• Title, Summary, Keyword: seasonal effect

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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.

The Numerical Analysis of Jeju Harbor Flow Considering Effect of Seasonal Wind

  • Kim, Nam-Hyeong;Park, Ji-Hun;Kang, Hyun-Woo
    • Journal of Navigation and Port Research
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    • v.31 no.9
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    • pp.793-799
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    • 2007
  • The effect of seasonal wind on the tidal circulation in Jeju harbor was examined by using a numerical shallow water model. A finite element for analyzing shallow water flow is presented. The Galerkin method is employed for spatial discretization. Two step explicit finite element scheme is used to discretize the time function, which has advantage in problems treating large numbers of elements and unsteady state. The numerical simulation is compared with three cases; Case 1 does not consider the effect of wind, Case 2 and Case 3 consider the effect of summer and winter seasonal wind, respectively. According to result considering effect of seasonal wind, velocity of current vector shows slightly stronger than that of case 1 in the flow field. It can be concluded that the present method is a useful and effective tool in tidal current analysis.

Trading Day Effect on the Seasonal Adjustment for Korean Industrial Activities Trend Using X-12-ARIMA

  • Park, Worlan;Kang, Hee Jeung
    • Communications for Statistical Applications and Methods
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    • v.7 no.2
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    • pp.513-523
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    • 2000
  • The X-12-ARIMA program was utilized on the analysis of the time series trend on 76 Korean industrial activities data in order to ensure that the trading day effect adjustment as well as the seasonal effect adjustment is needed to extract the fundamental trend-cycle factors from various economic time series data. The trading day effect is strongly correlated with the activity of production and shipping but not with the activity of inventory. Furthermore, the industrial activities were classified with respect to the sensitivity on the tranding day effect.

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Developing the Bullwhip Effect Measure in a Supply Chain Considering Seasonal Demand and Stochastic Lead Time (공급사슬에서 계절적 수요와 추계적 조달기간을 고려한 채찍효과 측도의 개발)

  • Cho, Dong-Won;Lee, Young-Hae
    • Journal of the Korean Operations Research and Management Science Society
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    • v.34 no.4
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    • pp.91-112
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    • 2009
  • The bullwhip effect means the phenomenon of increasing demand variation as moving UP to the upstream in the supply chain. Therefore, it is recognized that the bullwhip effect is problematic for effective supply chain operations. In this paper, we exactly quantifies the bullwhip effect for the case of stochastic lead time and seasonal demand in two-echelon supply chain where retailer employs a base-stock policy considering SARMA demand processes and stochastic lead time. We also investigate the behavior of the proposed measurement for the bullwhip effect with autoregressive and moving average coefficient, stochastic lead time, and seasonal factor.

Seasonal effect on hydrological models parameters and performance

  • Birhanu, Dereje;Kim, Hyeonjun;Jang, Cheolhee;Park, Sanghyun
    • Proceedings of the Korea Water Resources Association Conference
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    • pp.326-326
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    • 2018
  • The study will assess the seasonal effect of hydrological models on performance and parameters for streamflow simulation. TPHM, GR4J, CAT, and TANK-SM hydrological models will be applied for simulating streamflow in ten small and large watersheds located in South Korea. The readily available hydrometeorological data will be applied as an input to the four hydrological models and the potential evapotranspiration will be computed using the Penman-Monteith equation. The SCE-UA algorithm implemented in PEST will be used to calibrate the models considering similar objective functions bedside the calibration will be renewed to capture the seasonal effects on the model performance and parameters. The seasonal effects on the model performance and parameters will be presented after assessing the four hydrologic models results. The conventional approach and season-based results will be evaluated for each model in the tested watersheds and a conclusion will be made based on the finding of the results.

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Regression models based on cumulative data for forecasting of new product (신제품 수요예측을 위하여 누적자료를 활용한 회귀모형에 관한 연구)

  • Park, Sang-Gue;Oh, Jung-Hyun
    • Journal of the Korean Data and Information Science Society
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    • v.20 no.1
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    • pp.117-124
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    • 2009
  • If time series data with seasonal effect exist, various statistical models like winters for successful forecasts could be used. But if the data are not enough to estimate seasonal effect, not much methods are available. This paper proposes the statistical forecasting method based on cumulative data when the data are not enough to estimate seasonal effect. We apply this method to real cosmetic sales data and show its better performance over moving average method.

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The effect on the seasonal performance of an inverter compressor with higher and lower operating range (인버터 압축기의 저속과 고속운전범위가 계절성능에 미치는 영향)

  • 박윤철;하도용;민만기
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.10 no.2
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    • pp.173-179
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    • 1998
  • An experimental study was conducted on the effect of compressor capacity control range of heat pump on the seasonal energy efficiency ratio with variation of the maximum and minimum compressor input frequencies. To obtain seasonal energy efficiency ratio, steady state test at the maximum, minimum and intermediate compressor speed and cyclic test at the minimum compressor speed should be conducted. Maximum input frequency was varied to 95Hz, 105Hz, and 115Hz, and the minimum input frequency was varied to 35Hz, 45Hz, and 55Hz. The seasonal energy efficiency ratio increased as the input frequency of the compressor decreased. The maximum input frequency had only slight effects on the SEER.

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Seasonal Variation of Coastal Front by Numerical Simulation in the Southern Sea of Korea (수치모델을 이용한 한국 남해안 전선의 계절변동)

  • Bae, Sang-Wan;Kim, Dong-Sun
    • Journal of Environmental Science International
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    • v.20 no.9
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    • pp.1141-1149
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    • 2011
  • The three-dimensional hydrodynamic model was simulated to understand coastal sea front of formation and seasonal variation in the Southern Sea of Korea. In this study, we used to concept of stratification factor, to realize seasonal distribution of stratification coefficient which of seasonal residual flow, considered with, tide, wind and density effect. Tidal current tends to flow westward during the flood and eastward during ebb. The current by the wind stress showed to be much stronger the coastal than the offshore area in the surface layer. And the current by the horizontal gradient of water density showed to be relatively weak in the coastal area, with little seasonal differences. On the other hand, the flow in the offshore area showed results similar to that of the Tsushima Warm Current. The stratification factor (SHv) was calculated by taking into account the total flow of tide, wind and density effect. In summer, the calculated SHv distribution ranged from 2.0 to 2.5, similar to that of the coastal sea front. The horizontal temperature gradient showed to be strong during the winter, when the vertical stratification is weak. On the other hand, the horizontal gradient became weak in summer, during which vertical stratification is strong. Therefore, it is presume that the strength of vertical stratification and the horizontal temperature gradient affect the position of the coastal sea front.

The Effects of Season on Physiological Responses of Human Body, Clothing Microclimate, and Subjective Sensations (인체의 생리적 반응과 의복 기후, 주관적 감각에 미친 계절의 영향)

  • 김양원
    • Journal of the Korean Home Economics Association
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    • v.30 no.4
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    • pp.15-26
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    • 1992
  • To investigate the seasonal effects on physiological responses of human body, clothing micro-climate, and subjective sensation, selected the cloths the most frequently dressed by men in spring and fall, and completed wearing trials in the climatic chamber. The results are as follows: 1. Rectal temp. ranged 36.8-37.1$^{\circ}C$ in either spring or fall, and no seasonal effect was found. 2. In skin temp., there was no seasonal effect in forehead, abdomen, and forearm. Skin temp. of chest was higher in spring than in fall. On the contrary, reverse was true in high and leg. Average skin temp. ranged 32.2-33.2$^{\circ}C$ in spring and 32.9-34.$0^{\circ}C$ in fall. 3. Average total sweat rate of spring, 79.4g/hr, was smaller than that of fall, 110.9g/hr. 4. Clothing temp. ranged 28.1-32.8$^{\circ}C$ in spring and 27.6-31.$0^{\circ}C$ in fall. Clothing humidity ranged 36.9-48.9% in spring and 38.2-51.1% in fall. Therefore, clothing microclimate was higher during fall than during spring. As results, skin temp. of the body core except chest did not show seasonal variation, but there was obvious seasonal variation in skin temp. of the extremities. Therefore, seasonal variation should be take into consideration in the experiments related to the cloth. In addition, standard for each season and the degree of work performance should be re-established in clothing micro-climate.

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A Study on the Seasonal Adjustment of Time Series for Seasonal New Product Sales (계절상품 판매매출액 시계열의 계절 조정에 관한 연구)

  • 서명율;이종태
    • Korean Management Science Review
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    • v.20 no.1
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    • pp.103-124
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    • 2003
  • The seasonal adjustment is an essential process in analyzing the time series of economy and business. There are various methods to adjust seasonal effect such as moving average, extrapolation, smoothing and X11. One of the powerful adjustment methods is X11-ARIMA Model which is popularly used in Korea. This method was delivered from Canada. However, this model has been developed to be appropriate for Canadian and American environment. Therefore, we need to review whether the Xl1-ARIMA Model could be used properly in Korea. In this study, we have applied the method to the annual sales of refrigerator sales in A electronic company. We appreciated the adjustment by result analyzing the time series components such as seasonal component, trend-cycle component, and irregular component, with the proposed method.