• Journal of the Korean Ceramic Society
• /
• v.42 no.11 s.282
• /
• pp.763-769
• /
• 2005

Ferroelectric $ReMnO_3$(Re:Ho, Er) thin films were deposited on Si(100) substrate by Metal-Organic Chemical Vapor Deposition (MOCVD). Crystallinity and electric properties of $ReMnO_3$(Re:Ho, Er) thin films were investigated as a function of thermal heat treatment process, CHP (Conventional Heat-treatment Process) and RTP (Rapid Thermal Process). $ReMnO_3$(Re:Ho, Er) thin films prepared by RTP showed higher c-axis preferred orientation and homogeneous surface roughness than those prepared by CHP. The remnant polarization of ferroelectric hysteresis loop of $ReMnO_3$(Re:Ho, Er) thin films was strongly dependent on the c­axis preferred orientation of hexagonal single phase, and the leakage current characteristics of thin films were dependent on the homogeneity of grain size as well as surface roughness of thin films.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2015.08a
• /
• pp.181.1-181.1
• /
• 2015

용액 공정을 이용한 Resistive random access memory (ReRAM)은 간단한 공정 과정, 대면적화, 저렴한 가격 등의 장점으로 인해 큰 관심을 받고 있으며, HfOx, TiOx, AlOx 등의 산화물이 ReRAM 절연 막으로 주로 연구되고 있다. 더 나아가 최근에는 organic 물질을 메모리 소자로 사용한 연구가 보고되고 있다. 이는 경제적이며, wearable 또는 flexible system에 적용이 용이하다. 그럼에도 불구하고, organic 물질을 갖는 메모리 소자는 기존의 산화물 소자에 비해 열에 취약하며 전기적인 특성과 신뢰성이 우수하지 못하다는 단점을 가지고 있다. 이를 위한 방안으로 본 연구에서는 AlOx - polymethylmethacrylate (PMMA) blended thin film ReRAM을 제안하였다. 이는 organic물질의 전기적 특성을 개선시킬 뿐 아니라, inorganic 물질을 wearable 소자에 적용했을 때 발생하는 crack과 같은 기계적 물리적 결함을 해결할 수 있는 새로운 방법이다. 먼저, P-type Si 위에 습식산화를 통하여 SiO2 300 nm 성장시킨 기판을 사용하여 electron beam evaporation으로 10 nm의 Ti, 100 nm의 Pt 층을 차례로 증착하였다. 그리고 PMMA 용액과 AlOx 용액을 초음파를 이용하여 혼합한 뒤, 이 용액을 Pt 하부 전극 상에서 spin coating방법으로 1000 rpm 10초, 5000 rpm 30초의 조건으로 증착하였다. Solvent 및 불순물 제거를 위하여 150, 180, $210^{\circ}C$의 온도로 30 분 동안 열처리를 진행하였고, shadow mask를 이용하여 상부 전극인 Ti를 sputtering 방식으로 100 nm 증착하였다. 150, 180, $210^{\circ}C$로 각각 열처리한 AlOx - PMMA blended ReRAM의 전기적 특성은 HP 4156B semiconductor parameter analyzer를 이용하여 측정하였다. 측정 결과 제작된 소자 전부에서 2 V이하의 낮은 동작전압, 안정된 DC endurance (>150cycles), 102 이상의 높은 on/off ratio를 확인하였고, 그 중 $180^{\circ}C$에서 열처리한 ReRAM은 더 높은 on/off ratio를 갖는 것을 확인하였다. 결론적으로 baking 온도를 최적화하였으며 AlOx - PMMA blended film ReRAM의 우수한 메모리 특성을 확인하였다. AlOx-PMMA blended film ReRAM은 organic과 inorganic의 장점을 갖는 wearable 및 system용 비휘발성 메모리소자에 적용이 가능한 경제적인 기술로 판단된다.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.39 no.11
• /
• pp.1660-1665
• /
• 2010

To obtain data for the standardization of manufacturing method of red ginseng extract pouch products, saponin and physico-chemical properties of 44 Korean red ginseng extract pouch products were analyzed. The concentration of total ginsenoside contents were 5.5~185.7 mg/100 mL. Distribution of the contents of ginsenoside $Rg_3$, $Rg_2$, $Rh_1$, and $Rh_2$ known to have anticancer effect are as follows: $Rg_3$ is 1.6~46.3 mg/100 mL, $Rg_2$ is 0~22.0 mg/100 mL, $Rh_1$ is 0~4.3 mg/100 mL and that of $Rh_2$ is 0~20.4 mg/100 mL, respectively. The anti-diabetic effect of ginsenoside $Rb_2$ and Re distribution of contents were 0~10.8 mg/100 mL and 0~7.0 mg/100 mL, respectively. Among the other saponins, exhibited content to distribution of ginsenoside $Rb_1$ was 0~25.2 mg/100 mL, Rc was 0~12.5 mg/100 mL, Rd was 0~11.3 mg/100 mL, Rf was 0~5.9 mg/100 mL and $Rg_1$ was 0~4.4 mg/100 mL. Results of physicochemical characterization showed total sugar content of 226.6~3,102.9 mg/100 mL, total soluble solids content $1.4\sim9.5^{\circ}Bx$, turbidity 82.2~100.0%, pH in the range of 4.1 to 5.0, respectively. In approximately 50% of collected domestic ginseng extract pouch products (21~24 items), ginsenoside $Rb_1$, $Rb_2$, Rc, Rd, Re and $Rg_1$ were not detected, and saponin content of each product appears to differ greatly. Results indicated that standardization of production methods and standards set for red ginseng extract pouch products in Korea is needed.

• Journal of Applied Biological Chemistry
• /
• v.66
• /
• pp.114-121
• /
• 2023

Selective cyclooxygenase (COX)-2 inhibition is a novel strategy to reduce the risk of gastrointestinal side effects caused by conventional nonsteroidal anti-inflammatory drugs. However, some selective COX-2 inhibitors have become apparent to increase the risk of severe cardiovascular disease. The aim of this study was to examine the anti-inflammatory effect of rosemary extract (RE) and confirm the safety of cardiovascular side effects. Inhibition of COX enzyme activity was assessed, and the levels of COX-2 and prostaglandin E₂ (PGE₂) and COX-1 and thromboxane B₂ (TXB₂) were evaluated in lipopolysaccharide (LPS)-induced RAW 264.7 cells. The 40% RE group showed increased COX-2 inhibition activity in a dose-dependent manner, whereas the 50% RE group only exhibited at 100 ㎍/mL. In a cell-based study, COX-2 mRNA expression was similar in both RE groups and PGE₂ levels tended to decrease in the 40% RE group compared to the LPS group in the LPS pretreatment condition. In the LPS posttreatment condition, the COX-2 mRNA expression decreased in the 40% RE group, and PGE₂ levels were increased in the 40 and 50% RE groups. In both conditions, there was no significant difference in COX-1 and TXB₂ levels. In conclusion, 40 and 50% RE showed significant COX-2 inhibition, similar to the positive control group. It was confirmed that the inhibition of the COX-2 expression, but the effect did not affect the balance between prostacyclin and TXB₂. These results indicate that rosemary showed COX-2 inhibition activity with a low risk of cardiovascular diseases.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.27 no.1
• /
• pp.145-152
• /
• 2021

The purpose of this study was to determine the optimal distances between pipes to minimize the pressure loss and turbulent intensity. This was accomplished by investigating the distances between sleeve-jointed pipes and the flow changes in pipes based on variations in the Reynolds (Re) number when installing adjusting pieces for the pipes. When the thickness tp of the sleeve-jointed piping was fixed at 5 mm and the pipe lengths Lp were 10, 50, 100, and 200 mm, the correlations with the velocity of the sleeve-jointed part, pressure distribution, length of the reattachment point in the recirculation area, and Re number were analyzed. The flow characteristic of the sleeve-jointed part from a laminar to a turbulent flow region was determined by setting the Re range to 200 ≤ Re ≤ 5,000. This was done by utilizing Ansys Fluent 18.1, which is a commercial program. The enlargement and contraction ratios of the sleeve-jointed part were 1.2 and 0.83, respectively, and the turbulent intensity of the sleeve downstream edge and pressure change both increased as the Re number increased while Lp remained constant. The fact that the flow on the sleeve wall surface was disturbed by tp resulted in losses in velocity energy. Therefore, the edge of the sleeve-jointed part was also effected. When Lp was 10 mm or less, the turbulent intensity of the edge part did not change significantly as the Re number increased. The reattachment point in the recirculation area did not appear at Lp of 10 mm or less and was not affected by the vortex. In the case of 3,000 ≤ Re, the reattachment length of the wall surface of the sleeve-jointed part was nearly constant as Lp increased.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.7 no.1
• /
• pp.63-72
• /
• 1995

Convective heat transfer in a two-dimensional horizontal and vertical channel with isothermal rectangular beams attached to one adiabatic wall is investigated from the numerical solution of Navier-Stokes and energy equations. The solutions have been obtained for dimensionless beam spacings, S/L=1~4, aspect ratios of beam, H/B=0.25~4, Reynolds numbers, Re=50~1000 and Grashof numbers, $Gr=0{\sim}5{\times}10^4$. The total mean Nusselt number, Nu_T for horizontal and vertical channels shows same value at Gr=0. As Gr increases, Nu_T for horizontal channel increases, but Nu_T for vertical channel shows similar value at S/L=2, H/B=0.25, Re=100. The total mean Nusselt number for horizontal channel is higher than that for vertical channel. As H/B increases, $Nu_T$ for both channel decrease at $Gr=10^4$, Re=100.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2016.05a
• /
• pp.782-784
• /
• 2016

In this study, we studied the gamma-radiation effect of fiber Bragg gratings on the fiber re-coating methods. The fiber Bragg gratings were exposed to gamma-radiation up to a dose of 100 kGy at the dose rate of 104 Gy/min. In our experimental results, we confirmed that the fiber acrylate re-coating process leads to a slightly lower radiation sensitivity of FBGs.

• Korean Journal of Community Nutrition
• /
• v.21 no.4
• /
• pp.344-353
• /
• 2016

Objectives: New retinol activity equivalent (RAE) was introduced as vitamin A unit in Dietary Reference Intake (DRI) for Koreans 2015. The purpose of this study was to evaluate the adequacy of 2015 reference intake (RI) of vitamin A in RAE unit by the comparison with RI and dietary intake of vitamin A. Methods: Analyses on RI of vitamin A were based on the Recommended Dietary Allowances (RDA) for Koreans (1962~2000) and DRIs for Koreans (2005~2015). Analyses on Koreans dietary intake of vitamin A were based on the Korea National Health and Nutrition Examination Survey (KNHNES) reports (1969-2014). For recalculation of RI and dietary intake of vitamin A in RE to RAE, 2013 Koreans intake of retinol: carotenoids ratio of 13: 87 was applied. Results: RI of vitamin A was 600~750 RE for Korean adult, and 339~425 RAE when calculated by applying the retinol and carotenoids intake ratio. Vitamin A intakes of Koreans were <100% RI, 267~668 RE from 1969 to 2001. From 2005, vitamin A intake had increased to >700 RE, >100% RI. When vitamin A intake was converted from RE to RAE (2005~2014), 718~864 RE became 405.8~488.1 RAE, decreased to 56.5% level. The recent 2015 RI of vitamin A is 850 RAE, two times of 2005 & 2010 RI of 425 RAE for adult male. Conclusions: When nutritional status of vitamin A was assessed for Koreans using the estimated average requirement (EAR) of 2015 (570, 460 RAE for male, female adults, respectively), ratio of deficient people increased significantly when judged based on the previous intake of Koreans, <490 RAE. We needs to examine the 2015 RI (EAR) of vitamin A, find a way to measure the accurate intake of dietary vitamin A, and to increase the dietary intake of this vitamin.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.28 no.7
• /
• pp.789-799
• /
• 2004

An experimental study is conducted to investigate the effects of duct corrugation angle on heat/mass transfer characteristics in wavy ducts of a primary surface heat exchanger application. Local heat/mass transfer coefficients on the wavy duct sidewalls are determined by using a naphthalene sublimation technique. The corrugation angles(${\alpha}$) of the wavy ducts are 145$^{\circ}$, 130$^{\circ}$, 115$^{\circ}$ and 100$^{\circ}$. And the Reynolds numbers based on the duct hydraulic diameter vary from 300 to 3,000. The results show that at the low Re(Re $\leq$1000), the secondary vortices called Taylor-Gortler vortices perpendicular to the main flow direction are generated due to effect of duct curvature. By these secondary vortices, high heat/mass transfer regions are formed on both pressure-side and suction-side walls. At the high Re(Re $\geq$ 1000), these secondary flows are vanished with helping flow transition to turbulent flow and the regions which show high heat/mass coefficients by flow reattachment are formed on suction side. As corrugation angle decreases, the local peak Sh induced by Taylor-Gortler vortices increase at Re $\leq$1000. At high Re(Re $\geq$ 1000), by the existence of different kind of secondary flows called Dean vortices, non-uniform Sh distribution appears along spanwise direction at the narrow corrugation angle (${\alpha}$=100$^{\circ}$). Average Sh also increase by the enhanced effect of secondary vortices and flow reattachment. More pumping power (pressure loss) is required with the smaller corrugation angle due to the enhancement of flow instability.

• The Journal of Korean Society for Radiation Therapy
• /
• v.24 no.2
• /
• pp.149-155
• /
• 2012

Purpose: Long Extension (LE) is used in proton therapy for lung and abdomen. However, it has limitations in surface area, produces collision in posterior oblique beam which creates limitations in various gantry angles in planning therapy and increases air gap (distance between patient and compensator). Therefore, this study investigates the usability of manufactured Rounded Extension (RE) in comparison to LE to use the most suitable extension in proton therapy. Materials and Methods: To compare structural features of LE and RE. This study investigated usable gantry angle for snout sizes 100, 180 and 250 and CT scanned Humanoid phantom. And it compared the air gap in posterior oblique direction. Results: The structural features of two extensions are as follow. Because of the existence of supporting bar, the width of LE was 40 cm and RE was 50 cm. Result of the investigation of usable gantry angle for snout sizes 100, 180 and 250 are as follow. LE is ${\pm}36$ (average) at 180 degree and RE is ${\pm}70$ (average). And also, the air gap of RE is decreased by 11.3 cm in average at the same gantry angle. Conclusion: Manufactured RE for proton therapy has several benefits than LE. Its therapy surface area is wider and range of usable gantry angle is also wider. Also, the air gap at the posterior oblique beam has decreased. Therefore the usability of RE in proton therapy of lung and abdomen will be increased compared to LE. However, the air gap of proton therapy at the lateral direction may be increased, so there may be need for make up to decrease air gap at the lateral direction in the future.