• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.358-359
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• 2005

Chemical mechanical polishing(CMP) process depends on a variety of variables. Especially, surface roughness of pad plays a key role in material removal in CMP in terms of transportation ability of pores and real contact area. The surface roughness is deteriorated with polishing time by applied pressure and relative velocity. In this reason, diamond conditioner has been used to maintain the roughness on the pad. The authors try to investigate the correlation between pad roughness and frictional behavior by comparing ex-situ conditioning with in-situ conditioning.

• Journal of Powder Materials
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• v.14 no.1 s.60
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• pp.44-49
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• 2007

In the fabrication of dye-sensitized solar cells (DSSCs), carbon counter electrode has been tested for replacing the platinum counter electrode which has two drawbacks: limited surface area and high material cost. Poor mechanical stability of carbon layer due to weak bonding strength to electrically conductive TCO (transparent conducting oxide) glass substrate is a crucial barrier for practical application of carbon counter electrode. In the present study a carbon counter electrode with high conversion efficiency, comparable to Pt counter electrode, could be fabricated by adaption of a bonding layer between particulate carbon material and TCO substrate.

• Journal of Powder Materials
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• v.24 no.1
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• pp.17-23
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• 2017

In this study, a finite element analysis approach is proposed to predict the fluid-structure interaction behavior of active materials for lithium-ion batteries (LIBs), which are mainly composed of graphite powder. The porous matrix of graphite powder saturated with fluid electrolyte is considered a representative volume element (RVE) model. Three different RVE models are proposed to consider the uncertainty of the powder shape and the porosity. P-wave modulus from RVE solutions are analyzed based on the microstructure and the interaction between the fluid and the graphite powder matrix. From the results, it is found that the large surface area of the active material results in low mechanical properties of LIB, which leads to poor structural durability when subjected to dynamic loads. The results obtained in this study provide useful information for predicting the mechanical safety of a battery pack.

• Economic and Environmental Geology
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• v.32 no.2
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• pp.151-159
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• 1999

This research was carried out to evaluate the possible usage of natural clay materials collected from the Kimpo landfill site and nearby clay mines as a clay liner material. In order to evaluate the possible usage as a clay liner material, specific gravity, pH, loss-on-ignition, organic carbon content and mineralogical composition of clay materials were measured. The Atterberg limit test and the size analysis were performed for the engineering classification and the prediction of hydraulic conductivity of clay materials. Caution exchange capacity and batch tests were also carried out for the assessment of attenuation capacity. Clay specimens of KPNCL, KP-1, KP-2 and SH were recommended as suitable clay linder materials from viewpoint of their basic quality and attenuation capacity.

• Journal of the Korean Society for Advanced Composite Structures
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• v.1 no.4
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• pp.6-12
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• 2010

This study investigates how to apply composite material to the blast loading protection devices, mainly used for military purpose. Traditionally, earth-filled blast walls have been used for protecting important parts of military facilities and personnels. However these types of blast walls show difficulty in fabrication and portability because of their nature of heavy weight. Composite materials are known to have relatively higher specific stiffness and strength than any other metallic and earth-filled materials such as sand and gravels. Totally 4 times of TNT blast experiments were performed on the carbon/epoxy blast walls. After the end of each test, the improvement of blast wall was implemented to the structure. The test results show that the use of composite material in the blast protecting area is the one of very effective and reliable alternatives.

• Journal of the Korea Institute of Building Construction
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• v.11 no.6
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• pp.576-586
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• 2011

In recent years, pollution in residential spaces has been a significant area of concern. In particular, the indoor air quality (IAQ) of an apartment building before occupancy, which is related to the interior material, is a serious problem. Unlike previous research, which has mainly focused on pollution control after construction, this study has derived influencing factors and priority of management with a controlling schedule for IAQ. The objectives of this research are 1) control of schedule or improvement of management for IAQ, 2) distribution of responsibility to the parties concerned (factory, material company, construction company, design and engineering, occupancy). The results show the relative priority of the four major items in wall?based apartment buildings and in column?based apartment buildings. An analysis of the parties responsible for improvement based on the IAQ results shows more efforts to improve IAQ are needed in material factories and engineering/design companies.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07a
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• pp.426-429
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• 2005

The fringe-field switching (FFS) mode associated with a transition from a homogenously aligned to twist deformation require rubbing process. In this devices, $1^o$ of misalignment in an azimuthal direction could cause voltage-dependent transmittance (V-T) to be different from that in a normal area and consequently results in a rubbing mura. According to our studies, the single domain FFS cells are much more sensitive to the rubbing mura than the dual domain FFS cell. Moreover, the FFS cells with negative LC are much more sensitive to the rubbing mura than the FFS cells with positive LC.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.12S
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• pp.1224-1231
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• 2003

This paper reports on the air-gap type thin film bulk acoustic wave resonator(FBAR) using ultra thin wafer with thickness of 50$\mu\textrm{m}$. It was fabricated to realize a small size devices and integrated objects using MEMS technology for flexible microsystems. To reduce a error of experiment, MATLAB simulation was executed using material characteristic coefficient. Fabricated thin FBAR consisted of piezoelectric film sandwiched between metal electrodes. Used piezoelectric film was the aluminum nitride(AlN) and electrode was the molybdenum(Mo). Thin wafer was fabricated by wet etching and dry etching, and then handling wafer was used to prevent damage of FBAR. The series resonance frequency and the parallel frequency measured were 2.447㎓ and 2.487㎓, respectively. Active area is 100${\times}$100$\mu\textrm{m}$$^2$.Q-factor was 996.68 and K$^2$$\_$eff/ was 3.91％.

• Journal of the Korean Society for Railway
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• v.6 no.4
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• pp.252-256
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• 2003

Smart materials can adapt to changes of environment like living organs in nature such that they can maximize the performance and minimize the maintenance expense of engineering systems. Such materials have been paid attention ten years ago and applied in the area of industry, aerospace, transportation and civil structures. This paper summarizes smart material technology and shows some application examples in railway vehicles. Also, its future of smart material technology in railway vehicle technology is envisaged based on its possibility and practical aspect.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.3
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• pp.74-78
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• 2008

Conventionally, when we need to know about the dynamic characteristics of motors, the moving band method has been the first considerable technique. In this paper, we have investigated the moving material method that moves the property of the material in moving area elements of BLDC motors, instead of moving mesh elements of the rotor. From this method, we can reduce the demanded HDD memory for FEM analysis and the calculation time with same results.