• Title/Summary/Keyword: Head Distribution

Search Result 915, Processing Time 0.028 seconds

A Reliable 2-mode Authentication Framework for Wireless Sensor Network (무선 센서네트워크를 위한 신뢰성 있는 2-모드 인증 프레임워크)

  • Huyen, Nguyen Thi Thanh;Huh, Eui-Nam
    • Journal of Internet Computing and Services
    • /
    • v.10 no.3
    • /
    • pp.51-60
    • /
    • 2009
  • This paper proposes a reliable 2-mode authentication framework for probabilistic key pre-distribution in Wireless Sensor Network (WSN) that guarantees the safe defense against different kinds of attacks: Hello flood attacks, Wormhole attacks, Sinkhole attack, location deployment attacks, and Man in the middle attack. The mechanism storing the trust neighbor IDs reduces the dependence on the cluster head and as the result; it saves the power energy for the authentication process as well as provides peer-to-peer communication.

  • PDF

A New Distributional Record of an Acheilognathine fish, Rhodeus sericeus (Pallas) (Cyprinidae, Pisces) in South Korea (납줄개 Rhodeus sericeus(Palla$) (잉어과. 어강)의 신분포지)

  • 채병수;양홍준
    • The Korean Journal of Zoology
    • /
    • v.36 no.2
    • /
    • pp.175-180
    • /
    • 1993
  • Eighty one specimens of nhodeus sericeus (Pallas, 1176) were collected at the upper stream of the Som River (37$^{\circ}$32' 38" N, 127$^{\circ}$58' 57" E: Maegok-ri, Konggun-myon, Hoengsong-gun, Kanguvon-do, Korea) which is a tributary of the Namhan River. This is the first report of the species in the southern part of the Korean Peninsula. This species is well discriminated from the other species in the genus nhodeus by the following respects. The number of scales of transverse series is more than 34 (range 34-37, mean 35.7 $\pm$0.7). Head is echo감or and snout is Bonder than those of the other species. The upper part of the eve is always black and the lateral body surfaces are reddish purple. It had been hem that the southern limit of the distribution of Rhodeus sericeus was the Yonghung River in Hamgvongnam-do, north-eastern part of the Korean Peninsula. But their distributional range is extended more southerly to the Han River system which tons westward through the central part of the Korean Peninsula.Peninsula.

  • PDF

Flow Analyses around Intake within Sump in a Pump Station (펌프장에서 Sump내 흡입구 주위의 유동해석)

  • Roh Hyung-Woon;Kim Jae-Soo;Suh Sang-Ho
    • Proceedings of the KSME Conference
    • /
    • 2002.08a
    • /
    • pp.597-600
    • /
    • 2002
  • In general, the function of intake structure, whether it be a open channel, a fully wetted tunnel, a sump or a tank, is to supply an evenly distributed flow to a pump station. An even distribution of flow, characterized by strong local flow, can result in formation of surface or submerged vortices, and with certain low values of submergence, may introduce air into pump, causing a reduction of capacity and efficiency, an increase in vibration and additional noise. Uneven flow distribution can also increase or decrease the power consumption with a change in total developed head. To avoid these sump problems pump station designers are considered intake structure dimensions, such as approaching upstream, baffle size, sump width, width of pump cell and so on. From this background, flow characteristics of intake within sump are Investigated numerically to obtain the optimal sump design data. The sump model is designed in accordance with HI code.

  • PDF

A Flow Quantity Distribution Characteristics of the Hot Water Header for Individual Room Control System (실별제어 온수분배기의 유량분배 특성)

  • Sung, Sun-Kyung
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
    • /
    • v.20 no.3
    • /
    • pp.175-180
    • /
    • 2008
  • Flow quantity to supply to a coil in floor heating system is important to achieve comfortable indoor air condition in the winter season. The hot water header is used to distribute the water into the coil. Experimental study has been performed using the water header that have 5 branches consisted of flow control valves and automatic shut-off valves. Each branch line connected it with X-L pipe. Experimental tests accomplished it to investigate the flow distribution characteristics of the hot water header. Experimental results show that the selection of the pump head and differential pressure are very important to save running energy of the system, and high differential pressure needs more friction loss in the case of suitable differential pressure for balancing of the header.

A RETRIAL QUEUEING MODEL WITH THRESHOLDS AND PHASE TYPE RETRIAL TIMES

  • CHAKRAVARTHY, SRINIVAS R.
    • Journal of applied mathematics & informatics
    • /
    • v.38 no.3_4
    • /
    • pp.351-373
    • /
    • 2020
  • There is an extensive literature on retrial queueing models. While a majority of the literature on retrial queueing models focuses on the retrial times to be exponentially distributed (so as to keep the state space to be of a reasonable size), a few papers deal with nonexponential retrial times but with some additional restrictions such as constant retrial rate, only the customer at the head of the retrial queue will attempt to capture a free server, 2-state phase type distribution, and finite retrial orbit. Generally, the retrial queueing models are analyzed as level-dependent queues and hence one has to use some type of a truncation method in performing the analysis of the model. In this paper we study a retrial queueing model with threshold-type policy for orbiting customers in the context of nonexponential retrial times. Using matrix-analytic methods we analyze the model and compare with the classical retrial queueing model through a few illustrative numerical examples. We also compare numerically our threshold retrial queueing model with a previously published retrial queueing model that uses a truncation method.

A Study on SAR Reduction Method for Mobile Handsets (휴대 단말기의 SAR 저감법에 관한 연구)

  • Hwang Jae-Ho
    • Journal of the Korea Institute of Information and Communication Engineering
    • /
    • v.9 no.4
    • /
    • pp.833-838
    • /
    • 2005
  • In this paper, we propose SAR(Specific absorption rate) reduction methods based on surface electric field distribution relation for mobile handsets. Proposed the new method that is able to consider improvement of the SAR from the very beginning step of developing the mobile handsets. Analysis of mobile handset with human body(head) using finite element method(FEM). Results of this method, SAR reduced about $50\;\%$.

Measurement of Unsteady Total Pressure downstream of an 1-Stage Axial Turbine (1단 축류터빈 로터의 후류에서 비정상 전압력 측정에 관한 연구)

  • Kang, Jeong-Seek;Cha, Bong-Jun;Yang, Soo-Seok;Lee, Dae-Sung
    • 유체기계공업학회:학술대회논문집
    • /
    • 2005.12a
    • /
    • pp.318-323
    • /
    • 2005
  • To evaluate the accurate performance of turbomachinery, it is important to measure the unsteady flow phenomena downstream of the rotor blade. This paper presents the development of the fast-response total pressure probe for the measurement of the total pressure field at the exit of rotor and the result of measurement in a 1-stage axial turbine. The fast-response total pressure probe was fabricated by installing a fast-response pressure sensor near the head of a Kiel probe. And it measured the phase-lock averaged total pressure downstream of an 1-stage axial turbine. The developed probe successfully measured the accurate total pressure distribution at rotor exit and made possible to evaluate the loss distribution and the accurate performance of turbomachinery.

  • PDF

Analytical solution for steady seepage and groundwater inflow into an underwater tunnel

  • Zou, Jin-feng;Wei, An;Liang, Li
    • Geomechanics and Engineering
    • /
    • v.20 no.3
    • /
    • pp.267-273
    • /
    • 2020
  • Solutions of the water pressure and groundwater inflow distribution along the tunnel perimeter in a half-infinite aquifer were investigated considering the conditions of the constant head and constant water pressure. It is assumed that the circular tunnel is buried in a fully saturated, homogeneous, isotropic and half-infinite space. Coordinate transformation technique was adopted, the problem of solving the control equations of water pressure in the Cartesian coordinate was transformed to that in the bipolar coordinate system, which can significantly simplify the derivation procedure of the water pressure and inflow distribution. The validation results show the accuracy and advantage of the proposed approach.

Effect of Radiative Mean Temperature on Thermal Comfort of Underfloor Air Distribution System (바닥공조시스템에서 복사온도가 열적쾌적성에 미치는 영향)

  • Chung, Jae-Dong;Hong, Hi-Ki;Yoo, Ho-Seon
    • Proceedings of the SAREK Conference
    • /
    • 2006.06a
    • /
    • pp.15-20
    • /
    • 2006
  • Despite the fact that UFAD (Under Floor Air Distribution) systems have many benefits and are being applied in the field in increasing numbers, there is a strong need for an improved fundamental understanding of several key performance features of these systems. This study numerically investigates the effect of design parameters on the performance of UFAD, especially focused on thermal comfort. The design parameters considered in this study include supplied air temperature, supplied flow rate, diffuser shape, swirl, diffuser location, and floor-to-floor height. Also this study has compared UFAD with over head system, on the point of thermal comfort by evaluating PMV using radiative mean temperature, which shows how inadequate the evaluation of thermal comfort can be when radiation is neglected. Until now, the radiative temperature has been the missing link between CFD and thermal comfort, but the present study paves the way for overcoming this weakness.

  • PDF

Experimental study on standard and innovative bolted end-plate beam-to-beam joints under bending

  • Katula, Levente;Dunai, Laszlo
    • Steel and Composite Structures
    • /
    • v.18 no.6
    • /
    • pp.1423-1450
    • /
    • 2015
  • The paper presents the details and results of an experimental study on bolted end-plate joints of industrial type steel building frames. The investigated joints are commonly used in Lindab-Astron industrial buildings and are optimized for manufacturing, erection and durability. The aim of the research was to provide an experimental background for the design model development by studying load-bearing capacity of joints, bolt force distribution, and end-plate deformations. Because of the special joint details, (i.e., joints with four bolts in one bolt-row and HammerHead arrangements), the Eurocode 3 standardized component model had to be improved and extended. The experimental programme included six different end-plate and bolt arrangements and covered sixteen specimens. The steel grade of test specimens was S355, the bolt diameter M20, whereas the bolt grade was 8.8 and 10.9 for the two series. The end-plate thickness varied between 12 mm and 24 mm. The specimens were investigated under pure bending conditions using a four-point-bending test arrangement. In all tests the typical displacements and the bolt force distribution were measured. The end-plate plastic deformations were measured after the tests by an automatic measuring device. The measured data were presented and evaluated by the moment-bolt-row force and moment-distance from centre of compression diagrams and by the deformed end-plate surfaces. From the results the typical failure modes and the joint behaviour were specified and presented. Furthermore the influence of the end-plate thickness and the pretension of the bolts on the behaviour of bolted joints were analysed.