• Transactions on Control, Automation and Systems Engineering
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• v.1 no.2
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• pp.141-146
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• 1999

This paper describes the communication method of an auto-startup system. The Auto-Startup system is designed to operate a nuclear power plant automatically during the startup operation . In general , the operations during startup in existing plant have only been manually controlled by the operator. The manual operation caused to the operator mistake. The Auto-Startup system consists of the Distributed Control System(DCS) and G2 (Expert System). Also, Functional Test Facility(FTF) provides the plant's real-data for an Auto-Startup system. So, it is necessary to develop the communication method between these systems. We developed two methods ; one is a network and the other is a hardwire line. To communicate between these systems (DCS-G2 and DCS-FTF) , we developed the communication program. In case of DCS-FTF, we used the TCP/IP and VXI. BUt, in case of DCS-G2 , we , what it called , developed the bridge program using the GSI(G2 Standard Interface). We test to check the function of the important parameter, in time, for analysis of the developed communication method. The results are a good performance when we check the communication time of important parameter. We conclude that Auto-startup system could save heat-up time about at least 5 hours and reduced the change of the reactor operation and trip.

• 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 the Korean Society of Propulsion Engineers
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• v.19 no.5
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• pp.62-70
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• 2015

A liquid rocket engine system can cause rapid pressure and temperature variations during the startup period. Thus the startup analysis is required to reduce time and expense for successful development of liquid rocket engine through the startup prediction. In this study, a startup analysis simulator is developed for a staged combustion cycle engine powerpack. This simulator calculates propellant flow rates using pressure and flow rate balances. In addition, a rotational speed of turbopump is obtained as a function of time by mathematical modeling. A startup analysis result shows that the time to reach a steady-state and a rotational speed at the steady-state are 1.3 sec and 27,500 rpm, respectively. Moreover it can indicate proper startup sequences for stable operation.

• KIPS Transactions on Computer and Communication Systems
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• v.3 no.7
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• pp.209-218
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• 2014

An AP that is used by smart device is going to be complicated because smart devices support diverse functions. As a result, multiple low-level IPs including a dedicated CPU are integrated in a high-level subsystem for supporting complicated function such as multimedia codec and camera. A subsystem has software that executes separately from main system, and the software needs to be initialized for every execution of the subsystem. This causes increase of the subsystem startup time so it should be improved because startup time of subsystem affects launching time of application. Methods in applied to computer system for fast startup also could be applied to fast startup of subsystem because subsystem is similar with computer system. In this paper, we apply snapshot method that is used in computer system to subsystem and analyzes the pros and cons. And snapshot method could not be applied to register of IP without modification because register of IP offers restricted read and write. So this paper suggests technique that applying snapshot to each characteristic of register.

• Aerospace Engineering and Technology
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• v.4 no.2
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• pp.142-152
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• 2005

There are two definite objects for developing the startup transient of liquid rocket engine. One is to achieve the repeatability of startup to ensure higher reliability, and the other is to reduce the time of the startup transient. Typically in the initial phase of engine development as we are currently opposing, it is hard to estimate engine startup time due to the lack of experiences. In this work, a startup transient analysis tool was developed with the introduction of the mathematical model for each component of pump-fed liquid rocket engine system. Startup transient was investigated for a 25 ton class gas generator cycle engine to find necessary time for reaching steady state from startup and this enabled to reveal dynamic characteristics of the engine.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.10 no.3
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• pp.99-109
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• 2015

The investment in healthcare industry has recently increased not only for global ventures but also for the domestic ventures. However, there has been hardship of founding and investment caused by healthcare startups characteristics that are costly and time consuming. In this study, the applicability of 'Lean Startup' theory to healthcare ventures was explored through the case of a domestic startup which accomplished funding from VC and KOSDAQ after establishing based on its technology in healthcare industry. There have been numerous case studies that applied 'Lean Startup' to IT industry. However, this case study that applied 'Lean Startup' to healthcare industry have some implications as follow: First, it is critical to conduct a hypothesis testing at initial research stage through R&D of 'MVP' (Minimum Viable Product) as the prototype testing is strictly prohibited in healthcare industry. Second, healthcare R&D teams ought to be well organized as startup teams and all researchers should be equipped with entrepreneurship as the licensing process in healthcare industry is time-consuming and costly due to issues like clinical studies. Lastly, management skills as smart and light as 'Lean Startup' are required in order to encourage young engineers' technology startups.

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.432-435
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• 2008

Launch vehicle for injecting the satellite into its orbit is composed with propulsion system, guidance and navigation system, telemetry and so on. Among the others, the propulsion system is the most important part, because that is the key factor of failure of launch vehicle. Especially, the most of failures were occurred in time of engine startup. Therefore, the study of the conditions for stable engine startup is needed at the first step of development. The many researches were accomplished for mathematical modeling, stable startup engine and control of liquid propellant rocket engine. But the cavitation problem that can be occurred at an inlet of pump associated with propellant feeding system wasn't considered in these works. In this paper, propulsion system model was integrated with clustered engines and propellant feeding system for the simulations of engine startup. As the results of simulations, the requirements were deduced for the stable engine startup without the cavitation at an inlet of pump.

• Asian Journal of Innovation and Policy
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• v.7 no.1
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• pp.79-102
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• 2018

In an entrepreneurial ecosystem, the failure rate of startups is extremely high at 90%, and every startup that fails becomes an orphan. This phenomenon leads to higher costs of failure for the entrepreneurs in the ecosystem. Failed startups have many lessons to offer to the ecosystem and offer guidance to the potential entrepreneur, and this area is not fully explored compared to the literature on successful startups. We use a case based method distinguishing a failed startup and a successful startup, studying the entrepreneurial characteristics and firm level factors which cause the failures, in the technology startup ecosystem of Bangalore. We study one of the modes of exit adopted by failed startup entrepreneurs and draw key lessons on causes that culminate in failures. We have identified that factors such as the time to minimum viable product cycle, time for revenue realization, founders' complementary skillsets, age of founders with their domain expertise, personality type of founders, attitude towards financial independence and willingness to avail mentorship at critical stages, will decisively differentiate failed startups from the successful ones. Accordingly, implications have been derived for potential entrepreneurs for reducing the cost of failures in the entrepreneurial ecosystem.

• Journal of IKEEE
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• v.19 no.4
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• pp.573-582
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• 2015

This paper presents the design of dual mode boost converter for energy harvesting. The designed converter boosts low voltage from energy harvester through a startup circuit. When the voltage goes above predefined value, supplied voltage to startup circuit is blocked by voltage detector. Boost controller makes the boosted voltage into $V_{OUT}$. The proposed circuit consists of oscillator for charge pump, charge pump, pulse generator, voltage detector, and boost controller. The proposed converter is designed and fabricated using a $0.18{\mu}m$ CMOS process. The designed circuit shows that minimum input voltage is 600mV, output is 3V and startup time is 20ms. The boost converter achieves 47% efficiency at a load current of 3mA.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.62-65
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• 2009

This study for prediction of startup characteristics for 30 tonf liquid rocket engine TP-GG-CC coupled test was performed on the basis of the previous TP-GG test and prediction results. For determining the valve sequence the startup analysis was performed by the specified program for several main valve time and the adequate valve sequence for startup could be obtained.