• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.11
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• pp.7934-7940
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• 2015

The raise of the acceleration can be one of possible methods to increase the scheduled speed of the metropolitan railway system. It is possible to raise the acceleration to the some point by increasing the traction power of the motor. However, there is a limit of the acceleration because the traction power over some level related to the adhesion causes a slip, which prevents from accomplishing the target acceleration. The running resistance is also an important factor to consider. Both the adhesion and the running resistance as well as the traction power vary according to the velocity. Therefore, the standardization of the acceleration needs the analysis of these factors as a function of velocity. In this study, we focus on the advanced urban transit unit(AUTS) for the standardization. We derive a novel equation of the adhesion suitable for the AUTS by investigation of the traction and adhesion equation as well as the experiment data. And finally we propose the standard of the acceleration based on this analysis.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.5
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• pp.26-35
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• 2016

As a potential clean energy resource, the production and consumption of hydrogen gas are expected to gradually increase, so that hydrogen related studies are also increasing. The thermal and chemical properties of hydrogen result in its high flammability; in particular, there is a high risk if leaks occur within an enclosed space. In this study, we applied the computational fluid dynamics method to conduct a numerical study on the leakage behavior of hydrogen gas and compared these numerical study results with an experimental study. The leakage hole diameter was selected as an important parameter and the hydrogen gas dispersion behavior in an enclosed space was investigated through various analytical methods. Moreover, the flammable regions were investigated as a function of the leakage time and leakage hole size. We found that the growth rate of the flammable region increases rapidly with increasing leakage hole size. We also investigated the relation between the mass flow rate and the critical time when the hydrogen gas reaches the ceiling. The analysis of the monitoring points showed that the hydrogen gas dispersion behavior is isotropic and independent of the geometry. We found that the concentration of gas in an enclosed space is affected by both the leakage flow rate and amount of gas accumulated in the enclosure.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.10
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• pp.1277-1286
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• 2018

In this paper, we provide flexible scalability of computing resources in cloud environment and Apache Hadoop based cloud environment for analysis of public medical information big data. In fact, it includes the ability to quickly and flexibly extend storage, memory, and other resources in a situation where log data accumulates or grows over time. In addition, when real-time analysis of accumulated unstructured log data is required, the system adopts Hadoop-based analysis module to overcome the processing limit of existing analysis tools. Therefore, it provides a function to perform parallel distributed processing of a large amount of log data quickly and reliably. Perform frequency analysis and chi-square test for big data analysis. In addition, multivariate logistic regression analysis of significance level 0.05 and multivariate logistic regression analysis of meaningful variables (p<0.05) were performed. Multivariate logistic regression analysis was performed for each model 3.

• The Korean Journal of Nuclear Medicine
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• v.21 no.2
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• pp.143-150
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• 1987

To assess the analytic performance of immunoradiometric TSH assay (IRMA TSH), assay precision determined by intra and interassay variance, assay accuracy determined by dilution and recovery study, were evaluated by using two commercial kit $(Abott^{(R)}\;and\;Daichi^{(R)})$. Normal range of basal serum TSH and TRH stimulated TSH increment were also determined in 234 healthy subjects (male 110, female 124; age 20-70) and 30 voluteers (male 10, female 20; age 21-26). In addition, basal TSH levels of 70 patients with untreated hyperthyroidism, 50 untreated hypothyroidism, and 60 euthyroidism were measured to assess the clinical utility of IRMA TSH. The detection limit of IRMA TSH was 0.04 mU/l and 0.08 mU/l by Abott Kit and Daichi kit respectively. Using Abott kit, intra assay variance were 2.0, 3.1 and 1.4% in mean TSH concentration 2.4, 31.6 and 98.2 mU/l repectively and interassay variance were 2.0 and 3.2% in mean TSH concentration 2.3 and 31.3 mU/l. Mean recovery rate was 92.5% and dilution study showed nearly straight line. When Daichi kit was used, intrasssay variance were 5.6, 5.2 and 6.2% in mean TSH concentration of 2.4, 31.6 and 98.2 mU/l respectively and interassay variance were 7.1 and 7.4% in mean TSH of 2.3 and 31.3 mU/l. Mean recoveray rate was 89.9%. Normal range of basal TSH and TRH stimulated peak TSH were 0.38-4.02 mU/l and 2.85-30.8 mU/l repectively (95% confidence interval, Abott kit used). Sensitivity and specificity of basal TSH levels for diagnosing hypothyroidism as well as specificity for diagnosing hyperthyroidism were 100% by using both kit. Sensitivity of basal TSH level for diagnosing hyperthyroidism was 100% when TSH levels were measured by Abott kit while that was 80.9% when measured by Daichi kit. These results suggest that IRMA TSH was very precise and accurate method and might be used as a first line test in the evaluation of thyroid function.

• Nutrition Research and Practice
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• v.10 no.1
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• pp.56-66
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• 2016

BACKGROUND/OBJECTIVES: Despite successes recorded in combating iodine deficiency, more than 2 billion people are still at risk of iodine deficiency disorders. Rural landlocked and mountainous areas of developing countries are the hardest hit, hence the need to explore and advance novel strategies such as biofortification. SUBJECTS/METHODS: We evaluated adoption, purchase, and consumption of iodine biofortified vegetable legumes (IBVL) using the theory of protection motivations (PMT) integrated with an economic valuation technique. A total of 1,200 participants from three land-locked locations in East Africa were recruited via multi-stage cluster sampling, and data were collected using two, slightly distinct, questionnaires incorporating PMT constructs. The survey also elicited preferences for iodine biofortified foods when offered at a premium or discount. Determinants of protection motivations and preferences for iodine biofortified foods were assessed using path analysis modelling and two-limit Tobit regression, respectively. RESULTS: Knowledge of iodine, iodine-health link, salt iodization, and biofortification was very low, albeit lower at the household level. Iodine and biofortification were not recognized as nutrient and novel approaches, respectively. On the other hand, severity, fear, occupation, knowledge, iodine status, household composition, and self-efficacy predicted the intention to consume biofortified foods at the household level; only vulnerability, self-efficacy, and location were the most crucial elements at the school level. In addition, results demonstrated a positive willingness-to-pay a premium or acceptance of a lesser discount for biofortification. Furthermore, preference towards iodine biofortified foods was a function of protection motivations, severity, vulnerability, fear, response efficacy, response cost, knowledge, iodine status, gender, age. and household head. CONCLUSIONS: Results lend support for prevention of iodine deficiency in unprotected populations through biofortification; however 'threat' appraisal and socio-economic predictors are decisive in designing nutrition interventions and stimulating uptake of biofortification. In principle, the contribution is threefold: 1) Successful application of the integrated model to guide policy formulation; 2) Offer guidance to stakeholders to identify and tap niche markets; 3) stimulation of rural economic growth around school feeding programmes.

• Journal of Convergence for Information Technology
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• v.9 no.12
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• pp.141-146
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• 2019

Economic analysis predicts that the drone market will grow, and the growth of the toy and hobby drone market is expected to gradually expand. Drone expectations are rising due to the net economic function of drone market growth, but accidents due to improper management and operations are also increasing. The difference in toy drone performance is incomparably small compared to industrial drone performance, but the ordinary buyer can not know whether the difference can cause an accident during use. The toy drones used in this study were obtained from KC and CE certification, and 20 kinds of drones were used. The flight time ranged from a minimum of 3 minutes to a maximum of 12 minutes, and the control distance ranged from a minimum of 20m to a maximum of 380m. Therefore, it is necessary to secure product safety through sampling inspection of the radio wave output of toy drones, and it is also necessary to mount an algorithm that automatically lowers the altitude or hover when exceeding the limit flight distance. For future research, we will build data to establish toy drone safety standards through a altitude testing and impact testing of toy drone.

• The Korean journal of internal medicine
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• v.33 no.6
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• pp.1093-1102
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• 2018

Background/Aims: The aim of this study was to investigate parameters that predict radiation-induced liver disease (RILD) following stereotactic body radiotherapy (SBRT) in patients with hepatocellular carcinoma (HCC) and to identify the clinical significance of RILD. Methods: We retrospectively reviewed the medical records of 117 HCC patients who were treated by SBRT from March 2011 to February 2015. RILD was defined as elevated liver transaminases more than five times the upper normal limit or a worsening of Child-Pugh (CP) score by 2 within 3 months after SBRT. All patients were assessed at 1 month and every 3 months after SBRT. Results: Median follow-up was 22.5 months (range, 3 to 56) after SBRT. RILD was developed in 29 of the 117 patients (24.7%). On univariate analysis, significant predictive factors of RILD were pretreatment CP score (p < 0.001) and normal liver volume (p = 0.002). Multivariate analysis showed that CP score was a significant predictor of RILD (p < 0.001). The incidence of RILD increased above a CP score of 6 remarkably. The rate of recovery from RILD decreased significantly above a CP score of 8. Survival analysis showed that CP score was an independent prognostic factor of overall survival (p = 0.001). Conclusions: CP score is a significant factor to predict RILD in patients with chronic liver disease. RILD can be tolerated by patients with a CP score ${\leq}7$. However, careful monitoring of liver function is needed for patients with a CP score 7 after SBRT.

• Journal of Environmental Impact Assessment
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• v.28 no.3
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• pp.245-262
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• 2019

The objectives of this study were to construct a three-dimensional water quality model (EFDC) for the river reach between Chilgok Weir and Gangjeong-Goryong Weir (GGW) located in Nakdong River, and evaluate the effect of hydraulic changes, such as water level and flow velocity, on the control of water quality and algae biomass. After calibration, the model accurately simulated the temporal changes of the upper and lower water temperatures that collected every 10 minutes, and appropriately reproduced changes in organic matter, nitrogen, phosphorus, and cyanobacteria. However, the simulated values were overestimated for the diatoms and green algae cell density, possibly due to the uncertainties of the parameters associated with algae metabolism and the lack of zooplankton predation function in the simulations. As a result of scenario simulation of running the water level of GGW from EL. 19.44 m to EL. 14.90 m (4.54 m drop), Chl-a and algae cell density decreased significantly.In particular,the cyanobacteria on the surface layer, which causes algal bloom, declined by 56.1% in the low water level scenario compared to the existing management level. The results of this study are in agreement with the previous studies that maintenance of critical flow velocity is effective for controlling cyanobacteria, and imply that hydraulic control such as decrease of water level and residence time in GGW is an alternative to limit the overgrowth of algae.

• Tunnel and Underground Space
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• v.29 no.3
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• pp.172-183
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• 2019

The generalized Hoek-Brown (GHB) failure criterion developed by Hoek et al. (2002) is a nonlinear function which defines a stress condition at failure of rock mass. The relevant strength parameter values are systematically determined using the GSI value. Since GSI index is a value quantifying the condition of in-situ rock mass, the GHB criterion is a practical failure condition which can take into the consideration of in-situ rock mass quality. Considering that most rock mechanics engineers are familiar with the linear Mohr-Coulomb criterion and that many rock engineering softwares incorporate Mohr-Coulomb criterion, the equations for the equivalent friction angle and cohesion were also proposed along with the release of the GHB criterion. The proposed equations, however, fix the lower limit of the minor principal stress range, where the linear best-fitting is performed, with the tensile strength of the rock mass. Therefore, if the tensile stress is not expected in the domain of analysis, the calculated equivalent friction angle and cohesion based on the equations in Hoek et al. (2002) could be less accurate. In order to overcome this disadvantage of the existing equations for equivalent friction angle and cohesion, this study proposes the analytical formula which can calculate optimal equivalent friction angle and cohesion in any minor principal stress interval, and verified the accuracy of the derived formula.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.29 no.2
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• pp.28-38
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• 2011

Dwelling reflects the continuance and change that, in general, expresses the era's cultural and social values. The yard of Korean traditional dwelling, although it is an exterior space, it is a companion space that is engaged with the main house. It operates many housing functions that were not achieved within the interior space. After the time of enlightenment, shape, function and the meaning of Korean traditional house yard along with the change of values and major living style has been changing. Therefore, to understand how the Chosun Dynasty's house yard is being used in modern days, this study is based on the research of 47 sites and conducted a study regarding the acculturation and division the house yards. Typical elements in the target garden site that are expressed in a way differentiated from the original form of the Korean traditional house yard were the materials and methods of planting, the use of garden ornaments, paving materials, the use of water, and changes in kitchen gardens. As the role of house yards changes, the modern division of the style of gardens occurred; the areas in a garden have been divided and the form of a garden has been differentiated according to the limit and initiative. The pursuit of ornamentality and practicality led to the differentiation of gardens' functions, while seeking after convenience resulted in the division of gardens' materials. The use of gardens has also been differentiated by adding commerciality and a concept of open garden in both symbolic and daily manners.