• Journal of the Society of Cosmetic Scientists of Korea
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• v.29 no.1
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• pp.123-134
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• 2003

고속액체크로마토그래피 방법을 사용하여 동시에 arbutin, 메탄올에 녹인 methyl, ethyl, prpyl, butyl parben과 glablidien(유용성감초추출물)을 파장 254와 276 nm에서 Gradient methanol로 octdecyl culumn을 사용하여측정하였다. arbutin와 glablidien 농도 0.5-1.0 ug/ml 파라벤류는 0.1-2.0 ug/ml에서 검량선이 직선으로 작성되었다. 검량이 직선으로 나타나 정량분석을 할 수 있다는 것을 알 수 있었다. 샘플 전처리가 크로마토그래피로 측정하기에 좋은 방법이란 것을 판정하기 위하여 일반로션을 사용하여 판정하였다. 이 방법의 정확도는 모든 측정물질(arbutin, methylparaben, ethylparaben, propylparaben, butylparaben, glablidine)의 회수율 상대표준편차(RSD)가 (0.28-2.55%) 나타나 신뢰성 있는 결과를 보였다.A high-performance liquid chromatographic method for the simultaneous determination of arbutine, a mixture of methyl, ethyl, propyl, butyl parabens dissolved in methoanol and Glrablidine(Oil Soluble Licorice), was studied by using a ODS C18 column and a methanol gradient at 254 and 276 nm. Calibration curves were found to be linear in the 0.5-1.0 ug/ml range(compounds arbutine, glrablidin) and 0.1-20 ug/ml (compounds methylpaaben, ethylparaben, propylparaben, butylparaben). Linear regression analysis of the data demonstrates the efficacy of the method in terms of precision and accuracy. An extraction method is developed and validated in order to apply this chromatographic method to a cosmetic lotion. The presision of this method, calculated as the relativ standard deviation(RSD) of the recoveries(0.28-2.55%) was excellent for all compounds.

• Analytical Science and Technology
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• v.7 no.4
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• pp.441-453
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• 1994

Two extraction methods, liquid-liquid extraction(LLE) and solid-phase extraction(SPE), coupled with GC/MS were compared as preconcentration procedures for priority pollutants in water. Among the semi-volatile priority pollutants, 11 acid and 44 base/neutral compounds were spiked in reagent water. With LLE, which is a modification of EPA Method 625, the overall mean recovery of the 54 compounds was 91% with a mean relative standard deviation(RSD) of 4.6%. With SPE, the overall mean recovery of the 52 compounds was 53% with a mean RSD of 8.9%. The detection limits of both methods were in the range of $1{\sim}5{\mu}g/l$.

• Korean Journal of Pharmacognosy
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• v.50 no.2
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• pp.133-140
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• 2019

In our previous study, we found uracil, adenosine, protocatechuic acid, syringin (eleutheroside B) and scoparone (6, 7-dimethoxycoumarin) in the Oplopanax elatus Nakai Stem. High-performance liquid chromatography (HPLC) -UV was used to quality and quantify the internal marker compounds in the O. elatus extract after validation of method with linearity, limit of detection (LOD), limit of quantitation (LOQ), accuracy and precision. The specificity assessment visually confirmed that the substance was detected without the introduction of other substances. The established method showed high linearity of the calibration curve and coefficient of correlation ($R^2$) of over the 0.999. HPLC was reported as five standard compounds equivalent using the following linear equation based on the calibration curve. The accuracy of measurement was 84.34 ~ 119.74% and the relative standard deviation (RSD) value was 0.28 ~ 1.60%. In addition, our established method showed high repeatability. The RSD value was 1.10 ~ 6.81%. So, we found the amount of the internal marker compounds in the O. elatus extract. These results demonstrated that can be used to quality evaluation of the O. elatus.

• Korean Journal of Food Science and Technology
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• v.53 no.4
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• pp.391-398
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• 2021

As global interest in herbal medicines has increased, the adulteration of herbal medicines has become a critical safety issue. Adulteration with dyes to improve the appearance of low-quality products is of particular concern. This study aimed to develop a high-performance liquid chromatography (HPLC) method to detect dyes added as adulterants to Phellodendron. Samples were analyzed on a C18 column using 50 mM ammonium acetate and acetonitrile as the mobile phase. All calibration curves showed good linearity (r² ≥0.9999) over the five-point concentration range (1-50 mg/kg). Limit of detection ranged from 0.04-0.35 mg/kg, and limit of quantification ranged from 0.11-1.07 mg/kg. The repeatability and reproducibility for these measurements were 94.2-103.3% and 96.6-103.8% for accuracy and 0.14-2.28 RSD (%) and 0.80-2.37 RSD (%) for precision. Moreover, the measurement uncertainty of the low, medium, and high concentrations for 10 dyes was considered. Thus, this HPLC method is suitable for detecting color adulteration of Phellodendron.

• Proceedings of the Korean Society of Crop Science Conference
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• 2021.04a
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• pp.137-137
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• 2021

The study of total phenol (TP) content from 700 rice varieties was evaluated using the UV-Vis spectrophotometric method. The calibration curve of serial diluted gallic acid as a standard of this study showed the acceptable performances (R² = 0.999, mean accuracy 90%) and the mean of % relative standard deviation (%RSD: 0.07%) within the range of 7.8 to 1000 ppm concentrations. The mean value of total phenol content from 700 rice varieties was 2723.15 ㎍/g ranged from 55.48 ㎍/g to 9922.23 ㎍/g and the mean %RSD was 2.5%. Furthermore, this study aim was to analyze and profile individual phenolic compounds in the rice genetic resources to construct an integrative database for development of new rice variety with high functionality for health and understanding of phenolics characteristics in the rice grain. Herein, we analyzed selected 100 rice varieties based on high TP content and identified total 15 phenolic compounds by LC-ESI-MS/MS. Among selected 100 rice genetic resources, the phenolic metabolites consisted of higher amount of flavonoid (catechin) and phenolic acid mainly protocatechuic acid. Further research of more selected rice genetic resources would be continued to provide for an integrative phenolics profile of different rice genetic resources.

• Food Science of Animal Resources
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• v.43 no.6
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• pp.949-960
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• 2023

This research aimed to validate a high-performance liquid chromatography method for the quantitative determination of bixin and norbixin in various foods. The Diode Array Detector (495 nm) technique was used. Method was validated for specificity, linearity, limit of detection (LOD), limit of quantification (LOQ), precision, and accuracy, and the measurement uncertainty was assessed. The calibration curve showed excellent linearity (r²≥0.9999) over the tested concentration range of 0.2-25 mg/L. The LOD and LOQ were 0.03-0.11 and 0.02-0.05 mg/L for bixin and norbixin, respectively. The intra-and inter-day accuracies and precisions were 88.0±1.3-97.0±0.5% and 0.2%-2.6% relative SD (RSD) for bixin and 88.2±0.8-105.8±0.8% and 0.3%-2.7% RSD for norbixin, respectively. Inter-laboratory validation for accuracy and precision was conducted in three laboratories, and these results all met the AOAC guidelines. In addition, the relative expanded uncertainty (<22%) satisfied the CODEX recommendation. Furthermore, products distributed in Korea were monitored for annatto extracts using the proposed method to demonstrate its application. The developed analytical method is reliable for quantifying bixin and norbixin in various foods.

• Analytical Science and Technology
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• v.36 no.5
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• pp.205-215
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• 2023

In the present study, an analytical method was proposed for detecting trifluralin in aquatic products at trace concentrations. The method employed QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) and gas chromatography coupled with tandem mass spectrometry (GC-MS/MS) as the sample preparation and measurement, respectively. The effect of the aqueous phase volume used in the QuEChERS was demonstrated, and the ratio of 10:10 (mL) between water and acetonitrile phase was used for 5 g of sample. Besides, dSPE using C18 and primary-secondary amine (PSA) was applied to remove the potential interferences from the food matrices, indicating no remarkable analyte loss. The linear range was built up from 0.50 ㎍ L^-1 to 3.0 ㎍ L^-1 (R² = 0.9993). Other criteria, i.e., repeatability (RSD_r = 0.86-1.96 %), reproducibility (RSD_R = 1.09-2.01 %), and recovery (over 90 %), were in accordance with Appendix F of AOAC (2016) for method performance. Although no trifluralin was detected for the commercial samples (fish, shrimp, and breaded shrimp), the spiked samples performed favorable recoveries and precision.

• Journal of the Korean Society of Industry Convergence
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• v.27 no.3
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• pp.591-599
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• 2024

This paper presents the configuration and characteristic analysis of the protection system to improve the safety of the building integrated photovoltaic(BIPV) system. BIPV is a solar power system installed in buildings. Since the BIPV system is installed in buildings, there is a high risk of electric shock and fire accidents. Therefore, in order to improve the safety of BIPV, a protective system is required to block or quickly detect risk factors. In this paper, as a protection system to improve the safety of the BIPV system, it is composed of a rapid shutdown (RSD) that can quickly separate the PV system to prevent fire and electric shock accidents and a system to detect Arc faults that cause PV system fires. RSD and Arc Fault Detector analyzed the operating characteristics according to each condition and confirmed that the safety of the BIPV system can be improved through this.

• Coupled systems mechanics
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• v.13 no.4
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• pp.359-373
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• 2024

The present study aims to investigate the free vibration of bi-directional functionally graded (BDFG) beams using a refined shear deformation (RSD) theory. Power law variation of material composition was considered along thickness and longitudinal directions. The beams are considered simply supported. The methodology adopted is the Hamilton principle and the governing equation was solved using Navier's method for simply supported boundary conditions. A metal-ceramic combination of materials was used to provide gradation as per power law variation. The equivalent elasticity modulus and density of BDFG were computed using the rule of mixture. The results of the study were related to published works and found to be a good match. The effect of grading parameters in the thickness and longitudinal direction was studied to investigate its impact on the natural frequency.

• Journal of the Korean Society of Radiology
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• v.10 no.8
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• pp.597-602
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• 2016

Recent clinical field utilizes the aluminium filter in order to reduce the low-energy photons. However, the usage of the filter can cause adverse effect on the image quality because of the scattered dose that is generated by X-ray hardening phenomenon. Further, usage of filter with improper thickness can be a reason of dose creep phenomenon where unnecessary exposure is generated towards the patient. In this study, the author evaluated the RMS and the RSD analysis in order to have a quantitative evaluation for the effect of forward scattering dose by the filter on the image. as a result of the study, the FSR and the RSD was increased together with the increasing of thickness of the filter. In this study the RSD means the standard deviation of the mean value is relatively size. It can be understood that the signal-to-noise ratio decreases when the average value is taken as a signal and the standard deviation is judged as a noise. The signal-to-noise ratio can understanding as index of resolution at image. Based on these findings, it was quantitatively verified that there is a correlation of the image quality with the FSR by using an additional filter. The results, a 2.5 mmAl which is as recommended by NCRP in the tube voltage of 70 kVp or more showed the 14.6% on the RSD when the filter was not in used. these results are considered able to be utilized as basic data for the study about the filter to improve the quality of the image.