• Korean journal of applied entomology
• /
• 제29권3호
• /
• pp.190-193
• /
• 1990

To establish the successive rearing method of the perilla leaf pyralid, Prausta panopealis Walker, experiments were carried out wiht three diets based on a JAMSI-type artificial die for silkworm. On the SS4 diet containing 40% of perilla leaf powder the pupal and adult yields were higher than those on th fresh green perilla leaves.

• East Asian mathematical journal
• /
• 제29권4호
• /
• pp.425-447
• /
• 2013

Since the center of mass of mathematics curriculum in middle school is dealt with only on triangle and it is defined as just an intersection point of median lines without any physical experiments, students sometimes have misconception of the centroid as well as it is difficult to promote divergent thinking that enables students to think the centroids of various figures. To overcome these problems and to instruct effectively the centroid unit in middle school mathematics classroom, this study suggests a teaching and learning method for the unit which uses physical experiments, drawing, and calculation methods sequentially based on the investigation of students' understanding on the centroid of triangle and the analysis of the mathematics textbooks.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 한국항해항만학회 2019년도 추계학술대회
• /
• pp.130-133
• /
• 2019

수중(submerged)에 부유(floating)식으로 계류되는 거주목적의 구조체 설계(design basis) 관련 연구로서 계류안정성 모델(수중가옥)을 만들고 거동을 정수압적 유체역학적으로 수치분석한다. 임의 가정한 수중가옥의 1)배수량 규모 2) 함체형상에 따른 환경압 하에서의 계류안정성을 a)부력중심, b)무게중심과 가변하중의 변위에 따른 c)함체 기울기를 MATLAB프로그램을 이용하여 산정한다. 나아가 수중가옥의 동적(hydrodynamic) 계류안정성을 임의 시공 장소인 독도의 기상청 울릉도-독도 부이 최근 관측치를 근거로 OrcaFlex프로그램을 이용하여 분석하므로써 수중가옥의 수중건축 시공간상 계류안정성 설계요건(design basis)을 구체화 한다.

• Proceedings of the IEEK Conference
• /
• 대한전자공학회 2005년도 추계종합학술대회
• /
• pp.631-634
• /
• 2005

This paper has been studied a optical fiber sensor offer important advantages such as electrically passive operation, EMI immunity, high sensitivity, and multi-plexing capabilities of this technology has been the characteristic. The shift in optical fiber Bragg wavelength with mass can be expressed. Using the shift in the optical fiber Bragg grating(FBG) center wavelength due to mass change.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• 제66권5호
• /
• pp.812-818
• /
• 2017

In this paper, we design a reduced-order disturbance observer (DOB) controller for an EMS (Electro-Magnetic Suspension) system with mass uncertainty. Compared with conventional DOB controller, the proposed reduced-order DOB controller can be implemented in a simpler way, since it uses reduced order nominal model and Q-filter. It is shown that the nominal model for the proposed DOB controller should be carefully chosen in order to achieve the robust stability in the present of mass uncertainty. Computer simulation results to validate the effectiveness of the proposed DOB controller are included.

• Journal of Institute of Control, Robotics and Systems
• /
• 제14권9호
• /
• pp.886-892
• /
• 2008

In this paper, a closed-loop observer to extract the center of mass (CoM) of a bipedal robot is suggested. Comparing with the simple conversion method of just using joint angle measurements, it enables to get more reliable estimates by fusing both joint angle measurements and F/T sensor outputs at ankle joints. First, a nonlinear-type observer is constructed to estimate the flexible rotational motion of the biped in the extended Kalman filter framework. It adopts the flexible inverted pendulum model which is appropriate to address the flexible motion of bipeds, specifically in the single support phase. The predicted estimates of CoM in terms of the flexible motion observer are combined with measurements (that is, output of the CoM conversion equation with joint angles). Then, we have final CoM estimates depending on the weighting values which penalize the flexible motion model and the CoM conversion equation. Simulation results show the effectiveness of the proposed algorithm.

• The Transactions of the Korean Institute of Electrical Engineers D
• /
• 제49권10호
• /
• pp.563-571
• /
• 2000

In this paper, a nonlinear adaptive control method for an EMS(Electro-Magnetic Suspension) system with mass uncertainty is proposed. Using the coordinate transformation and feedback linearizing control, EMS system has been transformed into the form of parametric strict-feedback system with unknown virtual control coefficients. With this transformed system, tuning functions approach, which is an advanced from of adaptive backstepping, has been applied in order to stabilize the system against mass uncertainty. Computer simulation is also carried out in order to compare the performance of the proposed controller with that of feedback linerizing controller.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• 제40권2호
• /
• pp.157-164
• /
• 2012

The design strategy of the multi-functional structure is that the electrical components and the circuits are directly put on their supporting structural panel in which the radiation shields and the thermal control functions are integrated. Applying the multi-functional structure reduces the total mass and size of the space system and makes it possible to lower launch cost. In present study the performance of thermal radiation for six types of multi-functional structure are investigated by the numerical method. The effect of the rib configuration on heat transfer for the multi-functional-structure is not important alone but is meaningful considering with the structural stiffness, difficulty of manufacturing and mass increase. In heat spreading point of view, the thickness of the outer conductive layer is important rather than the rib configuration and the trade-off study with the mass and thickness is required for optimum design.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• 제49권9호
• /
• pp.749-757
• /
• 2021

In transportation missions using quadrotor, the payload may change the model parameters, such as mass, moment of inertia, and center of gravity. Moreover, if position of the payload is constantly changing during flight, the effect can adversely affect the control performances. To handle this issue, we suggest Model Reference Adaptive Control based on Linear Quadratic Regulator(LQR+MRAC) to compensate the uncertainty caused by payload. Firstly, the mathematical modeling with the fixed payload is derived. Second, Linear Quadratic Regulator (LQR) is used to design the reference model and baseline controller. Also, through the Stability method, Adaptive law is derived to estimate the model parameters. To verify the performance of proposed control scheme, we compared LQR and LQR+MRAC in situations where uncertainties exist. And, when the disturbance exist, the classic MRAC and proposed controller is compared to analyze the transient response and robustness.

• Journal of the korean academy of Pediatric Dentistry
• /
• 제28권3호
• /
• pp.403-411
• /
• 2001

The aim of this study was to evaluate the resistance to degradation of four commercial composite resins in an alkaline solution. The brands studied were Unifil(GC, Japan), Palfique(Tokuyama Japan). Definite$Degussa-H\ddot{u}ls$ AG, Germany). Revolution(Kerr, U.S.A.). Preweighed discs of each brand were exposed 0.1N NaOH solution at $60^{\circ}C$. After 14 days they were removed, neutralized with HCl, washed with water and dried. Resistance to degradation was evaluated on the basis of following parameters: (a) mass loss(%) - determined from pre-and post-exposed specimen weights; (b) Si loss(ppm) - obtained from ICP-AE analysis of solution exposed to specimens; and (c) degradation depth$({\mu}m)$ - measured microscopically (SEM) from polished circular sections of exposed specimens. The results were follows: 1. The mass loss of Unifil was 3.21%, it was the highest of materials. But, there was no significant difference among the materials. 2. The degree of degradation layer depth was $107.69\sim47.40{\mu}m$, the sequence of the degree pf degradation layer depth was in descending order by Unifil, Palfique, Revolution, Definite. There was significant difference among the materials except Palfique and Definite. 3. The Si loss of Paltique was 8940.0ppm, it was the highest. There was significant difference among the materials, except Revolution and Definite(p<0.05). 4. The correlation coefficient between mass loss and degradation depth was relatively high(r = 0.06, p<0.05). 5. There was no significant coefficient correlation between Si loss and mass loss, and/or the degree of degradation layer depth and Si loss. 6. When observed with SEM, destruction of bonding is observed between resin matrix and filler. Above results suggested that the hydrolytic degradation is considered as evaluation factor of composite resins.