• Mass Spectrometry Letters
• /
• v.13 no.3
• /
• pp.58-83
• /
• 2022

We developed analytical methods using high performance chromatography (HPLC) and liquid chromatography tandem mass spectrometry (LC-MS/MS) for the simultaneous determination of 80 unapproved compounds in dietary supplements. The target compounds for analysis were unapproved ingredients (e.g., pharmaceuticals) that have potential adverse effects on consumers owing to accidental misuse, overuse, and interaction with other medication in dietary supplement. Two analytical methods were tested to identify the optimal validation results according to AOAC guideline. As a result, limit of quantification (LOQ) was 0.14-0.5 ㎍ mL^-1; linearity (r²) was ≥ 0.99; accuracy (expressed as recovery) was 78.9-114%; precision (relative standard deviation) was ≤ 4.28% in the HPLC method. In the LC-MS/MS method, LOQ was 0.01-2 ng mL^-1, linearity (r²) was ≥0.98, accuracy was 71.7-119%; precision was ≤ 12.5%. The developed methods were applied to 51 dietary supplements collected from 2019 to 2021 through MFDS alert system. Based on our previous monitoring study, major compounds were icariin, sibutramine, yohimbine, sildenafil, tadalafil, sennosides (A, B), cascarosides (A, B, C, D), and phenolphthalein. In this study, we re-analyzed samples of detected compounds, and evaluated the statistical difference using Bland-Altman analysis to compare two analytical approaches between HPLC and LC-MS/MS. These results showed a good agreement between two methods that can be used to monitor the unapproved ingredients in dietary supplements. The developed two methods are complementarily suitable for monitoring the adulteration of 80 unapproved compounds in dietary supplements.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2008.03a
• /
• pp.1417-1421
• /
• 2008

Temperature variation affect the response of asphalt pavement and should be considered in the evaluation of performance of the pavement. In this paper, HWAW method is applied to evaluate shear wave velocity(or shear modulus) of the asphalt pavement with temperature. HWAW method which is based on time-frequency analysis using harmonic wavelet transform have been developed to determine phase and group velocities of waves. This method minimize effect of noise and is not affected by mode jump effect which cause erroneous result when surface wave method is applied to pavement evaluation. In order to estimate the applicability of HWAW method, field tests were performed in 1 site and preliminary correlation between shear wave velocity(shear modulus) and asphalt pavement average temperature.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.29 no.7 s.238
• /
• pp.947-954
• /
• 2005

The purpose of this study is to develop failure pressure evaluation models, which are applicable to straight pipes and elbows containing an internally wall thinning defect induced by flow-accelerated-corrosion (FAC). In this study, thus, three dimensional finite element (FE) analyses are performed to investigate the dependences of failure pressure of internally wall thinned pipe on the defect shape, the pipe geometry, and the defect location and bend radius of elbow. Also, the existing failure pressure assessment models for externally wall thinned pipes are examined. Based on these, the new models for assessing failure pressure of piping components with an internally wall thinning defect are proposed. Comparison of failure pressure, predicted by proposed models, with FE analysis result shows good agreement regardless of pipe type, defect shape, and defect location and bend radius.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2012.05a
• /
• pp.111-112
• /
• 2012

The purpose of this study is to evaluate a defect in apartment buildings as review a safety investigation and consult a defect. As a result to compare a safety investigation to consult a defect, they are almost similar in spite of the purpose and the scope of evaluation are different. Therefore, it needs to establish a special and systemic system, and follow an organized effort about raising a consultant and improving an ability.

• Hwankyungkyoyuk
• /
• v.23 no.4
• /
• pp.96-111
• /
• 2010

The purpose of this study is to develop criteria that can evaluate the application and implementation process of Education for Sustainable Development (ESD). The subject of study is: What are the criteria to evaluate the degree of implementation of ESD in schools, and how can they be developed? In addition, the criteria questions for ESD were conducted by teachers from research and model schools in T city which applied ESD in school education. As a result, evaluation criteria questions have 3 major, 16 medium and 105 minor categories, which can evaluate ESD in school education by using a total of four kinds of analysis framework including the ESD criteria questions of ENSI (Environment and School Initiatives).

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2004.10a
• /
• pp.677-680
• /
• 2004

This study investigates the buckling evaluation of connecting rods used in the diesel engine through finite element analysis. The Rankine formula, which is modified from classical Euler‘s formula, has been widely accepted in automotive industry to evaluate the buckling of connecting rods. Apparently, this formula is most suitable for the straight and idealized rod shape, and over-simplifies the geometric complexity associated with connecting rods. The subspace iteration method in FEA is used to predict the critical buckling stress of a connecting rod with certain slenderness ratio. To create models with various slenderness ratios for shank portion in the rod, the automatic meshing preprocessor was implemented. Results from FEA were verified by the experiments, in which the embedded strain gages measured for the connecting rod running at 4000rpm. The result indicates that the buckling prediction curve through FEA and experiment is effectively different from the curve of classical Rankine formula.

• Journal of the Korean Home Economics Association
• /
• v.25 no.3
• /
• pp.27-36
• /
• 1987

The purpose of this study was to develop a slacks pattern drafting method for the fatty women of 40∼55 aged Korean women who are more than 1.5 Rohrer's index on the basis of their physical characteristics. The study was composed as follows; 1. Body measurement and statistical analysis: One hundred and thirty women between the ages of 40∼55 over 1.5 Rohrer's index were measured on 21 items. Mean, standard deviation, variance, maximum, minimum, range were computed. 2. 4 types of conventional slacks pattern were collected. The most accepted conventional slacks pattern was decided through wearing test. The new pattern was based onthe most accepted conventional pattern, and developed through wearing tests. 3. Evaluation of the new pattern drafting method: The sensory evaluation was applied to evaluate the new pattern by comparing is with the most accepted conventional pattern. According to the statistical analysis of the result of the 12 items, all the items showed significant differences (α 0.01) between the two, with the new pattern having higher scores.

• Proceedings of the KSR Conference
• /
• 2000.11a
• /
• pp.402-409
• /
• 2000

In order to evaluate the stability of railway embankment under rainfall, explanatory variables and subordinate variables wet-e selected for multivariate analysis. Furthermore the site which had occurred failure due to rainfall was investigated, and by executing multivariate analysis for 121 cases, critical rainfall was defined by the case that had high value of correlation factor. The maximum hourly rainfall during 24 hours before failure caused the collapse of railway embankment and could be used estimate the stability of railway embankment. From the result of application to a collapse example, the evaluation method by critical rainfall curve is satisfactory.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.19 no.2
• /
• pp.94-99
• /
• 2005

This paper presents the integrity evaluation method of the windings in cast resin transformers using vertical thermal distribution analysis. The method is the result from comparing the temperature distribution in a sound condition specimen with that in the failure condition specimen layer-shorted by accelerated testing. The temperature distribution was acquisited by a infrared thermography system, and the Arrhenius equation was adopted to the accelerated testing. The proposed method may be available to detect the failures in cast resin transformers.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2017.11a
• /
• pp.167-168
• /
• 2017

In this research, the blast-furnace slag powder using the hydrometer also attempted to analysis the influence factor due to the temperature change of water and sample, and the number of upside down turns at the time of rapid evaluation. As a result, the influence of the number of turn was not large, but was the temperature of the water and sample are greatly affected.