• Journal of Energy Engineering
• /
• v.23 no.1
• /
• pp.90-94
• /
• 2014

Environmental qualification (EQ) for safety-related equipment is required to ensure that those equipment will perform their required function even under the harsh environment conditions arising from design basis accident in the nuclear power plant. As a part of EQ program, the room temperature analysis in case of a loss of Heating, Ventilation, and Air Conditioning(HVAC) system was carried out to ensure the operability of the safety-related equipment of a nuclear power plant randomly chosen among the Korean nuclear power plants. In this paper, this analysis was performed in the conservative perspective using GOTHIC code. The room temperature analysis includes selecting the rooms in which the safety related equipment are located but not supported by safety related HVAC and determining the temperature of the selected rooms. Target rooms for the analysis consist of W229/W237 (Aux. feedwater pump room), W232 (Aux. feedwater tank room) and W230 (Equipment passageway). The results showed the temperature range from $43^{\circ}C$ to $83^{\circ}C$, in 72 hours after a loss of HVAC. Those values are far below of generic EQ temperature($171^{\circ}C$). Therefore, it is satisfied with EQ requirement of temperature limits on safety related equipment.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 1991.04a
• /
• pp.95-98
• /
• 1991

회전 기기의 이상으로 인하여 발생하는 진동은 축 회전속도의 고주파 성분 (super-harmonic)이나 또는 분수조파 성분(sub-harmonic)으로 나타나는 경 우가 대부분이기 때문에 회전기기의 진동을 주파수 영역에서 해석함에 있어 파워 스펙트럼의 주파수 축을 Hz로 나타내기보다는 축 회전속도의 order로 써 나타내는 것이 매우 유용하다. 스펙트럼을 order로써 나타내기 위해서는 샘플링 시간을 축 회전속도와 동기(synchronization)시켜야 하는데 이 방법으 로는 회전축에 엔코더(encorder)를 부착하여 엔코더에서 발생하는 펄스 신호 를 이용하여 샘플링하는 방법과 order tracking 필터를 이용하는 방법이 있 다. 그러나 전자의 방법은 원하는 회전축마다 엔코더를 부착하여야 하며 경 우에 따라서는 엔코더를 부착하기가 어려운 경우도 있으며, 회전기기의 운전 개시나 종료시처럼 회전속도가 급격히 변화하는 경우에는 낮은 주파수에서 중첩(aliasig)에 의한 오차가 수반될 수도 있다. 후자의 방법은 order tracking 필터 이외에도 여러 부수장비가 필요하며 기준 주파수(즉 회전속 도)가 급격히 변화하는 경우 PLL(phase locked loop)에서 tracking 오차가 발생된다. 최근에 발표된 논문에서 일정한 시간간격으로 샘플링한 데이터들 로부터 신호를 재합성하여 회전축의 속도와 동기가 되도록 재 샘플링함으로 서 스펙트럼의 주파수를 회전속도의 order로써 나타내는 방법을 제시하였다. 그러나 위 논문에서는 신호의 재합성에 필요한 재합성 필터(reconstruction filter)의 설계 방법에 대하여 구체적인 언급이 없이 다만 결과만을 논하였다. 따라서 본 논문에서는 재합성 필터의 설계 방법에 대하여 구체적인 방법을 제시하고 또한 동기화 샘플링의 장점 및 고려 사항에 대하여 고찰하였다. 고려한 능동 소음제어 에 대해 연구하였다. 경량화 추세에 따라 지반이나 케이싱이 경량이거나 유연하여 회전축과 동적으로 연성된 경우 회전축-베어링-지반으로 이루어진 2중구조의 회전축 계 동특성을 해석할 수 있는 프로그램을 개발하므로서 회전 기계류의 진동 전반에 걸친 문제점에 대한 그 원인과 현상을 명확히 분석하여 국내의 전기 계류의 보다 신뢰성있는 설계 및 제작자료를 확보하는데 기여할 수 있게 하 였다.존의 small molecular Gd-chelate에 비해 매우 큼을 알 수 있었다. MnPC는 간세포에 흡수된 후 담도계로 배출되는 간특이성 조영제임을 확인하였다. 장비 내에서 반복 시행한 평균값의 차이는 대체적으로 유의한 차이가 없었으나, 다른 장비에서 반복 시행한 장비간의 사이에는 유의한 차이가 있는 경우가 더 많았다. 따라서 , MRS 검사를 소뇌나 뇌교의 어떤 절환에 적용하기 전에 각 장비 마다 정상 기준치를 반드시 얻은 후에 이상여부를 판 정하는 것이 필수적이라고 생각된다.EX> 이상이 적절한 진단기준으로 생각되었다. $0.4{\;}\textrm{cm}^3$ 이상의 좌우 부피차를 보이는 모든 증례에서 육안적으로도 해마위축이 뚜렷이 나타났다. 결론 : MR영상을 이용한 해마의 부피측정은 해마경화증 환자의 진단에 있어 육안적인 MR 진단이 어려운 제한된 경우에만 실제적 도움을 줄 수 있는 보조적인 방법으로 생각된다.ofile whereas relaxivity at high field is not affected by τS. On the other hand, the change in τV does not affect low field profile but strongly in fluences on both inflection fie이 and the maximum relaxivity value. The re

• Journal of the Korean Electrochemical Society
• /
• v.15 no.3
• /
• pp.115-123
• /
• 2012

As the market of lithium secondary batteries moves from mobile IT devices to large-format electric vehicles or energy storage systems, the strengthened battery specifications such as long-term reliability longer than 10 years, pack-level safety and tough competitive price have been required. Moreover, even though high power properties should also be achieved for hybrid electric vehicles, it is not easy to measure accurate power values at various conditions. Because it is difficult to choose a proper measurement method and its experimental condition is more complex comparing to capacity measurement. In addition, the power values are very sensitive to power duration time, state-of-charge (SOC) of cells, cut-off voltages, and temperatures, whereas capacity values are not. In this paper, we introduce three kinds of power measurement methods, hybrid pulse power characterization (HPPC) suggested by US FreedomCar, so-called J-pulse by Japan electric vehicle association standards (JEVS) and constant power measurement, respectively. Moreover, with pouch-type unit cells for HEV, experimental power data are discussed in order to compare each power measurement.

• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.48 no.2
• /
• pp.75-82
• /
• 1999

A compensation method of the motor parameters using zero sequence third harmonic voltage is presented for the speed sensorless vector control of the induction motor considering saturation of the flux. Generally, the air-gap flux of the saturated induction motor contains the space harmonic components rotating with the synchronous frequency of the motor. Because the EMF of the saturated induction motor contains the zero sequence harmonic voltages at the neutral point of the motor, those harmonic voltages can be used as a saturation index. In this work, the rotor flux observer is firstly designed for the speed sensorless vector control of induction motor. And a novel measurement method of the space harmonic voltage and a compensation method of th LPF(Low Pass Filter) are proposed. For compensating the non-linear variations of the magnetizing inductance depending on the saturation level of the motor, the dominant third harmonic voltage of the motor is used as a saturation function of the air-gap flux. And the variation of the stator resistance owing to the motor temperature can also be measured with the phase angle between the impressed voltage vector and the zero sequence voltage. The validity of the proposed parameter compensation scheme in the speed sensorless vector control using rotor flux observer is verified by the result of the simulations and the experiments.

• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.50 no.5
• /
• pp.229-237
• /
• 2001

Until recent years, most of the researches for motor drives focus on the high performance drive of the three phase induction motor, and that of the single phase induction motor(SPIM) is out of interest. The SPIM is widely used at low power level because it has the simple construction and economic advantage. In general such machine has both main winding and auxiliary winding. Conventionally, these winding are fed by only one single phase source, and the speed of the motor is not controlled. The SPIM with an auxiliary winding can be treated as an asymmetrical two phase machine. In this paper the space vector Equivalent circuit of SPIM is derived. For vector control of the SPIM the stator current must be decoupled into the flux producing component and the torque producing component. To accomplish decoupling control, the conventional method requires complex calculation and large computation time. We proposed the equivalent circuit referred to the rotor side, in this case only the stator resistances in the direct axis and the quadrature axis are different each other and the other parameters are represented to be equal. Thus the decoupling of the stator current is similar to that of the three phase induction motor. In this paper, the novel vector control system of the single phase induction motor is proposed. To verify the feasibility of this scheme, simulation and experimentation are carried out. The results prove the excellent characteristics for the dynamic response, which confirms the validity of the proposed system.

• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.51 no.11
• /
• pp.601-611
• /
• 2002

As resent trends in structural construction have been to build taller and larger structures than any time in the past, they have had high flexibility and low damping that can cause large vibration response under severe environmental loading such as earthquakes, winds, and mechanical excitations. The damper with mass and sqring is one aproach to safeguarding the structure against excessive vibrations. In this paper, a large capacity hybrid-type linear motor damper(LMD) was designed and fabricated for the application to the vibration control of a large building structure model. It has been designed to be able to move the damper mass, 1,500 kg up to ${\pm}250mm$ strokes at the first mode natural frequency of the building structure model, ${\pm}0.51Hz$. Linear motor is consisted of the fixed coil and the movable NdFeB permanent magnets field part. The PM field part composed magnet modules and iron yoke, is the damper mass itself, 1500kg. LMD therefore has a simplified structure and requires a few elements in the driving system, being compared with a rotary motor damper and a hydraulic damper. However, the manufacture of large PM linear actuator is difficult because of the limit of PM size and the attraction and repulsion at the assembly of PM. Therefore, large damper system is manufactured and tested for dynamic characteristics and frequency response.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.65 no.5
• /
• pp.730-737
• /
• 2016

Electric utilities may face new threats with increase in electric vehicles (EVs) in the personal automobile market. The peak demand will increase which may stress the distribution network equipment. The focus of this paper is on an adaptive control of smart household appliances by using an intelligent load management system (ILMS). The main objectives are to accomplish consumer needs and prevent overloading of power grid. The stress from the network is released by limiting the peak demand of a house when it exceeds a certain point. In the proposed strategy, for each smart appliance, the customers will set its order/rank according to their own preferences and then system will control the household loads intelligently for consumer reliability. The load order can be changed at any time by the customer. The difference between the set and actual value for each load's specific parameter will help the utility to estimate the acceptance of this intelligent load management system by the customers.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.16 no.6
• /
• pp.1223-1230
• /
• 2021

Recently, energy resource management is a major concern around the world. Energy management activities minimize environmental impacts of the energy production. This paper presents design and prototyping of a home electric energy monitoring system that provides residential consumers with real time information about their electricity use. The developed system is composed of an in-house sensing system and a server system. The in-home sensing system is a set of wireless smart plug which have an AC power socket, a relay to switch the socket ON/OFF, a CT sensor to sense current of load appliance and a Kmote. The Kmote is a wireless communication interface based on TinyOS. Each sensing node sends its detection signal to a home gateway via wireless link. The home gateway stores the received signals into a remote database. The server system is composed of a database server and a web server, which provides web-based monitoring system to residential consumers. We analyzed and presented energy consumption data from electrical appliances for 3 months in home. The experimental results show the promising possibilities to estimate the energy consumption patterns and the current status.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.17 no.4
• /
• pp.617-624
• /
• 2022

The small electric vehicles equipped with V2X(vehicle to everything) systems may provide more information and function to the existing navigation system of the vehicle. The key components of V2X technology include V2V (vehicle to vehicle), V2N(vehicle to network) and V2I (vehicle to infrastructure). This study is to design and implementation of VI type E-PTO which is interfaced with external equipments, the work designs the components of E-PTO such as DC/DC converter, DC/AC converter, battery bidirectional charging system etc. Also, it implements the devices and control systems for driving. The test results of VI type E-PTO components showed allowable 10% requirements of transient voltage variation rate and recovery time within 100ms for start/stop and normal operation.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
• /
• v.12 no.3
• /
• pp.282-289
• /
• 2019

Reflective and solar LED road studs are being used as a way of securing visibility for road environments. Road markers have various advantages and disadvantages in terms of versatility, efficiency, simplicity and visibility as individual products of reflective type and solar LED. However, in addition to the above, it is possible to prevent secondary accident after accident, It has a common drawback that it is difficult to have. In this paper, we propose a road stud system incorporating a wireless control function using RF - based communication with existing solar LED road studs and a system for controlling them. The proposed system is called the smart road stud system and it can control the equipment through the central control unit and the relay unit connected to the central control room by incorporating the RF communication function in the existing solar LED road stud. In addition, since it is possible to control the lighting method, color, etc. according to the road condition, it is possible to provide the driver with the state of the road to perform the function for preventing the second accident after the accident. It also adds features that minimize the ongoing power consumption of LED and RF communications. In order to verify the validity of the proposed system, prototypes were produced and it was confirmed that it is possible to act as a university for prevention of accident after accident by linking with other traffic system besides accident prevention function by securing existing visibility.