• Management Science and Financial Engineering
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• v.18 no.1
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• pp.13-20
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• 2012

This paper considers a revenue maximization problem on a single processor. Each job is identified as its processing time, initial reward, reward decreasing rate, and preferred start time. If the processor starts a job at time zero, revenue of the job is its initial reward. However, the revenue decreases linearly with the reward decreasing rate according to its processing start time till its preferred start time and finally its revenue is zero if it is started the processing after the preferred time. Our objective is to find the optimal sequence which maximizes the total revenue. For the problem, we characterize the optimal solution properties and prove the NP-hardness. Based upon the characterization, we develop a branch-and-bound algorithm for the optimal sequence and suggest five heuristic algorithms for efficient solutions. The numerical tests show that the characterized properties are useful for effective and efficient algorithms.

• Journal of the Korean Society of Propulsion Engineers
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• v.20 no.3
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• pp.1-8
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• 2016

It was examined that start-up characteristics of a staged combustion cycle engine powerpack. Among various parameters, valve opening time was considered as a main factor affecting the start-up characteristics. Using monte-carlo method, characteristics variation was analyzed when the valve opening time deviates from the nominal value. As a result, the main fuel valve opening time and the start turbine ending time were significant associated with the startup characteristics. When separating main fuel valve opening time and start turbine stop time, main fuel valve opening time was an important factor. For stable operation, the main fuel valve opening time must be set one second before after driving the start turbine. Likewise, it was confirmed that the startup analysis can suggest an appropriate startup sequence for a stable startup.

• Journal of East Asia Management
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• v.3 no.2
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• pp.65-82
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• 2022

The purpose of this study is to analyze the effects of start-up risks on university students's entrepreneurial intention. In particular, the start-up risk considers the recent ongoing Covid_19 Pandemic along with the level of awareness of the start-up risk of business administration university students. For this purpose, a total of 204 questionnaires collected for two months from October to November in 2020 were used to verify this relevance empirically through multiple regression analysis. The empirical analysis results are as follows. First, the level of students' awareness of start-up risks has no statistically significant relevance to their entrepreneurial intention, but the higher the level of negative perception of Covid_19 Pandemic, the lower the entrepreneurial intention. On the other hand, additional analysis showed that the students with low self-efficacy majoring in business administration, it was found that negative perceptions of start-up risk had a negative effect on start-up willingness. This study is timely and different from previous studies in that it empirically verified the effect of start-up risk on business administration university students' entrepreneurial intention at a time when negative perceptions of start-up risk increase and COVID_19 Pandemic make it increasingly difficult to start a business administration universit student.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.15 no.5
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• pp.65-76
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• 2020

This study analyzed the impact of women's self-preservation on their intention to start a business by using self-efficacy as a mediation, reflecting the importance of women's self-preservation to adapt to the new environment of start-up. In particular, in addition to the overall self-preservation, the sub-factors of behavioral delay, compensatory natural strategy, and constructive thinking strategy were also validated. As a research method, 198 people who responded to the online survey were analyzed using Model 4 of the PROCESS macro proposed by Hayes(2018), and indirect effects were analyzed by designating 5,000 bootstrapping samples. The findings were as follows. First, self-efficacy has been shown to have a mediating effect in which women's self-preservation influences their intention to start a business. At this time, the medium effect was shown as a partial medium. Second, the sense of self-efficacy was found to have a mediating effect on women's behavior-oriented strategies affecting their intention to start a business. At this time, the medium effect was shown as a partial medium. Third, self-efficacy was found to have a mediating effect in which women's natural compensatory strategies affect their intention to start a business. At this time, the medium effect was shown as a partial medium. Fourth, self-efficacy was found to have a mediating effect in which women's constructive thinking strategies affect their intention to start a business. At this time, the medium effect was shown as a complete medium. This shows that the higher a woman's self-preservation, the higher her self-efficacy and willingness to start a business. Based on the results of these studies, he made a developed proposal for women's start-ups.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.869-873
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• 2008

Optimization method for the open loop commutation time intervals in HDD spindle start-up control is presented in this paper. A hard disk drive(HDD) uses a sensorless brushless DC motor(BLDC) for the platter rotation. Because there is no direct sensor for the rotor position, open loop commutations after sensing the rotor position at a standstill using inductive sensing method are performed to speed up the rotor up to a certain speed where the zero crossings of the back electromotive force(EMF) are measurable. Therefore successful open loop commutations are necessary for the stable start-up control of the spindle motors. Random neighborhood search(RNS) algorithm is introduced as a optimization technic in this paper. Rotor speed and its standard deviation are used as a cost function and commutation intervals obtained from the spindle motion equation are used as initial parameter values for the RNS. With the help of the proposed method optimized open loop commutation time intervals for the very low start-up current are acquired and tested. The experimental results shows that the proposed method can decrease the start-up failure rate of a HDD spindle motor.

• World Technopolis Review
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• v.6 no.1
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• pp.4.1-4.15
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• 2017

In 1995, the Republic of Korea started to establish Techno Park (TP) in order to develop the regional industry while promoting the balanced development of the land. By 2008, 18TPs were established nationwide and have become cradles for developing local industries. And recently evolved forms of TP such as Daedeok Techno Valley and Pangyo Techno Valley emerged. In addition, 19 Centers for Creative Economy and Innovation (CCEI) were established nationwide and Tech-Incubator Program for start-ups (TIPS) was introduced to support and mentor start-ups. TPs in Korea become bureaucratic in course of time, and the new trial of innovation of TP is needed. In Korea, professional TIPS-accelerators mentoring and investing start-ups have a history of only five years. But they support and mentor start-ups efficiently, and have obtained good results. In this paper, we propose that TP attract TIPS-accelerators actively and collaborate with each other to support and mentor start-ups and SMEs effectively.

• Asian Journal of Innovation and Policy
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• v.7 no.3
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• pp.489-510
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• 2018

Institution-based Technology Business Incubators are on the rise in India, as a means of promoting innovation-based tech start-up ecosystems, due to increased policy initiatives. Against this background, we have traced the origin and process of building a start-up ecosystem in IIT Madras, Chennai of India, based on semistructured interviews held with the stakeholders of the ecosystem. Subsequently, we have ascertained the key components of IIT Madras start-up ecosystem, and the process of incubation comprising pre-incubation, incubation and post-incubation phases. Finally, we have derived the key lessons from the ecosystem development experience and incubation process which enable generation of start-ups from both students and faculty, apart from alumni and ex-industry executives. Though this ecosystem model has emerged over a period of time through learning and experience, the ecosystem is able to generate more than 100 start-ups, majority of them being from students and faculty. Thus, the evolved start-up ecosystem of IIT Madras is able to generate faculty-supported and student-led entrepreneurship successfully.

• The KIPS Transactions:PartD
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• v.8D no.6
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• pp.813-822
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• 2001

In this paper we proposed four data migration methods based on time segmented storage structure including past segment, current segment, and future segment. The migration methods proposed in this paper are the Time Granularity migration method, the LST-GET (Least valid Start Time-Greatest valid End Time) migration method, the AST-AET (Average valid Start Time-Average valid End Time) migration method, and the Min-Overlap migration method. In the each data migration method we define the dividing criterion among segments and entity versions to store on each segment. We measured the response time of queries for the proposed migration methods. When there are no LLTs (Long Lived Tuples), the average response time of AST-AET migration method and LST-GET migration method are smaller than that of Time Granularity migration method. In case of existing LLT, the performance of the LST-GET migration method decreased. The AST-AET migration method resulted in better performance for queries than the Time Granularity migration method and the LST-GET migration method. The Min-Overlap migration method resulted in the almost equal performance for queries compared with the AST-AET migration method, in case of storage utilization more efficient than the AST-AET.

• 대한공업교육학회지
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• v.32 no.2
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• pp.199-216
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• 2007

Stream Control Transmission Protocol(SCTP) is a transport layer protocol to support the data transmission. SCTP is similar to Transmission Control Protocol(TCP) in a variety of aspects. However, several features of SCTP including multi-homing and multi-streaming incur the performance difference from TCP. This paper highlights the data transfer during the initial slow start phase in SCTP congestion control composed of slow start phase and congestion avoidance phase. In order to compare the mean transfer time between SCTP and TCP, we experiment with different performance parameters including bandwidth, round trip time, and data length. By varying data length, we also measure the corresponding initial window size, which is one of factors affecting the mean transfer time. For the experiment, we have written server and client applications by C language using SCTP socket API and have measured the transfer time by ethereal program. We transferred data between client and server using round-robin method. Analysis of these experimental results from the testbed implementation shows that larger initial window size of SCTP than that of TCP brings the reduction in the mean transfer time of SCTP compared with TCP by 15 % on average during the initial slow start phase.

• Journal of IKEEE
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• v.18 no.2
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• pp.185-191
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• 2014

In this paper, we have implemented the low temperature fluidity test system with the composited package fuel heater, which has tested the low temperature fluidity and start time to evaluate the performance. Then we have compared the separation and the unified fuel heater type at $+20{\sim}-30^{\circ}C$. Also, we have tested the flowing pressure and start time, power consumption of heater. By comparing the performance with several condition, the experimental results obtain an improved start time of 23% and low temperature fluidity of 19%.