• Title, Summary, Keyword: Refractory

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Theoretical Analysis of Lined Pipe (Lined Pipe 이론 해석)

  • Jung, Jin-Han;Choi, Jae-Seung
    • Proceedings of the KSME Conference
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    • pp.964-968
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    • 2001
  • The refractory-lined pipe is used to protect the system from high-temperature of the internal flow. The property of the refractory has an effect upon the stress analysis for fluid catalyst cracking(FCC) unit piping design. The equivalent elastic modulus and density considering steel and refractory must be applied in the stress analysis of the system. In the research, the theoretical method to obtain the value of the equivalent property is introduced and then the parametric analysis is carried out to understand the characteristic of the material properties.

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Preparations of ASC Refractory Materials from Kaolin using Thermit Reaction (카오린으로부터 테르밋 반응을 통한 $Al_2O_3-SiC-C(ASC)$계 내화재료 합성)

  • 이온영;이용구;전병세
    • Journal of the Korean Ceramic Society
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    • v.32 no.4
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    • pp.429-435
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    • 1995
  • Al2O3-SiC-C(ASC) refractory materials were prepared from kaolin using thermit reaction. The mixed powder (A-K) for the thermit reaction was composed of Hadong kaolin, C(graphite) and Al. A-S(SiO2+C+Al) composition was also employed to compare with A-K in respect to reactability. As a result of XRD patterns of A-K sample after thermit reaction, and firing at 140$0^{\circ}C$ for 3hrs in Ar atmosphere, it was possible to use as a ASC refractory materials.

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Corrosion of Alumina-Chromia Refractory by Alkali Vapors: 1. Thermodynamic Approach

  • Lee, Kyoung-Ho;Jesse J. Brown Jr
    • The Korean Journal of Ceramics
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    • v.1 no.1
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    • pp.29-34
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    • 1995
  • Theoretical predictions were made for thermodynamically stable phases which formed when alkali(sodium and Potassium) vapors reacted with the 90% $Al_2O_3$-10% $Cr_2O_3$ refractory under coal gasifying atmosphere using the computer program of SOLGASMIX-PV. The calculation results showed that the stable compounds that formed were $X_2O$.$Al_2O_3$ and $X_2O$.$llAl_2O_3$(X=$Na^+$ or $K^+$), depending upon the alkali concentration. The presence of sulfur in gasifying atmospheres did not appear to affect the species of alkali reaction products. Alkali attack at high temperatures is likely to cause serious degradation at the hot face of the refractory, indicating that the alkali concentration is an important factor to affect the degradation of the refroctory.

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Anticancer Therapy for Breast Cancer Patients with Skin Metastases Refractory to Conventional Treatments

  • Varol, Umut;Yildiz, Ibrahim;Alacacioglu, Ahmet;Uslu, Ruchan
    • Asian Pacific Journal of Cancer Prevention
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    • v.15 no.4
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    • pp.1885-1887
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    • 2014
  • Skin metastases of breast cancer are usually late events in the course of tumor progression and signify a poor prognosis. They may remain as a therapeutic challenge especially after failure of standard treatments. Topical interventions, together with or without radiotherapy, may only palliate the symptoms temporarily. However, there may be alternative treatment modalities for unresectable breast cancer skin metastases resistant to chemotherapy and radiotherapy. There are various genetic alterations in tumors and therapeutic potential of expression patterns for factors like epidermal growth factor receptor may have important clinical implications in case of disease refractory to the conventional treatments. Here, we clarified the therapeutic options and genetic alterations in skin metastatic breast cancer patients refractory to standard chemotherapeutics.

Concomitant use of corticosteroid and antimicrobials for liver abscesses in patients with chronic granulomatous disease

  • Shin, Kyung-Sue;Lee, Mu Suk
    • Clinical and Experimental Pediatrics
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    • v.59 no.4
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    • pp.196-201
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    • 2016
  • Chronic granulomatous disease (CGD) is a rare inherited disorder caused by defective nicotinamide adenine dinucleotide phosphate oxidase enzyme and characterized by recurrent bacterial and fungal infections. Although liver abscess is a common manifestation of CGD, its management in CGD patients is not well-defined. In addition, the generalized guidelines for treating liver abscesses do not necessarily apply to CGD patients. Corticosteroids are commonly used to control granulomatous complications, such as inflammatory gastrointestinal and genitourinary lesions, in patients with CGD, Corticosteroids have also been used in combination with antimicrobials to treat refractory infections in patients with CGD. Because corticosteroids are capable of suppressing symptomatic inflammation, all potential infections must be adequately controlled prior to corticosteroid initiation. We report 3 typical CGD cases with liver abscesses refractory to conventional treatments that were successfully treated with the concomitant use of corticosteroid and antimicrobials. It remains unclear whether corticosteroid therapy is required for liver abscesses in CGD refractory to conventional treatments. However, based on our observations, use of corticosteroids in combination with optimal antimicrobials should be considered for refractory liver abscesses in CGD.

Management of Severe Fatigue Induced by Tyrosine Kinase Inhibitor in Radioiodine Refractory Thyroid Cancer (방사성요오드 불응성 갑상선암에서 티로신키나아제 억제제 투여로 유발된 중증 피로감의 관리)

  • Ahn, Byeong-Cheol
    • International journal of thyroidology
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    • v.11 no.2
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    • pp.75-77
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    • 2018
  • Tyrosine kinase inhibitor is known to prolong progression free survival in radioiodine refractory thyroid cancer patients. Fatigue/asthenia/malaise is one of most common adverse events by the tyrosine kinase inhibitor treatment, and management of the adverse event is important to keep the drug medication longer which is essential for the survival benefit. In the case report, a radioiodine refractory thyroid cancer patient receiving tyrosine kinase inhibitor experienced severe fatigue, and a pathologic fracture of right humerus occurred by slipping down which was tightly linked with the adverse event of the drug. The pathologic fracture was surgically well managed and the adverse event was well controlled by supportive managements combined with dose reduction of the tyrosine kinase inhibitor. The drug administration to the patient was kept more than 1 year without progression of the disease.

Management of patients with refractory nocturnal enuresis (치료에 반응하지 않는 야뇨증 환자의 관리)

  • Kim, Seong Cheol
    • Journal of the Korean Medical Association
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    • v.60 no.10
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    • pp.800-805
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    • 2017
  • There are two types of refractory nocturnal enuresis. The first type corresponds to patients who are refractory from initial success, and the second type refers to refractory nocturnal enuresis after long-term success, in patients who cannot discontinue medications for enuresis. In the former type, it is necessary to determine whether the timing of medications is appropriate, whether the usage of antidiuretics is appropriate, whether any lifestyle changes have taken place, and whether there are secondary causes of enuresis. In the latter type, enuretic alarm treatment should be considered initially, and it is then important to investigate whether a respiratory obstruction is present in patients with nocturnal polyuria, whether the patient is constipated, and whether patients with non-monosymptomatic nocturnal enuresis have lower urinary tract symptoms or attention deficit hyperactivity disorder.

The Influence of Sintering Atmosphere on the Reduction Behaviour of Refractory Bricks and the Basic Properties of $UO_{2}$ Pellet

  • Lee, Seung-Jae;Kim, Kyu-Tae;Chung, Bum-Jin
    • The Korean Journal of Ceramics
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    • v.4 no.4
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    • pp.279-285
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    • 1998
  • The $UO_2$ pellets are usually sintered under hydrogen gas atmosphere. Hydrogen gas may cause unexpected early failure of the refractory bricks in the sintering furnace. In this work, nitrogen was mixed with hydrogen to investigate the effect of nitrogen gas on a failure machanism of the refractory bricks and on the microstructure of the $UO_2$ pellet. The hydrogen-nitrogen mixed gas experiments show that the larger nitrogen the mixed gas contains, the less the refractory materials are reduced by hydrogen. The weight loss measurements at $1400^{\circ}C$ for fire clay and chamotte refractories containing high content of $SiO_2$ indicate that the weight loss rate for the mixed gas is about half of that for the hydrogen gas. Based on the thermochemical analyses, it is proposed that the weight loss is caused by hydrogen-induced reduction of free $SiO_2$ and/or $SiO_2$ bonded to $Al_2O_3$ in the fire clay and chamotte refractories. However, the retardation of the hydrogen-induced $SiO_2$ reduction rate under the mixed gas atmosphere may be due to the reduction of the surface reaction rate between hydrogen gas and refractory materials in proportion to volume fraction of nitrogen gas in the mixed gas. On the other hand, the mixed gas experiments show that the test data for $UO_2$ pellet still meet the related specification values, even if there exists a slight difference in the pellet microstructural parameters between the cases of the mixed gas and the hydrogen gas.

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R-wave Detection Algorithm in ECG Signal Using Adaptive Refractory Period (ECG 신호에서 적응적 불응기를 이용한 R-wave 검출 알고리즘)

  • Kim, Jung-Joon;Kim, Jin-Sub;Park, Kil-Houm
    • Journal of the Institute of Electronics and Information Engineers
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    • v.50 no.5
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    • pp.242-250
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    • 2013
  • In this paper, R-wave detection algorithm using refractory period to reflect the depolarization and repolarization of the myocardial cells of the heart is proposed. The proposed algorithm detects R-peaks using the features of R-wave and variable refractory period. First, the proposed algorithm extracts candidate R-peaks that have a relatively high potential and calculates the refractory period based on the kurtosis and potential for candidate R-peaks. Next, R-peak is determined by morphological features of the R-wave within the refractory period. In addition, due to less computation in the proposed algorithm, real-time processing is possible. The algorithm is applied to all records of the MIT-BIH arrhythmia database and the obtained results show a competitive detection rate of over 99.7%.

Effect of Fe2O3 Concentration in Coal Slag on the Formation of (Fe,Cr)3O4 in Chromia Refractory (크롬계 내화물에서 슬래그의 산화철 농도가 (Fe,Cr)3O4 형성에 미치는 영향)

  • Park, Woo Sung;Oh, Myongsook S.
    • Applied Chemistry for Engineering
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    • v.18 no.5
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    • pp.495-500
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    • 2007
  • The inside wall of a coal gasifier is lined with refractory, and the corrosion of the refractory is an important factor affecting the refractory lifetime and the replacement period. This paper examines the changes in microstructure of a chromia refractory due to chemical reactions with slag having varying amounts of $Fe_2O_3$. Slag samples were prepared by adding $Fe_2O_3$ to KIDECO slag, and static corrosion experiments were carried out at $1550^{\circ}C$. The layer of $(Fe,Cr)_3O_4$ formation and the depth of Fe depletion in the infiltrating slag were determined. In addition, FactSage equilibrium calculations were carried out in order to determine the conditions of formation, and to compare with the experimental observations. In the sample exposed to KIDECO slag, which has about 10 wt% $Fe_2O_3$, the formation of $(Fe,Cr)_3O_4$ was not observed. As the $Fe_2O_3$ concentration in slag increased, $(Fe,Cr)_3O_4$ formation and Fe depletion depth increased. Increasing $Fe_2O_3$ concentration also made the slag/refractory interface indistinguishable. Equilibrium calculations predicted that higher $Fe_2O_3$ concentrations favor chromite formation at gasification temperatures. The chromite formation was most favorable when the amount of $Cr_2O_3$ was limited, as in the case of dissolved $Cr_2O_3$ in slag. When the concentration of $Fe_2O_3$ in slag was less than 20%, the formation of chromite was least favorable in the system with equal amounts of slag and refractory.