• KSBB Journal
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• v.29 no.6
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• pp.432-436
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• 2014

We investigated antioxidative activity of the ethanol extracts of leaves of Cornus walteri Wanger (CWE) by treated enzyme in human dermal fibroblast (HDFs) irradiated by UVB. We examined the in vitro chemical and cellular antioxidant activities of CWE in HDFs. We employed scavenging assay for the 1,1-diphenyl-2,5-picrylhydrazyl (DPPH) radicals and cellular antioxidative activity of CWE, and we was investigated in $H_2O_2$-treated or UVB-irradiated HDFs. The CWE effectively scavenged DPPH radicals ($IC_{50}$ $7.03{\pm}0.4{\mu}g/mL$) when compared to the scavenging activities of L-ascorbic acid ($IC_{50}$ $4.69{\pm}0.3{\mu}g/mL$). CWE reduced UVB-induced cellular damage in HS68 cells by MTT assay and inhibited intracellular ROS generation in dose-dependent manner. In addition, CWE also attenuated the elevated levels of 8-isoprostane resulting from UVB-mediated oxidative stress. Collectively, these results suggest that CWE could be a new potential candidate as antioxidant against UVB-induced oxidative stress in HDFs.

• YAKHAK HOEJI
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• v.49 no.2
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• pp.174-179
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• 2005

The human skin is constantly exposed to environmental irritants such as ultraviolet, smoke, chemicals. Free radicals and reactive oxygen species (ROS) caused by these environmen tal facts play critical roles in cellular damage. These irritants are in themselves damaging to the skin structure but they also participate the immensely complex inflammatory reaction. The purpose of this study was to investigate the skin cell protective effect of Campsis grandiflora extract on the UVB-irradiated human dermal fibroblasts (HDFs). We tested free radical and superoxide scavenging effect in vitro. C. grandiflora extracts had potent radical scavenging effect by 82% at $100{\mu}g/ml$, respectively. For testing intracellular ROS scavenging activity the cultured HDFs were analyzed by increase in DCF fluorescence upon exposure to UVB 20 $MJ/cm^2$ after treatment of C.grandiflora extracts. The results showed that oxidation of CM-DCFDA was inhibited by C.grandiflora extracts effectively and C.grandiflora extracts has a potent free radical scavenging activity in UVB- irradiated HDFs. In ROS imaging using confocal microscope we visualized DCF fluorescence in HDFs directly. In conclusion, our results suggest that C.grandiflora can be effectively used for the prevention of UV-induced adverse skin reactions such as radical production, and skin cell damage.

• Proceedings of the Korea Information Processing Society Conference
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• 2015.10a
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• pp.613-616
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• 2015

최근 스마트폰 기기의 보급 및 소셜 서비스 산업의 고도화로 인해, 빅데이터가 등장하였다. 한편 빅데이터에서 효율적으로 정보를 분석하는 대표적인 플랫폼으로 하둡이 존재한다. 하둡은 클러스터 환경에 기반한 우수한 확장성, 장애 복구 기능 및 사용자가 기능을 정의할 수 있는 맵리듀스 프레임워크 등을 지원한다. 아울러 하둡은 개인정보나 위치 데이터 등의 민감한 정보를 보호하기 위해 Kerberos를 통한 사용자 인증 기법을 제공하고, HDFS 압축 코덱을 활용한 AES 코덱 기반 데이터 암호화를 지원하고 있다. 그러나 하둡 기반 소프트웨어를 사용하고 있는 국내 기관 및 기업은 국내 ARIA 데이터 암호화를 적용하지 못하고 있다. 이를 해결하기 위해 본 논문에서는 하둡을 기반으로 ARIA 암호화를 지원하는 HDFS 데이터 암호화 기법을 제안한다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.10a
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• pp.435-437
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• 2016

Hadoop Distributed File System(HDFS) is a file system for distributed processing of big data by replicating data to distributed data nodes. HDFS cluster shows a great scalability up to thousands of nodes, but it assumes a exclusive node cluster with numerous nodes for the big data processing. Various operational-purpose worker systems used by office are hardly considered as a part of cluster. This paper discusses this problem and proposes a dynamic cluster management technique to increase storage capability and analytic performance of hadoop cluster. The propsed technique can add legacy systems to the cluster and can remove them from the cluster dynamically depending on their availability.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.23 no.5
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• pp.831-847
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• 2013

The various types of data are being created in large quantities resulting from the spread of social media and the mobile popularization. Many companies want to obtain valuable business information through the analysis of these large data. As a result, it is a trend to integrate the big data technologies into the company work. Especially, Hadoop is regarded as the most representative big data technology due to its terabytes of storage capacity, inexpensive construction cost, and fast data processing speed. However, the authentication token system of Hadoop Distributed File System(HDFS) for the user authentication is currently vulnerable to the replay attack and the datanode hacking attack. This can cause that the company secrets or the personal information of customers on HDFS are exposed. In this paper, we analyze the possible security threats to HDFS when tokens or datanodes are exposed to the attackers. Finally, we propose the secure authentication protocol in HDFS based on hash chain.

• Journal of Ginseng Research
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• v.44 no.1
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• pp.50-57
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• 2020

Background: The cellular senescence of primary cultured cells is an irreversible process characterized by growth arrest. Restoration of senescence by ginsenosides has not been explored so far. Rg3(S) treatment markedly decreased senescence-associated β-galactosidase activity and intracellular reactive oxygen species levels in senescent human dermal fibroblasts (HDFs). However, the underlying mechanism of this effect of Rg3(S) on the senescent HDFs remains unknown. Methods: We performed a label-free quantitative proteomics to identify the altered proteins in Rg3(S)-treated senescent HDFs. Upregulated proteins induced by Rg3(S) were validated by real-time polymerase chain reaction and immunoblot analyses. Results: Finally, 157 human proteins were identified, and variable peroxiredoxin (PRDX) isotypes were highly implicated by network analyses. Among them, the mitochondrial PRDX3 was transcriptionally and translationally increased in response to Rg3(S) treatment in senescent HDFs in a time-dependent manner. Conclusion: Our proteomic approach provides insights into the partial reversing effect of Rg3 on senescent HDFs through induction of antioxidant enzymes, particularly PRDX3.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.05a
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• pp.479-482
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• 2014

Nowadays open-source hadoop systems have been using widely to efficiently manage a fast-growing big data. Hadoop systems consist of distributed file processing system called HDFS (Hadoop Distributed File System) and distributed parallel processing system called MapReduce. The MapReduce reads and processes big data from HDFS and then processed results are written in HDFS again by the MapReduce. Such a processing method has different system structure respectively according to hadoop version. Therefore, this paper shows analysis results for performance of hadoop systems. For this, we devise a way which monitors hadoop systems and measure occurrence frequency of processes, threads, and variables generated in hadoop system itself using the devised way. So, by using the measured results as analysis indicator, we help the indicator predict inner performance of hadoop systems.

• Proceedings of the Korean Society of Computer Information Conference
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• 2014.07a
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• pp.329-332
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• 2014

클라우드 컴퓨팅이 활성화 됨에 따라 기존의 파일 시스템과는 다른 대용량 파일 처리에 효율적인 분산파일시스템의 요구가 대두 되었다. 그 중에 하둡 분산 파일 시스템(Hadoop Distribute File System, HDFS)은 기존의 분산파일 시스템과는 달리 가용성과 내고장성을 보장하고, 데이터 접근 패턴을 스트리밍 방식으로 지원하여 대용량 파일을 효율적으로 저장할 수 있다. 이러한 장점 때문에, 클라우드 컴퓨팅의 파일시스템으로 대부분 채택하고 있다. 하지만 실제 HDFS 데이터 집합에서 대용량 파일 보다 소용량 파일이 차지하는 비율이 높으며, 이러한 다수의 소 용량 파일은 데이터 처리에 있어 높은 처리비용을 초래 할 뿐 만 아니라 메모리 성능에 악영향을 끼친다. 하지만 소 용량 파일을 프리패칭 함으로서 이러한 문제점을 해결 할 수 있다. HDFS의 데이터 프리페칭은 기존의 데이터 프리페칭의 기법으로는 적용하기 어려워 HDFS를 위한 데이터 프리패칭 기법을 제안한다.

• Proceedings of the Korean Society of Computer Information Conference
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• 2014.07a
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• pp.327-328
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• 2014

클라우드 컴퓨팅 환경에서는 시스템의 성능 및 비용적인 측면에서 정보 공유의 용이성, 장소의 제약성 최소화, 저장 공간의 효율적 사용을 위해 분산 파일시스템을 이용하고 있다. 하지만 현재 HDFS의 복제 정책은 모든 데이터에 3개의 복제복을 유지하도록 하고 있다. 하지만 이러한 정책은 데이터의 중요도, 이용빈도수를 반영하지 못한 정책으로 상이한 서비스 품질 및 신뢰성 수준을 반영하지 못한다. 본 논문에서는 Hidden Markov Model을 이용하여 데이터의 이용 빈도수에 따라 복사본의 개수를 조절하는 알고리즘을 제안한다.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.23 no.5
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• pp.803-813
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• 2013

As the developments of smart devices and social network services, the amount of data has been exploding. The world is facing Big data era. For these reasons, the Big data processing technology which is a new technology that can handle such data has attracted much attention. One of the most representative technologies is Hadoop. Hadoop Distributed File System(HDFS) designed to run on commercial Linux server is an open source framework and can store many terabytes of data. The initial version of Hadoop did not consider security because it only focused on efficient Big data processing. As the number of users rapidly increases, a lot of sensitive data including personal information were stored on HDFS. So Hadoop announced a new version that introduces Kerberos and token system in 2009. However, this system is vulnerable to the replay attack, impersonation attack and other attacks. In this paper, we analyze these vulnerabilities of HDFS security and propose a new protocol which complements these vulnerabilities and maintains the performance of Hadoop.