• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.26 no.4
• /
• pp.28-34
• /
• 2012

Installing surge protection devices for a low-voltage system is important to ensure the survival of electric or electronic devices and systems. If surge protection devices (SPD) are installed without consideration of the concept of lightning protection zones, the equipment to be protected might be damaged despite the correct energy coordination of SPDs. This damage is induced by the reflection phenomena on the cable connecting an external SPD and the load protected. These reflection phenomena depend on the characteristics of the output of the external SPD, the input of the loads, and the cables between the load and the external SPD. Therefore, the SPD has an effective protection distance under the condition of the specific load and the specific voltage protection level of SPD. In this paper, PSCAD/EMTDC software is used to simulate the residual voltage characteristics of SPD Entering the low-voltage device. And by applying a certain voltage level, the effective protection distances of SPD were analyzed according to the each load and length of connecting cable, and the effectiveness of SPD were verified.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.24 no.10
• /
• pp.58-66
• /
• 2010

This paper shows an implementation and management result of wireless networks based security light control system, which performs a great role in protection of pedestrians and prevention of crime. Conventional security light units have severe limits in confirmation and inspection of security light unit failure, like wilful damage by someone or failure by influence of other equipment or failure by spontaneous heat-increase, and so on. In addition, local government offices are responsible for maintenance of security light units and as a matter of fact, most of civil complaints are about security light units. It is an obvious that the existing security light maintenance system reaches the limit and the security light maintenance problem is a difficulty of local government. Therefore, efficient security light control system is needed, which enables central control and intelligent maintenance. Moreover, the system has to be easy to control and has to be stable. In this study, wireless sensor network based security light control system is implemented, which is independent of programming language and platform, and which is simple to control and extend the system. The proven protocols, HTTP and SOAP, are utilized in order to improve the system reliability. This paper shows the excellence of our proposed system by implementing and operating it in real environment.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.65 no.5
• /
• pp.711-717
• /
• 2016

Recently, fuel cell generation system with high energy efficiency and low CO2 emission is energetically interconnected with distribution power system. Especially, MCFC(molten carbonate fuel cell) operating at high temperature conditions is commercialized and installed as a form of large scale power generation system. However, it is reported that power system disturbances such as harmonic distortion, surge phenomenon, unbalance current, EMI(Electromagnetic Interference), EMC (Electromagnetic Compatibility) and so on, have caused several problems including malfunction of protection device and damage of control devices in the large scale FCGS(Fuel Cell Generation System). Under these circumstances, this paper proposes countermeasure algorithms to prevent power system disturbances based on the modelling of PSCAD/EMTDC and P-SIM software. From the simulation results, it is confirmed that proposed algorithms are useful method for the stable operation of a large scale FCGS.

• Journal of the Korea Society of Computer and Information
• /
• v.13 no.6
• /
• pp.155-162
• /
• 2008

The quality of the fruits is measured by a lot of parameters. The grader of the fruits to measure the size of them is using the rotation drum method. Therefore when we classify the size of the fruits, they will be damaged. Also the optical grader used for estimating the degree of the saccharinity will incur high cost for it. In the proposed system, to select the characteristics of the fruits, three cameras are used. Because the information such as the volume and the degree of the maturity is used to classify the fruits, the degree of the saccharinity can't be estimated itself, but the information such as the color and the damage of the fruits can be estimated. Therefore, because we don't need the digital image with high resolution, we can develop the grader system of the fruit with low cost. To evaluate the performance of the proposed system, we compared it with the sight estimation and then we classified the sample. The result shows the accuracy of 96.7%.

• The Korean Journal of Emergency Medical Services
• /
• v.13 no.1
• /
• pp.19-33
• /
• 2009

Purpose : To check the legal relation between rescue team and patient as well as legal responsibility for patient's damage intentionally or erroneously caused by rescue member, a public official, in the performance of relevant job ; to prevent legal dispute over rescue team and to present program for fair settlement of dispute and equitable and feasible burden of damage. Method : First, the legal principle of Civil Law, Criminal Law and Administrative Law related to the theme of this research will be investigated around research by literature. Second, the case of dispute related to rescue team will be introduced. Result: 1. If 119 rescue members as a public official intentionally or erroneously cause damage to patient in the performance of job, they shall bear civil, criminal and administrative responsibility. They shall bear civil responsibility for indemnity for damage due to default or tort. The typical criminal responsibility includes accidental homicide arising out of duty, preparing falsified official document, dereliction of duty, etc. In the administrative side, the state is responsible for indemnity for peculiar status of the rescue member, public official. 2. Though raising civil petition or legal dispute over unsatisfactory rescue service may be reasonable to guarantee the right of nation, such action may cause stress to rescue member as well as may lead to mental shrinking and defensive attitude only to take the basic first aid treatment which has low possibility of mistake instead of active first aid treatment so as to avoid legal responsibility. 3. The program that may prevent legal dispute over 119 rescue team includes expansion of manpower specialized in first aid treatment, enhancement of education on legal environment, development and application of standard job guideline, formation of mutual trust with patient, detailed explanation, preparing and keeping minute record, improvement of the rescue members' ability of first aid treatment and development of medical instruction mode. Conclusion : The best policy is to prevent legal dispute. If it is impossible to basically exclude the possibility of dispute, however, we need to make effort to minimize the occurrence, settle fairly and divide damage equitably and feasibly. To improve the preventible death rate of our first aid system to the level of advanced country, 119 rescue team which is in charge of the stage before hospital needs to positively enforce special first aid by improving the qualitative level of rescue service and to strive to prevent legal dispute that may occur in the process.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.14 no.4
• /
• pp.160-166
• /
• 2015

Ultrasonic machining (USM) has been considered a new, cutting-edge technology that presents no heating or electrochemical effects, with low surface damage and small residual stresses on brittle workpieces. However, nowadays, many researchers are paying careful attention to the disadvantages of USM, such as low productivity and tool wear. On the other hand, in this study, a high-performance rotary ultrasonic drilling (RUD) spindle is designed and assembled. In this system, the core technology is the design of an ultrasonic vibration horn for the spindle using finite element analysis (FEA). The maximum spindle speed of RUM is 9,600 rpm, and the highest harmonic displacement is $5.4{\mu}m$ noted at the frequency of 40 kHz. Through various drilling experiments on glass workpieces using a CVD diamond-coated drill, the cutting force and cracking of the hole entrance and exit side in the glass have been greatly reduced by this system.

• Journal of Power System Engineering
• /
• v.12 no.4
• /
• pp.57-63
• /
• 2008

The last stage blade of the low pressure steam turbine remarkably affects turbine plant performance and availability Turbine manufacturers are continuously developing the low pressure last stage blades using the latest technology in order to achieve higher reliability and improved efficiency. They tend to lengthen the last stage blade and apply shrouds at the blades to enhance turbine efficiency. The long blades increase the blade tip circumferential speed and water droplet erosion at shroud is anticipated. Parts of integral shrouds of the last stage 40 inch blades were cracked and liberated recently in a combined cycle power plant. In order to analyze the root cause of the last stage blades shroud cracks, we investigated operational history, heat balance diagram, damaged blades shape, fractured surface of damaged blades, microstructure examination and design data, etc. Root causes were analyzed as the improper material and design of the blade. Notches induced by erosion and blade shroud were failed eventually by high cycle fatigue. This paper describes the root cause analysis and countermeasures for the steam turbine last stage blade shroud cracks of the combined cycle power plant.

• Journal of Sensor Science and Technology
• /
• v.25 no.1
• /
• pp.8-12
• /
• 2016

A planar, light-weight, and low-cost notch filter structure is required for the KSTAR ECEI (Electron Cyclotron Emission Imaging) system to protect the mixer arrays from spurious plasma heating power. Without protection, this heating power can significantly degrade or damage the performance of the mixer array. To protect mixer arrays, a frequency selective surface (FSS) structure is the suitable choice as a notch filter to reject the spurious heating power. The FSS notch filter should be located between the lenses of the ECEI system. This paper presents a 170 GHz FSS notch filter for the KSTAR ECEI sensor application. The design of such an FSS notch filter is based on the single-sided square loop geometry, because that makes it relatively insensitive to the incident angle of incoming wave. The FSS notch filter exhibits high notch rejection with low pass-band insertion loss over a wide range of incident angles. This paper also reviews the simulated and measured results. The proposed FSS notch filter might be implemented in other millimeter-wave plasma devices.

• Proceedings of the KIPE Conference
• /
• 2014.07a
• /
• pp.431-432
• /
• 2014

Recently, the demand of LED(light-emitting diode) lighting is gradually enlarged by governmental saveenergy policy, which the LED lighting has been established compulsorily in new buildings, public institutions, and residential installations etc.. The LED lighting is driven by SMPS (switching mode power supply). The SMPS requires high efficiency because the SMPS changes a commercial ac power source to low voltage dc power source. Harmonic components that occur in the conversion process of SMPS decrease system power factor and deal great damage in electric power system. To improve such problems, this paper proposes a SMPS of high efficiency. The switching devices in the proposed SMPS are operated by soft switching technique using a new quasi-resonant circuit. The input ac current waveform in the proposed SMPS becomes a quasi-sinusoidal waveform proportional to the magnitude of input ac voltage under constant switching frequency. As a result, the proposed SMPS obtains low switching power loss and high efficiency, and its input power factor is nearly in unity.

• The Korean Journal of Emergency Medical Services
• /
• v.9 no.1
• /
• pp.111-119
• /
• 2005

Glucose is the most importantenergy source in the central nervous system. Because the central nervous system cannot synthesize or store glucose. low blood glucose even for a short period results in no functionally normal activity of the brain. In addition, continuous low blood glucosecan cause irreversible brain damage and brain death. Therefore, the current status of emergency care by first aid staffs during transfer of patients with hypoglycemia has been investigated in this study, 114 patients who have visited the hospital using 119 Emergency Medical Service from January 1, 2004 till December, 2004 and shown blood glucose of 2.8 mmol/L and less on arrival have been involved. In case of nurses, assistant nurses, first aid staffs receiving first aid training and second-class emergency medical technicians(EMTs), they provided basic life support (BLS). In case of first-class EMTs, they measured blood sugar and then they orally administered glucose to conscious patients or provided simple first aids and prompt transfer for unconscious patients. As a result of analysis, it is suggested that first aid retraining is required.