• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.145-145
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• 2011

Recently, multi-hole electrode RF capacitively coupled plasma discharge is being used in the deposition of microcrystalline silicon for thin film solar cell to increase the speed of deposition. To make efficient multi-hole electrode RF capacitively coupled plasma discharge, the hole diameter is to be designed concerning the plasma parameters. In past studies, the relationship between plasma parameters such as pressures and gas species, and hole diameter for efficient plasma density enhancement is experimentally shown. In the presentation, the relationship between plasma deriving frequency and hole diameter for efficient multi-hole electrode RF capacitively coupled plasma discharge is shown. In usual capacitively coupled plasma discharge, plasma parameter, such as plasma density, plasma impedence and plasma temperature, change as frequency increases. Because of the change, the optimum hole diameter of the multi-hole electrode RF capacitively coupled plasma for high density plasma is thought to be modified when the plasma deriving frequency changes. To see the frequency effect on the multi-hole RF capacitively coupled plasma is discharged and one of its electrode is changed from a plane electrode to a variety of multi-hole electrodes with different hole diameters. The discharge is derived by RF power source with various frequency and the plasma parameter is measured with RF compensated single Langmuir probe. The shrinkage of the hole diameter for efficient discharge is observed as the plasma deriving frequency increases.

• Journal of the Korea Society of Computer and Information
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• v.10 no.1 s.33
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• pp.1-6
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• 2005

White light emission is very important for applying electroluminescent device to full display, backlight and illumination light source. In this letter, Multilayer molecular organic white-light-emitting device using thin nim of blue material nitro-DPVT with fluorescent dye Rubrene for an orange emission were fabricated. The basic structure of the fabricated device is a-NPD / nitro-DPVT / nitro- DPVT:Rubrene / BCP/ Alq3. Aluminum is used as the cathode material and ITO was anode material. The white light emission spectrum covers a wide range of the visible region and the Commission Internationale do I'E clairage (C.I.E.) coordinates of the emitted light was ((0.3347, 0.3515) at 14V. The turn voltage is as low as 2.5V and quantum efficiencies are $0.35\%$.

• Journal of the Ergonomics Society of Korea
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• v.21 no.1
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• pp.95-112
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• 2002

Two experiments were carried out to compare the suitability in visual tasks between cathode-ray tube (CRT) and thin film transistor-liquid crystal display (TFT-LCD). In the first experiment, the subjects were requested to detect pre-assigned target words or icons among distracters presented under time-invariant (static) image mode. The subjects' visual performance and fatigue were assessed while carrying out search tasks with dim and bright ambient light conditions. Significant interaction effects were found among displays, task types, and ambient light conditions. Due to visual fatigue, the subjects' accommodative power decreased in the end of task and the degradation was more significant for the CRT users and under bright ambient light. IN the second experiment, the subjects performed information processing task with time-varying road signs at a driving simulator to assess interaction effects between display types and changing speed of dynamic image. The perception time using TFT-TCD was shorter under slow image change while that of CRT was shorter rapid image change. Findings from this study suggest that, to improve visual task performance, users should carefully select their visual display type depending on the task to be performed.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.611-616
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• 2004

In this study, microfabrication of a micro-arcjet nozzle with Fifth-harmonic generation Nd：YAG pulses (wavelength 213 nm) and its thrust performance tests were conducted. A micro-arcjet nozzle was machined in a 1.2 mm thick quartz plate. Sizes of the nozzle were 0.44 mm in width of the nozzle exit and constrictor diameter of 0.1 mm. For an anode, a thin film of Au (~100 nm thick) was deposited by DC discharge PVD in vacuum on divergent part of the nozzle. As for a cathode, an Au film was also coated on inner wall surface. In operational tests, a stable discharge was observed for mass flow of 1.0mg/sec, discharge current of 6 ㎃, discharge voltage of 600 V, or 3.6 W input power (specific power of 3.6 MW/kg). In this case, plenum pressure of the discharge chamber was 80 ㎪. With 3.6 W input power, thrust obtained was 1.4 mN giving specific impulse of 138 sec with thrust efficiency of 24 %.

• Proceedings of the KIEE Conference
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• 2001.10a
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• pp.183-186
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• 2001

평판 디스플레이의 기술이 급격히 발전함에 따라 그 응용 분야가 다양해지고 평판 모니터용 LCD도 대형화추세를 보이고 있다. LCD는 광변조기능을 가지는 수광소자로서 발광원인 백라이트(backlight)를 필요로 하는데 백라이팅 기술은 냉음극방전램프(CCFL: Cold Cathode Fluorescence Lamp)를 광원으로 사용하며 사용되는 냉음극 방전램프 또한 모니터의 추세에 따라 길어지고 얇아지고 있다. 본 논문에서는 20인치의 대형 LCD 모니터의 백라이팅 즉 램프구동을 위한 안정적이면서 대출력을 가지는 인버터를 설계하였다. 일반적으로 CCFL은 같은 제조공정을 거치더라도 점등, 주파수, 전압, 전류 등 여러 가지 특성이 동일하지 않은 단점을 가지고 있는데 이는 초기 점등조건이나 점등후에 동일한 휘도를 가지는데 어려움을 준다. 본 연구에 사용된 20인치 LCD 모니터는 내부에 상하 각각 3개씩 6개의 램프를 내장하고 있으며, 제작된 인버터는 입출력 휘도대비 90%의 효율을 얻었으며, 램프간의 출력전류차가 2%로 미소하고, 최대 8개의 램프구동도 가능하다.

• Journal of the Korean Ceramic Society
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• v.52 no.5
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• pp.338-343
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• 2015

To prevent an interfacial reaction between the anode and the electrolyte layer during the conventional high-temperature co-firing process, an anode-supported type cell with a thin-film electrolyte was fabricated by low-temperature ceramic thick film coating process. Ni-GDC cermet composite was used as the anode material and YSZ was used as the electrolyte material. Open circuit voltage and maximum power density were found to strongly depend on the surface uniformity of the anode functional layer. By optimizing the microstructure of the anode functional layer, the open circuit voltage and maximum powder density of the cell increased to 1.11 V and $1.35W/cm^2$, respectively, at $750^{\circ}C$. When a GDC barrier layer was applied between the YSZ electrolyte and the LSCF cathode, the cell showed good stability, with almost no degradation up to 100 h. Anode-supported type SOFCs with high performance and good stability were fabricated using a coating process.

• Journal of the Korean institute of surface engineering
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• v.19 no.3
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• pp.92-108
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• 1986

An electroplating on the lead frame fabricated from domestic copper plate was studied experimentally. In this study, nickel was plated on the thin copper lead frame and silver layer was coated on the nickel film in the cyanide electrolyte. The effect of process variables such as current density, plating time, coating thickness and flow rate of electrolytic solution on the properties of coating was investigated. Some samples on each step were fabricated during electroplating. The results obtained from polarization measurement, observation of SEM photograph, adhesion test of coating and microhardness test are as follows. On silver plating, polarization resistance of potentiostatic cathodic polarization curve is reduced as the flow rate of Ag electrolytic solution increases. And above resistance is also reduced when the minor chemicals of sodium cyanide and sodium carbonate are added in potassium silver cyanide bath. The reduced polarization resistance makes silver deposition on the cathode easy. An increase in the current density and the coating thickness causes the particle size of deposit to coarsen, and consequently the Knoop microhardness of the coating decreases. On selective plating an increase in the flow rate of plating solution lead to do high speed plating with high current density. In this case, the surface morphology of deposit is of fine microstructure with high Knoop hardness. An increasing trend of the adhesion of coating was shown with increasing the current density and flow rate of electrolytic solution.

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1359-1360
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• 2006

lTO(Indium-Tin-Oxide) was used as anode material for OLED. Characteristics of ITO have great effect on efficiency of OLEDS(Organic light emitting diodes). ITO surface was treated by Nd:YAG laser in order to improve its chemical properties, wettability, adhesive property and to remove the surface contaminants while maintaining its original function. In this study, main purpose was to improve the efficiency of OLEDs by the ITO surface treatment: ITO surface was treated using a Nd:YAG(${\lambda}=266nm$, pulse) with a fixed power of 0.06[w] and various stage scanning velocities. Surface morphology of the ITO was investigated by AFM. Test OLEDs with surface treated ITO were fabricated by deposition of TPD (HTL), Ald3 (ETL/TML) and Al (cathode) thin films. Device performance of the OLEDs such as V-I-L was investigated using Source Measurement Unit (SMU: Keithly. Model 2400) and Luminance Measurement (TOPCON. BM-8).

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1665-1666
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• 2006

TFT-LCD(Thin Film Transistor Liquid Crystal Display)는 표시장치로서 실용화된 후 많은 상품에 적용중이다. 그러나, LCD는 자체 발광능력이 없으므로 그후면에서 LCD 화면을 밝혀주는 BLU(Backlight Unit)를 필요로 한다. BLU는 내부 광원으로 밝기가 균일한 평면광을 만들어 LCD 화면을 균일하게 면조사하는 역할을 한다. LCD가 적용되는 분야중 Note PC에는 광원으로 CCFL(Cold Cathode Fluorescent Lamp)가 적용되어 왔지만, 최근 고휘도, 박형화, 저소비 전력을 달성하기 위해 CCFL로는 한계가 있어 LED(Light Emitting Diode)를 적용한 BLU를 제작하기 위한 연구가 진행되고 있다. 본 연구에서는 점광원인 LED 적용한 LED에 있어서 요구되는 휘도 균일성을 향상시키기 위해서는 LED광원이 적용된 BLU의 외관 품질 향상을 위한 도광판 입광부 구조 최적화를 광추적 Simulation을 통해 예측하고 향상시킬 수 있는 구조를 제안한다. Simulation결과, 외관품질 개선을 위해 도광판 입광면에 130도의 Serration과 휘도를 향상하기 위해 도광판 밑면에 렌즈 형상의 바 구조를 도출해 적용한 결과 외관품질향상과 휘도향상을 얻었다.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.29 no.4
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• pp.179-186
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• 2019

In this study, we investigated the structural properties of $Ga_2O_3$ thin films and the photo-electrical properties of metal-semiconductor-metal (MSM) photodetectors deposited by Ti/Au electrodes. $Ga_2O_3$ thin films were grown at different temperatures using metal organic chemical vapor deposition (MOCVD). The crystal phase of $Ga_2O_3$ changed from ${\varepsilon}$-phase to ${\beta}$-phase depending on the growth temperature. The crystal structure of ${\varepsilon}-Ga_2O_3$ was confirmed by X-ray diffraction (XRD) analysis and the formation mechanism of crystal structure was discussed by scanning electron microscopy (SEM) images. From the results of current-voltage (I-V) and time-dependent photoresponse characteristics under the illumination of external lights, we confirmed that the MSM photodetector fabricated by ${\varepsilon}-Ga_2O_3$ showed much better photocurrent characteristics in the 266 nm UV range than in the visible range.