• Proceedings of the Korean Powder Metallurgy Institute Conference
• /
• 2001.11a
• /
• pp.36-36
• /
• 2001

$BaTiO_3$는 현재 전기 전자 부속 산업엣 필수적인 재료로서, multilayer capacitor,positive temperature coefficient(PTC) resistor, grain-boundary battier layer capacitor(GBBLC)등에 쓰이고 있다. $BaTiO_3$의 전기적 특성을 최대화하기 위해서는 미세구조가 최적화 되어야만 하는데 일반적으로 수 마이트로 이내의 작고 균일한 크기의 입자크기가 바람직하다. 그러나 $BaTiO_3$계에서 화학양론의 조성이 정확하게 일치하지 않거나 $La^{3+}$나 $Nb^{5+}$같은 첨가제가 들어가지 않으면 비정상 입자 성장은 자발적으로 일어난다. 그러나 첨가제는 $BaTiO_3$의 강자성 특성에 영향을 주게 되므로 첨가제 없이 비정상 입자 성장을 억제할 수 있는 것이 바람직한 방법이며, 이 것이 본 실험의 목표이다. 본 실험에서는 0.4-mol%-$TiO_2$가 첨가된 $BaTiO_3$ 분말을 디스크 형태로 성형하여 $H_2$ 분위기, 1250에서 5시간동안 열처리한 후, 공기 중, 1300도에서 48시간까지 소결한 후 미세조직을 관찰하였다. 소결 전에 $H_2$ 분위기에서 열처리를 함으로서 초기 입자 크기는 증가하게 되고 이로 인한 계의 성장 구동력 감소로 비정상 입자 성장이 억제되었으며 균일하고 미세한 입자 크기를 가지는$BaTiO_3$ 소결체를 얻을 수 있었다. 또한 비정상이 억제되지 않은 $BaTiO_3$의 유전 특성보다 우수한 유전 특성을 나타내었다. 본 실험을 통해서 첨가제를 사용하지 않고 우수한 유전 특성을 가지는 미세한 균일한 입자의 $BaTiO_3$를 제조하는 새로운 기술을 개발하였다.

• Journal of KIISE:Software and Applications
• /
• v.33 no.4
• /
• pp.440-448
• /
• 2006

Self-Organizing Map (SOM) is an unsupervised learning neural network and it is used for preserving the structural relationships in the data without prior knowledge. SOM has been applied in the study of complex problems such as vector quantization, combinatorial optimization, and pattern recognition. This paper proposes a new usage of SOM as a tool for schema transformation hoping to achieve more efficient genetic process. Every offspring is transformed into an isomorphic neural network with more desirable shape for genetic search. This helps genes with strong epistasis to stay close together in the chromosome. Experimental results showed considerable improvement over previous results.

• Journal of Digital Convergence
• /
• v.12 no.6
• /
• pp.125-134
• /
• 2014

Supply Chain Management(SCM) is getting important, because size of the company is getting bigger and the kinds of product are various. In the case of manufacturing corporation, for the optimization of SCM, we have to make production and distribution plan by considering the various fluctuation in the aspect of integration. In this paper, first, It proposed the reasonable operational way of the SCM about when the customer's demanding is various and demanding expectation fluctuates in capacity standardization of producer stage. Second, the paper proposed the management way for demanding by considering confirmed demanding information, related inventory expense and demanding shortage expense when we make production and distribution plan. The paper applied the genetic algorithm proved for current usefulness. it proposed the optimal operational way for SCM by dividing into 2 ways for dealing with the duration of confirmed demanding information and various fluctuation.

• Journal of the Society of Naval Architects of Korea
• /
• v.36 no.4
• /
• pp.137-146
• /
• 1999

Inspection becomes to be important in the safety of structure and economical viewpoint, because structural damage accompanies lots of economical cost and social problems. Especially ship structure is composed of a lot of members and it is impossible to inspect all members continuously. The purpose of this paper is to get optimal inspection plan containing inspection time and method. Crack is one of major modes on the structural failure and can lead to collapse of structure. In this paper, the deteriorating process, which contains inspection to detect the crack before the propagation to large crack, is idealized as Markov chain model. Genetic algorithm is also used to accomplish the optimization of inspection plan. Especially, the probabilistic characteristics of cracks are changed, because ship is operating in corrosive environments and the scantling of structural members is reduced due to corrosion. Non-stationary Markov chain model is used to represent the process of corrosion in structural members. In this paper, the characteristics of indivisual inspection plan are compared by numerical examples for the change of corrosion rate, the cost due to scheduled system down and target failure probability. From the numerical example, it can be seen that the improvement of fatigue life for the members with short fatigue life is the most effective way in order to reduce total maintenance cost.

• Journal of Navigation and Port Research
• /
• v.36 no.5
• /
• pp.387-394
• /
• 2012

In an automated container terminal, automated stacking cranes(ASCs) take charge of handling of containers in a block of the stacking yard. This paper proposes a multi-criteria strategy to solve the problem of job dispatching of twin ASCs which are identical to each another in size and specification. To consider terminal situation from different angles, the proposed method evaluates candidate jobs through various factors and it dispatches the best score job to a crane by doing a weighted sum of the evaluated values. In this paper, we derive the criteria for job dispatching strategy, and we propose a genetic algorithm to optimize weights for aggregating evaluated results. Experimental results are shown that it is suitable for real time terminal with lower computational cost and the strategy using various criteria improves the efficiency of the container terminal.

• Journal of the Korean Institute of Intelligent Systems
• /
• v.12 no.5
• /
• pp.405-410
• /
• 2002

In this paper, fuzzy system modeling using new hierarchical structure is suggested for the complex and uncertain system. The proposed modeling technique Is to decompose the fuzzy rule base structure into the above-rule base and the sub-rule base. By applying hierarchical fuzzy rules, they can be used efficiently and logically. Also, hieratical fuzzy rules can improve the accuracy and the transparency of structure in the fuzzy system. The genetic algorithm is applied for optimization of the parameters and the structure of the fuzzy rules. To show the effectiveness of the proposed method, fuzzy modeling of the complex nonlinear system is provided.

• Journal of Life Science
• /
• v.14 no.1
• /
• pp.110-114
• /
• 2004

The optimized RAPD-PCR conditions, that can be utilized as a basic information for analysis of the gelletic characteristics were developed for genetic analysis of four mulberry varieties, named Milsung, Chungil, Suil, and Hansung using a primer, OPY15 (5'-AGTCGCCCTT-3') from Operon company. We tested several different factors for best PCR condition including concentrations of DNA, primer, Mgclu annealing temperature, number of PCR cycle, and prosence/absence of pre-heating time at the begining of PCR reaction in the $25 \mul$volume. The best RAPD profiles were obtained using 50 ng of DNA, 1 $\mu$M of primer, $1 \mum$of $MgCl_2\;,45^{\circ}C$ of annealing temperature and an absence of pre-heating time. An establishment of the stable and reproducible RAPD-PCR conditions are expected to be useful for the subsequent RAPD-related investigation, such as genetic characterization of the mulberry varieties, re-establishment of phylogenetic relationships and development of new varieties.

• Journal of IKEEE
• /
• v.1 no.1 s.1
• /
• pp.19-30
• /
• 1997

In this paper we design the optimal satellite-tracking antenna $H{\infty}$ control system using genetic algorithms. To do this, we give gain and dynamics parameters to the weighting functions and apply genetic algorithms with reference model to the optimal determination of weighting functions and design parameter ${\gamma}$ that are given by Glover-Doyle algorithm which can design $H{\infty}$ controller in the state space. These weighting functions and design parameter ${\gamma}$ are optimized simultaneously in the search domain guaranteeing the robust stability of closed-loop system. The effectiveness of this satellite-tracking antenna $H{\infty}$ control system is verified by computer simulation.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.35 no.7
• /
• pp.759-766
• /
• 2011

Recently, noise reduction in room air conditioners has been one of the important issues as well as cooling efficiency. The rotary compressor is the dominant noise source in an air conditioner. A number of studies have been conducted on reducing compressor noise through improving muffler and resonator design. However the noise from the accumulator, a noise delivering path between compressor and air conditioner, is not fully taken into consideration. The accumulator contains a large inner cavity, and usually generates additional resonance noise during operation. This paper aims to conduct an optimal design for reducing accumulator noise by maximizing the transmission loss within the target frequency range that represents high-order nonlinearity. Design of experiments and radial basis function neural network are used in the context of approximate meta-models, and genetic algorithm is used as an optimization tool.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.16 no.10
• /
• pp.6839-6845
• /
• 2015

The optimization design method for the broadband operation of the sleeve monopole was proposed to unify the multiple antennas essential to the multi-functional broadband wireless communication systems into one antenna. The structure of the sleeve part was optimized to enhance the impedance matching characteristics based on the theoretical analysis that sleeve part can works as the open stub. The thick monopole was used for the broadband operation. The radius of the sleeve and the permittivity of the dielectric inside the sleeve was optimized to enhance the impedance matching characteristics for the broadband operation. The optimized sleeve monopole having thick monopole shows broadband characteristics over 3:1 bandwidth, from 0.8 to 2.43 GHz, which is suitable for the commercial wireless communication system. The proposed broadband sleeve monopole can reduce multiple antennas essential to the multi-functional broadband systems to one antenna.