• Journal of Mechanical Science and Technology
• /
• v.14 no.5
• /
• pp.547-552
• /
• 2000

The objective of this paper is to present a modified fractional step method of keeping a constant mass flow rate in spatially periodic flows, because original fractional step methods do not precisely keep the mass flow rate constant in time. In the modified method, the mean and fluctuating pseudo-pressure gradients are separately obtained at each time step. This method is successfully applied to channel and pipe flows and shown to be suitable for maintaining a constant mass flow rate in time.

• Proceedings of the Korean Institute of Intelligent Systems Conference
• /
• 2003.09a
• /
• pp.579-582
• /
• 2003

In this paper, we propose a 4-step inference method needed for constructing a natural language communication system. The method is used to obtain fuzzy quantifier Q′when QA is Fisr τ⇔ Q′(m′A) is mF is m"is τ is inferred (Q, Q′: quantifiers, A: fuzzy subject, m′, m": modifiers, y: fuzzy predicate, τ: truth qualifier). We show that Q′is resolved step by step for two types of Q, including a non-increasing type (few,...) and a non-decreasing type(most,...).

• Proceedings of the Korean Society of Broadcast Engineers Conference
• /
• 1995.06a
• /
• pp.143-148
• /
• 1995

In this paper, we describe a fast 3D video segmentation method using mathematical morphology. The proposed 3D video segmentation algorithm is composed of intra-frame segmentation step and inter-frame segmentation step. In the intra-frame segmentation step, the first frame is segmented using the fast hierarchical segmentation method. Then, in the inter-frame segmentation step, the next frames are segmented using markers that are extracted from the difference of previous segmentation result and simplified present image. Experimental results show that the proposed method has more fast structure and is suitable for video segmentation.

• Proceedings of the KIPE Conference
• /
• 1997.07a
• /
• pp.318-321
• /
• 1997

This paper is about improving characteristic of plant by using micro-step driver method in 5 phase step motor for satisfying the condition of low oscillation and high accuracy in soldering machine. We choose open loop control method for minimizing hardware system and use one chip microprocessor, power MOSFET nd some device to realize accurate micro-step driver system.

• East Asian mathematical journal
• /
• v.18 no.2
• /
• pp.261-270
• /
• 2002

We obtain the convergence of three-step iteration methods and generalized three-step iteration methods for quasi-contractive and generalized quasi-contractive mappings, respectively, in Banach spaces. Our results extend the corresponding results in [1], [4]-[6].

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.19 no.5
• /
• pp.72-81
• /
• 2018

In this study, the sinusoidal-wave driving method, six-step driving method, and twelve-step driving method, which can be used in an inverter for permanent-magnet synchronous motors, were simulated, and the results were compared to review their operating performance. These driving methods were classified according to the electrical conduction angle and phase current of the motor. Conventionally, only the transition control technique between the sinusoidal-wave driving method and six-step driving method was studied for the efficiency of the inverter. In this paper, however, comparative analysis was focused on a variety of transition control applications to use the advantages of each driving method. For this purpose, computer simulations for these driving methods were carried out to obtain the motor torque, speed control characteristics, and THD of the motor phase currents. As a result, the sinusoidal-wave driving method showed the best performance in all respects. The six-step driving method has better speed control characteristics than the twelve-step driving method, and the twelve-step driving method has a lower THD of the motor phase currents than the six-step driving method.

• Structural Engineering and Mechanics
• /
• v.8 no.6
• /
• pp.561-578
• /
• 1999

The response of a reinforced concrete structure to loading is both immediate and time-dependent. Under a sustained load, the deflections caused by creep and shrinkage may be several times their instantaneous values. The paper describes a general finite element procedure, based on the so-called layered model, to analyse reinforced concrete members, and shows in particular how the simple Step by Step Method may be incorporated into this procedure. By invoking the Modified Newton Raphson Method as a solution procedure, the accuracy of the finite element method is verified against independent test results, and then applied to a variety of problems in order to demonstrate its efficacy. The method forms a general method for analysing highly indeterminate concrete structures in the time domain.

• Journal of the Korean Institute of Gas
• /
• v.18 no.4
• /
• pp.76-85
• /
• 2014

To establish the necessary safety technology in high-pressure toxic gas facilities, especially for the corrosion, which is the main causes of toxic gas accident, this study adopts and investigates the API-581 procedures developed by the American Petroleum Institute (API). And the applicability of the 8-step analytical procedures of consequence analysis in API-581 is discussed, and a method for consequence analysis in high-pressure toxic gas facilities is suggested. Based on the discussion and results, the analytical procedure is simplified as the 6 steps in total for the effective application to high-pressure toxic gas facilities: Step 1 (determination of representative material), Step 5 (determination of release type), Step 6 (determination of phase of fluid), and Step 8 (estimation of damage range) are not applied: Step 3 (estimation of total amount of release) is applied only for the inventory group concept; Step 4 (estimation of release rate) only for the gas release rate; and all of Step 2 (selection of release hole size) and Step 7 (evaluation of post-release response) are applied. In the proposed method, the generally applicable method of CCPS is adopted as alternative method for Steps 5 and 8.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.9 no.3
• /
• pp.132-140
• /
• 2006

In this paper, a new fault detection method for the extended Kalman filter, which uses a N-step predictor, is proposed. The N-step predictor performs the only time propagations for N-step intervals without measurement updates and its output is used as a monitoring signal for the fault detection. A consistency between the extended Kalman filter and the N-step predictor is tested to detect a fault. A test statistic is defined by the difference between the extended Kalman filter and the N-step predictor. The proposed method is applied to strapdown inertial navigation system (SDINS). By computer simulation, it is shown that the proposed method detects a fault effectively.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.23 no.6
• /
• pp.888-894
• /
• 1986

In this paper, a phase locked loop control system is designed to have high performance and stability in a 2-phase bifilar winding PM step motor. The BODE diagram analysis method is used to improve the stability and dynamic characteristic of the closed loop control system. Also, a PLL servo is used to accomplish high-precision speed and to attain smooth ness. In applying the PLL control to the step motor, a new design method is suggested to solve the control problem which occurs as a result of the limited maximum acceleration of the step motor. A simple design method is suggested without using the complicated multi-step characteirstic of the step motor in constant voltage driving. Computer simulation results agree clorelg with experiments, indicating that the PLL servo system of the step motor designed is very useful.