• 연구논문집
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• s.27
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• pp.141-151
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• 1997

Recently, the importance of electro-multifunction control valve which is digital control valve is increasing day after day. This is due to the demand of that the current industrial world wants the valve having simpler control circuit and higher operation reliability. It is the PWM controlled high speed electronic valve that satisfies the damands of current industrial world. But, the PWM controlled high speed electronic valve has some non-linearity characteristics like as the delay time of switching and the pressure oscillation phenomenon. These characteristics are an obstacle for the control of high speed & high efficiency in control system. Therefore, in this study, we set the studying purpose on analysis of parameter characteristics in solenoid, and on establishment of optimum design technique in high speed solenoid.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.6
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• pp.859-864
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• 2012

The computer network plays an important role in modern digital controllers within a safety system of a nuclear power plant. For the reliable and realtime data communication between controllers, this paper proposes a modified high-reliable MVB(multi-function vehicle bus) as a main control network for a safety system of a nuclear power plant. The proposed network supports the state-based communication in order to ensure the deterministic communication latency, and very fast network recovery when the bus master fails compare to the standard MVB. This paper also shows the implementation results using a FPGA-based testbed.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.2
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• pp.240-247
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• 2007

This paper presents an implementation of the generator protective relay using Real Time Digital Simulator (RTDS) user defined component (UDC) model designed to facilitate the investigation and evaluation of protective relays. The UDC for RTDS is a convenient model that allows user to develop new component models and run them on the RTDS. The developed model has major features related to the development of six models such as distance, frequency, reverse power, volts per Hz, over voltage, and out-of-step relays. Also, the generator relay models have been used to support and enhance power engineering education at both the undergraduate and graduate levels. The developed model functions are verified and tested by both static test and dynamic test. The simulation results show the capabilities of the developed generator relay using RTDS UDC.

• Journal of Power Electronics
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• v.14 no.3
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• pp.444-457
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• 2014

This paper presents the design and realization of a digital PV simulator with a Push-Pull Forward (PPF) circuit based on the principle of modular hardware and configurable software. A PPF circuit is chosen as the main circuit to restrain the magnetic biasing of the core for a DC-DC converter and to reduce the spike of the turn-off voltage across every switch. Control and I/O interface based on a personal computer (PC) and multifunction data acquisition card, can conveniently achieve the data acquisition and configuration of the control algorithm and interface due to the abundant software resources of computers. In addition, the control program developed in Matlab/Simulink can conveniently construct and adjust both the models and parameters. It can also run in real-time under the external mode of Simulink by loading the modules of the Real-Time Windows Target. The mathematic models of the Push-Pull Forward circuit and the digital PV simulator are established in this paper by the state-space averaging method. The pole-zero cancellation technique is employed and then its controller parameters are systematically designed based on the performance analysis of the root loci of the closed current loop with $k_i$ and $R_L$ as variables. A fuzzy PI controller based on the Takagi-Sugeno fuzzy model is applied to regulate the controller parameters self-adaptively according to the change of $R_L$ and the operating point of the PV simulator to match the controller parameters with $R_L$. The stationary and dynamic performances of the PV simulator are tested by experiments, and the experimental results show that the PV simulator has the merits of a wide effective working range, high steady-state accuracy and good dynamic performances.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.42 no.3
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• pp.391-398
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• 2022

The use rate of M-pass(transportation card for foreigners),developed and sold to provide convenience to foreign tourists, was only 0.0051 % of visitors to Seoul over the past five years. Even this poor sales fell to the 0.024 % level in 2020 due to COVID-19. The cause of the sluggish performance was that the Ministry of land, Transport and Maritime Affairs and the card issuer excluded transportation operating organizations, and problems such as poor public relation, irrationality in pricing, and limitied number of sales locations appeared. In order to solve this problem, the research result showed that business strategies such as the establishment of a digital marketing system, realistic pricing, and the establishment of a mobile sales system that fit the trend, as well as the development of new product that reflect the participation and opinions of all related organizations are necessary. It is expected that this study will not only provide convenience to foreign Seoul tourist in the age of Post Corona, but also help improve the management of subway operating organizations.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.4
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• pp.805-815
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• 1994

The development of automatic production systems has a trend toward Computer Integrated Manufacturing System(CIMS) in recent years. In hardware configuration, CIMS are composed of intelligent CAD/CAM work stations, multifunction CNC machining centers including material handling systems. The DNC systems present the key element of automation hierarchy in a FMS. A DNC system is one which connects a number of numerically-controlled machines to a common memory in a digital computer for part program storage with provision for on-demand distribution of part program data to machines using communication in hierarchical structure of central computer, control computer and cell controller. This paper describes the development of Behind-the-Tape-Reader(BTR) type DNC system using CYBER 180-830 as a central computer and IBM PC-386 cell control computer and NC lathe with FANUC 5T NC controller. In this system, the connection between central computer and cell control computer is done via RS-232C serial interface board, and the connection between cell control computer and FANUC 5T controller is done via parallel interface board. The software consists of two module, central computer communication module for NC program downloading and status uploading, NC machine running module for NC operating.

• Journal of Digital Convergence
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• v.16 no.10
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• pp.235-241
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• 2018

The printout management system should analyze the pattern of existence of personal information (resident number, card number) in the output log and users should be provided with functions such as warning message pop-up, forced printing termination, mailing to administrator, independently logs management. Authentication management can also be performed only by registered users by installing an agent on a user PC, and it should have a restriction function to permit or deny work according to user information. In addition, when printing/copying/scanning using this equipment, it is possible to use document printing and multifunction copier after ID card authentication and ID/PW should be input to device when ID card is not used. In this study, we developed these interfaces with WOWSOFT co., Ltd, a security company that has better technology than the existing printout security methods, to construct the printout management system. Also we designed the interface of basic functions necessary for printout management and contributed to the establishment of printout management system.

• Science of Emotion and Sensibility
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• v.13 no.1
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• pp.1-10
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• 2010

This study is about what process and methodology could make UI designer be able to achieve the interface which considers user's mental model through implementing corporate line-up model, when people design an interface between product of multi-function printer and user. The most important concern of UI designers who are dealing with an interface between product and user is how they can make product system image match user's mental model so that users can utilize products without any confusion and discomfort. If concept model which designers bring up and mental model which users expect and recognize could be of one accord, then users can feel ease of use toward products. The understanding and observation for user behavior and use pattern is prerequisite to develop user-centered interface between product and user. However, UI designers do design interface from their own perspective and assumption in many business areas, and users do not react as designers assumed and intended in many cases or examples. This study is to find inappropriate system images against users' mental model on basic function of multi-function printer, and the relationship of system image and user's mental model is diagramed to build up a hypothesis. The hypothesis from this study is validated through evaluation of domestic and international users. In addition, two suggestions to improve usability problems revealed from user test are proposed. The optimal solution is designed based on the result of user evaluation and consideration of many user environments, and then it is implemented to line-up product. In conclusion, this study considers how UI designers can create system image which is close to user's mental model.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.12
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• pp.6-13
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• 2009

For X-band phased array systems, a power amplifier, a 6-bit phase shifter, a 6-bit digital attenuator, and a SPDT transmit/receive (T/R) switch are fabricated and measured. All circuits are demonstrated by using CMOS 0.18 um technology. The power amplifier has 2-stage differential and cascade structures. It provides 1-dB gain-compressed output power ($P_{1dB}$) of 20 dBm and power-added-efficiency (PAE) of 19 % at 8-11 GHz frequencies. The 6-bit phase shifter utilizes embedded switched filter structure which consists of nMOS transistors as a switch and meandered microstrip lines for desired inductances. It has $360^{\circ}$ phase-control range and $5.6^{\circ}$ phase resolution. At 8-11 GHz frequencies, it has RMS phase and amplitude errors are below $5^{\circ}$ and 0.8 dB, and insertion loss of $-15.7\;{\pm}\;1,1\;dB$. The 6-bit digital attenuator is comprised of embedded switched Pi-and T-type attenuators resistive networks and nMOS switches and employes compensation circuits for low insertion phase variation. It has max. attenuation of 31.5 dB and 0.5 dB amplitude resolution. Its RMS amplitude and phase errors are below 0.4 dB and $2^{\circ}$ at 8-11 GHz frequencies, and insertion loss is $-10.5\;{\pm}\;0.8\;dB$. The SPDT T/R switch has series and shunt transistor pairs on transmit and receive path, and only one inductance to reduce chip area. It shows insertion loss of -1.5 dB, return loss below -15 dB, and isolation about -30 dB. The fabricated chip areas are $1.28\;mm^2$, $1.9mm^2$, $0.34\;mm^2$, $0.02mm^2$, respectively.

• Journal of the Korean Society of Radiology
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• v.5 no.3
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• pp.135-141
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• 2011

If protective performance of apron cannot be good, radiation exposure of an guardian or a patient, a person engaged in radiation related industry cannot rise. Therefore, It will be evaluated protection performance to radiation protection aprons by manufacturers and lead equivalent more than 0.25mm lead equivalent. And, will show in the direction of application to clinic. The new aprons by manufacturers(H, X, I, J company) and lead equivalent(0.50mmPb, 0.35mmPb, 0.25mmPb) measured transmitted dose rate and shielding rate, uniformity under fluoroscopy and general radiography using to fluoroscopy system and digital radiography system, x-ray multifunction meter. The shielding rate measurement results, 0.5mmPb apron was Shielding rate of apron of a I company(fluoroscopy : 97.96%) was the best under six companies, and shielding rate of apron of a J company(fluoroscopy : 96.25%) was worst. 0.35mmPb Apron was Shielding rate of a I company(fluoroscopy : 96.79%) was the best under the three companies, and shielding rate of an H company(fluoroscopy : 95.81%) was the worst. 0.25mmPb Apron was Shielding rate of X company apron(fluoroscopy : 90.908%) was better than H company apron(fluoroscopy : 88.82%) than two companies. The uniformity measurement results, 0.5mmPb Aprons of X company(fluoroscopy : 0.13) and I company(fluoroscopy : 0.19) was the best under the six companies, and J company apron(fluoroscopy : 0.45) was the worst. 0.35mmPb. Along a manufacturer and lead equivalent performance of apron protection is distinguished certainly. Therefore, a patient, guardian or a person engaged in radiation related industry shall enforce experiment of a lot of ways defined or evaluation so that the maximum reduces radiation exposure. Buy the apron that protective performance is good, It will be performed through experiment and evaluation.