• Applied Chemistry for Engineering
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• v.32 no.3
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• pp.332-339
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• 2021

Recently, due to concerns about the depletion of fossil fuels and the emission of greenhouse gases, the importance of hydrogen energy technology, which is a clean energy source that does not emit greenhouse gases, is being emphasized. Water electrolysis technology is a green hydrogen technology that obtains hydrogen by electrolyzing water and is attracting attention as one of the ultimate clean future energy resources. In this study, the surface properties of the porous transport layer (PTL), one of the cell components of the proton exchange membrane water electrolysis (PEMWE), were controlled using a sandpaper to reduce overvoltage and increase performance and stability. The surfaces of PTL were sanded using sandpapers of 400, 180, and 100 grit, and then all samples were finally treated with the sandpaper of 1000 grit. The prepared PTL was analyzed for the degree of hydrophilicity by measuring the water contact angle, and the surface shape was observed through SEM analysis. In order to analyze the electrochemical characteristics, I-V performance curves and impedance measurements were conducted.

• Journal of Forest and Environmental Science
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• v.35 no.4
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• pp.223-231
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• 2019

Castanopsis indica (Sil Batna) is an ecologically valuable multipurpose indigenous tree species of Bangladesh. Considering its high value but poor natural regeneration due to seed dormancy, the authors conducted an experiment at the Institute of Forestry and Environmental Sciences Chittagong University (IFESCU) during 2012-2013 to find out effective pre-sowing treatments. Ten pre-sowing seed treatments were applied on mature, even-sized seeds namely-control; sandpaper rubbing; nail clipping; immersion in normal water (at room temperature: 24℃) for 24 hrs., 48 hrs. and 72 hrs.; immersion in hot water (80℃) for 1 minute; soaking in 10% dilute H₂SO₄; soaking in 10% HCl for 5 minutes; and sowing in propagator house. Seeds sown after sandpaper rubbing at the distal end revealed best performances by providing highest germination percent (66.7%), germination energy (30%), germination index (0.17), germination rate (0.0145), germination value (30%) and plant percent (66.7%) within shortest period (38 days). The treatment also produced most vigor seedlings with 20.9 cm shoot height, 15 node number, and largest leaves (11.1 cm×2.9 cm). Hence, it is recommended to adopt sandpaper rubbing method for maximum germination and quality seedlings.

• Journal of the Korean Wood Science and Technology
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• v.46 no.4
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• pp.402-414
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• 2018

Species identification of wood provides important information for archaeology, restoration of cultural assets, preventing illegal logging, and more. Wood species are usually identified based on their anatomical features with the use of a microscope. However, this method may not be able to distinguish between anatomically similar species or subspecies. To overcome this problem, wood species need to be identified at the molecular level using DNA sequencing. However, unlike living plant cells, wood is difficult to pulverize using a mortar, and DNA extraction from dried wood is challenging. To solve these problems, we propose a pretreatment method in which wood is pulverized using 60-grit sandpaper and hydrated with water for 2 days. Using this method, we were able to stably amplify the rpoB gene from the extracted DNA of Pinus rigida. In addition, sequence analysis of the rpoB gene revealed six single nucleotide polymorphisms (SNPs), which classified the rpoB sequences in the genus Pinus into five groups. Our data indicate that although these SNPs were not suitable for species identification, they can potentially be used to determine the origin of different wood subspecies or individual samples of wood.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 1997.11a
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• pp.91-94
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• 1997

Objective of this stuey was to find the corrdlation between emotiona changes and the parameters of HRV spectrum evoked by tactile stimualtion. Twenty-one subjects were useds and five different types of materials, dry cottn, wet cotton, paper, sandpaper, and vinyl were applied to the left hand of each subject as a tactile stimulation. The results showed that HF/LF(ratio of high to low frequency amplitude calculated from power spectrum of HRV) decreased as the subject experienced the unpleasant emotion caused by wet cotton and sandpaper. On the othr hand, when the subject experienced the comfort, HF/LF increased. It was concluded that the proprsed methods can be applied to evaluate the characteristic changes in the autonomic nervous system which regulates the human emotion in the psychological aspects.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.4
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• pp.303-307
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• 2007

This paper investigated the effect of the pad buffing process on the material removal characteristics and pad stabilization during silicon chemical mechanical polishing. The pads surface were controlled by the buffing process using a buffer made by the sandpaper. The buffing process is based on abrasive machining by using a high speed sandpaper. The controlled pad by the buffing process show less deformation deviation and stable material removal rate during the CMP process. In addition, the controlled pad ensure better uniformity of removal rate than comparative pads. As a result of monitoring, the controlled pad by the buffing process demonstrated constant and stable friction force signals from initial polishing stage. Therefore, the tufting process could control the pad surface to be uniform and improve the performance of the polishing pad.

• Journal of the Korean Geosynthetics Society
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• v.5 no.4
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• pp.27-33
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• 2006

Frictional properties between geostrip and sand paper interface were estimated considering soil particle size also the friction coefficients and angles were determined with normal stress. Three kinds of geostrips of design strength 50, 70, 100 KN/m were used and 5 sandpapers of P100, P220, P320, P400, P600 were used also. Shear strength between geostrip and sand paper interface with design strength showed big difference and this is due to the uniform surface pattern of each geostrip when contact to sandpaper without regard to design strength. Shear strength of geostrip was increased with design strength and geostrips/P100 sandpaper interface showed the biggest value. Finally, all of geostrips showed the decrease phenomena of post-peak strength and this is due to the abrasion of geostrip surface by shear test.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.1
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• pp.170-178
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• 2019

Recently, as the interest in energy savings has increased, there has been increasing use of LED lighting, which is an eco-friendly device that replaces high energy consuming fluorescent lamps and incandescent lamps. In the case of a high output LED, however, the life time is shortened due to deterioration caused by heat generation. As a solution to this problem, this paper evaluated the LED life extension effect by increasing the convective heat transfer coefficient of the heat sink surface for LED packaging. A roughing process was carried out using sandpaper and sand blasting. The changes in surface roughness and surface area after each surface treatment process were evaluated quantitatively and the convective heat transfer coefficient was measured. When sandblasting and sandpaper were used to roughen the aluminum surface, a higher convection heat transfer coefficient was obtained compared to the untreated case, and a high heat dissipation efficiency of 82.76% was obtained in the sandblast treatment. Therefore, it is expected that the application of heat dissipation to the heat sink will extend the lifetime of the LED significantly and economically by increasing the heat efficiency.

• Design & Manufacturing
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• v.11 no.2
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• pp.51-56
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• 2017

Nitinol, a shape memory alloy (SMA), is manufactured from titanium and nickel and it used in various fields such as electrical applications, micro sensors. It is also recommended as a material in medical for implant because it has excellent organic compatibility. Nitinol is intended to be inserted into the human body, products require a high-quality surface and low residual stress. To overcome this problems, explore electrolyte polishing (EP) is being explored that may be appropriate for use with nitinol. EP is a particularly useful machining method because, as a non contact machining method, it produces neither machining heat nor internal stress in the machined materials. Sandpaper polishing is also useful machining method because, as a contact machining method, it can easily good surface roughness in the machined materials. The electrolyte polishing (EP) process has an effect of improving the surface roughness as well as the film polishing process, but has a characteristic that the residual stress is hardly generated because the work hardened layer is not formed on the processed surface. The sandpaper polishing process has the effect of improving the surface roughness but the residual stress remains in the surface. We experimented with three conditions of polishing process. First condition is the conventional polishing. Second condition is the electrochemical polishing(EP). And Last condition is a mixing process with the conventional polishing and the EP. Surface roughness and residual stress of the nitinol before a polishing process were $0.474{\mu}mRa$, -45.38MPa. Surface roughness and residual stress of the nitinol after mixing process of the conventional polishing and the EP were $1.071{\mu}mRa$, -143.157MPa. Surface roughness and residual stress of the nitinol after conventional polishing were $0.385{\mu}mRa$ and -205.15MPa. Surface roughness and residual stress of sandpaper and EP nitinol were $1.071{\mu}mRa$, -143.157MPa. The result shows that the EP process is a residual stress free process that eliminates the residual stress on the surface while eliminating the deformed layer remaining on the surface through composite surface machining rather than single surface machining. The EP process can be used for biomaterials such as nitinol and be applied to polishing of wafers and various fields.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.46 no.6
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• pp.94-102
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• 2014

The physical and chemical properties of recycled fibers from mixed waste paper are more and more deteriorated because of unknown history of recycling times. In order to improve the mechanical properties of liner paper, the recycled fibers from wasted cotton clothes were used in papermaking process, and their applicabilities were evaluated in several points of fiber modification. Thus, two kinds of fiberizing methods from waste cotton clothes were considered by using rotary sandpaper and grinder mill. Finally, the rotary sandpaper method was relatively desirable in preserving longer fiber length and fibrillated fiber surface. The recycled cotton fibers by swelling treatment with NaOH and bleaching with reductive chemicals were mixed with OCC fibers, and the handsheets were prepared to basis weight of $80g/m^2$ and evaluated the mechanical properties of paper. The fibrous properties showed outstanding results in freeness and WRV improvements by alkali treatment and high brightness by reductive bleaching treatment. The physical and mechanical properties of sheet by mixing OCC fibers and recycled cotton fibers were also highly improved in tensile, burst strength and specially folding resistance.

• Proceedings of the Korean Society of Postharvest Science and Technology of Agricultural Products Conference
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• 2003.10a
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• pp.145.1-145
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• 2003

신선편이 최소가공 근채류의 초기 품질 유지 및 유통기간의 연장을 위한 기초연구로 박피처리 조건별에 따른 품질특성을 조사하였다. 감자의 경우 sandpaper를 이용한 구근류 박피기로 박피된 감자의 감모율이 8%이하로 가장 낮게 나타났으며, 화학적 방법에 의한 박피가 8.9~9.8% 수준으로 NaOH의 농도가 높아질수록 감모율이 높아 17% NaOH용액으로 처리한 박피 감자의 감모율이 가장 높게 나타났다. 박피후의 수분함량 변화는 수작업과 15% NaOH 8$0^{\circ}C$에서 2분간 침지 후 박피된 처리구에서 박피 3시간 후 급격하게 감소되었다. pH는 화학적 박피 처리구는 5.78~6.33으로 수작업 박피의 6.53~6.81과 기계적 박피 처리구의 5.89~6.61에 비해 비교적 낮게 나타났다. 갈변도는 8$0^{\circ}C$, 15%-NaOH에 2분간 침지 후 박피된 처리구는 0.87로서 수작업 박피 직후의 갈변도 0.19에 비해 무려 4.5배 가량 높게 나타났다. 한편, 박피처리한 고구마는 감자에 비하여 갈변이 적게 일어났으며 감모율도 비교적 낮아 sandpaper를 이용한 구근류 박피기로 처리된 고구마가 7.3% 수준으로 가장 낮은 감모율을 나타내었고 10$0^{\circ}C$, 10%-NaOH에서 1분간 침지하여 박피한 처리구가 13.6%로 가장 높은 감모율을 보였다. pH는 시간 경과에 따라 6.51~5.94 수준으로 낮아지는 경향을 보였으며, 갈변도는 박피도구를 이용한 수작업에 있어 박피 3시간 경과 후에도 0.98 수준으로 가장 낮게 나타났다.