• 한국수소및신에너지학회논문집
• /
• 제28권6호
• /
• pp.657-662
• /
• 2017

This paper presents the reversible electrolysis characteristics of a solid oxide fuel cell (SOFC) using a $10{\times}10cm^2$ anode supported planar cell with an active area of $81cm^2$. In this work, current-voltage characteristic test and reversible electrolysis cycle test were carried out sequentially for 2,114 hours at a furnace temperature of $700^{\circ}C$. The current-voltage characteristics for reversible electrolysis mode was measured at a current of ${\pm}26.7A$ under various $H_2O$ utilization conditions. The reversible electrolysis cycle was performed 50 times at a current of ${\pm}32.4A$. As a result, The performance degradation of SOEC mode was larger than that of SOFC mode.

• 반도체디스플레이기술학회지
• /
• 제6권1호
• /
• pp.53-57
• /
• 2007

In this paper, the intelligent estimation algorithm is developed for residual quantity estimate of lithium secondary cell and we suggest the control algorithm to get battery SOC through thermal modeling of electric cell. Lithium secondary cell gives cycle life, charge characteristic, discharge characteristic, temperature characteristic, self-discharge characteristic and the capacity recovery rate etc. Therefore, we make an accurate estimate of the capacity of battery according to thermal modeling to know the capacity of electric cell that is decreased by various special quality of lithium secondary cell. And we show effectiveness through comparison of value as result that use simulation and fuzzy logic.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2003년도 춘계학술대회 논문집 센서 박막재료 반도체 세라믹
• /
• pp.291-294
• /
• 2003

The circuit substrate was made from the Low Temperature Cofired Ceramics(LTCC) that a $\varepsilon_\gamma$ was 7.8. Accumulated Varactor and the low noise transistor which were a Surface Mount Device-type element on LTCC substrate. Let passive element composed R, L, C with strip-line of three dimension in the multilayer substrate circuit inside, and one structure accumulate band-pass filter, resonator, a bias line, a matching circuit, and made it. Used Screen-Print process, and made Strip-line resonator. A design produced and multilayer-type VCO(Voltage Controlled Oscillator), and recognized a characteristic with the Spectrum Analyzer which was measurement equipment. Measured multilayer structure VCO is oscillation frequency 1292[MHz], oscillation output -28.38[dBm], hamonics characteristic -45[dBc] in control voltage 1.5[V], A phase noise is -68.22[dBc/Hz] in 100 KHz offset frequency. The oscillation frequency variable characteristic showed 30[MHz/V] characteristic, and consumption electric current is approximately 10[mA].

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.1
• /
• pp.515-518
• /
• 2004

The Piezoelectric ceramics for AE(Acoustic Emission) sensor are desired large electromechanical coupling factor, high mechanical quality factor and good characteristic resonance frequency. In this study, the empirical formula of specimens is used $0.9Pb(Zr_xTi_{1-x})O_3-0.1Pb(Mn_{1/3}Nb_{1/3}Sb_{1/3})O_3$ (PZT-PMNS). The piezoelectric and dielectric characteristic are investigated by sintering temperature and value of x as functions of $Ti^{2+},\;Zi^{2+}$ mol rate. MPB(morphotropic Phase boundary) is defined in the x=0.522. Because it is appeared to the best piezoelectric and dielectric characteristic in the x=0.522, it can be application by AE sensor. PZT-PMNS ceramics without pre-amplifier and filter are tested for detecting of arc signal. The detection characteristic is evaluated wave form, frequency distribution.

• 한국지반공학회논문집
• /
• 제36권10호
• /
• pp.33-39
• /
• 2020

심층 처분 방식은 고준위폐기물을 처분하기 위한 가장 적합한 대안으로 고려되어지고 있다. 고준위폐기물은 공학적방벽시스템에 의해 지하 500~1,000m 깊이의 암반층에 처분된다. 공학적방벽시스템의 구성 요소로는 처분용기, 완충재, 뒷채움재 및 갭채움재가 있다. 이 중 벤토나이트 완충재는 지하수 유입으로부터 처분용기를 보호하고, 방사성 핵종 유출을 저지하는 역할을 하기에 심층 처분시스템에 있어 매우 중요하다고 할 수 있다. 초기에는 처분용기로부터 발생하는 고온의 열량으로 인해 완충재의 포화도는 감소하지만, 그 후 주변 암반으로부터 유입되는 지하수로 인해 완충재의 포화도는 증가한다. 이렇듯 완충재의 불포화 거동 특성은 공학적방벽의 전체 안전성을 좌우할 수 있는 중요한 입력자료이다. 국내의 경우 경주에서 생산되는 벤토나이트가 완충재의 주요 후보물질로 고려될 수 있는데 국내 벤토나이트 완충재의 온도를 고려한 불포화 거동 특성에 대한 연구는 매우 미진한 상황이다. 따라서 본 연구에서는 국내 압축 벤토나이트 완충재의 온도 증가에 따라 함수비가 일정한 조건에서의 함수특성곡선을 도출하였으며, 시험 값과 온도가 고려된 수정 van-Genuchten 모델 값과의 상대오차는 약 2%를 나타냈다.

• 한국화재소방학회논문지
• /
• 제30권1호
• /
• pp.24-30
• /
• 2016

자연발화 특성은 가연성물질의 취급 및 화재예방을 위한 중요한 인자이다. 본 연구는 ASTM D2155식 발화온도 측정장치를 사용하여 Ethylene Glycol과 물을 혼합한 시료의 자연발화 특성을 고찰하였다. Ethylene Glycol 100%는 시료량 $75{\mu}l{\sim}160{\mu}l$의 범위에서 $434^{\circ}C$로 나타났다. 물을 첨가하여 Ethylene Glycol 80%와 물 20%를 혼합한 시료는 시료량 $100{\mu}l{\sim}125{\mu}l$의 범위에서 $434^{\circ}C$로 나타났고, Ethylene Glycol 60%와 물 40%를 혼합한 시료에서 시료량 $120{\mu}l{\sim}160{\mu}l$의 범위에서 $437^{\circ}C$로 나타났다. 또한 순간발화온도는 시료량 $125{\mu}l$에서 각각 $579^{\circ}C$, $595^{\circ}C$ 및 $611^{\circ}C$를 구하였으며, 물의 비율이 증가할수록 자연발화온도와 순간발화온도는 증가되는 것으로 나타났다.

• 한국전기전자재료학회논문지
• /
• 제36권6호
• /
• pp.570-575
• /
• 2023

Demand and necessity for eco-friendly offshore wind farms have been increasing. Research on submarine cables is constantly being considered for a reliable and stable power transmission. This study aimed to evaluate the thermal aging characteristic of submarine cables inside the J-tube of offshore wind farms. In this study, a submarine cable was set in three sections: The first is the part exposed to the air above the sea level at high temperature. The second is the section exposed to repeated temperature fluctuation as the sea level rises and falls. The third is the part submerged at low temperature below the sea level. Aged samples were tested by using the method of electrical evaluation to obtain insulation characteristics. The experimental results show that the dielectric breakdown of the sample with temperature fluctuation was 7% lower than the sample with a constant temperature; thereby, demonstrating that the section where the temperature fluctuation occurred in the submarine cables was weaker than the other. The sections of submarine cable with temperature fluctuations are believed as a weak point during operation; therefore, this part should be monitored preferentially.

• 한국태양에너지학회:학술대회논문집
• /
• 한국태양에너지학회 2011년도 추계학술발표대회 논문집
• /
• pp.214-219
• /
• 2011

Today, various activities to save energy are being conducted around the world. Even in our country, carbon reduction policy is being conducted for low carbon green growth and with this movement, effort to replace energy sources by recognizing the problems on environment pollution and resource exhaustion due to the indiscrete usage of fossil fuel is being made. Therefore, active study on renewable energy is in progress as part of effort to replace the energy supply through fossil fuel and solar ray industry has rapidly developed receiving big strength of renewable energy policies. The conclusion of this study measuring the surface temperature change of single crystal and polycrystalline PV module in green roof system and non-green roof system aspect are as follows. There was approximately $4^{\circ}C$ difference in PV module temperature in green roof system and non-green roof system aspect and this has the characteristic to decrease 0.5% when the temperature rises by $1^{\circ}C$ when the front side of the module is $20^{\circ}C$ higher than the surrounding air temperature following the characteristic of solar cells. It can be concluded that PV efficiency will be come better when it is $4^{\circ}C$ lower. Also, in result of temperature measurement of the module back side, there was $5^{\circ}C$ difference of PV module installed on the PV module back side and green roof system side on the 5th, $3^{\circ}C$ on the 4th, $2^{\circ}C$ on the 5th to show decreasing temperature difference as the air temperature dropped, but is judged that there will be higher temperature difference due to the evapotranspiration latent heat effect of green roof system floor side as the temperature rises. Based on this data, it is intended to be used as basic reference to maximize efficiency by applying green roof system and PV system when building non-green roof system flat roof.

• KIEE International Transactions on Electrophysics and Applications
• /
• 제4C권2호
• /
• pp.51-54
• /
• 2004

In this paper, the thermal and mechanical properties of elastic epoxy for the application of high voltage products were investigated. Glass transition temperature (Tg) of elastic epoxies cannot be found from room temperature to 20$0^{\circ}C$ by DSC (Differential Scanning Calorimetry). Weight reduction occurred at 285$^{\circ}C$ and 451$^{\circ}C$ according to a thermogravimeter. The first temperature was affected by addictives and the second by epoxies characteristic. Maximum tensile strain showed 28.3kgf/$\textrm{cm}^2$/$\textrm{cm}^2$ at 20% of mechanical stress in addictives 35 (phr). The SEM (Scanning electron microscope) micrograph of the fracture surface observed void and tearing of elastic epoxy at addictives 35 (phr). On the other side, the SEM micrograph of the rigid epoxy showed a broken trace.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2004년도 하계학술대회 논문집 C
• /
• pp.1817-1819
• /
• 2004

From the plasma application point of view, electron temperature and density are one of the most important parameters for plasma process. But it is only available to control plasma by adjusting external factors like gas pressure and input power. In this paper, pulse-modulated plasma is generated by modulating 13.56GHz RF power with 1, 5, 10kHz pulse. And Langmuir probe technique is used to study the distribution of electron temperature and density. When modulated pulse is off, electron temperature decreases gradually in form of exponential decay. The value t of exponential decay slope is 33.619, 13.834, 10.803 in 1kHz. 5kHz. 10kHz. This implies that this method can be used to control electron temperature and density.