• Transactions of the Korean Society of Mechanical Engineers
• /
• v.14 no.6
• /
• pp.1583-1591
• /
• 1990

Life prediction and residual life prediction of structures of machines are one of the most strongly world wide needed problems as requirement in the stage of slowly developing economy which comes after rapidly and highly developing stage. For the purpose of statistical life prediction, fatigue test was conducted under the 4 stress levels, and for each stress level, about 20 specimens are used. The statistical properties of crack growth parameter m and C in the fatigue crack growth law of da/dN=C(.DELTA.K)sup m/, and the relationship between m and C, and the statistical distribution pattern of fatigue crack growth rate can be obtained by experimental results.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.17 no.5
• /
• pp.165-171
• /
• 2017

Reading Pen is used mostly in educational purpose, yet its possibility is great as an input device for various IT devices. Reading Pen recognizes tiny dot patterns printed in papers, converts the patterns to corresponding codes, and plays audio contents that match the codes. Recognizing dot patterns and converting to the codes are the main function of Reading Pens, on which we focus and propose a novel algorithm. Such technology is never open to public and this paper is the first open attempt in this area. We test the algorithm and obtain 85% recognition ratio.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.16 no.6
• /
• pp.32-40
• /
• 2012

For predicting eigenfrequency and initial growth rate of combustion instabilities in lean premixed gas turbine combustor, linear thermoacoustic analysis model was developed in the current paper. A model combustor was selected for the model validation, which has well-defined inlet and outlet conditions and a relatively simple geometry, compared to the combustor in the previous works. Analytical linear equations for thermoacoustic waves were derived for a given combustion system. It was found that the prediction results showed a good agreement with the measurements, even though there was underestimation for instability frequencies. This underestimation was more obvious for a longer flame (i.e. wider temperature distribution) than for a shorter flame.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• v.29 no.1
• /
• pp.423-428
• /
• 2005

Due to the fast growing rate of the global container trade, every major port is under the pressure of meeting the projected capacity demand. As a result, alternative solutions have been sought for improving capacity and meeting the growing demand for container storage area and terminal capacity. Moreover, material handling process re-engineering is now a critical issue for logistics and supply chain managers of airline, shipping lines, terminal and warehousing enterprises around the world. Therefore, the purpose of this paper is to develop the 3D simulator for executing performance valuation of port transportation systems. The developed 3D simulator system is to measure the effectiveness of the proposed total system and compare it with existing practices. The performance analysis variables are also defined for these comparisons.

• The Journal of the Korea Contents Association
• /
• v.19 no.12
• /
• pp.229-237
• /
• 2019

Though start-ups by small businessmen are increasing year by year, the success rate of start-ups have been low. Accordingly, it is necessary to look at various ways to improve the success rate of start-ups by small businessmen. Most previous studies on the issue have focused on identifying influential factors that lead to the success and growth of start-ups by them, mostly based upon quantitative perspectives. Few has approaced with qualitative perspective such as actual case studies in academic papers. In this study, after analyzing a wide range of successful cases of start-ups by small businessmen, we will develop countermeasures by business types and suggest practical lessons that can be appropriately utilized in starting a new small business.

• The Journal of the Korea Contents Association
• /
• v.17 no.9
• /
• pp.523-535
• /
• 2017

Despite consumers' increasing awareness and interests in innovative wearable devices, the sales growth has been stagnant. To analyze this phenomenon, we investigate consumer preferences for various innovative features embedded in wearable devices. Conducting conjoint analysis on smartwatches, we empirically show that the curse of innovation can occur when the consumer's expected utility from the smartwatch falls short of his/her psychological cost associated with behavior change from smartwatch usage. Therefore, our findings provide managerial implications on the R&D strategy for new technologies and more importantly on the marketing strategy easing consumers' resistance to highly innovative products.

• Research in Plant Disease
• /
• v.26 no.4
• /
• pp.202-209
• /
• 2020

Organic farming is necessary to sustainable agriculture, preserve biodiversity and continued growth the sector in agriculture. In organic farming, reduced usage of chemical agents that adversely affect human health and environment, employing amino acids and oil cake fertilizer, plant extracts, and microbial agents are used to provide safe agricultural products to consumers. To investigation microbiome structure, we proceeded on the pepper plant with difference fertilizers and treatments in organic agriculture for three years. The microbial communities were analyzed by the next generation sequencing approach. Difference soil microbiota communities were discovered base on organic fertilizer agents. Occurrences of virus and anthracnose diseases had a low incidence in conventional farming, whereas bacteria wilt disease had a low incidence in microbial agents treated plots. Microbe agents, which applied in soil, were detected in the microbial community and the funding suggested the applied microbes successfully colonized in the organic farming environment.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.15 no.6
• /
• pp.98-106
• /
• 2011

This paper reviews the state-of-the-art thermoacoustic(TA) modeling techniques and research trend to predict major parameters determining combustion instabilities in lean premixed gas turbine combustors. Linear TA modeling results give us an information on eigenfrequencies and initial growth rate of the instabilities. For the prediction, linear relation equation between acoustic waves and heat release oscillations should be derived in the determined system. Key information for this analysis is to determine the heat release fluctuations in the combustor, which is typically obtained by using n-${\tau}$ function from flame transfer function measurements and/or predictions. Great advancement in the linear TA modeling has been made over a couple of decades, and some successful prediction results have been reported in actual gas turbine combustors. However nonlinear TA model developments which are required to analyze nonlinear system behaviors such as limit cycle saturation and transition phenomena are still limited in a very simple system. In order to fully understand combustion instabilities in a complicated real system, nonlinear flame dynamics and acoustic wave interaction with nonlinear system boundary conditions should be explained from the nonlinear TA model developments.

• Journal of Internet of Things and Convergence
• /
• v.8 no.1
• /
• pp.65-72
• /
• 2022

The Internet of Things (IoT) provides data convergence and sharing functions, and IoT technology is the most fundamental core technology in creating new services by convergence of various cutting-edge technologies. However, there are different classification systems for the Internet of Things, and when it is limited to the domestic public sector, it is difficult to properly grasp the current status of which devices are installed and operated with what share, and systematic data or research The results are very difficult to find. Therefore, in this study, the relevance of the classification system for IoT devices was analyzed according to reality based on sales, shipments, and growth rate, and based on this, the actual share of IoT devices among domestic public institutions was analyzed in detail. The derived detailed analysis results are expected to be efficiently utilized in the process of selecting IoT devices for research and analysis to advance information protection technology such as responding to malicious code attacks on IoT devices, analyzing incidents, and strengthening security vulnerabilities.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
• /
• v.17 no.3
• /
• pp.19-31
• /
• 2022

Currently, the role of public accelerators in the domestic accelerator market is gradually expanding. Accordingly, in order to establish relevant policies properly, it is necessary to check the effect and validity of public accelerators' investment. However, there is no quantitative research conducted on domestic accelerators, using their financial data, as domestic accelerators have a short history and quantitative data on them are not disclosed. Therefore, this study conducted an empirical analysis with financial data of the startups that received equity investments from public accelerators to confirm the effect of public accelerators'investment in startups. A regression analysis was conducted with financial data from 112 startups that acquired investments from public accelerators in the period of 2016~2020. And the findings are as follows: First, it was found that the initial investment of public accelerators had an effect on the growth and profitability of startups. Specifically, it was confirmed that the initial investment of public accelerators had a positive (+) effect on sales growth rates and total asset growth rates, which are growth indicators. Second, it was found that the joint investment of public accelerators had a significant positive (+) effect on profit margin, an indicator of profitability, rather than on growth. Therefore, it is deemed that it will be a great force for growth if investment in the early-stage startups that showed significant investment results in this study is continuously expanded in combination with support projects, which are a strength of public accelerators. Since this study has confirmed the investment effect of public accelerators, it is deemed necessary to actively promote policies that direct public accelerators' projects toward improving the performance of startups through joint investment with the private sector and supplementing private accelerators' deficiencies.