• Geophysics and Geophysical Exploration
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• v.4 no.4
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• pp.124-132
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• 2001

Electrical resistivity survey has been conducted for delineating geological fault structure in Kaekok-ri near Kyungju. In general, electrical resistivity survey has an advantage of searching buried faults and its traces compared with other geophysical survey methods. Distribution of electrical conductivity in the ground is influenced by the ratio of pores, groundwater and clay minerals. These properties are evidenced indirectly to explain for weathering condition, faults and fracture Bones. Thus the electrical resistivity survey can be an effective method to find buried faults. We have carried out two dimensional (2-D) interpretation by means of smoothness-constrained least-squares and finite element method. Field data used in this paper was acquired at Kaekok-ri, Wuedong-eup, Kyungju-si, where is Ulsan Fault and is close to the region in which debatable quaternary fault traces were found recently. The dipole-dipole array resistivity survey which could show the 2-D subsurface electrical resistivity structure, was carried out in the area with three lines. The results showed good property of fault, fracture zone and fault traces which we estimated were congruous with the results. Through this study, 2-D electrical resistivity survey interpretation for fault is useful to apply.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.3
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• pp.269-275
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• 2020

RAM of elements to support weapon systems is conducted at the initial development phase and standard is suggested to accomplish strategy requirement performance from a design spec. Operational availability is a key point of the military's ability to ensure combat readiness and to win the battle. In the weapon system development phase, operational availability is used as a development standard. The military provides ALDT, operation and standby time, which are elements of operational availability. ALDT is a key element of operational availability that must be maintained for combat readiness, as it depends on the aging of a weapon system, maintenance policies and geographical conditions. Operational Availability to be set at the development phase has many differences from the operational availability that is analyzed in the actual operational phase because ALDT is applied as a simple assumption. In the paper, we analyzed ALDT applying the decision tree method through failure data acquired from initial operation. Through this study, we have devised the optimal ALDT setting method to achieve operational availability about operation when the weapons system is unstable.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.36 no.4
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• pp.329-336
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• 2000

Welding is a important technological method in mechanical engineering. $CO_2$MAG(metal active gas) welding means that metal part in double capstan drum for the inshore and costal vessels are joined by melting(with or without a filler material) or that new material is added to a metal part by melting. The thermal stresses appear due to a non-uniform temperature field, inhomogeneous material properties, external restraint and volume changes during phase transformations. In this study analysis the elasto-plastic thermal stresses distribution of welding part in double capstan drum for the inshore and costal vessels using finite element method (FBM). Therefore it calculates the numerical value that can be applied to the optimum design of welding parts and the shapes. The significant results obtained in this study are summarized as fellows. At early stage of the cooling after welding process, the abrupt thermal stresses gradient has been shown in the vicinity of welding part. In the thermal stresses analysis due to temperature gradient and heat shocking maximum stress was occurred of welding part and stresses were distributed from 54MPa~48MPa.

• International Journal of Highway Engineering
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• v.6 no.1 s.19
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• pp.47-56
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• 2004

To determine the pure bond strength between substrate and its overlayed concrete material, a direct pull-off test method was introduced by using a bi-material cylinder with which a penny-shaped crack was mountained at its interface. First, to evaluate the stress magnification or concentration at the interface, the energy release rates of a penny-shaped interface crack in remote tension loading on a bi-material cylinder were determined in terms of different modulus ratios and undonded area ratios(crack ratios) using a commercial finite element program. Then the energy release rates were calibrated as non-dimensional values in consideration of structural dimensions and applied forces. And to evaluate whether this new pull-off test method gives sound test results, three different sizes of unbended area ratios were incorporated along their interface in bi-material cylinders(sulphur polymer concrete + old concrete). Test results showed that all specimens were broken off at their interfaces as intended. Also the FEM analyses and test results indicated that a bi-material specimen with unbended area ratio of 0.4$\sim$0.6 is suitable for best accurate testing.

• Journal of Korean Society for Geospatial Information Science
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• v.3 no.2 s.6
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• pp.43-61
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• 1995

The national land use plan that targets the whole national land and all kinds of urban plans that targets a city or a part of city must be performed continuously now and after that. Therefore, the importance of land use plan, that is included in those plans, is very big and crucial. This study scrutinizes the detail zoning land suitability analysis which bases on urban basis plan and the GSIS application plan about allocation, applied various basic theory which is arranged in that course to study area, and try to develop the land use suitability analysis system, a application system The programing language used in system development is the AML of ARC/INFO. On this study, the results divide into four parts. First, we develop the land use suitability analysis system and can simplify and automatize a complicated analysis course and this system will be more useful to the land use suitability analysis. Second, the analysis range is expanded, considering the circumstance environmental factor of planning area outside. So we can implement more comprehensive analysis. Third, we apply a precedency conception and a legal restrictive element that base on urban characteristics and urban space structure theory to this study, develop a computerized method about distributive method, and can allocate the detail zone in the various ways. Finally, the next studies that can clear the detail zone suitability criteria and the correlation of the relationship of materials are essential to improve the accuracy and confidence in this analysis.

• Journal of the Korean Society for Marine Environment & Energy
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• v.11 no.1
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• pp.13-23
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• 2008

In coastal region, eutrophication, Do deficit and red tide are frequently occurred by influx of fresh water. When the fresh water containing pollutants is discharged into the sea, the surrounding water is contaminated by dispersion of freshwater flowing into coastal waters. The prediction and analysis about the dispersion process of the discharged fresh water should be conducted. A modeling system using GUI was developed to simulate hydrodynamic flow and fresh water dispersion in coastal waters and to analyze the results efficiently. The modeling module of the system includes a tide model using a finite element method and a fresh water dispersion model using a particle-tracking method. This system was applied to predict the tidal currents and fresh water dispersion in Mokpo coastal zone. To verify accuracy of the hydrodynamic model, the simulation results were compared with observed sea level and time variations of tidal currents showing a good agreement. The fresh water dispersion was verified with observed salinity distribution. The dispersion model also was verified with analytic solutions with advection-diffusion problems in 1-dimensional and 2-dimensional simple domain. The system is operated on GUI environment, to ease the model handling such as inputting data and displaying results. Therefore, anyone can use the system conveniently and observe easily and accurately the simulation results by using graphic functions included in the system. This system can be used widely to decrease the environmental disaster induced by inflow of fresh water into coastal waters.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.1
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• pp.80-87
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• 2016

In this work, we conduct a thermal pointing error analysis of the observation satellites considering seasonal and daily temperature variation with interpolated temperature based on prescribed average temperature (PAT) method. Maximum 200 degree temperature excursion is applied to the observation satellites during on-orbit operation, which cause the line of sight (LOS) to deviate from the designated pointing direction due to thermo-elastic deformation. To predict and adjust such deviation, the thermo-elastic deformation analysis with a fine structural finite element model is accomplished with interpolated thermal maps calculated from the results of on-station thermal analysis with a coarse thermal model. After verifying the interpolated temperatures by PAT with two benchmark problems, we evaluate the thermal pointing error.

• The Korean Journal of Archival Studies
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• no.25
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• pp.233-278
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• 2010

An interest in various description of history was increased, resolutely breaking away from the existing frame also in a historical science world, under the influence of post-modernism arisen from the mid 20th century, and for this, oral history archives and oral history methodology began to attract the attention in various academia including archival science as a method for a new writing of history. Also, under the circumstance of korea having a difficulty in performing a whole reconstruction of modern age history and a liquidation of past affairs due to an absolute lack of archives, the tendency is toward more active management of oral history archives and establishing oral history archives in the context of an excavation of new archives and a reinterpretation of history, owing to the necessity in a particular situation. This article started with a critical mind regarding an absence of a collecting policy which can help an effective development of collection from a point of view of archival science, with regard to oral history archives that recently shows a rapid increase of an interest. For this, this article intended to present an new element of a collecting policy besides the study on a collecting policy performed meanwhile by an archival science world by noticing a characteristic and a collecting method of oral history archives, this can be examined largely through 'a statement of mission and collection purpose', 'a policy of collection at large', 'a definition of maintenance and use of the holdings', and 'a guide for a development of collection', and add a proposal regarding a plan to embody the parr which should be actually applied to collection of oral history archives among the existing constituents.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.5
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• pp.344-357
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• 2019

Operational failures may occur even though there had been no signs of defect during the manufacturing process, which may be caused due to exposure to environmental stress which had not been addressed properly during the design process. It is thus necessary to perform environmental testing to determine the cause of the failures. Environmental testing is also used to determine whether a materiel has enough tolerance to the environmental stress during its operation. In this study, the method and level for each environmental testing are properly tailored and applied to a fight aircraft intended to operate in ROK (Republic of Korea), based on the MIL-STD-810G Change 1. Since each part of a fighter aircraft may be exposed to each different environment, LRUs (Line Replaceable Units) exposed to similar environment should be tested similarly. In addition, the decision whether to apply specific test and the tailoring technique in test level were derived for natural and induced environments, respectively. As a fight aircraft is assumed to operate in ROK, the tailoring of test methods and test level to fit to the environment in Korean peninsula is necessary. Further research is needed in determining a specific procedure and a specific level in a test method, and also in determining the test sequence, when conducting more than one is needed, because it can alter test results and it hence becomes an essential element in test design.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.12
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• pp.1646-1653
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• 2020

In case that the train driving with diverse high-speeds is manipulates by real-time remote control in long-term evolution-railway (LTE-R) system with frequent handovers, the real-time safe transmission of train control messages is important element. The handover delay time stability method regardless of train speed in order to enhance the real-time remote train control stability in LTE-R system is proposed in the paper. Furthermore, the variable speeds and altitudes of train collected by real measurements are applied for upgrading simulation accuracy. The simulation results inform that not only there are stable and unstable ranges to A3 offset values, but the optimal offset value for average handover delay is in unstable range. However, the late handover with A3 offset values in stable range should be chosen to get the predictable handover delay regardless of train speed rather than the early handover with A3 offset values in unstable range, since the key value of high-speed Korea railway system is the stability.