• 펄프종이기술
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• 제30권3호
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• pp.38-45
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• 1998

Soil and water contamination caused by the abundant use of agricultural chemicals including herbicides and fertilizers draws public concerns since these chemicals may pollute the agricultural lands as well as the food products grown on these lands. As a method to reduce the use of agricultural chemicals mulching with thin plastic film has been commonly practised for many years. Although use of the plastic film for mulching is very effective in preventing the growth of weed, it is almost impossible to remove all of the plastic film from the agricultural land and the remaining film eventually contaminates the soils. Therefore, it is very imperative to develop a mulching material that decomposes completely to prevent soil pollution problems and to enhance the competitive edge of domestic agriculture. Mulch papers are believed to have many positive characteristics in preventing problems caused by the plastic mulch film since it decomposes completely after use. However, the basis weight of mulch papers needs to be reduced to improve its handling properties and to reduce the raw material costs of pulps. In this paper the possibilities of using domestic old corrugated containers in producing mulch papers were examined. Also use of unbleached softwood kraft pulps and dry strength additives were exploited along with two-layered sheet forming technology in decreasing the basis weight of the mulch paper. Results showed that reduction of 20g/$m^2$ of basis weight of mulch paper was possible by the appropriate raw material selection and application of strength resin. To use the mulch papers in paddy fields, however, further research to improve its durability should be pursued.

• 한국정보과학회:학술대회논문집
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• 한국정보과학회 2012년도 한국컴퓨터종합학술대회논문집 Vol.39 No.1(A)
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• pp.98-100
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• 2012

모바일 웜의 전파 속도는 시간이 지날수록 급격히 빨라진다. 급속도로 전파하는 웜을 억제하기 위한 연구가 계속 진행되어 왔다. 기존 연구 중 하나로 소셜 네트워크를 그래프(Graph)로 표현하고 분할한 뒤 각 파티션의 대표노드(Key Node)를 선택해 웜 패치를 전파하는 기법이 있다. 이 기법은 패치 전파 속도를 웜 전파 속도보다 빠르게 해서 웜을 억제 시킨다. 하지만 이 기법에서는 대표노드에 가중치(Weight)가 낮은 간선(Edge)이 연결 될 수 있거나 대표노드가 없는 파티션이 생길 수 있다. 잘못된 대표노드 선정은 패치 전파속도를 저하시키고 웜 억제를 지연시킬 수 있다. 본 논문에서는 페이지랭크를 이용해서 대표노드를 선정하는 개선된 소셜 네트워크 기반의 웜 패칭 기법을 제안한다. 제안 기법은 웜 패칭 전략에 사용할 수 있도록 수정한 페이지랭크를 각 파티션에 적용해서 대표노드를 선정한다. 파티션마다 전파 능력이 가장 높은 노드가 대표노드로 선정되기 때문에 웜 패치 전파 속도를 향상시킬 수 있다.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2012년도 춘계학술대회
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• pp.623-625
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• 2012

가우시안 잡음에 의해 훼손된 영상의 복원은 영상처리분야에서 가장 중요한 과제이다. 가우시안 잡음을 제거하기 위해, 가우시안 필터, 평균 필터, 가중치 필터 등 다양한 방법들이 제안되었다. 그러나 기존의 방법들은 잡음제거 및 에지 보존성능이 미흡하다. 따라서 본 논문에서는 효과적으로 잡음을 제거하기 위해, 마스크내의 각 화소들의 공간 거리와 추정된 잡음분산 등을 고려한 적응 가중치 필터를 제안하였다. 그리고 시뮬레이션을 통해 기존의 방법들과 그 성능을 비교하였고, 판단기준으로 MSE(mean squared error)를 사용하였다.

• Corrosion Science and Technology
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• 제19권5호
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• pp.239-249
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• 2020

The characteristics of cavitation-erosion damage with changes in the amplitude of 5052-O aluminum alloy for ships were investigated in a seawater environment. In the cavitation-erosion experiment, the cavitation environment was created using a vibration-generating device with a piezo-electric effect. The amplitudes of 5 ㎛, 10 ㎛, and 30 ㎛ were created by changing the geometric shape of the cavitation horn. The resistance characteristics of cavitation-erosion damage were evaluated by weight loss and pitting area. The damaged surface was analyzed using scanning electron microscopy (SEM) and 3D optical microscopy. As the amplitude increased, the amount of damage and the area of the damaged surface increased, and the damage was concentrated at the center and edge of the specimen. The pit was created after the initial incubation period with increasing experimental time, and then the pits were merged to grow and propagate into craters, and eventually, the surface was detached and damaged. The cavitation-erosion damage after 30 minutes with amplitude of 10 ㎛ and 30 ㎛ was 1.48 and 2.21 times compared to 5 ㎛, respectively.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권4호
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• pp.1760-1778
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• 2018

For image segmentation with intensity inhomogeneity, many region-based level set methods have been proposed. Some of them however can't get the relatively ideal segmentation results under the severe intensity inhomogeneity and weak edges, and without use of the image gradient information. To improve that, we propose a new level set method combined with local direction gradient in this paper. Firstly, based on two assumptions on intensity inhomogeneity to images, the relationships between segmentation objects and image gradients to local minimum and maximum around a pixel are presented, from which a new pixel classification method based on weight of Euclidian distance is introduced. Secondly, to implement the model, variational level set method combined with image spatial neighborhood information is used, which enhances the anti-noise capacity of the proposed gradient information based model. Thirdly, a new diffusion process with an edge indicator function is incorporated into the level set function to classify the pixels in homogeneous regions of the same segmentation object, and also to make the proposed method more insensitive to initial contours and stable numerical implementation. To verify our proposed method, different testing images including synthetic images, magnetic resonance imaging (MRI) and real-world images are introduced. The image segmentation results demonstrate that our method can deal with the relatively severe intensity inhomogeneity and obtain the comparatively ideal segmentation results efficiently.

• Geomechanics and Engineering
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• 제12권5호
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• pp.785-801
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• 2017

Biopolymer treatment of geomaterials to develop sustainable geotechnical systems is an important step towards the reduction of global warming. The cutting edge technology of biopolymer treatment is not only environment friendly but also has widespread application. This paper presents the strength and slake durability characteristics of biopolymer-treated sand sampled from Al-Sharqia Desert in Oman. The specimens were prepared by mixing sand at various proportions by weight of xanthan gum biopolymer. To make a comparison with conventional methods of ground improvement, cement treated sand specimens were also prepared. To demonstrate the effects of wetting and drying, standard slake durability tests were also conducted on the specimens. According to the results of strength tests, xanthan gum treatment increased the unconfined strength of sand, similar to the strengthening effect of mixing cement in sand. The slake durability test results indicated that the resistance of biopolymer-treated sand to disintegration upon interaction with water is stronger than that of cement treated sand. The percentage of xanthan gum to treat sand is proposed as 2-3% for optimal performance in terms of strength and durability. SEM analysis of biopolymer-treated sand specimens also confirms that the sand particles are linked through the biopolymer, which has increased shear resistance and durability. Results of this study imply xanthan gum biopolymer treatment as an eco-friendly technique to improve the mechanical properties of desert sand. However, the strengthening effect due to the biopolymer treatment of sand can be weakened upon interaction with water.

• 한국작물학회지
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• 제47권5호
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• pp.368-373
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• 2002

The strip intercropping system has used due to many advantages. Many researches supported these crop systems are usually equal to or better than monoculture crop systems in both total production and profit. There was no research to examine the important ecological factors in the competition between crops. A strip intercropping system composed of adjacent narrow strips of corn, soybean, and oat/legumes has been investigated in Iowa, USA. This study conducted to investigate why and how the differences in soybean yield are produced and affected by light, one of the microclimate, of the strip intercropping system. In height, the two rows of soybean closest to corn were taller than the two rows near the then-empty oat strip. The height of each crop decreased as the amount of light received increased. Weight of plant parts was lowest in row 1, nearest corn, and highest in row 4, next to the vacant oat strip. Daily photon flux density(PFD) increased with increasing distance from corn, with the highest value occurring on the edge next to the empty oat strip. Analyses of the relationship between light and biomass of soybean showed that all biomass measurements had a positive relationship to total PFD per day except height.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2011년도 추계학술발표대회
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• pp.19.2-19.2
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• 2011

The $(Sr_{0.75},\;La_{0.25})TiO_3$ (SLTO) ultra-thin films with various thicknesses have been grown on Ti-O terminated $SrTiO_3$(100) substrate using Laser-Molecular Beam Epitaxy (Laser MBE). By monitoring the in-situ specular spot intensity oscillation of reflection high energy electron diffraction (RHEED), we controlled the layer-by-layer film growth. The film structure and topography were verified by atomic force microscopy (AFM) and high resolution thin film x-ray diffraction by the synchrotron x-ray radiation. We have also investigated the electronic band structure using x-ray absorption spectroscopy (XAS). The ultra thin SLTO film exhibits thickness driven metal-insulator transition around 8 unit cell thickness when the film thickness progressively reduced to 2 unit cell. The SLTO thin films with an insulating character showed band splitting in Ti $L_3-L_2$ edge XAS spectrum which is attributed to Ti 3d band splitting. This narrow d band splitting could drive the metal-insulator transition along with Anderson Localization. In optical conductivity, we have found the spectral weight transfer from coherent part to incoherent part when the film thickness was reduced. This result indicates the possibility of enhanced electron correlation in ultra thin films.

• 한국정보과학회논문지:시스템및이론
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• 제34권5_6호
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• pp.195-201
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• 2007

트리의 최소단말경로분할이란 트리를 에지가 서로 소인 단말 노드 간 경로들로 분할하되, 가장 긴 경로의 길이를 최소화하는 문제이다. 본 논문에서는 트리의 최소단말경로분할을 $O({\mid}V{\mid}^2$시간에 구하는 알고리즘을 제시한다. 이 알고리즘은 주어진 최적화 문제를 이에 대응하는 결정 문제, 즉 최소단말경로 분할의 비용이 l 이하인지를 결정하는 문제를 이용한 이진 탐색으로 환원한다. 결정 문제는 트리를 한 차례 순회하는 동안 동적 계획법에 의해 해결된다

• 정보처리학회논문지:소프트웨어 및 데이터공학
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• 제6권6호
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• pp.285-292
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• 2017

전장공간은 다양한 무기체계가 유기적으로 활용되고 있으며, 자원의 성능 및 통신환경이 제약되고 환경의 가변성이 높은 특징이 있다. 이러한 전장환경에서 운용되는 자원의 접근성과 통합성의 한계를 극복하고 유연한 조합을 통해 임무를 수행할 수 있는 방안으로 서비스 지향 구조 기반의 기술을 접목시키는 연구들이 진행되고 있다. 본 연구에서는 지휘관이 전장 환경에서 임무에 필요한 다양한 SW를 서비스 기반으로 운용하기 위해 서비스 기반의 임무 계획 및 수행을 지원하는 계층형 임무서비스 모델을 제안한다. 또한 워크플로우 기술과 시맨틱 능력기반 추천을 활용한 개발도구를 구현하고 전투 임무 시나리오에 적용하여 실효성을 보이고자 한다.