• Journal of the Korea Institute of Information Security & Cryptology
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• v.12 no.3
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• pp.3-13
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• 2002

There are cases that revoke the certification because of disclosure of private key, deprivation of qualification and the expiration of a term of validity on PKI. So, a user has to confirm the public key whether valid or invalid in the certification. There are many methods such as CRL, Delta-CRL, OCSP for the cert-validation of certification. But these methods have many problems, which cause overload traffic on network and the CRL server because of realtime processing for cert-validation of certification. In this paper we proposed cert-validation of certification improvement method based on FM Subcarrier Broadcasting, which solved problems that are data integrity by different time between transmission and receiving for CRL, and overload traffic on network and the CRL server the realtime management.

• Proceedings of the Korean Information Science Society Conference
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• 2005.07a
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• pp.190-192
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• 2005

PKI(Public Key Infrastructure)에서 인증서 상태 검증은 네트워크 환경에서의 거래에 신뢰성과 안전성 및 기밀성, 무결성 등의 서비스를 제공한다. 인증서 검증 방식은 CRL, OCSP, SCVP, DVCS 등이 있다. CRL은 시간이 지남에 따라 CRL의 크기가 증가하여 검증 시간이 지연되고 실시간 검증을 할 수 없는 단점을 가지고 있다. OCSP는 CRL을 이용하지 않고 거의 실시간에 가깝게 인증서를 검증하지만 서버의 부하 증가와 느린 검증 등의 단점을 가지고 있다. 분산 OCSP는 OCSP 서버를 분산시킨 후 CRL을 중복하여 보관하거나 분개하여 보관한 상태에서 검증하는 방식으로 대리검증에 따른 느린 검증과 CA의 부하부담 등의 단점을 가지고 있다. 본 논문에서는 제기된 단점들을 해결하여 빠른 검증과 부하 분산 효과를 얻을 수 있도록 분산된 OCSP 서버를 그룹으로 분류하고, 그룹 내의 각 서버에 인증서 폐지 정보를 중복 저장하여 부하분산, 빠른 검증, CRL을 Delta CRL 방식으로 OCSP 서버에 전송하여 네트워크 부하를 감소할 수 있도록 그룹 분산 OCSP 방식을 제안하고자 한다.

• Journal of the Korea Society of Computer and Information
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• v.11 no.1 s.39
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• pp.35-44
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• 2006

As the E-commerce and E-business are developed actively, using certificate is incremented rapidly. The certificate validation must be confirmed at first in E-commerce and the OCSP Responder can offer CSI to the client using OCSP. With the rapid development of the E-commerce based on the Internet, a lot of clients request CSI to OCSP Responder. So, the load to OCSP Responder is increased and the OCSP Responder may be overloaded. Therefore, for distributing the load to an OCSP Responder, D-OCSP is introduced. As the CRL has a lot of information about revoked certificates and have a high exposure Possibility of information in the process of distribution, the confidentiality as well as integrity are required in the process of distribution. So, we propose a CRL distributing method based on group key agreement in D-OCSP. The proposed method can distribute effectively a published CRL to OCSP Responders with confidentiality as well as integrity and offer concurrency that each OCSP Responder can start CSI servicing of new CRL to clients at the same time.

• The Korean Journal of Ceramics
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• v.6 no.2
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• pp.168-171
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• 2000

VO$_2$ceramics exhibiting a negative temperature coefficient (NTC) of resistivity have been widely used as temperature dependence resistors. The NTC effect similar to $VO_2$ceramics was observed when a low-thermal-expansion ceramic matrix was loaded near the percolation threshold with conductive metal particles. The resistivity in a composite made from silica glass and 20 vol% Ag filler suddenly decreased from $10^{-7}$ to $10^3\;\Omega$cm at about $300^{\circ}C$.

• Proceedings of the CALSEC Conference
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• 2001.08a
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• pp.155-163
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• 2001

There are cases that revoke the certification because of disclosure of private key, deprivation of qualification and the expiration of a term of validity based on PKI. So, a user have to confirm the public key whether valid or invalid in the certification. There are many method such as CRL, Delta-CRL, OCSP for the cert-validation of certification. But these method many problems which are overload traffic on network and the CRL server because of processing for cert-validation of certification. In this paper we proposed the realtime cert-validation of certification method which solved problems that are data integrity by different time between transmission and receiving for CRL, and overload traffic on network and the CRL server based on DARC.

• Proceedings of the Korea Information Processing Society Conference
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• 2003.05c
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• pp.2077-2080
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• 2003

일반적으로 기존의 도메인으로부터 인증서를 검증하는 방법은 CRL(Certificate Revocation List), OCSP(Online Certificate Status Protocol), Freshest CRL, Delta CRL등이 있으나 CRL 검증 방식에 대해서 여러 단점이 부각되었다. 현재 CRL 검증 방법에 대해서 효율적으로 검증하기 위한 방안이 OCSP, Delta CRL등이 제시하여 서비스를 하고 있는 실정이다. 피러나 이런 검증 서비스 시스템에도 한계성이 드러나게 되었고 그 단점을 보완하기 위한 검증 시스템을 채택하여 기존의 인증서 검증 서비스보다 효율적이고 안정적인 시스템을 구현하기 위해 CSMS(Certificate Status Management Server)를 제시한다. CSMS는 OCSP와 같이 실시간으로 검증과 빠른 서비스로 USER에게로의 응답을 위한 서비스를 제공함으로써 전자상거래를 통한 트랜젝션에 적합한 시스템을 위한 것이다.

• Journal of the Korea Society of Computer and Information
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• v.21 no.1
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• pp.91-99
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• 2016

A certificate revocation list(CRL) should be distributed quickly to all the vehicles in the network to protect them from malicious users and malfunctioning equipments as well as to increase the overall security and safety of vehicular networks. However, a major challenge is how to distribute CRLs efficiently. In this paper, we propose a novel Regional CRL distribution method based on the vehicle location registration locally to manage vehicle mobility. The method makes Regional CRLs based on the vehicles' location and distributes them, which can reduce CRL size and distribution time efficiently. According to the simulation results, the proposed method's signaling performance of vehicle's registration is enhanced from 22% to 37% compared to the existing Regional CRL distribution method. It's CRL distribution time is also decreased from 37% to 67% compared to the existing Full CRL distribution method.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.21 no.4
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• pp.161-169
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• 2011

There is a consensus in the field of vehicular network security that public key cryptography should be used to secure communications. A certificate revocation list (CRL) should be distributed quickly to all the vehicles in the network to protect them from malicious users and malfunctioning equipment as well as to increase the overall security and safety of vehicular networks. Thus, a major challenge in vehicular networks is how to efficiently distribute CRLs. This paper proposes a CRL distribution method aided by terrestrial digital multimedia broadcasting (T-DMB). By using T-DMB data broadcasting channels as alternative communication channels, the proposed method can broaden the network coverage, achieve real-time delivery, and enhance transmission reliability. Even if roadside units are not deployed or only sparsely deployed, vehicles can obtain recent CRLs from the T-DMB infrastructure. A new transport protocol expert group (TPEG) CRL application was also designed for the purpose of broadcasting CRLs over the T-DMB infrastructure.

• Korean Journal of Veterinary Research
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• v.32 no.3
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• pp.309-319
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• 1992

This study was undertaken to establish the sequence of development of ages and its time of the fetal endochondral ossification in the scapula of the Korean native cattle. This study was also designed to confirm through histological observation the earliest stages of both chondrification and ossification. Thirty eight scapulae, a series of embryos and fetuses from the pregnant Korean native cattle ranging from 11 to 110mm in crown-rump (C-R) length, were used. The following results were obtained. The ossification center was observed in the supra- and infra- spinous fossa in the 5th group (CRL 51-60mm), that was markedly ossified in the 6th group (CRL 61~70mm) by Alizarin red S stain. The chondrogenic center of scapula was observed in the 1st group (CRL 11~20mm). The primary ossification center was presented in the 4th group (CRL 41~50mm). In the 5th group(CRL 51~60mm), the endochondral ossification progressed actively. Alcianophility was markedly increased in the interterritorial matrix in the 3rd group (CRL 31~40mm. However this reaction was markedly decreased in the interterritorial matrix the adjacent portion to the marrow cavity and trabecula in the 5th group (CRL 51~60mm).

• Journal of Korean Society of Industrial and Systems Engineering
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• v.28 no.4
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• pp.85-93
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• 2005

This paper is designed a VSI ${\overline{X}}$-CRL synthetic control chart in aspect of economy. We found the optimal sampling interval and various control limit factors under various cost parameters using cost function, proposed Lorenzen and Vance. Optimal design parameters include the sample size, control limit width, sampling interval, CRL/S chart control limit; L. Comparison and analysis of cost parameters are applied between synthetic VSI ${\overline{X}}$-CRL chart and FSI ${\overline{X}}$-CRL chart. The result of this paper shows that VSI ${\overline{X}}$-CRL chart brings cost-cutting effect of 3.04% control expense less than FSI control chart. It may not be difficult to establish the optimal economic control parameters to apply the practical cost parameters in the field.