• Proceedings of the Korean Geotechical Society Conference
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• 2010.09c
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• pp.37-46
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• 2010

Marine clays are soft soil deposits having complicated mineralogy and formation characteristics. Thus, characterization of its geotechnical behavior has been a main issue for geotechnical engineers. Nowadays, the importance and applications of geophysical exploration on marine clays are increasing significantly according to the accuracy, efficiency, and reliability of geophysical survey technology. For marine clays, seismic survey is effective for density and elasticity characterization, while electro-magnetic wave provides the information about the fluid conductivity phenomena inside soil. For practical applications, elastic wave technology can evaluate the consolidation state of natural marine clay layers and estimate important geotechnical engineering parameters of artificially reclaimed marine deposits. Electrical resistivity can provide geophysical characteristics such as particle cementation, pore geometry shape, and pore material phase condition. Furthermore, nondestructive geophysical monitoring is applicable for risk management and efficiency enhancement during natural methane gas extraction from gas hydrate-bearing sediments.

• Journal of the Korean Institute of Intelligent Systems
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• v.18 no.4
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• pp.555-561
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• 2008

This Paper introduces new approach to develop fast and reliable gaits for quadruped robot using GA(genetic algorithm). Planning gaits for legged robots is a challenging task that requires optimizing parameters in a highly irregular and multidimensional space. Recent approaches have problems to select proper parameters which are not known in advance and optimize more than ten to twenty parameters simultaneously. In our approach, the effects of major gait parameters are analysed and used to guide the search more efficiently. The experiments of Sony AIBO ERS-7 in Webots environment indicate that our approach is able to produce much improved results in fast velocity and reliability.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.30 no.3
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• pp.46-52
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• 2016

When a fault occurs on a transmission line, it is important to identify the fault location as speedily as possible for improvement of the power supply reliability. Generally, distance to fault location is estimated by off line from the recorded data. Conventional fault recorder uses the fault data at one end. This paper deals with the design of an advanced fault recorder for enhancement accuracy of the fault distance estimation and fast detection a fault occurrence position. The major emphasis of the paper will be on the description of the hardware and software of the fault recorder. The fault locator algorithm utilizes a GPS time-synchronized the fault data at both ends. The fault data is transmitted to the other side substation through communication. The advanced fault locator includes a Power module, MPU(Main Processing Unit) module, ADPU(Analog Digital Processing Unit) module, and SIU(Signal Interface Unit) modules. The MMI firmware and software of an advanced fault recording device was implemented.

• Proceedings of the KIEE Conference
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• 1999.07g
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• pp.3215-3217
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• 1999

In this paper, a new structure of realizing switching control logic for Data Weighted Average Technique is suggested. It uses memory and adder for summing past binary input and this summed data is used to select one switch in control logic. This control logic acts in parallel regardless of resolution so increasing resolution don't affect on converting speed. In this reason, high speed and high resolution D/A converter based on Data Weighted Average Technique could be made. In this paper, 4 bits current mode thermometer code D/A converter is degined and simulated by using HSPICE. Simulated results show that new structure of D/A converter has more than 250MHz converting speed and less than 0.0003[LSB] INL error. It is very useful in low power circuit because of using 3.3 V supply voltage.

• Journal of Satellite, Information and Communications
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• v.6 no.2
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• pp.117-124
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• 2011

In this paper, we present more effective throughput enhancement technique to improve the data rate and reliability by using the multiple antenna technique. The conventional spatial diversity scheme is limited in according with the interference from each antenna channel status, and the orthogonality of spreading codes and subcarriers are destroyed due to the frequency selectivity. Proposed system is considered MC-CDMA system with 4 transmit antennas and 1 receive antenna. Proposed system based on SVD with the MS-RLS MMSE subcarrier combining method in order to achieve better performance with low computational complexity. Via computer simulation, we confirm that the proposed system is able to improve the BER performance by suppressing the interference of other antenna signals.

• Journal of Electrical Engineering and Technology
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• v.7 no.2
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• pp.141-150
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• 2012

The present study examines an efficient congestion management system compatible with the evolving environment. The key is to build an information model shared and exchanged for marketbased solutions to alleviate congestion. Traditional methods for congestion management can be classified into two categories, i.e., the centralized scheme and the decentralized scheme, depending on the extent to which the independent system operator (ISO) is involved in market participants' (MPs) activities. Although the centralized scheme is more appropriate for providing reliable system operation and relieving congestion in near real-time, the decentralized scheme is preferred for supporting efficient market operation. The minimum set of information between the ISO and MPs for decentralized scheme is identified: i) congestion-based zone, ii) Power Transfer Distribution Factors, and iii) transmission congestion cost. The mathematical modeling of the proposed information is expressed, considering its process of making effective use of information. Numerical analysis is conducted to demonstrate both cost minimization from the MP perspective and the reliability enhancement from the ISO perspective based on the proposed information exchange scheme.

• Journal of Electrical Engineering and Technology
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• v.9 no.3
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• pp.984-990
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• 2014

Polymers are the most commonly used di-electrics because of their reliability, availability, ease of fabrication and cost. The commercial and industrial demand for advanced polymeric materials which are capable of being used in harsh environment is need of the hour. The study of the effect of electron beam irradiation on polymeric materials is an area of rapidly increasing interest. This paper discusses the resultant beneficial effects of electron beam irradiation on the SiR-EPDM blend having 50:50 composition. The changes in mechanical and electrical properties of SiR-EPDM blend which are exposed to three different doses of electron beam radiation namely 5 Mrad, 15 Mrad and 25 Mrad are presented. The irradiated blends are analyzed for their electro-mechanical and physico chemical properties. The electrical changes induced by irradiation are investigated by arc resistance, surface resistivity and volume resistivity measurements as per ASTM standards. The mechanical changes are observed by the measurement of tensile strength and elongation at break. Physico chemical investigation has been done using the FTIR, in order to investigate the irradiation induced chemical changes.

• The KIPS Transactions:PartD
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• v.15D no.5
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• pp.699-704
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• 2008

By the dependence on Web from popularization of internet and increasing number of users, web services capability and security problem of communication is becoming a great issue. Existing web services technology decrease the capability of web application server by limiting the number of synchronous client, decreasing the processing load and increasing average response time. The encryption process to secure communication and the early expense of handshake decrease transmission speed and server capability by increasing the calculation time for connecting. Accordingly, this paper executes an encryption procedure by elliptical encryption algorithm to satisfy secure demands, improve the overload of server for web services and get reliability and security of web server architecture and proposes an improved mobile web sever which provides better ability and the techniques for deferred processing.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.127-128
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• 2007

고밀도 트렌치 게이트 전력소자 제조를 위해 HBr. He-$O_2$, $SiF_4$, $CF_4$ 등의 식각 가스를 이용하여 형성한, 트렌치 표면 거칠기 및 손상을 최소화 하여 고밀도 트렌치 게이트 전력소자를 제조하였다. 트렌치 형상 각도가 약 900일 경우 항복전압은 약 29 V인 반면, 트렌치 각도가 $88^{\circ}$일 경우 항복전압이 37V로 트렌치 형상에 따라 약 25%의 항복전압이 높아졌음을 알 수 있었다. n-채널 트렌치 게이트 전력소자의 전압-전류 측정 결과 트렌치 게이트 수가 45.000개일 때 게이트에 10 V를 인가했을 때 전류는 약 46 A로 측정되어 고밀도 트렌치 게이트 전력소자의 특성이 좋음을 알 수 있었다.

• Tribology and Lubricants
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• v.31 no.6
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• pp.239-244
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• 2015

Chemical mechanical polishing (CMP) is one of the most important processes for enabling sub-14 nm semiconductor manufacturing. Moreover, post-CMP defect control is a key process parameter for the purpose of yield enhancement and device reliability. Due to the complexity of device with sub-14 nm node structure, CMP-induced defects need to be fixed in the CMP in-situ cleaning module instead of during post ex-situ wet cleaning. Therefore, post-CMP in-situ cleaning optimization and cleaning efficiency improvement play a pivotal role in post-CMP defect control. CMP in-situ cleaning module normally consists of megasonic and brush scrubber processes. And there has been an increasing effort for the optimization of cleaning chemistry and brush scrubber cleaning in the CMP cleaning module. Although there have been many studies conducted on improving particle removal efficiency by brush cleaning, these studies do not consider the effects of brush contamination. Depending on the process condition and brush condition, brush cross contamination effects significantly influence post-CMP cleaning defects. This study investigates brush cross contamination effects in the CMP in-situ cleaning module by conducting experiments using 300mm tetraethyl orthosilicate (TEOS) blanket wafers. This study also explores brush pre-treatment in the CMP tool and proposes recipe effects, and critical process parameters for optimized CMP in-situ cleaning process through experimental results.