• 한국기계가공학회지
• /
• 제7권3호
• /
• pp.96-102
• /
• 2008

In order to design establish automation or optimization of the machining process, predictions of the forces in machining are often needed. In this paper, a theoretical model in face milling is presented based on Oxley's predictive machining theory, where the cutting forces are predicted from input data of fundamental work material properties, tool geometry and cutting conditions without any preliminary cutting experiment. A simulation system for the cutting forces in face milling is developed using the model. Milling experimental tests are conducted to verify the model and the predictive results are compared and discussed with the experimental results.

• 산업기술연구
• /
• 제21권B호
• /
• pp.117-123
• /
• 2001

In a modern control field, a control engineer who has theoretical backgrounds with some practical knowledge is demanded. That is to say, an engineer who can understand and operate the various parts such as modeling, simulation, system analysis, signal processing, statistics, and hardware is required. In order to prove the theoretical backgrounds and operate various hardwares, a lot of experimental devices for students are designed in universities. Since the conventional experimental devices are manufactured abroad and the prices of the devices are too high, it is difficult to have. If a low cost experimental device can be developed, it will be very useful for a control engineering education. In Ibis paper, an experimental rig which has two control inputs and three sensor outputs to control the end point of a flexible beam is designed and manufactured. This rig can be used for a control field education.

• International Journal of Concrete Structures and Materials
• /
• 제4권1호
• /
• pp.37-43
• /
• 2010

Theoretical models based on modern interpretations of the morphology and interactions of cement hydration products are developed for prediction of the mechanical properties of hydrated cement paste (hcp). The models are based on the emerging nanostructural vision of calcium silicate hydrate (C-S-H) morphology, and account for the intermolecular interactions between nano-scale calcium C-S-H particles. The models also incorporate the effects of capillary porosity and microcracking within hydrated cement paste. The intrinsic modulus of elasticity and tensile strength of hydrated cement paste are determined based on intermolecular interactions between C-S-H nano-particles. Modeling of fracture toughness indicates that frictional pull-out of the micro-scale calcium hydroxide (CH) platelets makes major contributions to the fracture energy of hcp. A tensile strength model was developed for hcp based on the linear elastic fracture mechanics theories. The predicted theoretical models are in reasonable agreements with empirical models developed based on the experimental performance of hcp.

• 한국자동차공학회논문집
• /
• 제21권4호
• /
• pp.188-194
• /
• 2013

Hydrostatic pumps and motors occupy an important position in hydraulic system. There are a lot of researches on characteristics of hydraulic pumps, but not hydraulic motors. So in order to know the characteristics of hydraulic motors we had this research. The purpose of this study is to derive and analyze the theoretical calculation of hydraulic axial piston motor torque and torque ripples. Then, analyzed the differences between torque ripples with dead place and without dead place on the valve plate, and modeling a hydraulic motor with AMESim software. Finally, theoretical calculation of hydraulic motor torque ripples was verified from the viewpoint of simulation.

• Journal of Mechanical Science and Technology
• /
• 제16권12호
• /
• pp.1643-1651
• /
• 2002

Magnetic levitation systems are required to have a large operating range in many applications. As one method to solve this problem, Time Delay Control (TDC) is applied to a single-axis magnetic levitation system in this paper A reduced-order observer is utilized to estimate states excluding measurable states in the control law. The system consists of a square air-core solenoid and a circular permanent magnet attached on a plastic ball. Theoretical magnetic forces of the system are obtained on the basis of the location of the magnet around the solenoid. The magnetic levitation force is obtained by the experiment, and then compared with the theoretical one. As the results of the control experiments, the nonlinear controller (TDC : 1-2 ㎜) has a larger operating range than the linear controller (PD control : 1-1.4 ㎜), and is superior to linear. control in the robustness to the modeling uncertainty and the performance of the disturbance rejection.

• 대한원격탐사학회:학술대회논문집
• /
• 대한원격탐사학회 1999년도 Proceedings of International Symposium on Remote Sensing
• /
• pp.154-157
• /
• 1999

Microwave polarimetric backscattering from a wet soil surface had been measured using a Ku-band polarimetric scatterometer at the incidence angles ranging from 10$^{\circ}$ to 70$^{\circ}$ Since the accurate target parameters as well as the radar parameters are necessary for radar scattering modeling, a complete and accurate set of ground truth data were also collected, from which accurate measurements were made of the rms height, correlation length, and dielectric constant. The measured polarimetric backscattering coefficients (vv-, hh-, vh-, hv-polarizations) were compared with theoretical models and empirical models. A new semi-empirical model for microwave polarimetric radar backscattering from bare soil surfaces was developed using polarimetric radar measurements and the knowledge based on the theoretical and numerical solutions. The model was found to yield very good agreement with the backscattering measurements of this study.

• 한국경영과학회:학술대회논문집
• /
• 한국경영과학회 1993년도 추계학술대회발표논문집; 서강대학교, 서울; 25 Sep. 1993
• /
• pp.175-184
• /
• 1993

Modeling the production process is a necessary and essential aspect of the production planning. This paper introduces a theoretical model of the multi-stage production process. A multi-stage production process is regarded as a network of interrelated production activities which use system exogenous inputs of goods in production and the intermediate products transfers between activities to produce final products. Our model is characterized by (1) a few of the production-related assumptions and (2) two types of elements "goods and activities" that are represented in terms of the network terminology. This model is different from the another multi-stage production models, so-called production network models in relation to the production-theoretical concept. It is not based on the concept of the production correspondence and the activity production functions, but the technology model of Koopmans. Koopmans.

• 경영과학
• /
• 제29권2호
• /
• pp.105-125
• /
• 2012

As medical service industry is transformed into the market centered on consumers, medical service quality patients recognize is emphasized as the powerful means to ensure competitive advantage among hospitals in the fierce medical markets. Many researches have been done on the definition of medical service quality, developing a scale to measure it, patient satisfaction, hospital repurchase and oral transmission intention, but integrated studies have not been done sufficiently on the patient' cognitive emotional aspects. For these research purposes, based on service relation, service quality, physical surroundings, human services, corporate reputation, service value, emotional response, customer satisfaction and repurchase intention, this paper suggests a theoretical modeling composed of hypotheses on the relations of each theoretical variable. In addition, the moderating effect of service relationships is investigated based on the structural equation model.

• Journal of Welding and Joining
• /
• 제11권2호
• /
• pp.62-73
• /
• 1993

Weld pool oscillation for the full-penetration GTA welding process was investigated for its possible application to weld penetration control through theoretical modeling and experiment. Energy method was used to estimate the natural frequency of the molten pool having the physically-acceptable weld geometry and oscillation modes. An unique experimental system was built which had the data acquisiton and video capabilities so that the pool oscillation signals and molten pool surfaces could be monitored continuously. Pool oscillation was detected through arc voltage and arc light emission simultaneously. The signal from arc light emission showed good coherence with that from arc voltage, and arc light generated the higher quality signal. The molten pool was found to oscillate in different oscillation modes based on the travel speed and weld geometry. The natural frequency estimated from the theoretical model agreed reasonably well with the experimental results.

• Journal of the Optical Society of Korea
• /
• 제11권4호
• /
• pp.153-157
• /
• 2007

We have proposed an application of disturbance observer with PID controller to minimize gain-transient time of wavelength-division-multiplexing(WDM) multi channels in optical amplifier in channel add/drop networks. We have dramatically reduced the gain-transient time to less than $3{\mu}sec$ by applying a disturbance observer with a proportional/integral/ differential(PID) controller to the control of amplifier gain. The theoretical analysis on the 3-level erbium-doped fiber laser and the disturbance observer technique is demonstrated by performing the simulation with co-simulation of the $MATLAB^{TM}$ and a numerical modeling software package such as the $Optsim^{TM}$.