• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2015.05a
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• pp.31-31
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• 2015

본 연구는, TAB(Tape Automated Bonding)접속이나 Flip Chip 접속에 의한 패캐징을 실현시키기 위해, 실리콘 웨이퍼 표면에 구리 필러 및 주석 합금을 전기 도금법으로 형성하는 전기 접점용 범프에 관한 것이다. 본 연구에서는, 균일 범프 두께, 범프 표면의 균일화, 범프 내의 보이드 발생 문제 해결, 균일한 합금 조성 및 도금 속도의 고속화를 위해, Cu 도금액 및 Sn-Ag 도금액의 첨가제에 의한 표면 형상의 제어를 중심으로 그 성능에 대해 보고한다.

• Progress in Superconductivity
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• v.3 no.1
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• pp.17-22
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• 2001

Practical implementation of the SFQ technology in most application requires more than single-chip-level circuit complexity. Multiple chips have to be integrated with a technology that is reliable at cryogenic temperatures and supports an inter-chip data transmission speed of tens of GHz. In this work, we have studied two basic issues in building large RSFQ circuits. The first is the reliable inter-chip SFQ pulse transfer technique using Multi-Chip-Module (MCM) technology. By noting that the energy contained in an SFQ pulse is less than an attojoule, it is not very surprising that the direct transmission of a single SFQ pulse through MCM solder bump connectors can be difficult and an innovative technique is needed. The second is the recycling of the bias currents. Since RSFQ circuits are dc current biased the large RSFQ circuits need serial biasing to reduce the total amount of current input to the circuit.

• Journal of Power System Engineering
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• v.11 no.3
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• pp.53-58
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• 2007

The ruptured blade which is rotating at high speed can damage severely the all stage compressor blades and the turbine components. If the shattered blades flow downstream inside the turbine parts, then the turbine blades and vanes can be damaged. The small parts of shattered blades which are flowed into the turbine parts pass through without any damages in the leading edge of the first stage stationary blades. Then they bump against the convex side of the leading edge of the first stage moving blades and the trailing edge of the first stage stationary blades repeatedly. The debris of shattered blades may plug the cooling holes in the turbine blades and vanes. The dent damage and the coating delamination could be also occurred by the debris of shattered blades flowed downstream inside the combustion liner and the transition piece. This paper analyzes the influence on the turbine components and the damage mechanism and characteristics in case of the damaged blade of the multiple-stage axial flow compressor.

• Journal of Biosystems Engineering
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• v.32 no.2 s.121
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• pp.69-76
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• 2007

This study was conducted to evaluate the sideways overturning stability of side loaded mini-forwarder. The model of a prototype was developed using a 3D CAD modeler and the performance was experimentally validated. The prototype model was run on the multibody dynamic analysis program, RecurDyn 6.0, to simulate motions when the model traversed over a circular bump on a inclined ground surface. The simulation was performed at a constant forward speed of 1.85 km/h under the loaded and unloaded conditions. The forward direction was also controlled to vary from 0 to 360 degrees with an increment of 10 degrees. Results of the simulation showed safe regions in which the mini forwarder could travel safely in terms of direction and slope of the ground. Even when the mini-forwarder was loaded by 20 logs of 3.6 m long and 12 cm diameter, it traveled safely within the ground slopes of 1 to 45 degrees by directions.

• Nuclear Engineering and Technology
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• v.54 no.11
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• pp.4030-4048
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• 2022

In this study, road transportation tests were conducted with surrogate fuel assemblies under normal conditions of transport to evaluate the vibration and shock load characteristics of spent nuclear fuel (SNF). The overall test data analysis was conducted based on the measured acceleration and strain data obtained from the speed bump, lane-change, deceleration, obstacle avoidance, and circular tests. Furthermore, representative shock response spectrums and power spectral densities of each test mode were acquired. Amplification or attenuation characteristics were investigated according to the load transfer path. The load attenuated significantly as it transferred from the trailer to the cask. By contrast, the load amplified as it transferred from the cask to the surrogate SNF assembly. The fuel loading location on the cask disk assembly did not exhibit a significant influence on the strain measured from the fuel rods. The principal strain was in the vertical direction, and relatively large strain values were obtained in spans with large spacing between spacer grids. The influence of the lateral location of fuel rods was also investigated. The fuel rods located at the side exhibited relatively large strain values than those located at the center. Based on the strain data obtained from the test results, a hypothetical road transportation scenario was established. A fatigue evaluation of the SNF rod was performed based on this scenario. The evaluation results indicate that no fatigue damage occurred on the fuel rods.

• Journal of the Korea Convergence Society
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• v.8 no.11
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• pp.177-182
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• 2017

The purpose of the study is to investigate the intravenous access of paramedics in ambulance. The study consisted of confidence change in pre and post intravenous access by driving condition and speed of the vehicle. The research subjects were 30 119 paramedics (20 level 1 emergency medical technicians, 10 nurses), and 6 ambulance driving conditions were established in order to measure the number of attempts at intravenous access. The data was collected for 9 days from May 18 through May 27, 2017. The results show no disparities in number of attempts in terms of stop conditions and flat section driving conditions(p=.161) although there were significant disparities in unpaved road(p=.003), speed bump(p=.005), curve(p=.022), and slope(p=.003) section driving conditions. Confidence appeared to significantly rise(p=.000) after the experiment. In conclusion, it is recommended that swift intravenous access inside an ambulance while driving is attempted when the vehicle has come to a stop or a flat section and paramedics should maintain their confidence in intravenous access through continued training.

• Journal of the Microelectronics and Packaging Society
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• v.16 no.3
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• pp.11-17
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• 2009

The drop impact reliability comes to be important for evaluation of the life time of mobile electronic products such as cellular phone. The drop impact reliability of solder joint is generally affected by the kinds of pad and reflow number, therefore, the reliability evaluation is needed. Drop impact test proposed by JEDEC has been used as a standard method, however, which requires high cost and long time. The drop impact reliability can be indirectly evaluated by using high speed shear test of solder joints. Solder joints formed on 3 kinds of surface finishes OSP (Organic Solderability Preservation), ENIG (Electroless Nickel Immersion Gold) and ENEPIG (Electroless Nickel Electroless Palladium Immersion Gold) was investigated. The shear strength was analysed with the morphology change of intermetallic compound (IMC) layer according to reflow number. The layer thickness of IMC was increased with the increase of reflow number, which resulted in the decrease of the high speed shear strength and impact energy. The order of the high speed shear strength and impact energy was ENEPIG > ENIG > OSP after the 1st reflow, and ENEPIG > OSP > ENIG after 8th reflow.

• Korean Journal of Optics and Photonics
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• v.19 no.5
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• pp.376-380
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• 2008

This paper presents the Projection Moire method using a line scan camera. The high resolution feature of a line scan camera makes it possible to scan an image quickly, thus enabling a much quicker 3D profile. This method uses a high resolution line scan camera making it possible to scan an image at high speed simultaneously measuring the 3D profile of a large FOV. When using a high resolution scan camera, a full FOV is scanned, thus requiring just one movement of a projection grating. As a result, the number of grating movements is reduced drastically. The end result is a faster and more accurate 3D measurement. Moving the grating too quickly causes vibration in the imaging system, which will normally be required to apply a stitching technique when using an area scan camera. However the technique is not required when using a line scan camera. Compared with the previous techniques, it has the advantages of simple hardware without moving mechanical parts - single exposure for obtaining three-dimensional information. A method using a high resolution line scan camera can be used in mass production to measure the bump height of wafers or the bump height of package substrates.

• Electronics and Telecommunications Trends
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• v.35 no.4
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• pp.1-10
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• 2020

Since the 1960s, semiconductor packaging technology has developed into electrical joining techniques using lead frames or C4 bumps using tin-lead solder compositions based on traditional reflow processes. To meet the demands of a highly integrated semiconductor device, high reliability, high productivity, and an eco-friendly simplified process, packaging technology was required to use new materials and processes such as lead-free solder, epoxy-based non cleaning interconnection material, and laser based high-speed processes. For next generation semiconductor packaging, the study status of two epoxy-based interconnection materials such as fluxing and hybrid underfills along with a laser-assisted bonding process were introduced for fine pitch semiconductor applications. The fluxing underfill is a solvent-free and non-washing epoxy-based material, which combines the underfill role and fluxing function of the Surface Mounting Technology (SMT) process. The hybrid underfill is a mixture of the above fluxing underfill and lead-free solder powder. For low-heat-resistant substrate applications such as polyethylene terephthalate (PET) and high productivity, laser-assisted bonding technology is introduced with two epoxy-based underfill materials. Fluxing and hybrid underfills as next-generation semiconductor packaging materials along with laser-assisted bonding as a new process are expected to play an active role in next-generation large displays and Augmented Reality (AR) and Virtual Reality (VR) markets.

• Journal of Korea Society of Industrial Information Systems
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• v.17 no.3
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• pp.35-42
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• 2012

The database for driving patterns can be utilized in various system such as automatic driving system, driver safety system, and it can be helpful to monitor driving style. Therefore, we propose a driving pattern recognition system in which the sensor streams from a smartphone are recorded and used for recognizing driving events. In this paper we focus on the driving pattern recognition that is an essential and preliminary step of driving style recognition. We divide input sensor streams into 7 driving patterns such as, Left-turn(L), U-turn(U), Right-turn(R), Rapid-Braking(RB), Quick-Start(QS), Rapid-Acceleration (RA), Speed-Bump(SB). To classify driving patterns, first, a preprocessing step for data smoothing is followed by an event detection step. Last the detected events are classified by DTW(Dynamic Time Warping) algorithm. For assisting drivers we provide the classified pattern with the corresponding video stream which is recorded with its sensor stream. The proposed system will play an essential role in the safety driving system or driving monitoring system.