• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 추계학술대회 논문집 전력기술부문
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• pp.272-274
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• 2001

This paper presents a model for short-term load forecasting using relationship of temperature and load. We made one-day ahead load forecasting model using hourly normalized load and 11 dummy variables that were classified by day characteristics such as day of the week, holiday, and special holiday.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 합동 추계학술대회 논문집 정보 및 제어부문
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• pp.61-64
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• 2001

The electric power load during the peak time in summer is strongly affected by cooling load. which decreases the preparation ratio of electricity and brings about the failure in the supply of electricity in the electric power system. The ice-storage system and heat pump system etc are used to settle this problem. In this study, the method of estimating temperature and humidity to forecast the cooling load of ice-storage system is suggested. And also the method of forecasting the cooling load using neural network is suggested. For the simulation, the cooling load is calculated using actual temperature and humidity. The forecast of the temperature, humidity and cooling load are simulated. As a result of the simulation, the forecasted data approached to the actual data.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2015년도 제46회 하계학술대회
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• pp.300-301
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• 2015

Accurate and robust load forecasting model plays very important role in power system operation. In case of short-term electric load forecasting, its results offer standard to decide a price of electricity and also can be used shaving peak. For this reason, various models have been developed to improve accuracy of load forecasting. This paper proposes a newly forecasting model for weather sensitive season including temperature and Cooling Degree Hour(C.D.H) data as an input. This Forecasting model consists of previous electric load and preprocessed temperature, constant, parameter. It optimizes load forecasting model to fit actual load by PSO and results are compared to Holt-Winters and Artificial Neural Network. Proposing method shows better performance than comparison groups.

• Advances in Computational Design
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• 제3권1호
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• pp.1-16
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• 2018

The decaying temperature and dynamic response of a thermoelastic nanobeam subjected to a moving load has been investigated in the context of generalized theory of nonlocal thermoelasticity. The transformed distributions of deflection, temperature, axial displacement and bending moment are obtained by using Laplace transformation. By applying a numerical inversion method, the results of these fields are then inverted and obtained in the physical domain. Also, for a particular two models, numerical results are discussed and presented graphically. Some specific and special results are derived from the current study.

• 대한치과기공학회지
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• 제35권2호
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• pp.127-136
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• 2013

Purpose: In order to find out the impact of changes in polymerization conditions of orthodontic acrylic resin on maximum load. Methods: While maintaining mixing ratio 3:1 of polymer and monomer in spray-on way in the production condition of polymerization temperature $25^{\circ}C$ or $37^{\circ}C$ for 10 minutes or 30 minutes of polymerization time by pressure $3kfg/cm^2$ or $6kfg/cm^2$ in the lab maintaining $25^{\circ}C$ of room temperature, the change in maximum load rise rate was tested by producing 5 acrylic resin specimens for orthodontics per group to meet the standards of $25mm{\times}2mm{\times}2mm$ and using INSTRON with the 3rd bar 2mm in diameter and parallel support bending device of $15{\pm}0.1mm$ as test equipment showing 30.00mm/min of crosshead speed, $50{\pm}16$ N/min of load ratio in the laboratory of $24^{\circ}C$ room temperature and as a result, the following results were obtained. Results: 1. When increasing pressure from $3kfg/cm^2$ to $6kfg/cm^2$, maximum load was lowered by -4.285%. 2. When increasing polymerization time from 10 minutes to 30 minutes, maximum load rose by 3.848%. 3. When increasing polymerization temperature from $27^{\circ}C$ to $37^{\circ}C$, maximum load rose by 5.854%. Conclusion: Considering the above test results that polymerization time and polymerization temperature when polymerizing acrylic resin for orthodontics according to changes in working conditions had an impact on the rate of rise of maximum load values but the rate of rise was lowered when increasing pressure from $3kfg/cm^2$ to $6kfg/cm^2$, we came to a conclusion that high pressure more than necessary does not affect the rate of rise of maximum load.

• Steel and Composite Structures
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• 제42권5호
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• pp.649-655
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• 2022

In presented paper, moving load problem of simply supported axially functionally graded (AFG) beam is investigated under temperature rising based on the first shear beam theory. The material properties of beam vary along the axial direction. Material properties of the beam are considered as temperature-dependent. The governing equations of problem are derived by using the Lagrange procedure. In the solution of the problem the Ritz method is used and algebraic polynomials are used with the trivial functions for the Ritz method. In the solution of the moving load problem, the Newmark average acceleration method is used in the time history. In the numerical examples, the effects of material graduation, temperature rising and velocity of moving load on the dynamic responses ofAFG beam are presented and discussed.

• 조명전기설비학회논문지
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• 제23권9호
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• pp.47-54
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• 2009

'08.12$\sim$'09. 2월 동절기에 세계경제위축 심화에 따른 수출 급감으로 제조업은 마이너스 성장을 기록함에 따라 우리나라 전력소비의 53[%]를 차지하는 산업용 전력이 약 7[%]의 감소율을 나타내고 있다. 또한 국내에는 내수경기침체에 따른 전력소비 감소와 평년 대비 기온 상승으로 인한 난방수요 감소로 일일 전력수요 패턴에 많은 변화를 보이고 있다. 본 연구에서는 동절기의 최대전력, 평균전력, 상대계수에 의한 전력수요 패턴, 시간대별 온도민감도 분석을 통하여 최대전력은 GDP 성장률 보다는 기온변화에 민감한 반면, 평균전력은 GDP 성장률에 비례하여 감소하는 추세를 보이고 있는 것으로 분석되었다. 이 자료를 근거로 동 하절기의 최대전력과 평균전력의 정확한 전력 수요 예측으로 전력계통을 경제적이고 안정적으로 운영할 수 있다고 여겨진다.

• Tribology and Lubricants
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• 제31권4호
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• pp.141-147
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• 2015

Gas foil thrust bearings (GFTBs) have attractive advantages over rolling element bearings and oil film thrust bearings, such as oil-free operation, high speed stability, and high-temperature operation. However, GFTBs have lower load carrying capacity than the other two types of bearings owing to the inherent low gas viscosity. The load carrying capacity of GFTBs depends mainly on the compliance of the foil structure and the formed hydrodynamic wedge, where the gas pressure field is generated between the top foil and the thrust runner. The load carrying capacity of the GFTBs is very important for the suitable design of oil-free turbomachinery with high performance. The aim of the present study is to identify the characteristics of the load carrying performance of GFTBs. A new test rig for the experimental measurements is designed to provide static loads up to 800 N using a pneumatic cylinder. The maximum operating speed of the driving motor is 30,000 rpm. A series of experimental tests—lift-off test, static load performance test, and maximum load capacity test—estimate the performance of a six-pad GFTB, in terms of the static load, driving torque, and temperature. The maximum load capacity is determined by increasing the static load until the driving torque rises suddenly with a sharp peak. The test results show that the torque and temperature increase linearly with the static load. The estimated maximum load capacity per unit area is approximately 80.5 kPa at a rotor speed of 25,000 rpm. The test results can be used as a design guideline for GFTBs for realizing oil-free turbomachinery.

• 한국항공우주학회지
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• 제47권12호
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• pp.881-889
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• 2019

가스터빈 이차 유로의 프리스월 시스템은 터빈의 효율을 높이고 소재의 수명을 연장하기 위해 설치되는 냉각 장치이다. 본 연구에서는 프리스월 시스템의 설계점을 기준으로 가스터빈 외기 온도와 터빈 부하 변화에 따른 탈설계점 분석을 수행하였다. 탈설계점에서 내부 유동의 특성을 분석하기 위하여 유량계수와 단열계수를 비교하였다. 터빈 부하 증가에 따라 시스템 내부 냉각 공기의 체적 유량이 증가하였고, 단열계수 또한 20% 터빈 부하와 비교하여 100% 터빈 부하에서 30.46% 상승하였다. 외기 온도가 증가할수록 질량 유량과 냉각 공기의 밀도는 감소하였지만 체적 유량은 상승하였으며, 결과적으로 프리스월 시스템 내부의 냉각 성능은 향상되었다. 프리스월 시스템 출구에서 -20℃ 외기 온도와 비교하여 55℃ 외기 온도의 단열계수는 14.82% 향상되었다.

• 설비공학논문집
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• 제24권11호
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• pp.759-766
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• 2012

To estimate the cooling load for the following day, outdoor temperature and humidity are needed in hourly base. But the meteorological administration forecasts only maximum and minimum temperature. New methodology is proposed for predicting hourly outdoor temperature and humidity by using the forecasted maximum and minimum temperature. The correlations for normalized outdoor temperature and specific humidity has been derived from the weather data for five years at Seoul, Daejeon and Pusan. The correlations for normalized temperature are independent of date, while the correlations for specific humidity are linearly dependent on date. The predicted results show fairly good agreement with the measured data. The prediction program is also developed for hourly outdoor dry bulb temperature, specific humidity, dew point, relative humidity, enthalpy and specific volume.