• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2536-2539
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• 2008

A study has been made on how to occur inertial oscillations in a rotating flow. The flow is considered to be induced by differentially-rotating top and bottom disks with infinite radius. The top and bottom disks are assumed to be set in motion over a finite initial start-up time duration from initial solid body rotation ($\Omega$) to each finial state, i.e., the top disk is rotating at the angular velocity (${\Omega}+{\Delta}{\Omega}$) and the bottom disk (${\Omega}-{\Delta}{\Omega}$). The system Reynolds number, which is a reciprocal of conventional Ekman number in rotating flows, is very high so that a boundary layer flow near disks is pronounced. From a strict theoretical analysis, it is clearly found the fact that inertial oscillation in a rotating flow is caused by excessive input of torque during start-up phase. Above finding comes from the following physics of theoretical result: in the case of abrupt start-up within very shorter time-duration than spin-up time scale, the inertial oscillation is magnified but it could be completely depressed in the case of mildly accelerated start-up, i.e., start-up process being established over diffusion time scale.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.8
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• pp.228-234
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• 2020

The number of collaboration professors has significantly increased since the last decade, along with rapid technological developments and the necessity of entrepreneurial universities. Despite the expansion of collaboration professor recruitment, few empirical studies have examined the contribution of collaboration professors to university-industry collaboration. In particular, we do not have sufficient knowledge about the role of collaboration professors in the start-ups of undergraduate students, which is one of major duties of these professors. Following previous studies, this study constructs panel data of 203 universities explaining the proportions of collaboration professors, activities of undergraduate students, support of universities for students preparing new firms, and attributes of universities from 2017 to 2019. The results indicate that the percentage of collaboration professors is not statistically related with the start-ups of undergraduate students, whereas that of full-time professors working at organizations specializing in start-ups is positively and significantly associated with the number of new firms of undergraduate students. In addition, the percentage of students who had attended the start-up camps and the availability of financial support from universities for students who attempt to create new firms positively influence the start-ups of undergraduate students.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.601-605
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• 1991

In this paper an approximate solution method for the large-scale Traveling Salesman Problem(TSP) is presented. The method start with the subdivision of the problem domain into a number of clusters by considering their geometries. The clusters have limited number of nodes so as to get local solutions. They are linked to give the least path which covers the whole domain and become TSPs with start- and end-node. The approximate local solutions in each cluster are obtained by using geometrical property of the cluster, and combined to give an overall-approximate solution for the large-scale TSP.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.1
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• pp.103-107
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• 2016

In general, the voltage stability of induction generator is lower than synchronous generator. Induction generator has a number of advantages over the synchronous generator on the side of price and maintenance. So Induction generator has been applied to the small hydroelectric power of low output. Induction generator usually generates a high current during grid connection. The high current that occurs during grid connection can cause a voltage drop in the system. In order to increase the supply of the induction generator, it is necessary to propose a method of reducing high current. This paper proposes some method of the soft start to reduce voltage drop caused by the large starting current. soft-start method has high voltage drop effect than direct start method, control of firing angle can be increased the voltage drop effect.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.1128-1131
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• 1996

The collision-free path planning presented here uses linear parametric curve with one intermediate connection point between start and target points. The algorithm, in which connection point is organized in elliptic chord.(.theta., .delta.), maps objects in Euclidean Space into images in CPS through intersection check between path and obstacles a process defined as GM. Elliptic locus has special property that the total distance between focus points through a point on ellipse is the same regardless of .theta.. Hence by locating the start and target points to focus points of ellipse, and organizing connection point in elliptic coordinate, the .delta.-axis of CPS represents length of path. The GM of EWS requires calculation of interference in circumferential direction only. The procedures for GM is developed which include categorization of obstacles to reduce calculation amount. Simulations of GM of EWS, on a PC with Pentium/90MHz, is carried out to measure performance of algorithm and the results are reported on a table. The simulations are done for number of cases with different number of obstacles and location of start/target points.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.6
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• pp.744-752
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• 1999

Particle contamination in a hard disk drive has been recognized as an important issue because particles can significantly affect the reliability of the drive. In this study, characteristics of the particle generation in a hard disk drive during the start/stop period were investigated. The number of particles generated in the drive was measured at 5 locations by using condensation nucleus counters(CNC) with sampling probes. It was found that most of particles were generated whenever the drive started or stopped. The number of particles detected by the condensation nucleus counter depended on sampling parameters including sampling location, shape of sampling probe, and sampling velocity.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.4
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• pp.840-848
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• 2009

This paper proposes a new multi-start scheme that generates guided random bits in selecting initial search points for global optimization with univariate dynamic encoding algorithm for searches (uDEAS). The proposed method counts the number of 1 in each bit position from all the previously generated initial search matrices and, based on this information, generates 0 in proportion with the probability of selecting 1. This rule is simple and effective for improving diversity of initial search points. The performance improvement of the proposed multi-start is validated through implementation in uDEAS and function optimization experiments.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.18 no.10
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• pp.1065-1072
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• 2008

A HDD adopts a sensorless brushless DC (BLDC) motor as a spindle motor. Because there is no direct sensor measuring rotor position. open loop commutations with inductive sensing are used to increase the rotor speed up to a certain speed where the zero crossings of the back electromotive force (EMF) voltage are measurable. Therefore, successful open loop commutations are necessary for the stable start-up control of the spindle motors. In this paper, the time scale and the number of the open loop commutations are employed for design parameters to guarantee robustness to torque constant variation and initial rotor position. The design results are verified by experiments on a very low current start-up of the spindle motor with various environment. The experimental results show that the design results can decrease the start-up failure rate considerably.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.14 no.1
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• pp.73-83
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• 2019

As the awareness of the importance of Start-up increases, the number of entrepreneurs who decide to start their career is gradually increasing. However, the rate of start-up failure is still high and the qualitative level is very low due to lack of start-up performance. In this study, we analyzed the effect of entrepreneurship capability and start-up support system on start-up performance. To that end, 361 valid data were collected from businesses that were established less than seven years ago in Jeollabuk-do on August 1, 2018 and used for study verification through SPSS 21 and AMOS 21. First, the entrepreneurial competence (entrepreneurial competence, managerial competency) has a positive effect on the start-up support system and the technical competency has no significant effect. Second, entrepreneurial competence (entrepreneurial competence, managerial competency, technical competency) has a significant effect on entrepreneurial performance. However, entrepreneurial competence has a meaningful effect on the start-up performance of entrepreneurs with a negative (-) effect. Third, it was found that the start - up support system had a positive effect on the start - up performance. Finally, the start - up support system proved to have mediating effect between entrepreneurial competence and start - up performance. The implications of this study are as follows. In order to increase the start-up performance of the start-up companies, it is proved that increasing the capacity of the start-ups is an important factor. In addition, empirical studies have proved that the use of start-up support system is an important factor that directly or indirectly has a significant effect on start-up performance, We have made meaningful implications that actively supporting and utilizing entrepreneurship is necessary to enhance start-up performance.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.16 no.2
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• pp.153-161
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• 2021

This study analyzed the ripple effect of the demand-side support for start-up venture companies on the macro economy using Dynamic General Equilibrium model. In the model, start-up venture companies were expressed in a manner that distinguished between workers and entrepreneurs by applying the span of control in the Lucas(1978). As a result of the analysis, when the share of public procurement of start-up venture companies was increased from 5.7% to 10%, the actual production of start-up venture companies increased by about 46.17% and the number of venture companies increased by about 150%. In addition, it was analyzed that the number of jobs through venture companies increased by about 61.56%. In addition, it was found that the economic effect was greatly reduced when the start-up venture company was supported as a subsidy for the supply sector with the same amount as the public procurement support. This is interpreted as the fact that if the government implements the supply-side support policy, the expansion of supply causes the price of start-up venture companies to fall, reducing the effect of the support policy in half. Therefore, when supporting start-up venture companies, the government should make efforts to maximize the policy effect by expanding the demand-side support through public procurement and reducing the payment of simple subsidies to start-up venture companies.