A fundamental study on the automation of tunnel blasting design using a machine learning model (머신러닝을 이용한 터널발파설계 자동화를 위한 기초연구)
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- Journal of Korean Tunnelling and Underground Space Association
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- v.24 no.5
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- pp.431-449
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- 2022
As many tunnels generally have been constructed, various experiences and techniques have been accumulated for tunnel design as well as tunnel construction. Hence, there are not a few cases that, for some usual tunnel design works, it is sufficient to perform the design by only modifying or supplementing previous similar design cases unless a tunnel has a unique structure or in geological conditions. In particular, for a tunnel blast design, it is reasonable to refer to previous similar design cases because the blast design in the stage of design is a preliminary design, considering that it is general to perform additional blast design through test blasts prior to the start of tunnel excavation. Meanwhile, entering the industry 4.0 era, artificial intelligence (AI) of which availability is surging across whole industry sector is broadly utilized to tunnel and blasting. For a drill and blast tunnel, AI is mainly applied for the estimation of blast vibration and rock mass classification, etc. however, there are few cases where it is applied to blast pattern design. Thus, this study attempts to automate tunnel blast design by means of machine learning, a branch of artificial intelligence. For this, the data related to a blast design was collected from 25 tunnel design reports for learning as well as 2 additional reports for the test, and from which 4 design parameters, i.e., rock mass class, road type and cross sectional area of upper section as well as bench section as input data as well as16 design elements, i.e., blast cut type, specific charge, the number of drill holes, and spacing and burden for each blast hole group, etc. as output. Based on this design data, three machine learning models, i.e., XGBoost, ANN, SVM, were tested and XGBoost was chosen as the best model and the results show a generally similar trend to an actual design when assumed design parameters were input. It is not enough yet to perform the whole blast design using the results from this study, however, it is planned that additional studies will be carried out to make it possible to put it to practical use after collecting more sufficient blast design data and supplementing detailed machine learning processes.
This research is concerned with the social division of labor within the traditional industry district: Damyang bamboo ware industry district and Yeoju pottery industry district in South Korea, Damyang bamboo ware and Yeoju pottery are well known of the Korean traditional industry. The social division of labor in an industry district is considered as an important factor. The social division of labor helps the traditional industry to survive today. This summary shows five significant points from the major findings. First, Damyang bamoo ware industry and Yoeju pottery industry have experienced the growth stages until 1945, the stagnation in the 1960s, and the business recovery in the 1980s. Most Korean traditional industries had been radically declined under the Japanese colonization; while, Damyang bamboo ware industry and Yeoju pottery industry district have been developed during above all stages. The extended market to Japan helped the local government to establish a training center, and to provide financial aids and technical aids to crafts men. During the 1960s and 1970s, mass production of substitute goods on factory system resulted in the decrease of demand of bamboo ware and pettery. During the 1980s, these industries have slowly recovered as a result of the increased income per capita. The high rate of economic growth in the 1960s and 1970s was playing an important role in the emerging the incleased demand of the bamboo ware and pottery. Second the production-and-marketing system in a traditional industry district became diversified to adjust the demand of products. In Damyang bamboo ware industry district, the level of social division of labor was low until the high economic development period. Bamboo ware were made by a farmer in a small domestic system, The bamboo goods were mainly sold in the periodic market of bamboo ware in Damyang. In the recession period in the 1960s and 1970s, the production-and-marketing system were diversified; a manufacturing-wholesale type business and small-factory type business became established; and the wholesale business and the export traders in the district appeared. In the recovery period in the 1980s, the production-and-marketing systems were more diversified; a small-factory type business started to depend On subcontractors for a part of process of production; and a wholesale business in the district engaged in production of bamboo ware. In Yeoju pottery industry district, the social division of labor was limited until the early 1970s. A pottery was made by a crafts man in a small-business of domestic system and sold by a middle man out of Yeoju. Since the late 1970s, production-and-marketing system become being diversified as a result of the increased demand in Japan and South Korea. In the 1970s, Korean traditional craft pottery was highiy demanded in Japan. The demand encouraged people in Yoeju to become craftsmen and/or to work in the pottery related occupation. In South Korea, the rapid economic growth resulted in incline to pottery due to the development of stainless and plastic bowls and dishes. The production facilities were modernized to provide pottery at the reasonable price. A small-busineas of domestic system was transformed into a small-factory type business. The social division of labor was intensified in the pottery production-and-maketing system. The manufacturing kaoline began to be seperated from the production process of pottery. Within the district, a pottery wholesale business and a retail business started to be established in the 1980s. Third the traditional industry district was divided into "completed one" and "not-completed one" according to whether or not the district firms led the function of the social division of labor. The Damyang bamboo ware industry district is "completed one": the firm within the district is in charge of the supply of raw material, the production and the marketing. In the Damyang bamboo ware district, the social division of labor w and reorganized labor system to improve the external economics effect through intensifying the social division of labor. Lastly, the social division of labor was playing an important role in the development of traditional industry districts. The subdivision of production process and the diversification of business reduced the production cost and overcame the labor shortage through hiring low-waged workers such as family members, the old people and housewives. An enterpriser with small amount of capital easily joined into the business. The risk from business recession were dispersed. The accumulated know-how in the production and maketing provided flexiblility to produce various goods and to extend the life-cycly of a product.d the life-cycly of a product.
As business incubation centers (BICs) have been operating for more than 10 years in Korea, many early stage startups tend to use the services provided by the incubating centers. BICs in Korea have accumulated the knowledge and experience in the past ten years and their services have been considerably improved. The business incubating service has three facets : (1) business infrastructure service, (2) direct service, and (3) indirect service. The mission of BICs is to provide the early stage entrepreneurs with the incubating service in a limited period time to help them grow strong enough to survive the fierce competition after graduating from the incubation. However, the incubating services sometimes fail to foster the independence of new startup companies, and raise the dependence of many companies on BICs. Thus, the dependence on BICs is a very important factor to understand the survival of the incubated startup companies after graduation from BICs. The purpose of this study is to identify the main factors that influence the firm's dependence on BICs and to characterize the relationships among the identified factors. The business incubating service is a core construct of this study. It includes various activities and resources, such as offering the physical facilities, legal service, and connecting them with outside organizations. These services are extensive and take various forms. They are provided by BICs directly or indirectly. Past studies have identified various incubating services and classify them in different ways. Based on the past studies, we classify the business incubating service into three categories as mentioned above : (1) business infrastructure support, (2) direct support, and (3) networking support. The business infrastructure support is to provide the essential resources to start the business, such as physical facilities. The direct support is to offer the business resources available in the BICs, such as human, technical, and administrational resources. Finally, the indirect service was to support the resource in the outside of business incubation center. Dependence is generally defined as the degree to which a client firm needs the resources provided by the service provider in order to achieve its goals. Dependence is generated when a firm recognizes the benefits of interacting with its counterpart. Hence, the more positive outcomes a firm derives from its relationship with the partner, the more dependent on the partner the firm must inevitably become. In business incubating, as a resident firm is incubated in longer period, we can predict that her dependence on BICs would be stronger. In order to foster the independence of the incubated firms, BICs have to be able to manipulate the provision of their services to control the firms' dependence on BICs. Based on the above discussion, the research model for relationships between dependence and its affecting factors was developed. We surveyed the companies residing in BICs to test our research model. The instrument of our study was modified, in part, on the basis of previous relevant studies. For the purposes of testing reliability and validity, preliminary testing was conducted with firms that were residing in BICs and incubated by the BICs in the region of Gwangju and Jeonnam. The questionnaire was modified in accordance with the pre-test feedback. We mailed to all of the firms that had been incubated by the BICs with the help of business incubating managers of each BIC. The survey was conducted over a three week period. Gifts (of approximately ₩10,000 value) were offered to all actively participating respondents. The incubating period was reported by the business incubating managers, and it was transformed using natural logarithms. A total of 180 firms participated in the survey. However, we excluded 4 cases due to a lack of consistency using reversed items in the answers of the companies, and 176 cases were used for the analysis. We acknowledge that 176 samples may not be sufficient to conduct regression analyses with 5 research variables in our study. Each variable was measured through multiple items. We conducted an exploratory factor analysis to assess their unidimensionality. In an effort to test the construct validity of the instruments, a principal component factor analysis was conducted with Varimax rotation. The items correspond well to each singular factor, demonstrating a high degree of convergent validity. As the factor loadings for a variable (or factor) are higher than the factor loadings for the other variables, the instrument's discriminant validity is shown to be clear. Each factor was extracted as expected, which explained 70.97, 66.321, and 52.97 percent, respectively, of the total variance each with eigen values greater than 1.000. The internal consistency reliability of the variables was evaluated by computing Cronbach's alphas. The Cronbach's alpha values of the variables, which ranged from 0.717 to 0.950, were all securely over 0.700, which is satisfactory. The reliability and validity of the research variables are all, therefore, considered acceptable. The effects of dependence were assessed using a regression analysis. The Pearson correlations were calculated for the variables, measured by interval or ratio scales. Potential multicollinearity among the antecedents was evaluated prior to the multiple regression analysis, as some of the variables were significantly correlated with others (e.g., direct service and indirect service). Although several variables show the evidence of significant correlations, their tolerance values range between 0.334 and 0.613, thereby demonstrating that multicollinearity is not a likely threat to the parameter estimates. Checking some basic assumptions for the regression analyses, we decided to conduct multiple regression analyses and moderated regression analyses to test the given hypotheses. The results of the regression analyses indicate that the regression model is significant at p < 0.001 (F = 44.260), and that the predictors of the research model explain 42.6 percent of the total variance. Hypotheses 1, 2, and 3 address the relationships between the dependence of the incubated firms and the business incubating services. Business infrastructure service, direct service, and indirect service are all significantly related with dependence (β = 0.300, p < 0.001; β = 0.230, p < 0.001; β = 0.226, p < 0.001), thus supporting Hypotheses 1, 2, and 3. When the incubating period is the moderator and dependence is the dependent variable, the addition of the interaction terms with the antecedents to the regression equation yielded a significant increase in R2 (F change = 2.789, p < 0.05). In particular, direct service and indirect service exert different effects on dependence. Hence, the results support Hypotheses 5 and 6. This study provides several strategies and specific calls to action for BICs, based on our empirical findings. Business infrastructure service has more effect on the firm's dependence than the other two services. The introduction of an additional high charge rate for a graduated but allowed to stay in the BIC is a basic and legitimate condition for the BIC to control the firm's dependence. We detected the differential effects of direct and indirect services on the firm's dependence. The firms with long incubating period are more sensitive to indirect service positively, and more sensitive to direct service negatively, when assessing their levels of dependence. This implies that BICs must develop a strategy on the basis of a firm's incubating period. Last but not least, it would be valuable to discover other important variables that influence the firm's dependence in the future studies. Moreover, future studies to explain the independence of startup companies in BICs would also be valuable.