• 공업화학
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• 제32권3호
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• pp.332-339
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• 2021

최근 화석 연료 고갈과 지구 온난화를 가속화하는 온실 가스 배출에 대한 우려로 온실 가스를 배출하지 않는 청정 에너지원인 수소 에너지 기술의 중요성이 강조되고 있다. 그 중 물을 전기분해하여 수소를 얻는 수전해 기술은 그린 수소 기술로 궁극적인 청정 미래 에너지 자원으로 주목받고 있다. 본 연구에서는 양이온 교환막 수전해(proton exchange membrane water electrolysis, PEMWE)의 셀 구성요소 중 하나인 확산층(porous transport layer, PTL)을 sandpaper를 이용한 표면 처리를 통하여 표면 특성을 제어하였으며, 이러한 표면 특성 개선을 통하여 과전압을 줄이고 성능과 안정성을 높이기 위한 연구를 진행하였다. Sandpaper 400, 180, 100방을 준비하여 PTL 표면을 sanding하여 처리하였으며, 처리 후 1000방의 고른 sandpaper로 표면을 매끄럽게 처리하였다. 준비된 확산층은 물접촉각을 측정하여 친수성 정도를 분석하였으며, SEM 분석을 통하여 표면 형태를 관찰하였다. 전기화학적 특성 분석을 위하여 I-V 성능곡선, 임피던스 측정을 진행하여 성능 개선 여부를 확인하였다.

• Journal of Forest and Environmental Science
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• 제35권4호
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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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• 제46권4호
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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.

• 한국감성과학회:학술대회논문집
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• 한국감성과학회 1997년도 한국감성과학회 연차학술대회논문집
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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.

• 한국전기전자재료학회논문지
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• 제20권4호
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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.

• 한국지반신소재학회논문집
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• 제5권4호
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• pp.27-33
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• 2006

흙 입자의 크기를 고려한 5종류의 샌드페이퍼를 사용하여 지오스트립/샌드페이퍼 계면에서의 마찰특성을 평가하였으며, 전단력에 의한 마찰계수와 마찰각 등을 구하였다. 설계강도가 각각 50, 70, 100KN/m인 3종류의 지오스트립이 사용되었으며, 입자 크기가 각각 P100, 220, 320, 400, 600인 5종류의 샌드페이퍼가 사용되었다. 지오스트립의 설계강도에 따라 전단강도는 큰 차이를 나타내지 않았으며, 이는 전단 시 접촉되는 지오스트립 표면이 강도에 따라 차이가 나지 않고 비슷하기 때문이다. 샌드페이퍼의 입자의 크기가 클수록 더 큰 전단강도 값을 나타내었으며, 지오스트립/P100 계면에서 가장 큰 값을 나타내었다. 끝으로 모든 시료의 경우 post-peak 강도 감소 현상이 나타났으며, 이는 전단 시험에 의한 지오스트립 표면 의 마모에 기인한다.

• 한국산학기술학회논문지
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• 제20권1호
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• pp.170-178
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• 2019

최근 에너지 절감에 대한 관심도가 높아짐에 따라 에너지 소비가 높은 형광등과 백열등을 대체하는 친환경소재인 LED의 조명을 활용하는 움직임이 활발하다. 그러나, 고출력 LED의 경우 발열에 의한 열화현상 때문에 수명이 단축되는 현상이 발생하게 된다. 이에 대한, 해결방안으로 본 논문은 LED Packing중 방열판표면의 거칠기 처리를 통하여 열전달 계수를 증대시킴으로서 LED 수명연장 효과를 평가하였다. 거칠기 공정은 사포 및 샌드블라스트를 이용하여 진행하였다. 각 표면처리 공정에 따른 거칠기 및 표면적 변화를 정량적으로 평가하였으며, 열전달 계수를 측정하였다. 샌드블라스트, 사포를 이용하여 알루미늄 표면에 거칠기처리를 진행했을 경우 미 처리 시 보다 높은 대류 열전달 계수를 얻을 수 있었고, 샌드블라스트 처리 시 약 82.76%의 높은 방열 효율 향상을 얻을 수 있어, 이를 방열판에 적용할 시 큰 경제적 부담 없이 기존대비 더 높은 방열효율 증대를 통해 LED 수명을 대폭 연장 시킬 것으로 기대된다.

• Design & Manufacturing
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• 제11권2호
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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.

• 펄프종이기술
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• 제46권6호
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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.

• 한국식품저장유통학회:학술대회논문집
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• 한국식품저장유통학회 2003년도 제23차 추계총회 및 국제학술심포지움
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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.