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  • 제목/요약/키워드: Air blast

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Effect of blast-furnace slag particle fineness changes on the engineering characteristics of mortar (고로슬래그 미분말의 분말도 변화가 모르타르의 공학적 특성에 미치는 영향)

  • Lee, Jae-Jin;Moon, Byeong-Ryong;Park, Yong-Jun;Joo, Eun-Hui;Han, Min-Cheol;Han, Cheon-Goo
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2016.10a
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    • pp.102-103
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    • 2016
  • Recently on construction sites, there is increased use of concrete with large quantities of blast-furnace slag(BS) admixture replacements, for purposes of reducing CO2 created from cement, one of the ingredients of concrete. But such high-BS fineness changes can have a huge effect on the quality of mortar and concrete. Therefore in this study an experiment was conducted in which liquidity and intensity of mortar depending on an artificially-applied change in fineness degree at degree 7. The results, though subtle, were that the larger the fineness degree, liquidity increased and air quantity decreased, and compression and flexural strength increased.

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Effect of the Arc Furnace Manufacturing Process, Blast Furnace Manufacturing Process, and Carbon Content on the High-temperature Oxidation of Hot-rolled Steel between 650 and 900℃ (열간 압연강의 600~900℃에서의 고온산화에 미치는 전기로제조법, 고로제조법 및 탄소량의 영향)

  • Kim, Min Jung;Lee, Dong Bok;Baek, Seon-Pil
    • Korean Journal of Metals and Materials
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    • v.48 no.10
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    • pp.907-913
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    • 2010
  • Hot-rolled steel plates of SPHC and SS400 were oxidized at 600, 750 and 900C for 2 hr in air. With an increase in the oxidation temperature, their oxidation rates increased, and this was accompanied by the formation of pores and cracks in the thickened oxide scales, which were non-adherent. SPHC steels manufactured by either an arc furnace or a blast furnace displayed similar oxidation rates, indicating that their oxidation rates were insensitive to the manufacturing process. Medium-carbon SS400 steel displayed somewhat faster oxidation rates than low-carbon SS400 steel, indicating that the carbon content did not significantly influence the oxidation rates.

The Optimal Mixing Design of the PHC Piles Utilizing the Air Cooled Blast Furnace Slag as Coarse Aggregate (서냉 고로슬래그 굵은골재를 활용한 PHC 파일의 최적배합 및 물리적 특성)

  • Park, Yong-Kyu;Kim, Hyun-Woo;Kim, Seung-Il;Hur, Kab-Soo;Yoon, Ki-Won
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.2 no.2
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    • pp.137-144
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    • 2014
  • The PHC pile utilizing the air-cooled blast-furnace slag as coarse aggregate was studied. This research was progressed with the range from the indoor mixing design evaluation into the actual goods production. The physical properties of the PHC pile are determined to satisfy through the appropriate mixing design adjustments. However, it should eliminate the aggregates including CaO and MgO in SG when it utilize in an AC (autoclave) type manufacturing process. It satisfied the bending moment, shear strength, and compressive strength of KS F 4306 except the surface states of the pile.

Quality Characteristics of Korean Rice Cake by Freezing Methods (냉동 방법에 따른 떡의 품질특성 변화)

  • Lee, Hye-Jin;Ku, Su-Kyung;Choi, Hee-Don;Park, Jong-Dae;Sung, Jung-Min;Kim, Young-Boong;Choi, Hyun-Wook;Choi, Yun-Sang
    • Korean journal of food and cookery science
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    • v.33 no.2
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    • pp.148-154
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    • 2017
  • Purpose: Frozen Korean traditional rice cakes (Sulgitteok and Garaetteok) were evaluated different conditions (20C and 10C) freezing (magnetic resonance quick freezing and air blast freezing) to study differences in quality characteristics. Methods: Experiments analyze Korean rice cakes for water content, water activity, color, textural properties, and sensory characteristics. Results: Moisture content showed high value at 20C freezing regardless of freezing method. Water activity was higher at 20C than 10C, and water activity higher magnetic resonance quick freezing than air blast freezing. The lightness values were higher 20C freezing temperature compare to 10C freezing temperature. Hardness and chewiness were the lowest 20C magnetic resonance quick freezing. sensory evaluation both Sulgitteok and Garaetteok showed better overall acceptability at 20C magnetic resonance quick freezing. Conclusion: Therefore, the 20C magnetic resonance quick freezing method resulted in favorable textural properties and sensory characteristics.

A Study of the Characteristics of the High-Flowable Concrete (고유동콘크리트의 특성에 관한 실험적 연구)

  • Jeon, Hyun-Kyu;Kim, Dae-Hoi;Lee, Jong-Chan;Ji, Suk-Won;Yoo, Taek-Dong;Seo, Chee-Ho
    • Journal of the Korea Institute of Building Construction
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    • v.3 no.2
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    • pp.129-134
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    • 2003
  • In this research, we used fly-ash and blast-furnace slag as substitute material of cement and fine aggregate, and we, through experiments, researched and analyzed the features of high-flowable concrete added high efficiency AE water reduction agent. The results are below. 1. Liquefaction generally presented high-slump flow value; on the other hand, partial segregation was observed in case of mixing proportion with 65 cm slump flow and above. This segregation was partially improved in accordance with mixing admixture. 2. Compressive strength according to mixing admixture and increasing mixing ratio of fly-ash were subject to be declined when it was initially cast-in, but its gap was improved when time was fully passed. 3. After mixing blast-furnace slag and fly-ash as substitute material, the result showed that the modulus of elasticity against freezing & melting was improved according to mixing blast-furnace slag and also increased in accordance with increasing pulverulent-body volume. 4. According to increasing the mixing volume of fly-ash, the durability factor was deteriorated because compressive strength became lower as well as air content was decreased when it was initially case-in. 5. The minimum air content to secure durability was 3.7%, for that reason, we had better secure admixture such as air entraining agent when cast-in high-flowable concrete.

Spray Deposit Distribution of a Small Orchard Sprayer (소형 과수방제기 살포입자의 부착량 분포)

  • Koo, Young-Mo
    • Journal of Biosystems Engineering
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    • v.32 no.3
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    • pp.145-152
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    • 2007
  • Uniformity of spray deposit is one of the important factors in spray performance affecting efficacy of pest management. Distributions of spray deposit on artificial targets were measured and analyzed to enhance the efficiency of spray application. The research was studied to understand the deposition characteristics of spray droplets and to determine the optimum conditions of chemical application. The deposit and its pattern by the lower fan speed was more uniform and higher than that by the higher fan speed. The upward blasting distance was limited within 3 m, but the limit to the ground level was expanded the distance more than 3.5 m because of the accumulated droplets. When the fan speed was higher at the distance of 2.5 m, deposit reached to maximum. When the distance increased, deposit was getting lower. At the both fan speeds, the deposit was concentrated below 30 because of the gravitation and the resistance of wind. This research can be useful in designing an orchard sprayer and its operation for various tree canopies. To achieve a uniform distribution of deposit using the air-blast type orchard sprayer, the application rate from the middle boom should be increased as the air velocity to the upward increased. The spray rate to the side boom should be limited in a minimal level.

Numerical Simulation of the Liquid Flow in the Lower Part of the Blast Furnace - A Cold Flow Case (고로하부 액체유동에 대한 수치해석 사례 - 냉간유동)

  • Jin, Hong-Jong;Choi, Sang-Min;Jung, Jin-Kyung
    • Journal of the Korean Society of Combustion
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    • v.13 no.2
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    • pp.33-41
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    • 2008
  • The high permeability of the gas in the molten iron of the dripping zone of the blast furnace is a major factor in achieving the stable operation of a furnace with high productivity. Basic studies of the liquid flow behavior in a packed bed are necessary to grasp the effect of various operational changes on conditions in the dropping zone. Molten iron and slag together playa critical role in the lower zone, transporting mass and energy, while impairing and redistributing the gas flow. In turn, molten iron and slag undergo physical and chemical changes, and are redistributed radially as they descend to the hearth. In this research, mathematical formulations are derived for the gas and the liquid. The solid phase is fixed with constant porosity. The information for the molten iron and slag includes the hold-up, velocity, pressure, and information related to the areas of interaction between the gas and the liquid, and the solid and the liquid. Predictable results include the velocity, pressure and temperature distribution. Additional parameters include the packed particle size and the air blast rate.

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Development of a Daily Epidemiological Model of Rice Blast Tailored for Seasonal Disease Early Warning in South Korea

  • Kim, Kwang-Hyung;Jung, Imgook
    • The Plant Pathology Journal
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    • v.36 no.5
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    • pp.406-417
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    • 2020
  • Early warning services for crop diseases are valuable when they provide timely forecasts that farmers can utilize to inform their disease management decisions. In South Korea, collaborative disease controls that utilize unmanned aerial vehicles are commonly performed for most rice paddies. However, such controls could benefit from seasonal disease early warnings with a lead time of a few months. As a first step to establish a seasonal disease early warning service using seasonal climate forecasts, we developed the EPIRICE Daily Risk Model for rice blast by extracting and modifying the core infection algorithms of the EPIRICE model. The daily risk scores generated by the EPIRICE Daily Risk Model were successfully converted into a realistic and measurable disease value through statistical analyses with 13 rice blast incidence datasets, and subsequently validated using the data from another rice blast experiment conducted in Icheon, South Korea, from 1974 to 2000. The sensitivity of the model to air temperature, relative humidity, and precipitation input variables was examined, and the relative humidity resulted in the most sensitive response from the model. Overall, our results indicate that the EPIRICE Daily Risk Model can be used to produce potential disease risk predictions for the seasonal disease early warning service.

Effects of different drying methods on fermentation characteristics and viability of cold-adaptive yeast (저온 적응성 효모의 보존방법에 따른 균체의 생존율 및 발효특성)

  • Baek, Seong Yeol;Mun, Ji-Young;Yeo, Soo-Hwan
    • Food Science and Preservation
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    • v.24 no.7
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    • pp.1034-1042
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    • 2017
  • The quality characteristics of Yakju and survival rate of yeast were investigated by modifying the drying method for the cold adapted yeast strain Saccharomyces cerevisiae Y297 (SCY297). Viability and fermentation characteristics of the freeze-dried, air blast-dried, and liquid SCY297 cultures were compared after storing them at 25C. In addition, 5% skimmed milk, α-lactose, or trehalose was added as a protective agent for examining the effects of drying methods. During the 15-week storage period, the liquid and freeze-dried SCY297 cultures containing a protective agent showed a survival rate of 80%. However, the air blast-dried SCY297 culture showed 80% survival rate only in the skimmed milk supplemented group. Compared to the untreated cells, the acidity and amino acidity of Yakju prepared using freeze-dried or air blast-dried cultures of SCY297 increased by 2 fold and 5.7 fold respectively, while the alcohol content decreased by 5.07%. Compared to the untreated cells, the pH and amino acidity of Yakju prepared using the liquid culture of SCY297 increased by 1.5 fold and 2.5 fold respectively. Although the alcohol content decreased by 2.9%, decrease rate was lower than that observed for the freeze-dried and air blast-dried yeast cultures. Therefore, the results of this study showed that using a liquid starter culture was more advantageous than using the conventional solid culture.

Design of Simulation Prototype UI for Virtual Reality-based Air Blast and Vibration (가상현실 기반 발파소음 및 진동 시뮬레이션 UI 설계)

  • Lee, Dongyoun;Lee, Sang Gyu;Seo, Myoung Bae
    • Smart Media Journal
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    • v.10 no.4
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    • pp.35-44
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    • 2021
  • Recently, the new subway project called "Great Train Express" is in progress. During the tunnel excavation in the center of city, vibration and noise are generated, which make an uncomfortable effect on nearby residents. In order to prepare for this situation, the construction company generally establishes a noise and vibration management plan at the site from the construction planning stage through consultation with the residents of nearby areas and establishment of countermeasures for complaints raised. However, despite the establishment of a noise and vibration management plan, civil complaints have not been fundamentally resolved due to occurring noise and vibration during the construction in progress. In order to solve this problems, one of the best solution is to provide noise and vibration simulation technology with a high sense of reality and immersion for residents of nearby areas. Considering the ease and convenience of using the system, we intend to develop a UI(User Interface) necessary for the development of a simulation system that can directly experience the air blast and vibration based on virtual reality. The results of this study are expected to contribute to the development of virtual reality-based air blast and vibration simulations in the future.