• Journal of ILASS-Korea
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• v.12 no.1
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• pp.45-57
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• 2007

This paper presents both experimental and numerical studies regarding nozzles used for the SI engine application, particularly for the intake-port fuel injection type. The atomization mechanism of the multi-hole plate nozzle was investigated experimentally. It was found that the nozzle design added turbulence into the liquid-film jet and the jet disintegrated rapidly. Based on the results, various plate types for the nozzle were developed and tested; six hole nozzle for liquid jet interaction, plate-type nozzle with flat duct channel, and the simpler structured nozzle. The spray characteristics of the prototype nozzles were examined experimentally while the internal flow of the nozzle was investigated computationally. It was shown that turbulent liquid-film was injected and atomization quality was improved by controlling the internal flow condition of the plate-type nozzle.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.6 no.2
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• pp.11-18
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• 1995

The goal of this research is to get a measuring system for absorption characteristics of electromagnetic wave absorbers in fernite type which are flat, grid-type and special type, etc. It is, however, very difficult to measure the absorption characteristics in as low frequency as 30 MHz. To solve the problem, therefore, we propose a standing wave method and a measurement method in time domain using paralledl striplines, construct the measuring system, and measure the charac- teristics of ferrite microwave absorbers in grid type using the proposed measuring system.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.1835-1842
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• 2007

The purpose of this paper describes the changes of TGV & ICE series' nose shape by increasing train speed and according to the periodical characteristics. As the speed increases, the length of the nose shape trends to lengthen longer. But the nose shape length does not increase as speed improves by optimized nose shape to reduce aerodynamic drag and micro-pressure wave in tunnels. TGV & ICE series' nose shape can be classified into Advanced paraboloid type, Shape-nosed type, Organic double-edged type and Flat-nosed type by the advance research(the changes of Shinkansen vehicle' nose shape) of high speed railway. Because it trends to be diversified and characterized more and more. This paper analyzed and introduced as TGV & ICE series' nose shape by top 2 nation (Germany, France) and high speed railway in the past years(1980-2007) for their railway design trends by new positioning(Advance research).

• Journal of the Korean housing association
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• v.14 no.5
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• pp.11-17
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• 2003

This study is aimed at analyzing on the sunshine according to the blocks direction by location type of apartment complex in Busan, to propose a planning on the decision of blocks direction and the improvement of architectural law in sunshine environment. The results of this study were as follows; On the basis of winter solstice in "□ block type", the average of ratio of shadow area in flat site is 51 % in apartment with a southern exposure, 39% in apartment with a south-eastern exposure. The average of ratio of shadow area in the descended site toward the north is 49% in apartment with a southern exposure, 34% in apartment with a south-eastern exposure. The average of ratio of shadow area in the descended site toward the south is 66% in apartment with a southern exposure, 53% in apartment with a south-eastern exposure.

• Applied Microscopy
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• v.46 no.2
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• pp.110-115
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• 2016

Transmission electron microscopy (TEM) is a powerful tool for analyzing a broad range of materials and provides localized information about the microstructure. However, the analysis results are strongly influenced by the quality of the thin foil specimen. Sample preparation for TEM analysis requires considerable skill, especially when the area of interest is small or the material of interest is difficult to thin because of its high hardness and its mechanical instability when thinned. This article selectively reviews recent advances in TEM sample preparation techniques using a tripod polisher. In particular, it introduces two typical types (fl at type and wedge type) of TEM sample preparation and the benefits and drawbacks of each method; finally, a method of making better samples for TEM analysis is suggested.

• Proceedings of the KSR Conference
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• 2005.11a
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• pp.94-100
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• 2005

This paper describes the changes of Shinkansen vehicles' nose shape by increasing train speed and according to the stream of time. As the speed increases, the length of the nose trends to lengthen longer. But the nose length does not increase as speed improves by optimized nose shape to reduce aerodynamic drag and micro-pressure wave in tunnels. Shinkansen vehicles nose shape can be classified into Advanced paraboloid type, Sharp-nosed type, Organic double-edged type and Flat-nosed type. In addition, it trends to be diversified and characterized more and more. In the near future, nose designs will be emphasized by the design concept including identity of each JR company based on optimized aerodynamic shape.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.145.1-145.1
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• 2013

A prerequisite for the development of graphene-based field effect transistors (FETs) is reliable control of the type and concentration of carriers in graphene. These parameters can be manipulated via the deposition of atoms, molecules, and polymers onto graphene as a result of charge transfer that takes place between the graphene and adsorbates. In this work, we demonstrate a unique and facile methodology for the homogenous and stable p-type doping of graphene by hybridization with ZnO thin films fabricated by MeV electron beam irradiation (MEBI) under ambient conditions. The formation of the ZnO/graphene hybrid nanostructure was attributed to MEBI-stimulated dissociation of zinc acetate dihydrate and a subsequent oxidation process. A ZnO thin film with an ultra-flat surface and uniform thickness was formed on graphene. We found that homogeneous and stable p-type doping was achieved by charge transfer from the graphene to the ZnO film.

• Journal of the Korean Wood Science and Technology
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• v.32 no.6
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• pp.50-56
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• 2004

This study was conducted to investigate the performance of sound absorption type-noise barriers manufactured with a combination of wood particles used for particleboard, recycled waste newspaper, and cement. An average density of wood-combined cement board was in the range from 0.83 to 0.96 g/cm³, showing relatively low-density board. Regardless of types of cement bonded board or wooden board, the board with concave holes(凹)-formed surfaces showed greater sound absorption coefficient compared to those of flat surface boards. The board density was not related with those coefficients. Accordingly, it was concluded that concave or deep corrugated surface structure has played an important role in sound absorption for the application of sound absorption type-noise barrier.

• Journal of Power Electronics
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• v.12 no.2
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• pp.317-325
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• 2012

Resonant immittance converter (RIC) topologies can transform a current source into a voltage source (Type-I RICs) and vice versa (Type-II RICs), thereby making them suitable for many power electronics applications. RICs are operated at a fixed frequency where the resonant immittance network (RIN) exhibits immittance conversion characteristics. It is observed that the low-frequency response of Type-II RINs is relatively flat and that the state variables associated with Type-II RINs affect the response only at the high frequencies in the vicinity of the switching frequency. The overall response of a Type-II RIC is thus dominated by the filter response, which is particularly important for the controller design. Therefore, an approximate equivalent circuit model and a small-signal model of Type-II RICs are proposed in this paper, neglecting the high-frequency response of Type-II RINs. While the proposed models greatly simplify and speed-up the analysis, it adequately predicts the open-loop transient and small-signal ac behavior of Type-II RICs. The validity of the proposed models is confirmed by comparisons of their results with those obtained from a cycle-by-cycle simulation and with an experimental prototype.

• Current Research on Agriculture and Life Sciences
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• v.19
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• pp.31-37
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• 2001

Uyeki(1928) classified Pinus densiflora into six ecotypes(Northeastem type, Middle-southern flat type, middle-southern upland type, Wibong type, Ankang type, and Geumgang type) based on the pine tree type. The bark color of Geumgang type was ash-brown color on the lower parts of stem and yellowed color on the upper parts of stem. We investigated the physicochemical properties of soil forests to obtain basic data for preservation of exellent pine (Pinus densiflora for. erecta Uyeki). The results were as follows; The soil texture of the Pinus densiflora for. erecta Uyeki forests were showed nearly as sandy loam, that is, sand, silt and clay were consisted of 72%, 15% and 13%, respectively. Soil acidity(pH 4.6) was lower than Korea average forest soil acidity(pH 5.2). The average contents of available phosphate was 11.7ppm at Sokwang-ri, 26.8ppm at Mt. Eungbong, 24.2ppm at Mt. Kumma. It was the lowest at Uljin(4.6ppm). The contents of carbon was 6.2% at Mt. Chungok, 6.1% at Mt. Eungbong. This value was more than average of Korea forest soil.