• Fire Science and Engineering
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• v.29 no.4
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• pp.67-72
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• 2015

A series of fire tests was conducted to examine the fire characteristics of flaming and smoldering combustion of engineered wood products, which have been widely used for furniture and finishing materials in buildings. The engineered wood products of MDF, plywood, and chipboard were ignited by a radiant cone heater with incident heat flux of $50kW/m^2$. During the fire test, key parameters representing the fire characteristics such as the heat release rate, yield rate of combustion product, and effective heat of combustion were quantified in terms of thickness. The tests show two peak points of HRRPUA due to lateral fire propagation in the initial stage, followed by later fire penetration through the specimen thickness. The mass loss rate of flaming combustion was 5 times higher than that of smoldering combustion, while the CO yield rate of smoldering combustion was 10 times higher than that of flaming combustion. This study can contribute to the understanding of fire behavior of wood combustibles and provide useful data for fire analysis.

• Journal of the Korean Wood Science and Technology
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• v.25 no.2
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• pp.88-99
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• 1997

뉴질랜드산(産) 라디아타소나무의 수간(樹幹) 및 지재(枝材)에 발달(發達)되어 있는 압축이상재(壓縮異常材), 대응재(對應材) 및 측면재(側面材)의 해부학적(解剖學的) 특성(特性)을 광학현미경(光學顯微鏡), 주사전자현미경(走射電子顯微鏡) 그리고 투과전자현미경(透過電子顯微鏡)을 이용하여 조직학적(組織學的) 및 구성요소(構成要素)의 수량적(數量的) 측면(側面)에서 비교(比較), 검토(檢討) 하였다. 조직학적(組織學的)인 면(面)에서 볼 때 춘재(春材)로부터 추재(秋材)로의 가도관(假導管) 이행(移行)은 대응재(對應材)나 측면재(側面材)보다 압축이상재(壓縮異常材)가 훨씬 더 점진적(漸進的)이었다. 편심생장(偏心生長)으로 인해 연륜폭(年輪幅)은 압축이상재(壓縮異常材)가 가장 컸고 그 다음이 측면재(側面材) 및 대응재(對應材)의 순이었으며 추재솔(秋材率) 역시 압축이상재(壓縮異常材)가 대응재(對應材) 및 측면재(側面材)보다 컸다. 횡단면상(橫斷面上) 가도관(假導管) 형상면(形狀面)에서 압축이상재(壓縮異常材)가 원형(圓形)을 나타내는 반면 대응재(對應材)와 측면재(側面材)는 각형(角形)을 띠고 있었다. 또한 압축이상재(壓縮異常材)에서만 가도관(假導管)의 세포벽(細胞壁)에 나선강(螺旋腔)과 나선열(螺旋裂) (helical cavity and check), 슬릿(slit)형(形) 벽공구(壁孔口)가 존재(存在)하였으나 $S_3$층(層)이 결여(缺如)되어 있었으며 굴곡(屈曲)된 선단(先端)과 불규칙(不規則)한 형상(形狀)의 가도관(假導管) 및 세포간극(細胞間隙)이 자주 관찰(觀察)되었다. 직교분야(直交分野) 벽공(壁孔)은 압축이상재(壓縮異常材)가 가문비나무형(型) 그리고 대응재(對應材) 및 측면재(側面材)는 소나무형(型) 벽공(壁孔)을 나타냈다. 수량적(數量的) 특성(特性) 면에서 볼 때 가도관(假導管)의 길이는 압축이상재(壓縮異常材)가 가장 짧고 측면재(側面材)가 가장 길었으며 가도관(假導管)의 벽(壁) 두께는 압축이상재(壓縮異常材)가 대응재(對應材)나 측면재(側面材)보다 두꺼웠다. 수직수지구(垂直樹脂溝)는 대응재(對應材)가 그리고 수평수지구(水平樹脂溝)(방추형(紡錐形) 방사조직(放射祖織))는 압축이상재(壓縮異常材)의 쪽이 많았다. 결론적(結論的)으로 보면 라디아타소나무의 압축이상재(壓縮異常材)는 근본적으로 대응재(對應材)나 측면재(側面材)와는 상이(相異)한 특성(特性)을 지녔으나 대응재(對應材)와 측면재(側面材)는 거의 유사(類似)한 특성(特性)을 공유(共有)하는 것으로 밝혀졌다.

• The Korean Journal of Mycology
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• v.45 no.4
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• pp.319-327
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• 2017

In this study, we investigated the culture conditions of four ectomycorrhizal fungi, namely, Amanita spissacea NIFoS 2719, Pisolithus arhizus NIFoS 2784, Suillus spraguei NIFoS 2848, and Xanthoconium affine NIFoS 2716, in solid and liquid culture media. In addition, we attempted to induce in vitro mycorrhization of the fungi with Pinus densiflora. Prior to liquid culture, we determined the optimal culture conditions for each species in solid media. The results revealed that all species examined are capable of growth in potato dextrose agar (PDA), malt extract agar (MEA), and modified Melin-Norkran's medium (MMN), although their preferred growth media were different. Liquid culture experiments showed that inorganic nitrogen did not enhance the mycelial growth of all four species. Therefore, we used MMN-based liquid inocula to promote the growth of ectomycorrhizal fungi in our symbiosis culture system. Mycorrhization was observed in Xanthoconium affine NIFoS 2716. Morphological analysis revealed that fungi-inoculated roots of P. densiflora form simple and dichotomous lateral roots with dense mycelia. In addition, inoculation with X. affine NIFoS 2716 promoted root and shoot developments.

• Journal of the Korea Furniture Society
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• v.19 no.2
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• pp.137-140
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• 2008

This experiment states the ultra pure distilled water penetration depth through ray parenchyma cell in radial direction of Castanea crenata. Heartwood penetration depth was 1.16 times lower than the depth in softwood and that difference was found statistically significant at 75.2 second of penetration. Following go-stop-go cycle, water penetrated in the ray parenchyma cell. At the beginning this speed was high and then it was decreased slowly. Water penetration depth result was compared with alcohol penetration depth. It was found that water penetration in ray parenchyma was found lower than alcohol due to the low surface tension of water.

• Journal of the Korean Wood Science and Technology
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• v.43 no.4
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• pp.504-510
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• 2015

This research was performed to evaluate soil contamination caused by copper depleted from ACQ-treated wood. Three years after the exposure of ACQ-treated wood in the field test sites, soil samples around the treated wood were collected and analyzed for the copper amount and distribution through soil. Soils around the deck posts installed in five different neighborhood parks located in Chonnam and Gyeongnam were investigated for copper contents. The results of the field test showed that the amount of copper leached from the end surface of treated wood buried under soil was more than 1.5 times the copper amount leached from the lateral surfaces, and the mobility of copper was very restricted in soil. The copper contents of soil within 10 cm from the treated deck posts installed in the parks showed to be less than 500 mg/kg, which are the limit values of the 2nd region set up by enforcement regulation of soil environment conservation act. The distribution ranges of copper in soil from the treated wood set up in the field test sites seemed to be much wider than those from deck posts, which may explained by the fact that the retentions of the treated samples used in the field test sites were much higher than those of the deck posts.

• Journal of the Korean Wood Science and Technology
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• v.45 no.5
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• pp.535-543
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• 2017

For column-beam gussets of wooden structures, slit-processed members inserted with a steel plate are used in general. In this study, a rigid portal frame bonded with a joint was fabricated and a semi-rigid portal frame was fabricated by making a wooden gusset, a replacement for steel plate, of which a half was integrated into the column member and the other half was joined with the beam member by drift-pins. The lateral strength performance of the wooden portal frame was compared with that of the steel plate-inserted joint portal frame. The lateral strength performance was evaluated through a perfect elasto-plasticity model analysis, sectional stiffness change rate, and short-term permissible shear strength. As a result of the experiment, the maximum strength of the rigid portal frame was lower than that of the steel plate-inserted joint portal frame. The yield strength and ultimate strength were calculated as 0.58 and 0.48, respectively, but the measurements of initial stiffness and cumulative ductility improved by 1.35 and 1.1, respectively. As a result of the perfect elasto-plasticity model analysis of the semi-rigid portal frame, the maximum strength was lower than that of the rigid portal frame, but the toughness after failure was excellent. Thus, the ultimate strength was higher by 1.05~1.07. The steel plate-inserted portal frame showed rapid decrease in stiffness with the progress of repeated tests, but the stiffness of the portal frames with a wooden joint decreased slowly.

• Structural Engineering and Mechanics
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• v.21 no.1
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• pp.1-18
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• 2005

Foschi's connector model is used as a basic component in the development of nonlinear analysis programs for timber structures. This paper presents the extension of the model to include the effect of shaft frictional forces. The wood medium is modeled using the Foschi embedment model, while shaft friction is modeled using an elastic Coulomb-type friction model. The initial confining pressure for the case of driven fasteners is accounted for by a lateral shift of the load-embedment curve. The model is used to compute the cyclic response of both driven and inserted fasteners. The results obtained from the cases studied indicate that initial confining pressure and friction do not have a significant effect on the computed hysteretic response, however, they significantly affect the computed amount of fastener withdrawal. This model is particularly well-suited for modeling the hysteretic response of shear walls with moderate fastener withdrawal under lateral cyclic or earthquake loading.

• Structural Engineering and Mechanics
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• v.43 no.2
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• pp.147-161
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• 2012

This paper presents a curvature method for analysis of beam-columns with different materials and arbitrary cross-section shapes and subjected to combined biaxial moments and axial load. Both material and geometric nonlinearities (the p-delta effect in this case) were incorporated. The proposed method considers biaxial curvatures and uniform normal strains of discrete cross-sections of beam-columns as basic unknowns, and seeks for a solution of the column deflection curve that satisfies force equilibrium conditions. A piecewise representation of the beam-column deflection curve is constructed based on the curvatures and angles of rotation of the segmented cross-sections. The resulting bending moments were evaluated based on the deformed column shape and the axial load. The moment curvature relationship and the beam-column deflection calculation are presented in matrix form and the Newton-Raphson method is employed to ensure fast and stable convergence. Comparison with results of analytic solutions and eccentric compression tests of wood beam-columns implies that this method is reliable and effective for beam-columns subjected to eccentric compression load, lateral bracings and complex boundary conditions.

• The Korean Journal of Pain
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• v.32 no.3
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• pp.147-159
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• 2019

Lumbar foraminal pathology causing entrapment of neurovascular contents and radicular symptoms are commonly associated with foraminal stenosis. Foraminal neuropathy can also be derived from inflammation of the neighboring lateral recess or extraforaminal spaces. Conservative and interventional therapies have been used for the treatment of foraminal inflammation, fibrotic adhesion, and pain. This update reviews the anatomy, pathophysiology, clinical presentation, diagnosis, and current treatment options of foraminal neuropathy.

• Journal of Plant Biology
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• v.35 no.3
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• pp.211-217
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• 1992

In order to elucidate the formation of reaction tissues during the transition from primary to secondary growth, the developmental anatomy was conducted in the first internode of Acer sacchan'num seedling in horizontal position. During the transition from primary to secondary growth, tension wood(gelatinous fiber) was gradually developed on the upper side only, And the tension wood formation in the upper side of the horizontal first internode proceeds acropetally from base to apical portion. Some of the anatomical features of tension wood start to be in the primary vascular tissue and a typical tension wood show during the secondary growth, Therefore, the procambium seems to respond to the gravity as well as vascular cambium. For this reason, both procambium and vascular cambium has to regard as the same meristem, On the other hand, the upper side vessels were longer than those of the lower side in the horizontal first internode. The lateral-wall pitting of vessel elements, however, showed no differences between upper and lower sides which have alternate type. The width and height of rayon the upper side of horizontal first internode was larger as compared with the lower side.r side.