• Journal of the Korean GEO-environmental Society
• /
• v.16 no.11
• /
• pp.39-43
• /
• 2015

In this study, the infiltration quantity of fine-grained soil into coarse-grained soil or aggregate for methods to accelerate consolidation drainage is checked by laboratory tests under various conditions and those characteristics on infiltration are examined closely. Irrespectively of pressures to fine-grained soil corresponding to stresses in a soil mass or moisture contents of fine-grained soil, fine-grained soil does not infiltrate into standard sand and marine sand, so it is verified that drain-resistance into sand mass of drainage / pile does not occur entirely and its shear strength would increase highly by water compaction. It is known that the infiltration depth of fine-grained soil into aggregate increases according that those size is larger in case of aggregates and it increases according that the pressure or the moisture contents is higher in case of same size aggregate. It is thought that drain-resistance into aggregate mass of drainage / pile would occurs by infiltrated fine-grained soil in advance though the infiltration depth of fine-grained soi of lower moisture content than liquid limit into 13 mm aggregate is low quietly. So gravel drain method or gravel compaction pile method, etc. using aggregate of gravels or crushed stones, etc. larger than sand particle size should be not applied in very soft fine-grained soil mass of higher natural moisture contents than liquid limit, and it is thought that its applying is not nearly efficient also in soft fine-grained soil mass of lower natural moisture contents than liquid limit.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.4 no.4
• /
• pp.312-322
• /
• 1999

We have studied both submarine morphology and sediment characteristics of waste disposal sites in the southwestern Ulleung Basin, East Sea, as part of a marine environmental preservation program. The Jung waste disposal site in the outer shelf is characterized by the thick accumulation of coarse-grained palimpsest sediments and fine-grained sediments from various sources. The Byung waste disposal site in the continental slope is generally characterized by hemipelagic muds with intermittent sandy sediments originated from the outer shelf and upper slope. The hemipelagic sediments, draping the seafloor, consist of fluidized muds. The core sediments show numerous bioturbation structures which cause vertical mixing of sediments. The surface sediments can be divided into four sand types (S-1, S-2, S-3, and S-4) and two mud types (M-1 and M-2) based on relative contents of reworked coarse-grained palimpsest sediments and fine-grained sediments. sorting and heavy mineral contents. The sands are probably relict sediments reworked during high-energy conditions such as typoon or storm. On the other hand, the muds were originated from various sources such as recent input from the Nakdong River, reworked fine-grained sediment from the shelf or suspended particulate matter from the East Sea Warm Current.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.24 no.1
• /
• pp.26-35
• /
• 2012

Until now, study on the hydraulic resistance characteristics of the ground at the river and the ocean current has been focused on the behavior under uni-directional flow without the direction change of flow. However, recent research result shows that scour rate which were measured under the bi-directional flow was much higher than those measured under uni-directional flow for both fine grained and coarse soil. Since the direction of inflow and return flow at the shore, where the structure will be constructed, is not always $180^{\circ}$, effect of the incidence angle on the hydraulic resistance capacity of the ground should be examined. Using the improved EFA which can consider the direction change of flow, hydraulic resistance capacities of the artificially composed clayey fine grained soil and clayey sandy soil under $0^{\circ}$, $90^{\circ}$, $135^{\circ}$, $180^{\circ}$ flow angle of incidence were assessed. Test result shows that hydraulic resistance capacity decreases and scour rate increase with the increase of the incidence angle between inflow and return flow. For the low consolidation pressure condition, hydraulic resistance capacity of the fine grained soil decreases rapidly. While the hydraulic resistance capacity of the coarse grained soil decreases more rapidly than fine grained soil under high consolidation pressure. Eventually since the larger the incidence angle between inflow and return flow, the larger the scour rate. Hydraulic resistance capacity under bi-directional flow($0^{\circ}{\longleftrightarrow}180^{\circ}$) should be examined for the design purpose.

• Journal of KIISE:Software and Applications
• /
• v.30 no.11
• /
• pp.1025-1036
• /
• 2003

In industry, it is a current trend that systems are developed by using Enterprise JavaBeans(EJB) technology for reducing the cost and the time. Thus, the architecture of EJB is getting more essential to enhance reusability, extensibility and portability of system. However little has been studied in the realm of the practical software architectures for EJB. The architecture has just bean studied in abstract level, but not in concrete level providing the method to substantiate it using the practical J2EE techniques. Just using the EJB technology doesn't guarantee the reusability of the artifacts because EJB specification provides the characteristics and architecture for only fine grained components as session and entity bean. In this paper, we propose the enterprise software architecture for the systems based on EJB and the concrete techniques for implementing that. Also, design patterns of modeling efficient enterprise architecture are represented. By analyzing both the strengths and the weaknesses of suggested design patterns, EJB design patterns which are suitable for each layer of enterprise architecture will be identified. Through the component which design patterns are applied, the architecture can support the optimized relationship between the components. Five techniques for designing components from fine grained to coarse grained based on EJB technology, and architecture design techniques including transaction and assembling techniques are proposed.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2007.05a
• /
• pp.421-424
• /
• 2007

Dry sliding wear behavior of ultra-fine grained (UFG) plain low carbon dual phase steel, of which microstructure consists of hard martensite in a ductile ferrite matrix, has been investigated. The wear characteristics of the UFG dual phase steel was compared with that of a coarse grained dual phase steel under various applied load conditions. Dry sliding wear test were carried out using a pin-on-disk type tester at various loads of 1N to 100N under a constant sliding speed condition of 0.20m/s against an AISI 52100 bearing steel ball at room temperature. The sliding distance was fixed as 1000m for all wear tests. The wear rate was calculated by dividing the weight loss, measured to the accuracy of 10-5g by the specific gravity and sliding distance. The worn surfaces and wear debris were analyzed by SEM, EDS and profilometer. Micro-vickers hardness of the cross section of worn surfaces were conducted to analyze strain hardening underneath the contact surfaces. The wear mechanism of the UFG dual phase steel was investigated with emphasis on the unstable nature of the grain boundaries of the UFG microstructure.

• Transactions of Materials Processing
• /
• v.18 no.7
• /
• pp.544-549
• /
• 2009

This study aimed to elucidate the deformation mechanism during low-temperature superplasticity of fine-grained Ti-6Al-2Sn-4Zr-2Mo-0.1Si alloy in the context of constitutive equation. For this purpose, initial coarse equiaxed microstructure was refined to $2.2{\mu}m$ via dynamic globularization. Globularized microstructure exhibited large superplastic elongations(434-826%) at temperatures of $650-750^{\circ}C$ and strain rate of $10^{-4}s^{-1}$. It was found that the main deformation mechanism of fine-grained material was grain boundary sliding accommodated by dislocation motion with both stress exponent (n) and grain size exponent (p) values of 2. When the alpha grain size, not sub-grain size, was considered to be an effective grain size, the apparent activation energy for low-temperature superplasticity of the present alloy(169kJ/mol) was closed to that of Ti-6Al-4V alloy(160kJ/mol).

• Transactions of Materials Processing
• /
• v.16 no.4 s.94
• /
• pp.299-303
• /
• 2007

Dry sliding wear behavior of ultra-fine grained(UFG) plain low carbon dual phase steel, of which microstructure consists of hard martensite in a ductile ferrite matrix, has been investigated. The wear characteristics of the UFG dual phase steel was compared with that of a coarse grained dual phase steel under various applied load conditions. Dry sliding wear test were carried out using a pin-on-disk type tester at various loads of 1N to 100N under a constant sliding speed condition of 0.20m/s against an AISI 52100 bearing steel ball at room temperature. The sliding distance was fixed as 1000m for all wear tests. The wear rate was calculated by dividing the weight loss, measured to the accuracy of 10-5g by the specific gravity and sliding distance. The worn surfaces and wear debris were analyzed by SEM, EDS and profilometer. Micro-vickers hardness of the cross section of worn surfaces were conducted to analyze strain hardening underneath the contact surfaces. The wear mechanism of the UFG dual phase steel was investigated with emphasis on the unstable nature of the grain boundaries of the UFG microstructure.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.37 no.4
• /
• pp.323-329
• /
• 2004

In situ particle size and volume concentration of suspended sediment was measured at the mouth of Seomjin River Estuary In February 2001, using an optical instrument, 'LISST-100'. Time variation of in situ particle size and concentration shows: (1) during ebb tide, Seomjin River supplies relatively fine-grained particles with less-fluctuated, compared to during flood tide, and well-behaved concentrations following the tidal cycle; and (2) during flood tide, relatively coarse-grained particles with highly variable in size distribution and concentration flow upstream from Kwangyang Bay. This explains a poor correlation $(r^{2}=0.10)$ between sediment concentration and beam attenuation coefficient during flood and a high degree of correlation $(r^{2}=0.80)$ during ebb tide. Relatively fine grained and well defined, monotonous size distribution may promote the correlation between concentration and beam attenuation coefficient due to optical homogeneity of particles during ebb tide. Abundance of large aggregates with time-varying size and shape distributions may be mainly responsible for variations in optical properties of the sediment during flood tide, and thus may confound the relationship between the two variables. The difference in particle sizes and shapes between flood and ebb tides can also be observed on SEM images.

• Proceedings of the KSRS Conference
• /
• 2005.10a
• /
• pp.249-252
• /
• 2005

Microphytobenthos bloom from late January to early March in Korean tidal flats. KOMPSAT-2 will provide multi-spectral images with a spatial resolution of 4 m comparable with IKONOS. Using IKONOS and Landsat data, algal mat detection was tested in the Saemangeum area~ Micro-benthic diatoms are abundant and a major primary product in the tidal flats. A linear spectral unmixing (LSU) method was applied to the test data. LSU was effective to detect algal mat and the classified algal mat fraction well correlated with NDVI image. Fine grained upper tidal flats are generally known to be the best environment for algal mat. Algal mat thriving in coarse grained lower tidal flats as well as upper tidal flats were reported in this study. A high resolution multi-spectral sensor in KOMPSAT-2 will provide useful data for long-term monitoring of microphytobenthos in tidal flats.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1995.04a
• /
• pp.164-169
• /
• 1995

Cracks in the concrete structure are known to develope by various mechani는, including an alkali-aggregate reaction. The alkali-silicate reaction between aggregates and cement is studied using polarized microscope, electron probe microanalyser and electron microscope. Metamorphosed, biaxial quartz and feldspars grains appear to have reacted readily with alkali from cement. For a given mineral, fine-grained minerals tend to react readily over the coarse-grained ones. A chemical analysis shows that the elements K, Na, Ca, and Si migrated, in most cases, fro the portion of h호 concentration to the low, Some clay minerals, including smectite and illite are newly formed as one of the reaction products. The continual expansion and shrinkage of the expandible clay minerals, probably due to repeated absorption and loss of water within the structure, plays an important role in the development of cracks within the concrete structure.