• Korean Journal of Materials Research
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• v.23 no.9
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• pp.501-509
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• 2013

To evaluate the development of the microstructure and mechanical properties on surface modified and post-heattreated Inconel 718 alloy, this study was carried out. A friction stir process as a surface modification method was employed, and overlap welded Inconel 718 alloy as an experimental material was selected. The friction stir process was carried out at a tool rotation speed of 200 rpm and tool down force of 19.6-39.2 kN; post-heat-treatment with two steps was carried out at $720^{\circ}C$ for 8 h and $620^{\circ}C$ for 6 h in vacuum. To prevent the surface oxidation of the specimen, the method of using argon gas as shielding was utilized during the friction stir process. As a result, applying the friction stir process was effective to develop the grain refinement accompanied by dynamic recrystallization, which resulted in enhanced mechanical properties as compared to the overlap welded material. Furthermore, the post-heat-treatment after the friction stir process accelerated the formation of precipitates, such as gamma prime (${\gamma}^{\prime}$) and MC carbides, which led to the significant improvement of mechanical properties. Consequently, the microhardness, yield, and tensile strengths of the post-heat-treated material were increased more than 110%, 124% and 85 %, respectively, relative to the overlap welded material. This study systematically examined the relationship between precipitates and mechanical properties.

• Korean Institute of Interior Design Journal
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• v.16 no.1 s.60
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• pp.21-30
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• 2007

Frank O. Gehry is known to be an architect whose work ranges over different realms, especially between fine arts and architecture. He himself mentioned about this interdisciplinary aspect of his own work: he was inspired by, worked together with, and sometimes directly influenced by contemporary artists. Among the artists, the most influential ones are the sculptors, especially Richard Serra of Post-Minimalism and Claes Oldenburg of Pop Art. Based on this historically known fact, although very brief, this study explores how the features of Post-Minimal sculpture were transferred into Gerhy's architecture, and how Gehry has developed them into his own language. In Post-Minimal sculpture, the main concept 'Anti-Form' was realized by emphasis on materiality, process and intuitiveness of work of in. Those features appeared vividly in Gehry's works especially in his second stage of his life, but seemed to have disappeared in the third stage. However, in the fourth stage, Gehry went beyond the influence of Post-Minimalism, and he created very unique formal language dialectically formed between Post-Minimal sculptural language and his architectural language.

• Journal of the Korean Society for Precision Engineering
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• v.32 no.9
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• pp.781-786
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• 2015

Recently, studies of 3D printing methods have been working in various applications. For example, the powder base method laminates the prints by using a binding or laser sintering method. However, the draw back of this method is that the post process is time consuming and does not allow for parts to be rapidly manufactured. The binding method requires the post process while the time required for the post process is longer than the manufacturing time. This paper proposes a UV curing binding method with an integrated piezo printing head system. The optimization of an arbitrary waveform generation for the control of a UV curable resin droplet was researched, in addition to developed optimized UV curing processes in multi nozzle ink jet heads.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.11
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• pp.30-35
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• 2021

In this study, a machine simulation system was built using the actual scale of an AC-type 5-axis machine tool for mold surface machining that can be used in applications, such as, modeling and machine building, stroke, and collision detection. The validity of the 5-axis machine simulation system was verified by performing tool path generation, post-processing, machine simulation, prototype motion simulation, and an actual cutting experiment. This entire process was intended to activate the 5-axis machining in mold surface machining.

• Korean Journal of Child Studies
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• v.29 no.1
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• pp.275-292
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• 2008

This study investigated the effects of a teaching process using dynamic assessment for a unit on young children's measurement ability. Subjects were 45 5-year-old children in a kindergarten in Busan. The instrument was the Dynamic Assessment Tools for Young Children's Measurement Ability (Hwang & Ko, 2(07). Assessment consisted of four steps: pre-test, learning, transfer, post-test. Results were that at post-test, there were significant differences in scores of measurement ability between the dynamic assessment and control groups. In the dynamic assessment group there was significant improvement in length, width and weight between pre- and post-tests and there were significant shifts of measurement strategies and measurement errors between the pre- and post-tests.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2012.11a
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• pp.169-170
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• 2012

It is analyzed that constructability of post-tensioning system applying HDPE greased strand that is greased and coated by high density polyethylene on a bare strand in reactor containment building. The improvement of corrosion resistance by greasing and HDPE coating on a strand makes transportation, handling and installation of tendon to be easier. Therefore, serial and repetitive process of post-tensioning composed of construction preparation, tendon installation, stressing and anchoring, grease injection could be improved parallel and lumping process of installation and grouting, stressing and anchoring.

• Journal of the Korean Society of Clothing and Textiles
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• v.30 no.6 s.154
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• pp.961-970
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• 2006

This study attempted to understand post-purchase consumer return experiences which had not received much attention in consumer behavior research. As a first step to understand return experiences from consumers' viewpoint, the study took an exploratory approach and identified themes and patterns from subjective consumer experiences. Whenever possible, attribution theory was applied to interpret the identified patterns. A total of 99 cases were collected from an open-ended questionnaire and analyzed based on a qualitative method. The reasons of product return was classified into five groups: changing mind; product defects; unsuitable products; products not expected; and for a better deal. External attribution was observed for return decisions caused by consumers' changed mind as well as by product defects. Dissatisfaction with defected products seemed to be intensified or reduced by service failure or success in the post-purchase service encounter. Consumer expectation and situations seemed to affect this process. Overall, the study supported attribution theory in the post-purchase return experience, and insights for research questions were proposed.

• Journal of the Korean Operations Research and Management Science Society
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• v.22 no.3
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• pp.99-111
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• 1997

We consider a production system with post-operation and early set-up. As soon as there are no more units(raw materials) to process and the machine becomes idle, it undergoes a post-operation. After the post operation, if the number of waiting units is greater than or equal to m, it begins a set-up. After the set-up, if the number of units is greater than or equal to N($\geq$m), it begins to process the units. We first analyze the system by employing the decomposition property of the vacation queue. We, then, propose an algorithm that finds the optimal threshold values ($m^*$, $N^*$). Finally we present some numerical examples and interprete the system behavior.

• Journal of the Korean Home Economics Association
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• v.40 no.6
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• pp.197-211
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• 2002

This study constructed a family life education program designed to help divorced parents. The purpose of this research was to develop long term education program for post-divorce adjustment. This program is consisted of 6 sessions aiming for understanding the grief process for adults and the six station of divorce, the recovery through forgiveness, children's response to divorce and coping strategy, the opened mind of parent-child relation, enhancing the self-esteem, the healthy single parent. We expect this program to be helpful in helping divorced parents'post-divorce adjustment, improving parent-child relation and helping future life of divorced parents.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1193-1198
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• 2003

Translucent plastics are commonly used in packaging of mechanical and/or electrical components. Although Rapid Prototyping(RP) provides prototypes of various materials, translucent RP parts are not readily available from most RP processes. ABSi is one of the ABS materials available for Stratasys' FDM process, and the material has potential to be translucent. In this paper, two post-processing techniques were applied in order to increase optical transmissivity of the parts made of FDM's ABSi. First, elevated temperature condition was applied resulting in increased transmissivity while dimensional shrinkage was observed. Second, resin infiltration and surface sanding provided upto 16% transmissivity without shrinkage. These post-processes can be selectively applied to increase transmissivity of ABSi parts. Thus, translucent FDM part can be fabricated from regular FDM process followed by the post-processes developed in this study.