• Journal of the Korea Institute of Military Science and Technology
• /
• v.9 no.3
• /
• pp.41-47
• /
• 2006

Naval combat system is total management system integrating a ship and several weapon system functions. For the mission of a ship, naval combat system manages features and constraints of each weapon system. Proper treats of each weapon system's conditions guarantee effective performances of naval combat system. In this paper, the relationship of anti-air weapon system's on board position and self-defence effectiveness against anti-surface missiles is studied

• The Transactions of the Korean Institute of Electrical Engineers A
• /
• v.55 no.6
• /
• pp.236-241
• /
• 2006

This paper presents a transfer capability enhancement process using VSC HVDC system which can control active power as well as reactive power. The transfer capability is constrained by stability like voltage stability as well as thermal rating of power system components. Transfer capability of the power system limited by these constraints may be enhanced by reactive power control ability and active power flow control ability of the VSC HVDC system. To enhance the transfer capability of the system using VSC HVDC, selection of the HVDC installation site is performed. In this work, power zones which consist of major power plants and their sinks are identified using power tracing and distribution factor. Alternative route of major AC transmission line in the power zone is identified as VSC HVDC system.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
• /
• 2006.11a
• /
• pp.197-200
• /
• 2006

The portion of thin plate is expected to increases as to the development of design and fabrication technology. The weld-induced deformation is more serious in thin plates than in thick plates because heat affect zone of thin plates is wider than that of thick plates, and in addition internal and external constraints much more influence upon weld-induced deformation of thin plates. This paper deals with the application of the mechanical tensioning method to fillet weld of thin plates to reduce the weld-induced deformation. For this, fillet welding test have been carried out for several thin plate specimens with varying plate thickness and magnitude of tensile load. From the present study, it has been found that the tenssoning method is effective on reduction of weld-induced deformation.

• Journal of the Society of Naval Architects of Korea
• /
• v.44 no.6
• /
• pp.590-597
• /
• 2007

The portion of thin plate is expected to increases as to the development of design and fabrication technology. The weld-induced deformation is more serious in thin plates than in thick plates because heat affect zone of thin plates is wider than that of thick plates, and in addition internal and external constraints much more influence upon weld-induced deformation of thin plates. This paper is aimed at applying the mechanical tensioning method to fillet weld of thin plates to reduce the weld-induced deformation. For this purpose, fillet welding tests have been carried out for several thin plate specimens with varying plate thickness and magnitude of tensile load. From the present study, it has been found that the tensioning method is effective on reduction of weld-induced deformation.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2009.05a
• /
• pp.172-175
• /
• 2009

The purpose of this study is to predict the forming limit diagram (FLD) of strain-rate sensitive materials on the basis of the Marciniak and Kuczynski (M-K) theory. The strain-rate effect is taken into consideration in such a way that the stress-strain curves for various strain-rates are inputted into the formulation as point data, not as curve-fitted models such as power function. To solve the nonlinear system of equations derived from the equilibrium and constraints in the groove region and the safe zone, the Newton-Raphson method is used. The theoretical FLDs using four different yield criteria, that are von Mises, Hill (1948), Hill (1979), Logan and Hosford, are compared with the experimental, numerical (FEA) and other theoretical results. A new trial is made where a modified M-K model having n-step grooves is introduced to describe a real localized neck.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.18 no.4
• /
• pp.913-919
• /
• 2014

This study regards to a method how to select the optimized earth retaining technology among four target technologies which are applied to underground construction work by analyzing relative weight values of major influence factors. In this study, major affected zone and influence factors are analyzed through questionnaire survey to select a suitable earth retaining technology for downtown area, and an optimized earth retaining technology is proposed by using the matrix analysis based on them. Also, by systematically analyzing the weight values and methods of alternatives selection through consideration the importance of alternatives evaluation criteria, the importance of affected zones is evaluated to determine the optimized alternative. It is concluded that when performing the analysis to select the earth retaining technology which should consider a variety of constraints, the convergence with information processing technology in the field of IT is effective to analyze and optimize many constraints.

• Journal of Electrical Engineering and Technology
• /
• v.9 no.1
• /
• pp.15-26
• /
• 2014

This paper proposes a Modified Particle Swarm Optimization with Time Varying Acceleration Coefficients (MPSO-TVAC) for solving economic load dispatch (ELD) problem. Due to prohibited operating zones (POZ) and ramp rate limits of the practical generators, the ELD problems become nonlinear and nonconvex optimization problem. Furthermore, the ELD problem may be more complicated if transmission losses are considered. Particle swarm optimization (PSO) is one of the famous heuristic methods for solving nonconvex problems. However, this method may suffer to trap at local minima especially for multimodal problem. To improve the solution quality and robustness of PSO algorithm, a new best neighbour particle called 'rbest' is proposed. The rbest provides extra information for each particle that is randomly selected from other best particles in order to diversify the movement of particle and avoid premature convergence. The effectiveness of MPSO-TVAC algorithm is tested on different power systems with POZ, ramp-rate limits and transmission loss constraints. To validate the performances of the proposed algorithm, comparative studies have been carried out in terms of convergence characteristic, solution quality, computation time and robustness. Simulation results found that the proposed MPSO-TVAC algorithm has good solution quality and more robust than other methods reported in previous work.

• Journal of Forest and Environmental Science
• /
• v.39 no.3
• /
• pp.180-194
• /
• 2023

This study characterize, classify and evaluates the function of topography on spatial variability of some selected soil properties to assist in designing land management that support uniform agricultural production. The study site, an agricultural land, was part of the derived savanna zone in southwest Nigeria. Four soil profile pits each were established along two delineated toposequence and described following the FAO/UNESCO guidelines. Samples were collected from the identified genetic horizons. Properties of four soil series developed on different positions of the two delineated Toposequence viz upper, middle, lower slopes and valley bottom positions respectively were studied. The soil samples were analysed for selected physical and chemical properties and data generated were subjected to descriptive and inferential statistics. The results showed that soil colour, depth and texture varied in response to changes in slope position and drainage condition. The sand content ranged from 61 to 90% while the bulk density ranged between 1.06 g cm^-3 to 1.68 g cm^-3. The soils were neutral to very strongly acid with low total exchangeable bases. Available phosphorus value were low while the extractable micronutrient concentration varied from low to medium. Soils of Asejire and Iwo series mapped in the study area were classified as Typic isohyperthermic paleustult, Apomu series as Plinthic isohyperthermic paleustult and Jago series as Aquic psamment (USDA Soil Taxonomy). These soils were correlated as Lixisol, Plinthic Lixisol and Fluvisol (World Reference Based), respectively. Major agronomic constraints of the soils associations mapped in the study area were nutrient availability, nutrient retention, slope, drainage, texture, high bulk density and shallow depth. The study concluded that the soils were not homogenous, shows moderate spatial variation across the slope, had varying potentials for sustainable agricultural practices, and thus, the agronomic constraints should be carefully addressed and managed for precision agriculture.

• Computational Structural Engineering
• /
• v.8 no.2
• /
• pp.85-93
• /
• 1995

This study presents the formulation of beam transition elements and transition zone elements for the effective finite element analysis of the transition regions of coupled wall structures. Beam transition element can be described as the quasi beam element which is replaced by an equivalent plane stress element, keeping equally, the basic behavior of beam element, based on the kinematic and force constraints between beam and wall element. These beam transition elements solve the incompatibility related to different degrees of freedom between beam and wall element in transition regions. Also, the stiffness matrices of transition zone elements which are directly connected with beam transition elements in transition regions can be derived from the equivalent constraint conditions. These elements provide the reasonable mesh grading schemes for transition regions and can be usefully applied to the transition regions of all structures that the interactions of wall and beam element are considered.

• Economic and Environmental Geology
• /
• v.31 no.2
• /
• pp.101-110
• /
• 1998

The purpose of this study is to elucidate the source of U anormaly formed in stream water of the drainage system around the Shinbo talc mine area based on the hydrochemical properties of water masses including surface water and groundwater. The hydrochemical properties of water masses in the Shinbo talc mine area are divide into three types; Type I : $Ca(Mg)SO_4$ type with high U content as shown in the stream water flowout from the mine, Type II : $Ca(HCO_3)_2$ type with high U content as in deep groundwater, Type III : $Ca(HCO_3)_2$, type with low U content as in the other stream water and shallow groundwater. It is necessary to emphasize that in deducing the uranium source, a distinct discrimination between type I and type II is showed in their hydrothermal properties in spite of commonly having a high uranium content, which in turn means the occurrence of a different water-rock interaction processes between both type. All evidences suggest that type II groundwater have acted as a primary media in the transport of uranium and that, as the groundwater flows through the talc mineralization zone, water composition of type II was transformed into that of type I water as the results of a secondary water rock interaction process, caused by imposition of new mineralogically controlled thermodynamic constraints. Consequently, in the viewpoint of hydrochemical exploration, the investigation of the hydrologic circulation system and the hydrogeologic properties for the aquifer of type II groundwater shall be done first of all and will provide a crucial clue on tracing the uranium mineralization zone occurred in the Shinbo talc mine area.