• Transactions of the Korean Society of Mechanical Engineers
• /
• v.10 no.6
• /
• pp.923-928
• /
• 1986

A set of measurements has been made for the thermal conductivity of the pure paraffin in liquid and solid phases and for the effective thermal conductivity of the paraffin with metal scrap with the aid of the heat flux meter. Ther thermopile-type heat flux meter has been designed by steady state method and the functional relation between the temperature difference of both sides and heat flux has been obtained. The measured values of thermal conductivity are compared with the existing data for the pure paraffin and with the predicated values from the suggested model in which only one empirical constant is contained. The comparison within ten percent of the volume fraction of the metal scrap in the paraffin is satisfactory.

• Proceedings of the KIEE Conference
• /
• 1997.07a
• /
• pp.77-79
• /
• 1997

An induction watthour meter was designed for use on circuits in which the voltage and current are essentially sinusoidal. As the application of switching devices has been increased, the waveforms of voltage and current have involved the harmonics. Therefore, power energy involving voltage and current with the harmonics is supplied to the system and the registration error of watthour meter is existed. In this paper, we experimented on the error of watthour mesurement under the sinusoidal and nonsinusoidal input source.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2012.04a
• /
• pp.208-211
• /
• 2012

전력시스템에서 MDMS(Meter Data Management System)는 HAN(Home Area Network)과 Smart Meter, SUN(Smart energy Utility Network)와 같은 AMI(Advanced Metering Infrastructure) 기반 환경에서 수많은 전력 또는 수도 가스 사용량과 같은 데이터를 수집, 취득하고, 이들 데이터를 처리, 가공, 분석하여 가치 있는 정보로 변환시켜, 요금서비스 및 다양한 부가서비스 창출에 활용되는 소프트웨어 인프라이다. 최근 MDMS 개발은 기능의 중요성 뿐만 아니라 다른 응용 시스템들과의 상호 운용성을 고려하여 개발하는 요구 기능을 가진다. 본 논문에서는 스마트그리드 환경에 적합한 AMI의 전력처리시스템(MDMS) 개발을 위한 설계 방안을 기술하였다.

• Transactions of the Korean hydrogen and new energy society
• /
• v.29 no.1
• /
• pp.32-40
• /
• 2018

There has been an measuring errors between state of charge (SOC; kg) value and mass flow meter (MFM) value in dispenser for hydrogen refueling station. Finally, we observed average 15.5% weight difference between these two values and the MFM readings show a 15.5% higher readout of the SOC readings. Each car was charged with average 2.66 kg of hydrogen fuel during this period. In the initial charging of the day shows less measuring value than the final charging with the maximum 0.038 kg times number of filling. There is no effects of atmosphere temperature change for the hydrogen filled weight during one full year such as January's cold winters and August's hot summers.

• Journal of the Korean Society for Precision Engineering
• /
• v.28 no.6
• /
• pp.687-693
• /
• 2011

Spring-mass models have been widely accepted to explain the basic dynamics of human gait. Researchers found that the leg stiffness increased with gait speed to increase energy efficiency. However, the difference of leg stiffness change with gait speed between the young and the elderly has not been verified yet. In this study, we calculated the lower limb stiffness of the elderly using walking model with an axial spring. Vertical stiffness was defined as the ratio of the vertical force change to the vertical displacement change. Seven young and eight elderly subjects participated to the test. The subjects walked on a 12 meter long, 1 meter wide walkway at four different gait speeds, ranging from their self-selected speed to maximum speed randomly. Kinetic and kinematic data were collected using three force plates and motion capture cameras, respectively. The vertical stiffness of the two groups increased as a function of walking speed. Maximum walking speed of the elderly was slower than that of the young, yet the walking speed correlated well with the optimal stiffness that maximizes propulsion energy in both groups. The results may imply that human may use apparent limb stiffness to optimize energy based on spring-like leg mechanics.

• Transactions of the Korean hydrogen and new energy society
• /
• v.28 no.3
• /
• pp.279-286
• /
• 2017

Korea government decides to build one hundred hydrogen refueling stations (HRS) until 2020 and tries to disseminate HRS and boosts HRS market in korea. Naepo HRS in chungnam province has been operated for last one full year of 2016 and recorded 2,520 times full charge for the hydrogen fuel cell powered vehicles and total 6,016 kg hydrogen fueling for the 25 units of hydrogen fuel cell powered vehicles. Raw fuel of hydrogen from tube trailer measured by pressure, converting into weight of hydrogen and shows 19.6% surplus with final charged weight by dispenser. This result is caused measuring errors. Measured charged errors between dispenser and Mass flow meter was determined 13.13%.

• Proceedings of the KIEE Conference
• /
• 2006.11a
• /
• pp.114-116
• /
• 2006

본 논문에서는 DLMS/COSEM에 기반하여 전자식 전력량계의 전력정보를 모델링하는 방법을 제안 하였다. 유효/무효 전력량, 수요전력, 역률 등의 전력정보를 서술하였으며, 이러한 전력정보를 DLMS/COSEM에 기초하여 모델링하는 방법을 서술하였다.

• Transactions of the Korean hydrogen and new energy society
• /
• v.18 no.3
• /
• pp.238-243
• /
• 2007

The composite powder of Cu and YSZ was synthesized for a high temperature electrolysis cathode by mechanical milling. The average Cu particle size was reduced to 5 micro-meter from 48 micro-meter after the mechanical ball milling. The composite powder showed that Cu particles were uniformly covered with finer YSZ particles. Sub-micron sized pores were uniformly dispersed in the Cu/YSZ composit. Homogeneously-dispersed fine YSZ in the composite is expected to the increase in triple phase boundaries, thereby leading the enhanced performance of cathode.

• 제어로봇시스템학회:학술대회논문집
• /
• 2001.10a
• /
• pp.104.1-104
• /
• 2001

This paper presents a technique to development load control and management system in order to limits a maximum load demand and saves electric energy consumption. The computer programming proper load forecasting algorithm associated with programmable logic control and digital power meter through inform of multidrop network RS 485 over the twisted pair, over all are contained in this system. The digital power meter can measure a load data such as V, I, pf, P, Q, kWh, kVarh, etc., to be collected in statistics data convey to data base system on microcomputer and then analyzed a moving linear regression of load to forecast load demand Eventually, the result by forecasting are used for compost of load management and shedding for demand monitoring, Cycling on/off load control, Timer control, and Direct control. In this case can effectively reduce the electric energy consumption cost for 10% ...

• Solar Energy
• /
• v.5 no.2
• /
• pp.3-10
• /
• 1985

This paper is concerned with the characterized method of wind speed distribution for calculation of wind power density of regional group and wind potential in Korea. It is shown that the Rayleigh distribution, K = 2, is not suitable for analyzing wind data in Korea. Simple relationship, K = 0.21 V + 0.84, is derived from Weibull wind distribution by analyzing wind data obtained from 24 meteorological station and is a suitable tool for estimation of wind power density. Application of this result, the domestic ideal and actual wind potential are estimated as $3.16{\times}10^9$ KWH/year and $7.14{\times}$10^8 KWH/year respectively for the case of 10 meter height, $1m^2$ swept area and $0.1{\times}0.1Km^2$ land area. And for the case of 50 meter height, ideal and actual wind potential are increased as $7.56{\times}10^9$ KWH/year and $2.37{\times}10^9$ KWH/year respectively.