• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.04a
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• pp.629-634
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• 2000

Generally, the accuracy of motion control systems is strongly influenced by both the mechanical characteristics and servo characteristics of feed drive systems. In the fed drive systems of machine tools that consist of mechanical parts and electrical parts, a torsional vibration is often generated because of its elastic elements in torque transmission. Especially, a torsional vibration caused by the elasticity of mechanical elements might deteriorate the quick movement of system and lead to shorten the life time of the mechanical transmission elements. So it is necessary to analyze the electromechanical system mathematically to optimize the dynamic characteristics of the feed drive system. In this paper, based on the simplifies feed drive system model, radius errors due to position gain mismatch and servo response characteristic have been developed and an optimal criterion for tuning the gain of speed controller is discussed. The proportional and integral parameter gain of the feed drive controller are optimal design variables for the gain tuning of PI speed controller. Through the optimization problem formulation, both proportional and integral parameter are optimally tuned so as to compensate the radius errors by using the genetic algorithm. As a result, higher performance on circular profile tests has been achieved than the one with standard parameters.

• Journal of Soil and Groundwater Environment
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• v.20 no.3
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• pp.1-6
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• 2015

The rapid industrial development is facing problem due to energy depletion in Korea. So that, it can be necessary to develop alternative energy sources. Alternative energy like biofuels can be produced by using waste fuel, which is ecofriendly. As we know, the organic waste was banned to dump in landfill and ocean dumping. The most practicable method usually used to reduce organic waste is getting feedstuff or composting, considering the discharge characteristics of agricultural by-products waste treatment were selected. In this study, bio-coal was made using agriculture by product. Biocoal was prepared by adding 50 g of uniformly mixture into reactor and was carbonized at low temperatures 210, 220, and 230℃. The time of reaction was 1, 2 and 3 hours. Bio-coal approximately was similar to the standard of solid fuels. Other characteristics of fuel were also studied. The experiments which were analyzed were moisture content and calorific value, ash, chlorine, sulfur and heavy metals analysis as mercury, cadmium, lead, arsenic, and chromium. As a result, bio-coal 220℃, 2 hours was the optimal conditions while heating.

• Korean Journal of Materials Research
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• v.17 no.8
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• pp.402-407
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• 2007

In electronics manufacturing processes, soldering process has generally been used in surface mounting technology. Because of environmental restriction, lead free solders as like a SnAgCu ternary system are being used widely. After soldering process, the formation and growth of intermetalic compounds(IMCs) are formed in the interface between solder and Cu substrate as follows isothermal temperature and time. In this studies, therefore, we investigated the effects of the Cu substrate thickness on the IMC formation and growth of Sn-40Pb/Cu and Sn-3.0Ag-0.5Cu/Cu solder joints, respectively. The effect of the Cu thickness in PCB Cu pad and pure Cu plate was analyzed as measuring of thickness of each IMC. After solder was soldered on PCB and Cu plate which have different Cu thickness, we measured the IMC thickness in solder joints respectively. Also we compared with the effectiveness of Cu thickness on the IMC growth. From these results, we calculated the activation energy.

• Korean Journal of Computational Design and Engineering
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• v.7 no.1
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• pp.9-17
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• 2002

The study is insufficient on process planning of the elliptical deep drawing product. Thus, in this present study, the expert system for elliptical deep drawing products was constructed by using process sequence design. The expert system was developed to be based on the general concept of each entity. The system was developed in this work consists of sixth modules. The first one is a shape recognition module to recognize non-axisymmetric products and to generate Entity_list. The second one is three dimensional (3-D) modeling module to calculate the surface area for non-axisymmetric products. The third one is a blank design module to create suggested blanks of three shapes with the identical surface area. The fourth one is shape design module based on the production rules that play the most important role in an expert system for manufacturing. The production rules are generated and upgraded by inter- viewing field engineers, plastic theory and experiments. The fifth and sixth ones are a graphic module to visualize results of the expert system and a post module to rise user's convenience, respectively. According to constructed the expert system for process sequence design, it was possible to reduce the lead time.

• Journal of the Korean Society of Safety
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• v.29 no.1
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• pp.86-92
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• 2014

This paper provides an integrated view on human and system interaction in advanced and automated systems, which adopting computerized multi-functional artifacts and complicated organizations, such as nuclear power plants, chemical plants, steel and semi-conduct manufacturing system. As current systems have advanced with various automated equipments but human operators from various organizations are involved in the systems, system safety still remains uncertain. Especially, a human operator plays an important role at the time of critical conditions that can lead to catastrophic accidents. The knowledge on human error helps a risk manager as well as a designer to create and control a more credible system. Several human error theories were reviewed and adopted for forming the integrated perspective: gulf of execution and evaluation; risk homeostasis; the ironies of automation; trust in automation; design affordance; distributed cognition; situation awareness; and plan delegation theory. The integrated perspective embraces human error theories within three levels of human-system interactions such as affordance level, psychological logic level and trust level. This paper argued that risk management process should dealt with human errors by providing (1) reasoning improvement; (2) support to situation awareness of operators; and (3) continuous monitoring on harmonization of human system interaction. This approach may help people to understand risk of human-system interaction failure characteristics and their countermeasures.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.32 no.1
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• pp.64-69
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• 2019

Methylammonium lead triiodide ($MAPbI_3$)-based perovskite solar cells potentially have potential advantages such as high efficiency and low-cost manufacturing procedures. However, $MAPbI_3$ is structurally unstable and has low phase-change temperatures ($30^{\circ}C$ and $130^{\circ}C$); it is necessary to solve these problems. We investigated the crystal structure and phase separation using real-time temperature-change X-ray diffraction, transmission electron microscopy, and electron energy loss spectroscopy. $MAPbI_3$ has a tetragonal structure, and at about $35^{\circ}C$ the c-axis contracts, transforming $MAPbI_3$ into the related cubic crystal structure. In addition, at $130^{\circ}C$, phase separation occurs in which $CH_3NH_2$ and HI at the center of the unit cell of the perovskite structure are extracted by gas, leavingand only $PbI_2$ of the three-component structure, is produced as the final solid product.

• Journal of Internet Computing and Services
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• v.22 no.4
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• pp.99-110
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• 2021

Governments around the world are actively establishing strategies and initiatives to spread the use of artificial intelligence (AI), for AI is not a mere new technology, but is an innovative technology that brings about extensive changes in industrial and social structures and is a core engine that will lead the 4th Industrial Revolution. The South Korean government has also been paying attention to AI as a technology and tool for innovative growth, but its application to the industries is still rather sluggish. The government has prepared multifarious AI-related policies with the aim of constructing South Korea as an AI powerhouse, but there is no clear strategy on which detailed policies to implement first and which industries to apply AI preferentially. With these limitations of South Korea's AI policies in mind, this paper analyzed the priorities of industries in AI adoption and the priorities of AI-related national policies, using Delphi-AHP method for 30 top-level AI experts in South Korea. The results of analysis show that AI application is urgent and necessary in the fields of medical/healthcare, public and safety, and manufacturing, which seems to reflect the peak of the COVID-19 crisis in the second half of 2020 at the time of the investigation. And it turns out that policies related to AI talent cultivation, data, and R&D investment are important and urgent above all in order for organizations to apply AI. This suggests that strategies are required to focus limited national resources on these industries and policies first.

• Journal of the Microelectronics and Packaging Society
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• v.28 no.2
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• pp.1-12
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• 2021

3D printing, which designs product in three dimensions, draws attention as a technology that will lead the future for it dramatically shortens time for production without assembly, no matter how complex the structure is. The paper studies the latest researches of 3D-printed electronics and introduces papers studied electronics components, power supply, circuit interconnection and 3D-printed PCBs' applications. 3D-printed electronics showed possibility to simplify facilities and personalize electric devices by providing one-stop printing process of electronic components, soldering, stacking, and even encapsulation.

• The Journal of Economics, Marketing and Management
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• v.12 no.4
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• pp.13-25
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• 2024

Purpose: Korea's construction industry has faced declining productivity and quality issues due to labor-intensive onsite construction and variables like weather, material price fluctuations, and labor shortages. The modular housing industry, introduced in Korea in 2003, offered benefits like reduced construction time and enhanced productivity through offsite manufacturing. However, its adoption remains limited due to high costs, quality concerns, and low consumer acceptance. Research Design, Data, and Methodology: This study explores the feasibility and impact of implementing smart factory technologies in the modular housing industry to overcome these barriers. Using survey data from 179 construction industry experts, the study employs frequency and regression analysis to identify key factors influencing the adoption of modular housing and the effectiveness of smart factories. Findings suggest that government-led educational programs and strong policy support are essential for successful implementation, enhancing productivity, reducing costs, and improving quality. Conclusions: The study emphasizes the need for standardization of modular housing, deregulation of relevant laws, and increased public awareness to stimulate market growth and innovation. Policy recommendations include financial support for modular manufacturers transitioning to smart factories, ensuring stable supply volumes, and promoting the benefits of modular housing to consumers. Integrating smart factory technologies can lead to significant advancements in the modular housing industry, contributing to the sustainable development and modernization of Korea's construction sector.

• International Commerce and Information Review
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• v.12 no.4
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• pp.303-325
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• 2010

This study concerns the identification of INPR process (i.e., antecedents, timeliness in new product development (NPD) and international new product rollout (INPR) and consequences) for international new product performance. It was empirically tested by a Korean sample to verify the validity of the research framework. The results show that cross-functional integration exhibited a statistically significant and positive effect on NPD timeliness. For the rapid development of new products, evidence is mounting in favor of cross-functional integration that facilitates both the quick dissemination and utilization of information. A higher level of marketing synergy was positively associated with a higher level of NPD timeliness. These findings suggest that marketing synergy plays a key role in enhancing NPD timeliness in South Korean manufacturing companies. The results also indicate that HQ-subsidiary cooperation was positively related to INPR timeliness. More comprehensive and varied information flows between HQ and subsidiary are likely to achieve product competitive advantage and then the latter may lead to international new product launch timeliness. However, technology synergy has no significant influence on NPD timeliness, implying that Korean manufacturers' managers do not recognize technology to be a major driving force, unlike Western manufacturers' managers. The findings also indicate that the positive effects of timeliness in INPR on international new product performance. It is important note that successful achievements of international new product success are likely to rely on INPR timeliness. Importantly, the results found that products developed within planned time frames are more likely to be rolled out into multi-markets on-time, resulting in higher levels of performance than when NPD completion is delayed.