• Transactions of Materials Processing
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• v.18 no.1
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• pp.26-38
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• 2009

It was reported that the semi-solid forming process has many advantages over the conventional forming process, such as a long die life, good mechanical properties and energy savings. It is very important, however, to control liquid segregation to gain mechanical property improvement of materials. During forming process, rheology material has complex characteristics, thixotropic behavior. Also, difference of velocity between solid and liquid in the semi-solid state material makes a liquid segregation and specific stress variation. Therefore, it is difficult for a numerical simulation of the rheology process to be performed. General plastic or fluid dynamic analysis is not suitable for the behavior of rheology material. The behavior and stress of solid particle in the rheology material during forging process is affected by viscosity, temperature and solid fraction. In this study, compression experiments of aluminum alloy were performed under each other tool shape which is rectangle shape(square array), rectangle shape(hexagonal array), and free shape tool. In addition, the dynamics behavior compare with Okano equation to power law model which is viscosity equation.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.05a
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• pp.298-301
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• 2009

In this study, the casting process using forged insert was investigated to characterize the manufacturing process by which good mechanical properties can be obtained when compared with existing casting products. Process analysis for the casting design was performed by using FVM (Finite Volume Method) software. In filling process, three kinds of candidate gating systems are considered and analyzed respectively. The molten metal behavior in gating system is so important that it affects the solidification behavior of the cast.

• Human Ecology Research
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• v.62 no.2
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• pp.337-349
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• 2024

The aim of this study was to explore the mediating effects of adult attachment and marital satisfaction on the relationship between childhood maternal attachment and parenting behavior. A total of 372 mothers of preschoolers completed questionnaires on childhood maternal attachment, adult attachment, marital satisfaction, and parenting behavior. Adult attachment was analyzed by distinguishing between attachment anxiety and attachment avoidance. Parenting behavior was categorized into positive and negative behaviors. For the main analyses, Preacher and Hayes's PROCESS macro program was used to examine serial mediating effects. The results revealed that attachment anxiety mediated the effects of mothers' childhood attachment experiences on both positive and negative parenting behavior. However, attachment avoidance only mediated the effects on positive parenting behavior. Marital satisfaction mediated the effects of mothers' childhood attachment experiences on both positive and negative parenting behavior. Notably, the sequential mediating effects of attachment anxiety and marital satisfaction were not significant for either positive or negative parenting behavior. By contrast, the sequential mediating effects of attachment avoidance and marital satisfaction were significant for both positive and negative parenting behavior. These findings elucidate the predictive factors for parenting behavior within a process model framework, providing valuable insights for parental education and counseling aimed at enhancing mothers' parenting practices.

• Journal of the Korean institute of surface engineering
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• v.56 no.4
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• pp.250-258
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• 2023

Ceramic oxide layer was formed on the surface of high silicon aluminum alloy by using PEO (plasma electrolytic oxidation) process. The microstructure of the oxide layer was analyzed using scanning electron microscopy (SEM) and x-ray diffraction patterns (XRD). The high silicon aluminum alloy prior to PEO process consists of Al, Si and Al₂Cu phases in XRD analysis, whereas Al₂Cu phase selectively disappeared after PEO treatment. Considerable decrease of relative intensity in most of peaks in XRD results of the high silicon aluminum alloy treated by PEO process was observed. It may be attributed to the formation of amorphous phases after PEO treatment. The corrosion behavior of the high silicon aluminum alloy treated by PEO process was investigated using electrochemical impedance spectroscopy (EIS) and other electrochemical techniques (i.e., open circuit potential and polarization curve). Electroanalytical studies indicated that the high silicon aluminum alloy treated by PEO process shows greater corrosion resistance than that untreated by PEO process.

• Hwankyungkyoyuk
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• v.18 no.2 s.27
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• pp.76-89
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• 2005

The objectives of this study are to identify the environmental consumer behavior, to examine the degree of environmental consumer behavior of the junior high school students, and to investigate the educational system of a school which influence the consumer behavior. The data used in this study are 368 male and female students in 9th grade in Anyang City, Kyunggi-do province. Statistics used for data analysis are means, standard deviation, t-test, and Multiple Regression Analysis. The results of the research are summarized as follows : First of all, as a tendency of the environmental consumer behavior of junior high students, the primary factor to the environmental problems was media, and among those, TV and radio was the medium to environmental problems. This implies the fact that the time juveniles interact with mass media is significantly growing, which means that transmitting environmental problems by programs targeted to adolescences through mass media would be effective. Next, the disposal process showed the highest environmental consumer behavior, followed by the consuming and purchasing process. Education on the purchasing process will be necessary to encourage environmental consumer behavior. The route of obtaining environmental knowledge was basically from school and the level of the average environmental knowledge fumed out to be low. This shows the need to produce and distribute media education materials because educating the conclusion of actual experiments will be more effective than that of theoretical studies. The conformity showed general indifference on environmental consumer behavior and the environmental resources were normally collected seperated. Conformity is a cultural bond teenagers think important, therefore education available for students about the same age should be developed. Next, the value intention of the surveyed showed that the ecological intention was highest, followed by economic and convenience intentions. This means the morale of the junior high students to environmental consumer behavior is set sound. Females tended to act more environmentally, while males showed more intention to economic causes. Also, the students of the boys-only or girls-only schools showed higher environmentally sound behavior in disposal processes. Finally, the environmental consumer behavior was influenced most by environmental consumer behavior of the conformity group, followed by ecological morale, frequency of encountering environmental problems, gender, environmental knowledge, whether the school was boys-only or girls-only or not, economical morale, respectively. The largest factor affecting the consumer activity of the purchase, consumption, and disposal process was environmental consumer behavior of the conformity group, along with the ecological morale, and the frequency of encountering environmental problems. This implies that conformity group is a large factor to the juveniles and a plan to entice the environmental consumer behavior of conformity groups are necessary.

• Tribology and Lubricants
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• v.27 no.6
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• pp.351-355
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• 2011

Al/SiC composites were fabricated by thermal spray process, and the dry sliding wear tests were performed using the various sliding speed of 10, 30, 60 and 90 RPM through 1000 cycles. The applied load was 10 N and radius of wear track was 15 mm. Wear tracks on the Al/SiC composites were investigated using scanning electron microscope(SEM) and energy dispersive X-ray spectroscopy (EDS). In the case of sliding speed of 10 RPM, adhesive wear behavior caused by plastic deformation of composits surface was observed. In the cases of sliding speed of 30, 60, 90 RPM, abrasive wear behavior on the adhered layer formed by debris were observed. Through this study, it was found that the wear behavior of Al/SiC composites was mainly influenced by the sliding speed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.604-607
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• 2005

In the electro-discharge machining the machining performance is closely related to the characteristics of discharge which can be identified from electrical behavior in gap between workpiece and electrode. Therefore, the accurate prediction of electrical behavior in electro-discharge machining (EDM) is useful to process control and optimization. However, any simulation model fur prediction of electrical behavior in EDM process has never been reported until now. In this study, a simulation model is developed to analyze the electrical behavior of electro-discharge plasma which significantly influences electrical behavior in EDM process. For the purpose of this the fundamentals of electro-discharge mechanism such as inception, propagation, formation of plasma channel and termination are investigated to accurately predict the cycle of discharge plasma in EDM. As a result, a mathematical model of electro-discharge plasma is constructed with considering the fundamentals of electro-discharge plasma. Consequently, it is demonstrated that the developed model can predict the electrical behavior of plasma such as electron density in various conditions.

• Transactions of Materials Processing
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• v.19 no.8
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• pp.480-485
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• 2010

In this work, the closing behavior of cylindrical-shaped voids was experimentally investigated according to various parameters such as reduction ratio in height, initial void size and billet rotation during hot open die forging process. The reduction ratio in height, number of path, and billet rotation were chosen as key process parameters which influence the void closing behavior including the change of void shape and size. On the other hand, values of die overlapping and die width ratio were set to be constant. Void closing behavior was estimated by microscopic observation. Based on the observations, it was confirmed that application of billet rotation is more efficient to eliminate the void with less reduction ratio in height. The experimental results obtained from this study could be helpful to establish the optimum path schedule of open die forging process.

• Journal of the Korea Society for Simulation
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• v.19 no.1
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• pp.153-160
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• 2010

Most part of errors in software development process are included during the stage of requirements definition and design. And correction or elimination of errors from those stages requires much more efforts and costs than those from the later part of software development process. However, despite of the importance of the validation of requirement definition and design stages, several kinds of problem have made it hard to be done successfully. Therefore, in this paper, we introduce a novel validation process for the preliminary design stage. The validation process is based on simulations of model and it can be used to validate requirements and model simultaneously. Models in the validation process will take only the behavior of software and be built on Ptolemy framework. The usability of our validation process is confirmed with a case study over DNS system environment. And the result of simulation shows well-known errors or vulnerabilities can be found with simulations of model which has the behavior of software. This means our validation process can be used as a process to validate requirements and models during the early stage of software development process.

• Tunnel and Underground Space
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• v.18 no.6
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• pp.465-479
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• 2008

For the quantitative identification of rock behavior in shallow tunnels, we recommend using the rock behavior index (RBI) by the analytic hierarchy process (AHP) and the Rock Engineering Systems (RES). AHP and RES can aid engineers in effectively determining complex and un-structured rock behavior utilizing a structured pair-wise comparison matrix and an interaction matrix, respectively. Rock behavior types are categorized as rock fall, cave-in, and plastic deformation. Seven parameters influencing rock behavior for shallow depth rock tunnel are determined: uniaxial compressive strength, rock quality designation (RQD), joint surface condition, stress, pound water, earthquake, and tunnel span. They are classified into rock mass intrinsic, rock mass extrinsic, and design parameters. An advantage of this procedure is its ability to obtain each parameter's weight. We applied the proposed method to the basic design of Seoul Metro Line O and quantified the rock behavior into RBI on rock fall, cave-in, and plastic deformation. The study results demonstrate that AHP and RES can give engineers quantitative information on rock behavior.