Junhyun Kim

Estimating the fire behavior of wood flooring using a cone calorimeter

This article analyzes the flammability characteristics in order to investigate the adequacy of a newly proposed sampling method for wood and PVC materials that are commonly used for residential flooring. Experiments on commercial products were performed using a cone calorimeter according to ISO 5660-1 specifications. Samples for the test procedure were prepared in two methods: either using a cone calorimeter sample preparation method (case 1), or the proposed sample preparation method, which a simplified form for the actual constructed shape (case 2). The thermal characteristics of the common wood products differed depending on the sampling method, where the peak heat release rate (PHRR) had either two peaks for case 1 or a single peak for case 2, and the total heat rate (THR) and smoke production rate (SPR) also differed according to the case. Especially, the wood flooring differed significantly between the two cases in terms of the number of PHRR peaks and the trend of the SPR curves. Due to these differences, we presented another HRR evaluation method depending on the raw material and the size of HRR to reduce the fire hazards in flooring.

Characteristics of Particleboards Using Tannin Resin as Novel Environment-Friendly Adhesion System:

The objective of this study was to develop an environment-friendly adhesion system for particleboard using tannin-based resin. Tannin-based resin was used in the surface layer of particleboard to replace urea-formaldehyde resins. In addition, the additive with various content ratios in particleboard was evaluated to confirm the effect of formaldehyde reduction performance by the perforator and desiccator methods. As the amount of additive was increased, formaldehyde reduction performance would significantly be increased. Manufactured boards containing additive above 3 wt% in the surface layer satisfied grade SE0 in the results of the desiccator method. The mechanical properties of manufactured boards satisfied the minimum requisite quality standard. This study discussed the effects and possibilities of tannin-based resin to reduce formaldehyde emission in indoor environments.

Formaldehyde emissions from particle board made with phenol–urea–formaldehyde resin prepared by different synthesis methods

This paper suggests the optimum NAF resin preparation to reduce the quantity of pollutant emissions from the particle boards by using PUF resin. The pollutant emissions performance of the prepared NAF resin was evaluated by comparison with eMDI resin. Each PF and PUF resin was made by variation of the molar ratio and synthesis methods according to order of addition of the basic products. In addition, after verifying the properties of the resins, the quantity of pollutant emitted from boards made with the PUF resins were evaluated. Of the cases of boards made with each resin, the formaldehyde emission was the lowest for PB #7. The eMDI resin used in this board showed good quality as an eco-friendly resin, because it had less than half the formaldehyde emission of the other formaldehyde-based resins. In addition, the mechanical properties of the particle board met the KS criteria; therefore, there should be no restriction on use in manufactured goods.

Thermal Extractor Analysis of VOCs Emitted from Building Materials and Evaluation of the Reduction Performance of Exfoliated Graphite Nanoplatelets

This study evaluated the amount of volatile organic compounds (VOCs) emitted from building materials, such as wallpaper, paint, adhesive and wood-flooring material, using a thermal extractor (TE). To evaluate the performance of TE on VOCs emissions of building materials according to temperature variation, all specimens were measured at two temperatures: 25°C and 35°C. Through emission results, the acceleration effect on the diffusion of VOCs in the material at the elevated temperature and the feasibility of TE on VOCs emission test according to temperature variation were confirmed. In addition, exfoliated graphite nanoplatelets (xGnP) made by using shape modification process to improve porosity of graphite, which can remove VOCs by sorption was applied to materials. The adsorption amounts of VOCs by exfoliated xGnP were evaluated at 35°C with each specimen. The xGnP as a porous material had an effect on the material emissions; the emission amounts were reduced. The emission tests were conducted with the same exposed surface area for each specimen. As the temperature increased, VOCs emission rates increased from approximately 2 to 5 times. And the adsorption performance of xGnP showed that the reduction percentage of VOCs was 9% to 81%.

Consideration of Ozone Removal and Control in Built Environment by Building Materials

Recently, residents have been spending almost 90% of their time indoors, which presents a higher risk from inhalation of pollutants than when spending time outdoors. Therefore, controlling indoor air quality became important. It is reported that the lung diseases and mortality for occupants are increased when there is high density of ozone which is one of the pollutants among the indoor air. In addition, the reactions between ozone and building materials produce VOCs and formaldehyde. The studies to eliminate the ozone by building materials have been actively investigated. However, ozone removal and secondary pollutants from ozone reactions with building materials have not been reported in Korea. For this reason, the aim of this study is to introduce ozone removal by HVAC filters, various building materials, and eco-friendly building materials including the quantity of secondary pollutant emissions.

Confirmation of the performance of exfoliated graphite nanoplatelets for pollutant reduction rate on wood panel

Exfoliated graphite nanoplatelets have been used as an additive for the improvement of a variety of properties. Nowadays, it is used as an adsorbent for pollutants, especially volatile organic compounds and formaldehyde. Additionally, exfoliated graphite nanoplatelets have been used as an additive in wood composites, because wood composites have a higher thermal conductivity than timber or typical wood-based panels. Therefore, exfoliated graphite nanoplatelets have been applied to high-density fiberboard which is a core material of wood flooring for the emission rate reduction of volatile organic compounds and formaldehyde and for increasing the thermal conductivity of wood flooring in radiant floor heating systems. Volatile organic compound emissions have been reduced significantly in wood composite boards according to the addition of exfoliated graphite nanoplatelets. The properties of formaldehyde emission and thermal conductivity decreased when 2% exfoliated graphite nanoplatelets are added to high-density fiberboard. However, these properties increased with the increase in the addition of exfoliated graphite nanoplatelets from 2% to 4%.

Magnetic and Thermal Properties of MoN Underlayer for Spin Valves Depending on Nitrogen Concentration

We incorporated nitrogen in the Mo underlayer and investigated the effect of nitrogen concentration on the magnetic properties and annealing behavior of the spin valve devices. The spin valve structure was Si/SiO2/Mo(MoN)(35Aring)/NiFe(21 Aring)/CoFe(28 Aring)/Cu(22 Aring)/CoFe(18 Aring)/IrMn(65 Aring)/Ta(25Aring). It is concluded that MoN underlayer is magnetically as good as Ta underlayer for N2 gas flow rate of less than 6 sccm