• Journal of the Korean Vacuum Society
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• v.15 no.1
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• pp.97-102
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• 2006

Anodic alumina with self-organized and ordered nano hole arrays can be a good candidate of an irradiation mask to modify the properties of nano-scale region. In order to try using porous anodic alumina as a mask for ion-beam patterning, ion beam transmittance of anodic alumina was tested. 4 Um thick self-standing AAO templates anodized from Al bulk foil with two different aspect ratio, 200:1 and 100:1, were aligned about incident ion beam with finely controllable goniometer. At the best alignment, the transmittance of the AAO with aspect ratio of 200:1 and 100:1 were $10^{-8}\;and\;10^{-4}$, respectively. However transmittance of the thin film AAO with low aspect ratio, 5:1, were remarkably improved to 0.67. The ion beam transmittance of self-standing porous alumina with a thickness larger than $4{\mu}m$ is extremely low owing to high aspect ratio of nano hole and charging effect, even at a precise beam alignment to the direction of nano hole. $SiO_2$ nano dot array was formed by ion irradiation into thin film AAO on $SiO_2$ film. This was confirmed by scanning electron microscopy that the $SiO_2$ nano dot array is similar to AAO hole array.

• Publications of The Korean Astronomical Society
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• v.12 no.1
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• pp.111-143
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• 1997

We have developed a spherical FCT code in order to simulate the interaction of supernova remnants with stellar wind bubbles. We assume that the density profile of the supernova ejecta follows the Chevalier mode1(1982) where the outer portion has a power-law density distribution($\rho{\propto}\gamma^{-n}$) and the SN ejecta has a kinetic energy of $10^{51}$ ergs. The structure of wind bubble has been calculated with the stellar mass loss rate $\dot{M}=5\times10^{-6}M_{\odot}/yr$ and the wind velocity $\upsilon=2\times10^3$ km/s We have simulated seven models with different initial conditions In the first two models we computed the evolution of SNRs with n=7 and n=14 in the uniform medium The numerical results agree with the Chevalier's similarity solution at early times. When all of the power-law portion of the ejecta is swept up by the reverse shock, the evolution slowly converges to the Sedov-Taylor stage. There is not much difference between the two cases with different n's The other five models simulate SNRs produced inside wind bubbles. In model III, we consider the SN ejecta of 1.4 $M_{\odot}$ and the radius of bubble ~2.76 pc so that ratio of the mass $\alpha(=M_{W.S}/M_{ej}$ is 2. We follow the complex hydrodynamic flows produced by the interaction of SN shocks with stellar shocks and with the contact discontinuities, In the model III, the time scale for the SN shock to cross the wind shell $\tau_{cross}$ is similar to the time scale for the reverse shock to sweep the power-law density profile $\tau_{bend}$. Hence the SN shock crosses the wind shell. At late times SN shock produces another shell in the ambient medium so that we have a SNR with double shell structure. From the numerical results of the remaining models, we have found that when $\tau_{cross}/\tau_{bend}\leq2$, or equivalently when $\alpha\leq50$, the SNRs produced inside wind bubbles have double shell structure. Otherwise, either the SN shock does not cross the wind shell or even if it crosses at one time, the reverse shock reflected at the center accelerates the wind shell to merge into the SN shock Our results confirm the conclusion of Tenorio-Tagle et a1(1990).

• International Journal of Highway Engineering
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• v.12 no.4
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• pp.39-46
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• 2010

In 2007, Iowa department of transportation (DOT) initiated to run the falling weight deflectometer (FWD) network-level testing along Iowa highway and road systems and to build a comprehensive database of deflection data and subsequent structural analysis, which are used for detecting pavement structure failure, estimating expected life, and calculating overlay requirements over a desired design life. Iowa's current FWD networklevel testing protocol requires that pavements are tested at three-drop level with 8-deflection basin collected at each drop level. The test point is determined by the length of the tested pavement section. However, the current FWD network-level program could cover about 20% of Iowa's highway and road systems annually. Therefore, the current FWD network-level test protocol should be simplified to test more than 20% of Iowa's highway and road systems for the network-level test annually. The main objective of this research is to investigate if the minimum number of drop levels and test points could be reduced to increase the testing production rate and reduce the cost of testing and traffic control without sacrificing the quality of the FWD data. Based upon the limited FWD network-level test data of eighty-three composite pavement sections, there was no significant difference between the mean values of three different response parameters when the number of drop levels and test points were reduced from the current FWD network-level testing protocol. As a result, the production rate of FWD tests would increase and the cost of testing and traffic control would be decreased without sacrificing the quality of the FWD data.

• Journal of the Korean Graphic Arts Communication Society
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• v.31 no.1
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• pp.39-49
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• 2013

Nowadays the printing market has shift from 2D(two dimension) industry to 3D(three dimension) industry, along with IT. With rapidly changing market, it's true that the effort to develop the printing materials and upgrade the printing qualities is produced actively in the country. Particularly, the differences in printing materials can often determine the quality of printings in the printability. In the case of the printability of offset, 9 items(paper, ink, order of printing, ink supply, blowing-up halftone, grey balance, key color(base color), overlap efficiency, quality at the halftone dot reproduction etc.) are usually considered as the important factors and used to estimate the printability at abroad. However, in domestic, ink-jet paper is not used for the printing/publishing by ink-jet printing for digital, but done mainly for offset printing. Because the paper of gloss coated type, which is the ink-jet paper, has high price, it's too hard to manufacture massively printing/publishing. Also, in the case of the paper of uncoated type, in spite of its reasonable price rather than the former, the type of uncoated one also has demerit that the ink-jet paper has a clear difference between the front and the back. Therefore, it's tough reality that Ink Jet paper is hardly taken advantage of as the printing/publishing. Thus, what is done in the first to print and/or publish on ink-jet paper is that the front and the back must be printed evenly, and appropriate to the printability of ink-jet. Although there're some kinds of ink-jet paper in the country, it has not been produced in true domestic production yet. In addition, thanks to the brightness of fluorescence brightening agent, the foreign product can offer the good-qualified one-time printing. But when it comes to the printing/publishing, there're difficulties that it may cause the Ocular Fatigue because of long-term exposure of the eyes to text. This research tries to find out the optimum ink-jet paper in domestic for the printing/publishing by studying on the printability of ink-jet on digital web-printing. And it also tries to look for the paper's brightness which can be reduce the possibility to cause the consumers' Ocular Fatigue.

• Journal of Korean Society for Geospatial Information Science
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• v.4 no.2 s.8
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• pp.55-61
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• 1996

The objective of this paper is to show an optimal design model for branched water supply system which also can find the optimal location of pumping stations using linear programming. GIS is utilized in this model to better handle the data and the results front the optimization. The developed model considers hydraulic influences of some appurtenances such as supply tunnels and a filtration plant The model also considers tunnel construction cost which should be treated differently from pipe construction cost Different from other models presently available, the model guarantees a nonnegative pressure at every junction node in the system. The objective function includes annual operation cost (electricity rate) ill addition to initial construction cost, thus producing a more reasonable decision. The model selects the optimal diameter not in the form of continuous number but in the form of commercial discrete diameter (pipe size) using the pipe lengths as decision variables instead of pipe diameters. The model not only determines the optimal pumping head for each pumping station but also finds the optimal location and number of pumping stations. GIS is used to handle hydraulic and budgetary data automatically and to visualize the results for the of optimal design of the system. The model has been applied to an existing water supply system. 'The results show that the optimization model with the aid of GIS is helpful in the decision-nulling process for the design of more economical systems, and can be dot into practice successfully.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.154-155
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• 2010

최근 Stranski-Krastanov (SK) 성장법을 이용한 자발형성 (Self-assembled) InAs/GaAs 양자점 (Quantum Dot) 연구가 기초 물리학뿐만 아니라 응용에 있어 활발하게 진행되고 있다. 그러나 기존 보고에 따르면 SK 성장법을 통한 InAs/GaAs 양자점은 크기, 균일도, 및 밀도 등의 성장거동 제어에 한계가 있다. 예로, 성장속도 및 증착양이 감소하더라도 상대적으로 크기가 큰 InAs/GaAs 클러스터 (Cluster)를 형성하여 크기분포의 불균일 및 결함을 야기하여 결과적으로 전기/광학적 특성을 저해하는 요인이 된다. 이를 개선하기 위한 방안으로 SK 성장법을 변형한 다양한 수정자발형성법이 제안되어 연구되고 있다. 본 논문에서는 기존 SK 성장법과 Arsenic-interruption Technique(AIT), In Pre-deposition (IPD)법을 각각 접목한 수정자발형성법을 이용하여 상대적으로 크기가 큰 InAs/GaAs 양자점 또는 클러스터 형성을 감소시켜 공간적 크기 균일도 및 밀도를 제어한 결과를 보고한다. 성장된 InAs/GaAs 양자점 시료의 구조 및 광학적 특성을 원자력간현미경 (Artomic Force Microscopy, AFM)과 Photoluminescence (PL) 분광법을 이용하여 분석하였다. 기존 SK 성장법을 이용하여 형성한 기준시료의 AFM 이미지에서 InAs/GaAs 양자점과 클러스터의 공간밀도는 각각 6.4*1010/cm2와 1.4*109/cm2로 관찰되었다. 그러나, AIT를 이용한 양자점 시료의 경우 상대적으로 크기가 큰 InAs/GaAs 클러스터는 관찰되어지지 않았고, 양자점 밀도는 8.4*1010/cm2로 SK 양자점에 비하여 30% 정도 개선되었다. 또한, InAs/GaAs 클러스터를 제외한 공간 균일도는 SK-InAs/GaAs 양자점의 15.6%에 비하여 8%로 크게 개선된 결과를 얻었다. AIT 성장법을 이용한 InAs/GaAs 양자점에서 원자의 이동거리 (Migration Length)의 제어로 양자점의 형성특성이 개선된 것으로 설명할 수 있으며, Arsenic 차단 시간이 임계점 이상으로 길어지면 다시 InAs/GaAs 클러스터들이 형성되는 것을 관찰할 수 있었다. InAs/GaAs 양자점과 클러스터 형성 특성이 초기 표면 조건에 어떻게 영향을 받는지 분석하기 위해, InAs 양자점 성장 이전에 V족 물질 공급 없이 Indium의 공급시간을 1초(IPDT1S 시료), 2초 (IPDT2S 시료), 3초 (IPDT1S 시료)로 변화시키면서 증착하고 기존 SK 성장법으로 양자점을 성장하였다 (IPD성장법). 그 결과 IDP1S 양자점 시료의 공간밀도가 10*1010/cm2로 SK InAs/GaAs 양자점 시료에 비해 약 60% 정도 증가하였고, 클러스터도 관찰 할 수 없었다. 그러나 IPD 시간이 증가할수록 다시 InAs/GaAs 클러스터들이 형성되는 것을 관찰할 수 있었다. 이러한 결과는 InAs/GaAs 양자점 성장초기에 InAs 핵생성 사이트 (Nucleation site)의 크기 및 상태를 제어하는 것이 양자점의 밀도 및 균일도를 제어하는 중요한 요소임을 알 수 있다.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.2
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• pp.185-192
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• 2010

The objective of this study was to investigate the effectiveness of stabilization for army firing range soil highly contaminated with Pb (total Pb: 29,000 mg/kg) using calcined waste oyster shells. The calcination was conducted to activate quicklime from calcite. In order to evaluate the effectiveness of calcination, both natural oyster shells (NOS) and calcined oyster shells (COS) were applied to the Pb contaminated soil. Stabilization was conducted by mixing the contaminated soil with oyster shell media at 5-20 wt% and cured for 28 days. Following 28 days of curing, Pb leachability was measured based on the Korean Standard Test method (0.1 N HCl extraction). The treatment results showed that the COS treatment outperformed the NOS treatment. All of the NOS treatments failed to meet the Korean warning standard of 100 mg/kg. However, the Pb concentrations were significantly reduced to 47 mg/kg and 3 mg/kg upon 15 wt% and 20 wt% COS treatments, respectively which passed the Korean warning standard. Moreover, -#20 mesh materials were more effective than the -#10 mesh materials in effectively reducing Pb leachability. The scanning electron microscopy (SEM)-energy dispersive X-ray spectroscopy (EDX) results indicated that Pb immobilization was strongly linked to Al and Si.

• Journal of the Korean Society of Radiology
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• v.83 no.3
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• pp.538-558
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• 2022

The perivascular space (PVS) of the brain, also known as Virchow-Robin space, consists of cerebrospinal fluid and connective tissues bordered by astrocyte endfeet. The PVS, in a word, is the route over the arterioles, capillaries, and venules where the substances can move. Although the PVS was identified and described first in the literature approximately over 150 years ago, its importance has been highlighted recently after the function of the waste clearing system of the interstitial fluid and wastes was revealed. The PVS is known to be a microscopic structure detected using T2-weighted brain MRI as dot-like hyperintensity lesions when enlarged. Although until recently regarded as normal with no clinical consequence and ignored in many circumstances, several studies have argued the association of an enlarged PVS with neurodegenerative or other diseases. Many questions and unknown facts about this structure still exist; we can only assume that the normal PVS functions are crucial in keeping the brain healthy. In this review, we covered the history, anatomy, pathophysiology, and MRI findings of the PVS; finally, we briefly touched upon the recent trials to better visualize the PVS by providing a glimpse of the brain fluid dynamics and clinical importance of the PVS.

• Journal of Science and Technology Studies
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• v.6 no.1 s.11
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• pp.31-52
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• 2006

This paper aims to analyze the rise and decline of Seattle Community Network(briefly SCN), an electronic community network based upon Seattle, U.S. from the perspective of 'social shaping of technology' theory rather than that of technological determinism That is, this paper focuses on the social processes of the evolution of SCN. And this paper considers SCN as one important element of the 'network society', a concept manufactured by Manuel Castells. SCN was built successfully over 10 years ago by some progressive local activists and volunteers. The main purpose of building SCN at that time was said to make local community stronger with the help of advanced information technology. This can be understood that the founders of SCN tried to shape the direction of network society development based on civil society's values including public access and commitment to democracy rather than those of private companies. After some years of successful working, however, SCN started to decline. The expansion of internet services and the booming of dot.com companies in the late 90's were the main factors that made SCN decline. In conclusion, it can be said that the socia-economic factors rather than technological factors gave birth to the rise and decline of SCN.

• The Journal of the Korea Contents Association
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• v.12 no.5
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• pp.52-61
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• 2012

Text visualization is one of sectors in data visualization. This study is on methods to visually represent text's contents, structure, and form aspects based on various analytic techniques about wide range of text data. In this study -as a text visualization study-, 1) a method to find out the characteristics of a book's genre using words in the text of the book was looked into, 2) elements of visualization of a book's genre based on verification through an experiment were drew, and 3) the ways to intuitionally and efficiently visualize this were explained. According to visualization suggested by this study, first, actual genre of a book can be understood based on words used in the book. Second, with which genre is closed to the book can be found out with one glance through images of visualization. Moreover, the characteristics of complicated genres included in a book can be understood. Furthermore, the level of closeness (similarity) of a genre -which is found to be a representative genre using the number of dots, curvature of a curve, and brightness in the image- can be assumed. Finally, the outcome of this study can be used for a variety of fields including book customizing service such as a book recommendation system that provides images of personal preference books or genres through application of books favored by individual customers.