• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.12
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• pp.1184-1191
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• 2009

In order to reduce the download around the Smart UAV(SUAV) at Transition mode, flow control using synthetic jet has been performed. Many of the complex tilt rotor flow features are captured including the leading and trailing edge separation, and the large region of separated flow beneath the wing. Based on the results of part 1 of the present work, synthetic jet is located at 0.01c, $0.95c_{flap}$ and it is operated with the non-dimensional frequency of 0.5, 5 to control the leading edge and trailing edge separation. Consequently, download is substantially reduced compared to with no control case at transition mode using leading edge jet only. The present results show that the overall flight performance and stability of the SUAV can be remarkably improved by applying the active flow control strategy based on synthetic jet.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.12
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• pp.1173-1183
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• 2009

In order to reduce the download around the Smart UAV(SUAV) at hovering, flow control using synthetic jet has been performed. Many of the complex tilt rotor flow features are captured including the leading and trailing edge separation, and the large region of separated flow beneath the wing. In order to control the leading edge and trailing edge separation, synthetic jet is located at 0.01c, $0.3c_{flap}$, $0.95c_{flap}$. As non-dimensional frequency, the flow pattern is altered and the rate of drag reduction is changed. The results show that synthetic jets shorten the vortex period and decrease the vortex size by changing local flow structure. By using leading edge jet and trailing edge jet, download is efficiently reduced compared to no control case at hovering mode.

• Journal of Internet Computing and Services
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• v.6 no.2
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• pp.127-139
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• 2005

This research is in the same line of the research that was carried out in 1999 and 2001, Studies in 1999 and 2001 showed that there are significant differences in the usage levels of Internet in business between countries with longer history of using internet and those with shorter history. The 1999 and 2001 studies also suggested the model on development stages of Internet usage in business, This study is the continuation of the 1999 and 2001 research and used the previous data to compare and analyze the trend of the Internet development stages in leading 100 corporations in Korea, U,S.A., China and Japan in 2002. This study found that there have been significant developments in the ability to use Internet in business in three countries. The differences in Internet usage level in each stage among different countries are compared and analyzed in this study.

• Korean Journal of Materials Research
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• v.18 no.6
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• pp.307-312
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• 2008

In this study, a new cleaning process with a low cost of ownership (CoO) was developed with ozonated DI water ($DIO_3$). An ozone concentration of 40 ppm at room temperature was used to remove organic wax film and particles. Wax residues thicker than $200\;{\AA}$ remained after only a commercial dewaxer treatment. A $DIO_3$ treatment in place of a dewaxer showed a low removal rate on a thick wax layer of $8000\;{\AA}$ due to the diffusion-limited reaction of ozone. A dewaxer was combined with a $DIO_3$ rinse to reduce the wax removal time and remove wax residue completely. Replacing DI rinse with the $DIO_3$ rinse resulted in a surface with a contact angle of less than $5^{\circ}$, which indicates no further cleaning steps would be required. The particle removal efficiency (PRE) was further improved by combining a SC-1 cleaning step with the $DIO_3$ rinsing process. A reduction in the process time was obtained by introducing $DIO_3$ cleaning with a dewaxing process.

• Journal of Science of Art and Design
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• v.2
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• pp.128-160
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• 2000

The objective of this study is to establish a theoretical framework of factors and strategies for success , by probing into design management strategies and the resulting product development details of firms from many parts of the world that improved their images and competitiveness through industrial design. As a means for a company to successfully develop products and to survive, strategies for successful product development were unfolded by many leading businesses of industrial design, whose methods and strategies were respectively unique. International companies such as Philips, Sony, Braun, Ford, and Alessi employed industrial design to not only renew their brand perceptions, but also added values to human life by embedding exclusive designs that customers prefer in their products. They have used design as a business strategic tool, whose elemental processes are, planning, organizing, directing, and controlling. In conclusion, the successful strategies of the leading global companies' design management and product development share the following First, these companies seek design strategies that foresee upcoming changes and are ahead of their time. Second, the CEO is aware of the importance of design, has an appreciative eye for design, and puts in effort into supporting and developing his or her design sector. Third, the director is provided with the conditions in which he or she can take control of one's tasks, and has the abilities and qualities to provide visions for the future. Fourth, the product development team uses original and logical processes and is highly organized. Fifth, the design organization effectively utilizes necessary experts of internal and external company. Sixth, the firm produces innovative products that meet the customers' demand and predict the future. Seventh, the products developed shall employ cutting-edge technologies and are new and original. Eighth, the product must have an identity as a product that represents the company.

• Journal of the Society of Naval Architects of Korea
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• v.48 no.2
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• pp.128-133
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• 2011

In the present study, the flow fields in between the propeller and the semi-spade rudder are investigated by using PIV technique to find out the influences of both simulated hull wake and propeller wake on the incident flow to the rudder. The velocity fields are measured at the propeller rotation angle of $180^{\circ}$ and the rudder deflection angles of $0^{\circ}$. Flow fields measured at each rudder deflection angle are analyzed in terms of angle-of-attack against the rudder leading edge. The hull wake increases the angle-of-attack more than that in the uniform inflow condition, forming the angle-of-attack of about $20^{\circ}$ at 0.7R(R=propeller radius) position. The distribution of the angle-of-attack is strongly affected by the stagnation point around the leading edge and camber effect of the rudder. These effects provide asymmetric distribution of angle-of-attack with respect to the leading edge of the rudder.

• The KSFM Journal of Fluid Machinery
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• v.9 no.1 s.34
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• pp.25-31
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• 2006

The present study investigates the effects of bleed flow on heat/mass transfer and pressure drop in a rotating channel with transverse rib turbulators. The hydraulic diameter $(D_h)$ of the square channel is 40.0mm. The bleed holes are located between the rib turbulators on leading surface and the hole diameter (d) is 4.5 mm. The square rib turbulators are installed on both leading and trailing surfaces. The rib-to-rib pitch is 10.0 times of the rib height(e) and the rib height-to-hydraulic diameter ratio $(e/D_h)$ is 0.055. The tests were conducted at various rotation numbers (0, 0.2, 0.4), while the Reynolds number and the rate of bleed flow to main flow (BR) were fixed at 10,000 and $10\%$, respectively. The results suggest that the heat/mass transfer characteristics in the internal cooling passage are influenced by rib turbulators, bleed flow and the Coriolis force induced by rotation. For the rotating ribbed passage with bleed flow, the heat/mass transfer on the leading surface is hardly affected by bleed flow, but that on the trailing surface decreases due to the diminution of main flow. The results also show that the friction factor decreases with the bleed flow.

• Journal of the Economic Geographical Society of Korea
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• v.13 no.4
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• pp.697-709
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• 2010

The purpose of this paper is to analyze the effects of education and training on labor productivity of the leading firms in Busan during the period of 1999~2000. In order to control for firm heterogeneity and the endogeneity problem of education and training, we employed fixed effects model and 2SLS. Our empirical results showed that firms expenditures per capita on education and training were positively correlated with their labor productivity. We also tested whether the effects of education and training on labor productivity vary with firm size or across industries. It is shown that, while firm size makes no statistical differences, the effect of education and training on labor productivity is smaller in service industry than in manufacturing one. From heterogeneous effect of education and training across industries, we could infer that policies to support various education and training programs in service industry are needed to be reinforced to improve the competitiveness of service industry.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.10
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• pp.898-906
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• 2005

The present study has been conducted to investigate convective heat/mass transfer in the cooling passage with bleed holes. The rotating square channel has 40.0 mm hydraulic diameter and the bleed holes on the leading surface of the channel. The hole diameter of bleed hole is 4.5mm and its spacing is ( p/d:4.9) about five times of hole diameter. Exit mass flow rate through bleed holes is $10\%$ of the main mass flow rate and relation number is changed form 0.0 to 0.4. A naphthalene sublimation technique is employed to determine the detailed local heat transfer coefficients using the heat and mass transfer analogy The cooling performance is influenced by exit mass flow rate through bleed holes and Coriolis force of rotating channel for fixed Reynolds number. The heat transfer on the leading surface is decreased due to Coriolis force. However the total heat transfer is enhanced around holes on the leading surface because of trapping flow by bleeding.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.10
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• pp.907-913
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• 2005

The present study has been conducted to investigate convective heat/mass transfer in the cooling passage with bleed holes. The rotating square channel has 40.0 mm hydraulic diameter and the bleed holes on the leading surface of the channel. The hole diameter of bleed hole is 4.5mm and its spacing is ( p/d:4.9) about five times of hole diameter. Exit mass flow rate through bleed holes is $0\%,\;10\%\;and\;20\%$ of the main mass flow rate respectively. rotation number is fixed 0.2. A naphthalene sublimation technique is employed to determine the detailed local heat transfer coefficients using the heat and mass transfer analogy. The cooling performance is influenced by exit mass flow rate through bleed holes and Coriolis force of rotating channel for fixed Reynolds number. The heat transfer on the leading surface is decreased due to Coriolis force. However the total heat transfer is enhanced around holes on the leading surface because of trapping flow by bleeding.