• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.1
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• pp.22-26
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• 2013

PTCR ceramics of $(Ba_{0.998}Sm_{0.002})TiO_3+0.001MnCO_3+xSiO_2$ (x=1, 2, 3, 4, 5, 6 mol%) were fabricated by solid state method. Disk samples of diameter 5 mm and thickness about 1mm were sintered at $1,290^{\circ}C$ for 2 h in reduced atmosphere of $5%H_2-95%N_2$ followed by re-oxidation at $600^{\circ}C$ for 30 min. in $20%O_2-80%N_2$.and their microstructures and electrical properties were investigated with SEM and Multimeter. The color of sintered samples was strongly dependent on $SiO_2$ content showing that the color of samples with $SiO_2$ of 1~2 mol% was gray but that of samples with $SiO_2$ of 4~6 mol% was changed from gray to blue, which seems to be related with the reduction of samples due to the oxygen vacancies created during the sintering in reduced atmosphere. $SiO_2$ content had a great influence on the microstructure and the electrical properties. With increasing $SiO_2$ content, the grain size of samples increased and the resistivity as well as the resistivity jump ($R_{285}/R_{min}$) decreased, which is considered to be attributed to the resistivity change at grain interior and grain boundary due to the fast mass transfer through $SiO_2$ liquide phase during the sintering. Samples with 2 mol% $SiO_2$ has the resistivity of $202{\Omega}cm$ and the resistivity jump of 3.28. It is expected that $SiO_2$ doped $BaTiO_3$ based PTC ceramics can be used for multilayered PTC thermistor due to the resistance to the sintering in reduced atmosphere.

• Korean journal of applied entomology
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• v.57 no.4
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• pp.303-315
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• 2018

Bonsai is part of export forest products in Korea. Demand for bonsai exports to other countries is growing but the need for quarantine hazards must be eliminated in other to export. Plant parasitic nematode is also an important factor in quarantine. The nematodes were surveyed from bonsai farms in 6 areas of Korea. The surveyed deciduous bonsai plants were Acer palmatum, Zinnia elegans, Ligustrum obtusiflium, Carpinus turcaninowii, and Malus sieboldii. Three plant parasitic nematodes (Hemicyliophora koreana, Rotylenchus blothrotylus and Xiphinema americanum) and three non-parasitic nematodes (Aporclaimellus donghwaens, Egtitus andhricus, and Mesodorylaimus usitatus) were isolated from bonsai. Non-parasitic nematode, Mesodorylaimus usitatus was isolated from all surveyed bonsai trees. Only two species of quarantine nematodes (Hemcylicopora koreana and Xiphinema americanum) were found from bonsai. A. donghwaens and M. usitatus were isolated from root of bonsai tree. However other nematodes were isolated from soil in bonsai trees.

• Animal Bioscience
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• v.35 no.2
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• pp.247-259
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• 2022

Objective: This study was conducted to investigate the effects of age and diet forms on growth-development patterns, serum metabolism indicators, and parameters of body fat deposition in Cherry Valley ducks. Methods: According to the hatching age and initial weight, a total of 150 1-day-old male SM3 Cherry Valley ducks were randomly assigned to two diet forms (pellet vs powder form). Each treatment had with 5 replicates per treatment and 15 meat ducks per replicate. The study lasted 42 d, which was divided into two periods (1 to 21 vs 22 to 42 d). Results: Our results showed that compared with powder group, ducks in pellet group had greater growth performance during different period (p<0.05). The inflection point was 24 d and was not numerically affected by diet forms. Increasing age (42 vs 21 d) significantly increased the weight of body fat and hepatic fat metabolism related enzyme activities in ducks (p<0.05), meanwhile, increasing age (42 vs 21 d) improved serum metabolism indicators and decreased mRNA expression levels of fat metabolism-related genes in liver (p<0.05). Ducks fed different diets (pellet vs powder form) increased growth performance as well as the weight of body fat and improved serum metabolism indicators (p<0.05). In addition, interactions were found between age and diet forms on the levels of serum metabolism indicators in ducks (p<0.05). Conclusion: In conclusion, powder feed reduced growth performance of ducks, and the day of inflection point was 24 days old. Ducks with higher age or fed with pellet diet showed higher fat deposition. The effect of age and feed forms on body fat deposition might result from changes in the contents of serum metabolism indicators, key enzyme activity of lipid production, and hepatic gene expressions.

• Fisheries and Aquatic Sciences
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• v.25 no.3
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• pp.140-150
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• 2022

A method of ultrahigh performance liquid chromatography coupled to high resolution mass spectrometry (UPLC-HRMS) was established for characterization of the lipid profile of Skipjack tuna. Over 300 lipid molecular species were identified through cross-acquisition in both positive and negative ion mode. Phospholipids (PLs) were dominant in Skipjack tuna. Lysophosphatidylethanolamine (LPE), phosphatidylethanolamine (PE), lysophosphatidylcholine (LPC) and phosphatidylcholine (PC) were the main lipid molecular species in PLs, accounting for 89.24% of the total PLs. The ratio of sphingolipids (SLs) and glycerolipids (GLs) were considerable, accounting for 12.30% and 13.60% of the total lipids respectively. Ceramide (Cer) was the main lipid molecular species of SLs, accounting for 64.96% of total SLs, followed by sphingomyelin (SM), accounting for 25.45% of total SLs. Ether diglycerides (ether DG) were the main lipid molecular species of GLs (97.83%). The main fatty acids (FAs) are unsaturated fatty acids (UFAs) in Skipjack tuna. Besides, a new FAs class branched fatty acid esters of hydroxy fatty acids (FAHFA) was detected, together with the FA. The active lipids identified in this study can be used to evaluate the nutritional value of Skipjack tuna.

• Journal of the Korea Organic Resources Recycling Association
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• v.25 no.3
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• pp.91-98
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• 2017

The purpose of this study is to provide a design and operation technical guideline for meeting the appropriate design criteria to bio-gasification facilities treating organic wastes. 9 anaerobic digestion facilities which is normally operated during the field survey and 14 livestock manure farms were selected for precision investigation. the physicochemical analysis was performed on the moisture and organic contents, nutrients composition (carbohydrate, fat, protein), volatile fatty acids (VFAs), and nitrogen, etc. Volatile solids (VS) of organic wastes brought into the bio-gasification facilities were 2.81 % (animal manure only) and 5.92 % (animal manure+food waste), respectively. Total solids (TS) reults of samples from livestock farms were 5.6 % in piglets and 11~13 % in other kinds of breeding pigs. The actual methane yield based on nutrients contents was estimated to $0.36Sm^3CH_4/kgVS$ which is equivalent to 72 % of theoretical methane yield value. The optimum mixing ratio depending on the effect of the combined bio-gasification was obtained through the continuous stirred-tank reactor (CSTR) which is operated at different mixing ratio of swine manure and food waste leachate. The range of swine manure and food waste leachate from 60:40 to 40:60 were adequate to the appropriate conditions of anaerobic digestion; less than 100 gTS/, more than alkalinity of 1 gCaCO3/L, C/N ratio 12.0~30.0, etc.

• The Korean Journal of Quaternary Research
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• v.16 no.1
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• pp.1-16
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• 2002

A total of 4 muddy sediment samples collected from the Central Yellow Sea were analyzed for chemical composition. The results are compared with the previously published Huanghe, Changjiang and Keum River geochemical data in order to understand provenance and sedimentation of fine-grained mud, and the sediment accumulation rates estimated. The sandy sediment facies is distributed in the eastern area, a patch of fine-grained mud exists in the western central prat, and the sandy mud and clay sedimentary facies shot. north to south zonal distribution in the central region. The content of calcium carbonate ranges from 2.8 to 10.5%, and its distributional trends to be more concentrated on the western muddy sediments near toward the China side rather than on the eastern sandy sediments. The accumulation rates obtained using Pb-210 geochronologies for the muddy sediments in the Central Yellow Sea showed ranges from 0.21 to 0.68 cm/yr or 0.176 to 0.714 g/$\textrm{cm}^2$. yr. The sedimentation rate from core CY96010 located in the eastern near side of Shandong Peninsula which is affected by the Huanghe River shows 0.68 cm/yr or 0.714 g/$\textrm{cm}^2$ . yr. The sediment cores CY96008 and CY96002 in the Central Yellow Sea, the estimated of sediment accumulation rates shows 0.21~0.23cm1yr or 0.176~0.220 9/$\textrm{cm}^2$.Vr respectively, which are much lower than above samples. These indicate that the muddy sediments in central area of the Yellow Sea may have received influence of the sediment discharge from the Huanghe River. The concentrations of Ca, Na, Sr, Ho, La, Tb, Ta and Ca/Ti ratio of the muddy sediments in the Central Yellow Sea are higher than those of the Changjiang sediments and lower than those of the Huanghe sediments. However, these element values showed similar concentration patterns than those of the Huanghe sediment. The element contents such as Fe, Ti, Nl, Co, Cr, Cu, Pb, Sc, Ce, Nd, Sm, Eu, Cd and Dy in the study area are higher than those of the Huanghe sediments and lower than the Changjiang River sediments, but these values showed close to resemblance content trends those of the Changjiang sediment. The concentration of Mn, K and Sr in sediments of the study area are similar to those of the Keum River and eastern Yellow Sea sediment. They are rich in Zn, Rb, Cd, U, Cs and Li than those of the other comparison legions. Therefore, the terrigenous materials sources of the muddy sediment in the Central Yellow Sea comes mainly from Huanghe River in the past and present, and also have party derived from the Changjiang and Keum River, while the biological deposit in this area are carried by the Yellow Sea Warm Current.

• Korean Chemical Engineering Research
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• v.51 no.5
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• pp.609-614
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• 2013

This study investigated the spontaneous combustion behavior of solvent-treated low rank coals. Indonesian lignite (a KBB and SM coal) and sub-bituminous (a Roto coal) were mixed with non-polar 1-methyl naphthalene (1MN) either by mechanical agitation or ultrasonication. The property change associated with 1MN treatment was then analyzed using proximate analysis, calorific value analysis, Fourier transform infrared (FT-IR), X-ray photoelectron spectroscopy and moisture re-adsorption test. Susceptibility to spontaneous combustion was evaluated using crossingpoint temperature (CPT) measurement along with gas analysis by GC. A FT-IR profile showed that oxygen functional groups and C-H bonding became weaker when treated by 1 MN. XPS results also indicated a decrease of the oxygen groups (C-O-, C=O and COO-). Increased hydrophobicity was found in the 1MN treated coals during moisture readsorption test. A CPT of the treated coals was ${\sim}20^{\circ}C$ higher than that of the corresponding raw coals and the ultrasonication was more effective way to enhance the stability against spontaneous combustion than the agitation. In the gas analysis less CO and $CO_2$ were emitted from 1MN treated coals, also indicating inhibition of pyrophoric behavior. The surface functional groups participating in the oxidation reaction seemed to be removed by the ultrasonication more effectively than by the simple mechanical agitation.

• Journal of Plant Biotechnology
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• v.32 no.2
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• pp.105-109
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• 2005

To enhance salidroside productivity from a cell suspension cultures of Rhodiola sachalinensis, various combinations of auxin (NAA) and cytokinins (BA, Kinetin) concentration and addition of $GA_3$, TDZ, zeatin, spermine and spermidine at a hormone combination to be established were examined. NAA/BA combination is superior to NAA/kinetin combination in biomass and salidroside content. Maximum salidroside production ($64.6{\pm}8.9\;mg/L$ medium) was obtained from $2B_5$ medium with 1 mg/L NAA and 5 mg/L BA. The adding of $GA_3$ ($0.01\;mg/L{\sim}5\;mg/L$) was beneficial for salidroside accumulation and the highest productivity of salidroside, $90.3{\pm}8.34\;mg/L$, was obtained from $2B_5$ medium supplemented with 1 mg/L NAA, 5 mg/L BA and 0.1 mg/L $GA_3$. On TDZ, zeatin, spermine and spermidine, expectant results were not obtained except a little affirmative effect of spermidine ($69{\pm}2.88$ at 1 mg/L).

• Journal of the Mineralogical Society of Korea
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• v.5 no.2
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• pp.109-121
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• 1992

For the purpose of mineralogical and chemical study on the topazes from various localities of world(Brzail, China, India, Nigeria and Sri Lanka), electron microprobe analysis(EPMA), neutron activation analysis(NAA), X-ray diffractometry, Raman spectroscopy, etch test, scanning electron microscopy, refractive index, specific gravity, fluid inclusion were performed. The chemical composition in topaz was discussed along with its physical and structural properties. Variations in the unit-cell dimension and physical properties of topaz were found to have a close relations in the unit-cell dimension and physical properties of topaz were found to have a close relationship with extent of substitution of $OH^-\;for\;F^-$. According to neutron activation analyses, the trace elements had no effects on the physical properties of topaz. Raman spectra showed that the peaks of topaz were different in intensity from one locality to another. Etching defects in topaz includes negative crystal defect o point-bottom pit(India, Nigeria) and net work defect of curl-bottom pit(Brazil, China). Fluid inclusions in topaz may be classiffied into liquid $CO_2$-bearing inclusion, gaseous inclusion, halite, sylvite-bearing inclusion and liquid inclusion. The results of this study can be useful to devising artificial coloring methods for topaz with different mineralogical compositions.

• Applied Chemistry for Engineering
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• v.24 no.2
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• pp.148-154
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• 2013

UV curable acryl resin, pressure-sensitive adhesives (PSAs), are used in many different parts in the world. In particular, PSAs has been used in the wafer manufacturing process of semiconductor industry. As wafers become much thinner, UV curable PSAs require more proper adhesion performance. In this study, acrylic PSAs containing hydroxyl groups were synthesized using monomers of 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, styrene monomer and 2-hydroxyethyl acrylate. Isocyanate modified UV curable PSAs were then prepared by the adduct reaction that facilitates the UV curing property via controlling the amount of methacryloyloxyehtyl isocyanate. The proper adhesion performance and UV curing behavior of UV curable PSAs with various hydroxyl values were studied, and experimental conditions were then optimized to raise the efficiency of wafer manufacturing process. It was found that in case of using the equivalent ratio of 1 : 1 isocyanate hardener used in the UV curable PSAs, the peel strength before the UV curing process decreased as the amount of hydroxyl groups increased in the PSAs. The peeling adhesive strength was also decreased with increasing UV dose due to high curing characteristics.