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Consideration of Diluents Selection and Input Amounts of the Hunter Process for Tantalum Production
Jae‑Jin Sim,Sang‑Hoon Choi,Yong‑Kwan Lee,Sung Gue Heo,Taek‑Soo Kim,Seok‑Jun Seo,Kyoung‑Tae Park 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.7
Tantalum (Ta) is a heavy refractory metal with an atomic weight of 180.95 g/mol, a density of 16.6 g/cm3, and a high meltingpoint of 3017 °C. With its refractory characteristics, it shows excellent chemical and physical stability as well as corrosionand heat resistance at elevated temperatures. The demand for Ta metal and related compounds is increasing with the expansionof the electronics and chemical industries. The Hunter process was proven to be effective in producing Ta powder in1953. Hunter proposed a method in which potassium heptafluorotantalate (K2TaF7) was reduced by sodium (Na). Thus far,this process has been the primary commercial method to produce Ta powder. In this study, quantitative differences wereanalyzed for diluent selection. Additionally, consideration was given to changes in the caloric value depending on the inputamount of diluents. Finally, the optimum material input and the properties of the prepared Ta were analyzed. Stoichiometricratios of K2TaF7(1 mol), NaCl (6.2–6.7 mol), Na (5–7 mol) were weighed, to perform a metallothermic reduction reaction. After the reaction, the tantalum powder was recovered and the flush process was carried out. After that, it was dried in avacuum atmosphere. Physical properties such as oxygen concentration, PSA, ICP-OES, and XRD of powder were conductedto evaluate the characteristics of Ta powder that was finally manufactured.
김대중,박상태,정재욱,허훈,Kim, Dae-Jung,Park, Sang-Tae,Jeong, Jae-Uk,Heo, Hun 대한기계학회 1999 大韓機械學會論文集A Vol.23 No.11
A Newly proposed control methodology applied to the aeroelastic system experiencing flutter is investigated and its performance is verified experimentally. The flexible cantilever beam slicked with piezofilm sensor and piezoceramic actuator is modelled in physical domain. Dynamic moment equation for the system is derived via Ito's stochastic differential equation and F-P-K equation. Also system's characteristics in stochastic domain is analyzed simultaneously. LQG controller is designed and used in physical and stochastic domain. It is shown experimentally that the vibration of beam is controlled effectively by designed LQG controller in physical domain. By comparing the result with that of LQG controller designed in stochastic domain, it is shown that the new control method, called Heo-stochastic control technique, has better performance as a controller.
Tissue distribution of LOM strain viral antigens using immunohistochemistry in weaned pigs in Jeju
Jae-Sung Heo(Jae-Sung Heo),Jae-Beum Kim(Jae-Beum Kim),Yun-Ho Kim(Yun-Ho Kim),Hyoung-Nam Jo(Hyoung-Nam Jo),Won-Gyu Cho(Won-Gyu Cho),Myeong-Won Suh(Myeong-Won Suh),Hyoung-Seok Yang(Hyoung-Seok Yang),Wan 한국예방수의학회 2019 한국예방수의학회 학술대회자료집 Vol.2018 No.-
Jae-Young Cha(차재영),Hee-Young Ahn(안희영),Su-Jin Heo(허수진),Sang-Hyun Park(박상현),Yong-Kee Jeong(정영기),Young-Su Cho(조영수) 한국생명과학회 2011 생명과학회지 Vol.21 No.9
동충하초의 다양한 생리 활성 물질들 중 cordycepin의 함량을 측정한 결과 육종된 번데기 동추하초(Cordyceps militaris JLM 0636)가 7.42 mg/g으로 시판의 번데기 동충하초보다 최고 7배 정도 높게 나타났으며 눈꽃 동충하초는 cordycepin이 검출되지 않았다. Cordycepin 고함유 번데기 동충하초의 지방간 개선효과를 검토하기 위해 오르트산 유발 지방간 흰쥐에 눈꽃 동충하초, 번데기 동충하초, cordycepin 함량을 높인 번데기 동충하초를 각각 3% 식이 첨가 시킨 후 혈청 임상생화학적 특성과 간장 조직 검사를 조사하였다. 그 결과, 간장에서의 triglyceride 농도가 증가함으로서 지방간 유발이 확인되었고 혈청 triglyceride 농도가 감소함으로서 지방간에서 나타나는 전형적인 현상이 확인되었다. 이에 반해 OA투여와 함께 동충하초를 동시에 투여한 군들에서는 간장의 triglyceride 농도가 감소하고 혈청 triglyceride 농도가 증가해서 지방간이 개선되는 효과가 확인되었다. 또한 간장의 형태학적 및 조직병리학적 관찰에서도 OA유발 지방간에서는 지방의 침착과 지방세포수가 현저히 증가되었으나, 각각의 동충하초 동시투여에 의한 간장 및 혈청 triglyceride의 감소와 함께 간장 조직의 지방침착 정도 및 지방 세포수의 감소로 지방간 개선 효과가 다시 한번 확인되었고, 그 중 cordycepin 고함유 번데기 동충하초 투여군에서 가장 근접하게 정상군의 간장과 유사한 형태를 보임으로서 cordycepin이 OA 유발 지방간에 개선효과가 있는 것으로 사료된다. The concentration of cordycepin produced by crossbred Cordyceps militaris JLM 0636 (CMα) was 7.42 mg/g dry weight, which was 7-fold higher than that of C. militaris (CM). However, cordycepin was not detected in Paecilomyces japonica (PJ). The improvement effects of CMα, CM and PJ on orotic acid (OA)-induced fatty liver in male Sprague-Dawley rats was investigated. Rats were randomly divided into five groups (n=6) based on five dietary categories: normal (N), OA control (C), OA plus 3% (w/w) PJ (PJ), OA plus 3% CM (CM), and OA plus 3% CMα (CMα). OA treatment induced the retardation of body weight gain and enlargement of the liver. The concentration of hepatic triglyceride was markedly increased by OA-feeding, whereas this rise was significantly reduced by simultaneous feeding of OA, PJ, CM, and CMα, and this phenomenon was more pronounced by cordycepin- enriched CMα. The contents of total lipid, triglyceride, and free fatty acid in the serum were significantly or slightly lower in the OA control group than those of the N group, but there were no significant differences among the OA treatment groups. The hepatocytes in the OA-induced fatty liver contained numerous large lipid droplets, but PJ, CM, and CMα feeding prevented the OA-induced lipid droplet accumulation in the hepatocytes. This effect was more pronounced in cordycepin-enriched CMα than in PJ or CM in OA treatment rats. Accordingly, cordycepin-enriched CMα could be an ideal candidate material as a dietary supplement in healthy functional foods to improve the effects of fatty liver.
Culture Conditions for Glutathione Maximum Production by Saccharomyces cerevisiae FF-8 in Bioreactor
Jae-Young Cha(차재영),Sang-Hyun Park(박상현),Jin-Sun Heo(허진선),Bo-Kyung Park(박보경),Jin-Woo Lee(이진우),Jung-Wook Kim(김정욱),Young-Su Cho(조영수) 한국생명과학회 2008 생명과학회지 Vol.18 No.5
글루타티온은 의약품, 건강기능식품, 화장품 등에 널리 사용되고 있어서 오늘날 상업적인 수요가 증가하고 있다. 한국전통 발효주로부터 글루타티온-고함유 효모인 S. cerevisiae FF-8 균주를 분리한 바 있으며, FF-8 균주에서 글루타티온 생산량은 YM 기본배지를 이용한 플라스크 배양에서 90 ㎎/l이었으나, YM 최적배지에서는 2.27배 증가한 204 ㎎/l 이었다. 대량배양 발효방법은 일반적으로 효모에서 생리활성 물질을 더욱 효과적으로 생산하기 위하여 대량배양기를 이용한 S. cerevisiae FF-8에서 글루타티온 생산량을 증대시킬 수 있는 최적의 발효조건을 탐색하였다. 7 l 발효기에서 FF-8 균주에 의한 세포생육과 글루타티온 최대 생산량을 위한 발효조건은 교반 속도 200 rpm, 배양 온도 30℃, 초기 조절 pH 6.0, 통기조건 2.0 vvm이었다. 또한 100 l 대량배양기에서 S. cerevisiae FF-8에 의한 글루타티온 대량생산 조건은 내부압력 0.8 kgf/㎠ 이었고, 이때 글루타티온 생산량은 255.8 ㎎/l이었다. 글루타티온 생산량을 증대시키기 위한 중요한 요소의 검토는 최적의 프로세스 확립에 매우 유용하다. As glutathione is now widely used in medicine, functional health food and cosmetic industry, the commercial demand for glutathione has been expending. We have previously reported that Saccharomyces cerevisiae FF-8, an intracellular glutathione producing yeast strain, was isolated from Korean traditional rice wine. Glutathione production by FF-8 strain was 90 mg/l from basal YM medium in flask-scale fermentation, but that in optimal YM medium increased 2.27-fold to 204 ㎎/l. As large scale fermentation is generally applied to achieve more efficient production of bioactive components, this study was also tried to optimization of fermentation parameters to enhance the glutathione production using S. cerevisiae FF-8 in bioreactor process. The highest cell growth and glutathione concentrations of S. cerevisiae FF-8 in 7 l fermenter were observed to be the culture conditions containing culture temperature 30℃, adjusted initial pH 6.0, agitation speed 200 rpm, and aeration rate 2.0 vvm. The maximum glutathione production by FF-8 was cultured under the inner pressure 0.8 kgf/㎠ in a 100 l bioreactor and it was 255.8 ㎎/l. The investigation of significant parameters for improving the glutathione production could be very useful in optimizing processes.
Heo, Seong Eun,Lim, Hyun Woo,Cho, Deok Ki,Park, Ik Jae,Kim, Hyunki,Lee, Chan Woo,Ahn, Sang Hyun,Kim, Jin Young Elsevier 2020 Journal of catalysis Vol.381 No.-
<P><B>Abstract</B></P> <P>Ru- and Ti-based oxide electrocatalysts have been intensively studied for chlorine evolution reactions since their synergistic effect was demonstrated in commercial dimensionally stable anodes. Basically, oxide materials intrinsically possess a semiconducting nature; therefore, tuning conducting properties is important in achieving high electrocatalytic activity. Here, black TiO<SUB>2</SUB> nanotube arrays deposited with RuO<SUB>2</SUB> by pulsed electrodeposition are investigated as a three-dimensional supporting electrode for chlorine and hydrogen evolution. RuO<SUB>2</SUB>-loaded black titania achieves high chlorine evolution activity (10 and 100 mA cm<SUP>−2</SUP> at 1.090 and 1.125 V vs. SCE) with a faradaic efficiency of 95.25% while RuO<SUB>2</SUB>-loaded titania has no activity, though hydrogen evolution reaction performance is similar. This suggests that the type of titania support affects the conducting property at anodic potentials and chlorine evolution activity. This work provides new insights into the importance of black titania materials in enhancing the electrocatalytic activity of anodic reactions.</P> <P><B>Highlights</B></P> <P> <UL> <LI> RuO<SUB>2</SUB>/black TiO<SUB>2</SUB> NTAs exhibited outstanding chlorine evolution activity. </LI> <LI> RuO<SUB>2</SUB>/TiO<SUB>2</SUB> NTAs had almost no activity for chlorine evolution reaction. </LI> <LI> Conductivity difference of oxide supports in anodic reactions determine activity. </LI> <LI> Black TiO<SUB>2</SUB> is a promising material as a conductive support in chlorine evolution. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>