• Korean Journal of Optics and Photonics
• /
• v.33 no.4
• /
• pp.146-158
• /
• 2022

The detector of a focal-plane-array mid-wave infrared (MWIR) camera has different response characteristics for each detector pixel, resulting in nonuniformity between detector pixels. In addition, image nonuniformity occurs due to heat generation inside the camera during operation. To solve this problem, in the process of camera manufacturing it is common to use a gain-and-offset table generated from a blackbody to correct the difference between detector pixels. One method of correcting nonuniformity due to internal heat generation during the operation of the camera generates a new offset value based on input frame images. This paper proposes a technique for dividing an input image into block image patches and generating offset values using only homogeneous patches, to correct the nonuniformity that occurs during camera operation. The proposed technique may not only generate a nonuniformity-correction offset that can prevent motion marks due to camera-gaze movement of the acquired image, but may also improve nonuniformity-correction performance with a small number of input images. Experimental results show that distortion such as flow marks does not occur, and good correction performance can be confirmed even with half the number of input images or fewer, compared to the traditional method.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.10 no.4
• /
• pp.450-456
• /
• 2022

In this study, as the preliminary research on the development of heating concrete members, compressive strength and accelerated chloride diffusion behavior in the mortar specimens containing C₁₂A₇ based binder and anhydrite was evaluated. Also, the effect of the mixing ratio of the citric acid based retarder was quantitatively evaluated by considering 4 levels of mixing cases. The compressive strength tests of the mortar specimen were performed referred to KS L ISO 679, and the accelerated chloride diffusion tests were performed according to NT BUILD 492 and ASTM C 1202. In the mortar with 0.3 % of retarder, the highest compressive strength was evaluated, which showed the strength development ratio of 127.6 % compared to the control case. It was considered that engineering performance was improved by effectively securing setting and curing time with 0.3 % of citric acid based retarder. As the result of the evaluation of the passed charge and the accelerated chloride diffusion coefficient, the evaluation results had similar behavior with the results of compressive strength. According to the previous study, the strength behavior and the chloride diffusion behavior had a linear relationship. The mixture showing the highest strength performance had the highest durability performance for chloride ingress, and the heating concrete development from this study will be performed in the future.

• Journal of the Korea Organic Resources Recycling Association
• /
• v.18 no.1
• /
• pp.110-118
• /
• 2010

Supercritical treatment of liquefaction technology for rice hull was investigated the biomass conversion rate and evaluated its crude oil in respect to feasibility of burner in order to heat the green house. The reaction was carried out in a 5,000 mL liquefaction system with dispenser and external electrical furnace. Raw materials (160 g) of rice hull and 3,000 mL of different solvents were fed into the reactor. It was observed that the maximum crude oil yield was about 84.4 % with 1-butanol. The calorific value of crude oil from ethanol solvent were 7,752 kcal/kg. Furthermore, in case study of co-solvent with ethanol and bulk-glycerol, it observed that more than 80 % of rice hull was decomposed and liquefied in its solvent at $315{\sim}326^{\circ}C$ for 30 min. For the development of applicable bio-fuel from rice hull, it was considered that its feasibility is necessary to be carried out for co-solvent soluble portions. Regarding to utilize the crude oil into burner as fuel, it was observed that its calorific value was lower at approximately 24 % than the diesel. Also, flame length from crude oil at lower temperature was decreasing due to incomplete incineration. The temperature of warm wind on the burner was maintained between 63 and $65^{\circ}C$, and the temperature of emission line was appeared at $350{\sim}380^{\circ}C$.

• Journal of the Korean Applied Science and Technology
• /
• v.34 no.1
• /
• pp.1-11
• /
• 2017

Bio-oil has attracted considerable interest as one of the promising renewable energy resources because it can be used as a feedstock in conventional petroleum refineries for the production of high value chemicals or next-generation hydrocarbon fuels. Zeolites have been shown to effectively promote cracking reactions during pyrolysis resulting in highly deoxygenated and hydrocarbon-rich compounds and stable pyrolysis oil products. In this study, catalytic pyrolysis was applied to upgrade bio-oil from yellow poplar and then fuel characteristics of upgraded bio-oil was investigated. Yellow Poplar(500 g) which ground 0.3~1.4 mm was processed into bio-oil by catalytic pyrolysis for 1.64 seconds at $465^{\circ}C$ with Control, Blaccoal, Whitecoal, ZeoliteY and ZSM-5. Under the catalyst conditions, bio-oil productions decreased from 54.0%(Control) to 51.4 ~ 53.5%, except 56.2%(Blackcoal). HHV(High heating value) of upgraded bio-oil was more lower than crude bio-oil while the water content increased from 37.4% to 37.4 ~ 45.2%. But the other properties were improved significantly. Under the upgrading conditions, ash and TAN(Total Acid Number) is decrease and particularly important as transportation fuel, the viscosity of bio-oil decreased from 6,933 cP(Control) to 2,578 ~ 4,627 cP. In addition, ZeoliteY was most effective on producing aromatic hydrocarbons and decreasing of from the catalytic pyrolysis.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.53 no.10
• /
• pp.123-130
• /
• 2016

High-frequency induction heating equipment can heat the metal by applying a High-Frequency power to the resonant circuit. The resonance circuit is composed of the work coil and the conduction-cooled power capacitor, it influences the performance of the heat treatment equipment according to the characteristics of the capacitor. However, dependence on conduction-cooled power capacitor's import is high due to lack of core technology research and development. Minimizing the generation of internal heat transmitted inside during LC resonance, reduce the reactive power loss, there is a need for a capacitor within the voltage characteristic outstanding. To implement localization it is vital that prior study of the analysis on the frequency response characteristic for the finished capacitor advanced manufacturer be implemented. Studying the interpolation method to read the value at any point of the characteristic curve for a given log-log scale was applied to the analysis tool of the capacitor by my proposed algorithm. The simulation for reproducing frequency response curves was attempted by assuming a capacitor in a simplified series equivalent RC circuit to obtain the equivalent series resistance value. It was confirmed that the reproduction rate was the result value above 83% as compared to the simulation of the properties and characteristics on the actual reactive power for Peak value, and that the algorithm can be applicable when analyzing and predicting the characteristic curves of a simpled model capacitor.

• Applied Chemistry for Engineering
• /
• v.10 no.7
• /
• pp.990-995
• /
• 1999

To determine the effect of chemical structure of linear amine curing agents on thermal and mechanical properties, standard epoxy resin DGEBA was cured with ethylene diamine(EDA) and hexamethylene diamine(HMDA) in a stoichiometrically equivalent ratio. From this work, the effect of linear amine curing agents on the thermal and mechanical properties is significantly influenced by the chemical structure or chain length of curing agents. In contrast, the results show that the DGEBA/EDA system having the two carbons had higher values in the thermal stability, maximum conversion of epoxide, density, glass transition temperature, tensile modulus, flexural strength, and flexural modulus than the DGEBA/HMDA system having the six carbons, whereas the DGEBA/EDA cure system had relatively low values in the shrinkage(%), thermal expansion coefficient, tensile strength, and had similar values in the maximum exothermic temperature, and conversion of epoxide compared to the DGEBA/HMDA cure system. This findings indicate that packing ability in the HMDA structure affects the thermal and mechanical properties.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2009.06a
• /
• pp.157-157
• /
• 2009

$BaTiO_3$를 기본조성으로 하는 PTC 써미스터는 Curie 온도이상에서 저항이 급격히 상승하는 반도성 전자세라믹스로서 degaussing 소자, 정온 발열체, 온도센서, 전류 제한 소자 등 상업적으로 폭넓게 사용되고 있다. 본 소자는 소결온도, 소결 및 열처리 분위기, 불순물, 첨가제 등의 제조공정상의 인자들과 기공률, 결정립 크기 등이 복합적으로 작용하여 PTCR 특성이 크게 영향을 받기 때문에 제조하기에 무척 까다로운 소자로 알려져 있다. 특히 과전류 보호 소자용으로 사용하기 위해서는 상온 비저항을 크게 낮추어야 하며 이에 대한 연구가 계속 진행되고 있다. 따라서 본 연구에서는 SiO2을 0.5~10 at%로 달리한 조성으로 환원 분위기에서 소결하고 공기 중에서 재산화 처리하여 재료의 PTC 특성에 어떠한 영향을 미치는지 분석하였다. 소정의 조성을 선택하여 $1180^{\circ}C{\sim}1240^{\circ}C$에서 2시간 동안 환원분위기에서 소결하고, $800^{\circ}C$에서 1 시간 공기 중에서 재산화 처리한 후 R-T 특성을 측정하여 SiO2 함량에 따른 PTC 특성을 분석하였다. 그 결과 SiO2의 함량이 증가할수록 상온 저항은 낮아지다가 3.0 at% 이상으로 첨가할 경우 급격히 상승하는 경향을 나타내었다. 특히 SiO2를 1.0~3.0 at% 일 때 우수한 PTC 특성을 가졌다. $1180^{\circ}C$에서는 소결 밀도가 낮아 상온 비저항이 크게 높았지만, $1200^{\circ}C{\sim}1220^{\circ}C$에서는 정상 입성장이 나타나면서 일반적인 PTC 특성을 가졌지만, $1240^{\circ}C$ 이상에서는 공정 액상이 형성되어 비정상 입성장이 일어나 상온 비저항이 크게 낮아졌다. 한편 점핑비-log(Rmax/Rmin)는 SiO2 함량이 증가할수록 높아지다가 3.0 at% 이상에서는 낮아짐을 확인하였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2010.06a
• /
• pp.18-18
• /
• 2010

전기적 에너지를 기계적 에너지로 변환하고 또한, 기계적 에너지를 전기적 에너지로 변환할 수 있는 압전 세라믹스는 압전 변압기 (piezoelectric transformer), 초음파 모터, 센서 등과 같은 응용분야에 광범위하게 사용되고 있다. 특히, 전원장치에 있어서 현재 주요 전자제품에 사용되고 있는 권선형 변압기와 같은 전자 변환기의 대체품으로 압전 세라믹스 소재의 특성을 이용한 압전변압기의 개발과 응용연구는 국내외적으로 활발히 연구되어왔다. 압전변압기는 권선형 변압기와 비교 하였을 때 누설자속이 없어 노이즈 발생이 없고, 공진주파수만을 이용하므로 출력의 파형이 정현파에 가까워 고조파 잡음이 없으며, 불연성의 특징을 가지고 있다. 추가적으로 압전 변압기는 소형화, 슬림화, 경량화가 가능하며 90%이상의 높은 효율을 얻을 수 있다. 또한, 단판형 압전변압기의 출력한계를 개선하기 위해 높은 승압비와 고출력을 갖는 적층타입의 압전변압기가 제안되었다. 압전변압기용 조성 세라믹스는 높은 에너지 변환효율을 위해서 전기기계결합계수 ($k_p$)가 커야 하며, 발열에 의한 온도 상승을 억제하기 위하여 기계적 품질계수(Qm)가 큰 것이 바람직하다. 또한, 높은 전류를 발생하기 위해서는 유전상수가 커 압전변압기의 출력측 정전용량을 크게 하여야한다. 이러한 압전변압기의 제작 조건을 위해 우수한 압전 및 유전특성을 갖는 PZT계 세라믹스가 주로 사용 되어져 왔다. 그러나, PZT계 세라믹스의 우수한 압전 및 유전특성에도 불구하고 $1000^{\circ}C$에서 급격히 휘발하는 PbO의 성질 때문에 환경적으로나 인체의 건강문제로 인해 전세계적으로 그 사용량을 제한하고 있다. 또한 적층 압전변압기의 구조적 특성상 내부전극과 함께 소결하여야 하는데, 이때 소결온도가 높으면 값비싼 Pd합량이 높은 전극을 사용하여야 한다. Pd함량이 10%미만인 Ag/Pd 전극을 사용하기 위해서는 $950^{\circ}C$ 이하에서 저온소결이 가능한 세라믹스 제조가 필수적이라 할 수 있다. 소결온도를 낮추는 방법으로는 다른 물질들을 치환하여 소결온도를 낮추는 방법과 미세분말을 만들어 그레인사이즈를 미세화 하는 방법들이 있다. 많은 미세 분말 제조 방법 중에서 Attrition mill은 일반적인 ball mill에 비해 분말의 입도를 미세하게 할 수 있어 증가된 분말의 비표면적에 의하여 반응을 촉진시킴으로써 저온소결이 가능한 세라믹스를 만들 수 있다. 따라서 본 연구에서는 소결온도가 낮으면서도 유전 및 압전특성이 우수한 조성을 사용하여 적층 압전변압기를 제작하여 전기적 특성을 조사하였다.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.16 no.2
• /
• pp.17-24
• /
• 2012

Tetrahydrotricyclopentadiene(below THTCPD) isomer is a good candidate materials for the high performance liquid fuel component because of its high density and heat of combustion value. The object of this study was to find out the proper reaction condition to improve the fluidity of THTCPD which is solid state at room temperature. Therefore, we have carried out isomerization reactions using aluminum chloride in the varying reaction condition such as reaction temperature and solvents. The results showed that when using aluminum chloride catalyst, THTCPD isomerization reaction was more active in the polar halogenated reaction media such as dichloromethane(methylene chloride: MC), 1,2-dichloroethane(ethylene chloride: EC) and chloroform than in non-polar hydrocarbon media such as n-Hexnae and toluene and was effected by reaction temperature variation.

• Journal of the Microelectronics and Packaging Society
• /
• v.9 no.2
• /
• pp.49-54
• /
• 2002

Cobalt silcides thin films were prepared on Poly-Si/$SiO_2$/Si substrates by Co metal depostion using E-beam evaporation method and rapid thermal annealing for the application of inkjet printing heater. The crystal phases and composition distributions of the films were investigated as functions of the rapid thermal annealing (RTA) temperatures (600~$900^{\circ}C$) and times (20~40 sec). The high temparature thermal stability was also investigated by the analysis of sheet resistance and crystalline properties. The stable $CoSi_2$ phases were obtained by the RTA annealing at $800^{\circ}C$ for 20 seconds showing $0.8 \Omega /\Box$ of sheet resitance. However, the sheet resistances were sharply increased at below $700^{\circ}C$ due to changes of crystalline phases. The temperature resistance coefficient of heating elements was found to be about $0.0014/^{\circ}C$, and the obtained cobalt silicided films can be applied to the printer heating elements.