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A CPU Usage Control Mechanism for Processes with Execution Resource for Mitigating CPU DoS Attack
Toshihiro Tabata,Satoshi Hakomori,Kazutoshi Yokoyama,Hideo Taniguchi 보안공학연구지원센터 2007 International Journal of Smart Home Vol.1 No.2
In a ubiquitous environment, the hardware resources are limited; thus, an appropriate resource management mechanism is required for guaranteeing its processing activity. However, most operating systems (OSs) lack an access control mechanism for CPU resources to guarantee satisfactory processing and to safeguard the system from malicious attacks that affect the CPU resources, resulting in denial of service (DoS). Access control is not intended for CPU resources, which are important for the execution of a program. As a result, OSs cannot control the usage ratio of CPU resources. In this paper, we propose an access control model for CPU resources based on an execution resource. The proposed model can control the usage ratio of CPU resources appropriately for each user and each program domain. This execution resource can be applied to mitigate DoS attacks. In order to evaluate the effectiveness of the proposed method, we describe the results of a basic performance experiment and a DoS simulation experiment employing the Apache web server. From the results, we show that the proposed method can mitigate DoS attacks and does not have bad effects upon the performance of a target service.
Park, Seung-Yeol,Yoon, Seon-Joo,Jeong, Yeon-Tae,Kim, Jin-Man,Kim, Ji-Yeon,Bernert, Bradford,Ullman, Thomas,Itzkowitz, Steven H.,Kim, Jung-Hoe,Hakomori, Sen-itiroh Wiley Subscription Services, Inc., A Wiley Company 2010 International journal of cancer: Journal internati Vol.126 No.1
<P>N-glycosylation status of purified β-haptoglobin from sera of 17 patients, and from sera of 14 healthy volunteer subjects, was compared by blotting with various lectins and antibodies. Patients in this study were diagnosed as having colon cancer through histological examination of each tumor tissue by biopsy. Blotting index of serum β-haptoglobin with Aleuria aurantia lectin (AAL) was clearly higher for cancer patients than for healthy subjects. No such distinction was observed for blotting with three other lectins and two monoclonal antibodies. To determine tumor-associated reactivity of AAL binding as compared to inflammatory processes in colonic tissues, β-haptoglobin separated from sera of 5 patients with Crohn's disease (CD), and 4 patients with ulcerative colitis (UC), was studied. All these cases, except one case of UC, showed AAL index lower than that in cancer cases, similarly to healthy subjects. The higher AAL binding of β-haptoglobin in colon cancer patients than in healthy subjects appeared to be due to α-L-fucosyl residue, since it was eliminated by bovine kidney α-fucosidase treatment. N-linked glycans of serum haptoglobin from colon cancer patients vs. healthy subjects were released by N-glycanase, fluorescence-labeled, and subjected to normal-phase high performance liquid chromatography (NP-HPLC). Glycan structures were determined based on glucose unit (GU) values and their changes upon sequential treatment with various exoglycosidases. Glycosyl sequences and their branching status of glycans from 14 cases of serum β-haptoglobin were characterized. The identified glycans were sialylated or nonsialylated, bi-antennary or tri-antennary structures, with or without terminal fucosylation.</P>
Seung-Yeol Park,Seon-Joo Yoon,Jin-Man Kim,Ji-Yeon Kim,Bradford Bernert,Thomas Ullman,Steven H. Itzkowitz,Jung-Hoe Kim,Sen-itiroh Hakomori 한국당과학회 2009 한국당과학회 학술대회 Vol.2009 No.1
The glycosyl epitope dimeric Lea (Lea-on-Lea), defined by mouse monoclonal antibody NCC-ST-421, was identified previously as tumor-associated antigen, expressed highly in various human cancer tissues and cell lines derived therefrom, but with minimal expression in various normal tissues. In the present study, we observed clearly higher expression of this epitope, defined by ST421, in β-haptoglobin (β-Hap) from sera of patients with colorectal cancer, compared to normal, healthy subjects or patients with chronic inflammatory processes (Crohn\'s disease, ulcerative colitis). We focused, therefore, on biochemical characterization of glycosyl epitope status expressed in β-Hap. We concluded that the dimeric Lea epitope is carried by O-linked but not by N-linked structure, based on the following observations: (i) Strong reactivity of Colo205 supernatant with ST421 was reduced clearly by pre-incubation of cells with benzyl-α -GalNAc. (ii) Treatment of β-Hap with α-L-fucosidase reduced its reactivity with ST421, but did not affect its reactivity with anti-Hap antibody. In contrast, treatment of purified β-Hap with PNGase F, which releases N-linked glycans, had no effect on reactivity with ST421, but changed molecular mass from 40 kDa to 30 kDa.