• Proceedings of the Korea Information Processing Society Conference
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• 2004.05a
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• pp.1107-1110
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• 2004

PKI(Public key Infrastructure)기반에서 CA(Certificate Authority)는 사용자를 인증하기 위해서 인증서를 생성하고, 인증서의 상태를 검증하기위해서 CRL(Certificate Revocation List)를 발행하여 인증서 취소 상태를 확인하도록 한다. CRL을 사용할 경우 사용자의 증가로 인하여 CRL의 크기가 증가 함으로써 많은 부담과 실시간 처리가 어렵다. 이와 같은 단점을 보안하기 위해서 최근에는 실시간 처리가 가능한 OCSP(Online Certificate Status Protocol)방법이 제안되었지만 이 또한 사용자의 급증으로 하나의 OCSP 서버에 집중화 됨으로써 OCSP 서버의 부하가 많이 생긴다. 본 논문에서는 집중 OCSP 서버에서 생기는 부하를 줄이기 위해 여러 개의 OCSP 서버를 두고, 각 OCSP 서버의 응답 처리 시간을 빠르게 하기 위해서 CA가 실시간으로 인증서 취소 정보를 해당 OCSP 서버에게 분배하여 전달하고 Front Server를 둠으로써 각 OCSP의 Load를 모니터링하여 부하가 적게 걸린 OCSP에게 인증서 상태 검증을 함으로써 신뢰성과 각 OCSP 서버의 부하를 줄이는 방안을 제시한다.

• Molecules and Cells
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• v.37 no.11
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• pp.833-840
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• 2014

Cullin4-RING ubiquitin ligase (CRL4) is a family of multi-subunit E3 ligases. To investigate the possible involvement of CRL4 in heat stress response, we screened T-DNA insertion mutants of putative CRL4 substrate receptors that exhibited altered patterns in response to heat stress. One of the mutants exhibited heat stress tolerance and was named heat stress tolerant DWD1 (htd1). Introduction of HTD1 gene into htd1-1 led to recovery of heat sensitivity to the wild type level, confirming that the decrease of HTD1 transcripts resulted in heat tolerance. Therefore, HTD1 plays a negative role in thermotolerance in Arabidopsis. Additionally, HTD1 directly interacted with DDB1a in yeast two-hybrid assays and associated with DDB1b in vivo, supporting that it could be a part of a CRL4 complex. Various heat-inducible genes such as HSP14.7, HSP21, At2g03020 and WRKY28 were hyper-induced in htd1-1, indicating that HTD1 could function as a negative regulator for the expression of such genes and that these genes might contribute to thermotolerance of htd1-1, at least in part. HTD1 was associated with HSP90-1, a crucial regulator of thermotolerance, in vivo, even though the decrease of HTD1 did not affect the accumulation pattern of HSP90-1 in Arabidopsis. These findings indicate that a negative role of HTD1 in thermotolerance might be achieved through its association with HSP90-1, possibly by disturbing the action of HSP90-1, not by the degradation of HSP90-1. This study will serve as an important step toward understanding of the functional connection between CRL4-mediated processes and plant heat stress signaling.

• Proceedings of the Korean Information Science Society Conference
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• 2002.04a
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• pp.832-834
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• 2002

현재 인터넷 상에서 가장 많이 제공되고 사용되는 서비스는 전자 상거래에 관련된 서비스이다. 이러한 서비스에서 각 사용자 사이의 신원을 증명해 줄 인증서는 절대적인 위치를 차지하게 된다. 따라서 전자 상거래의 성격에 비추어 그 인증서는 항상 적시에 유지 관리 되어야하며, 그 상태가 매 순간마다 정확하게 변경되어야 할 것이다. 그리고 그 보안성도 높아야 한다. 이러한 요구사항을 만족하기 위해서 많은 연구가 진행되고 있다. 본 논문에서는 이를 현재 인터넷 환경에서 반드시 사용되어야 하는 DNS를 이용하여 해결하는 방법을 제안하고자 한다. 자원레코드의 한 속성을 사용하여 인증서를 배포하고, 그를 검증하여 안전하고 적시 적용이 가능하도록 한다.

• Proceedings of the Korean Information Science Society Conference
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• 2001.10a
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• pp.757-759
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• 2001

인증서의 유효성을 검사하기 위해 인증기관의 디렉도리내에 있는 최신의 인증서 폐지 목록을 많은 사용자가 동시에 조회시 시스템의 부하 및 속도 저하를 가중시킬 수 있다. 본 논문에서는 디렉토리에 대한 부하를 분산시키고 효율적으로 인증서 유효성 검사를 수행하기 위해 사용자 PC내에 자동 업데이트 엔진을 두어 인증서내의 CRL 분배점을 통한 인증서 폐지 목록을 다운로드 하는 방법을 제안하였다. 다운로드된 인증서 폐지 목록은 사용자의 인증서와 함께 유효성 검사에 이용되며 디렉토리에 대한 조회 횟수를 분산시켜부하를 감소시킬 수 있다.

• Proceedings of the Korean Information Science Society Conference
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• 2002.10c
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• pp.472-474
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• 2002

공개키 기반 구조에서 가장 비용이 많이 드는 부분이 인증서가 유효한지 여부를 검증하는 것이다. 특히 고액의 주식 거래나 전자상거래에서 실시간 인증서 상태 검증은 반드시 필요하다. 그동안 연구되어 왔던 인증서 폐지 여부를 확인하는 방법으로 CRL, delta-CRL, OCSP, CRTs, CRSL 등의 방법들이 제안되었다. 하지만, 이들 방법들은 즉시성과 네트워크 비용간의 trade-off가 발생하는 문제점이 있다. 본 논문에서는 Simple skip lists를 사용하여 인증서 사용 용도에 따라 알맞게 서비스를 제공하는 방안인 OCRS를 제안한다.

• International Union of Geodesy and Geophysics Korean Journal of Geophysical Research
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• v.22 no.1
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• pp.1.2-5
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• 1994

Ionospheric sounding experiments have been conducted at RRL (Radio Research Laboratory), Ministry of Communications, using Digisonde 256 since its installation in 1990. Routine observations of the vertical sounding are carried out 48 times (or 39 times) a day, at every 24 hour. In addition, we also made oblique sounding experiments to obtain the real time data of Maximum Usable Frequency (MUF) and detect the anomalous HF propagation, as a part of the joint study between RRL and CRL (Communications Research Laboratory) of Japan. The two stations involved in the study were Anyang (RRL, Korea) and Kokubunji (CRL, Japan). The ionosondes used in both stations were Digisonde 256, developed by ULCAR (University of Lowell, Center for Atmospheric Research), U. S. A. , and the synchronization of time was accomplished with the help of GPS receiver. During most part of the experiments RRL transmitted non-modulated pulses, and CRL received them. The experiment was scheduled from October 25 through October 29, 1993. However, the ionosphere was not developed well enough to conduct the experiment with pre-set operation parameters. The experiment became successful (from 0500 UT to 0800 UT, October 29) only after the operation parameters had been changed, and the continuous ionograms were obtained by CRL at 0718 UT and 0733 UT in October 29, 1993. We believe this type of experiment will ensure the qualitative enhancement of solar-terrestrial physics research and a routine observation of the oblique ionospheric sounding. In this report, we present the results of the fore-mentioned oblique sounding as well as the vertical sounding results obtained by Digisonde 256 at Anyang station of RRL.

• Korean Journal of Veterinary Research
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• v.39 no.6
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• pp.1161-1167
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• 1999

To investigate the effect of diazepam on fetal development in pregnant rats, this experiment was performed in eighty Sprague-Dawley female rats which were 8 weeks old and grouped into two according to different diazepam treatment period during 5-9 days of gestation and 10-14 days of gestation. Both experimental groups were included by saline treated groups (control) and diazepam-treated groups (6mg, 12mg and 24mg), respectively. Diazepam was injected to pregnant rats subcutaneously, which were sacrified on 20 days of gestation and mean litter size, fetal body weight, fetal crown-rump length (CRL) and pathological findings were examined. 1. Concerning mean litter size, diazepam-treated groups showed lower mean litter size than control in both 5-9 days and 10-14 days of gestation groups(p < 0.05) without difference according to dosage of diazepam and day of gestation. 2. Concerning fetal body weight, diazepam-treated groups during 5-9 days of gestation showed lower fetal body weight than control and the other treated group during 10-14 days(p < 0.01) without difference according to dosage of diazepam. Diazepam-treated group during 10-14 days of gestation showed no difference among experimented groups. 3. Concerning fetal crown-rump length (CRL), diazepam-treated groups during 5-9 days of gestation showed shorter CRL than control and the other treated group during 10-14 days of gestation(p < 0.01) without difference according to dosage of diazepam. 4. Reduction of mean litter size, fetal body weight and CRL was shown from when treated by the dosage of 6mg/kg of diazepam. 5. Maternal mortality according to dosage of the 20mg/kg of diazepam were 30% and 20% in the treated group during 5-9 days and 10-14 days of gestation, respectively. These results indicated that diazepam treatment in pregnant rats caused considerable reduction of mean litter size, fetal body weight and fetal crown-rump length when treated during 5-9 days of gestation.

• Biomedical Science Letters
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• v.18 no.3
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• pp.268-275
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• 2012

Reference ranges of standard experimental parameters are useful for comparisons in toxicology. The aim of this study was to collect data from 4-week repeated toxicity studies in Crl:CD (SD) rats, a strain widely used for toxicity and efficacy research, for establishing domestic reference values. Data on body weight, food consumption; urinalysis, hematological, and blood biochemical parameters; and organ weights were collected from 16 toxicity studies in 220 Crl:CD (SD) rats (110 males and 110 females). The studies had been performed at a single testing facility over the last 3 years and involved animals sourced from a single breeder. The findings were collated as means, standard deviations, percentages, and ranges. Urine volume, uterus weight, eosinophil, and basophil counts, and triglyceride, total bilirubin, and gammaglutamyl transpeptidase levels showed standard deviations of 30% or more. These historical control data would help to interpret the effects of test substances in routine toxicity and efficacy studies.

• Proceedings of the Korea Institutes of Information Security and Cryptology Conference
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• 2002.11a
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• pp.381-384
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• 2002

현재 인증서의 상태 검증을 실시간으로 제공하기 위해 각 CA(Certificate Authority)들은 고전적 방법인 CRL(Certificate Revocation List) 배포보다는 OCSP(Online Certificate Status Protocol)을 통하여 인증서의 상태에 대한 정보를 실시간으로 제공한다. 그러나, 경로검증 및 인증서 정책 맵핑 및 정책검증과 인증서 상태검증을 제공하는 SCVP(Simple Certificate Validation Protocol)는 CRL을 사용하는 한계로 인하여 실시간 검증을 제공하지 못하고 있다. 또한 OCSP는 인증서의 실시간 상태검증만을 제공할 뿐, 인증서의 경로검증과 인증서 정책 맵핑 및 정책검증에 대한 서비스는 제공하지 못하고 있다. 따라서, 이러한 두 프로토콜의 단점을 보안하고, 인증서 검증서버가 제공해야 하는 모든 서비스를 제공하기 위해 OCSP와 SCVP의 연동방안에 대한 연구를 통하여 SCVP에서의 실시간 검증을 제공할 수 있도록 한다.

• Journal of the Korea Society of Computer and Information
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• v.9 no.3
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• pp.163-169
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• 2004

In this paper, a conventional key exchange method simply performs the key exchange setup step based on discrete algebraic subjects. But the mutual-authentication procedure of wireless PKI for reducing authentication time uses an elliptical curve for a key exchange setup step. Proposed handover method shows reduced handover processing time than conventional method since it can reduce CRL retrieval time. Also, we compared proposed authentication structure and conventional algorithm. and simulation results show that proposed authentication method outperforms conventional algorithm in all environment regardless of call arrival rate. queue service rate. queue size.