This experiment was accomplished to investigate antioxidative activity of Korean mistletoe by organic solvents partitioning of methanol extact of 3 Korean mistletoes, fractionationing on column chromatography, and evaluation the reduction of a free radical ${\alpha}$,${\alpha}$-diphenyl-${\beta}$-picrylhydrazyl. Butanol partition of Loranthus yadoriki MeOH extract showed higher electron donating ability than ${\alpha}$-tocopherol. It was thought phenolic compounds including gallic acid account for antioxidative activity, on execution sub-fractionation, electron donating ability evaluation, and GC/MS analysis, but further studies on what are major actives must be investigated exactly.

Two wood decay ascomycetes fungi identified as Hypoxylon mammatum and H. truncatum were isolated from backyard of Korea Research Institute of Chemical Technology (KRICT) in Korea. Hypoxylon truncatum is newly recorded as a wood degrader in Korea. Unusual germination mechanisms of ascospores in H. mammatum and H. truncatum are described and illustrated. The differences between two species were noticed on the process of germ tube formation. In the process of germ tube formation, the fast movement to pigmented ascospores activated from their perispores was termed as spore eclosion that was only found in H. mammatum. This sophisticated recognition mechanism indicated the existence of specific eclosion and germ tube formation due to the composition of cell wall layers and their preferable host derive, based on examined two species under a genus. The observation on present study postulates different composition of wall layers of ascospore and different nutrient composition for germination.

The peroxidase activity was localized cytochemically to get an insight into its precise function in lignin biosynthesis. In this work, cerium chloride ($CeCl_3$) was used as a trapping agent for hydrogen peroxide ($H_2O_2$) generated from peroxidase. Seasonal variation of peroxidase activities in cambial region of Populus, Pinus, and Ginkgo was investigated at subcellular levels. Under transmission electron microscopy, electron dense deposits of cerium perhydroxide formed by reaction with $H_2O_2$ were observed in cambium and its immediate derivatives. The staining with $CeCl_3$ in cambium varied with growth seasons. The strongest $H_2O_2$ accumulation, regardless of tree species, appeared in May. Staining pattern of $CeCl_3$ in the cambium of poplar indicated that the production of peroxidase started in March before the opening of buds and reached the highest in May and then declined in August. Ginkgo and Pinus showed relatively late generation of $H_2O_2$ production when compared with Populus. Although Ginkgo and Pinus are classified into gymnosperms, however, the generation of peroxidase production and its duration was different from each other. Little staining appeared in all the tree samples collected in September before falling the leaves.

Two flavan 3,4-diol derivatives were isolated from the heartwood of Robinia pseudoacacia and characterized by spectroscopic methods including $^1H$ and $^{13}C$ NMR and positive FAB-MS. The structures were identified as 2,3-trans-3,4-cis-3,4,7,3',4',5'-hexahydroxy flavan, one of isomeric leucorobinetinidins, and 4'-methoxy-2,3-trans-3,4-cis-3,4,7,3',5'-pentahydroxy flavan.

Highly purified Cerrena unicolor laccase (benzenediol:oxygen oxidoreductase, EC 1.10.3.2) caused the demethoxylation of milled wood lignin and several lignin related substances. The constitutive form of the enzyme produced extracellularly by C. unicolor fermenter culture was isolated and purified by ion-exchange chromatography on the DEAE-Toyopearl column and by affinity chromatography on a ConA-Sepharose and Syringyl-AH-Sepharose 4B columns. The enzyme was further immobilized on functionalized porous glass (CPG) and keratin coated CPG. The demethylating activity was monitored both by estimation of released methanol and by detection of the level of methoxyl groups (also in some water miscible solvents) after incubation of lignin materials with laccase preparations (free and immobilized). The effects of the incubation time and temperature on the demethoxylating activity of immobilized laccase preparations were also studied.

Cement-bonded particleboard is being used as outdoor siding material all over the world, because this composite particularly bears a light weight, high resistance against fire, decay, and crack by cyclic freezing and thawing, anti-shock property, and strength enhancement. Construction systems are currently changing into a frame-building style and wooden houses are being constructed with prefabrication type. Therefore, they require a more durability at outdoor-exposed sides. In this study, the cement hydration property for Korean pine particle, Japanese larch particle and face- and middle layer particles (designated as PB particle below) used in Korean particleboard-manufacturing company was investigated, and the rapid manufacturing characteristics of cement-bonded particleboard by supercritical $CO_2$ curing was evaluated. Korean pine flour showed a good hydration property, however, larch flour showed a bad one. PB particle had a better hydration property than larch flour. The addition of $Na_2SiO_3$ indicated a negative effect on hydration, however, $MgCl_2$ had a positive one. Curing by supercritical $CO_2$ fluid gave a conspicuous enhancement in the performances of cement-bonded particleboards compared to conventional curing. $MgCl_2$ 3%-added PB particle had the highest properties, and $MgCl_2$ 1%-added Korean pine particle had the second class with the conditions of cement/wood ratio of 2.7, a small fraction-screened particle and supercritical curing. On the contrary, the composition of non-hammermilled or large fraction-screened particle at cement/wood ratio of 2.2 was poorer. Also, the feasibility for actual use of 3%-added, small PB particle-screened fraction was greatest of all the conventional curing treatments. Relative superiority of supercritical curing vs. conventional curing at dimensional stability was not so apparent as in strength properties. Through the thermogravimetric analysis, it was ascertained that the peak of a component $CaCO_3$ was highest, and the two weak peaks of calcium silicate hydrate and ettringite and $Ca(OH)_2$ were present in supercritical treatment. Accordingly, it was inferred that the increased formation of carbonates in board contributes to strength enhancement.

The woodceramics which are new porous carbon materials were obtained by carbonizing from thinned small log of Aomori HIBA (Thujopsis dolabrata S. et. Z. var. hondae M.) impregnated with phenol resin in a vacuum furnace. During the carbonization process, the resin changes into glassy carbon, which has superior property. The resin impregnation rate and bending strength depend on the types of board and density. In this paper, the manufacturing method of woodceramics made from thinned small logs of Aomori HIBA was introduced and some properties were examined.

A new porous carbon material "woodceramics" was developed by carbonizing wood or woody materials impregnated with thermosetting resin. Steamed board and non-steamed board were made from thinned small log of Aomori Hiba (Thujopsis dolabrata S. et. Z. var. hondae M.). They were impregnated with phenol resin and sintered in a vacuum furnace at $650^{\circ}C$. In this paper, the manufacturing method of woodceramics and changes of dimension, weight and compressive strength were investigated. The changes of dimension, weight and compressive strength depend on the types of board and density.

The effect of the treatment with CCFZ, FR-4, and PEG400 from butt end on the dimensional stability and bending properties was examined. Three softwood species such as red pine, Korean white pine and Japanese larch and three hardwood species such as poplar, alder and oak were investigated in this research. Shrinkage of red pine, Korean white pine, poplar, and alder treated with PEG400 decreased. However, there was no significant decrease of shrinkage in Japanese larch and oak. The decrease of shrinkage when moisture content changed from about 20% to 10% was larger than that at any other phase. In regard to the effect of treatment on bending properties, bending MOE and MOR of all specimens treated with PEG400 decreased significantly. Especially in the case of red pine, poplar, and alder treated with PEG400, bending MOR reduced 9%, 14%, and 12%, respectively. Reductions of MOR of the hardwood was also much larger than that of the softwood. However, in all species, treatment with CCFZ and FR-4 did not affect the change of bending MOE and MOR significantly. Comparing the large specimen which also included heartwood with the small specimen which included only treated sapwood, there was a difference in the change of bending MOE and MOR between them. The large specimens of Korean white pine, alder and Poplar, which had a relatively low proportion of sapwood(18~22%), showed the decrease of MOR by 11~13% more than that of small specimens, while red pine, Japanese larch and oak, which had a relatively high proportion of sapwood(35~40%), showed little decrease. It means that bending MOE and MOR of structural wood treated from butt end should be considered in terms of sapwood proportion as well as effect of treated chemicals.

Attempts were made to analyze the behavior of single and multiple-bolted connections through theoretical methods such as European yield theory, empirical approaching method, and semi-rigid theory instead of many experimental methods that have been actually inefficient and non-economical. In the case of a single-bolted connection, if accurate characteristic values of a material could be guaranteed, it would be more convenient and economical to perform the behavior analysis using a model based on the semi-rigid theory, instead of the existing complex yield model, or the empirical formula which produces errors, giving different results from the actual ones. If the variables of equation determining the load and deformation could be appropriately controlled, the analytical method in conjunction with a semi-rigid theory could be effectively applied to obtain the desirably predicted value, considering that the appropriate solution could be derived through a simpler equation using a less difficult method compared to the existing yield model. It is concluded that analytical method with semi-rigid theory can be used in the behavior analysis of bolted connection because our developed method showed excellent analysis ability of behavior until number of bolt is two. Although our analytical method has the disadvantage that the number of bolt is limited to two, it is concluded that it has the advantage than numerical method which complicated and time-consuming.

This study was carried out to improve the physico-mechanical properties of board products by applying the technique of high frequency heating, and find out the optimum conditions of high frequency heating, compared with the technique of hot platen heating. The possibility of isocyanate resin application to board production was also considered to solve the problem of free formaldehyde emission from urea resin which is generally used in wood industry. For this study, 30 mm thick MDP (medium density fiberboard) with isocyanate resin were manufactured by the techniques of hot platen heating, high frequency heating and the combination techniques of both heating methods, and compared in several point of views.