• Journal of Powder Materials
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• v.20 no.4
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• pp.275-279
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• 2013

Fe-based oxide dispersion strengthened (ODS) powders were produced by high energy ball milling, followed by spark plasma sintering (SPS) for consolidation. The mixed powders of 84Fe-14Cr-$2Y_2O_3$ (wt%) were mechanically milled for 10 and 90 mins, and then consolidated at different temperatures ($900{\sim}1100^{\circ}C$). Mechanically-Alloyed (MAed) particles were examined by means of cross-sectional images using scanning electron microscopy (SEM). Both mechanical alloying and sintering behavior was investigated by X-ray diffraction (XRD) and high resolution transmission electron microscopy (HR-TEM). To confirm the thermal behavior of $Y_2O_3$, a replica method was applied after the SPS process. From the SEM observation, MAed powders milled for 10 min showed a lamella structure consisting of rich regions of Fe and Cr, while both regions were fully alloyed after 90 min. The results of sintering behavior clearly indicate that as the SPS temperature increased, micro-sized defects decreased and the density of consolidated ODS alloys increased. TEM images revealed that precipitates smaller than 50 nm consisted of $YCrO_3$.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.11 no.3
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• pp.115-119
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• 2001

Hydroxyapatite-yttria stabilized zirconia bioceramics containing fine zirconia particles were prepared as 3-layered functionally graded materials (FGMs) using a spark plasma sintering (SPS) and hot pressing (HP) apparatuses. The pretreatment of the raw hydroxyapatite promoted the sinterability of hydroxyapatite. The maximum density of pretreated FGM composites could be obtained at lower temperature than that for he untreated FGM samples. No decomposition from hydroxyapatite to three calcium phosphate (TCP) was observed in FGMs of HAp-$ZrO_2$ sintered below $1200^{\circ}C$ for 8 min under 10 MPa by SPS. However, the transformation of the tetragonal zirconia to the cubic modification had occurred in FGMs at this temperature. The presence of zirconia i.e. stress induced transformation of zirconia may be expected to enhance the mechanical properties of HAp-$ZrO_2$ FGM. The SPS is concluded as a better method to fabricated the FGM with dense and high strength compared with HP process.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.12 no.4
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• pp.172-177
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• 2002

The CuZnAl alloys have some advantages against other shape memory alloys, such as the widely variable transformation temperature, the low cost and easy fabrication. The alloys have been produced mostly by metallurgical methods. Thereby a tendency to large grain sizes is observed, which causes brittle properties of the materials. In order to avoid these deficiencies a special powder metallurgical process, SPS(spark plasma sintering), is applied in the present investigation. The starting materials were the pure (99.9 %) Cu, Zn and Al element powders with different particle size. The relatively fine grained and homogeneous Cu-24.78Zn-9.11Al (at.%) and Cu-13.22Zn-17.24Al (at.%) shape memory alloys were obtained using the powders with size of 75-150 $\mu$m. The average grain size is about 70 $\mu$m and the phases at room temperature are the austenitic and martensitic phase respectively.

• Journal of the Korean Society of Food Science and Nutrition
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• v.40 no.7
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• pp.1048-1052
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• 2011

This study examined the flow properties, paste clarity, freeze-thaw stability and gel strength of acetylated sweet potato starch (ASPS) pastes and gels as a function of degree of substitution (DS). ASPS showed high shear-thinning flow behaviors with high Casson yield stress ($\sigma_{oc}$). Consistency index (K), apparent viscosity ($\eta_{a,100}$) and $\sigma_{oc}$ values of ASPS increased with an increase in DS. In the temperature range of $25{\sim}70^{\circ}C$, ASPS followed an Arrhenius temperature relationship. The activation energies (Ea=13.2~14.3 kJ/mol) of the ASPS samples were much lower than that (18.1 kJ/mol) of the native sweet potato starch (SPS). ASPS gels showed better freeze-thaw stability with a significant decrease in syneresis (%) compared to SPS gel. The gel strength values of ASPS were much lower than that of SPS, and significantly decreased with an increase in DS. The clarity of native SPS paste increased after acetylation.

• Journal of Korean Academy of Nursing
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• v.40 no.2
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• pp.151-160
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• 2010

Purpose: The purpose of this study was to evaluate the effects of teaching method using Standardized Patients (SPs) on nursing competence, self-directed learning readiness, and problem solving ability-focusing on subcutaneous insulin injection. Methods: This research was a nonequivalent control group non-synchronized post-test design. The subjects consisted of 62 junior nursing students at E University. Scenarios to train SPs and checklists to evaluate the students' competence were developed by our research team. The experimental group (n=31) participated in the teaching class using SPs. The control group (n=31) received traditional practice education. The collected data were analyzed with descriptive analysis, $\chi^2$/Fisher's exact test, t-test, Pearson's correlation coefficient, and Cronbach's $\alpha$ using SPSS WIN 14.0 Program. Results: The mean scores of competence, self-directed learning readiness, and problem solving were significantly higher in the experimental group than the control group. Conclusion: As confirmed by this research findings, the teaching method using SPs was more effective than the traditional method to improve junior nursing students' competence, self-directed learning readiness, and problem solving. Therefore, It is necessary to develop a various of scenarios and to testify their effectiveness.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.314-314
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• 2010

The SiC-$ZrB_2$ composites were fabricated by combining 40vol.% of Zirconium Diboride(hereafter, $ZrB_2$) powders with Silicon Carbide(hereafter, SiC) matrix. TheSiC+40vol.%$ZrB_2$ composites were manufactured through Spark Plasma Sintering(hereafter, SPS) under argon atmosphere, uniaxial pressure of 50MPa, heating rate of $100^{\circ}C$/min, sintering temperature of $1,500^{\circ}C$ and holding time of 5min. But one on/off pulse sequence(one pulse time: 2.78ms) is 10:9(hereafter, SZ10), and the other is 48:8(hereafter, SZ48). The physical and mechanical properties of the SZ12 and SZ48 were examined. Reactions between $\beta$-SiC and $ZrB_2$ were not observed via X-Ray Diffraction(hereafter, XRD) analysis. The apparent porosity of the SZ10 and SZ48 composites were 9.7455 and 12.2766%, respectively. The SZ10 composite, 593.87MPa, had higher flexural strength than the SZ48 composite, 324.78MPa, at room temperature. The electrical properties of the SiC-$ZrB_2$ composites had Positive Temperature Coefficient Resistance(hereafter, PTCR).

• THE INTERNATIONAL COMMERCE & LAW REVIEW
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• v.75
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• pp.179-198
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• 2017

Recently, agricultural exports of Korea have steadily increased. But, no progress is being made at the WTO and DDA negotiations, the FTAs have played a leading role in the formulation of the international trade rules, and countries have been cleverly utilizing non-tariff barriers such as SPS and TBT, there is a growing need to respond to non-tariff barriers aggressively. On the other hand, since the FTA has the potential to activate the global value chain, there is a high need for exporting companies in the domestic agricultural sector to understand the structure of the global value chain in agriculture and actively utilize the global value chain. The non-tariff measures of agricultural commodities major trading partners in the field of domestic agricultural exports were mostly comprised of SPS measures and TBT measures. The non-tariff measures corresponding to inputs and production stages of value chain elements (seeds, seedlings) in the value chain were mainly reported in SPS measures. TBT measures are mainly carried out in selective packaging, storage, processing, distribution, and export sales. It is most important for agricultural export companies to know their position on the value chain and information on non-tariff measures of importing countries in order to actively utilize the global value chain. Since there are non-tariff barriers that are difficult to be solved at the individual enterprise level, active government support of the government is not only important but also actively promoting relevant information to farmers and agricultural exporters. In addition, potential export farmers and prospective export companies will be able to identify TBT and SPS and other non-tariff barriers well in advance, and respond to them in advance. Also, through networking with export related organizations and overseas buyers, It is very important that policy support from the perspective of global value chain is linked effectively.

• Biomolecules & Therapeutics
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• v.22 no.3
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• pp.213-222
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• 2014

Abnormal adaptation of the stress-response system following traumatic stress can lead to alterations in the hypothalamic-pituitaryadrenal (HPA) axis that may contribute to the development of post-traumatic stress disorder (PTSD). The present study used several behavioral tests to investigate the anxiolytic-like and antidepressant activity of L-tetrahydropalmatine (L-THP) in an experimental rat model of anxiety and depression induced by single prolonged stress (SPS), an animal model of PTSD. Male rats were treated intraperitoneally (i.p.) with vehicle or varied doses of THP 30 min prior to SPS for 8 consecutive days. Daily THP (50 mg/kg) administration significantly increased the number and duration of open arm visits in the elevated plus maze (EPM) test, reduced the anxiety index, increased the risk assessment, and increased the number of head dips over the borders of the open arms after SPS. THP was also associated with increased time spent at the center of the open field, reduced grooming behaviors in the EPM test, and reduced time spent immobile in the forced swimming test (FST). It also blocked the decrease in neuropeptide Y (NPY) and the increase in corticotrophin-releasing factor (CRF) expression in the hypothalamus. This is the first study to determine that THP exerts pronounced anxiolytic-like and antidepressant effects on the development of the behavioral and biochemical symptoms associated with PTSD, indicating its prophylactic potential. Thus, THP reversed several behavioral impairments triggered by the traumatic stress of SPS and is a potential non-invasive therapeutic intervention for PTSD.

• Journal of Ginseng Research
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• v.44 no.4
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• pp.644-654
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• 2020

Background: Posttraumatic stress disorder (PTSD), a mental disorder induced by traumatic stress and often accompanied by depression and/or anxiety, may involve an imbalance in the neurotransmitters associated with the fear response. Korean Red Ginseng (KRG) has long been used as a traditional medicine and is known to be involved in a variety of pharmacological activities. We used the open field test and forced swimming test to examine the effects of KRG on the depression-like response of rats after exposure to single prolonged stress (SPS), leading to activation of the serotonergic system. Methods: Male rats received KRG (30, 50, and 100 mg/kg, intraperitoneal injection) once daily for 14 days after exposure to SPS. Results: Daily KRG administration significantly improved depression-like behaviors in the forced swimming test, increased the number of lines crossed and time spent in the central zone in the open field test, and decreased freezing behavior in contextual and cued fear conditioning. KRG treatment attenuated SPS-induced decreases in serotonin (5-HT) tissue concentrations in the hippocampus and medial prefrontal cortex. The increased 5-HT concentration during KRG treatment may be partially attributable to the 5-hydroxyindoleacetic acid/5-HT ratio in the hippocampus of rats with PTSD. These effects may be caused by the activation of hippocampal genes encoding tryptophan hydroxylase-1 and 2 mRNA levels. Conclusion: Our findings suggest that KRG has an antidepressant effect in rats subjected to SPS and may represent an effective use of traditional medicine for the treatment of PTSD.

• Ocean and Polar Research
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• v.38 no.2
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• pp.129-137
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• 2016

This study aimed to isolate and characterize sulfated polysaccharides (SPs) from Iridaea cordata and evaluate their anticancer activity. SPs of the Antarctic red seaweed were obtained by $CaCl_2$ (SP1) and ethanol precipitations (SP2) following diluted acid extraction at room temperature. Yields of SP1 and SP2 were approximately 14% and 23%, respectively, of the dry weight of red seaweed. The average molecular mass of the SP1 and SP2 was estimated about $1.84{\times}10^3$ and $1.42{\times}10^3kDa$, respectively, by size-fractionation High-Performance Liquid Chromatography (HPLC). From the High-Performance Anion-Exchange Chromatography-Pulsed Amperometric Detection (HPAEC-PAD) analysis, the main monosaccharide was galactose with glucose and fucose as minor components. The sulfate content of SP2 (40.4%) was slightly higher than that of SP1 (33.8%). The FT-IR spectra also showed characteristic band of carrageenan-like sulfated polysaccharides. Taken together the SPs are thought to be carrageenan-like sulfated galactan. The polysaccharides (SPs) from I. cordata exhibited weak antitumor activity against PC-3 (prostate cancer), HeLa (cervical cancer), and HT-29 (human colon adenocarcinoma). To our knowledge, this is the first data on biological activity of the Antarctic red seaweed I. cordata.