• Journal of the Microelectronics and Packaging Society
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• v.6 no.4
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• pp.61-71
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• 1999

The recent trend toward higher frequencies, miniaturization and lower-cost in wireless communication equipment is demanding high density packaging technologies such flip chip interconnection and multichip module(MCM) as a substitute of conventional plastic package. With analyzing the recently reported research results of the RF flip chip, this paper presents the technical issues and advantages of RF flip chip and suggest the flip chip technologies suitable for the development stage. At first, most of RF flip chips are designed in a coplanar waveguide line instead of microstrip in order to achieve better electrical performance and to avoid the interaction with a substrate. Secondly, eliminating wafer back-side grinding, via formation, and back-side metallization enables the manufacturing cost to be reduced. Finally, the electrical performance of flip chip bonding is much better than that of plastic package and the flip chip interconnection is more suitable for Transmit/Receiver modules at higher frequency. However, the characterization of CPW designed RF flip chip must be thoroughly studied and the Au stud bump bonding shall be suggested at the earlier stage of RF flip chip development.

• Journal of Biomedical Engineering Research
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• v.21 no.4
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• pp.339-344
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• 2000

The mucociliary system is one of the most important airway defense mechanisms in human body and impairment of ciliary movement results in various diseases in respiratory tract. In this study, we have developed a system that can measure ciliary movement in vivo and quantified ciliary beat frequency (CBF) through autoregressive (AR) power spectrum. To measure the frequency in vivo, we applied a photoelectric method that was composed of a laser light and a fiber optic probe. Scattered signals are transferred to a PC in which they are displayed on the monitor and its CBF is determined by the AR method in were acquired. For 8 normal subjects, the analyzed CBFs ranged from 5 to 10Hz and its mean was 7.3${\pm}$1.1Hz. This result showed similar aspects to the reported results of CBFs to data. We expect that this result will be applied in various clinical studies such as analysis of CBF changes by drugs or by diseaes.

• Journal of Practical Engineering Education
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• v.9 no.1
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• pp.7-13
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• 2017

This study will provide a practical plan of engineering education through the study of major activities connected with the production of works to accomplish the graduation conditions by completing the comprehensive design subject and the result of the performance. The designed subject is to measure the minimum safety distance during driving using the obstacle detection function of the ultrasonic sensor and to perform the avoidance algorithm based on the measurement value of the acceleration gyro sensor. It is proposed an access surveillance system that minimizes the damage of drones, surrounding objects, and people, and improves air mobility. Experimental results show that the obstacles around the drone are detected by five ultrasonic sensors and the difference of output value is applied to each motor of the drone and obstacle avoidance is confirmed. In addition, the content and level of the data for measuring the achievement of learning achievement in the engineering education certification program were used and the results were confirmed to be consistent with the description of the engineering problem level required for the graduates of 4-year engineering college.

• Journal of Advanced Navigation Technology
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• v.26 no.2
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• pp.85-90
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• 2022

In this study, in order to test the performance of the aircraft system, a threat signal simulator that can transmit a signal similar to the actual threat to the aircraft under test with high power was designed. The high-power threat signal simulator should be able to transmit broadband (UHF band, L band, S band, X band) communication signals and radar signals, and control to transmit signals accurately directed to the aircraft through interfacing tracking radar. The signal strength of the developed equipment is 63 dBm to 93 dBm or more depending on type of signal, and the tracking precision is less than 0.1 degree, which satisfies the required performance. And it was confirmed that the antenna of the high-power threat signal simulator can accurately direct the signal to the aircraft position through the tracking radar interfacing.

• Journal of the Institute of Convergence Signal Processing
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• v.23 no.1
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• pp.44-49
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• 2022

Abstract Recently, with the development of IoT technology and communication media, various video equipment is being used in industrial fields. Image data acquired from cameras and sensors are easily affected by noise during transmission and reception, and noise removal is essential as it greatly affects system reliability. In this paper, we propose a weight filter algorithm based on the pixel value distribution pattern to preserve details in the process of restoring images damaged in AWGN. The proposed algorithm calculates weights according to the pixel value distribution pattern of the image and restores the image by applying a filtering mask. In order to analyze the noise removal performance of the proposed algorithm, it was simulated using enlarged image and PSNR compared to the existing method. The proposed algorithm preserves important characteristics of the image and shows the performance of efficiently removing noise compared to the existing method.

• Journal of Advanced Navigation Technology
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• v.27 no.3
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• pp.300-305
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• 2023

In this paper, we confirmed that an efficient sensor network can be established at a low cost by applying Geofencing technology to a LoRa-based sensor network and verified its effectiveness in disaster management such as forest fires. We detected changes through GPS, gyro sensors, and combustion detection sensors, and defined the validity size of the Geofencing cell accurately. We proposed a LoRa Payload Frame Structure that has a flexible size according to the size of the sensor information.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2022.11a
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• pp.388-389
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• 2022

Recently, AI (Artificial Intelligence) has been applied to various technologies such as automatic driving, robot and smart communication. Currently, AI system is developed by software-based method using tensor flow, and GPU (Graphic Processing Unit) is employed for processing unit. However, if software-based method employing GPU is used for AI applications, there is a problem that we can not change the internal circuit of processing unit. In this method, if high-level jobs are required for AI system, we need high-performance GPU, therefore, we have to change GPU or graphic card to perform the jobs. In this work, we developed a CNN-based FPGA (Field Programmable Gate Array) chip to solve this problem.

• Journal of Software Assessment and Valuation
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• v.15 no.2
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• pp.101-109
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• 2019

Lasers for optical broadband communication systems should have excellent frequency selectivity and modal stability. DFB(Distributed Feedback) lasers have low lasing frequency shift during high speed current modulation. In this paper, I have developed a simulation software and analysed threshold gain and lasing frequency of a lasing mode in longitudinal direction of an 1.55um DFB laser with two mirrors and without anti-reflection coatings, that have both an index- and gain-gratings. The grating phase on a left mirror face is fixed as π/2 and the grating phase on a right mirror face is varied. As the phases of the index and gain gratings on the right mirror facet are π and 0, κL should be in the range of 2~6 in order to enhance the frequency stability. In order to reduce the threshold current of a lasing mode, κL should be greater than 8, regardless of the grating phases on the mirror faces.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.13 no.3
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• pp.127-133
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• 2013

As an essential part of current industrial society, electric power energy is contantaly increasing in pace with the development of science and technology. In order to meet the demand of electric power, power facilities which take care of the higher voltage and bigger capacity is required. To produce and supply electric power on a sound basis the electric facilities should operate with reliability. To prevent disasters in advance, the high quality facilities should be manufactured, and a constant management should be done. When the power facilities cause accidents, the result is huge national deficits. Since the power facilities play a pivotal role in the key industry of national infrastructures of they should operate for a long time in maintaining a stable state, and the accidents can be prevented in advance. The lifetime of a power cable is considered to be 30 years at the time of manufacture, but in real fields, accidents of cable occur 8-12 years from the start of operation, resulting in a heavy loss of properties. In this paper, we will show that we have found out the cause and process of the deterioration of 22kV cable systems in operation. The result is that the process of deterioration does not follow the Weibull distribution only ; but rather, after the heat deterioration the Weibull distributed deterioration comes, then the cable is destroyed due to the partial discharge resulting from the Weibull distributed deterioration.

• The Journal of the Korea Contents Association
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• v.9 no.8
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• pp.64-72
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• 2009

AMR(Automatic Meter Reading), which means that it reads the meter of electricity, gas, or water, etc at a remote place automatically through wired or wireless communication, has been studied in terms of Power Line Communication method and Local Area Wireless Communication method, etc. In this paper, we designed and implemented JCA(Java Card for AMR) capable of AMR, which is based on java Card technology indispensable to the ubiquitous world. In this paper, JCA follows standard transactional procedures offered by power supply company and manages power usage log and billing data, and is designed in order to satisfy EMV multi-functional specifications. Because JCA is a multi-functional smart card capable of post-issuance applets as an open platform, it is installed into other applications of affiliated concerns as well as credit card and traffic card applications. Not only the proposed JCA is a low cost system, compared to other AMR systems, but is capable of paying rates in advance or later by applying authentication and security function of java Card. In addition the proposed JCA system can create value added services such as affiliated services with corporate alliance.