• Title/Summary/Keyword: m-structure

Search Result 11,673, Processing Time 0.037 seconds

Study on the Mophology Observation and Electrical Properties of Dipyridinium Organic Monolayer Using STM (STM을 이용한 Dipyridinium 유기 단분자막의 모폴로지 관찰 및 전기적 특성 연구)

  • Lee Nam-Suk;Shin Hoon-Kyu;Kwon Young-Soo
    • The Transactions of the Korean Institute of Electrical Engineers C
    • /
    • v.54 no.2
    • /
    • pp.51-54
    • /
    • 2005
  • In this work, the attempt has been made to investigate the morphology of self-assembled dipyridinium dithioacetate on Au(111) substrate by Scanning Tunneling Microscopy(STM). Also, we measured electrical properties(I-V) using Scanning Tunneling Spectroscopy(STS). Sample used in this experiment is dipyridinium dithioacetate, which contains thiol functional group, this structure that can be self-assembled easily to Au(111) substrate. The self-assembly procedure was used for two different concentrations, 0.5 mM/ml and 1 mM/ml. Dilute density of sample by 0.5 mM/ml, 1 mM/ml and observed dipyridinium dithioacetate's image by STM after self-assembled on Au(111) substrate. The structure of STM tip-SAMs-Au(111) substrate has been used measurement for electrical properties(I-V) using STS. The current-voltage(I-V) measurement result, observed negative differential resistance(NDR) properties.

A study on the optimum range of reinforcement in tunneling adjacent to structures (구조물 근접 터널시공시 최적의 보강범위에 관한 연구)

  • Lee, Hong-Sung;Kim, Dae-Young;Chun, Byung-Sik;Jung, Hyuk-Sang
    • Journal of Korean Tunnelling and Underground Space Association
    • /
    • v.11 no.2
    • /
    • pp.199-211
    • /
    • 2009
  • Development of underground space is actively performed globally for better life in the surface, and the scale of the space is increasing. Extreme care should be taken in the construction of the underground space in urban areas in order to avoid damage of adjacent structures and interference with existing underground space. In case of shallow tunnels, reinforcement of ground and structures is necessary to minimize the damage to structures due to excavation but any standard for optimum range of the reinforcement has not been established yet. In this paper, a series of numerical analyses have been performed for a 20 m diameter tunnel excavated underneath a structure to investigate the degree of damage of the structure according to vertical and horizontal spacing between the tunnel and structure. In addition to that, optimum range of reinforcement is presented for each case where reinforcement is required. It has been observed that the reinforcement is necessary for the ground condition adapted in the analyses as follows: (1) if horizontal spacing ($S_{H}$) approaches to 0D (D: equivalent diameter of tunnel) for vertical spacing (Sv) of 0.5D, and (2) if tunnel exists underneath the structure for vertical spacing (Sv) of 0.75D. The reinforcement is not necessary for Sv of 10 regardless of $S_{H}$. It also has been obtained that the optimum ranges of the reinforcement around structure foundation are 7 m in depth and whole width of the structure and 5 m beyond tunnel sidewall. These reinforcememt ranges have been confirmed to be enough for stability of the structure if types of reinforcement method is appropriately selected.

Spatial Genetic Structure of Allozyme Polymorphisms within a Small Population of Abies nephrolepis in Mt. Ohdae, South Korea

  • Lee, Seok-Woo;Yang, Byeong-Hoon;Lee, Kab Yeon;Song, Jeong Ho;Hur, Seong Doo;Lee, Jung Joo
    • Journal of Korean Society of Forest Science
    • /
    • v.97 no.2
    • /
    • pp.144-151
    • /
    • 2008
  • Using 8 isozyme polymorphic loci as gene markers, we studied the spatial distribution of genotypes in a naturally regenerated uneven-aged Eastern Siberian Fir (Abies nephrolepis Max.) stand (1ha, $100{\times}100m$) on Mt. Ohdae in northeastern South Korea. Gregorius' distograms and Moran's I correlograms revealed no evidence of significant genetic structure at three spatial classes of 5 m, 10 m, and 20 m. Extensive gene flow, due to the long distance dispersal of pollen and seeds in A. nephrolepis, may account for the lack of fine-scale spatial structure. Alternatives would be overlapping seed shadows caused by high densities of A. nephrolepis adult trees (160 trees/ha) and/or intraspecific competition resulting in extensive thinning within maternal half-sib groups.

A Study on Powder Electroluminescent Device through Structure and Thickness Variation (구조 및 두께 변화에 따른 후막 전계발광 소자에 관한 연구)

  • Han, Sang-Mu;Lee, Jong-Chan;Park, Dae-Hee
    • Proceedings of the KIEE Conference
    • /
    • 1998.07d
    • /
    • pp.1379-1381
    • /
    • 1998
  • Powder electroluminescent device (PELD) structured conventionally dielectric and phosphor layer, between electrode and their layer fabricated by screen printing splaying or spin coating method. To promote performance of PELDs, we approached the experiments for different structure and thickness variation of PELD. Thickness variation($30{\mu}m{\sim}130{\mu}m$) was taken. To investigate electrical and optical properties of PELDs, EL spectrum, transferred charge density using Sawyer-Tower's circuit brightness was measured. Variation of structure in PELDs was as follows: WK-1 (ITO/BaTiO3/ZnS:Cu/Silver paste), WK-2 (ITO/BaTiO3/ZnS:Cu/BaTiO3/ZnS:Silver paste), WK-3 (ITO/BaTiO3/ZnS:Cu/BaTiO3/Silver paste), WK-4(ITO/BaTiO3+ZnS:Cu/Silver paste) As a result, structure of the highest brightness appeared WK-4 possessed 60 ${\mu}m$ thickness. The brightness was 2719 cd/$m^2$ at 100V, 400Hz.

  • PDF

Effect of Strarting Structures and Intercritical Annealing on Low Temperatures Mechanical Properties of a HSLA Steel (초기조직 및 이상역열처리가 저합금 고강도강의 저온기계적 성질에 미치는 영향)

  • Cho, H.K.;Park, K.G.;Shin, D.H.;Maeng, S.C.
    • Journal of the Korean Society for Heat Treatment
    • /
    • v.7 no.1
    • /
    • pp.53-60
    • /
    • 1994
  • Austenite formation and Low temperatures mechanical properties of HSLA steel of different starting structures have been studied by intercritical annealing(IA). The different starting structures are: ferrite+pearlite(FP1), martensite(M1), cold worked ferrite+pearlite(FP2) and cold worked martensite(M2). In most cases tensile strength and elongation was increased by decreasing the testing temperatures regardless of the IA time. Tensile strength of the cold worked starting structures was higher than that of the non-cold worked starting structures. However not any noticeable difference in elongation was found between two cases. Low temperatures impact properties were affected by the starting structures. Charpy V-notch impact transition temperatures of the M-starting structures were around $-40^{\circ}C$, and those of the FP starting structures were around $-10^{\circ}C$. Impact energy was lower in the cold worked specimens than in the non-cold worked specimens at the same starting structures. DP structure obtained from the M-starting structure has shown superior low temperatures mechanical properties than the DP structure obtained from the FP-starting structure.

  • PDF

Rapid Acquisition of m-sequence Signals by Sequential Estimation with Flexible Structure (가변구조를 갖는 순차 예측 방법을 이용한 m 계열 신호의 고속 포착)

  • 현광민;박상규
    • The Journal of Korean Institute of Communications and Information Sciences
    • /
    • v.27 no.7B
    • /
    • pp.664-672
    • /
    • 2002
  • This paper analyzes a sequential estimator with flexible structure for rapid acquisition of the m-sequence signals. If the received PN chips stored in the estimator's internal registers as initial loading values include one error, this chip with error can be corrected through multiple local PN code generators to achieve high-speed acquisition performance. Hamming distance between regenerated local PN codes from the proposed system and received PN code is compared with given threshold to choose a possible correct path and to declare success of the code acquisition. Using signal flow graph, average acquisition time that depends on detection and false alarm probability is calculated. By modifying generally used matched filter structure for PN code acquisition, the proposed system provides flexible structure and rapid acquisition process.

A Study on the Relation between Riverbed Structure and Pollutant Concentration in Down Stream of Nakdong River (낙동강, 서낙동강, 수영천 하구의 하상구조에 따른 연중 퇴적저토의 오염특성 연구와 부산근해 적조에의 영향에 관한 연구)

  • 황선출;이봉헌
    • Journal of Environmental Science International
    • /
    • v.6 no.5
    • /
    • pp.513-520
    • /
    • 1997
  • This study was performed to investigate the riverbed structure and the pollution type in Nakdong River, Western Nakdong River. and Suyoung Stream. Sediment and water samples were collected at is in Nakdong River. in Western Nakdong River, and 8 states In Suyoung Stream from February 20, 1997 to June 15, 1997. The depth distributions of sampling sites in the three streams were measured and heavy metals(Cd, Pb, Cr, Cu) and pesticides in sediments and COD, BOD, and total nitrogen(T-N) in water samples were analysed. The deepest and the shallowest sites were strate 11(11.58m) and 9(3.35m) in Nakdong River, site 7(6.25m) and 4(2.06m) in Western Nakdong River, and site 8(2.89m) and 1(0. 61m) in Suyoung Stream , respectively. The mean concentration of Cd(45.79ppm) was higher In the sediment of Western Nakdong River than In other two streams and those of Pb(76.25ppm), Cr(48.13ppm), and Cu(77.50ppm) were higher in file sediment of Suyoung Stream than in other two streams. Pesticides(1 kind of organophosphorus and 3 kinds of organochlorine pesticide) were detected only in the sediment of Western Nakdong River. The mean concentrations of COD(20.26ppm), BOD(25.36ppm), and T-N(18.05ppm) were higher in the water sample of Suyoung Stream than In other two streams.

  • PDF

¹H NMR Study of the Effect of G-T Mismatches on Dynamics and Stability of d(GCGTGCGC)₂ and Its Berenil Complex

  • 허성호;홍석주;이조웅;정채준
    • Bulletin of the Korean Chemical Society
    • /
    • v.17 no.11
    • /
    • pp.1045-1052
    • /
    • 1996
  • The effects of G-T mismatches on thermal stability, the base-pair lifetime and the global structure of a d(GCGTGCGC)2 duplex were studied by using 1H NMR, UV and CD spectroscopy. The existence of G-T mismatches was found to cause a noticeable change in the chemical environment of imino protons associated with significant decrease in the base-pair lifetime at the mismatched site as well as in thermal stability of the duplex itself. The melting transition of d(GCGTGCGC)2 was not cooperative at all at 100 mM or lower concentration of NaCl, but became cooperative at 500 mM or higher NaCl concentration. The melting temperature (Tm) of this duplex was 32℃ at 500 mM concentration of NaCl, which is much lower than that of d(GCGCGCGC)2 at the same NaCl concentration. This suggests that the decrease in stability may be ascribed to the decrease in the base-pair lifetime and the deviation from the normal structure due to the G-T mismatches. Adding berenil to d(GCGTGCGC)2 caused no observable change in the global structure but the large decrease in the base-pair lifetime and the stability of the duplex.

Variable amplitude fatigue test of M30 high-strength bolt in bolt-sphere joint grid structures

  • Qiu, Bin;Lei, Honggang;Yang, Xu;Zhou, Zichun;Wang, Guoqing
    • Steel and Composite Structures
    • /
    • v.33 no.3
    • /
    • pp.433-444
    • /
    • 2019
  • Fatigue failure of a grid structure using bolt-sphere joints is liable to occur in a high-strength bolt due to the alternating and reciprocal actions of a suspension crane. In this study, variable amplitude fatigue tests were carried out on 20 40 Cr steel alloy M30 high-strength bolts using an MTS fatigue testing machine, and four cyclic stress amplitude loading patterns, Low-High, High-Low, Low-High-Low, and High-Low-High, were tested. The scanning electron microscope images of bolt fatigue failure due to variable amplitude stress were obtained, and the fractographic analysis of fatigue fractures was performed to investigate the fatigue failure mechanisms. Based on the available data from the constant amplitude fatigue tests, the variable amplitude fatigue life of an M30 high-strength bolt in a bolt-sphere joint was estimated using both Miner's rule and the Corten-Dolan model. Since both cumulative damage models gave similar predictions, Miner's rule is suggested for estimating the variable-amplitude fatigue life of M30 high-strength bolts in a grid structure with bolt-sphere joints; the S-N fatigue curve of the M30 high-strength bolts under variable amplitude loading was derived using equivalent stress amplitude as a design parameter.

LDO Regulator with Improved Regulation Characteristics and Feedback Voltage Buffer Structure (Feedback Buffer 구조 및 향상된 Regulation 특성을 갖는 LDO regulator)

  • Jung, Jun-Mo;Park, Tae-Ryong
    • Journal of IKEEE
    • /
    • v.26 no.3
    • /
    • pp.462-467
    • /
    • 2022
  • The feedback buffer structure is proposed to alleviate the overshoot and undershoot phenomenon and the regulation of the output voltage. The conventional LDO regulator undergoes a regulation voltage change caused by a constant load current change. An LDO regulator with a feedback voltage sensing structure operates in the input voltage range of 3.3 to 4.5 V and has a load current of up to 150 mA at output voltage of 3 V. According to the simulation results, a regulation value of 6.2 mV was ensured when the load current uniformly changed to 150 mA.