• Journal of the Korea Society for Simulation
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• v.31 no.3
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• pp.23-34
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• 2022

Due to the characteristics of the railway system, a fleet consists of multiple railway vehicles, and a project contract is made by supplying multiple fleets to the customer. If the project fails to meet the due date, the manufacturer must compensate for the delay to the customer. In this paper, we analyze the operation strategies of the railway vehicle manufacturing factory using simulation, in which the layout adopts the concept of the flow lines, and when shortages of parts are considered. If there is a shortage of parts, the subsequent assembly process cannot proceed due to the nature of the assembly process. Thus, in order to overcome this problem, three strategies for performing assembly work are presented when the events of shortages are occurred. We also compare the strategies with respect to reduce the total cost which includes labor costs and compensation costs for delay.

• Journal of the Korea Society for Simulation
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• v.32 no.3
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• pp.67-74
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• 2023

A semiconductor fabrication facility(FAB) is one of the most capital-intensive and large-scale manufacturing systems which operate under complex and uncertain constraints through hundreds of fabrication steps. To improve fab performance with intuitive scheduling, practitioners have used weighted-sum scheduling. Since the determination of weights in the scheduling significantly affects fab performance, they often rely on simulation-based decision making for obtaining optimal weights. However, a large-scale and high-fidelity simulation generally is time-intensive to evaluate with an exhaustive search. In this study, we investigated three sampling methods (i.e., Optimal latin hypercube sampling(OLHS), Genetic algorithm(GA), and Decision tree based sequential search(DSS)) for the optimization. Our simulation experiments demonstrate that: (1) three methods outperform greedy heuristics in performance metrics; (2) GA and DSS can be promising tools to accelerate the decision-making process.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.6
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• pp.407-410
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• 2018

As the operating frequency of an electromagnetic wave increases, the maximum output and wavelength of the wave decreases, so that the size of the circuit cannot be reduced. As a result, the fabrication of a circuit with high power (of the order of or greater than kW range) and terahertz wave frequency band is limited, due to the problem of circuit size, to the order of ${\mu}m$ to mm. In order to overcome these limitations, we propose a source design technique for 0.1 THz~0.3 GW level with cylindrical shape (diameter ~2.4 cm). Modeling and computational simulations were performed to optimize the design of the high-power electromagnetic sources based on Cherenkov radiation generation technology using the principle of plasma wakefield acceleration with ponderomotive force and artificial dielectrics. An effective design guideline has been proposed to facilitate the fabrication of high-power terahertz wave vacuum devices of large diameter that are less restricted in circuit size through objective verification.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.10
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• pp.841-850
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• 2015

With the rapid progress of electronics and radio communication technology, human enjoys greater freedom in information communication. However, EMW(Electro-Magnetic Wave) environments have become more complicate and difficult to control. Thus, international organizations, such as the American National Standard Institution(ANSI), Federal Communications Commission(FCC), the Comite Internationale Special des Perturbations Radio Electrique(CISPR), etc, have provided standard for controlling the EM wave environments and for the countermeasure of the electromagnetic compatibility(EMC). In this paper, fabrication of the smart EMW absorber which has heat radiating function and high performance absorption abilities were suggested. Furthermore, we prospected future smart EMW absorbers. The designed smart EMW absorber is fabricated following process. Firstly, we applied high temperature heat treated to a mixture of Iron-oxide($Fe_2O_3$) and ceramics. Secondly, we applied low temperature heat treated to the mixture of heat treated material and a carbon material. Lastly, we made apertures on the absorber. The designed smart EM wave absorber has the absorption ability of more than 20 dB from 2 GHz to 2.45 GHz band, respectively. Thus, it is respected that these results can be applied as various EMC devices in electronic, communication, and controlling systems.

• Journal of Korean Society of Steel Construction
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• v.28 no.1
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• pp.13-22
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• 2016

Recently, interest for environmental pollution in various fields is on the increase, and the researches on the life cycle assessment of environmental performance assessment method for calculating the environmental loads are currently most performed. It is expected to have a significant influence on the environment, since SOC infrastructures are go through a variety of materials, manufacturing process, however it is judged that researches and measures for environmental pollution is insufficient. In this study, we build the data for 204 of steel bridge designed after 2000 year, and the 100 of bridge which were selected to from obtained results were calculated the environmental loads at the planning stage based on the life cycle assessment. In addition, standard classification systems in work type for steel bridges were established. Based on this, the basic design data and input materials for the bridges are applied to the LCI DB, and the environmental load for required material is evaluated and is shown as Eco-point. Environmental loads obtained from this study, it is judged that can be utilized as a basic data for the process of the life cycle assessment in future steel bridge design.

• Journal of Venture Innovation
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• v.5 no.1
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• pp.107-127
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• 2022

Global challenges such as the corona pandemic, climate change and the war-on-tech ensure that the demand who the technologies of the future develops and monitors prominently for will be on the agenda. Development of, and applications in, agrifood, biotech, high-tech, medtech, quantum, AI and photonics are the basis of the future earning capacity of the Netherlands and contribute to solving societal challenges, close to home and worldwide. To be like the Netherlands and Europe a strategic position in the to obtain knowledge and innovation chain, and with it our autonomy in relation to from China and the United States insurance, clear choices are needed. Brainport Eindhoven: Building on Philips' knowledge base, there is create an innovative ecosystem where more than 7,000 companies in the High-tech Systems & Materials (HTSM) collaborate on new technologies, future earning potential and international value chains. Nearly 20,000 private R&D employees work in 5 regional high-end campuses and for companies such as ASML, NXP, DAF, Prodrive Technologies, Lightyear and many others. Brainport Eindhoven has a internationally leading position in the field of system engineering, semicon, micro and nanoelectronics, AI, integrated photonics and additive manufacturing. What is being developed in Brainport leads to the growth of the manufacturing industry far beyond the region thanks to chain cooperation between large companies and SMEs. South-Holland: The South Holland ecosystem includes companies as KPN, Shell, DSM and Janssen Pharmaceutical, large and innovative SMEs and leading educational and knowledge institutions that have more than Invest €3.3 billion in R&D. Bearing Cores are formed by the top campuses of Leiden and Delft, good for more than 40,000 innovative jobs, the port-industrial complex (logistics & energy), the manufacturing industry cluster on maritime and aerospace and the horticultural cluster in the Westland. South Holland trains thematically key technologies such as biotech, quantum technology and AI. Twente: The green, technological top region of Twente has a long tradition of collaboration in triple helix bandage. Technological innovations from Twente offer worldwide solutions for the large social issues. Work is in progress to key technologies such as AI, photonics, robotics and nanotechnology. New technology is applied in sectors such as medtech, the manufacturing industry, agriculture and circular value chains, such as textiles and construction. Being for Twente start-ups and SMEs of great importance to the jobs of tomorrow. Connect these companies technology from Twente with knowledge regions and OEMs, at home and abroad. Wageningen in FoodValley: Wageningen Campus is a global agri-food magnet for startups and corporates by the national accelerator StartLife and student incubator StartHub. FoodvalleyNL also connects with an ambitious 2030 programme, the versatile ecosystem regional, national and international - including through the WEF European food innovation hub. The campus offers guests and the 3,000 private R&D put in an interesting programming science, innovation and social dialogue around the challenges in agro production, food processing, biobased/circular, climate and biodiversity. The Netherlands succeeded in industrializing in logistics countries, but it is striving for sustainable growth by creating an innovative ecosystem through a regional industry-academic research model. In particular, the Brainport Cluster, centered on the high-tech industry, pursues regional innovation and is opening a new horizon for existing industry-academic models. Brainport is a state-of-the-art forward base that leads the innovation ecosystem of Dutch manufacturing. The history of ports in the Netherlands is transforming from a logistics-oriented port symbolized by Rotterdam into a "port of digital knowledge" centered on Brainport. On the basis of this, it can be seen that the industry-academic cluster model linking the central government's vision to create an innovative ecosystem and the specialized industry in the region serves as the biggest stepping stone. The Netherlands' innovation policy is expected to be more faithful to its role as Europe's "digital gateway" through regional development centered on the innovation cluster ecosystem and investment in job creation and new industries.

• Polymer(Korea)
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• v.31 no.4
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• pp.329-334
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• 2007

Osmotic pellet system, which is one of the oral drug delivery systems, has been developed to improve manufacturing process, reduce product cost and other problems of osmotic tablet systems. Osmotic pellet is consisted of water swellable seed layer, drug layer, and membrane layer. Among them, the membrane layer plays an important role in a control of the drug release. In this work, we examined the effect of ratio for Eudragit RL and RS on the drug release behavior. Osmotic pellet with nifedipine as a model drug was easily obtained in a good yield by fluidized bed coater. Osmotic pellet showed round morphology with a range of size $1300{\sim}1500\;{\mu}m$. In the experiment of nifedipine release, the release amount increased with the increase of the ratio of Eudragit. This is due to the fact that Eudragit RL contains more hydrophilic quaternary ammonium group than Eudragit RS. Additionally, the release amount was retarded with increasing the membrane thickness. There are no differences in the release amount measured at the different pH 1.2, 6.5, 6.8, and 7.2. In conclusion, it was found that the drug release from osmotic pellets depended on the composition ratio and coating thickness of membrane layer.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.12B
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• pp.1744-1751
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• 2011

The concept of the advanced concept technology demonstration (ACTD) has previously been introduced in USA in order to make it possible to rapidly transfer advanced technologies developed in commercial sectors to develop weapon systems in the defense area. Since then in Korea several ACTD programs have been developed and being carried out However, there are few program management methods suitable for the characteristics of the ACTD programs, which requires stringent management of the program requirements and risks due to the radically shortened development time. In this paper such a problem has been addressed and as a solution approach the quality function deployment (QFD) method has been adopted, which is being served as a successful model in various areas such as manufacturing. The QFD method is used in our study to improve communication between various stakeholders involved in the ACTD programs and also to reduce risks related to requirements. Specifically we have developed the ACTD standard templates based on the QFD method and discussed how to use the developed templates. Finally, the application of the study result is demonstrated through the ACTD program of flight information demonstration system and also specific ways are suggested to use the standard templates, to manage requirements, and to reduce risks.

• Journal of Aerospace System Engineering
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• v.14 no.5
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• pp.130-138
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• 2020

In this paper, a plan to expand the scale of the domestic MRO industry was proposed by finding the technical common points between the aviation MRO and naval vessel MRO industries. The aviation MRO industry is led by Europe, North America, and Singapore. Europe and North America have very large aviation industries. The reason for the development of the MRO industry in Singapore is that the aviation MRO and ship MRO industries gathered to expand the industrial scale. The MRO field is an industry that spans all fields from research & development, production, manufacturing, operation, disposal, and crew training. The MRO industry is divided into military and civilian use. However, most of them are only differences in the needs of users, and there are no significant technical differences. The weapon system used by the military is steadily developing. It is impossible for the military to maintain all equipment at a time when troops are reduced. For that reason, it is necessary to share roles in each field. There is a need for an MRO industry in which civil and military operations cooperate to maintain all weapon systems at optimal performance. And the MRO industry development should be based on the civil market. The scale of the MRO industry should be expanded by gathering equipment commonly used in aircraft and naval vessels. This can increase military availability and reduce maintenance budgets.

• Membrane Journal
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• v.32 no.6
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• pp.427-441
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• 2022

Polymer electrolyte membrane (PEM) serving as a separator that can prevent the permeation of unreacted fuels as well as an electrolyte that selectively transports protons from the anode to the cathode has been considered a key component of polymer electrolyte membrane fuel cell (PEMFC). The perfluorinated sulfonic acid-based PEMs, represented by Nafion®, have been commercialized in PEMFC systems due to their high proton conductivity and chemical stability. Nevertheless, these PEMs have several inherent drawbacks including high manufacturing costs by the complex synthetic processes and environmental problems caused by producing the toxic gases. Although numerous studies are underway to address these drawbacks including the development of sulfonated hydrocarbon polymer-based PEMs (SHP-PEMs), which can easily control the polymer structures, further improvement of PEM performances and durability is necessary for practical PEMFC applications. Therefore, this study focused on the various strategies for the development of SHP-PEMs with outstanding performance and durability by 1) introducing cross-linked structures, 2) incorporating organic/inorganic composites, and 3) fabricating reinforced-composite membranes using porous substrates.