• Proceedings of the Korea Multimedia Society Conference
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• 2003.11a
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• pp.183-186
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• 2003

인터프레임 웨이블렛 부호화(Interframe Wavelet Coding)는 3D 서브밴드 부호화라고도 하며, 기존의 DCT 기반 동영상 부호화 방식에 비해 압축 효율이 우수하고, 특히 스케일러빌리티 기능이 뛰어난 부호화 방법이다. 본 논문에서는 기존의 인터프레임 웨이블렛 부호화 방법에서 시간 밴드 영상에 대해 동일한 웨이블렛 필터를 사용하여 공간 웨이블렛 필터를 적용하던 것을, 시간 밴드 영상의 특성을 고려하여 로우 밴드와 하이 밴드에 서로 다른 웨이블렛 필터를 적용하는 방법을 제안하였다. 본 논문에서는 로우밴드에는 9/7 필터를 적용하고 하이 밴드에는 Haar필터를 적용하여 보았다. 이렇게 적용함으로서 부호과정에서 가장 많은 연산량을 필요로하는 역 웨이블렛 변환이 간단하게 되어 복호기의 복잡도가 감소하는 효과가 있다. PSNR 실험에서 기존의 9/7 필터만을 사용하는 경우와 비교한 결과 거의 차이가 없었다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.644-647
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• 2003

Resulting from reproducibility and possibility of mass production. many researches to fabricate micro lens array using lithography have been developed. However, it still remains the level of fabricating compensation lens. Therefore, to realize the fabrication of lens having high numerical aperture can be the key technology of ultra slim optical system. Reflow phenomenon have been researched to make lens having high refractive power. And through those researches, the possibility to fabrication of high refractive power lens has been investigated. In this paper, we analyze the effect of many parameters in reflow process to get an aspheric shape with high repeatability. And we make possible to estimate shape error, through we give direct information about decrease in volume of photoresist.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.4
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• pp.94-101
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• 2003

Recently, miniaturization and weight reduction is getting more attention due to various benefits in automotive components design. It is a trend that the design of experiment(DOE) and statical design method are frequently used for optimization. In this research, the safety of lower control arm is evaluated according to its material change form S45C to A16061 for the reduction of arm's weight. The variance analysis on the basis of structure analysis and DOE is applied to the lower control m. We have proposed a statistical design model to evaluate the effect of structural modification by performing the practical multi-objective optimization considering mass, stress and deflection.

• Proceedings of the Korea Information Processing Society Conference
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• 2023.05a
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• pp.116-118
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• 2023

자율주행차가 제공하는 새로운 시장과 경쟁력, 인력 및 시간 절약, 교통 체증 문제 해결 등의 장점을 다루고, UN 사이버 보안 법률에 따른 자율주행차의 기술적인 요구사항을 준수해야 한다. 하지만 자율주행차에 대한 기술적인 요구사항을 준수하는 것으로는 모든 사이버 공격에 대해서 막을 수 없다. 자율주행차의 법적 요구사항과 사이버 보안 위협에 대처하는 방법을 다룬다. 특히 RTOS(Real Time OS)와 같은 실시간 시스템에 매우 위험할 수 있는 DRAM(Dynamic Random Access Memory)에 대한 로우해머링 공격 기법에 대해 분석하고 로우해머링에 대한 보안 방법을 제시한다. 그리고 자율 주행 시스템의 안전과 신뢰성을 보장하기 위해 하드웨어 기반 또는 소프트웨어 기반 방어 기술을 소개하고 있다.

• Proceedings of the Materials Research Society of Korea Conference
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• 2000.11a
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• pp.147-147
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• 2000

• Journal of the Microelectronics and Packaging Society
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• v.11 no.1
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• pp.1-6
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• 2004

The requirements for harsh environment electronic controllers in automotive applications have been steadily becoming more and more stringent. Electronic substrate technologists have been responding to this challenge effectively in an effort to meet the performance, reliability and cost requirements. An effect of the plasma cleaning at the ECM(Engine Control Module) alumina substrate and the intermetallic compound layer between Sn-37wt%Pb solder and pad joints after reflow soldering has been studied. Organic residual carbon layer was removed by the substrate plasma cleaning. So the interfacial adhesive strength was enhanced. As a result of AFM measurement, conductor pad roughness were increased from 304 nm to 330 nm. $Cu_6/Sn_5$ formed during initial reflow process at the interface between TiWN/Cu pad and solder grew by the succeeding reflow process, so the grains became coarse. A cellular-shaped $Ag_3Sn$ was observed at the interface between Ag-Pd conductor pad and solder. The diameters of the $Ag_3Sn$ grains ranged from about 0.1∼0.6 $\mu\textrm{m}$. And a needle-shaped was also observed at the inside of the solder.

• Journal of the Microelectronics and Packaging Society
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• v.19 no.2
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• pp.35-39
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• 2012

We studied interfacial reaction and bonding characteristics of a flip chip bonding with the viewpoint of formation behavior of intermetallic compounds. For this purpose, Sn-0.7Cu and Sn-3Cu solders were reflowed on the Al/Cu and Al/Ni UBMs. When Sn-0.7Cu was reflowed on the Al/Cu UBM, no intermetallic compounds were formed at the solder/UBM interface. The $Cu_6Sn_5$ intermetallic compounds formed by reflowing Sn-3Cu solder on the Al/Cu UBM were spalled from the interface, resulting in delamination of the solder/UBM interface. On the other hand, the $(Cu,Ni)_6Sn_5$ intermetallic compounds were formed by reflowing of Sn-0.7Cu and Sn-3Cu on the Al/Ni UBM and the interfacial bonding between the Sn-Cu solders and the Al/Ni UBM was kept stable.

• Journal of Broadcast Engineering
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• v.28 no.1
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• pp.90-99
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• 2023

In this paper, we propose a super resolution network for raw sensor image which data size is lower comparatively to RGB image. But the actual capabilities of raw image super resolution depends on color correction because its absent of camera post processing that leads to unintended result having different white balance, saturation, etc. Thus, we introduce novel color corrector attention network by adopting the idea of precedent raw super resolution research, and tune to the our faced problem from data specification. The result is not superior to former researches but shows decent output on certain performance matrix. In the same time, we encounter new challenging problem of unexpected shadowing artifact around image objects that cause performance declination despite its good result overall. This problem remains a task to be solved in the future research.

• Journal of the Microelectronics and Packaging Society
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• v.22 no.1
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• pp.69-74
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• 2015

With difficulties during the cleaning of reflow flux residues due to the decrease of the part size and interconnection pitch in the advanced electronic devices, the need for the no-clean solder paste is increasing. In this study, an epoxy curable solder paste was made with SAC305 solder powder and the curable flux of which the main ingredient is epoxy resin and its reflow solderability, flux residue corrosivity and solder joint mechanical properties was investigated with comparison to the commercial rosin type solder paste. The fillet shape of the cured product around the reflowed solder joint revealed that the curing reaction occurred following the fluxing reaction and solder joint formation. The copper plate solderability test result also revealed that the wettability of the epoxy curable solder paste was comparable to those of the commercial rosin type solder pastes. In the highly accelerated temperature and humidity test, the cured product residue of the curable solder paste showed no corrosion of copper plate. From FT-IR analysis, it was considered to be resulted from the formation of tight bond through epoxy curing reaction. Ball shear, ball pull and die shear tests revealed that the adhesive bonding was formed with the solder surface and the increase of die shear strength of about 15~40% was achieved. It was considered that the epoxy curable solder paste could contribute to the improvement of the package reliability as well as the removal of the flux residue cleaning process.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2012.11a
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• pp.123-123
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• 2012

최근 연구되고 있는 TSV(Through Silicon Via) 기술은 Si 웨이퍼 상에 직접 전기적 연결 통로인 관통홀을 형성하는 방법으로 칩간 연결거리를 최소화 할 수 있으며, 부피의 감소, 연결부 단축에 따른 빠른 신호 전달을 가능하게 한다. 이러한 TSV 기술은 최근의 초경량화와 고집적화로 대표되는 전자제품의 요구를 만족시킬 수 있는 차세대 실장법으로 기대를 모으고 있다. 한편, 납땜 재료의 주 원료인 주석은 주로 반도체 소자의 제조, 반도체 칩과 기판의 접합 및 플립 칩 (Flip Chip) 제조시의 범프 형성 등 반도체용 배선재료에 널리 사용되고 있다. 최근에는 납의 유해성 때문에 대부분의 전자제품은 무연솔더를 이용하여 제조되고 있지만, 주석을 이용한 반도체 소자가 고밀도화, 고 용량화 및 미세피치(Fine Pitch)화 되고 있기 때문에, 반도체 칩의 근방에 배치된 주석으로부터 많은 알파 방사선이 방출되어 메모리 셀의 정보를 유실시키는 소프트 에러 (Soft Error)가 발생되는 위험이 많아지고 있다. 이로 인해, 반도체 소자 및 납땜 재료의 주 원료인 주석의 고순도화가 요구되고 있으며, 특히 알파 방사선의 방출이 낮은 로우알파솔더 (Low Alpha Solder)가 요구되고 있다. 이에 따라 본 연구는 4인치 실리콘 웨이퍼상에 직경 $60{\mu}m$, 깊이 $120{\mu}m$의 비아홀을 형성하고, 비아 홀 내에 기능 박막증착 및 전해도금을 이용하여 전도성 물질인 Cu를 충전한 후 직경 $80{\mu}m$의 로우알파 Sn-1.0Ag-0.5Cu 솔더를 접합 한 후, 접합부 신뢰성 평가를 수행을 위해 고속 전단시험을 실시하였다. 비아 홀 내 미세구조와 범프의 형상 및 전단시험 후 파괴모드의 분석은 FE-SEM (Field Emission Scanning Electron Microscope)을 이용하여 관찰하였다. 연구 결과 비아의 입구 막힘이나 보이드(Void)와 같은 결함 없이 Cu를 충전하였으며, 고속전단의 경우는 전단 속도가 증가할수록 취성파괴가 증가하는 경향을 보였다. 본 연구를 통하여 전해도금을 이용한 비아 홀 내 Cu의 고속 충전 및 로우알파 솔더 볼의 범프 형성이 가능하였으며, 이로 인한 전자제품의 소프트에러의 감소가 기대된다.