• Asian Pacific Journal of Cancer Prevention
• /
• v.15 no.16
• /
• pp.6553-6558
• /
• 2014

Background: This study was conducted to gauge how the demographic profile of smokeless tobacco (SLT) users from Gujarat and Andhra Pradesh, India, differs from that of smokers. It also addresses how factors associated with the initiation and continuation of smokeless tobacco vary by age, gender, and education. Materials and Methods: We analyzed 2011 cross-sectional survey data collected from 4,759 respondents (smokers/SLT users/non-users) in both states. Chi-square analysis was used to make comparisons between the demographic profiles of smokers and SLT users. Multivariable logistic regression analysis was used to obtain the odds ratios (ORs) for initiation and continuation factors regressed on socio-demographic variables (age, gender, education). Results: Initiation-women were less likely than men to report "peer pressure", "fashion statement", and "stress/coping" as relevant factors for SLT use (OR: 0.45 CI: 0.30-0.70; OR: 0.42 CI: 0.24-0.74; OR: 2.47, CI: 1.47-4.15). Older age groups had lower odds of choosing "peer pressure" than the 15-24 year olds. Respondents with 11 or more years of education were more likely to report "stress/coping" than those with no education (OR: 2.82, CI: 1.06-7.48). Continuation-women were less likely than men to choose "relaxation", and "distance from family" as important continuation factors (OR: 0.50, CI:0.32-0.80; OR: 0.20, CI: 0.06-0.65). All age groups were less likely to choose "stimulation" as a factor than the youngest group. Conclusions: Along with confirming and expanding upon previous literature, the findings of this study should encourage further SLT research in women and younger age groups (15-24 and 24-44). They also confirm the need for SLT prevention and cessation interventions in India in other community-based settings, besides schools.

• Journal of Power Electronics
• /
• v.18 no.2
• /
• pp.482-491
• /
• 2018

The practical design methodology of a three-phase dual active bridge (3ph-DAB) converter applied to low voltage direct current (LVDC) applications is proposed by using a mathematical model based on the steady-state operation. An analysis of the small-signal model (SSM) is important for the design of a proper controller to improve the stability and dynamics of the converter. The proposed lead-lag controller for the 3ph-DAB converter is designed with a simplified SSM analysis including an equivalent series resistor (ESR) for the output capacitor. The proposed controller can compensate the effects of the ESR zero of the output capacitor in the control-to-output voltage transfer function that can cause high-frequency noises. In addition, the performance of the power converter can be improved by using a controller designed by a SSM analysis without additional cost. The accuracy of the simplified SSM including the ESR zero of the output capacitor is verified by simulation software (PSIM). The design methodology of the 3ph-DAB converter and the performance of the proposed controller are verified by experimental results obtained with a 5-kW prototype 3ph-DAB converter.

• Journal of Institute of Control, Robotics and Systems
• /
• v.15 no.8
• /
• pp.859-866
• /
• 2009

The article discusses an issue of estimating the airspeed of an autonomous flying vehicle. Airspeed is the difference between ground speed and wind speed. It is desirable to know any two among the three speeds for navigation, guidance and control of an autonomous vehicle. For example, ground speed and position are used to guide a vehicle to a target point and wind speed and airspeed are used to maximize flight performance such as a gliding range. However, the target vehicle has not an airspeed sensor but a ground speed sensor (GPS/INS). So airspeed or wind speed has to be estimated. Here, airspeed is to be estimated. A vehicle's dynamics and its dynamic parameters are used to estimate airspeed with attitude and angular speed measurements. Kalman filter is used for the estimation. There are also two major sources arousing a robust estimation problem; wind speed and altitude. Wind speed and direction depend on weather conditions. Altitude changes as a vehicle glides down to the ground. For one reference altitude, multiple model Kalman filters are pre-designed based on several reference airspeeds. We call this group of filters as a cluster. Filters of a cluster are activated simultaneously and probabilities are calculated for each filter. The probability indicates how much a filter matches with measurements. The final airspeed estimate is calculated by summing all estimates multiplied by probabilities. As a vehicle glides down to the ground, other clusters that have been designed based on other reference altitudes are activated. Some numerical simulations verify that the proposed method is effective to estimate airspeed.

• Journal of Agricultural Extension & Community Development
• /
• v.19 no.3
• /
• pp.551-579
• /
• 2012

This case study aims to explore how RDA PLA model affects the agri-SMEs' empowerment. As an agri-business management renovation program from main workshop it was conducted on March to December 2011 with agri-SMEs and extension officials nationwide by RDA. Especially, as a packaged action learning process in the model used participatory action research. This study collected data with participants observation, interviews, situational analysis and systematic review of discourse in qualitative method. For the validity and identifying empirical results, this study used statistic analysis as a mixed method. Further including various pedagogic methods and business coaching skills, this model was conducted from workshop in RDA, in turn, on-farm business coaching as follow-up, CoPs' activities, and local ATCs extension services by each actors. The dynamic process and effects of each process led some change for farmers' innovative knowledge, skills, attitude, practice and aspiration on their farm business. RDA PLA model development based on the previous practices and research, which provided a configurated picture in the holistic action learning process. In statistic research, this study focused on 279 farmers as respondents who had participated in the program. It shows that their income and benefits increased from their renovative practices on farm business. Following the sampling group, it was surveyed by four indicators - products, customer, quality and cost. The level of contribution of education on economic impact 15% is quoted from previous paper. Even in some limitations of public sector, RDA PLA model actively suggests the paradigm shift of agricultural HRD and development of alternative extension-service system.

• Wind and Structures
• /
• v.17 no.6
• /
• pp.647-670
• /
• 2013

The paper presents a numerical approach to study of fluid flow characteristics and to predict performance of wind turbines. The numerical model is based on Finite-volume method (FVM) discretization of unsteady Reynolds-averaged Navier-Stokes (URANS) equations. The movement of turbine blades is modeled using moving mesh technique. The turbulence is modeled using commonly used turbulence models: Renormalization Group (RNG) k-${\varepsilon}$ turbulence model and the standard k-${\varepsilon}$ and k-${\omega}$ turbulence models. The model is validated with the experimental data over a large range of tip-speed to wind ratio (TSR) and blade pitch angles. In order to demonstrate the use of numerical method as a tool for designing wind turbines, two dimensional (2-D) and three-dimensional (3-D) simulations are carried out to study the flow through a small scale Darrieus type H-rotor Vertical Axis Wind Turbine (VAWT). The flows predictions are used to determine the performance of the turbine. The turbine consists of 3-symmetrical NACA0022 blades. A number of simulations are performed for a range of approaching angles and wind speeds. This numerical study highlights the concerns with the self-starting capabilities of the present VAWT turbine. However results also indicate that self-starting capabilities of the turbine can be increased when the mounted angle of attack of the blades is increased. The 2-D simulations using the presented model can successfully be used at preliminary stage of turbine design to compare performance of the turbine for different design and operating parameters, whereas 3-D studies are preferred for the final design.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.35 no.9
• /
• pp.923-932
• /
• 2011

Because of the instability of a flow pattern in the inlet transition square duct (hereinafter referred to as "transition duct") of a heat recovery steam generator (hereinafter referred to as "HRSG") in a combined cycle power plant, the Reynolds number in the first row of a tube bank is differs sharply from that in the sectional area of the transition duct. This causes differences in the heat flux in each tube in the tube bank. The computational fluid dynamics (CFD) predictions provide three-dimensional results for velocity, temperature, and other flow parameters over the entire domain of the duct and HRSG. A renormalization group theory (RNG) based k-${\epsilon}$�� turbulent model is used for obtaining the results cited in this study. A porous media option is used for modeling the tube banks and the number of transfer units method is used for determining the heat transfer characteristics. This study describes a comparison between the numerical simulation results and actual design output.

• Journal of Korean Neurosurgical Society
• /
• v.29 no.12
• /
• pp.1634-1641
• /
• 2000

Objective : The cerebrospinal fluid(CSF) pulsates within the craniospinal axis in response to rhythmic cerebral blood volume variation during the cardiac cycle. The aim of this study is to characterize the normal and abnormal CSF flow and its waveforms in the cervical spinal subarachnoid space. Methods : The magnetic resonance(MR) images were obtained with 1.5 T(GE Signa, GE Medical Systems, Milwaukee, USA) unit using the 2 dimensional cine PC(phase contrast) sequence with cardiac gating and gradient recalled echo imaging. This pulse sequence yielded 16 quantitative flow-encoded images per cardiac cycle. Sagittal and axial images of the cervical spinal CSF space were obtained, and target sites were analyzed for characteristic CSF flow (TR=50ms, TE=12.5-15ms). The region of interest(ROI) was 1mm 3 in volume. Twenty six persons were included in this study : 10 healthy volunteers and 16 patients with cervical myelopathy. The post-operative cine MR study were also done in five patients. Results : The normal CSF pulsation dynamics in the cervical spine showed discrete systolic and diastolic components. The CSF flow revealed a sine wave pattern, in which the systolic phase was shorter than the diastolic phase(ratio=2 : 3). The patient group revealed decreased amplitudes of the CSF flow and irregularly distored flow waves. The systolic phase was elongated in the ROI above the stenotic level, whereas the diastolic phase was lengthened below the level. In the postoperative images, the abnormal pattern and amplitude were found to be corrected. Conclusion : From these results, the authors believe that the CSF flow study provides valuable informations regarding the extent of cervical stenosis and may be useful for the surgical planning and post-operative evaluation.

• Journal of the Korean Society for Marine Environment & Energy
• /
• v.12 no.1
• /
• pp.9-14
• /
• 2009

A numerical investigation was performed based on the Reynolds-Averaged Navier-Stokes(RANS) equations for the two-dimensional unsteady flow around a vertical axis turbine(VAT) with three or four blades. VAT is one of the promising devices for tidal current energy conversion. The geometry of the turbine blade was $NACA65_3$-018 airfoil, for which CFD analysis using Fluent was carried out at several angles of attack and the results were compared with the corresponding experimental data for validation and calibration. Then CFD simulations were carried out for the whole vertical axis turbine with a two-dimensional setup. The CFD simulation demonstrated the usefulness of the method to study the typical unsteady flows around VATs and the results showed that the optimum turbine efficiency could be achieved for carefully selected combinations of the number of blade and Tip-Speed Ratio(TSR).

• Proceedings of the KSRS Conference
• /
• 2007.10a
• /
• pp.29-32
• /
• 2007

Tidal channel development is influenced by sediment type, grain size, composition and tidal current. Tidal channels are usually characterized by channel development, density and shape. Quantitative analysis of tidal channels using remotely sensed data have rarely been studied. The objective of this study is to quantify tidal channels in terms of fractal dimension and compare different inter-tidal channel patterns. For the fractal analysis, we used Box counting method which had been successfully applied to streams, coastlines and others linear features. For a study, the southern part of Ganghwado tidal flats was selected where is famous for high dynamics of tidal currents and vast tidal flats. This area has different widths and lengths of tidal channels. IKONOS and Komsat-2 MSC images were used for extracting tidal channels, and the Box counting method was applied to obtain fractal dimensions (D) for each tidal channel. Yeochari area possesses channels with linear pattern and less dense development and accordingly show low D values ranging from 1.037 to 1.038. On other hands, area (near Donggumdo and Yeongjongdo ) of dendrites channel pattern and dense development resulted in high D values from 1.2057 to 1.2667. Also, area possesses channels with linear pattern had low density about $18{\sim}24%$. Area of dendritic channel pattern had high density about $34{\sim}69%$. The difference of fractal dimensions about 0.2 according to channel development in tidal flats is relatively large enough to use as an index for tidal channel classification. Also, area where channels showed linear pattern had low density about $18{\sim}24%$. Area of dendritic channel pattern had high density about $34{\sim}69%$. Using fractal dimension and density, it would be possible to quantify the tidal channel development in association with surface characteristics.

• Fire Science and Engineering
• /
• v.23 no.1
• /
• pp.48-54
• /
• 2009

The present study has been performed to investigate the effect of statistical number of droplets on the simulation of the sprinkler spray using fire field model. In order to simulate the sprinkler spray characteristics, the present study uses NIST Fire Dynamics Simulator version 5.2. A group of Lagrangian particles with similar droplet characteristics, such as diameter, velocity, temperature and so on, is represented by parcel concept to decrease the total number of droplets tracked in the simulation. The present study introduces a new parameter to represent the ratio between real number of droplets and computational parcels. The dependency of the number of parcels on the fire suppression characteristics and spray patterns is quantitatively examined for different ratio between the real number of droplets and computational parcels.