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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.
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.
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.
Jang, Jungsik,Hong, Kee-Jeung The Institute of Internet 2020 International Journal of Internet, Broadcasting an Vol.12 No.3
This study discussesresearch and development of large-sized 3D printers that can be applied to construction and civil engineering for various designs of protective casing on foam liner for concrete exteriors. The consistent use of concrete represents the current surroundings. However, concrete exteriors in Korea have not considered the regional characteristics, but the concrete has been poured solely for economical aspects for the last decade or two. There are many cases of poor installation and not enough design development projects to correct it. This study was conducted to apply various patterns, regional characteristics, and 3D printing for protective casing design for foam liner to create various designs for the concrete walls. Therefore, we started researching on a large 3D printer, and designed and developed this system. Considering the chronological process, the properties of concrete structures were identified, the application of designs for concrete in Korea and abroad and the 3D printing materials for the protective casing were surveyed and analyzed, and a stereotype was produced in the first year to study designs for the beauty of concrete surfaces. In the second year, images of regional characteristics were gathered, design ideas for regional promotion were derived, virtual images were produced along with design modeling to simulate the appearances, and verify the effect of application and promotion. Finally, in the third year, the 3D printer for concrete foam liner was constantly improved to analyze the 3D printing program and the various library elements to complete an actual large-sized 3D printer.