The Low Molecular Weight Alginate Production and Separation Using Chemical and Physical Method

Ha-neul JO,Kyung-du MIN,Yoo-sung CHOI,Jung-hun LEE 한국생물공학회 2014 한국생물공학회 학술대회 Vol.2014 No.4

Endothelial miR-26a regulates VEGF-Nogo-B receptor-mediated angiogenesis

( Ha-neul Jo ),( Hyesoo Kang ),( Aram Lee ),( Jihea Choi ),( Woochul Chang ),( Myeong-sok Lee ),( Jongmin Kim ) 생화학분자생물학회(구 한국생화학분자생물학회) 2017 BMB Reports Vol.50 No.7

The Nogo-B receptor (NgBR) is necessary for not only Nogo-B-mediated angiogenesis but also vascular endothelial growth factor (VEGF) -induced angiogenesis. However, the molecular mechanisms underlying the regulatory role of the VEGF-NgBR axis in angiogenesis are not fully understood. Here, we report that miR-26a serves as a critical regulator of VEGF-mediated angiogenesis through directly targeting NgBR in endothelial cells (ECs). Stimulation of ECs by VEGF increased the expression of NgBR and decreased the expression of miR-26a. In addition, miR-26a decreased the VEGF-induced migration and proliferation of ECs. Moreover, miR-26a overexpression in ECs decreased the VEGF-induced phosphorylation of the endothelial nitric oxide synthase (eNOS) and the production of nitric oxide, which is important for angiogenesis. Overall, these data suggest that miR-26a plays a key role in VEGF-mediated angiogenesis through the modulation of eNOS activity, which is mediated by its ability to regulate NgBR expression by directly targeting the NgBR 3`-UTR. [BMB Reports 2017; 50(7): 384-389]

고지방·고단순당 식이 섭취 마우스에서 토종보리수 열매의 인슐린 저항성 및 고혈당 개선 효과

최하늘(Ha-Neul Choi),조애진(Ae-Jin Jo),김하나(Ha-Na Kim),김정인(Jung-In Kim) 한국영양학회 2024 Journal of Nutrition and Health Vol.57 No.1

Purpose: Type 2 diabetes mellitus is a metabolic condition marked by persistent elevated blood sugar levels resulting from insulin resistance. The effective management of diabetes mellitus involves strict regulation of the blood glucose levels. This study examined the effects of Autumn olive (Elaeagnus umbellata Thunb.) berry (AOB) on insulin resistance and hyperglycemia using a type 2 diabetes mellitus animal model. Methods: Eight-week-old C57BL/6J mice were divided into four groups. The control group received a basal diet, while the high-fat, high-sucrose (HFHS) group was fed a HFHS diet containing 27% sucrose and 33% lard for 12 weeks. The low AOB (LAOB) and high AOB (HAOB) groups were offered a HFHS diet with a 0.5% and 1.0% AOB extract, respectively. Results: The HAOB group showed significantly lower epididymal fat pad weight than the HFHS group. The LAOB and HAOB groups showed lower serum glucose levels and homeostasis model assessment for insulin resistance values than the HFHS group, and the HAOB group has lower serum insulin levels than the HFHS group. Supplementation with HAOB decreased serum cholesterol levels significantly compared with the HFHS group. The consumption of LAOB and HAOB reduced the serum triglyceride and hepatic total lipids and triglyceride levels compared to the HFHS group. In addition, LAOB and HAOB consumption in mice fed a HFHS diet increased adenosine monophosphate-activated protein kinase protein expression. Insulin receptor substrate-2 protein expression in the HAOB group was significantly higher than the HFHS group. Conclusion: AOB can alleviate hyperglycemia in type 2 diabetes mellitus partly by mitigating insulin resistance.

The catalytic role of additive components for the nitridation of silicon/additive mixture

KIM, Ha-Neul,PARK, Young-Jo,KIM, Jin-Myung,LEE, Jae-Wook,KO, Jae-Woong,KIM, Hai-Doo,LEE, Seung-Jun,BAEK, Seung-Su,SEO, Il-Sung Ceramic Society of Japan 2016 JOURNAL OF THE CERAMIC SOCIETY OF JAPAN - Vol.124 No.3

<P>The nitriding behavior of silicon/additives mixture with varied composition was investigated by focusing on the catalytic effect of sintering additives (Y2O3 and Al2O3) and diluents (Si3N4). While sintering additives have originally been mixed to form a liquid phase to promote both densification and grain growth during post-sintering, it was revealed that the addition of Y2O3 enhances the nitriding reaction by eliminating the SiO2 and Si3N4 layer on the surface of silicon particles. Further, a synergistic effect resulting in an increased nitridation was verified by concurrent addition of sintering additives and diluents. The contribution of each component of the compact to the promoted nitriding reaction was elucidated in quasi in-situ manner by the combination of phase analysis and thermogravimetric analysis. (C) 2016 The Ceramic Society of Japan. All rights reserved.</P>

질화규소 세라믹스 소재 리뷰

김하늘(Ha-Neul Kim),박영조(Young-Jo Park),고재웅(Jae-Woong Ko),이재욱(Jae-Wook Lee),마호진(Ho-Jin Ma) 한국세라믹학회 2023 세라미스트 Vol.26 No.2

As the heat generation problem is predicted to intensify due to the trend of integration and high density of the power semiconductor power module responsible for the electric drive of the electric vehicle, which has recently been in full swing, high-reliability materials and It is essential to secure large-area heat dissipation substrate manufacturing process technology, and technical obstacles to maintain reliability even in environmental changes such as severe cold/excessive heat are becoming issues. In the case of silicon nitride ceramic material, which is in the spotlight as a heat dissipation substrate material, a balance that meets the user’s needs is required. In order to realize excellent heat dissipation performance, it is necessary to reduce the thickness of the silicon nitride substrate, increase the thickness of the metal junction, and improve the thermal conductivity of the silicon nitride material. Therefore, the task of technological progress beyond the complementary relationship between heat conduction-intensity still remains. In this paper, various technical considerations for increasing the thermal conductivity of silicon nitride ceramics are described, and the direction of technological progress is described along with detailed examples. In order to improve thermal conductivity, it is necessary to minimize the inflow of impurities into the raw material powder, appropriately select sintering additives required for liquid phase sintering, and optimize the microstructure through minimization of the amorphous glass phase and control of grain growth by the gas pressure sintering process.

Characterization of porous sintered reaction-bonded silicon nitride containing three different rare-earth oxides

Kim Ha-Neul,Kim Mi-Ju,Park Young-Jo,Ko Jae-Woong 한국세라믹학회 2021 한국세라믹학회지 Vol.58 No.1

The eff ect of rare-earth oxides on the characteristics of porous sintered reaction-bonded silicon nitride (SRBSN) was investigated. Three types of raw Si powder mixtures containing diff erent rare-earth oxide (La 2 O 3 , Er 2 O 3 , and Yb 2 O 3 ) were prepared and nitrided in the form of compacts. The nitriding profi les of the respective raw powder mixtures with elevating temperature indicated that Yb 2 O 3 clearly promoted the nitridation of Si compacts at low temperature compared with other rare-earth oxides, and the β-Si 3 N 4 ratio after completion of the nitriding reaction was diff erent at which temperature the major nitridation occurred. Yb 2 O 3 was found to be the most eff ective additive to achieve a strong porous SRBSN, having the fl exural strength of 441 MPa. The reason why Yb 2 O 3 promotes the nitridation reaction and has excellent mechanical properties after post-sintering is that oxygen was removed during the nitriding reaction, which was supported by the analysis of oxygen content via the laser-induced breakdown spectroscopy.

레이저 발진용 투명세라믹의 발전사 및 국내/외 연구 동향

김하늘(Ha-Neul Kim),고재웅(Jae-Woong Ko),박영조(Young-Jo Park),오현명(Hyeon-Myeong Oh),이현권(Hyun-Kwuon Lee) 한국세라믹학회 2020 세라미스트 Vol.23 No.3

The most valuable application of transparent ceramics is the laser crystal for the solid-state laser. Especially, since a large-area laser crystal cannot be realized by the single crystal due to the inhomogeneous segregation of laser generating element, the transparent ceramics is considered as the most appropriate material for the high intensity solid-state laser system. In order to generate the laser from the transparent ceramics effectively, it is necessary to remove every single pore for the nearly theoretical inline transmittance as well as to make the ceramics highly durable against the thermal shock induced by heat generation. In this article, while briefly looking back on the global development history of solid-state lasers, we would like to discuss the recent trend of research on transparent ceramics for the solid-state laser in Korea and the direction of future technology development.

추천 시스템에 의한 필터 버블 개선 방향 제시 : 유투브를 통해서

조성재(Sung-Jae Jo),이근희(Geun-Hee Lee),전경향(Gyeong-Hyang Jun),허수진(Su-Jin Hur),김하늘(Ha-Neul Kim),김성희(Sung-Hee Kim) 한국HCI학회 2020 한국HCI학회 학술대회 Vol.2020 No.2

추천 시스템은 개인화 알고리즘을 이용해 사용자의 선호도에 부합하는 서비스나 콘텐츠를 제공하는 것으로 상품이나 영화, 음악 등 다양한 서비스에 활용되고 있다. 하지만 이러한 추천 시스템은 사용자에게 맞춤형 정보를 제공한다는 장점도 있지만, 이미 필터링 된 정보만을 접하게 되어 자기도 모르는 사이에 정보 편식을 하게 되는 필터버블(filter bubble) 현상을 경험할 수도 있다. 필터버블은 제공되는 정보가 사용자의 견해를 편협하게 함으로써 사회적 문제를 해결하는 데 어려움을 겪을 수 있다는 문제점이 있다. 본 논문은 추천 시스템에 의한 필터 버블 현상을 개선하기 위해서 사용자의 추천 시스템에 대한 인식을 설문을 통해 알아보았다. 그 결과 추천 시스템에 의해 제공되는 정보의 다양성이 제한되어 필터 버블이 발생할 가능성을 확인할 수 있었고, 사용자 또한 추천 시스템의 다양성이 부족하다는 문제점에 대해 공감을 나타냈다. 본 논문은 필터 버블 현상이 발생할 가능성과 추천 시스템의 다양성이 부족하다는 문제점을 밝혔다는 점에서 의의를 가진다.

Improved thermal conductivity of sintered reaction-bonded silicon nitride using a BN/graphite powder bed

Li, Yinsheng,Kim, Ha-Neul,Wu, Haibo,Kim, Mi-Ju,Ko, Jae-Woong,Kim, Jin-Myung,Park, Young-Jo,Huang, Zhengren,Kim, Hai-Doo Elsevier Science Publishers 2017 Journal of the European Ceramic Society Vol. No.

<P><B>Abstract</B></P> <P>Sintered reaction-bonded silicon nitride (SRBSN) with improved thermal conductivity was achieved after the green compact of submicron Si powder containing 4.22wt% impurity oxygen and Y<SUB>2</SUB>O<SUB>3</SUB>-MgO additives was nitrided at 1400°C for 6h and then post-sintered at 1900°C for 12h using a BN/graphite powder bed. During nitridation, the BN/10wt%C powder bed altered the chemistry of secondary phase by promoting the removal of SiO<SUB>2</SUB>, which led to the formation of larger, purer and more elongated Si<SUB>3</SUB>N<SUB>4</SUB> grains in RBSN sample. Moreover, it also enhanced the elimination of SiO<SUB>2</SUB> and residual Y<SUB>2</SUB>Si<SUB>3</SUB>O<SUB>3</SUB>N<SUB>4</SUB> secondary phase during post-sintering, and thus induced larger elongated grains, decreased lattice oxygen content and increased Si<SUB>3</SUB>N<SUB>4</SUB>-Si<SUB>3</SUB>N<SUB>4</SUB> contiguity in final SRBSN product. These characteristics enabled SRBSN to obtain significant increase (∼40.7%) in thermal conductivity from 86 to 121 W∙m<SUP>−1</SUP> ∙K<SUP>−1</SUP> without obvious decrease in electrical resistivity after the use of BN/graphite instead of BN as powder bed.</P>

Highly transparent Nd-doped yttria ceramics fabricated by hot pressing with ZrO₂ and La₂O₃ as sintering additives

Gan, Lin,Park, Young-Jo,Zhu, Lin-Lin,Kim, Ha-Neul,Ko, Jae-Woong,Lee, Jae-Wook Elsevier 2018 JOURNAL OF ALLOYS AND COMPOUNDS Vol.763 No.-

<P><B>Abstract</B></P> <P>Highly transparent Nd-doped yttria ceramics were fabricated by hot-pressing at 1600 °C with single addition and co-addition of ZrO<SUB>2</SUB> and La<SUB>2</SUB>O<SUB>3</SUB>. The binary additives were found to promote the densification of yttria more effectively than single addition, resulting in higher transmittance. The highest transmittance was obtained in the sample with 1 at.% ZrO<SUB>2</SUB> and 3 at.% La<SUB>2</SUB>O<SUB>3</SUB>, which reached 74.3% transparency at a wave length of 400 nm and 81.3% at 1100 nm. The optical absorption, luminescence, and fluorescence decay of this sample was investigated. The absorption cross-sections of the sample at 806 nm and 820 nm were 1.22 × 10<SUP>−20</SUP> and 1.31 × 10<SUP>−20</SUP> cm<SUP>2</SUP>, respectively. The strongest emission was measured at 1078 nm with a full-width at half-maximum of 5 nm with excitation at 808 nm and a fluorescence lifetime of 423 μs. Additionally, the microhardness of the all samples is ranging from 7.88 to 7.05 GPa with variation of the grain size from 0.85 to 1.81 μm, while the fracture toughness of the all samples is about 1 MPa m<SUP>1/2</SUP> and was found to be almost unchanged. These results have demonstrated that Nd-doped yttria ceramics for the application of laser gain media can be fabricated by hot-pressing.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Highly transparent Nd-doped yttria ceramics fabricated by hot-pressing. </LI> <LI> Effects of ZrO<SUB>2</SUB>-La<SUB>2</SUB>O<SUB>3</SUB> additives on the samples were studied. </LI> <LI> The optical and mechanical properties of the samples were studied. </LI> </UL> </P>