• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.7
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• pp.1144-1150
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• 2016

Short-term load forecasting is essential to the electricity pricing and stable power system operations. The conventional weekday 24-hour load forecasting algorithms consider the temperature model to forecast maximum load and minimum load. But 24-hour load pattern forecasting models do not consider temperature effects, because hourly temperature forecasts were not present until the latest date. Recently, 3 hour temperature forecast is announced, therefore hourly temperature forecasts can be produced by mathematical techniques such as various interpolation methods. In this paper, a new 24-hour load pattern forecasting method is proposed by using similar day search considering the hourly temperature. The proposed method searches similar day input data based on the anomalous weather features such as continuous temperature drop or rise, which can enhance 24-hour load pattern forecasting performance, because it uses the past days having similar hourly temperature features as input data. In order to verify the effectiveness of the proposed method, it was applied to the case study. The case study results show high accuracy of 24-hour load pattern forecasting.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.11
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• pp.1608-1614
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• 2014

Power demand forecasting is an important factor of the peak management. This paper deals with the 15 minutes ahead load forecasting problem in a DC urban railway system. Since supplied power lines to trains are connected with parallel, the load characteristics are too complex and highly non-linear. The main idea of the proposed method for the 15 minutes ahead prediction is to use the daily load similarity accounting for the load nonlinearity. An Euclidean norm with weighted factors including loads of the neighbor substation is used for the similar load selection. The prediction value is determinated by the sum of the similar load and the correction value. The correction has applied the neural network model. The feasibility of the proposed method is exemplified through some simulations applied to the actual load data of Incheon subway system.

• Journal of Electrical Engineering and Technology
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• v.13 no.2
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• pp.591-598
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• 2018

Short term load forecasts complexly affected by socioeconomic factors and weather variables have non-linear characteristics. Thus far, researchers have improved load forecast technologies through diverse techniques such as artificial neural networks, fuzzy theories, and statistical methods in order to enhance the accuracy of load forecasts. Short term load forecast errors for special days are relatively much higher than that of weekdays. The errors are mainly caused by the irregularity of social activities and insufficient similar past data required for constructing load forecast models. In this study, the load characteristics of Lunar New Year's Day holidays well known for the highest error occurrence holiday period are analyzed to propose a load forecast technique for Lunar New Year's Day holidays. To solve the insufficient input data problem, the similarity of the load patterns of past Lunar New Year's Day holidays having similar patterns was judged by Euclid distance. Lunar New Year's Day holidays periods for 2011-2012 were forecasted by the proposed method which shows that the proposed algorithm yields better results than the comprehensive analysis method or the knowledge-based method.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.32 no.5
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• pp.411-418
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• 2008

In this work, the effect of strength mismatch on plastic limit loads is quantified for similar metal weld plates with cracks under tension load, via three-dimensional, small strain elastic-perfectly plastic finite element analyses. Relevant variables related to plate geometry and crack length are systematically varied, in addition to the weld width. An important finding is that mis-match limit loads can be uniquely quantified through strength mis-match ratio and one geometry-related parameter. Based on the proposed limit load solutions, reference stress based J-integral estimates is also investigated. When the reference stress is defined by the mis-match limit load, predicted J-integral values agree overall well with FE results.

• Journal of Korea Multimedia Society
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• v.20 no.5
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• pp.800-807
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• 2017

The Pattern Sequence-based Forecasting (PSF) is an approach to forecast the behavior of time series based on similar pattern sequences. The innovation of PSF method is to convert the load time series into a label sequence by clustering technique in order to lighten computational burden. However, it brings about a new problem in determining the number of clusters and it is subject to insufficient similar days occasionally. In this paper we proposed an adaption of the PSF method, which introduces a new clustering index to determine the number of clusters and imposes a threshold to solve the problem caused by insufficient similar days. Our experiments showed that the proposed method reduced the mean absolute percentage error (MAPE) about 15%, compared to the PSF method.

• Geomechanics and Engineering
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• v.29 no.4
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• pp.407-420
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• 2022

Embedded piles, which are typically used in Korea, are precast piles inserted into prebored ground with cement paste. Dynamic pile tests tend to underestimate the bearing capacity of embedded piles because of the undeveloped shaft resistance prior to the curing of the cement paste and the insufficient energy transferred after the curing. In this study, a resistance combination method using the base resistance before the cement paste is cured and the shaft resistance after the cement paste is cured is proposed to obtain a combined load-settlement curve from dynamic pile tests. Two pairs of embedded piles with diameters of 600 and 500 mm are installed. Each pair comprises one pile for the dynamic pile test and another pile for the static load test. The shape of the load-settlement curve obtained using the proposed method is similar to that obtained from the static load test. Thus, the resistances evaluated using the proposed method at selected settlements are similar to those obtained from the static load test. This study shows that the resistance combination method may be used effectively in dynamic pile tests to accurately evaluate the bearing capacity of embedded piles.

• Restorative Dentistry and Endodontics
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• v.19 no.2
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• pp.384-408
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• 1994

The purpose of this study was to evaluate the fracture resistance of tooth restored with gold inlay. A profound understanding of the isthmus width factor, which is one of the several parameters of cavity designs, would facilitate the appropriate cavity preparation in a specific clinical situation. In this study, the cavities for gold inlay were prepared in maxillary left first premolar. A three-dimensional model was designed using I-DEAS program. The model was composed of 2515- nodes and 2172 isoparametric brick elements. In the model isthmus width was varied into 1/4, 1/3 and 1/2 of intercuspal width respectively, and numeric values of the material properties of enamel, dentin and gold was set. Three types of load : concentrated load, divided load and distributed load was 500N. The empty cavities in the model were also examined using divided load and distributed load. The three - dimensional Finite Element Method was used to analysis the displacement and stress distribution. The results were as follows : 1. All of the experimental models which were filled with gold inlay revealed similar direction of displacement to that of the natural tooth model under the same load type. But in the models with empty cavities, as the isthmus width increased, the degree of displacement increased in the case of divided load type. 2. All experimental models which were filled with gold inlay showed stress concentration at load points, but in the models with empty cavities at divided load type, as isthmus width increased, stress was concentrated at the comer of the pulpal floor. 3. In the models with empty cavities at divided load type, tooth fracture was expected regardless of isthmus width, but all experimental models which were filled with gold inlay after cavity preparation were not susceptible to fracture. 4. In all experimental models which were filled with gold inlay after cavity preparation, displacement patterns were similar under both concentrated and divided load types. In the models with empty cavities, a divided load resulted in a bucco-lingual cuspal displacemenat in both sides, but a distributed load resulted in a lingual displacement of the tooth.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2002.10a
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• pp.51-55
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• 2002

End of July. 2002 Hyundai Heavy Industries Co. Ltd. Offshore Division is successfully completed Load-out & Float-off work of "AMENAM KPONO/FSO Project" similar to 300K VLCC size. The AMENAM FSO hull and topside module built at the HHI Offshore yard using "On-Ground Building Method" developed by HHI. Various methodologies/techniques like Flexi-built FPSO Hull. Topside module erection method. Load-out Float-off methodology etc. are combined to develop a successful on-ground building method. In this paper, we described the "Hull Structural Strength Analysis Methodology" using 3-D Finite Element Analysis and results. This analysis is performed to verily the structural integrity or the AMENAM FSO hull during the main load-out on two semi-submersible barges combined together.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.9
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• pp.1516-1521
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• 2008

Recently, distribution load analysis using AMR (Automatic Meter Reading) data is researched in electric utilities. Load analysis method based on AMR system generates the typical load profile using load data of AMR customers, estimates the load profile of non-AMR customers, and analyzes the peak load and load profile of the distribution circuits and sectors per every 15 minutes/hour/day/week/month. Typical load profile is generated by the algorithm calculating the average amount of power consumption of each groups having similar load patterns. Traditional customer clustering mechanism uses only contract type code as a key. This mechanism has low accuracy because many customers having same contract code have different load patterns. In this research, We propose a customer clustring mechanism using k-means algorithm with contract type code and AMR data.

• Journal of the Korean Solar Energy Society
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• v.30 no.3
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• pp.39-46
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• 2010

This study is focused on the effect of thermal load according to the various plan types in tower-type apartment in Korea. So, we chose the '』' type model in order to analyze the shading effect of the plan type. The main results are as follows. In chosen model, cooling energy demands are more sensitive than heating ones when is compared with the two methods. And there are about 10% deviations between new and conventional method. Because new method considers more detailed than conventional one about the building geometries. We also found that this building type affects to the about 3 floors from the top and it doesn't affect to the thermal load in lower floors. From these facts, we suggest new modeling method to the similar researches that will be analyzed the thermal load on the tower type apartment in Korea. Also there is no difference of the thermal load in each azimuth between simple and detailed modeling method. Consequently, we judge that this new method considered the shading effect will be used a lot to the similar analysis in tower type apartment in Korea.