• Journal of Ginseng Research
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• v.43 no.3
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• pp.368-376
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• 2019

Background: In the current phytochemical research on ginseng, the differentiation and structural identification of ginsenosides isomers remain challenging. In this paper, a two-dimensional mass spectrometry (2D-MS) method was developed and combined with statistical analysis for the direct differentiation, identification, and relative quantification of protopanaxadiol (PPD)-type ginsenoside isomers. Methods: Collision-induced dissociation was performed at successive collision energy values to produce distinct profiles of the intensity fraction (IF) and ratio of intensity (RI) of the fragment ions. To amplify the differences in tandem mass spectra between isomers, IF and RI were plotted against collision energy. The resulting data distributions were then used to obtain the parameters of the fitted curves, which were used to evaluate the statistical significance of the differences between these distributions via the unpaired t test. Results: A triplet and two pairs of PPD-type ginsenoside isomers were differentiated and identified by their distinct IF and RI distributions. In addition, the fragmentation preference of PPD-type ginsenosides was determined on the basis of the activation energy. The developed 2D-MS method was also extended to quantitatively determine the molar composition of ginsenoside isomers in mixtures of biotransformation products. Conclusion: In comparison with conventional mass spectrometry methods, 2D-MS provides more direct insights into the subtle structural differences between isomers and can be used as an alternative approach for the differentiation of isomeric ginsenosides and natural products.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.12 no.3
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• pp.427-435
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• 1999

In the field of shape optimum design, much efforts are needed in regridding method and shape design sensitivity analysis. In this paper, Bezier curve is used to make the boundary of a structure and the improved direct differentiation method is used to calculate the shape design sensitivity. To regrid the finite element model, modified displacement field is presented in this paper. The modified displacement field makes more fine grid at large curvature. The purpose of this paper is to obtain the optimum shape of a cantilever with weight and a 3-dimensional journal bearing cap.

• Structural Engineering and Mechanics
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• v.52 no.6
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• pp.1099-1120
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• 2014

In this paper, reliability-based design optimization (RBDO) of structures is addressed. For this purpose, the global search and optimization capabilities of genetic algorithm (GA) are combined with the efficiency and reasonable accuracy of an advanced moment-based finite element reliability method. For performing RBDO, three variants of GA including a real-coded, a binary-coded and an improved binary-coded GA are developed. In these methods, GA performs (finite element) reliability analyses to evaluate reliability constraints. For truss structures which include finite element modeling, reliability constraints are evaluated using finite element reliability analysis. Response sensitivity required for finite element reliability analysis is obtained by direct differentiation method (DDM) rather than finite difference method (FDM). The proposed methods are examined within four standard test examples and real-world design problems. The results illustrate the superiority and efficiency of the improved binary-coded GA. Results also illustrate that DDM significantly reduces the computational cost and improves the efficiency of the optimization procedure.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.11
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• pp.2262-2269
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• 2002

Process optimization is carried out to determine process parameters which satisfy the given design requirement and constraint conditions in sheet metal forming processes. Sensitivity -based-approach is utilized for the optimum searching of process parameters in sheet metal forming precesses. The scheme incorporates an elasto-plastic finite element method with shell elements . Sensitivities of state variables are calculated from the direct differentiation of the governing equation for the finite element analysis. The algorithm developed is applied to design of the variablc blank holding force in deep drawing processes. Results show that determination of process parameters is well performed to control the major strain for preventing fracture by tearing or to decrease the amount of springback for improving the shape accuracy. Results demonstrate that design of process parameters with the present approach is applicable to real sheet metal forming processes.

• Communications of the Korean Mathematical Society
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• v.32 no.2
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• pp.425-433
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• 2017

This paper is concerned with the analysis of the busy period distribution in a batch arrival $M^X/G/1$ retrial queue. The expression for the Laplace-Stieltjes transform of the length of the busy period is well known, but from this expression we cannot compute the moments of the length of the busy period by direct differentiation. This paper provides a direct method of calculation for the first and second moments of the length of the busy period.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.04a
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• pp.378-382
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• 1996

This paper presents a 'mixed' method for performing the sensitivity analysis for multibody dynamics. The mixed method uses both the analytical derivation and the numerical evaluation, in which premitive derivations rely on the analytical process and their associated individual terms are evaluated by the numerical precess. Therefore, this method can eliminate difficulty in dervation of the direct differentiation. Furthermore, by using the joint coordinate formulation for the equations of motion, compulational efficiencyand numerical accuracy are achieved.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.7 no.3
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• pp.110-117
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• 1998

A continuum-based configuration design sensitivity analysis method is developed for kinematically driven mechanical systems. The configuration design variable for mechanical systems is defined. The 3-1-3 Euler angle is employed as the orientation design variable. Kinematic admissibility conditions of configuration design change. Direct differentiation method is used to derive the governing equations of the design sensitivity. Numerical examples are presented to demonstrate the validity and effectiveness of the proposed method.

• The Journal of Internal Korean Medicine
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• v.32 no.1
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• pp.75-86
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• 2011

Objectives : This study investigated oriental diagnosis and treatment of reflex esophagitis (RE) such as syndrome differentiation and herbal medicine by reviewing Chinese journals. Methods : A journal search was performed using China National Knowledge Infrastructure (CNKI) from January 2006 to December 2010. The keywords were the various combinations of 'reflex esophagitis', 'Chinese medicine', 'syndrome differentiation', and 'herbal medicine'. All types of journal entries that explained or referred to herbal medicines and definite syndrome differentiations were included. The Types of the journals were randomized clinical trials (RCT), reviews, essays, case series and reports. Vague syndrome differentiations and experimental studies were excluded. Selected journals were extracted and summarized by two researchers independently. Results : 47 Chinese entries were finally selected. 61% of them were case-control trials that had non-randomized, active controlled clinical trials. 36 kinds of syndrome differentiations about RE were investigated. We summarized and divided them into 10 syndrome differentiation groups. 肝胃不和(syndrome of liver qi invading the stomach) in syndrome differentiation, 和胃降逆 (harmonize the stomach and direct qi downward) in method of treatment, and Jwa kum-whan (左金丸) were cited with high frequency in RE. Conclusions : We find that many kinds of syndrome differentiation groups and herbal medicines for reflex esophagitis are used in China, compared with Korea. Further studies will be required about oriental syndrome differentiation and treatment of this disease.

• Proceedings of the KSR Conference
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• 1998.05a
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• pp.299-306
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• 1998

Design sensitivity analysis of a mechanical system is an essential tool for design optimization and trade-off studies. This paper presents an efficient algorithm for the design sensitivity analysis of railway vehicle systems, using the direct differentiation method. The cartesian coordinate is employed as the generalized coordinate. The governing equations of the design sensitivity analysis are formulated as the differential equations. Design sensitivity analysis of railway vehicle systems is performed to show the validity and efficiency of the proposed method.

• Animal cells and systems
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• v.3 no.1
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• pp.73-78
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• 1999

Although there are several methods for the preparation of mitochondrial DNA (mtDNA) from mammalian tissues, most are relatively long ultracentrifugation or manipulations by a small-scale method. We escribed a rapid method for large-scale extraction of mtDNA from human placental and horse liver tissues. The method is based on the preparation and homogenization of tissues, urification of crude mitochondria by differential centrifugations and isolation of mtDNA by alkaline Iysis. It was improved from Pre-existing methods by replacing some steps with simpler ones and discarding many others. This method gives a high yield of pure mtDNA(approximately 1-5mg from one placenta; ca. 400-600 g wet weight), depending on its sources (fresh tissue gave better results than frozen one). The resulting mtDNA indicated that this method can yield mtDNA in sufficient purity and quantity to identify the direct restriction analysis on agarose gel, random-primed labeling as a probe, and end labeling. Therefore, the method is ideal for obtaining good mtDNA samples to conduct routine restriction fragment length polymorphism (RFLP) analyses of natural populations for genetic studies.