• International Journal of Control, Automation, and Systems
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• 제6권2호
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• pp.269-277
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• 2008

This paper proposes a necessary and sufficient condition of convergence in the $L_2$-norm sense for a feedback-based iterative learning control (ILC) system including a multi-input multi-output (MIMO) linear time-invariant (LTI) plant. It is shown that the convergence conditions for a nominal plant and an uncertain plant are equal to the nominal performance condition and the robust performance condition in the feedback control theory, respectively. Moreover, no additional effort is required to design an iterative learning controller because the performance weighting matrix is used as an iterative learning controller. By proving that the least upper bound of the $L_2$-norm of the remaining tracking error is less than that of the initial tracking error, this paper shows that the iterative learning controller combined with the feedback controller is more effective to reduce the tracking error than only the feedback controller. The validity of the proposed method is verified through computer simulations.

• 융합신호처리학회논문지
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• 제5권3호
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• pp.205-209
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• 2004

벡터양자화에서 사용되는 부호책 생성 알고리즘들 중에서 가장 널리 사용되는 방법은 K-means 알고리즘이다. 본 논문에서는 부호책의 성능 개선을 위해 새로운 갱신조건을 적용한 부호책 생성 알고리즘을 제안한다. 기존의 K-means 알고리즘은 모든 학습반복 과정 동안 부호벡터 갱신 시 거리의 가중치를 고정하지만, 제안된 방법은 학습반복 과정에서 새로운 부호벡터의 갱신 조건에 따라서 다른 가중치를 적용하여 부호책을 구한다. 따라서, 갱신 조건에 의해 부호벡터에 다른 가중치를 적용할 수 있고, 학습반복 과정마다 가변되는 가중치를 적용하는 효과를 얻을 수 있다. 실험 결과 K-means 알고리즘보다 부호책의 성능이 향상됨을 확인하였다.

• 한국융합학회논문지
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• 제6권4호
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• pp.55-64
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• 2015

본 연구는 운항 승무원의 삶의 질을 높이기 위한 방안마련을 위해 안전과 근무조건 및 조직공정성, 조직몰입 정도를 측정하고, 조직몰입에 영향을 미치는 관련요인을 파악하기 위해 경로분석을 시행하였다. 2014년 11월 2일부터 3일까지 인천국제공항 및 김포국제공항을 운항하는 국내 7개 민간 항공사의 운항승무원 230명을 대상으로 설문조사를 실시하였다. 안전, 근무조건, 조직공정성, 조직몰입 등을 리커트 5점 만점으로 측정하여 신뢰도와 타당성 검정을 수행하였다. 경로모형의 적합도는 $X^2=88.424$, p<0.001, df=48, $X^2/df=1.842$, RMR=0.044, GFI=0.940, NFI=0.926, CFI=0.964, IFI=0.965로 나타났으며, 최종 연구모형에서 근무조건과 안전은 조직공정성과 조직몰입의 유의미한 영향요인으로 나타났다. 따라서 민간 항공사의 조직공정성과 조직몰입을 위해서는 안전을 강화하고 근무조건을 향상시키고 안전에 대한 노력을 강화해야 한다고 제시된다.

• 한국산업융합학회 논문집
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• 제14권4호
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• pp.143-149
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• 2011

The experiment has been investigated the room temperature change under adjusting 4-way valve which was installed for cooling and heating switch. Beside, the temperature of heat pump was controlled automatically for autonomously adjusting temperature and maintaining a constant room temperature. As results, Inlet & outlet temperature differences of compressor are $95^{\circ}C$ in cooling condition and $57^{\circ}C$ in heating condition. Therefore, Compression efficiency of cooling effect is higher than heating effect. In addition, Heat exchange effect of Cooling system condition is higher than heating system. This results can be used for studying about automatic temperature control of cooling and heating system with heat pump and 4way valve.

• 한국산업융합학회 논문집
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• 제2권2호
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• pp.73-81
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• 1999

Shake mixing has been widely used in cell culture. The mixing performance for shake mixing, however, has not been reported quantitatively. The critical circulating frequency and the power consumption for complete suspension of particles, based on the definition of Zwietering, were measured in a shaking vessel containing a solid-liquid system. The critical suspension frequency was correlated by the equation from Baldi's particle suspension model modified with the physical properties of the particles. Critical suspension frequency was correlated as following ; $$N_{JS}={\frac{0.58\;d{_p}^{0.06}(g{\Delta}{\rho}/{\rho}_L)^{0.004}X^{0.03}}{D^{0.35}d^{0.17}{\upsilon}^{0.04}}}$$ The power consumption at the critical suspension condition in the shaking vessel was less than that in an agitated vessel with impeller.

• 한국산업융합학회 논문집
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• 제22권2호
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• pp.191-199
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• 2019

In this paper, dissimilar friction welding were produced using 15 mm diameter solid bar in chrome molybedenum steel(SCM440) to stainless steel(STS316L) to investigate their mechanical properties. Consequently, optimal welding conditions were n=2000 rpm, HP=70 MPa, UP=140 MPa, HT=10 sec and UT=10 sec when the metal loss(Mo) is 8.6 mm. In addition, an acoustic emission technique was applied to evaluate the optimal friction welding condition. AE parameters including the cumulative count, amplitude and energy showed a various changes according to the friction condition. A continuous type waveforms and low frequency spectrum was presented in friction time. On the other hand, a burst type waveform and high frequency spectrum was exhibited in pressing time.

• 한국산업융합학회 논문집
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• 제22권3호
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• pp.243-250
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• 2019

The nanosecond laser assisted ablation have been investigated. The biocompatable polymer PMMA was employed as the target material and the two distinctive surface conditions were test. The first surface condition is a dry surface for which the target surface is exposed to air and the second surface condition is the wet surface for which the target surface is covered with dehydrated water. The ablation volume, the laser induced acoustic wave, the laser induced plasma were investigated for both wet and dry condition. The nanosecond laser pulse ablatied more on the wet surface compared to the dry surface. The enhanced ablation of wet surface is attributed to the confined acoustic wave and the laser-induced plasma in the liquid layer.

• Nonlinear Functional Analysis and Applications
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• 제28권3호
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• pp.623-646
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• 2023

In this article, we introduce the hyperbolic space version of a faster iterative algorithm. The proposed iterative algorithm is used to approximate the common fixed point of three multi-valued almost contraction mappings and three multi-valued mappings satisfying condition (E) in hyperbolic spaces. The concepts weak w²-stability involving three multi-valued almost contraction mappings are considered. Several strong and △-convergence theorems of the suggested algorithm are proved in hyperbolic spaces. We provide an example to compare the performance of the proposed method with some well-known methods in the literature.

• Composites Research
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• 제30권3호
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• pp.175-180
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• 2017

탄소섬유 강화 복합재료는 가볍고, 우수한 물성을 가지고 있기 때문에 그 수요는 급격하게 증가되고 있다. 그에 따라, 탄소섬유 강화 복합재료의 기지로 재활용이 가능한 열가소성 수지를 사용한 복합재료 연구를 많이 진행하고 있다. 본 연구에서는 재활용 PET를 이용하여 재활용 복합재료에 대한 활용성 평가를 하였다. PET는 음료수 병으로 활용되는 폐기물을 수집하여 PET 필름을 제조하는 과정을 거쳤으며, PET 필름을 제조하기 위한 성형 온도와 시간의 차이에 따른 기계적 물성을 비교하여 최적의 성형온도와 시간을 분석하였다. 이를 바탕으로 재활용 PET 필름과 탄소섬유 매트를 이용하여 CF/PET 복합재료를 최적으로 성형하기 위한 변수를 관찰하였다. 성형 조건에 따른 기계적 물성을 굴곡시험으로 확인하였고, PET 필름이 탄소섬유 매트 내에 함침 되는 정도를 단면 사진으로, 그리고 계면 성질을 층간전단강도로 평가하였다. 궁극적으로 최적의 기계적 물성을 가지는 CF/PET 복합재료를 성형하기 위한 성형 조건이 $270^{\circ}C$와 5분임을 확인했다.

• 한국수학교육학회지시리즈B:순수및응용수학
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• 제13권3호
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• pp.207-215
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• 2006

Using more precise majorizing sequences than before [6], [10], [11], [14] we provide a finer semilocal convergence analysis for a certain class of Euler-Halley type methods for approximating a solution of an equation in a Banach space setting.