• 한국섬유공학회:학술대회논문집
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• 한국섬유공학회 2003년도 The Korea-Japan Joint Symposium
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• pp.45-46
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• 2003

A process control system has been developed for measurement and characterization of the nanofiber web qualities. The nano-fiber information system (NAFIS) developed consists of a measurement device and an analysis algorithm, which are a microscope-laser sensor fusion system and a process information system, respectively. It has been found that NAFIS is so successful in detecting irregularities of pore and diameter that the resulting product has been quitely under control even at the high production rate. Pore distribution, fiber diameter and mass uniformity have been readily measured and analyzed by integrating the non-contact measurement technology and the random function-based time domain signal/image processing algorithm. Qualifies of the nano-fiber webs have been revealed in a way that the statistical parameters for the characteristics above are calculated and stored in a certain interval along with the time-specific information. Quality matrix, scale of homogeneity is easily obtained through the easy-to-use GUI information. Finally, ANFIS has been evaluated both for the real-time measurement and analysis, and for the process monitoring.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 학술회의 논문집 정보 및 제어부문 A
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• pp.103-106
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• 2003

In this paper, we present a hybrid inertial and vision-based tracking system for VR applications. One of the most important aspects of VR (Virtual Reality) is providing a correspondence between the physical and virtual world. As a result, accurate and real-time tracking of an object's position and orientation is a prerequisite for many applications in the Virtual Environments. Pure vision-based tracking has low jitter and high accuracy but cannot guarantee real-time pose recovery under all circumstances. Pure inertial tracking has high update rates and full 6DOF recovery but lacks long-term stability due to sensor noise. In order to overcome the individual drawbacks and to build better tracking system, we introduce the fusion of vision-based and inertial tracking. Sensor fusion makes the proposal tracking system robust, fast, accurate, and low jitter and noise. Hybrid tracking is implemented with Kalman Filter that operates in a predictor-corrector manner. Combining bluetooth serial communication module gives the system a full mobility and makes the system affordable, lightweight energy-efficient. and practical. Full 6DOF recovery and the full mobility of proposal system enable the user to interact with mobile device like PDA and provide the user with natural interface.

• International Journal of Internet, Broadcasting and Communication
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• 제7권2호
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• pp.149-154
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• 2015

Biometric techniques for authentication using body parts such as a fingerprint, face, iris, voice, finger-vein and also photoplethysmography have become increasingly important in the personal security field, including door access control, finance security, electronic passport, and mobile device. Finger-vein images are now used to human identification, however, difficulties in recognizing finger-vein images are caused by capturing under various conditions, such as different temperatures and illumination, and noise in the acquisition camera. The human photoplethysmography is also important signal for human identification. In this paper To increase the recognition rate, we develop camera based identification method by combining finger vein image and photoplethysmography signal. We use a compact CMOS camera with a penetrating infrared LED light source to acquire images of finger vein and photoplethysmography signal. In addition, we suggest a simple pattern matching method to reduce the calculation time for embedded environments. The experimental results show that our simple system has good results in terms of speed and accuracy for personal identification compared to the result of only finger vein images.

• 한국진공학회지
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• 제16권4호
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• pp.235-243
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• 2007

지금 국내에서는 토카막 핵융합실험장치, 대전류 중성입자빔 실험장치 및 우주 모의실험실 같은 거대시설의 건설과 운용이 활발하다. 이런 시설의 핵심설비인 대형 진공용기는 중소형 용기에 비해 누설 가능성은 높은 반면 기체누설을 검사하는 것은 까다롭다. 중소형 용기에서 널리 사용되는 헬륨누설검사 방법을 어떻게 효율적으로 이런 대형 용기에 적용할 수 있는가 알아보기 위해, 다양한 가상적인 누설검사 시스템들을 구성하고 압력분포 및 헬륨 분압을 계산하여 주어진 장치조건에서 적절한 검사 시스템을 찾는 방법에 대해 논한다.

• 대한의용생체공학회:의공학회지
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• 제41권1호
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• pp.14-21
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• 2020

Recently, porous additive manufactured(AM) cages have been introduced to provide more desirable stiffness and may be beneficial to bone ingrowth. They are designed to attempt to reduce the subsidence problem of traditional titanium cage and to get osseointegrative property that PEEK doesn't have. This study was performed to evaluate the mechanical performance of newly developed lumbar porous AM cages. Three types of mechanical tests were performed in accordance with the ASTM standards: Static compression, compression-shear, and subsidence tests. The porous AM cages with 60% porosity showed similar device stiffness and strength as the various products submitted to FDA 510(k), and their wider contact area improved the subsidence test results by about 50%. In conclusion, the porous AM cages developed in this study were considered mechanically safe and could be an alternative to solid PEEK cages.

• 한국표면공학회지
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• 제41권1호
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• pp.12-15
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• 2008

The zinc oxide(ZnO) nanowires were deposited on Si(001) substrates by thermal chemical vapour deposition without any catalysts. SEM data suggested that the grown nanostructures were the well-aligned ZnO single crystals with preferential orientation. Back-gate ZnO nanowire field effect transistors(FET) were successfully fabricated using a photolithography process. The fabricated nanowire FET exhibits good contact between the ZnO nonowire and Au metal electrodes. Based on I-V characteristics it was found out that the ZnO nanowire revealed a characteristic of n-type field effect transistor. The drain current increases with increasing drain voltage, and the slopes of the $I_{ds}-V_{ds}$ curves are dependent on the gate voltage.

• Journal of Welding and Joining
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• 제30권3호
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• pp.32-37
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• 2012

Lead frame which has a high thermal conductivity and high mechanical strength is one of core technology for ultra-thin electronics such as LED lead frames, memory devices of semiconductors, smart phone, PDA, tablet PC, notebook PC etc. In this paper, we fabricated a Cu/STS/Cu 3-layered clad metal for lead frame packaging materials and characterized the mechanical properties and thermal conductive properties of the clad metal lead frame material. The clad metal lead frame material has a comparable thermal conductivity to typical copper alloy lead frame materials and has a reinforced mechanical tensile strength by 1.6 times to typical pure copper lead frame materials. The thermal conductivity and mechanical tensile strength of the Cu/STS/Cu clad metal are 284.35 W/m K and $52.78kg/mm^2$, respectively.

• 마이크로전자및패키징학회지
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• 제26권3호
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• pp.15-22
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• 2019

In these days, importance of the power electronic devices and modules keeps increasing due to electric vehicles and energy saving requirements. However, current silicon-based power devices showed several limitations. Therefore, wide band gap (WBG) semiconductors such as SiC, GaN, and $Ga_2O_3$ have been developed to replace the silicon power devices. WBG devices show superior performances in terms of device operation in harsh environments such as higher temperatures, voltages and switching speed than silicon-based technology. In power devices, the reliability of the devices and module package is the critically important to guarantee the normal operation and lifetime of the devices. In this paper, we reviewed the recent trends of the power devices based on WBG semiconductors as well as expected future technology. We also presented an overview of the recent package module and fabrication technologies such as direct bonded copper and active metal brazing technology. In addition, the recent heat management technologies of the power modules, which should be improved due to the increased power density in high temperature environments, are described.

• 열처리공학회지
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• 제32권6호
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• pp.270-274
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• 2019

In this study, simulation structure analysis was performed for the differential gear system for passenger cars as a prerequisite for the design of the balancing module. The differential gear system was modeled by using CATIA and simulation structure analysis was performed using ANSYS software. The material of the modeled differential gear system uses the mechanical properties of S45C (Q&T). In the structural analysis of the differential gear, the areas where the maximum stress and the maximum strain occurred can be identified. The maximum stress and maximum strain occurred in the pitch circle of the bevel gear. In evaluating the safety factor, it was found that sufficient safety factor was secured. Based on the analysis results for the differential gear, it is expected that it will be a good reference if we design the balancing module device.

• Journal of electromagnetic engineering and science
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• 제19권1호
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• pp.20-30
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• 2019

A wide-band multiple-input multiple-output (MIMO) antenna with dual-band (2.4 and 5 GHz) operation is proposed for premium indoor access points (IAPs). Typically, an omni-directional pattern is used for dipole antennas and a directional radiation pattern is used for patch antennas. In this paper, both antenna types were used to compare their performance with that of the proposed $2{\times}2$ MIMO antenna. We simulated and measured the performance of the MIMO antenna, including the isolation, envelope correlation coefficient (ECC), mean effective gain (MEG) for the IAPs, and the throughput, in order to determine its communication quality. The performance of the antennas was analyzed according to the ECC and MEG. The proposed antenna has sufficient performance and excellent characteristics, making it suitable for IAPs. We analyzed the communication performance of wireless networks using the throughput data of a typical office environment. The network throughput of an 802.11n device was used for the comparison and was conducted according to the antenna type. The results showed that the values of the ECC, MEG, and the throughput have unique characteristics in terms of their directivity, antenna gains, isolation, etc. This paper also discusses the communication performance of various aspects of MIMO in multipath situations.