• Title/Summary/Keyword: Salt core

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Preparation and Characteristics of Ceramic Composite Powders Coated with $Al_2O_3$: (I) Hydrolysis of Mixed Aluminum Salt Solution for Coating ($Al_2O_3$로 피복시킨 세라믹 복합분체의 제조 및 특성 : (I) 피복용 혼합 알루미늄 염 용액의 가수분해)

  • 현상훈;정형구
    • Journal of the Korean Ceramic Society
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    • v.27 no.7
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    • pp.851-860
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    • 1990
  • The hydrolysis-precipitation reaction of mixed aluminum salt solutions of aluminum sulfate, aluminum nitrate, and urea has been investigated to obtain narrow-sized and unagglomerated fine spherical precipitates of aluminum hydroxide required for coating core particles. The hydrolysis-precipitatin reaction could be controlled to be appropriate to coating processes by usign urea as a pH control-agent. As the concetration of total Al3+ ion and the molar ratio of SO42-/Al3+ in starting solutions became smaller and also as the vol. ratio of water/solution for hydrolyzing mixed aluminum salt solution became larger, the morphology of precipitates tended to be more unagglomerated and spherical, while their size(0.5longrightarrow0.05${\mu}{\textrm}{m}$) to be smaller. The optimum hydrolysis condition for coating processes was to hydrolyze the mixed aluminum salt solution, in which the molar ratio of SO42-/Al3+ was 0.75, while the amount of water corresponding to the vol. ratio of water/solution of 15. The precipitate was the aluminum hydroxide which sulfate ions were strongly adsorbed on and the maximum yield in the hydrolysis-precipitation reaction was about 20%.

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Modified Adaptive Switching Median Filter using Noise Density in Salt and Pepper Noise Environment (Salt and Pepper 잡음 환경에서 잡음 밀도를 이용한 변형된 적응 스위칭 메디안 필터)

  • Kwon, Se-Ik;Kim, Nam-Ho
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2015.10a
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    • pp.916-918
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    • 2015
  • Image processing is being spotlighted as an important sector with increasingly diverse applications as the society advances into a sophisticated digital information age. Especially, the image restoration as the core technology of image processing, many studies are being progressed. In this paper, in order to restore the damaged image in the Salt and Pepper noisy environment, a modified adaptive switching median filter where the size of local mask can be varied according to the noise density was proposed. And using the PSNR as the standard for objective decision making of the improvement effect, it was compared with the existing methods.

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Burnable Absorber Design Study for a Passively-Cooled Molten Salt Fast Reactor

  • Nariratri Nur Aufanni;Eunhyug Lee;Taesuk Oh;Yonghee Kim
    • Nuclear Engineering and Technology
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    • v.56 no.3
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    • pp.900-906
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    • 2024
  • The Passively-Cooled Molten Salt Fast Reactor (PMFR) is one of the advanced design concepts of the Molten Salt Fast Reactor (MSFR) which utilizes a natural circulation for the primary loop and aims to attain a long-life operation without any means of fuel reprocessing. For an extended operation period, it is necessary to have enough fissile material, i.e., high excess reactivity, at the onset of operation. Since the PMFR is based on a fast neutron spectrum, direct implementation of a burnable absorber concept for the control of excess reactivity would be ineffective. Therefore, a localized moderator concept that encircles the active core has been envisioned for the PMFR which enables the effective utilization of a burnable absorber to achieve low reactivity swing and long-life operation. The modified PMFR design that incorporates a moderator and burnable absorber is presented, where depletion calculation is performed to estimate the reactor lifetime and reactivity swing to assess the feasibility of the proposed design. All the presented neutronic analysis has been conducted based on the Monte Carlo Serpent2 code with ENDF/B-VII.1 library.

AMBIDEBTER Nuclear Complex - A Credible Option for Future Nuclear Energy Applications (AMBIDEXTER 원자력 복합체 - 신뢰성 있는 미래 원자력에너지 이용 방안)

  • 오세기;정근모
    • Proceedings of the Korea Society for Energy Engineering kosee Conference
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    • 1998.05a
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    • pp.235-242
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    • 1998
  • Aiming at one of decisive alternatives for long term aspect of nuclear power concerns, an integral and closed nuclear system, AMBIDEXTER (Advanced Molten-salt Break-even Inherently-safe Dual-mission Experimental and TEst Reactor) concept is under development. The AMBIDEXTER complex essentially comprises two mutually independent loops of the radiation/material transport and the heat/energy conversion, centered at the integrated reactor assembly, which enables one to utilize maximum benefits of nuclear energy under minimum risks of nuclear radiation. And it provides precious radioisotopes and radiation sources from its waste stream. Also the reactor operates at very low level of fission products inventory throughout its lifetime. The nuclear and thermalhydraulic characteristics of the molten TH/$^{233}$ U fuel salt extend the capability of the self-sustaining AMBIDEXTER fuel cycle to enhance resource security and safeguard transparency. The reactor system is consisted of a single component module of the core, heat exchangers and recirculation pumps with neither pipe connections nor active valves in between, which will significantly improve inherent features of nuclear safety. States of the core technologies associated with designing and developing the AMBIDEXTER concept are mostly available in commercialized form and thus demonstration of integral aspects of the concept should be the prime area in future R&D programs.

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Enhanced photo-Fenton degradation of tetracycline using TiO2-coated α-Fe2O3 core-shell heterojunction

  • Zheng, Xiaogang;Fu, Wendi;Kang, Fuyan;Peng, Hao;Wen, Jing
    • Journal of Industrial and Engineering Chemistry
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    • v.68
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    • pp.14-23
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    • 2018
  • $TiO_2-coated$ cubic ${\alpha}-Fe_2O_3$ with mostly exposed (012) and (101) facets (${\alpha}-Fe_2O_3@TiO_2$) was fabricated using a hydrothermal route for the photo-Fenton degradation of tetracycline under visible light irradiation. $TiO_2$ coating could greatly affect the photocatalytic activity of ${\alpha}-Fe_2O_3@TiO_2$. Compared with cubic ${\alpha}-Fe_2O_3$ alone for photodegradation of tetracycline, ${\alpha}-Fe_2O_3@TiO_2$ with $TiO_2$ shell of around 15 nm exhibited higher removal efficiency of tetracycline in photo-Fenton system, and its durability was slightly affected after five cycle times under same conditions. It is ascribed to the well-matched interface between cubic ${\alpha}-Fe_2O_3$ core and $TiO_2$ shell, leading to the broadened light-absorption and the efficient separation of photo-generated electon-hole pairs. The $^{\bullet}OH$ radicals were main responsible for the advanced photocatalytic performance of ${\alpha}-Fe_2O_3@TiO_2$ in visible-light driven degradation of tetracycline.

Conceptual design of a dual drum-controlled space molten salt reactor (D2 -SMSR): Neutron physics and thermal hydraulics

  • Yongnian Song;Nailiang Zhuang;Hangbin Zhao;Chen Ji;Haoyue Deng;Xiaobin Tang
    • Nuclear Engineering and Technology
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    • v.55 no.6
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    • pp.2315-2324
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    • 2023
  • Space nuclear reactors are becoming popular in deep space exploration owing to their advantages of high-power density and stability. Following the fourth-generation nuclear reactor technology, a conceptual design of the dual drum-controlled space molten salt reactor (D2-SMSR) is proposed. The reactor concept uses molten salt as fuel and heat pipes for cooling. A new reactivity control strategy that combines control drums and safety drums was adopted. Critical physical characteristics such as neutron energy spectrum, neutron flux distribution, power distribution and burnup depth were calculated. Flow and heat transfer characteristics such as natural convection, velocity and temperature distribution of the D2-SMSR under low gravity conditions were analyzed. The reactivity control effect of the dual-drums strategy was evaluated. Results showed that the D2-SMSR with a fast spectrum could operate for 10 years at the full power of 40 kWth. The D2-SMSR has a high heat transfer coefficient between molten salt and heat pipe, which means that the core has a good heat-exchange performance. The new reactivity control strategy can achieve shutdown with one safety drum or three control drums, ensuring high-security standards. The present study can provide a theoretical reference for the design of space nuclear reactors.

A NMR Study on the Micellization of Sodium Dodecyl Sulfate in ω-Phenylalkylammonium Salt Solution (1H NMR을 이용한 ω-Phenylalkylammonium Salt의 수용액에서 Sodium Dodecyl Sulfate의 미셀에 관한 연구)

  • Oh, Jung Hee
    • Applied Chemistry for Engineering
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    • v.10 no.4
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    • pp.628-634
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    • 1999
  • The orientational binding of ${\omega}$-phenylakylammonium ions to the sodium dodecyl (SDS) micellar interface has been studied from $^{1}H\;NMR$ chemical shift data. The NMR resonaces of the methylene protons of SDS and aromatic protons embedded into the micellar interior have shown the upfield shift. The aromatic induced chemical shifts of the alkyl chain methylene protons of SDS demonstrate the deep penetration into the palisade layer by these organic salts. Alkylammonium groups have been considered to be oriented toward outside of the micellar interface. Aromatic rings have been thought to be oriented toward the micellar core. The depth of penetration by organic salts has been observed to increase with the length of alkyl chain.

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A Study on the Combined Deterioration of Concrete subjected to Freezing-Thawing and Chloride Attack (동해와 염해를 동시에 받는 콘크리트의 복합열화에 관한 연구)

  • Kim Eun-Kyum;Choi Sang-Deok
    • Proceedings of the Korea Concrete Institute Conference
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    • 2005.05b
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    • pp.225-228
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    • 2005
  • This paper was accomplished for analyzing the reason of the above deterioration happened on the deck of concrete bridge. The bridge was constructed at 660m above the sea level having more freezing and snowing days. Therefore, it is placed on the particular condition sprinkling $CaCl_2$ enough for keeping up with moderate traffic condition. When it is considered to the former condition, the bridge can be assumed to potentialities for combined deterioration with freezing-thawing under sprinkling deicing chemical. Core specimens were gathered from the concrete deck for clearing the reason of the above deterioration exactly, and it is used for various tests for measuring the compressive strength, elastic modulus, content of $Cl^-$, freezing-thawing at the fresh and salt water. As a result of freezing-thawing test, the specimen at the fresh water has over 90$\%$ of durability factor, but another specimen at 1$\%$ of salt water has 0$\%$ of durability factor at 140 cycles of the freezing-thawing. The result means that frost damage is sccelerated at the salt water. Therefore, the deterioration of the concrete deck is estimated to be occured by combined effects of freezing-thawing and chloride ion attack.

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A Study on Partial Discharge Degradation Properties of PVC Cable due to NaCl (NaCl에 의한 PVC 케이블의 부분방전 열화 특성에 관한 연구)

  • Lee, Sung Ill
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.28 no.10
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    • pp.636-641
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    • 2015
  • In this study, the partial discharge degradation properties for 2-core PVC cable($2cores{\times}1.5mm^2$ cross section, length of 10 cm, 20 cm, 30 cm) following immersion with the salt water that the 2%, 4%, 8% of NaCl is dissolved in 100 g of distilled water for 48 and 96 hours has been measured. The results of this study are as follows. When the degradation time in salt water of 2% NaCl is 48 hours, it found that the number of partial discharge increased as about 40 pps, 50 pps, 90 pps with increasing the length of cable to 10 cm, 20 cm, 30 cm. In case the concentration and degradation time is same, the inception and extinction voltage decreased with increasing the length of cable. When the degradation time in salt water is 96 hours and the length of cable is 20 cm, it found that the number of partial discharge decreased as 3,000 pps, 500 pps, 100 pps with increasing the concentration of NaCl to 2%, 4%, 8%.