• 대한전자공학회논문지SD
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• 제47권5호
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• pp.31-40
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• 2010

본 논문에서는 IEEE 802.11n 무선 랜 표준용 LDPC 복호기 프로세서를 설계하였다. 설계된 프로세서는 IEEE 802.11n 표준의 블록길이 1,944와 부호화율 1/2의 패리티 검사 행렬을 지원하며, 하드웨어 감소를 위해 최소합 알고리듬과 layered 구조를 적용하였다. 최소합 알고리듬의 특징을 이용한 검사노드 메모리 최소화 방법을 고안하여 적용하였으며, 이를 통해 기존방법의 메모리 크기의 25%만을 사용하여 구현하였다. 설계된 프로세서를 $0.35-{\mu}m$ CMOS 셀 라이브러리로 합성한 결과, 200,400 게이트와 19,400 비트의 메모리로 구현되었으며, 80 MHz@2.5V로 동작하여 약 135 Mbps의 성능을 갖는다. 설계된 회로는 FPGA 구현을 통해 하드웨어 동작 검증과 복호성능을 분석하였으며, 이를 통해 설계된 LDPC 복호기의 유용성을 입증하였다.

• 마이크로전자및패키징학회지
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• 제20권4호
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• pp.53-58
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• 2013

An innovative packaging solution, Flip Chip with Copper (Cu) Column bond on lead (BOL) Enhanced Process (fcCuBE$^{(R)}$) delivers a cost effective, high performance packaging solution over typical bond on capture pad (BOC) technology. These advantages include improved routing efficiency on the substrate top layer thus allowing conversion functionality; furthermore, package cost is lowered by means of reduced substrate layer count and removal of solder on pad (SOP). On the other hand, as electronic packaging technology develops to meet the miniaturization trend from consumer demand, reliability testing will become an important issue in advanced technology area. In particular, electromigration (EM) of flip chip bumps is an increasing reliability concern in the manufacturing of integrated circuit (IC) components and electronic systems. This paper presents the results on EM characteristics on BOL and BOC structures under electrical current stressing in order to investigate the comparison between two different typed structures. EM data was collected for over 7000 hours under accelerated conditions (temperatures: $125^{\circ}C$, $135^{\circ}C$, and $150^{\circ}C$ and stress current: 300 mA, 400 mA, and 500 mA). All samples have been tested without any failures, however, we attempted to find morphologies induced by EM effects through cross-sectional analysis and investigated the interfacial reaction characteristics between BOL and BOC structures under current stressing. EM damage was observed at the solder joint of BOC structure but the BOL structure did not show any damage from the effects of EM. The EM data indicates that the fcCuBE$^{(R)}$ BOL Cu column bump provides a significantly better EM reliability.

• 한국건설순환자원학회논문집
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• 제1권3호
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• pp.233-239
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• 2013

콘크리트의 표면보호제은 표면으로부터 함침제를 함침시켜 표층부의 개질을 목적으로 사용하며 주로 Silane계 및 Silicate계 재료가 사용된다. 일반적으로 이용되는 Silicate는 Sodium과 Lithium silicate이며 탄산화한 부분의 알칼리 부여와 성능저하가 예상되는 콘크리트 부재의 구체 강화 등 성능회복을 목적으로 사용한다. 본 연구에서는 Self-Cleaning 실리케이트계 콘크리트 표면보호제로서 TEOS, $TiO_2$, Lithium silicate를 사용하여 노출 및 컬러 콘크리트 등의 고기능성이 요구되는 건축물에 적용이 가능한 Self-Cleaning 실리케이트계 콘크리트 표면보호제를 제조하였다. 또한 제조된 표면보호제의 건축물 적용을 위한 표면접촉각, 방오성능, 표면특성 및 조직관찰 등의 성능을 검토하였다. 실험결과 Self-Cleaning 실리케이트계 콘크리트 표면보호제를 적용한 시험체는 접촉각 $20^{\circ}$ 이하의 친수성을 보였고 기능성 부여가 가능하므로 표면보호제로서 사용이 가능하다.

• 대한전자공학회논문지SD
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• 제41권12호
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• pp.13-19
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• 2004

반도체 또는 평판디스플레이 제조에 있어 노광공정 후의 PR(photo-resist) 제거 공정으로서 기존의 황산기반 용액을 대체하는 고농도 오존 수 생성 기술에 대한 연구를 수행하였다. 세라믹 연면방전구조의 오존발생장치를 개발하여, 0.5［ℓ/min］의 산소 유량에서 최대 12［wt%］이상의 오존가스 농도를 얻었으며, 이를 고농도로 물과 혼합하기 위한 고효율 오존접촉장치를 개발하였다. 오존 수 생성 실험 결과, 오존가스 10［wt%］에서 80［ppm］이상의 오존 수 농도를 달성하였으며, 70［ppm］의 오존 수에서 PR 제거율 147［nm/min］의 양호한 결과를 얻었다.

• The Journal of Advanced Prosthodontics
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• 제9권6호
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• pp.423-431
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• 2017

PURPOSE. The goal of this study was to evaluate the fracture resistances of various monolithic crowns fabricated by computer-aided design and computer-aided manufacturing (CAD/CAM) with different thickness. MATERIALS AND METHODS. Test dies were fabricated as mandibular molar forms with occlusal reductions using CAD/CAM. With different occlusal thickness (1.0 or 1.5 mm), a polymer-infiltrated ceramic network (Enamic, EN), and zirconia-reinforced lithium silicate (Suprinity, SU and Celtra-Duo, CD) were used to fabricate molar crowns. Lithium disilicate (e.max CAD, EM) crowns (occlusal: 1.5 mm) were fabricated as control. Seventy crowns (n=10 per group) were bonded to abutments and stored in water for 24 hours. A universal testing machine was used to apply load to crown until fracture. The fractured specimens were examined with a scanning electron microscopy. RESULTS. The type of ceramics and the occlusal thickness showed a significant interaction. With a recommended thickness (1.5 mm), the SU revealed the mean load similar to the EM, higher compared with those of the EN and CD. The fracture loads in a reduced thickness (1.0 mm) were similar among the SU, CD, and EN. The mean fracture load of the SU and CD enhanced significantly when the occlusal thickness increased, whereas that of the EN did not. CONCLUSION. The fracture loads of monolithic crowns were differently influenced by the changes in occlusal thickness, depending on the type of ceramics. Within the limitations of this study, all the tested crowns withstood the physiological masticatory loads both at the recommended and reduced occlusal thickness.

• The Journal of Advanced Prosthodontics
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• 제10권4호
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• pp.300-307
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• 2018

PURPOSE. To investigate the fatigue and fracture resistance of computer-aided design and computer-aided manufacturing (CAD/CAM) ceramic molar crowns on dental implants and human teeth. MATERIALS AND METHODS. Molar crowns (n=48; n=8/group) were fabricated of a lithium-disilicate-strengthened lithium aluminosilicate glass ceramic (N). Surfaces were polished (P) or glazed (G). Crowns were tested on human teeth (T) and implant-abutment analogues (I) simulating a chairside (C, crown bonded to abutment) or labside (L, screw channel) procedure for implant groups. Polished/glazed lithium disilicate (E) crowns (n=16) served as reference. Combined thermal cycling and mechanical loading (TC: $3000{\times}5^{\circ}C/3000{\times}55^{\circ}C$; ML: $1.2{\time}10^6$ cycles, 50 N) with antagonistic human molars (groups T) and steatite spheres (groups I) was performed under a chewing simulator. TCML crowns were then analyzed for failures (optical microscopy, SEM) and fracture force was determined. Data were statistically analyzed (Kolmogorow-Smirnov, one-way-ANOVA, post-hoc Bonferroni, ${\alpha}=.05$). RESULTS. All crowns survived TCML and showed small traces of wear. In human teeth groups, fracture forces of N crowns varied between $1214{\pm}293N$ (NPT) and $1324{\pm}498N$ (NGT), differing significantly ($P{\leq}.003$) from the polished reference EPT ($2044{\pm}302N$). Fracture forces in implant groups varied between $934{\pm}154N$ (NGI_L) and $1782{\pm}153N$ (NPI_C), providing higher values for the respective chairside crowns. Differences between polishing and glazing were not significant ($P{\geq}.066$) between crowns of identical materials and abutment support. CONCLUSION. Fracture resistance was influenced by the ceramic material, and partly by the tooth or implant situation and the clinical procedure (chairside/labside). Type of surface finish (polishing/glazing) had no significant influence. Clinical survival of the new glass ceramic may be comparable to lithium disilicate.

• The Journal of Advanced Prosthodontics
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• 제10권4호
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• pp.328-334
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• 2018

PURPOSE. To evaluate the reproducibility of scan-based abutments using a blue light model scanner. MATERIALS AND METHODS. A wax cast abutment die was fabricated, and a silicone impression was prepared using a silicone material. Nine study dies were constructed using the prepared duplicable silicone, and the first was used as a reference. These dies were classified into three groups and scanned using a blue light model scanner. The first three-dimensional (3D) data set was obtained by scanning eight dies separately in the first group. The second 3D data set was acquired when four dies were placed together in the scanner and scanned twice in the second group. Finally, the third 3D data set was obtained when eight dies were placed together in the scanner and scanned once. These data were then used to define the data value using third-dimension software. All the data were then analyzed using the non-parametric Kruskal-Wallis H test (${\alpha}=.05$) and the post-hoc Mann-Whitney U-test with Bonferroni's correction (${\alpha}=.017$). RESULTS. The means and standard deviations of the eight dies together were larger than those of the four dies together and of the individual die. Moreover, significant differences were observed among the three groups (P<.05). CONCLUSION. With larger numbers of abutments scanned together, the scan becomes more inaccurate and loses reproducibility. Therefore, scans of smaller numbers of abutments are recommended to ensure better results.

• Composites Research
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• 제25권6호
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• pp.178-185
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• 2012

본 연구에서는 기능성 나노복합재를 제작하는 방법이 제시되었다. 미소 입자들을 포함하고 있는 점성을 가진 유체에 전기장을 가하여 유체속에 포함된 입자들을 전기장의 방향에 따라 규칙적으로 배열을 하였다. FAiMTa 기술이라고 불리는 이 방법은 마이크로 혹은 나노 사이즈의 입자들을 체인의 형태로 배열하여 직교이방성 폴리머 나노복합재의 제작을 가능하게 하였다. 알루미나($Al_2O_3$), 탄소나노튜브(CNT), 탄소(Graphite), 텅스텐(W) 등의 마이크로 혹은 나노 사이즈 입자 분말을 사용하여 FAiMTa기술의 유효성을 확인하는 시험을 수행하였다. 이러한 입자들을 전기장을 사용하여 일정한 방향으로 배열하여 직교이방성 폴리머 복합재를 만들었고, 시험시편의 물리적 특성 즉 기계적 열적 특성을 측정하여 방향성을 확인하였다. 이렇게 제작된 첨단 나노복합재는 각종 산업분야에서 큰 효과가 기대된다.

• Journal of Advanced Marine Engineering and Technology
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• 제28권3호
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• pp.551-558
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• 2004

Recently, fuel prices have been continually raised in diesel engine. Such a change in the fuel price influences enormously the development trend of marine diesel engines for slow speed, In other words, the focus was shifted from large diameter and high speed to low fuel consumption. Accordingly, more efforts are being made for engine manufacturing and development to develop highly efficient engines. In this study. a single cylinder 4 stroke cycle DI slow speed diesel engine was designed and manufactured, a 4 stroke cycle was configured and basic performances were evaluated. The results are as follows. The optimal fuel injection timing had the lowest value when specific fuel consumption was in BTDC 8~$10^{\circ}$, a little more delayed compared to high speed diesel engines. Cycle variation of engines showed about 5% difference at full loads. This is a significantly small value compared to the cycle variation in which stable operation is possible, showing the high stability of engine operation is good. The torque and brake thermal efficiency of engine increased with an increase of engine 250-450 rpm. but fuel consumption ratio increased from the 450 rpm zone and thermal efficiency abruptly decreased. Mechanical efficiency was maximally 70% at a 400 rpm that was lower than normal engines according to the increase of mechanical frictional loss for cross head part. The purpose of this study was to get more practical engines by comparing the above results with those of slow speed 2 stroke cycle diesel engines.

• Journal of Advanced Marine Engineering and Technology
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• 제38권9호
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• pp.1075-1080
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• 2014

본 연구는 5MW급 해상풍력 하부구조물개발에 있어 설계에 필요한 다양한 해양환경 조건에 대하여 높은 안정성 확보가 요구되는 해상용 풍력발전 하부구조물과 관련, 구조물의 설계방법을 제시하고 그 안정성을 고찰하여 관련 기술 분야에 기여함을 목표로 한다. 특히, 5MW급 해상풍력발전 시스템에 대해 시험영역에서 큰 바람의 방향이 지속되고 있는 동안에 동시에 발달된 파도의 계산에 대한 정보를 제공한다. 그러므로 바람의 영역과 접근하는 파동 행열간의 관련성을 검토하여 강도, 방향 그리고 시간의 이동성을 계산할 수 있음을 확인하였다. 쇄파에서의 국부적인 압력분포를 물리적인 모델링과 수치적 모델링을 통해 조사하는 것이 가능하다. 해상 풍력 에너지 변환장치의 지지구조물들에 대해 최근 적용된 구조 및 피로에 대한 평가는 일반 설계규칙에 근거했다. 5MW 해상풍력 하부구조물은 제약조건이 많아 단일구조로 취급하는데 이는 생산에서 높은 안전계수를 고려해야함을 의미한다.