• Structural Engineering and Mechanics
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• v.5 no.5
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• pp.491-505
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• 1997

This paper deals with the formulation and solution of a wide class of structures, in the presence of both geometric and material nonlinearities, as a particular mathematical programming problem. We first present key ideas for the nonholonomic (path dependent) rate formulation for a suitably discretized structural model before we develop its computationally advantageous stepwise holonomic (path independent) counterpart. A feature of the final mathematical programming problem, known as a nonlinear complementarity problem, is that the governing relations exhibit symmetry as a result of the introduction of so-called nonlinear "residuals". One advantage of this form is that it facilitates application of a particular iterative algorithm, in essence a predictor-corrector method, for the solution process. As an illustrative example, we specifically consider the simplest case of plane trusses and detail in particular the general methodology for establishing the static-kinematic relations in a dual format. Extension to other skeletal structures is conceptually transparent. Some numerical examples are presented to illustrate applicability of the procedure.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.23 no.61
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• pp.41-50
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• 2000

Cell formation(CF) Is to group parts with similar geometry, function, material and process into part families, and the corresponding machines into machine cells. Cell formation solutions often contain exceptional elements(EEs). Also, the following objective functions - minimizing the total costs of dealing with exceptional elements and maximizing total similarity coefficients between parts - have been used in CF modeling. Thus, multiobjective programming approach can be developed to model cell formation problems with two conflicting objective functions. This paper presents an effective cell formation method with fuzzy multiobjective nonlinear mixed-integer programming simultaneously to form machine cells and to minimize the cost of eliminating EEs.

• Proceedings of the Korean Nuclear Society Conference
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• 1997.05b
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• pp.237-243
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• 1997

The ultimate object of our study is to minimize the release of radioactive material into the environment and to maximize the treatable amount of the generated wastes. In planning the practical operation of the system, however, the operating cost, Process economics and technical flexibility must also be considered. For dealing with these multiple criteria decision making Problems, we used a foal programming which is a kind of multi-objective linear programming. This method requires the decision maker to set goals for each objective that one wishes to attain.

• Structural Engineering and Mechanics
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• v.83 no.5
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• pp.577-591
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• 2022

This paper develops a comparatively time-efficient methodology for performing seismic fragility analysis of the reinforced concrete (RC) buildings in the presence of uncertainty sources. It aims to appraise the effectiveness of any variation in the material's mechanical properties as epistemic uncertainty, and the record-to-record variation as aleatory uncertainty in structural response. In this respect, the fuzzy set theory, a well-known 𝛼-cut approach, and the Genetic Algorithm (GA) assess the median of collapse fragility curves as a fuzzy response. GA is requisite for searching the maxima and minima of the objective function (median fragility herein) in each membership degree, 𝛼. As this is a complicated and time-consuming process, the authors propose utilizing the Gene Expression Programming-based (GEP-based) equation for reducing the computational analysis time of the case study building significantly. The results indicate that the proposed structural analysis algorithm on the derived GEP model is able to compute the fuzzy median fragility about 33.3% faster, with errors less than 1%.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.199-199
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• 2008

이 실험은 NVM의 Oxide, Nitride, Oxide nitride층별 blocking, trapping and tunneling 속성에 대해서 밝히고자 한다. gate 전극은 값싸고 전도도가 좋은 알루미늄을 사용한다. 유리기판위에 Silicon nitride층을 20nm로 코팅하고 Silicon dioxide층을 10nm로 코팅한다. 그리고 amorphous Silicon material이 증착된다. Poly Silicon은 Solid Phase Crystallization 방법을 사용하였다. 마지막 공정으로 p-doping은 ion shower에 의한 방법으로 drain과 source 전극을 생성하였다. gate가 biasing 될 때, p-channel은 source와 drain 사이에서 형성된다. Oxide Nitride Oxide nitride (ONO) 층은 각각 12.5nm/20nm/2.3nm의 두께로 만들었다. 전하는 Program process 중에 poly Silicon층에서 Silicon Oxide nitride tunneling층을 통하여 움직이게 된다. 그리고 전하들은 Silicon Nitride층에 머무르게 된다. 그 전하들은 erasing process 중에 trapping 층에서 poly Silicon 층으로 되돌아 간다. Silicon Oxide blocking층은 trapping층으로 전하가 나가는 것을 피하기 위하여 더해진다. 이 논문에서 Programming process와 erasing process의 Id-Vg 특성곡선을 설명한다. Programming process에 positive voltage를 또는 erasing process에 negative voltage를 적용할 때, Id-Vg 특성 곡선은 왼쪽 또는 오른쪽으로 이동한다. 이 실험이 보여준 결과값에 의해서 10년 이상의 저장능력이 있는 메모리를 만들 수 있다. 그러므로, NVM의 중요한 두 가지 성질은 유지성과 내구성이다.

• Computers and Concrete
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• v.19 no.6
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• pp.651-658
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• 2017

High-performance concrete, besides aggregate, cement, and water, incorporates supplementary cementitious materials, such as fly ash and blast furnace slag, and chemical admixture, such as superplasticizer. Hence, it is a highly complex material and modeling its behavior represents a difficult task. This paper presents an evolutionary system for the prediction of high performance concrete strength. The proposed framework blends a recently developed version of genetic programming with a local search method. The resulting system enables us to build a model that produces an accurate estimation of the considered parameter. Experimental results show the suitability of the proposed system for the prediction of concrete strength. The proposed method produces a lower error with respect to the state-of-the art technique. The paper provides two contributions: from the point of view of the high performance concrete strength prediction, a system able to outperform existing state-of-the-art techniques is defined; from the machine learning perspective, this case study shows that including a local searcher in the geometric semantic genetic programming system can speed up the convergence of the search process.

• International Journal of Computer Science & Network Security
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• v.22 no.1
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• pp.21-26
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• 2022

This study touched on the effect of the different electronic course designs on the programming skills of university students. The researcher used the experimental research design of a quasi-experimental of two experimental groups to achieve the objectives of the study. The first group underwent an electronic course designed in the holistic pattern, and the second group was taught a course in a sequential pattern. This experimental design was intended to measure the impact of these two learning modes on the learners' cognitive and performance achievement of programming skills. An achievement test and observational form were the data collection tools. Data were analyzed statistically using Pearson correlation, Mann Whitney Test, and Alpha Cronbach. The findings revealed statistically- significant differences between the mean scores of the students of the first and second experimental groups in favor of the former concerning the observational form and the latter in the cognitive test. Based on the findings, some recommendations are suggested. Due to their effectiveness in the educational process, expanding using the e-courses at universities is vital. The university teachers are highly recommended to design e-courses and provide technical and material support to the e-courses user to fulfill their design purpose.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.10
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• pp.918-922
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• 2006

Chalcogenide Phase change memory has the high performance necessary for next-generation memory, because it is a nonvolatile memory with high programming speed, low programming voltage, high sensing margin, low power consumption and long cycle duration. To minimize the power consumption and the program voltage, the new composition material which shows the better phase-change properties than conventional $Ge_2Sb_2Te_5$ device has to be needed by accurate material engineering. In the present work, we investigate the basic thermal and the electrical properties due to phase-change compared with chalcogenide-based new composition $Ge_1Se_1Te_2$ material thin film and convetional $Ge_2Sb_2Te_5$ PRAM thin film. The fabricated new composition $Ge_1Se_1Te_2$ thin film exhibited a successful switching between an amorphous and a crystalline phase by applying a 950 ns -6.2 V set pulse and a 90 ns -8.2 V reset pulse. It is expected that the new composition $Ge_1Se_1Te_2$ material thin film device will be possible to applicable to overcome the Set/Reset problem for the nonvolatile memory device element of PRAM instead of conventional $Ge_2Sb_2Te_5$ device.

• IE interfaces
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• v.10 no.3
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• pp.179-187
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• 1997

The efficiency of material flow systems in terms of optimal network flow and minimum cost flow has always been an important design and operational goal in material handling and distribution system. In this research, an attempt was made to develop a new algorithm and the model to solve a stochastic material flow network with bidirectional and uncertain flows. A stochastic material flow network with bidirectional flows can be considered from a finite set with unknown demand probabilities of each node. This problem can be formulated as a special case of a two-stage linear programming problem which can be converted into an equivalent linear program. To find the optimal solution of proposed stochastic material flow network, some terminologies and algorithms together with theories are developed based on the partitioning and subgradient techniques. A computer program applying the proposed method was developed and was applied to various problems.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.283-283
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• 2009

Composition environments - Automatic Control System based on Sproute Cultivator using Remote Conditional Driving System was realized. It was carried out to investigate into the characteristics of LEDs Control for the cultivation of sprouts. We have also composed a Combined Automatic Control System possible for the control of temperature and humidity at the same time. The applied LEDs for measurement are blue, green, red, white, yellow leds. And we had also designed the Web Programming for the automatic control about sprout cutivators.