• Journal of the Korean Society of Propulsion Engineers
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• v.7 no.2
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• pp.44-53
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• 2003

A vertical hot-firing test facility was established to carry out the IPPT(Integrated Propulsion Performance Test) and SQT(Stage Qualification Test) of KSR-III(Korea Sounding Rocket-III). The components for actual launcher were mostly used, hence these tests were carried out under the condition of relatively lower safety margin. To perform hot-firing tests with the maximum safety, an engine emergency blockage system was investigated and applied. An emergency blockage system using combustion chamber pressures and acceleration signals was set up to monitor ignition delay and fail, flame out, propellant feeding status, unstable combustion and excessive structural vibration. With such a system, the test safety could be secured by rapid judgement and follow-up measures, which made IPPT and SQT be safely completed.

• Journal of KIISE:Computer Systems and Theory
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• v.31 no.11
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• pp.617-625
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• 2004

We propose an efficient stream authentication scheme that is an improvement of PCC scheme by using information dispersal algorithm. The drawback of PCC scheme is that received packets for each group are verifiable only if the signature packet of the group is successfully received. The proposed scheme processes the signature packet by introducing some amount of redundancy and splitting the result into pieces, which are then transmitted. The receiver is able to reconstruct the signature packet if the number of the received pieces is larger than the threshold. It is shown that under the same communication overhead verification probability of the proposed scheme is higher than that of SAIDA. Moreover, its computational cost is lower than that of SAIDA.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.18 no.5
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• pp.241-253
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• 2023

In the current rapidly changing environment, each country continues to make efforts to create jobs and strengthen technological competitiveness. In particular, support and revitalization policies for venture companies and start-ups are known to play a role in increasing national competitiveness. Companies should make appropriate replacements amid growing uncertainties in the environment in which business life is shortened and customer needs are diversified due to intensifying competition. First of all, it is important for companies to make efforts to strengthen their internal capabilities on their own. However, venture companies lack internal resources and capabilities, so support from the external environment is important enough to lead to the survival of the company(Timmons, 1994). Financial support and certification systems are being operated at the national level to strengthen the competitiveness of companies. However, financial support can lower a company's self-sustainability depending on the situation, so non-financial support such as R&D support and start-up education is considered to be helpful in the long term for venture growth(Aghion et al., 2012; Jeon & Ko, 2021). Non-financial support is divided into commercialization, facilities, space, childcare, manpower, and certification systems, and this study confirmed the benefits of the venture company confirmation system, which is a certification system. To this end, the 2021 venture company precision survey data and venture company sales data were used, and analyzed using the SPSS 26.0 package and SPSS PROCESS MACRO. As a result of the analysis, it was confirmed that the level of the management environment of venture companies has a positive effect on the benefits of the venture confirmation system or increasing the level of venture company capabilities, but it is difficult to lead to actual management performance. In addition, it was confirmed that the level of venture company competency mediates the relationship between the level of the venture company's business environment and management performance. As a result, even if the level of the venture company's business environment is positive or venture-friendly, it can be said that companies with internal capabilities to digest support from the external environment increase management performance.

• The Korean Journal of Air & Space Law and Policy
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• v.28 no.1
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• pp.3-54
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• 2013

Nowadays, major advanced countries in aviation technology are putting their effort to develop commercial and civil Unmanned Aircraft System(UAS) due to its highly promising market demand in the future. The market scale of commercial and civil UAS is expected to increase up to approximately 8.8 billon U.S. dollars by the year 2020. The usage of commercial and civil UAS covers various areas such as remote sensing, relaying communications, pollution monitoring, fire detection, aerial reconnaissance and photography, coastline monitoring, traffic monitoring and control, disaster control, search and rescue, etc. With the introduction of UAS, changes need to be made on current Air Traffic Management Systems which are focused mainly manned aircrafts to support the operation of UAS. Accordingly, the legislation for the UAS operation should be followed. Currently, ICAO's Unmanned Aircraft System Study Group(UASSG) is leading the standardization process of legislation for UAS operation internationally. However, some advanced countries such as United States, United Kingdom, Australia have adopted its own legislation. Among these countries, United States is most forth going with President Obama signing a bill to integrate UAS into U.S. national airspace by 2015. In case of Korea, legislation for the unmanned aircraft system is just in the beginning stage. There are no regulations regarding the operation of unmanned aircraft in Korea's domestic aviation law except some clauses regarding definition and permission of the unmanned aircraft flight. However, the unmanned aircrafts are currently being used in military and under development for commercial use. In addition, the Ministry of Land, Infrastructure and Transport has a ambitious plan to develop commercial and civil UAS as Korea's most competitive area in aircraft production and export. Thus, Korea is in need of the legislation for the UAS operation domestically. In this regards, I personally think that Korea's domestic legislation for UAS operation will be enacted focusing on following 12 areas : (1)use of airspace, (2)licenses of personnel, (3)certification of airworthiness, (4)definition, (5)classification, (6)equipments and documents, (7)communication, (8)rules of air, (9)training, (10)security, (11)insurance, (12)others. Im parallel with enacting domestic legislation, korea should contribute to the development of international standards for UAS operation by actively participating ICAO's UASSG.

• 한국정보통신설비학회:학술대회논문집
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• 2008.08a
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• pp.211-217
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• 2008

Recently, there are many efforts to support seamless mobility in 802.11 WLANs using IP Layer mobility protocols. The IP layer mobility protocols are the most efficient mechanism to guarantee the service session continuity when IP subnet is changed during handover. Even if the IP layer mobility protocols are quite efficient, the feature of the protocols that had been designed to consider only L3 layer makes it difficult to improve the performance of hand over more and more. Nowadays, to overcome this limitation of IP mobility protocols, many researchers have worked on the mobility protocols integration of different layers (e.g., L2 layer). In this paper, we propose the enhanced Proxy MIPv4 to minimize the latency of handover using MIH protocol in 802.11 WLANs. The proposed mechanism minimizes the latency of authentication by exchanging security keys between Access Routers during handover. Moreover, it also minimizes packet losses by Inter-AP Tunneling and data forwarding.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.14 no.5
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• pp.43-59
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• 2019

The promotion of social economy is one of the Korean government's top 100 initiatives. As of August 2019, there are 2,249 certified social enterprises in Korea, showing explosive growth with a 41-fold increase from 2007 when the Social Enterprise Promotion Act was first enacted. Currently, the discussion of the sustainability of social-economic organizations is lively, including the issue of changing the certification system to the registration system. Noting the unusual management structure of social enterprise - seeking both social and economic value, this study identifies factors affecting the performance of social enterprises. The study focuses on an empirical investigation of the relationships between characteristics of entrepreneurs' experiences in social economy, strategic competency, the extent to which they seek social value, and their performance. This study is unique in social enterprise research due to its approach to the hybrid management structure of social enterprise with a focus on entrepreneurs' characteristics. Accordingly, this empirical investigation focuses on how social-value seeking mediates the relationships between strategic competency emphasized in typical for-profit enterprises, the characteristics of experiences stressed in social-economic organizations, and the performance of social enterprises. The study findings suggest that, firstly, social entrepreneurs must seek social value as a top priority and improve economic performance using strategic competency to keep pursuing social value, and secondly, social-value seeking must be founded upon entrepreneurs' understanding and experiences in social economy. Practical implications of the study findings include concrete directions for training in social enterprises offered by relevant agencies and the establishment of competency models for current and future entrepreneurs.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.17 no.6
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• pp.39-50
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• 2022

Based on the signaling theory, this study examined whether startups are more likely to attract venture investment when receiving government R&D subsidies. First, we reviewed previous studies of the investment decision-making process of venture capitalists and understood the conditions that influence investment decisions. Based on previous studies on the signal effect of government subsidies, particularly government R&D grants, on inducing private fund investment, this study revealed a mechanism to induce venture investment by startups. In addition, in order to verify whether government R&D subsidies have the effect of inducing venture investment, an empirical analysis was conducted based on data from startups under seven years and certified as a venture companies in 2021. This paper used PSM(Propensity Score Matching) method and DID(Difference In Difference) analysis for an empirical study to analyze the average treatment effect on the treated group(beneficiary startups of government R&D grants). As a result of empirical analysis, companies that receive more government R&D subsidies after starting a business are more likely to attract venture investment. From two to three years after conducting the first government R&D project, startups that received government R&D grants attracted more venture investment than those that did not. The results of this paper demonstrate that government R&D projects can also affect the venture investment ecosystem, giving policy implications to government R&D projects targeting startups. It is also expected to suggest strategic implications to startups that need new funding.

• Journal of Internet Computing and Services
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• v.11 no.6
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• pp.87-110
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• 2010

Recently competitive Korean companies are suffered from financial loss due to illegal exposure of their own proprietary know-how secrets, since it is difficult to watch hidden illegal channels to leak them due to their digitalization. Today the DRM-based system designed to protect such secrets is insufficient to prevent it, since DRM-based protection system cannot defend the intelligent robbery of secrets, in special, employee's robbery. The MSEC is much appropriate to secure secrets against employee's robbery. Our paper notes that IGMP, MSEC and SNMP can work easily together to realize secure system that satisfy strong security condition for prevention from leaking secrets. Since the previous research was on the architectural design for prevention of illegal exposure, this paper proposes the efficient protocol based on MSEC protocol. Our protocol satisfies the strong security conditions that the principles that the secret should be stored/distributed only in an encrypted shape, and should be separated physically from its encryption key, and should be carried in registered mobile storage separate from its processing device, and should be verified in terms of both user and device. Thus this paper proposes both the protocol for secret document distribution and its group key management.

• Journal of Animal Science and Technology
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• v.49 no.2
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• pp.245-256
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• 2007

There are approximately 250,000 organic livestock farming in the world. The total retail value of organic food sales in the world is $ 27 billion. The organic livestock products such as milk, lamb and beef are marketed mostly in Europe and the USA. The market share of organic food is about 2% in total food marketing value of worldwide and of the organic food marketing value, organic livestock products portioned 17% in the USA. The organic livestock products are primarily marketed at Supermarket(Europe), Health and Natural Food store(USA). Concerning international trade, it is very little. But it is increasing among the developed counties of Europe. In the future, the production of organic livestock products will be rapidly increased in South America, Middle East and Oceania, but the growth rate will be limited due to its expensive price, lack of marketing-infra and different regulation system. Most of developed countries drive organic farming policy strongly as the strategic means of rural development, diversifying agriculture system and environmental improvement.

• Convergence Security Journal
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• v.7 no.3
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• pp.109-120
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• 2007

VoIP service provides various functions that PSTN phone service hasn't been able to provide. Since it also has superiority in service charge, the number of user is increasing these days. When we think of the other side in cost aspect, the spam caller can also send his/her commercial message over phone line using more economic way. This paper presents the characteristics that should be considered to detect the spam call using greylisting method. We have explored static and dynamic characteristics in VoIP calls, and analyzed the relation among them. Especially, we have surveyed the authentication and charging method of Korean VoIP service provider. We have analyzed each charging method using our spam call simulation result, and derived the charging method that can be favored by spam caller. The contribution of the work is in analysis result of static aspect for SPIT Level calculation in greylisting method.