• 제목/요약/키워드: Access Resistance

검색결과 163건 처리시간 0.031초

암반 비탈면의 인장균열 위치 선정에 관한 사례 연구 (Case Study on Location of Possible Tension Crack in Rock Slope)

  • 전병곤;김지성;강기천
    • 한국지반공학회논문집
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    • 제37권3호
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    • pp.5-17
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    • 2021
  • 본 연구는 도로건설공사 중 발생한 암반 비탈면의 인장균열 발생원인 및 대책 방안을 소개하고자 한다. 확장 가능한 인장균열 범위를 조사하기 위하여 전기비저항 탐사를 수행하여 암반의 연약대 분포 여부를 조사한 결과, 인장균열이 발생한 부체도로 하단에 저비저항대가 나타나며 굴착 비탈면 상단 부근에 저비저항대가 분포하는 것으로 확인되었다. 따라서 발생 가능한 인장균열 위치를 굴착 비탈면 상단으로 결정하여 보강 설계를 수행하였고, 보강방안으로 앵커와 억지말뚝 2열이 제안되었고 비탈면 안정해석을 통하여 보강 이후 허용안전율을 만족하는 것으로 나타났다.

Apply evolved grey-prediction scheme to structural building dynamic analysis

  • Z.Y. Chen;Yahui Meng;Ruei-Yuan Wang;Timothy Chen
    • Structural Engineering and Mechanics
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    • 제90권1호
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    • pp.19-26
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    • 2024
  • In recent years, an increasing number of experimental studies have shown that the practical application of mature active control systems requires consideration of robustness criteria in the design process, including the reduction of tracking errors, operational resistance to external disturbances, and measurement noise, as well as robustness and stability. Good uncertainty prediction is thus proposed to solve problems caused by poor parameter selection and to remove the effects of dynamic coupling between degrees of freedom (DOF) in nonlinear systems. To overcome the stability problem, this study develops an advanced adaptive predictive fuzzy controller, which not only solves the programming problem of determining system stability but also uses the law of linear matrix inequality (LMI) to modify the fuzzy problem. The following parameters are used to manipulate the fuzzy controller of the robotic system to improve its control performance. The simulations for system uncertainty in the controller design emphasized the use of acceleration feedback for practical reasons. The simulation results also show that the proposed H∞ controller has excellent performance and reliability, and the effectiveness of the LMI-based method is also recognized. Therefore, this dynamic control method is suitable for seismic protection of civil buildings. The objectives of this document are access to adequate, safe, and affordable housing and basic services, promotion of inclusive and sustainable urbanization, implementation of sustainable disaster-resilient construction, sustainable planning, and sustainable management of human settlements. Simulation results of linear and non-linear structures demonstrate the ability of this method to identify structures and their changes due to damage. Therefore, with the continuous development of artificial intelligence and fuzzy theory, it seems that this goal will be achieved in the near future.

스마트 카드 및 동적 ID 기반 멀티서버 원격 사용자 인증 프로토콜의 취약점 분석 (Vulnerability Analysis of Remote Multi-Server User Authentication System Based on Smart Card and Dynamic ID)

  • 권순형;변해원;최윤성
    • 융합보안논문지
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    • 제23권4호
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    • pp.43-52
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    • 2023
  • 많은 기업과 단체들은 원격 접근을 위해 스마트카드 기반 사용자 인증을 사용한다. 그 동안 다양한 연구를 통하여 사용자와 서버 간의 연결을 보호하기 위해 분산된 다중 서버 환경에 대한 동적 ID 기반 원격 사용자 인증 프로토콜들이 제안되었다. 그 중, Qiu 등은 상호 인증 및 키 동의, 사용자 익명성, 다양한 종류의 공격에 대한 저항을 제공하는 효율적인 스마트카드 기반 원격 사용자 인증 프로토콜을 제안하였다. 이후, Andola 등은 Qiu 등이 제안된 인증 프로토콜에 대한 다양한 취약점을 찾아내었고, 그들의 인증 프로토콜에 대한 결점을 극복하고 사용자가 서버에 로그인하기를 원할 때마다 로그인하기 전에 사용자ID가 동적으로 변경되는 향상된 인증 프로토콜을 제안하였다. 본 논문에서는 Andola 등이 제안한 프로토콜의 동작 과정 및 취약점을 분석하여, Andola 등이 제안한 프로토콜이 offline smart card attack, dos attack, lack of perfect forward secrecy, session key attack에 취약하다는 것을 밝혔다.

High Performance Flexible Inorganic Electronic Systems

  • 박귀일;이건재
    • 한국진공학회:학술대회논문집
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    • 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
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    • pp.115-116
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    • 2012
  • The demand for flexible electronic systems such as wearable computers, E-paper, and flexible displays has increased due to their advantages of excellent portability, conformal contact with curved surfaces, light weight, and human friendly interfaces over present rigid electronic systems. This seminar introduces three recent progresses that can extend the application of high performance flexible inorganic electronics. The first part of this seminar will introduce a RRAM with a one transistor-one memristor (1T-1M) arrays on flexible substrates. Flexible memory is an essential part of electronics for data processing, storage, and radio frequency (RF) communication and thus a key element to realize such flexible electronic systems. Although several emerging memory technologies, including resistive switching memory, have been proposed, the cell-to-cell interference issue has to be overcome for flexible and high performance nonvolatile memory applications. The cell-to-cell interference between neighbouring memory cells occurs due to leakage current paths through adjacent low resistance state cells and induces not only unnecessary power consumption but also a misreading problem, a fatal obstacle in memory operation. To fabricate a fully functional flexible memory and prevent these unwanted effects, we integrated high performance flexible single crystal silicon transistors with an amorphous titanium oxide (a-TiO2) based memristor to control the logic state of memory. The $8{\times}8$ NOR type 1T-1M RRAM demonstrated the first random access memory operation on flexible substrates by controlling each memory unit cell independently. The second part of the seminar will discuss the flexible GaN LED on LCP substrates for implantable biosensor. Inorganic III-V light emitting diodes (LEDs) have superior characteristics, such as long-term stability, high efficiency, and strong brightness compared to conventional incandescent lamps and OLED. However, due to the brittle property of bulk inorganic semiconductor materials, III-V LED limits its applications in the field of high performance flexible electronics. This seminar introduces the first flexible and implantable GaN LED on plastic substrates that is transferred from bulk GaN on Si substrates. The superb properties of the flexible GaN thin film in terms of its wide band gap and high efficiency enable the dramatic extension of not only consumer electronic applications but also the biosensing scale. The flexible white LEDs are demonstrated for the feasibility of using a white light source for future flexible BLU devices. Finally a water-resist and a biocompatible PTFE-coated flexible LED biosensor can detect PSA at a detection limit of 1 ng/mL. These results show that the nitride-based flexible LED can be used as the future flexible display technology and a type of implantable LED biosensor for a therapy tool. The final part of this seminar will introduce a highly efficient and printable BaTiO3 thin film nanogenerator on plastic substrates. Energy harvesting technologies converting external biomechanical energy sources (such as heart beat, blood flow, muscle stretching and animal movements) into electrical energy is recently a highly demanding issue in the materials science community. Herein, we describe procedure suitable for generating and printing a lead-free microstructured BaTiO3 thin film nanogenerator on plastic substrates to overcome limitations appeared in conventional flexible ferroelectric devices. Flexible BaTiO3 thin film nanogenerator was fabricated and the piezoelectric properties and mechanically stability of ferroelectric devices were characterized. From the results, we demonstrate the highly efficient and stable performance of BaTiO3 thin film nanogenerator.

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Rapid Molecular Diagnosis using Real-time Nucleic Acid Sequence Based Amplification (NASBA) for Detection of Influenza A Virus Subtypes

  • Lim, Jae-Won;Lee, In-Soo;Cho, Yoon-Jung;Jin, Hyun-Woo;Choi, Yeon-Im;Lee, Hye-Young;Kim, Tae-Ue
    • 대한의생명과학회지
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    • 제17권4호
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    • pp.297-304
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    • 2011
  • Influenza A virus of the Orthomyxoviridae family is a contagious respiratory pathogen that continues to evolve and burden in the human public health. It is able to spread efficiently from human to human and have the potential to cause pandemics with significant morbidity and mortality. It has been estimated that every year about 500 million people are infected with this virus, causing about approximately 0.25 to 0.5 million people deaths worldwide. Influenza A viruses are classified into different subtypes by antigenicity based on their hemagglutinin (HA) and neuraminidase (NA) proteins. The sudden emergence of influenza A virus subtypes and access for epidemiological analysis of this subtypes demanded a rapid development of specific diagnostic tools. Also, rapid identification of the subtypes can help to determine the antiviral treatment, because the different subtypes have a different antiviral drug resistance patterns. In this study, our aim is to detect influenza A virus subtypes by using real-time nucleic acid sequence based amplification (NASBA) which has high sensitivity and specificity through molecular beacon. Real-time NASBA is a method that able to shorten the time compare to other molecular diagnostic tools and is performed by isothermal condition. We selected major pandemic influenza A virus subtypes, H3N2 and H5N1. Three influenza A virus gene fragments such as HA, NA and matrix protein (M) gene were targeted. M gene is distinguished influenza A virus from other influenza virus. We designed specific primers and molecular beacons for HA, NA and M gene, respectively. In brief, the results showed that the specificity of the real-time NASBA was higher than reverse transcription polymerase chain reaction (RT-PCR). In addition, time to positivity (TTP) of this method was shorter than real-time PCR. This study suggests that the rapid detection of neo-appearance pandemic influenza A virus using real-time NASBA has the potential to determine the subtypes.

3상 22.9/3.3kV 유입변압기의 소손패턴 해석 및 발화원인 판정에 관한 연구 (Study on the Damage Pattern Analysis of a 3 Phase 22.9/3.3kV Oil Immersed Transformer and Judgment of the Cause of Its Ignition)

  • 최충석
    • 전기학회논문지
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    • 제60권6호
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    • pp.1274-1279
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    • 2011
  • The purpose of this paper is to present the manufacturing defect and damage pattern of a 3 phase 22.9/3.3kV oil immersed transformer, as well as to present an objective basis for the prevention of a similar accident and to secure data for the settlement of PL related disputes. It was found that in order to prevent the occurrence of accidents to transformers, insulating oil analysis, thermal image measurement, and corona discharge diagnosis, etc., were performed by establishing relevant regulation. The result of analysis performed on the external appearance of a transformer to which an accident occurred, the internal insulation resistance and protection system, etc., showed that most of the analysis items were judged to be acceptable. However, it was found that the insulation characteristics between the primary winding and the enclosure, those between the ground and the secondary winding, and those between the primary and secondary windings were inappropriate due to an insulating oil leak caused by damage to the pressure relief valve. From the analysis of the acidity values measured over the past 5 years, it is thought that an increase in carbon dioxide (CO2) caused an increase in the temperature inside the transformer and the increase in the ethylene gas increased the possibility of ignition. Even though 17 years have passed since the transformer was installed, it was found that the system's design, manufacture, maintenance and management have been performed well and the insulating paper was in good condition, and that there was no trace of public access or vandalism. However, in the case of transformers to which accidents have occurred, a melted area between the upper and the intermediate bobbins of the W-phase secondary winding as well as between its intermediate and lower bobbins. It can be seen that a V-pattern was formed at the carbonized area of the transformer and that the depth of the carbonization is deeper at the upper side than the lower side. In addition, it was found that physical bending and deformation occurred inside the secondary winding due to non-uniform pressure while performing transformer winding work. Therefore, since it is obvious that the accident occurred due to a manufacturing defect (winding work defect), it is thought that the manufacturer of the transformer is responsible for the accident and that it is lawful for the manufacture to investigate and prove the concrete cause of the accident according to the Product Liability Law (PLL).

AFTL: Hot Data 검출기를 이용한 적응형 플래시 전환 계층 (AFTL: An Efficient Adaptive Flash Translation Layer using Hot Data Identifier for NAND Flash Memory)

  • 윤현식;주영도;이동호
    • 한국정보과학회논문지:시스템및이론
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    • 제35권1호
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    • pp.18-29
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    • 2008
  • 최근 NAND 플래시 메모리는 빠른 접근속도, 저 전력 소모, 높은 내구성, 작은 부피, 가벼운 무게 등으로 차세대 대용량 저장 매체로 각광 받고 있다. 그러나 이런 플래시 메모리는 데이타를 기록하기 전에 기존의 데이타 영역이 지워져 있어야 한다는 제약이 있으며, 비대칭적인 읽기, 쓰기, 삭제 연산의 처리속도 각 블록당 최대 소거 횟수 제한과 같은 특징들을 지닌다. 위와 같은 단점을 극복하고 NAND플래시 메모리를 효율적으로 사용하기 위하여. 다양한 플래시 전환 계층 제안되어 왔다. 기러나 기존의 플래시 전환 계층들은 Hot data라 불리는 빈번히 접근되는 데이타에 의해서 잦은 겹쳐쓰기 요구가 발생되며, 이는 급격한 성능 저하를 가져 온다. 본 논문에서는 Hot data 검출기를 이용하여, 매우 적은 양의 데이타인 Hot data를 검출한 후, 검출된 Hot data는 섹터사상 기법을 적용시키고, 나머지 데이타인 Cold data는 로그 기반 블록 사상 기법을 적용시키는 적응형 플래시 전환 계층(AFTL)을 제안한다. AFTL은 불필요한 삭제, 쓰기, 읽기 연산을 최소화시켰으며, 기존의 플래시 전환 계층과의 비교 측정을 통하여 성능의 우수성을 보인다.

바이오 상변화 Template 위한 전극기판 개발 (Developing the Electrode Board for Bio Phase Change Template)

  • 리학철;윤중림;이동복;김수경;김기범;박영준
    • Korean Chemical Engineering Research
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    • 제47권6호
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    • pp.715-719
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    • 2009
  • 본 연구에서는 DNA 정보를 상변화 물질의 전기저항 변화특성으로 검출할 수 있는 상변화 전극 기판을 개발하였다. 이를 위해 반도체 공정에서 사용하는 Al을 사용하여 전극 기판을 제작하였다. 하지만 주사전자현미경을 이용하여 Al 전극의 단면 상태를 확인해 본 결과 PETEOS(plasma enhanced tetraethyoxysilane) 내에서 보이드(void)가 발생하여 후속공정인 에치백과 세정공정 분위기에 과도하게 노출되어 심하게 손상되어 전극과 PETEOS 사이에 홀(hole)로 변형된다. 이 문제점을 해결하기 위하여 에치백 및 세정 공정을 진행하지 않으면서 $Ge_2Sb_2Te_5$(GST) 박막의 단차피복성(stepcoverage)을 좋게 할 수 있고, 열역학적으로 GST 박막과의 반응성을 고려했을 때 안정적이면서 비저항이 낮은 TiN 재료를 사용하여 상변화 전극 기판을 제작하였다. 주사전자현미경을 통하여 전극의 단면의 상태를 관찰하였으며 TiN 전극과 GST 박막이 정상적으로 연결되어 있는 것을 확인하였다. 또한 저항측정 장비를 사용하여 TiN 상변화 전극 기판 위에 증착된 GST의 비정질과 결정질의 저항을 측정하였고, GST의 비정질과 결정질저항의 차이는 약 1,000배 정도로 신호를 검출하는데 충분함을 확인하였다.

Utilizing chromosome segment substitution lines (CSSLs) to evaluate developmental plasticity of root systems in hardpan penetration and deep rooting triggered by soil moisture fluctuations in rice

  • Nguyen, Thi Ngoc Dinh;Suralta, Roel R.;Mana, Kano-Nakata;Mitsuya, Shiro;Stella, Owusu Nketia;Kabuki, Takuya;Yamauchi, Akira
    • 한국작물학회:학술대회논문집
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    • 한국작물학회 2017년도 9th Asian Crop Science Association conference
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    • pp.321-321
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    • 2017
  • Water availability in rainfed lowlands (RFL) is strongly affected by climate change. In RFL, rice plants are exposed to soil moisture fluctuations (SMF) but rarely to simple progressive drought as widely believed. Typical RFL field is characterized by a about 5-cm thick high bulk density hardpan layer underneath the cultivated layer at about 20 cm depth that impedes deep root development. Root system has the ability to develop in response to changes in SMF, known as phenotypic plasticity. We hypothesized that genotypes that can adapt to RFL have root plasticity. The roots can sharply respond to re-wetting after drought period and thus penetrate the hardpan layer when the hardpan is wet and so becomes relatively soft, and thus access water under the hardpan. This study aimed to identify CSSLs derived from a cross between Sasanishiki and Habataki which adapted to such RFL conditions. We used 39 CSSLs together with the parent Sasanishiki, which were grown in hydroponics and pot under transient soil moisture stresses (drought and then rewatering), and compared with continuously well-watered (WW) (control) up to 14 days after sowing (DAS), and 20 DAS, respectively. Based on the results of hydroponics and pot experiments, we selected a few lines, which were grown in the soil-filled rootbox with artificial hardpan layer and without artificial hardpan. For the rootbox without artificial hardpan, plants were grown under WW and transient soil moisture stresses for 49 DAS. While the rootbox with artificial hardpan, the plants were grown under WW (control) and SMF (WW up to 21 DAS, 1st drought (22-36 DAS), rewatering (37-44 DAS), and followed by 2nd drought (45-58 DAS)). Among the 39 CSSLs, only CSSL439 (SL39) consistently showed significantly higher shoot dry weight (SDW) than Sasanishiki under transient soil moisture stress conditions as well as SMF conditions in all the experiments. Furthermore, under WW, SL39 consistently showed no significant differences from Sasanishiki in shoot and root growth in most of traits examined. SL39 showed significantly greater total root length (TRL) than Sasanishiki under transient soil moisture stress, which is considered as phenotypic plasticity in response to rewatering after drought period. Such plastic root development was the key trait that effectively contributed to root elongation and branching during the rewatering period and consequently enhanced the root to penetrate hardpan layer when the soil penetration resistance at hardpan layer reduced. In addition, using the rootbox with artificial hardpan layer ($1.7g\;cm^{-3}$, heavily compacted), SL39 showed greater root system development than Sasanishiki under SMF, which was expressed in its significantly higher TRL, total nodal RL, and total lateral RL at hardpan layer as well as at below the hardpan layer. These results prove that SL39 has plasticity that enables its root systems to penetrate hardpan layer in response to rewatering. Under SMF, such root plasticity contributed to its higher gs and Pn.

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Growth and yield responses of rice varieties to various soil water deficit conditions under different soil types

  • Kikuta, Mayumi;Samejima, Hiroaki;Magoti, Rahab;Kimani, John M.;Yamauchi, Akira;Makihara, Daigo
    • 한국작물학회:학술대회논문집
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    • 한국작물학회 2017년도 9th Asian Crop Science Association conference
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    • pp.322-322
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    • 2017
  • To avoid drought stress under rainfed upland conditions, it is important for rice to efficiently utilize water at shallow soil layers supplied by rainfall, and access to water retained in deer soil layers. The root developmental characteristics of rice, which play important role in the adaptability to drought conditions, vary depending on the variety. Moreover, water availability for plant differs depending on the soil types that have different physical properties such as water holding capacity, permeability, capillary force, penetration resistance, etc. In this study, we evaluated growth and yield responses of rice varieties to various soil water deficit conditions under three different soil types. The experiment was conducted in a plastic greenhouse at the Kenya Agricultural and Livestock Research Organization-Mwea from October 2016 to January 2017. Two upland varieties (NERICA 1 and 4) and one lowland variety (Komboka) were grown in handmade PVC pots (15.2 cm diameter and 85.0 cm height) filled with three different types of soil collected from major rice-growing areas of the country, namely black cotton (BC), red clay (RC), and sandy clay (SC). Three watering methods, 1) supplying water only from the soil surface (W1), 2) supplying water only from the bottom of the pots (W2), and 3) supplying water both from the soil surface and the bottom of pots (W3), were imposed from 40 days after sowing to maturity. Soil water content (SWC) at 20, 40, and 60 cm depths was measured regularly. At the harvesting stage, aboveground and root samples were collected to determine total dry weight (TDW), grain yield, and root length at 0-20, 20-40, 40-60, and 60-80 cm soil layers. Irrespective of the watering methods, the greatest root development was obtained in RC, while that in BC was less than other two soils. In BC, the degree of yield reduction under W1 was less than that in RC and SC, which could be attributed to the higher water holding capacity of BC. In RC, the growth and yield reduction observed in all varieties under W1 was attributed to the severe drought stress. On the other hand, under W2, SWC at the shallow soil depth in RC was maintained because of its higher capillary force compared with BC and SC. As the result, growths and yields in RC were not suppressed under W2. In SC, deep root development was not promoted by W2 irrespective of the varieties, which resulted in significant yield losses. Under W1, the rice growth and yield in SC was decreased although shallow root development was enhanced, and the stomatal conductance was maintained higher than RC. It was suspected that W1 caused nutrients leaching in SC because of its higher permeability. Under rainfed conditions, growth and yield of rice can be strongly affected by soil types because dynamics of soil water conditions change according to soil physical properties.

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