• Journal of the Korea Institute of Military Science and Technology
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• v.23 no.3
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• pp.195-203
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• 2020

Selective laser melting(SLM) is one of the powder bed fusion(PBF) processes, which enables quicker production of nearly fully dense metal parts with a complex geometry at a moderate cost. However, the process still lacks knowledge and the experimental evaluation of possible process parameter sets is costly. Thus, this study presents a finite element analysis model of the SLM process to predict the melt pool characteristics. The physical phenomena including the phase transformation and the degree of consolidation are considered in the model with the effective method to model the volume shrinkage and the evaporated material removal. The proposed model is used to predict the melt pool dimensions and validated with the experimental results from single track scanning process of Ti-6Al-4V. The analysis result agrees with the measured data with a reasonable accuracy and the result is then used to evaluated each of the process parameter set.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.313-313
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• 2008

Aerosol Deposition(AD) method is based on the impact consolidation phenomenon of ceramic fine particles at room temperature. AD is promising technology for the room temperature deposition of the dielectrics thin films with high quality. Embedding of passive components such as capacitors into printed circuit board is becoming an important strategy for electronics miniaturization and device reliability, manufacturing cost reduction. So, passive integration using aerosol deposition. In this study, we examine the effects of the characteristics of raw powder on the thickness, roughness, electrical properties of $BaTiO_3$ thin films. Thin films were deposited on the copper foil and copper plate. Electrical and material properties was investigated as a change of annealing temperature. We final aim the effects of before and after of laminated on the electrical properties and suit of embedded capacitor.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.23 no.6
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• pp.703-714
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• 2010

This paper proposes an approach for staged finite element modeling with coupled seepage and stress analysis. The stage modeling is based on the predefined inter-relationship between the base model and the unit stage models. A unit stage constitutes a complete finite element model, of which the geometries and attributes are subject to changes from stage to stage. The seepage analysis precedes the mechanical stress analysis at every stage. Division of the wet and dry zone and the pore pressures are evaluated from the seepage analysis and used in determining input data for the stress analysis. The results of the stress analysis may also be associated with the pore water pressures. For consolidation analysis, the pore pressure and the displacement variables are mixed in a coupled matrix equation. The time marching solution produces the dissipation of excess pore pressure and variation of stresses with passage of time. For undrained analysis, the excess pore pressures are computed from the stress increment due to loading applied in the unit stage and are used in revising the hydraulic head. The solution results of a unit stage are inherited and accumulated to the subsequent stages through the relationship of the base model and the individual unit stages. Implementation of the proposed approach is outlined on the basis of the core procedures, and numerical examples are presented for demonstration of its application.

• Journal of Wetlands Research
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• v.11 no.2
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• pp.89-98
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• 2009

This study determines the stream mean slope, stream slope and longitudinal stream profile based on the concept of informational entropy. Maximizing the entropy will make the probability distribution of longitudinal stream profile as uniform as possible while satisfying the constraints. Using this relationships the mean stream slope, stream slope and longitudinal stream profile formulas were derived. The parameters of the applied streams were estimated by the least square method using the geomorphological factors of Dalchon stream basin obtained from Chungcheong Buk-Do local stream consolidation scheme drawings. The comparative investigation was performed between the observed and simulated mean stream slope and longitudinal stream profile, and are in good agreement with the measured data. It is noted that this results can be used in the estimation of stream mean slope and longitudinal stream profile.

• Korea Journal of Hospital Management
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• v.16 no.1
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• pp.77-100
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• 2011

The purpose of this study is to the improvement of general hospital outpatients waiting time using Theory Of Constraints(TOC) methodology and to the development of a Reception Desk in general hospital. This study is to provide decision-making guidelines for hospital managers and to provide feedback for the efficiency of job process. The target people of the study are outpatients and Cashiers on Chungnam national university hospital in Daejeon. The methods of study are summarized as follows. First, The team managers from a Reception Desk group were appointed. This team managers have the adjustment authority to the Outpatients schedule of doctor and Cashier members. Second, The consolidation of the general Reception desk and special inspection the Reception Desk. A movement line and waiting time of patients were simple and fast to accept. As a result of study, it shows that the TOC is the method for a job process and waiting time improvement, patients' satisfaction increase and we need an objective measurement indexes in the medical treatment industry.

• Journal of Dairy Science and Biotechnology
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• v.29 no.2
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• pp.59-68
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• 2011

In Korea, there are a couple of risk assessment organizations: The Animal Plant and Fisheries Quarantine and Inspection Agency(QIA) and the Korea Food and Drug Administration (KFDA). The major food laws include the Food Sanitation Act (FSA), the Livestock Product Processing Act (LPPA), and the Agricultural Products Quality Control Act (APQCA). Milk and dairy products are mostly controlled by the Food Sanitation Act and the Livestock Product Processing Act. This study was carried out to estimate the current standard methods of foodborne pathogens for dairy products, comparing the Livestock Products Processing Act with the Food Sanitation Act. The standard methods of foodborne pathogens for dairy products are composed by growth culture, isolation culture, and identification, however, standard methods of QIA and KFDA are different at the using of medium and inspection stage. Therefore, consolidation of risk management and risk assessment methods are regarded important to provide safe dairy products to consumer.

• Journal of Navigation and Port Research
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• v.31 no.4
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• pp.317-323
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• 2007

As economic trade between Korea and China has been encouraged with the rapid growth of Chinese economy and port competition in Northeast Asia, Korean government is trying to promote development and consolidation of ports to cope with the lack of facilities. Thus, many projects for port development have been propelled including the enactment the 'Private investment promotion law for social overhead capital 1994.' However, there are still some unsettled issues since considerable part of risk is still allocated to the Government when it has to support the private businesses in these port investments whenever unexpected problems arise. Allocation of risk among the participants - in this case especially - is a very subtle issue, however, it was revealed that not many precedent researches were done on the subject. In my previous research, I classified and analyzed 4 principle risks i.e, construction, management, financial and social risk. This research investigates the reasonable allocation of the risks among the participants using the Hierarchial Fuzzy Process. In the result of analysis, responsibility of private party is the most important and it must put the responsibility before Government' roll concerned. Also, this research displayed and proposed the direction of management method on port development in a view of minimizing risk and maximizing initiative of a private party.

• Korean Journal of Metals and Materials
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• v.50 no.12
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• pp.961-966
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• 2012

Nano-sized Co and $Al_2O_3$ powders were successfully synthesized from $3/4Co_3O_4$ and 2Al by high-energy ball milling. A dense nanocrystalline $2.25Co-Al_2O_3$ composite was consolidated from mechanically synthesized powders by the pulsed current activated sintering (PCAS) method within 2 min. Consolidation was accomplished under the combined effects of a pulsed current and mechanical pressure. A dense $2.25Co-Al_2O_3$ with relative density of up to 95% was produced under simultaneous application of a 80 MPa pressure and a pulsed current of 2800 A. The fracture toughness and hardness of the $2.25Co-Al_2O_3$ composite were $8MPa{\cdot}m^{1/2}$, $870kg/mm^2$, respectively.

• Korean Journal of Metals and Materials
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• v.47 no.6
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• pp.344-348
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• 2009

Dense $4.25Co_{0.53}Fe_{0.47}-Al_{2}O_{3}$ composite was simultaneously synthesized and consolidated by pulsed current activated combustion method within 2 min from mechanically activated powders. Consolidation was accomplished under the combined effects of a pulsed current and mechanical pressure. Dense $4.25Co_{0.53}Fe_{0.47}-Al_{2}O_{3}$ with relative density of up to 96% was produced under simultaneous application of 80 MPa pressure and the pulsed current. Fracture toughness and hardness of the composite are $6MPa{\cdot}m^{1/2}$ and $570kg/mm^{2}$ respectively.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.19 no.2
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• pp.233-241
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• 2021

A series of three bench-scale experiments was performed to investigate the conversion of sodium metal to sodium chloride via reactions with non-metal and metal chlorides. Specifically, batches of molten sodium metal were separately contacted with ammonium chloride and ferrous chloride to form sodium chloride in both cases along with iron in the latter case. Additional ferrous chloride was added to two of the three batches to form low melting point consolidated mixtures of sodium chloride and ferrous chloride, whereas consolidation of a sodium-chloride product was performed in a separate batch. Samples of the products were characterized via X-ray diffraction to identify attendant compounds. The reaction of sodium metal with metered ammonium chloride particulate feeds proceeded without reaction excursions and produced pure colorless sodium chloride. The reaction of sodium metal with ferrous chloride yielded occasional reaction excursions as evidenced by temperature spikes and fuming ferrous chloride, producing a dark salt-metal mixture. This investigation into a method for controlled conversion of sodium metal to sodium chloride is particularly applicable to sodium containing elevated levels of radioactivity-including bond sodium from nuclear fuels-in remote-handled inert-atmosphere environments.