• Proceedings of the KSRS Conference
• /
• 1999.11a
• /
• pp.107-114
• /
• 1999

The large-scale distribution of crops Is usually determined by climate. We present the results of a climate-crop prediction based on spatial bio-physical process model approach, implemented in a GIS (Geographic Information System) environment using several regional and global agriculture-environmental databases. The model utilizes daily climate data like temperature, rainfall, solar radiation being generated stocastically by in-built model weather generator to determine the daily biomass and finally the crop yield. Crops are characterized by their specific growing period requirements, photosynthesis, respiration properties and harvesting index properties. Temperature and radiation during the growing period controls the development of each crop. The model simulates geographic/spatial distribution of climate by which a crop-growing belt can also be determined. The model takes both irrigated and non-irrigated area crop productivity into account and the potential increase in productivity by the technical means like mechanization is not considered. All the management input given at the base year 1995 was kept same for the next twenty-year changes until 2015. The simulated distributions of crops under current climatic conditions coincide largely with the current agricultural or specific crop growing regions. Simulation with assumed weather generated derived climate change scenario illustrate changes in the agricultural potential. There are large regional differences in the response across the country. The north-south and east-west regions responded differently with projected climate changes with increased and decreased productivity depending upon the crops and scenarios separately. When water was limiting or facilitating as non-irrigated and irrigated area crop-production effects of temperature rise and higher $CO_2$ levels were different depending on the crops and accordingly their production. Rise in temperature led to yield reduction in case of maize and rice whereas a gain was observed for wheat crop, doubled $CO_2$ concentration enhanced yield for all crops and their several combinations behaved differently with increase or decrease in yields. Finally, with this spatial modeling approach we succeeded in quantifying the crop productivity which may bring regional disparities under the different climatic scenarios where one region may become better off and the other may go worse off.

• The Journal of the Acoustical Society of Korea
• /
• v.21 no.1
• /
• pp.73-81
• /
• 2002

The transmission of vibration energy through beam-plate junctions in vibration intensity analysis called power new analysis (PFA) has been studied. PFA is an analytic tool for the prediction of frequency averaged vibration response of built-up structures at medium to high frequency ranges. The power transmission and reflection coefficients between the semi-infinite beam and plate are estimated using the wave transmission approach. For the application of the power coefficients to practical complex structures, the numerical methods, such as finite element method are needed to be adapted to the power flow governing equation. To solve the discontinuity of energy density at the joint, joint matrix is developed using energy flow coupling relationships at the beam-plate joint. Using the joint matrix developed in this paper, an idealized ship stem part is modeled with finite element program, and vibration energy density and intensity are calculated.

• Journal of Korea Multimedia Society
• /
• v.20 no.3
• /
• pp.520-532
• /
• 2017

Large-scale natural disasters such as typhoon and localized torrential downpour cause widespread human and property damages. Recently, management systems using GIS are being developed to manage such disasters from various angles. Integrated disaster management encompasses diverse areas such as prediction through the computation of disaster information and field support for response. The development of disaster information systems must also consider the installation of various computation modules. Furthermore, GIS is generally included for realistic description of the field situation and for spatial operations. This study aims to develop the core module of a visualization platform for the 3D GIS services of integrated disaster information using Unity engine This system will enable integrated disaster management from various angles, encompassing disaster prevention experts, field support personnel, and citizens.

• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.26 no.2
• /
• pp.369-375
• /
• 2016

Most companies are willing to spend money on security systems such as DRM, Mail filtering, DLP, USB blocking, etc., for data leakage prevention. However, in many cases, it is difficult that legal team take action for data case because usually the company recognized that after the employee had left. Therefore perceiving one's resignation before the action and building up adequate response process are very important. Throughout analyzing DRM log which records every single file's changes related with user's behavior, the company can predict one's resignation and prevent data leakage before those happen. This study suggests how to prevent for the damage from leaked confidential information throughout building the DRM monitoring process which can predict employee's resignation.

• Atmosphere
• /
• v.26 no.4
• /
• pp.635-647
• /
• 2016

The effects of sea surface temperature (SST) gradient induced by the previous typhoon on the following typhoon motion over East Asia have been investigated using Weather Research and Forecasting (WRF) model for the previous Typhoon Bolaven (1215) and following Typhoon Tembin (1214). It was observed that Typhoon Bolaven remarkably reduced SST by about $7^{\circ}C$ at Yellow Sea buoy (YSbuoy). Using the WRF experiments for the imposed cold wake over West of Tembin (WT) and over East of Tembin (ET), this study demonstrates that the effects of eastward SST gradient including cold wake over WT is much significant rather than that over ET in relation to unexpected Tembin's eastward deflection. This difference between two experiments is attributed to the fact that cold wake over WT increases the magnitude of SST gradient under the eastward SST gradient around East Asia and the resultant asymmetric flow deflects Typhoon Tembin eastward, which is mainly due to the different atmospheric response to the SST forcing between ET and WT. Therefore, it implies that the enhanced eastward SST gradient over East Asia results in larger typhoon deflection toward the region of warmer SST according to the location of the cold wake effect. This result can contribute to the improvement of track prediction for typhoons influencing the Korean Peninsula

• Journal of the Korean Institute of Gas
• /
• v.24 no.5
• /
• pp.47-55
• /
• 2020

Hazardous materials accidents are not limited to the leakage of the material, but if the early response is not appropriate, it can lead to a fire or an explosion, which increases the scale of the damage. However, as the 4th industrial revolution and the rise of the big data era are being discussed, systematic analysis of hazardous materials accidents based on new techniques has not been attempted, but simple statistics are being collected. In this study, we perform the systematic analysis, using machine learning, on the fire accident data for the past 11 years (2008 ~ 2018), accumulated by the National Fire Service. The analysis results are visualized and presented through text mining analysis, and the possibility of developing a damage-scale prediction model is explored by applying the regression analysis method, using the main factors present in the hazardous materials fire accident data.

• Structural Engineering and Mechanics
• /
• v.53 no.5
• /
• pp.997-1016
• /
• 2015

The contribution of tensioned concrete between cracks (tension-stiffening) cannot be ignored when analysing deformation of reinforced concrete elements. The tension-stiffening effect is crucial when it comes to adequately estimating the load-deformation response of steel reinforced concrete and the more recently appeared fibre reinforced polymer (FRP) reinforced concrete. This paper presents a unified methodology for numerical modelling of the tension-stiffening effect in steel as well as FRP reinforced flexural members using the concept of equivalent deformation modulus and the smeared crack approach to obtain a modified stress-strain relation of the reinforcement. A closed-form solution for the equivalent secant modulus of deformation of the tensioned reinforcement is proposed for rectangular sections taking the Eurocode 2 curvature prediction technique as the reference. Using equations based on general principles of structural mechanics, the main influencing parameters are obtained. It is found that the ratio between the equivalent stiffness and the initial stiffness basically depends on the product of the modular ratio and reinforcement ratio ($n{\rho}$), the effective-to-total depth ratio (d/h), and the level of loading. The proposed methodology is adequate for numerical modelling of tension-stiffening for different FRP and steel reinforcement, under both service and ultimate conditions. Comparison of the predicted and experimental data obtained by the authors indicates that the proposed methodology is capable to adequately model the tension-stiffening effect in beams reinforced with FRP or steel bars within wide range of loading.

• Computers and Concrete
• /
• v.7 no.4
• /
• pp.347-364
• /
• 2010

Since its invention in the $19^{th}$ century, Reinforced Concrete (RC) has been widely used in the construction of a lot of different structures, as buildings, bridges, nuclear central plants, or even ships. The details of the mechanical response for this kind of structures depends directly upon the material behavior of each component: concrete and steel, as well as their interaction through the bond-slip, which makes a rigorous engineering analysis of RC structures quite complicated. Consequently, the practical calculation of RC structures is done by adopting a lot of simplifications and hypotheses validated in the elastic range. Nevertheless, as soon as any RC structural element is working in the inelastic range, it is possible to obtain the numerical prediction of its realistic behavior only through the use of non linear analysis. The aim of this work is to develop a new kind of Finite Element: the "Enhanced Solid Element (ESE)" which takes into account the complex composition of reinforced concrete, being able to handle each dissipative material behavior and their different deformations, and on the other hand, conserving a simplified shape for engineering applications. Based on the recent XFEM developments, we introduce the concept of nodal enrichment to represent kinematics of steel rebars as well as bonding. This enrichment allows to reproduce the strain incompatibility between concrete and steel that occurs because of the bond degradation and slip. This formulation was tested with a couple of simple examples and compared to the results obtained from other standard formulations.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.34 no.5
• /
• pp.30-38
• /
• 2006

A new calibration method for five-hole pressure probe is presented. This method provides accuracies better than those based on the traditional regression method. The calibration algorithm uses a single sector interpolation response surface calculated by comparing the regression curve fits with the actual calibration data. A five-hole pressure probe with hemispherical tip was fabricated and calibrated at Reynolds number of $4.11{\times}10^6$/m and flow angle of ${\pm}48$ degrees. Two data prediction models, the least-square regression and a single sector error interpolation, were evaluated. The comparison of these two calibration methods to a five-hole probe is described and discussed. An evaluation of the calibration accuracy is also given.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.38 no.2
• /
• pp.135-140
• /
• 2010

A new treatment is proposed to handle a deflection limit in the open-loop-onset-point (OLOP), which is commonly used in the prediction of pilot in-the-loop oscillation (PIO) due to a rate saturation. The new approach is motivated by the frequency response of a stand-alone actuator in that, unlike the suggestion by the original OLOP procedure, the rate limit onset is not delayed to a higher frequency by a deflection limit. Indeed, if a feedback control loop is closed, the rate limit onset can be shifted to a lower frequency since the controller tends to react with larger commands when deflection limited. The amplitude of the command at this onset frequency is combined with the deflection limit to estimate the associated gain reduction in the open-loop-onset-point in the final step of the OLOP process. The comparison of the new approach with the previous method reveals that an inaccurate optimism which can occur in the previous method is corrected by the proposed treatment.