• The Journal of the Petrological Society of Korea
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• v.25 no.1
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• pp.51-67
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• 2016

Geochemical characteristics of the Early Cretaceous igneous rocks from eastern China and the Gyeongsang Basin, Korean Peninsula has been summarized. They have wide range of lithological variation with extrusive picrite-basalt-andesite-trachyte-rhyolite and lamprophyre, and intrusive gabbro-diorite-monzonite-syenite-granite and diabase in eastern China, mostly belonging to the high-K calc-alkaline or shoshonitic series. The volcanic rocks intercalated with the Hayang Group sedimentary assemblages in the Gyeongsang basin are high-K to shoshonitic basaltic trachyandesites. The Early Cretaceous basaltic rocks studied mostly fall within the field of within-plate basalts on the Zr/Y-Zr and Nb-Zr-Y tectonic discrimination diagrams. On a Sr-Nd isotope correlation diagram, basaltic rocks from the North China block (NCB) and the continent-continent collision zone (CZ) between the North and South China blocks plot into the enriched lower right quadrant along the extension of the mantle array. The initial $^{87}Sr/^{86}Sr$ ratios of basaltic rocks from the South China block (SCB) are indistinguishable from those of the NCB and CZ basaltic rocks, but their ${\varepsilon}_{Nd}$ (t) values are relatively more elevated, plotting in right side of the mantle array. Basaltic rocks from the NCB and CZ are characterized by low $^{206}Pb/^{204}Pb(t)$ ratios, lying to the left of the Geochron on the $^{207}Pb/^{204}Pb(t)$ vs. $^{206}Pb/^{204}Pb(t)$ correlation. Meanwhile, the SCB basaltic rocks have relatively radiogenic Pb isotopic compositions compared with those of the NCB and CZ basaltic rocks. Basaltic rocks from the Hayang Group plot within the field of the NCB basaltic rocks in Sr-Nd and Pb-Pb isotope spaces. Metasomatically enriched subcontinental lithospheric mantle (SCLM) is likely to have been the dominant source for the early Cretaceous magmatism. Asthenospheric upwelling under an early Cretaceous extensional tectonic setting in eastern China and the Korean Peninsula might be a heat source for melting of the enriched SCLM. Metasomatic agents proposed include partial melts of lower continental crust delaminated and foundered into the mantle or subducted Yangtze continental crust, or fluid/melt derived from the subducted paleo-Pacific plate.

• Korean Chemical Engineering Research
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• v.49 no.5
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• pp.664-668
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• 2011

Spherical alumina precursors represented by $AlO_xCl_y(OH)_z$, 30~200 nm in particle diameter, were prepared by partial hydrolysis of $AlCl_3$ vapor in a 500 ml reactor. Investigated on the particle morphology and size were the effects of the reaction time, the stirring speed and the reaction temperature. The particle morphology and size was insensitive to the reaction time in the range 20 to 300 s. The variation of the stirring speed from 0 to 300 and 800 rpm showed that the particle size was the largest at 0 rpm. As the temperature was varied from 180 to 190, 200, $140^{\circ}C$, the particle size showed a maximum at $190^{\circ}C$. By calcination of the as-produced particles at $1,200^{\circ}C$ for 6h with a heating rate of $10^{\circ}C$/min, ${\alpha}$-alumina particles 45 nm in surface area equivalent diameter were obtained. The particle shape after calcination turned wormlike due to sintering between neighboring particles. A rapid calcination at $1400^{\circ}C$ for 0.5 h with a higher heating rate of $50^{\circ}C$/min reduced the sintering considerably. An addition of $SiCl_4$ or TMCTS(2,4,6,8-tetramethylcyclosiloxane) to the $AlCl_3$ reduced the sintering effectively in the calcination step; however, peaks of ${\gamma}$ or mullite phase appeared. An addition of $AlF_3$ to the particles obtained from the hydrolysis resulted in a hexagonal disc shaped alumina particles.

• Korean Journal of Construction Engineering and Management
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• v.12 no.6
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• pp.65-78
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• 2011

Construction business, which is complex and long-term business, requires accurate estimation and verification in construction costs and payment procedure from project planning to the completion of construction phase. And more importantly, it is necessary to investigate and determine the risk factors related to construction costs during the entire process including design planning, construction drawings, and quantity calculating. But, currently, it is not seem to be adequate to cope with the risk and increased construction costs against the operational budget in terms of actual costs when screening and estimating the bidding cost of public apartment. Therefore, this study selected and analyzed 40 sites' report of construction completion account from 2004 to 2010 focused on the adequacy on the modification of contract and design planning and on the complication of the budget in the beginning of the project. This study deducted various risk causes and results by analyzing actual costs according to year, architectural area, region, construction cost and sale/lease classification. We could find out construction risk according to annual variation of government policy and economy, and also deducted risk items by construction characteristic according to region and architectural area. Study result, we first found out the problems of lowest price award system according to the construction costs. The weight of the cost increase risk was analyzed that subcontract and material costs are very high. Roof and tile work were analyzed highly in subcontract cost risk and reinforcing bar and cement were analyzed highly in material cost risk, among direct construction cost. Finally, this study results could be used in comparing the categories of the construction costs made by specific construction process, belonging to the construction costs, with the operational budget made in the beginning of the project that can enable to grasp unpredictable risks over the construction costs and making quantitative analysis for it through analyzing the range of fluctuation and variations led by the fluctuations in the actual construction costs.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.12
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• pp.6-13
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• 2009

For X-band phased array systems, a power amplifier, a 6-bit phase shifter, a 6-bit digital attenuator, and a SPDT transmit/receive (T/R) switch are fabricated and measured. All circuits are demonstrated by using CMOS 0.18 um technology. The power amplifier has 2-stage differential and cascade structures. It provides 1-dB gain-compressed output power ($P_{1dB}$) of 20 dBm and power-added-efficiency (PAE) of 19 % at 8-11 GHz frequencies. The 6-bit phase shifter utilizes embedded switched filter structure which consists of nMOS transistors as a switch and meandered microstrip lines for desired inductances. It has $360^{\circ}$ phase-control range and $5.6^{\circ}$ phase resolution. At 8-11 GHz frequencies, it has RMS phase and amplitude errors are below $5^{\circ}$ and 0.8 dB, and insertion loss of $-15.7\;{\pm}\;1,1\;dB$. The 6-bit digital attenuator is comprised of embedded switched Pi-and T-type attenuators resistive networks and nMOS switches and employes compensation circuits for low insertion phase variation. It has max. attenuation of 31.5 dB and 0.5 dB amplitude resolution. Its RMS amplitude and phase errors are below 0.4 dB and $2^{\circ}$ at 8-11 GHz frequencies, and insertion loss is $-10.5\;{\pm}\;0.8\;dB$. The SPDT T/R switch has series and shunt transistor pairs on transmit and receive path, and only one inductance to reduce chip area. It shows insertion loss of -1.5 dB, return loss below -15 dB, and isolation about -30 dB. The fabricated chip areas are $1.28\;mm^2$, $1.9mm^2$, $0.34\;mm^2$, $0.02mm^2$, respectively.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.19 no.1
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• pp.76-87
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• 2014

Chlorophyll a in seawater which is an indicator of phytoplankton biomass and primary production is determined by High Performance Liquid Chromatography (HPLC), Fluorometry and Spectrophotometry. In this study, various methods for chlorophyll a determination in seawater are compared using in situ seawater samples from Korean seas. Three inter-laboratory comparison campaigns were carried out using chlorophyll a standard samples (R0) and in situ seawater samples, collected from the East China Sea (R1) and the East Sea (R2). 6 laboratories by HPLC methods, 4 laboratories by fluorometry, and 3 laboratories by spectrophotometry participated. Precisions, defined as the coefficient of variation (CV) were within 9% in standard samples, 0.8~20% (average: 6.1%) in R1, 4~21% (average: 13.2%) in R2. Discrepancy in three methods was approximately 20% within the range of the sample homogeneity intended the laboratory precision (R1: 8%, R2: 15%). The discrepancy in laboratories was greater than the discrepancy in methods. The chlorophyll a concentrations can be produced within 20% discrepancy in spite of using different methods. It is recommended to consider this 20% discrepancy when using the chlorophyll a data produced by different laboratories and different methods.

• Korean Journal of Environmental Biology
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• v.39 no.4
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• pp.526-535
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• 2021

Spatial sampling design plays an important role in GIS-based modeling studies because it increases modeling efficiency while reducing the cost of sampling. In the field of agricultural systems, research demand for high-resolution spatial databased modeling to predict and evaluate climate change impacts is growing rapidly. Accordingly, the need and importance of spatial sampling design are increasing. The purpose of this study was to design spatial sampling of paddy fields (11,386 grids with 1 km spatial resolution) in Korea for use in agricultural spatial modeling. A stratified random sampling design was developed and applied in 2030s, 2050s, and 2080s under two RCP scenarios of 4.5 and 8.5. Twenty-five weather and four soil characteristics were used as stratification variables. Stratification and sample allocation were optimized to ensure minimum sample size under given precision constraints for 16 target variables such as crop yield, greenhouse gas emission, and pest distribution. Precision and accuracy of the sampling were evaluated through sampling simulations based on coefficient of variation (CV) and relative bias, respectively. As a result, the paddy field could be optimized in the range of 5 to 21 strata and 46 to 69 samples. Evaluation results showed that target variables were within precision constraints (CV<0.05 except for crop yield) with low bias values (below 3%). These results can contribute to reducing sampling cost and computation time while having high predictive power. It is expected to be widely used as a representative sample grid in various agriculture spatial modeling studies.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.51 no.spc1
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• pp.139-145
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• 2006

The objectives of this study was to determine the oil contents and fatty acid compositions of soybean germplasms including major Korean cultivars, and to provide the basic information of fatty acid composition for development high quality soybean varieties. Among 46 Korean major cultivated soybean samples, the oil contents were varied from 15.8% to 20.3%, and the average oil content was 18.2%. Crude oil content of cv. Saebyolkong (20.3%) was the highest among that of other cultivated soybeans. Likely many other oils of plant origin, most fatty acids in soybean are unsaturated. The highest percentage of fatty acid in soybean was linoleic acid (18:2), followed in a decreasing order by oleic (C18:1), palmitic (C16:0), linolenic (C18:3), and stearic acid (C18:0). The composition of C18:1 and C18:2 fatty acids among 563 soybean germplasms and cultivars which were positively correlated with nutritional quality of edible vegetable oil, were ranged $13.29{\sim}43.30%\;and\;38.21{\sim}61.51%$, respectively, and the C18:3 which were negatively correlated with flavor quality were varied from 5.03% to 11.48%. Also, the composition of C16:0 and C18:0 which were known to raise total cholesterol levels in human serum were ranged $8.50{\sim}14.78%\;and\;1.86{\sim}4.78%$ respectively. On the other hand, the range of fatty acid composition among 46 Korean major soybean cultivars has been investigated to be: C16:0, $8.96{\sim}13.23%$; C18:0, $2.55{\sim}4.20%$; C18:1, $16.33{\sim}36.41%$; C18:2, $42.32{\sim}58.84%$; C18:3, $6.98{\sim}10.72%$. Among the 563 germplasms tested, there are significant correlations among unsaturated fatty acids: negative between C18:1 and C18:2 (r=-0.961**) or C18:3 (r=-0.756**), and positive between C18:2 and C18:3 (r=0.608**). Also, the C18:1 was negatively correlated with saturated fatty acids, C16:0 (r=-0.231**) and C18:0 (r=-0.479**).

• Journal of Sericultural and Entomological Science
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• v.16 no.2
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• pp.77-98
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• 1974

This study was carried out ill an attempt to investigate the properties and activities of sericin obtained from silk cocoon shells in silk reeling water through various instrumental analyses. In addition, the effects of the characteristics in sericin solubility on the reeling process and silk qualities were also studied on the basis of tile above conditions. The results obtained are as follows： I. The sericin properties and activities through various analytical instruments. 1. The water solubility of each amino acid such as serine, glycine. glutamic and aspartic acids against the pH modified water by using automatic amino acid analyzer, showed the lowest solubility at PH 5, but it increased according to drifting toward the alkalinity. 2. When the obtained sericin particles by water pH variation were observed with the electronic microscope, it was found for the sericin Particles to expand in the alkaline regions. 3. The IR spectrum results showed the differences among the pH modified sericin solutions at the range of 2,100cm-1 and 1.890cm-1 of wave number. 4. The existence of sericin with in silk fabrics made differences in the X-ray interference intencity, that is, the non-degummed fabrics had the interference peak at 2$\theta$=14$^{\circ}$, 17$^{\circ}$, 24$^{\circ}$, and the degummed ones had it at 2$\theta$=17$^{\circ}$, 18$^{\circ}$, 20$^{\circ}$, 23$^{\circ}$, 26$^{\circ}$. II. The results of sericin solubility for silk reeling process. 1. The sericin solubility and swelling had a tendency to increase up with high M-alkalinity and pH value of water. But in case of acidity. water hardness and concentration of ethylene glycol were high, the sericin solubility and swelling were decreased. 2. With the filature experiments, the best conditions of filature orator are summarized as fellows ; a. pH; 6.9${\pm}$0.2 d. acidity; below10ppm b. total hardness; 55：5ppm e. Fe ion; none c. M-alkalinity; 40${\pm}$10ppm

• Journal of Aquaculture
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• v.13 no.4
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• pp.339-351
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• 2000

Optimal environmental conditions, that sustained fastest growth, lowest mortality and abnormality of the scallop Patinopecten yessoensis, were identified from field experiments undertaken at Chumunjin during 1991-1998. Temperature within the water column 10~30 m depth ranged between 5 and 23$^{\circ}C$; high temperature and daily fluctuation resulted in growth retardation and heavy mortality of the scallop. Optimal salinity range was between 31.5 and 34.5%0 and water transparency 6.0 and 18.1 m, which was significantly affected by phytoplankton density. Chlorophyll concentration ranged between 0.04 and 3.51 f.lgfL. Low temperature and high chlorophyll concentration appear to support faster growth of the scallop. Optimal periods of transplantation for intermediate culture were between mid July and early November: cultured under high density during July-August as a first step and under low density during mid September through early November as a second step. Optimal stocking density in square net cage (<35${\times}$35 em) for intermediate culture was 30-40 individuals per cage for main culture using lantern net and 80 -100 individuals of the size of 1.5 ~ 3.0 em shell height per cage for sowing culture. During the intermediate culture, the highest growth was realized, when the cage was held at water depth between 10 and 15 m. Water depth below 25 m, however, was best to avoid mass mortality during the periods of abnormally high water temperature and high variation of water temperature. The daily growth rate during the intermediate culture was between 0.019~0.381 mm; low in January and February but high in March and April. It is suggested that the main culture is commenced before June under low stocking density to avoid the possibility of mass mortality during summer by high water temperature.

• Korean Journal of Ecology and Environment
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• v.47 no.1
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• pp.53-61
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• 2014

The origin of particulate organic matter (POM) and food web structure were investigated in Shingu reservoir based on stable isotope analysis from pre-monsoon (July) to post-monsoon (September) 2007. According to the depth in Shingu reservoir, the $^{13}C$ and $^{15}N$ values of POM for pre-monsoon period were nonsignificant distinction, while it was significant variation after rainfall period. The ${\delta}^{13}C$ values of POM in premonsoon period ranged from -25.1‰ to -26.1‰ in whole water column, but the ${\delta}^{13}C$ values of POM in post-monsoon period showed relatively wide range between -23.2‰ and -27.5‰. The apparently lighter values (average -27.5‰) in near bottom water (7 m water depth) demonstrate that POM in high turbid water in post-monsoon period may be derived from the outside terrestrial plants (allochthonous) through heavy rainfall during the summer monsoon period. After rainfall period, $^{13}C$ and $^{15}N$ values of D. brachyurum showed -23.3‰ and 12.2‰, respectively, while B. longirostris showed -27.1% and 8.7%, respectively. It suggested that D. brachyurum mainly feed on POM in autochthonous organic matter pool, but B. longirostris mainly consumed POM in allochthonous organic matter pool after rainfall period. Carbon and nitrogen stable isotope ratios were markedly different among secondary consumers. The carp (C. carpio) and catfish (S. asotus) were in the higher trophic level and crucian carp (C. auratus) and mudfish (M. mizolepis) were in the lower trophic level. $^{13}C$ and $^{15}N$ values of Z. platypus didn't significantly changed between before and after rainfall period. But P. parva and C. auratus apparently changed the $^{13}C$ and $^{15}N$ values after rainfall period. It is suggested that P. parva and C. auratus seem to feed allochthonous food source while Z. platypus depend on autochthonous food source.