• International Journal of Precision Engineering and Manufacturing
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• 제8권2호
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• pp.26-31
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• 2007

A novel scanning probe measurement system was developed to enable precise profile measurements of microaspheric surfaces. An air-bearing stylus with a microprobe was used to perform the surface profile scanning. The new system worked in a contact mode and had the capability of measuring micro-aspheric surfaces with large tilt angles and complex profiles. Due to limitations resulting from the contact mode, such as possible damage caused by the contact force and lateral resolution restrictions from the curvature of the probe tip, several system improvements were implemented. An air bearing was used to suspend the shaft of the probe to reduce the contact force, enabling fine adjustments of the contact force by changing the air pressure. The movement of the shaft was measured by a linear encoder with a scale attached to the actual shaft to avoid Abbe errors. A $50-{\mu}m-diameter$ glass sphere was bonded to the tip of the probe to improve the lateral resolution of the system. The maximum contact force of the probe was 10 mN. The shaft was capable of holding the probe continuously if the contact force was less than 40 mN, and the resolution of the probe could be as high as 10 nm, The performance of the new scanning probe measurement system was verified by experimental data.

• Journal of Pharmacopuncture
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• 제23권3호
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• pp.165-172
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• 2020

Objectives: In the past few years, herbal medicines have gained popularity over synthetic drugs because of their natural source and minimal side effects which has led to a tremendous growth of phytopharmaceuticals usage. With the development of nanotechnology, it provides alternative approaches to overcome several limitations using nano-formulations. In spite of considerable quantity of antianemic preparations with different iron forms available, currently additives are used and represented in modern pharmaceutical market. Iron deficiency anemia is a major global public health problem which particularly affects pregnant women, children and elderly persons. The situation is complicated because of disadvantages and drug side effects from existing antianemic medicines. There is a great demand for the development of new antianemic preparations. Green synthesis of iron oxide nanoparticles, possess high potential in this field. Methods: Our study focuses on developing green synthesis of iron oxide nanoparticles (IONPs) of 10-50 nm with spherical shape where different dosages were used -1 mg/kg, 10 mg/kg and 100 mg/kg for exposure in Wistar albino female rats for 28 days. The toxicity was assessed using various parameters such as measurements of the rat body and organ mass, hematology, biochemical evaluation and histopathological examinations. Results: No significant differences were observed in body and organ weights. Hematological indices also indicated no significant differences whereas biochemical factors showed increase in levels of direct bilirubin and globulin of medium as well as high dose and SGPT levels were increased only in high dose. The major organs (heart, kidney and liver) showed histopathological alterations in 10 and 100 mg/kg whereas brain showed only in 100 mg/kg. Conclusion: The toxicity of IONPs was found to be more significant when the concentration was increased; however, low doses can be used for further investigation as an antianemic preparation.

• Korean Journal of Materials Research
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• 제25권8호
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• pp.386-390
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• 2015

Fe-base superalloy powders with $Y_2O_3$ dispersion were prepared by high energy ball milling, followed by spark plasma sintering for consolidation. High-purity elemental powders with different Fe powder sizes of 24 and 50 mm were used for the preparation of $Fe-20Cr-4.5Al-0.5Ti-O.5Y_2O_3$ powder mixtures (wt%). The milling process of the powders was carried out in a horizontal rotary ball mill using a stainless steel vial and balls. The milling times of 1 to 5 h by constant operation (350 rpm, ball-to-powder ratio of 30:1 in weight) or cycle operation (1300 rpm for 4 min and 900 rpm for 1 min, 15:1) were applied. Microstructural observation revealed that the crystalline size of Fe decreased with an increase in milling time by cyclic operation and was about 15 nm after 3 h, forming a FeCr alloy phase. The cyclic operation had an advantage over constant milling in that a smaller-agglomerated structure was obtained. The milled powders were sintered at $1100^{\circ}C$ for 30 min in vacuum. With an increase in milling time, the sintered specimen showed a more homogeneous microstructure. In addition, a homogenous distribution of Y-compound particles in the grain boundary was confirmed by EDX analysis.

• KSBB Journal
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• 제31권1호
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• pp.1-7
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• 2016

Changes in the concentrations of glucosinolates and related compounds in different extracts of Dolsan leaf mustard kimchi (DLMK) and Dolsan leaf mustard pickles (DLMP) were during storage investigated. Samples were kept at 0oC for 35 days and collected at 7 day intervals. The leaves and stems of DLMK and DLMP were refluxed for 24 h with 50% acetonitrile, and the extracts were analyzed by LC-PDA/MS/MS. The main glucosinolates detected in DLMK were sinigrin, gluconapoleiferin, glucobrassicanapin, and gluconapin, whereas those in DLMP were sinigrin, gluconapoleiferin, glucobrassicanapin, glucobrassicin, and glucoerucin. Sinigrin concentrations were quantified by UV absorption at 228 nm. Sinigrin concentrations in the leaves and stems of DLMK on the day of preparation were 2.14 mg/g and 2.25 mg/g, respectively, and those on day 35 after preparation were 1.25 mg/g and 1.00 mg/g, respectively. DLMP showed a similar trend: the concentrations in the leaves and stems on the day of preparation were 2.04 mg/g and 0.29 mg/g, respectively, whereas those on day 35 after preparation were 0.59 mg/g and 0.41 mg/g, respectively. Thus, sinigrin concentrations decreased during storage.

• KSBB Journal
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• 제31권1호
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• pp.20-26
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• 2016

This study aims to examine the optimum blanching conditions as a pretreatment condition to improve the storage stability of Dolsan leaf mustard pickle. The effects of the blan- ching temperature and time were investigated at a temperature range of $80-100^{\circ}C$. Sampling was done for 1 month after a 5 days interval. The L value of the Dolsan leaf mustard was found to be the highest at $80^{\circ}C$. The cutting force increased as the blanching temperature increased. The tensile strength decreased at $95^{\circ}C$ and $100^{\circ}C$. In addition, the sensory evaluation scores were the best at $80^{\circ}C$. The storage stability was assessed at various blanching temperatures to increase the sinigrin content during storage. Liquid chromatography with photodiode array and tandem mass spectrometry (LC-PDA/MS/MS) analysis was conducted to identify and quantify the sinigrin content in the Dolsan leaf mustard. Sinigrin as an internal standard was co-injected into each sample solution. The sample was monitored by recording the ultraviolet absorbance at 228 nm and by electrospray ionization (ESI) positive ion mode in the m/z 50-1,500 range. Blanching the sample at $80^{\circ}C$ showed the highest sinigrin concentration during storage among various temperatures and the maximum concentration was 350 ppm at 15 days storage. Study on utilization of vegetable from food processing of leaf mustard and preservation conservation results suggest that blanching at $80^{\circ}C$ is expected to improve the palatability of the pickle.

• Journal of Electrical Engineering and Technology
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• 제5권2호
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• pp.337-341
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• 2010

In this paper, an extremely low voltage operated micro corner cube retroreflector (CCR) was fabricated for free-space optical communication applications by using bulk silicon micromachining technologies. The CCR was comprised of an orthogonal vertical mirror and a horizontal actuated mirror. For low voltage operation, the horizontal actuated mirror was designed with two PZT cantilever actuators, torsional bars, hinges, and a mirror plate with a size of $400{\mu}m{\times}400{\mu}m$. In particular, the torsional bars and hinges were carefully simulated and designed to secure the flatness of the mirror plate by using a finite element method (FEM) simulator. The measured tilting angle was approximately $2^{\circ}$ at the applied voltage of 5 V. An orthogonal vertical mirror with an extremely smooth surface texture was fabricated using KOH wet etching and a double-SOI (silicon-on-insulator) wafer with a (110) silicon wafer. The fabricated orthogonal vertical mirror was comprised of four pairs of two mutually orthogonal flat mirrors with $400{\mu}m4 (length) $\times400{\mu}m$ (height) $\times30{\mu}m$ (thickness). The cross angles and surface roughness of the orthogonal vertical mirror were orthogonal, almost $90^{\circ}$ and 3.523 nm rms, respectively. The proposed CCR was completed by combining the orthogonal vertical and horizontal actuated mirrors. Data transmission and modulation at a frequency of 10 Hz was successfully demonstrated using the fabricated CCR at a distance of approximately 50 cm.

• Korean Journal of Oriental Medicine
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• 제16권1호
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• pp.173-178
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• 2010

The purpose of this study was investigation of quantitative analysis of marker substances in solid fermented Angelicae Gigantis Radix by High performance liquid chromatography(HPLC). HPLC was performed for determination of nodakenin and decursin in solid fermented Angelicae Gigantis Radix extract, the separation method was performed on C18 column ($250\;mm\;{\times}\;4.6\;mm$, $5\;{\mu}m$, RS tech) using gradient solvent mixtures of water-acetonitrile with photodiode array detector (330 nm). The flow rate was 1.0 ml/min. Retention time of nodakenin and decursin was about 11.47, 46.79 min and linearity of calibration was showed good result(r2=0.9999, 0.9999), respectively. Content of nodakenin was $0.76\;{\pm}\;0.02%$ in control, $0.31\;{\pm}\;0.00%$ in Angelicae Gigantis Radix extract fermented with Paecilomyces japonica(SDT)(p<0.01), $0.51\;{\pm}\;0.02%$ in Angelicae Gigantis Radix extract fermented with Ganoderma lucidum(SYT)(p<0.01), $0.82\;{\pm}\;0.03%$ in Angelicae Gigantis Radix extract fermented with honey(SST)(p<0.05) and $0.88\;{\pm}\;0.01%$ in Angelicae Gigantis Radix extract fermented with Nuruk(SNT)(p<0.01). Content of decursin was $4.50\;{\pm}\;0.08%$ in control, $2.90\;{\pm}\;0.05%$ in Angelicae Gigantis Radix extract fermented with Paecilomyces japonica(SDT)(p<0.01), $2.65\;{\pm}\;0.08%$ in Angelicae Gigantis Radix extract fermented with Ganoderma lucidum(SYT)(p<0.01), $4.46\;{\pm}\;0.11%$ in Angelicae Gigantis Radix extract fermented with honey(SST) and $4.73\;{\pm}\;0.04%$ in Angelicae Gigantis Radix extract fermented with Nuruk(SNT)(p<0.05), respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 한국전기전자재료학회 2003년도 춘계학술대회 논문집 센서 박막재료 반도체 세라믹
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• pp.111-115
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• 2003

200nm 정도의 두께를 가진 SBT 박막이 liquid delivery MOCVD 공정에 의해 (111) oriented Pt/Ti/$SiO_2$/Si 기판 위에 증착되었다 이 실험에서는 $Sr(TMHD)_2$tetraglyme, $Bi(ph)_3$ 그리고 $Ta(O^iPr)_4$(TMHD)를 출발 물질로 사용하였다. Sr 출발 물질의 열적 안정화를 위해서 adduct로 tetraglyme를 사용하여 실험하였고 유기 용매로는 n-butyl acetate를 사용하였다 Substrate temperature와 reactor pressure는 각각 $570^{\circ}C$와 5Torr로 유지시켰다. 또한 vaporizer의 용도는 $190-200^{\circ}C$, 그리고 delivery line 의 온도는 vaporizer 보다 높게 유지 $(220-230^{\circ}C)$하여 출발 용액을 분당 0.1ml로 50분간 주입하였다. 수송가스로 Ar, 산화제로 $O_2$ 가스를 사용하였다. 제조한 SBT 박막은 $750^{\circ}C$에서 열처리한 후 인가전압 3V와 5V에서 $2P_r$값이 각각 6.47, $8.98{\mu}C/cm^2$이었으며, $2E_c$값은 인가전압 3V와 5V에서 각각 2.05, 2.31V이었다 그리고 $800^{\circ}C$에서는$750^{\circ}C$에서 열처리한 SBT 박막보다 다소 우수한 이력특성을 나타내어 $2P_r$ 값은 인가전압 3V와 5V에서 각각 7.59, $10.18{\mu}C/cm^2$ 이었으며, $2E_c$값은 인가 전압 3V와 5V에서 각각 2.00, 2.21V 이었다.

• Proceedings of the KIEE Conference
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 C
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• pp.1850-1852
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• 2005

$SrTiO_3$ and $BaTiO_3$ sol-liquids and powders were prepared by the sol-gel method. $SrTiO_3/BaTiO_3$ heterolayered thin/thick films have been prepared on the $Al_2O_3$ substrates by screen printing and spin-coating method. The thin films were sintered at $750^{\circ}C$ in the air for 1 hour and the thick films sintered at $1325^{\circ}C$ in the air for 2 hours, respectively. The $SrTiO_3/BaTiO_3$ thin/thick films's structural and dielectric properties were investigated. Increasing the spin-coating times, (110), (200), (211) peaks of the $SrTiO_3$ were increased. The X-ray diffraction(XRD) patterns and SEM photographs indicated that the $SrTiO_3$ phase were formed in the surface of $BaTiO_3$ thick films. The average thickness of a $BaTiO_3$ thick films and $SrTiO_3$ thin films were $50{\mu}m$ and 400nm, respectively The dielectric constant and dielectric loss of the $SrTiO_3/BaTiO_3$ thin/thick films with $SrTiO_3$ coated 5 times were 1598 and 0.0436 at 10KHz.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• 제29권6호
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• pp.348-352
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• 2016

In this paper, GaN film was grown on AlN/PSS by hydride vapor phase epitaxy compared with GaN on planar sapphire. Thin AlN layer for buffer layer was deposited on patterned sapphire substrate (PSS) by metal organic chemical vapor deposition. Surface roughness of GaN/AlN on PSS was remarkably decreased from 28.31 to 5.53 nm. Transmittance of GaN/AlN grown on PSS was lower than that of planar sapphire at entire range. XRD spectra of GaN/AlN grown on PSS corresponded the wurzite structure and c-axis oriented. The full width at half maximum (FWHM) values of ${\omega}$-scan X-ray rocking curve (XRC) for GaN/AlN grown on PSS were 196 and 208 arcsec for symmetric (0 0 2) and asymmetric (1 0 2), respectively. FWHM of GaN on AlN/PSS was improved more than 50% because of lateral overgrowth and AlN buffer effect.