• 한국정밀공학회지
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• 제27권7호
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• pp.49-54
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• 2010

The cryogenic ball milling was performed on carbon nanotubes (CNTs) at an extremely low temperature to increase the dispersion of CNTs. The effects of milling speed and time on the deagglomeration and structural changes of CNTs were studied. FESEM was used to analyze the dispersion and the change of particle size before and after milling process. Transmission electron microscopic (TEM) analysis was also investigated the effect of cryogenic ball milling on the morphological characteristics of CNTs. The structural changes by the cryogenic ball milling process were further confirmed by x-ray diffraction (XRD) and Raman spectroscopic analysis. The results showed that the agglomeration of CNTs was significantly reduced and amorphous structure was observed at high milling speed. However, the milling time has no great effect on the dispersion property and structural change of CNTs compared with milling speed.

• 지역연구
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• 제15권1호
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• pp.93-116
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• 1999

Recently the concept of learning has become very fashionable among academics from different economic disciplines. Economic geographers and spatial planners joined this fashion by increasingly speaking about the 'learning region'. This paper makes clear that this learning region'. This paper makes clear that this learning region concept has been launched from three angles; as spatial outcome of grand societal changes, as spatial concentration of entrepreneurial learning for innovation and as regional development concept. Despite the deficits and flaws such a young concept is faced with, such as vague definitions, the lack of empirical research and an insufficiently clear separation from existing concepts, the learning region concept might provide economic geography with more insight in agglomeration effects, stronger links with policy-making and more knowledge on path dependency and thus on unravelling the distinction between 'good' and 'bad' industrial agglomerations.

• 한국산업안전학회:학술대회논문집
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• 한국안전학회 1999년도 춘계 학술논문발표회 논문집
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• pp.229-233
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• 1999

일반적으로 가연성 분진의 최소착화에너지(Minimum Ignition Energy; MIE)를 측정하는 방법에는 Hartmann식(이하 재래식이라 칭한다)이 주로 이용되고 있다. 그러나, 재래식은 상당히 정확하게 측정할 수 있으나 착화 후 용기류의 청소, 실험장치의 조작성 등 실험에 어려움이 있으며, 또한, 압축공기계통의 필요 등으로 제조 가격이 상당히 고가이다. 따라서, 일본에서는 이러한 재래식의 단점을 보완하면서도 기존의 재래식보다 신뢰성이 크게 뒤떨어지지 않은 장치를 개발하고자, 신 개념의 진동형 분진 최소 착화 에너지 측정장치를 개발중에 있다. (중략)

• 한국산업안전학회:학술대회논문집
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• 한국안전학회 1998년도 추계 학술논문발표회 논문집
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• pp.179-182
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• 1998

It is widely recognized that conventional means for determining the minimum ignition energy(MIE) of powder are time-consuming and require operational skill. As a variety of new fine powders are being produced day by day in industry, there is an urgent need to a quicker and more economical means to measure MIE. To meet this requirement, we have developed a measurement system which employs a novel method to create an air/dust mixture in a miniature combustion box. In this system, the powder to be tested input into a hopper made of metal mesh, and successively fed downward to form a thin, curtain-like dust/air mixture by vibration. With this new apparatus, three type of powders -Lycopodium, Anthraquinone, and Polyacrylonitrile-were tested and the MIE data were compared with those taken with a conventional apparatus(the Hartmann tube). Two of them agreed satisfactory, but the other, anthraquinone, showed quite different values supposedly due to the agglomeration of the powder particles by static-charge.

• Macromolecular Research
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• 제9권6호
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• pp.297-302
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• 2001

Rice starch was incorporated into linear low density polyethylene (LLDPE) using a Brabender Plastic-Corder internal mixer at a temperature of 140$\^{C}$ and 40 rpm. The starch loading was varied from 0 to 30% with 5 intervals. Studies on brabender torque development, mechanical properties and water absorption were investigated. The starch loading did not influence the brabender torque significantly. With respect to mechanical properties; the tensile strength and elongation at break decrease with increasing starch loading. The Young's modulus also increases with the starch filling. Mechanical properties were deteriorated as the starch absorbed moisture. The rate of water absorption was dependent on the starch filling in the composites. The scanning electron microscope (SEM) analysis was performed for the tensile fracture surfaces and it revealed the starch agglomeration and a poor dispersion of starch in the LLDPE matrix.

• Steel and Composite Structures
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• 제34권2호
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• pp.289-297
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• 2020

In the present research post-buckling of a cut out plate reinforced through carbon nanotubes (CNTs) resting on an elastic foundation is studied. Material characteristics of CNTs are hypothesized to be altered within thickness orientation which are calculated according to Mori-Tanaka model. For modeling the system mathematically, first order shear deformation theory (FSDT) is applied and using energy procedure, the governing equations can be derived. With respect to Rayleigh-Ritz procedure as well as Newton-Raphson iterative scheme, the motion equations are solved and therefore, post-buckling behavior of structure will be tracked. Diverse parameters as well as their reactions on post-buckling paths focusing cut out measurement, CNT's volume fraction and agglomeration, dimension of plate and an elastic foundation are investigated. It is revealed that presence of a square cut out can affect negatively post-buckling behavior of structure. Moreover, adding nanocompsits in the matrix leads to enhancement of post-buckling response of system.

• 한국산학기술학회논문지
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• 제6권3호
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• pp.261-264
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• 2005

90nm급 게이트로 활용되는 폴리실리콘을 패턴화 하기 위해서 하드 마스크의 채용 등 신공정과 함께 폴리실리콘 자체의 평탄화가 필요하다. 본 연구는 70nm 두께의 LPCVD 폴리실리콘 게이트를 상정하여 열산화막 상부에 기판 전면을 폴리실리콘으로 만들고 쾌속열처리 온도를 달리해가며 40초가 열처리하여 이때의 표면조도의 변화를 광발산 주사전자현미경(FESEM)과 주사탐침현미경(AFM)으로 확인하였다. 폴리실리콘은 $700^{\circ}C\~1100^{\circ}C$ 온도범위에서 표면 응집효과에 의해 고온에서 표면조도가 급격히 증가하는 경향이 있었으며 $700^{\circ}C$-40sec 조건에서 최적 평탄화 효과가 가능하였다.

• 국토계획
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• 제53권6호
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• pp.5-18
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• 2018

While the zoning system has been developed based on the rationale of separated and specialized land uses to prevent negative externalities in the modern industrial era, the emergence of office-based new industries in the post-industrial era rather encourages mixed land uses to create agglomeration economies. This study aims to find historical basis to justify the reform of zoning system to promote both specialized and mixed land uses. When the zoning system was first introduced in Japanese colonial period by Chosun Planning Ordinance enacted in 1934, Special District within Manufacturing Area, and later within Residential, Commercial, and Mixed Areas respectively was institutionalized for specialized land uses, though it was not actually designated. When City Planning Law was enacted in 1962, Special District was substituted by Exclusive Areas (Exclusive Residential Area, Exclusive Manufacturing Area). Meanwhile Undesignated Area was designated for mixed land uses by Chosun Planning Ordinance, and later it was converted mostly into Mixed Area and partially into Green Area. Finally Mixed Area was substituted by Semi-Areas (Semi-Residential Area, Semi-Manufacturing Area) by City Planning Law in 1962. These demonstrate that Korean zoning system needs to revive the tradition that clearly promoted both specialized and mixed land uses.

• The Journal of Asian Finance, Economics and Business
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• 제8권9호
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• pp.113-119
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• 2021

With the increasing pressure of international competition, urban agglomeration cooperation and innovation had become an important means of regional economic development. This study analyzed the spatial characteristics of the Urban Cooperative Innovation Network in Guangdong-Hong Kong-Macao Greater Bay Area, found out the dynamic evolution law of innovation, provided suggestions for policy management departments, and effectively planned the industrial layout. According to the data of the State Intellectual Property Office of China, this study researched invention patents from 2005 to 2019. This paper constructed the urban cooperative innovation network, and took 11 cities in the bay area as the research objects, and used social network analysis to study the spatial structure and dynamic evolution of the urban innovation network. Every indicator reflected the urban cooperative innovation, but they all showed a certain decline in 2008-2010. And it is inferred that the innovation network space of each city will be "obvious fist advantages, significant spillover effect and weakening role of Hong Kong and Macao". This paper divided urban cooperative innovation of Guangdong-Hong Kong-Macao Greater Bay Area into three stages. Summing up the characteristics of each stage is helpful to recognize the changes of urban cooperative innovation and to do a good job in industrial layout planning.

• 지식경영연구
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• 제17권3호
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• pp.65-91
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• 2016

Although the success of industrial clusters largely depends on whether clustering firms can achieve economic performance, there has been less attention on investigating factors and conditions contributing to the performance enhancement for clustering small and medium-sized enterprises (SMEs). Along this vein, we adopt the theories of social capital and organizational learning as those success factors for clustering SMEs. This study thus aims at examining what effect social capital accrued in the relationships among actors within clusters has on firm performance of clustering SMEs and what role organizational learning plays in the linkage between social capital and firm performance. For the empirical analysis, we operationalized the variables and their measures to develop questionnaires through the theoretical reviews on literatures. As a sample of 227 clustering SMEs, our collected data was analyzed by hierarchical regression analysis. The results confirmed that a high level of social capital, represented by network, trust, and norm, has positive effect on firm performance of clustering SMEs. We also found that clustering firms presenting high organizational learning, represented by absorptive and transformative capability, achieve better performance than those placing less value on organizational learning. Furthermore the significant relationship between social capital and firm performance is mediated partially through organizational learning. These findings imply not only that the territorial agglomeration of industrial cluster does not guarantee the performance creation of clustering SMEs but that they need to develop social capital among various actors within clusters, facilitating their knowledge diffusion. In order to absorb and mobilize the shared knowledge and information into strategic resources, the firms should improve their capability associated with organizational learning. These expand our understanding on the importance of social capital and organizational learning for the performance enhancement of clustering firms. Differentiating from major studies addressing benefits and advantages of industrial cluster, this study based on the perspective of firm-internal business process contributes to the literature advancement. Strategic and policy implications of this study are discussed in detail.