• Title/Summary/Keyword: X-MAC

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Research on Mac OS X Physical Memory Analysis (Mac OS X 물리 메모리 분석에 관한 연구)

  • Lee, Kyeong-Sik;Lee, Sang-Jin
    • Journal of the Korea Institute of Information Security & Cryptology
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    • v.21 no.4
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    • pp.89-100
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    • 2011
  • Physical memory analysis has been an issue on a field of live forensic analysis in digital forensics until now. It is very useful to make the result of analysis more reliable, because record of user behavior and data can be founded on physical memory although process is hided. But most memory analysis focuses on windows based system. Because the diversity of target system to be analyzed rises up, it is very important to analyze physical memory based on other OS, not Windows. Mac OS X, has second market share in Operating System, is operated by loading kernel image to physical memory area. In this paper, We propose a methodology for physical memory analysis on Mac OS X using symbol information in kernel image, and acquire a process information, mounted device information, kernel information, kernel extensions(eg. KEXT) and system call entry for detecting system call hooking. In additional to the methodology, we prove that physical memory analysis is very useful though experimental study.

Measurements of Mid-arm Circumference(MAC) and Mid-arm Circumference/Head Circumference (MAC/HC) Ratio as Indices of Nutritional Status in Newborn Infants (신생아 신체 발육지표로서의 중앙 상완위 및 중앙 상완위와 두위비의 측정)

  • Lee, Jae-Jun;Lee, Kyung-A;Lee, Young-Hwan;Shin, Son-Moon
    • Journal of Yeungnam Medical Science
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    • v.11 no.1
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    • pp.160-166
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    • 1994
  • Mid-arm circumference and mid-arm circumference/head circumference ratio(MAC/HC) were measured in 207 AGA(appropriate for gestational age) infants delivered at 26 to 42 weeks of gestation from January 1990 to December 1993 in Yeungnam University Hospital, Taegu, Korea. There were linear relationships between MACs and MAC/HC ratios and gestational age(MAC : y=0.3181x - 2.2069, r=0.81, p<0.001 ; MAC/HC ratio : y=0.0049x+0.1128, r=0.62, ; < 0.001). Using standard curves of MAC and MAC/HC ratio according to the gestational age, measurement of MAC or MAC/HC ratio can be a noninvasive, simple method to evaluate the intrauterine growth of newborn infants and the nutritional status of growing premature infants.

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A High Performance Transmission Method for Massively Delivering Multimedia Data in WMSN (무선 멀티미디어 센서 네트워크(WMSN) 환경에서 멀티미디어 데이터 전송을 위한 대용량 전송 기법에 대한 연구)

  • Lee, Jae-Ho;Eom, Doo-Seop
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.37A no.11
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    • pp.903-917
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    • 2012
  • For transmitting sensed data, wireless sensor networks have been developed and researched for the improvement of energy efficiency, hence, many MAC protocols in WSN employ the duty cycle mechanism. Since the progressed development of the low power transceiver and processor let the high energy efficiency come true, the delivery of the multimedia data which occurs in area of sensor work should be needed to provide supplemental information. In this paper, we design a new scheme for massive transmission of large multimedia data where the duty cycle is used in contention based MAC protocol, for WMSN. The proposed scheme can be applied into the previous duty cycle mechanism because it provides two operation between normal operation and massive transmission operation. Measuring the buffer status of sender and the condition of current radio channel can be criteria for the decision of the above two operations. This paper shows the results of the experiment by performing the simulation. The target protocol of the experiment is X-MAC which is contention based MAC protocol for WSN. And two approaches, both X-MAC which operates only duty cycle and X-MAC which operates combined massive transmission scheme, are used for the comparative experiment.

SPMC-MAC : Slim Preamble Multi-Channel MAC Protocol with Transmission Power Control in Wireless Sensor Networks (무선 센서 네트워크에서 다중 채널과 전송세기 제어를 이용한 맥 프로토콜)

  • Yoon, Jang-Muk;Bahk, Sae-Woong
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.33 no.10B
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    • pp.876-884
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    • 2008
  • In this paper, we propose an asynchronous MAC protocol to minimize energy usage and to maximize data throughput for a wireless sensor network in multi channel environments. Our proposed SPMC-MAC (Slim Preamble Multi-Channel Media Access Control) adopts the preamble sliming mechanism proposed in [6] that takes advantage of the knowledge about the wakeup time of the receiver node. The preamble contains the receiver's ID and a randomly selected channel ID for data communication, and it is transmitted over a dedicated common channel. The power control has the benefit of keeping an appropriate number of nodes with the communication range, resulting in reduced collision and interference. We compare our SPMC-MAC and X-MAC extensively in terms of energy consumption and throughput using mathematical analysis and simulation.

SB-MAC : Energy efficient Sink node Based MAC protocol for Wireless Sensor Networks (무선 센서 네트워크 에서 에너지 효율적인 싱크노드 기반 MAC 프로토콜)

  • Jeon, Jun-Heon;Kim, Seong-Cheol
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.18 no.1
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    • pp.177-182
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    • 2014
  • In this paper, we propose an energy efficient sink node based MAC protocol for Wireless Sensor Networks (WSNs). The proposed sink node-based MAC (SB-MAC) protocol uses a RB(rapid beacon) frame to save sender's energy consumption and to reduce transmission delay. The RB frame is a modified IEEE 802.15.4 beacon frame. The RB frame contains the length of the sender nodes data. Using this information other nodes except sender and receiver nodes can be stay sleep mode long time to reduce energy consumption. Results have shown that the SB-MAC protocol outperformed other protocols like X-MAC and RI-MAC in terms of packet delivery delay and energy consumption. The SB-MAC protocol is especially energy efficient for the networks with one sink node and many senders.

A Wireless MAC Scheduler based on Video Traces for One-to-one Video-on-demand Services in CDMA2000 1xEV-DO (CDMA2000 1xEV-DO 이동통신 망에서 일대일 주문형 비디오 서비스를 위한 비디오 트레이스 기반 무선 MAC 스케줄러)

  • Pyun, Ki-Hyun
    • Journal of KIISE:Information Networking
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    • v.36 no.4
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    • pp.351-359
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    • 2009
  • A wireless MAC scheduler for CDMA2000 IxEV-DO that provides a high level of quality-of-service(QoS) for video-on-demand(VOD) applications while achieving a reasonable level of system throughput is proposed, The proposed scheduler that exists in the MAC layer utilizes the video data information that resides in the application layer such that it improves the QoS for VOD applications. We show by simulations that our approach is better than the previous scheduler which is also based on video traces for VBR videos that have high variability between video frames.

A Study on AI-based MAC Scheduler in Beyond 5G Communication (5G 통신 MAC 스케줄러에 관한 연구)

  • Muhammad Muneeb;Kwang-Man Ko
    • Proceedings of the Korea Information Processing Society Conference
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    • 2024.05a
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    • pp.891-894
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    • 2024
  • The quest for reliability in Artificial Intelligence (AI) is progressively urgent, especially in the field of next generation wireless networks. Future Beyond 5G (B5G)/6G networks will connect a huge number of devices and will offer innovative services invested with AI and Machine Learning tools. Wireless communications, in general, and medium access control (MAC) techniques were among the fields that were heavily affected by this improvement. This study presents the applications and services of future communication networks. This study details the Medium Access Control (MAC) scheduler of Beyond-5G/6G from 3rd Generation Partnership (3GPP) and highlights the current open research issues which are yet to be optimized. This study provides an overview of how AI plays an important role in improving next generation communication by solving MAC-layer issues such as resource scheduling and queueing. We will select C-V2X as our use case to implement our proposed MAC scheduling model.

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Polling Scheme Adapted to Unbalanced Traffic Load in IEEE 802.11x Wireless LAN (IEEE 802.11x Wireless LAN에서 불균형한 트래픽 부하에 적응적인 폴링 기법)

  • Shin Soo-Young;Park Soo-Hyun
    • The KIPS Transactions:PartC
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    • v.12C no.3 s.99
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    • pp.387-394
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    • 2005
  • Every MAC (Medium Access Control) sub-layers of IEEE 802.11x, including IEEE 802.11e, defines Connection-based and CF (Contention Free)-based service functions in common. In this paper, a New-CF method is proposed. In the proposed method, conventional Round Robin method, which is used as a polling method by IEEE 802.11x PCF (Point Coordination Function) or IEE 802.11e HCCA, is modified to give weights to channels with heavier traffic load and to provide those weighted channels with more services. Based on NS-2 simulations, it is verified the proposed method shows better throughput in general, particularly under unbalanced traffic load conditions.

Enhancing Gamma-Neutron Shielding Effectiveness of Polyvinylidene Fluoride for Potent Applications in Nuclear Industries: A Study on the Impact of Tungsten Carbide, Trioxide, and Disulfide Using EpiXS, Phy-X/PSD, and MCNP5 Code

  • Ayman Abu Ghazal;Rawand Alakash;Zainab Aljumaili;Ahmed El-Sayed;Hamza Abdel-Rahman
    • Journal of Radiation Protection and Research
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    • v.48 no.4
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    • pp.184-196
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    • 2023
  • Background: Radiation protection is crucial in various fields due to the harmful effects of radiation. Shielding is used to reduce radiation exposure, but gamma radiation poses challenges due to its high energy and penetration capabilities. Materials and Methods: This work investigates the radiation shielding properties of polyvinylidene fluoride (PVDF) samples containing different weight fraction of tungsten carbide (WC), tungsten trioxide (WO3), and tungsten disulfide (WS2). Parameters such as the mass attenuation coefficient (MAC), half-value layer (HVL), mean free path (MFP), effective atomic number (Zeff), and macroscopic effective removal cross-section for fast neutrons (ΣR) were calculated using the Phy-X/PSD software. EpiXS simulations were conducted for MAC validation. Results and Discussion: Increasing the weight fraction of the additives resulted in higher MAC values, indicating improved radiation shielding. PVDF-xWC showed the highest percentage increase in MAC values. MFP results indicated that PVDF-0.20WC has the lowest values, suggesting superior shielding properties compared to PVDF-0.20WO3 and PVDF-0.20WS2. PVDF-0.20WC also exhibited the highest Zeff values, while PVDF-0.20WS2 showed a slightly higher increase in Zeff at energies of 0.662 and 1.333 MeV. PVDF-0.20WC has demonstrated the highest ΣR value, indicating effective shielding against fast neutrons, while PVDF-0.20WS2 had the lowest ΣR value. The Monte Carlo N-Particle Transport version 5 (MCNP5) simulations showed that PVDF-xWC attenuates gamma radiation more than pure PVDF, significantly decreasing the dose equivalent rate. Conclusion: Overall, this research provides insights into the radiation shielding properties of PVDF mixtures, with PVDF-xWC showing the most promising results.

Determination of Air-dry Density of Wood with Polychromatic X-ray and Digital Detector

  • Kim, Chul-Ki;Kim, Kwang-Mo;Lee, Sang-Joon;Lee, Jun-Jae
    • Journal of the Korean Wood Science and Technology
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    • v.45 no.6
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    • pp.836-845
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    • 2017
  • Gravimetric method is usually used to evaluate air-dry density, which is governing physical or mechanical properties of wood. Although it had high evaluation accuracy, the method is time consuming process. Thus, this study was conducted to estimate air-dry density of wood with high accuracy by using polychromatic X-ray and digital detector as alternative of gravimetric method. To quantify polychromatic X-ray projection for evaluating air-dry density, Lambert-Beer's law with the integral value of probability function was used. The integral value was used as weighting factor in the law, and it was determined by conducting simple test at various penetration depths and tube voltage. Mass attenuation coefficient (MAC) of wood also calculated by investigating polychromatic X-ray projection according to species, penetration depth and tube voltage. The species had not an effect on change of MAC. Finally, an air-dry density of wood was estimated by applying the integral value, MAC and Lambert-Beer's law to polychromatic X-ray projection. As an example, the relation of the integral value (${\alpha}$) according to penetration depth (t, cm) at tube voltage of 35 kV was ${\alpha}=-0.00091t{\times}0.0184$ while the regression of the MAC (${\mu}$, $cm^2/g$) was ${\mu}=0.5414{\exp}(-0.0734t)$. When calculation of root mean squared error (RMSE) was performed to check the estimation accuracy, RMSE at 35, 45 and 55 kV was 0.010, 0.013 and $0.009g/cm^3$, respectively. However, partial RMSE in relation to air-dry density was varied according to tube voltage. The partial RMSE below air-dry density of $0.41g/cm^3$ was $0.008g/cm^3$ when tube voltage of 35 kV was used. Meanwhile, the partial RMSE above air-dry density of $0.41g/cm^3$ decreased as tube voltage increased. It was conclude that the accuracy of estimation with polychromatic X-ray and digital detector was quite high if the integral value and MAC of wood were determined precisely or a condition of examination was chosen properly. It was seemed that the estimation of air-dry density by using polychromatic X-ray system can supplant the gravimetric method.