• Journal of the Korean GEO-environmental Society
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• v.6 no.1
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• pp.23-31
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• 2005

The "Silt Pond" is 180 hectares in size and contained ultra soft slurry-like soil varying between 3 to 20 meters in thickness. Reclamation works in the Silt Pond commenced in the mid of 1990s. A considerable amount of subsurface investigation inclusive of sampling, field vane and density logging tests were carried out prior to the reclamation of the Silt Pond. Since material in the Silt Pond is extremely soft, filling was done by spreading sand with high water content in thin and equal thickness lifts, allowing the stability of the slurry-like foundation. Despite the extreme care taken, failures occurred during the sand spreading phase. A large piece of high strength geotextile measuring $900m{\times}700m$ was placed to strengthen the slurry like soil foundation at locations where the ultra-soft soil was found to be exposed. Following the remedial works, the Silt Pond was again reclaimed by sand spreading up to +4.0m CD. The success of the reclamation was confirmed by marine CPT profiling.

• Plant Journal
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• v.13 no.4
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• pp.48-50
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• 2017

A program for analyzing the transient behaviors of industrial gas turbines was developed. Each component (compressor, combustor, turbine and ducts)of gas turbine is modeled as a fully module to enhance the expandability of the program. We used object-oriented programing for this purpose. The mass and energy balance equations are solved numerically by Multivariable Newton Raphson method. The characteristic maps for the compressor and turbine were used for predicting the performance of a gas turbine engine. Combustion in the combustor is assumed to be complete combustion. PID control is used to maintain constant rotational speed and turbine exhaust temperature by the control of the fuel flow rate and the changing of the compressor inlet guide vane angle at the same time. It was confirmed that stable control of the gas turbine was possible, even for a rapid load change.

• Proceedings of the National Institute of Ecology of the Republic of Korea
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• v.2 no.1
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• pp.26-31
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• 2021

Reproduction and molt are costly processes in avian life histories. These two fitness-related traits are expected to be under one of physiological trade-offs. Age-related molt is known to be higher in young birds than that in adults presumably due to the cost of reproduction in adults. The present study partially replicated a previous study using a non-invasive method of seasonal wing feather loss instead of capture-inspection for molting progress in oriental storks (Ciconia boyciana). We first examined characteristics of the known six wing feather types (i.e., primaries [P], primary coverts [PC], secondaries [S], secondary coverts [SC], and tertials [T]) from two specimens with four wings. Results were utilized as references for further investigation. We then collected a total of 3,807 wing feathers shedded by 61 captive storks for one year and classified them into six wing feather types based on the reference with structures of vane (i.e., how asymmetrical) and calamus (i.e., how rigidly attached to skin) of wing feathers. Our results indicated that annual losses of all six-type wing feathers decreased with increasing ages, ranging from 29% to 58% for PC, alula, SC, P, S, and T in order. Our results were also comparable to those of a former study, suggesting that the pattern of age-specific molt might be associated with the cost of reproduction in adults. However, juveniles might shed more wing feathers with low quality formed during the previous development stage than older birds.

• Journal of the Korean Geotechnical Society
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• v.23 no.5
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• pp.89-100
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• 2007

In this study, various field and laboratory tests were performed to investigate the characteristics of shear strength and bearing behavior to be considered in the estimation of stability and trafficability in early stage of stabilization process in marine clay dredged deposit. Site characterization was carried out to grasp the basic properties of the deposit. Field vane test, unconfined compression test and direct shear test were conducted to evaluate the shear strength distribution for varied depths, and the characteristics of shear strength and stress-strain behavior of the crust layer. Plate load tests were also performed to estimate the bearing capacity and to assess load-settlement behavior and failure pattern of the deposit. The bearing capacity was also estimated using previously proposed methods for double-layered clay deposit. The estimated bearing capacity was compared with the results of the plate load tests and then, the applicability of the estimation method was discussed.

• Journal of the Korean Society of Propulsion Engineers
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• v.19 no.5
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• pp.1-14
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• 2015

In case of a gas turbine engine for supersonic operation, the engine have a wide range of operating inlet mass flow rate and required high performance such as thrust and fuel consumption. Therefore, variable system and its optimal control logic are essentially needed. In this work, a method for performance prediction of a gas turbine engine with variable system compressor and its control scheme were developed. Conceptual design of compact acuation system for the operation of the variable system was also conducted. The performance of a low-bypass ratio mixed flow turbofan engine was analyzed, and it was observed that the surge margin of the engine is improved at off-design condition by applying the control scheme.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.10
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• pp.4666-4672
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• 2011

Performance of NOx removal in SCR(Selective Catalytic Reduction) process depends on such various factors as catalyst factors (catalyst composition, catalyst form, space velocity, etc.), temperature of exhaust gas, and velocity distribution of exhaust gas. Especially the flow uniformity of gas stream flowing into the catalyst layer is believed to be the most important factor to influence the performance. In this research, the flow characteristics of a SCR process at design stage was simulated, using 3-dimensional numerical analysis method, to confirm the uniformity of the gas stream. In addition, the effects of guide vanes, baffles, and perforated plates on the flow uniformity for the inside and catalyst layer of the reactor were studied in order to optimize the flow uniformity inside the SCR reactor. It was found that the installation of a guide vane at the inlet duct L-tube part and the installation of a baffle at the upper part is very effective in avoiding chaneling inside the reactor. It was also found that additional installation of a perforated plate at the lower part of the potential catalyst layer buffers once more the flow for very uniform distribution of the gas stream.