• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.8
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• pp.1326-1333
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• 2016

It is important to clear the fault and prevent resulting in damage to power system. Although the frequency of generator internal fault is relatively low, it can lead to incalculable damage to power system as well as generator. Especially, loss of field on generator can cause the generator to lose synchronism for a short time if it is not removed promptly. Therefore, it is needed to conduct research on loss of field relay for detecting or clearing the loss of field. However, the setting of the relay may vary in generator operator or engineer, and the relay is not coordinated well with other elements associated with loss of field. In this paper, we address specifically the coordination of positive offset mho loss of field relay which is one of the protection schemes for loss of field. Computer simulations are performed by using ElectroMagnetic Transients Program-Restructured Version (EMTP-RV) based on actual data.

• Journal of the Korean Vacuum Society
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• v.14 no.4
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• pp.238-244
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• 2005

IZO thin films are prepared on a corning 7059 glass substrate in a mixed gases of Ar +$O_2$ by rf-magnetron sputtering, using a powder target with a composition ratio of $In_{2}O_{3}$ : ZnO=90 : 10 $wt.\%$. Their electrical sheet resistance are strongly dependent on the oxygen concentration introduced during the deposition, a minimum resistivity of $3.7\times10^{-4}\Omega\cdot$ cm and an average transmittance over $85\%$ in the visible range are obtained in a film deposited in pure Ar gas which is close to near the stoichiometry. During the heat treatment from room temperature up tp $600^{\circ}C$ in various environments, the electrical resistance changes are explained by cyrstallizations or oxidizations of In metal and InO contained in the IZO film. The electrical properties due to oxygen adsorption and phase transitions occurring at temperatures over $40000^{\circ}C$ during heat treatment in air are also investigated.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.451-451
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• 2010

최근들어 80인치 이상의 대경 고화질 display 및 휴대용 projection display 제작이 가능한 LCoS (Liquid Crystal on Silicon) display에 대한 관심이 높아지고 있다. LCoS projection display는 높은 개구율, 빠른 응답속도, 고화질, 대형 디스플레이 임에도 불구하고 낮은 제조단가 등의 여러 가지 장점을 가지고 있다. LCoS projection display의 핵심 기술로는 높은 투과도와 낮은 반사율을 갖는 유리기판, 무기 배향막 증착 기술, Si back plane과의 접합기술 등이 있다. 이 중 LCoS projection display 제작을 위한 첫 단계인 유리기판은 가시광선 영역에서 96% 이상의 높은 투과도와 3% 미만의 반사도를 요구하는 기술을 필요로 한다. 본 연구에서는 indium이 doping된 tin oxide (ITO)를 투명 전도성막으로 사용하고, $SiO_2/MgF_2$ 이중 박막을 반사방지막으로 채택하여 고투과도 및 저반사율을 갖는 유리기판 제조에 응용하였다. 먼저 15nm 두께의 ITO 박막을 DC sputtering을 이용하여 8-inch 크기의 corning1737 유리기판 상에 증착한 후, 그 반대편에 e-beam evaporation 장비를 사용하여 120nm 두께의 반사 방지막을 증착하였다. 또한 유리기판 상에 증착된 투명 전도성막의 표면개질을 위하여 Ar plasma를 이용하여 treatment를 수행하였다. 이 때 sputtering 조건은 DC power, Ar 유량 및 압력을 조절함으로서 높은 투과도를 갖는 최적의 조건을 구현하였고, e-beam evaporation을 이용한 반사방지막 증착 조건은 $SiO_2$와 $MgF_2$의 계면에서 빛의 반사를 최소화할 수 있는 최적의 조건을 구현하였다. 제작된 유리기판은 가시광선 영역에서 97% 이상의 투과도를 보였으며, 최대 2.8%의 반사율을 보여, LCoS display 제작에 적합함을 확인할 수 있었다. 또한 Ar plasma 처리 후 ITO 박막의 면저항 값은 $100\;{\omega}/{\Box}$, 표면 거칠기는 rms 값 기준 0.095nm, 접촉각 $20.8^{\circ}$의 특성을 보여, 타 index matched transparent conducting oxide가 coating된 유리기판에 비해 우수한 특성을 보였다.

• Journal of the Korean Solar Energy Society
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• v.33 no.3
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• pp.58-66
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• 2013

Recently, PV module that the most important part of the photovoltaic system is more widened to lower manufacturing costs for module. However, the broad PV module results to the serious mechanical damage corning from installation circumstances such as snow, wind etc of snow and finally lead to the dramatic degradation of the electrical behavior of PV module. In this paper, 3 kinds of PV modules that consist of the different thickness and area of front glass and the diverse cross sectional structures of the frame are prepared for this experiment. The drooped length and electrical outputs of the PV modules are measured by means of applying 600Pa mechanical load to the PV modules from 1200Pa to 5400Pa base on the mechanical load test procedure of K SC IEG 61215 standard. The simulation data are obtained by the simulation tool as ANSYS and those are validate by comparing with the those experimental results figure out relations between the deformation and the constituent part of PV module.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2001.11a
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• pp.68-68
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• 2001

Thin films of polycrystalline silicon (poly-Si) is a promising material for use in large-area electronic devices. Especially, the poly-Si can be used in high resolution and integrated active-matrix liquid-crystal displays (AMLCDs) and active matrix organic light-emitting diodes (AMOLEDs) because of its high mobility compared to hydrogenated _amorphous silicon (a-Si:H). A number of techniques have been proposed during the past several years to achieve poly-Si on large-area glass substrate. However, the conventional method for fabrication of poly-Si could not apply for glass instead of wafer or quartz substrate. Because the conventional method, low pressure chemical vapor deposition (LPCVD) has a high deposition temperature ($600^{\circ}C-1000^{\circ}C$) and solid phase crystallization (SPC) has a high annealing temperature ($600^{\circ}C-700^{\circ}C$). And also these are required time-consuming processes, which are too long to prevent the thermal damage of corning glass such as bending and fracture. The deposition of silicon thin films on low-cost foreign substrates has recently become a major objective in the search for processes having energy consumption and reaching a better cost evaluation. Hence, combining inexpensive deposition techniques with the growth of crystalline silicon seems to be a straightforward way of ensuring reduced production costs of large-area electronic devices. We have deposited crystalline poly-Si thin films on soda -lime glass and SiOz glass substrate as deposited by PVD at low substrate temperature using high power, magnetron sputtering method. The epitaxial orientation, microstructual characteristics and surface properties of the films were analyzed by TEM, XRD, and AFM. For the electrical characterization of these films, its properties were obtained from the Hall effect measurement by the Van der Pauw measurement.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.160-160
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• 2020

조류는 계절별 기상 및 수질 조건에 따라 규조, 녹조, 남조의 발생 및 천이가 이루어지는데 최근 기후 변화로 인해 출연종 별 발생 및 천이의 시기 또한 빨라지고 있다. 이 중 남조류의 경우 초여름에 발생하여 급격한 증식으로 대발생되어 녹조현상을 야기하고 이는 해당 수역의 생태계 파괴, 그 이외에도 사회적, 경제적, 환경적인 측면에서 많은 문제를 유발한다. 하천·호소의 조류의 발생과 거동에 대한 이해와 효과적인 대응책 마련을 위하여 현상에 대한 모니터링이 선행되어야 하지만 기존 조사방식은 점, 선 단위의 간헐적 측정을 통해 진행되고 있어 많은 인력과 시간이 필요로 하고 있는 실태이다. 현재 이에 따른 문제 해결을 위한 하천·호소의 원격탐사 기법을 이용한 조류의 발생 및 거동에 대한 모니터링 연구가 많이 진행되고 있다. 본 연구에서는 초분광 영상을 이용한 원격 탐사 모니터링을 위한 선행연구를 위해 400-1000 nm에서 NIR(visNIR)파장을 분석할 수 있는 초분광 카메라 CORNING사의 micro HSITM 410 shark와 영상 흔들림 보정을 위한 DJI사의 로닌-MX를, 이용하여 현재 녹조류, 남조류 5종의 배양액과 방사보정을 위해 99% 반사율의 반사판과 함께 촬영하여 영상을 수집하였다. 수집된 영상을 통하여 방사보정 및 해당 Base 제거를 통한 조류의 분광 정보 추출 과정을 통해 조류별 분광 정보를 추출, 분석하여 해당 조류의 분광특성을 파악하고 기초 라이브러리를 구축하여 제시함으로 추후 하천·호소에서의 초분광 영상 기반 원격탐사 모니터링에 적용하고자 한다.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.119-119
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• 2021

최근 국내에서는 이상기후변화로 인해 수환경 변화가 일어나고 있으며, 이로인해 하천이나 저수지에 조류의 과대성장이 빈번히 발생되고 있다. 조류의 과대성장으로 인해 조류가 생산하는 독성물질, 이취미 물질은 수질을 악화 및 생태계에 큰영향을 미치는 실정이다. 또한, 조류는 하천, 저수지에 넓은 분포로 발생하게 되며, 현재 조류 조사방법은 다양한 계측장비를 통해 조사를 진행하고 있으나, 조류를 직접 채취하여 검경하거나, 보트 또는 조사선에 센서를 부착하여 측정하기 때문에, 점 또는 선단위의 간혈적 조사가 진행된다. 따라 많은 인력과 시간이 소요된다. 국내에선 인력과 시간을 줄이기 위해 최근 위성영상과 드론을 활용한 조류 원격탐사 모니터링에 대한 연구가 많이 진행되고 있다. 본 연구에서는 안동댐 인근 예안교에서 드론과 초분광센서를 이용하여 초분광데이터를 수집 및 조류 맵핑을 진행하였다. 사용된 드론은 DJI사의 RGB드론과 M-600Pro를 사용하였으며, 초분광 센서는 CORNING사의 microHSITM 410 SHARK를 이용하였으며, 파장 400-1000 nm에서 NIR(visNIR)파장을 분석할 수 있다. 드론에 짐벌을 장착하여 초분광센서를 수표면과 평행하게 두고 촬영 및 영상을 수집하였다. 방사보정을 하기위해 영상을 촬영 구간에 방사 보정용 반사천을 두고 동시간에 같이 촬영 하여 방사보정을 진행하였다. 본 연구에서는 초분광센서와 드론을 활용하여 조류 맵핑에 대한 연구를 하기위해 시료를 채취하여 검경결과와 비교분석을 하였으며, 초분광영상 분석을 통해 조류 최적밴드비를 산정하고 조류 맵핑을 진행하여 촬영구간에 대한 2차원 조류 맵핑 제시하여 하천에 적용하고자 한다.

• Nanomaterials
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• v.12 no.10
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• pp.1618-1626
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• 2022

CdS films with a wide range of substrate temperatures as deposition parameters were fabricated on Corning Eagle 2000 glass substrates using RF magnetron sputtering. The crystallographic structure, microscopic surface texture, and stoichiometric and optical properties of each CdS film deposited at various substrate temperatures were observed to be highly temperature-dependent. The grown CdS thin films revealed a polycrystalline structure in which a cubic phase was mixed based on a hexagonal wurtzite phase. The relative intensity of the H(002)/C(111) peak, which represents the direction of the preferential growth plane, enhanced as the temperatures climbed from 25 ℃ to 350 ℃. On the contrary, the intensity of the main growth peak at the higher temperatures of 450 ℃ and 500 ℃ was significantly reduced and exhibited amorphous-like behavior. The sharp absorption edge revealed in the transmission spectrum shifted from the long wavelength to the short wavelength region with the rise in the substrate temperature. The bandgap showed a tendency to widen from 2.38 eV to 2.97 eV when the temperatures increased from 25 ℃ to 350 ℃. The CdS films grown at the temperatures of 450 ℃ and 500 ℃ exhibited glass-like transmittance with almost no interference fringes of light, which resulted in wide bandgap values of 3.09 eV and 4.19 eV, respectively.

• Korean Journal of Materials Research
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• v.10 no.1
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• pp.97-106
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• 2000

In these respects the purpose of this research is manufacturing Co-W-P alloy thin film on the corning glass 2948 by electroless plating method using $NaH_2PO_2H_2O$ (sodium hypophosphite) as a reductant, and analyzing deposition rate, alloy composition, microstructure, and magnetic characteristics at various pH's and temperatures. For Co-P alloy thin film, the reductive deposition reaction occurred only in basic condition, not in acidic condition. The deposition rate increased as the pH and temperature increased, and the optimum condition was found at the pH of 10 and the temperature of 8$0^{\circ}C$. Also magnetic characteristics was found to be most excellent at the pH of 9 and the temperature of 7$0^{\circ}C$, resulting in the coercive force of 870Oe and the squareness of 0.78. At this condition, the contents of P was 2.54% and the thickness of the film was 0.216$\mu\textrm{m}$. For crystal orientation, we could not observe fcc for $\beta$-Co. On the other hand, (1010), (0002), (1011) orientation of hcp for $\alpha$-Co was observed. We could confirm the formation of longitudinal magnetization from dominant (1010) and (1011) orientation of Co-P alloy. For Co-W-P alloy thin film, coercive force was 500Oe and squareness was 0.6. For crystal orientation, (0002) orientation of $\alpha$-Co was dominatly found. Then we could confirm the formation of perpendicular magnetization. The content of P was constant at 0.8$\pm$0.2% and the content of W increased as the concentration of Na$_2$WO$_4$increased. When the concentration of Na$_2$WO$_4$was 0.1mol/L, the composition of W was 20%. We observed the changes of magnetic characteristics and microstructure of thin film depositions of Co-W-P by the heat treatment. For heat treatment, the temperature was increased step by step to 10$0^{\circ}C$, 20$0^{\circ}C$, 30$0^{\circ}C$, and 40$0^{\circ}C$ and it took 1 hour at each step in the reductive condition of hydrogen gas. By the heat treatment, flatness of surface was improved, but there were no changes on the magnetic characteristics and the microstructures.

• Korean Journal of Materials Research
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• v.9 no.3
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• pp.274-281
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• 1999

Usually sputtering and electroless plating methods were used for manufacturing metal-alloy thin film magnetic memory devices. Since electroless plating method has many merits in mass production and product variety com­pared to sputtering method, many researches about electroless plating have been performed in the United State of America and Japan. However, electroless plating method has not been studied frequently in Korea. In these respects the purpose of this research is manufacturing Co-Mn-P alloy thin film on the corning glass 2948 by electroless plating method using sodium hypophosphite as a reductant, and analyzing deposition rate, alloy composition, microstructure, and magnetic characteristics at various pH's and temperatures. For Co-P alloy thin film, the reductive deposition reaction 0$\alpha$urred only in basic condition, not in acidic condition. The deposition rate increased as the pH and temperature increased, and the optimum condition was found at the pH of 10 and the temperature of $80^{\circ}C$. Also magnetic charac­teristics was found to be most excellent at the pH of 9 and the temperature of $70^{\circ}C$, resulting in the coercive force of 8700e and the squareness of 0.78. At this condition, the contents of P was 2.54% and the thickness of the film was $0.216\mu\textrm{m}$. For crystal orientation, we could not observe fcc for $\beta$-Co. On the other hand,(1010), (0002), (1011) orientation of hcp for a-Co was observed. We could confirm the formation of longitudinal magnetization from dominant (1010) and (1011) orientation of Co-P alloy. For Co-Mn-P alloy deposition, coercive force was about 1000e more than that of Co P alloy, but squareness had no difference. For crystal orientation, (l01O) and (lOll) orientation of $\alpha$-Co was dominant as same as that of Co- P alloy. Likewise we could confirm the formation of longitudinal magnetization.