Yong Tae Hong

This paper reviews various processes for manufacturing new type of robots termed “soft biomimetic robots.” Most robots are made of rigid metallic materials. But in recent years, various biomimetic robots based on soft materials and compliant parts have been developed. New manufacturing processes are required to fabricate these types of robots, and the processes include Shape Deposition Manufacturing (SDM) and Smart Composite Microstructures (SCM). Since the design of robots are limited by the av

Reported herein is a stretchable strain-tolerant soft printed circuit board (SPCB) following optimized circuit design rules. Inkjet-printed interconnects with a wrinkled structure and rigid epoxy patterns allow the outstanding stretchability and strain distribution controllability of the SPCB, respectively. The prototype circuits show reliable operation under various mechanical deformations, even in the 180° folding state and the irregular deformed state with 25% tensile strain. This research pa

An inkjet-printed silver electrode and a spin-coated cross-linked poly(4-vinylphenol)(PVP) dielectric layer were used as a gate electrode and a gate insulator for a bottom-gate pentacene thin-film transistor (TFT), respectively. The printing and the curing conditions of the printed silver electrode were optimized and tested on various substrates, such as glass, silicon, silicon dioxide, polyethersulfone, polyethyleneterephthalate, polyimide and polyarylate, to produce a good sheet resistance of

A trimer with thermally crosslinkable vinyl groups, (4-butyl-phenyl)-bis-[4-((4-vinyl-phenyl)-(4-butyl-phenyl)-phenyl-amine)-phenyl]-amine (3-TPA), was synthesized successfully. Differential scanning calorimetry (DSC) thermogram of 3-TPA showed two endothermic processes at 122 and 218 oC at the first heating scan. The endothermic peak at 122 oC corresponds to the melting behavior of 3-TPA and the other at 218 oC seems to be from thermal crosslinking. Thermally cured 3-TPA film at 180 oC for 1 h

We report low-operating-voltage, long-lifetime organic light-emitting diodes (OLEDs) with a molybdenum-oxide (MoO3)-doped N,N'-di(1-naphthyl)-N,N'-diphenylbenzidine (α-NPD) layer between the indium tin oxide and the α-NPD. The current density-voltage-luminance characteristics and the lifetime were studied for various MoO3 doping concentrations and thicknesses. The devices with α-NPD layers of various MoO3 doping concentrations and thicknesses exhibited lower driving voltage and higher power effi

We report the channel current variation and the bias stress behavior of hydrogenated amorphous silicon thin-film transistors (a-Si:H TFTs) that have wavy-edge source/drain (S/D) electrodes. Edge waviness of electrodes can be often observed in printed narrow lines. Wavy edges of the S/D electrodes were intentionally patterned by using photolithography to implement edge waviness of the printed electrodes. Based on the measured data, we found that the peak-to-peak magnitude of the S/D wavy edge was

This paper reports the resistance change of conductive carbon nanotube (CNT) thin-films according to the temperature variation. Resistance of conductive CNT thin-films intrinsically has good thermal sensitivity, but shows environmental dependency. In order to reduce environmental effects, we spin-coated polydimethylsiloxane (PDMS) on the conductive CNT thin-films. We observed that conductive CNT thin-films with a PDMS encapsulation layer showed little environmental dependency, but more linear an

본 논문은 플렉시블 디스플레이용 stainless steel(SS) 기판의 평탄막 재료로서 유기 및 유기/무기 하이브리드 에폭시 레진을 연구한 첫 결과를 보고한다. 유기 에폭시로는 diglycidyl ether of bisphenol A(DGEBA)를, 하이브리드 에폭시는 실세스퀴옥산이 포함된 octa(dimethylsiloxypropylglycidylether) silsesquioxane(OG)를 선택하였다. 경화제로는 diaminodiphenylmethane(DDM)을 에폭시와 1：2 당량비로 사용하였으며 두 물질 모두 SS 기판위에 어려움 없이 코팅이 되었다. TGA로 살펴본 열 안정성 분석은 순수한 물질이나 경화된 필름이나 모두 OG가 DGEBA 보다 안정하며 AFM에 의한 필름 표면의 관찰은 필름이 충분히 두꺼운 경우(> 1μm) 1∼2 nm 정도의 표면 거칠기 값을 갖는 평탄한 면이 얻어진다는 것을 보여주었다. 또 이 필름들은 0~10000 초에 걸치는 시간 동안 100

We report, for the first time, operation frequency dependence of current density-voltage (JOLEDVOLED)shift for multi-layer organic light-emitting diodes (OLEDs). When the OLEDs were electrically stressed for 21 hours with 50% duty voltage pulses at 60, 120, 240, and 360 Hz, the JOLED-VOLED shifts were suppressed by half for 360 Hz operation compared with 60 Hz operation, but with little change in emission efficiencies. This frequency dependent JOLED-VOLED shift is believed to be commonly observe

Flexible pressure sensors can be applied to human–machine interfaces, next-generation touch interfaces for wearable displays, and real-time blood pressure monitoring. For these applications, pressure sensors must have high pressure sensitivity, flexibility, stability, and tunable sensitivity, like the human skin. Reported in this paper is a highly sensitive and flexible pressure sensor with tunable sensitivity. Silver-nanowires-embedded Polydimethylsiloxane (PDMS), the elastomeric nanowire compo

In this paper, a plasma-assisted patterning method for the organic layers of organic light-emitting diodes (OLEDs) and its effect on the OLED performances are reported. Oxygen plasma was used to etch the organic layers, using the top electrode consisting of lithium fluoride and aluminum as an etching mask. Although the current flow at low voltages increased for the etched OLEDs, there was no significant degradation of the OLED efficiency and lifetime in comparison with the conventional OLEDs. Th

The solution-processed gallium-doped zinc oxide (GZO) layer was used as an anode-flattening photonic-crystal (PC) underlayer to enhance the light outcoupling of polymer light-emitting diodes (PLEDs). A corrugated PC surface was directly coated with GZO, which acted as a planarization layer as well as an anode. The PLEDs with the PC-embedded GZO anode showed higher efficiencies and an effective areal light emission when several PLEDs were formed in an array format.