• Journal of the Korean Society of Food Science and Nutrition
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• v.46 no.5
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• pp.616-621
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• 2017

The objective of this study was to investigate the physicochemical properties of domestic strong wheat flour (DSWF). Three commercial DSWFs (D1, D2, and D3) were compared with imported strong wheat flour (ISWF). DSWFs had higher moisture content, crude protein content, lightness, and whiteness than ISWF. DSWFs showed lower solvent retention capacity and water absorption index than ISWF. DSWFs also showed significantly higher water solubility index than ISWF (P<0.05). Setback values by rapid visco analysis were significantly higher in D1 and D2 than in ISWF and D3, which means ISWF and D3 were better in retarding retrogradation. Differential scanning calorimetry results showed that ISWF required 6.2 J/g of energy for phase transition, whereas DSWFs needed 6.67~7.13 J/g. The farinograph results showed that ISWF had higher water absorption, longer dough stability time, and significantly higher softening of dough at 20 min than DSWF (P<0.05). Dough resistance and extensibility were higher in ISWF than in DSWFs.

• Korean Journal of Social Welfare
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• v.56 no.4
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• pp.57-78
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• 2004

The economic crisis in $1997{\sim}1998$ caused massive unemployment and unprecedentedly increased the number of the poor in Korea. As many unemployed families fell into poverty, the poverty rate skyrocketed to higher than 10 percent. Not later than 2000, unemployment late got back to normal and real average income among urban households approached to the income level prior to the economic crisis. Although the economic crisis has been passed through, poverty was not decreased to the low level prior to the crisis by 2000. Why does it remain high? This study attempts to provide an answer to this question by analysing the poverty trend over the 1990s. Data come from the National Survey of Household Income and Expenditures 1991, 1996, and 20001. Results show that poverty was rapidly reduced in the first half period of the 1990s. This reduction in poverty is largely explained by steady and rapid economic growth. Modest improvement in income inequality also contributed. In contrast, the poverty rate considerably increased in the latter half of the 1990s. Average income was not fully recovered to its prior level, which reflected the economic crisis and the subsequent economic stagnation. Worsened income inequality led to higher poverty rate too. In addition, demographic changes increased the share of economically vulnerable types of families, such as families headed by single parents and the elderly. The most significant factor in explaining the higher poverty rate was extended income differential among non-elderly adults, while the next was the increased number of the elderly families. Yet, findings a little differ depending on which concepts of poverty to adopt. In the analyses based on the concept of absolute poverty, economic growth the most significantly affected the poverty trends in the 1999s. Changes in income inequality played the most important role in explaining the trend in relative poverty. Adopting the concepts of quasi-absolute poverty, which is preferred in this study, results show that rapid economic growth significantly reduced poverty in the first half of the 1990s and both worsened income inequality and stagnated economic growth increased poverty in the latter 1990s.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.1
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• pp.54.1-54.1
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• 2016

Multi-wavelength variability is a staple of active galactic nuclei (AGN). Optical variability probes the nature of the central engine of AGN at smaller linear scales than conventional imaging and spectroscopic techniques. Previous studies have shown that optical variability is more prevalent at longer timescales and at shorter wavelengths. Intra-night variability can be explained through the damped random walk model but small samples and inhomogeneous data have made constraining this model hard. To understand the properties and physical mechanism of intra-night optical variability, we are performing the KMTNet Active Nuclei Variability Survey (KANVaS). Using KMTNet, we aim to study the intra-night variability of ~1000 AGN at a magnitude depth of ~19mag in R band over a total area of ${\sim}24deg^2$ on the sky. Test data in the COSMOS, XMM-LSS, and S82-2 fields was obtained over 4, 6, and 8 nights respectively during 2015, in B, V, R, and I bands. Each night was composed of 5-13 epoch with ~30 min cadence and 80-120 sec exposure times. As a pilot study, we analyzed data in the COSMOS field where we reach a magnitude depth of ~19.5 in R band (at S/N~100) with seeing varying between 1.5-2.0 arcsec. We used the Chandra-COSMOS catalog to identify 166 AGNs among 549 AGNs at B<23. We performed differential photometry between the selected AGN and nearby stars, achieving photometric uncertainty ~0.01mag. We employ various standard time-series analysis tools to identify variable AGN, including the chi-square test. Preliminarily results indicate that intra-night variability is found for ~17%, 17%, 8% and 7% of all X-ray selected AGN in the B, V, R, and I band, respectively. The majority of the identified variable AGN are classified as Type 1 AGN, with only a handful of Type 2 AGN showing evidence for variability. The work done so far confirms there are more variable AGN at shorter wavelengths and that intra-night variability most likely originates in the accretion disk of these objects. We will briefly discuss the quality of the data, challenges we encountered, solutions we employed for this work, and our updated future plans.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.10 no.1
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• pp.66-72
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• 2000

The behavior of nucleation and crystallization in the $Li_2O_3-SiO_2$ glass heat-treated at different condition under the conventional and microwave processing was studied by differential thermal analysis (DTA), X-ray diffractometry (XRD), optical microscopy (OM), and electrical conductivity measurement. Nucleation temperature and temperature of maximum nucleation rate in both conventionally and microwave heat-treated samples were 460~$500^{\circ}C$ and $580^{\circ}C$, respectively. It was expected that the probability for bulk crystallization increased in microwave heat-treated sample, compared to conventionally heat-treated one. Degree of crystallization increased with increasing crystallization temperature in both conventionally and microwave heat-treated samples. However, pattern of crystallization growth under microwave processing appeared to be quite different from that under the conventional one due to its internal or volumetric heating. Electrical conductivity of conventionally and microwave heat-treated samples were 1.337~2.299, 0.281~~$0.911{\times}10^{-7}\Omega {\textrm}{cm}^{-1}$, respectively.

• Journal of the Korean Chemical Society
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• v.36 no.3
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• pp.428-441
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• 1992

We synthesized a series of binuclear pentadentate Schiff base complexes such as $Co(Ⅱ)_2$ (BSPP)($H_2O)_2$, $Co(Ⅱ)_2$ (BSPD)($H_2O)_2$, $Mn(Ⅱ)_2$ (BSPP)($H_2O)_2$ and $Mn(Ⅱ)_2$ (BSPD)($H_2O)_2$, mononuclear pentadentate Schiff base complexes such as Co(Ⅱ)(BSP)($H_2O)$ and Mn(Ⅱ)(BSP)($H_2O)$. The composition of these complexes identified by IR, UV-visible spectrum, T.G.A., DSC, and elemental analysis. The electrochemical redox processes have been examined by cyclic voltammetry and differential pulse polarography with glassy carbon electrode in 0.1M TEAP-Py(-DMSO and -DMF) as a supporting electrolyte solution. As a result of electrochemical measurements, the reduction processes for pentadentate binuclear Schiff base cobalt(Ⅱ) and manganese(Ⅱ) complexes occurred to four steps in $M(Ⅲ)_2$ / $Mn(Ⅱ)_2$ and $Mn(Ⅱ)_2$ / $M(Ⅰ)_2$ (M; Co, Mn) two processes through each two reduction steps with one electron, by contrast, the mononuclear pentadentate Schiff base cobalt(Ⅱ) and manganese(Ⅱ) complexes occurred to two steps in M(Ⅲ) / M(Ⅱ) and M(Ⅱ) / M(Ⅰ) (M; Co, Mn) two processes with one electron reduction steps.

• Bulletin of the Korean Chemical Society
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• v.31 no.4
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• pp.976-980
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• 2010

A series of arylacetylene resins with siloxane units were synthesized by the condensation reactions of m-diethynylbenzene magnesium reagents with various $\alpha,\omega$-bis(chloro)dimethylsiloxanes. These resins are liquids and are miscible with common organic solvents at room temperature. The structures of the resins were characterized by FT-IR, $^1H$ NMR, $^{13}C$ NMR, $^{29}Si$ NMR, and gel permeation chromatography (GPC). The thermal behaviors of the resins were examined with differential scanning calorimetry (DSC). These resins have good processability. They can be thermally cross-linked through the ethynyl groups to produce cured resins. The thermal and thermooxidative stabilities of the cured resins were studied by thermogravimetric analysis (TGA). The cured resins possess high thermal and thermooxidative stability. Their decomposition occurs at above $500^{\circ}C$ in both $N_2$ and air. With increasing the length of siloxane units in the resins, the thermal stability of the cured resins decreases in $N_2$. When the cured resins were sintered above $1450^{\circ}C$ under argon, hard and glassy SiOC ceramics were obtained. These SiOC ceramics have the decomposition temperatures at 5% weight loss above $800^{\circ}C$ in air.

• Korean Journal of Agricultural Science
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• v.27 no.2
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• pp.141-157
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• 2000

This study is aimed at identifying the socio-economic value of the total area of 23,500ha of paddy field which will be reclaimed in year 2003. In Korea, tidal land reclamation projects has been carried out not only for paddy field expansion to meet national food security but also for national land expansion to cope with the shortage of land supply in implementing urbanization and industrialization. As of end of 1999, 75,738ha of tidal land reclamation, 48.3%, out of 156,666ha has been carried out in Korea. In spite of continuous implementation of tidal land reclamation, 48.3%, out of 156,666ha has been carried out in Korea. In spite of continuous implementation of tidal land reclamation projects, the appraisal of the national land expansion value has not been made even though the severe competitiveness of land use in economic development. Agricultural land about 20,000 - 30,000ha per year has been converted to urban and industrial land and the converted areas have been produced higher added value than that of the farm land. Accordingly, farm land expansion equivalent to the converted area have to be reclaimed to cope with the food shortage and security in the future. In relation to the study, demand and supply of rice, the staple food of Korean, has been projected up to year 2025. The study results are as follows: 1. Under the assumption of continuing the present tendencies of rice consumption, population increase, farming practices and farm land conversion, paddy area requirement to meet self sufficiency of rice were forecasted as 136,950ha in 2015, 193,460ha in 2020 and 218,482ha in 2025 respectively. 2. The average converted price of paddy per pyeong in Kimje city, Puna Gun and Gunsan city was estimated at 241,150won and average farm land price was amounted to 63,760won. The differential rent was estimated at 177,400won per pyeong which was used as a criteria for valuation of national land expansion effect of the tidal land reclaimed by Saemangeum project. The total land rent of 23,250ha expanded by tidal land reclamation was amounted to 12,361 billion won. Annual expected value of the expanded national land was estimated at 988.9 billion won considering 8% of annual discount rate in Korea. 3. Tidal land resource for paddy area development is limited comparing with the future requirement of paddy area to cope with self sufficiency of rice consumption. Accordingly farm land conversion to urban and industrial land should be regulated and protected in the sense of sustainable development in the future.

• Elastomers and Composites
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• v.37 no.1
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• pp.7-13
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• 2002

In this study, mechanical properties of PVC complexes containing the gypsum (Namhae Chemical Co.) which contains phosphte, CaO, etc., Pb-species stabilizer, and $CaCO_3$ were investigated as a function or the content. As a result, mechanical properties increased when the gypsum was mixed with PVC at the extent of 8.46wt%. From this result, it is suggested that the gypsum containing phosphate and CaO is compatible with PVC. Thermogravimetric analysis(TGA) showed that pyrolysis started about at $275^{\circ}C$, and residual weight(%) increased with the amount of the gypsum, and differential scanning calorimetry (DSC) showed that $T_m,\;T_g$ had the maximum and minimum value respectively when the gypsum was mixed with PVC at the extent of 8.46wt%. Comparing all the results, both mechanical and thermal properties of PVC complex were improved. The X-ray diffraction measurement also showed their blonds and structures.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.12 no.1
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• pp.27-33
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• 1982

The purpose of this study is to obtain some informations for the differential diagnosis of ameloblastoma from dentigerous cyst by analysis of the radiographic findings of these lesions. The author studied age and sex distribution, the site of the lesion, tooth behavior and several radiographic features of ameloblastoma and dentigerous cyst. The material consisted of 65 patients of ameloblastoma and 37 patients of dentigerous cyst. The results were obtained as followings. 1) The incidence was highest in 2nd decade (29.2%) and total 65 cases consists of 35 males (53.8%) and 30 females (46.2%) in ameloblastoma. 62 cases were found in lower jaw (95.4%) and the highest site of occurence of ameloblastoma was mandibular molar. region 27 cases. (41.5%) 2) In 65 cases of amelobl!!stoma, 18 cases were seen in association with tooth and 15 cases (83.2%) out of those were associated with mandibular molar teeth. Mandibular molar were most frequently involved in dentigerous cyst (11/31 cases, 29.7%). 3) (a) 23 cases (35.3%) of tooth resorption were found in ameloblastoma and 11 cases (29.7%) of tooth resorption were found in dentigerous cyst. (b) 15 cases (23.1%) of tooth migration were found in ameloblastoma and 10 cases (27.0%) of tooth migration were found in dentigerous cyst. 4) Several radiographic features. (a) Monolocular type ameloblastoma were seen in 23 cases (35.4) and multilocular type of ameloblastoma were seen in 42 cases (64.6%). Monolocular type of dentigerous cyst were seen in 33 cases (89.2%) and multilocular type was seen in 4 cases. (b) Monolocular type ameloblastoma showed 20 cases (87.0%) of scalloped border but 32 cases (97.0%) of dentigerous cyst showed smooth border. (c) 34 cases (81.0%) of ameloblastoma showed honey-comb appearance, soap-bubble appearance or mixed appearance. but all 4 cases of dentigerous cyst showed multicystic appearance. (d) 12 cases (52.2%) of monolocular type ameloblastoma showed slightly increased radiopacity in surrounding bone, and 22 cases (66.7%) of monolocular type dentigerous cyst showed sharp osteosclerotic border. 27 cases (64.3%) of multilocular type ameloblastoma and 3 cases (75.0%) of multilocular type dentigerous cyst showed no changes in surrounding bone.

• Polymer(Korea)
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• v.32 no.3
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• pp.256-262
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• 2008

Copolyimides containing pendant trifluoromethyl ($CF_3$) groups were synthesized from 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) and bis[4-(3-aminophenoxy)phenyl]sulfone (BAPS) with various concentrations of 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane(BAPP) to poly(amic acid)(PAA), followed by thermal imidization. These copolyimides were readily soluble in N,N'-dimethylacetamide (DMAc) and could be solution-cast into a flexible and tough film. The thermomechanical properties, morphology and an optical transparency of the copolyimide films were determined using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), wide angle X-ray diffraction (XRD), scanning electron microscopy (SEM), universal tensile machine (UTM), and a UV-Vis spectrometer. The cast copolyimide films exhibited high optical transparency with a cut-off wavelength (${\lambda}_0$) of $275{\sim}319\;nm$ in UV-vis absorption and a low yellow index(YI) value of $3.65{\sim}10.37$. The thermo-mechanical properties of copolyimide films were enhanced linearly with increasing a BAPP content. In contrast, the optical transparency of the copolyimide films was found to get worse with increasing a BAPP content.