• 대한금속재료학회지
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• 제50권10호
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• pp.729-734
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• 2012

This study investigated the effect of water absorption on the tensile properties of carbon-glass/epoxy hybrid composites at room temperature and $-30^{\circ}C$. To investigate the effect of the position of glass fabric in the hybrid composite on the tensile properties, the stacking pattern of the fiber fabrics for reinforcing was created in three different ways: (a) glass fabrics sandwiched between carbon fabrics, (b) carbon fabrics sandwiched between glass fabrics and (c) alternative layers of carbon and glass fabrics. They were manufactured by a vacuum-assisted resin transfer molding (VARTM) process. The results showed that there was surprisingly little difference in tensile strength at the two different temperatures with dry and wet conditions. However, the water absorption into the hybrid system affected the tensile properties of the hybrid composites at RT and $-30^{\circ}C$. When the glass fabrics were at the outermost layers, the hybrid composite had the lowest tensile properties. This is attributed to the fact that the composite had a relatively high water absorption rate.

• 한국세라믹학회지
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• 제43권1호
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• pp.33-37
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• 2006

For producing the fine ribs structure of plasma display panel, the metal ions of barrier materials during the etching process should be understood on the etching mechanism with etching conditions. Etching was done on bulk glasses of the $BaO_B_2O_3-ZnO$ system with $HNO_3$ solution at $40^{\circ}C$. The surface structure of glasses and ion dissolution were analyzed by ICP (Inductive Coupled Plasma measurement). The structure and surface of the etched bulk glass were investigated by using scanning electron microscopy and nanoindenter. As a result, Ba (3-35 ppm/min) and Zn (2-27 ppm/min) ions as major components were leached in the solution and the leached layers were found to be phosphor-rich surface layers. A decrease of the bridge oxygen and relative increase of non bridge oxygen in the etched glass were found by X-ray photoelectron spectroscopy.

• 한국음향학회지
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• 제26권1호
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• pp.8-15
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• 2007

음향 공동-유리창 연성계를 대상으로 도청음의 음성 명료도를 검토한다. MLS신호를 음원으로 유리창의 가속도와 속도 응답을 가속도계와 레이저 도플러 진동계를 사용하여 측정한다. 변조전송함수 (MTF)를 사용하여 공동-유리창 진동계의 음성전달특성을 규명한다. 변조전송함수에 근거하여 음성전송지수 (STI)를 구하고, 유리창 진동음의 음성명료도를 평가한다. 가속도음과 속도음의 음성명료도를 비교하고, 최종적으로 대화음의 명료도를 주관적 평가로 확인한다.

• 한국정보통신학회논문지
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• 제25권1호
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• pp.124-133
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• 2021

스마트팩토리는 공장 내 장비에 센서를 부착하여 각종 데이터를 실시간으로 수집, 분석 및 모니터링함으로써 스스로 공정을 제어 및 통제하는 미래형 공장이다. 스마트팩토리에서 장비의 상태 및 이력을 현장에서 실시간으로 조회 및 생성하는 것은 매우 중요한 일이며 다양한 스마트 기기의 등장은 이것을 보다 효율적으로 수행할 수 있게 하고 있다. 본 논문은 실시간으로 장비의 상태 및 이력을 생성, 조회, 삭제 할 수 있는 다중장치 기반 시스템을 제안한다. 제안 시스템은 공장이라는 특수한 환경을 고려하여 안드로이드 시스템과 스마트 글래스 시스템을 동시에 사용한다. 스마트 글래스 시스템은 장비 인식을 위해 QR코드를 이용하였으며 음성 인식 기능을 이용하여 보다 효율적인 작업환경을 제공한다. 다중장치기반 실시간 장비 모니터링을 위한 시스템 구조를 설계하였으며 안드로이드 시스템, 스마트 글래스 시스템 및 웹 애플리케이션 서버를 구현함으로써 실용성을 보이겠다.

• Current Optics and Photonics
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• 제1권4호
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• pp.378-388
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• 2017

We present a graphical method for determining a pair of optical materials and powers to design an achromatic and athermal lens system with corrected Petzval curvature. To graphically obtain the solutions, a three-dimensional (3D) glass chart is proposed. Even if a particular material combination is unavailable, we can select an element suitable for a specific lens and continuously change the element powers of an equivalent single lens for aberrations correction. Thus, we can iteratively identify the materials and powers on a 3D glass chart. By designing a fisheye lens using this method, an achromatic and athermal system with flat Petzval curvature is obtained, over the specified waveband and temperature ranges.

• 대한안전경영과학회지
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• 제10권4호
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• pp.105-109
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• 2008

The purpose of this study is to distinguish the causes of broken glass on doors or windows when it is originally kept among the remains on the floor in fire site - whether it was broken due to heating or outer power-through test and characteristics of the broken plane including the pattern on the plane. Addition to it, the study tries to find characteristics to judge the point and direction of breakdown through the analysis of glass broken by outer power. With two assumed causes - a) breakdown due to heating and b) breakdown due to outer power-3 pieces of glass plates ($30cm{\times}30cm{\times}5mm$) were tested for each case, getting the results as following: First, for the glass broken due to the change of temperature, the broken plane is of slow and smooth curve without any pattern. Second, for the glass broken due to outer power, with the impact point as the center, the glass shows breakdown of radial type and the side shows breakdown of near-perpendicular type. The far the broken piece is from the impact point, the bigger the size is. The broken piece at the impact point is of long triangle type and the two long planes of the triangle shows semi-arc with the center of breakdown point and the other plane shows opposite pattern. Third, when glass that is damaged by outer power is heated, damaged forms and side patterns of the glass that is damaged by outer power are heated and disappeared.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1995년도 추계학술대회 논문집
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• pp.18-21
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• 1995

In this study, crystallization, water swelling and dielectric properties of Li$_2$O-MgO-MgF$_2$-SiO$_2$System glass ceramics were investigated. Base glass melted at 1450$^{\circ}C$ and crystallized through heat treatment. The optimum heat treatment schedule was 460$^{\circ}C$ for nucleation and 640$^{\circ}C$, 1100$^{\circ}C$ for crystallization. The Principle crystalline phase was lithium fluorhectorite. Lithium fluorhectorite was the crystal phase which it was influenced water swelling. Samples progressed 2 minutes later they have rapid hydration at forced water swelling condition. Also value of dielectric constants have approximately 10 at 100kHz.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2003년도 International Meeting on Information Display
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• pp.814-817
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• 2003

The sintering behavior of $BaO-B_{2}O_{3}-ZnO$, which is Pb-free glass-ceramic system, was examined as functions of the composition and the amount and particle size of $Al_{2}O_{3}$ filler. Different kinds of modifiers were added and $Al_{2}O_{3}$ fillers with different particle sizes ($1.5{\mu}m$ and $4.5{\mu}m$) were added. The glass frit-filler composites were sintered in the temperature range $520{\sim}580^{\circ}C$. X-ray diffraction results revealed that some of the composites crystallized during sintering. Dielectric constant and thermal expansion coefficient the glass-ceramics were analyzed.

• 한국세라믹학회지
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• 제23권6호
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• pp.25-32
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• 1986

Phase spearated glass is heterogeneous in microscopic point of view and the heterogeneities affect the structures of glasses. In the present work the phase separation of $BaO-B_2O_3$ glass system was investigated and the effect of $P_2O_5$ on the phase separation and crystallization was also studied in the above system. Experiments such as scanning electron microscopy X-ray diffraction and infrared spectroscopy were performed. Phase separation with $B_2O_3$ rich phase matrix and BaO rich phase droplet was observed for the glasses containing less than 6 mole% of BaO while the opposite morphology of phase separation was found for the glasses containing more than 7 mole% of BaO. Phase separation region was extended up to the glass with 22mole% of BaO when the amount of $P_2O_5$ was increased. The heat-treated glasses crystallized to BaO.$4B_2O_3$$P_2O_5$ hindered the glass from the crystalli-zation.

• 유변학
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• 제10권2호
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• pp.57-64
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• 1998

A pultrusion resin impregnation (PRI) die, which has been developed recently in our laboratory, was used to pre-pare various composite system. The continuous fiber reinforced composites of glass fiber/polypropylene(GFPP) and glass fiber/polyamide 6 (GFPA) were first manufactured by means of the PRI die and then cut into chopped pellets of predet-ermined length. These pellets and either virgin or modified thermoplastic resin were melt-mixed by a twin screw extruder to prepare GF/PA/PP and GF/PA/PPMA system. The mechanical properties of these blends were investigated and discussed in terms of their morphological observations. These preliminary results revealed that this new impregnation die could be suc-cessfully applied to produce prepregs suitavle for the final shaping process.