• Proceedings of the KIEE Conference
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• 1999.07c
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• pp.1276-1278
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• 1999

This paper proposed the optimal operational scheduling of cogeneration system for paper mill connected with several auxiliary devices. Auxiliary devices that include auxiliary boiler, waste boiler and sludge incinerator operate with multi-cogeneration system. Especially environment element was considered in objective function to solve environment problem. Electricity can be purchased through power system from utility. The proposed operational strategy on cogeneration system for paper mill to increase energy efficiency can be applied to the similar cogeneration system in industrial field.

• Journal of applied mathematics & informatics
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• v.8 no.3
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• pp.975-987
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• 2001

We treat the problem of variance estimation for the estimator of population total, which is derived from the calibration estimation procedure corresponding to the levels of auxiliary information under nonresponse situation. We develop the calibrated variance estimation procedure using the fact that the population total and variance as well as the sample total and variance of the auxiliary variable are known. We show that the proposed variance estimation procedure improves the $Lundst\ddot{o}rm$ and $S\ddot{a}rndal's$ (1999) procedure with respect to the variance and nonresponse bias reduction through the simulation study.

• Communications for Statistical Applications and Methods
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• v.16 no.5
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• pp.821-840
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• 2009

This article addresses the problem of estimating a family of general population parameter ${\theta}_{({\alpha},{\beta})}$ using auxiliary information in the presence of measurement errors. The general results are then applied to estimate the coefficient of variation $C_Y$ of the study variable Y using the knowledge of the error variance ${\sigma}^2{_U}$ associated with the study variable Y, Based on large sample approximation, the optimal conditions are obtained and the situations are identified under which the proposed class of estimators would be better than conventional estimator. Application of the main result to bivariate normal population is illustrated.

• Journal of Power System Engineering
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• v.7 no.3
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• pp.54-60
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• 2003

In general, the swing motion of the crane is controlled and suppressed by activating the trolley motion. In this paper, we suggest a new type of anti-sway control system of the crane. In the proposed control system, a small auxiliary mass(moving-mass) is installed on the spreader and the swing motion is controlled by moving the auxiliary mass. The actuator reaction against the auxiliary mass applies inertial control forces to the container to reduce the swing motion in the desired manner. In this paper, we apply the $H_{\infty}$ based control technique to the anti-sway control system design problem. And the experimental result shows that the proposed control system is shown to be useful and robust to disturbances like winds and initial sway motion.

• Communications for Statistical Applications and Methods
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• v.9 no.2
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• pp.479-489
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• 2002

The case which applies two-phase sampling to stratification and nonresponse problem, it is a poweful and effective technique. In this paper we study the calibration estimator and its variance estimator for the population total using two-phase sampling method according to the of auxiliary information for population and sample having strong correlation with an interested variable in unit nonresponse situation. The auxiliary information that available both at first-phase and second-phase sampling can be used to improve weights by the calibration procedure. A weight which corresponds to the product of sampling weights and response probability is calculated at each phase of sampling.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.4
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• pp.86-92
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• 2008

This paper is to investigate the behavior of linear static structure stress, the fatigue and experimental shock fracture far engine base in the Auxiliary Power Unit to resolve its restricted electrical power problem. The shock fracture test was experimentally made under MIL standard criteria. The numerical results by finite element method had a good agreement with those from the shock test. The design data of predicting the fracture at the initial crack and the damage behavior of structure with shock and vibration load in the battle field can be obtained from shock test. In the functional shock test, the crack at the side parts of the engine base was found at peak acceleration of 40g.

• Journal of Power System Engineering
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• v.8 no.1
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• pp.55-61
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• 2004

In general, the swing motion of the crane is controlled and suppressed by activating the trolley motion. In this paper, we suggest a new type of anti-sway control system of the crane. In the proposed control system, a small auxiliary mass(moving-mass) is installed on the spreader and the swing motion is controlled by moving the auxiliary mass. The actuator reaction against the auxiliary mass applies inertial control forces to the container in order to reduce the swing motion in the desired manner. In this paper, we apply the $H_{\infty}$ based control technique to the anti-sway control system design problem. And the experimental result shows that the proposed control system is useful and robust to disturbances like winds and initial sway motion.

• Journal of Ocean Engineering and Technology
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• v.14 no.4
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• pp.43-48
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• 2000

In this paper, an actively controlled anti-rolling system is considered to reduce the rolling motion of the ship. In this control system, a small auxiliary mass is installed on the upper area of the ship, and actuator us connected between the auxiliary mass and a ship. The actuator reacts against the auxiliary mass, applying inertial control forces to the ship to reduce the rolling motion in the desired manner. In this paper, we apply the PID controller to design the anti-rolling control system for the controlled ship. And the experimental result shows that the desirable control performance is achieved.

• Proceedings of the KIEE Conference
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• 2005.04a
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• pp.172-175
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• 2005

Recently international regulations governing the amount of harmonic currents(e.g IEC 61000-3-2) became mandatory and active Power factor correction (PFC) pre-regulator circuit became inevitable for the AC/DC converters. Among these topologies, the boost topology represents an optimum solution for a PFC pre-regulation in a high power application. This paper propose improved ZVT(Zero Voltage Transition) AC/DC PFC Boost using the average current control employing a soft-switching technique of the auxiliary switch with a minimum number of components. The conventional ZVT PFC Boost Converter has a disadvantage that the auxiliary switch turns off hard, which influences the overall efficiency and the EMI problem. In this paper, an improved ZVT PFC Boost converter using active snubber is proposed to minimize the switching loss of the auxiliary. The prototype of 100kHz, 640W system was implemented to show the improved performance.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.12
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• pp.1810-1817
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• 2015

The railway vehicle has an auxiliary power unit for supplying power to the associated electronic control devices and passenger service unit. Typically, input voltage from the catenary for rolling stock is highly fluctuating according to the substation capacity, vehicle propulsion and regeneration. Especially, the frost and freezing on contact wire in winter can cause a blackout inside vehicle, and also brings about electronic components damaging and the system down. To prevent this problem, a large filter and capacitor is used. But this is not a perfect solution, because it is increasing weight of the unit. In this paper, a new algorithm is proposed to suppress the disturbance without adding devices. Simulation and experimental results show that the proposed algorithm has performance to suppress the disturbance at the sudden input voltage variations.