• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2004년도 제22회 춘계학술대회논문집
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• pp.524-527
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• 2004

Hybrid rocket had many advantage with compared to solid and liquid rockets. However, the engines have not yet been used in practical rocket systems, due mainly to the disadvantage of hybrid combustion, such as low fuel regression rate. In this study, lab-scale hybrid motor was designed and manufactured. And the methods of regression rate improvement were considered. Test firings with thrusts up to 300 N were conducted with GOX and transparent PMMA. Thrust was calculated with the pressure of the combustion chamber and the regression rate was measured in with variation of oxidizer flow rate. The regression rates showed a strong dependency on GOX mass flux. The frequency analysis technique of the bulk-mode oscillation of motor was applied to a hybrid rocket motor and was based on the principle that this frequency was inversely proportional to the square root of the chamber volume. Several problems and solutions of operating hybrid rocket were presented.

• 대한전기학회논문지:시스템및제어부문D
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• 제53권6호
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• pp.433-439
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• 2004

The Helicopter Simulator System is non-linear and complex. Futhermore, because of absence of its accurate mathematical model, it is difficult to control accurately its attitudes such as elevation angle and azimuth one. Therefore, we proposed a Hybrid GA-PID WAVENET(Genetic Algorithm Proportional Integral Derivative Wavelet Neural Network)control technique to control efficiently these angles. The proposed Hybrid GA-PID WAVENET is made through the following process. First, the WAVENET fundamental functions are defined. And their dilation and translation values are adjusted by GA to construct the optimal WAVENET controller. Secondly, the proportional, integral, and derivative gain coefficients of PR controller are tuned optimally. Finally, WAVENET controller which has a good transient characteristic and GA-PE controller which has a good steady state characteristic is adequately combined in hybrid type. Through the computer simulations, it is proved that the Hybrid GA-PE WAVENET control technique has a more excellent dynamic response than PID control technique and GA-PID one.

• 대한금속재료학회지
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• 제49권10호
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• pp.760-765
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• 2011

This paper presents a study of the tensile behavior of carbon and glass fiber reinforced epoxy hybrid laminates manufactured by vacuum assisted resin transfer molding (VARTM). The objective of this study was to develop and characterize carbon fiber reinforced plastic hybrid composite material that is low cost and light-weight and that possesses adequate strength and stiffness. The effect of position and content of the glass fabric layer on the tensile properties of the hybrid laminates was examined. The strength and stiffness of the hybrid laminates showed a steady decrease with an increase of the glass fabric content this decrease was almost linear. Fracture strain of these laminates showed a slight increasing trend when glass fabric content was increased up to 3 layers, but at a glass fabric content > 3 layers the strain was almost constant. When glass fabric layers were at both outer surfaces, the hybrid laminate exhibited a slightly higher tensile strength and elastic modulus due to the small amount of glass yarn pull-out.

• International Journal of Computer Science & Network Security
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• 제21권4호
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• pp.272-276
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• 2021

Presently, Online / Offline Users are facing cyber attacks every day. These cyber attacks affect user's performance, resources and various daily activities. Due to this critical situation, attention must be given to prevent such users through cyber attacks. The objective of this research paper is to improve the IDS systems by using machine learning approach to develop a hybrid model which controls the cyber attacks. This Hybrid model uses the available KDD 1999 intrusion detection dataset. In first step, Hybrid Model performs feature optimization by reducing the unimportant features of the dataset through decision tree, support vector machine, genetic algorithm, particle swarm optimization and principal component analysis techniques. In second step, Hybrid Model will find out the minimum number of features to point out accurate detection of cyber attacks. This hybrid model was developed by using machine learning algorithms like PSO, GA and ELM, which trained the system with available data to perform the predictions. The Hybrid Model had an accuracy of 99.94%, which states that it may be highly useful to prevent the users from cyber attacks.

• Advances in materials Research
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• 제12권1호
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• pp.67-81
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• 2023

Basalt and poly-ester fibers along with epoxy resin were used to produce inter-ply, intra-ply and functionally gradient hybrid composites. In all of the composites, the relative content of basalt fiber to poly-ester fiber was equal to 50 percent. The flexural and charpy impact properties of the hybrid composites are presented with particular regard to the effects of the hybrid types, stacking sequence of the plies, loading direction and loading speed. The results show that with properly choosing the composition and the stacking sequence of the plies; the inter-ply hybrid composites can achieve better flexural strength and impact absorption energy compared to the intra-ply and functionally gradient composites. The flexural strength and impact absorption energy of the functionally gradient hybrid composites is comparable to, or higher than the intra-ply sample. Also, by increasing the loading speed, the flexural strength increases while the flexural modulus does not have any special trend.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1999년도 춘계학술대회논문집
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• pp.62-65
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• 1999

To reduce the cost of finite element analyses for sheet forming a 3D hybrid membrance/sheel method has been developed to study the springback of anisotropic sheet metals. in the hybrid method the bending strains and stresses were analytically calculated as post-processing using incremental shapes of the sheet obtained previously from the membrane finite element analysis. To calculate springback a shell finite element model was used to unload the final shape of the sheet obtained from the membran code and the stresses and strains that were calculated analytically. For verification the hybrid method was applied to predict the springback of a 2036-T4 aluminum square blank formed into a cylindrical cup. the springback predictions obtained with the hybrid method was in good agreement with results obtained using a full shell model to simulateboth loading an unloading and the experimentally measured data. The CPU time saving with the hybrid method over the full shell model was 75% for the punch stretching problem.

• 한국벤처창업학회:학술대회논문집
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• 한국벤처창업학회 2021년도 춘계학술대회
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• pp.131-136
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• 2021

산업 패러다임과 트랜드의 변화 속에서도 저성장, 고령화는 뉴 노말 시대의 가장 큰 문제점으로 대두되고 있다. 이에 따라 각자도생이 필요하며, 결국 창업이 대세인 시대가 되었다. 성공적인 창업을 위해서는 많은 준비와 실패 노하우의 축적이 필요하나 실패를 용납하지 않는 우리 사회분위기상 이는 쉽지 않다. 조사에 따르면 창업 장애요인으로 '창업실패 및 재기에 대한 두려움', '창업 준비부터 성공까지의 생계유지'가 많은 부분을 차지하고 있다. 이러한 장애요인을 줄이는 방법으로 Hybrid창업을 제시할 수 있으나 국내 많은 기업이 직장인의 겸직을 제한하는 탓에 Hybrid창업이 활성화되지 못하고 있고 관련 연구도 거의 없는 수준이다. 그러나 52시간 근무제로 직장인이 투잡(two-job)을 통한 수익창출 기회는 증가하였고, 고용불안과 은퇴이후를 고민하는 직장인들이 우회 창업하는 경우도 적지 않다. 이러한 Hybrid창업 현상은 조기은퇴, 고령화의 영향으로 계속 증가할 것으로 예상됨에 따라 관련 연구를 축적할 필요가 있다. 본 연구의 목적은 직장인의 Hybrid 창업의도에 미치는 영향요인을 탐색하는데 있다. 본 연구에서는 직장인의 창업가 특성, 창업역량, 경력지향성과 Hybrid창업의도간의 관계와, 직장인의 조직불안 인식의 조절효과를 검증하고자 한다.

• Nuclear Engineering and Technology
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• 제55권7호
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• pp.2547-2555
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• 2023

Amberlite IRN-78 resin was incorporated with iron to make a hybrid resin for the removal of silica from the borated water of nuclear power plants. The hybrid resin contained 0.84 wt % iron compounds upon pyrolysis. In batch experiments carried out at room temperature, 1 g of the hybrid resin removed ~60 ㎍ silica from 1 ppm borated water in ~120 min. The efficiency of the hybrid material increased with the resin quantity, decreased with silica concentration, and remained unchanged at different pH values. Freundlich and Temkin isothermal adsorption dominated the silica removal process and followed the pseudo-first-order and intra-particle diffusion mechanism simultaneously. The concentration of the leached iron remained appreciably under the safe limits of 200 ㎍/l during the experiments. This detailed study suggests the use of hybrid resin for the removal of silica from borated water streams and other similar systems.

• Journal of applied mathematics & informatics
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• 제40권3_4호
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• pp.769-784
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• 2022

The main theme of this present paper is to study ordered semigroups in the context of anti-hybrid interior ideals. The notion of anti-hybrid interior ideals in ordered semigroups is introduced. We prove that the concepts of ideals and interior coincide in some particular classes of ordered semigroups; regular, intra-regular, and semisimple. Finally, the characterization of semisimple ordered semigroups in terms of anti-hybrid interior ideals is considered.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2023년도 봄 학술논문 발표대회
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• pp.351-352
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• 2023

In order to respond to changes in the industrial environment such as the 4th industrial revolution, university education also needs active educational innovation efforts. This study proposed a construction construction hybrid curriculum that can actively utilize online education in the direction of educational innovation in domestic universities. The hybrid curriculum was based on online learning through lecture videos used in team-based learning. The hybrid curriculum additionally allows learners to choose their learning methods. In a hybrid class, learners can choose the class participation method they want from offline classroom or online real-time. Hybrid classes are considered to strengthen learners' options and take a step forward in learner-centered education.