• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.190-193
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• 2001

ZnO varistors have been widely used to protect power system and electronic system against overvoltages based on their excellent nonlinearity. In order to increase their protection capability, the fracture and protection technologies of arresters have to study according to their applications, namely ImA DC voltage, leakage currents, impulse residual voltages, withstanding capability to impulse surge, and energy absorption capability. ZnO varistors which have nonlinear current-voltage characteristic name a number of failure mechanism when ZnO elements absorb surge energies. Failure mode by thermal stress and Pin hole are among the most common failure mechanism at the high current surge current. In this study, the fracture mechaism of power arresters are introduced and protection technologies are researched. In particular the effect of thermal stress by surge currents to ZnO elements and methods against arc surge energy through withstand structure design of arrester are discussed.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1998년도 추계학술대회 논문집
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• pp.263-266
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• 1998

ZnO varistors have an excellent non-linearity and a large surge-energy absorption capability. For these reasons, the ZnO varistors are widely used to protect electrical/electronic circuits from an abnormal surge and/or noise signal. In order to obtain the low-voltage varistor with randomly distributed large seed grain within bulk, the ZnO varistors are made by a new three-composition seed grain method. And a conduction mechanism of varistors, which was observed in the temperature range of 30 ∼ 120$^{\circ}C$ and at the current range of 10$\^$-8/∼10$^2$ A/cm$^2$, was classified by the three regions of different mechanism when the current was increased.

• 정보저장시스템학회논문집
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• 제1권2호
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• pp.132-136
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• 2005

It is widely accepted that the reading mechanism of Super-RENS(super-resolution near field structure) and Super-ROM(super-resolution read only memory) is closely related with non-linear temperature dependent material properties such as refractive indices, phase change. Furthermore, the dynamic change of the temperature distribution also an essential part of reading mechanism of Super-RENS/ROM. Therefore, the knowledge of the temperature distribution as a function a time is one of the important keys to reveal the physics of reading mechanism in Super-RENS/ROM. We calculated time-dependent temperature distribution in a 3-dimensional Super-ROM disk structure when moving laser beam is irradiated. With a help of commercial software FEMLAB which employed finite element method, we simulated the temperature distribution of ROM structure whose pit diameter is 120-nm with 50-nm depth. Energy absorption by moving laser irradiation, time variations of heat transfer processes, heat fluxes, heat transfer ratios, and temperature distributions of the complicate 3-dimensional ROM structure have been obtained.

• Computers and Concrete
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• 제30권3호
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• pp.185-196
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• 2022

In this paper, the dynamic characteristics of a composite cylindrical beam made of a mechanism of carbon dioxide absorption coated on the tube core are investigated based on the classical beam theory coupled with the modified couple stress theory. The composite tube structures are assumed to be uniform along the tube length, and the energy method regarding the Hamilton principle is utilized for generating the governing equations. A powerful numerical solution, the generalized differential quadrature method (GDQM), is employed to solve the differential equations. The carbon dioxide trapping mechanism is a composite consisting of a polyacrylonitrile substrate and a cross-link polydimethylsiloxane gutter layer. Methacrylate, poly (ethylene glycol), methyl ether methacrylate, and three pedant methacrylates are all taken into account as potential mechanisms for capturing carbon dioxide. The application of the present study is helpful in the design and production of microelectromechanical systems (MEMS) and the different valuable parameters, such as the length-scale parameter, rate of section change, aspect ratio, etc., are presented in detail.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제16권2호
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• pp.544-564
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• 2022

Underwater images often suffer from color distortion, blurring and low contrast, which is caused by the propagation of light in the underwater environment being affected by the two processes: absorption and scattering. To cope with the poor quality of underwater images, this paper proposes a multiscale fusion underwater image enhancement method based on channel attention mechanism and local binary pattern (LBP). The network consists of three modules: feature aggregation, image reconstruction and LBP enhancement. The feature aggregation module aggregates feature information at different scales of the image, and the image reconstruction module restores the output features to high-quality underwater images. The network also introduces channel attention mechanism to make the network pay more attention to the channels containing important information. The detail information is protected by real-time superposition with feature information. Experimental results demonstrate that the method in this paper produces results with correct colors and complete details, and outperforms existing methods in quantitative metrics.

• Journal of Welding and Joining
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• 제31권5호
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• pp.59-63
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• 2013

A bendable electronic module has been developed for a mobile application by using a low-cost roll-to-roll manufacturing process. In flexible embedded electronic module, a thin silicon chip was embedded in a polymer-based encapsulating adhesive between flexible copper clad polyimide layers. To confirm reliability and durability of prototype bendable module, the following tests were conducted: Moisture sensitivity level, thermal shock test, high temperature & high humidity storage test, and pressure cooker tester. Those experiments to induce failure of the module due to temperature variations and moisture are the experiment to verify the reliability. Failure criterion was 20% increase in bump resistance from the initial value. The mechanism of the increase of the bump resistance was analyzed by using non-destructive X-ray analysis and scanning acoustic microscopy. During the pressure cooker test (PCT), delamination occurred at the various interfaces of the bendable embedded modules. To investigate the failure mechanism, moisture diffusion analysis was conducted to the pressure cooker's test. The hygroscopic characteristics of the encapsulating polymeric materials were experimentally determined. Analysis results have shown moisture saturation process of flexible module under high temperature/high humidity and high atmosphere conditions. Based on these results, stress factor and failure mechanism/mode of bendable embedded electronic module were obtained.

• 한국재료학회지
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• 제11권7호
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• pp.599-602
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• 2001

전도성 고분자인 poupyrrole과 polyaniline을 이용하여 센서를 제조하고 휘발성 유기화합물에 대한감응특성 및 감지막의 물성을 조사하여 지금까지 알려지지 않은 감응 기구를 설명하고자 하였다. Polypyrrole과 polyaniline은 두께가 얇은 경우가 두꺼운 경우보다 감도가 높았으며, 1분간 도펀트를 제거한 센서가 가장 높은 감도를 나타내었다. 또한 두 가지 센서 모두 극성이 강한 분자가 흡착될수록 감도가 증가하였는데, 이는 극성을 갖는 분자가 감지막 내부로 침투하여 polaron 및 자유 carrier를 고착시키거나 추가의 자유 carrier를 형성하여 전도도에 변화를 주기 때문인 것으로 판단된다.

• 대한화학회지
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• 제39권5호
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• pp.350-355
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• 1995

요오드와 테트라메틸주석간의 전하이동에 따른 상호작용을 사염화탄소 용매내에서 분광학적 방법으로 연구하였다. 이들의 결과로부터 일시적인 전하이동 착물의 흡수 스펙트 럼(${\lambda}_{max}=270nm$)이 관찰되었으며, 흡수스펙트럼의 후속적인 감소현상으로 요오드에 의한 테트라메틸주석의 분해반응임을 알았다(iodoedestannylation). 따라서 Iodoedestannylation에 대한 속도 상수를 온도 10, 25 및 $35^{\circ}C$ 압력을 1200 bar까지 변화 시켜가면서 측정하였으며, 이때의 반응속도상수는 온도와 압력에 따라 증가함을 알았다. 이 반응속도 상수로부터 ${\Delta}V^{\neq},\;{\Delta}{\beta}^{\neq},\;{\Delta}H^{\neq}$ 및 ${\Delta}S^{\neq}$의 값을 구했으며 이들 값으로부터 전이상태의 용매구조 변 화 및 메카니즘을 규명하였다. 이러한 사실로부터 본 반응은 $S_F2$ 메카니즘이 지배적 이며 압력이 증가함에 따라 $S_F2$의 성격이 약화됨을 알았다.

• 한국펄프종이공학회:학술대회논문집
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• 한국펄프종이공학회 2000년도 추계학술발표논문집
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• pp.83-83
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• 2000

Alkylketene dimer was known as a cellulose reactive or alkaline size because it does not require to fix to the fiber as do the traditional rosin sizes. A proposed sizing mechanism of AKD was the formation of P -ketoester bond between AKD and cellulose which provides the permanent attachment and the orientation of the hydrophobic alkylchains outward. However, some questions about the reaction had arisen and thus, the sizing mechanism of AKD has been a subject of controversy for several decades. The major concern of the controversy is that AKD is really reactive with cellulose or not in the papermaking conditions. In this study, reaction between AKD and pulp fiber was investigated, in order to find out whether AKD forms P-ketoester with pulp fiber during aging under no catalyzed neutral condition with obvious spectroscopic evidence. In addition, effect of aging treatment on the sizing development was studied. It has been disclosed that, in absence of water, AKD reacted with cellulose to form P -ketoester linkage under no catalyzed neutral condition, while, in presence of water, most of AKD was hydrolyzed to a dialkyl ketone or P -ketoacid. In addition, during the aging treatment of AKD-sized paper, its typical IR spectra bands gradually were reduced, completely disappeared after 6hr aging, and formed new absorption bands at 1707cm-' and shoulder peak at 1700cm-' which refer to the typical dialkylketone absorption bands. Therefore, the formation of P -ketoester between AKD and pulp fiber is impossible in the practical papermaking process. It could be suggested that the sizing development of AKD-sized paper is obtained by next two mechanism: 1) formation of a thin-layer of AKD on the fiber surface through melting and spreading of AKD emulsion particles by heat and 2) the hydrolysis of AKD to dialkyl ketone which has higher melting point, during drying and storage of AKD sized papers.

• 대한화학회지
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• 제37권3호
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• pp.287-293
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• 1993

n-헥산과 아세톤 용매내에서 요오드와 테트라메틸주석간의 전하이동 상호작용을 분광학적 방법으로 연구하였다. 이들의 결과로부터 일시적인 전하이동착물의 흡수 스펙트럼이 관찰되었으며, 흡수 스펙트럼의 후속적인 감소현상이 요오드에 의한 테트라메틸주석의 분해반응임을 알았다.(iododestannylation). 따라서 iododestannylation에 대한 속도상수를 온도 10, 25 및 35$^{\circ}C$, 압력을 1600 bar까지 변화시켜 가면서 측정하였으며, 이때의 반응속도상수는 온도와 압력에 따라 증가함을 알았다. 이 반응속도상수로부터 ${\Delta}V^{\neq}$, ${\Delta}{\beta}^{\neq}$, ${\Delta}H^{\neq}$ 및 ${\Delta}S^{\neq}$의 값을 얻었으며, 이들 값으로부터 전이상태의 용매구조 변화 및 메카니즘을 규명하였다. 이러한 사실로부터 본 반응은 S$_F$2 메카니즘이 지배적이며 압력이 증가함에 따라 S$_F$2의 성격이 약화됨을 알았다.