본 연구는 목질보드류 및 가구 생산 현장에서 주로 품질 관리를 위해 사용되는 데시케이터 방법을 개선 및 보완함으로써 측정 및 포집 시간을 단축하는 가속 포집 공정을 개발하기 위해 수행되었다. 먼저 등급별 목질 보드류에 대해 데시케이터 방법에 의한 포름알데히드를 측정하였다. 이어 개발된 공정을 가지고 데시케이터 방법과 비교하였을 때 최적 온도와 시간, 노출면적 등을 선정하여 시험한 후 그 상관성을 분석하였다. 그 결과 온도는 100 ℃, 시간은 1시간, 시편은 2개일 때 데시케이터 방법과 비교적 유사한 결과값을 나타내었으며 그 상관성도 높은 것으로 나타났다. 개발된 시험 공정을 검증하기 위해서 설정된 표준화된 온도 및 시간, 시편의 매수를 가지고 Korea Conformity Laboratories (KCL)에 의뢰되어 실제 시험에 쓰이지 않았던 시료를 가지고 비교하였다. 그 결과 데시케이터 방법과의 상관성은 매우 높은 것으로 나타났다. 그러나 가속 포집 공정에서의 포름알데히드 방출량 결과값은 데시케이터 방법보다 대부분 높게 나타났다. 몇 개 시료의 포름알데히드 방출 등급은 한단계 더 높게 나타나는 경우도 있었다. 하지만 품질관리의 관점에서는 본 연구에서 설계된 가속 포집 공정 방법에 의해 충분히 적용될 수 있다고 판단되었다.

This study aimed at developing an accelerated collection method that reduces measurement and collection time by improving and complementing the desiccator method, which is mainly used for quality control in wood-based panels and furniture production sites. First, this study measured the formaldehyde emissions from the wood-based panels by grade using the desiccator method. Further, this study compared the desiccator method with the developed process and analyzed the correlation in optimal temperature, time, and exposed area. The results showed that the developed process resulted in relatively similar outcomes in comparison to the desiccator method when the temperature was 100℃, the time was 1 h, and two specimens were used, at which the correlation was high. To verify the developed process, this study commissioned Korea Conformity Laboratories with the standardized temperature, time, and the number of specimens to compare them with the specimen that was not used in the actual test. As a result, the correlation to the desiccator method was shown to be very high. However, the formaldehyde emission measured by the accelerated collection process was mostly higher than that measured by the desiccator method. The formaldehyde emission grades from several specimens were one level higher. However, from the perspectives of quality control, it was determined that the accelerated collection method developed in this study could be sufficiently used.

This study aimed to increase the sugar and ethanol yield from the mengkuang plant biomass through biological and liquid hot water (LHW) pretreatment and their combination. The results showed that biological pretreatments with 5% inoculum of the fungus Trametes versicolor resulted in the highest alpha cellulose content incubated for 30 days, and 10% inoculum resulted in the lowest lignin content. LHW pretreatment decreased the hemicellulose content of pulps from 10.17% to 9.99%. T. versicolor altered the structure of the mengkuang pulp by degrading the lignin and lignocellulose matrix. The resulting delignification and cellulose degradation facilitate the hydrolysis of cellulose into sugars. The alpha cellulose content after biological-LHW pretreatment was higher (78.99%) compared to LHW-biological pretreatment (76.85%). Scanning electron microscopy analysis showed that biological-LHW combinated treatment degrades the cell wall structures. The ethanol yield for biological-LHW pretreated sample was observed 43.86% (13.11 g/L ethanol by weight of the substrate, which is much higher than that of LHW-biological pretreatment (34.02%; 9.097 g/L). The highest reducing sugar content about 45.10% was observed with a resulting ethanol content of 15.5 g/L at LHW pretreatment temperature of 180℃ for 30 min.

폐MDF로부터 해섬하여 얻은 재생섬유를 Reactive Red H-E3B (Bis-monochlorotriazine(MCT)/MCT type)와 Reactive Red RB 133%(bis-monochlorotriazine/Vinyl sulphone type)로 염색할 때 최적의 염색조건을 구명하기 위하여 염색조건(염료 농도, 염과 알칼리 첨가량, 염색온도)과 염색특성 및 일광견뢰도와의 관계를 검토하였다. 2종의 반응성염료 모두 염료농도가 1∼10(%,OWF)로 증가함에 따라 염착량(K/S)은 증가하였다. 또한, H-E3B가 RB 133%보다 염료 농도에 관계없이 K/S는 높았으며, 자외선 조사에 따른 색차는 낮아 자외선에 의한 변색 저항성이 양호하였다. 황산나트륨의 첨가량이 증가할수록 색차 및 K/S도 증가하였으며, 염의 첨가량은 50∼70 g/L가 적절하였다. 2 g/L의 탄산나트륨 첨가에 의해 색차 및 K/S가 크게 증가하였으나 그 이상의 첨가량 증가에서는 거의 차이가 없었다. 탄산나트륨의 첨가량은 pH 10을 유지하는 5∼10 g/L 가 적절할 것으로 생각된다. H-E3B 염료는 염색 온도가 높아짐에 따라 염착량이 증가하다가 80℃에서 다시 감소한 반면 RB 133%는 60∼70℃까지는 거의 동일한 염착량을 나타냈으나, 이후 감소하였다. 따라서 H-E3B는 80℃, RB 133%는 60℃가 적정한 것으로 판단된다. 이상의 최적조건에서 폐MDF 목질섬유를 염색처리하면 H-E3B염료는 1.5∼2.0R, RB 133%염료는 9.6∼10.0 PR의 색상을 가지는 염색 재생 목질섬유의 제조가 가능하였다.

This study aims to review the relations between the dyeing conditions (i.e., dye concentration, addition amounts of salt and alkali, and dyeing temperature) and dyeing properties and color fastness to light for identifying the optimal dyeing conditions when dyed regenerated woody fibers were obtained through the defibration of waste medium density fiberboard (MDF) using reactive Red H-E3B (Bis-monochlorotriazine (MCT)/MCT type) and reactive Red RB133% (Bis-MCT/Vinyl sulphone type). The dyeing yield (K/S) obtained using two types of reactive dyes increased as the dye concentration increased by 1-10% (on the weight of fiber (OWF)). In addition, the K/S of H-E3B was higher than that of RB133% irrespective of the dye concentration. The color difference of H-E3B after ultraviolet (UV) radiation was lower than that of RB133%, denoting good resistance to discoloration by UV. As the amount of sodium sulfate increased, the color difference and K/S also increased, and the adequate salt content was determined to be 50-70 g/L. Further, the color difference and K/S significantly increased only the addition of 2 g/L of sodium carbonate; however, almost no difference was observed when more than 2 g/L of sodium carbonate was added. The addition amount of sodium carbonate was adequate 5-10 g/L to dyeing the fiber and the pH at this addition level was 10. The dyeing yield of H-E3B increased when the dyeing temperature increased; however, it subsequently decreased after the dyeing temperature became 80℃. The dyeing yield of RB133% was almost the same up to 60-70℃ but declined subsequently. Thus, the adequate temperatures were 80℃ and 60℃ for H-E3B and RB133%, respectively. If the waste MDF woody fiber was dyed under the aforementioned optimal conditions, dyed regenerated woody fiber can be obtained having the following colors: 1.5 to 2.0R with the H-E3B dye and 9.6 to 10.0 PR with RB133%.

Licorice, which has an extensive history of use as an herbal medicine, has been suggested to have oral health benefits. However, to date, no systematic study has been conducted on the preparation method of licorice extracts for oral health. In this study, licorice extracts prepared using water and ethanol were investigated for its ability to inhibit the biofilm formation of Streptococcus mutans. The licorice extract prepared with around 60% ethanol effectively inhibited the biofilm formation of S. mutans. Licorice extracted with 50% ethanol almost completely inhibited the biofilm formation at 1.5 g/L of licorice extract. This inhibitory activity was confirmed in a microplate assay and a flow cell system. Glycyrrhetic acid was extracted from licorice effectively with 60% ethanol concentration. The strong inhibitory activity of glycyrrhetic acid and the synergistic inhibition with glycyrrhizin on biofilm formation were suggested as major reasons for a concentration-specific extraction. These results suggest that licorice extract prepared using around 60% ethanol effectively inhibits the biofilm formation of S. mutans.

This study addresses the biorefinery feedstock from Pinus densiflora. This raw material is a major tree species in the Republic of Korea; it is renewable, has cost-effective, and is readily available. In this study, steam explosion of P. densiflora was performed in a reactor at 225 ℃ and with 1 to 13 min reaction times with or without previous water impregnation. The combined severity factor (Ro), which is an expression relating the reaction temperature and reaction time used in the steam explosion treatment, ranged from 3.68 to 4.79. The influence of both impregnation and steam explosion conditions were investigated by examining color variations, chemical composition, and mass balance on the pretreated solids. The results showed that steam-exploded P. densiflora that was not impregnated with water exhibited significantly darker color (chroma 28.8-41.4) than water-impregnated and steam-exploded P. densiflora (chroma 18.8-37.3). The increased α-cellulose and lignin contents were detected as the severity factor increased. Furthermore, the α-cellulose and lignin contents in the non-impregnated/steam-exploded P. densiflora were higher than those in the water-impregnated/steam-exploded P. densiflora. However, the decreased holocellulose content was detected as the severity factor increased. In mass balance, the holocellulose yield from water-impregnated/steam-exploded P. densiflora was higher than that from the non-impregnated P. densiflora.

To improve the water resistance of melamine-urea-formaldehyde (MUF) resins, different levels of blocked polymeric 4,4 diphenyl methane diisocyanate (B-pMDI) were blended with MUF resins to prepare B-pMDI/MUF hybrid adhesives, and their adhesion performances were evaluated for the surface lamination of fancy veneer on plywood. FT-IR spectra showed that the de-blocked -NCO groups reacted with the -OH of hydroxymethyl groups of the MUF resins to form urethane bonds at 2% B-pMDI/MUF, which was detected before and after their hydrolysis. The mass loss after the hydrolysis consistently decreased as the B-pMDI level increased, indicating an improvement in the water resistance. As the B-pMDI level increased, the activation energy of hybrid adhesives decreased, which improved the reactivity of the hybrid adhesives. Additionally, the water resistance improvement of the hybrid adhesives increased the tensile shear strength of the surface laminated plywood in semi-water proof and water-proof by 23 % and 8 %, respectively, at 2% B-pMDI level. This was likely due to the urethane linkages in the hybrid adhesives. However, the formaldehyde emission from plywood panels bonded with the hybrid adhesives increased in the dry state, indicating incomplete curing of the hybrid adhesives.

This work aimed to evaluate the influence of culture conditions on laccase production in the co-culture of wood-rotting fungus with Trichoderma sp. The effects of infection extent, infection time, and culture filtrate of Trichoderma sp. on the laccase production by wood-rotting fungus in co-culture were examined. T. rubrum LKY-7 and T. longibrachiatum were selected as fungi which are effective in co-culture for laccase production. A significant increase in laccase activity was observed when T. rubrum LKY-7 was co-cultured with T. longibrachiatum in glucose-peptone liquid medium, yielding an increase of more than 5 times in laccase activity, as compared with control. Laccase production by T. rubrum LKY-7 during co-culturing was significantly influenced by the infection extent and the infection time of T. longibrachiatum. Maximal laccase activity was obtained when T. rubrum LKY-7 culture was infected by T. longibrachiatum after 3 days of cultivation at an inoculum size ratio of 0.5 to 1. The addition of culture filtrate or autoclaved mycelium of T. longibrachiatum to T. rubrum LKY-7 culture did not significantly enhance laccase production by T. rubrum LKY-7 as compared with control (mono cultures of T. rubrum LKY-7).

This study reports the performance of urea-formaldehyde (UF) resins prepared at two different low formaldehyde/urea (F/U) mole ratios with different numbers of urea addition during synthesis. The second or third urea was added during the synthesis of UF resins to obtain two different low molar ratios of 0.7 and 1.0, respectively. The molecular weights, cure kinetics, and adhesion performance of these resins were characterized by the gel permeation chromatography, differential scanning calorimetry, and tensile shear strength of plywood, respectively. When the number of urea additions and F/U molar ratio increased, the gelation time decreased, whereas the viscosity and molecular weight increased. Further, the UF resins prepared with the second urea and 1.0 molar ratio resulted in greater activation energy than those with third urea and 0.7 molar ratio. Tensile shear strength and formaldehyde emission (FE) of the plywood that bonded with these resins increased when the number of urea additions and molar ratio increased. These results suggest that the UF resins prepared with 0.7 molar ratio and third urea addition provide lower adhesion performance and FE than those resins with 1.0 mole ratio and the second urea addition.