• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.05a
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• pp.151-152
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• 2010

• Journal of ILASS-Korea
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• v.20 no.3
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• pp.181-186
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• 2015

This study presents the dynamic wetting characteristics of an impact droplet on hole-patterned textured surfaces. The flat surfaces were manufactured by a drilling machine to generate the micro-order holes, leading to make the surface hydrophobic. Other flat surfaces were fabricated by the anodizing technique to make hydrophilic texture surfaces with a nanometer order. For hydrophilic and hydrophobic textured surfaces with similar texture area fractions, the impinging droplet experiments were conducted and compared with flat surface cases. As results, an anodized textured surface decreases apparent equilibrium contact angle and increases contact diameters, because of increase in contact area and surface energy. This is attributed to more penetration inside holes from larger capillary pressure on nanometer-order holes. On the other hand, temporal evolution of the contact diameter is smaller for the hydrophobic textured surface from less penetration on the micro-order holes.

• Journal of Mechanical Science and Technology
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• v.18 no.10
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• pp.1849-1858
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• 2004

For examining friction-factor characteristics of round-hole pattern surfaces which are usually applied on damper seals, flat plate test apparatus is designed and fabricated. The measurement method of leakage and pressure distribution along round-hole pattern specimen with different hole area is described and a method for determining the Fanning friction factor is discussed. Results show that the round-hole pattern surfaces provide a much larger friction factor than smooth surface, and the friction factor vs. clearance behavior yields that the friction factor generally decreases as the clearance increases unlike the results of Nava's flat plate test. As the hole depth is decreased, the friction factor is increased, and maximum friction factor is obtained for 50% of hole area. Since the present experimental friction factor results show coincident characteristics with Moody's friction factor model, empirical friction factors for round-hole pattern surfaces are obtained by using the Moody's formula based on curve-fit of the experimental data. Results of Villasmil's 2D CFD simulation support the present experimental test result.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.2
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• pp.1-6
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• 2012

Recent ultra-precision machining systems have nano-scale resolution, and can machine various shapes of complex structures using five-axis driven modules. These systems are also multi-functional, which can perform various processes such as planing, milling, turning et al. in one system. Micro machining technology using these systems is being developed for machining fine patterns, hybrid patterns and high aspect-ratio patterns on large-area molds with high productivity. These technology is and will be applied continuously to the fields of optics, display, energy, bio, communications and et al. Domestic and foreign trends of micro machining technologies for flat molds were investigated in this study. Especially, we focused on the types and the characteristics of ultra-precision machining systems and application fields of micro patterns machined by the machining system.

• Journal of the Korean Institute of Rural Architecture
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• v.20 no.2
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• pp.11-18
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• 2018

The purpose of this study is to analyze the structure and use change of the private space according to the balcony expansion and use it as the data of plan design. According to Bay, front length/width ratio and the change of balcony space before and after expansion of space organization of house units were analyzed. Common characteristics of Flat type and Tower type are an increase of the frontage length of house units in an apartment, an increase of the number of front bay, and an increase of integrated LDK focusing on living room. A difference is that Flat type shows high frontage ratio, Bay figure, and spatial arrangement favorable to front openness and lighting. Flat type shows higher area distribution than Tower type in LDK area distribution located in at the plane center. Spatial expandability and visual openness of Flat type are more beneficial than those of Tower type in the planning, and a balcony extension of house units has developed to direction to open more. Tower type creates various block images through a combination of house units focusing on the core. Uses after balcony expansion are area expansion of a balcony-neighboring room, storage space, expansion and function improvement of the variable range, and specialized space different from a neighboring room. In addition, there is no escapable space except for a shelter, so unit plan should be prepared to prevent using it other space of a shelter and to solve moving line of two-way horizontal refuge and vertical refuge.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1506-1511
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• 2003

The present study proposes a new structure for a flat plate heat pipe which could embody a thin thickness, any shapes and high heat density a unit area. It is on the structure for the formation of vapor passages and the support of the case of the flat plate heat pipe. A screen mesh is used as the one. To verify the validity of the one, the flat plate heat pipe of 1.08mm thickness was made with a layer of the screen mesh with 14 and 100 mesh number respectively and tested. Here the screen mesh with 14 mesh number plays a role of the vapor passage and the support of the case and the screen mesh with 100 mesh number functions as the wick structure. T he results show that the screen mesh excellently carries out the function of the vapor passage and the support of the case.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.130.2-130.2
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• 2011

The application of solar energy in residential building is general and natural in today. And application methods of solar thermal energy is divided in two kind of form, single evacuated tube and flat-plate form. Then in this study, the efficiency of single evacuated tube and flat-plate system is compared by total and effective area considering the time receiving the solar radiation between 24 hours and the specific time(10:00~15:00). As a result of the experiment, single evacuated tube and flat-plate collector's efficiency is varied by the quantity of solar radiation. And especially, the flat-plate system is more affected by outdoor temperature. Therefore the application of solar thermal system should be considered the solar radiation and outdoor temperature.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.11
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• pp.67-72
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• 2011

Recently, photovoltaic generator system is widely extended by energy policy of the government. Add to this, for high efficiency of power generation per natural light unit area is needed to sun tracking system. And it is needed to condensed light generator for reducer of equipment expense. As method of solving this problem, this paper is developed multi-flat reflector sun tracking system for sun photocell maximum power generation. The system is consisted of multi-flat reflector and two axes machinery and sun location perceiver and AVR controller. GaAs 3J cell generated 6.75 times power more than silicon cell by times condensing light system. As a result, condensing light system of multi-flat reflector generated maximum power and showed reducing costs to photovoltaic generator.

• Wind and Structures
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• v.17 no.5
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• pp.537-552
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• 2013

Wind tunnel experiments were performed to study the wind loads on an inclined flat plate with and without a guide plate. Highly turbulent flow, which corresponded to free-stream turbulence intensity on the flat roof of low-rise buildings, was produced by a turbulence generation grid at the inlet of the test section. The test model could represent a typical solar collector panel of a solar water heater. There are up-stream movements of the separation bubble and side-edge vortices, more intense fluctuating pressure and a higher bending moment in the turbulent flow. A guide plate would result in higher lift coefficient, particularly with an increased projected area ratio of a guide plate to an inclined flat plate. The value of lift coefficient is considerably lower with increased free-stream turbulent intensity.

• Journal of Ocean Engineering and Technology
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• v.24 no.3
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• pp.72-78
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• 2010

This paper presents a design approach of driving system for tidal flat vehicle. Firstly, topographic and geological survey of tidal flat zone was accomplished. 'Anac' located in the west-south coast of South Korea was chosen for the survey area. From the survey, the basic design data such as distribution of gullies size and bearing pressure was obtained. To figure out the shape of driving system, numerical simulations were carried out. Through the numerical dynamic simulations using $Recurdyn^{TM}$, the performance of various concepts of driving system was analyzed. From the results, we propose the conceptual design with the functions: a) low contact pressure, b) powerful driving force transmission, c) adaptation to the ground undulation. To satisfy these functional requirements, the driving system adopts rubber tracks, sprockets, tires and suspensions. The static structural analysis of the frame structure was executed as well, from which the detailed design was drawn out. To validate the performance of the designed driving system, the test vehicle which has gasoline engine of 27HP and mechanical transmission was constructed. The driving tests of the vehicle were performed twice at the "Anac" area, and unveiled its capability.