• 한국CDE학회논문집
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• 제16권5호
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• pp.380-389
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• 2011

Esthetic appeal of a product is often affected by the appearance quality of seams forming between components of the product. The appearance quality of seams is, however, assessed in a very subjective and qualitative manner that heavily depends on the evaluator. This paper presents a preliminary study to quantify such assessment by formulating a quantitative index which is a linear function of the seam gap sizes, seam gap ranges, and the size uniformity of seam gaps. By considering a highly simplified problem of a drawer system and utilizing subjective assessments by twenty evaluators, the index has been formulated. The validity of this index has been confirmed by observing its behavior with changes of the component tolerances. Also, the utility of this index has been demonstrated through a selective assembly scheme applied to the drawer system problem. Though the index formulated in this study for seam appearance quality may be useful, future studies are necessary to make the model readily applicable to real problems.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2011년도 춘계학술발표대회
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• pp.6.2-6.2
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• 2011

Block copolymer (BCP) self-assembly in a film geometry has recently been the focus of increased research interest due to their potential use as templates and scaffolds for the fabrication of nanostructured materials. The phase behavior in a thin film geometry that confines polymer chains to the interfaces will be influenced by the interfacial interactions at substrate/polymer and polymer/air and the commensurability between the equilibrium period (L0) of the BCP and the total film thickness. We investigated the phase transitions for the films of block copolymers (BCPs) on the modified surface, like the order-to-disorder transition (ODT) by in-situ grazing incidence small angle x-ray scattering (GISAXS) and transmission electron microscopy (TEM). The selective interactions on the surface by a PS-grafted substrate provide the preferential interactions with the PS component of the block, while a random copolymer (PS-r-PMMA) grafted substrate do the balanced interfacial interactions on the surface. The thickness dependence of order-to-disorder behavior for BCP films will be discussed in terms of the surface interactions.

• Biotechnology and Bioprocess Engineering:BBE
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• 제6권6호
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• pp.419-425
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• 2001

A dense pellicular solid matrix has been fabricated by coating 4% agarose gel on to dense zironia-silica(ZS) spheres by watr-in-oil emulsification . The agarose evenly laminated the ZS bead to a depth of 30㎛, and the resultin gpellicular assembly was characterised by densities up to 2.39g/mL and a mean particle dimeter of 136 ㎛. In comparative fluidisation tests, the pellicular solid phase exhibited a two-fold greater flow velocity than commercial benchmark ad-sorbents necessary to achieve common values of bed expansion. Furthermore, the perlicular parti-cles were characterised by improved qualities of chromatographic behaviour, particularly with re-spect to a three-fold increase in the apparent effective diffusivity of lysozyme within a pellicular assembly modified with Cibacron Blue 3GA. The properties of rapid protein adsorption/desorp-tion were attributed to the physical design and pellicular deployment of the reactive surface in the solid phase. When combined with enhanced feedstock throughput, such practical advantages recommend the pellicular assembly as a base matrix for the selective recovery of protein products from complex, particulate feedstocks(whole fermentation broths, cell disruptates and biological extracts).

• Advances in Computational Design
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• 제4권1호
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• pp.43-52
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• 2019

Variation Analysis (VA) is used to simulate final product variation, taking into consideration part manufacturing and assembly variations. In VA, all the manufacturing and assembly processes are defined at the product design stage. Process Capability Data Bases (PCDB) provide information about measured variation from previous products and processes and allow the designer to apply this to the new product. A new challenge to this traditional approach is posed by the Industry 4.0 (I4.0) revolution, where Smart Manufacturing (SM) is applied. The manufacturing intelligence and adaptability characteristics of SM make present PCDBs obsolete. Current tolerance analysis methods, which are made for discrete assembly products, are also challenged. This paper discusses the differences expected in future factories relevant to VA, and the approaches required to meet this challenge. Current processes are mapped using I4.0 philosophy and gaps are analysed for potential approaches for tolerance analysis tools. Matching points of simulation capability and I4.0 intents are identified as opportunities. Applying conditional variations, incorporating levels of adjustability, and the un-suitability of present Monte Carlo simulation due to changed mass production characteristics, are considered as major challenges. Opportunities including predicting residual stresses in the final product and linking them to product deterioration, calculating non-dimensional performances and extending simulations for process manufactured products, such as drugs, food products etc. are additional winning aspects for next generation VA tools.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.267-267
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• 2013

Band engineering of a nanowire is related to the question what is the minimum size of a nanowire-based device. At the subnanometer scale, there has been a long standing problem whether it is possible to both control an energy band of an isolated nanowire by a dopant and measure it using angle-resolved photoemission spectroscopy (ARPES). This is because an extra atom in the subnanometer wire plays as a defect rather than a dopant and it is challenging to assemble isolated subnanometer wires into an array for an ARPES measurement. We demonstrate that only one of multiple metallic subnanometer wires canbe controlled electronically by a dopant maintaining the whole metallic bands of other wires, which was observed directly by ARPES. Here,the multiple metallic subnanometer wires were produced on a stepped Si(111) surface by a self-assembly method. The selective band engineering proves that the selectively-controlled metallic wire is nearly isolated electronically from other metallic wires and an electronic structure controlcan be realized down to subnanometer scale.

• Bulletin of the Korean Chemical Society
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• 제30권11호
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• pp.2759-2761
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• 2009

• 한국정보전자통신기술학회논문지
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• 제8권1호
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• pp.37-44
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• 2015

본 논문에서 전계효과 트랜지스터 (field effect transistor; FET) 제작을 위한 표면 프로그램된 aminopropylethoxysilane(APTES)와 1-octadecyltrichlorosilane(OTS) 패턴을 이용하여 단일벽 탄소 나노튜브(single-walled carbon nanotube; SWCNT)를 실리콘 기판 위에 선택적으로 흡착시키는 공정방법을 제안하였다. 양성 표면 분자 패턴을 만들기 위해 형성된 APTES 패턴은 많은 양의 SWCNT의 흡착을 위해 제작되었고, OTS 만을 이용한 공정보다 효과적인 SWCNT 흡착이 가능하다. 산화막(silicon dioxide)이 형성된 실리콘 기판 위에 사진공정(photolithography process)을 이용하여 임의의 감광액(photoresist; PR) 패턴이 형성되었다. PR 패턴이 형성된 기판은 헥산 용매를 이용하여 1:500 (v/v)로 희석된 OTS 용액 속에 담가진다. OTS 박막이 표면 전체에 만들어지고, PR 패턴이 제거되는 과정에서 PR 위에 형성되었던 OTS 박막도 같이 제거되어, 선택적으로 형성된 OTS 박막 패턴을 얻을 수 있다. 이 기판은 다시 에탄올 용매를 이용하여 희석된 APTES 용액 속에 담가진다. APTES 박막은 OTS 박막 패턴이 없는 노출된 산화막 위에 형성된다. 마지막으로 이처럼 APTES와 OTS에 의해 표면 프로그램된 기판은 SWCNT가 분산된 다이클로로벤젠(dichlorobenzene) 용액 속에 담가진다. 결과적으로 SWCNT는 양 극성을 띠는(positive charged) APTES 박막 패턴 위에만 흡착된다. 반면 중성O TS 박막 패턴 위에는흡착되지 않는다. 이러한 표면 프로그램 방법을 사용하여 SWCNT는 원하는 영역에 자기 조립시킬 수 있다. 우리는 이 방법을 이용하여 소오스와 드레인 전극사이에 SWCNT가 멀티 채널로 구성된 다중채널 FET를 성공적으로 제작하였다.

• 전기전자학회논문지
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• 제27권4호
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• pp.610-616
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• 2023

본 논문에서는 Robot Operating System(ROS) 기반의 모바일 매니퓰레이터(Manipulator)를 이용한 무인 배송 로봇 시스템을 구현하고 시스템 구현을 위해 사용된 기술에 대해 소개한다. 로봇은 엘리베이터를 이용해 건물 내부에서 자율주행이 가능한 모바일 로봇과 진공 펌프를 부착한 Selective Compliance Assembly Robot Arm(SCARA)-Type의 매니퓰레이터로 구성된다. 로봇은 매니퓰레이터에 부착된 카메라를 이용하여 이미지 분할과 모서리 검출을 통해 배송물을 들어올리기 위한 위치와 자세를 결정할 수 있다. 제안된 시스템은 스마트폰 앱 및 ROS와 연동된 웹서버를 통해 배송 현황을 조회하고 로봇의 실시간 위치를 파악할 수 있도록 사용자 인터페이스를 가지고 있으며, You Only Look Once(YOLO)와 Optical Character Recognition(OCR)을 통해 배송 스테이션에서 배송물과 주소지를 인식한다. 아울러 4층 건물 내부에서 진행한 배송 실험을 통해 시스템의 유효성을 검증하였다.

• 한국산업보건학회지
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• 제25권4호
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• pp.472-481
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• 2015

Objectives: Welding is a major task in shipbuilding yards that generates welding fumes. A significant amount of welding in shipbuilding yards is done on steel. Inevitably, manganese is present in the base metals being joined and the filler wire being used and, consequently, in the fumes to which workers are exposed. The objective of this work was to characterize manganese exposure associated with work area, total and particle size-selective mass concentration, and compare the mass concentrations obtained using a three-piece cassette sampler, size-selective impactor sampler and blood manganese concentrations. Materials: All samples were collected from the main work areas at one shipbuilding yard. We used a three piece cassette sampler and the eight stage cascade impactor sampler for the airborne manganese mass concentration of total and all size fractions, respectively. In addition, we used the results of health examination of workers sampled for airborne manganese. Results: The oder of high concentration of airborne manganese in shipbuilding processes was as follows; block assembly, block erection, outfitting installation, steel cutting, and outfitting preparation. The percentages of samples that exceeded the OES of the ministry of employment and labor by the cassette sampling method was 12.5%, however 59.1% of sampled workers by the impactor sampling method exceeded the TLV of the ACGIH. Conclusions: Even though the manganese concentrations in blood of workers exposed to higher airborne manganese concentration were higher than among those exposed to lower concentrations, there was no difference in blood manganese concentrations among work duration. The data analyzed here by characterizing size-selective mass concentrations indicates that the inhaled manganese of welders in shipbuilding yards could be mostly manganese-containing respirable particle sizes.

• 대한기계학회논문집A
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• 제39권7호
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• pp.653-657
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• 2015

표면확산계수의 활성화를 통한 실리콘-게르마늄(silicon-germanium) 양자점의 성장을 수치해석적으로 구현하였다. 실리콘 기판 위에 증착된 실리콘-게르마늄 박막의 성장을 표현하는 비선형 지배방정식을 유도하였으며, 확산계수를 온도의 함수로 고려하여 표면확산계수의 국소적 향상이 미치는 효과를 살펴보았다. 해석결과는 안정상태의 박막이 섭동될 때에 양자점이 자기조립되는 과정을 보여주며, 박막표면의 국소부위에 선택적으로 구조물이 성장하는 현상을 나타낸다. 본 연구는 바텀업(bottom-up) 방식이 내재적으로 지닌 불규칙성을 해결할 대안을 마련하여 양자기기를 위한 공정개발의 방향을 제시한다.