• 공업화학
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• 제28권6호
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• pp.691-695
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• 2017

본 연구에서는 알카라인 연료전지 환원극 가스확산층에 내열화학성이 우수한 초발수 성능을 부여하기 위하여 PDMS 코팅 공정을 최적화하였다. 성격이 상이한 두 개의 상용 가스확산층을 선택하였으며, 소재의 열적 안정성을 검토하여 코팅 온도를 최적화하고, PDMS 점도를 제어하여 코팅 균일성을 확보하고자 하였다. PDMS 전구체의 점도와 관계없이 $200^{\circ}C$ 부근에서 코팅하게 되면 모든 확산층 표면에서 높은 초발수 성능을 나타내었다. 가혹실험 조건에서 초발수 성능변화를 측정한 결과 1000 CS PDMS를 이용하여 28BC 가스확산층에 코팅한 경우가 가장 높은 내구성을 나타내었다.

• 센서학회지
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• 제17권5호
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• pp.329-337
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• 2008

Simple, small and portable oxygen sensors were fabricated by tape casting technique. Yttria stabilized zirconia containing cordierite ceramics (YSZC) were used as a porous diffused layer of oxygen in pumping cell. Yttria stabilized zirconia (YSZ) solid electrolyte, YSZC porous diffusion layer and heater-patterned ceramic sheets were prepared by co- firing method. Limit current characteristics and the linear relationship of current to oxygen concentration were observed. Viscosity variation of the slurries both YSZ and YSZC showed a similar behavior, but micro pores in the fired sheet were increased with increasing of the cordierite amount. Molecular diffusion was dominated due to the formation of large pores in porous diffusion layer. The plateau range of limit current in porous-type oxygen sensor was narrow than the one of aperture-type oxygen sensor. However limit current curve was appeared in porous-type oxygen sensor even at the lower applied voltage. The plateau range of limit-current was widen as increasing the thickness of porous diffusion layer of the YSZ containing cordierite. Measuring temperature of $600{\sim}650^{\circ}C$ was recommended for limit-current oxygen sensor. Porous diffusion layer-type oxygen sensor showed faster response than the aperture-type one and was stable up to 30 days running without any crack at interface between the layers.

• 대한수학회지
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• 제47권1호
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• pp.165-187
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• 2010

We introduce two numerical schemes for solving a system of ordinary differential equations which characterizes several kinds of linear reactions and diffusion from biochemistry, physiology, etc. The methods consist of sequential applications of the simple exact solver for a reversible reaction. We prove absolute stability and convergence of the proposed explicit methods. One is of first order and the other is of second order. Numerical results are included.

• Wind and Structures
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• 제4권6호
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• pp.469-480
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• 2001

The Leipzig Wind Profile is generally known as a typical neutral planetary boundary layer flow. But it became clear from the present research that it was not completely neutral but weakly stable. We examined whether we could simulate the Leipzig Wind Profile by using a ($k-{\varepsilon}$) turbulence model including the equation of potential temperature. By solving analytically the Second Moment Closure Model under the assumption of local equilibrium and under the condition of a stratified flow, we expressed the turbulent diffusion coefficients (both momentum and thermal) as functions of flux Richardson number. Our ($k-{\varepsilon}$) turbulence model which included the equation of potential temperature and the turbulent diffusion coefficients varying with flux Richardson number reproduced the Leipzig Wind Profile.

• Bulletin of the Korean Chemical Society
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• 제7권3호
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• pp.224-228
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• 1986

A nonlinear theory is presented for the fluctuations of intermediates in the Brusselator near the critical point caused by diffusion. The method used is the two time scaling method different from the conventional method in the sense that a slight nonlinear effect is included in the initial time region where the linear approximation is conventionally valid. The result obtained by the nonlinear theory shows that fluctuations close to the critical point approach the value of a stable steady state or deviate infinitely from an unstable steady state, as time goes to infinity, while the linear theory gives approximately time-independent fluctuations. A brief discussion is given for the correlation at a time between fluctuating intermediates when the system approaches a stable steady state.

• Journal of Electrochemical Science and Technology
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• 제12권2호
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• pp.225-229
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• 2021

Commercially available continuous glucose sensors require the operation stability for more than two weeks. Typically, the sensor comprises a sensing layer and an over-coating layer for the stable operation inside the body. In the sensing layer, enzymes and mediators are cross-linked together for the effective sensing of the glucose. The over-coating layer limits the flux of glucose and works as a biocompatible layer to the body fluids. Here, we report the simple preparation of the flux-limiting layer by the condensation of polyethyleneimine (PEI), tri-epoxide linker, and trimethylolpropane triglycidyl ether (PTGE). The sensor is constructed by a layer-by-layer drop-coating of the sensing layer containing glucose dehydrogenase and the PEI-derived blocking layer. It is stable for more than 14 days, which is enough for the sensor in the continuous monitor glucose monitoring (CGM) system.

• International Journal of Internet, Broadcasting and Communication
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• 제15권2호
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• pp.31-38
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• 2023

This paper introduces a real-time face swapping system that enables video influencers to swap their faces with arbitrary generated face images of their choice. The system is implemented as a Django-based server that uses a REST request to communicate with the generative model,specifically the pretrained stable diffusion model. Once generated, the generated image is displayed on the front page so that the influencer can decide whether to use the generated face or not, by clicking on the accept button on the front page. If they choose to use it, both their face and the generated face are sent to the landmark extraction module to extract the landmarks, which are then used to swap the faces. To minimize the fluctuation of landmarks over time that can cause instability or jitter in the output, a temporal filtering step is added. Furthermore, to increase the processing speed the system works on a reduced set of the extracted landmarks.

• International Journal of Internet, Broadcasting and Communication
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• 제15권4호
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• pp.166-171
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• 2023

With significant advancements in the field of artificial intelligence, many novel algorithms and technologies have emerged. Currently, AI painting can generate high-quality images based on textual descriptions. However, it is often challenging to control details when generating images, even with complex textual inputs. Therefore, there is a need to implement additional control mechanisms beyond textual descriptions. Based on ControlNet, this passage describes a combined utilization of various local controls (such as edge maps and depth maps) and global control within a single model. It provides a comprehensive exposition of the fundamental concepts of ControlNet, elucidating its theoretical foundation and relevant technological features. Furthermore, combining methods and applications, understanding the technical characteristics involves analyzing distinct advantages and image differences. This further explores insights into the development of image generation patterns.

• International Journal of Internet, Broadcasting and Communication
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• 제16권3호
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• pp.199-204
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• 2024

This study aims to explore the issue of character consistency in AI-generated artwork. First, the concept of character consistency is explained, including the consistency of appearance, actions, and lighting, and its importance in continuous creation and storytelling is analyzed. Next, the study examines current mainstream AI drawing tools such as MidJourney and Stable Diffusion-based WebUI and ComfyUI, evaluating their strengths and limitations in maintaining character consistency. Finally, methods to improve AI drawing technology were proposed to enhance character consistency, aiming to achieve a higher level of consistency in AI art creation.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2006년도 제33회 KOSCO SYMPOSIUM 논문집
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• pp.73-78
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• 2006

The lifted oscillating flame has been studied using experiments of inverse diffusion flames that the air jet injected into a methane background. To find out the characteristics of inverse diffusion flames, fundamentally flame stabilized diagram is investigated with various air and fuel jet velocities. It has five regions - flame extinction, stable attached flame, anchored flame, liftoff flame and blow off region. In inverse diffusion flame, lifted flames were observed near the blow off region. As long as flames lift off, flames oscillate by periods. In this oscillating lifted flame region, the frequency of 1 and under were observed in various air and methane jet velocities. Characteristics of lifted flames are also examined by using the ICCD direct image. And intensity of flame chemiluminescence is very different in rising and falling period from photographs. For the present, it is predicted that the changes of flame structure are related with flame oscillation, but more experiments will be needed to make clear the phenomenon.