• Journal of the Korean Institute of Telematics and Electronics B
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• v.33B no.1
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• pp.57-66
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• 1996

In this paper, a new biotelemetry system for a transcutaneous data communication between an implanted artificial heart with a control system and an external human-interfaced management system has been developed. A radio telemetry using radio frequency is a commonly used method in the conventional telemetry systems. But, it is not suitable for the medical applications because of not only an interference due to a radio broadcasting but also a harmfulness to the human body. In this paper, therefore, a new biotelemetry system applied to an artificial heart has been developed with the results of the recent research for an optical telemetry system based on the infrared light transmission with good skin permeability. The performance of the biotelemetry system developed has been assessed through mock circulatory experiments, and the clinical applicability has been also confirmed with the successful results in the animal experiments.

• Applied Chemistry for Engineering
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• v.27 no.5
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• pp.483-489
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• 2016

Here, we examined the photo-degradation efficiency of $Cu_2Se$-graphene nanocomposites synthesized by a facile and fast microwave-assisted technique. The prepared composites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, XPS and UV-Vis spectrophotometry. The photocatalytic performance was studied through the decomposition of Rhodamine (Rh B) as a standard dye under visible light radiation. A 95% of Rh B degradation after visible light irradiation for 180 min indicates that the $Cu_2Se$-graphene composite exhibited significant photodegradation efficiency. Therefore, it can be concluded that the synthesized $Cu_2Se$-graphene can be used as a suitable catalyst for decomposing dye pollutants.

• Journal of Korea Multimedia Society
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• v.11 no.4
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• pp.492-503
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• 2008

With the recent development and increasing importance of personal identification systems, biometric technologies with less risk of loss or unauthorized use are being popularized rapidly. In particular, because of their high identification rate and convenience, fingerprint identification systems are being used much more commonly than other biometric systems such as iris recognition, face recognition and vein pattern recognition. However, a fingerprint identification system has the problem that artificially forged finger-prints can be used as input data. Thus, in order to solve this problem, the present study proposed a method for detecting forged fingerprints by measuring the degree of attenuation when the light from an optical fingerprint sensor passes through the finger and analyzing changes in the transmission of light over stages at fixed intervals. In order to prove improvement in the performance of the proposed system, we conducted an experiment that compared the system with an existing multi-sensor recognition system that measures also the temperature of fingerprint. According to the results of the experiment, the proposed system improved the forged fingerprint detection rate by around 32.6% and this suggests the possibility of solving the security problem in fingerprint identification systems.

• Journal of Advanced Navigation Technology
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• v.27 no.5
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• pp.610-620
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• 2023

The interest in the aircraft interior market is gradually growing due to technological development based on the 4th industrial revolution and competition for airlines to attract customers, and as part of that, Cabin Display System (CDS) for FAA Part.25 civil aircraft is being developed in Korea. The CDS is a system that provides various multimedia services to passengers by utilizing Flexible and Transparent Organic Light Emitting Diodes (OLED) with Integrated Display Processing Module (IDPM). This paper presents a new method for efficient Data Load Process of large-sized files and deals with their implementation and performance. The results of this study are expected to be applied to Data Load Process development of avionics that require reliable large-capacity file transmission along with reducing the costs of development compared to existing ARINC-615A.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.95-95
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• 2014

An OLED(Organic Light-Emitting Diode) device based on the emissive electroluminescent layer a film of organic materials. OLED is used for many electronic devices such as TV, mobile phones, handheld games consoles. ULVAC's mass production systems are indispensable to the manufacturing of OLED device. ULVAC is a manufacturer and worldwide supplier of equipment and vacuum systems for the OLED, LCD, Semiconductor, Electronics, Optical device and related high technology industries. The SMD Series are single-substrate sputtering systems for deposition of films such as metal films and TCO (Transparent Conductive Oxide) films. ULVAC has delivered a large number of these systems not only Organic Evaporating systems but also LTPS CVD systems. The most important technology of thin-film encapsulation (TFE) is preventing moisture($H_2O$) and oxygen permeation into flexible OLED devices. As a polymer substrate does not offer the same barrier performance as glass substrate, the TFE should be developed on both the bottom and top side of the device layers for sufficient lifetimes. This report provides a review of promising thin-film barrier technologies as well as the WVTR(Water Vapor Transmission Rate) properties. Multilayer thin-film deposition technology of organic and inorganic layer is very effective method for increasing barrier performance of OLED device. Gases and water in the organic evaporating system is having a strong influence as impurities to OLED device. CRYO pump is one of the very useful vacuum components to reduce above impurities. There for CRYO pump is faster than conventional TMP exhaust velocity of gases and water. So, we suggest new method to make a good vacuum condition which is CRYO Trap addition on OLED evaporator. Alignment accuracy is one of the key technologies to perform high resolution OLED device. In order to reduce vibration characteristic of CRYO pump, ULVAC has developed low vibration CRYO pumps to achieve high resolution alignment performance between Metal mask and substrate. This report also includes ULVAC's approach for these issues.

• Korean Journal of Materials Research
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• v.23 no.11
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• pp.655-660
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• 2013

Photoelectrochemical cells have been used in photolysis of water to generate hydrogen as a clean energy source. A high efficiency electrode for photoelectrochemical cell systems was realized using a ZnO hierarchical nanostructure. A ZnO nanofiber mat structure was fabricated by electrospinning of Zn solution on the substrate, followed by oxidation; on this substrate, hydrothermal synthesis of ZnO nanorods on the ZnO nanofibers was carried out to form a ZnO hierarchical structure. The thickness of the nanofiber mat and the thermal annealing temperature were determined as the parameters for optimization. The morphology of the structures was examined by field-emission scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. The performance of the ZnO nanofiber mat and the potential of the ZnO hierarchical structures as photoelectrochemical cell electrodes were evaluated by measurement of the photoelectron conversion efficiencies under UV light. The highest photoconversion efficiency observed was 63 % with a ZnO hierarchical structure annealed at $400^{\circ}C$ in air. The morphology and the crystalline quality of the electrode materials greatly influenced the electrode performance. Therefore, the combination of the two fabrication methods, electrospinning and hydrothermal synthesis, was successfully applied to fabricate a high performance photoelectrochemical cell electrode.

• Journal of the Korean Solar Energy Society
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• v.33 no.2
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• pp.35-41
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• 2013

Dye-sensitized solar cell (DSC) allows light transmission and the application of various colors that make it especially suitable for building-integrated PV (BIPV) application. In order to apply DSC module into windows, it has to be panelized: DSC module should be protected with reinforced glass to the entire surface. Up to date, it seems to be common to make double glazing with DSC modules with air gaps between the glasses and the DSC modules. Few research has been conducted on the characteristics of various glazing types with DSC modules. This study aims to analyze the electrical performance of DSC modules according to panelizing method for glazing unit with DSC modules. The prototype of the DSC glazing that applied silicone filler between DSC modules and glasses was developed. The electrical performances of this type of DSC glazing with the filler and rather conventional double glazing with DSC modules were compared. Their performances were measured using a solar simulator that is suitable for DSC performance testing. The results indicated that the electrical performance of the filler type DSC glazing improved by 7% compared to that of the conventional DSC double glazing type.

• Journal of Environmental Science International
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• v.29 no.1
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• pp.95-108
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• 2020

Silver nanoparticles were loaded onto g-C₃N₄ (CN) with a nanoroll-type morphology (Ag/CN) synthesized using a co-polymerization method for highly selective conversion of toxic nitrobenzene to industrially-valuable aminobenzene. Scanning electron microscopy and high-resolution transmission electron microscopy (HRTEM) images of Ag/CN revealed the generation of the nanoroll-type morphology of CN. Additionally, HRTEM analysis provided direct evidence of the generation of a Schottky barrier between Ag and CN in the Ag/CN nanohybrid. Photoluminescence analysis and photocurrent measurements suggested that the introduction of Ag into CN could minimize charge recombination rates, enhancing the mobility of electrons and holes to the surface of the photocatalyst. Compared to pristine CN, Ag/CN displayed much higher ability in the photocatalytic reduction of nitrobenzene to aminobenzene, underscoring the importance of Ag deposition on CN. The enhanced photocatalytic performance and photocurrent generation were primarily ascribed to the Schottky junction formed at the Ag/CN interface, greater visible-light absorption efficiency, and improved charge separation associated with the nanoroll morphology of CN. Ag would act as an electron sink/trapping center, enhancing the charge separation, and also serve as a good co-catalyst. Overall, the synergistic effects of these features of Ag/CN improved the photocatalytic conversion of nitrobenzene to aminobenzene.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.2
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• pp.123-130
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• 2008

A 3D structure production method for microstereolithography is a useful way that produces complex structures with flexible processes and low cost. Several UV curable resins were blended and the optimal resin for micro-lens fabricate was selected through viscosity, workability and transmission tests. It consists of 1, 6 - Hexanediol diacrylate with 15 Apha and Isobornyl acrylate for reducing some shrinkage. When fabricating a micro-lens array on large surface, some distortion of shape occurred because of the surface tension between cured part. To overcome this problem, the optimal processing conditions were derived from considering amount of the resin and surface tension. Large surface Micro-lens array, which are a type of elliptical convex and consist of 18,000 micro-lens in the range of 2cm*2cm were fabricated. The focal length to the X-axis and Y-axis were calculated. To verify the performance, measure an energy distribution of transmitted light from the Large surface Micro-lens array.

• Smart Structures and Systems
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• v.8 no.5
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• pp.471-486
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• 2011

Various types of strain sensors have been developed and widely used in the field for monitoring the mechanical deformation of structures. However, conventional strain sensors are not suited for measuring large strains associated with impact damage and local crack propagation. In addition, strain sensors are resistive-type transducers, which mean that the sensors require an external electrical or power source. In this study, a gold nanoparticle (GNP)-based polymer composite is proposed for large strain sensing. Fabrication of the composites relies on a novel and simple in situ GNP reduction technique that is performed directly within the elastomeric poly(dimethyl siloxane) (PDMS) matrix. First, the reducing and stabilizing capacities of PDMS constituents and mixtures are evaluated via visual observation, ultraviolet-visible (UV-Vis) spectroscopy, and transmission electron microscopy. The large strain sensing capacity of the GNP-PDMS thin film is then validated by correlating changes in thin film optical properties (e.g., maximum UV-Vis light absorption) with applied tensile strains. Also, the composite's strain sensing performance (e.g., sensitivity and sensing range) is also characterized with respect to gold chloride concentrations within the PDMS mixture.