• 전기학회논문지
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• 제62권5호
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• pp.657-662
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• 2013

A size-reduced high frequency mixer designed by adopting artificial dielectric substrate is described in this work. The artificial dielectric substrate is composed by stacking the lower substrate in which a lot of metalized via-holes exist, and upper substrate on which microstrip lines are realized. The effective dielectric constant increases due to the inserted lots of via-holes, and this may be applied to size-reduction of high frequency circuits. In this work, in order to present an application example of size-reduction for active high frequency circuits using the artificial dielectric substrate, a 8GHz single gate mixer is miniaturized and measured. It is described that the basic circuit elements for mixers such as hybrid, low pass filter, and matching networks can be replaced by the artificial dielectric substrate for size-reduction. The final mixer has 55% of size compared to the normal one. The measured average conversion gain is around 3dB which is almost similar result as the normal circuit.

• Bulletin of the Korean Chemical Society
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• 제25권12호
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• pp.1917-1923
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• 2004

Although the proteolytic activity of the Cu(II) complex of cyclen (Cyc) is greatly enhanced upon attachment to a cross-linked polystyrene (PS), the Cu(II)Cyc-containing PS derivatives reported previously hydrolyzed only a very limited number of proteins. The PS-based artificial metalloproteases can overcome thermal, mechanical, and chemical instabilities of natural proteases, but the narrow substrate selectivity of the artificial metalloproteases limits their industrial application. In the present study, artificial metalloproteases exhibiting broad substrate selectivity were synthesized by attaching Cu(II)Cyc to a PS derivative using linkers with various structures in an attempt to facilitate the interaction of various protein substrates with the PS surface. The new artificial metalloproteases hydrolyzed all of the four protein substrates (albumin, myoglobin, ${\gamma}$-globulin, and lysozyme) examined, manifesting $k_{cat}/K_m$ values of 28-1500 $h_{-1}M_{-1}$ at 50 $^{\circ}C$. The improvement in substrate selectivity is attributed to steric and/or polar interaction between the bound protein and the PS surface as well as the hydrophobicity of the microenvironment of the catalytic centers.

• 한국조경학회지
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• 제31권2호
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• pp.102-112
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• 2003

This study was carried out to research and develop a shallow green rooftop system which would require low maintenance and therefore could be used for existing rooftops. To achieve these goals, the conceptual model was induced by past studies and the experimental systems were deduced from the conceptual model. On the growth of Sedum sarmentosum grown in these rooftop systems, the effects of artificial substrate type, soil depth, and drainage type were investigated from 3 April to 11 October 2002. Artificial substrates were an alone type and a blending type. The alone type was an artificial substrate formulated by blending crushed porous glass with bark(v/v, 6:4). The blending type was formulated by blending the alone type with loam(v/v, 1:1). Soil depths were 5cm, loom, and 15cm. Drainage types were a reservoir-drainage type and a drainage type. The reservoir-drainage type could keep water and drain excessive water at the same time. The drainage type could drain excessive water but could not keep water. Covering area, total fresh and dry weight, visual quality, and water content per 1g dry matter were measured. All the variables were analyzed by correlation analysis and factor analysis. The results of the study are summarized as follows. The growth increment was higher in the blending type than in the alone type, the highest in loom soil depth and higher in the reservoir-drainage type than in the drainage type. The growth quality was higher in the blending type than in the alone type, the highest in l0cm soil depth, and higher in the drainage type than in the reservoir-drainage type. In consideration of the permissible load on the existing rooftops and the effects of the treatments on the growth increment and quality, the system should adopt the blending type in artificial substrate types, 5~10cm in soil depths, and the drainage type in drainage types. This system will be well-suited to the growth of Sedum sarmentosum, and when the artificial substrate was in field capacity, the weight will be 75~115kg/$m^2$.

• 생명과학회지
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• 제4권3호
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• pp.92-101
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• 1994

With the rapid development of bioorganic chemistry recently, a field of artificial enzymes has a great concern from the industrial point of view. A number of possibilities now exist ofr the construction of artificial enzymes. They must posses two structural entities, a substrate-binding site and a catalytically effective site. It has been found that producing the facility for substrate binding is relatively straightforward but catalytic sites are somewhat more difficult. Therefore, synthetic catalysts do not yet match all the properties of an enzyme, however, the design of catalysts has lead to very powerful effects. This article reviews the existing literature on the modeling of artificial enzymes using cyclodextrin, modified cyclodextrin and crown compounds.

• 한국산학기술학회논문지
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• 제12권7호
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• pp.3169-3175
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• 2011

본 논문에서는 가유전체 기판구조의 증가하는 유효 유전율 효과를 이용하여 방향성결합기를 소형화하여 설계하는 것에 대하여 기술한다. 방향성결합기는 RF 신호의 크기를 간접적으로 측정하거나 신호전력을 결합하는데 널리 사용되는 회로이다. 가유전체 기판구조는 다수의 도금된 비어홀에 의하여 표준형 기판보다 유효 유전율이 증가하는 특성을 지니는데, 이 특성이 바로 회로 소형화에 이용된다. 한 예로써 2GHz대에서 15dB의 결합계수를 갖는 방향성결합기가 표준형 기판과 가유전체 기판구조에 대하여 각각 설계되고 그 크기가 비교된다. 표준형 회로와 비교할 때, 가유전체 기판구조로 소형화된 방향성결합기는 동일한 성능을 유지하면서도 1/3로 줄어든 회로의 크기를 갖는다. 또한 소형화된 방향성결합기를 제작하여 측정한 성능은 예측 결과와도 매우 유사함을 보여준다. 측정한 성능 결과는 2GHz대에서 -14.62B의 결합도, -24.1dB의 정합도, -0.38dB의 삽입손실 특성을 보여준다.

• 한국환경복원기술학회지
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• 제13권2호
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• pp.52-62
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• 2010

This study was carried out in the Tropical Plant Resources Research Center of Korea National Arboretum to determine the optimum edaphic environment for the growth of tropical and subtropical plants. The physicochemical properties of artificial substrates and the growth characteristics of tropical and subtropical plants were investigated. Subtropical plants exhibited a high growth rate when cultivated in a substrate of Dry Zone that had physical properties similar to those of arid native soil. Mediterranean plants showed a low growth rate when grown in a substrate of Subtropical Zone that required changes in acidity. The substrate of Tropical Zone had high organic matter and mineral contents and therefore had good physical properties:this substrate has a good environment for the stimulation of the growth of tropical plants. Our results indicate that the chemical properties such as pH and mineral contents of most artificial substrates need to be more urgently improved than their physical properties in order to ensure better growth of tropical and subtropical plants. Initial management strategies for the construction of new tropical greenhouses were formulated, and data from monitoring studies will be continuously gathered and incorporated in the manual to keep it updated.

• 환경위생공학
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• 제16권3호
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• pp.22-27
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• 2001

It have been investigated how algal and bacterial symbiotic reaction influences on removal of organic carbon in river ecosystem. And artificial experimentation apparatus was made for algae'and bacteia'culture as lab scale. Investigating and researching minutely the change of concentration of organic carbon substrate and the change of population density of algae'and of bacteria'with this artificial experimentation apparatus, the next results could be obtained. 1. Successful decrease of DOC(dissolved organic carbon) could not be expected unless algal and bacterial biomass floe was nut formed effectively and unless biosorption was not proceeded effectively in the very culture system in which artificial synthetic wastewater was supplied continuously at constant rate. 2. In conditions of culture liquid of 1335 glucnse mg/L(type 1) and of 267 glucose mg:L(type 2), the algal dominant species was always Chlorella vulgaris in both types in which artificial synthetic wastewater were supplied continuously at constant rate and algae population density was around maximum 107 cells/mL. 3. It was around 108 ~ 107 cells/mL that the population density of heterotrophic bacterium. In culture medium systems type 1 and type 2 in which artificial wastewater were supplied continuously at constant rate, the same density appeared initially when using the population density of Escherichia coli w 3110 as indirect indicator. And this density decreased rapidly till the culturing date 35 days were passed away, while this density increased with gentle slope after same date and then the trend of change at type 2 was more severe than one at type 1. 4. When seeing such a change of population density of Escherichia coli w 3110, the growth of heterotrophic bacterium appeared as survival instinct pattern of broader requirement of nutrient at condition of low concentration of organic carbon substrate than condition of high concentration of same substrate.

• 한국환경과학회지
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• 제22권3호
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• pp.309-318
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• 2013

This study was conducted for determining the influence of artificial structures on benthic macroinvertebrate communities in stream. Sampling was taken at upper(pool), down(riffle) and control(riffle) from two check dams, two weirs, one agricultural reservoir, and one multipurpose dam in northern part of Gyeongsangbuk-do. The benthic macroinvertebrate communities of these structures were surveyed during 2009 to 2011. The simple habitat of benthic macroinvertebrates occurred at the upper sites due to pooling effects from artificial structures. Specifically, Check dam1, Jusanji, Imha dam showed very low biological attribute values compared to the down and control sites, which have greater difference in substrate characteristics. However, in the upper sites of Check dam2, Weir1 and Weir2, the difference of values of biological attributes was relatively smaller. Also, proportion of functional feeding groups and functional habit groups were relatively simpler at upper stream and the degree of community differences was greater between upper and down, control sites. Spearman's correlation between biological attributes and substrate characteristics, water quality parameters had significant correlations; particularly, the substrate characteristics were more significantly related. In conclusion, the pool caused by artificial structures had negative effects on benthic macroinvertebrate communities thus leading to simplified stream habitats at upper stream ecosystems.

• 전기학회논문지
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• 제58권8호
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• pp.1585-1591
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• 2009

This paper describes a new method for extracting characteristic impedance of transmission line using Substrate Integrated Artificial Dielectric (SIAD). The new procedure to calculate the characteristic impedance of SIAD transmission line is described with the proper equations and basic transmission line theory. The characteristic impedance is determined as an almost fixed value in the proposed method, while it fluctuates according to frequency in the previous method. As the result, the effective dielectric constant of SIAD transmission line is calculated as a fixed value rather than fluctuating one. In order to show the validity of the proposed method, SIAD microstrip lines are simulated and measured, and characteristic impedances and effective dielectric constant are calculated and compared to the previous method.

• 마이크로전자및패키징학회지
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• 제19권1호
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• pp.25-32
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• 2012

Package for artificial satellite is to produce mass production for high package with reliability certification as well as develop SDRAM (synchronous dynamic RAM) module which has such as miniaturization, mass storage, and high reliability in space environment. It requires sophisticated technology with chip stacking or package stacking in order to increase up to 4Gbits or more for mass storage with space technology. To make it better, we should secure suitable processes by doing design, manufacture, and debugging. Pin type PCB substrate was then applied to QFP-Pin type 3D memory package fabrication. These results show that the 3D memory package for artificial satellite scheme is a promising candidate for the realization of our own domestic technologies.