered starfish skeletal plate was shown to be 6h at 0.0%, 3 days at 0.1%, 20 days at 0.2%, and until 30 days at 0.4%. The elementary composition of the powdered starfish skeletal plates from A. amurensis and A. pectinifera mainly consisted of calcium, and it formed 98.95 and 98.52% of the powdered starfish skeletal plates, respectively. The results of the X-ray diffraction (XRD) analysis showed that they were present in the form of $CaCO_3$. Based on these results, it is suggested that starfish skeletal plate can be utilized as a functional material for a calcium supplement.

• Journal of the Korean Magnetics Society
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• v.21 no.6
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• pp.219-224
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• 2011

The motion features of sanals inside of the primo vascular system (PVS), that is so-called the Kyungrak system, are investigated under a low static magnetic field by using the anatomy technology and optical microscope. The sanals with a size of about 1 selected and separated from the primo vessel and node of the real PVS inside of the surface of the internal organs are observed from rabbits' abdominal wall and dipped with PBS liquid inside of petri dish. The sanal's moving velocity along the direction of magnetic field (xdirection) and perpendicular to the direction of magnetic field (y-direction) under the low magnetic field of 0 Oe, 20 Oe, 40 Oe, 60 Oe, and 80 Oe, respectively, is observed below a internal temperature of $38^{\circ}C$. Ten sanals' moving velocities versus magnetic field are shown two differently dominant tendencies with an average velocity of 0.9 pixel/s and a random velocity according to the x-direction and y-direction, respectively. This experimental results imply that the rotating motion of sanal with nuclei DNA composed of many inorganic magnetic materials of Mn and Co is monotonically weakened by the increase of applied magnetic field.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.6
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• pp.963-969
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• 2011

The river-bed sediments from the major river basins were analysed for the chemical and physical properties to evaluate environmental safety for the agricultural uses. The samples were taken from 16 sites of Han river, 36 of Geumgang river, 27 of Yeongsan river, and 140 of Nakdong river. The total of 219 samples from the 28 counties were taken from the surface of the sediments at the depth of 50 cm. The particle density of the sediments was greater than $2.63Mg\;m^{-3}$ and the whole range of the density was $2.60{\sim}2.69Mg\;m^{-3}$, the average particle size was 0.7 mm whereas the size range was 0.075~0.85 mm. The analyses of the particle sizes by basins showed that Han and Geumgang river had particle sizes of 0.075~0.85 mm, while Geumgang and Yeongsan river had particle sizes of 0.25~0.85 mm. Geumgang and Yeongsan river tended to have greater particle sizes. The average values of the chemical properties were 6.3 for pH, $0.16dS\;m^{-1}$ for EC, $8g\;kg^{-1}$ for organic matter, $101mg\;kg^{-1}$ for available phosphate, 0.39, 3.47, and $0.93cmol_c\;kg^{-1}$ for exchangeable potassium, calcium, and magnesium respectively. The greatest property at each basin was pH for Han river, Ec, available phosphate and exchangeable sodium for Geumgang river, organic matter, exchangeable calcium and magnesium for Yeongsan river, and exchangeable potassium for Nakdong river.

• Journal of the Mineralogical Society of Korea
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• v.17 no.3
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• pp.277-288
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• 2004

Alkali-silica reaction (ASR) is a chemical reaction between alkalies in cement and chemically unstable aggregates and causes expansion and cracking of concrete. In the Present study, we studied the effects of metakaolin, which is a newly introduced mineral admixture showing excellent pozzolainc reaction property, on the inhibition of ASR. We prepared mortar-bars of various replacement ratios of metakaolin and conducted alkali-silica reactivity test (ASTM C 1260), compressive strength test and flow test. We also carefully analyzed the mineralogical changes in hydrate cement paste by XRD qualitative analysis. The admixing of metakaolin caused quick pozzolanic reaction and hydration reaction that resulted in a rapid decrease in portlandite content of hydrated cement paste. The expansion by ASR was reduced effectively as metakaolin replaced cement greater than 15%. This resulted in that the amounts of available portlandite decreased to less than 10% in cement paste. It is considered that the inhibition of ASR expansion by admixing of metakaolin was resulted by the combined processes that the formation of deleterious alkali-calcium-silicate gel was inhibited and the penetration of alkali solution into concrete was retarded due to the formation of denser, more homogeneous cement paste caused by pozzolanic effect. Higher early strength (7 days) than normal concrete was developed when the replacement ratios of metakaolin were greater than 15%. And also, late strength (28 days) was far higher than normal concrete for the all the replacement ratios of metakaolin. The development patterns of mechanical strength for metakaolin admixed concretes reflect the rapid pozzolanic reaction and hydration properties of metakaolin.

• Polymer(Korea)
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• v.30 no.1
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• pp.64-69
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• 2006

A series of dinuclear half-sandwich titanium complexes with aryloxy substituent at titanium$[(\eta^5-cyclopentadienyl)(aryloxy)TiCl_2]_2[(CH_2)_n]$ (n=3, n=6, n=9) have been successfully synthesized and their styrene polymerization properties have been investigated. All complexes are characterized by $^1H\;NMR,\;^{13}C\;NMR$, elemental analysis, and mass spectrometry. In order to examine the catalytic properties of the dinuclear complexes styrene polymerization has beer conducted in the presence of MMAO. It was found that (i) all the prepared complexes were very effective catalyst for the production of SPS (syndiotactic polystyrene), (ii) the complex with the longest bridge between the two active sites exhibited greatest catalytic activity among the three catalysts, but produced SPS with the smallest molecular weight, (iii) the activities of dinuclear half-titanocens with aryloxy substitution at titanium metal were greater than those of the chloride substituted compounds. These results indicate that not only the nature of the bridge between the two active sites but also the property of substituents at the metal exert a significant influence on the polymerization behaviors of the dinuclear half-titanocene.

• Food Science and Preservation
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• v.19 no.2
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• pp.178-184
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• 2012

The physiochemical property, nutrient composition, and functionality of apple juice sterilized at a low temperature (LT, $70^{\circ}C$, 30 min) or a high temperature (HT, $100^{\circ}C$, 20 min) were analyzed. The pH of the apple juice that was sterilized at LT (pH 4.72) was higher than that of the apple juice that was sterilized at HT (pH 4.57), and the acidity of the apple juice that was sterilized at HT (8.90%) was higher than that of the other sample. The sugar content of the two apple juice samples was 15 $^{\circ}Brix$, and the apple juice samples had high potassium, malic acid, and glutamic acid contents. The total polyphenol contents of the apple juice samples that were sterilized at LT and HT were 27.39 mg/100 mL and 23.24 mg/100 mL, respectively. The apple juice that was sterilized at LT had a significantly stronger DPPH radical scavenging activity than the apple juice that was sterilized at HT ($p$ <0.01), and the apple juice that was sterilized at LT had a lower hydroxyl radical scavenging activity level than the other apple juice. Finally, the apple juice that was sterilized at LT showed significantly stronger activities that inhibit enzyme-related oxidation than the apple juice that was sterilized at HT ($p$ <0.05).

• Journal of the Korea Institute of Building Construction
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• v.15 no.1
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• pp.25-33
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• 2015

In this study, initial crack index was evaluated by FEM analysis to find the crack propagation from hydration heat in precast concrete. As results, as the usage of hardening accelerator increased, initial compressive strength increased and setting time was shortened. Additionally, as amounts of hardening accelerators increased, the central temperature of concrete increased and the time to reach the highest temperature was shortened. It was demonstrated that the hardening accelerators accelerated the hydration reaction of cement, and caused the increase of hydration heat within the short period of time. Furthermore, the crack index for evaluating the heat level was performed by FEM. As results, there was no problem about the cracks, despite of the growth of initial high hydration heat. This is because of the increased tensile strength that is large enough to sustain the thermally induced-stress.

• Journal of the Korean Institute of Gas
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• v.5 no.2 s.14
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• pp.22-29
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• 2001

The number of gas containers and the period of exchanging gas containers are vsy important in designing liquefied petroleum gas(LPG) supply system for small capacity domain. And also the evaluation of remaining LPG in containers to be exchanged is very useful information in commerce. However seldon has been studied on calculating method about those with respect to gas consumption pattern. In this study, a simulation method was developed to estimate the evaporation capacity of LPG container, the mass gas flow rate from LPG container, the temperature and vapor pressure of LPG, and the remained LPG at containers to be exchange by using LPG property equations, mass balance equation, and heat balance equation. The simulation results were correlated well with experimental data. The overall heat transfer coefficient from air to LPG is approximately $9{\~}13 kcal/m^2{\cdot}hr{\cdot}^{\circ}C$ and does not strongly affect on the evaporation capacity of LPG container. The mass gas flow rate from LPG container is constant when the vapor pressure of LPG is within pressure regulator's control range. While, out of range, it suddenly reduce to a evaporation rate which is balanced with heat transfer from air. The evaporation capacity of LPG container increased with surrounding temperature and the composition of propane, and decreased drastically with continuous gas consumption. The number of gas containers divided the number of houses using gas supply system was reduced by using automatic gas feeding device.

• Korean Journal of Heritage: History & Science
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• v.48 no.2
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• pp.4-29
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• 2015

This article considered generally gradational change aspect, character of community for the tombs of the Three kingdoms prepared by some certain homogenous groups. It was completed by tracing the transfering process to grasp character of social structure and organizing System in the community. For this reason, it's analyzed that Wooden chamber tomb was formed in some certain Time-Space of the Yaksadong Buk-dong archaeological site in the Three Kingdom Period. Constructed group was distinguished by the five classes. So perhaps scale of Wooden chamber and sort, material of burial relics, the top layer and the upper layer were established two status those are active the ruling class led the Wooden chamber tomb's society, the general public hold a large majority from the middle class to the lowest class. And it depends on age(nonage-adult) that differed in relation of arrangement, character. It's changed with function or roles, property, purpose etc. of social community in accordance with these individual position, age. Received signification, value of social status were considered with social worth, faith. Members in a community had been conducted under premeditated, organised system for common target, relatedness. Also it seems to attempt organization's own maintenance, persistiveness in norms that given at common law. To do that, relation for combination between members who consisted systems had to be organic. The relation for combination was considered to form relation for the much larger community in based on blood relationship that most vital part. One social structure had established family(house, household) community in based on individual blood relationship, family communities gather up to develop into relative(blood relative, same race) community gradually. Furthermore, relative(blood relative, same race) communities, that focus on the public good gather up to develop into social community in based on regionalism. It's considered to go through the Development Process of family(house, household) community - relative(blood relative, same race) community - social community.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.6C
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• pp.367-377
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• 2008

As part of study to develop LRFD (Load and Resistance Factor Design) codes for foundation structures in Korea, resistance factors for static bearing capacity of driven steel pipe piles were calibrated in the framework of reliability theory. The 57 data sets of static load tests and soil property tests conducted in the whole domestic area were collected and these load test piles were sorted into two cases: SPT N at pile tip less than 50, SPT N at pile tip equal to or more than 50. The static bearing capacity formula and the Meyerhof method using N values were applied to calculate the expected design bearing capacities of the piles. The resistance bias factors were evaluated for the two static design methods by comparing the representative measured bearing capacities with the expected design values. Reliability analysis was performed by two types of advanced methods: the First Order Reliability Method (FORM), and the Monte Carlo Simulation (MCS) method using resistance bias factor statistics. The target reliability indices are selected as 2.0 and 2.33 for group pile case and 2.5 for single pile case, in consideration of the reliability level of the current design practice, redundancy of pile group, acceptable risk level, construction quality control, and significance of individual structure. Resistance factors of driven steel pipe piles were recommended based on the results derived from the First Order Reliability Method and the Monte Carlo Simulation method.