• 마이크로전자및패키징학회지
• /
• 제29권3호
• /
• pp.55-61
• /
• 2022

본 연구에서는 용융온도가 중온계 무연 솔더인 Sn-3.0Ag-0.5Cu(SAC305)와 저온계 무연 솔더인 Sn-57Bi-1Ag를 사용하여 형성된 복합 무연 솔더 접합부의 특성에 대하여 보고 하였다. SAC305 솔더볼이 형성된 ball grid array(BGA) 패키지와 Sn-57Bi-1Ag 솔더 페이스트가 도포된 flame retardant-4(FR-4) 인쇄회로기판(printed circuit board, PCB)을 리플로우 솔더링 공정을 이용하여 복합 무연 솔더 접합부를 형성 하였다. 공정 온도 프로파일을 두 가지 형태로 달리하여 리플로우 솔더링 공정을 진행하였으며 리플로우 솔더링 공정 조건에 따른 계면 반응, 금속간화합물(intermetallic compound, IMC)의 형성, Bi의 확산 거동 등 복합 무연 솔더 접합부 계면 특성을 비교 분석 하였다. 또한, 열 충격 시험을 통하여 리플로우 솔더링 공정에 따른 복합 무연 솔더 접합부의 신뢰성 특성을 비교하고 열 충격 시험 전후 전단 시험을 진행하여 접합부의 기계적 특성 변화를 분석하였다.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2008년도 춘계학술대회 논문집
• /
• pp.1505-1510
• /
• 2008

A railway is a complex system integrated with a lot of technical elements such as trains, track facilities, human factors, operation & control and maintenance. As a mass transportation system, a railway could contain potential risks that may result in a high death rate and property losses. Accordingly, Railroad Safety Technology R&D Corps. is adopting the plan of the construction of Railway Safety Test Facilities as a part of the Railway Total Safety Project to enhance the railway safety, and carrying out researches on effective project management methods with Systems Engineering techniques. Recently, various systems engineering tools such as CORE or Cradle are applied to manage the system requirements and the project management process in the part of the aerospace engineering and automobile engineering so on. The railway industry also makes an effort to develop an efficient management skills using systems engineering tools as the railway system is multi-disciplinary. Therefore, we propose the more effectual management method of constructing the Railway Safety Test Facilities applying the systems engineering tool to the research.

• Ocean Systems Engineering
• /
• 제7권2호
• /
• pp.107-120
• /
• 2017

Spud-can is used for fixing jack-up rig on seabed. It needs to be inserted up to the required depth during the installation process to secure enough soil reaction and prevent overturning accidents. On the other hand, it should be extracted from seabed soils as fast as possible during the extraction process to minimize the corresponding operational cost. To achieve such goals, spud-can may be equipped with water-jetting system including monitoring and control. To develop such a smart spud-can, a reliable numerical simulation tool is essential and it has also to be validated against physical model tests. In this regard, authors developed a numerical simulation tool by using a commercial program ANSYS with extended Drucker-Prager (EDP) formula. Authors also conducted small-scale (1/100) physical model tests for verification and calibration purpose. By using the numerical model, a systematic parametric study is conducted both for sand and K(kaolin)-clay with varying important soil parameters and the best estimated soil properties of the physical test are deduced. Then, by using the selected soil properties, the numerical and experimental results for a sand/K-clay multi-layer case are cross-checked to show reasonably good agreement. The validated numerical model will be useful in the next-stage study which includes controllable water-jetting.

• 대한조선학회논문집
• /
• 제59권4호
• /
• pp.243-250
• /
• 2022

In the design stage of hull forms, a fast prediction method of resistance performance is needed. In these days, large test matrix of candidate hull forms is tested using Computational Fluid Dynamics (CFD) in order to choose the best hull form before the model test. This process requires large computing times and resources. If there is a fast and reliable prediction method for hull form performance, it can be used as the first filter before applying CFD. In this paper, we suggest the offset-based performance prediction method. The hull form geometry information is applied in the form of 2D offset (non-dimensionalized by breadth and draft), and it is studied using Convolutional Neural Network (CNN) and adapted to the model test results (Residual Resistance Coefficient; C_R). Some additional variables which are not included in the offset data such as main dimensions are merged with the offset data in the process. The present model shows better performance comparing with the simple regression models.

• 방사성폐기물학회지
• /
• 제7권3호
• /
• pp.175-182
• /
• 2009

유동층 비중차 분리기를 이용하여 혼합 폐 이온교환수지에서 폐 양이온수지와 폐 음이온수지로 분리하였으며, 원소분석과 열분석으로 분리가 잘 되었음을 확인하였다. 비중차 분리를 통해 얻은 수백 미크론의 구형 알갱이 형태의 폐 양이온수지와 폐 음이온수지 각각을 볼밀로써 24시간 습식 분쇄하여 적정 입도 이하의 입자가 균일하게 분산된 고농도 슬러리를 얻은 다음, 희석하여 $COD_{cr}$, 농도 25,000ppm의 시료를 준비하였다. 실험실 규모의 소형 초임계수산화(Super Critical Water Oxidation, SCWO) 장치(반응기 용량 : 220 mL)로써 화력발전소에서 발생한 폐 양이온수지와 폐 음이온수지에 대해 최적의 분해조건을 확립한 다음, 파일럿플랜트(반응기 용량 : 24 L)로 scale-up 실험을 수행하였다. 우선 화력발전소의 폐수지로서 파일럿테스트를 실시한 다음, 원자력발전소의 폐수지로써 파일럿테스트를 수행하여 최적의 분해조건을 설정하였다. 실험실 규모의 소형 SCWO 장치와 파일럿플랜트의 설계 및 운전에서 얻은 경험을 바탕으로 원자력발전소 내에 설치 가능한 규모로 상용설비(처리용량 : 150kg/h)를 설계 중에 있다.

• 한국전자파학회논문지
• /
• 제20권10호
• /
• pp.1077-1083
• /
• 2009

MTI(Moving Target Indicator) 방식으로 구현된 레이더에 있어서 안테나 고속 회전시 발생되는 지형 특성에 따른 고정 클러터의 도플러 주파수 스펙트럼 확산 현상에 대해 신호 처리 파라메터값(MTI 필터 단수, M/N Detector 비율, CFAR(Constant False-Alarm Ratio)의 K-factor 및 offset값)을 조정하여 지형 클러터의 제거 능력을 최적화하였다. 최적화 구현은 지형 클러터의 유형별 데이터 수집을 위한 치구를 설계 및 활용하여 유형별 지형 클러터 데이터를 수집하였으며, 이의 유형별 분석 및 제거 능력 최적화를 위해 Matlab 시뮬레이션을 통하여 test case를 만들고, 레이더 실내 시험 및 지형별 야외 시험을 통한 반복 검증을 수행하여, 진화적 개발 모델과 같이 반복, 점진적인 과정으로 병행되는 최적화를 수행하였다. 연구 결과, 기존 레이더 시스템에 비해 7.5 dB(5.6배) 이상의 지형 클러터 제거 능력 향상 효과를 거두었다.

• 한국수소및신에너지학회논문집
• /
• 제18권4호
• /
• pp.432-438
• /
• 2007

The reforming process for hydrogen production generates some impurities. Impurities in hydrogen such as $CO_2$, CO, $H_2S$, $NH_3$ affect fuel cell performance. It is well known that CO generated by the reforming process may negatively affect performance of cell, cause damage on catalysts resulting performance degradation. Hydrogen produced by reforming process includes about 2% methane. The presence of methane up to 10% is reported negligible degradation in cell performance. However, methane more than 10% in hydrogen stream had not been researched. The concentration of impurity supplied to the fuel cell was verified by gas chromatography(GC). In this study, the influence of $CH_4$ on performance of PEM fuel cell was investigated by means of current vs. potential experiment, long run(10 hr) test and electrochemical impedance measurement when the concentrations of impurities were 10%, 20% and 30%.

• 한국주조공학회지
• /
• 제28권6호
• /
• pp.256-260
• /
• 2008

The Hybrid-Lower Arm, which has been developed for reducing cost and weight, was produced by three kinds of casting methods such as the high-pressure diecasting(HPDC), the squeeze casting(SC), and the H-NCM rheocasting process. The important factors for development of the Hybrid-Lower Arm are the integral feeding in Al casting for heat treatment and the high joinning ratio between the steel part and the Al part. In this study, effects of these casting processes on the quality of Hybrid-Lower Arm were investigated. Compared with HPDC and squeeze casting, the rheocasitng process using the H-NCM slurry had some advantages in joinning different materials of Al and steel pipe without deforming the steel pipe. X-ray analysis also showed the poreless microstructure in semisolid Hybrid-Lower Arm. In the torsion stress test, semisolid Hybrid-Lower Arm was satisfied with the requirements of automobile standard.

• 공업화학
• /
• 제22권2호
• /
• pp.230-234
• /
• 2011

반도체산업은 고집적화된 회로를 요구하면서 미세 패턴을 형성하기 위해 계속해서 발전해가고 있다. 이에 반도체 산업에서 미세 패턴을 형성하기 위하여 하드마스크를 도입하여 사용되고 있다. 일반적으로 하드마스크는 화학증기증착법(CVD) 공정을 이용하여 다층구조로 제작된다. 이에 본 연구에서는 스핀공정이 가능하고 단층의 하드마스크용 조성물을 제조하기 위하여 유-무기 하이브리드 중합체를 이용하여 그 특성에 대하여 연구하였다. Silanol로 처리된 siloxane 화합물과 acetonide 그룹을 가지는 propionic acid를 에스터화 반응을 통하여 얻은 유-무기 하이브리드 중합체에 가교제 및 첨가제들의 첨가로 광학적, 열적, 그리고 표면 특성이 조절된 하드마스크 막을 제조하였다. 또한 하드마스크 막과 감광층의 식각비를 비교하여 유-무기 소재의 하이브리드 중합체에 대해 미세패턴을 형성시킬 수 있는 하드마스크 막으로써의 유용성을 확인하였다.

• 신재생에너지
• /
• 제2권2호
• /
• pp.118-125
• /
• 2006

The target of this work was the process development of demonstration plant to produce the high quality alternative fuel oil by the pyrolysis of mixed plastic waste. In the first step of research, the bench-scale units of 70 t/y and the pilot plant of 360 t/y had been developed. Main research contents in this step were the process performance test of pilot plant of 360 ton/year and the development of demonstration plant of 3,000 t/y, which was constructed at Korea R & D Company in Kimjae City. The process performance of pilot plant of 360 t/y showed about 80% yield of liquid product, which was obtained by both light gas oil(LGO) and heavy gas oil(HGO), The boiling point range distribution of LO product that was mainly consisting of olefin components in PONA group appeared at between that of commercial gasoline and kerosene. On the other hand, HO product was mainly paraffin and olefin components and also appeared at upper temperature distribution range than commercial diesel. Gas product showed a high fraction of $C_3\;and\;C_4$ product like LPG composition, but also a high fraction of $CO_2$ and CO by probably a little leak of process.