• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.1
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• pp.64-69
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• 2011

A novel concept of the gridable desalination plant is to provide an operation management to enable an electricity plant operation cost reduction. Adjusting recovery rate responded to electricity price, an electricity plant operation cost can be saved. To show a suggested approach, the data of 10 [MIGD](Million Imperial Gallons per Day) SWRO testbed are used. The result shows that total cost reduction rate is calculated about 1.6[%] of annual total electric plant operation cost.

• Journal of KIBIM
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• v.5 no.4
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• pp.23-29
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• 2015

The purpose of this study is to provide considerations for developing reverse engineering guidelines for AEC(Architecture, Engineering and Construction). The reverse engineering is a methodology which has the purpose of extracting and recognizing geometries and properties from physical objects such as buildings, facilities, terrain and infrastructure including roads, bridges, and tunnels. To handle them for the purpose of construction management, maintenance, and operation, we should know the exact position, orientation, and dimension of the objects including their properties. As the viewpoint of the information extraction from reverse engineering, it is necessary to derive consideration factors for developing reverse engineering guidelines.

• The Transactions of the Korean Institute of Power Electronics
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• v.24 no.5
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• pp.327-333
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• 2019

This study analyzes the reverse recovery phenomenon of a semi-bridgeless rectifier (SBR) in an inductive power transfer (IPT) system for electric vehicles. Ideally, the reverse recovery phenomenon does not occur in a diode rectifier, however, in practical systems, the reverse recovery phenomenon occurs even when the SBR operates like a diode rectifier due to high operating frequency. Therefore, a practical analysis of operation modes for SBRs is presented in this study, considering the reverse recovery phenomenon, and the requirements for SBR switches are proposed. The analysis results are experimentally verified using a 3.3 [kW] IPT system prototype to which three different types of switches are applied.

• Journal of the Korean Operations Research and Management Science Society
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• v.42 no.1
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• pp.29-41
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• 2017

Korea is expected to become a super-aged society by 2050. Given an aging population and the increasing pressure for the early retirement, a sufficient social safety net for elderly population becomes important. The Korean government introduced public reverse mortgage program in 2007, which is a product for aging seniors and the elderly, The number of reverse mortgage subscribers has also steadily grown. The demand continues to grow, but the reverse mortgage over a long period of time is a highly uncertain and risky product in the position of guarantee or lending institution. Thus, suitable demand prediction of the reverse mortgage subscribers is necessary for stable and sustainable operation. This study uses a Bass diffusion model to forecast the long-term demand for reverse mortgage and provides insight into reverse mortgage by forecasting demand for stability and substantiality of the loan product. We represent the projections of new subscribers on the basis of the data obtained from Korea Housing Finance Corporation. Results show that potential market size of Korean reverse mortgage reaches approximately 760,000-1,160,000 households by 2020. We validate the results by comparing the estimate of the cumulative number of subscribers with that found in literature.

• Journal of Communications and Networks
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• v.2 no.1
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• pp.5-17
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• 2000

cdma2000 offers several enhancement as compared to TIA/EIA-95, although it remains fully compatible with TIA/EIA-95 systems and allows for a smooth migration from one to the other-Major new capability include:1)connectivity to GSM-MAP in addition to IP and IS-41 networks; 2) new layering with new LAC and MAC architectures for improved service multiplexing and QoS management and efficient use of radio resource ;3) new bands and band widths of operation in support of various operator need and constraints, as well as desire for a smooth and progressive migration to cdma 2000; and 4) flexible channel structure in support of multiple services with various QoS and variable transmission rates at up to 1 Mbps per channel and 2 Mbps per user. Given the phenomenal success of wireless services and desire for higher rate wireless services. improved spectrum efficiency was a major design goal in the elaboration of cdma2000. Major capacity enhancing features include; 1) turbo coding for data transmission: 2)fast forward link power control :3) forward link transmit diversity; 4) support of directive antenna transmission techniques; 5) coherent reverse link structure; and 6) enhanced access channel operation. As users increasingly rely on their cell phone at work and at home for voice and data exchange, the stand-by time and operation-time are essential parameters that can influence customer's satisfaction and service utilization. Another major goal of cdma2000 was therefore to enable manufacturers to further optimize power utilization in the terminal. Major battery life enhancing features include; 1) improved reverse link performance (i.e., reduced transmit power per information bit; 2) new common channel structure and operation ;3) quick paging channel operation; 4) reverse link gated transmission ; and 5) new MAC stated for efficient and ubiquitous idle time idle time operation. this article provides additional details on those enhancements. The intent is not to duplicate the detailed cdma2000 radio access network specification, but rather to provide some background on the new features of cdma2000 and on the qualitative improvements as compared to the TIA/EIA-95 based systems. The article is focused on the physical layer structure and associated procedures. It therefore does not cover the MAC, LAC, radio resource management [1], or any other signaling protocols in any detail. We assume some familiarity with the basic CDMA concepts used in TIA/EIA-95.

• ETRI Journal
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• v.38 no.2
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• pp.244-251
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• 2016

In this paper, we investigate the electrical characteristics of two trench-gate-type super-barrier rectifiers (TSBRs) under different p-body implantation conditions (low and high). Also, design considerations for the TSBRs are discussed in this paper. The TSBRs' electrical properties depend strongly on their respective p-body implantation conditions. In the case of the TSBR with a low p-body implantation condition, it exhibits MOSFET-like properties, such as a low forward voltage ($V_F$) drop, high reverse leakage current, and a low peak reverse recovery current owing to a majority carrier operation. However, in the case of the TSBR with a high p-body implantation condition, it exhibits pn junction diode.like properties, such as a high $V_F$, low reverse leakage current, and high peak reverse recovery current owing to a minority carrier operation. As a result, the TSBR with a low p-body implantation condition is capable of operating as a MOSFET, and the TSBR with a high p-body implantation condition is capable of operating as either a pn junction diode or a MOSFET, but not both at the same time.

• Journal of Power Electronics
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• v.16 no.1
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• pp.57-65
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• 2016

Reverse matrix converters, which can step up voltages, are suitable for applications with source voltages that are lower than load voltages, such as generator systems. Reverse matrix converter topologies are advantageous because they do not require additional components to conventional matrix converters. In this paper, a detection method and a post-fault modulation strategy to operate a converter as close as possible to its desired normal operation under the open-switch fault condition in the rectifier stage are proposed. An open-switch fault in the rectifier stage of a reverse matrix converter causes current distortions and voltage ripples in the system. Therefore, fault-tolerant control for open-switch faults is required to improve the reliability of a system. The proposed strategy determines the appropriate switching stages from among the remaining healthy switches of the converter. This is done based on reference currents or voltages. The performance of the proposed strategy is experimentally verified.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.33 no.8
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• pp.289-298
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• 1984

The single phase induction motor is recently requested to meet a broad speed control and smooth forward and reverse operation due to the multifarious usages. This paper deals with two phase operation of a two winding motor by reference current adaptive inverter which can supply the currents to satisfy the balanced oeration into the main and auxiliary winding through the entire operational region. According to the roposed system, the starting, forward and reverse and variable speed control of a two winding motor eliminated the capacitor from the capacitor-run motor is also possible. The formation and its principle of the reference current adaptive inverter and characteristic analysis of the motor fed by this apparatus are described in this paper. Excellent agreement with the measured results and calculated values by computer simulation is obtained.

• Journal of Korean Institute of Industrial Engineers
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• v.30 no.4
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• pp.346-354
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• 2004

Most industrial logistic systems have focused on carrying products from manufacturers or distribution centers to customers. In recent years, they are faced with the problem of integrating reverse flows into their transportation systems. In this paper, we address the vehicle routing problems with mixed delivery and pick-up(VRPMDP). Mixed operation of delivery and pick-up during a vehicle tour requires rearrangement of the goods on board. The VRPMDP considers the reshuffling time of goods at customers, hard time windows, and split operation of delivery and pick-up. We construct a mixed integer mathematical model and propose a new genetic algorithm named GAMP for VRPMDP. Computational experiments on various types of test problems are performed to evaluate GAMP against the modified Dethloff's algorithm. The results show that GAMP reduces the total vehicle operation time by 5.9% on average, but takes about six times longer computation time.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.32 no.4
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• pp.313-319
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• 2019

Induction motors connected with a three-phase AC system may malfunction due to reverse phase or open phase faults. Conventional overcurrent relays and overheating relays are used to prevent such accidents; however, their drawbacks include a low response speed and false operation. Therefore, in this study, a digital relay for the reverse-open phase was designed and fabricated. This relay can detect the reverse phase and open phase faults and send a trigger signal to the control circuit. The proposed relay was developed based on a microcontroller. The detection times of the reverse phase and open phase were verified as 320ms and 80ms, respectively. Compared with conventional relays that only protect the motor from one type of fault, the proposed relay can detect both, reverse phase and open phase faults. In addition, the fault detection, identification criterion, and trigger signal patterns can be modified by programming according to the requirements of users.