• Journal of Mechanical Science and Technology
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• v.16 no.9
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• pp.1121-1136
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• 2002

The flow characteristics of film coolant issuing into turbulent boundary layer developing on a convex surface have been investigated by means of flow visualization and three-dimensional velocity measurement. The Schlieren optical system with a spark light source was adopted to visualize the jet trajectory injected at 35° and 90° inclination angles. A five-hole directional pressure probe was used to measure three-dimensional mean velocity components at the injection angle of 35°. Flow visualization shows that at the 90° injection, the jet flow is greatly changed near the jet exit due to strong interaction with the crossflow. On the other hand, the balance between radial pressure gradient and centrifugal force plays an important role to govern the jet flow at the 35° injection. The velocity measurement shows that at a velocity ratio of 0.5, the curvature stabilizes downstream flow, which results in weakening of the bound vortex structure. However, the injectant flow is separated from the convex wall gradually, and the bound vortex maintains its structure far downstream at a velocity ratio of 1.98 with two pairs of counter rotating vortices.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.2
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• pp.93-98
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• 2008

To investigate the characteristics of water droplet on the gas diffusion layer from both top-view and side-view of the flow channel, a rig test apparatus was designed and fabricated with prism attached plate. This experimental device is used to simulate the growth of single liquid water droplet and its transport process with various air flow velocity and channel height. The contact angle hysteresis and height of water droplet are measured and analyzed. It is found that droplet tends towards to be instable by decreasing channel height, increasing flow velocity or making GDL more hydrophobic. Also, the simplified force balance model matches with experimental data only in a restricted range of operating conditions and shows discrepancy as the air flow velocity and channel height increases.

• Asian review of World Histories
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• v.2 no.2
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• pp.147-167
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• 2014

The urban modernity that became an irresistible model for elites in Asia in the decades before and after 1900 was far from being gender-neutral. It represented an exceptional peak of patriarchy in its exclusion of respectable middle class women from the work force, from ownership and control of property and from politics. Marriage was indissoluble and the wife's role in the male-headed nuclear family was to care for and educate the abundant children she produced. Puritan religious values underlined the perils for women of falling outside this pattern of dependence on the male. Though upheld as modern and civilized, this ideal was in particularly striking contrast with the pre-colonial Southeast Asian pattern of economic autonomy and balance between women and men, and the relative ease of female-initiated divorce. Although attractive to many western-educated Southeast Asian men, including religious reformers determined to 'save' and domesticate women, urban respectability of this type was a poor fit for women accustomed to dominant roles in commerce and marketing, and at least equal ones in production. Southeast Asian relative failure in the high colonial era to adapt to the modern market economy may also have a gendered explanation. We should not be surprised that patriarchy and puritanism became more important in Southeast Asia as it urbanized in the late 20th Century, since this was echoing the European experience a century earlier. The question remains how far Southeast Asia could retain its relatively balanced gender pattern in face of its eventual rapid urbanization and commercial development.

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.599-601
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• 2001

This paper investigates the permanent magnet (PM) overhang effect on the characteristics such as cogging torque and torque in brushless DC motor (BLDCM). The overhang effect has been used to enlarge the performance of the radial flux density in BLDCM and balance the force in the axial direction for the reduction of the vibration. 3D equivalent magnetic circuit network method (3D EMCNM) is used for the accurate and efficient analysis. The characteristics of BLDCM are analyzed according to the variation of overhang length and the optimal length and ratio of overhang is determined.

• Tribology and Lubricants
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• v.9 no.1
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• pp.62-69
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• 1993

Friction and wear behavior of a carbon/carbon composite material for aircraft brake material was experimentally investigated. Friction and wear test setup was designed and built for the experiment. Friction and wear tests were conducted under various sliding conditions. Friction coefficients were measured and processed by a data acquisition system and amount of wear measured by a balance. Stainless steel disk was used as the counterface material. Temperature was also measured by inserting thermocouple 2.5 mm beneath the sliding surface of the carbon/carbon composite specimen. Wear surfaces were observed by SEM, and analyzed by EDAX. The experimental results showed that sliding speed and normal force did not have significant effects on friction coefficient and wear factor of the composite. Temperature increase just below the surface was not large enough to cause any thermal degradation or oxidation which occurred at higher temperature when tested by TGA. Wear film was generated both on the specimen and on the counterface at relatively low sliding speed but cracks, grooves, and wear debris were observed at high sliding speed. Friction coefficient remained almost constant when the sliding speed or normal load was varied. It is believed that the adhesive and abrasive components contributed mainly to the friction coefficient. Wear behavior at low sliding speed was governed by wear film formation and adhesive wear mechanism. At high speed, fiber orientation, ploughing by counterface asperities, and fiber breakage dominated wear of the carbon/carbon composite.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.347-352
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• 2009

Pneumatic system is widely applied to ground facility and launcher on-board system. The main requirements of pneumatic system is to meet pressure and flow requirements of gas consumers. For launcher related applications, different from other applications, very high flow is required which can leads to supply pressure drop against required setting pressure. The supply pressure decrease is closely related to regulator characteristics. In this paper, the characteristics of pneumatic regulator related to supply pressure decrease and the control methods for reducing the pressure offset are reviewed.

• The Bulletin of The Korean Astronomical Society
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• v.39 no.2
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• pp.74.2-74.2
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• 2014

Magnetohydrodynamics(MHD) dynamo depends on many factors such as viscosity ${\gamma}$, magnetic diffusivity ${\eta}$, magnetic Reynolds number $Re_M$, external driving source, or magnetic Prandtl number $Pr_M$. $Pr_M$, the ratio of ${\gamma}$ to ${\eta}$ (for example, galaxy ${\sim}10^{14}$), plays an important role in small scale dynamo. With the high PrM, conductivity effect becomes very important in small scale regime between the viscous scale ($k_{\gamma}{\sim}Re^{3/4}k_fk_f$:forcing scale) and resistivity scale ($k_{\eta}{\sim}PrM^{1/2}k_{\gamma}$). Since ${\eta}$ is very small, the balance of local energy transport due to the advection term and nonlocal energy transfer decides the magnetic energy spectra. Beyond the viscous scale, the stretched magnetic field (magnetic tension in Lorentz force) transfers the magnetic energy, which is originally from the kinetic energy, back to the kinetic eddies leading to the extension of the viscous scale. This repeated process eventually decides the energy spectrum of the coupled momentum and magnetic induction equation. However, the evolving profile does not follow Kolmogorov's -3/5 law. The spectra of EV (${\sim}k^{-4}$) and EM (${\sim}k^0$ or $k^{-1}$) in high $Pr_M$ have been reported, but our recent simulation results show a little different scaling law ($E_V{\sim}k^{-3}-k^{-4}$, $EM{\sim}k^{-1/2}-k^{-1}$). We show the results and explain the reason.

• Journal of the Korean Home Economics Association
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• v.49 no.6
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• pp.23-37
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• 2011

This research tried to identify how different types of environments related with work-family reconciliation effects the amount of resource exchange between working mothers and their child. In this study, we applied theoretical concepts such as 'Defamiliarization'(rights of mothers to access the work force without any environmental obstacles) and 'Familiarization'(a movement trying to balance work with family and child). This study is an analysis of valid questionnaires filled out by 220 female respondent's who was holding a job and also had children attending elementary, middle, or high school at the time answering the survey questionnaire. Results of this survey are as follows. Mother's attitudes toward familiarization and child's school environments related with defamiliarization had critical effects on mother's perceived resource exchange. And in a further analysis, among the clustered groups of mothers the group which consists of mothers who try to work hardly on both work and family had the highest degree of the resource supplies to their child.

• Journal of Korea Game Society
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• v.5 no.3
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• pp.25-30
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• 2005

Until now, the level design for games has played a very important role in the process of developing games since it has been mapped out and applied so the game players have fun to certain level in playing games. So as game becomes more complex the number of game designers also grow and to make diverse levels, work force and working hours also should grow larger. In this treatise, it suggest a way where level's structure is changing dynamically so with only one level you can experience diverse levels by introducing wandering agent to the level structure. Also, I am trying to show the possibility of balance between the players by wandering agent.

• Journal of Korean Society of Forest Science
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• v.76 no.3
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• pp.275-294
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• 1987

In the United States, forest administration is a constantly changing complex of policies, programs, and management regulations. Forest administration is the product of a brief but tumultuous history during which much of the forests which once covered half the land were coutover for farms, industry, and cities. In the last 15 years, forest administration has been increasingly dominated by concerns for maintaining an ecological balance. Current forest administration is deeply rooted in the American traditions of decentralized federalism and free enterprise, yet combines state socialism and private capitalism. The major elements of U.S. forest administration consist of : 1) programs and policies on taxation, professional education and research, and "cooperative forestry", 2) state controls on forest practices for privately owned lands, and of federal policies and regulations for the management of federal lands. The federal Forest Service has played a lead role in developing and implementing national forest policies and programs. Since the end of World War II, the national forests managed by the Forest Service for multiple use have provided and ever growing fraction of domestic timber needs. In the coming decades, cultural and social trends may force a change in management policy on federal land, reducing the importance of timber harvesting in relation to amenity values.