• Journal of the Korean Association of Geographic Information Studies
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• v.24 no.3
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• pp.58-72
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• 2021

In July 2021, UNCTAD classified Korea as a developed country. After the Korean War in the 1950s, economic development was promoted despite difficult conditions, resulting in epoch-making national growth. However, in order to respond to the rapidly changing global economy, it is necessary to continuously study the domestic industrial ecosystem and prepare strategies for continuous change and growth. This study analyzed the industrial ecosystem of the automobile industry where it is possible to obtain transaction data between companies by applying complexity spatial network analysis. For data, 295 corporate data(node data) and 607 transaction data (link data) were used. As a result of checking the spatial distribution by geocoding the address of the company, the automobile industry-related companies were concentrated in the Seoul metropolitan area and the Southeastern(Dongnam) region. The node importance was measured through degree centrality, betweenness centrality, closeness centrality, and eigenvector centrality, and the network structure was confirmed by identifying density, distance, community detection, and assortativity and disassortivity. As a result, among the automakers, Hyundai Motor, Kia Motors, and GM Korea were included in the top 15 in 4 indicators of node centrality. In terms of company location, companies located in the Seoul metropolitan area were included in the top 15. In terms of company size, most of the large companies with more than 1,000 employees were included in the top 15 for degree centrality and betweenness centrality. Regarding closeness centrality and eigenvector centrality, most of the companies with 500 or less employees were included in the top 15, except for automakers. In the structure of the network, the density was 0.01390522 and the average distance was 3.422481. As a result of community detection using the fast greedy algorithm, 11 communities were finally derived.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.12 no.2
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• pp.162-169
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• 2019

Non-destructive freshness measurement using spectroscopy has been carried out several times, but research on freshness and freshness has not been conducted. Therefore the purpose of this study is to develop a system for visually measuring and quantifying the air sack inside the egg by non - destructive method. The experimental environment which designed a small chamber was composed of 850nm band of two IR lasers, IR camera and two servo motors to acquire air sack Images. When the air sack volume ratio is 2.9% or less and the density is 0.9800 or more, the Haugh Unit value is 60 or more It was judged to be a fresh egg of a grade B or higher. These results mean, using the weight measurement, nondestructive decision system, and freshness evaluating algorithm. It can be expected to distinguish grade B or more marketable eggs without using destructive methods.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.3
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• pp.455-464
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• 2019

The sensorless control based on the flux linkage of PM synchronous motors has excellent position estimation characteristics at low speeds. However, a limitation arises because the integrator of flux estimator is saturated by the DC offset generated during the analog to digital conversion(ADC) process of the measured current. In order to overcome this limitation, HPF with a low cutoff frequency is used. However, the estimation performance is deteriorated (Ed- the verb deteriorate already includes the meaning of 'problem') at high speed due to the low cutoff frequency, and increasing the cutoff frequency of the HPF induces further problems of phase leading and initial starting failure at low speeds. In this paper, the cutoff frequency of HPF was synchronized to the operation frequency of the motor: at low speeds the cutoff frequency was set to low in order to reduce the phase leading of the estimated flux, and at high speeds it was set to high to raise the DC offset removal performance. As a result, the operating range was increased by 200%. Furthermore, a phase compensation algorithm is proposed to reduce the phase leading of the HPF to less than 1.5 degrees over the full operating range. The proposed sensorless control algorithm was verified by experiment with a PM synchronous motor for a washing machine.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.6
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• pp.74-79
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• 2019

The military vehicle produces electric power through an engine-integrated serial hybrid generator that is connected to the engine and does not have a separate generator installation space. However, depending on the mechanical characteristics of the connection between the generator and the engine, iron oxide for internal rusting and lubrication grew scattered. The iron oxide is adhered to the starter to deteriorate the starting performance, and there is a problem that the noise of the leg due to wear of the gear is increased. To solve this problem, the connection spline material and the surface treatment of the engine were improved and the shape was changed to a grease sealing type to prevent the generation of iron oxide inside. As the shape of the generator connector composing the shafting system was changed, the integrity of the structure was confirmed through the torsional endurance test. In addition, through the actual vehicle load test, it was verified that no corrosion occurred during the target life span without internal corrosion. It was confirmed that the anti-scattering structure of the grease effectively suppresses the generation of iron oxide, thereby reducing the noise generated from the generator. In this paper, we propose a fundamental solution to the degradation of the starter and the noise generation by preventing the back corrosion caused by the serial hybrid generator installed between the engine and the transmission.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.4
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• pp.35-42
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• 2019

Nut fasteners that require ultra-precise control are required in the overall manufacturing industry including electronic products that are currently developing with the automobile industry. Important performance factors when tightening nuts include loosening due to insufficient fastening force, breakage due to excessive fastening, Tightening torque and angle are required to maintain and improve the assembling quality and ensure the life of the product. Nut fasteners, which are now marketed under the name Nut Runner, require high torque and precision torque control, precision angle control, and high speed operation for increased production, and are required for sophisticated torque control dedicated to high output BLDC motors and nut fasteners. It is demanded to develop a high-precision torque control driver and a high-speed, low-speed, high-response precision speed control system, but it does not satisfy the high precision, high torque and high speed operation characteristics required by customers. Therefore, in this paper, we propose a control technique of BLDC motor variable speed control and nut runner based on vector control and torque control based on coordinate transformation of d axis and q axis that can realize low vibration and low noise even at accurate tightening torque and high speed rotation. The performance results were analyzed to confirm that the proposed control satisfies the nut runner performance. In addition, it is confirmed that the pattern is programmed by One-Stage operation clamping method and it is tightened to the target torque exactly after 10,000 [rpm] high speed operation. The problem of tightening torque detection by torque ripple is also solved by using disturbance observer Respectively.

• Journal of the Economic Geographical Society of Korea
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• v.22 no.2
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• pp.160-177
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• 2019

In this study, we examined the distribution of dealers and the repair parts management system of a Japanese car manufacturer in the Chinese market in looking at the case of Toyota. We conducted our research by obtaining information from a GAC Toyota dealer about the current distribution of dealers and locations of warehouses throughout China, as well as the status of stocks and the distribution system for repair and maintenance parts. The results of our investigation showed that although GAC Toyota has 437 dealers throughout the country, there is an imbalance in distribution towards the coastal areas, after the population ratios and other measurements are factored in. Therefore, it can be said expansion towards the inland regions, where demand for automobiles has increased in recent years, has been stunted. On the other hand, there is a high correlation between gross GDP by region and the number of stores, and it can be pointed out that the company prioritizes the sale of high-priced vehicles in major coastal areas where the economy is large, rather than selling low-priced vehicles for inland consumers with a relatively small economic scale. The company also has difficulty in securing dealers that can provide sufficient after-sales service. According to the regulations of GAC Toyota, the company require dealers to have at least 1,500 repair and maintenance parts in stock. Also, when exchanging maintenance parts, GAC Toyota's emphasis is on increasing customer satisfaction by giving sufficient explanations for customers and obtaining consent from them. As a result, the company's dealers need financial resources to continue their business from a long-term perspective. However, it can be pointed out that such dealers are limited, and it is difficult to distribute profits among manufacturers and dealers.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.16 no.5
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• pp.189-203
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• 2021

Environmental changes, which are strongly requiring technological cooperation, such as technological development and strategic alliances according to industrial ecosystem change, have a significant impact on not only product quality but also services. Thus, there is a need for 'servitization' that can satisfy the needs of customers and the ecosystem of businesses through the convergence of manufacturing companies and services. This study uses the Expectation-Confirmation Model to examine the impact on user satisfaction and Continuance Usage Intention. Research(Study) was conducted on users who are using high-tech-based cars. For this, we used Expectation Confirmation(match expections for the user's pre-and post-use relationships), Perceived Ease, Perceived Usefulness, User Satisfaction and Habitual Use and using Continuance Usage Intention as a dependent variable. Their causation was examined with the spss 26.0 and smartpls 2.0 statistical programs. As implications of this study, Expectation Confirmation has been shown to have significant positive effects on Perceived Ease, Perceived Usefulness, User Satisfaction and Habitual Use. For this results, the expectations before and after the use of high-tech cars lead to improved daily lives convenience and(or) work efficiency, leading to user satisfaction and further Continuance Usage Intention. Motors consider it important to pursue the work improvements that consumers want and use it useful in daily lives in the production and sale of high-tech cars. It is expected that it will create natural habits for services that users are satisfied with, and that these habits will affect the continuous growth and understanding of the trend of change.

• Korean Chemical Engineering Research
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• v.59 no.4
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• pp.521-531
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• 2021

Vacuum Pressure Impregnation (VPI) is a process that enhances physical properties by coating some types of epoxy resins on windings of stator used in large rotators such as generators and motors. During vacuum and pressurization of the VPI process, resin gas is generated by vaporization of epoxy resin. When the tank is opened for curing after finishing impregnation, resin gas is leaked out of the tank. If the leaked resin gas spreads throughout the workplace, there are safety and environmental problems such as fire, explosion and respiratory problems. So, exhaust system for resin gas is required during the process. In this study, a case study of exhaust efficiency by location of vent was conducted using Computational Fluid Dynamics (CFD) in order to design a system for exhausting resin gas generated by the VPI process. The optimal exhaust system of this study allowed more than 90% of resin gas to be exhausted within 1,800 seconds and reduced the fraction of resin gas below the Low Explosive Limit (LEL).

• Journal of Internet of Things and Convergence
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• v.8 no.6
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• pp.55-63
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• 2022

In recent years, with the rapid development of large and medium-sized urban rail transit in China, the total operating mileage of high-speed railway and the total number of EMUs(Electric Multiple Units) are rising. The system complexity of high-speed EMU is constantly increasing, which puts forward higher requirements for the safety of equipment and the efficiency of maintenance.At present, the maintenance mode of high-speed EMU in China still adopts the post maintenance method based on planned maintenance and fault maintenance, which leads to insufficient or excessive maintenance, reduces the efficiency of equipment fault handling, and increases the maintenance cost. Based on the intelligent operation and maintenance technology of PHM(prognostics and health management). This thesis builds an integrated PHM platform of "vehicle system-communication system-ground system" by integrating multi-source heterogeneous data of different scenarios of high-speed EMU, and combines the equipment fault mechanism with artificial intelligence algorithms to build a fault prediction model for traction motors of high-speed EMU.Reliable fault prediction and accurate maintenance shall be carried out in advance to ensure safe and efficient operation of high-speed EMU.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.12
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• pp.688-701
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• 2020

This study analyzes the characteristics and change factors of technological cooperation networks in the automotive industry. Using Social Network Analysis (SNA) of 112,009 autonomous driving-related patents filed from 2000 to 2017 by major automotive firms in the world, we investigate the structure of the technological cooperation network. Network characteristics such as density are analyzed through structural characteristic analysis among the network analysis indicators. The structural characteristics of the technology cooperation network are confirmed through analysis of status characteristic indicators, such as the degree of centrality, betweenness centrality, and closeness centrality. Results show that car makers such as Toyota and Hyundai Motors, as well as parts suppliers such as Bosch and Continental, have high-performance technology developments related to autonomous driving. The structural characteristics of the network show that companies participating in cooperative networks for autonomous driving technology development have increased in number and are diversified, and all of the status characteristics indicators have decreased. This can be interpreted as an increasing number of horizontal and complementary forms of technological cooperation between firms. In addition, it was confirmed that the number of participants in the field of autonomous driving technology has increased, and the networks have become more complex.