• 한국세라믹학회지
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• 제40권12호
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• pp.1141-1149
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• 2003

Refractory industry in technologically advanced countries has long been on gradual decline due to leveled-off steel production and decreasing unit consumption of refractories for steel. Notable technological achievements by refractory industry that contributed significantly to steel production are briefly reviewed covering from blast furnace, basic oxygen furnace to continuous casting. Future possibility to revitalize the refractory industry is discussed on the basis of the review, taking into account opportunities available in environment and energy related sector of industries.

• Computers and Concrete
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• 제25권1호
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• pp.29-36
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• 2020

This work presents a numerical modeling procedure to simulate the refractory concrete lining in fluid catalytic cracking units of oil refineries. The model includes the simulation of the anchors that reinforce the contact between the refractory concrete and the steel casing. For this purpose, the constitutive relations of an interface finite element are set to values that represent the homogenized behavior of the anchored interface. The parameters of this constitutive relation can be obtained by experimental tests. The model includes also multi-surface plasticity, in order to represent the behavior of the refractory concrete lining. Since the complexity of real case applications leads to high computational costs, the models presented here were implemented in a high-performance parallelized finite element platform. A case study representing a riser similar to the ones used by the refinery industry demonstrates the potential of the model.

• 제어로봇시스템학회논문지
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• 제21권4호
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• pp.291-300
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• 2015

In the steel manufacturing process heat-endurance deterioration of a ladle used to cause a big accident. In this paper, an infrared imaging system and image analyzing procedure are proposed for inspecting refractory bricks of a ladle. The proposed algorithm contains following three parts: two-stage image selection procedure, reference point detection, and analysis of heat-endurance deterioration. Experiments were conducted with real data from a steel plant and detailed configuration of infrared imaging system was presented.

• Journal of Microbiology and Biotechnology
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• 제26권11호
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• pp.1871-1880
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• 2016

Bio-oxidation is an effective technology for treatment of refractory gold concentrates. However, the unsatisfactory oxidation rate and long residence time, which cause a lower cyanide leaching rate and gold recovery, are key factors that restrict the application of traditional bio-oxidation technology. In this study, the oxidation rate of refractory gold concentrates and the adaption of microorganisms were analyzed to evaluate a newly developed two-step pretreatment process, which includes a high temperature chemical oxidation step and a subsequent bio-oxidation step. The oxidation rate and recovery rate of gold were improved significantly after the two-step process. The results showed that the highest oxidation rate of sulfide sulfur could reach to 99.01 % with an extreme thermophile microbial community when the pulp density was 5%. Accordingly, the recovery rate of gold was elevated to 92.51%. Meanwhile, the results revealed that moderate thermophiles performed better than acidophilic mesophiles and extreme thermophiles, whose oxidation rates declined drastically when the pulp density was increased to 10% and 15%. The oxidation rates of sulfide sulfur with moderate thermophiles were 93.94% and 65.73% when the pulp density was increased to 10% and 15%, respectively. All these results indicated that the two-step pretreatment increased the oxidation rate of refractory gold concentrates and is a potential technology to pretreat the refractory sample. Meanwhile, owing to the sensitivity of the microbial community under different pulp density levels, the optimization of microbial community in bio-oxidation is necessary in industry.

• 한국산업융합학회 논문집
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• 제15권3호
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• pp.71-77
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• 2012

This study gives the optimal reaction conditions, reaction mechanisms, reaction rates leaded from the oxidation of phenol by electron beam accelerator and ozone used for recent water treatment. It gives the new possibility of water treatment process to effectively manage industrial sewage containing toxic organic compounds and biological refractory materials. The high decomposition of phenol was observed at the low dose rate, but at this low dose rate, the reaction time was lengthened. So we must find out the optimal dose rate to promote high oxidation of reactants. The reason why the TOC value of aqueous solution wasn't decreased at the low dose was that there were a lot of low molecular organic acids as an intermediates such as formic acid or glyoxalic acid. In order to use both electron beam accelerator and biological treatment for high concentration refractory organic compounds, biological treatment is needed when low molecular organic compounds exist abundantly in sewage. In this experiment, the condition of making a lot of organic acids is from 5 kGy into 20 kGy dose. Decomposition rate of phenol by electron beam accelerator was first order reaction up to 300ppm phenol solution on the basic of TOC value and also showed first order reaction by using both air and ozone as an oxidants.

• 한국주조공학회지
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• 제30권3호
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• pp.115-120
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• 2010

Recently, an advanced raw material supplying system in diecasting industry that molten metal produced by the raw material supplier can be directly delivered to the diecasting shops was proposed. It was known to have advantages of reducing melting process cost and improving working environment. However, for its successful mass production, the development of high insulation ladle is inevitable. In this study, the optimal mixing ratio of $SiO_2-Al_2O_3$ was investigated and the high insulation ladle with computer simulation result was built in a prototype and evaluated. The prototype which has refractory wall of $SiO_233%-Al_2O_3$ 35%-CaO 33% showed high insulation sufficient for carrying the Al molten metal for 138 minutes. Gas quantity result and SEM-EDS analysis on the melt poured in the ladle also showed extremely low level of 0.028 cc / 100 g and no penetration of Al molten metal into the refractory wall, satisfying the requirements for mass production.

• Journal of the Korean Wood Science and Technology
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• 제45권5호
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• pp.544-558
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• 2017

본 연구는 국내야외시험을 통하여 난주입수종의 방부성능을 조사하기 위하여 수행되었다. 난주입수종의 방부처리에 적합하다고 판단되는 캐나다 방부목재 표준규격 CSA O80 Series-08 중 주거용 방부목 그룹 C와 D에 따라 방부 처리된 웨스턴 헴록과 스프루스의 방부성능을 야외시험을 통해 평가하였다. 제조된 샘플들은 자상처리를 실시한 후 alkaline copper quaternary (ACQ)와 copper azole (CA)로 방부처리를 실시하였다. 성능시험용 시편들은 2010년 11월 경남 진주에 조성된 야외시험장에서 AWPA E7-09와 AWPA E18-06 방법에 따라 지접부 및 지상부 성능시험을 수행하였으며 매년 정기점검을 통해 시편들의 부후 및 흰개미 가해상태가 조사되었다. 2017년 3월까지 약 6년 5개월 동안의 국내 야외시험 결과를 살펴보면 무처리 시편에서는 부후와 흰개미 가해가 심하게 발생되었지만 방부처리된 시편에서는 거의 발생하지 않은 것으로 나타났다. 이러한 결과는 국내 목재사용환경에서 5 mm 침윤깊이의 적용가능성을 보여준다. 본 논문에서는 국내목재방부산업에서 난주입수종의 활용을 증가시키기 위해 고려되었으면 하는 부분을 침윤도와 보유량의 관점에서 논의한다.

• Horticulture, Environment, and Biotechnology : HEB
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• 제59권6호
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• pp.865-873
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• 2018

Allium ochotense and Allium microdictyon are commonly known as 'Mountain garlic' and are popular, economically important species in many countries such as Korea, China, and Mongolia. Their leaves are used as culinary side dishes and in traditional medicines. In Korea, these two species are at risk of extinction due to damage to their natural habitat and thus, conservation and breeding programs are needed. However, their identification relies mostly on morphological data, which is limited and until recently, led to classifying these two species under A. victorialis. In the present study, a simple and reliable method of molecular identification was developed to distinguish A. ochotense from A. microdictyon that targets four barcoding regions: the internal transcribed spacer (ITS), the maturase K gene (matK), the chloroplast psbA-trnH intergenic region, and the ribulose-bisphosphate carboxylase large subunit gene (rbcL). Single nucleotide polymorphisms (SNPs) were found in ITS and matK regions, and species-specific primers were designed based solely on the SNP at position 680 of the ITS region that could differentiate A. ochotense from A. microdictyon. Using these primers in amplification refractory mutation system (ARMS)-PCR, A. ochotense, and A. microdictyon could be simultaneously and efficiently distinguished. This study is the first to report a simple, rapid, and efficient method for discriminating A. ochotense and A. microdictyon, indicating the utility of species-specific markers in the development of conservation and breeding programs.

• Safety and Health at Work
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• 제13권3호
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• pp.357-363
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• 2022

Background: Refractory ceramic fibers (RCFs) are a suspected carcinogen but have been widely used as insulations. Depending on the temperature, RCFs can transform into crystalline SiO₂, which is a carcinogen that can be present in the air during bulk RCF handling. This study analyzed the physicochemical and morphological characteristics of RCFs at high temperatures and determined the exposure levels during the semiconductor scrubber maintenance. Methods: Sampling was conducted at a company that manufactures semiconductor scrubbers using RCFs as insulation. Bulk RCF samples were collected both before and after exposure to a scrubber temperature of 700℃. Airborne RCFs were collected during scrubber maintenance, and their characteristics were analyzed using microscopes. Results: The components of bulk RCFs were SiO₂ and Al₂O₃, having an amorphous structure. Airborne RCFs were morphologically different from bulk RCFs in size, which could negatively affect maintenance workers' health. 58% of airborne RCFs correspond to the size of thoracic and respirable fibers. RCFs did not crystallize at high temperatures. The exposure caused by airborne RCFs during the scrubber frame assembly and insulation replacement was higher than the occupational exposure limit. Conclusion: Workers conducting insulation replacement are likely exposed to airborne RCFs above safe exposure limits. As RCFs are suspected carcinogens, this exposure should be minimized through prevention and precautionary procedures.

• 한국산업보건학회지
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• 제10권1호
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• pp.104-114
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• 2000

This study was carried out to estimate current status of dust concentrations in the factories producing non-metallic products in Korea. Data were gathered from the environmental monitoring reports by 40 workplace environmental monitoring institutes and the questionnaire designed for the study by the authors. A total of 1838 dust samples from 368 plants were obtained from the reports and were analyzed with no data modifications. But data on asbestos, rock wool, and welding fumes were excluded in this evaluation. The factories were classified into eight groups according to the standard industrial classification scheme in Korea. The results of this study were as follows; 1. The factories included were glass, non-refractory ceramic, refractory ceramic ware, structural non-refractory clay and ceramic, cement and lime, articles of concretes, and stone. Mean(geometric mean) concentrations of total dust samples ranged from $1.75(0.84)mg/m^3$ to $5.87(2.84)mg/m^3$. Statistically significantly higher dust concentrations were found in the cement and lime industries compared with other industries. 2. The non-compliance rates were 15.2% in glass and 20.6% in other non-metallic mineral products industries. Although all institutions surveyed utilized the identical sampling and classification scheme for dusts as specified in the current occupational exposure limits, wide discrepancies were found in collecting samples and classifying dusts. Further problems were discovered in classifying dusts. A dust sample collected could be classified into any of the three groups regardless of silica content. The results of this study showed that dust concentrations in the non-metallic products industries varied widely. Also discovered was classification errors of dust types among workplace monitoring institutes. These errors could adversely affect the results of exposure assessments and the true nature of dust hazards. Further, no institutions performed respirable dust sampling and analysis of crystalline silica. In order to correct these malpractices, current standards of occupational exposure limits should be revised and tight supervision by the Ministry of Labour be suggested.