• Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
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• 2001.06a
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• pp.4111-4111
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• 2001

When a drug is prepared in a tablet, the active component represents only a small portion of the dosage form. The other components of the formulation include materials to assist in the dissolution, antioxidants, coloring agents and bulk fillers. The tablets are tested using approved testing methods usually involving separation and subsequent quantification of the active component. Tablets may also be tested by near-Infrared Reflectance spectrometry (NIRS). In the present study, based on NIRS and multivariate calibration methods, a novel and precise method is developed for direct determination of ascorbic acid in vitamin C tablet. Two different tablet formulations were powdered in three different sizes, 63-125 ${\mu}{\textrm}{m}$, and examined. Spectral region of 4750-4950 $cm^{-1}$ / was used and optimized for quantitative operations. Partial least squares (PLS) and multiple linear regression (MLR) methods were performed for this spectral region. The results of optimized PLS and MLR methods showed that reproducibility increase with decreasing grain size and standard error of calibration (SEP) of less than 1% w/w of ascorbic acid and a correlation coefficient of 0.998 can be achieved. The PLS method showed better results than MLR. Seven overdose and underdose samples (prepared in the laboratory to match marketed products) were tested by proposed and iodometric standard methods. A correlation between NIRS predicted ascorbic acid values and iodomet.ic values was calculated ($R^2$=0.9950). Finally, the direct analysis of individual intact tablets in their unit-dose packages (Blistering in aluminum and PVC foils) obtained from market were also carried out and a correlation coefficient of 0.9989 and SEP of 0.931% w/w of ascorbic acid were achieved.

• Spatial Information Research
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• v.21 no.3
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• pp.71-78
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• 2013

Continuous management of bicycle facilities is needed, as uses of bicycles are increased. In the previous studies, evaluation of bicycle facilities were performed mainly from the surveys to bicycle users and experts. This study aims to evaluate the facilities for bicycle uses by setting up the quantitative assessing measures for the purpose of contributing to balanced management of the facilities for bicycle uses. Based on the existing measures provided in the previous studies about conditions for bicycles users, the variables of the facilities that are available and quantifiable were derived, and the scales of the facilities were set up. For evaluation, the station influence areas in Songpa District were selected as test areas. The methods for analysis were, first, to carry out the 'bicycle roads-facilities' analysis, which was modified from quadrant method. Consequently, individual facilities and station areas were relatively examined. Second, by principal component analysis, bicycle facilities were analyzed in a general and integrated way. From that, the variables sharing common characteristics were grouped, similar types of stations influence areas were found out, and then the groups were ranked.

• Korean Journal of Adult Nursing
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• v.28 no.1
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• pp.95-105
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• 2016

Purpose: This study was conducted to test whether Health Communication Assessment Tool (HCAT) developed by Campbell et al. in 2013 can be applied to assess Korean nursing students' communication skills in simulation education. Methods: The content validity of the Korean version of HCAT (K-HCAT) was evaluated through expert's assessment and a principal component analysis was conducted for testing construct validity. The convergent validity was tested by measuring relationship between the K-HCAT and those of existing communication assessment tool for standardized patient instruction. The evaluation was done by surveying 154 senior students from four different nursing colleges. Results: The K-HCAT was condensed into 15 items from the original 22 HCAT items. Four factors were extracted from the principal component analysis; factor loadings ranged from .50 to .83; cumulative explained variance was 62.65%. Four factors were entitled as 'relationship building', 'empowering', 'empathy/response', and 'education/feedback'. Cronbach's ${\alpha}$ for sub-dimensions ranged from .73 to .84. An evaluation of convergent validity showed that the scores of the K-HCAT were moderately correlated with those of an assessment tool for standardized patient instruction. Conclusion: The K-HCAT can be used as an effective tool for assessing nursing students' communication skills in various kinds of simulation educations Further research is needed to test the consistency of the K-HCAT.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.660-665
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• 2006

This paper presents a finite element method to analyze the free and forced vibration of a hard disk drive (HDD) considering the flexibility of a spinning disk-spindle with fluid dynamic bearings (FDBs), an actuator with pivot bearings, an air bearing between head-disk interface and the base with complicated geometry. Finite element equation of each component is consistently derived with the satisfaction of the geometric compatibility of the internal boundary between each component. The spinning disk, hub and FDBs are modeled by annular sector elements, beam elements and stiffness and damping elements, respectively. The actuator am, E-block, suspension and base plate are modeled by tetrahedral elements. The pivot bearing in the actuator and the air bearing between head-disk interfaces are modeled by the stiffness element with five degrees of freedom and the axial stiffness, respectively. A global matrix equation obtained by assembling the finite element equations of each substructure is transformed to a state-space matrix-vector equation, and both damped natural frequencies and modal damping ratios are calculated by solving the associated eigenvalue problem with the restarted Arnoldi iteration method. Modal and shock testing are performed to show that the proposed method well predicts the vibration characteristics of a HDD.

• Journal of The Korean Association For Science Education
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• v.18 no.4
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• pp.545-555
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• 1998

The improvement of process skills has been one of the most important goals in secondary science education. To achieve this goal, it is essential to develop an instrument for evaluating inquiry skills in addition to improving science curricula, inquiry teaching methods, and other educational environment. There are a lot of instruments in testing science process skills in Korea as well as America and Europe. However, it has been difficult to find the instruments that have a characteristic in content and form. The purpose of this study is to develop a valid and reliable instrument for evaluating science process skills using line graph. This study examined the whole body of scientific process and identified 6 component skills. Three or four items for each component process skills were developed and revised by pilot test and field test. The instrument is considered valid and reliable, for the content validity is 78% and the reliability(KR-20) is 0.82. The discrimination index is 0.57 and difficulty index is 0.47, which also suffice the criteria of good test.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.12
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• pp.1040-1047
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• 2012

This paper presents a fault diagnosis algorithm of control surfaces of small fixed-wing aircraft to reduce maintenance cost or to improve repair efficiency by estimation of fault occurrence or part replacement periods. The proposed fault diagnosis algorithm consists of ANPSD (Averaged Normalized Power Spectral Density), PCA (Principle Component Analysis), and GC (Geometric Classifier). ANPSD is used for frequency-domain vibration testing. PCA has advantage to extract compressed information from ANPSD. GC has good properties to minimize errors of the fault detection and isolation. The algorithm was verified by the accelerometer measurements of the scaled normal and faulty ailerons and the test results show that the algorithm is suitable for the detection and isolation of the control surface faults. This paper also proposes solutions for some kind of implementation problems.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.5
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• pp.66-72
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• 2019

To improve ride quality and running stability of high speed train(HST), it is important that connection between coaches adopts the articulated bogies by using a gangway ring, unlike the conventional independent bogies assembled with car bodies. Although the gangway ring should be ensured absolute safety against passenger movement between coaches during train operation, there is still a lack of quantitative durability criteria of that. Therefore, in order to improve the passenger safety of HST, it is important to study the test requirements on durability evaluation for the ring. In this study, seven mixed loading cases were derived from the triaxial loading(vertical/lateral/longitudinal) modes. The safety factor of each component is at least 2.4 or more from the results of the finite element analysis. In addition, fatigue safety was evaluated through durability analysis from the viewpoint of strain-life design. Durability tests for the gangway ring carried out a total of 10 million cycles in 4 phases load conditions. After the durability test, the defect of each component was investigated using nondestructive testing techniques.

• Food Science and Preservation
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• v.30 no.4
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• pp.573-588
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• 2023

The purpose of this study was to monitor changes in the quality of ginseng and predict its shelf-life. As the storage period of ginseng increased, some quality indicators, such as water-soluble pectin (WSP), CDTA-soluble pectin (CSP), cellulose, weight loss, and microbial growth increased, while others (Na₂CO₃-soluble pectin/NSP, hemicellulose, starch, and firmness) decreased. Principal component analysis (PCA) was performed using the quality attribute data and the principal component 1 (PC1) scores extracted from the PCA results were applied to the multivariate analysis. The reaction rate at different temperatures and the temperature dependence of the reaction rate were determined using kinetic and Arrhenius models, respectively. Among the kinetic models, zeroth-order models with cellulose and a PC1 score provided an adequate fit for reaction rate estimation. Hence, the prediction model was constructed by applying the cellulose and PC1 scores to the zeroth-order kinetic and Arrhenius models. The prediction model with PC1 score showed higher R² values (0.877-0.919) than those of cellulose (0.797-0.863), indicating that multivariate analysis using PC1 score is more accurate for the shelf-life prediction of ginseng. The predicted shelf-life using the multivariate accelerated shelf-life test at 5, 20, and 35℃ was 40, 16, and 7 days, respectively.

• Hip & pelvis
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• v.36 no.2
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• pp.129-134
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• 2024

Purpose: Preoperative planning has become essential in performance of total hip arthroplasty (THA). However, data regarding the effect of the planner's experience on the accuracy of digital preoperative planning is limited. The objective of this study was to assess the accuracy of digital templating in THA based on the surgeon's experience. Materials and Methods: A retrospective study was conducted. An analysis of 98 anteroposterior pelvic radiographs, which were individually templated by four surgeons (two hip surgeons and two orthopaedic residents) using TraumaCad^® digital planning, was performed. A comparison of preoperatively planned sizes with implanted sizes was performed to evaluate the accuracy of predicting component size. The results of preoperative planning performed by hip surgeons and orthopaedic residents were compared for testing of the planner's experience. Results: Femoral stem was precisely predicted in 32.4% of cases, acetabular component in 40.3%, and femoral offset in 76.7%. Prediction of cup size showed greater accuracy than femoral size among all observers. No differences in any variable were observed among the four groups (acetabular cup P=0.07, femoral stem P=0.82, femoral offset P=0.06). All measurements showed good reliability (intraclass correlation coefficient [ICC] acetabular cup: 0.76, ICC femoral stem: 0.79). Conclusion: The results of this study might suggest that even though a surgeon's experience supports improved precision during the planning stage, it should not be restricted only to surgeons with a high level of experience. We consider preoperative planning an essential part of the surgery, which should be included in training for orthopaedics residents.

• Journal of Wind Energy
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• v.13 no.3
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• pp.13-21
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• 2022

When a wind turbine is designed, the dynamic stability of the system as well as the dynamic characteristics of the main components such as blades, hub, main shaft and tower must be evaluated. In particular, the natural frequencies of a blade, as a main load-generating component, need to be measured and assessed by component level testing. In conventional practice, the natural frequencies of a blade are determined as the measured frequencies near the reference frequencies provided by FE analysis results. But the reference frequencies are also uncertain since designers have difficulty distinguishing the torsional mode shape among the analysis results due to the complexity of its mode shape. So, in conventional practice, the determination of a measured torsional frequency inevitably contains uncertainty. Therefore, a novel method to definitely determine the torsional frequencies from the experimental data itself is necessary. In this paper, a new methodology to measure the torsional frequency of a blade was studied from the perspective of a modal test procedure, data processing method and mode determination logic. Finally, the validity of the method that can measure torsional frequency without reference FE analysis results was verified by applying it to an actual large wind turbine blade