• 한국의류학회지
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• 제47권1호
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• pp.110-122
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• 2023

The COVID-19 pandemic increased people's time at home and caused an 80% increase in noise disputes between floors. The purpose of this study is to propose suitable materials for making indoor shoes (insoles) to minimize noise between floors. Subjects without back pain and leg-related disease (e.g. arthritis, etc.) from three different age groups (childhood, adolescence, and adulthood) were recruited for the study. Five polymer insole materials were considered: Chloroprene Rubber (CR foam), Ethylene Propylene Diene Monomer (EPDM foam), Natural Latex foam, Ethylene Vinyl Acetate (EVA foam), and Polyurethane (PU foam). From these materials, 20 combinations were prepared and randomly tested for noise and vibration. The results revealed a significant difference in noise and vibration levels based on the type of material used and the age of the subject. Nevertheless, all materials under consideration successfully reduced noise and vibration; in particular, type A-C greatly decreased. The CR foam material was especially effective at noise and vibration reduction (p<.01). This study suggests that adding insoles into socks that children wear at home could reduce noise vibration and disputes between floors.

• Smart Structures and Systems
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• 제6권2호
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• pp.101-113
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• 2010

This paper presents the results of a series of experiments conducted to model a magnetorheological damper operated in shear mode. The prototype MR damper consists of two parallel steel plates; a paddle covered with an MR fluid coated foam is placed between the plates. The force is generated when the paddle is in motion and the MR fluid is reached by the magnetic field of the coil in one end of the device. Two approaches were considered in this experiment: a parametric approach based on the Bingham, Bouc-Wen and Hyperbolic Tangent models and a non parametric approach based on a Neural Network model. The accuracy to reproduce the MR damper behavior is compared as well as some aspects related to performance are discussed.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 2017년도 춘계공동학술대회
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• pp.170-170
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• 2017

기후변화 따른 스마트팜 돈사 외부 환경의 변화에 대응하고, 사육 환경을 능동적으로 개선하기 위한 연구가 수행 중이다. 돈사 내 열전달 요소 간 상호 역학성 분석을 위해서 고려해야할 사항은 입기구, 보온 등, 열풍기, 단열제, 위치, 방향, 돈사의 연평균 온도, 습도, 연중 일사량, 가축의 열복사 등 상호 복잡하게 연관되어 있는 물리량이다. 돈사 전체 열손실, 자연발생 에너지량, 강제발생 에너지량, 난방용량 등을 고려한 순간 열부하 산정을 위한 여러 방법 중 우선적으로 CFD(Computational Fluid Dynamics)를 이용하였다. 순간 열부하 산정을 위한 해석 도구 선정에 있어서 다양한 유체 및 기체 전산 유체역학 Solver(Fluent, Open-FOAM, Blender)를 고려하였다. 공간 Mech를 수행하기 위한 도구로는 공개 소프트웨어 인 FreeFem++ 3.51-4 (http://www.freefem.org)를 이용하였다. 이 과정에서 일부 기체 (암모니아)의 농도를 난수로 변화시키는 기법을 적용하여 가상적으로 돈사의 환경을 Pseudo 시뮬레이션 하였다. 결과적으로 Fluent에 비하여 OpenFOAM을 이용하여 얻은 열유동의 방향(속도)과 크기 백터가 상대적으로 크게 나타났다. Fluent가 시계열 상에서 혼합 기체 물리량 변화를 무시할 수 있는 안정되고 균일한 환경에 적합하기 때문인 것으로 판단되었다. Blender의 경우 Lattice Boltzmann methods 과 Smoothed-particle hydrodynamics 방법을 이용한 유체/입자 동력학 모델링을 제공함에 있어 시각적 효과를 강조하는 기능에 중점을 두었다. Fluent와 Blender에서 제공하는 해석 연산 모듈의 정확성 검증을 위해선 공간 분해능을 높인 정밀 계측 시스템을 이용하여 검증할 필요가 있다. Open-FOAM를 이용한 열부하 분석 수행이 상대적으로 높은 절대값을 보이는 특성은 열부하 제어 시스템의 Overshoot를 유발할 가능성이 있으므로 이에 대한 해석 모델의 보정이 추가적으로 필요할 것이다. CFD의 한계인 시간 복잡도를 낮추고 상대적으로 높은 시계열 분해능을 확보할 경우 돈사 내 환기시스템에 맞는 소요 환기량 실시간 산정이 가능해지고 외부기상 및 돈사내부 복사열을 활용함과 동시에 돈군 순환에 상응하는 실시간 열부하 관리 시스템 도출이 가능할 것이다.

• Smart Structures and Systems
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• 제13권4호
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• pp.615-636
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• 2014

Aluminium Foam Sandwich (AFS) panels are becoming always more attractive in transportation applications thanks to the excellent combination of mechanical properties, high strength and stiffness, with functional ones, thermo-acoustic isolation and vibration damping. These properties strongly depend on the density of the foam, the morphology of the pores, the type (open or closed cells) and the size of the gas bubbles enclosed in the solid material. In this paper, the vibrational performances of two classes of sandwich panels with an Alulight(R) foam core are studied. Experimental tests, in terms of frequency response function and modal analysis, are performed in order to investigate the effect of different percentage of porosity in the foam, as well as the effect of the random distribution of the gas bubbles. Experimental results are used as a reference for developing numerical models using finite element approach. Firstly, a sensitivity analysis is performed in order to obtain a limit-but-bounded dynamic response, modelling the foam core as a homogeneous one. The experimental-numerical correlation is evaluated in terms of natural frequencies and mode shapes. Afterwards, an update of the previous numerical model is presented, in which the core is not longer modelled as homogeneous. Mass and stiffness are randomly distributed in the core volume, exploring the space of the eigenvectors.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 추계 학술발표회
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• pp.473-485
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• 2010

Lightweight materials using in-situ clay soil contain large amounts of fine grain and cement for increasing the strength, lighter weight to increase liquidity for the foam and the bulk of the material is conducted by the water. Domestic cases, Light weight soil to improve cementation and lightness using demountable mixing device is defined Smartsoil. Typical features are their self-leveling, self-compaction, folwability. By adjusting the amount of cement, the strength can be controlled artificially. And re-excavation is easy. In this paper, pre-loading method using the road due to the displacement of adjacent structures under construction as an alternative SmartSoil introduces the design and construction practices. Is to discuss and improve.

• 한국분말재료학회지
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• 제26권3호
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• pp.231-236
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• 2019

Ni hydroxides ($Ni(OH)_2$) are synthesized on Ni foam by varying the hexamethylenetetramine (HMT) concentration using an electrodeposition process for pseudocapacitor (PC) applications. In addition, the effects of HMT concentration on the $Ni(OH)_2$ structure and the electrochemical properties of the PCs are investigated. HMT is the source of amine-based $OH^-$ in the solution; thus, the growth rate and morphological structure of $Ni(OH)_2$ are influenced by HMT concentration. When $Ni(OH)_2$ is electrodeposited at a constant voltage mode of -0.85 V vs. Ag/AgCl, the cathodic current and the number of nucleations are significantly reduced with increasing concentration of HMT from 0 to 10 mM. Therefore, $Ni(OH)_2$ is sparsely formed on the Ni foam with increasing HMT concentration, showing a layered double-hydroxide structure. However, loosely packed $Ni(OH)_2$ grains that are spread on Ni foam maintain a much greater surface area for reaction and result in the effective utilization of the electrode material due to the steric hindrance effect. It is suggested that the $Ni(OH)_2$ electrodes with HMT concentration of 7.5 mM have the maximum specific capacitance (1023 F/g), which is attributed to the facile electrolyte penetration and fast proton exchange via optimized surface areas.

• 한국수소및신에너지학회논문집
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• 제35권2호
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• pp.152-161
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• 2024

In this study, a fuel cell system for future defense unmanned vehicles was designed and validated. A Co/Al₂O₃-Ni foam catalyst for NaBH₄ hydrolysis was characterized using several analytical methods. A NaBH₄ hydrogen generation system with the Co/Al₂O₃-Ni foam catalyst continuously generated hydrogen at elevated reaction temperatures. The fuel cell system with the NaBH₄ hydrogen generation system was designed and tested. The performance of the fuel cell system was comparable to that of the fuel cell system using pure hydrogen. Therefore, the fuel cell system with the NaBH₄ hydrogen generation system is a suitable power source for future defense unmanned vehicles owing to its easy refueling and simple system.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2023년도 가을학술발표대회논문집
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• pp.51-52
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• 2023

Recently, heat island and dry island phenomena occur frequently due to land surface development and excessive energy consumption in urban areas. As a result, the surface temperature of the building and the entire temperature of its surroundings are increased, and as a result, the durability of the building is rapidly deteriorated. In order to suppress these causes, a method of maintaining the temperature of road heating wires was implemented as a temporary measure, but this did not predict climate change. Therefore, this study is a method to measure the compressive strength, density, and thermal conductivity of light weight concrete using waste glass foam beads. After fabricating a simple chamber, the temperature and humidity of the inside and outside were measured with an Arduino device in consideration of external factors. Therefore, if waste glass foam beads made through proper mixing are constructed in the urban center, the quality of the urban can be improved.

• 한국산학기술학회논문지
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• 제22권6호
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• pp.36-42
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• 2021

최근 4차 산업혁명으로 인해 제조업계에서는 제조업의 인공지능을 접목시켜 효율성을 극대화하는 스마트 팩토리 붐이 일어나고 있다. 특히 자동차 부품 제조 및 생산에 널리 적용되어 불량을 낮추는 연구들이 활발히 진행되고 있다. 이에 본 연구에서는 머신러닝을 통한 불량예측을 시트 폼 발포공정에 접목시켜 발포공정의 효율성을 극대화하는 연구를 진행하였다. 자동차 시트폼 에서 주로 사용되는 폴리우레탄 폼(polyurethane foam)은 폴리올(polyol, 이하 POL)과 이소시아네이트(isocyanate, 이하 ISO)를 혼합 및 발포하는 공정으로 제조되며, 각 원료의 혼합비율과 온도의 변화에 따라 제품의 특성이 변화한다. 이에 본 연구에서는 발포공정에서 수집되는 인자별 데이터값을 머신러닝에 적용하여 불량을 예측하고자 한다. 머신러닝에 사용되는 알고리즘으로는 의사결정트리, kNN, 앙상블 알고리즘을 사용하였으며 학습은 5,147개의 데이터를 사용하였으며, 학습된 결과를 1,000개의 검증용 데이터에 적용한 결과, 세 알고리즘 중 앙상블 알고리즘에서 최대 98.5 %의 정확도를 확인할 수 있었다. 이러한 결과를 통해 발포공정에서 실시간으로 수집되는 데이터를 통해 현재 생산되는 부품의 불량 여부를 확인할 수 있으며, 나아가 각 인자를 조절하여 불량률을 개선할 수 있음을 짐작할 수 있다고 사료된다.

• Journal of Microbiology and Biotechnology
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• 제27권4호
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• pp.747-758
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• 2017

Chronic wounds, pressure sores, lesions, and infections of microbial origin in bedridden, paralyzed, or malnutrition patients remain the object of study of many researchers. A variety of factors behind the development of these disorders are related to the patient's immune system, making it unable to respond effectively to the treatment of the wound. These factors can be properly controlled, giving particular importance to the ethiology and stage of the wound, as well as the time periods corresponding to the replacement of the dressings. The present research reports a novel foam/soft material, ${{\small}L}$-Cys-g-PCL, with an application for decubitus/pressure ulcers, especially for wounds with a difficult healing process due to infections and constant oxidation of the soft tissues. During this work, the interactions between S. aureus and ${{\small}L}$-Cys-g-PCL foam were studied under conditions that simulate decubitus ulcers; namely, pH and exudate. The effects of duration of grafting (1 or 8 h) and pH (7.0 and 8.9) on wettability, surface energy, swelling, and porosity were also evaluated. Results showed an effective microbicidal activity exhibiting an inhibition ratio of 99.73% against S. aureus. This new ${{\small}L}$-Cys-g-PCL soft material showed saftey to contact skin, ability to be shaped to fill in sunken holes (craters) - pressure ulcers stage III - and to act as a smart material responsive to pH, which can be tailored to develop better swelling properties at alkaline pH where exudates are normally higher, so as to address exudate self-cleaning and prevention of desiccation.