• Title/Summary/Keyword: energy degradation

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Storage Life Estimation of Next Infrared Flare Material (차기 적외선 섬광제 저장수명 예측)

  • Back, Seungjun;Son, Youngkap;Kim, Namjin;Kwon, Taesoo
    • Journal of the Korea Institute of Military Science and Technology
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    • v.19 no.3
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    • pp.311-318
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    • 2016
  • This paper shows storage life estimation of next IR(infrared) flare material through accelerated degradation tests. Three temperature conditions for the accelerated degradation tests are 55, 65 and $75^{\circ}C$. Six performances of IR flare material are burning time, IR peak/continuous Intensity, total energy of near/mid-IR and color ratio, and they were measured after the tests. Storage life of the IR flare material was estimated through both analyzing the degradation data of those performances and applying distribution-based degradation models to the data. Over 30 years of storage life at $20^{\circ}C$ is estimated in terms of IR peak intensity with reliability 0.99 and confidence level 99 %. Additionally, 10 years of storage period at $21^{\circ}C$ would be equivalent to 68 days of accelerated test at $65^{\circ}C$ from the activation energy in Arrhenius model.

A Study on Thermal Degradation of Poly (methyl methacrylate) (PMMA) using TGA (TGA를 이용한 Poly(methyl methacrylate) (PMMA)의 열분해 특성 연구)

  • Kim, Sang-Guk;Choi, Hyun-Gyu;Eom, Yu-Jin;Kim, Joo-Sik
    • Proceedings of the Korean Institute of Resources Recycling Conference
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    • 2005.10a
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    • pp.360-367
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    • 2005
  • PMMA has been used extensively worldwide as industrial and construction materials due to its excellent material properties. When PMMA is subject to thermal degradation, unit of monomers are detached from polymer chain and this phenomena is called unzip reaction. Therefore, PMMA thermally degrades into its monomer. Characteristics of thermal degradation of PMMA has been investigated using TGA in this research as a basic study for recovery of MMA.

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Effect of thermal conductivity degradation on the behavior of high burnup $UO_2$ fuel

  • Lee, Byung-Ho;Koo, Yang-Hyun;Sohn, Dong-Seong
    • Proceedings of the Korean Nuclear Society Conference
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    • 1996.05c
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    • pp.265-270
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    • 1996
  • The temperature distribution in the pellet was obtained from beginning the general heat conduction equation. The thermal conductivity of pellet used the SIMFUEL data that made clear the effect of burnup on the thermal conductivity degradation. Since the pellet rim acts as the thermal barrier to heat flow. the pellet was subdivided into several rings in which the outer ring was adjusted to play almost the same role as the rim. The local burup in each ring except the outer ring was calculated from the power depression factor based on FASER results. whereas the rim burnup at the outer ring was achieved by the pellet averaged burnup based on the empirical relation. The rim changed to the equivalent Xe film so the predicted temperature shooed the thermal jump across the rim. The observed temperature profiles depended on linear heat generation rate. fuel burnup. and power depression factor. The thermal conductivity degradation modelling can be applied to the fuel performance code to high burnup fuel,

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Further Electrochemical Degradation of Real Textile Effluent Using PbO2 Electrode

  • Wang, Chao;Tian, Penghao
    • Journal of Electrochemical Science and Technology
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    • v.12 no.2
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    • pp.266-271
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    • 2021
  • A commercial PbO2 electrode was adopted as the anode for the electrochemical degradation of the real textile effluent with the initial COD of 56.0 mg L-1 and the stainless steel plate as the cathode. The effect of the initial pH, the electrolyte flow rate and the cell voltage on the COD, the current efficiency and the energy consumption were investigated without the addition of NaCl or Na2SO4. The experimental results illustrated that the PbO2 electrode can reduce the COD of the textile effluent from 56.0 mg L-1 to 26.0 mg L-1 with the current efficiency of 86.1% and the energy consumption of 17.5 kWh kg-1 (per kilogram of degraded COD) under the optimal operating conditions. Therefore PbO2 electrode as the anode was promising to further electrochemically degrade the real textile effluent.

Radiation-induced thermal conductivity degradation modeling of zirconium

  • Sangil Choi;Hyunmyung Kim;Seunghwan Yu
    • Nuclear Engineering and Technology
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    • v.56 no.4
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    • pp.1277-1283
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    • 2024
  • This study presents a radiation-induced thermal conductivity degradation (TCD) model of zirconium as compared to the conventional UO2 TCD model. We derived the governing factors of the radiation-induced TCD model, such as maximum TCD value and temperature range of TCD. The maximum TCD value was derived by two methods, in which 1) experimental result of 32 % TCD was directly utilized as the maximum TCD value and 2) a theoretical approach based on dislocation was applied to derive the maximum TCD value. Further, the temperature range of TCD was determined to be 437-837 K by 1) experimental results of post-annealing of irradiation hardening as compared to 2) the rate theory and thermal equilibrium. Consequently, the radiation-induced TCD model of zirconium was derived to be $f_r=1-{\frac{0.32}{1+{\exp}\,\{(T-637)/45\}}}$. Because the thermal conductivity of zirconium is one of the factors determining the storage and transport system, this newly proposed model could improve the safety analysis of spent fuel storage systems.

Degradation Characteristics according to Encapsulant Materials Combining with Transparent Backsheet on the Mini Shingled Si Photovoltaic Modules (투명 백 시트와 봉지재 물질 조합에 따른 소형 슁글드 실리콘 태양전지 모듈의 열화 특성 분석)

  • Son, Hyung Jin;Kim, Sung Hyun
    • Current Photovoltaic Research
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    • v.8 no.1
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    • pp.12-16
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    • 2020
  • This study investigates the degradation characteristics of different material types of ethyl vinyl acetate (EVA) and polyolefin (POE) with combining transparent backsheet. To this end, we fabricated samples with structure of glass/encapsulant/transparent backsheet for each type of encapsulants, and shingled Si modules with the same structure. The samples were then subjected to accelerated test by storing under damp heat condition of 85℃ and 85% RH. As a result, encaplsulant discoloration was observed, which the transmittance of the samples with EVA decreased in a rapid rate than the samples with POE. The discoloration also affected a power degradation of the shingled modules with a reduction of current density, resulting that the module with EVA showed more drop on the efficiency than the modules with POE. Furthermore, corrosion of the soldered ribbon caused by acetic acid produced from the degraded EVA also contributed in fill factor reduction.

Effect of Fast Charging Mode on the Degradation of Lithium-Ion Battery: Constant Current vs. Constant Power (정전류/정출력 고속충전 방식에 따른 리튬이온전지의 열화 비교 연구)

  • Park, Sun Ho;Oh, Euntaek;Park, Siyoung;Lim, Jihun;Choi, Jin Hyeok;Lee, Yong Min
    • KEPCO Journal on Electric Power and Energy
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    • v.6 no.2
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    • pp.173-179
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    • 2020
  • Electric vehicles (EVs) using lithium secondary batteries (LIBs) with excellent power and long-term cycle performance are gaining interest as the successors of internal combustion engine (ICE) vehicles. However, there are few systematic researches for fast charging to satisfy customers' needs. In this study, we compare the degradation of LIB where its composition is LiNi0.5Co0.2Mn0.3/Graphite with the constant current and constant power-charging method. The charging speed was set to 1C, 2C, 3C and 4C in the constant current mode and the value of constant power was calculated based on the energy at each charging speed. Therefore, by analyzing the battery degradation based on the same charging energy but different charging method; CP charging method can slow down the battery degradation at a high rate of 3C through the voltage curve, capacity retention and DC-IR. However, when the charging rate was increased by 4C or more, the deviation between the LIBs dominated the degradation than the charging method.

Comparative Genomic Analysis and BTEX Degradation Pathways of a Thermotolerant Cupriavidus cauae PHS1

  • Chandran Sathesh-Prabu;Jihoon Woo;Yuchan Kim;Suk Min Kim;Sun Bok Lee;Che Ok Jeon;Donghyuk Kim;Sung Kuk Lee
    • Journal of Microbiology and Biotechnology
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    • v.33 no.7
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    • pp.875-885
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    • 2023
  • Volatile organic compounds such as benzene, toluene, ethylbenzene, and isomers of xylenes (BTEX) constitute a group of monoaromatic compounds that are found in petroleum and have been classified as priority pollutants. In this study, based on its newly sequenced genome, we reclassified the previously identified BTEX-degrading thermotolerant strain Ralstonia sp. PHS1 as Cupriavidus cauae PHS1. Also presented are the complete genome sequence of C. cauae PHS1, its annotation, species delineation, and a comparative analysis of the BTEX-degrading gene cluster. Moreover, we cloned and characterized the BTEX-degrading pathway genes in C. cauae PHS1, the BTEX-degrading gene cluster of which consists of two monooxygenases and meta-cleavage genes. A genome-wide investigation of the PHS1 coding sequence and the experimentally confirmed regioselectivity of the toluene monooxygenases and catechol 2,3-dioxygenase allowed us to reconstruct the BTEX degradation pathway. The degradation of BTEX begins with aromatic ring hydroxylation, followed by ring cleavage, and eventually enters the core carbon metabolism. The information provided here on the genome and BTEX-degrading pathway of the thermotolerant strain C. cauae PHS1 could be useful in constructing an efficient production host.

Evaluation of Hydride Effect on Fuel Cladding Degradation (피복관 열화거동에 미치는 수소화물 영향 평가)

  • Kim, Hyun-Gil;Kim, Il-Hyun;Park, Sang-Yoon;Park, Jeong-Yong;Jeong, Yong-Hwan
    • Korean Journal of Metals and Materials
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    • v.48 no.8
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    • pp.717-723
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    • 2010
  • The degradation behavior of fuel cladding is a very import concern in nuclear power generation, because the operation of nuclear plants can be limited by fuel cladding degradation. In order to evaluate the hydride effect on failure of zirconium fuel claddings, a ring tensile test for the circumferential direction was carried out at room temperature for claddings having different hydride characteristics such as density and orientation; microstructural evaluation was also performed for those claddings. The circumferential failure of the claddings was promoted by increasing the hydride concentration in the matrix; however, the failure of the claddings was affected by the hydride orientation rather than by the hydride concentration in the matrix. From fracture surface observation, the cladding failure during the ring tensile test was matched with the hydride orientation.