• Journal of the Korean Society for Nondestructive Testing
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• v.36 no.5
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• pp.391-398
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• 2016

Acoustic emission (AE) is one of the most powerful techniques for detecting damages and identify damage location during operations. However, in case of the source location technique, there is some limitation in conventional AE technology, because it strongly depends on wave speed in the corresponding structures having heterogeneous composite materials. A compressed natural gas(CNG) pressure vessel is usually made of carbon fiber composite outside of vessel for the purpose of strengthening. In this type of composite material, locating impact damage sources exactly using conventional time arrival method is difficult. To overcome this limitation, this study applied the previously developed Contour D/B map technique to four types of CNG storage tanks to identify the source location of damages caused by external shock. The results of the identification of the source location for different types were compared.

• Journal of the Korea Organic Resources Recycling Association
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• v.26 no.2
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• pp.5-10
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• 2018

This study was evaluated the characteristics of organic materials in the water source and the removal characteristics of organic materials by ultrafiltration including mixing and coagulation process. As a results of the study, it was found that the total organic carbon in the water source was mostly caused by the dissolved organic materials. As the specific ultraviolet absorbance value of the raw water was low, we found the soluble organic material has a high hydrophilic and low molecular material composition ratio. As a result of ultrafiltration experiment including mixing and coagulation process, the average removal rate of total organic carbon, dissolved organic carbon and ultraviolet absorbance at 254 were 37.9%, 30.3%, and 28.2%, respectively.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.7
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• pp.532-536
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• 2011

The silicon nitride films were prepared by chemical vapor deposition using inductively coupled plasma. During the deposition, the substrate was heated at $150^{\circ}C$ and power 1,000 W. To evolution low temperature manufacture, we have studied the role of source gases, $SiH_4$, $NH_3$, $N_2$, and $H_2$, to produce Si-N and N-H bond in a-SiNx:H film growth. $SiH_4$, $NH_3$, and $N_2$ flow rate fixed at 100, 10, and 10 sccm, $H_2$ flow rate varied from 0 to 10 sccm by small scale. To get the electrical characteristics, we makes MIM structure, and analysis surface bonding state. Experimental data show that Si-N and N-H bond is increased and hence electrical characteristics is showed 3 MV/cm breakdown-voltage, and leakage-current $10^{-7}\;A/cm^2$.

• KIEAE Journal
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• v.14 no.4
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• pp.119-125
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• 2014

This study investigated the effects of pipe network materials and distance on system performance utilizing unused energy sources in large-scale horticulture facility. For this, the modeling was performed with a 100 m long and 100 m wide rectangular shaped glass house having an area of 1ha ($10,000m^2$) using EnergyPlus software. The heat sources considered were air source, geothermal heat, power plant waste heat, sea water heat, and river water. The temperature variation of the fluid with regard to pipe material and distance from the heat source and the resultant heat pump electricity consumptions were calculated. It turned out that the fluid temperature reaching the heat pump increased as the distance from the heat source increased in case of sea water and river water, which have higher temperatures than the surrounding soil, improving the heat pump efficiency. It was vice versa in case of the power plant waste heat. In addition, pipe material of PVC showed the smallest effect on the system performance variation due to the lowest thermal conductivity, compared to PB and HDPE.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.352.1-352.1
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• 2014

Indium Tin Oxide (ITO) films are the most extensively studied and commonly used as ones of TCO films. The ITO films having a high electric conductivity and high transparency are easily fabricated on glass substrate at a substrate temperature over $250^{\circ}C$. However, glass substrates are somewhat heavy and brittle, whereas plastic substrates are lightweight, unbreakable, and so on. For these reasons, it has been recently suggested to use plastic substrates for flexible display application instead of glass. Many reaearchers have tried to produce high quality thin films at rood temperatures by using several methods. Therefore, amorphous ITO films excluding thermal process exhibit a decrease in electrical conductivity and optical transparency with time and a very poor chemical stability. However the amorphous Indium Gallium Zinc Oxide (IGZO) offers several advantages. For typical instance, unlike either crystalline or amorphous ITO, same and higher than a-IGZO resistivity is found when no reactive oxygen is added to the sputter chamber, this greatly simplifies the deposition. We reported on the characteristics of a-IGZO thin films were fabricated by RF-magnetron sputtering method on the PEN substrate at room temperature using 3inch sputtering targets different rate of Zn. The homogeneous and stable targets were prepared by calcine and sintering process. Furthermore, two types of IGZO TFT design, a- IGZO source/drain material in TFT and the other a- ITO source/drain material, have been fabricated for comparison with each other. The experimental results reveal that the a- IGZO source/drain electrode in IGZO TFT is shown to be superior TFT performances, compared with a- ITO source/drain electrode in IGZO TFT.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.31-36
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• 2003

We investigated dry etching of GaAs and AlGaAs in a high density planar inductively coupled plasma system with $BCl_3$ and $BCl_3/Ar$ gas chemistry. A detailed process study as a function of ICP source power, RIE chuck power and $BCl_3/Ar$ mixing ratio was performed. At this time, chamber pressure was fixed at 7.5 mTorr. The ICP source power and RIE chuck power were varied from 0 to 500 W and from 0 to 150 W, respectively. GaAs etch rate increased with the increase of ICP source power and RE chuck power. It was also found that etch rate of GaAs in $BCl_3$ gas with 25% Ar addition was superior to that of GaAs in a pure $BCl_3$ (20 sccm $BCl_3$) plasma. The result was same with AlGaAs. We expect that high ion-assisted effect in $BCl_3$/Ar plasma increased etch rates of both materials. The GaAs and AIGaAs features etched at 20 sccm $BCl_3$ and $15BCl_3/5Ar$ with 300 W ICP source power, 100 W RIE chuck power and 7.5 mTorr showed very smooth surfaces(RMS roughness < 2 nm) and excellent sidewall. XPS study on the surfaces of processed GaAs also proved extremely clean surfaces of the materials after dry etching.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.111-111
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• 2007

Further scaling the semiconductor devices down to low dozens of nanometer needs the extremely shallow depth in junction and the intentional counter-doping in the silicon gate. Conventional ion beam ion implantation has some disadvantages and limitations for the future applications. In order to solve them, therefore, plasma source ion implantation technique has been considered as a promising new method for the high throughputs at low energy and the fabrication of the ultra-shallow junctions. In this paper, we study about the effects of DC bias and base pressure as a process parameter. The diluted mixture gas (5% $PH_3/H_2$) was used as a precursor source and chamber is used for vacuum pressure conditions. After ion doping into the Si wafer(100), the samples were annealed via rapid thermal annealing, of which annealed temperature ranges above the $950^{\circ}C$. The junction depth, calculated at dose level of $1{\times}10^{18}/cm^3$, was measured by secondary ion mass spectroscopy(SIMS) and sheet resistance by contact and non-contact mode. Surface morphology of samples was analyzed by scanning electron microscopy. As a result, we could accomplish the process conditions better than in advance.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.33 no.4
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• pp.281-285
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• 2020

Oxide semiconductor devices have become increasingly important because of their high mobility and good uniformity. The channel length of oxide semiconductor thin film transistors (TFTs) also shrinks as the display resolution increases. It is well known that reducing the channel length of a TFT is detrimental to the current saturation because of drain-induced barrier lowering, as well as the movement of the pinch-off point. In an organic light-emitting diode (OLED), the lack of current saturation in the driving TFT creates a major problem in the control of OLED current. To obtain improved current saturation in short channels, we fabricated indium gallium zinc oxide (IGZO) TFTs with single gate and double gate structures, and evaluated the electrical characteristics of both devices. For the double gate structure, we connected the bottom gate electrode to the source electrode, so that the electric potential of the bottom gate was fixed to that of the source. We denote the double gate structure with the bottom gate fixed at the source potential as the BGFP (bottom gate with fixed potential) structure. For the BGFP TFT, the current saturation, as determined by the output characteristics, is better than that of the conventional single gate TFT. This is because the change in the source side potential barrier by the drain field has been suppressed.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.176-177
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• 2016

In the last few decades, attention toward atmospheric pressure plasma (APP) has been greatly increased due to the numerous advantages of those applications, such as non-necessity of high vacuum facility, easy setup and operation, and low temperature operation. The practical applications of APP can be found in a wide spectrum of fields from the functionalization of material surfaces to sterilization of medical devices. In the secondary battery industry, separator film has been typically treated by APP to enhance adhesion strength between adjacent films. In this process, the plasma is required to have high stability and uniformity for better performance of the battery. Dielectric barrier discharge (DBD) was usually adopted to limit overcurrent in the plasma, and we developed the pre-discharge technology to overcome the drawbacks of streamer discharge in the conventional DBD source which makes it possible to produce a super-stable plasma at atmospheric pressure. Simulations for the fluid flow and electric field were parametrically performed to find the optimized design for the linear jet plasma source. The developed plasma source (Plasmapp LJPS-200) exhibits spatial non-uniformity of less than 3%, and the adhesion strength between the separator and electrode films was observed to increase 17% by the plasma treatment.

• Transactions on Electrical and Electronic Materials
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• v.16 no.5
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• pp.254-259
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• 2015

This paper reports the optimized mixed-signal performance of a high-voltage (HV) laterally double-diffused metaloxide-semiconductor (LDMOS) field-effect transistor (FET) with a dual gate oxide (DGOX). The fabricated device is based on the split-gate FET concept. In addition, the gate oxide on the source-side channel is thicker than that on the drain-side channel. The experiment results showed that the electrical characteristics are strongly dependent on the source-side channel length with a thick gate oxide. The digital and analog performances according to the source-side channel length of the DGOX LDMOS device were examined for circuit applications. The HV DGOX device with various source-side channel lengths showed reduced by maximum 37% on-resistance (R_ON) and 50% drain conductance (g_ds). Therefore, the optimized mixed-signal performance of the HV DGOX device can be obtained when the source-side channel length with a thick gate oxide is shorter than half of the channel length.