• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.332-332
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• 2011

The extreme ultraviolet (EUV) radiation, whose wavelength is from 120 nm down to 10 nm, and the energy from 10 eV up to 124 eV, is widely utilized such as in photoelectron spectroscopy, solar imaging, especially in lithography and soft x-ray microscopy. In this study, we have investigated the plasma diagnostics as well as the debris characteristics between the two types of dense plasma focusing devices with coaxial electrodes of Mather and hypocycloidal pinch (HCP), respectively. The EUV emission intensity, electron temperature and plasma density have been investigated in these cylindrical focused plasma along with the debris characteristics. An input voltage of 5 kV has been applied to the capacitor bank of 1.53 uF and the diode chamber has been filled with Ar gas at pressure ranged from 1 mTorr and 180 mTorr. The inner surface of the cathode was covered by polyacetal insulator. The central anode electrode has been made of tin. The wavelength of the EUV emission has been measured to be in the range of 6~16 nm by a photo-detector (AXUV-100 Zr/C, IRD). The visible emission has also been measured by the spectrometer with the wavelength range of 200~1,100 nm. The electron temperature and plasma density have been measured by the Boltzmann plot and Stark broadening methods, respectively, under the assumption of local thermodynamic equilibrium (LTE).

• Journal of Sensor Science and Technology
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• v.12 no.4
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• pp.191-197
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• 2003

Due to explosive increase of internet usage, broadband data transmission using optical fibers is broadly used. In order to decrease distortion during long distance transmission, the optical signal need to be restored, typically, by converting the optical signal into the electrical signal. The optical signal is converted into the electrical signal using a photo-diode, and then a clock-and-recovery (CDR) circuit is used to recover the clock and retime the data. In this study, a clock-and-data recovery circuit has been designed using a standard 1.8 V $0.18\;{\mu}m$ CMOS process. With this CDR circuit, the improved phase detector and charge pump have been utilized. Also, by using a ring oscillator, the CDR circuit can recover clock and data from broadband multi-rate data ranging between 750 Mb/s and 2.85 Gb/s.

• YAKHAK HOEJI
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• v.55 no.1
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• pp.64-68
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• 2011

In this study, a high performance liquid chromatography-diode array detector method was established, for simultaneous determination of three compounds, berberine, palmatine and geniposide in Hwangryunhaedok-tang, To develop and validate method, $C_{18}$ column (5 ${\mu}M$, 4.6 mm${\times}$250 mm) was used with gradient mobile phase, water containing 0.1% trifluoroacetic acid (TFA) and MeOH at the column temperature of $30^{\circ}C$. UV wavelength was set at 230 and 280 nm. Validation of the chromatography method was evaluated by linearity, precision and accuracy test. Calibration curve of standard components showed good linearity ($R^2$ > 0.9999). The limits of detection (LOD) and limits of quantification (LOQ) varied from 0.05 to 0.17 ${\mu}g/ml$ and 0.15 to 0.53 ${\mu}g/ml$, respectively. The relative standard deviations (RSDs) data of intra-day and inter-day test were in less than 2.99% and 1.90%, respectively. The results of the accuracy test were in the range of 98.36 to 102.52% with RSDs values 0.32 to 1.98%. The results of validation indicated that this method was a very accurate and sensitive assay.

• Journal of Ginseng Research
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• v.40 no.4
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• pp.382-394
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• 2016

Background: Ginsenosides are the characteristic and principal components which manifest a variety of the biological and pharmacological activities of the roots and rhizomes of Panax ginseng (GRR). This study was carried out to qualitatively and quantitatively determine the ginsenosides in the cultivated and forest GRR. Methods: A rapid and sensitive ultra-high-performance liquid chromatography coupled with diode-array detector and quadrupole/time of flight tandem mass spectrometry (UPLC-DAD-QTOF-MS/MS) was applied to the qualitative analysis of ginsenosides and a 4000 QTRAP triple quadrupole tandem mass spectrometer (HPLC-ESI-MS) was applied to quantitative analysis of 19 ginsenosides. Results: In the qualitative analysis, all ingredients were separated in 10 min. A total of 131 ginsenosides were detected in cultivated and forest GRR. The method for the quantitative determination was validated for linearity, precision, and limits of detection and quantification. 19 representative ginsenosides were quantitated. The total content of all 19 ginsenosides in the forest GRR were much higher than those in the cultivated GRR, and were increased with the growing ages. Conclusion: This newly developed analysis method could be applied to the quality assessment of GRR as well as the distinction between cultivated and forest GRR.

• Nuclear Engineering and Technology
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• v.43 no.4
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• pp.399-404
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• 2011

A LEGO-type multi-purpose dosimetry phantom was developed for intensity-modulated radiation therapy (IMRT), which requires various types of challenging dosimetry. Polystyrene, polyethylene, polytetrafluoroethylene (PTFE), and polyurethane foam (PU-F) were selected to represent muscle, fat, bone, and lung tissue, respectively, after considering the relevant mass densities, elemental compositions, effective atomic numbers, and photon interaction coefficients. The phantom, which is composed of numerous small pieces that are similar to LEGO blocks, provides dose and dose distribution measurements in homogeneous and heterogeneous media. The phantom includes dosimeter holders for several types of dosimeters that are frequently used in IMRT dosimetry. An ion chamber and a diode detector were used to test dosimetry in heterogeneous media under radiation fields of various sizes. The data that were measured using these dosimeters were in disagreement when the field sizes were smaller than $1.5{\times}1.5\;cm^2$ for polystyrene and PTFE, or smaller than $3{\times}3\;cm^2$ for an air cavity. The discrepancy was as large as 41% for the air cavity when the field size was $0.7{\times}0.7\;cm^2$, highlighting one of the challenges of IMRT small field dosimetry. The LEGO-type phantom is also very useful for two-dimensional dosimetry analysis, which elucidates the electronic dis-equilibrium phenomena on or near the heterogeneity boundaries.

• The Journal of Korean Society for Radiation Therapy
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• v.7 no.1
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• pp.32-44
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• 1995

I. 제 목 고에너지 X-선 소조사야의 선량분포 및 계측에 관한 연구 II. 연구의 목적 및 중요성 최근 수술이 어려운 뇌종양등에 대한 방사선수술법(Radiosurgery)이 관심의 대상이 되고 있다. 방사선수술법은 크게 나누어 200여개의 Co-60이 장착된 장치(Gamma Knife)를 이용하는 방법과, X-선치료기를 이용하는 방법은 몇개의 보조기구를 설치하면 가능한 매우 경제적인 방법이다. 따라서 Microtron을 이용한 방사선수술의 기초자료확보를 위하여 소조사야에 대한 선량과 선량분포의 측정 및 계산을 실시하였다. III. 연구의 내용 및 범위 Microtron으로부터 조사되는 6MV, 10MV, 21MV X-선의 지름 3cm이하 소조사야에 대한 정확한 선량 및 선량분포 자료를 확보하기 위해, 가. Microtron치료기와 보조장치등에 대한 정밀도 계측 및 평가 나. 보조 Collimator의 적당한 크기와 재료의 선택 및 설계, 제작. 다. 에너지와 조사야 크기 각각에 대한 여러측정장치(Ion chamber, Diode detector, TLD 및 Film등)를 이용한 선량 및 선량분포 측정. 라. 측정값들의 비교, 검토 및 측정된 자료에 의한 선량 및 선량분포의 계산을 수행했다. IV. 연구결과 및 활용에 대한 건의 본 연구에서 얻은 결과는 다음과 같다. 가. Microtron치료기와 보조장치등의 정확도의 허용 오차범위내에서 잘 일치하였다. 나. 보조 collimater adpator는 총 길이 24cm로 하였으며 재질로는 두랄미늄을 사용하였고, 보조 collimator는 low melting alloy를 사용하였으며 소조사야 크기의 정확도는 0.5mm이내에서 매우 잘 일치 하였다. 다. 방사선 수술법의 에너지 선택에 중요한 요소중의 하나인 penumbra는 6MV X-선에서 가장 적게 나타났으며 라. 소조사면에 대한 깊이-선량 백분율곡선은 모든 에너지에서 조사면이 작아질수록 표면으로 이동하는 경향을 보였다. 이상의 결과로부터 방사선 수술을 시행할 경우 수십억원에 이르는 장비의 도입이나 새로운 시설 없이 Microtron에서 조사되는 고에너지 X-선을 이용할 수 있을 것으로 사료된다. 또한 새로 구입한 측정기나 보조 Collimator를 이용하여 소조사야에 대한 선량측정기술을 습득함으로써 일반적인 소조사야의 방사선치료나 회전치료등에 활용할 수 있다.

• Preventive Nutrition and Food Science
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• v.16 no.3
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• pp.242-247
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• 2011

The methanolic extract of Rosa davurica Pall. roots exhibited strong antioxidant activity in a 1,1-diphenyl-2-picryl-hydrazyl (DPPH) radical scavenging assay and was found to be a dose-dependent inhibitor of non-enzymatic formation of advanced glycation end products (AGEs), which are relevant to diabetes complications. HPLC-diode array detector (DAD) analysis of the R. davurica Pall. root extract led to the identification of four compounds: hydrocaffeic acid, catechin, epicatechin, and ellagic acid. Catechin was present in the largest amount and exhibited high antiglycation activity. A CYP3A4 assay was used to investigate potential interactions between drugs and the extract, and results suggest that the R. davurica Pall. root extract had moderate potential for interfering with drug metabolism. The R. davurica Pall. extract did not display anti-inflammatory activity on the level of that for tumor necrosis factor-${\alpha}$ (TNF-${\alpha}$) in a lipopolysaccharide (LPS)-stimulated macrophage assay; however, the extract did exhibit low to moderate immunostimulatory activity in a pro-inflammatory macrophage assay. Therefore, we conclude that R. davurica Pall. root is a promising anti-AGE agent with low to moderate risks of associated inflammation or drug interaction.

• Journal of Ginseng Research
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• v.36 no.2
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• pp.205-210
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• 2012

For quality control of components in Korean red ginseng powder and extract, a new method for simultaneous quantification of 12 ginsenosides ($Rg_1$, Re, Rf, $Rh_1$, $Rg_2$[S], $Rg_2$[R], $Rb_1$, Rc, $Rb_2$, Rd, $Rg_3$[S], and $Rg_3$[R]) was studied. Compared to the official method for quantification of marker substances (ginsenosides $Rg_1$ and $Rb_1$), the proposed methods were guaranteed by in-house method validation. Several criteria such as linearity, specificity, precision and accuracy were evaluated. For red ginseng powder, recovery (averaging 95% to 105%) was calculated, and analysis of variance was carried out to estimate the relative standard deviation (0.20% to 2.12%). For red ginseng extract, the average recovery rate was 90% to 99% and the relative standard deviation was 0.39% to 2.40%. These results indicate that the proposed method could be used in the laboratory for determination of 12 ginsenosides in red ginseng powder and extract. In addition, this method was found to be suitable for quality control of ginseng products and potentially offer time and cost benefits.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.4
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• pp.605-611
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• 2015

The measurement and analysis of angular change have been studied in many fields. This study developed an angle measurement technique with optical fiber and photodiode. The position and attached angle of photodiode were investigated to find the proper combination of parameter. The results showed that the increased measuring range was achieved when the position of detector was away from the center of rotation. Inverse mathematical model was used to obtain angular changes with an optical fiber. The applications of this study include in optical sensor, joint angle measurement, and sport science.

• YAKHAK HOEJI
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• v.52 no.6
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• pp.446-451
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• 2008

A high-performance liquid chromatography (HPLC) with diode array detector (DAD) and electrospray ionization mass spectrometry (ESI-MS) was established for the simultaneous determination of chlorogenic acid (1), sweroside (2), luteolin-7-O-glucoside (3), (E)-aldosecologanin (4) and 3,5-dicaffeoylquinic acid (5) from Lonicera joponica flower buds. The optimal chromatographic conditions were obtained on an ODS column (5 ${\mu}m$, 4.6${\times}$150 mm) with the column temperature $25^{\circ}C$. The mobile phase was composed of (A) water with 0.1% formic acid and (B) acetonitrile with 0.1% formic acid using a gradient elution, the flow rate was 0.3 ml/min. Detection wavelength was set at 250 nm. All calibration curves showed good linear regression ($r^2$>0.994) within test ranges. The developed method provided satisfactory precision and accuracy with overall intra-day and inter-day variations of 0.05${\sim}$1.95% and 0.15${\sim}$2.26%, respectively, and the overall recoveries of 97.71${\sim}$103.65% for the five compounds analyzed. The verified method was successfully applied to quantitative determination of the three types (phenolic compounds, iridoids and flavonoids) of bioactive compounds in 21 commercial L. japonica flower buds samples from different markets in Korea and China. The analytical results demonstrated that the contents of the five analytes vary significantly with sources.