• 한국신재생에너지학회:학술대회논문집
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• 2008.10a
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• pp.131-133
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• 2008

A serious problem of the 21st century is the supply of energy resources. Reserves of fossil fuels are facing depletion: renewable energy resources must be developed in this era. Dye sensitized solar cell (DSC) has been very economical and easy method to convert solar energy to electricity. Recently a novel tandem cell structure is proposed to improve photocurrent of DSC. To fabricated a tandem cell, the mesh structure of counter electrode is essential for the improvement in transmittance. In this study, we conducted the experiment to get the characteristic of DSC with mesh counter electrode. Under the standard test condition (AM 1.5, 100mW/$cm^2$), we obtained the maximum efficiency of 3.41% and the transmittance of 72% in the DSC with mesh counter electrode.

• Communications for Statistical Applications and Methods
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• v.10 no.2
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• pp.457-469
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• 2003

In this paper, we have proposed the efficient algorithm that can segment the video scene change using a various statistical characteristics obtained from by applying the wavelet transformation for each frames. Our method firstly extracts the histogram features from low frequency subband of wavelet-transformed image and then uses these features to detect the abrupt scene change. Second, it extracts the edge information from applying the mesh method to the high frequency subband of transformed image. We quantify the extracted edge information as the values of variance characteristic of each pixel and use these values to detect the gradual scene change. And we have also proposed an algorithm how extract the proper key frame from segmented video scene. Experiment results show that the proposed method is both very efficient algorithm in segmenting video frames and also is to become the appropriate key frame extraction method.

• Journal of the Korean Graphic Arts Communication Society
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• v.31 no.1
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• pp.1-14
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• 2013

Screen printing is a printing method with flexible plate surface characteristics. In addition, since the appearance of electronics industry the screen printing has been demanding high quality and definition. However, Screen printing is a method for taking ink through mesh opening because screen mesh tends to restrict quality of screen printing. In particular, the biggest problem compared with other printing type is halftone reproduction characteristics. Halftone reproduction characteristics for screen printing depend on screen mesh and opening. Dot losses or dot gains are observed through various types of screen mesh because thread of screen mesh interfere with the movement of the ink. Excessive dot losses or gains can affect the tonal range. Furthermore, this problem can result in other problem such as bad contrast and gray balance. Therefore, it is an important factor to use proper screen mesh for halftone screen printing. However, domestic screen printing industry relies on worker's experience in field rather than depending on objective data although standardized specifications and optimal printing conditions are required for screen printing. For this reason, it is important to stipulate standard condition for domestic screen printing industry. Therefore, it was examined to find tonal range by mesh opening in halftone prints process of screen printing used domestic paper and ink in this study. In addition, TVI(Tone Value Increase) characteristic was observed by comparing to the manuscripts and prints of the dot area ratio. Furthermore, contrast value and gray balance were confirmed for each condition of the printout. Conditions for the proper selection of screen mesh screen for the quality of the prints were also examined, compared with the international standard of screen printing, ISO 12647-5.

• The Journal of the Korea Contents Association
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• v.15 no.10
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• pp.10-17
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• 2015

Transparent LED display is providing city residents with different attractions via information services and landscape and increasing demand is detected in various areas. It is true that majority of the current demand in transparent electrode material was found and used in ITO but limitations in capacity and economic efficiency led to the need for continuous research and technology development via new materials. As a new material, metal mesh has 85% of the materials to substitute ITO and is widely used due to low-cost and high-conductive rate. Maintenance of transparent LED display utilizing metal mesh compared to existing ITO transparent display is much easier as it not only saves resources but is also economical. Thus the objective of this paper lies in proposing the utilization of metal mesh in transparent LED display prototype to enable economical use of transparent LED display technology and to expand the market and to also propose transparent LED display development method via metal mesh and manufacture a prototype based on the method. And a characteristic comparison test between ITO and metal mesh provides the possibility of using metal mesh as a transparent electrode material in transparent LED display development.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.15 no.1
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• pp.33-42
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• 2002

A method of automatic 3D tunnel modeling is proposed. The proposed method used the parametric representation of geometry and a hierarchical and relational data structure. These two bases provide the generalization and extension for 3D tunnel modeling. Especially, these two fundamentals ion the basis iota representing the characteristics of the tunnel structure for analysis. The constant-curvature characteristic is exploited to generate 3D mesh on the tunnel surface. This is attributed to the advantage that any 2D automatic mesh generation algorithm can be applied to 3D mesh modeling.

• 한국전산유체공학회:학술대회논문집
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• 2003.08a
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• pp.194-199
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• 2003

The studying is to analyze characteristic of air flow and is used to design in an automotive HVAC module. The RNG k-e turbulence model with the Upwind Difference convection scheme and an unstructured hybrid mesh with arbitrary matching method were applied to the simulation. The comparing air flow characteristic of the basic HVAC module and total HVAC module with blower were discussed in the paper.

• Journal of Korea Multimedia Society
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• v.10 no.12
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• pp.1632-1644
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• 2007

Wireless Mesh Networks aim to attain large connectivity with minimum performance degradation, as network size is increase. As such, scalability is one of the main characteristics of Wireless Mesh Networks that differentiates it from other wireless networks. This characteristic creates the need for bandwidth efficiency strategies to ensure that network performance does not degrade as the size of the network increase. Several researches have been done to realize mesh networks. However, the researches conducted were mostly focused on a per TCP/IP layer basis. Also, the studies on bandwidth efficiency and bandwidth improvement are usually dealt with as separate issues. This paper aims to simultaneously study bandwidth efficiency and improvement. Aside from optimizing the bandwidth given a fixed capacity, the capacity is also increased using results of physical layer studies. In this paper, the capacity is improved by using the concept of non-overlapping channels for wireless communication. A channel allocation scheme is conceptualized to choose the transmission channel that would optimize the network performance parameters with consideration of chosen Quality of Service (QoS) parameters. Network utility maximization is used to optimize the bandwidth after channel selection. Furthermore, a routing scheme is proposed using the results of the network utilization method and the channel allocation scheme to find the optimal path that would maximize the network gain.

• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.459-462
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• 2006

In this study, the characteristic of a vane pump of an automative power steering system is numerically analyzed. The vane pump changes the energy level of operation fluid by converting mechanical input power to hydraulic output. To simulate this mechanism, moving mesh technique is adopted. As a result, the flow rate and pressure are obtained by numerical analysis. The flow rate agrees well with the experimental data. Moreover, the variation and oscillation of the pressure around the rotating vane are confirmed. The difference of pressure appears in the vane tip as a result of the flow characteristics. Furthermore, the back flow into the rotor was observed.

• 한국전산유체공학회:학술대회논문집
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• 2007.04a
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• pp.41-44
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• 2007

A large eddy simulation method with unstructured mesh is presented. Two explicit filtering procedures are adopted for reducing the aliasing error of the nonlinear convective term and measuring the level of subgrid scale velocity fluctuation, respectively. The developed subgrid scale model is basically an eddy viscosity model which depends on both local velocity fluctuation level and local grid scale. As a validation problem, the flows around a sphere of several Reynolds numbers are simulated and some characteristic quantities are compared to experimental data and numerical results in the literature.

• Tribology and Lubricants
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• v.37 no.5
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• pp.189-194
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• 2021

A straightforward, yet effective surface modification method of stainless steel mesh and its interesting anti-wetting characteristics are reported in this study. The stainless steel mesh is electrochemically etched, and the specimen has both micro and nano-scale structures on its surface. This process transforms the two types of mesh specimens known as the regular and dense specimens into hydrophobic specimens without applying any hydrophobic chemical coating process. The fundamental wettability of the modified mesh is analyzed through a dedicatedly designed experiment to investigate the waterproof characteristics, for instance, the penetration threshold. The waterproof characteristics are evaluated in a manner that the modified mesh resists as high as approximately 2.7 times the pressure compared with the bare mesh, i.e., the non-modified mesh. The results show that the penetration threshold depends primarily on the advancing contact angles, and the penetration stop behaviors are affected by the contact angle hysteresis on the surfaces. The findings further confirm that the inexpensive waterproof meshes created using the proposed straightforward electrochemical etching process are effective and can be adapted along with appropriate designs for various practical applications, such as underwater devices, passive valves, and transducers. In general, , additional chemical coatings are applied using hydrophobic materials on the surfaces for the applications that require water-repelling capabilities. Although these chemical coatings can often cause aging, the process proposed in this study is not only cost-effective, but also durable implying that it does not lose its waterproof properties over time.