• Journal of the Korean Wood Science and Technology
• /
• v.23 no.2
• /
• pp.55-69
• /
• 1995

The primary objective of this research was to investigate optimum manufacturing condition of thin composite panels composed of sawdust, polyethylene film and polypropylene net. At the study the experiment was designed to make thin board in which sawdust offers effectiveness as core composing material, polyethylene as adhesive with added urea resin, and polypropylene as stiffness and flexibility in the composition panel. 100 types of thin composite panels were manufactured according to press-lam and mat-forming process of various hot pressing conditions(pressure, temperature and time). They were tested and compared with control boards on bending properties(MOR, MOE, SPL, WML), internal bond strength, thickness swelling, linear expansion and water absorption. At the same time the visual inspections of each types of panels were accomplished. The physical and mechanical properties of composite types passed by visual inspection were analyzed by Tukey's studentized range test. From the statistical analysis, the optimum manufacturing condition of thin composite panels were selected. Compared with two manufacturing processes, mat-forming process performed better than press-lam process in all tested properties. The optimum manufacturing conditions resulted from the experiment and statistical analysis were able to determine as following: the press temperature was shown the most good result at 130$^{\circ}C$ in mat forming process and 140$^{\circ}C$ press lam process, the press time 4 min in both processes, but the press pressure was 25-10kg/$cm^2$ in mat forming and 15k/$cm^2$ press lam process.

• Journal of the Korean Wood Science and Technology
• /
• v.44 no.4
• /
• pp.600-606
• /
• 2016

Wood-based composite panels such as plywood, particleboard (PB), or medium density fiberboard (MDF) are mostly used in the lamination on their surface for the manufacturing of furniture, or interior building products, the concern on the formaldehyde emission (FE) from the surface laminated wood panels is increasingly attracting attentions from the public. Thus, this study was conducted to understand influence of surface laminating materials to the FE from PB and MDF with or without edge sealing, using 24-hour desiccator method. Both PB samples that had been laminated on their surface with low-pressure laminate (LPL) or polypropylene (PP) film and MDF that had been treated with poly(vinyl chloride) (PVC) or coating were tested for the FE with or without edge sealing. As expected, the FE of PB with the sealed edges decreased to 37.4% and 80.7% with the LPL and PP lamination, respectively. The surface laminated MDF with the sealed edges also showed a decrease in the emission up to 57.8% and 54.3%, with the PVC lamination and coating, respectively. However, the coated MDF samples showed 5.3% increase in the emission when their edges were not sealed, indicating a FE form the solvent used for coating. These results showed that the type of surface lamination materials on wood-based composite panels has a great impact on their resultant FE, indicating that the influence of surface laminating materials should be taken into consideration for the formaldehyde mission measurement.

• Fire Science and Engineering
• /
• v.32 no.4
• /
• pp.86-94
• /
• 2018

A sports center fire in Jecheon caused 29 deaths and 40 injuries. This study focused only on the structural factors of the building and equipment to investigate the causes of casualties based on the fire investigation results at the sports center. The structural factors of the building and equipment were a piloti-type parking lot, lack of a fire compartment between the piloti-type parking lot and lobby, lack of an installed sprinkler system, lack of an installed fire door in the main stairs on the $1^{st}$ floor, lack of an installed fire water tank on the rooftop, an installed pocket fire door in the main entrance on the $2^{nd}$ floor, poor fire compartments in an EPS space and a pipe pit and on each floor, a leak in the joint of a drain pipe, plywood installed in the hoistway of the freight elevator and interior wall, illegal remodeling of a closed rooftop structure, which cannot discharge smoke and heat, installed styrofoam insulation in the inside of the parking lot ceiling, an installed tempered glass window, which cannot be opened in the ladies bathroom on the $2^{nd}$ floor, and a finished dryvit exterior wall.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
• /
• 2011.04a
• /
• pp.180-187
• /
• 2011

본 논문은 다중이용업소와 목조건축물에 자주 사용되는 미송합판에 방염처리를 하여 유사 화재를 구현하고, 그 화염 세기에 따른 방염의 실효성을 실험한 것이다. 방염처리를 하면 화재 시 가연물의 초기착화시간을 지연시켜 화재성장속도를 늦출 수 있고, 원활한 소화활동을 가능하게 해준다. 하지만 어느 정도 화재가 진행되어 화염이 거세지면, 45도 연소시험을 통한 방염기준을 충족하여도 그 성능을 기대하기 어렵다고 한다. 따라서 45도 연소시험 시 사용되는 65mm의 불꽃보다 큰 화염상태(초기착화 이후의 상태)에서 방염처리한 내장재(미송합판)의 방염성능이 유지되는지의 여부를 실제로 입증하고 그 근거를 뒷받침하기 위하여 본 연구를 시작하게 되었다. 실험에서는 화재의 규모(화염의 세기)를 달리하여 각기 다른 종류의 방염제로 방염 처리한 미송합판의 착화 시 화염온도, 복사열 유속 그리고 착화지연시간을 파악하였으며, 45도 연소시험과 관련하여 방염성능을 분석하였다. 45도 연소시험의 경우 실험에 사용한 방염 처리 합판은 방염성능 기준을 만족하는 것으로 나타났으며, 소규모 유사 화재로 직경 10cm 연소용기를 사용한 연소실험에서는 방염 처리한 합판의 착화지연시간이 평균적으로 대규모 유사 화재실험보다 길어 어느 정도는 방염효과를 갖는 것으로 나타났다. 하지만 대규모 유사 화재로 1단위 유류화재 연소용기를 사용한 연소실험의 경우 열방출율이 커 형성된 탄화막이 무분별하게 박리되고 발화가 일어나 착화지연시간의 차이를 구별하기 어려웠기 때문에 방염효과를 기대할 수 없었다.

• Journal of the Korean Wood Science and Technology
• /
• v.19 no.4
• /
• pp.34-42
• /
• 1991

Protection of tropical forest affects on significant reduce of tropical hardwood supply, and softwood resources will be increasingly important for the timber security in Korea. U.S. softwood log was most favorite species for Korean softwood log importers in overall import conditions except price stablization and consistency of export policy. Reduced export volume from Pacific Northwest to Korean market has been immediately replenished by rediata pine from New Zealand and Chilean plantation. Siberian timber will hardly play major roles in Korean timber market unless budding structure. softwood plywood and softwood furniture uses are enhanced. Recent rapid rise of labor cost and reducing tariff rrate in Korea provided better opportunities for import lumber in building materials market. Dry dimension lumber was relatively profitable when processed from import U.S. soft-wood log while green lumber was favorable products processed from radiata pine log in Korean lumber market. This means U.S. softwood lumber would have better opportunity to market for '2${\times}$'4 studs when wood frame housing is introduced. On the other hand while radiata pine is competitive on temporary construction lumber such as supporter and concrete forming frame in Korea. Shortage of raw material for the new capacity of board plants in Korea will be it bottle neck. Major log export countries to Korea as U.S. New Zealand and Chile showed high trade intensity indices of composite hoard produces for Korean market. As Korea efforts to diversify import sources, and tariffs are reduced to 8% as scheduled by 1994. countries of scoring higher comparative advantages as Portugal. Brazil, Austria as well as New Zealand will have better opportunity to penetrate into promised Korean composites hoard market.

• Journal of the Society of Naval Architects of Korea
• /
• v.51 no.2
• /
• pp.114-121
• /
• 2014

Liquefied natural gas(LNG) cargo containment system(CCS) has the primary function of ensuring both adequate structural safety with respect to sloshing load which is defined as a violent behaviour of the liquid contents in CCS due to external forced motions and thermal insulation keeping natural gas below its boiling point. Among different LNG CCS types such as independent B-type and membrane ones, Mark III CCS is considered in this paper to perform its strength assessment. Mark III CCS plate is designed and constructed by stacking various non-metallic engineering materials such as plywood, triplex, reinforced PU foam that are supported by series of mastic upon inner steel hull structure. From the viewpoint of structural analysis, this plated structure is treated as a laminated composite structure showing complex structural behaviour under external load. Advanced finite element models of Mark III CCS plate is generated and used in conjunction with ultimate strength based failure criteria from laminated composite mechanics for the strength assessment. The strength assessment is performed within the initial failure state of Mark III CCS plate. Results provide failure details such as failure locations and loads. Finally obtained results are reviewed using the loads from acceptance criteria suggested by classification.

• Journal of the Korean Wood Science and Technology
• /
• v.27 no.3
• /
• pp.99-116
• /
• 1999

Wooden hollow core flush door is one of the main products of furniture manufacturing and woodworking industries. Warping and buckling of the door is serious problems in service. It has been reported that warping is caused by differences of physical and mechanical properties of face and back of skin panel for the door. This study focused on the prediction of warping and buckling phenomena of the flush door using numerical models. Predictions from the models were also compared with the experimental results obtained from the doors with plywood and hardboard skin panels under various environmental conditions. Three elastic constitutive models, so called elastic beam model, plate model and plate-buckling model, were employed to predict warping and buckling of the doors. It was observed that warping was more pronounced in low humidity condition than in high humidity condition. The plate model considering Poisson's effect was reliable to predict warping more closely than elastic beam model in low humidity condition. The plate-buckling model, however, was the best in the fitting of predictions with the experimental results under high humidity condition because buckling was developed in face and back of skin panel at that condition.

• Fire Science and Engineering
• /
• v.34 no.4
• /
• pp.13-21
• /
• 2020

This study tested the wood used in building interiors; each type had various incident heat fluxes based on their thickness. The combustion characteristics measured were effective heat of combustion, heat release rate peak and arrival time, maximum average rate of heat emission, and piloted ignition temperature. The wood specimens used in the experiment were 4.8 to 18 mm thick. 25, 35, 50, and 60 kW/㎡ were applied to the incident heat flux that the wood specimens were exposed to. The wood specimens tested were two types of medium-density fiberboard (each with a different density), treated red pine, particle board, and plywood. A comprehensive comparison of different fire characteristics was conducted to analyze the fire patterns corresponding to each type of wood in this way, the risk of fire was studied. The risk of fire was particularly high for particle board. The results of quantifying the fire characteristics of the types of wood studied could function as important input data with which to calculate the fire load of composite combustibles.

• Journal of Korean Society of Forest Science
• /
• v.104 no.2
• /
• pp.254-260
• /
• 2015

This paper assesses the tariff reduction on imported wood products that will have impact on the demand for domestic wood products in South Korea, by estimating the Armington substitution elasticities based on the assumption that they are imperfect substitutes. Results indicate that domestic and foreign wood products are far from perfect substitutes to each other. The substitution elasticities in plywood and fiberboard appeared to be high, implying that tariff reduction may have negative effects on those industries. On the contrary, imported and domestic particleboard showed a low substitution elasticity. The decline of fiberboard industry may lead to the decline in forestry since fiberboard is produced mainly by thinned woods supplied from domestic forests. Therefore, effective countermeasures to enhance the competitiveness of wood products industry are needed to cope with the market opening.

• Bulletin of the Korean Chemical Society
• /
• v.23 no.8
• /
• pp.1106-1109
• /
• 2002

Studies on subtle spacer ligand effects of AgCF3SO3 with 3,3'-Py2X (X = O vs S) have been carried out. The reaction of AgCF3SO3 with 3,3'-Py2O and 3,3'-Py2S produces [Ag(CF3SO3)(3,3'-Py2O)] and [Ag(3,3'-Py2S)] (CF3SO3), respectively. Crystallographic characterization of [Ag(CF3SO3)(3,3'-Py2O)] (monoclinic P1, a =8.405(2) $\AA$, b = 10.714(2) $\AA$, c = 18.031(2) $\AA$, $\alpha=$ 77.36(2), $\beta=107.83(2)^{\circ}$, $\gamma=$ 66.92(2), V = 1438.0(5) $\AA3$ , Z =2,R = 0.0486) reveals that the skeletal structure is an anion-bridged double-strand. The double-strands are packed like a plywood. The framework of [Ag(3,3'-Py2S)](CF3SO3) (orthorhombic Pcab, a = 17.330(2) $\AA$, b = 8.640(1) $\AA$, c = 19.933(6) $\AA$, V = 2985(1) $\AA3$ , Z =8, R = 0.0437) is a sinusoidal single-strand. The formation of each coordination polymer appears to be primarily associated with the donating ability and the confor ma-tional energy barrier of the spacer ligands. Thermal analyses indicate that [Ag(CF3SO3)(3,3'-Py2O)] and [Ag(3,3'-Py2S)](CF3SO3) are stable up to 250 $^{\circ}C$ and 210 $^{\circ}C$, respectively. For the anion exchangeability, the nature of the spacer ligand is more significant factor than the distance of silver(Ⅰ)···triflate.