• Journal of the Korean Geosynthetics Society
• /
• v.12 no.1
• /
• pp.83-92
• /
• 2013

Backfill material with thermal resistivity which has $50^{\circ}C$-cm/Watt in wet and $100^{\circ}C$-cm/Watt in dry is requested to improve the power transfer capability for dissipation of heat production in underground power cables. In the field test performed by buried cable backfills, the backfill material developed from this study is compared with river sand and weathered soil (native soil) to investigate the effect of heat transfer in various seasons and locations of thermal sensors. As a result, the developed backfill material is faster approaching yielding temperature (critical heat) than that of river sand and weathered soil, and it has good dissipation capacity rather than other materials by keeping moisture content at dry season.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.22 no.3
• /
• pp.380-388
• /
• 2011

In this paper, we developed the X-band 63 watt pulsed SSPA(Solid State Power Amplifier) by using HMIC(Hybrid Microwave Integrated Circuits). The pulsed SSPA consists of power supply and 3-stage amplifier modules : pre-amplifier stage, driver-amplifier stage, final-amplifier stage. The developed pulsed SSPA provides more than 63 watts of output power with a short pulse width and the duty cycle of up to 1.2 % at $70^{\circ}C$. The fabricated module offers great than 37 dB of saturated gain across the operating band. Input and output VSWR is <1.5:1. This module has an average current of 400 mA typical and operates at a +28 $V_{dc}$ supply. The developed SSPA in this paper can apply to pulsed Doppler radar with high speed operation.

• The Transactions of the Korean Institute of Electrical Engineers A
• /
• v.54 no.4
• /
• pp.185-192
• /
• 2005

This paper proposes a DRMS(Distribution Remote Management System) which can enhance highly the economics of automatic metering system and the power quality supplied to the electric customer improving the efficiency of the meter reading, voltage management and load management work by realizing the remote meter reading, the remote voltage management and the remote load management based on the ADWHM(Advanced Digital Watt Hour Meter). The DRMS is designed so that the voltage management and load management work in remote site can be processed by collecting the voltage pattern and current pattern as well as watt hour data from all ADWHMs one time every month regularly or from special ADWHMS several time irregularly, A new on-line voltage and load management strategy based on the ADWHM is designed by analyzing the existing voltage management and load management process. Also, DRMS is designed so that watt-hour data, voltage pattern data, load pattern data and power factor data can be collected selectively according to the selection of user to assist effectively the methodology. Remote management program and database of the DRMS are implemented based on Visual C++, MFC and database library of MS. Also, DRMS is designed so as to communicate with the ADWHM using RS232C-TCP/IP converter and ADSL. The effectiveness of the remote metering function is proven by collecting and analyzing the data after ADWHMs installed in any site. The developed strategy and program also is verified through the simulation of voltage management and load management.

• Journal of IKEEE
• /
• v.26 no.1
• /
• pp.1-9
• /
• 2022

In order to secure the reliability of the power system and to increase the penetration level of distributed energy resources (DERs), requirements such as IEEE 1547 have been revised to strengthen the grid connection standards for DER. This paper proposes a control scheme for smart inverter functions based on IEEE 1547-2018 that satisfy these standards, and introduces a power HILS-based test platform built for verification of smart inverter. Among the smart inverter functions, Volt-var and Frequency-watt allow the curve to be set from the upper level to comply with the interoperability and operation time of enable signals for each function are controlled by references from the upper level. According to the requirement, Volt-var and Frequency-watt are performed via power HILS platform and verified through the measurement results that all of the specified type tests were satisfied.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.27 no.9
• /
• pp.594-599
• /
• 2014

The heat dissipation conditions of high-power 5 watt LEDs-based searchlight modules were optimized with varying LED bar'shape, materials, and ambient temperature. The LED junction temperature was estimated by using Computational Fluid Dynamics simulation. The optimal heat dissipation conditions were found as follows; LED bar' shape: L=80 mm, W=4 mm, t=10 mm, copper material, LED junction temperature of $116.6^{\circ}C$, ambient temperature of $50^{\circ}C$, total mass of 184 g, and shadowing area of $320mm^2$. The difference between the junction temperatures of our fabricated and simulated LEDs-based searchlight modules is about $3^{\circ}C$, which confirms the validity of our thermal simulation results.

• Proceedings of the KIEE Conference
• /
• 2007.10c
• /
• pp.172-174
• /
• 2007

An electronic watt-hour meter with high-precision measurement technology can provide many valuable metering data of a real-time system measurements, such as per-phase voltage, ampere, active power, reactive power, apparent power, power factor, and system frequency. Also many of accumulated metering data such as active energy, reactive energy, apparent energy, and load profile can be gettable from an electronic watt-hour meter[1]. This paper presents an approach of the small-sized AMR (Automatic Meter Reading) that provides customers with a very valuable electrical service. This AMR service transmits lots of a valuable metering data by using ZigBee communication module, so that users resided in their premises can use the information to audit a power quality and improve their electrical conditions by using the PQ monitoring device equipped with ZigBee receiver. This PQ monitoring device shows metering data on LCD and transmits to the PC through an internal network. Also, the device can keep the valuable meter data into a built-in non-volatile memory. The final goal of this paper is to better understand the power quality of electrical systems and offer the power qualify information for the convenience of all power consumers.

• The Journal of Industrial Distribution & Business
• /
• v.9 no.10
• /
• pp.21-37
• /
• 2018

Purpose - This paper explores the contribution lean makes to service levels by addressing lean thinking application in logistics process improvement within a MNC soft drinks manufacturer situated in the United Arab Emirates, and identifies the most significant sources of wastes and their interdependence and highlights key attributes of successful lean implementation. Research design, data, and methodology - This case study examines key logistics employees' perceptions on lean methodology. Results - The results highlight the most significant types of wastes in logistical processes and illustrates ways to eliminate wastes and streamline process flow. The importance of the human role within lean methodology is also identified. Findings suggest that managers should follow both a micro and macro approach when implementing lean practices, as focusing on one waste often leads to ignoring the significance of other wastes. Conclusions - This study highlights the importance of implementing lean at both micro and macro levels and shows how staff involvement increases the efficacy of lean thinking. It offers guidance towards the efficiency of creating value stream mapping processes in situ, which considers different wastes and their interdependence. Managers with limited resources are encouraged to implement lean methodology taking cognizance of these factors.

• Korean Journal of Optics and Photonics
• /
• v.7 no.4
• /
• pp.397-402
• /
• 1996

A compact excimer laser was developed with coaxial type which the one line cross flow fan is only used. At 1 kHz repetitive operation, average power of KrF laser is 56 watt. In this paper, Design parameter and CR characteristic are investigated for attainment of the compact 1 kHz excimer laser. We have obtained overall efficiency of 1.2% with KrF laser gas. At this time, CR and the variation of laser output are 2.97, $\pm$9%. Laser gas volume and active volume are 10 liter, 1.8(H)$\times$1.2(W)$\times$30(L)=64.8 ㎤, respectively.

• Laser Solutions
• /
• v.15 no.2
• /
• pp.15-20
• /
• 2012

A novel joining technology was developed to compensate the camber in polymers. The preheating laser beam circulates on the joining location and the accumulated heat serves to increase the flexibility of neighboring polymers. The temperature rises up to the glass transient temperature of the polymers and continually loading spring force closes the gap of camber. The irradiated laser was 808nm central wavelength and the power varied between 2Watt and 5Watt. The laps were adjusted between 3 and 10 and the optimum process parameters were 3Watt and 5 laps for the specific application. An FEM analysis was introduced to understand the mechanism of joining by the transient temperature distribution on the polymers. Thermocouples experiments were also tried to correlate the numerical analysis results and it showed the trend of heat accumulation in experiments.

• Proceedings of the KIEE Conference
• /
• 2001.07a
• /
• pp.308-310
• /
• 2001

With the development of Computer & Communication Technology, nowadays many people are interested in remote metering, and many vendors are suggesting various remote metering solutions. KEPCO (Korea Electric Power Corporation) adopts some of these to some customers who uses a lot of electric power, also continues researching them. But, currently used electronic watt-hour meters vary in terms of communication protocol and data structure by the vendors. So we have to know each vendor's communication protocol and data structure to construct a remote metering system, or to find problems in it. But that's impossible to know each vendor's protocol and data structure because they are reluctant to tell those to outside the company. To solve these problems and to make a much more cost-effective metering system, KEPCO developed standard communication protocol between meters and PC (or metering server), and defined standard functions and data structure which can be used by everyone easily. Those developments support standard interface for every vendors' meters. And Those will be adopted by KEPCO for a part of a new metering standard for electronic watt-hour meters.