• Nuclear Medicine and Molecular Imaging
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• v.41 no.6
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• pp.561-565
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• 2007

Purpose: Lipophilic cations including tetraphenylphosphonium (TPP) salts penetrate the hydrophobic barriers of the plasma and mitochondrial membranes, resulting in accumulation in mitochondria in response to the negative inner transmembrane potentials. The development of radiolabeled phosphonium cations as a noninvasive imaging agent may serve as a new molecular "voltage sensor" probe to investigate the role of mitochondria in the pathophysiology and diagnosis of cancer. Materials and Methods: We have synthesized a reference compound (4-fluorophenyl)triphenylphosphonium (TPP) and a labeled compound $[^{18}F]$TPP via two step nucleophilic substitution of no-carrier-added $[^{18}F]$fluoride with the precursor, 4-iodophenyltrimethylammonium iodide, in the presence of Kryptofix-2.2.2 and $K_2CO_3$. Result: The reference compound (4-fluorophenyl)triphenylphosphonium (TPP) was synthesized in 60% yield. The radiolabeled compound $[^{18}F]$TPP was synthesized in $10\sim15%$ yield. The radiochemical purity of the $[^{18}F]$TPP was $95.57{\pm}0.51%$ (n=11). Conclusion: $[^{18}F]$TPP was successfully synthesized that might have a potential to be utilized as a novel myocardial or cancer imaging agent for PET. However, it is required to improve the radiochemical yield to apply $[^{18}F]$TPP in preclinical or clinical researches.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.2
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• pp.821-828
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• 2011

This paper developed the algorithm for improving the performance the auto pilot in the autonomous vehicle system consisting of the Track keeping control, the Automatic steering, and the Automatic mooring control. The automatic steering is the control device that could save the voyage distance and cost of fuel by reducing the unnecessary burden of driving due to the continuous artificial navigation, and avoiding the route deviation. During the step of the ship autonomic navigation control, since the wind power or the tidal force could make the ship deviate from the fixed course, the automatic steering calculates the difference between actual sailing line and the set course to keep the ship sailing in the vicinity of intended course. first, we could get the transfer function for the modeling of ship according to the Nomoto model. Considering the maneuverability, we propose it as linear model with only 4 degree of freedoms to present the heading angle response to the input of rudder angle. In this paper, the model of ship is derived from the simplified Nomoto model. Since the proposed model considers the maximum angle and rudder rate of the ship auto pilot and also designs the Fuzzy controller based on existing PID controller, the performance of the steering machine is well improved.

• Journal of the Korean Society of Safety
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• v.11 no.4
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• pp.143-150
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• 1996

This is an explicit-Implicit, finite element analysis for linear as well as nonlinear hygrothermal stress problems. Additional features, such as moisture diffusion equation, crack element and virtual crack extension(VCE ) method for evaluating J-integral are implemented in this program. The Linear Elastic Fracture Mechanics(LEFM) Theory is employed to estimate the crack driving force under the transient condition for and existing crack. Pores in materials are assumed to be saturated with moisture in the liquid form at the room temperature, which may vaporize as the temperature increases. The vaporization effects on the crack driving force are also studied. The Ideal gas equation is employed to estimate the thermodynamic pressure due to vaporization at each time step after solving basic nodal values. A set of field equations governing the time dependent response of porous media are derived from balance laws based on the mixture theory Darcy's law Is assumed for the fluid flow through the porous media. Perzyna's viscoplastic model incorporating the Von-Mises yield criterion are implemented. The Green-Naghdi stress rate is used for the invariant of stress tensor under superposed rigid body motion. Isotropic elements are used for the spatial discretization and an iterative scheme based on the full newton-Raphson method is used for solving the nonlinear governing equations.

• Journal of Korean Society of Steel Construction
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• v.20 no.1
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• pp.151-163
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• 2008

A formulation of three-dimensional model of articulated train-b ridge dynamic interaction has been made for the Korean eXpress Train (KTX). Semi-periodic profiles of rail irregularities consisting of elevation, alignment, cross and gauge irregularities have also been proposed using FRA maximum tolerable rail deviations. The effects of rail joints and sleeper step were also included. The resulting system matrices of train and bridge are very spare, and thus, are stored in one-dimensional arrays, yielding a time-efficient solution. A numerical algorithm for computing bridge-train response including an iterative scheme is also formulated. A program simulating train-bridge interaction and solving this problem using the new algorithm is implemented as new modules for the f inite element analysis software named XFINAS. Computed results using the new program are then checked by that of the validated 2-D bridge-train interaction model. This new 3D analysis provides more detailed train responses such as swaying, bouncing, rolling, pitching and yawing accelerations, which are useful inevaluating passenger riding comfort. Train operation safety and derailment could also be directly investigated by relative wheel displacements computed from this program.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.5
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• pp.691-699
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• 2021

The global surface temperature has risen critically over the past century and according to the IPCC Fifth Assessment Report 2014, existing risks in natural and human systems will worsen. Coastal erosion is mostly caused by climate change and among all the coastal areas at risk, Benin, which is part of the Gulf of Guinea, has been ranked very highly as a vulnerable region. Therefore, in this review, we focus on the evolution of coastline change in Cotonou of Benin, summarizing its resultant impacts and applied measures around the coast area by reviewing previous studies. Signs of coastal erosion in Cotonou appeared in 1963. After 39 years, the east shoreline of Cotonou has retreated by 885 m, resulting in the disappearance of more than 800 houses. To solve this problem, Benin authorities built seven groynes in 2013, and have increased the number of the structure as a way to interrupt water flow and limit the movement of sediment. Over the region, shorelines appeared preserved accordingly. In contrast, areas located further east, where groynes were not installed, have suf ered from intensive erosion at a rate of 49 m/yr. In the future, as a next step, the effectiveness of groynes should be studied with local and broader perspectives.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.18 no.2
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• pp.29-43
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• 2019

The calibration of microscopic traffic simulation models has received much attention in the simulation field. Although no standard has been established for it, a genetic algorithm (GA) has been widely employed in recent literature because of its high efficiency to find solutions in such optimization problems. However, the performance still falls short in simulation analyses to support fast decision making. This paper proposes a new calibration procedure using a dual GA and central composite design (CCD) in order to improve the efficiency. The calibration exercise goes through three major sequential steps: (1) experimental design using CCD for a quadratic response surface model (RSM) estimation, (2) 1st GA procedure using the RSM with CCD to find a near-optimal initial population for a next step, and (3) 2nd GA procedure to find a final solution. The proposed method was applied in calibrating the Gipps car-following model with respect to maximizing the likelihood of a spacing distribution between a lead and following vehicle. In order to evaluate the performance of the proposed method, a conventional calibration approach using a single GA was compared under both simulated and real vehicle trajectory data. It was found that the proposed approach enhances the optimization speed by starting to search from an initial population that is closer to the optimum than that of the other approach. This result implies the proposed approach has benefits for a large-scale traffic network simulation analysis. This method can be extended to other optimization tasks using GA in transportation studies.

• Science of Emotion and Sensibility
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• v.22 no.1
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• pp.45-54
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• 2019

Empathy has been observed to be pivotal in enhancing both social relations and the efficiency of task performance. Empathetic interaction has been shown to begin with individuals mirroring each other's facial expressions, vocal tone, actions, and so on. The internal responses of the cardiovascular activity of people engaged in empathetic interaction are also known to be synchronized. This study attempted to objectively and quantitatively define the rules of empathy with regard to the synchronization of cardiac rhythm between persons. Seventy-four subjects participated in the investigation and were paired to imitate the facial expressions of their partner. An electrocardiogram (ECG) measurement was taken as the participants conducted the task. Quantitative indicators were extracted from the heart rhythm pattern (HRP) and the heart rhythm coherence (HRC) to determine the difference of synchronization of heart rhythms between two individuals as they pertained to empathy. Statistical significance was confirmed by an independent sample t-test. The HRP and HRC correlation(r) between persons increased significantly with empathy in comparison to an interaction that was not empathetic. A difference of the standard deviation of NN intervals (SDNN) and the dominant peak frequency decreased. Therefore, significant parameters to evaluate empathy have been proposed through a step-wise discrimination analysis. Empathic interactions may thus be managed and monitored for high quality social interaction and communication.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.4
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• pp.503-509
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• 2019

The demand for smaller, faster, and multi-functional mobile devices in increasing at a rapidly increasing rate. In response to these trends, Stacked Chip Scale Package (SCSP) is used widely in the assembly industry. A film type adhesive called die attach film (DAF) is used widely for bonding chips in SCSP. The DAF requires high flowability at high die attachment temperatures for bonding chips on organic substrates, where the DAF needs to feel the gap depth, or for bonding the same sized dies, where the DAF needs to penetrate bonding wires. In this study, the mixture design of experiment (DOE) was performed for three raw materials to obtain the optimized DAF recipe for low elastic modulus at high temperature. Three components are acrylic polymer (SG-P3) and two solid epoxy resins (YD011 and YDCN500-1P) with different softening points. According to the DOE results, the elastic modulus at high temperature was influenced greatly by SG-P3. The elastic modulus at $100^{\circ}C$ decreased from 1.0 MPa to 0.2 MPa as the amount of SG-P3 was decreased by 20%. In contrast, the elastic modulus at room temperature was dominated by YD011, an epoxy with a higher softening point. The optimized DAF recipe showed approximately 98.4% pickup performance when a UV dicing tape was used. A DAF crack that occurred in curing was effectively suppressed through optimization of the cure accelerator amount and two-step cure schedule. The imizadole type accelerator showed better performance than the amine type accelerator.

• Journal of Internet Computing and Services
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• v.20 no.5
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• pp.27-36
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• 2019

In this study, experiments on the improvement of the emotion classification, analysis and accuracy of EEG data were proceeded, which applied DEAP (a Database for Emotion Analysis using Physiological signals) dataset. In the experiment, total 32 of EEG channel data measured from 32 of subjects were applied. In pre-processing step, 256Hz sampling tasks of the EEG data were conducted, each wave range of the frequency (Hz); Theta, Slow-alpha, Alpha, Beta and Gamma were then extracted by using Finite Impulse Response Filter. After the extracted data were classified through Time-frequency transform, the data were purified through Independent Component Analysis to delete artifacts. The purified data were converted into CSV file format in order to conduct experiments of Machine learning algorithm and Arousal-Valence plane was used in the criteria of the emotion classification. The emotions were categorized into three-sections; 'Positive', 'Negative' and 'Neutral' meaning the tranquil (neutral) emotional condition. Data of 'Neutral' condition were classified by using Cz(Central zero) channel configured as Reference channel. To enhance the accuracy ratio, the experiment was performed by applying the attributes selected by ASC(Attribute Selected Classifier). In "Arousal" sector, the accuracy of this study's experiments was higher at "32.48%" than Koelstra's results. And the result of ASC showed higher accuracy at "8.13%" compare to the Liu's results in "Valence". In the experiment of Random Forest Classifier adapting ASC to improve accuracy, the higher accuracy rate at "2.68%" was confirmed than Total mean as the criterion compare to the existing researches.

• BMB Reports
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• v.55 no.9
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• pp.453-458
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• 2022

Diabetes mellitus (DM) is a serious disease in which blood sugar levels rise abnormally because of failed insulin production or decreased insulin sensitivity. Although many studies are being conducted for the treatment or early diagnosis of DM, it is not fully understood how mitochondrial genome (mtDNA) abnormalities appear in patients with DM. Here, we induced iPSCs from fibroblasts, PBMCs, or pancreatic cells of three patients with type 2 DM (T2D) and three patients with non-diabetes counterpart. The mtDNA mutations were detected randomly without any tendency among tissues or patients. In T2D patients, 62% (21/34) of iPSC clones harbored multiple mtDNA mutations, of which 37% were homoplasmy at the 100% mutation level compared to only 8% in non-diabetes. We next selected iPSC clones that were a wild type or carried mutations and differentiated into pancreatic cells. Oxygen consumption rates were significantly lower in cells carrying mutant mtDNA. Additionally, the mutant cells exhibited decreased production of insulin and reduced secretion of insulin in response to glucose. Overall, the results suggest that screening mtDNA mutations in iPSCs from patients with T2D is an essential step before pancreatic cell differentiation for disease modeling or autologous cell therapy.