• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.4
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• pp.788-797
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• 2003

Class library is one of the most crucial element of Java runtime environment in addition to Java virtual machine. In particular, embedded Java system depends heavily on the class library due to having a low bandwidth communication link and a small amount of memory which are a common restriction of embedded system. It is therefore quite necessary to find the characteristic of the class library for embedded Java system to build an efficient Java runtime environment. In this paper we have analyzed the characteristic of the class library for embedded system. The analysis includes sorts of classes in the library, typical size of the file which contains the class, and the composition of constant pool which is a major part of the file. We also have found typical number of field and method a class contains, the sizes of stack and local variable array each method requires, and the length of bytecode in the method. The result of this study can be used to estimate the startup time for class loading and the size of memory to create an instance of class which are a mandatory information to design an efficient embedded Java virtual machine.

• Journal of Korean Society on Water Environment
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• v.27 no.6
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• pp.794-803
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• 2011

Self Organizing Map (SOM) was applied for pattern classification of hydrological and water quality data measured at Jangseong Reservoir on a monthly basis. The primary objective of the present study is to understand better data characteristics and relationship between the data. For the purpose, two SOMs were configured by a methodologically systematic approach with appropriate methods for data transformation, determination of map size and side lengths of the map. The SOMs constructed at the respective measurement stations for water quality data (JSD1 and JSD2) commonly classified the respective datasets into five clusters by Davies-Bouldin Index (DBI). The trained SOMs were fine-tuned by Ward's method of a hierarchical cluster analysis. On the one hand, the patterns with high values of standardized reference vectors for hydrological variables revealed the high possibility of eutrophication by TN or TP in the reservoir, in general. On the other hand, the clusters with low values of standardized reference vectors for hydrological variables showed the patterns with high COD concentration. In particular, Clsuter1 at JSD1 and Cluster5 at JSD2 represented the worst condition of water quality with high reference vectors for rainfall and storage in the reservoir. Consequently, SOM is applicable to identify the patterns of potential eutrophication in reservoirs according to the better understanding of data characteristics and their relationship.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.11
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• pp.398-411
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• 2020

This study explored the case of non-face-to-face classes at colleges initiated in the Corona 19 environment. The scope of this study was to analyze the learning development process of the non-face-to-face class case facing the Corona 19 environment in university classrooms in terms of class and learning content, interaction, assignment activity, and teaching-learning activities. It was conducted for first-year students at H University's Early Childhood Education Department of Startup Basic Course. Study results found that, first, interest in entrepreneurship increased as learning content. Second, as a result of exploring the teaching and learning process, there is no significant difference in understanding the content or achieving learning goals. Third, the most regrettable thing about non-face-to-face teaching-learning is the lack of interaction activities. Fourth, the students finished by adapting to the new non-face-to-face teaching-learning environment. In the future, a non-face-to-face environment platform should be established, and studies that can deal with new perspectives and approaches, such as an educational interaction system including online and offline, should be continued.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.19 no.1
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• pp.1-21
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• 2024

Recently, venture capital investment has been shrinking globally due to high interest rates and economic slowdown. Korea is no exception. Due to the downturn in the M&A and public markets, increasing economic uncertainty, and the aftermath of corporate bankruptcies, venture capitalists are facing many difficulties in raising funds. In the changed economic environment, the investment decision factors of venture capitalists have also changed. However, studies on VCs' investment decisions have focused on the general economic environment. This study examines how VCs' investment decision-making factors change during economic recessions and booms. To this end, we interviewed active investors who have experienced both economic recessions and booms to compare how VCs' investment decision factors change: 1) personal characteristics of founders, 2) experience of founders, 3) product/service, 4) market, 5) financial situation, 6) contract terms and 7) venture capital co-investment. The results showed that founder's personal characteristics, experience, and product/service were more important during the economic recession. Market is slightly more important during economic booms. The importance of financial situation and investment conditions increased sharply during the recession compared to the boom. Finally, venture capital co-investment did not differ significantly between recessions and booms. By understanding the investment decision-making factors of venture capitalists in the recent difficult venture investment environment, this study aims to help startups raise funds and survive in a difficult market.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.12 no.2
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• pp.167-174
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• 2012

The circuits including with Optical transceiver and clock data recovery, in this paper, SERDES (SERializer-DESerializer) are implemented to construct a GE-PON burst-mode transceiver supporting IEEE 802.3ah and a jig for measuring the burst-mode characteristics, that is to say, PON upstream optical transmission environment are manufactured to evaluate the performance of transceiver. we verified that the limiting amplifier compensated the gap of max. 26dB optical power by experiments. The startup acquisition lock time is 670ns in case of using VSC7123 and 2300ns in case of S2060 and the data acquisition lock time were measured to be 400ns and 600ns, respectively, in the upstream channel transmission in this work. While on the other, VSC7123 is satisfied with IEEE802.3ah recommendations.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.38-41
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• 2009

For the technology development of LOx/kerosene liquid rocket engine, turbopump-gas generator closed-loop coupled tests using 30tonf main engine components such as turbopump and gas generator except combustion chamber are performed. In the engine system operation environment, simulating combustion chamber by flow control units, the chill-down procedure, startup characteristics, nominal operability and smooth shutdown of turbopump+gas generator closed-loop coupled Test Plant are successfully confirmed. The serviceability of the turbopump and gas generator are evaluated. The feed-back control system for the turbopump rotational speed and gas generator mixture ratio are also verified. The results of closed-loop coupled test will be used as the technology development for the liquid rocket engine.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.5
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• pp.563-568
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• 2010

Turbopump-gas generator open-loop coupled tests are performed during the development of a 30tonf-LOx/Kerosene rocket engine. In the turbopump-gas generator open-loop tests, the propellants to gas generator are supplied from the outlets of turbopump, while the gas exhausted from the gas generator is vented out to the atmosphere, instead of being used to turbine driving. This paper presents the objectives, procedure, and results of the open-loop coupled test, in addition to a schematic representation of the test apparatus and the operating conditions for the test facility system and control system. The results of turbopump-gas generator open-loop coupled test confirm chill-down procedure, startup characteristics, nominal operability and smooth shutdown of the open-loop coupled Test Plant in test conditions simulating engine system operation environment.

• Journal of the Korean Institute of Intelligent Systems
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• v.19 no.1
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• pp.40-47
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• 2009

Recently, dynamic proxy caching has been proposed on the distributed environment so that media objects by user's requests can be served directly from the proxy without contacting the server. However, it makes caching challenging due to multimedia large sizes, low latency and continuous streaming demands of media objects. To solve the problems caused by streaming demands of media objects, this paper has been proposed the grouping scheme with fuzzy filtering based on partition and mapping. For partition and mapping, this paper divides media block segments into fixed partition reference block(R$_f$P) and variable partition reference block(R$_v$P). For semantic relationship, it makes fuzzy relationship to performs according to the fixed partition temporal synchronization(T$_f$) and variable partition temporal synchronization(T$_v$). Simulation results show that the proposed scheme makes streaming service efficiently with a high average request response time rate and cache hit rate and with a low delayed startup ratio compared with other schemes.

• Journal of KIISE:Databases
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• v.29 no.2
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• pp.119-127
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• 2002

Video server which stores video streams should serve more users with the requested streams rapidly, satisfying their time constraints. However, the number of users supported and the response times for the requested services in video server are in the oppositional relationship with viewpoint of disk throughput. In this paper, we propose new policy that can provide not only rapid responses for the service requests but also increase the number of users supported in the storage system of video server. The policy admits the random movements of disk heads for urgent service requests but maintains the sequential or restricted movements of disk heads and eliminates rewind time of disk heads for less-urgent service requests in storage system of multiple disks environment so that it can not satisfy only the QoS of users but also support more users.

• Journal of the Korea Convergence Society
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• v.10 no.1
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• pp.133-139
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• 2019

The Tech Shop, which provides an environment for fast prototyping by using 3D printers and various work tools, is a place where the fusion design education can be realized and creative ideas can be produced in the era of industrial 4.0. The purpose of this study is to propose and establish the possibility of a tech shop for the revitalization of local businesses in the Chungcheong province where many of contents related universities and institutions are located. For this purpose, we reviewed the necessity and the requirements of a tech shop, and analyzed the necessary components of a tech shop for successful operation. If the proposed tech shop is built and efficient operation is applied, it is expected that many of prototypes based on good ideas could be quickly produced and commercialized.