• Journal of Korea Soil Environment Society
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• v.3 no.3
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• pp.63-74
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• 1998

In the study, the feasibility of deposit soil in river and stream bed as a subsitute for conventional plant soil was investigated through the analysis of soil characteristics and germination/growth rate for 75 days. Proper mixtures among sediments from various places were compared to optimize the germination and growth rate of plant in the ratio of 2 : 1 and 3 : 1 (sand : deposit). From the results, it could be concluded that the sediment mixed 3 : 1 showed most favorable germination and growth conditions for pansy and the sediment containing enough amount of silt and clay components showed most favorable conditions for marigold. Consequently, the feasibility of sediments as a substitutional plant soil was evaluated to be high, once the sediments were properly mixed for each specific plant.

• Journal of the Korean Wood Science and Technology
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• v.7 no.1
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• pp.3-7
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• 1979

A bark comprises about 10 to 20 percents of a typical log by volume, and is generally considered as an unwanted residue rather than a potentially valuable resources. As the world has been confronted with decreasing forest resources, natural resources pressure dictate that a bark should be a raw material instead of a waste. The utilization of the largely wasted bark of genus Pinus, Quercus and Populus grown in korea can be enhanced by Knowing its chemical Properties. Specially, uses of bark in mulching, growing media and soil amendment can be enhanced by knowing pH and C.E.C values. In this paper, an investigative study is carried out on the pH-and C.E.C-values. The results may be summarized as follows: 1. Bark is acid in nature, and pH values of bark varying from 3.3 to 4.7, is lower than that of wood.pH value of Pinus is the lowest. 2. Cation exchange capacity of bark is greater than that of wood, silt loam soil, and wheat straw.CEC of bark is 45.7 meq/100gm in Pinus, 41.8 meq/100gm in populus, 37.8 meq/100gm in Quercus.

• Journal of Korean Society of Water and Wastewater
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• v.26 no.1
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• pp.87-95
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• 2012

In this study, the following conclusions were obtained from an investigation of the effect of the simulation time step on the simulation results of the two-dimensional, vertically averaged sediment transport model SED2D and an analysis of the deposited sediment distribution in suspended sediments of reservoirs according to grain size. The simulation time step has a significant effect on the deposited sediment distribution in a reservoir. In particular, if the simulation time step is set to be excessively large, physically invalid results are obtained. Additionally, in order to determine an appropriate simulation time step for SED2D, the selection of a simulation time step that will allow the analysis of the suspended sediment concentration profile at the main points of the simulation domain is necessary. The deposited sediment distribution in a reservoir according to grain size, including suspended sediments of clay, silt, and sand, was successfully simulated. Such information will prove valuable in application to the establishment of efficient management and reduction measures of reservoir sediment deposits.

• The Journal of the Acoustical Society of Korea
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• v.25 no.2E
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• pp.49-55
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• 2006

Compressional wave velocity (Vp), shear wave velocity (Vs), elastic and physical properties, and electrical resistivity for two core sediments obtained from Southeastern Yellow Sea Mud (SEYSM) were measured and computed. The sediments consist of homogeneous mud (mostly silt and clay) with shells and shell fragments. As a result, the mean grain size is uniform ($7.5-8.5{\Phi}$ throughout the core sediments. However, physical properties such as wet bulk density and porosity show slightly increasing and decreasing patterns with depth, compared to the mean grain size. The compressional (about 1475 m/s in average) and shear wave (about 60 m/s in average) velocities with depth accurately reflect the pattern of wet bulk density and porosity. Electrical resistivity is more closely correlated with compressional wave velocity than physical properties. The computed Vp/Vs and Poisson's ratios are relatively higher (more than 10) and lower (approximately 0.002) than Hamilton's (1979) data, respectively, suggesting the typical characteristics of soft and fully water-saturated marine sediments. Thus, the Vp/Vs ratio in soft and unconsolidated sediments is not likely sufficient to examine lithology and sediment properties. Relationships between the elastic constant and physical properties are correlated well. The elastic constants (Poisson's ratio, bulk modulus, shear modulus) given in this paper can be used to characterize soft marine sediments saturated with seawater.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.1042-1050
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• 2008

In this study, SCP method was used by purpose to improve loose sand and soft clay that is drilled Sand Compaction Pile in underground. Settlement behavior of field analyzed through SCP method. When sand Compaction Pile drilled in clay, forming composite ground that foundation and Sand Compaction Pile behavior. According to SCP method can expect bearing capacity improvement, Settlement reduction, lateral flow protection. SCP increase the consolidation settlement of ground and it reduce settlement for that purpose increase liquefaction resistance, lateral Resistance. Because SCP had been widely used for sand. Area of Inchon-A by sand compose clay and silt to upper Ground and compose soft clay to under ground. After pre-loading, it measured settlement by extensometer and settlement extensometer that purpose of ground improvement with 13% in replacement ratio. The result analyzed settlement behavior is similar to Multi-layered Ground that it happened to elastic settlement at upper ground and to consolidation settlement at under ground.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.2
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• pp.66.1-66.1
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• 2016

We developed an observation control software for the IGRINS (Immersion Grating Infrared Spectrograph) silt-viewing camera module, which points the astronomical target onto the spectroscopy slit and sends tracking feedbacks to the telescope control system. The point spread function (PSF) is not always symmetric. In addition, bright targets are easily saturated and shown as a donut shape. It is not trivial to define and find the center of the asymmetric PSF especially on a slit mask. We made a center balancing algorithm (CBA) following the concept of median. The CBA derives the expected center position along the slit-width axis by referencing the stray flux ratios of both upper and lower sides of the slit. We compared efficiencies of the CBA and those of a two-dimensional Gaussian fitting (2DGA) through simulations from observation images in order to evaluate the center finding algorithms. Both of the algorithms are now applied in observation and users can select the algorithm.

• Journal of the Korean Institute of Landscape Architecture
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• v.31 no.5
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• pp.11-19
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• 2003

The main purpose of this study was to examine the application of the root system as a shore protection material through the measurement of the 개ot growth curve of Salix gracilisyla Miq. depending on the cutting size. As materials and methodology, nine group of cuttings were classified by the length(l0cm, 20cm, 40cm) and the diameter(0.72cmm$\pm$0,02, 0.58cm$\pm$0.02, 0.35cm$\pm$0.02), Each group was stuck to a flooding bed of sandy loam(Sand 60,36%, Silt 28%, Clay 11.64%) on 27th March 2001, After 65 growing days, the weight and length of the newly developed roots, shoots, and leaves were measured and analysed, This was repeated at 99, 129, 159, and 190 growing days. The major findings were as follows. The primary determinant of the root growth rate was on the weight of cutting, The secondary determinant was on the number of growing days. In addition, the dominant dimension of the cutting was the diameter rather than the length, The thicker cutting caused more rapid and stable growth however the longer cutting made the growth of the root slower and more unstable.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.1224-1227
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• 2006

It has been recognized unsaturated soil behaviour playing an important role in geomechanics. Up to now, only a few experimental data are available for the technical difficulties related to both volume changes and suction measurements. In this study, the volume changes of unsaturated compacted silty soil were monitored with proximeter (i.e. non-contactable transducer) during various triaxial compression tests, which gave a realistic estimation in the volume changes of unsaturated soil sample. The measurement of volume changes were performed with 0.5% of the maximum error under the axial strain ratio of less than 10%. The experimental results have revealed that the mechanical behaviour of unsaturated soil can be significantly affected by the matric suction. During the shearing processes, the level of maximum deviator stress under the initial suction pressure of 50kPa was higher than that under the initial suction pressure of 10kPa. On the other hand, the volume changes became smaller under the increase in the initial suction pressure.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.268-275
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• 2006

Excavation works of cylindrical shafts and tunnels for the construction of a variety of infrastructures have been frequently going on in the urban areas. When ground excavations of cylindrical shafts and shallow tunnels proceed in the ground condition of high water level and silt particle component, ground water drawdown involving soil particle migration causes loosening of ground around tunnels and shafts, causes settlement and deformation of ground. Damages due to ground sinking and differential settlement can occur in the adjacent ground and structures. The extent and possibility of damage relevant to ground water drawdown and soil particle migration can't be so precisely expected in advance that we will face terrible damages in case of minor carefulness. This paper introduces two examples of construction management where using incremental deformation graph of inclinometer, we noticed the possibility of soil migration due to ground water drawdown in the excavation process of vertical shaft and shallow tunnel, analysed a series of measurement data in coupled connection, properly prepared countermeasures, so came into safe and successful completion of excavation work without terrible damages. The effort of this article aims to improve and develop the technique of design and construction in the coming projects having similar ground condition and supporting method.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.1528-1537
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• 2005

The purpose of this study is investigated the method for estimation of the liquefaction on the reclaimed land, located in Incheon and assessed the ability of liquefaction under the condition of criteria, which is the magnitude '6.5' of seismic on the basis of the domestic seismic characteristics. Performed not only field test but the experiment as well to study how the fine content would affect into the dreging and reclaimed land and also estimated the safety factor through the empirical method and anticipated detail method based on the results. Within the reclaimed land, there are many sized soils which are almost extended from well-graded silty sand(SM) to poor-graded fine grained sand, and which have the condition, so called, the liquefaction which is easily to bring into under the circumstances within the ground. However, partly, now that the soil is mixed with silt and silty clay which include the content of fine grained dust quite a bit, the difficulties and inconveniences has been expected while trying to find the ratio of cyclic resistance, but finally Seed and Idriss method showed the most way when we estimate the safety factor on the liquefaction.