• Journal of KSNVE
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• v.9 no.2
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• pp.377-386
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• 1999

This paper is a study on model method for estimating system inputs from vibration responses, which is one of indirect input identification methods in frequency domain. The method has advantages over direct inverse method especially when points of operational inputs are inaccessible so that artificial excitation forces cannot be applied to obtain frequency response functions of the complete system. Procedures of extended modal model method are proposed and checked by numerical experiment. Mechanisms of error propagation, i.e., how errors in modal parameters such as poles nad mode shape vectors affect estimation of the input forces, are illustrated. Then, in order to counteract the error propagation, discrete modal filter approach is taken in this paper to compute the inversion of modal matrix in which the most serious errors seem to be generated. Further, a Reduced form of Modified Reciprocal Modal Vector(RMRMV) is proposed for estimating multiple inputs. It is shown to have smaller orthogonality error than MRMV.

• Korean Journal of Remote Sensing
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• v.24 no.5
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• pp.473-481
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• 2008

This paper presents an approach to Back-propagation and Radial Basis Function neural network method with various training set for automatic vehicle detection from aerial images. The initial extraction of candidate object is based on Mean-shift algorithm with symmetric property of a vehicle structure. By fusing the density and the symmetry, the method can remove the ambiguous objects and reduce the cost of processing in the next stage. To extract features from the detected object, we describe the object as a log-polar shape histogram using edge strengths of object and represent the orientation and distance from its center. The spatial histogram is used for calculating the momentum of object and compensating the direction of object. BPNN and RBFNN are applied to verify the object as a vehicle using a variety of non-car training sets. The proposed algorithm shows the results which are according to the training data. By comparing the training sets, advantages and disadvantages of them have been discussed.

• Structural Engineering and Mechanics
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• v.59 no.5
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• pp.901-920
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• 2016

MeshFree methods have become popular owing to the ease with which high stress gradients can be identified and node density distribution can be reformulated to accomplish faster convergence. This paper presents a strategy for nodal density refinement with strain energy as basis in Element-Free Galerkin MeshFree technique. Two popular flat plate problems are considered for the demonstration of the proposed strategies. Issue of integration errors introduced during nodal density refinement have been addressed by suggesting integration cell refinement. High stress effects around two symmetrical semi-circular notches under in-plane axial load have been addressed in the first problem. The second considers crack propagation under mode I and mode II fracture loading by the way of introducing high stress intensity through line crack. The computational efficacy of the adaptive refinement strategies proposed has been highlighted.

• Journal of Integrative Natural Science
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• v.5 no.3
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• pp.175-181
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• 2012

Oxepane high explosives substituted to explosive group such as azido, nitrato and hydrazino are investigated theoretically the acid catalyzed reaction using the semiempirical MINDO/3, MNDO and AM1 methods to use as the guidelines of high explosives. The nucleophilicity and basicity of oxepane high explosives can be explained by the value of negative charge on oxygen atom of oxepane and the reactivity in propagation step can be represented by the value of positive charge on carbon atom and low electrophile LUMO energy. It was known that carbenium ion was favorable due to the stable energy (19.507~32.101 Kcal/mol) between oxonium ion and carbenium ion in the process of cyclic oxonium ion of oxepane high explosives being converted to open carbenium ion in oxepane high explosives. The value of concentration of cyclic oxonium ion and open carbenium ion in equilibrium status was found to be a major determinant of mechanism, it was expected to react faster in the prepolymer propagation step in SN1 mechanism than in that of $S_N2$.

• Journal of Positioning, Navigation, and Timing
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• v.10 no.3
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• pp.207-214
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• 2021

A new positioning technique for positioning of LTE base stations is proposed. The positioning information of the base station is absolutely necessary for model-based wireless positioning, and is required in some of the various merhodologies for estimating signals in an uncorrected area when construnting a database for fingerprinting-based positioning. Using the acquired location-based Reference Signal Received Power (RSRP) information to estimate the location of the base station, it is impossible with the existing trilateration methods. Therefore, in this paper, a method using reference particles is proposed. Particles are randomly generated in the application area, and signal propagation modeling is performed assuming that a base station is located in each particle. Based on this, the errors of measurements are calculated. The particle group with the minimum measurement errors is selected, the position of the base station is estimated through weighted summation, and the signal propagation model of the corresponding base station is built at the same time. The performance of the proposed technology is verified using data acquired in Seocho-dong, Seoul.

• Journal of Ocean Engineering and Technology
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• v.38 no.3
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• pp.87-102
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• 2024

Given the inadequate regulatory framework for liquefied hydrogen gas storage tanks on ships and the limitations of the IGC Code, designed for liquefied natural gas, this study introduces a critical assessment procedure to ensure the safety and suitability of such tank designs. This study performed a heat transfer analysis for boil-off gas (BOG) calculations and established separate design load cases to evaluate the yielding and buckling strength. In addition, the study assessed methodologies for both high-cycle and low-cycle fatigue assessments, complemented by comprehensive structural integrity evaluations using finite element analysis. A comprehensive approach was developed to assess the structural integrity of Type C tanks by conducting crack propagation analysis and comparing these results with the IGC Code criteria. The practicality and efficacy of these methods were validated through their application on a 23K-class liquefied hydrogen carrier at the concept design stage. These findings may have important implications for enhancing safety standards and regulatory policies.

• Journal of the East Asian Society of Dietary Life
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• v.14 no.6
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• pp.608-617
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• 2004

This study is conducted to find out the appropriate preparing method and fermenting condition through analysis of physicochemical, microbiological, sensory evaluation of Myungtae sikhae, Korean fermented fishery food which was prepared in simplified and conventional methods. During the fermentation of sikhae at 4℃, pH was decreased gradually, but acidity was increased and salinity was steady state. In this aspect, no significant difference was revealed between sikhae prepared in simplified and conventional methods. Under fermentation at 20℃ and kept at 4℃, pH was decreased to 4.6～4.9 for 15～20 days fermentation with steady state of salinity. However, acidity was changed in conversely. The content of reducing sugar with rapidly decreasing in the beginning of fermentation was continually decreased. The propagation of microorganism in th sikhae depends on the fermentation temperature rather than the preparing methods. Generally low propagation of microorganism began to increase gradually in the sikhae fermented at 4℃ comparing to that fermented at 20℃. In the sikhae fermented at 20℃ and kept at 4℃, the total count including lactic acid bacteria, was rapidly increased after 5 days' fermentation of sikhae is dominated by Lactobacillus sp. and the unique flavor and organic acid were contributed by this flora with Leuconostoc. sp. By the sensory evaluation, the best flavor was revealed in the sikhae, prepared in simplified method fermented for 30 days at 4℃. Until 20 days, sikhae fermented at 20℃ revealed higher score than fermented at 4℃. General preference for the sikhae fermented at 4℃ for 15 days prepared by simplified method and those fermented at 20℃ for 10 days. The sikhae, fermented at 4℃, showed less difference between preparing methods and preferable acceptability after being 25 days. The best acceptability of sikhae fermented at 20℃ showed after 15～25 days. In the final conclusion, the appropriate preparing method of sikhae is to use frozen Alaska pollack with simplified method and fermented at 20℃ for 5 days and then kept at 4℃.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.45 no.5
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• pp.1-8
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• 2008

The belief propagation method that has been studied recently yields good performance in disparity extraction. The method in which a target function is modeled as an energy function based on Markov random field(MRF), solves the stereo matching problem by finding the disparity to minimize the energy function. MRF models provide robust and unified framework for vision problem such as stereo and image restoration. the belief propagation method produces quite correct results, but it has difficulty in real time implementation because of higher computational complexity than other stereo methods. To relieve this problem, in this paper, we propose a fast algorithm of the belief propagation method. Energy function consists of a data term and a smoothness tern. The data term usually corresponds to the difference in brightness between correspondences, and smoothness term indicates the continuity of adjacent pixels. Smoothness information is created from messages, which are assigned using four different message arrays for the pixel positions adjacent in four directions. The processing time for four message arrays dominates 80 percent of the whole program execution time. In the proposed method, we propose an algorithm that dramatically reduces the processing time require in message calculation, since the message.; are not produced in four arrays but in a single array. Tn the last step of disparity extraction process, the messages are called in the single integrated array and this algorithm requires 1/4 computational complexity of the conventional method. Our method is evaluated by comparing the disparity error rates of our method and the conventional method. Experimental results show that the proposed method remarkably reduces the execution time while it rarely increases disparity error.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2019.04a
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• pp.43-43
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• 2019

Deparia pycnosora (Christ) M. Kato is a fern used as ornamental plant. In addition, it is called "Teol-go-sa-ri" in Korean name. The aim of this study was to develop a practical propagation method of D. pycnosora using tissue culture technique. Prothallus obtained from spore germination was the used as experiment materials. The prothalli (300 mg) used in all experiments were sub-cultured for 8-week intervals. The most suitable media for prothallus propagation were identified by culturing 300 mg of prothalli in $1/4{\times}$, $1/2{\times}$, $1{\times}$, $2{\times}$ MS medium and in Knop medium for 8 weeks. Also, the prothalli were cultured by chopping with a scalpel. In addition, sucrose, activated charcoal, and total nitrogen source were added in different concentrations based on the culture medium selected. Cultures were maintained at a temperature of $25{\pm}1^{\circ}C$, light intensity of $30{\times}1.0{\mu}mol-m-2{\cdot}s-1$, and a photoperiod of 16/8 h (light/dark) in in vitro. The results showed that optimum was achieved prothallus fresh weight and development in $1{\times}$ MS medium. When other components were added to the basic $1{\times}$ MS medium, prothallus propagation was maximized in $1{\times}$ MS medium supplemented with 2% sucrose, 0.2% activated charcoal, and 60 mM total nitrogen. To select a suitable soil mixture for sporophyte formation, 1.0 g of prothallus was blended with distilled water, spread on five combinations of different soil substrates (decomposed granite, horticultural substrates, peat moss, and perlite), and cultivated for 12 weeks. The sporophyte cultures were maintained at a temperature of $25{\pm}1^{\circ}C$, light intensity of $43{\pm}2.0{\mu}mol-m-2{\cdot}s-1$, humidity of $84{\pm}1.4%$, and a photoperiod of 16/8 h (light/dark). As a results, horticultural substrate alone, 2:1 (v:v) mixtures of horticultural substrate and perlite, and 2:1 mixtures of horticultural substrate and decomposed granite induced 208.0, 201.3 and 248.8 sporophytes per pot, respectively. Therefore, this result could provide a practical mass propagation method of D. pycnosora

• Bulletin of the Korean Space Science Society
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• 2008.10a
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• pp.26.4-27
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• 2008

The completion ('initiation' de facto) of the KASI Orbit Propagator and Estimator (KASIOPEA) has been delayed for several reasons unfortunately. Due to the lack of working staffs and the Division priority rearrangement, the initial plan was dismantled and ignored for many years. However, fundamental researches regarding the essential parts of KASIOPEA has been done by author. The numerical integration module of the KASIOPEA is the most sensitive part in the precision of the final output in general. There is no silver bullet in the numerical integration in an orbit propagation as a non-stiff ODE case. Many numerical integration method like single-step methods, multi-step method, and extrapolation methods have been used in overly populated orbit propagator or estimator. In this study, several popular methods from single-step, multi-step, and extrapolation methods have been tested in numerical accuracy and stability.