• 한국응용과학기술학회지
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• 제24권1호
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• pp.1-9
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• 2007

It prepared the $TiO_2$ powder which has photo-catalytic activity in the visible-light by the wet process with titanium oxysulfate. The titanium $dioxide(TiO_2)$ by the wet process creates a new absorption band in the visible light region, and is expected to create photocatalytic activity in this region. Anatase $TiO_2$ powder which has photocatalytic activity in the visible light region, is treated using microwave and radio-frequency(RF) plasma. But, the $TiO_2$ powder for the visible light region, which also can be easily produced by wet process. The wet process $TiO_2$ absorbed visible light between 400nm and 600nm, and showed a high activity in this region, as measured by the oxidation removal of aceton from the gas phase. The AH-380 sample appears the yellow color to be strong, the catalytic activity in the visible ray was excellent in comparison with the plasma-treated $TiO_2$. The AH-380 $TiO_2$ powder, which can be easily produced on a large scale, is expected to have higher efficiency in utilizing solar energy than the plasma-treated $TiO_2$ powder.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 제13회 신호처리 합동 학술대회 논문집
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• pp.109-112
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• 2000

An algorithm for the reduction of blocking artifacts is pro-posed. Instead of filtering the pixels by a digital filter, the proposed algorithm considers the compressed image as continuous-time ,signal and replaces it by a pre-designed lowpass filter outputs. The algorithm shows better performance than the conventional methods in low activity region, and comparable or a little worse objective performance in high activity region. Hence, by applying the proposed algorithm to the low activity region and the conventional ones to the high activity region, the objective and subjective performances are improved in most cases.

• Plant Resources
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• 제1권1호
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• pp.60-79
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• 1998

In this review we summarize the isolation, structural determination, antitumor activity of substances from higher plants which were collected in Asian region.

• The Korean Journal of Physiology and Pharmacology
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• 제1권5호
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• pp.477-484
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• 1997

Intracellular recordings of oscillatory firing (bursting activity) were obtained from Purkinje cells (PCs) in rat cerebellar slices. Apamin inhibited post-burst hyperpolarizations (PBHs) progressively and finally terminated oscillatory firing activity of PCs. Apamin did not affect the amplitude or duration of the after-hyperpolarization (AHP) between spikes within the burst. In the voltage clamp mode, apamin shifted the whole-cell, quasi-steady state I/V relationship in an inward direction and abolished the zero slope resistance (ZSR) region by blocking outward current. Nickel ($Ni^{2+}$) terminated oscillatory activity and also abolished the ZSR region. However, $Ni^{2+}$ did not have progressive blocking action on the post-burst hyperpolarization before it blocked oscillatory activity. $Ni^{2+}$ blocked an inward current at potentials positive to approximately -65 mV, which was responsible for the ZSR region and outward current at more negative potentials. These data indicated that oscillatory activity of PCs is sustained by a balance between a slow $Ni^{2+}$-sensitive inward current and an apamin-sensitive outward current in the region of ZSR of the whole-cell I/V curve.

• Bulletin of the Korean Chemical Society
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• 제20권9호
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• pp.1078-1084
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• 1999

A synthetic cecropin A(1-13)-melittin(1-13) [CA-ME] hybrid peptide was known to be an antimicrobial peptide having strong antibacterial, antifungal and antitumor activity with minimal cytotoxic effect against human erythrocyte. Analogues were synthesized to investigate the influences of the flexible hinge region of CA-ME on the antibiotic activity. Antibiotic activity of the peptides was measured by the growth inhibition against bac-terial, fungal and tumor cells and vesicle-aggregating or disrupting activity. The deletion of Gln-Gly-Ile (P1) or Gly-Gln-Gly-Ile-Gly (P3) from CA-ME brought about a significant decrease on the antibiotic activities. In contrast, Gly-Ile-Gly deletion (P2) from CA-ME or Pro insertion (P5) instead of Gly-Gln-Gly-Ile-Gly of CA-ME retained antibiotic activity. This result indicated that the flexible hinge or β-bend structure provided by Gly-Gln-Gly-Ile-Gly, Gln-Gly, or Pro in the central region of the peptides is requisite for its effective antibiotic activity and may facilitate easily the hydrophobic C-terminal region of the peptide to penetrate the lipid bilayers of the target cell membrane. In contrast, P4 and P6 with Gly-Gln-Gly-Pro-Gly or Gly-Gln-Pro in the central region of the peptide caused a drastic reduction on the antibiotic activities. This result suggested that the con-secutive β-bend structure provided by Gly-Gln-Gly-Pro-Gly or Gly-Gln-Pro in the central hinge region of the peptide seems to interrupt the ion channel/pore formation on the target cell membranes.

• 한국축산식품학회지
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• 제37권3호
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• pp.402-409
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• 2017

A novel peptide having free radical scavenging activity was separated, using an on-line high-performance liquid chromatography (HPLC) - ABTS screening method, from bovine skim milk fermented by Lactococcus lactis SL6 (KCTC 11865BP). It was further purified using reverse phase-HPLC (RP-HPLC) and sequenced by RP-HPLC-tandem mass spectrometry. The amino acid sequence of the identified peptide was determined to be Phe-Ser-Asp-Ile-Pro-Asn-Pro-Ile-Gly-Ser-Glu-Asn-Ser-Glu-Lys-Thr-Thr-Met-Pro-Leu-Trp (2,362 Da), which is corresponding to the C-terminal fragment of bovine ${\alpha}_{s1}$-casein (f179-199). The hydroxyl radicals scavenging activity ($IC_{50}$ $28.25{\pm}0.96{\mu}M$) of the peptide chemically synthesized based on the MS/MS data showed a slightly lower than that of the natural antioxidant Trolox ($IC_{50}$ $15.37{\pm}0.52{\mu}M$). Furthermore, derivatives of the antioxidant peptide were synthesized. The antioxidative activity of the derivatives whose all three proline residues replaced by alanine significantly decreased, whereas replacement of two proline residues in N-terminal region did not affect its antioxidative activity, indicating that $3^{rd}$ proline in C-terminal region is critical for the antioxidative activity of the peptide identified in this study. In addition, N-terminal region of the antioxidant peptide did not show its activity, whereas C-terminal region maintained antioxidative activity, suggesting that C-terminal region of the peptide is important for antioxidative activity.

• Journal of Microbiology and Biotechnology
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• 제34권5호
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• pp.1135-1145
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• 2024

When cells are exposed to freezing temperatures, high concentrations of cryoprotective agents (CPA) prevent ice crystal formation, thus enhancing cell survival. However, high concentrations of CPAs can also cause cell toxicity. Exopolysaccharides (EPSs) from polar marine environments exhibit lower toxicity and display effects similar to traditional CPA. In this study, we sought to address these issues by i) selecting strains that produce EPS with novel cryoprotective activity, and ii) optimizing culture conditions for EPS production. Sixty-six bacteria producing mucous substances were isolated from the Ross Sea (Antarctic Ocean) using solid marine agar plates. Among them, Pseudoalteromonas sp. RosPo-2 was ultimately selected based on the rheological properties of the produced EPS (p-CY02). Cryoprotective activity experiments demonstrated that p-CY02 exhibited significantly cryoprotective activity at a concentration of 0.8% (w/v) on mammalian cells (HaCaT). This activity was further improved when combined with various concentrations of dimethyl sulfoxide (DMSO) compared to using DMSO alone. Moreover, the survival rate of HaCaT cells treated with 5% (v/v) DMSO and 0.8% (w/v) p-CY02 was measured at 87.9 ± 2.8% after freezing treatment. This suggests that p-CY02 may be developed as a more effective, less toxic, and novel non-permeating CPA. To enhance the production of EPS with cryoprotective activity, Response Surface Methodology (RSM) was implemented, resulting in a 1.64-fold increase in production of EPS with cryoprotective activity.

• Asian-Australasian Journal of Animal Sciences
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• 제24권10호
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• pp.1372-1376
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• 2011

The content of Ca in milk exceeds the typical saturation level of Ca salts, which is necessary for neonate growth. This calcium is distributed between the casein micelles in the colloidal and aqueous phases. Information on the properties of calcium activity in the aqueous phase is limited compared with that on the properties of bound or sequestrated calcium. The objectives of this study were to evaluate the changes in calcium activity in fresh milk using an ion-selective electrode and to assess the relationship between calcium activity and milk production in hot season. Milk samples collected from 10 cows at the National Agricultural Research Center for Kyushu Okinawa Region in June to October (Min-Max: 7.2-$35.2^{\circ}C$, 24.3-100% RH) were analyzed on total calcium concentrations and calcium activity. We observed that the rectal temperature of the cows increased according to elevation of ambient temperature but that the pH of the collected milk ($6.61{\pm}0.01$ (Mean${\pm}$SEM)) was not significantly influenced by rectal and ambient temperature. Total calcium concentrations and calcium activity in fresh milk decreased in July (Min-Max: 21.1-$33.5^{\circ}C$, 48.9-100.0% RH) compared with the values after August (Min-Max: 18.1-$35.0^{\circ}C$, 26.5-96.2% RH) (p<0.05); however, there was no significant correlation between the two parameters. The ratio of calcium activity to total calcium concentration decreased after August compared with the values in June and July (p<0.05). The calcium activity in fresh milk was positively correlated with milk yield (r = 0.45, p<0.01) and negatively correlated with milk lactose content (r = -0.53, p<0.01). These results suggest that the calcium activity in milk could be affected by ambient temperature and might be associated with milking production in hot season.

• 지역연구
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• 제11권1호
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• pp.31-60
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• 1995

The distribution of economic activity over a mutually exclusive and exhaustive categorical industry-region matrix is modeled as a composition of two random components: the probability-like share distribution of jobs and the dynamic evolution of absolute aggregates. The former describes the individual activity location choice by comparing the predicted profitability of the current industry-region pair against that of all other alternatives based on the available information on industry-specific, region specific, or activity specific attributes. The latter describes the time evolution of macro-level aggregates using a dynamic reduced from model. With the seperation of micro choice behavior and macro dynamic aggregate constraint, the usual independence and identicality assumptions become consistent with the activity share distribution, hence multi-regional industrial migration can be represented by a set of probability evolution equations in a conservative Markovian from. We call this a Micro-Macro Composition Approach since the product of the aggregate prediction and the predicted activity share distribution gives the predicted activity distribution gives the predicted activity distribution which explicitly considers the underlying individual choice behavior. The model can be applied to interesting practical problems such as the plant location choice of multinational enterprise, the government industrial ploicy to attract international firms, and the optimal tax-transfer mix to influence activity location choice. We consider the latter as an example.

• Preventive Nutrition and Food Science
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• 제8권1호
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• pp.61-65
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• 2003

This study was investigated to identify the regulatory mechanism of ACC gene expression by hormones and nutrition. The fragment of ACC promoter I (PI) -220 bp region was recombined to pGL3-Basic vector with luciferase as a reporter gene. The primary hepatocyte from the rat was used to investigate the regulation of ACC PI activity. ACC PI (-220 bp)/luciferase chimeric plasmid was transfected into primary rat hepatocyte by using lipofectin. ACC PI activity was shown by measuring luciferase activity. The addition of insulin, dexamethasone, and triiodothyronine to the culture medium increased the activity of ACC PI by 2.5-, 2.3- and 1.8-fold, respectively. In the presence of 1 $\mu$M dexamethasone, the effects of insulin was amplified about 1.2-fold showing the additional effects of dexamethasone. Moreover the activity of luciferase was increased by insulin, dexamethasone, and triiodothyronine treatment approximately 4-fold. These results indicated that insulin, dexamethasone and thyroid hormone coordinately regulate ACC gene expression via regulation of promoter I activity. On the -220 to ＋21 region of ACC PI, the addition of the glucose to the culture medium increased the activity of ACC PI. With 25 mM glucose, luciferase activity increased by 7-fold. On the other hand, on the -220 bp region, ACC PI activity was not changed by polyunsaturated fatty acids. Therefore, it can be postulated that there are response elements for insulin, triiodothyronine, dexamethasone, and glucose, but not PUFAs on the -220 bp region of ACC PI.