• 대한산업공학회지
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• 제27권1호
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• pp.11-17
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• 2001

We consider the M/G/1 with Bernoulli feedback, where the served customers wait in the feedback queue for rework with probability p. It is important to decide the moment of dispatching in feedback systems because of the dispatching cost for rework. Up to date, researches have analyzed for the instantaneous-dispatching model or the case that dispatching epoch is determined by the state of feedback queue. In this paper we deal with a dispatching model whose dispatching epoch depends on main queue. We adopt supplementary variable method for our model and a numerical example is given for clarity.

• Journal of Electrical Engineering and information Science
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• 제3권2호
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• pp.193-201
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• 1998

In this paper, the standard Dole, Glover, Khargoneker, and Francis (abbr. : DGKF 1989) H\ulcorner controller (H\ulcornerC) is extended to the nonlinear feedback linearization-H\ulcorner/sliding mode controller (NFL-H\ulcorner/SMC), to tackle the problem of the unmeasurable state variables as in the conventional SMC, to obtain smooth control as the linearized controller in a linear system, and to improve the time-domain performance under a worst scenario. The proposed controller is obtained by combining the H\ulcorner estimator with the nonlinear feedback linearization-sliding mode controller (NFL-SMC) and it does not need to measure all the state variables as in the traditional SMC. The proposed controller is applied as a nonlinear power system stabilizer (PSS) for the improvement of the power system damping characteristics of an single machine infinite bus system (SMIBS) connected through a double circuit line. The effectiveness of the proposed controller is verified by nonlinear time-domain simulation in case of a 3-cycle line-to-ground fault and in case of the parameter variations for the AVR gain K\ulcorner and for the inertia moment M.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.1934-1937
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• 2005

This paper proposes suitable gait generation for dynamic walking of biped robot with varying load in real time. Author proposes the relationship between ZMP(Zero Moment Point) and measurement from FSR(Force Sensing Register). Simplifying this relationship, it is possible to reduce the computational time and control the biped robot in real time. If the weight of the biped robot varies in order to move some object, then joint trajectories of the the biped robot must be changed. When some object is loaded on the biped robot in it's home position, FSRs can measure the variation of weight. Evaluating the relations between varying load and stable gait of the biped robot, it can walk adaptively. This relation enables the biped robot to walk properly with varying load. The simulation is also represented in this paper which shows proposed relationships.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 춘계학술대회 논문집 전기설비전문위원
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• pp.166-168
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• 2009

In this paper, we studied fire sensing and position tracing system in fire region. The coordinates of fire position is communicated to fire suppression system immediately. And the fire is suppressed by this system effectively. For the purpose, the fire occurrence region images are extracted with two different CCD surveillance cameras and fire occurrence are sensed, I suggested a method to measure the fire occurrence position. It was able to be sensed early experiment result fire outbreak and, I was able to understand a fire outbreak position coordinate at the moment when a fire occurred and, I confirmed that I could accomplish warning official announcement and fire suppression in an auto.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 춘계학술대회 논문집
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• pp.724-728
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• 1996

The instrumented Charpy impact test is generally used to evaluate the dynamic fracture toughness for varying engineering materials. However, the test is known to be difficult to evaluate the dynamic fracture toughness for very brittle materials because of the small crack initiation load. To evaluate the dynamic fracture toughness of verybrittle materials, it is necessary to develop a load sensitive instrumented tup. In this study, a polymer tup, which has small Young's modulus, is used for the instrumented Charpyimpact test and a proper testing method is developed. The results show that the developed method can measure rapidly changing loads from the moment of contact between the tup and the specimen to dynamic crack initation of the very brittle materials.

• 한국안전학회지
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• 제32권5호
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• pp.122-128
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• 2017

Korean government announced long-term railway safety investment plan for the safety improvement by 2020. But no research have been done about differential analysis on railroad safety investment and safety improvement. In this study, recent 10 year data on safety investments and accident data are analysed for the differential analysis. Three main safety investments are analysed on regard to accident rate and accident fatalities. Three safety measures include level crossing accident, platform fatalities, and track trespass fatalities. About 90% of railway accident fatalities are caused by these three kind of accidents. Differential analysis shows about 4 to 6 years delay after railroad safety investment and safety improvement. This result can be utilized for the decision making on safety measures and safety target. Which required long term approach.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집A
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• pp.806-811
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• 2001

To develop design and evaluation technologies of automotive seat frames, structural analysis and fatigue tests have been performed. Under the back moment loading condition, the numerical simulation yielded the maximum stress over the yield strength at the side frame bracket. To measure the stresses under the test condition, strain gauges were attached on some weakest points of the side frames. the measured strains are in good agreements with the CAE results. On the other hand, fatigue tests have been performed using the side frame bracket specimens made of various welding types to estimate their durabilities. From the fatigue test results and the analysis ones, it was recommended that the welding position of the bracket should be moved upward.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 전력전자학술대회 논문집
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• pp.234-238
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• 1998

Parameter estimation of induction motor for vector control presented in this paper can be easily implemented and applied to inverters in the industrial field, because it needs no additional hardware such as voltage sensor and measuring equipment. At first, the stator resistance including switching loss of inverter is measured by simple voltage-current equation. Next, in pre-magnetization of machine by imposing the d-axis constant field-current, q-axis torque current is forced to the machine until its speed feedback reachs to pre-defined level of speed limit. At this time, we can measure the rotor time-constant by decreasing the distorted output-voltage of inverter. At last, stator inductance, transient inductance, and moment of inertia can be measured by the relationship of output voltage, output torque and speed feedback. The validity and usufulness of this method is verified by experimental results.

• 한국자동차공학회논문집
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• 제12권4호
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• pp.50-57
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• 2004

Structural analysis and fatigue tests have been performed to develop design and evaluation technologies of automotive seat frames. Under the back moment loading condition, the numerical simulation unveiled the maximum stress up to the yield strength at the side frame bracket. To measure the stresses under the test condition, strain gauges were attached to some weakest points of the side frames. the measured strains are in good agreements with the CAE results. On the other hand, some fatigue tests have been performed using the side frame bracket specimens made of various welding types to evaluate their durabilities. From the fatigue tests and the numerical analyses, it was recommended that the bracket welding position should be moved upward.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1994년도 추계학술대회 논문집
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• pp.653-657
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• 1994

A symbolic performance analysis approach for flexible for manufactring systems (FMS) can be formulated based on the integration of Petri Nets (PN) and moment generating function (MGF) concept. In this method, generalized stochastic Petri Nets are used to define performance models for FMS, then MGF nased approach for evaluating stochastic PN is used to derive performance parameters of PN, and finally system performance is calculated. A GSPN model of machine cell is shown to illustrate the proposed method for evaluating such performance indices as production rate, utilization, work-in-process and lead time. The major advantage of this method over existing performance evaluation of FMS is the ability to compute symbolic solutions for performance. Finally future research toward automating performance measure for GSPN models of FMS is discussed.