• Journal of the Semiconductor & Display Technology
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• v.13 no.2
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• pp.37-44
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• 2014

In this study, the performance of dye-sensitized solar cells with different thickness of the photelectrode film was simulated by using the electron-diffusion differential model. Through this simulation, the relationships between the thickness of the photoelectrode film and the performances (open-circuit voltage, short-circuit current density, and overall photoelectric-conversion efficiency) of cells were understood and the performances with different thickness of the photoelectrede film were also examined. For considering the refractive index in the liquid electrolyte and exploring the scattering effect of titanium dioxide particles with different sizes using the Mie light-scattering theory, the highest scattering effect of each particles was found out and the optimal size of the titanium dioxide particle was determined for light scattering in the photoelectrode film of dye-sensitized solar cell. Through experiment, the mixed titanium dioxide cell was better than the single titanium dioxide cell and generated a higher overall conversion efficiency because the optimal titanium dioxide particles in the phoelectrode film as light scattering.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2018.04a
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• pp.66-66
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• 2018

Light fermentation has been conducted under different light conditions such as normal dark light, white light, and light emitting diodes (LEDs) various color (blue, green, red, white on blueberry powder with fermenting bacteria Bacillus subtilis (B2). The bacteria B2 was isolated and identified by 16S rRNA sequencing method. RYRP biologically converted to secondary metabolites through light fermentation in the presence of Bacillus subtilis, the bacteria actively involved in bioconversion process. LEDs fermentation to enhance the production of phenolic content while comparing to normal dark and white light. Among the different color LEDs, blue LEDs mediated fermentation showed higher amount of total phenolic and flavonoid content. Then blue LEDs mediated fermented compound were characterized by FTIR and GC-MS, subsequently the compound was analyzed antioxidant activity tests and the antioxidant activity exhibited higher. This is the first study to demonstrate that B. subtilis-LEDs mediated fermentation is useful for facilitating phenolic compound production and enhancing antioxidant activity, which may have greater application fermentation fields.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.20 no.1
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• pp.35-42
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• 2010

In this paper, three types of CNT/$TiO_2$ composite electrodes were prepared with different methods. The changes in XRD patterns showed that the Electrode A contained a mixed phase of anatase and rutile while the Electrode B and Electrode C contained a typical single and clear anatase crystal structure. From SEM micrographs, $TiO_2$ particles were adhered on the surface of the CNT network in the forms of small clusters. The results of chemical elemental analysis indicated that the main elements such as C, O and Ti were existed. The results demonstrated that the efficiency of photoelectrocatalytic (PEC) oxidation for methylene blue (MB) was higher than that of photocatalytic (PC) oxidation. There was a clear enhancement trend of the MB degradation using the prepared CNT/$TiO_2$ composite electrodes with an increase of applied potential. Finally, the prominent PEC activities of the CNT/$TiO_2$ composites could be attributed to combination effects of photo-degradation of $TiO_2$, electron assistant of CNT and function of applied potential.

• Bulletin of the Korean Chemical Society
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• v.34 no.2
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• pp.411-414
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• 2013

In order to enhance the photovoltaic property of the CdS/CdSe co-sensitized quantum dot sensitized solar cells (QDSSCs), the surface of nanoporous $TiO_2$ photoanode was modified by ultrathin $Al_2O_3$ layer before the deposition of quantum dots (QDs). The $Al_2O_3$ layer, dip-coated by 0.10 M Al precursor solution, exhibited the optimized performance in blocking the back-reaction of the photo-injected electrons from $TiO_2$ conduction band (CB) to polysulfide electrolyte. Transient photocurrent spectra revealed that the electron lifetime (${\tau}_e$) increased significantly by introducing the ultrathin $Al_2O_3$ layer on $TiO_2$ surface, whereas the electron diffusion coefficient ($D_e$) was not varied. As a result, the $V_{oc}$ increased from 0.487 to 0.545 V, without appreciable change in short circuit current ($J_{sc}$), thus inducing the enhancement of photovoltaic conversion efficiency (${\eta}$) from 3.01% to 3.38%.

• Proceedings of the KOSOMBE Conference
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• v.1996 no.11
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• pp.3-6
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• 1996

The Ultra-high molecular weight polyethylene (UHMWPE) is exclusivity used as the articulation component with metal or ceramic materials in artificial joint prosthesis because of its good mechanical properties. In the long term however, wear of UHMWPE causes complex problems and hence causes loosening of He prosthesis. In this study, we tried to enhance the wear property of UHMWPE by attaching a hydrophilic graft on the UHMWPE surface and by improving surface hardness without deteriorating the mechanical properties of UHMWPE. This was achieved by ion implantation and by ${\gamma}$-irradiation to the surface in acrylic acid solution and by photo-polymerization in divinylbenzen (DVB), diallysophthalate (DAIP) solution. The wear test was performed by a wear testing machine of ball-on-disk type devised by the authors. The UHMWPE with hydrophlic surface and increased surface hardness developed by above treatments showed less volumetric wear.

• Proceedings of the Korea Contents Association Conference
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• 2008.05a
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• pp.846-850
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• 2008

Technologies related to sealed-type ultrasonic sensors and driving circuit modules for them are the key elements for intelligent robot industry. Those technologies are believed to yield a drastic enhancement of the performance measuring distances in the intelligent robot systems. Modulization technologies of ultrasonic sensors are expected to develop ASIC and MEMS technologies in the future. The size of domestic market for sealed-type ultrasonic sensor modules is expected to grow to 1 billion and 5.72 billion Won by 2008 and 2012, respectively. Recent interest to service robots and government-driven programs are promoting the rapid growth of the market for the service robots. Successful application of the sealed-type ultrasonic modules to the service robots is expected to replace the conventional photo-sensors in a near future.

• Transactions on Electrical and Electronic Materials
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• v.18 no.4
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• pp.225-228
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• 2017

In this study, zinc tin oxide (ZTO) films were prepared on indium tin oxide (ITO) glasses and annealed at different temperatures under vacuum to investigate the correlation between the Ohmic/Schottky contacts, electrical properties, and bonding structures with respect to the annealing temperatures. The ZTO film annealed at $150^{\circ}C$ exhibited an amorphous structure because of the electron-hole recombination effect, and the current of the ZTO film annealed at $150^{\circ}C$ was less than that of the other films because of the potential barrier effect at the Schottky contact. The drift current as charge carriers was similar to the leakage current in a transparent thin-film device, but the diffusion current related to the Schottky barrier leads to the decrease in the leakage current. The direction of the diffusion current was opposite to that of the drift current resulting in a two-fold enhancement of the cut-off effect of leakage drift current due to the diffusion current, and improved performance of the device with the Schottky barrier. Hence, the thin film with an amorphous structure easily becomes a Schottky contact.

• Journal of the Semiconductor & Display Technology
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• v.17 no.2
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• pp.76-80
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• 2018

In recent years, with the development of automobile technology, smart system technology that assists safe driving has been developed. A camera is installed on the front and rear of the vehicle as well as on the left and right sides to detect and warn of collision risks and hazards. Beyond the technology of simple black-box recording via cameras, we are developing intelligent systems that combine various computer vision technologies. However, most related studies have been developed to optimize performance in laboratory-like environments that do not take environmental factors such as weather into account. In this paper, we propose a method to detect object by restoring visibility in image with degraded image due to weather factors such as fog. First, the image quality degradation such as fog is detected in a single image, and the image quality is improved by restoring using an intermediate value filter. Then, we used an adaptive feature extraction method that removes unnecessary elements such as noise from the improved image and uses it to recognize objects with only the necessary features. In the proposed method, it is shown that more feature points are extracted than the feature points of the region of interest in the improved image.

• Convergence Security Journal
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• v.22 no.4
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• pp.141-146
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• 2022

The iris, a biometric information, is safe, unique, and reliable, such as fingerprints, and is personal information that can significantly lower the misrecognition rate than other biometric authentication. However, due to the nature of biometric authentication, it is impossible to replace it if it is stolen. There is a case in which an actual iris photo is taken and 3d printed so that the eyes work as if they were in front of the camera. As such, there is a possibility of iris leakage through high-definition images and photos. In this paper, we propose to improve iris masking performance by supplementing iris region masking research based on existing blurring techniques. Based on the results derived in this study, it is expected that it can be used for the security of video conference programs and electronic devices.

• International Journal of Computer Science & Network Security
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• v.23 no.11
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• pp.93-98
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• 2023

Instagram is one of the fastest-growing online photo social web services where users share their life images and videos with other users. Image tagging is an essential step for developing Automatic Image Annotation (AIA) methods that are based on the learning by example paradigm. Hashtags can be used on just about any social media platform, but they're most popular on Twitter and Instagram. Using hashtags is essentially a way to group together conversations or content around a certain topic, making it easy for people to find content that interests them. Practically on average, 20% of the Instagram hashtags are related to the actual visual content of the image they accompany, i.e., they are descriptive hashtags, while there are many irrelevant hashtags, i.e., stophashtags, that are used across totally different images just for gathering clicks and for search ability enhancement. Hence in this work, Sorting instagram hashtags all the way through mass tagging using HITS (Hyperlink-Induced Topic Search) algorithm is presented. The hashtags can sorted to several groups according to Jensen-Shannon divergence between any two hashtags. This approach provides an effective and consistent way for finding pairs of Instagram images and hashtags, which lead to representative and noise-free training sets for content-based image retrieval. The HITS algorithm is first used to rank the annotators in terms of their effectiveness in the crowd tagging task and then to identify the right hashtags per image.