• Journal of the Korean Wood Science and Technology
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• 제48권6호
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• pp.791-806
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• 2020

본 연구에서는 공학목재로 목구조건축에 주로 사용되는 집성재 및 CLT 그리고 Ply-lam CLT의 블록전단시험을 실시하여 강도 및 파괴 유형을 비교 분석하였다. 이를 통해 Ply-lam CLT의 라미나 및 합판의 수종, 접착제의 종류 및 Layer구성 등 최적생산을 위한 제조조건을 구명하고자 하였으며 그 결과는 다음과 같다. 블록전단시험을 통해 집성재, Ply-lam CLT, CLT 순으로 높은 강도를 나타냈다. 특히, 낙엽송 합판과 낙엽송 라미나의 복합구조로 제조되는 Ply-lam CLT의 전단강도는 집성재 전단강도 기준인 7.1 N/㎟을 통과하였다. 아울러 본 연구에서는 집성재, CLT, Ply-lam 접착에 사용된 접착제 종류에 따른 전단강도의 차이는 나타나지 않았다. 그러나 Ply-lam CLT의 경우에는 라미나와 합판의 수종에 따라 Ply-lam CLT의 전단강도의 차이를 나타냈다. 그 결과는 낙엽송 > 남양재 ≒ 육송 합판 순으로 높은 강도를 나타났다. Ply-lam CLT의 최적 구성은 낙엽송 합판과 낙엽송 라미나를 사용하는 경우이며 접착제는 용도에 따라 PRF, PUR을 선정하여 사용하면 될 것으로 판단된다. 목질재료 유형에 따른 전단강도 파괴 양상 결과 분석을 통하여 집성재는 shear parallel-to-grain, CLT는 rolling shear, Ply-lam CLT는 shear parallel-to-grain과 rolling shear가 복합적으로 나타났다. 이는 전단강도 결과와 밀접한 관련이 있으며 rolling shear로 인하여 CLT보다 Ply-lam CLT에서 더 높은 전단 강도를 나타내는 것으로 판단된다.

• Journal of the Korean Wood Science and Technology
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• 제48권5호
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• pp.685-695
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• 2020

The connection performance between cross-laminated timber (CLT) walls and support has the greatest effect on the horizontal shear strength. In this study, the horizontal shear performance of CLT walls with reinforced connection systems was evaluated. The reinforcements of metal bracket connections in the CLT connection system was made by attaching glass fiber-based reinforcement to the connection zone of a CLT core lamina. Three types of glass fiber-based reinforcement were used: glass fiber sheet (GS), glass fiber cloth (GT) and fiber cloth plastic (GTS). The horizontal shear strength of the fabricated wall specimens was compared and evaluated through monotonic and cyclic tests. The test results showed that the resistance performance of the reinforced CLT walls to a horizontal load based on a monotonic test did not improve significantly. The residual and yield strengths under the cyclic loading test were 38 and 18% higher, respectively, while the ductility ratio was 38% higher than that of the unreinforced CLT wall. The glass fiber-based reinforcement of the CLT connection showed the possibility of improving the horizontal shear strength performance under a cyclic load, and presented the research direction for the application of real-scale CLT walls.

• 한국음향학회지
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• 제42권6호
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• pp.572-583
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• 2023

전 세계적으로 탄소중립 2050 실현을 위한 목조 건축물 수요가 늘어나고 있으며, 국내에서도 구조용 직교 집성판(Cross Laminated Timber, CLT)을 이용한 목조 고층 건축물에 대한 기술적 검토가 이루어지고 있다. 본 논문에서는 CLT의 기초 음향성능을 검토하기 위해, 국내산 낙엽송과 소나무로 CLT 슬래브(두께 150 mm)를 제작해 바닥 충격음 차단 성능과 음향투과손실을 측정했다. 실험은 상하로 연결된 페어 잔향실에서 수행했으며, CLT 슬래브에 콘크리트 토핑(두께 50 mm ~ 210 mm, 6조건)을 추가해 차음성능 개선량을 정량적으로 평가했다. 수종에 따른 바닥충격음 차단 성능의 단일수치 평가량을 비교하면, 낙엽송 CLT가 소나무 CLT보다 중량 바닥충격음에서 3 dB, 경량 바닥충격음에서 1 dB 낮았으나, 상부에 콘크리트 토핑을 추가한 조건에서는 수종 간 차이가 없었다. 상부의 콘크리트 층 두께 상승에 따라 중량 바닥충격음이 9 dB ~ 20 dB, 경량충격음이 20 dB ~ 30 dB 저감했다. 이 관계를 면밀도로 분석한 결과, CLT 슬래브의 바닥충격음 차단 성능은 면밀도와 높은 상관관계(R² = 0.94 ~ 0.99)가 있는 것을 확인했다. CLT 슬래브의 음향투과손실은 수종에 따른 차이가 없었다. 면밀도와 주파수로 산출한 음향투과손실 이론치와 실측치의 주파수 특성은 유사하지만 실측치가 8 dB ~ 12 dB 낮아, 보정치를 이용해 실험 대상인 CLT 슬래브의 음향투과손실과 주파수 특성의 관계를 도출했다.

• Journal of the Korean Wood Science and Technology
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• 제48권2호
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• pp.245-252
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• 2020

This study was performed to analyze the mechanical properties of tropical hybrid cross-laminated timber (CLT) with bamboo laminated board as the core layer in order to evaluate the possibility of its use as a CLT material. Bamboo board was used as the core layer and the tropical species Acacia mangium willd., from Indonesia, was used as the lamination in the outer layer. The modulus of elasticity (MOE), modulus of rupture (MOR), and shear strength of the hybrid CLT were measured according to APA PRG 320-2018 Standard for Performance-Rated Cross-Laminated Timber. The results show that the bending MOE of the hybrid CLT was found to be 2.76 times higher than SPF (Spruce Pine Fir) CLT. The reason why the high MOE value was shown in bamboo board and hybrid CLT applied bamboo board is because of high elasticity of bamboo fiber. However, the shear strength of the hybrid CLT was 0.8 times lower than shear strength of SPF CLT.

• Journal of the Korean Wood Science and Technology
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• 제47권1호
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• pp.33-39
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• 2019

The square timbers of larch having cross section of $90mm{\times}90mm$ were glued laterally to be formed $1,200mm{\times}2,400mm$ panels which were used as cores for CLT wall panels. Then, structural plywood panels having size of $1,200mm{\times}2,400mm$ were used as cross band covering the small square timber cores to manufacture CLT wall panels. The sound absorption rate of CLT wall panels and polyester board attached CLT wall panels were investigated. The mean sound absorption coefficients of the former and the latter in the frequency range of 100-6400 Hz were 0.21 and 0.74, respectively. The noise reduction coefficients (NRC) of those were 0.21 and 0.40, respectively. Also, the mean sound transmission loss of CLT wood panel in the frequency range of 50-1600 Hz was 45.12 dB and that value at the frequency of 500 Hz was 42.49 dB. It was suggested that the polyester board attached CLT wall panels could be used as housing wall because of its high sound absorption rate and high sound transmission loss.

• 한국농촌건축학회논문집
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• 제22권4호
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• pp.71-78
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• 2020

Today, the whole world is going through a big chaos due to the COVID-19, but paradoxically, the emergence of COVID-19 has been leading to the need for sustainable development, such as Green New Deal that can improve global warming and carbon emissions, and the need for sustainable architecture is growing bigger and bigger in the architectural field as well. The level of CLT buildings in Korea is at a very rudimentary stage, while CLT buildings remedying existing wooden buildings are getting the spotlight among European countries for sustainable architecture. This study was conducted to categorize structure layer compositions of overseas CLT buildings and analyze architectural techniques and materials applied by collecting and analyzing information about CLT structure layer compositions of overseas CLT building-related institutions, companies and cases. When classifying structure layer compositions of foreign CLT buildings depending on the roles of layers. it was revealed that exterior wall structure layers were combined and organized within a sequence of external finishing, ventilation, waterproof, board, external insulation, airtightness, structure, airtightness, interior insulation, interior finishing, sloped roof structure layers were external finishing, ventilation, waterproof, board, external insulation, airtightness, structure, airtightness, interior insulation, interior finishing, flat roof structure layers were external finishing, ventilation, waterproof, planking wood, external insulation, waterproof, external insulation, airtightness, structure, airtightness, interior insulation, interior finishing.

• Journal of the Korean Wood Science and Technology
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• 제51권5호
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• pp.419-430
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• 2023

In this study, the floor impact sound insulation performance of Korean domestic Cross-Laminated Timber (CLT) slabs was evaluated according to their joint types, species and thicknesses in laboratory experiments. The sound insulation performance of the CLT has not been investigated before, thus, this study was conducted to quantify basic data on floor impact sound insulation performance of CLT slabs. 5-ply and 150 mm thick CLT panels made of 2 species, Larix kaempferi and Pinus densiflora, were used for the study. The CLT panels were assembled by 3 types of inter-panel joints to form floor slabs: spline, butt and half-lap. And the 150 mm thick Larix CLT slabs were stacked to the thicknesses of 300 mm and 450 mm. The heavy-weight floor impact sound insulation performance of the 150 mm CLT slabs were evaluated to be 70 dB for the Larix slabs and 71.6 dB for the Pinus slabs, and the light-weight floor impact sound insulation performance, 78.3 dB and 79.6 dB, respectively. No significant difference in the sound insulation performance was found between the slabs of the 2 species or among the 3 types of joints. The reduction of 1 dB in the heavy-weight floor impact sound and 1.6 dB in the light-weight floor impact sound per 30 mm increase in thickness were confirmed through the experiments. This study can be viewed as the basic research for the evaluation of floor impact sound insulation performance of CLT.

• Journal of the Korean Wood Science and Technology
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• 제45권6호
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• pp.746-752
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• 2017

Cross-laminated timber (CLT) is a relatively new engineered wood for timber construction. It is a great shear wall material. It was known that the shear performance of the CLT wall depends on the performance of connections. In connection, nail or screw has to be installed with a certain distance from the end of the timber. Current building code specifies the distance on the name of end distance. The end distance was decided as a minimum distance not to make splitting or tearing out in lumber or glued laminated timber. As a relatively new engineered wood, the end distance of CLT connection need to be identified because CLT is cross-wisely glued lumber products like plywood. Different from glued laminated timber or lumber, cross layer of CLT may prevent wood from splitting or tearing-out. As a result, the end distance of CLT was expected to be reduced than glued laminated timber. The shorter end distance may let more versatile connector design possible. In this study, prior to developing novel connection for CLT, the end distance of CLT connection was experimentally investigated to identify the end distance limitation. The experiments showed that the end distance can be reduced from 7D to 6D, in case of the tested CLT combination and screw in this study.

• Journal of the Korean Wood Science and Technology
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• 제45권6호
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• pp.846-856
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• 2017

The aim of this study was to develop the details of cross-laminated timber (CLT) envelops for satisfying the design standard for energy saving (DSEA) and passive standard in South Korea. When the same thickness of 180 mm concrete or CLT was used and the same materials for other layers were used for the roof, wall, and interlayer floor, the required insulation thickness for the different building envelopes in central, southern, and Jeju island was evaluated. As a result, compared to the concrete envelop, about 43 mm of insulation thickness was reduced for wall and roof with the CLT envelope. When the CLT envelopes were modified to protect the CLT from moisture based on FPInnovations (2011), the insulation thickness was further reduced by 12 mm. When the modified CLT building envelops satisfied with a passive standard are used for 10-story building, the required insulation was decreased by $40.89m^3$ for a floor ($105.27m^2{\times}2.3m$ in height) compared to concrete building. As the number of floors increases, about 3.58 m3 of insulation per floor was additionally saved.

• Biomolecules & Therapeutics
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• 제16권1호
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• pp.21-27
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• 2008

Clotrimazole (CLT), a potent antifungal drug, is known to inhibit tumor cell proliferation. In the present study, we examined the role of intracellular $Ca^{2+}$ in CLT-induced cell cycle arrest of colon adenocarcinoma HT29 cells. CLT inhibited growth of HT29 cells in a concentration-dependent manner, which was associated with inhibition of cell cycle progression at the G(1)-S phase transition and an increase in the expression of cell cycle inhibitor proteins p27 and p53. CLT also suppressed the $Ca^{2+}$ overload by A23187, a calcium ionophore, suggesting its role in modulation of intracellular $Ca^{2+}$ concentration in HT29 cells. The simultaneous application of CLT and A23187 with addition of $CaCl_2$ (1mM) to the medium significantly reversed CLT-induced p27 and p53 protein level increase and growth suppression. Our results suggest that CLT induces cell cycle arrest of colon adenocarcinoma HT29 cells via induction of p27 and p53, which may, at least in part, be mediated by alteration of intracellular $Ca^{2+}$ level.