• Journal of the Korea Society for Simulation
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• v.20 no.2
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• pp.29-40
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• 2011

This paper focuses on the sensitivity analysis for the calibration of an agent-based simulation that analyzes the brand-level diffusion dynamics of competing products in the domestic premium mid-sized car market. In this paper, we employ a consumer-agent model that imitates the purchasing characteristics and behaviors of the consumers. The group of consumer agents that are socially interconnected represents a virtual market. By spreading the product information from previous adopters to potential consumer agents in the virtual market, the word-of-mouth phenomenon emerges like in the real market. The phenomenon influences the product choice of potential consumer agents that causes the variation of the product diffusion dynamics. In this simulation model, it is important to calibrate the virtual market parameters(e.g., ratio of innovators, social network structure, purchase time decision method) so that the virtual market can simulate the real market. However, it is difficult to measure these parameters directly from the real market. In this paper, we analyze the diffusion dynamics of simulations under various conditions in comparison with real sales data to calibrate the parameters.

• The Journal of the Convergence on Culture Technology
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• v.7 no.4
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• pp.759-764
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• 2021

Because sensitive and private information should be exchanged between electric vehicles and a V2G service provider, reliable communication channel is essential to operate Vehicle-to-Grid (V2G) system which considers battery of electric vehicles as a factor of smart grid. The block chain is a platform for cryptocurrency transaction and fully distributed database system running by only equivalent node in the network without help of any central management or 3^rd party. In this paper, the structure and operation method of the blockchain are investigated, and the application of the blockchain for the V2G system was also explained and analyzed.

• Journal of Biomedical Engineering Research
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• v.43 no.5
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• pp.331-340
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• 2022

Early afterdepolarization (EAD), a significant cause of fatal ventricular arrhythmias including Torsade de Pointes (TdP) in long QT syndromes, is a depolarizing afterpotential at the plateau or repolarization phase in action potential (AP) profile early before completing one pace. AP duration prolongation is related to EAD but is not necessarily accounted for EAD. Several computational studies suggested EAD can form from an abnormality in the late plateau and/or repolarization phase of AP shape. In this sense, we hypothesized the slope during repolarization has the characteristics to predict TdP risk, mainly focusing on the maximum slope during repolarization (dVm/dt_{max_repol}). This study aimed to predict the sensitivity of dVm/dt_{max_repol} to ion channel conductances as a TdP risk metric through a population simulation considering multiple effects of simultaneous reduction in six ion channel conductances of g_NaL, g_Kr, g_Ks, g_to, g_K1, and g_CaL. Additionally, we verified the availability of dVm/dt_{max_repol} for TdP risk prediction through the correlation analysis with qNet, the representative TdP metric. We performed the population simulations based on the methodology of Gemmel et al. using the human ventricular myocyte model of Dutta et al. Among the sixion channel conductances, dVm/dt_{max_repol} and qNet responded most sensitively to the change in g_Kr, followed by g_NaL. Furthermore, dVm/dt_{max_repol} showed a statistically significant high negative correlation with qNet. The dVm/dt_{max_repol} values were significantly different according to three TdP risk levels of high, intermediate, and low by qNet (p<0.001). In conclusion, we suggested dVm/dt_{max_repol} as a new biomarker metric for TdP risk assessment.

• Journal of Soil and Groundwater Environment
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• v.22 no.1
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• pp.49-58
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• 2017

Biotic ligand model (BLM) and species sensitivity distribution (SSD) were used to determine the site-specific Cu threshold concentration (5% hazardous concentration; HC5) in soil pore water. Model parameters for Cu-BLM were collected for six plants, one collembola, and two earthworms from published literatures. Half maximal effective concentration ($EC_{50}\{Cu^{2+}\}$), expressed as $Cu^{2+}$ activity, was calculated based on activities of major cations and the collected Cu-BLM parameters. The $EC_{50}\{Cu^{2+}\}$ varied from 2 nM to $251{\mu}M$ according to the variation in environmental factors of soil pore water (pH, major cation/anion concentrations) and the type of species. Hazardous activity for 5% (HA5) and HC5 calculated from SSD varied from 0.076 to $0.4{\mu}g/L$ and 0.4 to $83.4{\mu}g/L$, respectively. HA5 and HC5 significantly decreased with the increase in pH in the region with pH less than 7 due to the decrease in competition with $H^+$ and $Cu^{2+}$. In the region with pH more than 7, HC5 increased with the increase in pH due to the formation of complexes of Cu with inorganic ligands. In the presence of dissolved organic carbon (DOC), Cu and DOC form a complex, which decreases $Cu^{2+}$ activity in soil pore water, resulting in up to 292-fold increase in HC5 from 0.48 to $140{\mu}g/L$.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.43 no.3
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• pp.205-210
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• 2010

Dynamic modeling was used to predict the Pseudomonas spp. concentration in Alaska pollack under dynamic temperature conditions in a programmable incubator using Euler's method. The model evaluation showed good agreement between the predicted and measured concentrations of Pseudomonas spp. In the simulation, three kinds of distribution path were assumed: consumers buying from a distribution center (A), manufacturer (B), or direct market (C). Each of these distribution paths consists of six phases: shipping, warehousing/shipment, warehousing/storing, processing, market exhibition, and sale/consumption. Sensitivity analysis of each phase was also implemented. The Pseudomonas concentrations and sensitivities ($S_k$) at the terminal phases of the three paths were estimated to be (A) 11.174 log CFU/g and 10.550 log $S_k$, (B) 10.948 log CFU/g and 10.738 log $S_k$, and (C) 8.758 log CFU/g and 9.602 log $S_k$, respectively. The sensitivities indicated that path A has the highest risk of failure in managing the relevant phases.

• Tuberculosis and Respiratory Diseases
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• v.59 no.6
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• pp.651-655
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• 2005

Background : Diagnosing a pulmonary embolism is difficult because its presenting symptoms are nonspecific and there are limitations with all of the objective tests. The D-dimer is known to be a marker of the lysis of intravascular cross-linked fibrin as a result of the activation of the endogenous fibrinolytic pathways, and the D-dimer assay is these an objective method for diagnosing a pulmonary embolism. This study assessed the benefits of the D-dimer test for diagnosing a pulmonary embolism using semiquantitative latex agglutination. Methods : The latex agglutination results of 185 patients were retrospectively reviewed. The D-dimer test was performed at the time a pulmonary embolism was suspected. Ninety patients(group I) were diagnosis with PE through spiral chest CT or a chest CT angiogram, perfusion/ventilation scans, and/or pulmonary angiogram. Ninety-five patients (group II) were found not to have a pulmonary embolism through the above tests. Results : The male to female ratio and mean age in groups I and II was 37:55, and 57 years old to 50:45 and 52 years old, respectively. When the cut off value for a positive D-dimer assay was set to $500{\mu}g$, the sensitivity, positive predictive value, negative predictive value and specificity was 86.7%, 61.4%, 79.3%, and 48.4%, respectively. Conclusion : The semiquantitative latex agglutination method in the D-dimer test has a lower sensitivity and negative predictive value than the well known ELISA test particularly for small emboli. Therefore, this test is not a suitable screening test for excluding a pulmonary embolism.

• Information and Communications Magazine
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• v.32 no.9
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• pp.24-30
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• 2015

새로운 서비스의 실현을 목표로 하는 차세대5G이동통신에 대한 비전, 요구사항 및 주요 요소 기술들에 대한 연구가 다양하게 진행 중이다. 지연 시간에 민감한 새로운 저지연 서비스의 지원을 위해 5G 이동통신 비전의 핵심 성능 지표 중 하나로 무선구간에서 1ms 이내의 사용자 데이터 전송이 제시되었다. 본고에서는 ITU-R WP 5D의 5G 이동통신 비전 권고 내용들과 권고 내용을 직접적인 반영하는 5G 관련 기술 개발 단계는 아니지만 3GPP 에서 현재 진행 중인 Release-13 표준화 활동 중에서 사용자 데이터 전송에 있어서 지연 감소를 목표로 논의되는 후보 기술들을 살펴보고 이를 바탕으로 3GPP에서의 관련 표준화 동향을 정리한다.

• Journal of the Korea Concrete Institute
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• v.26 no.3
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• pp.277-285
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• 2014

The purpose of this study is to investigate experimentally the variation factors range having influence on the rheological properties of the combined self-compacting concrete according to materials quality, weighting error and site conditions. Two types cement (blast-furnace slag cement and belite cement), lime stone powder as binder and the optimum mix proportions in the preceded study are selected for this study. Also, variations for sensitivity test are as followings; (1) Concrete temperature 3 cases (2) Surface moisture of sand 5cases (3) Fineness modulus of sand 5cases (4) Specific surface of lime stone powder 3cases (5) Dosage of chemical admixture 5cases. Slump flow ($650{\pm}50mm$), 500 mm reaching time (($7{\pm}3sec$), V-type flowing time ($15{\pm}5sec$) and U-box height (min. 300 mm) are tested for sensitivity. As test results, the variations range for quality control are as followings. (1) Concrete temperature; $10{\sim}20^{\circ}C$(below $30^{\circ}C$) (2) Surface moisture of sand; $base{\pm}0.6%$ (3) Fineness modulus of sand; $2.6{\pm}0.2$ (4) Dosage of chemical admixture; $base{\pm}0.2%$ (5) Specific surface of lime stone powder $6000cm^2/g$. Compared with two types cement including based belite cement (binary type) and based slag cement (ternary type), the combined self-compacting concrete used belite cement type is most stable in the quality control because of high contents for lime stone powder and $C_2S$. It is to propose a control scheme of the combined self-compacting concrete in the actual construction work.

• Korean Chemical Engineering Research
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• v.49 no.1
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• pp.105-108
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• 2011

The increased concern for the security of the oil supply and the negative impact of fossil fuels on the environment, particularly greenhouse gas emissions, has put pressure on society to find renewable fuel alternatives. Compared to the traditional biofuel, ethanol, higher alcohols offer advantage as gasoline substitutes because of their higher energy density and lower hygroscopicity. For this reason, microbial fermentation is known as potential producers for sustainable energy carriers. In this study, bacterial responses including cellular and molecular toxicity were studied in three different microorganisms, such as Escherichia coli, Clostridium acetobutylicum, and Saccharomyces cerevisiae. In this study, it was analyzed specific stress responses caused by ethanol and buthanol using four different stress responsive genes, i.e. fabA, grpE, katG and recA. The expression levels of these genes were quantified by semi-quantitative reverse transcription-PCR. It was found that four genes have shown different responsive patterns when E. coli cultures were under stressful conditions caused by ethanol and buthanol, respectively. Therefore, in this study, the stress responsive effects caused by these alcohols and the extent of each stress response can be analyzed using the expression levels and patterns of different stress responsive genes.

• The Journal of the Korea Contents Association
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• v.15 no.5
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• pp.375-385
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• 2015

The study is to develop specific strategies to prevent adolescents' depression, early detection and intervention services. This study was a descriptive research study with the purpose of predictors of protective factors for depression in adolescent using decision making tree analysis. The subjects for the study were 485 student in G city. This study collected data between September 23, 2013 and September 26, 2013 and analyzed them with frequency analysis, percentage, the mean and standard deviation, ${\chi}^2$-test, t-test, and a decision-making tree by using SPSS 20.0 program. From the data analysis, the predictive model for protective factors related to depression in adolescent with 4 pathways, 12 nodes. The common predicting variables of depression in adolescent were characteristics, family cohesion, parent adolescent communication, peer communication. The specialty of training data and test data was 76.0% and 65.4%. The sensitivity of training data was 78.2% and 63.7%. As for the classification accuracy, training data and test data explained 70.1% and 69.7%. Parent adolescent communication and peer communication to decrease depression of Korean middle and high school students are necessary. This study should contribute as baseline data for intervention strategies and planning ability of depression prevention in adolescents.