• Journal of Korean Society for Atmospheric Environment
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• 제23권E2호
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• pp.66-73
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• 2007

The introduction of tracer gas techniques to ventilation studies in indoor environments provides valuable information that used to be unattainable from conventional testing environments. Data acquisition systems (DASs) containing analogue-to-digital (A/D) converters are usually used to function the key role that records signals to storage in digital format. In the testing process, there exist a number of components in the measuring equipment which may produce system-based inference to the monitored results. These unwanted fluctuations may cause significant error in data analysis, especially when non-linear algorithms are involved. In this study, a pre-processor is developed and applied to separate the unwanted fluctuations (noise or interference) in raw measurements and to reduce the uncertainty in the measurement. Moving average, notch filter, FIR (Finite Impulse Response) filters, and IIR (Infinite Impulse Response) filters are designed and applied to collect the desired information from the raw measurements. Tracer gas concentrations are monitored during leakage and ventilation tests in the model test room. The signal analysis functions are introduced to carry out the digital signal processing (DSP) work. Overall the FIR filters process the $CO_2$ measurement properly for ventilation rate and mean age of air calculations. It is found that, the Kaiser filter was the most applicable digital filter for pre-processing the tracer gas measurements. Although the IIR filters help to reduce the random noise in the data, they cause considerable changes to the filtered data, which is not desirable.

• 한국정보과학회논문지:시스템및이론
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• 제26권8호
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• pp.905-917
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• 1999

멀티미디어 시스템에서 수행되는 부하 중 상당 부분은 정해진 시간에 주기적으로 수행되어 연속 매체(continuous media)를 처리하는 주기 태스크들이다. 연속 매체들을 처리하는 두 주기 태스크의 수행 요청 시간(release time)간에 인공적인 위상(phase)을 줄 경우, 전체 부하의 처리 타이밍에 영향을 주게 되며, 특히, 적절한 위상을 부여할 경우 부하가 고르게 분산된다. 부하의 고른 분산은 태스크 간섭을 줄여 지터(jitter), 종료시한 초과(deadline miss), 그리고 긴 응답 시간(response time) 등의 문제를 해소시킨다. 본 논문에서는 새로운 위상 스케줄링(phased scheduling) 알고리즘 및 알고리즘을 개발하고 평가할 수 있는 실험 환경을 제안한다. 본 논문에 제시된 알고리즘은 저자들의 선행 논문 1 에서 제시한 알고리즘의 대안이다. 새로운 알고리즘은 정확하게 최적의 위상을 찾지는 않으나 기존 알고리즘보다 빠르게 수행되며 적용 범위가 넓다.Abstract A multimedia system consists of substantial amount of continuous media workload scheduled periodically at deterministic time points. Artificial phase between the invocation times of any two continuous media tasks affects the timing of the entire workload. A proper phase configuration distributes workload uniformly over time and reduces task interference that may otherwise result in jitter, deadline miss, and long response time. The objective of this paper is to work out a phased scheduling algorithm and to evaluate its effectiveness. The algorithm in this paper is an alternative approach to our previous work 1 . It is almost as accurate as the predecessor but two of three times faster in identifying the appropriate phase vector.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2010년도 춘계 학술대회 제22권1호
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• pp.11-12
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• 2010

복부에 중공부가 있는 PSC 거더는 여러 가지 이점이 있다. 중공부에 정착부를 두어 프리스트레싱힘을 단계적으로 도입할 수 있으며 길이가 동일한 경우 거더의 중량을 줄일 수가 있고, 같은 중량인 경우 경간을 더 늘일 수 있다. 그리고 빔에 의한 조망권의 간섭도 줄일 수 있다. 본 연구에서는 복부에 여러 개의 원형 개구부를 가지고 있는 50m 실물 다단계 긴장 PSC 거더를 제작하여 모달테스트를 수행하였다. 모달테스트를 위한 가진방법으로 거더의 중앙에 가진기를 설치하여 일정 주파수 단위로 가진시킴으로써 정확한 주파수응답을 얻고자 하였다. 얻어진 주파수응답을 FFT와 PSD를 통하여 거더의 고유진동수와 감쇠비를 추정하였고 이를 Midas FEA를 이용한 해석결과와 비교하였다.

• Wind and Structures
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• 제16권3호
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• pp.249-261
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• 2013

Flexible stay cables on cable-stayed bridges are three-dimensional. They sag and flex in the complex wind environment, which is a different situation to ideal rigid cylinders in two-dimensional wind flow. Aerodynamic interference and the response characteristics of wake galloping of full-scale parallel cables are potentially different due to three-dimensional flows around cables. This study presents a comprehensive wind tunnel investigation of wake galloping of parallel stay cables using three-dimensional aeroelastic cable models. The wind tunnel study focuses on the large spacing instability range, addressing the effects of cable separation, wind yaw angle, and wind angle of attack on wake galloping response. To investigate the effectiveness of vibration suppression measures, wind tunnel studies on the transversely connected cable systems for two types of connections (flexibility and rigidity) at two positions (mid-span and quarter-span) were also conducted. This experimental study provides useful insights for better understanding the characteristics of wake galloping that will help in establishing a guideline for the wind-resistant design of the cable system on cable-stayed bridges.

• 한국응용과학기술학회지
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• 제31권2호
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• pp.190-196
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• 2014

The sol-gel method was used to prepare binary metal oxide ($IrO_2-RuO_2$) pH sensor. The electrodes that mole percent compositions (mol%) of $IrO_2$ and RuO2 were 70:30 and 30:70 were selected. The characterizations of Nernstian response over pH range, response rate, interference on alkaline metals and reproducibility were investigated. Also the electroanalytical properties of these electrodes were evaluated in comparison with a commercial glass pH electrode. The composition of $IrO_2:RuO_2$ 70:30 mol% was chosen as better electrode formulation. The electrode was not susceptible to the action of interfering ions such as $Li^+$, $Na^+$ and $K^+$.

• 대한간호학회지
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• 제30권2호
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• pp.293-306
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• 2000

Providing care to the dementia elderly with behavioral problem is a major issue in nursing homes today. This study was aimed to explore the nursing staffs′ response to aggressive dementia patients, and the effect that the aggressive behavior had on Nsgstaff. The interviews used a semi-structured questionnaire are were carried out from May to July, 1999. The subjects were 23 nursing personnel working in the nursing homes for dementia elderly. The result are as follows; 1. The types of aggressive behavior cited by the subjects was "physical", "linguistic", and "sexual". 2. The factors that caused the behavior were "symptoms of disease", "under- conditioning", "context of nursing care", "unsatisfied need", "relationship to other patients", "change of outer environment", and "invasion of one′s own privacy". 3. The response of the subjects were "unhappiness", "stress", "anger", "exaggeration", "anxiety", and "fear". 4. The management strategies listed by nursing personnel used to alleviate aggressive behavior were "ignorance" "patience" "leaving the area" "soothing sounds" "verbal punishment" "restriction and isolation" and "various management skill appliance" "adaptation". 5. The effect that aggressive behavior and were "disturbance of relationship to elderly" "decline in the amount and quality of nursing care" "interruption of task performance" "job exhaustion" "desire to leave the job" "physical impact" "stress on the cognition of others" "anxiety about health and one own future" "interference to family life′. The findings of this study will be useful in understanding the difficulties of nursing personnel when confronting the aggressive behavior of dementia partients. It also is useful as basic data in preparing efficient intervention program for these difficulties.

• 한국항공우주학회지
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• 제33권4호
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• pp.17-26
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• 2005

새로운 개념의 위성발사 방식으로 연구되고 있는 초음속 공중발사로켓의 모선분리 현상을 파악하기 위하여 모선-로켓의 단순화된 형상에 대하여 발사속도, 장착각, 수평-수직방향의 장착위치 변화에 따른 발사체의 피칭모멘트의 변화를 고찰하였다. 정상상태의 유동해석을 위하여 삼차원 Euler 방정식을 수치적으로 해석했고, 이러한 연구를 통하여 모선날개에 장착된 초음속 공중발사로켓의 모선분리에 큰 영향을 주는 장착변수를 확인하였으며 각 변수의 변화에 따른 발사체의 거동의 변화를 반응면 모델을 구성하여 도식으로 나타내었다. 본 연구를 통하여 초음속 공중발사 메커니즘에 대한 공력특성과, 비정상 모선분리를 위한 최적 장착 위치에 대한 유용한 데이터를 제공하게 되었다.

• 한국시뮬레이션학회논문지
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• 제17권4호
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• pp.99-112
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• 2008

UHF 대역 수동형 RFID 시스템은 860~960 MHz 대역에서 리더와 태그가 역산란 변조 방식을 이용하여 통신한다. 따라서 다수의 리더와 태그가 동시에 존재하는 환경에서는 리더 신호 간에 간섭이 발생하고 원활한 통신이 어렵게 된다. 본 논문에서는 이러한 충돌 문제를 해결하기 위해 중재기를 사용한 중앙 중재 방법을 제안하고 제안된 방법의 성능을 평가하기 위하여 시스템을 모델링하고 시뮬레이션 하였다. 시뮬레이션은 완료시간, 이용도, 응답시간으로 평가하고, 제시한 중재 방법이 만족스러운 성능을 보임을 확인하였다.

• IEIE Transactions on Smart Processing and Computing
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• 제3권3호
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• pp.142-152
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• 2014

Vehicular Ad-hoc Networks (VANETs) are comprised of wireless mobile nodes characterized by a randomly changing topology, high mobility, availability of geographic position, and fewer power constraints. Orthogonal Frequency Division Multiplexing (OFDM) is a promising candidate for the physical layer of VANET because of the inherent characteristics of the spectral efficiency and robustness to channel impairments. The susceptibility of OFDM to Inter-Carrier Interference (ICI) is a challenging issue. The high mobility of nodes in VANET causes higher Doppler shifts, which results in ICI in the OFDM system. In this paper, a frequency domain com-btype channel estimation was used to cancel out ICI. The channel frequency response at the pilot tones was estimated using a Least Square (LS) estimator. An efficient interpolation technique is required to estimate the channel at the data tones with low interpolation error. This paper proposes a robust interpolation technique to estimate the channel frequency response at the data subcarriers. The channel induced noise tended to degrade the Bit Error Rate (BER) performance of the system. Parallel concatenated Convolutional codes were used for error correction. At the decoding end, different decoding algorithms were considered for the component decoders of the iterative Turbo decoder. A performance and complexity comparison among the various decoding algorithms was also carried out.

• Bulletin of the Korean Chemical Society
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• 제11권3호
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• pp.200-205
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• 1990

Chemically modified electrodes(CMEs), based on 2-imino-1-cyclopentane-dithiocarboxylic acid (icdc) containing carbon paste, have been characterized using cyclic voltammetric techniques. Ag(I) was chemically deposited on the CMEs, and voltammograms were obtained with the electrode in a separate buffer solution. The CME surface can be regenerated with exposure to acid and reused for deposition. In 10 deposition/measurement/regenerate cycles, the linear response have been reproduced up to $1{\times}10^{-6}$ M in linear sweep voltammetry and 1${\times}$10-8 M in differential pulse voltammetry with relative standard deviation of 5.2% and 12.4%, respectiveiy. The sensitivity increased with deposition time and scanning rate, and detection limit was $1{\times}10^{-7}M\;and\;1{\times}10^{-9}M$ at 20 minutes deposition in the linear sweep voltammetry and differential pulse voltammetry, respectively. The presence of some metal ions does not influence the silver ion response. Satisfactory results were obtained for the analysis of the silver ion for a variety of reference materials without interference of Hg ion at the condition of pH = 5-6.