• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1991년도 추계학술대회 논문집
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• pp.48-51
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• 1991

Short channel Nonvolatile EEPROM memory devices were fabricated to CMOS 1M bit design rule, and reviews the characteristics and applications of SNOSFET. Application of SNOS field effect transistors have been proposed for both logic circuits and nonvolatile memory arrays, and operating characteristics with write and erase were investigated. As a results, memory window size of four terminal devices and two terminal devices was established low conductance stage and high conductance state, which was operated in “1” state and “0”state with write and erase respectively. And the operating characteristics of unit cell in matrix array were investigated with implementing the composition method of four and two terminal nonvolatile memory cells. It was shown that four terminal 2${\times}$2 matrix array was operated bipolar, and two termineal 2${\times}$2 matrix array was operated unipolar.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.78-83
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• 2001

In this work, the surface of inorganic fillers were modified with some functional groups such as stearic acid, aliphatic long chain, vinylsilane and aminosilane to control the interaction between inorganic fillers and polymer matrix. Ethylene-vinyl acetate copolymers (EVA) with various amount of vinyl-acetate content and copolyether-ester elastomer were used as polymer matrix. The addition of inorganic fillers increases flame retardancy, but results in steep drop of electrical and mechanical properties, which may be caused by the defect in the interface between organic/inorganic hybrid composites. The hybrid composites are found to show better mechanical properties and higher volume resistivities as inorganic fillers are well dispersed and have good adhesion with polymer matrix. Also, the most effective type of functional group coated on fillers depends on the chemical structure of polymer.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 춘계학술대회논문집
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• pp.280-285
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• 2008

The helmholtz resonator with the perforated neck has demerits that the absorption performance is not so outstanding in an anti-resonance frequency and high frequency bandwidth. In order to overcome these problems, in the paper, a resonator combined with porous material is proposed. The absorption performances of resonators are measured by two-microphone method and estimated by transfer matrix method. The experimentally measured values of normal absorption coefficients agree well with the corresponding values from the transfer matrix method. Because of the porous material, it is shown that the absorption performance have been significantly improved in the anti-resonance frequency and high frequency bandwidth.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2003년도 추계학술발표대회 논문집
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• pp.207-210
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• 2003

Vacuum hot pressing has been used for the development of Ti-MMCs using foil-fiber-foil method, and subsequent micro-mechanical characteristics of the composites are evaluated by means of several experimental processes. As shown by the results, fiber strength degradation occurs during the consolidation, and particularly residual stresses results from the thermal expansion mismatch between fiber and matrix materials during cooling process are incorporated in the changes of mechanical properties of the composites. In industrial applications, the processing conditions avoiding micro-material failures are important together with the properties of finished products, and therefore should be included in the assesment of the material characterization.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2005년도 추계학술발표대회 논문집
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• pp.49-52
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• 2005

In the development of a propellant tank using liquid oxygen and liquid hydrogen, the improvement of microcrack resistance of carbon/epoxy composites is necessary for the application of a composite material to tank structures. In this research, two types of carbon/epoxy composites with different matrix systems were tested to measure interlaminar shear strength (ILSS), one of the material properties to evaluate fiber-matrix interface adhesion indirectly. Short beam specimens were tested inside an environmental chamber at room temperature(RT) and at cryogenic temperature( - 150 $^{\circ}C$) respectively. Results showed that the matrix system with large amount of bisphenol-A and CTBN modified rubber had good performance at cryogenic temperature.

• 한국소음진동공학회논문집
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• 제19권6호
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• pp.628-633
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• 2009

The helmholtz resonator with the perforated neck has demerits that the absorption performance is not so outstanding in an anti-resonance frequency and high frequency bandwidth. In order to overcome these problems, in the paper, a resonator combined with porous material is proposed. The absorption performances of resonators are measured by two-microphone method and estimated by transfer matrix method. The experimentally measured values of normal absorption coefficients agree well with the corresponding values from the transfer matrix method. Because of the porous material, it is shown that the absorption performance have been significantly improved in the anti-resonance frequency and high frequency bandwidth.

• 한국세라믹학회지
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• 제34권10호
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• pp.1092-1098
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• 1997

Electrical discharge machining (EDM) was attempted on a ceramic matrix composite containing non-conductive alumina as a matrix and conductive titania as a second phase, and was found successful. As the current or duty factor increased, the material removal rate (MRR) increased and the surface roughness also increased. The EDMed surface was covered with a number of craters of a circular shape having 100-200 microns of diameter. The melting and evaporation was suggested for the EDM mechanism. The bending strength decreased 44% after EDM, but the Weibull modulus increased more than twice. Combination of EDM and barre이 polishing resulted in the maintenance of the bending strength level. Temperature distribution near a spark in the sample was computer-simulated by use of finite element method, and was found to have similar shape to the one which the observed craters have.

• 대한안전경영과학회지
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• 제13권4호
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• pp.101-108
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• 2011

In this paper deals with strength of glass fiber reinforced plastics produced by shouting machine was investigated by universal testing instrument. We can obtain following results by performing the strength evaluation of polymer composite material according as varied environment temperature. The effect of environmental temperature on Strength properties was more sensitive in the weld specimen than parent. When changed environmental temperature, variation of strength in the parent was much bigger than it of weld specimen, that is, matrix in the parent, orientation in the specimen ware more sensitive to environmental strength. Tensile strength of polycarbonate matrix was similar regardless of mold temperature.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1998년도 춘계학술대회 논문집
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• pp.243-246
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• 1998

This paper presents a 6-bit self-calibrated D/A converter designed with current cell matrix structure. This structure is based on the current-cell matrix configuration using a regulated gate cascode current cell with 3-way switch. using from CMOS process and 5V power supply, the simulated conversion rate is 45.78MHz and the average mismatching properties among current sources are reduced to 0.02% and 0.005%, respectively when 1% and 0.5% errors of current sources are considered.

• Structural Engineering and Mechanics
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• 제5권6호
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• pp.785-801
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• 1997

Reinforced Concrete beams with tension and compression softening material constitutive laws are studied. Energy-based and non-local regularisation techniques are presented and applied to a R.C. element. The element characteristics (sectional tangent stiffness matrix, element tangent stiffness matrix restoring forces) are directly derived from their symbolic expressions through numerical integration. In this way the same spatial grid allows us to obtain a non-local strain estimate and also to sample the contributions to the element stiffness matrix. Three examples show the spurious behaviors due to the strain localization and the stabilization effects given by the regularisation techniques, both in the case of tension and compression softening. The possibility to overestimate the ultimate load level when the non-local strain measure is applied to a non softening material is shown.