• 제어로봇시스템학회논문지
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• 제18권6호
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• pp.513-518
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• 2012

In this paper, we propose a generalized index independent stability condition for a descriptor systemwithout any transformations of system matrices. First, the generalized Lyapunov equation with a specific right-handed matrix form is considered. Furthermore, the existence theorem and the necessary and sufficient conditions for asymptotically stable descriptor systems are presented. Finally, some suitable examples are used to show the validity of the proposed method.

• International Journal of Naval Architecture and Ocean Engineering
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• 제13권1호
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• pp.450-465
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• 2021

In this study, an attempt has been made to investigate the water-entry characteristics of the high-speed parallel projectile numerically. The shear stress transport k-𝜔 turbulence model and the Zwart-Gerber-Belamri cavitation model based on the Reynolds-Averaged Navier-Stokes method were used. The grid independent inspection and grid convergence index is carried out and verified. The influences of the parallel water-entry on flow filed characteristics, trajectory stability and drag reduction performance for different values of initial water-entry speed (𝜈₀ = 280 m/s, 340 m/s, 400 m/s) and clearance between the parallel projectiles (L_p = 0.5D, 1.0D, 2.0D, 3.0D) are presented and analyzed in detail. Under the condition of the parallel water-entry, it can be found that due to the intense interference between the parallel projectiles, the distribution of cavity is non-uniform and part of the projectile is exposed to water, resulting in the destruction of the cavity structure and the decline of trajectory stability. In addition, the parallel projectile suffers more severe lateral force that separates the two projectiles. The drag reduction performance is impacted and the velocity attenuation is accelerated as the clearance between the parallel projectiles reduces.

• The Journal of Korean Physical Therapy
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• 제33권6호
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• pp.286-291
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• 2021

Purpose: This study aims to measure the improvement of balanced ability and rapid response of 30 healthy adults by performing dynamic stretching, static stretching, and sargent jump. Methods: The sample 30 peoples without any musculoskeletal disease who volunteered to be the subject of the study. We measured all subjects on following metrics to evaluate the function and stability under the normal condition, with dynamic stretching (DS) group, static stretching (SS) group: vertical jump height and reaching distance Anterior, Posteromedial, Posterolateral and NO (Normal eye open), NC (Normal eye close), PO (Pillow with eye open), and PC (Pillow with close eye) were evaluated. All measures were analyzed using independent t-test and One-way repeated Anova. Results: There was a significant increase in SJH (Sargent jump) in both groups (p<0.05). In Y-balance test, there was a significant increase in both groups except for the ANT (Anterior) direction, and there was a significant increase only in the SS group in the ANT (Anterior) direction (p<0.05). There was no significant difference between the DS group and the SS group (p>0.05). There was no significant improvement in ST (Stability Index) and WDI (Weight Distribution Index) in both groups (p>0.05). Conclusion: Both DS and SS showed significant improvement in SJH and Y-balance tests, which are dynamic functions, but had no significant effect on static balance ability.

• 공업화학
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• 제32권3호
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• pp.320-325
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• 2021

본 연구에서는 밀배아유에 항산화 물질이 다량 함유되어있는 밀싹 추출물을 첨가한 후 O/W 유화액을 제조하는 최적화 공정을 설계하였다. 최적화 공정 설계는 반응표면분석법의 중심합성계획모델을 사용하였다. 기초실험을 통하여 유화제 첨가량, 유화시간, 밀싹 추출물의 첨가량을 독립변수로 설정하였다. 그리고 반응치는 평균입자크기, 점도, 유화안정도지수를 설정하여 유화액의 안정성을 평가하였다. 각 독립변수에 대해 최적화하여 P-value와 결정계수를 평가하여 실험 신뢰도를 확인하였다. 모든 독립변수를 만족하는 최적화 조건은 유화제 첨가량 = 7.7 wt.%, 유화시간 = 23.6 min, 밀싹 추출물의 첨가량 = 3.9 wt.%에서 평균입자크기 = 252.3 nm, 유화액의 점도 = 616.7 cP, ESI = 88.7%로 나타났다. 종합만족도가 0.9137으로 실험의 타당성을 뒷받침하였고, 실제실험을 진행하여 오차율이 0.5 %이하로 측정되었다. 따라서 중심합성계획모델을 통해 밀싹 추출물을 첨가하여 유화액을 제조하는 최적화 과정을 설계하였다.