• Nuclear Engineering and Technology
• /
• v.51 no.7
• /
• pp.1738-1748
• /
• 2019

Previous research has shown that the inclined condition has an impact on the natural circulation (natural circulation) mode operation of Floating Nuclear Power Plant (FNPP) mounted on the movable marine platform. Due to its compact structure, small volume, strong maneuverability, the Integral Pressurized Water Reactor (IPWR) is adopted as marine reactor in general. The OTSGs of IPWR are symmetrically arranged in the annular region between the reactor vessel and core support barrel in this paper. Therefore, many parallel natural circulation loops are built between the core and the OTSGs primary side when the main pump is stopped. and the inclined condition would lead to discrepancies of the natural circulation drive head among the OTSGs in different locations. In addition, the flow rate and temperature nonuniform distribution of the core caused by inclined condition are coupled with the thermal hydraulics parameters maldistribution caused by OTSG group operating mode on low power operation. By means of the RELAP5 codes were modified by adding module calculating the effect of inclined, heaving and rolling condition, the simulation model of IPWR in inclined condition was built. Using the models developed, the influences on natural circulation operation by inclined angle and OTSG position, the transitions between forced circulation (forced circulation) and natural circulation and the effect on natural circulation operation by different OTSG grouping situations in inclined condition were analyzed. It was observed that a larger inclined angle results the temperature of the core outlet is too high and the OTSG superheat steam is insufficient in natural circulation mode operation. In general, the inclined angle is smaller unless the hull is destroyed seriously or the platform overturn in the ocean. In consequence, the results indicated that the IPWR in the movable marine platform in natural circulation mode operation is safety. Selecting an appropriate average temperature setting value or operating the uplifted OTSG group individually is able to reduce the influence on natural circulation flow of IPWR by inclined condition.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.15 no.1
• /
• pp.38-48
• /
• 2007

this paper analyses how much acceleration and deceleration of urban rail vehicle should be applied and how to choose an operation mode to minimize energy consumption when train runs between stations within the fixed operation time. The decided operation pattern satisfying the minimum energy consumption becomes a target trajectory and a basis for the controller design criteria. To make this goal it grasps the characteristics of urban rail vehicle, realize operation energy model of urban rail vehicle and verity the accuracy of embodied model the Matlab simulation with the same operation result of real route. It searches for operation pattern to minimize operation energy by changing the acceleration and deceleration on the imaginative route and proposes operation pattern minimizing energy consumption by applying real operation data between stations of Seoul Metropolitan Subway Line 6.

• Journal of Power Electronics
• /
• v.15 no.3
• /
• pp.634-643
• /
• 2015

This paper presents a high frequency design approach for improving efficiency over a wide load range in the self-driven phase-shifted full-bridge converters for server power systems. In the proposed approach, a detailed ZVS analysis of the lagging leg switches in both the continuous conduction mode (CCM) and the discontinuous conduction mode (DCM) is presented. The optimum dead time and the determination of the appropriate operation mode are given for high efficiency according to the load conditions. Finally, the optimum operation conditions are defined to achieve a high-efficiency. A laboratory prototype operating at 80 kHz, rated 1 kW (12 V-83.3 A), is built to verify proposed theoretical analysis and evaluations. The experimental results show that the maximum efficiency is achieved as 95% and 83.5% at full load and 5% load conditions, respectively.

• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.55 no.6
• /
• pp.314-324
• /
• 2006

In recent years, having the advantages of being small, low in cost and high in efficiency, Half-wave resonant type, (having only one output diode), is used in ZVS Half-Bridge DC/DC converter. This paper presents the operation mode by multi-resonant factors in the Half-wave type multi-resonant converter with direct Buck chopper circuit operated in discontinuous current mode. To study the characteristics of a multi-resonant operation in steady-state, the characteristic impedances in each mode and safe operation-region(S.O.R) are reported. Computer simulation and experimental data are also riven to verify the theoretical results.

• Proceedings of the KSR Conference
• /
• 2004.06a
• /
• pp.528-533
• /
• 2004

The purpose of this thesis is to construct the autonomous decentralized train traffic management structure using techniques of Autonomous Decentralized System. Currently, a method of train traffic control is making use of CTC(Centralized Traffic Control). Its operation method is divided into the remote mode and the local mode. The classified basis is according to the control authority of install signals in track side. In most cases, a large scale station is operated by the local mode. Because of dispatchers in center can not control the shunting works influence on the main route. In order to solve these problem s, we analyzed a current operation condition and system requirements. Moreover, this thesis is constructing autonomous decentralized train traffic management structure. Finally, this research proposed that interface with CTC and step-by-step construction.

• Proceedings of the KOSOMBE Conference
• /
• v.1992 no.11
• /
• pp.127-129
• /
• 1992

In this paper, we describe about control system for eletro-hydraulic LVAD(Left Ventricular Assist Device) and control algorithm for two operation mode. One is asynchronous operation mode and the other is synchronous operation mode synchronized with natural heart's R pulse. We also present implementation method of software PI algorithm for velocity control of motor used in LVAD system and its response.

• 제어로봇시스템학회:학술대회논문집
• /
• 1998.10a
• /
• pp.210-214
• /
• 1998

Radio-Controlled helicopter has superior movement abilities like as hovering or backward move. So it has been used as a sprinkler of agricultural medicines or an observer of dangerous area such as a volcano, etc. But its operation is not simple because it has many control factors and they interfere with each other. Therefore the helicopter is not controlled by simple theory in the case of automatic operation. Then fuzzy sliding mode control, which has fastness, fineness and robustness, is thought to be suitable to satisfy various requirements of the helicopter operation. In this work, the fuzzy sliding mode control was applied to the flying of RC helicopter, As tile result, it was controlled with good performance.

• Proceedings of the KSR Conference
• /
• 1998.11a
• /
• pp.249-254
• /
• 1998

This paper describes the control methods to cut out the NFB(No Fuse Breaker) of shorted load in the auxiliary power supply, Generally, when the short-circuit occurs in the load of the auxiliary power supply, the auxiliary power supply stops the operation according to the protection sequence. Finally, the other auxiliary power supply stops the operation by the same fault, To resolve this problem, we suggest the control method to trip the NFB of shorted load. That is, when the short circuit occurs, the controller changes control mode from voltage mode to current mode without the operation of output contactor(SIVK) in the auxiliary power supply. The auxiliary power supply provides a large current for the short-circuit load. After some time, the NFB of the short-circuit load is cut off and the auxiliary power supply Provides stable voltage for the loads except for the short-circuit load.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.8 no.2
• /
• pp.77-88
• /
• 1988

This research investigated the effect of COD/N ratio on nitrogen removal, and the use of organics in raw wastewater as a carbon source for denitrification in SBR(Sequencing Batch Reactor) systems. Four laboratory scale reactors were operated in three modes. Only the difference between modes were; Mode I operated in aerated condition during fill while Mode II in anoxic condition and Mode III operated on two fills per cycle in anoxic condition. When COD/N ratio increased, total nitrogen removal efficiencies increased from 8.7 to 57.7 percent in Mode I, from 28.9 to 83.2 percent in Mode II and from 42.7 to 97.8 percent in Mode III, respectively. COD removal efficiencies ranged from 93 to 98 percent throughout the study. SBR operation in Mode III of feeding twice per cycle in anoxic condition was an effective operating method for nitrogen removal and nitrogen concentration in effluent can be estimated using influent COD and nitrogen concentrations.

• 제어로봇시스템학회:학술대회논문집
• /
• 1988.10a
• /
• pp.518-523
• /
• 1988

A Teaching and Operating Expert System (TOES) was designed in order to perform a task effectively which is inaccessible to man. Once an error occurs in the middle of the task operation, the automatic mode is converted into a manual mode. After recovering the error by the manual mode, the manual mode should be converted into the automatic mode. It was necessary to improve the manual mode in order to increase the availability of a man-robot system, a part of the human interface technique. Therefore, the Error Recovery Expert System must be constructed and developed.