• Title, Summary, Keyword: Refractory

Search Result 938, Processing Time 0.035 seconds

The Use of Monolithic Refractories and Microwave Drying for RH Steelmaking Vessels

  • Kayama, Tsuneo;Hanagiri, Seiji;Sukenari, Shiro
    • The Korean Journal of Ceramics
    • /
    • v.6 no.2
    • /
    • pp.143-149
    • /
    • 2000
  • Monolithic refractory technology has been developed for RH vessels, with the purpose of reducing the total refractory cost. The technology includes the use of an improved monolithic refractory and microwave drying. The improved monolithic refractory was an alumina-spinel composition, of the type used in steel ladles, to which fine alumina was added to increase the density and corrosion resistance. The microwave drying method, previously developed and used to dry the monolithic lining in steel ladles, was modified for use in drying the dense, 500mm thick lining in RH vessels. This work has resulted in significant cost savings.

  • PDF

Runoff Characteristics of Refractory Organic Matters from South-Han River Watershed during Rainfall Event and Dry Season (남한강 지역의 건기 시, 강우 시, 난분해성 유기물질 유출 특성)

  • Gil, Kyungik;Kim, Taewon;Jung, Myung-Sook
    • Journal of Korean Society on Water Environment
    • /
    • v.27 no.3
    • /
    • pp.306-313
    • /
    • 2011
  • In this paper, runoff characteristics of South-Han river watershed in terms of refractory organic matters were investigated. The concentrations of DOC, POC, R-DOC, R-POC in runoff and flow rates were determined by monitoring 27 times in dry season and 4 times in rainy season. The concentrations of the dissolved refractory organic matter, R-DOC was the lowest in fall and similar in the other dry seasons. The particulate refractory organic matter, R-POC showed less fluctuation than R-DOC. In summer, mass loading was the highest than other dry seasons. The concentrations of R-DOC, R-POC were showed to be affected by runoff volume. The mass loading grows higher as runoff volume gets higher.

Feature, Problem find the Hereafter of Chrome-Containing Refractory (크롬계 내화물의 특징과 문제점 및 장래)

  • Yamaguchi, Akira
    • Ceramist
    • /
    • v.9 no.6
    • /
    • pp.12-17
    • /
    • 2006
  • One of characteristic of $Cr_2O_3-containing$ refractory is excellent resistance to corrosion. However, there is a problem that hexa-valent chromium, which is noxious to the human body, is easily formed by reaction between the refractory and slag with CaO, $Na_2O$ and/or $K_2O$. In this article, the reason why the $Cr_2O_3-containing$ refractory has excellent corrosion resistance qualities, he conditions under which hexa-valent chromium formed, methods for suppressing generation of hexa-valent chromium and the possibility of the refractory components excluding $Cr_2O_3$ for the furnace are described as a base of development of further excellent refractories.

  • PDF

Corrosion of Alumina-Chromia Refractories by Alkali Vapors; II. Experimenal Approach

  • Lee, Kyung-Ho;Jesse . Brown Jr
    • The Korean Journal of Ceramics
    • /
    • v.1 no.2
    • /
    • pp.86-90
    • /
    • 1995
  • Theoretical predictions for thermodynamically stable phases which formed when alkali(sodium and potassium) vapors reacted with alumina-chromia refractories under coal gasifying atmosphere were confirmed experimentally using a laboratory-scale coal gasifying reaction system and a commercial alumina-chromia refractory using SEM, XRD, and EDAX. Alkali concentration profiles in the refractory as a function of time were also determined. The results showed that the compounds that formed were $X_2O{\cdot}Al_2O_3, X_2O{\cdot}Cr_2O_3, X_2O{\cdot}5Al_2O_3, X_2O{\cdot}7Al_2O_3, X_2O{\cdot}11Al_2O_3(X=Na^+ \;or\; K^+)$, depending upon the alkali concentration and time of exposure at high temperatures. The presence of sulfur in gasifying atmospheres did not appear to affect the alkali reaction produces. Alkali pentration into the alumina-chromia refractory was deep and the formation of the $Na_2O{\cdot}Al_2O_3/K_2O{\cdot}Al_2O_3$ compunds resulted in the serious deformation of the refractory due to the large volume expansion at the reaction surface. The hot face of the alumina-chromia refractory in service under an alkali environment is prone to failure by alkali attack.

  • PDF

Scapulothoracic Arthrodesis for Refractory Shoulder Dysfunction: A Retrospective Study of Indications and Functional Outcome

  • Chung, Soo-Tai;Warner, Jon J.P.
    • The Academic Congress of Korean Shoulder and Elbow Society
    • /
    • /
    • pp.208-208
    • /
    • 2009
  • Eleven shoulders (9 patients) with refractory scapulothoracic dysfunction were treated with scapulothoracic arthrodesis between 2000 and 2006. Refractory shoulder dysfunction included facioscapulohumeral muscular dystrophy in five shoulders (3 patients), refractory scapular winging with long thoracic nerve palsy in one shoulder, scapular winging caused by serratus anterior palsy with trapezius dysfunction in one shoulder, post-surgical thoracic outlet syndrome due to medial clavicle resection in two shoulders, refractory scapular winging with spinal accessory nerve injury in one shoulder, and chronic trapezius rupture caused by cervical spine surgery in one shoulder. The mean active flexion was improved from 82 degrees preoperatively to 112 degrees postoperatively. The mean Constant score was improved from 27.2 points to 68.0 points. Two shoulders (1 patient) that had facioscapulohumeral muscular dystrophy had broken wires due to nonunion, and one patient had a reactive pulmonary effusion. In ten of the eleven shoulders, the patients were satisfied with their results. The scapulothoracic arthrodesis can cause significant pain relief and functional improvement in refractory scapulothoracic and/or shoulder dysfunction. By selecting patients that present with appropriate indications, and using experienced surgical technique through complete preoperative evaluation, we can diminish the complication rate and make good clinical outcomes.

  • PDF

Two Cases of Adjuvant Immunotherapy with Cytokine-Induced Killer Cells for Relapsed or Refractory Neuroblastoma (재발성 혹은 불응성 신경모세포종 환자에서의 활성화 T-림프구 세포치료 2예)

  • Choi, Jung Yoon;An, Hong Yul;Hong, Kyung Taek;Hong, Chery;Kang, Hyoung Jin;Shin, Hee Young
    • Clinical Pediatric Hematology-Oncology
    • /
    • v.25 no.2
    • /
    • pp.202-207
    • /
    • 2018
  • The treatment outcomes of relapsed or refractory neuroblastoma have been unsatisfactory till date. We reported two cases of adoptive immunotherapy using cytokine-induced killer (CIK) cells against relapsed or refractory neuroblastoma. CIK cell production was attempted in three patients, out of which two patients exhibited adequate levels of CIK cell production. Two patients completed full term of CIK cell infusions (weekly for 6 weeks and then biweekly for 8 wk) without serious adverse events. The progression-free survivals for the two patients were 1.9 and 4.1 months. Their overall survivals were 16.7 and 28.7 months. Although the efficacy was unclear, CIK cell infusion combined with other treatment strategies may have prolonged overall survival in refractory neuroblastoma patients. Further studies are needed to determine the exact role of CIK cell-based immunotherapy in relapsed or refractory neuroblastoma patients.

Estimation of the thickness of refractory ceramics using the impact-echo method (충격반향기법을 이용한 내화물 두께 추정)

  • Lee, Seongmin;Shin, Namho;Roh, Yongrae
    • The Journal of the Acoustical Society of Korea
    • /
    • v.36 no.4
    • /
    • pp.247-253
    • /
    • 2017
  • Generally, the vibration characteristics of refractory ceramics are identified by assuming them as isotropic materials. However, in practice, refractory ceramics exhibit anisotropic properties as they are manufactured by pressing ceramic powders along a particular direction. Therefore, in this research, the frequency responses of a refractory ceramic brick along its width, length, and height directions were acquired using finite element analysis by assuming that the ceramics had tetragonal symmetry in their material properties. The validity of the numerical analysis results was verified by comparing them with those from experimental measurements. Based on the frequency response, the thicknesses of the refractory brick along three different directions were estimated using the impact-echo technique. The maximum difference between the estimated and actual thicknesses was observed to be less than 5 %. This result confirms the effectiveness of the impact-echo technique along with anisotropic property characterization to evaluate the thickness of the refractory ceramic.

Investigation of Degradation Mechanism of High Alumina Refractory in a Coal Gasifier (석탄 가스화기에서의 고알루미나 내화물의 손상 기구 규명)

  • Kim, Yuna;Lee, Jae Goo;Oh, Myongsook S.
    • Applied Chemistry for Engineering
    • /
    • v.20 no.6
    • /
    • pp.638-645
    • /
    • 2009
  • High alumina refractory used in a coal gasifier was analyzed and the degradation mechanism by molten slag was investigated. The depth of refractory severely damaged by slag varied between 12~40 mm, including the adhered slag layer. The sample also showed the cracks formed in parallel to the slag/refractory interface. The degree of degradation varied with the micro-structures in the refractory. Fused alumina grains showed the uneven boundary and pore formation just along the edges, while the tablet alumina showed the slag penetrated between sintered alumina around which the formation of Al-Fe phase was observed. Calcium aluminate cements were not observed at the high temperature zone near the slag/refractory interface, probably due to dissolution into molten slag. Around large grains of alumina, rod shape alumina, which appeared to be recrystallized during cooling, were observed, and large pores were also formed around those grains. Therefore, in high alumina refractories, hot molten slag dissolves the bonding phase and rod-shape alumina phase is recrystallized upon cooling. During this process, cracks are developed due to structural change, and the degradation occurs by physical causes such as structural spalling.

Case Series of Refractory Gastroesophageal Reflux Disease Treated with Lijin-tang-gamibang (이진탕가미방(二陳湯加味方)을 투여한 불응성 위식도역류질환의 증례군 연구)

  • Ha, Na-yeon;Han, Ga-jin;Kim, Dae-jun;Ko, Seok-jae;Park, Jae-woo;Kim, Jin-sung
    • The Journal of Internal Korean Medicine
    • /
    • v.38 no.6
    • /
    • pp.1085-1095
    • /
    • 2017
  • Objectives: The purpose of this study was to investigate the efficacy of Lijin-tang-gamibang on refractory gastroesophageal reflux disease (GERD). Methods: This before-and-after study compared the first medical examination and examination at the end of medical treatment. Twelve refractory GERD patients who visited the Department of Digestive Diseases of Kyung Hee University Korean Medicine Hospital from August 14th, 2017 to October 14th, 2017, were treated with Lijin-tang-gamibang for four consecutive weeks. The clinical characteristics of refractory GERD and the efficacy of herbal medical treatment was assessed by questionnaires, the Nepean Dyspepsia Index-Korean version (NDI-K), the Korean Gastrointestinal Symptom Rating Scale (KGSRS), the Numerical Rating Scale (NRS), the Korean version of the Perceived Stress Scale (KPSS-10), the Qi Stagnation Questionnaire (QSQ), the Spleen Qi Deficiency Questionnaire (SQDQ), and the Patient Global Impression of Change (PGIC). Prolonged effects were reported upon the follow-up telephone survey two weeks after treatment. Results: After treatment with the herbal medicine Lijin-tang-gamibang, the clinical characteristics of 12 refractory GERD patients were improved, especially in terms of the most common symptoms of acid regurgitation and heartburn. Each symptom score of NDI-K, KGSRS, NRS, SQDQ, and PGIC showed significant advances. Prolonged effects were reported in NDI-K, NRS and PGIC questionnaires two weeks after treatment. Conclusions: These results suggest that Lijin-tang-gamibang is an effective treatment for refractory GERD.

Microbial Composition and Pattern of Antibiotic Resistance in Subgingival Microbial Samples From Patients With Refractory Periodontitis (난치성 치주염환자로부터 채취한 치은연하 세균의 구성과 항생제 내성에 관한 연구)

  • Chang, Beom-seok
    • Journal of Periodontal and Implant Science
    • /
    • v.30 no.4
    • /
    • pp.725-736
    • /
    • 2000
  • It is becoming increasingly apparent that periodontitis consists of mixture of diseases, most of which respond favorably to traditional mechanical therapy. Among these variants of the disease, some appear to be associated with unusual microbial infections and defective host defenses. Many of these fail to respond to conventional treatment. The recognition that some forms of periodontitis are refractory to standard periodontal therapy has given rise to a new classification of peridontitis. A series of 1692 subgingival microbial samples sent to a diagnostic microbiology laboratory included 738 samples that could be identified as compatible with a clinical diagnosis of refractory or recurrent periodontitis. In descending order of prevalence the associated microbiota included Bacteroides forsythus(85%) ,Fusobacterium species(78%), Spirochetes(67%), Campylobacter rectus(64%), Porphyromonas gingivalis(59%), Peptostreptococcus micros(58%), motile rods(46%), Prevotella intermedia(33%), Eikenella corrodens(13%), Capnocytophaga species(12%) ,and Actinobacillus actinomycetemcomitans(6%). Antibiotic resistance to tetracycline, penicillin G, or metronidazole was particularly noticeable for Fusobacterium species, Capnocytophaga species, and Actinobacillus actinomycetemcomitans. It was largely absent for Campylobacter rectus. No antibiotic data were obtained for Porphyromonas gingivalis or Bacteroides forsythus, as these species were detected by immunofluorescence. The results indicate that a substantial number of microorganisms associated with refractory periodontitis are variably resistant to commonly-used antibiotics. Diagnostic microbiology must be considered an essential adjunct to the therapist faced with periodontal lesions refractory to conventional treatment.

  • PDF