• Journal of the Computational Structural Engineering Institute of Korea
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• v.20 no.1
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• pp.9-18
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• 2007

This study shows an implementation of partial holes in an initial design domain in order to improve convergences of topology optimization algorithms. The method is associated with a bubble method as introduced by Eschenauer et al. to overcome slow convergence of boundary-based shape optimization methods. However, contrary to the bubble method, initial holes are only implemented for initializations of optimization algorithm in this approach, and there is no need to consider a characteristic function which defines hole's deposition during every optimization procedure. In addition, solid and void regions within the initial design domain are not fixed but merged or split during optimization Procedures. Since this phenomenon activates finite changes of design parameters without numerically calculating movements and positions of holes, convergences of topology optimization algorithm can be improved. In the present study, material topology optimization designs of Michell-type beam utilizing the initial design domain with initial holes of varied sizes and shapes is carried out by using SIMP like a density distribution method. Numerical examples demonstrate the efficiency and simplicity of the present method.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.43 no.3 s.309
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• pp.76-81
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• 2006

Recently, Finite field is applied the cryptography in the modern multimedia communication. Especially, block codes such as Elliptic Curve Cryptosystem and Reed-Solomon code among the error correcting codes are defined with finite field. Also, finite field algorithm is conducting the research actively because many kind of application parts need the real time operating ability therefore the exclusive hardware have been implementing. In this paper, we proposed the inverse finite field algorithm over GF($2^8$) using finite composite field and implemented in a hardware, and then compare this hardware with the currently used 'Itoh and Tsujii' hardware in respect to structure, area and computation time. Furthermore, this hardware was inserted into the AES SubBytes block and implemented on FPGA emulator board to confirm that the superiority of the proposed algorithm through the performance evaluation.

• Journal of Ocean Engineering and Technology
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• v.29 no.1
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• pp.45-55
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• 2015

Because of the high stress concentration near the toe of a welded joint, the calculation of local stress using the finite element method which is relevant to the fatigue strength of the weld toe crack, is a challenging task. This is mainly caused by the sensitivity of finite element analysis, which usually occurs near the area of a dramatically changing stress field. This paper presents a novel numerical method through which a less mesh-sensitive local stress calculation can be achieved based on the 3D solid finite element, strictly sticking to the original definition of hot spot stress. In order to achieve the goal, a traction stress, defined at 0.5t and 1.5t away from the weld toe, was calculated using either a force-equivalent or work-equivalent approach, both of which are based on the internal nodal forces on the imaginary cut planes. In the force-equivalent approach, the traction stress on the imaginary cut plane was calculated using the simple force and moment equilibrium, whereas the equivalence of the work done by both the nodal forces and linearized traction stress was employed in the work-equivalent approach. In order to confirm the validity of the proposed method, five typical welded joints widely used in ships and offshore structures were analyzed using five different solid element types and four different mesh sizes. Finally, the performance of the proposed method was compared with that of the traditionally used surface stress extrapolation method. It turned out that the sensitivity of the hot spot stress for the analyzed typical welded joints obtained from the proposed method outperformed the traditional extrapolation method by far.

• Journal of Internet of Things and Convergence
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• v.6 no.1
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• pp.97-102
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• 2020

Multi-Channel Switch ICs for IoT have integrated several solid state structure low ON-resistance bi-directional relay MOS switches with level shifter to drive high voltage and they should be independently controlled by external serialized logic control. These devices are designed for using in applications requiring high-voltage switching control by low-voltage control signals, such as medical ultra-sound imaging, ink-jet printer control, bare board open/short and leakage test system using Kelvin 4-terminal measurement method. This paper describes implementation of analog switch control block and its verification using Field programmable Gate Array (FPGA) test pattern generation. Each block has been implemented using Verilog hardware description language then simulated by Modelsim and prototyped in a FPGA board. Compare to conventional IC, The proposed architecture can be applied to fields where multiple entities need to be controlled simultaneously in the IoT environment and the proposed pattern generation method can be applied to test similar types of ICs.

• The Journal of the Korea Contents Association
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• v.9 no.12
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• pp.410-417
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• 2009

South Korea had experienced the great of sports since entered in advanced country group. International sports game such as Olympic developed nation. Sports is intermediate that improve Korean public information level in community of nations. It's difficult to find another contents. Also, sports is important means between south and north Korea in branch situation. Sports is expected to practical improvement of country more than ever. In this way, sports had become real means of nation development. Therefore, social effort about promotion of sports need to be engaged in continuous and various form. This research proposed legal improvement for safety promotion of sports equipment. Sports facilities utilization activation may be ended by country sports competitive power.

• Journal of the Korea Institute of Building Construction
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• v.11 no.3
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• pp.319-325
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• 2011

During a construction project, construction managers must be provided with material information to help them to make decisions more efficiently without delaying the delivery of material. Construction work can be smoothly performed with the proper material supply. Construction duration depends on several material-related decisions, including the order, delivery, and allocation of material to the correct work location. Hence, it is worthwhile to introduce data warehouse techniques that generate subject-oriented and integrated data to construction material management. The data warehouse for construction material management can perform multidimensional analysis and then define KPIs (Key Performance Index) in order to provide construction managers with construction material information such as lead time, material delivery rate, material installation rate and so on. This research proposes a method of effectively facilitating large amounts of data in the operating systems during the construction management process. In other words, the proposed method can supply structured and multi-perspective material-related information using data warehouse techniques.

• Journal of The Korean Society of Grassland and Forage Science
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• v.30 no.2
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• pp.103-108
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• 2010

This experiment was carried out to select adaptability and forage production and quality of Pasture species at paddy field from 2007 to 2009 at Chungnam province. Among growth characters, 'Tall fescue' and 'Tall fescue mixture (Orchardgrass, Tall fescue, Perennial ryegrass, Kentuck bluegrass, White clover)' were somewhat good for waterlogging, production and disease and insect resistance. Fresh yield of 'Tall fescue mixture' and 'Tall fescue' were the highest as 84,294 kg and 78,400 kg per ha among 6 species. The dry yield of 'Tall fescue mixture' and 'Tall fescue' were also the highest as 20,644 kg and 19,759 kg per ha. The result of this study showed that 'Tall fescue mixture' and 'Tall fescue' had good growth characters and forage productivity at paddy field in middle region of South Korea.

• Korean Security Journal
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• no.10
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• pp.409-441
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• 2005

During reformation of the world order in the 21st century, the terrorism has been showing up as a new value and rising up as core element of determining human being's quality of lives. The middle east's terrorism is leading the international terrorism and it is originated from the religious ideology which has formed for centuries and struggles for regional influence. This is the conflict aspect coming from the opposition of religious ideologies and cultural dislocations. It concludes as confrontation between the terrorism of Islam fundamentalism and western christianity that America is leading after the terrorist attack on the World Trade Center on September 11, 2001. There is little prospect for an improvement of their relationship. The Terrorism supported by government might be eradicated by America's drastic anti-terrorism policy. However, it will be serious and spread all over the world that the terrorist attacks against America and western countries is acted by militant warriors of Islamic fundamentalism, uniting Arab and Islamic peoples' emotions against America. Terrorism is urgent menace to Korea and it is needed to take measures to cope with it considering their religion and people throughly.

• Journal of Korean Society of Steel Construction
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• v.24 no.4
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• pp.469-478
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• 2012

In this study, structural behavior of high tension bolted connections was analyzed in order to investigate effective utilizations. Also, the simplified numerical analysis method showing bolt behavior was proposed using the connector element in the ABAQUS, a nonlinear finite element program and verified by numerical analyses on the basis of the experiment of previous study. In an effort to analyze strength properties of plate girder which high tension bolts are applied to, the effects of each design parameter were compared and analyzed after moment-displacement relations were investigated according to design parameters (upper flange, lower flange, upper and lower flange, web) by action force standards.

• Polymer(Korea)
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• v.29 no.3
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• pp.314-319
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• 2005

Four kinds of new aliphatic diols were synthesized by the ring opening reaction of glycolide with 1,4-butanediol, 1,6-hexanediol, 1,4-cyclohexanediol, or 1,4-cyclohexanedimethanol, a difunctional initiator, in the presence of stannous octoate catalyst. The resulting diols were melt-polymerized with succinic acid, adipic acid, or suberic acid at 170, 190, or $220^{circ}C$ to produce new sequentially ordered aliphatic polyesters and their corresponding polyesters with random structure. Their glass transition temperatures ($T_g$) ranged from -40 to $30^{circ}C$, The sequentially ordered polyesters prepared at $170^{cir}C$ had higher $T_g$ of 5 to $10^{circ}$ than the polyesters with rand()m structure produced at higher temperature. From in-vitro degradation test the sequentially ordered polyesters was shower in the rate of hydrolysis in a buffer solution than the polymers with random molecular structure.