• Korean Chemical Engineering Research
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• v.51 no.1
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• pp.87-92
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• 2013

Microalgae have been suggested as a promising feedstock for producing biofuel because of their potential of lipid production. In this study, a first principles ODE model for microalgae growth and neutral lipid synthesis proposed by Surisetty et al. (2010) is investigated for the purpose of maximizing the rate of microalgae growth and the amount of neutral lipid. The model has 6 states and 12 parameters and follows the assumption of Droop model which explains the growth as a two-step phenomenon; the uptake of nutrients is first occurred in the cell, and then use of intra-cellular nutrient to support cells growth. In this study, optimal input design using D-optimality criterion is performed to compute the system input profile and sensitivity analysis is also performed to determine which parameters have a negligible effect on the model predictions. Furthermore, model predictive control based on successive linearization is implemented to maximize the amount of neutral lipid contents.

• Tunnel and Underground Space
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• v.24 no.4
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• pp.289-296
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• 2014

A simple analytical approach for stability assessment of underground storage caverns against ground uplift of overburden rock above the rock caverns for high pressurized fluid such as compressed air energy storage (CAES) and compressed natural gas (CNG) was developed. In the developed approach, we assumed that failure plane of the overburden is straight upward to ground surface, and factor of safety can be calculated from a limit equilibrium analysis in terms of this cylindrical shape failure model. The frictional resisting force on the failure plane was estimated by Hoek-Brown strength criterion which replaces with Mohr-Coulomb criterion such that both intact rock strength and rock mass conditions can be considered in the current approach. We carried out a parametric sensitivity analysis of strength parameters under various rock mass conditions and demonstrated that the factor of safety againt ground uplift was more sensitive to Mohr-Coulomb strength criterion rather than Hoek-Brown criterion.

• Proceedings of the KSME Conference
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• 2005.11a
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• pp.214.2-214.2
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• 2005

• Science of Emotion and Sensibility
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• v.15 no.4
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• pp.517-526
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• 2012

This study investigated the impact of individual differences in motivational reactivity on cognitive effort, memory strength (sensitivity) and decision making (criterion bias) in response to Internet ads with positive and negative content. Individual variation in trait motivational activation was measured using the Motivational Activation Measurement developed by A. Lang and her colleagues (A. Lang, Bradley, Sparks, & Lee, 2007). MAM indexes an individual's tendency to approach pleasant stimuli (ASA, Appetitive System Activation) and avoid unpleasant stimuli (DSA, Defensive System Activation). Results showed that individuals higher in ASA exert more cognitive effort during positive ads than individuals lower in ASA. Individuals higher in DSA exert more cognitive effort during negative ads compared to individuals lower in DSA. ASA did not predict recognition memory. However, individuals higher in DSA recognized ads better than those lower in DSA. The criterion bias data revealed participants higher in ASA had more conservative decision criterion, compared to participants lower in ASA. Individuals higher in DSA also showed more conservative decision criterion compared to individuals lower in DSA. The theoretical and practical implications are discussed.

• Structural Engineering and Mechanics
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• v.49 no.2
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• pp.183-202
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• 2014

A new method of multiple damage detection in beam like structures is introduced. The mode shapes of both healthy and damaged structures are used in damage detection process (DDP). Multiple Damage Localization Index Based on Mode Shapes (MDLIBMS) is presented as a criterion in detecting damaged elements. A finite element modeling of structures is used to calculate the mode shapes parameters. The main advantages of the proposed method are its simplicity, flexibility on the number of elements and so the accuracy of the damage(s) position(s), sensitivity to small damage extend, capability in prediction of required number of mode shapes and low sensitivity to noisy data. In fact, because of differential and comparative form of MDLIBMS, using noise polluted data doesn't have major effect on the results. This makes the proposed method a powerful one in damage detection according to measured mode shape data. Because of its flexibility, damage detection process in multi span bridge girders with non-prismatic sections can be done by this method. Numerical simulations used to demonstrate these advantages.

• Journal of muscle and joint health
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• v.21 no.1
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• pp.75-84
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• 2014

Purpose: The purpose of this study was to test the validity and reliability of the Korean version of the Geriatric Anxiety Inventory (K-GAI). Methods: Two hundreds and thirty six elderly were participated to test K-GAI. Goldberg's short screening scale for anxiety was tested for criterion validity. Receiver operating characteristics (ROC) analysis was used for measuring sensitivity and specificity. Results: The obtained internal consistency was 0.88. There were significant associations between test and retest results. K-GAI scores was significantly associated with Goldberg's short screening scale for anxiety (r=.694, p<.001). We found that a score of seven and greater was optimal for a criterion of anxiety among elderly Koreans. At this cut point, sensitivity was 78.9% and specificity was 73.1%. Conclusion: The K-GAI displayed good psychometric properties. This tool would be useful for early detection of anxiety among elderly Koreans with various situations including cognitive disorder, low education, or physical disability.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.10
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• pp.2475-2482
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• 1993

The effects of the hole size(2R) and the specimen width(W) on the fatigue strength and the fatigue life in plain woven glass/epoxy composite plates are experimentally investigated under constant amplitude tensile fatigue loading. It is shown in this study that the notch sensitivity under fatigue loading is lower than that under static loading. It can be explained by the fact that the stress concentration is relaxed by the damage developed at the boundary of circular hole. To predict the fatigue strength at a specific cycle, the modified point stress criterion represented as a function of the geometry of the specimen(2R and W) is applied. It is found that the model used in the prediction of the notched tensile strength predicts the fatigue strength with reasonable accuracy. A model for predicting the fatigue life in the notched specimen, based on the S-$N_f$, curve in the smooth specimen, is suggested.

• Journal of Oriental Medical Thermology
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• v.3 no.1
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• pp.15-19
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• 2004

Cold hypersensitivity means a condition feeling cold at a temperature when one should not feel so. Cold hypersensitivity has been diagnosed based on the patient's subjective complaints. But these days, cold hypersensitivity can be diagnosed by the help of D.I.T.I.(Digital Infrared Thermal Imaging) This study is designed to verify the validity of diagnosis of cold hypersensitivity by D.I.T.I. Thermographic findings of 100 outpatients who visited the Kangnam Korean Hospital, KyungHee University, Seoul, Korea, from June 2000 to November 2000 were analyzed. The experimental group consisted of 50 patients who complained cold hypersensitivity, and for the control group, 50 patients who did not complain cold hypersensitivity. For the diagnosis of cold hypersensitivity of the hands, thermographic measurements were performed on two pairs of areas(palm-upper arm and back of hand-upper arm). And for that of the feet, other two pairs of areas(anterior thigh-top of the feet and posterior thigh-heel). When the criterion for thermal deviation between the palm and the upper arm was appointed as higher than $0.3^{\circ}C$, the sensitivity was 94.0% and the specificity, 90.0%. And when the criterion for that between the anterior thigh and the top of feet was appointed higher than $2.0^{\circ}C$, the sensitivity was 94.0% and the specificity, 76.0%. Through this study, the diagnostic standard for cold hypersensitivity of hands and feet could be presented.

• Safety and Health at Work
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• v.10 no.3
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• pp.314-320
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• 2019

Background: Sitting posture may be related to risk factors, including inadequate weight-bearing support, particularly when maintained for long periods. Considering that body weight is loaded in a closed support system composed of the seat, backrest, floor and working surface, the aims of the present study were to describe the development of an ergonomic sitting workstation to continuously record weight-bearing at the seat, chair, backrest, work surface, and floor and to test its measurement properties: reproducibility, criterion-related validity, and sensitivity. Methods: Rigid bodies (1 to 30 kg) and participant weights were recorded to evaluate the workstation measurement properties. Results: Rigid body tests showed variation values less than 0.050 kg on reproducibility test and errors below 5% of measured value on criterion validity tests. Participant tests showed no statistically significant differences between repeated measures ($p{\geq}0.40$), errors were less than 2% of participant weights an sensitivity presented statistically significant changes (p = 0.007). Conclusion: The sitting workstation proposed showed to be reliable, valid and sensitive for use in future ergonomic studies to evaluate the sitting posture.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.2
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• pp.58-64
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• 2019

This paper describes the analysis of dynamic characteristics and prediction of the stiffness for the joint between structural members. In the process of deriving the governing equations, the stiffness values responsible for the moment and shear force were modelled by using linear and torsional springs in the middle of a clamped-clamped beam. The sensitivities of the natural frequency and modal assurance criterion were investigated as a function of the dimensionless linear and torsional spring stiffness. The reliability of the predictions for the linear and torsional stiffness values was verified by the inverse computations of the stiffness matrix. The predictive and exact theoretical stiffness values were compared for the stiffness element in the finite element formulation, and their results show an excellent correlation. It is strongly anticipated that although the proposed methodology is currently limited to the analytical utilization, it will provide a useful tool to estimate unknown joint stiffness values based on the experimental natural frequency and mode shape.