• Wind and Structures
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• 제21권1호
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• pp.25-40
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• 2015

Oscillating motions of flexible cylinders are associated to some extent with the aerodynamic response of plants. Tandem motions of reeds with flexible stems in a colony are experimentally investigated using an array of flexible cylinders made of polydimethylsiloxane (PDMS). Consecutive images of flexible cylinders subjected to oncoming wind are recorded with a high-speed camera. To quantify oscillating motions, the average bending angle and displacement of flexible cylinders are evaluated using point-tracking method and spectral analysis. The tandem motions of flexible cylinders are closely related to the flow characteristics around the cylinders. Thus, the dynamic motions of a tandem arrangement of flexible cylinders are investigated with varying numbers of cylinders arranged in-line, numbers of cylinders in a group (behaving like a single body), and Reynolds numbers (Re). When the number of cylinders in a group increases, the damping effect caused by the support of downstream cylinders is pronounced. These results would be provide useful information on the tandem-arranged design of complex structures and energy harvesting devices.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
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• pp.411-411
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• 2012

Over the recent years, surface enhanced Raman spectroscopy (SERS) has dramatically grown as a label-free detecting technique with the high level of selectivity and sensitivity. Conventional SERS-active nanostructured layers have been deposited or patterned on rigid substrates such as silicon wafers and glass slides. Such devices fabricated on a flexible platform may offer additional functionalities and potential applications. For example, flexible SERS-active substrates can be integrated into microfluidic diagnostic devices with round-shaped micro-channel, which has large surface area compared to the area of flat SERS-active substrates so that we may anticipate high sensitivity in a conformable device form. We demonstrate fabrication of flexible SERS-active nanostructured substrates based on soft-lithography for simple, low-cost processing. The SERS-active nanostructured substrates are fabricated using conventional Si fabrication process and inkjet printing methods. A Si mold is patterned by photolithography with an average height of 700 nm and an average pitch of 200 nm. Polydimethylsiloxane (PDMS), a mixture of Sylgard 184 elastomer and curing agnet (wt/wt = 10:1), is poured onto the mold that is coated with trichlorosilane for separating the PDMS easily from the mold. Then, the nano-pattern is transferred to the thin PDMS substrates. The soft lithographic methods enable the SERS-active nanostructured substrates to be repeatedly replicated. Silver layer is physically deposited on the PDMS. Then, gold nanoparticle (AuNP) inks are applied on the nanostructured PDMS using inkjet printer (Dimatix DMP 2831) to deposit AuNPs on the substrates. The characteristics of SERS-active substrates are measured; topology is provided by atomic force microscope (AFM, Park Systems XE-100) and Raman spectra are collected by Raman spectroscopy (Horiba LabRAM ARAMIS Spectrometer). We anticipate that the results may open up various possibilities of applying flexible platform to highly sensitive Raman detection.

• 한국전기전자재료학회논문지
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• 제36권6호
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• pp.563-569
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• 2023

마이크로 발광다이오드(LED)는 칩 사이즈가 100마이크로미터 이하인 무기발광재료로 우수한 전기적, 광학적, 기계적 성능 때문에 유연 디스플레이, AR/VR, 바이오 메디컬 분야의 차세대 광원으로 큰 주목을 받고 있다. 특히, 바이오메디컬 분야에 적용하기 위해서는 매우 작은 크기의 마이크로 LED 칩을 원하는 유연 기판에 옮기기 위한 기술이 요구되며, 실제 인간의 얼굴, 장기 등 여러 신체 부위에 적용하기 위해서는 대량의 마이크로 LED 칩을 낮은 정밀 오차, 빠른 속도, 높은 수율로 타겟 기판에 전사하는 것이 중요하다. 본 논문의 목적은 미용/의료용 유연 마이크로 LED 디바이스 제작 공정 방법을 소개하고, 이를 실제 미용/의료 산업에 적용하기 위해 필요한 마이크로 LED 전사 기술을 소개한다. 해당 기술로 제작된 유연 마이크로 LED 디바이스는 피부 질환, 암, 신경질환 등 인간 질병 치료에 널리 활용될 것으로 기대된다.

• 전기학회논문지
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• 제65권8호
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• pp.1369-1375
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• 2016

A rapid progress of the next-generation non-volatile memory device has been made in recent years. Metal/insulator/Metal multi-layer structure resistive RAM(ReRAM) has attracted a great deal of attention because it has advantages of simple fabrication, low cost, low power consumption, and low operating voltage. This paper describes the working principle of the ReRAM device, a review of fabrication techniques, and characteristics of flexible ReRAM devices using graphene oxide as an insulating layer and ReRAM devices using multi-layered insulator. The switching characteristics of the above ReRAM devices have been compared. The oxidized graphene could be employed as an insulator of next generation ReRAM devices.

• 한국전기전자재료학회논문지
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• 제28권3호
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• pp.196-200
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• 2015

In this paper, we fabricated flexible antenna radiator using the CNT/PVDF (carbon nanotube / polyvinylidene fluoride) composite film. We used polymer film as a matrix material for the flexible devices, and introduced CNTs for adding conductivity into the film resulting in obtaining performances of the antenna radiator. Spray coating method was used to form the CNT/PVDF composite radiator, and pattern formation of the radiator was done by shadow mask during the spray coating process. We investigated the electrical properties of the CNT/PVDF composite films with the CNT concentration, and also estimated the radiator performance. Finally we discuss the feasibility of the CNT/PVDF composite radiator for the flexible antenna.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.578-578
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• 2012

Graphene, a flat one-atom-thick two-dimensional layer of carbon atoms, is considered to be a promising candidate for nanoelectronics due to its exceptional electronic properties. Most of all, future nanoelectronics such as flexible displays and artificial electronic skins require low cost manufacturing process on flexible substrate to be integrated with high resolutions on large area. The solution based printing process can be applicable on plastic substrate at low temperature and also adequate for fabrication of electronics on large-area. The combination of printed electronics and graphene has allowed for the development of a variety of flexible electronic devices. As the first step of the study, we prepared the gate electrodes by printing onto the gate dielectric layer on PET substrate. We showed the performance of graphene field-effect transistor with electrohydrodynamic (EHD) inkjet-printed Ag gate electrodes.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2009년도 춘계학술발표대회
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• pp.3.2-3.2
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• 2009

Development of printed electronics, which is occasionally referred to as 'flexible' or 'polymer' electronics, has attracted considerable world wide attention in recent years. Printed (or flexible) electronics is currently expected to represent a new form of electronics and open up wide ranging applications in displays, electron devices for medical use, sensors, and other areas. This presentation aims to provide a strategy for scalable and viable paths to accomplish flexible, printable, large area circuits displaying high performance. Novel approaches evolving from system on package (SoP) to system on flex (SoF) technology will allow the integration of heterogeneous materials platforms into a system which is needed to enhance the functionality of the system. The talk also includes speculations about areas on which future advances in printed electronics could have a substantial impact along with a brief introduction of the Korea Printed Electronics Association (KoPEA).

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2019년도 추계 학술논문 발표대회
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• pp.12-13
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• 2019

Flexible Table Form is being used more frequently at the level of formwork in construction site. However, one of the most common structural frameworks, the RC column-beam structure, is having problems in these factors. To improve this problems, this study developed support devices and proposed installation specifications to enable application of the one-way void slab method to flexible table form. It is expected that the effects of reducing the self-weight of the slab in the floor slab construction using flexible table form.

• 한국분말재료학회지
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• 제26권1호
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• pp.45-48
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• 2019

Quantum dots (QDs) are an attractive material for application in solar energy conversion devices because of their unique properties including facile band-gap tuning, a high-absorption coefficient, low-cost processing, and the potential multiple exciton generation effect. Recently, highly efficient quantum dot-sensitized solar cells (QDSCs) have been developed based on CdSe, PbS, CdS, and Cu-In-Se QDs. However, for the commercialization and wide application of these QDSCs, replacing the conventional rigid glass substrates with flexible substrates is required. Here, we demonstrate flexible CISe QDSCs based on vertically aligned $TiO_2$ nanotube (NT) electrodes. The highly uniform $TiO_2$ NT electrodes are prepared by two-step anodic oxidation. Using these flexible photoanodes and semi-transparent Pt counter electrodes, we fabricate the QDSCs and examine their photovoltaic properties. In particular, photovoltaic performances are optimized by controlling the nanostructure of $TiO_2$ NT electrodes.

• 한국재료학회지
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• 제31권3호
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• pp.132-138
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• 2021

Electrochromic devices (ECDs) have been drawing great attention due to their high color contrast, low power consumption, and memory effect, and can be used in smart windows, automatic dimming mirrors, and information display devices. As with other electronic devices such as LEDs (light emitting diodes), solar cells, and transistors, the mechanical flexibility of ECDs is one of the most important issue for their potential applications. In this paper, we report on flexible ECDs (f-ECDs) fabricated using an all-in-one EC gel, which is a mixture of electrolyte and EC material. The f-ECDs are compared with rigid ECDs (r-ECDs) on ITO glass substrate in terms of color contrast, coloration efficiency, and switching speed. It is confirmed that the f-ECDs embedding all-in-one gel show strong blue absorption and have competitive EC performance. Repetitive bending tests show a degradation of electrochromic performance, which must be improved using an optimized device fabrication process.