• Title/Summary/Keyword: Response Time Delay

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Conceptual Design of Emergency Communication System to Cope with Severe Accident in Nuclear Power Plants (중대사고를 대비한 원전비상통신시스템 개념설계)

  • Son, Kwang Seop
    • Journal of the Institute of Electronics and Information Engineers
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    • v.51 no.5
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    • pp.58-69
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    • 2014
  • To cope with sever accident like Fukushima accident, the emergency response system is needed. It consist of the hardened I&C system and the mobile control station. The hardened I&C system monitors the state in the nuclear power plant and controls the emergency equipment such as valves, pumps and the mobile control station placed at 30km away from nuclear power plant receives the status information from the hardened I&C system and transmits the control data to the hardened I&C system. In this paper, we design the emergency communication system connecting the hardened I&C system to the mobile control station and analyze the performance of the system. This system consists of the terrestrial communication system and the satellite communication. The performance such as a communication link budget, throughput and delay time is analyzed for each system.

An Experimental Study on the Sensor Response at Hydrogen Leakage in a Residential Fuel Cell System (가정용 연료전지 시스템 내부 수소 누출 시 센서 응답 특성에 관한 연구)

  • Kim, Young-Doo;Shin, Dong-Hoon;Chung, Tae-Yong;Nam, Jin-Hyun;Kim, Young-Gyu;Lee, Jung-Woon
    • Transactions of the Korean hydrogen and new energy society
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    • v.20 no.5
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    • pp.378-383
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    • 2009
  • Hydrogen is the primary fuel in fuel cell systems. Because of high inflammation and explosion possibility of hydrogen, fuel cell systems require safety measures to prevent hydrogen hazard upon leakage. In this study, a model enclosure was made by referring to a commercial residential fuel cell system and hydrogen leakage experiments and computational simulations were conducted therein. Hydrogen was injected into the cavity through leakage holes located at the bottom while its flow rate was precisely controlled using MFC. The transient sensor signals from hydrogen sensors installed inside the enclosure were recorded and analyzed. The hydrogen sensor signals showed different delay times depending on their position relative to a leakage point, which indicated that hydrogen generally moves upward and accumulates at the upper region of a closed cavity. The inflammable regions with hydrogen concentration over 4% LEL were observed to locate near the leakage hole initially, and broaden towards the upper cavity region afterward. The simulation result showed that detection time at the hydrogen sensor was similar to the pattern of experimental results. However, the maximum concentration of hydrogen had a gap between experiment and simulation at detect point due to measurement errors and reaction rate.

Optimization of Active Tendon Controlled Structures by Efficient Solution of LQR Control Gain (LQR 제어이득의 효율적 산정에 의한 능동텐던 구조물의 최적화)

  • Cho, Chang-Geun;Kyun, Jun-Myong;Jung, In-Kju;Park, Moon-Ho
    • Journal of Korean Association for Spatial Structures
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    • v.8 no.4
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    • pp.73-80
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    • 2008
  • The objective of current study is to develop an optimization technique for the seismic actively controlled building structures using active tendon devices by an efficient solution of LQR control gain. In order to solve the active control system, the Ricatti closed-loop algorithm has been applied, and the state vector has been formulated by the transfer matrix and solved by a numerical technique of the trapezoidal rule. The time-delay problem has been also considered by phase compensation. To optimize the performance index, the ratio of the weighted matrix is the design variable, allowable story drift limits of IBC 2000 and tendon forces have been applied as restraint conditions, and the optimum control program has been developed with the algorithm of the SUMT technique. In examples of the optimization problem of eight stories shear buildings, it is evaluated that the optimum controlled building is more suitable in the control of earthquake response than the uncontrolled system and can reduce the performance index to compare with the controlled system with a constant ratio of the weighted matrix.

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다중 환경추적자를 이용한 제주도 지하수 유동 및 수질 특성 분석

  • 고동찬;김용재
    • Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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    • 2004.09a
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    • pp.138-141
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    • 2004
  • The environmental tracers tritium/helium-3 (3H/3He) and chlorofluorocarbons (CFCs) were investigated in ground water from Jeju Island, Korea, a basaltic volcanic island. The apparent 3H/3He and CFC-12 ages were in relatively good agreement in samples with low concentrations of terrigenic He. Ground water mixing was evaluated by comparing 3H and CFC-12 concentrations with mixing models, which distinguished old water with negligible 3H and CFC-12, young water with piston flow, and binary mixtures of the two end members. The ground water CFC-12 age is much older in water from wells completed in confined zones of the hydro-volcanic Seoguipo formation in coastal areas than in water from the basaltic aquifer. Comparison of major element concentrations in ground water with the CFC-12 age shows that nitrate contamination processes contribute more solutes in young water than are derived from water-rock interactions in non-contaminated old water. Chemical evolution of ground water resulting from silicate weathering in basaltic rocks reaches the zeolite-smectite phase boundary. The calcite saturation state of ground water increased with the CFC-12 apparent (piston flow) age. In agricultural areas, the temporal trend of nitrate concentration in ground water was consistent with the known history of chemical fertilizer use on Jeju Island, but the response of nitrate concentration in ground water to nitrogen inputs follows an approximate 10-year delay. Based on mass balance calculations, it was estimated that about 40% of the nitrogen applied by fertilizers reached the water table and contaminated ground water resources when the fertilizer use was at the highest level.

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Concurrency Control Method using the Asynchronous Data Broadcast in Mobile Computing Environments (이동 컴퓨팅 환경에서 비동기적 데이터방송을 사용한 동시성 제어 기법)

  • Ko Seung-Min;Kim Dae-In;Im Sun-Mo;Hwang Bu-Hyun
    • The KIPS Transactions:PartD
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    • v.12D no.1 s.97
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    • pp.21-30
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    • 2005
  • In mobile computing environments, a mobile host caches the data to use the narrow bandwidth efficiently and improve the response time. A server periodically broadcasts the update data for maintaining the cache consistency of a mobile host. However, a method for maintaining cache consistency using periodic invalidation report has a problem that defers the commit decision of a mobile transaction to guarantee its serializable execution. In this paper, we propose CCM-AD method that guarantees the serializable execution of a mobile transaction even in the case that it is executed using cached data. As CCM-AD method guarantees the serializable execution of mobile transactions by using the intersection between the data broadcast to mobile host and the data updated at server. Then the CCM-AD method can reduce the delay of commitment decision of a mobile transaction. Also our method can reduce the size of invalidation report.

Groundwater and Surface Water Hydrology in the Lake Rotorua Catchment, New Zealand, and Community Involvement with Lake Water Quality Restoration

  • White, Paul A.;Hong, Timothy;Zemansky, Gil;McIntosh, John;Gordon, Dougall;Dell, Paul
    • Proceedings of the Korea Water Resources Association Conference
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    • 2007.05a
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    • pp.8-14
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    • 2007
  • Water quality in Lake Rotorua, New Zealand, deteriorated since the 1960s because of excessive phytoplankton growths due principally to increasing nitrogen and phosphorus in the lake waters. Nutrient concentrations in eight of the nine major streams feeding Lake Rotorua have increased since 1965. The groundwater system has a key role in the hydrology of the Lake Rotorua catchment and the groundwater system is probably the control on the time delay between intensification of agricultural land use and response of surface water quality. All major, and many minor streams, in the catchment are fed by springs. Two lithological units are most important to groundwater flow in the Lake Rotorua catchment: Mamaku Ignimbrite, erupted in about 200,000 years ago and Huka Formation sediments which filled the caldera left by the Mamaku Ignimbrite eruption. Rainfall recharge to groundwater in the groundwater catchment of Lake Rotorua is estimated as approximately 17300 L/s. A calibrated steady-state groundwater flow model estimates that approximately 11100 L/s of this flow discharges into streams and then into the lake and the balance travels directly to Lake Rotorua as groundwater discharge through the lake bed. Land use has impacted on groundwater quality. Median Total Nitrogen (TN) values for shallow groundwater sites are highest for the dairy land use (5.965 mg/L). Median TN values are also relatively high for shallow sites with urban-road and cropping land uses (4.710 and 3.620 mg/L, respectively). Median TN values for all other uses are in the 1.4 to 1.5 mg/L range. Policy development for Lake Rotorua includes defining regional policies on water and land management and setting an action plan for Lake Rotorua restoration. Aims in the action plan include: definition of the current nutrient budget for Lake Rotorua, identification of nutrient reduction targets and identification of actions to achieve targets. Current actions to restore Lake Rotorua water quality include: treatment of Tikitere geothermal nitrogen inputs to Lake Rotorua, upgrade of Rotorua City sewage plant, new sewage reticulation and alum dosing in selected streams to remove phosphorus.

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Directive Spectrum Analyzing System Using a Linear Hydrophone Array (직선배열 hydrophone에 의한 수중음원의 분석)

  • CHANG Jee-Won;JEONG Jung-Hyun;SUR Doo-Og
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.14 no.4
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    • pp.265-268
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    • 1981
  • The direction and spectra of underwater sound wave were a remarkable contrast to the sound wave in the air because of the difference of transmissive medium. The linear hydrophone array of passive system has so far been applied to find out the direction and spectra of underwater sound wave from the sources for many purposes. The conventional methods are generally classified into two systems such as, the system which varying frequency responses, other parameters and pattern of signal like an adaptive array controlled by internal feedback, and another system which obtaining maximum of S/N ratio by giving a appropriate delay and a weighting coefficient in the output of each hydrophone. The array device of passive system can easily change the amplitude and the phase of signal by separately controlled hydrophone. And here we introduce a method that the spectral analyzing and the direction finding can be simultaneously carried out using a linear array of hydrophones. By making a circular convolution of output of signal from each hydrophone with appropriate rectangular weighting coefficient on the array, a sharp response of single lobe directivity and the spectral analyzing by time averaging were simultaneously obtained. In tile computer simulation of the array system with the length of 250cm and the interhydrophone distance of l0cm the power levels of sound signals received from given array direction were 16dB higher than those from the other directions when processing with rectangular weightings, and 8dB higher when processing with rectangular sound signals and rectangular weightings.

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Feasibility Study for the Development of a Device for Pathological Tissue (병리학적 조직 진단장치 개발에 대한 타당성 분석 연구)

  • Ko Chea-Ok;Park Min-Young;Kim Jeong-Lan;Lee Ae-Kyoung;Choi Hyung-Do;Choi Jae-Ic;Pack Jeong-Ki
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.17 no.4 s.107
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    • pp.341-350
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    • 2006
  • In this paper, a new method for detecting breast cancer is proposed, which utilizes dielectric characteristics of pathological tissues and time delay of back scattered response, and its feasibility was investigated. We have developed a detection algorithm and verified it by numerical simulation and measurement for a prototype system. For a prototype system, we have fabricated experimental model(artificial breast with a cancer) and UWB(ultra-wideband) antenna. The results of the measurement simulation show an excellent detection capability of a cancer tissue. It is found that a good UWB antenna and a good calibration signal are key elements of such detection system. Further study is ongoing to develop a commercial system.

The effect of initial Pd catalyst oxidation stale on CH$_4$sensitivity of SnO$_2$thin film sensor (Pd 촉매의 부분 산화 조절을 이용한 SnO$_2$박막 센서의 CH$_4$감도 변화 연구)

  • Choi, W. K.;Cho, J.;Cho, J. S.;Song, J. H.;Jung, H. J.;Koh, S. K.
    • Journal of the Microelectronics and Packaging Society
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    • v.6 no.2
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    • pp.45-49
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    • 1999
  • A flammable gas sensor based on the $SnO_2$thin film deposited by the reactive ion assisted deposition was fabricated and ultra-thin Pd layer as catalyst was adsorbed at surface by ion beam sputtering. The initial oxidation states of Pd catalyst were controlled to investigate the role of Pd in the sensing process of inflammale gas sensor through annealing in air and vacuum respectively. The Pd catalyst existing in pure metallic state showed the sensitivity higher than that of PdO. The result might be closely related to the fact that PdO as a surface acceptor would receive electrons via Pd sub-channel from $SnO_2$, and thus which reduces the sensitivity and delay the response time.

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Analytical Models and Performance Evaluations of Network Management Systems (네트워크 관리 시스템의 해석적 모델 및 성능 평가)

  • Jung Woo, Lee;Jae Hyuk, Choi;Woo Seok, Lee;Sang Bang, Choi
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.41 no.9
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    • pp.17-28
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    • 2004
  • Since the Internet has grown into a large communication infrastructure, the network management system to systematically manage the large number of network components has become an essential part of the Internet. The rapid growth of network size has brought into question the scalability of the existing centralized model, such as SNMP (Simple Network Management Protocol) and CMIP (Common Management Information Protocol). Thus, for efficient network management, researches about mobile agent have also been performed recently. This paper presents analytical models of centralized approach based on SNMP protocol, distributed approach based on mobile agent, and mixed mode to make up for shortcomings of SNMP and mobile agent. We compare the performance of these analytical models based on network management response time. Experiment results show that performance of mobile agent and the mixed mode is less sensitive to the delay in WAN network environment. However, SNMP is more efficient for the simple network environment like LAN.