• Title/Summary/Keyword: Overflow

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A Study on the Protection against Buffer-Overflow Attack using Modifed Linux Kernel (Linux 커널 수정을 통한 Buffer Overflow Attack 방지에 관한 연구)

  • 서정택;최홍민;손태식;김동규
    • Proceedings of the Korean Information Science Society Conference
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    • 2000.10a
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    • pp.635-637
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    • 2000
  • Linux는 다양한 하드웨어 플랫폼을 지원하며, 강력한 네트워크 지원 기능, 다양한 형식의 파일시스템 지원 기능 등 높은 성능을 자랑한다. 그러나, 소스코드의 공개로 인하여 많은 보안상의 취약성을 내포하고 있으며, 최근 이를 이용한 해킹사고가 많이 발생하고 있다. 본 논문에서는 Linux상에 상존하는 보안 취약성을 조사하고, 보안 요구사항을 도출하며, 최근 해킹의 상당부분을 차지하고 있는 Buffer Overflow 공격 방지를 위한 방안으로 커널 수정을 통해 Secure Linux를 개발하고자 한다.

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Study on Numerical Analysis for Structural Safety Verification of Overflow Preventer System for LNG Tank (LNG탱크 수위 넘침 방지 시스템의 구조 안전성을 검증하기 위한 수치 해석에 관한 연구)

  • Ryu, Young-Chun;Park, Young-Chul
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.15 no.4
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    • pp.1801-1806
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    • 2014
  • This paper proposed the design technology for the level meter of the overflow preventer system of LNG storage tank. The parts of LNG ship should be developed under considering the cryogenic environment. Therefore, we proposed the structure of level meter to prevent overflow of LNG tank using the numerical analysis method. The proposed level meter for the overflow preventer is manufactured and the performance is verified through international authorized inspection agency.

Overflow Probability Analysis and Bandwidth Allocation for Traffic Regulated by Dual Leaky Bucket (Dual Leaky Bucket 에 의해 규제되는 트래픽의 오버플로 확률분석과 대역폭 할당방법)

  • Yoon, Y.H.;Lie, C.H.;Hong, J.S.
    • Journal of Korean Institute of Industrial Engineers
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    • v.25 no.3
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    • pp.404-410
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    • 1999
  • A scheme of more exact overflow probability analysis is proposed for traffic regulated by dual leaky bucket. To each regulated traffic stream is allocated bandwidth and buffer independent of other traffic stream and overflow occurs when total bandwidth or buffer allocated to each traffic exceed link capacity or physical buffer size. Ratio of buffer and bandwidth allocated to each traffic stream is assumed to be constant, and this ratio is larger than the ratio of physical buffer and bandwidth due to buffer sharing effect. Numerical experiments show that this sharing effect have significant influence on overflow probability and effective bandwidth.

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USE OF AN ORTHOGONAL PROJECTOR FOR ACCELERATING A QUEUING PROBLEM SOLVER

  • Park, Pil-Seong
    • Journal of applied mathematics & informatics
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    • v.3 no.2
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    • pp.193-204
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    • 1996
  • Overflow queuing models are ofter analyzed by explicitly solving a large sparse singular linear systems arising from Kolmogorov balance equation. The system is often converted into an eigenvalue problem the dominant eigenvector of which is the desired null vector. In this paper we convert an overflow queuing problem the dominant eigenvector of which is the desired null vector. In this paper we convert an overflow queuing problem into an overflow queuing problem into an eigen-value problem into an eigen-value problem of size 1/2 of the original. Then we devise an orthogonal projector that enhances its convergence by removing unsanted eigen-components effectively. Numerical result with some suggestion is given at the end.

Performance Analysis of a Hydrodynamic Separator for Treating Particulate Pollutants in Highway Rainfall Runoff

  • Yu, Jianghua;Yi, Qitao;Kim, Young-Chul
    • Environmental Engineering Research
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    • v.14 no.4
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    • pp.262-269
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    • 2009
  • This study examined the separation characteristics of particles in the rainfall runoff from paved roads using a ${\varphi}7.5$ cm hydrocyclone. The volume fraction and total suspended solids concentrations in the overflow and underflow from the hydrocyclone, as well as the separation efficiency were determined. The results indicated that the overflow volume increased with increasing operational pressure, but decreased with decreasing ratio of underflow outlet to inlet sizes ($D_u/D_i$), while the underflow to overflow volumes showed contrary behavior. The total suspended solid (TSS) concentration ratio between the overflow and inflow ($TSS_{over/in}$) decreased as a function of the operational pressure, while the corresponding ratio of underflow to inflow ($TSS_{under/in}$) increased. There was no visible difference in the $TSS_{over/in}$ with increasing $D_u/D_i$ ratio, but the $TSS_{under/in}$ decreased sharply. The particle removal efficiency was mainly affected by the particle size.

Performance of a Foam Fractionator in a Lab-scale Seawater Recirculating Aquaculture System

  • Peng Lei;Jo Jae-Yoon
    • Fisheries and Aquatic Sciences
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    • v.6 no.4
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    • pp.187-193
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    • 2003
  • The performance of a foam fractionator to remove TAN, $NO_2,\;NO_3$, TSS, protein, and $PO_4-P$ at different superficial air velocities and foam overflow heights was evaluated in a lab-scale seawater recirculating system for culture of Korean rockfish (Sebastes schlegeli). The foam overflow rates increased with the increase of superficial air velocities, but decreased with the increase of foam overflow heights. Concentrations of all the water quality variables in the foam condensates increased with the increase of foam overflow height, but decreased with the increase of superficial air velocities. TSS, protein, and phosphate enrichment factors were within the range of 6.4-39.4, 1.6-7.3 and 1.2-3.9, respectively. Low values of TAN, $NO_2,\;and\;NO_3$ enrichment factors were obtained and they indicate that foam fractionation is rot an effective way to remove dissolved inorganic nitrogen. The calculated maximum daily removal values for TSS and protein were 10.9 and 1.4g, respectively.

Fast Simulation of Overflow Probabilities in Multi-Class Queues with Class-Transition (계층 전이가 가능한 다계층 대기행렬의 빠른 시뮬레이션)

  • Song, Mi-Jung;Bae, Kyung-Soon;Lee, Ji-Yeon
    • Communications for Statistical Applications and Methods
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    • v.16 no.2
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    • pp.217-228
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    • 2009
  • In this paper, we consider a multi-class queueing system in which different classes of customers have different arrival rates, service rates and class-transition probabilities. We use the fast simulation method to estimate the overflow probability and the expected number of customers of each class at the first time the total number of customers hits a high level. We also discuss the overflow probabilities and the expected number of customers at different loads, respectively.

The effect of Combined Sewer Overflows on river's water quality

  • Bae, Hun Kyun
    • Membrane and Water Treatment
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    • v.11 no.1
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    • pp.49-57
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    • 2020
  • The effect of Combined Sewer Overflow on the river system was investigated throughout three preliminary field tests and three main ones. As a result of the study, Combined Sewer Overflow did not affect water qualities on the main stream since the concentration of the main stream did not significantly changed during rainfall events although the water quality of tributaries has rapidly deteriorated due to the influence of the Combined Sewer Overflow during rainfall events. The main cause of the result is that the flow rate of the tributaries is considerably lower than that of the main stream, so that the tributaries with deteriorated water quality during rainfall events did not significantly affect the quality of the actual main stream. Therefore, the water quality of the Kumho River is more affected by the wastewater treatment facilities that discharges water continuously to the main stream than pollutants from non-point pollution sources during rainfall events. As a result, managements for discharges from wastewater treatment facilities should be strengthened in order to improve the water quality of the river.

High-Performance Reversible Data Hiding with Overflow/Underflow Avoidance

  • Yang, Ching-Yu;Hu, Wu-Chih
    • ETRI Journal
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    • v.33 no.4
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    • pp.580-588
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    • 2011
  • This paper proposes reversible data hiding using minimum/maximum preserved overflow/underflow avoidance (MMPOUA). The proposed MMPOUA algorithm consists of three main steps. These steps include the minimum (or maximum) pixel fixing, pixel squeezing, and pixel isolation. The aims of pixel fixing are to keep the minimum (or maximum) pixel of a host block unchanged and prevent the occurrence of overflow/underflow. Both the pixel squeezing and pixel isolation supply hiding storage while keeping the amount of distortion low. The proposed method can avoid (or significantly reduce) the overhead bits used to overcome overflow/underflow issues. At an embedding rate of 0.15 bpp, the proposed algorithm can achieve a PSNR value of 48.52 dB, which outperforms several existing reversible data hiding schemes. Furthermore, the algorithm performed well in a variety of images, including those in which other algorithms had difficulty obtaining good hiding storage with high perceived quality.

The Blocking of buffer overflow based attack for Linux kernel (리눅스 시스템의 버퍼 오버플로우 공격 대응 기법)

  • Kim, Jeong-Nyeo;Jeong, Gyo-Il;Lee, Cheol-Hun
    • The KIPS Transactions:PartA
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    • v.8A no.4
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    • pp.385-390
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    • 2001
  • In this paper, we describe a blocking method of buffer overflow attack for secure operating system. Our team developed secure operating system using MAC and ACL access control added on Linux kernel. We describe secure operating system (SecuROS) and standardized Secure utility and library. A working prototype able to detect and block buffer overflow attack is available.

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