• Journal of Powder Materials
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• v.27 no.1
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• pp.58-62
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• 2020

Recently, electrochromic devices (ECDs) have gathered increasing attention owing to their high color contrast and memory effect, which make them highly applicable to smart windows, auto-dimming mirrors, sensors, etc. Traditional ECDs have a sandwich structure that contains an electrochromic layer between two ITO substrates. These sandwich-type devices are usually fabricated through the lamination of two electrodes and followed by the injection of a liquid electrolyte in the inner space. However, this process is sometimes complex and time consuming. In this study, we fabricated ECDs with a lateral electrode structure that uses only an ITO substrate and an all-in-one electrochromic gel, which is a mixture of electrolyte and electrochromic material. Furthermore, we investigated the EC properties of the lateral-type device by comparing it with a sandwich-type device. The lateral-type ECD shows strong blue absorption as the applied voltage increases and has a competitive coloration efficiency compared to the sandwich-type device.

• Proceedings of the KAIS Fall Conference
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• 2011.12b
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• pp.413-416
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• 2011

Flip top cap은 경량성, 가공성, 내식성 우수하여 최근에 생활 용기 뚜껑으로 많이 활용되고 있다. Flip top cap은 사출성형에 의해 제작 되며 사출성형 과정에서 힌지부분에 웰드라인(Weldline)이 형성되어 기계적 강도가 떨어지게 된다. Flip top cap은 생활용기에 사용되며 실제생활에서 많은 작동을 요구하기 때문에 힌지부분의 웰드라인은 제품불량에 큰 원인이 된다. 또한 Flip top cap은 생산성을 높이기 위해 멀티캐비티(Multi-cavity) 사출방식을 선호한다. 멀티캐비티 방식은 높은 사출압력을 요구하기 때문에 사출품의 불량과 사출기에 많은 부하가 예상된다. 본 연구에서는 게이트 위치를 조정함으로써 사출품 힌지부분에서 발생할 수 있는 웰드라인을 품질에 영향이 없는 곳으로 이동시키고 최적의 사출 압력을 찾기 위한 유동해석을 통해 최적의 사출조건을 도출함으로써 Flip top cap의 기계적 품질과 제품생산성 향상을 위한 연구가 수행되었다.

• Journal of Korea Foundry Society
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• v.32 no.2
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• pp.65-74
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• 2012

In this paper, we present the results of our studies on optimal die design towards development of a vacuum die casting process to fabricate fuel cell bipolar plate with micro-channel array. Cavity and overflow shape is designed by computational filling analysis of MAGMA soft. Optimal die design consists of seven overflows at the end of cavity and three overflows at each side wall of cavity. The molten metal that passed the gate and reached the side wall flowed into the side overflow, no turbulent flow occurred, and the filling behavior and velocity distribution were uniform. In addition, partially solidified molten metal passing through the channel was perfectly eliminated by overflow without back-flow. When vacuum pressure, injection speed of low and high region was 300 mbar, 0.3 m/s and 2.5 m/s respectively with Silafont 36 die casting alloy, sound sample without casting defects was obtained. The experimental results are nearly consistent with simulation results.

• Journal of Korean Society for Atmospheric Environment
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• v.33 no.4
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• pp.306-318
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• 2017

Heavy diesel vehicles are one of major sources of urban fine dust in Korea and other developing countries. In this study, an auxiliary device assisting fuel atomization, which is called FAD (Fuel Activation Device), was closely reviewed through numerical simulation. As calculated, the diesel flow velocity passing across FAD increased up to 1.68 times, and it enhanced the cavitation effect which could improve the injected fuel atomization. Super cavitation phenomenon, which is the most important effect on nozzle injection, has occurred until the cavitation number (${\sigma}$) decreased from 1.15 to 1.09, and atomized droplets via a nozzle of which opening was $500{\mu}m$ distributed less than $200{\mu}m$ in sauter mean diameter (SMD).

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.10
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• pp.941-944
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• 2005

In this experiment, OLEDs(Organic Light Emitting Diodes) was fabricated to confirm effect of Plasma treatment which increase the hole injection characteristic from anode. Device structure was $ITO/2-TNATA/{\alpha}-NPD/DPVBi/BAlq/Alq_3/Al:Li$. We used DPVBi (4, 4 - Bis (2,2-diphenylethen-1-yls) - Biphenyl) as a blue emitting material. To optimize the process condition of plasma treatment, we used 2 gases of the oxygen and nitrogen gas under 120 mTorr with 100 W, 200 W, and 400 W plasma power. The current efficiency of $N_2$ plasma is more efficient than that of $O_2$ plasma. At $1000 cd/m^2$, we obtained the maximum current efficiency of 6.45 cd/A using $N_2$ gas with 200 W plasma power.

• Proceedings of the KIEE Conference
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• 2000.07a
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• pp.72-74
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• 2000

This paper presents the linear model of the measurement system with Phasor Measurement Units (PMU's) and the parallel processing technique to determinate state vectors of a power system. The conventional model of the PMU measurement system is in a dilemma that it is not applicable to optimal PMU placements and it needs more PMU to apply this model. In order to improve this defect, in this paper, the extended linear model which adaptable to optimal PMU placements considering the feature of zero injection bus is proposed. Because the proposed model is expressed as over-determined measurement equation, the efficient algorithm is needed. This paper proposed the partitioning scheme and the process algorithm for parallel determinating state vectors of a power system efficiently. The performance of the proposed linear model and the parallel processing algorithm is evaluated with IEEE sample systems.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.05a
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• pp.37.1-37.1
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• 2011

Miniaturization of lenses has been widely researched by various scientific and engineering techniques. As a result, micro scaled lens structure could be easily achieved from various fabrication techniques; nevertheless it is still challenging to make nano scaled lenses. This paper reports a novel fabrication method of silicon nanotemplate for nanolens array. The inverse structure of nanolens array was fabricated on silicon substrate by reactive ion etching (RIE) process. This technique has a flexibility to produce different tip shapes using different pattern masks. Once the silicon nano-tip array structure is well-defined using an optimized recipe, it is followed by polymer molding to duplicate nanolens array from the template. Finally, the nanostructures formed on silicon nanotemplate and polymer replica were investigated using FE-SEM and AFM measurements. The nano scaled lens can be manufactured from the same template, also using other replication techniques such as imprinting, injection molding and so on.

• Membrane Journal
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• v.1 no.1
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• pp.78-95
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• 1991

Water factory 21(WF 2) in Orange County California, is a advanced wastewater treatment(AWT) plant designed to reclaim biologically treated munidpal wastewater for injection into a seawater barrier system. Processes included are lime treatment air stripping, filtration, activated carbon adsorption, reverse osmosis(RO), and chlorination. The effectiveness of each treatment process is presented including pretreatment, RO dimineralization. The data collected show that the processes, including RO, used at WF-21 are capable of producing a very high quality water on a reliable basis. Treatment reduced all contaminants, to levels below national primary drinldng water regulation maximum contaminant levels. It was found that lime clarified secondary effluent can be used as feedwater to a RO dimineralizer. Experiments with new low pressure membrane(250psi) show great potential for reducing RO cost.

• Journal of Korean Academy of Nursing Administration
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• v.16 no.4
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• pp.399-408
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• 2010

Purpose: The purpose of this study was to compare the cost using different methods of costing nursing activities for patients with chronic otitis media having surgery. Method: Data were collected from 30 patients who had mastoidectomy and tympanoplasty. To compare the cost, the researchers used three different costing methods; consumed time, resource based relative value scale (RBRVS), and critical pathway (CP). Results: Twenty-six nursing activities for surgical patients with chronic otitis media were found. Total cost was 83,843.7 won using RBRVS. The costliest activity was recording at 9,734.4 won, followed by confirmation of doctors' orders at 9,302.4 won, and injection with infusion pump at 9,072.0 won. There was a difference in nursing activities performed according to the length of hospital stay, and the cost was highest on the surgery day at 13,417.8 won. Comparatively, the total cost was 72,014.4 won using CP. Conclusions: Nursing activities are performed in various forms according to the disease and patient's condition, and different nursing activities are executed according to the length of hospital stay. In order to measure the load of nursing activities and distribute it appropriately, it is necessary to analyze the cost of nursing activities by the process of nursing services performed.

• JSTS:Journal of Semiconductor Technology and Science
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• v.15 no.4
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• pp.454-461
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• 2015

Light enhancement of GaN based light emitting diodes (LEDs) have been investigated by texturing the top p-GaN surface. Nano-textured LEDs have been fabricated using self-assembled Ni nano mask during dry etching process. Experimental results were further compared with simulation data. Three types of LEDs were fabricated: Conventional (planar LED), Surface nano-porous (porous LED) and Surface nano-cluster (cluster LED). Compared to planar LED there were about 100% and 54% enhancement of light output power for porous and cluster LED respectively at an injection current of 20 mA. Moreover, simulation result showed consistency with experimental result. The increased probability of light scattering at the nano-textured GaN-air interface is the major reason for increasing the light extraction efficiency.