• Journal of the Korean Wood Science and Technology
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• 제31권3호
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• pp.17-23
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• 2003

As a fundamental study of developing sawdust board from thinning softwood logs from three species (Pinus densiflora S. et Z., Larix leptolepis G. and Pinus koraiensis S. et Z.), this study examined the effect of board density and resin content on physical and mechanical properties of sawdust board. As the board density increase, thickness swelling, bending strength, and Brinell hardness increased while water absorption decreased. With increasing the resin content, the bending strength and hardness increased while water absorption and thickness swelling decreased. The board made of L. leptolepis was slightly low in its water absorption, and the one made of P. koraiensis was a little high in its bending strength, while there was no definite difference between each kind of trees in their hardness values.

• Journal of the Korean Wood Science and Technology
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• 제45권1호
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• pp.62-71
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• 2017

본 연구는 쌀의 도정과정에서 발생되는 농업부산물인 왕겨를 탄화시켜 만든 왕겨숯을 톱밥과 혼합하여 밀도별, 수지첨가율별 및 톱밥첨가율별로 보드를 제조하고 기초물성을 측정하여 보드 재료로서의 이용가능성을 검토하였다. 수분흡수율은 수지첨가량 25%일 때 80.09%로 가장 낮은 값을 나타냈고, 밀도가 증가하고 톱밥첨가량이 감소할 때 수분흡수율이 감소하는 경향을 나타냈다. 또한 측정된 두께팽윤율은 KSF 3104 파티클보드의 품질규정에 만족시키고 있어 치수안정성 부분에서 건축내장재로 활용가능성이 확인되었다. 박리강도는 수지첨가량 25%일 때 $0.244N/mm^2$으로 KSF 3104 파티클보드의 품질기준을 만족시켰지만, 나머지 조건에서는 현저하게 낮은 값을 나타내 조건을 충족시키지 못하였다. 밀도, 수지첨가율, 톱밥첨가율이 증가할수록 경도도 증가하는 경향을 나타냈다.

• Journal of the Korean Wood Science and Technology
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• 제41권6호
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• pp.528-534
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• 2013

본 연구는 톱밥과 귤박을 이용하여 혼합보드를 제조하여 기본 물성을 조사하였다. 혼합보드의 귤박 혼합율이 10%에서 40%로 증가함에 따라 흡수율은 94.1%에서 86.5%로, 두께 팽창율은 27.2%에서 18.0%로, 휨강도는 $65.1kgf/cm^2$에서 $39.2kgf/cm^2$로, 경도는 $195.3kgf/cm^2$에서 $180.3kgf/cm^2$로 감소하였다. 혼합보드의 밀도가 $0.4g/cm^3$에서 $0.8g/cm^3$로 증가함에 따라 흡수율은 149.2%에서 58.6%로 감소하였으나, 두께 팽창율은 6.4%에서 17.9%로, 휨강도는 $4.2kgf/cm^2$에서 $96.6kgf/cm^2$로, 경도는 $40.4kgf/cm^2$에서 $196.2kgf/cm^2$로 증가하였다.

• 한국가구학회지
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• 제11권1호
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• pp.85-89
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• 2000

This study investigated the effect of steaming on fixation of compression set and the effect of these treatments on mechanical properties of heat-compressed wood specimens. To determine the effect of steaming after compression set, wood specimens were compressed for 100min at 180f and then steamed for 20-100min at $120^{\circ}C$. Swelling tests were used to evaluate recovery of compression set. Bending, compression, and Brinell hardness tests were carried out for evaluating mechanical properties. Compressed wood steamed for 100 min at $120^{\circ}C$ showed 1.9% recovery of set, increases in bending and compressive properties, and no hardness change. We concluded that almost complete fixation of compression set in wood can be achieved by steaming compressed wood.

• 대한치과기공학회지
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• 제19권1호
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• pp.43-54
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• 1997

This investigation is carried out of inqurie into the effects of the accelerator on the setting time and haedness when it is used with plaster products. Plaster($\beta$), dental hard stone($\alpha$), and limproved dental hard stone($M{\alpha}$) are selected as the objects of the investigation, since they are most common materials for dental plaster products. Setting time is gauged by means of Vicket Needle and Gilmore Needle, and hardness is gauged by means of Brinell and Vicket Hardness machines. Samples of each material are made in the standerd water powder ratio and with the accelerator repectively, Every material is tested five times each. The results of the tests are as fallow : 1) In each case the setting time is shortened when the accelerator is used. 2) Of the three materials the hardness of the plaster was lowest A($\beta$) < B($\alpha$) < C($M{\alpha}$)} 3) In each case the hardness of the samples made in the standard water powder ratio were higher than that of the sample made with the accelerator. A1 > A2 ; B1>B2 ; C1>C2 4) Final Conclusion : Higher quality cast is expected when it is made in the standard water powder ratio.

• 한국가구학회지
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• 제28권2호
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• pp.111-117
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• 2017

Recently, as people's interest in wood has increased, the use of wood as household and landscape decking materials has increased. As the deck material, imported wood such as synthetic wood, Ipe, and Malas was used in addition to the existing preserved wood, but recently deck use has been activated as part of the activation of domestic materials. As an important quality factor in the selection of such decking materials, various durability along with weatherability for long - term use is required for maintenance. Generally used tropical hardwoods have excellent weatherability and durability without additional preservative treatment. However, the domestic larch is a wood species with a higher specific gravity and durability than ordinary conifers. However, it has not yet been used as a deck material due to lack of comparative studies on its characteristics. Therefore, hardness and durability of wood were measured using six specimens of Ipe, Massaranduba, Malas, Douglas-fir, Larch and Torrefied-Larch. Density Profile was used to measure the density, and Brinell hardness test and resistance test against momentary impact were carried out for the test of resistance to static load. Also, The hardness and durability of wood were measured by castor test with resistance test against dynamic load, as well as, nail down test by experiment on surface hardness and durability. As a result of the experiment, the hardness was increased in proportion to the density, and it was confirmed that the imported lumber was harder and durable than the domestic larch.

• 한국주조공학회지
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• 제42권6호
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• pp.337-346
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• 2022

본 연구에서는 Al-7Si-(0.3~0.5)Mg-(0~0.5)Cu 합금의 용체화 처리 조건 최적화를 위해 545℃ 온도 조건에서 최대 7시간까지 용체화 처리를 수행한 후 광학현미경 및 FE-SEM을 활용한 미세조직 관찰 및 브리넬 경도 측정을 수행하였다. 합금 내 공정 Si 상은 용체화 처리 초반 3시간 동안 급격한 조대화 현상을 나타내었으며, 이후에는 용체화 처리가 진행되어도 Si 상 크기는 크게 변화하지 않았다. 한편 공정 Si 상의 구상화의 경우, 용체화 처리 시간이 7시간에 도달할 때 까지 지속적으로 진행되었다. Cu가 첨가된 합금의 주방상태에서는 Q-Al₅Cu₂Mg₈Si₆ 상과 θ-Al₂Cu 상이 확인되었으나, 545℃에서 3시간 동안 진행된 용체화 처리 이후에는 모두 분해되었다. 주방상태에서 확인된 π-Al₈FeMg₃Si 상은 5시간의 용체화 처리 이후에 사라지거나(0.3wt%Mg) 혹은 7시간의 용체화 처리 이후에도 존재(0.5wt%Mg)하였다. 초정 α상 내 Mg 및 Cu 함량은 용체화 처리 시간이 5시간에 도달할 때 까지 증가하였으며, 이는 Mg 및 Cu를 함유한 금속간 화합물의 용체화 시간에 따른 분해 거동과 일치하였다. Al-7Si-Mg-Cu 합금의 용체화 처리 과정에서 확인한 미세조직 변화를 종합적으로 고려할 때, 본 연구에서 다룬 합금의 석출강화 효과 극대화를 위해서는 545℃ 조건에서 최소 5시간의 용체화 처리가 필요한 것으로 판단되며, 용체화 처리 조건 별로 측정된 브리넬 경도 데이터로부터 동일한 최적 용체화 처리 조건을 도출할 수 있었다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.1597-1600
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• 2003

Fine-Blanking is an advanced and precision stamping process, by which a component with precise geometry and smooth cut surface can be produced without any further major secondary operations. By applying the Fine-Blanking technology, the significant improvement of the component should be obvious. As the components are with good shape, smooth surface and precise size, they can be ready for assembly without any further secondary operations. The productivity is increased, the production cycle time and the component cost are significantly reduced. We apply the fine-Blanking for chain sprocket. And do Mecanical test for compress strenth. impaact, roughness, Brinell hardness, dimensional stability.

• 한국농공학회지
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• 제26권1호
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• pp.52-72
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• 1984

This study was performed to obtain the basic data which can be applied to the use of epoxy resin mortars. The data was based on the properties of epoxy resin mortars depending upon various mixing ratios to compare those of cement mortar. The resin which was used at this experiment was Epi-Bis type epoxy resin which is extensively being used as concrete structures. In the case of epoxy resin mortar, mixing ratios of resin to fine aggregate were 1: 2, 1: 4, 1: 6, 1: 8, 1:10, 1 :12 and 1:14, but the ratio of cement to fine aggregate in cement mortar was 1 : 2.5. The results obtained are summarized as follows; 1.When the mixing ratio was 1: 6, the highest density was 2.01 g/cm$^3$, being lower than 2.13 g/cm$^3$ of that of cement mortar. 2.According to the water absorption and water permeability test, the watertightness was shown very high at the mixing ratios of 1: 2, 1: 4 and 1: 6. But then the mixing ratio was less than 1 : 6, the watertightness considerably decreased. By this result, it was regarded that optimum mixing ratio of epoxy resin mortar for watertight structures should be richer mixing ratio than 1: 6. 3.The hardening shrinkage was large as the mixing ratio became leaner, but the values were remarkably small as compared with cement mortar. And the influence of dryness and moisture was exerted little at richer mixing ratio than 1: 6, but its effect was obvious at the lean mixing ratio, 1: 8, 1:10,1:12 and 1:14. It was confirmed that the optimum mixing ratio for concrete structures which would be influenced by the repeated dryness and moisture should be rich mixing ratio higher than 1: 6. 4.The compressive, bending and splitting tensile strenghs were observed very high, even the value at the mixing ratio of 1:14 was higher than that of cement mortar. It showed that epoxy resin mortar especially was to have high strength in bending and splitting tensile strength. Also, the initial strength within 24 hours gave rise to high value. Thus it was clear that epoxy resin was rapid hardening material. The multiple regression equations of strength were computed depending on a function of mixing ratios and curing times. 5.The elastic moduli derived from the compressive stress-strain curve were slightly smaller than the value of cement mortar, and the toughness of epoxy resin mortar was larger than that of cement mortar. 6.The impact resistance was strong compared with cement mortar at all mixing ratios. Especially, bending impact strength by the square pillar specimens was higher than the impact resistance of flat specimens or cylinderic specimens. 7.The Brinell hardness was relatively larger than that of cement mortar, but it gradually decreased with the decline of mixing ratio, and Brinell hardness at mixing ratio of 1 :14 was much the same as cement mortar. 8.The abrasion rate of epoxy resin mortar at all mixing ratio, when Losangeles abation testing machine revolved 500 times, was very low. Even mixing ratio of 1 :14 was no more than 31.41%, which was less than critical abrasion rate 40% of coarse aggregate for cement concrete. Consequently, the abrasion rate of epoxy resin mortar was superior to cement mortar, and the relation between abrasion rate and Brinell hardness was highly significant as exponential curve. 9.The highest bond strength of epoxy resin mortar was 12.9 kg/cm$^2$ at the mixing ratio of 1:2. The failure of bonded flat steel specimens occurred on the part of epoxy resin mortar at the mixing ratio of 1: 2 and 1: 4, and that of bonded cement concrete specimens was fond on the part of combained concrete at the mixing ratio of 1 : 2 ,1: 4 and 1: 6. It was confirmed that the optimum mixing ratio for bonding of steel plate, and of cement concrete should be rich mixing ratio above 1 : 4 and 1 : 6 respectively. 10.The variations of color tone by heating began to take place at about 60˚C, and the ultimate change occurred at 120˚C. The compressive, bending and splitting tensile strengths increased with rising temperature up to 80˚ C, but these rapidly decreased when temperature was above 800 C. Accordingly, it was evident that the resistance temperature of epoxy resin mortar was about 80˚C which was generally considered lower than that of the other concrete materials. But it is likely that there is no problem in epoxy resin mortar when used for unnecessary materials of high temperature resistance. The multiple regression equations of strength were computed depending on a function of mixing ratios and heating temperatures. 11.The susceptibility to chemical attack of cement mortar was easily affected by inorganic and organic acid. and that of epoxy resin mortar with mixing ratio of 1: 4 was of great resistance. On the other hand, when mixing ratio was lower than 1 : 8 epoxy resin mortar had very poor resistance, especially being poor resistant to organicacid. Therefore, for the structures requiring chemical resistance optimum mixing of epoxy resin mortar should be rich mixing ratio higher than 1: 4.

• 임산에너지
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• 제21권2호
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• pp.10-16
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• 2002

소나무, 낙엽송 및 잣나무 간벌재를 재료로 가압압력과 열압시간을 달리하여 톱밥 보드를 제조하고, 이들이 보드의 물성에 미치는 영향을 조사하였다. 두께 팽창율과 흡수율은 열압시간이 증가함에 따라 감소하였으며, 휨강도와 경도는 열압시간이 증가함에 따라 증가하였다. 톱밥보드의 물성은 가압압력 보다 열압시간에 의해 영향을 받음을 알 수 있었고, 수종간 비교에서는 뚜렷한 경향을 발견 할 수 없었다.