• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.12
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• pp.2678-2686
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• 2002

A novel approach is developed for avoidance of obstacles in unknown environment. This paper proposes a new way of intelligent autonomous wheelchairs for the handicapped to move safely and comfortably. It is the objective of this paper to develop delayed time fuzzy control algorithms to deal with various obstacles. This new algorithm gives the benefit of the collision free movement in real time and optimal path to the moving target. The computer simulations and the experiments are demonstrated to the effect of the suggested control method.

• Journal of the Korean Society of Safety
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• v.27 no.5
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• pp.135-140
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• 2012

In this study, the behavior of pollutant was calculated at Paldang reservior according to several scenarios of the accidental water pollution by means of the numerical models for forecasting water quality. Also managemental plans for situation of the accidental water pollution happening at Paldang watershed were simulated. According to the simulating results, a plan of increase of discharge at Cheongpyeong dam reduced the peak concentration of pollutants, whereas extended the time for stopping water intake. Another plan, drop of water elevation at Paldang dam, decreased seriously the time for stopping water intake although there were a little effect to decrease the peak concentration. Thus it was concluded that appropriate combinations of the plans for the increase discharge and the dropping water elevation should be used to deal with the accidental water pollution at Paldang watershed.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10a
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• pp.555-558
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• 2000

It has been increasingly proving in interest of environment pollution around the world. so, recycling of waste resources are seriously taken into consideration. Great deal of coolant for the car have been wasted for along time. due to the end of life time of them. Therefore, validities of wasted coolant as an agent for concrete are described in this paper. Mechanical properties of concrete using coolant wastes is investigated. As contents of coolant wastes increase, slump and slump flow decrease, while air content show reverse tendency. setting time shows to be accelerated with increase of waste contents. As for the effect of low curing temperature, low curing temperature increase compressive strength with increase of coolant waste. Application of coolant waste to cold weather concrete is considered to achieve favorable effects.

• 전기의세계
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• v.28 no.7
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• pp.60-66
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• 1979

In this paper we deal with a hardware redundency, using the replications of an original module to enhance the reliability of the system in view of static and dynamic redundancy. As results of the study the following facts have been proved that (1) if the mission time is small (T .neq. 0.5), the effect of spare modules cannot be expected significantly, (2) for the small mission time (0.1 .neq. T .neq. 0.3) the SPR system is more reliable than the other redundant systems. In addition to above facts, it is also proved that for the large mission time (T=1), the dynamic redundant system is more reliable than the static redundant system, and that the SR system is more reliable than the HR system in the dynamic redundant system.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.53 no.10
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• pp.530-538
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• 2004

A electromagnetic waves are used for sensing in insulation diagnosis at electric machine or equipment. When it a method, waves are transformed into the FFT(Fast Fourier Transform); a kind of the process for data transformation. In a general way, a scientist use frequncy band 30[㎒]～l[㎓] to applied field. If we are measured high frequency band, we will need to a high capacity hardware. Also a antenna has a fault on atmospheric phenomena, outside environment and the like. In this paper We proposed new method for detecting electric equipment faulty state using only electric voltage which is generally measured in the electric and electronic field. It is called the Partition-FFT The analytic method is this first divide measured voltage waves into equal parts, second each deal with give effect to the FFT, finally each results deal with a graphic method and gather graphic. We are compare Partition-FFT with discharge form by tracking tester. As the result it demonstrated that the Partition-FFT is applicable.

• International journal of advanced smart convergence
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• v.5 no.1
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• pp.34-46
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• 2016

Networked Control System (NCS) has evolved in the past decade through the advances in communication technology. The problems involved in NCS are broadly classified into two categories namely network issues due to network and control performance due to system network. The network problems are related to bandwidth allocation, scheduling and network security, and the control problems deal with stability analysis and delay compensation. Various delays with variable length occur due to sharing a common network medium. Though most delays are very less and mostly neglected, the network induced delay is significant. It occurs when sensors, actuators, and controllers exchange data packet across the communication network. Networked induced delay arises from sensor to controller and controller to actuator. This paper presents an adaptive delay compensation process for efficient control. Though Smith predictor has been commonly used as dead time compensators, it is not adaptive to match with the stochastic behavior of network characteristics. Time delay adaptive compensation gives an effective control to solve dead time, and creates a virtual environment using the plant model and computed delay which is used to compensate the effect of delay. This approach is simulated using TrueTime simulator that is a Matlab Simulink based simulator facilitates co-simulation of controller task execution in real-time kernels, network transmissions and continuous plant dynamics for NCS. The simulation result is analyzed, and it is confirmed that this control provides good performance.

• The Journal of the Acoustical Society of Korea
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• v.24 no.3E
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• pp.87-89
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• 2005

The acoustical sources of intake and exhaust systems in fluid machines are often characterized by the source impedance and strength using linear frequency-domain modeling. In the case of the sources which are nonlinear and time-variant, however, the source parameters were sometimes incorrectly obtained. In this paper, the source model and direct measurement technique are modified in order to evaluate the effect due to nonlinear and periodically time-varying source character as well as the linear property of the reflectivity of in-duct fluid machine source. With a priori known kinematical information of the source, the types of nonlinear time-variant terms can be presumed by a simple physical model, in which there is practically no restriction on the form of the model. The concept of source impedance can be extendable by introducing the linear frequency response function for each nonlinear or time-variant input. Extending the conventional method and adapting the reverse MISO technique, it is possible to develop a direct method that can deal with the nonlinear time-variant source parameters. The proposed direct method has a novel feature that there is no restriction on the probability or spectral natures of the excited sound pressure data. The present method is verified by the simulated measurements for simplified fluid machines. It is thought that the proposed method would be useful in predicting the insertion loss or the radiated sound level from intake or exhaust systems.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2005.05a
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• pp.643-650
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• 2005

The object of this study is the development of a measuring framework for supply chain flexibility. Prior to treat supply chain flexibility, time flexibility, quantity flexibility, and cash-flow flexibility for each company are newly suggested. Especially, all developed measures can deal with the monetary point of view through various cost functions. Then weights of time flexibility, quantity flexibility, cash-flow flexibility are determined to find the effect of the level of flexibility in the supply chain. This is based on the relationship between the ratio of profit to revenue and value of three developed flexibility measures. To find the level of weight for each flexibility measure, neural network theory is used. Then the forecasting of the ratio of profit to revenue for all companies in the next period can be available. Therefore, all companies in the supply chain can control their operating processes to improve flexibility.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.37 no.3
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• pp.43-50
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• 2014

In this paper, we deal with a single machine scheduling problems integrating with step deterioration effect and a rate-modifying activity (RMA). The scheduling problem assumes that the machine may have a single RMA and each job has the processing time of a job with deterioration is a step function of the gap between recent RMA and starting time of the job and a deteriorating date that is individual to all jobs. Based on the two scheduling phenomena, we simultaneously determine the schedule of step deteriorating jobs and the position of the RMA to minimize the makespan. To solve the problem, we propose a hybrid typed genetic algorithm compared with conventional GAs.

• Journal of Korean Society of Water and Wastewater
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• v.21 no.6
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• pp.717-726
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• 2007

Fully-grown flocs in a mixing tank of membrane filtration with dead-end membrane are ruptured while passing through a pump and the ruptured flocs are aggregated again in a Membrane-Feed-Pipe (MFP). To look at more details, this study tries to relate the reaggregation to a parameter of mixing intensity in MFP, i.e., G-value. The G-value is a function of Reynolds number, pipe diameter, friction factor and average velocity in MFP. To deal with polydispersity condition, we develop a representative particle size called in this study EDPD (Effective Diameter for Polydispersity condition in Dead-end filtration). The experimental results show that as the G-value increases, the EDPD decreases and also the cake resistance increases. Through comparison between EDPD and cake resistance, these results show that cake resistances are controlled by reaggregation phenomenon in MFP. The effect of detention time in MFP, however, does not affect the reaggregation of the broken flocs as G-values are increased.