• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2001.04a
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• pp.27-34
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• 2001

The BGA Package has been the area array package of choice for several rears. Recently, the transition has been to finer pitch configuration called Chip Scale Packages (CSP). Several of these package types are available at 0.5 mm pitch, requiring surface mount assemblers to evaluate and optimize various elements of the assembly process. This presentation describes the issues associated with making the transition from BGA to CSP assembly. Areas addressed will include the accuracy of pick and piece equipment, printed wiring board lines and spaces, PWB vias, in-circuit test issues, solder paste printing, moisture related factors, rework and reliability. The transition to 0.5 mm pitch requires careful evaluation of the board design, solder paste selection, stencil design and component placement accuracy. At this pitch, ball and board pad diameters can be as small as 0.25 mm and 0.20 mm respectively. Drilled interstitial vias are no longer possible and higher ball count packages require micro-via board technology. The transition to CSP requires careful evaluation of these issues. Normal paste registration and BGA component tolerances can no longer achieve the required process levels and higher accuracy pick and place machines need to be implemented. This presentation will examine the optimization of these critical assembly operations, contrast the challenges at 0.5 mm and also look at the continuation of the process to incorporate smaller pitch flip chip devices.

• Journal of the Society of Naval Architects of Korea
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• v.30 no.4
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• pp.102-111
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• 1993

One of the most important design procedures for large sized structures is the evaluation of fracture strength against fatigue and brittle fractures threatening to occur in their steel members. In this paper, the safety assessment based upon the knowledge about the fracturing characteristics of such ship structures was discussed, which can be estimated from such phenomena as fatigue crack propagation and brittle fractures, as obtained by employing fracture mechanics at the basic design stage. Model tests with a partial structure specimen of full size was carried out to authenticate a question as to whether or not the fracturing characteristics of such sophisticated structures could be estimated with precision from ordinary scale specimen tests, It was shown that the behviour of fatigue crack growth of large sized structures in this study could be predicted from the results of ordinary scale specimen test.

• Journal of the Korea Fashion and Costume Design Association
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• v.9 no.3
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• pp.191-203
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• 2007

The purpose of this study was to present a making method of jeans pattern with high fitness after deriving the appropriate shrinkage rate by material and washing process. According to the result of the exterior evaluation of test jeans, all 6 jeans were rated high with scores close to 3.5. Following the evaluation of satisfaction of usage by physical movement, the highest ranking was in the order of walking with normal steps, back bending $90^{\circ}$, chair sitting, climbing stairs and squatting. The shrinkage rate by physical area showed the highest score in the order of pants length, waist circumference, thigh circumference, knee circumference, hem circumference, hips circumference. In addition, the shrinkage rate was higher in warp direction than weft direction after washing finishing. As for the result of addition and reduction of pattern measurements by parts of jeans, waist circumference was $3.1{\sim}5.1cm$, hips circumference was $-1.2{\sim}4.2cm$, thigh circumference was $-0.9{\sim}3.1cm$ and pants length was $3.4{\sim}6.1cm$. That is, this results showed a wide range of addition and reduction according to material and washing finishing.

• Steel and Composite Structures
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• v.8 no.5
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• pp.389-402
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• 2008

In December 2005, one(A) of the two pre-engineered warehouse buildings in the port of K City of Korea was completely destroyed and the other(B) was seriously damaged to be demolished. Over-loaded snow and unexpected blast of wind were the causes of the accident and destructive behavior was brittle fracture caused by web local buckling and lateral torsional buckling at the flange below rafter. However, the architectural design technology of today based on material non-linear method does not consider the tolerances to solve the problem of such brittle fracture. So, geometric non-linear evaluation which includes initial deformation, width-thickness ratio, web stiffener and unbraced length is required. This study evaluates the structural safety of 4 models in terms of width-thickness ratio and unbraced length using ANSYS 9.0 with parameters such as width-thickness ratio of web, existence/non-existence of stiffener and unbraced length. The purpose of this study is to analyze destructive mechanism of the above-mentioned two warehouse buildings and to provide ways to promote the safety of pre-engineered buildings.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.4
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• pp.180-188
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• 2003

The vehicle simulator is a useful virtual reality system. The simulator enables engineers to effectively research and analyze various experiments. Therefore, the development of a specific vehicle simulator is required, and its performance must be verified. This paper verifies the performance of Pusan National University Vehicle Simulator. Human sensibility ergonomic tests of vehicle simulator were also executed. The sense of simulator motion was chosen as the standard of performance evaluation. The driver's senses were subdivided into senses of rectilinear and rotational velocities. This study extracted ergonomic sensibility words that can be used to evaluate the performance of the simulator As a practical application of simulator, the relation was studied between the sense of simulator motion and the characteristics of drivers, who are classified into their sexes and driving careers. A statistical method was applied to human sensibility ergonomic tests of vehicle simulator.

• International Journal of Internet, Broadcasting and Communication
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• v.13 no.1
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• pp.107-115
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• 2021

This paper presents a smartphone application for the clinical practice education conducted in hospitals, with an aim to evaluate its effectiveness. A nonequivalent control group posttest design was used, which included a total of 100 nursing of school students who conducted their clinical practice. They were divided into one control and one experimental group (50 students each). The control group was directly trained in the clinical practice orientation, and the experimental group was a group who self-learned the clinical practice orientation using a smartphone application. Research data were collected between March 5 and April 27, 2019. They were analyzed with descriptive statistics and independent t-test, using the SPSS Statistics Version 24. The smartphone application customized for the clinical practice education was implemented through the following four phases: analysis, design, development, and evaluation. The developed application was registered in Google Play (for Android apps) and Apple Store, and related information was provided, making it available for download. The study showed that the satisfaction with and self-confidence in learning differed significantly between the groups. However, technology acceptance and knowledge acquired through practice showed no statistically significant difference. The research results serve as basic data for applying smartphone applications as an educational method that can replace traditional modes of education, serving as a significant indicator of the education delivery method diversification.

• International Journal of Advanced Culture Technology
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• v.10 no.2
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• pp.62-68
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• 2022

Evaluation as learning is important for the learner competency test, and the applicable method is studied. Assessment is the role of diagnosing the current learner's status and facilitating learning through appropriate feedback. The system is insufficient to enable process-oriented evaluation in small educational institute. Focusing on becoming familiar with the AI through experience can end up simply learning how to use the tools or just playing with them rather than achieving ultimate goals of AI education. In a previous study, the experience way of AI education with PLAY model was proposed, but the assessment stage is insufficient. In this paper, we propose ELAS (Experiential K-12 AI education Learning Assessment System) for small educational institute. In order to apply the Assessment factor in in this system, the AI-factor is selected by researching the goals of the current SW education and AI education. The proposed system consists of 4 modules as Assessment-factor agent, Self-assessment agent, Question-bank agent and Assessment -analysis agent. Self-assessment learning is a powerful mechanism for improving learning for students. ELAS is extended with the experiential way of AI education model of previous study, and the teacher designs the assessment through the ELAS system. ELAS enables teachers of small institutes to automate analysis and manage data accumulation following their learning purpose. With this, it is possible to adjust the learning difficulty in curriculum design to make better for your purpose.

• Journal of the Ergonomics Society of Korea
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• v.21 no.3
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• pp.25-34
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• 2002

The road sign in dynamic traffic system is an important element which affects on human cognitive performance on driving. Web-based vision system simulator was developed to examine the cognition time of the road sign in dynamic environment. This experiment the cognition time of the road sign in dynamic environment. This experiment was designed in with-subject design with two factors: vehicle speed and the amount of information of the traffic sign. It measured the cognition time of the road sign through two evaluation methods: the subjective test with vision system simulator and computational cognitive model. In these two evaluations of human cognitive performance under the dynamic traffic environment, it demonstrated that subject's cognition time was affected by both the amount of information of traffic sign and driving speed.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.1
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• pp.143-150
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• 1998

The evaluation of joint fatigue strength of light weight materials for electrical vehicle body has been performed through single lap joint tests with the design parameters such as joint style, adherend, bonding overlap length and bonding thickness. Fatigue strength was evaluated through 5-Hz, tension-tension, load controlled test with the stress ratio zero value. It is experimentally observed that fatigue strength of joint increases for the increase of overlap length. The combinations of Al-Al and Al-FRP adherends show that fatigue strength of joint is hardly changed for the increase of bonding thickness, but FRP-FRP adherend specimen shows that fatigue strength of joint increases after decreases for the increase of bonding thickness. Al-Al adherend specimen has much higher fatigue length than Al-FRP and FRP-FRP adherend specimens. Riveting at adgesive bonded joint gives little effect on fatigue strength.

• Proceedings of the Korea Society for Simulation Conference
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• 2002.05a
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• pp.163-168
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• 2002

The road sign in dynamic traffic system is an important element which affects on human cognitive performance on driving. Web-based vision system simulator was developed to examine the cognition time of the road sign in dynamic environment. This experiment was designed in within-subject design with two factors; vehicle speed and the amount of information of the traffic sign. It measured the cognition time of the road sign through two evaluation methods; the subjective test with vision system simulator and computational cognitive model. In these two evaluations of human cognitive performance under the dynamic traffic environment, it demonstrated that subject's cognition time was affected by both the amount of information of traffic sign and driving speed.