• 제어로봇시스템학회논문지
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• 제14권1호
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• pp.1-6
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• 2008

The ubiquitous sensor network technique is widely applied to variety of information fields such as home automations, logistics, traffic controls, public administrations, health and environment monitoring and etc. It is particularly useful in the areas where energy consumption is minimal and where continuous monitoring of the surrounding environments, which generates streams of data, are required. In this study, we have designed and implemented a living environment automatic control system which collects the streams of temperature, humidity, light and noise data of a simulated house setting in real-time fashion, then controls the home environment based on the collected data according to the users favorites. In order to differentiate the proposed system from the currently existing similar system, we have demonstrated not only the feasibility of collecting data using sensor network in the controlled environment but also the ability to control the various household equipments through wireless communications.

• 한국지리정보학회지
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• 제11권2호
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• pp.93-107
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• 2008

최근 한국에서는 하천의 환경적 생태적 기능을 되살리기 위해 하천복원과 관련된 여러 가지 사업이 진행되고 있다. 이러한 하천복원사업에 있어서 사업대상 하천의 생태성에 대해 평가하고, 이를 바탕으로 하천복원사업의 목표와 계획을 수립할 수 있도록 하는 일은 학술적이나 사업적으로나 모두 값진 일이 될 것이다. 한편, 하천의 생태성을 개략적으로 판단할 수 있는 방법의 하나는, 하천의 수문지형 물리적 구조(hydromorphological structure)를 평가하는 것이다. 본 연구에서는 LAWA(물관리 연구 독일 연방 법적공동체)의 하천 평가 기법을 이용하여 중 소규모 하천의 자연 생태성을 평가하기 위한 하천의 수문지형 물리적 구조를 평가하는 현장 조사 체계(field survey system)를 개발하고, 아울러 조사결과를 이용하여 도면자동화 체계(auto mapping system) 및 보고서로 작성하는 과정을 지원하는 GIS 기반의 하천 평가 체계를 개발하였다. 하천복원 및 관리 분야 종사자들이 하천복원 계획 수립과 관리의 단계에서 대상하천의 하천자연도 내지 생태성을 인지하고 분석하는데 도움을 주고, 대상하천의 '도달해야 하는 이상적인 하천모델상'을 결정하기 위한 기초 자료를 수집하는데 도움을 주고자 한다.

• 한국콘텐츠학회논문지
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• 제7권10호
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• pp.27-35
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• 2007

RFID 기술은 객체의 추적이나 SCM 시스템에서 중요한 역할을 하고 있으며 RFID 응용에서는 새로운 데이터 관리 방법을 필요로 하고 있다. RFID 데이터는 자동으로 빠르게 생성되며 객체의 실시간 모니터링이나 추적에 사용되고 있다. 이러한 RFID 응용의 대부분은 이벤트가 발생할 때 타임스탬프를 가지는 특성이 있다. 본 논문에서는 RFID 객체를 모니터링하고 상태 변화의 이력을 관리하기 위하여 시간지원 RFID 데이터 모델을 제시하고 이 모델에 기반을 둔 비활성 데이터의 필터링 기법을 제안하다. 제안한 시간지원 RFID 데이터 모델은 RFID 객체를 모니터링할 수 있는 핵심 연산을 포함하고 있으며, 비활성 데이터의 필터링 기법을 통하여 질의 처리의 속도가 향상됨을 보였다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 I
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• pp.477-480
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• 2003

Packet losses in the Internet can dramatically degrade quality of multimedia streams. Forward Error Correction (FEC) is one of the best methods that can protect data from packet erasures by means of sending additional redundant information. Proposed control algorithm provides the possibility of receiving real-time multimedia streams of given quality wifth minimal traffic overhead. The traffic optimization is reached by adjusting packet size as well as block code parameters. Calculations and simulation results show that for non-bursty network conditions traffic optimization can lead to more than 50% bandwidth reduction.

• Journal of information and communication convergence engineering
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• 제12권2호
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• pp.109-115
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• 2014

This paper presents a concurrent channel time allocation scheme used in the reservation period for concurrent transmissions in 60-GHz wireless personal area networks (WPANs). To this end, the proposed resource allocation scheme includes an efficient method for creating a concurrent transmission group by using a table that indicates whether individual streams experience interference from other streams or not. The coordinator device calculates the number of streams that can be concurrently transmitted with each stream and groups them together on the basis of the calculation result. Then, the coordinator device allocates resources to each group such that the streams belonging to the same group can transmit data concurrently. Therefore, when the piconet coordinator (PNC) allocates the channel time to the individual groups, it should allow for maximizing the overall capacity. The performance evaluation result demonstrates that the proposed scheme outperforms the random grouping scheme in terms of the overall capacity when the beamwidth is $30^{\circ}C$ and the radiation efficiency is 0.9.

• 한국농공학회지
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• 제43권5호
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• pp.163-171
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• 2001

Reaeration phenomena, the physical process of absorption of oxygen from atmosphere, is one of the important parameters of dissolved oxygen simulation in streams. This study was aimed at predicting reaeration coefficients in rural small streams, examining the influence of drop structure on reaeration and the seasonal fluctuation of reaeration coefficients. Reaeration coefficients of five streams including four tributaries of Bokha watershed in Gyeonggi Ichon and Onyang stream in Chungnam Onyang were measured. Constant rate injection (CRI) method using propane and Rhodamine-WT as gas and dye tracer was adopted. Reaeration coefficients ranged between 6.16 and 29.16 reciprocal day, higher than those in USGS database. Prediction equation,$k_2=CV^{0.593}$, was regressed from the measured data at 95% confidence level, with an absolute error of 21.2% and a standard error of 4.0 reciprocal days. Reaeration coefficients of experimental reaches with drop structure showed percentile increases of 42.3 to 159.2 compared to those without it, an indication that drop structure plays an important role on stream reaeration. Taking into consideration the seasonal fluctuation of reaeration coefficients, the values measured during September and October were the highest, mainly due to the removal of aquatic plants. by intensive rainfall during summer.

• 한국농공학회논문집
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• 제55권6호
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• pp.177-186
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• 2013

The purpose of this study was to analyze the temporal and spatial characteristics of the stream flow of small rural streams for investigating the status of stream depletion located downstream of irrigation reservoir. Bonghyun and Hai reservoirs and each downstream were selected for this study. Streamflow was measured for 8 stations downstream from two reservoirs from 2010 to 2012. The water quality samples were collected monthly from the 8 stream stations and 2 reservoir stations from 2011 to 2012. The stream depletion was found in most of the downstream of reservoirs for the non-irrigation period and even in the irrigation period when there were a lot of antecedent precipitation. We found that the stream segments where there were few streamflow, vegetation covers the stream and block the streamflow which makes the stream lost its original function as a stream. Water quality monitoring results of Bonghyun stream indicated that the concentration of SS, Turbidity, TOC, COD were decreased as the stream flows from the reservoir to downstream while the TN and TP were increased. The correlation analysis for water quality data indicated that the correlation between T-N and T-P was high for Bonghyeon and Sukji streams, respectively. Continuous monitoring for rural streams located in downstream of reservoirs are required to quantify the status of stream flow depletion and determine the amount of environmental flows.

• Water Engineering Research
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• 제4권2호
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• pp.69-85
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• 2003

Previously developed empirical equations used to calculate the parameters of the transient storage model are analyzed in depth in order to evaluate their behavior in representing solute transport in the natural streams with storage zone. A comparative analysis of the existing theoretical and experimental equations used to predict parameters of the transient storage (TS) model is reported. New simplified equations for predicting 4 key parameters of the TS model using hydraulic data sets that are easily obtained in the natural streams are also developed. The weighted one-step Huber method, which is one of the nonlinear multi-regression methods, is applied to derive new parameters equation. These equations are proven to be superior in explaining mixing characteristics of natural streams with the transient storage zone more precisely than the other existing equations.

• Journal of information and communication convergence engineering
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• 제14권2호
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• pp.84-88
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• 2016

As good example of potential application-specific requirement, (m,k)-firm real-time streams have been recently introduced to deliver multimedia data efficiently in wireless sensor networks. In addition to stream model, communication protocols to meet specific (m,k)-firm real-time streams have been newly developed or extended from existing protocols. However, since the existing schemes for an (m,k)-firm stream have been proposed under typical flat architecture, the scalability problem remains unsolved when the number of real-time flows increases in the networks. To solve this problem, in this paper, we propose a new clustering scheme for an (m,k)-firm stream. The two different clustering algorithms are performed according to either the (m,k)-firm requirement or the deadline. Simulation results are presented to demonstrate the suitability of the proposed scheme under hierarchical architecture by showing that its performance is acceptable irrespective of the increase in the number of flows.

• Water Engineering Research
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• 제1권3호
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• pp.171-185
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• 2000

A mathematical model to adequately predict complex mixing characteristics of sorptive polluants in natural streams with pools-and-riffes has been developed. In this model, sorption of pollutants onto the bed sediment as well as mass storage and exchange in the storage zones were incorporated into one-dimensional mass balance equatins. The geometric and hydraulic characteristics of the pool-riffle sequences were properly conceptualized. Simulations with parameters of pool-and-riffle streams better fit the measured data in overall shape and peak concentration than simulations with parameters for uniform channels. The analyses on the characteristics of the storage zone model parameters reveal that a linear relationship between the logrithm of the storage zone volume ratio and a function of the friction factor exists. A linear relatiohship might also be tenatively assumed between the logarithm of the dimensionless mass exchange coefficient and the logarithm of the aspect ratio of the storage zone if some of the high values of the dimensionless mass exchange coefficient collected on the successive bed forms are excluded.