• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.265.2-265.2
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• 2016

Oxide thin film transistors (TFTs) have attracted considerable interest for gate diver and pixel switching devices of the active matrix (AM) liquid crystal display (LCD) and organic light emitting diode (OLED) display because of their high field effect mobility, transparency in visible light region, and low temperature processing below $300^{\circ}C$. Recently, oxide TFTs with polycrystalline In-Ga-O(IGO) channel layer reported by Ebata. et. al. showed a amazing field effect mobility of $39.1cm^2/Vs$. The reason having high field effect mobility of IGO TFTs is because $In_2O_3$ has a bixbyite structure in which linear chains of edge sharing InO6 octahedral are isotropic. In this work, we investigated the characteristics and the effects of oxygen partial pressure significantly changed the IGO thin-films and IGO TFTs transfer characteristics. IGO thin-film were fabricated by rf-magnetron sputtering with different oxygen partial pressure ($O_2/(Ar+O_2)$, $Po_2$)ratios. IGO thin film Varies depending on the oxygen partial pressure of 0.1%, 1%, 3%, 5%, 10% have been some significant changes in the electrical characteristics. Also the IGO TFTs VTH value conspicuously shifted in the positive direction, from -8 to 11V as the $Po_2$ increased from 1% to 10%. At $Po_2$ was 5%, IGO TFTs showed a high drain current on/off ratio of ${\sim}10^8$, a field-effect mobility of $84cm^2/Vs$, a threshold voltage of 1.5V, and a subthreshold slpe(SS) of 0.2V/decade from log(IDS) vs VGS.

• 한국화재소방학회논문지
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• 제14권1호
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• pp.1-7
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• 2000

절연재료의 내부에서 부분방전이 발생하면 국부파괴와 완전절연파괴의 원인이 된다. 부분방전으로 생기는 트리잉은 절연재료를 열화시키고 절연 수명을 단축시키는 중요한 원인이 된다. 따라서 절연파괴의 예측과 절연재료의 수명을 진단할 수 있는 방법에 대한 연구는 매우 중요하다. 고전압 하에서 일어나는 트리잉 현상에 대해서 저밀도 폴리에틸렌의 트리잉 개시 전압과 그 진전 과정을 진성파괴의 견해에서 고찰하였다. 이러한 관점에서 본 연구는 고전압하에서 일어나는 트리잉현상에 대해서 저밀도폴리에틸렌에서 트리형상의 전계의존성에 관하여 고찰하였다. 결과로서 트리의 성장을 그 내부가 각각 유전체 혹은 도체라고 가정했을 때의 중간적인 특성을 갖는다는 추리하에 이론적으로 검토한 결과, 실험결과와도 잘 일치됨을 알 수 있었다.

• 조명전기설비학회논문지
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• 제22권5호
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• pp.7-12
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• 2008

부싱의 형상에 따라 전계 분포를 비교하여 가장 효율적인 형상을 설계하고자 하였다. 본 연구에서 형상 변화는 12 조건이며 전극 길이의 변화로 벡터 분포도는 0.7[%], 전계 분포도는 약 $21{\sim}26[%]$의 절연 성능을 향상시킬 수 있었다. 그리고 고압부 절연물 두께의 변화는 벡터 분포도는 2[%], 전계 분포도는 약 $23{\sim}43[%]$의 절연 성능을 향상시킬 수 있었다. 따라서 조건변화에 따라 절연성능이 향상되는 것을 알 수 있으므로 부분방전 개시전압 소멸전압을 향상시킬 수 있을 것으로 사료된다.

• International Journal of Fluid Machinery and Systems
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• 제3권2호
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• pp.129-136
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• 2010

The attachment of inducer upstream of main impeller is an effective method to improve the suction performance of turbopump. However, various types of cavitation instabilities are known to occur even at the designed flow rate as well as in the partial flow rate region. The cavitation surge occurring at partial flow rates is known to be strongly associated with the inlet back flow. In the present study, in order to understand the detailed structure of internal flow of inducer, we firstly carried out the experimental and numerical studies of non-cavitating flow, focusing on the flow field near the inlet throat section and inside the blade passage of a two bladed inducer at a partial flow rate. The steady flow simulation with cavitation model was also made to investigate the difference of flow field between in the cavitating and no-cavitating conditions.

• Journal of Electrical Engineering and Technology
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• 제9권1호
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• pp.293-300
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• 2014

This paper proposes a novel pattern recognition approach based on the radial basis function (RBF) neural network for identifying insulation defects of high-voltage electrical apparatus arising from partial discharge (PD). Pattern recognition of PD is used for identifying defects causing the PD, such as internal discharge, external discharge, corona, etc. This information is vital for estimating the harmfulness of the discharge in the insulation. Since an insulation defect, such as one resulting from PD, would have a corresponding particular pattern, pattern recognition of PD is significant means to discriminate insulation conditions of high-voltage electrical apparatus. To verify the proposed approach, experiments were conducted to demonstrate the field-test PD pattern recognition of cast resin current transformer (CRCT) models. These tests used artificial defects created in order to produce the common PD activities of CRCTs by using feature vectors of field-test PD patterns. The significant features are extracted by using nonlinear principal component analysis (NLPCA) method. The experimental data are found to be in close agreement with the recognized data. The test results show that the proposed approach is efficient and reliable.

• Water Engineering Research
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• 제3권1호
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• pp.31-44
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• 2002

The effect of diurnal cycle, intermittent visit of observation satellite, sensor installation, partial coverage of remote sensing, heterogeneity of soil properties and precipitation to the soil moisture estimation error were analyzed to present the global sampling strategy of soil moisture. Three models, the theoretical soil moisture model, WGR model proposed Waymire of at. (1984) to generate rainfall, and Turning Band Method to generate two dimensional soil porosity, active soil depth and loss coefficient field were used to construct sufficient two-dimensional soil moisture data based on different scenarios. The sampling error is dominated by sampling interval and design scheme. The effect of heterogeneity of soil properties and rainfall to sampling error is smaller than that of temporal gap and spatial gap. Selecting a small sampling interval can dramatically reduce the sampling error generated by other factors such as heterogeneity of rainfall, soil properties, topography, and climatic conditions. If the annual mean of coverage portion is about 90%, the effect of partial coverage to sampling error can be disregarded. The water retention capacity of fields is very important in the sampling error. The smaller the water retention capacity of the field (small soil porosity and thin active soil depth), the greater the sampling error. These results indicate that the sampling error is very sensitive to water retention capacity. Block random installation gets more accurate data than random installation of soil moisture gages. The Walnut Gulch soil moisture data show that the diurnal variation of soil moisture causes sampling error between 1 and 4 % in daily estimation.

• 대한자원환경지질학회:학술대회논문집
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• 대한자원환경지질학회 2005년도 춘계 학술발표회 논문집
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• pp.148-151
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• 2005

Field-scale DNAPL dissolution is controlled by the topology of DNAPL distributions with respect to the velocity field. A high resolution percolation model was developed and employed to simulate the distribution of DNAPL within source zones. Statistically anisotropic permeability values and capillary parameters were generated for 10${\times}$10${\times}$10 m domains at a resolution of 0.05 to 0.1 m for various statistical properties. TCE leakage was simulated at various rates and the distribution of residual DNAPL in 'fingers' and 'lenses' was computed. Variations in finger and lens geometries, frequencies, average DNAPL saturations, and overall source topology were predicted to be strongly influenced by statistical properties of the medium as well as by injection rate and fluid properties. Model results were found to be consistent with observations from controlled DNAPL release experiments reported in the literature. The computed distributions of aquifer properties and DNAPL were utilized to perform high-resolution numerical simulations of groundwater flow and dissolved transport. Simulations were performed to assess the effect of grout or foam injection in bore holes within the source zone and of shallow point-releases of fluids with various properties on dissolution in DNAPL dissolution rate, even for widely spaced injection points. The results indicate that measures that induced partial flow reductions through DNAPL source zones can significantly decrease dissolution rates from residual DNAPL. The benefit from induced partial flow reductions is two-fold: 1) local flow reduction in DNAPL contaminated zones reduces mass transfer rates, and 2) contaminant flux reductions occur due to the decrease in groundwater velocity

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제55권10호
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• pp.485-491
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• 2006

This paper describes that the distribution of electromagnetic field occurred by PD(Partial Discharge) pulse was calculated with simulation program and characteristics of calibration and PD pulses measured with folded dipole types sensors were analyzed. As the distribution of electromagnetic field in simulation was very random the wide band measuring methods were good. Therefore three folded dipole antenna types sensors which had different their widths were designed and made. The signal according to direction and distance between sensor and pulse source in these sensor was measured and the spectrum of surface PD were acquired in the experiment of model transformer. In this result the characteristics of sensor which had middle width was better than others and the main spectrum of PD signals in surface discharge were existed in around 220MHz, 320MHz and from 450MHz to 750MHz.

• 대한족부족관절학회지
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• 제27권2호
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• pp.75-78
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• 2023

During bone tumor resection, many cases require medial malleolar osteotomy to achieve adequate access to the operative field. Various osteotomy methods have been developed to address this issue, including oblique, transverse, reverse V-shape, and step-cut osteotomies. However, medial malleolar osteotomy has several drawbacks, such as the excessive disruption of the joint surface, unstable screw fixation when fixing the medial malleolus, and iatrogenic medial ankle joint arthritis due to articular displacement during the reduction of the osteotomy site. In addition, there is a possibility of injury to the posterior tibial artery, tibial nerve, or posterior tibialis tendon if the osteotomy range is too aggressive. Therefore, the authors propose a new osteotomy method, which has shown promising clinical results, namely, partial posterior medial malleolar osteotomy. This method minimizes articular involvement and provides adequate access to the operative field during talar body bone tumor resection.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 추계학술대회 논문집 전기설비전문위원
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• pp.239-242
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• 2008

In this paper, we developed HPF (high pass filter) consisted of lumped LC components to decrease the noises that are detected in PD (partial discharge) measuring test, and adapted it to field test. We tested under laboratory circumstances like the fields, and measured the phase change properties of detected signal in UHF sensor with Lemke probe and oscilloscope (TDS-3054, Tektronix).