• Journal of Dental Anesthesia and Pain Medicine
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• 제17권3호
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• pp.191-198
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• 2017

Background: For peripheral nerve regeneration, recent attentions have been paid to the nerve conduits made by tissue-engineering technique. Three major elements of tissue-engineering are cells, molecules, and scaffolds. Method: In this study, the attachments of nerve cells, including Schwann cells, on the nerve conduit and the effects of both growth factor and adhesion molecule on these attachments were investigated. Results: The attachment of rapidly-proliferating cells, C6 cells and HS683 cells, on nerve conduit was better than that of slowly-proliferating cells, PC12 cells and Schwann cells, however, the treatment of nerve growth factor improved the attachment of slowly-proliferating cells. In addition, the attachment of Schwann cells on nerve conduit coated with fibronectin was as good as that of Schwann cells treated with glial cell line-derived neurotrophic factor (GDNF). Conclusion: Growth factor changes nerve cell morphology and affects cell cycle time. And nerve growth factor or fibronectin treatment is indispensable for Schwann cell to be used for implantation in artificial nerve conduits.

• Elastomers and Composites
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• 제44권2호
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• pp.98-105
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• 2009

내이의 달팽이관은 기저막(basilar membrane)과 유모세포(hair cells)라는 두 가지 중요한 요소로 이루어져 있다. 기저막은 귀로 들어오는 소리를 주파수에 따라 분리하는 기능을 가지고 있으며, 기저막 위에 있는 유모세포는 생체전기 신호를 발생시키는 기계적 감각 수용기관이다. 인간의 생체청각기구를 모사한 인공와우와 신개념의 인공감각기관을 개발하기 위해서, 본 논문에서는 ZnO 압전 나노필라를 사용하여 인공유모세포(artificial hair cell)를 구현할 수 있는 핵심 기반 기술인 생체모사 기술을 연구하였다. 그 구체적인 방법으로 ZnO 나노필라를 저온성장법으로 유연기판에, 고온성장법으로 실리콘 웨이퍼에 성장시켰다. 유연기판과 실리콘 웨이퍼 위에 ZnO 나노필라를 성장 전에 미리 패턴을 만들었고, 기판에 선택적으로 ZnO 나노필라를 성장시켰다. 또한 ZnO 나노필라의 동적 정적 거동을 이해하기 위해 다중 물리 해석기법을 사용하여 ZnO 나노필라의 electric potential, von Mises stress, 변형량 등을 분석하였다. 본 연구에서는 ZnO 나노필라를 제작 및 패터닝하는 기술과 최적화하는 다중 물리 해석기술을 이용하여 인공 유모세포를 구현하는 핵심기술을 개발하였다.

• Journal of electromagnetic engineering and science
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• 제13권2호
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• pp.113-119
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• 2013

We developed a transformed, symmetrical, mushroom-like surface without via holes in cells focused on a 2.4-GHz WLAN band. Each slot in the novel type structure plays a key role in modeling at the desired frequencies. The designed artificial magnetic conductor (AMC) has several advantages, including a small size, a wider bandwidth, a short reflecting distance to the antenna, and easy fabrication because there are no via holes. Overall dimensions of the AMC cell are 21 mm $(Width){\times}21mm$ $(Height){\times}2.6mm$ (Thickness), and the bandwidth is about three times wider (11.7%) compared to that of a conventional AMC (4.0%). For evaluating the performance of the proposed structure, a reflector, which periodically consists of the designed AMC cells, was developed. The antenna with the investigated AMC reflector not only works within a quarter of the wavelength because of the extremely high wave impedance generated by the AMC cells on the surface of the structure but also reduces the specific absorption rate (SAR). Electromagnetic field (EMF) exposure to a human phantom was analyzed by applying the designed reflector to the 2.4-GHz dipole antenna in a tablet PC. The calculated peak SAR averaged over 1 g was 0.125 W/kg when the input power was 1 W and the antenna was located at 20 cm from the human phantom. However, the SAR value was only 0.002 W/kg (i.e., 98.4% blocked) when the designed reflector was inserted in front of the antenna.

• 미생물학회지
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• 제43권1호
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• pp.40-46
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• 2007

생태계가 파괴된 파로호에 수초대를 복원하는 방법으로 rubberized coconut fiber를 식생기반재로 사용한 인공식물섬을 2003년 8월에 설치하였다. 인공식물섬 식생기반재에서는 식물이 자랄 수 있을 정도로 영양염이 농축되어 꽂창포(Iris ensata), 노랑 꽃창포(Iris pseudoacorus), 갈대(Phragmites communis)등 식재된 식물이 잘 자랐다. 이 과정에서 세균의 역할을 알아보기 위하여 2004년 4월부터 10월까지 2주 간격으로 총세균수, 활성세균수, ${\beta}-glucosidase$, phosphatase를 조사한 결과 인공식물성 식생기반재의 공극수에서 각각 평균 $28.6{\times}10^{6}\;cells/ml,\;22.7{\times}10^{6}\;cells/ml,\;452.9nM/L/hr,\;16381.9nM/L/hr$로 조사되어 파로호 호수물보다 각각 10배, 15배, 22배, 38배 높았다. 그리고 영양염류농도는 총인과 충질소가 식생기반재 공극수에서 각각평균 1.06 mg/L, 12.5 mg/L으로 조사되어 호수물보다 12배, 3배 높았다. 이 결과 인공식물섬 식생기반재에서 새로운 생태계가 만들어졌으며, 이 생태계에서 세균이 중요한 역할을 하여 빈-중영양상태의 호수물에서도 식물이 잘 자랄 수 있었다.

• 한국해양학회지:바다
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• 제3권4호
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• pp.271-275
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• 1998

해수에 잠긴 인공기질 표면에 부착한 박테리아가 규조류의 후속부착에 미치는 영향에 대해 상반된 견해가 있다. 그러나 자연조건의 해수에서 인공기질 표면에 먼저 부착한 해산 박테리아가 규조류의 후속부착에 어떤 영향을 주는지에 대해서는 아직 알려져 있지 않다. 따라서 본 연구에서는 해산 박테리아를 일정 시간별로 미리 부착시킨 여러 재질을 이용하여 실험하였다. 첫번째 실험에서는 유리 슬라이드에 미리 해산 박테리아를 0~133 시간별로 부착시키고 해수에 일정기간 노출시킨 후 규조류의 부착수도를 조사하였다. 규조류의 부착은 먼저 부착된 박테리아의 수도와 관련이 없었으며(p>0.05), 무처리 슬라이드에 가장 많은 수의 규조류가, 가장 높은 수도의 박테리아가 부착된 표면에는 가장 적은 수의 규조류가 부착하였다. 두번째 실험에서는 유리와 아크릴 슬라이드를 이용하여 해산 박테리아를 6 일 동안 먼저 부착시킨 것과 한천(agar)을 입힌 슬라이드 그리고 대조구로서 무처리 슬라이드를 해수 중에 함께 노출시켰다. 박테리아가 가장 높은 수도($5.4{\pm}0.02{\times}10^5\;cells\;cm^{-2}$)로 부착된 아크릴 슬라이드에서는 무처리 슬라이드보다 적은 수의 규조류가 부착하였으나, 박테리아가 $2.5{\pm}1.0{\times}10^5\;cells\;cm^{-2}$로 부착된 유리 슬라이드에서는 무처리 슬라이드와 차이가 없었다. 반면 점액질을 모사한 표면에 부착한 규조류의 수도와 이입계수는 다른 표면들에 비해 평균 2 배 이상 높게 나타났다. 따라서 해산 박테리아의 부착이 규조류 후속부착의 선결요건이 아닌 것으로 판단된다.

• 한국환경복원기술학회지
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• 제4권2호
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• pp.84-91
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• 2001

This study was carried out to develop the technology of artificial floating island for the wild-life habitat at the reservoir of Korea University farm near Seoul. After the execution of an artificial floating island with 6 cells(each $3{\times}3m$), each cell was planted with 5 different species and one mixed of them, to the reservoir in 1999 through 2000. The monitored results were as follows; 1. Typha orientalis, Zizania latifolia and Oenanthe japonica were died back, but Phragmites communis, Phragmites japonica and Juncus effusus var. decipiens were well growing. 2. The limits of sinking water depth of the planting foundation were different with the plant species, that is, 40cm to the Juncus effusus var. dicipiens and 50cm to Phragmites communis. Accordingly the water depth should be kept differently with each species. 3. 33 species of fauna were monitored in the first year(1999) and 43 species in the second (2000) increasingly. 4. For the more wild-lives inducing to the artificial floating island, establishing the eco-corridor from the surrounding environment was needed.

• 산업경영시스템학회지
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• 제39권2호
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• pp.46-53
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• 2016

In mobile communication systems, location management deals with the location determination of users in a network. One of the strategies used in location management is to partition the network into location areas. Each location area consists of a group of cells. The goal of location management is to partition the network into a number of location areas such that the total paging cost and handoff (or update) cost is a minimum. Finding the optimal number of location areas and the corresponding configuration of the partitioned network is a difficult combinatorial optimization problem. This cell grouping problem is to find a compromise between the location update and paging operations such that the cost of mobile terminal location tracking is a minimum in location area wireless network. In fact, this is shown to be an NP-complete problem in an earlier study. In this paper, artificial bee colony (ABC) is developed and proposed to obtain the best/optimal group of cells for location area planning for location management system. The performance of the artificial bee colony (ABC) is better than or similar to those of other population-based algorithms with the advantage of employing fewer control parameters. The important control parameter of ABC is only 'Limit' which is the number of trials after which a food source is assumed to be abandoned. Simulation results for 16, 36, and 64 cell grouping problems in wireless network show that the performance of our ABC is better than those alternatives such as ant colony optimization (ACO) and particle swarm optimization (PSO).

• 한국경영과학회지
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• 제31권4호
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• pp.69-87
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• 2006

This paper proposes an effective approach for the part-machine grouping(PMG) based on the non-binary part-machine incidence matrix in which real manufacturing factors such as the operation sequences with multiple visits to the same machine and production volumes of parts are incorporated and each entry represents actual moves due to different operation sequences. The proposed approach adopts Fuzzy ART neural network to quickly create the Initial part families and their machine cells. A new performance measure to evaluate and compare the goodness of non-binary block diagonal solution is suggested. To enhance the poor solution due to category proliferation inherent to most artificial neural networks, a supplementary procedure reassigning parts and machines is added. To show effectiveness of the proposed approach to large-size PMG problems, a psuedo-replicated clustering procedure is designed. Experimental results with intermediate to large-size data sets show effectiveness of the proposed approach.

• Journal of the Korean Physical Society
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• 제73권12호
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• pp.1908-1917
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• 2018

The binding affinity between the T-cell receptors (TCRs) and antigenic peptides mainly determines immunological recognition. It is not a trivial task that T cells identify the digital sequences of peptide amino acids by simply relying on the integrated binding affinity between TCRs and antigenic peptides. To address this problem, we examine whether the affinity-based discrimination of peptide sequences is learnable and generalizable by artificial neural networks (ANNs) that process the digital experimental amino acid sequence information of receptors and peptides. A pair of TCR and peptide sequences correspond to the input for ANNs, while the success or failure of the immunological recognition correspond to the output. The output is obtained by both theoretical model and experimental data. In either case, we confirmed that ANNs could learn the immunological recognition. We also found that a homogenized encoding of amino acid sequence was more effective for the supervised learning task.

• Advances in nano research
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• 제15권2호
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• pp.165-174
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• 2023

The study investigated the effect of geometric structures of nano-patterned surfaces, such as peak sharpness, height, width, aspect ratio, and spacing, on mechano-bactericidal properties. Here, in silico models were developed to explain surface interactions with Escherichia coli. Numerical solutions were performed based on the finite element method and verified by the artificial neural network method. An E. coli cell adhered to the nano surface formed elastic and creep deformation models, and the cells' maximum deformation, maximum stress, and maximum strain were calculated. The results determined that the increase in peak sharpness, aspect ratio, and spacing values increased the maximum deformation, maximum stress, and maximum strain on E. coli cell. In addition, the results showed that FEM and ANN methods were in good agreement with each other. This study proved that the geometrical structures of nano-patterned surfaces have an important role in the mechano-bactericidal effect.