• Korea-Australia Rheology Journal
• /
• v.20 no.3
• /
• pp.117-125
• /
• 2008

Viscoelastic instabilities are of fundamental importance to understanding the physics of complex fluids and of practical importance to materials processing and fluid characterization. Significant progress has been made over the past 15 years in understanding instabilities in viscoelastic flows with curved streamlines and is reviewed here. Taylor-Couette flow, torsional flow between a cone and plate, and torsional flow between parallel plates have received special attention due to both the basic significance of these flows and their critical role in rheometry. First, we review the criteria for determining when these flows become unstable due to elasticity in the absence of inertia, and discuss the generalization of these criteria to more complex flows with curved streamlines. Then, focusing on experiments and simulations in the Taylor-Couette problem, we review how thermal sensitivity (i.e., the dependence of fluid viscosity and elasticity on temperature) and inertia affect the stability of viscoelastic flows. Finally, we conclude with some general thoughts on unresolved issues and remaining challenges related to viscoelastic instabilities.

• Journal of Information Science Theory and Practice
• /
• v.2 no.3
• /
• pp.18-28
• /
• 2014

Reddit is a large user generated content (USG) website in which users form common interest groups and submit links to external content or text posts of user-created content. The web site operates on a voting system whereby registered users can assign positive or negative ratings to both submitted content and comments made to submitted content. While Reddit is a pseudonymous site, with users creating usernames but providing no biographical data, an informal survey posted to a large shared interest community yielded 734 responses including age and gender of users. This provided a large amount of contextual biographical data with which to analyse user profiles at the first level of Computer Mediated Discourse Analysis (CMDA), articulated by Susan Herring. The results indicate that older Reddit users both formulate more complex writing and enjoy more success when rated by other users. Gender data was incomplete and as such only tentative results could be proposed in that regard.

• 한국지구물리탐사학회:학술대회논문집
• /
• 2007.06a
• /
• pp.231-236
• /
• 2007

Electrical resistivity, self-potential and time-domain induced polarization methods were conducted for study of electrical responses on vein-type sulfides ore, which is intruding limestone and dolomite of Ordovician, of Geumpung mine located in Dojeon-ri, Susan-myeon, Jecheon-si, Chungbuk. Sulfides bearing chalcopyrite, pyrrhotite and galena etc. are deposited in disseminated or vein-type. Good result that resistivity and self-potential surveys detect high grade-estimated mineralized zone located in upper part of existing low grade ore zone is acquisited and is to some extent consistent with induced polarization. Furthmore, a new mineralization zone directing EW is detected.

• Hwankyungkyoyuk
• /
• v.23 no.1
• /
• pp.87-98
• /
• 2010

This study examined college students' environmental knowledge, attitudes as well as their behaviors in Busan. Among four areas (biodiversity, carbon cycle, ozone, and global warming) of environmental knowledge, students represented the most understanding on global warming, and the least understanding on biodiversity. In regards to environmental attitude, students represented the lowest scores in reality of limits to growth, and the highest scores in antianthropocentrism. With respect to environmental-friendly behavior, less than 30% of students responded that they always tried to use less paper towels. In addition, only 24% of students responded that they always recycle e-waste. These college students did not represent gender difference in environmental knowledge, attitude as well as behavior. Moreover, there was a strong relationship between environmental knowledge and attitude, while no relationship between environmental knowledge and behavior as well as between environmental attitude and behavior.

• International Journal of Fluid Machinery and Systems
• /
• v.4 no.1
• /
• pp.104-113
• /
• 2011

The paper presents a new method for the analysis of the cavitation behaviour of hydraulic turbomachines. This new method allows determining the coefficient of the cavitation inception and the cavitation sensitivity of the turbomachines. We apply this method to study the cavitation behaviour of a large storage pump. By plotting in semi-logarithmic coordinates the vapour volume versus the cavitation coefficient, we show that all numerical data collapse in an exponential manner. By analysis of the slope of the curve describing the evolution of the vapour volume against the cavitation coefficient we determine the cavitation sensitivity of the pump for each operating point.

• International Journal of Fluid Machinery and Systems
• /
• v.4 no.1
• /
• pp.47-56
• /
• 2011

Our previous experimental and numerical investigations of decelerated swirling flows in conical diffusers have demonstrated that water jet injection along the symmetry axis mitigates the pressure fluctuations associated with the precessing vortex rope. However, for swirling flows similar to Francis turbines operated at partial discharge, the jet becomes effective when the jet discharge is larger than 10% from the turbine discharge, leading to large volumetric losses when the jet is supplied from upstream the runner. As a result, we introduce the flow-feedback approach for supplying the jet by using a fraction of the discharge collected downstream the conical diffuser. Experimental investigations on mitigating the pressure fluctuations generated by the precessing vortex rope and investigations of pressure recovery coefficient on the cone wall with and without flow-feedback method are presented.

• Journal of Korea Port Economic Association
• /
• v.19 no.2
• /
• pp.69-85
• /
• 2003

The current legislation of the Port Authority which empowers the central government to control finance, personnel management, business of the Port Authority should be amended to allow the Port Authority to exercise its authority over port management and operation by gaining authority from the central government. In addition, to enhance Busan port's competitiveness and for a successive activation of the Susan Port Authority, it is necessary for the BPA to develop its new business and for the Busan Metropolitan City to establish both the department of Port Logistics and relevant regulations. The central government should also support and cooperate with the BPA rather than controlling the Authority.

• Journal of Korea Port Economic Association
• /
• v.19 no.2
• /
• pp.141-158
• /
• 2003

There are several Customs Free Zone in Korea. Those are Susan Port, Kwangyang Port, Inchun Port. and International Airport Inchun. And there are several zone which will be appointed soon, Busan Port area, Kwangyang Port area, Inchun Port and International Airport Inchun area. But there are many problems to operate CFZ in Korea. This paper aim at pointing out for the problems and drawing up the plan. The problems are an unreasonable incentive standard, security of the behind site related to CFZ, present customs law not to process and assemble, and several similar system related CFZ. Globalization and regionalization are major trends in the international economic system recently. So we have to make desperate efforts to win the severe competition among many countries in economic aspect and make a good plan to solve the problems related CFZ in future.

• Journal of the Korean Chemical Society
• /
• v.57 no.1
• /
• pp.63-72
• /
• 2013

Some vanadyl complexes were synthesized by treating a methanolic solution of the appropriate Schiff base ligand and one equivalent of $VO(SO_4)_2$ to yield [($VOL_2^{1-14}$)](L=Salicylaldehyde's derivatives, Schemes 1, 2). These oxovanadium (IV) complexes were characterized based on their FT-IR, UV-Vis spectroscopy and elemental analysis. The IR spectra suggest that coordination takes place through azomethine nitrogen and phenolate oxygen. In addition, the formation constants of the oxovanadium (IV) binary complexes were determined in methanolic medium. The ab initio calculations were also carried out to determine the structural and the geometrical properties of one of the complexes and its calculated vibrational frequencies were investigated.

• Safety and Health at Work
• /
• v.7 no.1
• /
• pp.83-85
• /
• 2016

Effective interventions to reduce work-related exposures are available for many types of work-related diseases or injuries. However, knowledge of the impact of these interventions on injury or disease outcomes is scarce due to practical and methodological reasons. Study designs are considered for the evaluation of occupational health interventions on occupational disease or injury. Latency and frequency of occurrence of the health outcomes are two important features when designing an evaluation study with occupational disease or occupational injury as an outcome measure. Controlled evaluation studies-giving strong indications for an intervention effect-seem more suitable for more frequently occurring injuries or diseases. Uncontrolled evaluation time or case series studies are an option for evaluating less frequently occurring injuries or diseases. Interrupted time series offer alternatives to experimental randomized controlled trials to give an insight into the effectiveness of preventive actions in the work setting to decision and policy makers.