• Current Photovoltaic Research
• /
• v.9 no.3
• /
• pp.106-109
• /
• 2021

In order to perform photovoltaic (PV) operation and management (O&M) efficiently, individual PV module monitoring is becoming more important. In this research, we developed wireless IoT sensor which can monitor individual photovoltaic modules. This IoT sensor can detect the output voltage, current and module temperature of individual modules and provide monitored data by wireless communication. Measured voltage error was 1.23%, and it shows 16.6 dBM, 0.42sec and 7.1 mA for voltage, transmittance output, response time and mean power consumption, respectively. IoT sensors were demonstrated in the test field with real climate environment condition and each of 5 sensors showed precise results of voltage, current and temperature. Also, sensors were compared with commercial power-optimizers and showed result difference within 5%.

• Proceedings of the KIEE Conference
• /
• 2008.07a
• /
• pp.872-873
• /
• 2008

In this paper, a new type of switchgear, electro magnetic force driving actuator (EMFA), is developed and analyzed, applicable to high voltage gas circuit breaker (HGCB). Transient analysis is performed in order to obtain the dynamic characteristics of the EMFA. The distribution of static magnetic flux is obtained using the finite element method (FEM). The governing electric and kinematical equations are solved using the time difference method (TDM). Fabrication and experiments were performed in order to prove the applicability of HGCB for overall class. In comparing the experiment with simulated data, it is confirmed that analysis of the dynamic characteristics of EMFA is appropriate for design.

• Proceedings of the KIEE Conference
• /
• 1989.11a
• /
• pp.211-215
• /
• 1989

This paper presents the thermal analysis of EHV OF cable accessories using FEM. The governing equation about the temperature in the cable accessories is induced by the energy balance equation. Since the temperature distribution is a function of space and time, the weighted residual method is adopted for FEM formulation. The difference approximation is used to treat the time differential term in the element equation. Automatic mesh generation which save time and labor is introduced for the data input process. It will be expected that the following thermal analysis result will be very useful to cable accessories design.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.8 no.7
• /
• pp.1532-1536
• /
• 2004

So far, the quantified elasticity data of textile fabrics has not been present because the measurement method depends on the knowledge of measurement operators. In this paper, the special manufactured measurement equipment using road cell is presented to measure the elasticity coefficient of textile fabrics in real time. The measurement method is based on the voltage differency among textile fabrics. The textiles with strong elasticity are high voltage produced from road cell. The others are low. The presented method can be applied to visualize the textile, sew the cloth, control quality of textile fabrics. Also, these measurement datum are used to B2B electronic trading system.

• Journal of the Korean Chemical Society
• /
• v.65 no.3
• /
• pp.219-229
• /
• 2021

In this study, the new electrochemical cell device using Arduino and sensor was developed, and experiments of changes in voltage at the time of serial and parallel connection of electrochemical cells were conducted to verify the effectiveness of the device. In addition, in order to examine the educational effects of the device, student's inquiry activities of measuring voltage of electrochemical cells and making objects using the voltage difference were conducted. As a result, it was confirmed that the electrochemical device using Arduino and sensor could not only perform automatic measurements and visualize data but also have a possibility to seek various educational effects through easy coding and modification of the device. Based on the results of students' performance, it was found that experimental activities using the device impart a positive effect not only on the understanding of scientific concepts, but also on the development of the practical ability to apply scientific knowledges to the real life. Educational implications are discussed in terms of 'learning by making'.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.22 no.12
• /
• pp.36-46
• /
• 2008

This paper is to study on the Construction of Test circuit and Unification of Experiment Method for high voltage gas-insulated load switch using high power testing system The high power testing system is a equipment to verify electrical and mechanical performance on electrical product. The system consist of short-circuit generator, back-up breaker, making switch, impedance, high voltage transformer, low voltage transformer, measuring and protection system, etc. Using this system, we can test related to high power, for example, short-time current test, active load Current test, magnetizing Current test, capacitive current test, closed loop current test, etc. Standards of high voltage gas-insulated load switch that is in use domestic distribution line are ES 5925-0002, IEC 60265-1, IEC 62271-1 and IEEE C 37.74, etc. In this paper, we standardized on the test procedure, organization of test circuit and analysis of measured data prescribed many difference standards, and applied this test method to 600[MVA] high power testing system. So that we can test the load switch satisfied standards.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2000.10a
• /
• pp.31-35
• /
• 2000

We worried about the technology difference between our company and the advanced company at present motor market and are asked to set up the independent coil insulation system to accumulate insulation technology data. And to export our products at oversee market, we are asked to the evaluation of insulation performance to show our product excellence. In this study, we evaluated the insulation system of our motor, and studied the insulation diagnosis technology systematically to do site diagnosis. We are now accumulating the measured data. And also to reduce the initial insulation failure, we performed the insulation characteristic test and acquired the data to evaluate the initial soundness. We are doing the improvement of the insulation system. And also these data were used to new product development as very useful data, also will be used in the insulation deterioration diagnosis to estimate the remained life time which is very important data for the maintenance management. As the result, we were able to get our product reliability.

• Journal of the Korean Society of Safety
• /
• v.38 no.5
• /
• pp.1-7
• /
• 2023

This study analyzes the operational characteristics of 311 aged and non-aged residual current circuit breakers (RCCBs) in low-voltage consumer contexts. It investigates the influence of external temperature and harmonics based on the rated current multiples. To simulate temperature variations, a convectional oven was used around the circuit breakers. Additionally, the generation of harmonic reference signals and data measurement for overcurrent experiments were conducted using NI SCXI, myDAQ, and LabVIEW. An observation revealed that as the ambient temperature increased, the operating time of RCCBs decreased in the time delay region. This was attributed to the faster response or bending of the bimetal, which is the tripping element. However, aged RCCBs encountered challenges with tripping outside the protective curve. The operating time of the circuit breakers exhibited an acceleration influenced by the order and content of harmonic currents, potentially leading to malfunctions. Aged RCCBs demonstrated faster operating times than their non-aged counterparts. However, the difference in operating time varied based on the manufacturer's and operating environment of the RCCBs. Frequent malfunctions of RCCBs can result in power outages. In cases where these circuit breakers fail to operate, they can lead to secondary damages, including electrical fires and shocks. Consequently, it is imperative to consider the operating environment of RCCBs and provide appropriate replacement cycles to mitigate these risks.

• The KIPS Transactions:PartA
• /
• v.10A no.3
• /
• pp.247-254
• /
• 2003

This paper describes a Delay Locked Loop (DLL) with low supply voltage and wide lock range for Synchronous DRAM which employs Double Data Rate (DDR) technique for faster data transmission. To obtain high resolution and fast lock-on time, a new type of phase detector is designed. The new counter and lock indicator structure are suggested based on the Dual-clock dual-data Flip Flop (DCDD FF). The DCDD FF reduces the size of counter and lock indicator by about 70%. The delay line is composed of coarse and fine units. By the use of fast phase detector, the coarse delay line can detect minute phase difference of 0.2 nsec and below. Aided further by the new type of 3-step vernier fine delay line, this DLL circuit achieves unprecedented timing resolution of 25psec. This DLL spans wide locking range from 500MHz to 500MHz and generates high-speed clocks with fast lock-on time of less than 5 clocks. When designed using 0.25 um CMOS technology with 1.8V supply voltage, the circuit consumes 32mA at 500MHz locked condition. This circuit can be also used for other applications as well, such as synchronization of high frequency communication systems.

• Proceedings of the KIEE Conference
• /
• 2000.07b
• /
• pp.922-924
• /
• 2000

We worried about the technology difference between our company and the advanced companies at present motor market. Thus we started independently to develop the technology of motor coil insulation system and to accumulate insulation technology data. When we export the electric machines to oversee market. we are asked to set up the insulation system to show our product excellence. We first evaluate the insulation system of our motors to realize higher reliability of high voltage insulation system. Therefore we are possible to do the insulation diagnosis in real site and have accumulated the data related in insulation diagnosis. Thus we have improved the our insulation system. And also these data were used to new product development as very useful data. also will be used the insulation deterioration diagnosis to estimate the remained life time which is very important data for the maintenance management. As the result. we are able to get the our product reliability.