• Journal of Power Electronics
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• v.18 no.3
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• pp.662-671
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• 2018

This paper presents a new structure for a step up dc-dc converter, which has several advantageous features. Firstly, the input dc source and the clamped capacitor are connected in series to transfer energy to the load through dual voltage multiplier cells. Therefore, the proposed converter can produce a very high voltage and a high conversion efficiency. Secondly, a double voltage clamped circuit is introduced to the primary side of the coupled inductor. The energy of the leakage inductance of the coupled inductor is recycled and the inrush current problem of the clamped circuits can be shared equally by two synchronous clamped capacitors. Therefore, the voltage spike of the switch tube is solved and the current stress of the diode is reduced. Thirdly, dual voltage multiplier cells can absorb the leakage inductance energy of the secondary side of the coupled inductor to obtain a higher efficiency. Fourthly, the active switch turns on at almost zero current and the reverse-recovery problem of the diodes is alleviated due to the leakage inductance, which further improves the conversion efficiency. The operating principles and a steady-state analysis of the continuous, discontinuous and boundary conduction modes are discussed in detail. Finally, the validity of this topology is confirmed by experimental results.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.4
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• pp.418-425
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• 2014

This paper presents a Ku-Band Doppler Radar System to measure respiration and heart rate. It was measured by using simultaneous radar and ECG(Electrocardiogram). Arctangent demodulation without dc offset compensation can be applied to transmitted I/Q(In-phase & Quadrature-phase) signal in order to improve the RMSE(Root Mean Square Error) about 50 %. The power leaked to receiving antenna from the transmitting antenna is always generated because of continuously opening the transceiver of CW(Continuous Wave) Doppler radar. As the output power increase, leakage power has an effect on the SNR(Signal-to-Noise Ratio) of the system. Therefore, in this paper, leakage cancellation technique that adds the signal having the opposite phase of the leakage power to the leakage power was implemented in order to minimize the decline of receiver sensitivity. By applying the leakage cancellation techniques described above, it is possible to measure the heart rate and respiration of the human at a distance of up to 35 m. the heart rate of the measured data at a distance of 35 m accords with the heart rate extracted from the ECG data.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.48 no.2
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• pp.14-19
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• 2011

We have fabricated GaN Schottky barrier diode (SBD) for high-voltage applications on Si substrate. The leakage current and the electrical characteristics of GaN SBD are investigated by annealing metal-semiconductor junctions. Ohmic junctions of Ti/Al/Mo/Au and Schottky junctions of Ni/Au are used in the fabrication. A test structure is proposed to measured buffer leakage current through a mesa structure. When annealing temperature is increased from $700^{\circ}C$ to $800^{\circ}C$, measured buffer leakage current is also increased from 87 nA to 780 nA at the width of 100 ${\mu}m$. The diffusion of Au, Ti, Mo, O into GaN buffer layer increases the leakage current and that is verified by Auger electron spectroscopy. Experimental results show that the low leakage current and the high breakdown voltage of GaN SBD are achieved by annealing metal-semiconductor junctions.

• Journal of Korea Society of Digital Industry and Information Management
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• v.13 no.1
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• pp.37-48
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• 2017

As the risk of technical leakage is increasing, technology protection support systems for small and medium-sized businesses have gained attention. This paper analyzed the perception gap of the user and policy-maker regarding technology protection support systems. First, to identify key elements of technology protection support systems and construct measurement factors, interviews with experts are conducted. Then, surveys are conducted to analyze the perception differences between the users and policy-makers. Factor analysis and ANOVA have been utilized to analyze survey results. The result shows that the perception gaps exist in the following areas: management system, cost reduction, copyright protection, customer satisfaction, leakage prevention, and awareness. To enhance the effectiveness of technology protection support systems, this paper suggests technology protection support systems should be customized in terms of the company's size and type of busines.

• Journal of Digital Convergence
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• v.20 no.4
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• pp.377-388
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• 2022

Metaverse, realistic virtual space technology has become a hot topic. However, due to the lack of an institutional system to the metaverse environment, concerns are rising over the leakage of industrial confidentiality, including digital assets produced, stored, processed, and transferred within the metaverse. Digital forensics, a technology to defend against hacking attacks in cyberspace, cannot be used in metaverse space, and there is no basis for calculating the extent of damage and tracking responsibility, making it difficult to respond to human resources leakage and cyberhacking effectively. In this paper, we define the scope of industrial confidentiality information and leakage scenario and propose policy and institutional measures based on problems in each metaverse scenario. As a result of the study, it was necessary to prepare a standardized law on Extra-territorial search and seizure issues and a system for collecting cryptocurrency evidence to respond to industrial confidentiality leaks in the metaverse. The study expects to contribute to industrial technology development by preparing in advance for problems that may arise in metaverse technology.

• Journal of Ocean Engineering and Technology
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• v.27 no.3
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• pp.85-90
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• 2013

The growing need for energy (oil and gas) has led to offshore resource development. As a reflection of this trend, there have been many advances in the technologies used for the subsea production systems that make offshore resource development possible. As the technologies for subsea production systems continue to grow, a subsea X-mas tree, the core equipment in a subsea production system, is required to have more functions than before. Generally, these complex functions lead to a change in its configuration. Therefore, this paper investigates a change in a subsea X-mas tree system to enhance system understanding, and conducts a leakage path analysis of a subsea X-mas tree system. Utilizing the recent configuration of the subsea X-mas tree, an identification of the leakage path and a quantitative risk analysis for the leakage using an FTA (fault tree analysis) are conducted.

• Journal of Convergence for Information Technology
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• v.7 no.1
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• pp.25-33
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• 2017

In order to prevent information leakage, companies are monitoring the information leakage by internal staff by building individual security system and integrated monitoring system of firewall and DLP function. Especially, many log data of the integrated monitoring system cause time and money, and it is difficult to detect information leak of fast malicious personnel due to system slowdown. It is necessary to speed up the system by digitizing large log data for each day and person for fast information leakage detection and there is a need to develop and manage a continuous monitoring program for the information leakage indications personnel. Therefore, we propose an improved integrated monitoring system using log data by date and individual data.

• Journal of Advanced Marine Engineering and Technology
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• v.35 no.3
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• pp.329-334
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• 2011

The cooling water circulation plates had been used to drop the temperature of refractory outside shell of common cooling system by using cooling plate or stave type. When they are attacked by surrounding gas, they are corroded and the water flows in the refractory due to leakage of water. So, the life of refractory material is shortened and changed due to the worse conditions of cooling system. The automatic sensing device for water leakage of cooling plate is developed to check the position of trouble by using the microprocessor system when cooling water leak and gas are flowed into the cooling plate through the leakage position. The flowed gas is detected in the micro-process system which delivers the detected position of cooling plate or stave to main control room through the wireless-radio relay station. This system can be possible to detect the position of cooling plate or stave against the water leakage part immediately and then deliver the signal to main control room by using the microprocessor system and wireless-radio relay station. This system will be developed in changing the working condition from manual system to unmanned auto alarm system.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.7
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• pp.741-748
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• 2013

A conventional packing ring was designed with a large clearance to prevent damage due to the vibration of the rotor, which can lead to an increase in steam leakage. In this study, a flexible packing ring using winding springs was developed to prevent damage to the rotor teeth by minimizing vibration, while maintaining a smaller clearance than that of conventional rotor designs. Theoretical analysis and finite element analysis (FEA) were used to design the winding spring to satisfy the specified allowable stress limit and minimum load requirements. The shape of the winding spring was designed by applying curves to the center and end parts of a flat spring. Computational fluid dynamics (CFD) analysis was used to predict the leakage of the flexible packing ring. Flow rate measurement tests were performed to verify the leakage reduction efficiency and the reliability of the CFD analysis.

• Tribology and Lubricants
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• v.24 no.6
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• pp.285-290
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• 2008

The purpose of this paper is to present the case study of tribological failure analysis on the gear damages, oil leakage, and sealant sealing in a manual transmission of front engine and front wheel drive vehicle. The manual transmission is to change the speed range and direction of the engines depending on the driving conditions by friction driving forces with input and output gear system. The material property and surface roughness of the gears are strongly related to the gear noise and micro-vibration, oil leakage and wear, which may decrease the real contact area of the gear and the strength of the oil film thickness between the driving gear and driven one. The O-ring damage of speedometer driven gear and bad sealant sealing of oil pan may produce oil leakage through the contact surfaces, which cause the oil shortage and seizure on the sliding surfaces of the transaxle gears. In the failure case study, the proper repair working and good lubrication are very important for the long life of the transaxle without any tribological failures and oil leakage.