• Journal of Mechanical Science and Technology
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• v.20 no.1
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• pp.1-12
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• 2006

This work reviews the effects of catalyst formulation and exhaust gas composition on soot oxidation in CDPF (Catalytic Diesel Particulate Filter). DOC's (Diesel Oxidation Catalysts) have been loaded with Pt catalyst (Pt/$Al_{2}O_3$) for reduction of HC and CO. Recent CDPF's are coated with the Pt catalyst as well as additives like Mo, V, Ce, Co, Fe, La, Au, or Zr for the promotion of soot oxidation. Alkali (K, Na, Cs, Li) doping of metal catalyst tends to increase the activity of the catalysts in soot combustion. Effects of coexistence components are very important in the catalytic reaction of the soot. The soot oxidation rate of a few catalysts are improved by water vapor and NOx in the ambient. There are only a few reports available on the mechanism of the PM (particulate matter) oxidation on the catalysts. The mechanism of PM oxidation in the catalytic systems that meet new emission regulations of diesel engines has yet to be investigated. Future research will focus on catalysts that can not only oxidize PM at low temperature, but also reduce NOx, continuously self-cleaning diesel particulate filters, and selective catalysts for NOx reduction.

• Korean Journal of Materials Research
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• v.30 no.6
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• pp.279-284
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• 2020

In this work, a carbon-doped carbon nitride photocatalyst is successfully synthesized through a simple centrifugal spinning method after heat treatment. The morphology and properties of the prepared photo catalyst are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-vis spectrophotometer (UV-vis), and specific surface area. The results show that the band gap of the prepared sample, g-CN-10 is 2.1 eV, is significantly lower than that of pure carbon nitride, 2.7 eV. As the amount of cotton candy increased, the absorption capacity of the prepared catalyst for visible light is significantly enhanced. In addition, the degradation efficiency of Rhodamine B (RhB) by sample g-CN-10 is 98.8 % over 2 h, which is twice that value of pure carbon nitride. The enhancement of photocatalytic ability is attributed to the increase of specific surface area after the carbon doping modifies carbon nitride. A possible photocatalytic degradation mechanism of carbon-doped carbon nitride is also suggested.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.11
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• pp.896-900
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• 2010

Electrical properties of organic light-emitting diodes were studied in a device with 7,7,8,8-tetracyano-quinodimethane (TCNQ) to see how the TCNQ affects on the device performance. Since the TCNQ has a high electron affinity, it is used for a charge-transport and injection layer. We have made a reference device in a structure of ITO(170 nm)/TPD(40 nm)/$Alq_3$(60 nm)/LiF(0.5 nm)/Al(100 nm). And two types of devices were manufactured. One type of device is the one made by doping 5 and 10 vol% of TCNQ to N,N'-diphenyl-N,N'-di(m-tolyl)-benzidine (TPD) layer. And the other type is the one made with TCNQ layer inserted in between the ITO anode and TPD organic layer. Organic layers were formed by thermal evaporation at a pressure of $10^{-6}$ torr. It was found that for the TCNQ doped devices, turn-on voltage of the device was reduced by about 20 % and the current efficiency was improved by about three times near 6 V. And for devices with TCNQ layer inserted in between the ITO anode and TPD layer, it was found that the current efficiency was improved by more than three times even though there was not much change in turn-on voltage.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.12
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• pp.1039-1044
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• 2009

Red color OLED has been fabricated by the doping method apply to CBP using co-evaporation, GDI4349 of phosphorescent dopant, and rubrene of fluorescent dopant. The OLED structure are multi-layer of ITO(150 nm)/ELM_HIL(50 nm)/ELM_HTL(30 nm)/CBP : Rubrene, GDI4349 (30 nm)/BAlq (30 nm)/LiF(0.7 nm)/Al (100 nm). Accomplished best result at 3 vol.% of rubrene when the OLEDs were made of 1, 3, 5, 7, 9 vol.% doped rubrene. The highest efficiency of 7.2 cd/A was resulted at 8 vol.% of GDI4349 when the OLEDs were made among 5, 8, 11, 14 vol.% of GDI4349. Obviously, the best concentration of rubrene at 3 vol.% and changing GDI4349 concentration to 5, 8, 11, 14 vol.% OLED dramatically enhanced characteristic of resulted 10.7 cd/A at 8 vol.% of GDI4349. This result would understand to analyse as the emission efficiency increases by energy transport efficiency increase using GDI4349 energy transfer when rubrene absorbs the energy from CBP of fluorescences host.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.11a
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• pp.32-33
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• 2006

In this study, in order to develop multilayer ceramic actuator for ultrasonic nozzle and ultrasonic vibrator, PMN-PNN-PZT ceramics were fabricated using $Li_2CO_3$. $Na_2CO_3$ and ZnO as sintering aids. And then, their piezoelectric and dielectric properties according to the amount of ZnO addition were investigated. The addition of ZnO improved density, dielectric constant, electromechanical coupling factor, mechanical quality factor and piezoelectric d constant of PMN-PNN-PZT ceramics due to the increase of sinterability and accepter doping effect. Electromechanical coupling factor and mechanical quality factor of PMN-PNN-PZT ceramics increased with ZnO amount up to 0.4wt% and then decreased. At the sintering temperature of $900^{\circ}C$ and 0.4wt% ZnO addition, density, dielectric constant, electromechanical coupling factor, mechanical quality factor and piezoelectric d constant showed the optimum value of 7.876g/$cm^2$, 1299, 0.612, 1151 and 369pC/N, respectively.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.1583-1586
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• 2006

All non-dopant white organic light-emitting diodes (WOLEDs) have been realized by using solid state highly fluorescent red bis(4-(N-(1- naphthyl)phenylamino)phenyl)fumaronitrile (NPAFN) and amorphous bipolar blue light-emitting 2-(4- diphenylamino)phenyl-5-(4-triphenylsilyl)phenyl- 1,3,4-oxadiazole (TPAOXD), together with well known green fluorophore tris(8- hydroxyquinolinato)aluminum $(Alq_3)$. The fabrication of multilayer WOLEDs did not involve the hard-tocontrol doping process. Two WOLEDs, Device I and II, different in layer thickness of $Alq_3$, 30 and 15 nm, respectively, emitted strong electroluminescence (EL) as intense as $25,000\;cd/m^2$. For practical solid state lighting application, EL intensity exceeding $1,000\;cd/m^2$ was achieved at current density of $18-19\;mA/cm^2$ or driving voltage of 6.5-8 V and the devices exhibited external quantum efficiency $({\eta}_{ext})$ of $2.6{\sim}2.9%$ corresponding to power efficiency $({\eta}_P)$ of $2.1{\sim}2.3\;lm/W$ at the required brightness.

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.984-987
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• 2003

The electrophosphorescent emission properties were investigated in polymer light-emitting diodes (PLEDs) based on a poly(9-vinylcarbazole) (PVK) doped with a green phosphorescent dye of fac-tris(2-phenylpyridine) iridium (III) [$Ir(ppy)_3$]. A green light peaked at 516 nm was emitted from devices with a configuration of ITO/PEDOT:PSS/PVK:$Ir(ppy)_{3}$/BCP/$Alq_{3}$/LiF/Al. The optimal doping concentration of $Ir(ppy)_{3}$ in PVK was found at 2% by weight, under which maximum current efficiency of 24.3 cd/A and peak external quantum efficiency of 6.8% were achieved at the high luminance of 4240 $cd/m^{2}$. The external quantum efficiency of 5% and current efficiency of 18 cd/A can be sustained even at the very high luminance of 35000 $cd/m^{2}$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.324-324
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• 2010

최근에는 압전체의 환경오염 문제의 해결 및 가격경쟁력을 갖추기 위해서 비납계 압전체에 대한 연구가 활발히 진행되고 있다. (Na,K)$NbO_3$ 계는 페로브스카이트 구조를 가지는 비납계 세라믹스로 현재 가장 많이 연구되고 있는 물질 중의 하나이다. 본 연구에서는 압전성이 우수한 $(Na_{0.44}K_{0.52}Li_{0.04})(Nb_{0.9}Ta_{0.04}Sb_{0.06})O_3$ 조성에 CuO, $Cu_2O$ 등의 Cu 산화물을 첨가하였을 때의 전기기계결합계수, 기계적품질계수, 비유전율, 압전전하상수, 문극-전계 이력곡선 (P-E hysteresis curve) 등을 변화를 평가하고자 하였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.33-34
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• 2005

In this study, in odor to develop low temperature sintering multilayer piezoelectric actuator and ultrasonic vibrator, PMN-PNN-PZT ceramics were fabricated using $Li_2CO_3$ and $Na_2CO_3$ as sintering aids and their piezoelectric and dielectric characteristics were investigated according to the addition of dopant CuO and $Fe_2O_3$, respectively. The CuO added PMN-PNN-PZT ceramics improved mechanical quality factor Qm due to the acceptor doping effect. And also, $Fe_2O_3$ reacted as softner in this composition system in addition to the increase of grain size and sinterability. Taking into consideration electromechanical coupling factor kp of 0.62, dielectric constant $\varepsilon_r$, of 1275, Piezoelectric $d_{33}$ constant of 377[pC/N] and mechanical quality factor Qm of 975, it was concluded that the ceramics with the $Fe_2O_3$, added composition sintered at 900[$^{\circ}C$] were best for the multilayer piezoelectric actuator and ultrasonic vibrator application.

• Journal of the Korean Ceramic Society
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• v.51 no.4
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• pp.283-288
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• 2014

PdO-doped $BaZr_{0.85}Y_{0.15}O_{3-\delta}$ (BZPY) proton conductors have been proposed as applicable for intermediate temperature electrolytes for protonic ceramic fuel cells (PCFCs) because the PdO doping is effective for improving the proton conductivity of $BaZr_{0.85}Y_{0.15}O_{3-\delta}$ (BZY) with high affinity for hydrogen. In order to further improve the conductivity of BZPY, two-phase composite electrolytes consisting of a BZPY and molten carbonate were designed. Dense BZPY-based composite electrolytes were fabricated after sintering at $670^{\circ}C$ for 4 h, since molten carbonates fill the grain boundary of the porous BZPY matrix. Furthermore, BZPY/$(Li-0.5Na)_2CO_3$ composites show a significantly enhanced protonic conductivity at intermediate temperatures. This may be because easy proton transport is possible through the interface of the carbonate and oxide phase.