• 한국약용작물학회지
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• 제21권5호
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• pp.401-414
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• 2013

Ginsenoside Rg3 (G-Rg3) contained only in red ginseng has been found to show various pharmacological effects such as an anticancer, antiangiogenetic, antimetastastic, liver protective, neuroprotective immunomodulating, vasorelaxative, antidiabetic, insulin secretion promoting and antioxidant activities. It is well known that G-Rg3 could be divided into 20(R)-Rg3 and 20(S)-Rg3 according to the hydroxyl group attached to C-20 of aglycone, whose structural characteristics show different pharmacological activities. It has been reported that G-Rg3 is metabolized to G-Rh2 and protopanaxadiol by the conditions of the gastric acid or intestinal bacteria, thereby these metabolites could be absorbed, suggesting its absolute bioavailability (2.63%) to be very low. Therefore, we reviewed the chemical, physical and biological transformation methods for the production on a large scale of G-Rg3 with various pharmacological effects. We also examined the influence of acid and heat treatment-induced potentials on for the preparation method of higher G-Rg3 content in ginseng and ginseng products. Futhermore, the microbial and enzymatic bio-conversion technologies could be more efficient in terms of high selectivity, efficiency and productivity. The present review discusses the available technologies for G-Rg3 production on a large scale using chemical and biological transformation.

• 한국재료학회지
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• 제16권10호
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• pp.624-628
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• 2006

In this study, divalent europium-activated $NaCaPO_4$ green phosphor powders were prepared by the chemical synthetic method followed by heat treatment in reduced atmosphere, and the crystal structures, morphologies and photoluminescent properties of the powders were investigated by x-ray powder diffraction, scanning electron microscope and spectrometer for the first time. The effects of Ca/P and Na/Ca mole ratios on the final products were also investigated. The influences of input amount change of europium as the activator on the light emission intensity were studied, and the resulting concentration quenching phenomenon was observed. The optimized synthesis conditions obtained in this study were Ca/P mole ratio 1.2, Na/Ca mole ratio 3.0 and 4 mole%Eu. The peak wavelength was 505 nm for all the samples. The result of excitation spectrum measurement indicated that the excitation efficiency was high for the long-wavelength UV region. It was thus concluded that the samples prepared in this study can be successfully applied for the light-emitting devices such as LED excited with long-wavelength UV light sources.

• 한국재료학회지
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• 제12권7호
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• pp.517-521
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• 2002

Europium-activated $Ga_2$$O_3$ phosphor powders were prepared by Pechini method from the mixed aqueous solutions of gallium(III) nitrate, europium(III) nitrate, ethylene glycol and citric acid. The phase formation process and particle shape of the powders obtained were investigated by means of TG/DTA, XRD and SEM. It was found that the powders were amorphous or ${\gamma}$-$Ga_2$$O_3$-like phase up to $500^{\circ}C$ and then transformed into $\beta$- $Ga_2$$O_3$ phase above $600 ^{\circ}C$. The powders calcined below $1000^{\circ}C$ were spherical and nanometer-sized. Photoluminescence spectra measured at room temperature showed that the highest luminescence intensity was obtained for the sample synthesized under the conditions of 2 mol% Eu concentration and heat treatment at $1000^{\circ}C$.

• Corrosion Science and Technology
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• 제20권2호
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• pp.77-84
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• 2021

This study aims to optimize the DL-EPR test solution for duplex stainless steel S31083 using the Taguchi design. The test solution parameters applied to the Taguchi design are H₂SO₄, NaCl, KSCN concentration, and temperature. In the experimental design, an orthogonal array of 4 levels 4 factor L₁₆(4⁴) was used. Output values for the orthogonal array were used for resolution (degree of sensitization) and selective etch (I_a) values. The optimal test solution conditions were selected by comparing the normalized S/N ratio for the two reaction properties. As a result, the H₂SO₄ and NaCl were identified as the main factors influencing the sensitivity measurement, but the delta statistics showed that the KSCN concentration and temperature had relatively low influence. The optimal condition was identified as 1.5 M H₂SO₄+0.03 M KSCN+1.5M NaCl at 30 ℃. The degree of sensitization presented a tendency to depend on the heat treatment temperature and time in the optimal test solution. This investigation confirmed the possibility of optimizing the experiment solution for the DL-EPR test of stainless steel using the Taguchi technique.

• 한국축산식품학회지
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• 제41권2호
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• pp.261-273
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• 2021

Leuconostoc mesenteroides H40 (H40) was isolated from kimchi, and its probiotic properties and neuroprotective effect was evaluated in oxidatively stressed SH-SY5Y cells. H40 was stable in artificial gastric conditions and can be attached in HT-29 cells. In addition, H40 did not produce β-glucuronidase and showed resistant to several antibiotics. The conditioned medium (CM) was made using HT-29 cells refined with heat-killed probiotics (Probiotics-CM) and heated yogurts (Y-CM) to investigate the neuroprotective effect. Treatment with H40-CM not only increased cell viability but also significantly improved brain derived neurotropic factor (BDNF) expression and reduced the Bax/Bcl-2 ratio in oxidatively stress-induced SH-SY5Y cells. Besides, probiotic Y-CM significantly increased BDNF mRNA expression and decreased Bax/Bcl-2 ratio. The physicochemical properties of probiotic yogurt with H40 was not significantly different from the control yogurt. The viable cell counts of lactic acid bacteria in control and probiotic yogurt with H40 was 8.66 Log CFU/mL and 8.96 Log CFU/mL, respectively. Therefore, these results indicate that H40 can be used as prophylactic functional dairy food having neuroprotective effects.

• 한국염색가공학회지
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• 제34권4호
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• pp.217-223
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• 2022

Flame-retardant finished silk fabrics could release carcinogenic formaldehyde resulting from the conventional finishing agents. New water-soluble cyclophosphazene derivative can be used as a formaldehyde-free flame retardant for the silk protein. Dichloro tetrakis{N-[3-dimethylamino)propyl]methacrylamido}cyclophosphazene(DCTDCP) can be cured by heat or UV irradiation as a durable flame retardant for the silk fabrics. Treatment conditions were optimized including curing temperature and time, finishing formulations, and UV energy. At the 30% DCTDCP application, peak HRR and THR decreased by 42.6% and 49.6% respectively compared to the pristine silk fabrics. Also char residue increased up to 48% from 11% indicating solid-phase retarding mechanism. The flame-retardant silk fabrics showed a LOI of 31.1 and the washed sample maintained a LOI of 26.8 even after ten laundering cycles.

• 한국표면공학회지
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• 제56권4호
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• pp.259-264
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• 2023

As the demand for lithium-ion batteries, a key power source in electric vehicles and energy storage systems, continues to increase for achieving global carbon neutrality, there is a growing concern about the environmental impact of disposing of spent batteries. Extensive research is underway to develop efficient recycling methods. While hydrometallurgy and pyrometallurgy methods are commonly used to recover valuable metals from spent cathode materials, they have drawbacks including hazardous waste and complex processes. Hence, alternative recycling methods that are environmentally friendly are being explored. However, recycling spent cathode materials still remains complex and energy-intensive. This study focuses on a novel approach called solid-state synthesis, which aims at regenerating the performance of spent cathode materials. The method offers a simpler process and reduces energy consumption. Optimal heat treatment conditions were identified based on experimental results, contributing to the development of sustainable recycling technologies for lithium-ion batteries.

• 한국표면공학회지
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• 제56권4호
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• pp.265-272
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• 2023

Photoelectrochemical (PEC) water splitting is one of the promising methods for hydrogen production by solar energy. Iron oxide has been effectively investigated as a photoelectrode material for PEC water splitting due to its intrinsic property such as short minority carrier diffusion length. However, iron oxide has a low PEC efficiency owing to a high recombination rate between photoexcited electrons and holes. In this study, we synthesized nanoporous structured iron oxide by anodization to overcome the drawbacks and to increase surface area. The anodized iron oxide was annealed in Ar atmosphere with different purging times. In conclusion, the highest current density of 0.032 mA/cm² at 1.23 V vs. RHE was obtained with 60 s of pursing for iron oxide(Fe-60), which was 3 times higher in photocurrent density compared to iron oxide annealed with 600 s of pursing(Fe-600). The resistances and donor densities were also evaluated for all the anodized iron oxide by electrochemical impedance spectra and Mott-Schottky plot analysis.

• 한국초전도ㆍ저온공학회논문지
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• 제11권1호
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• pp.5-8
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• 2009

MgO nanodots have been deposited and formed on top of the substrate surface. Mg was sputtered to form the MgO nanodots on the single crystal substrates by rf-sputtering method and followed by heat treatment in the oxygen ambient. The deposition and formation of MgO nanodots have been controlled systematically using the process variables such as substrate temperature, sputtering time, and rf-power. As the substrate temperature increased from the room temperature the density of MgO nanodots decreased. The optimal conditions of MgO nanodots formation using the rf-sputtering was investigated and the maximum density of more than $230/{\mu}m^2$ on single crystal substrates was obtained when the rf-power of 100 watts was applied for 30 seconds at room temperature. The typical size of MgO nanodots was identified to be <160 nm(diameter) and 4-30nm (height) by atomic force microscopy. The modulated surface morphology was examined through surface images and cross-section analysis and discussed for the artificial pinning sites in the superconducting films.

• 한국가금학회지
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• 제38권3호
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• pp.213-223
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• 2011

본 연구는 매실박과 홍삼박을 사료에 첨가하여 육계 체내 생리활성 효과를 구명하고자 실시하였으며, 이를 위해 고온 스트레스 자극과 LPS 염증 반응을 유도하여 스트레스에 대한 반응을 조사하였다. 이를 위해 고온 스트레스 자극에 따른 생산성 및 혈액생화학 변화를 조사하였으며, LPS로 염증 반응이 유도된 육계에서 immunoglobulin 농도 및 비장 조직내 cytokine mRNA 발현을 조사하였다. 공시계로는 1일령 Ross종 육계수컷 192수를 선별하여 고온 환경(96수)과 일반 환경(96수)으로 구분하였다. 고온 환경은 불쾌지수 86($33^{\circ}C$, 75%)의 고온 스트레스를 자극하여 5주간의 사양 시험을 실시하였으며, 일반 환경은 5주간의 사양 시험 종료 후 LPS를 주입하였다. 환경에 따라 각각 처리당 24수(3수${\times}$8반복)씩 4처리구에 총 96수를 임의 배치하여 실시하였다. 시험구 배치는 무첨가구(negative control; C), 시판 면역 증강제 첨가구(positive control: PC, 25 ppm ${\beta}$-glucan), 매실 부산물 1% 첨가구(PM: plum marc), 홍삼 부산물 3%(RGM: red gingeng marc)로 배치하였다. 고온 스트레스에 대한 혈액생화학 조성에서 매실박 첨가구는 Mg 농도를 높게 유지하여 Ca/Mg 비율을 무첨가구보다 낮게 유지하였으며, 홍삼박 첨가구는 Mg 농도가 무첨가구와 같았지만, Ca 농도를 높여 Ca/Mg 비율을 무첨가구보다 낮게 유지하였다(P<0.05). 따라서 매실박과 홍삼박 첨가구는 고온 환경에서 무첨가구보다 C a/Mg 비율을 낮게 유지하여, Ca/Mg 비율과 정의 상관관계에 있는 cholesterol 수준을 낮추는데 긍정적으로 작용할 것이라 사료된다. LPS 접종 후 IgM 농도는 매실박 첨가구가 무첨가구에 비해 유의적으로 낮은 수준을 나타내었으며(P<0.05), 홍삼박 첨가구는 무첨가구에 비해 낮은 경향을 나타냈지만 유의적인 차이는 없었다. 또한 비장 조직 내 cytokine mRNA 발현에서 홍삼박 첨가구의 경우 공통적으로 IL-1, IL-2 및 IL-6의 mRNA 발현 비율이 무첨가구에 비해 유의적으로 낮았으며, 매실박 첨가구도 IL-1, IL-2에서 무첨가구와 베타글루칸 첨가구보다 낮게 나타났다(P<0.05). 따라서 육계에서 매실박은 LPS 감염 시 IL-1, IL-2 같은 친염증 사이토카인의 발현을 감소시킴으로 염증 반응을 줄여 IgM 상승을 억제하는 것으로 사료된다. 홍삼박 첨가구의 경우 친염증성 사이토카인 억제 효과가 높았지만 항체 농도는 무첨가구와 같은 수준으로 상승하였는데, 생산성, 면역 반응을 개선할 수 있는 첨가 수준에 대한 추가적인 연구가 필요할 것으로 사료된다. 또한 이 실험에서 양성 대조군으로 활용한 ${\beta}$-glucan 전체적으로 긍정적인 효과를 보이지 않았는데, 양성 대조군 활용 시 첨가 수준에 대한 세밀한 검토가 필요할 것으로 사료된다. 결론적으로 매실박과 홍삼박은 고온 스트레스와 외부 병원성 물질 자극에 대한 반응을 최소화하는데 긍적적으로 작용하는 것으로 사료된다.