• Journal of the Korean Society of Food Science and Nutrition
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• v.46 no.9
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• pp.1091-1096
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• 2017

The aim of this study was the validation of a modified analytical method for determination of oxypaeoniflorin and paeoniflorin in Moutan Cortex Radicis extract. For validation of the analytical method, we modified established analytical methods and validated improvement. For validation, the specificity, linearity, precision, accuracy, limit of detection (LOD), and limit of quantification of oxypaeoniflorin and paeoniflorin were measured by high performance liquid chromatography. The results show that the correlation coefficients of the calibration curve for oxypaeoniflorin and paeoniflorin were 1.0000 and 0.9998, respectively. The LOD for oxypaeoniflorin and paeoniflorin were $0.23{\mu}g/mL$ and $0.25{\mu}g/mL$, respectively. The inter-day and intra-day precision values of oxypaeoniflorin and paeoniflorin were 0.70~3.19% and 1.74~2.43%, and 0.32~0.92% and 0.62~2.28%, respectively. The inter-day and intra-day accuracies of oxypaeoniflorin and paeoniflorin were 98.33~102.11% and 97.72~118.12%, and 98.44~101.56% and 97.10~112.00%, respectively. Therefore, the analytical method was validated for the detection of oxypaeoniflorin and paeoniflorin in Moutan Cortex Radicis.

• Smart Structures and Systems
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• v.26 no.3
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• pp.391-401
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• 2020

The present article reports the feasibility of the electrical energy generation from ambient low-frequency vibration using a piezoelectric material mounted on a bimorph cantilever beam actuator. A corresponding higher-order analytical model is developed using MATLAB in conjunction with finite element method under low-frequency with both damped and undamped conditions. An alternate model is also developed to check the material and dimensional viability of both piezoelectric materials (mainly focussed to PVDF and PZT) and the base material. Also, Genetic Algorithm is implemented to find the optimum dimensions which can produce the higher values of voltage at low-frequency frequencies (≤ 100 Hz). The delamination constraints are employed to avoid inter-laminar stresses and to increase the fracture toughness. The delamination has been done using a Teflon sheet sandwiched in between base plates and the piezo material is stuck to the base plate using adhesives. The analytical model is tested for both homogenous and isotropic material characteristics of the base material and extended to investigate the effect of the different geometrical parameters (base plate dimensions, piezo layer dimensions and placement, delamination thickness and placement, excitation frequency) on the model responses of the bimorph cantilever beam. It has been observed that when the base material characteristics are homogenous, the efficiency of the model remains higher when compared to the condition when it is of isotropic material. The necessary convergence behaviour of the current numerical model has been established and checked for the accuracy by comparing with available published results. Finally, using the results obtained from the model, a prototype is fabricated for the experimental validation via a suitable circuit considering Glass fibre and Aluminium as the bimorph material.

• Journal of Pharmaceutical Investigation
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• v.37 no.6
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• pp.329-338
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• 2007

The quality assurance issue of drug products is more important than the general product because it is highly related to the human health and life. In this reason, the regulatory guide lines have continuously been intensified all around the world. In order to achieve effective quality assurance and real-time product release (RTPR) of drug products, process analytical technology (PAT), which can analyze and control a manufacturing process, has been proposed from the United States. With the PAT process, we can obtain significant process features of materials, quality characteristics and product capabilities from a raw material to the final product in the real-time procedure. PAT can also be utilized to process validation using information system that can analyze the risk of drug products through out an entire product life-cycle. In this paper, we first offered a new concept for the off-line process design methods to prepare the improved quality assurance restrictions and a real-time control method by establishing an information system. We also introduced an automatic inspection system by obtaining surrogate variables based on drug product formulations. Finally, we proposed an advanced PAT concept using validation and feedback principles through out the entire life-cycle of drug product manufacturing processes.

• Analytical Science and Technology
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• v.34 no.2
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• pp.68-77
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• 2021

Cannabis is one of the most abused drugs in Korea. The main psychoactive component in cannabis, Δ9-tetrahydrocannabinol, is metabolized to 11-nor-9-carboxy-Δ9-tetrahydrocannabinol (THCCOOH) and THCCOOH-glucuronide (THCCOOH-glu) in the human liver, whereby the amount of THCCOOH-glu found in urine is twice as high as that of THCCOOH. The analytical process adapted by the majority of urine drug-testing programs involves a two-step method consisting of an initial immunoassay-based screening test followed by a confirmatory test if the screening test result is positive. In this study, a qualitative gas chromatography-mass spectrometry (GC-MS) method was developed and validated for the detection of THCCOOH in human urine, where THCCOOH-glu was converted into THCCOOH by alkaline hydrolysis. For purification of the urine extract prior to instrumental analysis, high-speed centrifugation was used to minimize interference. In addition, an injection-port derivatization method using ethyl acetate and N,O-bis(trimethylsilyl)-trifluoroacetamide containing 1 % trimethylchlorosilane was employed to reduce the time required for derivatization, and an aliquot of the final solution was injected into the GC-MS. The method was validated by measuring the selectivity, limit of detection (LOD), and repeatability. The sensitivity, specificity, precision, accuracy, Kappa, F-measure, false positive, and false negative rate were determined by comparing the GC-MS results with those obtained using the immunoassay. The LOD was determined to be 0.32 ng/mL, while the repeatability was within 9.1 % for THCCOOH. Furthermore, a comparison study was carried out, whereby the screening immunoassay exhibited a sensitivity of 86.4 % and a specificity of 100 % compared to GC-MS. The applicability of the developed method was examined by analyzing spiked urine and forensic urine samples obtained from suspected cannabis abusers (n = 221).

• Korean journal of applied entomology
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• v.61 no.4
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• pp.659-664
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• 2022

Putrescine generated by the action of microorganisms in the decay generally used as a measure of freshment in food. However, the analytical method of putrescine in freeze-dried royal jelly has not yet been established. In the present study, the UPLC method for putrescine in lyophilized royal jelly was established using C18 column. The newly established method was able to analyze putrescine accurately within 7 minutes and was validated by analytical parameters such as specificity, linearity, precision, accuracy, limit of detection, and limit of quantification. These results provide for the analytical method to evaluate the level of freshment in freeze-dried royal jelly, which will useful in further studies of safety verification.

• YAKHAK HOEJI
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• v.59 no.3
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• pp.98-106
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• 2015

Analytical method for related substances can be categorized into two methods depending on the necessity of reference standard (RS). The analytical method of related substances with RS is fast and accurate, but it's very expensive and technically difficult to synthesize RS due to their complicated structure. Another method is using relative retention time (RRT) and relative response factor (RRF) which are already validated with RS. Validation of this method is not easy and time consuming, but once it has been developed, it can save cost and time. In this study, we developed the analytical method for related substances of fenofibrate using RRT and RRF. We validated the method by evaluating specificity, linearity, accuracy and precision according to the "Manual for Guideline Application for Validation of Analytical Procedures" of MFDS. Also, we calculated RRT and RRF between fenofibrate and fenofibrate related substances. The results of this study showed high specificity for fenofibrate and fenofibrate related substances. Correlation coefficient(r) of all substances were more than 0.99, and the recovery of fenofibrate, fenofibrate related substance I, II and III were 99.44%, 100.84%, 99.14% and 101.58%, respectively. Precision of fenofibrate and its related substances were ranged between RSD 0.29% and 0.93%. Quantification limits of fenofibrate, fenofibrate related substance I, II and III were determined to be $0.03{\mu}g/ml$, $0.05{\mu}g/ml$, $0.04{\mu}g/ml$ and $0.02{\mu}g/ml$, respectively by confirming signal to noise ratio of each chromatogram. The RRT for fenofibrate related substance I, II and III were determined to be 0.35, 0.41 and 1.34, respectively. Also, the RRF for fenofibrate related substance I, II and III were determined to be 1.28, 0.98 and 0.79, respectively. The developed method was applied to determine contents for fenofibrate related substances in commercial fenofibrate (active pharmaceutical ingredient). As a result, developed analytical methods of related substances will be used for revising the monograph of fenofibrate in Korean Pharmacopoeia revision and contribute quality control of drugs by improving cost and time consuming problem of RS.

• YAKHAK HOEJI
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• v.58 no.3
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• pp.190-199
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• 2014

The Korean Pharmaceutical Codex (KPC) analytical method of ambroxol hydrochloride and clenbuterol hydrochloride formulation is complicated and needed to carry out multiple processes during the test. To improve the low efficiency of analytical procedure that makes pharmaceutical laboratory consume much time and high cost to conduct the test of this formulation, this study was performed for simplifying the pretreatment process and optimizing conditions of the HPLC assay. The analytical procedure using HPLC was developed to establish analytical specification for ambroxol hydrochloride and clenbuterol hydrochloride formulations. The newly developed analytical method has good linearity ($R^2$ >0.999), specificity, precision (RSD<1.0%) and the recovery ranges of 98.50~101.84% for ambroxol, 98.29~101.35% for clenbuterol syrup and 98.66~101.71% for clenbuterol tablets. The LOQs were 0.204 ${\mu}g/ml$ for ambroxol, 0.021 ${\mu}g/ml$ for clenbuterol syrup and 0.073 ${\mu}g/ml$ for clenbuterol tablets. The new method was performed with commercially available samples to confirm analytical conditions and validated to be suitable for saving time and cost to control the quality of routine manufactured products. This analytical method will be used for revising the monograph of ambroxol hydrochloride and clenbuterol hydrochloride formulation in next supplement of KPC.

• Journal of Electrical Engineering and Technology
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• v.10 no.4
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• pp.1674-1681
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• 2015

This paper presented an improved analytical method for calculating armature-reaction field in the surface-mounted permanent magnet machines accounting for opening slots. The analytical model is divided into two types of subdomains. The current of the armature is centralized in the center of the slots. The field solution of each subdomain is obtained by applying the interface and boundary conditions of the model. Two 30-pole/36-slot prototype machines with different slot-opening width are used for validation. The FE (finite element) results confirm the validity of the analytical results with the proposed model. The investigation shows that the wider the slot-opening width is, the smaller the peak value of radial and circumferential components of flux density, and the analytical armature-reaction field produced by centralized current in the slots is similar with the armature-reaction field produced by distributed current in the slots in the FE.

• Journal of Electrical Engineering and Technology
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• v.10 no.3
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• pp.990-1001
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• 2015

This paper presents analysis of Switched Reluctance Machine (SRM) using Geometry Based Analytical Model (GBAM), Finite Element Analysis (FEA) and Fourier Series Model (FSM) with curve fitting technique. Further a Transient Analysis (TA) technique is proposed to corroborate the analysis. The main aim of this paper is to give in depth procedure in developing a Geometry Based Analytical Model of Switched Reluctance Machine which is very accurate and simple. The GBAM is developed for the specifications obtained from the manufacturer and magnetizing characteristic of the material used for the construction. Precise values of the parameters like Magneto Motive Force (MMF), flux linkage, inductance and torque are obtained for various rotor positions taking into account the Fringing Effect (FE). The FEA model is developed using MagNet7.1.1 for the same machine geometry used in GBAM and the results are compared with GBAM. Further another analytical model called Fourier Series Model is developed to justify the accuracy of the results obtained by the methods GBAM and FEA model. A prototype of microcontroller based SRM drive system is constructed for validating the analysis and the results are reported.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.11
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• pp.3655-3665
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• 1996

An analytical solution is presented for the conduction-dominated solidification of a binary mixture in a semi-infinite medium. The present approach differs from that of other solution by these four characteristics. (1) Solid fraction is determined from the phase diagram, (2) thermophysical properties in mushy zone are weighted according to the local solid fraction, (3) non-equilibrium solidification can be simulated and (4) the cooling condition of under-eutectic temperature can be simulated. Up to now, almost all analyses are based on the assumption of constant properties in mushy zone and solid fraction linearly with temperature or length. The validation for these assumptions, however, shows that serious error is found except some special cases. The influence of microscopic model on the macroscopic temperature profile is very small and can be ignored. But the solid fraction and average solid concentration which directly influence the quality of materials are drastically changed by the microscopic models. An approximate solution using the method of weighted residuals is also introduced and shows good agreement with the analytical solution. All calculations are performed for NH$_{4}$Cl-H$_{2}$O and Al-Cu system.