• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2000.08a
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• pp.149-152
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• 2000

통신기술의 발달과 정보화 사회로 빠르게 변화되면서, 유선ㆍ무선, 핸즈프리, 원거리 화상회의 등의 다양한 방식의 통신이 이루어지고 있다. 음성통신의 어려운 문제 중에 하나는 주위의 소음이다. 소음은 상황에 따라서 다양하고 복잡하여 그 특성을 분석하기가 어렵다. 소음의 특성과 반향 등을 분석하기 위해서는 수 천 개의 적응필터 탭이 필요하게 된다. 따라서 실시간 소음제거를 위해서는 계산량이 많아 어려움이 따르므로 계산량 감소를 위해 FFT연산에 근거한 주파수 영역의 FDAF 적응필터를 이용하게 되었다. 하지만 계산량은 상당히 감소되었지만, 적응필터의 차수가 증가하면서 시간지연과 하드웨어적으로 복잡하게 되어 블록의 차수를 줄일 수 있는 MDF를 비교 검토하였다.

• Journal of the Korean Wood Science and Technology
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• v.49 no.5
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• pp.453-461
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• 2021

In wood-based composite panels, low-molar ratio (LMR) urea-formaldehyde (UF) resins usually result in reduced formaldehyde emission (FE) at the expense of poor adhesion. However, the FE and adhesion of medium-density fiberboard (MDF) bonded with LMR UF resins were both improved in this study. The modified LMR UF resins with transition metal ion-modified bentonite (TMI-BNT) nanoclay simultaneously improved the FE and adhesion of MDF panels. The modified LMR UF resins with 5% TMI-BNT resulted in a 37.1% FE reduction and 102.6% increase in the internal bonding (IB) strength of MDF panels. Furthermore, thickness swelling and water absorption also significantly decreased to 13.0% and 24.9%, respectively. These results imply that TMI-BNT modification of LMR UF resins could enhance the formation of a three-dimensional network rather than crystalline domains, resulting in improved cohesion.

• Cement
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• s.119
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• pp.14-20
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• 1990

• Journal of the Korean Wood Science and Technology
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• v.36 no.1
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• pp.45-53
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• 2008

The burning behaviors of board for flooring materials were investigated using cone calorimetry at an incident heat flux of $50kWm^{-2}$. Seven domestic flooring materials were used to observe the burning behavior of maximum heat release rate, total heat release and average heat release rate. The experimental data indicated that the medium density fiberboard (MDF) flooring had higher release rate than the other flooring materials. Also, the mass loss of MDF flooring was higher than the other floors. When measuring the smoke production from burning, PE fiberboard flooring and PVC Plastic Resin Sheet showed higher carbon monoxide and carbon dioxide yield than the others. The average smoke release of both carbon dioxide and carbon monoxide through specific extinction area was similar. Toxic smoke measurement from flooring materials were determined by the mouse stop motion, and the results indicated that MDF flooring contains more toxic material than the other flooring materials.

• Journal of the Korean Wood Science and Technology
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• v.44 no.5
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• pp.639-654
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• 2016

This study building materials by relates to human hazard assessment in accordance with the combustion gas SEM, the flame-retardant foam FTIR and cone calorimeter to configure the Forest products of MDF and preservative treated Lauan two kinds of Retardant styrofoam, Styrofoam, Urethane foam and gypsum board four kinds of plastics material by the combustion gas were each analyzed. MDF was burned to the structure of the wood and the glue evenly mixed combustion area preservative treated Lauan, kept constant even in the form of high heat to penetrate deep into the wood flame retardant agents. Retardant styrofoam is due to feed my Dropped dissolved inorganic flame retardant without the fire-stick and confirmed that the weak form of gypsum board, but keep the column. In MDF ammonia ($NH_3$), lethal concentration (750 ppm) compared to 795 ppm, preservative treated Lauan is carbon dioxide ($CO_2$) that was greater than 2.5 times the lethal concentration (100,000 ppm) to 256,965 ppm, the lethal concentration (500 ppm) of hydrogen chloride (HCl). The Urethane greater than 697 ppm, 434 ppm also greatly exceeding the nitrogen dioxide ($NO_2$) lethal concentration (250 ppm) in Retardant styrofoam and 398 ppm was released. It is confirmed that the human body is extremely harmful gas emitted from most of the materials to be utilized as basic data for evaluating the hazard-specific human future building material.

• Composites Research
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• v.12 no.3
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• pp.84-90
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• 1999

High alumina cement(HAC) and polyvinyl alcohol(PVA) based macro-defect-free(MDF) cement composites were reinforced using short carbon fibers, 3mm in length, 1-4% in weight fraction and insoluble polymers such as polyurethane, epoxy, phenol resin, in order to increase mechanical properties and water stability. The specimens were manufactured by the low heat-press(warmpress) method. In addition, the interface and the cross-linking reaction of cement and polymers was also studied by the SEM and TEM. Flexural strength of HAC/PVA based MDF cementitious composites was proportionally decreased with increasing fiber contents due to the undensified structure around fibers. The flexural strength of insoluble polymer added specimen was decreased with increasing fiber contents, while water stability was dramatically improved. Epoxy resin added specimen showed the highest strength with increasing fiber contents, compared with other specimens. The water stability of fiber content 4% added specimen immersed in water presented about 95%, 87% at 3 and 7 days immersed in water, respectively. The interfacial adhesive strength of fiber-matrix was very much improved due to cross linking reaction of polymer and metal ions of cement. Tensile strength of insoluble polymers added composites as linearly increased with increasing the fiber contents. The epoxy resin added specimen also showed highest tensile strength. The 4% fiber added specimen presented 30~80% higher strength than controlled specimen.

• Fire Science and Engineering
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• v.33 no.1
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• pp.76-84
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• 2019

Experimental studies using an open cone calorimeter were conducted to provide information on the CO and soot yields of wood combustibles required for a kitchen fire simulation of PBD. A total of eight specimens were examined for medium density fiberboard (MDF) and particle board (PB), which are used widely in kitchen furniture production, depending on the water content, surface processing method, and surface color. The thermal penetration time related to the fire spread rate in the depth direction differed significantly according to the surface processing treatment method, even for a specimen of identical thickness. The CO yield ($y_{CO}$) of the MDF and PB series did not change significantly according to the combustion mode and surface treatment process in flaming mode. On the other hand, $y_{CO}$ was approximately 10 times higher in smoldering mode than in flaming mode. The soot yield ($y_{soot}$), however, varied considerably depending on the combustion mode and surface treatment process. In particular, a higher $y_{soot}$ was found in flaming mode and in the surface-treated specimens. Finally, the $y_{CO}$ and $y_{soot}$ of MDF and PB measured for the kitchen fire simulation of PBD were applied.

• Journal of the Korean Wood Science and Technology
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• v.30 no.2
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• pp.172-179
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• 2002

In this study, two materials treated with a flame retardant were examined for their fire resistance. The first, MDF (medium density fiberboard) was overlaid by an oak sliced veneer, which was either treated by soaking in a 6wt.% solution of flame retardant chemicals (pentabromine-chlorinated paraffin) or non-treated and then was coated with either a flame retardant polyurethane coating or with a common polyurethane coating. The second material, Pinus koraiensis penal was either treated by a spray treatment using a flame retardant solution or non-treated and then was coated with either a flame retardant polyurethane coating or with a common polyurethane coating. Pentabromine-chorinated paraffin chemicals were added (6 part of urethane resin) as the flame retardant chemicals in the polyurethane coatings. In the fire resistance test, the th𝜃(℃·min) decreased with the flame retardant treatment or/and the flame retardant coatings, compared to the untreated sample Weight loss (%) decreased with the flame retardant treatment or/and the flame retardant coatings. The ignition time (sec.) increased and the residual flame time (sec.) decreased with the flame retardant treatment or/and flame retardant coatings. Therefore, the flame retardant treatment or/and flame retardant polyurethane coatings have excellent incombustibility.

• Proceedings of the IEEK Conference
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• 2001.09a
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• pp.927-930
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• 2001

본 논문에서는 웨이블렛 변환 알고리듬을 이용 한 음향반향 제거 기법을 제안하였다. 일반적으로 LMS 알고리듬은 간단하지만 그 수렴특성이 고유치 분포율과 탭 수에 의해 결정되는 단점이 있고 MDF (multidelay filter)를 이용한 적응 알고리듬은 블록단위로 수행되는 LMS를 수렴속도 측면에서 보완해주지만 긴 차수일때는 FFT에 비례하여 연산량이 늘어나는 단점이 있다. 본 논문은 웨이블렛의 직교성을 이용한 변환 적응 알고리듬을 음향반향 제거기에 도입하여 그 성능을 비교·평가하였다. 모의실험을 통해 시간영역 LMS, MDF 알고리듬과 비교하여 제안한 알고리듬의 수렴성능이 우수함을 보였다.

• Magazine of the Korea Concrete Institute
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• v.2 no.2
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• pp.20-25
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• 1990