• Tribology and Lubricants
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• v.32 no.6
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• pp.201-206
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• 2016

In this study, we attempt to produce a semi-elliptical riblet with a shark skin-like surface using wire electrical discharge machining (WEDM) and micro molding techniques. Our design for the production of the semi-elliptical mold includes an electrode, a winding roller, and a guide on the WEDM system. A replication mold with negative riblets is machined using WEDM, and a shark skin inspired surface with positive riblets is fabricated using a micro molding technique. For a comparison with the original shark skin, a shark skin replica is also produced using the micro molding technique directly from a shark skin template. Droplet contact angles on a flat surface, the shark skin replica, and the epoxy resin-based micro riblet shark skin-like surface are evaluated. The effect of a Teflon coating on the contact angles for the three different surfaces is also investigated. The results show the micro riblet with a shark skin-like surface has a similar contact angle as the shark skin replica, which means that the simplified riblet shark skin surface strongly influences the performance of wettability. This study confirms the effectiveness of using the WEDM method to prepare hydrophobic surfaces with diverse surface patterns.

• Journal of Industrial and Engineering Chemistry
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• v.68
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• pp.196-208
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• 2018

The effect of channel-system of zeolite on methanol-to-DME reaction was studied. Results revealed that channels size and topology affect catalyst lifetime, type and location of coke precursors. FER and MFI showed the best resistance towards coke deposition, whilst fast deactivation was observed on MOR. Although the higher concentration and strength of acid sites, FER structure formed a lower coke amount, preferably located within the pores, while coke cluster deposited on the external surface of MOR. Analysis of acid sites distribution and strength was performed during deactivation-regeneration process. Coke location assessment was also supported by molecular simulations.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2019.11a
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• pp.143-144
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• 2019

Recently, environmental pollution related to global warming is on the rise. Meanwhile, renewable energy is a representative example of many efforts to develop eco-friendly energy to solve the depletion of natural resources and the depletion of petroleum resources in conjunction with global warming. Among them, photovoltaic power generation is increasing the subsidies for the government to increase the production of photovoltaic electricity of the general public, showing a high growth rate. However, polysilicon, which is a raw material of the photovoltaic panel, generates waste called polysilicon sludge in the manufacturing process. In order to produce 1 ton of polysilicon, about 2 tons of waste polysilicon sludge is generated. In 2012, polysilicon sludge was generated at 78,000 tons, with an average of about 220 tons per day. The sludge generated due to insufficient treatment of polysilicon sludge is currently solidified and is processed by landfilling. Therefore, in this study, polysilicone sludge is used as the concept of admixture, and the physical properties of the matrix according to the polysilicon sludge replacement ratio based on light burned magnesia is determined.

• Current Optics and Photonics
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• v.1 no.1
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• pp.7-11
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• 2017

In this study, multilayered graphene was easily transferred to the target substrate in one step using thermal release tape. The transmittance of the transferred graphene according to the number of layers was measured using a spectrophotometer. The sheet resistance was measured using a four-point probe system. Graphene formed using this transfer method showed almost the same electrical and optical properties as that formed using the conventional poly (methyl methacrylate) transfer method. This method is suitable for the mass production of graphene because of the short process time and easy large-area transfer. In addition, multilayered graphene can be transferred on various substrates without wetting problem using the one-step dry transfer method. In this work, this easy transfer method was used for dielectric substrates such as glass, paper and polyethylene terephthalate, and a sheet resistance of ~240 ohm/sq was obtained with three-layer graphene. By fabricating organic solar cells, we verified the feasibility of using this method for optoelectronic devices.

• Journal of Climate Change Research
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• v.9 no.4
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• pp.399-406
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• 2018

The purpose of this study is to propose a methodology for estimating greenhouse gas emission reduction through HFCs used in the foam industry. This study investigated characteristics of HFCs and greenhouse gas emissions from production processes in the foam industry, which uses HFCs as a blowing agent. Also, we investigated fluorinated gas removal technology to determine a proper technology for the foam industry. And we confirmed the criteria and characteristics of External Project for methodology development. According to criteria of External Project and foam industrial process emission, a methodology for calculating the amount of greenhouse gas emission reduction in foam industry was developed. Lastly, we analyzed the amount of greenhouse gas emission reduction and KOC (Korea Of Offset) in the foam industry based on the domestic government's plan to reduce HCFCs and imported amount of HFCs used as a blowing agent. The results of this study demonstrate that linking greenhouse gas reduction in the foam industry and the domestic greenhouse gas reduction system can contribute to achieve the domestic greenhouse gas reduction goal.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.42 no.1
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• pp.21-32
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• 2019

The flow of the $4^{th}$ Industrial Revolution calls for the innovation of the traditional business models of the manufacturers. Servitization is a corporate strategy to respond to changes in the business environment. These days, the value that the market demands can be created on the basis of the product-service integration. Thus the manufacturers must pursue the fundamental innovation of the current strategy and business models. It is necessary to create common values with customers through providing product-service integrated offerings beyond the development, production, and delivery. The purpose of this study is to develop the evaluation indicators for selecting suppliers when the manufacturer who offers the value of product-service integration needs to obtain the resources from outside. The case company in this study is the manufacture firm conducting the retail IoT business as a new business. The Delphi method is used to develop the evaluation indicators for selecting suppliers. This study suggests the academic implications providing the perspective of Servitizaiton by using Delphi method, and the practical implications applying the creating value method of Servitization by collecting the opinions from both value providers and value consumers in the process of developing the evaluation indicators.

• Journal of the Institute of Convergence Signal Processing
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• v.19 no.4
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• pp.162-166
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• 2018

Companies that use automatic feeder systems use multiple feeders in close proximity to each other for mass production. Unlike when the feeder is used independently, it does not oscillate to a value that is set to offset or freeze due to symbiosis caused by asynchronous forces hitting each other. This may result in the shipment being damaged by hitting each other or thrown to one side, preventing the transport from being moved to the next process. Whenever an unstable resonance occurs, the operator must reset the value of each feed controller or operate it several times. To address these problems, this paper proposes synchronization algorithm suitable for feed controllers using multiple units and tests are used to confirm performance improvements.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.41 no.4
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• pp.213-219
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• 2018

Mechanical components are to be produced with accurate dimensions in order to function properly in assemblies of a machine. Once designs of mechanical components are created, designers examine the designs by adopting many known experimental methods. A primary test method includes stress and strain evaluation of structural parts. In addition, fatigue test and vibration analysis are an important test method for mechanical components. Real experiments at a laboratory are established when products are manufactured. Since design changes should be done before producing the designs in factories, rapid modifications for new designs are required in production industries. FEM simulation is a proper choice for a design evaluation with speed at a detail stage in design process. This research focuses modeling and mechanical simulation of a mechanical component in order to ensure structural safety. In this paper, a universal joint, being used in driving axels of vehicles, is studied as a target component. A design model is created and tested in some ways by using commercial software of FEM. The designed component is being twisted to transmit heavy power and thus, torsional stress should be under strengths of the component's material. The next is fatigue analysis to convince fatigue cycles to be within the endurance limit of the material. Another test is a vibration analysis for rotational components. This research draws final conclusions from these test analyses and recommends whether the designed model is under safety condition in terms of mechanical structure.

• Journal of Animal Science and Technology
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• v.61 no.3
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• pp.122-137
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• 2019

Methane, one of the important greenhouse gas, has a higher global warming potential than that of carbon dioxide. Agriculture, especially livestock, is considered as the biggest sector in producing anthropogenic methane. Among livestock, ruminants are the highest emitters of enteric methane. Methanogenesis, a continuous process in the rumen, carried out by archaea either with a hydrogenotrophic pathway that converts hydrogen and carbon dioxide to methane or with methylotrophic pathway, which the substrate for methanogenesis is methyl groups. For accurate estimation of methane from ruminants, three methods have been successfully used in various experiments under different environmental conditions such as respiration chamber, sulfur hexafluoride tracer technique, and the automated head-chamber or GreenFeed system. Methane production and emission from ruminants are increasing day by day with an increase of ruminants which help to meet up the nutrient demands of the increasing human population throughout the world. Several mitigation strategies have been taken separately for methane abatement from ruminant productions such as animal intervention, diet selection, dietary feed additives, probiotics, defaunation, supplementation of fats, oils, organic acids, plant secondary metabolites, etc. However, sustainable mitigation strategies are not established yet. A cumulative approach of accurate enteric methane measurement and existing mitigation strategies with more focusing on the biological reduction of methane emission by direct-fed microbials could be the sustainable methane mitigation approaches.

• Natural Product Sciences
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• v.25 no.3
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• pp.215-221
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• 2019

Inflammation is the crucial biological process of immune system which acts as body's defense and protective response against the injuries or infection. However, the systemic inflammation devotes the adverse effects such as multiple inflammation associated diseases. One of the best ways to treat this entity is by blocking the tumor necrosis factor alpha ($TNF-{\alpha}$) and TNF-related apoptosis-inducing ligand (TRAIL) to avoid the proinflammation cytokines production. Thus, this study aims to evaluate the potency of Sambucus bioactive compounds as anti-inflammation through in silico approach. In order to assess that, molecular docking was performed to evaluate the interaction properties between the $TNF-{\alpha}$ or TRAIL with the ligands. The 2D structure of ligands were retrieved online via PubChem and the 3D protein modeling was done by using SWISS Model. The prediction results of the study showed that caffeic acid (-6.4 kcal/mol) and homovanillic acid (-6.6 kcal/mol) have the greatest binding affinity against the $TNF-{\alpha}$ and TRAIL respectively. This evidence suggests that caffeic acid and homovanillic acid may potent as anti-inflammatory agent against the inflammation associated diseases. Finally, this study needs further examination and evaluation to validate the potency of Sambucus bioactive compounds.