• 한국생산제조학회지
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• 제23권5호
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• pp.435-442
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• 2014

This paper describes an improved design model that can be used to configure a non-contact pneumatic device to turn a large sheet at the in-line system. For rotational moving in the conveyor system, the conventional method is to turn the system itself. The improved non-contact pick-up system mainly uses 8 pairs of L-shaped latches and 12 swirl type heads. It is positioned above the upward air flow table. This system performs the non-contact gripping and side-edge contact support in the vertical and rotational directions to hold the self-weight of a large flat sheet. A non-contact air head can exert a sufficient gripping ability at 4N lower than the standard working pressure. The side latches support 60% of the lifting force required. Through structural and flow analysis, the working conditions were simultaneously considered in accordance with the deflection and flatness of the glass.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
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• pp.413-413
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• 2007

In recent years, flexible display devices such as liquid crystal display (LCD), organic light emitting diode (OLED), etc. have attracted considerable interest in a wide variety of applications. Polymer substrate is absolutely necessary to realize this kind of flexible display devices. Using the polymer as a substrate, there are lots of advantages including not only mechanical flexibility such as rolling and bending characteristics but also light weights, low cost and so on. In detail, thickness and weights is only one forth and one second of glass substrate, respectively. However, it needs low temperature below $150^{\circ}C$ in the fabrication process comparing to conventional deposition process. The polymer substrate is not thermally stable as much as the glass substrate so that some deformation can be occurred according to variation of temperature. In particular, performance of devices can be easily deteriorated by shrinkage of substrate when heating it. In this paper, pre-annealing and deposition of buffer layer was introduced and studied to solve previously mentioned problems of the shrinkage and followed shear stress.

• 한국전자파학회논문지
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• 제22권6호
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• pp.605-612
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• 2011

본 논문에서는 차량 앞유리에 탈부착이 가능한 다이폴 형태의 T-DMB 수신용 안테나를 설계하였다. 안테나의 구조는 동박과 급전선의 매우 간단한 구조를 가지며, 운전자의 시야에서 완벽히 벗어날 수 있도록 차량 유리의 테두리 쪽에 존재한다. 차체의 특성과 안테나의 입력 임피던스 특성을 고려하여 제안된 미앤더 형태의 다이폴 안테나는 T-DMB 주파수 대역(174~216 MHz)을 만족한다. Common Mode Stub를 추가한 Flexible 안테나는 차량 앞유리에서 부착되는 위치에 상관없이 안테나의 입력 반사 손실은 -5 dB 이하를 가지는 것이 가장 큰 특징이다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.431-431
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• 2013

Flexible Organic Light Emitting Diode (OLED) displays are required for future devices. It is possible that plastic substrates are instead of glass substrates. But the plastic substrates are permeable to moisture and oxygen. This weak point can cause the degradation of fabricated flexible devices; therefore, encapsulation process for flexible substrate is needed to protect organic devices from moisture and oxygen. Y.G. Lee et al.(2009) [1] reported organic and inorganic multilayer structure as an encapsulation barrier for enhanced reliability and life-time.Flowable Oxide process is a low-temperature process which shows the excellent gap-fill characteristics and high deposition rate. Besides, planarization is expected by covering dust smoothly on the substrate surface. So, in this research, Bi-layer structured is used for encapsulation: Flowable Oxide Thin film by PECVD process and Al2O3 thin film by ALD process. The samples were analyzed by water vapor transmission rate (WVTR) using the Calcium test and film cross section images were obtained by FE-SEM.

• Current Photovoltaic Research
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• 제10권4호
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• pp.107-110
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• 2022

Lightweight and flexible photovoltaic (PV) modules are attractive for building-integrated photovoltaic (BIPV) applications because of their easy construction and applicability. In this study, we fabricated lightweight and flexible c-Si PV modules using ethylene tetrafluoroethylene (ETFE) front cover and shingled design string cells. The ETFE front cover instead of glass made the PV modules lighter in weight, and the shingled design string cells increased the flexibility. Finally, we fabricated a PV module with a conversion power of 240.08 W at an area of 1.25 m² and weighed only 2 kg/m². Moreover, to check the PV module's flexibility, we conducted a bending test. The difference of conversion power between the modules before and after bending shown was only 1.7 W, which showed a power reduction rate of about 0.7%.

• 한국지반신소재학회논문집
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• 제13권1호
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• pp.33-40
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• 2014

보통 지중에 매설되는 관은 강성관과 연성관으로 구분된다. 연성관 중 유리섬유강화플라스틱(Glass fiber reinforced thermosetting polymer plastic, GFRP)으로 이루어진 GFRP 관은 지중에 매설시 지반과 관의 상호관계를 고려하여 설계되어야 한다. 본 연구에서는 지중에 매설되는 GFRP 관의 장단기의 구조적 거동을 조사하고자 한다. 먼저, 국내에서 생산되는 GFRP 관의 역학적 성질조사를 하고, 현장매설실험과 유한요소해석을 수행하여 장기거동 예측에 대한 기초자료로 활용하였다. GFRP 관의 장기거동을 예측하기 위해 약 5,232시간 동안의 수직 관변형을 조사하였으며, 이를 바탕으로 최대 50년 동안의 관변형에 대하여 Monod-type 방법으로 예측하였다.

• 한국도로학회논문집
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• 제3권1호
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• pp.151-163
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• 2001

아스팔트포장층내에 보강용 토목섬유를 설치하여 포장층의 응력-거동특성을 연구한 예는 매우 드물다. 본 연구에서는 유한요소법을 사용하여 지오그리드와 유리섬유로 보강한 층의 응력-변형 특성을 연구하였다. 유리섬유와 지오그리드의 강성이 다른 두가지 종류를 사용하고 설치위치, 포장단면층의 두께 변화를 주어 아스팔트포장층에 미치는 영향을 분석하였다. 포장층내에 발생하는 수직응력, 수직변위, 최대전단응력을 분석한 결과 수직응력, 수직변위 보다 최대전단응력을 크게 감소시키는 경향이 나타났다. 최대전단응력 감소효과가 약 15$\sim$20% 정도 있음을 알 수 있었다. 보강재의 탄성계수가 큰 유리섬유가 가장 효과가 좋으며 깊이 3cm$\sim$5cm에 설치하는 것이 가장 효과가 좋은 것으로 나타났다.

• 폴리머
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• 제37권6호
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• pp.711-716
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• 2013

폴리(에틸렌 나프탈레이트)(PEN)의 사슬 배향과 이완이 PEN 유연기판의 치수안정성 및 광학 특성에 미치는 영향에 대하여 살펴보았다. 사슬이 배향된 PEN 기판은 사용온도 증가 시 PEN 분자 유동성을 감소시켜 $100^{\circ}C$ 이하에서 PEN의 열팽창계수(CTE)를 $20ppm/^{\circ}C$까지 감소시키나, 유리전이온도 근처에서 연신된 사슬의 이완에 의하여 열수축이 발생됨을 알 수 있었다. 유리전이온도 근처에서의 열처리는 이러한 열수축을 최소화시킬 수 있으나 사슬이완에 따른 PEN 분자의 경직성 또한 감소되어 열팽창계수가 연신 전 PEN의 고유 CTE의 65% 정도인 $70ppm/^{\circ}C$까지 다시 증가함을 확인하였다. 열처리 과정에서 연신된 필름에 응력을 가하지 않는 경우, 열수축 시작 온도 증가와 함께 열수축을 최소화할 수 있으며 연신에 의해 얻어진 낮은 CTE 또한 유지할 수 있었다. 배향에 의한 광 투과도 감소는 없는 반면 열처리는 미약한 결정화를 발현시켜 5% 정도의 광 투과도가 감소됨을 알 수 있었다.

• 대한조선학회논문집
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• 제54권5호
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• pp.415-420
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• 2017

Insulation systems in Liquefied Natural Gas Carriers (LNGC) are vulnerable to sloshing impact and fatigue loads because of waves. If gas leaks into the primary barrier, the Flexible Secondary Barrier (FSB) prevents the leakage of gas in this system. Fatigue strength of the FSB largely depends on the behavior of composite materials. In this study, a new system is applied to the FSB using aramid fiber to improve the fatigue strength of the secondary barrier, with the intention of replacing conventional E-glass fibers. The manufacturing method involved varying the ratio of the aramid fiber to the E-glass fiber for optimum design of the FSB. The fatigue tests results of the secondary barrier using aramid fiber were superior to that using E-glass fiber. The statistical analysis is performed to obtain the fatigue test results and estimate the probability of failure as well as the design guideline of LNGC secondary barriers.

• Bulletin of the Korean Chemical Society
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• 제29권6호
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• pp.1167-1172
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• 2008

We investigated the glass transition temperatures ($T_g$) of dendrons consisting of conformationally mobile aliphatic polyether dendritic cores plus glassy peripheral polystyrenes (PSs), and linear PSs in the molecular weight range of 1000-8500 g/mol. We compared their $T_g$ behavior depending on their polymeric architecture. The linear PSs show a typical growth of $T_g$ up to 92.5 ${^{\circ}C}$ as the molecular weight increases to 8300 g/mol, while the dendrons display nearly constant $T_g$ values of 58-61 ${^{\circ}C}$, despite the increase of molecular weight with each generation. The striking contrast of Tg behavior would be mainly attributed to the fact that the dendrons keep the ratio of $N_e$/M ($N_e$: number of peripheral chain ends, M: molecular weight) over all the generations. Additionally, for the influence of dendritic spacers on glass transition temperature we prepared dimeric PSs with different linkage groups such as aliphatic ether, ester and amide bonds. We found that the dimer with the ether spacer exhibited the lowest glass transition at 55.4 ${^{\circ}C}$, while the amide linked dimer showed the highest glass transition temperature at 74.2 ${^{\circ}C}$. This indicates that the peripheral PS chains are effectively decoupled by the conformationally flexible ether spacer. The results from this study demonstrated that polymeric architecture and dendritic core structures play a crucial role in the determination of glass transition behavior, providing a strategy for the systematic engineering of polymer chain mobility.