• Journal of the Korean Society for Precision Engineering
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• v.6 no.4
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• pp.84-93
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• 1989

This paper describes some development of Computer-Aided Process Planning System for cold-forging of rotationally symmetric parts(soild shape and solid-can combined shape) produced by the presses or formers. Using the developed system, forming sequences for producing final product are generated as graphic forms and process names, preform dimensions and process parameters(load, punch pressure, die pressure) are generated as routing sheets. Konwledges for forming sequence and process parameters are extracted from process limitations, plasticity theories, handbooks, relevent refferences and empirical know-how of experts in cold forging companies. Among extracted knowldeges, general and consistent knowledges are represented as design rules and are constructed as knowledge base. The developed system provides more powerful tool for through checking the producibilities of design, conformation of appropriate forming sequences and discoveries of new possibility. The results of the developed system are in good agreement with the practical data.

• Journal of the Korea Concrete Institute
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• v.12 no.5
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• pp.153-164
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• 2000

Numerical studies were carried out to investigate long-term behavior of flat plates, subjected to combined in-plane compressive and transverse loads. For the numerical studies, a computer program of nonlinear finite element analysis was developed. It can address creep and shrinkage as weel as geometrical and material nonlinearity, and also it can address various load combinations and loading sequences of transverse load, in-plane compressive load and time. This numerical method was verified by comparison with the existing experiments. Parametric studies were performed to investigate the strength variations of flat plates with four parameters; 1) loading sequence of floor load, compressive load and time 2) uniaxial and biaxial compression 3) the ratio of dead to live load 4) span length. Through the numerical studies, the behavioral characteristics of the flat plates and the governing load combinations were examined. These results will be used to develop a design procedure for the long-term behavior of flat plates in the future.

• Proceedings of the KIEE Conference
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• 2004.04a
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• pp.103-105
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• 2004

In this paper, a novel control scheme compensating for source voltage unbalance and current harmonics and power factor simultaneously in unified active power filter systems combined with shunt passive filters is proposed, where no low/high-pass filter are used in deriving the reference voltage for compensation. Using digital all-pass filters, the phase angle and the reference voltages compensating for harmonic current and unbalanced voltage are derived from the positive sequence component of the unbalanced voltage. The amplitude of d-axis current in a series filter is controlled as zero for power factor correction. The validity of the proposed control scheme has been verified by experimental results.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.2 s.245
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• pp.112-119
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• 2006

Due to their intrinsic anisotropy, composite materials show quite complicated damage mechanism with their fiber orientation and stacking sequence and especially, their fatigue damage process is sequential occurrence of matrix cracking, delamination and fiber breakage. In the study, to propose new model capable of describing damage mechanism under fatigue loading, fatigue analysis of composite laminates based on damage mechanics, are performed. The average stress is disassembled with stress components of matrix, fiber and interlaminar interface through stress analysis. Each stress components are used to assess static damage analysis based on continuum damage mechanics (C.D.M.). Fatigue damage curves are obtained from hysteresis loop and assessed by the fatigue damage analysis. Then, static and fatigue damage analysis are combined. Expected results such as stress-cycle relation are verified by the experimental results of fatigue tests.

• Journal of the Korean Mathematical Society
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• v.45 no.5
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• pp.1221-1241
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• 2008

Most of domains people have studied are convex bounded projective (or affine) domains. Edith $Soci{\acute{e}}$-$M{\acute{e}}thou$ [15] characterized ellipsoid in ${\mathbb{R}}^n$ by studying projective automorphism of convex body. In this paper, we showed convex and bounded projective domains can be identified from local data of their boundary points using scaling technique developed by several mathematicians. It can be found that how the scaling technique combined with properties of projective transformations is used to do that for a projective domain given local data around singular boundary point. Furthermore, we identify even unbounded or non-convex projective domains from its local data about a boundary point.

• Fisheries and Aquatic Sciences
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• v.6 no.1
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• pp.20-26
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• 2003

A bacterial strain was isolated from seawater to screen for phytase activities. A colony had the highest activity and was identified as an Escherichia coli strain. Using primers derived from E. coli acid phosphatase appA sequence, we cloned a 1,495 bp DNA fragment connected with the pGEM-T vector. It was over-expressed under lac promoter combined with its native promoter in E. coli $DH5\alpha$. The expression of the phytase gene occurred during late exponential growth and the intracellular phytase production was 16.9 units/ml. The yield of recombinant phytate was 412-fold higher than that of wild type E. coli K13.

• Management Science and Financial Engineering
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• v.17 no.1
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• pp.19-43
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• 2011

Tuning the architecture of SVM (support vector machine) is to build an SVM model of better performance. Two different tuning methods of the grid search and the GA (genetic algorithm) have been addressed in the literature, each of which has its own methodological pros and cons. This paper suggests a combined method for tuning the architecture of SVM models, which employs the GAM (generalized additive models), the grid search, and the GA in sequence. The GAM is used for selecting input variables, and the grid search and the GA are employed for finding optimal parameter values of the SVM models. Applying the method to a bankruptcy prediction problem, we show that SVM model tuned by the proposed method outperforms other SVM models.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.303-310
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• 2002

The bending vibration and thermal flutter instability of spacecraft booms modeled as circular thin-walled beams of closed cross-section and subjected to thermal radiation loading is investigated in this paper. Thermally induced vibration response characteristics of a composite thin walled beam exhibiting the circumferantially uniform system(CUS) configuration are exploited in connection with the structural flapwise bending-lagwise bending coupling resulting from directional properties of fiber reinforced composite materials and from ply stacking sequence. The numerical simulations display deflection time-history as a function of the ply-angle of fibers of the composite materials, damping factor, incident angle of solar heat flux, as well as the boundary of the thermal flutter instability domain. The adaptive control are provided by a system of piezoelectric devices whose sensing and actuating functions are combined and that an bonded or embedded into the host structure.

• The Plant Pathology Journal
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• v.29 no.3
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• pp.317-322
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• 2013

For the past two decades, the causal agent of anthracnose occurring on strawberry in Korea was considered Colletotrichum gloeosporioides. However, the recent molecular analysis has shown that the genus Colletotrichum has undergone many taxonomic changes with introduction of several new species. As a result, it revealed that C. gloeosporioides indeed consisted of more than 20 distinct species. Therefore, the Korean pathogen isolated from strawberry should be reclassified. The shape and size of the conidia of the pathogen were not distinctly different from those of C. gloeosporioides and C. fructicola, but it differed in shape of the appressoria. A combined sequence analysis of partial actin, glyceraldehydes-3-phosphate dehydrogenase genes, and the internal transcribed spacer regions showed that the strawberry isolates formed a monophyletic group with authentic strains of C. fructicola. On the basis of these results, the anthracnose fungi of the domestic strawberry in Korea were identified as C. fructicola and distinguished from C. gloeosporioides.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 1996.10a
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• pp.211-214
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• 1996

This paper propose a method for pattern recogniton using spectrum analyzer and fuzzy ARTMAP. Contour sequences obtained from 2-D planar images represent the Euclidean distance between the centroid and all boundary pixels of the shape, and are related to the overall shape of the images. The Fourier transform of contour sequence and spectrum analyzer are used as a means of feature selection and data reduction. The three dimensional spectral feature vectors are extracted by spectrum analyzer from the FFT spectrum. These Spectral feature vectors are invariant to shape translation, rotation, and scale transformations. The fuzzy ARTMAP neural network which is combined with two fuzzy ART modules is trained and tested with these feature vectors. The experiments include 4 aircrafts and 4 industrial parts recognition process are presented to illustrate the high performance of this proposed method in the ion problems of noisv shapes.