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PKINIT 기반 새로운 커브로스 인증 메커니즘의 설계
김철현(Cheolhyun Kim),정일용(Ilyong Chung) 한국정보과학회 2001 정보과학회논문지 : 정보통신 Vol.28 No.1
본 논문에서는 X.509와 DNS를 연관하여 새로운 Kerberos 인증 메카니즘을 제안한다. Kerberos에서는 영역간의 서비스에 대하여 언급을 하지 않았기 때문에 영역간 인증은 X.509와 DNS(Domain Name System)를 사용하여 얻을 수 있는 체인에 의해서 수행하는 PKINIT를 통하여 이루어진다. 두 개의 프로토콜은 상이한 키관리 방식을 갖고 있는데 Kerberos는 공통키에 기반을 두고 있는 반면에 X.509 는 공개키 방식에 기반을 두고 있다. 따라서 본 논문에서는 이들을 상호 연동시키기 위해 연결 세션은 DS(Directory Service)를 이용하였고, 실제적인 인증을 위해서는 Kerberos를 적용하였다. 새로운 프로토콜은 통신복잡도의 관점에서 고찰하면 IETF CAT 작업반(Working Group)에서 제안한 인증 메커니즘보다 개선되었다. In this paper, a new Kerberos authentication mechanism associated with X.509 and DNS(Domain Name system) is presented. Since any suggestion to regional services are not described in Kerberos, authentication between regions is performed via PKINIT, which can be accomplished by the connected chain obtained from X.509 and DNS. These two protocols have distinguished key management systems. X.509 is designed using an asymmetric method, while Kerberos using a symmetric method. In order to provide regional services, DS(Directory Service) is employed on connection part and Kerberos on actual authentication part. The new protocol is better than the authentication mechanism proposed by IETF CAT Working group in terms of communication complexity.
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신선 물오징어의 도ㆍ소매시장 간 가격 변동성의 전이 및 비대칭성 분석에 관한 연구
김철현 ( Cheolhyun Kim ),남종오 ( Jongoh Nam ) 한국수산경영학회 2018 수산경영론집 Vol.49 No.2
Squid is a popular seafood in Korea. However, since the 2000s, the squid production has been declining. The unstable supply of the squid products may cause price fluctuations of fresh and chilled squid. These price fluctuations may be relatively more severe than them of other commodities, because the fresh and chilled squid can not be stored for a long period of time. Thus, this study analyzes the structural characteristics of price volatility and price asymmetry of fresh squid based on off-diagonal GARCH model. Data used to analysis of this study are daily wholesale and retail prices of fresh squid from January 1, 2006 to December 31, 2016 provided in the KAMIS. As theoretical approaches of this study, first of all, the stability of the time series is confirmed by the unit root test. Secondly, the causality between distribution channels is checked by the Granger causality test. Thirdly, the VAR model and the off-diagonal GARCH model are adopted to estimate asymmetry effect and price volatility spillover between distribution channels. Finally, the stability of the model is confirmed by multivariate Q-statistic and ARCH-LM test. In conclusion, fresh squid is found to have shock and volatility spillover between wholesale and retail prices as well as its own price. Also, volatility asymmetry effect is shown in own wholesale or retail price of fresh squid. Finally, this study shows that the decrease in the fresh squid retail price of t-1 period than the increase in the t-1 period has a greater impact on the volatility of the fresh squid wholesale price in t period.
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