• Title/Summary/Keyword: thermal impact

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Safety Evaluation of a Shipping Capsule for Special Form Radioisotope (특수형 방사성 동위원소 운반캡슐의 안전성 평가)

  • Lee, Ju-Chan;Seo, Ki-Seog;Ku, Jeong-Hoe;Bang, Kyoung-Sik;Han, Hyon-Soo;Park, Seong-Won
    • Journal of Radiation Protection and Research
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    • v.26 no.1
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    • pp.35-43
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    • 2001
  • All of sealing capsules to transport a special form radioactive material should be designed and fabricated in accordance with the design criteria prescribed in IAEA standards and domestic regulations. The objective of this study is to demonstrate the safety of a shipping capsule for $^{192}Ir$ special form radioisotope which produced in the HANARO. The safety tests were carried out for the impact, percussion, bending and heat test conditions. And leakage tests were carried out before and after the each test. Also, the safety analyses wert performed using computer codes in order to verify the test results. The capsule showed slight scratches and deformation, and maintained its structural and thermal integrities in all tests without any severe damage or melting. It also met the allowable limits of leakage rate after each test. Therefore, it has been verified that the capsule was designed and fabricated to meet all requirements for the special form.

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A Study on the Behaviors of Inorganic Fillers in Recycling of the Waste Agricultural Plastic Films (I) - Effects on the Addition of Calcium Carbonate and Calpet - (무기(無機) 충진재(充鎭材) 첨가(添加)에 따른 재생(再生) 폐(廢)비닐의 특성(特性) 분석(分析) (I) - 중탄과 칼펫의 첨가(添加)에 따른 영향(影響) -)

  • Ahn, Tae-Kwang;Son, Sang-Jin;Kim, Hea-Tae;Kim, Myoung-Ho;Zhou, Gong-Ming;Chen, De-Zhen
    • Resources Recycling
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    • v.17 no.3
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    • pp.10-20
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    • 2008
  • In order to study the behaviors of inorganic fillers in recycling of the waste agricultural plastic films, the washed PE fluffs from Shihwa and Jungeup Plant belonging to ENVICO were used respectively. First of all, the test pellets were manufactured by adding of inorganic fillers suchlike calcium carbonate and calpet by certain portions to PE fluffs and then the tested sheets were formed. The mechanical and thermal properties of the samples were measured and compared with others. The items measured were tensile, flexural, Izod impact, HDT, MFT, and so on. Morphologies were also investigated for various samples using the SEM. Finally, optimum ratios between recycled PE and inorganic additives were found out for the best products in physical condition as well as in economic point of view.

Phyllite as a New Flame Retardant Synergist for ABS Resin Containing Bromine Flame Retardant (브롬계 난연제를 사용한 ABS 수지에 대한 신규 난연 상승작용제로시의 천매암)

  • Kim, Seog-Jun
    • Elastomers and Composites
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    • v.41 no.3
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    • pp.172-181
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    • 2006
  • Flame retardant synergism of phyllite was studied in ABS resins containing brominated flame retardant(tetrabromobisphenol A(TBBA) or brominated epoxy oligomer(BEO)) and antimony trioxide($Sb_2O_3)$. Talc was used for the comparison purpose. ABS compounds were manufactured by a twin-screw co-rotating extruder and subsequently injection molded into several specimen for mechanical and thermal properties. Flame retardancy of ABS compounds measured by UL 94 vertical test with 1.6 mm thick bar specimen was enhanced by the replacement of antimony trioxide into phyllite or talc in the range of 12.5%(0.5 wt%) to 37.5%(1.5 wt%). Phyllite showed better synergistic effect comparing with talc especially for BEO. Only phyllite enhanced the flowability of ABS compounds. Notched Izod impact strength decreased with the proportion of phyllite or talc content. Phyllite could replace the antimony trioxide up to the content of 25%(1 wt%) to give better flame retardancy and flowability without darkening problem.

A Study on the Cost Analysis of risk facilities using e-Consequence Analysis - Focusing Steel pipe Industry (e-CA(e-Consequence Analysis)를 활용한 위험설비의 비용 분석에 관한 연구 : 강관제조업 사례를 중심으로)

  • Kwon, Hyeok Min;Hwang, Yong Woo;Lee, Ik Mo;Chun, Young Woo;Choi, Young Hun
    • Journal of the Korea Safety Management & Science
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    • v.20 no.3
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    • pp.27-36
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    • 2018
  • The steel pipe manufacturing industry deals with facilities and materials. Especially thermal facilities are close to vapor cloud explosion (VCE) and may cause secondary damage to facilities because they deal with corrosive substances such as hydrofluoric acid, sulfuric acid and acid, fire, explosion, leakage etc. It is in danger. In this study, hazard identification method was conducted using HAZOP techniques and quantitative risk analysis was conducted using e-CA, a program that supports accident impact analysis. Equipment in the influence range of ERPG - 3 was determined to be a facility requiring replacement. It was decided that neutralization is necessary using slaked lime. Based on the cost of loss, We presented the proper replacement which is the timing of the dangerous facility. As a result, It was ideal to replace the facilities with 20 years of heat treatment facilities, one year of hydrofluoric acid storage tank, 20 years of sulfuric acid storage tank, and 5 years of hydrochloric acid storage tank.

The Study for Cell Morphology with Gas Cocktail in Microcellular Foaming Process (초미세 발포 공법 시 가스 혼합에 따른 셀 형상 연구)

  • Cha Sung Woon;Yoon Jae Dong;Lee Yoon Sung;Kim Hak Bin
    • Journal of the Korean Society for Precision Engineering
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    • v.22 no.6 s.171
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    • pp.168-174
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    • 2005
  • Nowadays, the companies use polymer materials for many purposes fur they have many advantages. The costs of these materials take up too high a proportion of the overall cost of products that use these materials as their major material. It is advantage for polymer industries to reduce these costs. The microcellular foaming process was developed in the early 1980s to solve this problem and proved to be quite successful. Microcellular foaming process uses inert gases such as $CO_2,\;N_2$. As these gases solve into polymer matrices, many properties are changed. The microcellular foaming process makes the glass transition temperature of polymers to low, and diminish the residual stress of polymer matrices. Besides, the microcellular foaming process has several merits, impact strength elevation, thermal insulation, noise insulation, and raw material saving etc. In previous research, many facts of microcellular foaming process are founded its characteristics. But previous researcher found the characteristics of microcellular foaming process with pure gas, for example $CO_2,\;N_2$ and so on, they did not found the characteristics of microcellular foaming process with one more gases. If one more gases inlet the resin, the characteristics of microcellular foaming process is changed very amazingly. In this paper, discuss on the characteristics of microcellular foaming process wi th gas cocktail about cell morphology.

Effects of Oxygen Plasma-treated Graphene Oxide on Mechanical Properties of PMMA/Aluminum Hydroxide Composites (산소 플라즈마 처리된 그래핀 산화물이 PMMA/수산화알루미늄 컴포지트의 기계적 물성에 미치는 영향)

  • Kim, Hyo-Chul;Jeon, Son-Yeo;Kim, Hyung-Il;Choi, Ho-Suk;Hong, Min-Hyuk;Choi, Ki-Seop
    • Polymer(Korea)
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    • v.35 no.6
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    • pp.565-573
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    • 2011
  • The nanocomposites containing graphene oxide (GO) were prepared in order to improve the mechanical properties of poly(methyl methacrylate)/aluminum hydroxide (PMMA/AH) composites. GO was prepared from graphite by oxidation of Hummers method followed by exfoliation with thermal treatment. The surface of GO was modified by oxygen plasma in various exposure times from 0 to 70 min to improve interfacial compatibility. Compared with PMMA/AH composites, the nanocomposites containing GO modified with oxygen plasma for the exposure time up to 50 min showed significant increases in flexural strength, flexural modulus, Rockwell hardness, Barcol hardness, and Izod impact strength. The morphology of fracture surface showed an improved interfacial adhesion between PMMA/AH composites and GO, which was properly treated with oxygen plasma. The mechanical properties of nanocomposites were deteriorated by increasing the content of GO above 0.07 phr due to the nonuniform dispersion of GO.

Castor oil based hyperbranched polyester/bitumen modified fly ash nanocomposite

  • Bhagawati, Deepshikha;Thakur, Suman;Karak, Niranjan
    • Advances in nano research
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    • v.4 no.1
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    • pp.15-29
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    • 2016
  • A low cost environmentally benign surface coating binder is highly desirable in the field of material science. In this report, castor oil based hyperbranched polyester/bitumen modified fly ash nanocomposites were fabricated to achieve the desired performance. The hyperbranched polyester resin was synthesized by a three-step one pot condensation reaction using monoglyceride of castor oil based carboxyl terminated pre-polymer and 2,2-bis (hydroxymethyl) propionic acid. Also, the bulk fly ash of paper industry waste was converted to hydrophilic nano fly ash by ultrasonication followed by transforming it to an organonano fly ash by the modification with bitumen. The synthesized polyester resin and its nanocomposites were characterized by different analytical and spectroscopic tools. The nanocomposite obtained in presence of 20 wt% styrene (with respect to polyester) was found to be more homogeneous and stable compared to nanocomposite without styrene. The performance in terms of tensile strength, impact resistance, scratch hardness, chemical resistance and thermal stability was found to be improved significantly after formation of nanocomposite compared to the pristine system after curing with bisphenol-A based epoxy and poly(amido amine). The overall results of transmission electron microscopic (TEM) analysis and performance showed good exfoliation of the nano fly ash in the polyester matrix. Thus the studied nanocomposites would open up a new avenue on development of low cost high performing surface coating materials.

Modification of RFSP to Accommodate a True Two-Group Treatment

  • Bae, Chang-Joon;Kim, Bong-Ghi;Suk, Soo-Dong;D. Jenkins;B. Rouben
    • Proceedings of the Korean Nuclear Society Conference
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    • 1996.05a
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    • pp.185-190
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    • 1996
  • RFSP is a computer program to do fuel management calculations for CANDU reactors. Its main function is to calculate neutron flux and power distributions using two-energy-group, three dimensional neutron diffusion theory. However, up to now the treatment has not been true two-group but actually "one-and-half groups". In other words, the previous (1.5-group) version of RFSP lumps the fast fission term into the thermal fission term. This is based on the POWDERPUFS-V Westcott convention. Also, there is no up-scattering term or bundle power over cell flux (H1 factor) for the fast group. While POWDERPUFS-V provides only 1.5 group properties, true two-group cross sections for the design and analysis of CAUDU reactors can be obtained from WIMS-AECL. To treat the full two-group properties, the previous RFSP version was modified by adding the fast fission, up-scatter terms, and H1 factor. This two-group version of RFSP is a convenient tool to accept lattice properties from any advanced lattice code (e.g. WIMS-AECL DRAGON, HELIOS...) and to apply to advanced fuel cycles. In this study, the modification to implement the true two-group treatment was performed only in the subroutines of the *SIMULATE module of RFSP. This module is the appropriate one to modify first, since it is used for the tracking of reactor operating histories. The modified two-group RFSP was evaluated with true two-group cross sections from WIMS-AECL. Some tests were performed to verify the modified two-group RFSP and to evaluate the effects of fast fission and up-scatter for three core conditions and four cases corresponding to each condition. The comparisons show that the two-group results are quite reasonable and serve as a verification of the modifications made to RFSP. To assess the long-term impact of the full 2-group treatment, it is necessary to simulate a long period (several months) of reactor history. It will also be necessary to implement the full two-group treatment of reactivity devices and assess the reactivity-device worths.ce worths.

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Post-fire Repair of Concrete Structural Members: A Review on Fire Conditions and Recovered Performance

  • Qiu, Jin;Jiang, Liming;Usmani, Asif
    • International Journal of High-Rise Buildings
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    • v.10 no.4
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    • pp.323-334
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    • 2021
  • Concrete structures may rarely collapse in fire incidents but fire induced damage to structural members is inevitable as a result of material degradation and thermal expansion. This requires certain repairing measures to be applied to restore the performance of post-fire members. A brief review on investigation of post-fire damage of concrete material and concrete structural members is presented in this paper, followed by a review of post-fire repair research regarding various types of repairing techniques (FRP, steel plate, and concrete section enlargement) and different type of structural members including columns, beams, and slabs. Particularly, the fire scenarios adopted in these studies leading to damage are categorized as three levels according to the duration of gas-phase temperature above 600℃ (t600). The repair effectiveness in terms of recovered performance of concrete structural members compared to the initial undamaged performance has been summarized and compared regarding the repairing techniques and fire intensity levels. The complied results have shown that recovering the ultimate strength is achievable but the stiffness recovery is difficult. Moreover, the current fire loading scenarios adopted in the post-fire repair research are mostly idealized as constant heating rates or standard fire curves, which may have produced unrealistic fire damage patterns and the associated repairing techniques may be not practical. For future studies, the realistic fire impact and the system-level structural damage investigation are necessary.

Massive MIMO with Transceiver Hardware Impairments: Performance Analysis and Phase Noise Error Minimization

  • Tebe, Parfait I.;Wen, Guangjun;Li, Jian;Huang, Yongjun;Ampoma, Affum E.;Gyasi, Kwame O.
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.13 no.5
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    • pp.2357-2380
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    • 2019
  • In this paper, we investigate the impact of hardware impairments (HWIs) on the performance of a downlink massive MIMO system. We consider a single-cell system with maximum ratio transmission (MRT) as precoding scheme, and with all the HWIs characteristics such as phase noise, distortion noise, and amplified thermal noise. Based on the system model, we derive closed-form expressions for a typical user data rate under two scenarios: when a common local oscillator (CLO) is used at the base station and when separated oscillators (SLOs) are used. We also derive closed-form expressions for the downlink transmit power required for some desired per-user data rate under each scenario. Compared to the conventional system with ideal transceiver hardware, our results show that impairments of hardware make a finite upper limit on the user's downlink channel capacity; and as the number of base station antennas grows large, it is only the hardware impairments at the users that mainly limit the capacity. Our results also show that SLOs configuration provides higher data rate than CLO at the price of higher power consumption. An approach to minimize the effect of the hardware impairments on the system performance is also proposed in the paper. In our approach, we show that by reducing the cell size, the effect of accumulated phase noise during channel estimation time is minimized and hence the user capacity is increased, and the downlink transmit power is decreased.