• Journal of Korea Foundry Society
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• v.11 no.4
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• pp.293-302
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• 1991

Aluminum alloy matrix composites reinforced with various amounts of $Al_2O_3$ short fibers have been produced by a combined technique of rheo-compocasting and hot extrusion. Distribution of fibers in the composites fabricated by rheo-compocasting was relatively uniform. A good degree of uniaxial fiber alignment has been achieved by hot extrusion, but a lot of fibers fractured during extrusion. The tendency of fiber fracturing increases as the aspect ratio and the amount of fibers increase. Relatively good bonding between fiber and matrix was obtained by the formation of $MgAl_2O_4$ and Mg(Al, Fe)$_2O_4$ at the interface between fiber and matrix. In extruded composites, fiber-strengthening effect was relatively small since a lot of fibers fractured during hot extrusion. On the other hand, dispersion strengthening effect may increase. In order to improve the fiber strengthening effect, it is important to optimize the extrusion condition with consideration of metal flow in extrusion die.

• JOURNAL OF ELECTRICAL WORLD
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• s.417
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• pp.70-73
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• 2011

• Journal of Korean Society of Disaster and Security
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• v.12 no.2
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• pp.47-56
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• 2019

Recently, in order to overcome the difficulty of entering a fire source due to the occurrence of a large amount of smoke in the event of a fire in a parking lot, it has used that a method of discharge smoke using air supply, exhaust fans and jet fans installed for ventilation of parking lots. In this study, the variation of flow in the smoke layer was observed using CCTV under two conditions, in which only the air supply fan operates and the manned fan operates together, and the temperature around the plume was compared to Albert eq. to assess its suitability as a parking lot ventilation performance evaluation method. As a result, it was found that the smoke layer could be disturbed if the Jet Fan was operated at the same time, which could lead to the possibility of an initial evacuation disturbance. However, the additional operation of the Jet Fan has been confirmed by the observation CCTV that the emission performance is improved, which is believed to help conduct the suppression operation. The temperature around the plume was measured and compared to Alpert eq, and was analyzed to be about $2^{\circ}C$ lower at the center axis of the plume and $9.0^{\circ}C$ higher at 8 m in the direction of the discharge of smoke. The results of temperature measurements around the plume were lower than the maximum temperature expected in AS 4391 and did not exceed the expected temperature risk caused by the experiment. As with these results, the temperature risk from the progression of hot smoke tests is foreseeable, so it will be available as one of the general evaluation methods for assessing smoke control performance in a parking lot without relevant criteria.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.10a
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• pp.329-332
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• 2008

Nowadays, It is required human body-friendly, good mechanical properties, and economical efficiency material, simultaneously. The material to meet above requirement condition rear up high nitrogen stainless steel(HNS). However, HNS have a lot of problem such as poor workability, hot crack sensitivity. So, It is needed the condition of plastic working to overcome above many problem. In this study, VIM ingot with 100kg was made by pressurized vacuum induction melting. And then, The slab perform for hot rolling was prepared by open-die forging. Hot rolling process was performed by computer simulation according to change of height reduction, rolling temperature, heating numbers, rolling pass and so forth. The results of analysis were investigated between analysis and lab-scale rolling product.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.55-59
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• 2004

Recently, life cycle and lead-time of products have been shortened with the demand of customers. Therefore, it is important to reduce time and cost at the step of manufacturing trial molds. In order to realize three dimensional shape on CAD, the machining process has been widely used because it offers practical advantages such as precision and versatility. However, traditional machining process spends a lot of time in cutting product and the remained material causes trouble such as inconvenience for clean. In this work, a new machining process using the hot tool has been proposed to overcome those limitations. In the process, the hot tool moves the predetermined path and the heat of the tool decomposes the remained material. In order to set up the process, the hot tool to satisfy requirements is designed and the material thermal properties are obtained using the DSC and TGA machine. The relationships between process parameters and thermal radius of the tool are obtained through experiment.

• Journal of the Korea Safety Management & Science
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• v.12 no.2
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• pp.75-82
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• 2010

Gas turbines for power generating operate in a very high temperature condition and use natural gas for fuel. For this reason, many cases of damage happen at hot gas parts which are severely affected by high temperature gas and many cases of explosion occur by fuel gas. So a lot of efforts should be made to prevent hot gas parts damage and gas explosion accidents. Though there are many damage cases and explosion accidents, it is very difficult to find out the root causes of hot gas parts damage caused by gas explosion due to gas leakage in the heat exchanger for air cooling and gas heating. To prevent gas turbine from damage caused by gas explosion, removal of leakage gas from gas turbine is inevitably required before firing the gas turbine and installing alarm systems is also required for detecting gas leakage at stop valve to turbine while shut down.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.05a
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• pp.39-42
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• 2008

Alloy 718 nozzle component was manufactured by hot working and electron beam welding process. In this process, domestic 718 materials were applied and evaluated. Hot compression tests were carried out at a lot of process conditions and microstructural evaluation was investigated. Using the results, FEM simulations were performed in order to optimize the hot working process. After hot working, forged work-pieces were machined and welded by electron beam. Final nozzle component were heat treated and their microstructure and mechanical properties were investigated.

• Transactions of Materials Processing
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• v.8 no.1
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• pp.65-77
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• 1999

In recent years, the quality requirements from the customers of hot rolled steel strip have been steadily increasing in diversity and strictness. To meet these quality requirements as well as to improve productivity, steel mills have been doing their efforts for developing high performance Automatic Gauge Control (AGC) system. However, it is very time consuming and also needs a lot of money to develop the new technologies of AGC in actual mill. So, there has been a demand for developing the Dynamic Hot Rolling Simulator since late 80's. It is a kind of software packages and can analyze the dynamic behaviors of hot finishing rolling process without laborious experiments in actual mill. It can also be used as a designing tool of Automatic Gauge Controller. In this work, the Dynamic Hot Rolling Simulator which is applicable to 6 sands hot strip mill rolling was developed. The MATLAB with SIMLINK was used as a software developer for making the main part of simulator because it is very powerful tool for modeling, integrating, controller design, and simulation. In this paper, the structures and the mathematical models of the simulator were briefly described and the results of simulation on the transient phenomena of hot rolling process with actual mill data were also presented.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.10a
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• pp.281-286
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• 2002

To study of binder and fine aggregate a lot of replacement fly-ash concrete, initial characteristics, standard environment of curing temperature $20^{\circ}C$, hot-weather environment of curing temperature $35^{\circ}C$, . Flesh concrete tested slump. air contest and Hardening concrete valuated setting period of form, day of age 1, 3, 5. 7, 10, 28 compression strength in sealing curing. Purpose of study is consultation materials in field that variety of fly-ash replacement concrete mix proportion comparison and valuation. (1) Experiment result age 28day compression strength more higher plan concrete then standard environment in curing temperature $20^{\circ}C$, , most strength F43 is hot-weather environment in curing temperature $35^{\circ}C$, replacement binder 25%, fine aggregate 15%. (2) Hot-weather environment replacement a mount of fly-ash is a same of plan concrete setting period of form. Age 28day compression strength replacement a mount of fly-ash more hot-weather concrete then plan concrete.

• Journal of the Korean housing association
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• v.16 no.2
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• pp.75-82
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• 2005

The High-rise Residential Buildings are recently consuming a lot of energy because of the vertical height rise in case of supplying cold and hot water. It is required to a appropriate solution in occurring discomfortable use and unexpected conditions of High-rise Residential Buildings on account of the difference of water supply pressure on top and bottom floor, faucet outlet pressure rise. Thus, the purpose of this study is to research on practical use status of Cold and Hot Water Supply System through Question Survey in High-rise Residential Buildings and to analyze problems.