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NLS와 OLS의 하이브리드 방법에 의한 Bass 확산모형의 모수추정
홍정식(Jungsik Hong),김태구(Taegu Kim),구훈영(Hoonyoung Koo) 대한산업공학회 2011 대한산업공학회지 Vol.37 No.1
The Bass model is a cornerstone in diffusion theory which is used for forecasting demand of durables or new services. Three well-known estimation methods for parameters of the Bass model are Ordinary Least Square (OLS), Maximum Likelihood Estimator (MLE), Nonlinear Least Square (NLS). In this paper, a hybrid method incorporating OLS and NLS is presented and it’s performance is analyzed and compared with OLS and NLS by using simulation data and empirical data. The results show that NLS has the best performance in terms of accuracy and our hybrid method has the best performance in terms of stability. Specifically, hybrid method has better performance with less data. This result means much in practical aspect because the avaliable data is little when a diffusion model is used for forecasting demand of a new product.
제약적 NLS 방법을 이용한 출시 초기 신제품의 중장기 수요 예측 방안
홍정식(Jungsik Hong),구훈영(Hoonyoung Koo) 한국경영과학회 2013 韓國經營科學會誌 Vol.38 No.1
A long-term forecasting method for a new product in early stage of diffusion is proposed. The method includes a constrained non-linear least square estimation with the logistic diffusion model. The constraints would be critical market informations such as market potential, peak point, and take-off. Findings on 20 cases having almost full life cycle are that (ⅰ) combining any market information improves the forecasting accuracy, (ⅱ) market potential is the most stable information, and (ⅲ) peak point and take-off information have negative effect in case of overestimation.
확산이론 관점에서 로지스틱 모형과 Bass 모형의 비교
홍정식(Jungsik Hong),구훈영(Hoonyoung Koo) 한국경영과학회 2012 韓國經營科學會誌 Vol.37 No.2
The logistic model and the Bass model have diverse names and formulae in diffusion theory. This diversity makes users or readers confused while it also contributes to the flexibility of modeling. The method of handling the integration constant, which is generated in process of deriving the closed form solution of the differential equation for a diffusion model, results in two different "actual" models. We rename the actual four models and propose the usage of the models with respect to the purpose of model applications. The application purpose would be the explanation of historical diffusion pattern or the forecasting of future demand. Empirical validation with 86 historical diffusion data shows that misuse of the models can draw improper conclusions for the explanation of historical diffusion pattern.
개봉 규모와 수익성에 따른 영화의 분류와 확산 패턴 분석
김태구(Taegu Kim),홍정식(Jungsik Hong) 대한산업공학회 2013 대한산업공학회지 Vol.39 No.5
Motion picture industry is one of the most representative fields in the cultural industry and has experienced constant growth both worldwide and within domestic markets. However, little research has been undertaken for diffusion patterns of motion pictures, whereas various issues such as demand forecasting and success factor analysis have been widely explored. To analyze diffusion patterns, we adopted extended Bass model to reflect the potential demand of movies. Four clusters of selected movies were derived by k-means clustering method with criteria of opening strength and profitability and then compared by their diffusion patterns. Results indicated that movies with high profitability and medium opening strength are most significantly influenced by word of mouth effect, while low profitability movies display nearly monotonic decreasing diffusion patterns with noticeable initial adoption rates and relatively early peak points in their runs.