• Magazine of the Korean Society of Agricultural Engineers
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• v.45 no.4
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• pp.98-106
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• 2003

In order to set up structural improvement strategy against meteorological disasters of the shading structures in ginseng fields, structural safety analyses as well as some case studies of structural damage patterns were carried out. According to the results of structural safety analysis, allowable safe snow depth for type B(wood frame with single span) was 25.9 cm, and those for type A(wood frame with multi span) and type C and D (steel frame with multi span) were 17.6 cm, 25.8 cm, and 20.0 cm respectively. So types of shading structures should be selected according to the regional design snow depth. An experiential example study on meteorological disasters indicated that a strong wind damage was experienced once every 20 years, and a heavy snow damage once every 9.5 years. The most serious disasters were caused by heavy snow and it was found that a half break and complete collapse of structures were experienced by about 70% of snow damage. In addition to maintenance, repair and reinforcement, it is also recommended that improved model of shading structures for ginseng cultivation should be developed as a long term countermeasures against meteorological disasters.

• 한국신재생에너지학회:학술대회논문집
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• 2007.11a
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• pp.564-568
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• 2007

Gas hydrate has been attractive topic for two dedicates because it may cause the global warming, ocean hazards associated with the instability of marine slope due to the gas hydrate release as well as high potential of future energy resources. The study on gas hydrate in Ulleung basin has been performed since 1999 to explore the potential and distribution of gas hydrate offshore Korea. The numerous multi channel seismic data have been acquired and processed by Korea Institute of Geosciences and Mineral Resources (KIGAM). The results showed clearly the gas hydrate indicators such as pull up structure, bottom simulating reflector (BSR), seismic blanking zone. The prestack depth migration has been considered as fast and accurate technique to image the subsurface. In this paper, we will present both the conventional seismic data processing and apply Kirchhoff prestack depth migration for gas hydrate data set. The results will be applied for core sample collections and for proposal more detail 2D with long offset or 3D seismic exploration.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.6
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• pp.39-44
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• 2019

The evaporator is a key driver of an air conditioning system's efficiency. In this study, we study methods of maximizing the efficiency of a Massey Ferguson (MF) evaporator by measuring how the cooling performance of different shapes vary with temperature. We varied the tube insertion depth as well as the shape of the evaporator's header and tube. When we compare header shapes of "D", "Ellipse", and "Quadrangle" types, we find that the elliptical header creates the smallest pressure loss and the highest temperature difference. Between tube shapes of "Rectangular", "Projection", and "Circular" types, the "Projection" type tube creates the most temperature difference. We also investigated the depth of tube insertion in the header and find that tube insertion of 5 - 10 mm is feasible; we selected the depths of 5, 7, and 10 mm since they corresponded to approximately 30%, 50%, and 70% of the total width of the header. The tube insertion test demonstrated that a tube insertion depth of 7 mm creates the least pressure loss and the highest temperature difference. In conclusion, the optimal evaporator design uses an "Ellipse" type header, "Projection" type tube, and a tube insertion depth between 30 and 50% of the header width.

• Journal of the Korean Geotechnical Society
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• v.24 no.8
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• pp.43-52
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• 2008

In this study, the verification test and creep test for both a single-rebar nail and a multi-rebar nail are carried out to investigate a tensile strength for both nails. The adhesion effects between a rebar and a cement grout, a mobilized frictional force induced by pull-out load, and load transfer characteristics are examined. The results obtained from the field pull-out tests and from the numerical analysis using $FLAC^{2D}$ which is one of the programs developed based on the finite difference method are analyzed and compared for a single-rebar nail and a multi-rebar nail. The field pull-out test results for a multi-rebar nail relative to a single-rebar nail show that a tensile failure load is relatively large and the pull-out loads are well transferred to the ground in deep depth.

• Journal of the Semiconductor & Display Technology
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• v.6 no.3
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• pp.65-70
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• 2007

A method to focus the object in camera system by applying the Hill climb algorithm from optical lens moving device (VCM; Voice coil motor) is proposed. The focusing algorithm from VCM is focus on the object but in these criteria is a well-known drawback; the focus is good only at same distance objects but the focus is bad (blur image) at different distance objects because of the DOF (Depth of focus) or DOF (Depth of field) at the optical characteristic. Here, the new camera system that describes the Reflector of free curvature systems (or Diffractive Fresnel lens) and the partition of focusing window area is proposed. The method to improve the focus in all areas (different distance objects) is proposed by new optical system (discrete auto in-focus) using the Reflector of free curvature systems (or Diffractive Fresnel lens) and by applying the partition of all areas. The proposal is able to obtain good focus in all areas.

• ETRI Journal
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• v.34 no.3
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• pp.466-469
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• 2012

In this letter, we propose a dual autostereoscopic display platform employing a natural interaction method, which will be useful for sharing visual data with users. To provide 3D visualization of a model to users who collaborate with each other, a beamsplitter is used with a pair of autostereoscopic displays, providing a visual illusion of a floating 3D image. To interact with the virtual object, we track the user's hands with a depth camera. The gesture recognition technique we use operates without any initialization process, such as specific poses or gestures, and supports several commands to control virtual objects by gesture recognition. Experiment results show that our system performs well in visualizing 3D models in real-time and handling them under unconstrained conditions, such as complicated backgrounds or a user wearing short sleeves.

• Journal of Ship and Ocean Technology
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• v.7 no.2
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• pp.1-19
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• 2003

This paper introduces a unified theory for the radiation problem of adjacent multiple floating bodies. The particular case of interest is the multiple slender bodies that their centerlines are parallel. The infinite-and finite-depth unified theories for the single-body problem are extended to solve each sub-problem of multiple bodies. The present method is valid for deep water and moderate water depth, and applicable for individually floating bodies as well as multimaran-type vehicles. For the validation of the present method, the heave and pitch hydrodynamic coefficients for two adjacent ships are compared with the results of a three-dimensional method, and an excellent agreement is shown. The application includes the hydrodynamic coefficients and motion RAOs of four trimarans which have different longitudinal and transverse arrangements for sidehulls.

• Transactions on Electrical and Electronic Materials
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• v.4 no.5
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• pp.10-14
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• 2003

A low-cost, large area, random, maskless texturing scheme independent of crystal orientation is expected to have significant impact on terrestrial photovoltaic technology. We investigated silicon surface microstructures formed by reactive ion etching (R IE) in Multi-Hollow cathode system. Desirable texturing effect has been achieved when radio-frequency (rf) power of about 20 Watt per one hollow cathode glow is applied for our RF Multi -Hollow cathode system. The black silicon etched surface shows almost zero reflectance in the visible region as well as in near IR region. The etched silicon surface is covered by columnar microstructures with diameters from 50 to 100 nm and depth of about 500 nm. We have successfully achieved 11.7 % efficiency of mono-crystalline silicon solar cell and 10.2 % for multi-crystalline silicon solar cell.

• Korean journal of communication and information
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• v.45
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• pp.255-295
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• 2009

The purpose of this study was to investigate how much multi-cultural traits the multiculture-oriented TV programs would have and how they tended to represent it with what kinds of meaning structures. As an object of this study, the authors chose the Program of KBS-TV which had been discussed seriously to raise a multi-cultural issue as well as a sexuality issue of lady guests. They collected 70 weekly programs from Nov. 26 of 2006 to March 31, 2008, and finally selected and analyzed 5 weekly programs as main analytic data. They tried to analyze them with various semiotic research methods, especially, linguistic semiotic research methods and pictorial research methods. As results of this study, it was found that this Program was based on multiful-levels of meaning structure: that is, superficial level, representation level and in-depth level. The superficial level of this program presented various multi-cultural traits through many and various talks of lady guests. Its representation level indicated some patterns of discourses about issues and agendas of the talks among lady guests. The in-depth level was based on the sexuality of lady guests as well as the male-dominant ideology. It was finally implicated that this Program was based on the sexuality and feminity of lady guests even though it tried to advocate its multi-cultural traits.

• Journal of Fisheries and Marine Sciences Education
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• v.27 no.5
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• pp.1310-1317
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• 2015

Two-phase flow boiling heat transfer in micro-channels was experimently investigated. The test section consisted of 15 rectangular micro-channels with a depth of 0.45mm, width of 0.20mm. The experiments were performed for heat fluxes ranging from 5.6 to 46.1kW/m2 and mass fluxes from 150 to 450kg/m2s using FC-72 as the working fluid. According to the results, at the low heat flux region, heat transfer coefficient strongly depends on the heat flux, while heat transfer coefficient at the high heat flux region was independent on the heat flux. Four correlations were used to predict the heat transfer coefficient. The measured heat transfer coefficient was compared with four correlations. It was found that Kaew-On and Wongwises's correlation well predicted the measured data, within the MAE of 40.3%.