• The KIPS Transactions:PartC
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• v.17C no.2
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• pp.135-144
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• 2010

U-City pursues personalized service by collecting contexts through sensors located over the city and presenting the service automatically depending not on the user's request but on the situations that are needed. To provide the personalized service, however, contexts collected through various sensors are needed, and they include private information. Therefore, it is important to keep a balance between the convenience by presenting service and protecting private information. In this paper, we classify and grade person's various contexts requested in the personalized service environment. Based on these, we make decisions on whether to present the service or not by profile-matching between user profile and service profile. Also, we propose an efficient privacy-protection management scheme to encrypt transmitted private information and to control key distribution.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.26 no.5
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• pp.1089-1097
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• 2016

It is well-known that, if additional information other than a plaintext-ciphertext pair is available, breaking the RSA cryptosystem may be much easier than factorizing the RSA modulus. For example, Coppersmith showed that, given the 1/2 fraction of the least or most significant bits of one of two RSA primes, the RSA modulus can be factorized in a polynomial time. More recently, Henecka et. al showed that the RSA private key of the form (p, q, d, $d_p$, $d_q$) can efficiently be recovered whenever the bits of the private key are erroneous with error rate less than 23.7%. It is notable that their algorithm is based on counting the matching bits between the candidate key bit string and the given decayed RSA private key bit string. And, extending the algorithm, this paper proposes a new RSA private key recovery algorithm using a generalized probabilistic measure for measuring the consistency between the candidate key bits and the given decayed RSA private key bits.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.3
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• pp.383-390
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• 2018

Piezoelectric micro-machined ultrasonic transducers for highly directional speaker need DC bias voltage. Most existing power amplifiers are not suitable for use in highly directional transducers because they are based on AC. In addition, since the piezoelectric micro-machined ultrasonic transducer has a large capacitive reactance, the power efficiency of the power amplifier is very low. Thus this paper proposes a new high efficiency power amplifier with DC bias voltage. In addition, by designing a matching circuit to compensate the capacitive reactance of the micro-machined ultrasonic transducer, the power efficiency of the power amplifier increases. The operating characteristics of the proposed power amplifier was verified by an experimental prototype. The proposed power amplifier is expected to be widely used in designing and implementing other related power amplifiers.

• Korean Journal of Social Welfare Studies
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• v.42 no.3
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• pp.291-327
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• 2011

The purpose of this study is to classify the type of retirement process among the mature-aged in Korea. The study used the panel data from Korean Labor Panel (year2~6) for the classification of retirement process through Optimal Matching and Cluster Analysis. Classification is made in 5 categories as 'peripheral-economically active', 'private-transfer dependent', 're-entering limited', 'securely exiting', 'exit-and-reentering'. First, "peripheral-economically active" is a group which frequently experienced job status change and work insecurity. Second, "private-transfer dependent" is a group in which private transfer is likely to be supplements income in the incidence of unemployment. Third, "re-entering limited" is a group in which the proportion of no financial support combined with the absence of any economic activity is the largest. Fourth, the type "Securely exit" is th group whose members switches over to non-economically active status with pension receipt. The last type is "exit-and-reenter" that the member are highly possible to reenter in the labor market and stay in long time regardless of with or without pension plan. To examine the inequality among the types of retirement process, the duration of each status is analyzed. First, in the situation of being non-economically active, the duration of status is maintain public pension receiving and duration stabile in "securely exit" group. For "private-transfer dependent" type, members are mostly dependent on private financial support and that duration of it is longest. Through the analysis of retirement process without under other financial supports, it is "securely-exiting" type for which the duration of full-time employment is longest. It appears that the duration of part-time employment is longest in "peripheral-economically active" type. And for the case of non-waged employment it is "exit-and-reenter" type. Finally, the redistribution policy based on life course perspective is necessary to prevent that the opportunity in the structure before retirement stage and the unfavorable position in labor market make worse disadvantage in retirement process and after that.

• KDI Journal of Economic Policy
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• v.39 no.1
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• pp.1-18
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• 2017

This paper empirically studies the effect of public procurement on small and medium-sized enterprises (SMEs) in the Republic of Korea using firm-level data. Public procurement, the purchase of goods and services from private firms by the public sector, is regarded as an important policy measure for providing support to firms, particularly SMEs. This study uses establishment-level panel data of the mining and manufacturing sectors from the Korean National Bureau of Statistics (Statistics Korea) and procurement history from the Korean Public Procurement Service to empirically estimate the effects of public procurement on firms' productivity (total factor productivity) and survivability. Using a propensity score matching estimation method, we find that participating firms showed higher productivity than non-participating ones in the control group only for the year of participation, that is, 2009. After two years, in 2011, they exhibited significantly lower productivity. In contrast, establishments that participated in public procurement for SMEs in 2009 were more likely to survive than those that did not do so in 2011. These results can be interpreted as the negative consequences of government intervention. The market's efficiency enhancement is hindered if underserving companies survive owing to government intervention but fail to improve efficiency.

• Journal of Information Processing Systems
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• v.14 no.5
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• pp.1087-1101
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• 2018

As cloud computing has become a widespread technology, malicious attackers can obtain the private information of users that has leaked from the service provider in the outsourced databases. To resolve the problem, it is necessary to encrypt the database prior to outsourcing it to the service provider. However, the most existing data encryption schemes cannot process a query without decrypting the encrypted databases. Moreover, because the amount of the data is large, it takes too much time to decrypt all the data. For this, Programmable Order-Preserving Secure Index Scheme (POPIS) was proposed to hide the original data while performing query processing without decryption. However, POPIS is weak to both order matching attacks and data count attacks. To overcome the limitations, we propose a group order-preserving data encryption scheme (GOPES) that can support efficient query processing over the encrypted data. Since GOPES can preserve the order of each data group by generating the signatures of the encrypted data, it can provide a high degree of data privacy protection. Finally, it is shown that GOPES is better than the existing POPIS, with respect to both order matching attacks and data count attacks.

• Asian Journal of Innovation and Policy
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• v.8 no.3
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• pp.396-416
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• 2019

The key conditions for the promotion of innovative technology-based start-ups are expanding the market for innovative technology products and services, increasing equity-based funding opportunities, promoting the commercialization of technological innovation, and establishing a fair-trade system for start-ups to compete fairly in the market. Besides, there is a need for a support system that minimizes the cost of failure in case of business failure to facilitate re-challenge and provides education and training opportunities to enhance entrepreneurial capabilities. To activate technology-based start-ups, the Korean government introduced the TIPS policy in 2013. It is a program that creates technology start-up with private investment led by successful venture entrepreneurs, which has shown remarkable achievement and is regarded as the most successful policy in this field up to now. The most critical factor contributed to the success of this program is to invite private investors to select a technology entrepreneurship team and provide mentoring with the investment. The government provides R&D funding with matching investment, commercialization and marketing support to ensure that technology start-ups survive crossing the death-valley. Subsequent investments from domestic and abroad investors are actively made and it is becoming a representative technology-based start-up program in Korea.

• The Journal of Fisheries Business Administration
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• v.12 no.2
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• pp.61-71
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• 1981

This essay examines the marketing of Fishermen's Cooperative in Korea, and in particular considers the marketing channel of fisheries products, No company can perform by itself all the activities involved in the production and distribution of its products and services to its final markets. It must work with other firm to get the job done. Thus marketing channel firms of the fisheries products include primarily the Fishermen's Cooperative the licensed dealers and tile merchant middlemen, The goal of marketing is in matching of segments of supply and demand. Every producer seeks to the link the marketing channel firms that will help it accomplish its objective best. Therefore this study surveys the three types of marketing channels through tile central market That. is, they are a marketing channel through the terminal market, a marketing channel through the fishermen's cooperative terminal market, and a marketing channel through the private fish market. Consequently the Fishermen's Cooperative can choose to improve in any of tile marketing channel as follows: \circled1 The Fishermen's Cooperative is nominated wholesaler in the terminal market. \circled2 It is abolished to sell by double auction in the production district terminal market and the consuming city terminal market of Fishermen's Coopertive. \circled3 The steady wholesalers in private fish market are entitled to the licensed dealers. \circled4 The Fishermen's Cooperative sponsored voluntary chains join with retailer, supermarkets, consumers' society. Therefore the study of marketing channel of fisheries products can appropriately referred to satisfying needs and wants through exchange process.

• Journal of Korea Technology Innovation Society
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• v.15 no.3
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• pp.649-674
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• 2012

The purpose of this study is to investigate the effects of public R&D subsidies on private R&D. We have analyzed rationales for the public R&D subsidy from different perspectives. On the basis of literature review, a two step research model is constructed: participation phase (when firms benefit from public subsidies) and decision phase (when firms make decision on additional R&D investments). Using propensity score matching(PSM) method, we compare the potential outcome of the treated group to a matched controlled group of non-subsidized firms. The data used in this paper was collected from various sources. The Korean Innovation Survey 2008(manufacturing sector) is a main source of data. Financial data such as revenue, asset and capital stock, and number of employees were supplemented from the Nice Information Service KIS Value database. The R&D survey, conducted by MEST(Ministry of Education, Science and Technology) each year, was also used for the R&D expenditures of the manufacturing firms. This study comes up with the following empirical results. First, a firm's innovation capability, financial constraints, and sector appear to influence the selection of firms who were benefited from government's financial supports for R&D. Second, empirical results show that public R&D funding complements private investment on average and appear to have perpetual effects on the following year. Finally, sectoral difference in the effect of public subsidies on firms' R&D investment was confirmed. In addition, SMEs show more positive effects than large firms.

• Journal of the Korean Institute of Gas
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• v.25 no.5
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• pp.78-87
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• 2021

This paper analyzes the range and attributes of the traffic information service between domestic public institutions and private companies, and suggests the possibility of joint application of node-link information for each company and the possibility of joint use of private traffic information. For this purpose, the present condition and attributes of domestic and foreign traffic information node-links (link length, node ID number, U-turn information, lane information, left turn information, right turn information, etc.) were analyzed. The analysis targets, the node-link of the national standard node and the two companies were analyzed. The area of the experiment was selected in Jongno-gu, Seoul, where standard-link information is complex, traffic volume is high, and various standard-links exist. The experiment was conducted by comparing and analyzing the traffic information attributes of three types of node-links and performing node-links overlapping matching (utilizing encoding_decoding method), and the possibility of matching node-links and attributes of different specifications was analyzed using Open LR technique.