• Journal of Aerospace System Engineering
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• v.8 no.3
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• pp.1-5
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• 2014

An inner flow of a porous cylinder with partial slots was visualized to study fluidic phenomena in a solid rocket motor. A high-pressure chamber and an air supply system for high flow rate were used. In order to visualize the inner flow, the smoke generator with a cam-driven pump and heaters and high speed camera were adopted. The results of the cylinder type and the partial slot type were compared. As a result, the injected smoke flow in the partial slot type had circumferential fluctuations unlike the cylinder type. It was found that the circumferential flow induced from the partial slots could be the cause of combustion instability and roll torque.

• The Research Journal of the Costume Culture
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• v.25 no.3
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• pp.340-358
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• 2017

The purpose of this study is to fundamentally examine the vests of the robes "Daeraebok" and "Soraebok" of the Korean Empire from the 1876 Port Opening to the 1910 annexation of Korea to Japan. Among the collections of different robes of the Korean Empire which belong to various universities and institutions, only the vests were surveyed. The shape of the vests in the Korean Empire were single-breasted and double-breasted. Most V-necklines and vests with a shawl collar look like a tailored collar, where the collar outline was shaped like a notched and picked collar, which is a mix of the step collar and roll collar of the 19th century. The rear center line was not flat, but inclined to a triangle. All vests of the robe Daeraebok were equipped with gold buttons, and those of the robe Soraebok had black satin buttons. The tailoring characteristic is that the front has a different material (dark black wool) from the back (black silk). This characteristic is expected to be an important basic piece of information in the restoration and reproduction of the vest, which was worn during the imperial period, especially to reveal its shape, characteristics and composition. This characteristic can also be used as data of cultural contents based on Korean modern history.

• Corrosion Science and Technology
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• v.19 no.2
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• pp.57-65
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• 2020

As competition among global automakers intensifies, demand for materials that are better in price and performance is increasing. While steel and plastic materials compete for automotive fuel tanks, plastic materials have advantages such as light weight for automobiles. However, they have high prices. Accordingly, in this paper, four types of Zn-X plated steel sheets, electroplating (X = none, Sn) and galvannealed (X = Fe, Fe-Mg), were manufactured and their applicability as a fuel tank material was evaluated. Nano-composite coating solution with good conductivity was treated on the surface of plated steels using a roll coater and then cured through induction furnace to improve corrosion resistance. Quality characteristics such as corrosion resistance, fuel resistance to diverse gasoline and diesel fuels, and seam weldability were evaluated for the above plated steels. Their properties were compared and analyzed with conventional Zn-Ni electroplating steels. Among the above plated steels, Zn-Fe-Mg galvannealed steels coated with nano-composite coating exhibited better properties than other steels. Detailed experimental results suggest that evenly distributed Mg elements on the coating layer play a key role in the enhanced quality performance.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2002.05a
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• pp.109-113
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• 2002

Steel industry is the most capital intensive and the largest energy consuming industry, which operate huge and complex facilities to supply various steel products as the primary materials to almost every manufacturing industry Major steel products are hot-rolled and cold-rolled coils, plates, and wires that are produced through molten iron making, molten steel making, casting, and rolling. Each process runs in batch between setups and the specifications or bach are different with each other High energy consuming and heavy material handling require careful synchronization or processes, as well. Considering the synchronization or processes, the lot planning and scheduling problem in the integrated steelmaking process rovers the roll grouping with given casts. the sequencing or rolls over time, and the machine assignment and time scheduling or charges and casts. The problem is investigated by dividing it into two cases whether single or parallel machines at the molten steel making and the continuous casting processes. Problem descriptions and solution approaches or each instance are introduced. To test their performance and conformity, implementation or the algorithms and numerical experiments are carried out with real world and constructed data sets.

• Proceedings of the SAREK Conference
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• 2008.11a
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• pp.541-545
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• 2008

Particulate matter (PM) is one of the major indoor air pollutants especially in the subway station in Korea. In order to remove PM in the subway station, several kinds of PM removal system such as roll-filter, auto-washable air filter, demister, and electrostatic precipitator re used in the air handling unit (AHU) of subway station. However, those systems are faced to operation and maintenance problems since the filter-regeneration unit consisting of electrical or water jet parts is malfunctioned due to the high load of particulates and the filter material needs periodic replacement. In this study, we surveyed the particle removal systems in order to develop the new system of particle removing can be adopted in the current AHU of subway station.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.8
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• pp.28-34
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• 2008

A magnetic field detector as a potential MRI receiver is proposed. The proposed device is composed of SRR(split ring resonator) which is a kind of LC resonator first introduced as a negative permeability material and a simple loop antenna. The proposed device showed similar degree of performance to commercial one with a simpler circuit.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.05a
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• pp.432-435
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• 2005

Extensive width reduction of slabs is an important technology to achieve continuous production between the steelmaking and hot rolling processes. Conventionally, a vertical roll process has been used to achieve extensive width reduction. However, it is impossible to avoid the defects such as dog-bone, fish tail and camber. The deformation behavior in the width sizing process is more favorable than that in conventional vertical rolling edger, i.e. the material better flows toward the center of slab. This study is carried out to investigate the deformation of slab by two-step sizing press. The FE-simulation is utilized to predict plastic deformation mode in compression by a sizing press of slabs far hot rolling. In this paper, the various causes of the asymmetrical rolling phenomena are mentioned for the purpose of understanding of rolling conditions. Analytical results of slab-deformation by sizing press are presented below in this study.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.05a
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• pp.329-332
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• 2005

Cross rolling process is one of incremental forming processes to form an axi-symmetric shaped metal component. It can be classified into two types according to the shape of dies, which are a drum type (roll type) and a plate type (straight type). It can also be classified into a wedge type and a ramp type processes according to deformation characteristics of a material. The ramp type die is applied to plate type cross rolling process in cold forming process for forming of teeth of gear or bolt, while the wedge type die is generally utilized to drum type and plate type cross rolling processes in hot forming process. A shape of the ramp type die is usually same as final shape of a product at every section of a progressing direction, while the shape of the wedge type die has different shapes in a progressing direction. In this paper, a rolling of neck part in a ball stud component has been carried out using the plate type cross rolling process with a ramp shaped die. Forming characteristics have been performed using finite element analysis in order to obtain a proper preform for the ramp type plate cross rolling process.

• 한국가시화정보학회:학술대회논문집
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• 2002.11a
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• pp.67-72
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• 2002

Today, the research to examine a fact that interaction between the air and the fluid free surface affects the steady state flow and air. We proved the interaction between vortex pairs and free surface on each condition that is created by the end of delta wings. another purpose of this study is to investigate the effect of surface active material which can change the surface tension and we must consider when we refer to turbulent flow on surface tension. therefore, this research examined the growth process of vortex pairs on condition of clean, contaminated free surface and wall after we made vortex pairs through counter rotating flaps. The results of this study suggest that vortex pairs in clean free surface rise safely but the vortex pairs in contaminated free surface and rigid, no slip is made secondary vortex or rebounding. However the secondary vortex in rigid, no slip is stronger than before, and we can find the vortex shape which roll up more completely. However, these will disappear by the effect of wall.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.8
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• pp.2468-2479
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• 1996

An upper bound solution is obtained to perform the process analysis of hot strip rolling process. The material flows within the roll bite at various geometries and frictional conditions are obtained from finite element analysis and the typical flow pattern which is necessary to determine the kinematically admissible velocity field is assumed. From the kinematically admissible velocity field, the upper bound energy is calculated and the rolling load, angle of neutral point and forward slip ratio at various operational conditions are obtained from upper bound energy. The process analysis of above mentioned parameters at various operational conditions have provided valuable information which is hard to obtain during rolling operation and the predicted ranges of quantitive values from these analyses lie whthin the bound of actual operational data.