• Honam Mathematical Journal
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• v.33 no.2
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• pp.181-186
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• 2011

Consider a multiplicative group of integers modulo n, denoted by $\mathbb{Z}_n^*$. Any element $a{\in}\mathbb{Z}_n^*$ n is said to be a semi-primitive root if the order of a modulo n is $\phi$(n)/2, where $\phi$(n) is the Euler phi-function. In this paper, we classify the multiplicative groups of integers having semi-primitive roots and give interesting properties of such groups.

• Steel and Composite Structures
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• v.3 no.5
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• pp.307-320
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• 2003

This paper presents an efficient approach to the determination of the buckling loads of down-aisle, spliced, unbraced, pallet rack structures subjected to vertical and horizontal loads. A pallet rack structures is analysed by considering the stability equations of an equivalent free-sway column. The effects of semi-rigid beam-to-upright, splice-to-upright and base-plate-to-upright connections are fully incorporated into the analysis. Each section of upright between successive beam levels in the pallet rack is considered to be a single column element with two rotational degrees of freedom. A computer algebra package was used to determine modified stability equations for column elements containing splices. The influence of the position of splices in a pallet rack is clearly demonstrated.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.680-681
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• 2015

This paper proposes a comparative study of dual-airgap flux switching permanent magnet (FSPM) and spoke-type interior permanent magnet (S-IPM) machines equipped with phase-group concentrated-coil (PGCC) windings. Both of the investigated machines are the same size and material amounts which are compared at the same operating conditions. All the relevant machine performance including back electromotive force (EMF), cogging torque, and electromagnetic torque are analyzed by a 2-D time-stepping finite element method (FEM).

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.04a
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• pp.397-402
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• 2000

In this paper, we have been concerned with development of plastic mold design system by using Auto CAD. We provides a interface and interaction for mold designer who can select optimal mold base and mold parts within Auto CAD environment. We use the paramatric design method and an essential elements group forms. This program made for using Visual Lisp, DCL and Visual Basic that could easily get a database which is built to mold base and parts within Auto CAD. We provide 6 types mold base and 35 parts database for designer. In addition, it will be lined to mold cost and not only 2-D but also 3-D models

• Journal of Powder Materials
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• v.27 no.5
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• pp.420-428
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• 2020

Additive manufacturing technology is recognized as an optimal technology for mass-customized distributed production because it can yield products with high design freedom by applying an automated production system. However, the introduction of novel technologies to the additive manufacturing industry is generally delayed, and technology uncertainty has been pointed out as one of the main causes. This paper presents the results of the research and analysis of current standardization trends that are related to additive manufacturing by examining the hierarchical structure of the quality system along with the various industry and evaluation standards. Consequently, it was confirmed that the currently unfolding standardization does not sufficiently reflect the characteristics of additive manufacturing technology, and rather can become a barrier to entry for market participants or an element that suppresses the lateral shearing ability of additive manufacturing technology.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.5
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• pp.2723-2740
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• 2017

Steganographic schemes which are based on minimizing an additive distortion function defined the overall impacts after embedding as the sum of embedding costs for individual image element. However, mutual impacts during embedding are often ignored. In this paper, an adaptive JPEG steganographic method based on weight distribution for embedding costs is proposed. The method takes mutual impacts during embedding in consideration. Firstly, an analysis is made about the factors that affect embedding fluctuations among JPEG coefficients. Then the Distortion Update Strategy (DUS) of updating the distortion costs is proposed, enabling to dynamically update the embedding costs group by group. At last, a kind of adaptive JPEG steganographic algorithm is designed combining with the update strategy and well-known additive distortion function. The experimental result illustrates that the proposed algorithm gains a superior performance in the fight against the current state-of-the-art steganalyzers with high-dimensional features.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.855-856
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• 2006

Inductance can be defined as several kinds of slops on the B-H curve, and at is classified into apparent, effective, incremental inductances, etc. In many research cases, its calculation and measurement are partially dealt. However it is hard to find the clear explanation of the inductance in the voltage equation of PM machines, and even its relationship with those classified inductances in the view point of design and characteristics analysis. Moreover some previous definition of inductance can not be used for the inductance of coils in PM machines. Therefore, in this paper the inductance is redefined for voltage equation of PM machines, and the methods of calculation by using finite element analysis method and measurement are explained.

• Bulletin of the Korean Space Science Society
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• 2004.10b
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• pp.360-363
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• 2004

This review is concerned with the MP (multipactor) phenomena of the diplexer for RFDU DM of next generation satellite. The MP discharge is serious problems to design RF components in space applications such ase damage of physical structure, performance degradation, and mission failure of the satellite. In this work, we employed the 3D finite element method (FEM) to calculate the critical gap points and adopted ESTEC curve, MP susceptibility zone, to analyze the maximum handling RF power in the diplexer. And this work also recommends that one should design the tx filter of the diplexer which is more wider bandwidth upto the points to escape the ears of the group delay especially the cavity type of RF components in space applications.

• Proceedings of the KIEE Conference
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• 2006.10a
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• pp.10-11
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• 2006

The azobenzene dendrimer is one of the dendrimeric macromolecules that include the azo-group exhibiting a photochromic character. Due to the presence of the charge transfer element of the azo-group and its rod-shaped structure, these compounds are expected to have potential interest in electronics and photoelectronics, especially in nonlinear optics. In the present paper, we give pressure stimulation to organic thin films and detect the induced displacement current. Functional photoisometrization organic molecular the photo-stimulus to organic monomolecular L films and LB films of dendrimer and SASH were performed. The SASH organic monolayer in case of pressure stimulus occurred that positive course but in case of the photo-stimulus compared positive and negative. It is assumed that generation forms of displacement current were measured when photo-stimulus for impression.

• Structural Engineering and Mechanics
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• v.32 no.2
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• pp.269-282
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• 2009

Responding to the threat of terrorist attacks around the world, numerous studies have been conducted to search for new methods of vulnerability assessment and protective technologies for critical infrastructure under extreme bomb blasts or high velocity impacts. In this paper, a two-dimensional behavioral rate dependent lattice model (RDLM) capable of analyzing reinforced concrete members subjected to blast and impact loading is presented. The model inherently takes into account several major influencing factors: the progressive cracking of concrete in tension, the inelastic response in compression, the yielding of reinforcing steel, and strain rate sensitivity of both concrete and steel. A computer code using the explicit algorithm was developed based on the proposed lattice model. The explicit code along with the proposed numerical model was validated using experimental test results from the Woomera blast trial.