• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.24 no.6
• /
• pp.809-817
• /
• 2020

In the design and development process of Small-Sat power distribution and transmission module, the stability of dynamic resources was evaluated by a deep learning algorithm. The requirements for the stability evaluation consisted of the power distribution function of the power distribution module and demand module to the SAR radar in Small-Sat. To verify the performance of the switching power components constituting the power module PDM, the reliability was verified using a dynamic neural network. The adoption material of deep learning for reliability verification is the power distribution function of the payload to the power supplied from the small satellite main body. Modeling targets for verifying the performance of this function are output voltage (slew rate control), voltage error, and load power characteristics. First, to this end, the Coefficient Structure area was defined by modeling, and PCB modules were fabricated to compare stability and reliability. Second, Levenberg-Marquare based Two-Way NARX neural network Sigmoid Transfer was used as a deep learning algorithm.

• Korean Journal of Food Science and Technology
• /
• v.39 no.5
• /
• pp.584-587
• /
• 2007

The effect of molar substitution (MS, 0.030-0.118) on the dynamic rheological properties of hydroxypropylated rice starch pastes (5%, w/w) was investigated by small-deformation oscillatory measurements during aging. The magnitudes of storage (G#) and loss (G") moduli measured at $4^{\circ}C$ before aging increased with an increase in MS in the range of 0.030-0.118, while those of tan ${\delta}$ (the ratio of G"/G#) decreased. The G# values of hydroxypropylated rice starches, as a function of aging time (10 hr) at $4^{\circ}C$, increased rapidly at the initial stage, and then reached a plateau region at shorter aging times. However, for the native starch, the plateau values were not observed for G# after a long aging time. Increasing the MS resulted in a decrease in plateau values. The rate constant (K) for structure development during aging was described by first-order kinetics. The K values of hydroxypropylated rice starches at 0.086 and 0.118 MS were much lower than the K value at 0.030 MS.

• Journal of the Korean Geotechnical Society
• /
• v.19 no.4
• /
• pp.167-178
• /
• 2003

Damage and overbreak of the remaining rock induced by blasting can not be avoided during tunnel construction which may result in either short-term or long-term tunnel instability. Therefore, in this paper, a methodology to take into account the effect of blast-induced damage in tunnel stability assessment is proposed. Dynamic numerical analysis was executed to evaluate damage and overbreak of the remaining rock for the most common blasting pattern in road tunnel. Rock damage was quantified by utilizing the damage variable factor which is adopted proposed in continuum damage mechanics. The damaged rock stiffness and the damaged failure criteria are used to consider the effect of rock damage in tunnel stability analysis. The damaged geological strength index of the damaged rock was newly proposed from the relationship between deformation modulus and geological strength index. Also the Hoek-Brown failure criteria of the damaged rock was obtained using the damaged geological strength index. Analysing the tunnel stability with the consideration of the blast-induced damage of remaining rock, it was found that the extend of plastic zone and deformation increased compared to the undamaged rock. Therefore the short-term or long-term tunnel stability will be threatened when the rock damage from blasting is ignored in the tunnel stability analysis.

• Proceedings of the KIPE Conference
• /
• 2013.07a
• /
• pp.429-430
• /
• 2013

대용량 계통연계형 인버터에서 필터의 사이즈와 가격을 줄이고, 빠른 동적 특성을 얻기 위해서 LCL필터가 많이 사용된다. LCL필터 설계 시에 계통으로 유입되는 고조파 전류를 제한하는 것이 주된 목적이지만, LCL필터가 가지는 공진 특성 또한 고려되어야 한다. 그리고 인버터 전류 피드백으로 전류 제어 루프를 구성하는 경우와는 달리 계통 전류 피드백으로 인버터의 전류 제어 루프를 구성하게 되면 전자보다 더 안정적인 운전영역을 확보하게 된다. 하지만 이러한 운전영역 또한 LCL필터를 어떻게 설계하느냐에 따라 달라진다. 본 논문에서는 계통전류의 고조파 제한과 함께 전류제어기의 안정성을 고려한 LCL필터 설계 기법을 제안하고자 한다. 제안된 설계 기법을 통해서 얻어진 결과를 7.5kW급 계통연계형 인버터 시작품을 통해서 검증하였다.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.13 no.12
• /
• pp.947-955
• /
• 2003

This research analyzes the dynamic stability of stiffened plates on elastic foundations using the finite element method. For analyzing the stiffened plates, both the Mindlin plate theory and Timoshenko beam-column theory were applied. In application of the finite element method, 8-nodes serendipity element system and 3-nodes finite element system were used for plate and beam elements, respectively Elastic foundations were modeled as the Pasternak foundations in which the continuity effect of foundation is considered. In order to verify the theory of this study, solutions obtained by this analysis were compared with the classical solutions in open literature and experimental solutions. The dynamic stability legions of stiffened plates on Pasternak foundations were determined according to changes of in-plane stresses, foundation parameters and dimensions of stiffener.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.34 no.9
• /
• pp.859-866
• /
• 2010

Nonlinear dynamics of pulsating instability-diffusional-thermal instability with Lewis numbers sufficiently higher than unity-in counterflow diffusion flames, is numerically investigated by imposing a Damkohler number perturbation. The flame evolution exhibits three types of nonlinear behaviors, namely, decaying pulsating behavior, diverging behavior (which leads to extinction), and stable limit-cycle behavior. The stable limit-cycle behavior is observed in counterflow diffusion flames, but not in diffusion flames with a stagnant mixing layer. The critical value of the perturbed Damkohler number, which indicates the region where the three different flame behaviors can be observed, is obtained. A stable simple limit cycle, in which two supercritical Hopf bifurcations exist, is found in a narrow range of Damkohler numbers. As the flame temperature is increased, the stable simple limit cycle disappears and an unstable limit cycle corresponding to subcritical Hopf bifurcation appears. The period-doubling bifurcation is found to occur in a certain range of Damkohler numbers and temperatures, which leads to extend the lower boundary of supercritical Hopf bifurcation.

• Tunnel and Underground Space
• /
• v.28 no.5
• /
• pp.457-475
• /
• 2018

For increase of reality in numerical analysis, a blasting vibration waveform obtained from field blast operations has been directly used for input parameters of dynamic analysis in the form of vibration velocity. A numerical model was built considering the geological characteristics of underground limestone opening as well as the mining stages in this opening, and the effect of blast operations on stability of underground limestone opening was investigated by dynamic numerical analysis. The adequacy of applying the real vibration waveform to dynamic analysis has been approved from the preliminary analysis, and the dynamic numerical analysis results show that the continuous mining operation can cause the collapse of roof in openings and the active yield zone around openings. Therefore, the additional reinforcements should be applied for ensuring the stability of underground limestone openings.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 1999.10a
• /
• pp.23-23
• /
• 1999

일반적인 제어대상 시스템을 모델링하여 제어기를 설계할 경우 시스템을 제어하는 액츄에이터의 saturation 현상을 무시하고 설계하는 경우가 자주 있다. 만일 시스템이 SISO이며, 충분히 안정하고 동적 특성이 빠른 경우에는 saturation 무시가 주는 영향이 크게 나타나지 않지만, 만일 시스템이 MIMO이며 비선형일 경우 비선형 요소인 입력 saturation에 의하여 시스템의 특성이 변형되고 크게는 불안정화 된다.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.10 no.2
• /
• pp.392-397
• /
• 2006

This paper proposed yaw moment control scheme using braking and active rear wheel steering for improving driving stability especially in high speed driving. Its characteristics the unified chassis control system of two equipment that 4WS(4 Wheel Steering) and ESP(Electronic Stability Program). in this study the performance of the vehicle was compared each equipment. And conventional ABS and TCS can only possible to control the longitudinal movement of braking equipment and drive which can only available to control of longitudinal direction. There after new braking system ESP was developed, which controls both of longitudinal and lateral, with adding of the function of controlling Active Yaw Moment. On this paper, we show about not only designing of improved braking and steering system through establishing of the integrated control system design of 4WS and ESP but also designing of the system contribute to precautious for advanced vehicle stability problem.

• Journal of KIISE:Information Networking
• /
• v.27 no.4
• /
• pp.522-530
• /
• 2000

네트워킹 환경에서 만족스러운 멀티미디어 응용 서비스를 제공하기 위해서는 효과적인 미디어 전송 구조가 필요하다. 그러나 인터넷 같은 일반적인 네트워크는 안정적인 멀티미디어 서비스를 위한 보장된 네트워크 대역폭을 제공하지 않는다. 따라서 종단 시스템에서 멀티미디어 서비스를 지원하기 위한 일반적인 방법으로 버퍼를 사용한다. 기존의 제안된 버퍼 관리 기법은 크게 두가지 영역으로 분류된다. 하나는 변화하는 네트워크 환경에 적응하기 위한 기법이고 다른하나는 요구 대역폭을 평활하하는 기법이다. 그러나 전자는 서비스 풉질의 심각한 손실을 일으킬 수 있고 후자는 동적인 네트워크 환경에 적응할 수 없다는 단점이 있다. 본 논문에서는 동적인 네트워크에 적응하며 대역폭 평활화를 통해 더 좋은 서비스 품질을 제공하는 적응성 있는 대역폭 평활화 기법을 제안한다. 또한 저장된 MPEG 비디오를 이용한 실험을 통해 제안된 기법의 사용으로 비디오 전송 품질이 향상됨을 보인다.