• Korean Journal of Remote Sensing
• /
• v.30 no.2
• /
• pp.161-172
• /
• 2014

Established in the lower reaches of the Nakdong river in Busan, the Noksan national industrial complex is one of the deepest soft ground areas in Korea. In case of the costal landfill having deep soft ground, there is a significant residual settlement over a long period of time. In this study, there was observed ground subsidence occurred in the Noksan national industrial complex from September 2002 to April 2007 by applying DInSAR and SBAS time series method using RADARSAT-1 and Envisat SAR datasets. As a result, it was calculated that ground subsidence developed at the velocity of about maximum 10 cm/yr and mean 6 cm/yr at the eastern center, west, western center and southern area contiguous on the coastline of the study area during the period from September 2002 to April 2007. In addition, the RADARSAT-1 average displacement map has been compared with the total displacement map observed by accurate magnetic probe extensometer during the period from 2001 to 2002. Since the time series displacement has shown a linear trend mostly, we consider that continuous monitoring should be needed until the ground subsidence of the study area has been stabilized.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.25 no.3
• /
• pp.85-92
• /
• 2015

SiC crystals are well known for their true potential as high power devices and their crystal growth activity is actively carried out in domestic as well as in abroad. Until now the process to grow this crystal has been done by sublimation technique using radio frequency induction heating method. However in order to get better quality of SiC crystals, the stability of temperature is needed because SiC crystal tends to transform to other polytypes. So, the possibility of SiC crytals growth was evaluated by different heating method. This study aimed to observe whether the resistant heating method would show stable growth and better quality of SiC single crystal than that of RF induction heating. As a result, polycrystalline SiC crystals were grown by the growth rate of 0.02~0.5 mm/hr under the condition of $2100{\sim}2300^{\circ}C$ at the bottom side of the crucible and 10~760 torr. The polycrystalline SiC crystals with 0.25 and 0.5 mm in thickness were grown successfully without seed and characterized by optical stereo microscopic observation.

• Korean Journal of Food Science and Technology
• /
• v.25 no.6
• /
• pp.742-746
• /
• 1993

Retrogradation of legume starches and their gel properties were studied. From DSC results, kidney bean starch retrograded faster than other starches whereas cow pea and mung bean starches retrograded slowly. Retrogradation rate of 1% starch solutions during storage showed similar patterns to the DSC results. During storage, the sags of cow pea and mung bean gels(starch conc., 8%) were slowly increased, but that of kidney bean was rapidly increased. The water mobility of cow pea and mung bean gels, which was measured by NMR, remained unchanged for one day, afterwards decreased slowly, whereas that of red bean and kidney bean gels decreased rapidly through the storage time.

• Geotechnical Engineering
• /
• v.14 no.2
• /
• pp.21-30
• /
• 1998

The settlement characteristics of refuse landfills are peculiar because considerable amount of settlement occurs due to the decomposition of refuse organic solids for very long period. The total amount of compression that occurs due to the decomposition in refuse landfill is mainly dependent on the amount of biodegradable refuse solids and fill Ige of the refuse landfill, and the settlement stabilization speed is dependent on the decomposition condition. In order to figure out the settlement characteristics of refuse landfills. a proposed mathematical model is applied to settlement data of refuse landfills with different fill ages. A data bank of model parameters was obtained and the trends were analyzed. The long-term settlement behavior of refuse landfills can be estimated fairly well by the proposed model. The total remaining amount of settlement may be predicted on the basis of the fill age and appropriate two design parameters.

• Journal of the Korean Ceramic Society
• /
• v.41 no.4
• /
• pp.340-343
• /
• 2004

SrA1$_2$O$_4$was prepared by polymerized complex method and crystalline growth was investigated. Precursors was annealed at temperatures form 900 to 100$0^{\circ}C$, for different time(between 0 and 10 h), and that was determined by Transmittance Electron Microscopy (TEM) and X-Ray Diffractometer (XRD). Crystalline size was calculated by Scherrer's equation and its variation was studied. It increased rapidly in the primary stage and then slowly as a function of square root of time. so, It was grown to 32, 45 and 59nm after heating treatment at 900, 980, and 100$0^{\circ}C$ for 10 h respectively. Cstalline growth rates were 4.5, 9.6, and 18.6 nm/h$^{1}$2/ as a addition of heating temperature.

• Journal of the Korean Geotechnical Society
• /
• v.19 no.6
• /
• pp.61-70
• /
• 2003

The behaviour of an earth and rock-fill dam is complicated due to reservoir water and various materials in zoned dams. Different materials with a wide range of permeability and seasonal variation of reservoir water result in the time dependent post-constructional behaviour. In aged dams it is often required to control water level to keep the dams safe. In this case information on the post-constructional dam behaviour is important. However, present geotechnical knowledge does not fully support the occasion. In this study the post-constructional behaviour of a dam is investigated using coupled finite element models for series of idealized water reservoir cases: impoundment, draw down, seasonal fluctuation with different rising and falling speeds. Numerical results were analysed in respect of geotechnical parameters such as load transfer, hydraulic fracturing potential and stress paths. It is shown that the control of water level is an important factor while operating dams.

• Journal of the Korean Geotechnical Society
• /
• v.27 no.6
• /
• pp.49-61
• /
• 2011

This paper presents the applicability of rheological models for describing fine-laden debris flows and analyzes the flow characteristics as a function of grain size. Two types of soil samples were used: (1) clayey soils - Mediterranean Sea clays and (2) silty soils - iron ore tailings from Newfoundland, Canada. Clayey soil samples show a typical shear thinning behavior but silty soil samples exhibit the transition from shear thinning to the Bingham fluid as shear rate is increased. It may be due to the fact that the determination of yield stress and plastic viscosity is strongly dependent upon interstructrual interaction and strength evolution between soil particles. So grain size effect produces different flow curves. For modeling debris flows that are mainly composed of fine-grained sediments (<0.075 mm), we need the yield stress and plastic viscosity to mimic the flow patterns like shape of deposition, thickness, length of debris flow, and so on. These values correlate with the liquidity index. Thus one can estimate the debris flow mobility if one can measure the physical properties.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.7 no.3
• /
• pp.203-212
• /
• 1987

The hydration and strength of concrete are affected by curing conditions, especially curing temperature. In this paper, the hydration temperature of heated curing concrete specimen are measured by thermo-couples instead of conduction calorimeter, and strengths of concrete are tested. The results of this study show that the compressive strengths of concrete are especially dependent on the curing temperature. And the strength results of concrete agree approximately with the results of approach to the hydration process of cement concrete.

• Korean Journal of Food Science and Technology
• /
• v.24 no.1
• /
• pp.37-41
• /
• 1992

Starch solid system was used to investigate the effects of lipoxygenase, linoleic acid and water activity on the oxidation of ${\beta}-carotene$ or ${\alpha}-tocopherol$. ${\beta}-carotene$ or ${\alpha}-tocopherol$ was co-oxidized severely with linoleic acid by lipoxygenase, and these were reduced to 19% and 5% of initial concentration, respectively, after 2 days storage at $a_w$ 0.72 in the system. The concentration of ${\beta}-carotene$ and the destruction rates were linearly correlated. However, the ${\beta}-carotene$ was very stable in the system without linoleic acid and lipoxygenase. The oxidation products of ${\alpha}-tocopherol$ were considered as ${\alpha}-tocopheryl$ quinone and ${\alpha}-tocopheryl$ dimer, and the level of ${\alpha}-tocopherol$ quinone increased as the reaction time increased.

• Journal of Energy Engineering
• /
• v.5 no.1
• /
• pp.50-55
• /
• 1996

A numerical simulation on a primary calcinator of porcelain was performed with using Fluent to calculate the heat efficiency by studying velocity vector and temperature profile according to variables such as the location of outlet and porcelain. Control-Volume based Finite Difference Method and Up-wind scheme are used for discretization of differential equation. SIMPLEC Algorithm and standard k-$\varepsilon$ turbulent model are selected to resolve the pressure-velocity coupling and the turbulent. The result of simulation showed that the whole velocity vector field in a calcinator was varied greatly according to the location of outlet. But the whole temperature profile at each zone was still high regardless of the location of outlet because of the radiation. But the temperature of a case with a outlet at sidepart of preheating or cooling zone was little high compared to the case with a outlet on the top of preheating zone. The velocity vector field and temperature profile in a calcinator were almost not affected by the location of porcelain, but the temperature inside a porcelain was much affected according to the place where it was located. The heat efficiency in a calcinator was 44.6% and the gas temperature in the outlet was about 1000 K.