• Korean Journal of Materials Research
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• v.22 no.10
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• pp.545-551
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• 2012

In semiconductor manufacturing, the circuit integrity of packaged BGA devices is tested by measuring electrical resistance using test sockets. Test sockets have been reported to often fail earlier than the expected life-time due to high contact resistance. This has been attributed to the formation of Sn oxide films on the Au coating layer of the probe pins loaded on the socket. Similar to contact failure, and known as "fretting", this process widely occurs between two conductive surfaces due to the continual rupture and accumulation of oxide films. However, the failure mechanism at the probe pin differs from fretting. In this study, the microstructural processes and formation mechanisms of Sn oxide films developed on the probe pin surface were investigated. Failure analysis was conducted mainly by FIB-FESEM observations, along with EDX, AES, and XRD analyses. Soft and fresh Sn was found to be transferred repeatedly from the solder bump to the Au surface of the probe pins; it was then instantly oxidized to SnO. The $SnO_2$ phase is a more stable natural oxide, but SnO has been proved to grow on Sn thin film at low temperature (< $150^{\circ}C$). Further oxidation to $SnO_2$ is thought to be limited to 30%. The SnO film grew layer by layer up to 571 nm after testing of 50,500 cycles (1 nm/100 cycle). This resulted in the increase of contact resistance and thus of signal delay between the probe pin and the solder bump.

• Korean Journal of Materials Research
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• v.18 no.10
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• pp.564-570
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• 2008

Nanostructured carbon materials have been found to have applications in fuel cell electrodes, field emitters, electronic devices, sensors and electromagnetic absorbers, etc. Especially, the CNF (carbon nanofiber) can be expected to play an important role in catalyst supporters for fuel cell electrodes and chemical reactions. In this study, we synthesized CNF from a liquid phase carbon source by a solvothermal method. In addition, we studied the parameters for the preparation of CNF by controlling heating and cooling rates, synthesis temperature and time. We characterized the CNF by SEM/TEM, XRD, Raman spectroscopy and EDS. We found that the heating and cooling rate have strong effects on the CNF formation and growth. We were able to prepare the best CNF at the heating rate of $10^{\circ}$/min, at $450^{\circ}$ for 60 minutes, and at the cooling rate of $4^{\circ}$/min. As a result of Raman spectra, we found that the sample showed two characteristic Raman bands at ${\sim}1350cm^{-1}$ (D band) and ${\sim}1600cm^{-1}$ (G band). The G band indicates the original graphite feature, but the D band has been explained as a disorder feature of the carbon structure. The diameter and length of the CNF was about $15{\sim}20nm$, and over $1{\mu}$, respectively.

• Journal of the Korean Institute of Intelligent Systems
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• v.22 no.6
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• pp.780-785
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• 2012

Wind energy is currently the fastest growing source of renewable energy used for electrical generation around the world. Generally, wind turbine systems are designed to be operated for twenty years long, Therefore, various faults in the wind turbine system inevitably occur during their long term period of operation. Especially, rotor shaft, gear-box and generator are installed inside of nacelle, furthermore, some cooling systems for normal operation of these devices are also required. If these cooing systems have failed in their operation, it is impossible for the entire system to be operated normally. In this work, IR(Infra Red) camera based fault detection system for the preventive detection of various cooling systems faults is proposed. To verify the applicability of the proposed system, physical implementation is embodied and various experiments are carried out.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.3
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• pp.592-599
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• 2007

The advancement of wireless technology improves the electronic learning by combining with the mobile function, and promotes the expanded transition to the mobile learning. Basically, the mobile learning provides the usefulness in terms of tile and space to provide learners with the access to the educational contents. However, the small display device and limited memory space of mobile device is limiting the access to the learning contents simply to the text-based transmission. This paper designed and implemented the multimedia mobile learning system that reduces the size of parser by define into MSMIL composed only of needed tag to multimedia contents production in the mobile devices by using the SMIL that supports the multimedia object synchronization reduces the data of multimedia learning data and enhances the transmission efficiency by applying the macro method in creating the contents of learning. The results of implementation indicates that it simplifies the designing language, makes the language learning easy, and saves the CPU resources for the parsing by reducing the size of parser.

• Journal of Digital Convergence
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• v.17 no.11
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• pp.195-200
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• 2019

The role of the Internet of Things in the Fourth Industrial Revolution is in the era of collecting data at the end and analyzing big data through technology to analyze the future or behavior. Therefore, due to the nature of the IoT, it is vulnerable to security and requires a lightweight security protocol. The spread of things Internet technology is changing our lives a lot. IT companies all over the world are already focusing on products and services based on things Internet, and they are going to the era of all things internet that can communicate not only with electronic devices but also with common objects. People, people, people and objects, things and things interact without limitation of time and space, collecting, analyzing and applying information. Life becomes more and more smart, but on the other hand, the possibility of leakage of personal information becomes greater. Therefore, this study proposed security threats that threaten the protection of personal information and countermeasures, and suggested countermeasures for building a secure IoT environment suitable for the Fourth Industrial Revolution.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.05a
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• pp.829-832
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• 2009

Recently, IT-centered convergence between different industries has undergone rapid expansion, accompanied by major advances in u-IT development and digital convergence. Notably, in the automotive-IT convergence sector, automotive sensors and electronic devices interact closely and intelligently with each other, thereby increasing driver safety and convenience and creating the optimal driving environment. This has led to the generation of value-added for the future-oriented automotive industry. Sensing technologies - which are used to monitor traffic situations and transmit correct information (or warnings) on the road traffic situation to car drivers, and to provide accurate information to road traffic controllers - represent both the birth of high-safety, intelligent automotive technologies and the key to automotive manufacturing. In view of these developments, this paper examines the characteristics and structure of the automotive sensor industry, and outlines the policy implications for the automotive sensor industry with regard to the development of the automotive-IT convergence industry.

• Journal of Advanced Navigation Technology
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• v.23 no.5
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• pp.367-372
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• 2019

With the development of various IT technologies, data generated in the ship can be controlled through CAN communication, autonomous operation, and information provision in various situation. In addition, electronic navigation vessels with various functions have emerged, and navigation and communication equipment used in these vessels are mainly following the NMEA standard. Currently, NMEA-0183 is still mainly used, but more efficient multimedia transmission processing method is needed for multimedia transmission and USN equipment compatible using NMEA-2000 standard. Furthermore, Ethernet-based ship control is required. However, this paper proposes a multimedia transmission scheme to be smoothly linked with existing ship devices by utilizing CAN communication that can be easily used in the ship.

• Journal of the Korea Society of Computer and Information
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• v.17 no.2
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• pp.187-195
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• 2012

Smart phone allows advertisers to estimate customers behavior by selecting user context awareness information and gives users instant feed back about their behavior. Electronic equipments such as smart phone enable advertisers to advertise interesting product for each customers at the point of purchase. In this paper, we deal with the trends of Smart phone and internet based TV in the spotlight as the upcoming advertising media and propose the effective way of advertising, Smart Advertising model, which can give users advertising contents of their interesting product by collecting user context information from a variety of devices including N-screen in smart space. This model will induce modern people who live in flood of advertisements to buy products by providing interesting advertising contents.

• Journal of Advanced Navigation Technology
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• v.25 no.5
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• pp.370-376
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• 2021

development of the aerospace industry is increasing the research of projectiles. In addition, many tests are under way and many failures occur accordingly. Projectiles should be able to minimize failures because they are more dangerous than other electronic equipment. Therefore, it is necessary to verify wiring before powering the projectile. Accordingly, the wiring status was verified by resistance measurements. However, the wiring test of the previous resistance measurement method cannot be accurately measured due to devices such as capacitors and inductors in the projectile circuit. In this paper, impedance is measured in the connection state of cables and projectiles using a TDR meter. The Z-Segmentation algorithm is used to set the reference value for the measured steady state impedance. The Z-Segmentation algorithm first finds the peak values of the impedance waveform using a Kalman filter and obtains the final impedance peak segment through segmentation. In this way, the wiring status is determined based on the reference value for the normal state of the wiring.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.21 no.6
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• pp.141-145
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• 2021

Various types of memory architectures have been developed, and various compiler optimization techniques have been studied to efficiently use them. In particular, since a memory is a major component that determines performance in mobile computing devices, various optimization techniques have been developed to support them. Recently, a lot of research on hybrid type memory architecture is being conducted, so various compiler techniques are being studied to support it. Existing compiler optimization techniques can be used to achieve the required minimum performance and constraint on low power according to market requirements. References for determining the low-power effect and the degree of performance improvement using these optimization techniques are not properly provided yet. This study was conducted to provide the experimental results of the existing compiler technique as a reference for the development of multibank memory architecture.