• Annual Conference of KIPS
• /
• 2007.05a
• /
• pp.337-340
• /
• 2007

일반적인 히스토그램 기법은 용선과 골로 이뤄진 지문 영상을 개선하는 효과가 미미하다. 히스토그램 스트레칭 기법은 명암 분포를 확장하여 전체 영상의 명암을 확장시키며, 히스토그램 스트레칭은 국소적인 명암 개선 효과에 탁월하므로 지문 영상 개선에 적합하지 않다. 따라서, 이 논문에서는 지문 영상을 개선하기 위해 평균과 표준 편차를 이용한 방법을 제안한다.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.2 no.4
• /
• pp.23-30
• /
• 1998

During an earthquake, there are three components of excitation : horizontal excitation of the ground, vertical excitation of the pile due to superstructure feedback produced by vertical excitation of the ground, and the seawater excitation by the vertical ground shaking, that is, "the seaquake." These excitations could have effects on the pore pressure buildup mode induced in the near-field of open-ended pile and the soil plugs in open-ended pipe piles installed at offshore sites. While the ground and pile excitation could be modeled by exciting the soil and pile with simulated motions, seaquake excitation induced by the vertical ground shaking can be modeled by pulsing the water pressure at the seabed. The objectives of this study were to observe buildup trend for the porewater pressures developed in near-field of open-ended pipe pile installed in the calibration chamber during the simulated earthquake and seaquake and, also to confirm the cause for reduction of soil plugging according to pore pressure buildup. During the simulated horizontal seismic motion, there was no upward flow through soil plug because the similar magnitude of excess porewater pressure were occurred at the top and under the toe of soil plug. During the horizontal seismic motion, relatively higher hydraulic gradients caused upward flow in the soil plug and then the degradation of plugging resistance was about 20%. During seaquake, in the case of the open-ended pile installed in a deep sea with more than 220m of water depth, soil plug failed completely because of high upward hydraulic gradients through soil plug.soil plug.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2013.05a
• /
• pp.820-823
• /
• 2013

Recently, the need for improving image quality of the image is increasing in various fields smartphones, cameras, and portable devices. How a significant impact on improving image quality of the image is a contrast enhancement, as a representative method to improve the contrast, the process of histogram equalization, various studies have been made. However, the method of histogram equalization general, by readjusting the only brightness, when the image histogram is biased to one side, due to changes in the excess brightness, distortions such as blocking phenomenon occurs. In this paper, we provide a contrast enhancement techniques through the compression and re-distribution of a well-balanced average brightness of the histogram distribution. By be differential compression histogram based on the histogram frequency in order to suppress the supersaturation phenomenon due to the increase in contrast ratio excessive repositioning well-balanced histogram lopsided, the proposed method, the balance of the brightness of the image I want to to take. The experimental results, the image brightness is balanced manner compared to conventional methods, the proposed method showed a good effect to improve the contrast without supersaturation phenomenon as compared with the conventional methods.

• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.8 no.6
• /
• pp.13-20
• /
• 2005

This study was conducted to examine the growth and physiological characteristics of Polystichum lepidocaulon native fern as affected by soil mixture as an environment modeled on habitate where was sunken-condition. 1. Polystichum lepidocaulon grew well sunken more than non-sunken condition. Under soil mixture of field soil : sand : leaf mold, Plant height, frond width, frond length, stipe length and ornamental value were increased compared with the other soil mixture. 2. Fresh and dry weight of fronds were higher with non-sunken than sunken condition. In sunken condition, fresh and dry weight were better with field soil : sand : leaf mold than the other soil mixture. 3. Number of spore fronds were increased with sunken condition. As sunken condition, sand : leaf mold was better than field soil : sand : leaf mold or leaf mold. 4. Photosynthetic rate, $CO_2$ absorption rate and water efficiency were higher with field soil : sand : leaf mold than that of sand : leaf mold or leaf mold. expect of stomatal conduction and $CO_2$ use efficiency.

• Journal of the Korean Geotechnical Society
• /
• v.33 no.12
• /
• pp.7-20
• /
• 2017

In this study, effects of grain size distribution on the shear strength and rheological properties are investigated for coarse- and fine-grained soils by using direct shear apparatus. Shear strengths are estimated for fine-grained soils with the maximum particle size of 0.075 mm and coarse-grained soils with the maximum particle size of 0.425 mm and fine contents of 17% prepared at dry and liquid limit states. The direct shear tests are conducted under the relatively slow shear velocity, which corresponds to the reactivated landslide or debris flow after collapse according to the landslide classification. In addition, for the evaluation of rheological properties, residual shear strengths for both fine- and coarsegrained soils prepared under liquid limit states are obtained by multiple reversal shear tests under three shear velocities. From the relationship between residual shear strengths and shear rates, Bingham plastic viscosity and yield stress are estimated. The direct shear tests show that cohesions of fine-grained soil are greater than those of coarse-grained soil at both dry and liquid limit states. However, internal friction angles of fine-grained soil are smaller than those of coarse-grained soil. In case of rheological parameters, the plastic viscosity and yield stress of fine-grained soils are greater than those of coarse-grained soils. This study may be effectively used for the prediction of the reactivated landslide or debris flow after collapse.

• Journal of the Korean Geotechnical Society
• /
• v.20 no.2
• /
• pp.115-124
• /
• 2004

Granular compaction pile has the load bearing capacity of the soft ground increase and has the settlement of foundation built on the reinforced soil reduce. The granular compaction group piles also have the consolidation of the soft ground accelerate and prevent the liquefaction caused by earthquake using the granular materials such as sand, gravel, stone etc. However, this method is not widely used in Korea. The granular compaction piles are constructed by grouping them with a raft system. The confining pressure at the center of bulging failure depth is a major variable in estimating the ultimate bearing capacity of the granular compaction piles. Therefore, a share of loading is determined considering the effect of load concentration ratio between the granular compaction piles and surrounding soils, and the variation of the magnitude of the confining pressure. In this study, a method for the determination of the ultimate bearing capacity is proposed to apply a change of the horizontal pressure considering bulging failure depth, surcharge, and loaded area. Also, the ultimate bearing capacity of the granular compaction pile is evaluated on the basis of previous study(Kim et al., 1998) on the estimation of the ultimate bearing capacity and compared with the results obtained from laboratory scale model tests and DEM numerical analysis using the PFC-2D program.

• Korean Journal of Environmental Agriculture
• /
• v.37 no.3
• /
• pp.166-171
• /
• 2018

BACKGROUND: Nitrogen leaching depends on the drainage pattern and nitrate content, and those are influenced by soil hydraulic properties and fertility. The purpose of this study was to confirm how soil texture contributed to leaching and balance of nitrogen, as well as to drainage. METHODS AND RESULTS: This study was performed using undisturbed weighing lysimeters which were piled up with clay loam (Songjung series) and sandy loam (Sanju series) soils in National Institute of Agricultural Science experimental field. Chinese cabbage was cultivated from August 30 to October 31, 2017. The application rates of N, $P_2O_5$, and $K_2O$ were 21.5, 7.8, and $15.0kg\;10a^{-1}$, respectively, and irrigation was supplied at -33 kPa in 30 cm soil depth. Drainage in clay loam was not noticeable, although it was increased by rainfall in early September. By contrast, the trend of drainage in sandy loam was strongly dependent upon rainfall pattern. Owing to different drainage patterns between both soil textures, nitrogen leaching was 5-fold higher in sandy loam than in clay loam. Nitrogen use efficiencies in clay loam and sandy loam were represented as 43% and 52%, respectively. CONCLUSION: The pattern of drainage and nitrogen leaching were greatly depended on clay content in soil. From this study, we carefully suggest that soil texture should be considered as an incidental factor to estimate nitrogen balance.

• Journal of the Korean Society of Earth Science Education
• /
• v.12 no.2
• /
• pp.165-173
• /
• 2019

This study purposes to figure out the effects of applying discussion-based science class on concept of science achievement and science teaching efficacy. This study established an twelve-week period of experimental treatment from April to June 2019, and the students who participated in this study formed a research group consisting of 27 students in the first semester of the second year of the B University of Education. and taking courses in 'elementary Science Textbook Research 1' For the classes applying discussion-based science class, the analysis was made on 2015 revised curriculum, and 12th process-centered performance assessment based on discussion. The developed data had designed to develop concept of science achievement and science teaching efficacy. The study group applied process-centered performance assessment based on discussion science class, so unaffectedly study group could improve their concept of science achievement and science teaching efficacy. B University of education is singleness class that doesn't have compare group, so this study is constituted only study group. Applying based-discussion science class to study group, before and after concept of science concept test, science teaching efficacy test is performed. The results of the study were as follows. First, the study group applied discussion-based science class had statistically significant differences in concept of science achievement (p<.05). Second, the study group applied discussion-based science class had statistically significant differences in science teaching efficacy(p<.05). Third, after discussion-based science class of pre-service teachers have a very good feeling. Through such study results, the study could figure out that the class applying discussion-based science class has positive effect on concept of science achievement and science teaching efficacy.

• 주택과사람들
• /
• s.122
• /
• pp.23-29
• /
• 2000

• Journal of the Korean GEO-environmental Society
• /
• v.7 no.1
• /
• pp.5-18
• /
• 2006

Stone column or granular compaction pile have been used in widely during the several decades as a technique to reinforce soft cohesive soils and increase bearing capacity, accelerate consolidation settlement of the foundation soil. The bearing capacity of the granular compaction pile is governed mainly by the lateral confining pressure mobilized in the native soft soil to restrain bulging collapse of the granular pile. Therefore, the technique becomes unfeasible in soft, compressible clayey soils that do not provide sufficient lateral confinement. This paper presents the main results of numerical study of granular compaction pile which is partly mixed with lean concrete. 3D finite element analyses are performed with composite reinforced foundations by both granular compaction pile and partly mixed granular compaction pile with lean-mixed concrete. Finally, a regression formula for calculating settlement reduction coefficients is proposed in this study by using numerical analysis results and applicability of the proposed method is identified by a series of parametric study about settlement reduction coefficients.