• Proceedings of the Korean Geotechical Society Conference
• /
• 2004.03b
• /
• pp.82-89
• /
• 2004

To secure stability and availability of Rammed Aggregate Pier method as the foundation of a structure, the shear strength characteristics according to the area replacement ratio of RAP and the relative density of in-situ ground was studied through soil laboratory tests and large direct shear tests in a model ground. As a result, the internal friction angle tends to increase in proportion to in-situ relative density(Very Loose, Loose, Medium) in composite ground formed by the same area replacement ratio of RAP and also increase in proportion to increasing the area replacement ratio(30, 40, 50%) of RAP in the same ground condition. Furthermore, the comparative analysis between the experimental value and theoretical value of the shear strength is carried out.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1996.11a
• /
• pp.10-12
• /
• 1996

AlGaAs/GaAs Heterojunotion Bipolar Transistors (HBTs) with various emitter areas were fabricated and the device size dependence on the current gain was examined. With the different emitter areas, the passivated devices having the same peripheral length were fabricated and measured. The measured base current density in the Gummel plots shows an ideality factor of nearly 2. It is found that as the emitter area becomes small, the base current density with the ideality factor of 2 increases linearly, and as the emitter perimeter/area ratio becomes large, the surface recombination current density component increases. The current gain performance in AlGaAs/GaAs HBTs is mainly determined by either the larger emitter area or the smaller ratio of the emitter perimeter to the emitter area. These results will be compared with experimental works for GaInP/GaAs HBTs

• Journal of the Korean Graphic Arts Communication Society
• /
• v.10 no.1
• /
• pp.15-22
• /
• 1992

This paper proposed correction tone density eq. and dot area eq. for perdict tone reproduction when dot gain is constant, and these are based on Yule & Nielson`s tone density equation. The experimental results show that proposed coreaction tone density eq. and dot area eq. are useful and valid for perdict tone reproduction of a half-tone image.

• Journal of the Korean Society of Tobacco Science
• /
• v.16 no.1
• /
• pp.34-42
• /
• 1994

Experiments on the variability of plant type and factors representing the productivity and quality of the cultivars were subsequently carried out in relation to different plant density. Results are summarized as below. The higher was the plant density, the greater was the plant height and mean leaf inclination(MLI). As the plant density increased, the horizontal leaf area distribution became greater in proximal to the stem in NTN 77 and Br.49 but evenly in distal part in Br.21. Meanwhile, in terms of vertical leaf area distribution, it was decreased much more in middle and lower leaves than in upper in NTN 77 and Br.49 although it steadily decreased in any part of the plant in Br.21. Br.49 was the largest but Br.21 and NTN 77 were similar with respect to both CGR and NAR. The yield was greater in larger MLI cultivars(NTN 77>Br.49>Br.21). These three characteristics became greater when the tobacco were planted more densely in the field. Dry leaf weight and dry matter weight per plant were heavier in the larger MLI and increased with lower plant density. Total nitrogen content was greater in lower plant density and larger MLI cultivar. The plant density increases filling power seems to be enhanced regardless to the plant type. There was no discernible tendency on combustibility according to the plant density or plant type.

• 한국해양학회지
• /
• v.27 no.2
• /
• pp.164-172
• /
• 1992

This study was carried out to investigate the benthic polchaete community in the southern area of Kyeonggi Bay, Korea. The species composition was examined in Asan Bay in 1985, the coastal area near Yibug in 1987, the area between Daeranjido and Asan Bay for 1988-1989, and the offshore south of Deogjeogdo in 1992. Polychaetes, the dominant faunal group occupying 57.4% in total density, comprised a total of 124 species with a mean density of 211 indiv.m/SUP -2/. The dominant polychaete was Prionospio sp. (28.8%), followed by Nephtys polybranchia (6.0%), Tharyx sp. (4.8%) Stermaspis scutata (4.4%), Lumbrineris longifolia (3.9%). The Number of species and density were higher in the coastal area near Yibug, Asan Bay and the mouth of Namyang Bay, while lower in the channels of offshore region. The cluster analysis revealed that the study area could be divided into 5 regions, which were distributed serially along the coast from Asan Bay to open sea. Each region sustained its specific Bay, Stermaspis-Heteromastus assemblage from Asan Bay to Daeranjido, Hemipodus assemblage in the channels of offshore, Lumbrineris assemblage on the coastal area o Yibug and Prionospio assemblage in the coastal area south of Yibug. Tharyx-Chone assemblage had the highest species number of 75 spp. and Prionospio assemblage had the highest density of 3,695 indiv.m/SUP -2/ due to the predominance of prionospio sp.. Hemipodus assemblage with the lowest density occupied the largest area in offshore region. The southern Kyeonggi Bay showed higher species number and lower density than the northern Kyeonggi Bay. But the dominant Polychaetes were similar between the southern Bay and the channel regions of the northern Bay.

• Journal of the Korean Society of Radiology
• /
• v.14 no.5
• /
• pp.635-642
• /
• 2020

The purpose of this study was to analysis the effects of shielding area of field configuration with changing of sensitivity and density on tube current (milliampere-seconds, mAs) and image quality in automatic exposure control (AEC) system. The equipment used a digital radiography device (Digital Diagnost, Philips, Netherlands), which has a integral type with an X-ray tube and an indirect digital detector. The AEC system conditions were consisted of 9 setting environments, that mode changing of the sensitivity (S200, S400, S800) and the density (+2.5, 0, -2.5). The tube current evaluated automatically exposed mAs under 81 combination conditions crossed by AEC conditions in fixed at 40 kVp. The image quality evaluated the radiographic images that selected valid images by visual assessment the radiographic images of the self-produced conical pyramid phantom and then measured their signal to noise ratio (SNR). As a result, the maximum tube current was 60.0 mAs that automatically exposed conditions were the 100% of shielding area and the sensitivity of S200 and the density of +2.5. The minimum tube current was 0.9 mAs with non-shielding area and the sensitivity of S800 and the density of -2.5. When the shielded area 0% with the sensitivity of S200 and the density of +2.5, the maximum SNR was the highest as 25.2. But when the shielded area 25% with the sensitivity of S800 and the density of -2.5, the minimum SNR was the lowest as 4.7.

• Journal of the Korean Magnetics Society
• /
• v.23 no.6
• /
• pp.188-192
• /
• 2013

The magnetic interaction effect on the magnetic activation volume and area of electrodeposited CoPt magnetic films was investigated. The dipolar interaction was predominant interaction mechanism for all samples. And the interaction strength was increased with decreasing current density and increased with increasing sample thickness. Although the activation volumes of the samples fabricated at low current density were larger than those of the high current density samples, the sample thickness seemed to have little influence on the variation of activation volume. But it was found that the activation area was apparently affected by the magnetic interaction strength as well as the current density.

• Journal of Forest and Environmental Science
• /
• v.31 no.4
• /
• pp.288-296
• /
• 2015

In many very high density cities in Asia in which there is limited area to expand, growth is forced upward as well as outward. Densely packed detached houses and low-rise buildings are replaced by lower density high-rises, leaving open spaces between high-rise buildings. Through this process, areas that formerly did not have much green space gain valuable green spaces, and new ecological corridors and patches are created. In this study, the demographic and housing-type changes of Wonju City were delineated using land use maps, aerial images, census data, and other administrative data. Green area changes were calculated using land cover data derived from multi-year Landsat TM satellite imagery. The values were then compared against demographic and housing-type changes for each administrative unit. The overall results showed a decrease of forested area in the city and an increase of developed area. Urban sprawl was clearly visible in many of the suburban areas. However, as expected, we also detected areas in which greenness did not decrease when the population greatly increased. These areas were characterized by residential building complexes of ten or more stories. If an equal number of housing units had been built as detached houses, these areas would not have kept as much green space. Our research result showed that high-density and high-rise residential structures can offer an alternative means to protect or create urban green spaces in high-density urban environments.

• Land and Housing Review
• /
• v.2 no.3
• /
• pp.217-226
• /
• 2011

The Seoul Metropolitan Government is striving to minimize the amount of traffic according to the supply of apartment houses along with the solution of housing shortage for the low income people through high density development near the subway area. Therefore, a stronger policy is necessary to control the traffic of the passenger cars in a subway area for the successful high density development focusing on public transportation, and especially, the estimation of the demand of cars with high reliability is necessary to control the demand of parking such as the limited supply of parking lot. Accordingly, this study developed car ownership forecasting model using Look-up Table among category analyses which are easy to be applied and have high reliability. The estimation method using Look-up-Table is possible to be applied to both measurable and immeasurable types, easy to accumulate data, and features the flexible responding depending on the changes of conditions. This study established Look-up-Table model through the survey of geographical location, the scale of housing, the accessible distance to a subway station and to a bus station, the number of bus routes, and the number of car owned with data regarding 242 blocks in Seoul City as subjects.

• Journal of the Korean Geographical Society
• /
• v.33 no.3
• /
• pp.365-376
• /
• 1998

The goal of this study is to find the geomorphic variables contolling gully development on hillslopes following deforestation. Two possible geomorphic processes, surface erosion and mass movement were reviewed to compare the characteristics and geomorphic variables involved. The research objective in this paper is to find the variables and the statistical model which can explain gully density in the study area. Gully density was selected as a response variable. For log gully density, the best subset regression was found to have the variables such as area, surface length, and surface width. Log area is the most significant predictor. Even with several outliers, the normal probability plot of the residuals from this regression looks straight. So, area, surface length, and surface width explain half of the variance in gully density.