• Title/Summary/Keyword: forecast performance

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Quantifying the Bullwhip Effect in a Supply Chain Considering Seasonal Demand (공급사슬에서 계절적 수요를 고려한 채찍효과 측도의 개발)

  • Cho, Dong-Won;Lee, Young-Hae
    • Journal of Korean Institute of Industrial Engineers
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    • v.35 no.3
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    • pp.203-212
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    • 2009
  • The bullwhip effect refers to the phenomenon where demand variability is amplified when one moves upward a supply chain. In this paper, we exactly quantify the bullwhip effect for cases of seasonal demand processes in a two-echelon supply chain with a single retailer and a single supplier. In most of the previous research, some measures of performance for the bullwhip effect are developed for cases of non-seasonal demand processes. The retailer performs demand forecast with a multiplicative seasonal mixed model by using the minimum mean square error forecasting technique and employs a base stock policy. With the developed bullwhip effect measure, we investigate the impact of seasonal factor on the bullwhip effect. Then, we prove that seasonal factor plays an important role on the occurrence of the bullwhip effect.

Electric Power Load Forecasting using Fuzzy Prediction System (퍼지 예측 시스템을 이용한 전력 부하 예측)

  • Bang, Young-Keun;Shim, Jae-Sun
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.62 no.11
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    • pp.1590-1597
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    • 2013
  • Electric power is an important part in economic development. Moreover, an accurate load forecast can make a financing planning, power supply strategy and market research planned effectively. This paper used the fuzzy logic system to predict the regional electric power load. To design the fuzzy prediction system, the correlation-based clustering algorithm and TSK fuzzy model were used. Also, to improve the prediction system's capability, the moving average technique and relative increasing rate were used in the preprocessing procedure. Finally, using four regional electric power load in Taiwan, this paper verified the performance of the proposed system and demonstrated its effectiveness and usefulness.

Generalized Replacement Demand Forecasting to Complement Diffusion Models

  • Chung, Kyu-Suk;Park, Sung-Joo
    • Journal of Korean Institute of Industrial Engineers
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    • v.14 no.1
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    • pp.103-117
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    • 1988
  • Replacement demand plays an important role to forecast the total demand of durable goods, while most of the diffusion models deal with only adoption data, namely initial purchase demand. This paper presents replacement demand forecasting models incorporating repurchase rate, multi-ownership, and dynamic product life to complement the existing diffusion models. The performance of replacement demand forecasting models are analyzed and practical guidelines for the application of the models are suggested when life distribution data or adoption data are not available.

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Forecasting Exchange Rates using Support Vector Machine Regression

  • Chen, Shi-Yi;Jeong, Ki-Ho
    • 한국데이터정보과학회:학술대회논문집
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    • 2005.04a
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    • pp.155-163
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    • 2005
  • This paper applies Support Vector Regression (SVR) to estimate and forecast nonlinear autoregressive integrated (ARI) model of the daily exchange rates of four currencies (Swiss Francs, Indian Rupees, South Korean Won and Philippines Pesos) against U.S. dollar. The forecasting abilities of SVR are compared with linear ARI model which is estimated by OLS. Sensitivity of SVR results are also examined to kernel type and other free parameters. Empirical findings are in favor of SVR. SVR method forecasts exchange rate level better than linear ARI model and also has superior ability in forecasting the exchange rates direction in short test phase but has similar performance with OLS when forecasting the turning points in long test phase.

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ADS-B based Trajectory Prediction and Conflict Detection for Air Traffic Management

  • Baek, Kwang-Yul;Bang, Hyo-Choong
    • International Journal of Aeronautical and Space Sciences
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    • v.13 no.3
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    • pp.377-385
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    • 2012
  • The Automatic Dependent Surveillance Broadcast (ADS-B) system is a key component of CNS/ATM recommended by the International Civil Aviation Organization (ICAO) as the next generation air traffic control system. ADS-B broadcasts identification, positional data, and operation information of an aircraft to other aircraft, ground vehicles and ground stations in the nearby region. This paper explores the ADS-B based trajectory prediction and the conflict detection algorithm. The multiple-model based trajectory prediction algorithm leads accurate predicted conflict probability at a future forecast time. We propose an efficient and accurate algorithm to calculate conflict probability based on approximation of the conflict zone by a set of blocks. The performance of proposed algorithms is demonstrated by a numerical simulation of two aircraft encounter scenarios.

Neural Network and Its Application to Rainfall-Runoff Forecasting

  • Kang, Kwan-Won;Park, Chan-Young;Kim, Ju-Hwan
    • Korean Journal of Hydrosciences
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    • v.4
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    • pp.1-9
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    • 1993
  • It is a major objective for the management and operation of water resources system to forecast streamflows. The applicability of artificial neural network model to hydrologic system is analyzed and the performance is compared by statistical method with observed. Multi-layered perception was used to model rainfall-runoff process at Pyung Chang River Basin in Korea. The neural network model has the function of learning the process which can be trained with the error backpropagation (EBP) algorithm in two phases; (1) learning phase permits to find the best parameters(weight matrix) between input and output. (2) adaptive phase use the EBP algorithm in order to learn from the provided data. The generalization results have been obtained on forecasting the daily and hourly streamflows by assuming them with the structure of ARMA model. The results show validities in applying to hydrologic forecasting system.

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The Time Variant Power Signal Processing of Wind Generator using Buneman Frequency Estimator Algorithm (부너맨 주파수 추정 알고리듬을 이용한 풍력발전기 가변 전력신호 처리에 관한 연구)

  • Choi, Sang-Yule;Lee, Jong-Joo
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.24 no.12
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    • pp.138-146
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    • 2010
  • On wind turbine generators, the speed and volume of the wind affect the turbine angle speed which finally determines the output level of the electric power. However it is very difficult to forecast correctly the future power output and quality based on previous fixed sampling methods. This paper proposes a variable sampling method based on Buneman frequency estimation algorithm to reflect the variations of the frequency and amplitude on wind power outputs. The proposed method is also verified through the performance test by comparing with the results from previous fixed sampling methods and the real measurement data.

High Brightness Prism Light-guide Plate for TFT-LCDs Using Optical Simulation and Novel Injection Mold Process (광학시뮬레이션과 새로운 사출성형법을 사용한 TFT-LCD용 고휘도 프리즘 도광판)

  • Han, Jeong-Min;Shon, Jin-Geun
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.61 no.2
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    • pp.93-96
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    • 2012
  • We have designed high performance prism light-guide plate (LGP) in 17 inch TFT-LCD. In test result to embody high brightness BLU in case of LGP of base and upper surface with 17 inch, thickness 8mm adding prism construct. Using optical simulation, we forecast the brightness and uniformity in LGP with prism structure. And we adopted novel injection mold method and Nickel stamper to make actual evolution sample. Novel injection mold process has steady heating time zone in heat cycle time of injection mold process. For this novel heat cycle control, we achieved above 90[%] height prism structure as our design. It is superior brightness improvement than previous that of printing form about some 20[%] and in this course to embody actual material it succeeded prism LGP production by 17 inch injection form process.

A Study on the Performance of Slot Restrictor Bearing with a Variation in Circumferential Direction (원주방향 변화를 갖는 슬롯 레스트릭터 베어링의 성능 연구)

  • 박정구;김경웅
    • Tribology and Lubricants
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    • v.16 no.2
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    • pp.91-98
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    • 2000
  • A slot restrictor air journal bearing has high load capacity and high stiffness. The stability characteristics of the slot restrictor air journal bearing are studied theoretically and experimentally to forecast and to prevent the whirl instability. As for the high speed rotating machinery, the instability called'whirl'occurs when the rotor rotates at a speed more than twice the resonant speed. Once the whirl occurs, rubbing contact between the journal and the bearing occurs mostly and the bearing-rotor system is destroyed ultimately. Therefore, the forecasting and prevention of the occurrence of whirl instability is a very important subject especially to develop highly efficient high speed rotating machinery. The bearing with the slot restrictor that varies about circumferential direction is used for the purpose of the prevention of whirl instability.

Study on system dynamic behaviors for 4kW-class fuel cell hybrid vehicle (4kW급 연료전지 하이브리드 자동차 개발을 위한 시스템 동특성 연구)

  • Lee, Dong-Ryul;Park, Kwang-Jin;Bae, Joong-Myeon;Jeong, Jae-Haw;Ji, Hyun-Jin
    • 한국신재생에너지학회:학술대회논문집
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    • 2006.11a
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    • pp.93-96
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    • 2006
  • PEMFC(proton exchange membrane fuel cell) is most applicable to automobile in various types of fuel cell. However, to improve system dynamics and logn term Performance fuel cell is supported by auxiliary power unit forming hybrid system. The operating strategy of hybrid system influences on efficiency and stability. In this paper the proper strategies are compared each other considering power distribution and stable system operation. The chosen strategy is simulated by MATLAB simulink to forecast realization of fuel cell hybrid vehicle

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