• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 1998.10a
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• pp.539-544
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• 1998

Generally, welding gap is a serious factor of a falling-off in weld quality among various kind of weld defect. Welding gap is created between two work piece in GMAW(Gas Metal Arc Welding) of horizontal fillet weld because surface of workpiece is not flat by cutting process. In these days, there were many attempts to detect welding gap. though we prevalently use the vision sensor or arc sensor in welding process, it is difficult to detect welding gap for improvement of welding quality. But we have a trouble to find relationship between welding gap and many welding parameters due to non-linearity of welding process. As mentioned about the various difficult problem, we can detect welding gap precisely using neural networks which are able to model non-linear function. Also, this paper was proposed real-time monitoring of weld bead shape to find effect of welding gap and to estimate weld quality. Monitoring of weld bead shape examined the correlation of welding parameters with bead eometry using learning ability of neural networks. Finally, the developed system, welding gap detecting system and bead shape monitoring system, is expected to the successful capability of automation of welding process by result of simulation.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2000.04a
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• pp.17-17
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• 2000

The issue of reflow profiling continues to be a complex topic. The pains often associated with profiling can be reduced greatly if certain guidelines are followed and if there is a strong understanding of the variables that can be encountered during the reflow process. This paper shall discuss the appropriate guidelines and trouble shooting methods for reflow profiling, and in particular shall focus upon the benefits of implementing the linear ramp-to-spike profile. Delta T(T) is defined as the variation of temperature found on an assembly during the reflow process. Too large of a T can result in soldering defects, so to combat T a Ramp-Soak-Spike(RSS) reflow profile often is utilized. However, when using a newer-style reflow oven, the T often is minimized or eliminated, thus, the soak zone of the reflow profile becomes an unnecessary step. Because of this, the implementation of a linear Ramp-To-Spike(RTS) reflow profile should be considered. Benefits such as reduced energy costs, reduced solder defects, increased efficiency, improved wetting, and a simplification of the reflow profile process may be experienced when using the RTS profile. Included in this paper are the suggested process parameters for setting up the RSS and RTS profiles and the chemical and metallurgical reactions that occur at each set point of these profiles. The paper concludes with a discussion and pictures of several profile-related defects. Each of these defects is described, analyzed, and instructions are given for troublshooting these defects.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• autumn
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• pp.432-437
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• 2002

As the working design process of Turn-Key projects is a basic process for the final contract, this process has lots of business decision to be made. Because such results of business decision can be the basis on contract documents, it is the step which needs a through management for Turn-key project. But in case of domestic construction companies, because those are not organized process of working design process, project manager has had lots of trouble at each process to make the business decision. As a means of settling the problems, this research is initiated. First, working decision management process is identified and generalized by interviews with project managers. Second, cases that actually happened in the project are investigated and categorized. Third, response plan to solve the problems and check lists to prevent the problems are suggested. Finally, the process, cases, response plan, and check list are integrated using CBR for future reuse.

• The Journal of Korean Association of Computer Education
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• v.9 no.1
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• pp.29-39
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• 2006

In this paper, we propose an adaptive tutoring system, which analyzes learning process, subject materials, and test items of students, diagnoses learning problems of them, and then gives proper advice accordingly. In the system, learning materials are constructed using concept map, on which the relationships among learning concepts are represented. Concept map can be used for several purposes in instruction process. Our work considers that new learning knowledge is dependent on what is already known. That is, it means that precedent concepts should be thoroughly learned for students to comprehend new concepts. After grasping the learning state of students for precedent concepts to be required before learning new concepts, our system provides proper learning materials for want of them, diagnoses the concepts which students have trouble to understand in the learning process, and provides suggestions for it.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1963-1966
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• 2005

Degenerative lumbar spinal stenosis(DLSS) is a disease inducing low back pain, leg pain, convulsion, numbness, and neurogenic claudication from compression of nerve root. Intervertebra fixation was reported to increase the degenerative of neighbor region after treatment. Recently, a new surgical technique of inserting a fixator between interspinous processes has been introduced. The purpose of this study is to design of the interspinous process fixator with flexibility to complement the trouble of using fixator in DLSS. This study evaluated the existing fixator through the mechanical test and modified fixators using the finite element analysis(FEA). Displacement, stiffness and Von-Mises stress were found to have similar values to those obtained from the mechanical test and the FEA in the biomechanical loading condition. Effects of variation in length and thickness were investigated to design an optimal fixator.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.3 s.180
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• pp.195-202
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• 2006

The degenerative lumbar spinal stenosis (DLSS) is a disease inducing low back pain, leg pain, convulsion. numbness, and neurogenic claudication from compression of nerve root. Intervertebra fixation was reported to increase the degeneration of neighbor lesion after treatment. Recently, a new surgical technique of inserting a fixator between interspinous processes has been introduced. The purpose of this study is to design the interspinous process fixator with flexibility to complement the trouble of using fixator in DLSS. This study evaluated the existing fixator through the mechanical test and modified it using the finite element analysis (FEA). The evaluation was based on the displacement, stiffness and von-Mises stress obtained from the mechanical test and calculated from the FEA in the biomechanical loading condition. Effects of variation in length and thickness were investigated to design an optimal fixator. Three prototypes were manufactured using FEA results. Mechanical tests under the biomechanical loading condition were performed to select the best one from these three. The selected fixator increased flexiblity by 32.9%.

• International Journal of Contents
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• v.16 no.4
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• pp.50-67
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• 2020

This study investigated whether writing weekly listening logs could influence college English learners' metacognitive awareness and listening proficiency. In addition, the Metacognitive Awareness Listening Questionnaire (MALQ) was applied to examine the learners' knowledge of their listening process. It is process-oriented research conducted by analyzing the MALQ and students' listening logs as to how their metacognitive awareness and listening proficiency have changed during the semester. Eighty-nine students who took an English listening practice course at a university participated in this study. The research findings are as follows. First, it turned out that there was a significant relationship between EFL university students' listening comprehension and some subscales of metacognitive awareness. Second, the students had an opportunity to reflect on learning through regular listening activities, and weekly listening logs, which included important information about listening process and practice. Third, as the students' listening proficiency increased at the end of the semester, it was found that introducing listening logs along with classroom lessons helped the students improve their listening ability. Finally, the high proficiency group students used multiple strategies simultaneously, regardless of the type of listening strategies, while the low proficiency group students used one or two limited listening strategies. However, the low proficiency group students may have had trouble expressing their ideas in English or recognizing the listening strategies they used, not because they did not use a lot of listening strategies. Therefore, teachers should regularly check if students are following their instructions and help them use appropriate strategies for better understanding.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.39 no.1
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• pp.116-122
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• 2016

Recently, the production cycle in manufacturing process has been getting shorter and different types of product have been produced in the same process line. In this case, the control chart using coefficient of variation would be applicable to the process. The theory that random variables are located in the three times distance of the deviation from mean value is applicable to the control chart that monitor the process in the manufacturing line, when the data of process are changed by the type of normal distribution. It is possible to apply to the control chart of coefficient of variation too. ${\bar{x}}$, s estimates that taken in the coefficient of variation have just used all of the data, but the upper control limit, center line and lower control limit have been settled by the effect of abnormal values, so this control chart could be in trouble of detection ability of the assignable value. The purpose of this study was to present the robust control chart than coefficient of variation control chart in the normal process. To perform this research, the location parameter, ${\bar{x_{\alpha}}}$, $s_{\alpha}$ were used. The robust control chart was named Tim-CV control chart. The result of simulation were summarized as follows; First, P values, the probability to get away from control limit, in Trim-CV control chart were larger than CV control chart in the normal process. Second, ARL values, average run length, in Trim-CV control chart were smaller than CV control chart in the normal process. Particularly, the difference of performance of two control charts was so sure when the change of the process was getting to bigger. Therefore, the Trim-CV control chart proposed in this paper would be more efficient tool than CV control chart in small quantity batch production.

• Journal of Korea Society of Digital Industry and Information Management
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• v.17 no.4
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• pp.177-195
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• 2021

The purpose of this study is to examine the trouble of recruitment and research and development of ICT SMEs. Recently, many ICT SMEs have emerged for selling products and services using the technology of the 4th industrial revolution. However, SMEs have relatively deficient resources compared to large companies, the difficulty of maintenance or growth of human resources and intangible resources. This research methodology organized the four stages of the analysis process. The first analysis is the association rules for human resource recruitment. The second analysis is the difficulty of hiring jobs and experienced workers by each stage of company growth. The third analysis is a regression analysis of the trouble of R&D activity. The last analysis is an analysis of association rules on the difficulties of management activities by company growth. As the research result, the first analysis has shown a difference in favored human resources by the ICT industry. The second analysis also showed factor differences in job recruitment difficulties for each stage of corporate growth. In the third analysis, the operation of research institutes in ICT SMEs is influenced by industry type, corporate certification, corporate growth stage, self-technology development, joint technology development, technology transfer, and commercialization. As the last analysis, ICT SMEs showed factor differences in difficulties in management activities by stage of corporate growth. This study contributed empirically emphasizing the troubling phenomenon of human resources and R&D necessary for the growth of ICT SMEs. As a theoretical implication, this research contributed to the research-area expansion of management information using big-data technologies. In particular, this research practically suggests the differentiated direction of recruitment and R&D by ICT SMEs based on industry and each stage of company growth through the association rules of big data.

• Journal of the Korean Wood Science and Technology
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• v.32 no.4
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• pp.46-51
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• 2004

The objective of this study was to evaluate the applicability of high temperature drying to pitch pine (Pinus rigida) lumber, especially intended for use as lamina of structural glued laminated timber (glulam), to enhance the efficient utilization and provide added-value to that species. The high temperature schedule and drying procedures utilized were shown to be reasonable for drying glulam lamina due to the occurrence of small moisture gradients, minimal residual drying stress, and low warpage. Through preliminary tests, it was confirmed that residual resin at lamina surfaces did not adversely affect the gluing process. However, quantitative analysis of resin is required for developing a method to constrain the occurrence of pitch trouble with respect to decreasing long-term adhesive and finish durability of glulam in use after manufacturing. The final moisture content of high temperature dried lamina was much lower than target moisture content and discoloration was more severe than anticipated. In a further study, it will be necessary to determine the optimal drying conditions, such as temperature, humidity, drying time, and top load restraint level, which could best control discoloration, warpage, and moisture content of the lamina, while minimizing fuel expense.