• 대한기계학회논문집B
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• 제27권7호
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• pp.956-962
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• 2003

The Lippmann-Young equation has been widely used in electrowetting to predict the contact-angle change of a droplet on a insulating substrate with respect to the externally-applied electrical voltage. The Lippmann-Young equation is derived by assuming a droplet as a perfect conductor, so that the effect of the electrical double layer and the line tension are not taken into account. The validity of the assumption has never been checked before, systematically. In the present investigation, a modified Lippmann-Young equation is derived taking into account of the effect of the electrical double layer and the line tension. To assess their influence on contact-angle change in electrowetting, the electrostatic field around the three-phase contact line is analyzed by solving the Poisson-Boltzmann equation numerically. The validity of the numerical methods is verified by using the past theoretical results on the electrostatic field around a wedge-shaped geometry, which shows fairly good agreement. The results of the present investigation clearly indicate that the effect of the electrical double layer and the line tension is negligible for a millimeter-sized droplet. On the other hand, for a micron-sized droplet, the effect of the line tension can become a dominating factor which controls the contact-angle change in electrowetting.

• 한국정보전자통신기술학회논문지
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• 제15권5호
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• pp.315-320
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• 2022

일반적인 나선형 인덕터의 경우에 비대칭 구조를 가짐에 따라 포트의 방향에 영향을 받게 된다. 본 논문에서는 2층이면서 대칭 구조를 가질 수 있는 나선형 인덕터를 제안하고 시뮬레이션 및 주파수 특성을 분석하였다. 기존 단층 대칭형 인덕터가 3.9~4.2nH의 인덕턴스를 갖는 것과 비교하여 제안된 2층 대칭 나선형 인덕터는 포트에 변함없이 0.3~1.2GHz 범위에서 11~12nH의 인덕턴스, 800MHz에서 약 4.4의 품질계수, 약 2.7~2.8GHz의 자기공진주파수를 가진다. 이는 기존 일반적인 나선형 인덕터가 포트에 따라 큰 차이를 갖는 것과 비교하여 포트의 방향에 대한 영향이 적은 것을 확인할 수 있었다.

• 한국인터넷방송통신학회논문지
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• 제20권1호
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• pp.77-82
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• 2020

본 논문에서는 2중 유전체층 사이의 완전도체띠 격자구조에 의한 E-분극 전자파 산란 문제는 전자파 수치해석 방법으로 알려진 FGMM(Fourier-Galerkin moment method)를 이용하여 해석하였다. 경계조건들은 미지의 계수를 구하기 위하여 이용하였고, 도체띠의 해석을 위해 완전도체 경계조건을 적용하였다. 도체띠의 폭과 주기, 2중 유전층 사이의 비유전율과 두께 및 입사각에 대해 정규화된 반사전력과 투과전력을 계산하였다. 전반적으로 2중 유전체 층의 비유전율이 증가할수록 반사전력은 증가하였으며, 상대적으로 투과전력은 감소하였다. 2중 유전체 층의 비유전율이 증가할수록 도체띠에 유도되는 전류밀도는 스트립 중앙에서 증가하였다. 본 논문의 제안된 구조에 대한 수치결과들은 기존 논문의 수치해석 결과들과 비교하여 매우 잘 일치하였다.

• 한국인터넷방송통신학회논문지
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• 제20권1호
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• pp.83-88
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• 2020

본 논문에서는 접지된 2중 유전체층 사이의 완전도체띠 격자구조에 의한 H-분극 전자파 산란 문제는 전자파 수치해석 방법으로 알려진 FGMM(Fourier-Galerkin Moment Method)를 이용하여 해석하였다. 경계조건들은 미지의 계수를 구하기 위하여 이용하였고, 도체띠의 해석을 위해 완전도체 경계조건을 적용하였다. 도체띠의 폭과 주기, 접지된 2중 유전층 사이의 비유전율과 두께 및 입사각에 대해 정규화된 반사전력을 계산하였다. 전반적으로 접지된 2중 유전체층의 비유전율 및 두께가 증가할수록 반사전력은 증가하였다. 그리고 접지된 2중 유전체 층의 두께가 증가할수록 도체띠에 유도되는 전류밀도는 스트립 중앙에서 증가하였다. 본 논문의 제안된 구조에 대한 수치결과들은 PMM을 이용한 기존 논문의 수치해석 결과 들과 비교하여 매우 잘 일치하였다.

• 한국군사과학기술학회지
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• 제19권5호
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• pp.618-628
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• 2016

The development of new concepts of liners is required in order to effectively neutralize the enemy's attack power concealed in the armored vehicles. A multiple-layer liner is one of possibilities and has a mechanism for explosion after penetrating the target which is known as "Behind Armor Effect." The multiple-layer explosive liner should have sufficient kinetic energy to penetrate the protective structure and explosive material react after target penetration. With this in mind, double-layer liner materials were obtained by cold spray coating methods and these material properties were experimentally characterized and used in this simulation for double-layer liners. In this study, numerical simulations in the three different layer types, i.e., single, A/B, A/B/A in terms of the layer location were verified in terms of finite element mesh sizes and numerical results for the jet tip velocity, kinetic energy, and the corresponding jet deformation characteristics were analysed in detail depending on the structure of layer types.

• 반도체디스플레이기술학회지
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• 제7권2호
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• pp.49-53
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• 2008

The yellow base polymer light emitting diodes(PLEDs) with double emission and hole blocking layers were prepared to improve the light efficiency. ITO(indium tin oxide) and PEDOT : PSS[poly(3,4-ethylenedioxythiophene) : poly(styrene sulfolnate)] were used as cathode and hole transport materials. The PFO[poly(9,9-dioctylfluorene)] and MEH-PPV[poly(2-methoxy-5(2-ethylhe xoxy)-1,4-phenylenevinyle)] were used as the light emitting host and guest materials, respectively. TPBI[Tpbi1,3,5-tris(N-phenylbenzimidazol-2-yl)benzene] was used as hole blocking layer. To investigate the optimization of device structure, we prepared four kinds of PLED devices with different structures such as single emission layer(PFO : MEH-PPV), two double emission layer(PFO/PFO : MEH-PPV, PFO : MEH-PPV/PFO) and double emission layer with hole blocking layer(PFO/PFO : MEH-PPV/TPBI). The electrical and optical properties of prepared devices were compared. The prepared PLED showed yellow emission color with CIE color coordinates of x = 0.48, y = 0.48 at the applied voltage of 14V. The maximum luminance and current density were found to be about 3920 cd/$m^2$ and 130 mA/$cm^2$ at 14V, respectively for the PLED device with the structure of ITO/PEDOT : PSS/PFO/PFO : MEH-PPV/TPBI/LiF/Al.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2008년도 International Meeting on Information Display
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• pp.270-271
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• 2008

The contact resistance between organic semiconductor and source-drain electrode in Bottom Contact Organic Thin-Film Transistors (BCOTFTs) can be effectively reduced by metal oxide/molybdenum double layer structure; metal oxide layers including nickel oxide (NiOx/Mo) and moly oxide(MoOx) under molybdenum work as a high performance carrier injection layer. Step profiles of source-drain electrode can be easily achieved by simultaneous etching of the double layers using the difference etching rate between metal oxides and metal layers.

• 대한기계학회논문집A
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• 제26권7호
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• pp.1393-1400
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• 2002

A double cantilever sandwich-beam method has been applied to the evaluation of the frequency dependence of dynamic elastic modulus and material loss factor of EPDM rubbers. The flexural vibration of a double cantilever sandwich-beam specimen with an inserted rubber layer was studied using a finite element simulation in combination with the sine-sweep test. Effects of the rubber layer length on the dynamic characteristics were also investigated: reliable values were measured when the length of the inserted rubber layer was larger than and equal to 50% of the effective specimen length. The values were compared with those obtained by the dynamic mechanical analysis and the simple resonant test. Relationships of the dynamic characteristics of rubbers with frequency could be determined using the least square error method.

• Earthquakes and Structures
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• 제9권4호
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• pp.767-788
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• 2015

A steel shear wall with double-tapered links and in-plane reference was developed for assisting the assessment of the structural condition of a building after an earthquake while maintaining the original role of the wall as a passive damper device. The double-tapered link subjected to in-plane shear deformation is designed to deform torsionally after the onset of local buckling and works as an indicator of the maximum shear deformation sustained by the shear wall during an earthquake. This paper first examines the effectiveness of double-tapered links in the assessment of the structural condition under various types of loading. A design procedure using a baseline incremental two-cycle loading protocol is verified numerically and experimentally. Meanwhile, in-plane reference links are introduced to double-tapered links and greatly enhance objectivity in the inspection of notable torsional deformation with the naked eye. Finally, a double-layer system, which consists of a layer with double-tapered links and a layer with rectangular links made of low-yield-point steel, is tested to demonstrate the feasibility of realizing both structural condition assessment and enhanced energy dissipation.

• 공업화학
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• 제20권4호
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• pp.370-374
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• 2009

용존산소농도(DO)와 pH를 동시에 검출하기 위하여 이중층 광학 센서 막을 제조하였다. DO 민감성 염료인 Rudpp를 MTMS 졸-겔에 혼합하고 24-웰 마이크로타이터 플레이트에 코팅하였다. DO-검출층 위에 HPTS와 혼합된 GA 졸-겔용액을 코팅하고 pH 측정을 위해 사용하였다. 이중층 광학 센서 막은 온도와 이온 강도에 영향을 받았다. 또한 DO와 pH 이중층 광학 센서 막은 미생물발효공정에 온라인 모니터링 하는데 응용하였으며 좋은 성능을 보였다.