• 한국산학기술학회논문지
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• 제16권1호
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• pp.801-806
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• 2015

본 최근 세계적으로 기후 변화에 의한 홍수 피해가 증가하고 있다. 우리나라의 경우 홍수가 발생하는 빈도가 증가함에 따라 홍수 발생 상황을 예측하고 대비할 수 있는 기술이 주로 대규모 하천을 대상으로 이루어졌으므로, 기존의 홍수 예보시스템을 예보 선행시간이 짧은 소규모 유역에 적용하기에는 무리가 있다. 이에 본 연구에서는 도시 유역 내 배수위 영향을 가진 수암천 유역을 대상으로 2개의 경보발령지점을 선정한 후, 홍수 예 경보 모형을 이용하여 홍수 경보 강우량을 산정하였다. 산정 결과, 저수 예 경보 지점의 경우 25.4mm/120min~78.8mm/120min로 산정되었으며, 고수 예 경보 지점의 경우 68.5mm/120min~140.7mm/120min로 산정되었다. 이에 따른 빈도로는 저수 예 경보의 경우 3년 빈도에 해당되며, 고수 예 경보의 경우 80년 빈도에 해당된다. 본 연구의 분석결과는 도시유역의 홍수 발생 상황을 예측하는데 기초 자료를 제공할 것으로 기대되며, 장차 실제 홍수 경보발령기준을 제시하기 위해 많은 유역에서의 관측자료를 바탕으로 한 지속적인 적용 및 검증이 필요하다.

• 한국방재안전학회논문집
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• 제12권2호
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• pp.1-13
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• 2019

본 연구에서는 강우재현주기의 내용을 포함하고 있는 고속도로 토석류 평가를 기초로 하여 고속도로 조기경보 시스템 개발을 위한 강우기준을 제안하였다. 강우기준은 주의경보와 위험경보로 구분하여 선행연구결과를 기초로 하여 적절한 강우기준이 추천되었으며 추천된 기준은 재현주기에 따른 토석류 평가등급별 1시간, 6시간, 3일 확률 강우량이다. 이때, 연구대상은 강원지역으로 하였으며 강원지역 8개 관측소의 확률 강우량을 수집하였다. 또한, 8개 자료의 확률 분석을 통해 강원지역 고속도로 토석류 조기경보에 이용될 1시간, 6시간, 3일 강우기준에 대한 확률분포를 산정하였다. 또한, 강우기준으로 선택된 3가지 강우정보와 실제 토석류 피해와의 연관성 분석을 실제 토석류가 발생한 강원지역 고속도로 7개 노선, 12개 지점의 피해발생시의 강우자료를 수집하여 검토에 이용하였다. 이때, 확률분포 상의 강우기준을 평균값과 하한값을 구분하여 검토하였다. 검토결과, 재현주기별 강우량의 하한값을 사용하는 경우가 실제 토석류 피해시의 상황을 잘 모사하는 것으로 나타났다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1996년도 창립기념 전력전자학술발표회 논문집
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• pp.43-46
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• 1996

The carborne Automatic Train Control(ATC) system keeps automatically optimum train speed code signals from wayside(track) circuit equipment. If there is no response for braking against the over speed detected, the driver will be noticed instantly by visual and audible warning signals. And then the ATC processes into braking mode for safe train operations to prevent any hazards by over speed limit. In this paper we are introduced the novel ATC system which has triple constructed structure made by 32 bit floating point DSP(ADSP21020-20) and process dealed with frequency domain and time domain for detecting signals. Owing to these reason it is no needed several band pass filters used in conventional ATC systems to detect the speed limit frequency. Also system's reliability and tolerance are incremented by adopt to 2 out of 3 logic to the outputs decision.

• 품질경영학회지
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• 제40권2호
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• pp.176-185
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• 2012

After a work of Derman and Ross(1997) that considered simple main runs rules and derived ARL (Average Run Length) using Markov chain modeling, $\bar{X}$ control chart based on diverse alternative main and supplementary runs rules that is the most popular control chart for monitoring the mean of a process are proposed. This paper reviews and discusses the-state-of-art researches for these runs rules and classifies according to several properties of runs rules. ARL derivation for a proposed runs rule is also illustrated.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1987년도 정기총회 및 창립40주년기념 학술대회 학회본부
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• pp.122-124
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• 1987

This paper presents a new algorithm in formulating a performance index for contingency selection method considering voltage security. Security limits defined-in terms of real power line flows and voltage magnitudes are considered in normalized subspaces where in critical contingencies are identified by a filtering algorithm using the infinite norm. Two types of limits, warning limit and emergency limit, are introduced for voltage and line flow. Usually performance indices have been constructed for real power line flows and voltages with each different criterion. This paper, however, presents a method that constructs them with the same criterion in use of the norm properties, so that we can assess security considering both of them. Rapid contingency simulation is performed using one iteration of fast decoupled load flows with LMML(Inverse Matrix Modification Lemma).

• Tribology and Lubricants
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• 제22권5호
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• pp.260-268
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• 2006

The dielectric constants of used gasoline engine oils were obtained at a few temperatures and a frequency. Through analyzing the characteristics of dielectric constant, the related correlation between the changes in dielectric constants of oil and the degree of oil deterioration is going to be found. The dielectric constant was calculated using cross capacitances measured by a sensor tube. As results of the measurement of the fresh engine oil's dielectric constant, it was found that the value of dielectric constant was set down below $60^{\circ}C$ regardless changing frequency. Further, above 6 kHz, the dielectric constant was set down even if temperature was above $100^{\circ}C$ Therefore, for the measurement of used oils, it was selected the frequency of 6 kHz,,and the temperature of $80^{\circ}C$ preventing a certain ionic-conduction effects on the measured dielectric constant and the evaporation of a certain fluid mixed with engine oil. Specially, the effects of the mixing fluid like coolant, water and fuel on the fresh engine oil's dielectric constant were studied. It was found that the oil mixed with coolant showed the highest value, next water, and the lowest fuel. As results of the measurement of the used engine oil's dielectric constant, it was found that the possible changed rate of the used engine oil's dielectric constant based on the warning limit for engine oil in service was below 4% for gasoline engine oil.

• Tribology and Lubricants
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• 제22권5호
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• pp.290-300
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• 2006

The dielectric constants of used diesel engine oils were obtained at a few temperatures and a frequency. Through analyzing the characteristics of dielectric constant, the related correlation between the changes in dielectric constants of oil and the degree of oil deterioration is going to be found. The dielectric constant was calculated using cross capacitances measured by a sensor tube. As results of the measurement of the fresh engine oil's dielectric constant, it was found that the value of dielectric constant was set down below $60^{\circ}C$ regardless changing frequency. Further, above 6 kHz, the dielectric constant was set down even if temperature was above $100^{\circ}C$. Therefore, for the measurement of used oils, it was selected the frequency of 6 kHz, and the temperature of $80^{\circ}C$ preventing a certain ionic-conduction effects on the measured dielectric constant and the evaporation of a certain fluid mixed with engine oil. Specially, the effects of the mixing fluid like coolant, water and fuel on the fresh engine oil's dielectric constant were studied. It was found that the oil mixed with coolant showed the highest value, next water, and the lowest fuel. As results of the measurement of the used engine oil's dielectric constant, it was found that the possible changed rate of the used engine oil's dielectric constant based on the warning limit for engine oil in service was below 10% for diesel engine oil.

• 분석과학
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• 제12권4호
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• pp.312-317
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• 1999

저농도, 고농도의 BOD, COD, TN, TP 항목에 대해 13개 기관을 대상으로 정도관리를 실시하였다. 정도관리 평가값은 6회에 걸쳐 주기적으로 반복측정한 평균치로 정하였으며, 이 값은 실제 조제한 값으로부터 오차율이 5%이내였으며, 표준편차도 0.44 (BOD, 저농도), 2.15 (BOD, 고농도), 0.12 (COD 저농도), 1.63 (COD 고농도), 0.35 (TN 저농도), 1.99 (TN 고농도), 0.05 (TP, 저농도), 0.14 (TP, 고농도)으로 정밀도가 아주 우수한 것으로 나타났다. 6회에 걸쳐 주기적으로 반복측정하여 허용상하한값과 경고상하한값을 구하여 정도관리차트를 얻었으며, 이 차트에 따라 평가한 결과 BOD 저농도의 경우 3개 기관이 5.30, 9.70, 5.30 mg/L로 허용상하한값을 벗어났으며, 고농도는 5개 기관이 허용상하한값을 벗어나 BOD 측정분석의 신뢰도가 다소 좋지 않은 것으로 나타났다. COD 저농도의 경우 4개 실험실, 고농도는 2개 기관이 41.00, 30.60 mg/L로 허용상하한값을 벗어났으며, 그외의 11개 기관은 신뢰할 수 있는 측정분석 결과를 산출하였다. TN 저농도의 경우 1개 기관만이 0.70 mg/L로 허용 하한값을 벗어났지 그외의 11개 기관은 거의 평가값에 가까운 우수한 측정분석 결과를 산출하였으며, 고농도는 거의 대부분인 11개 기관이 허용상하한값의 범위를 벗어나 측정분석 결과에 대한 신뢰도 향상에 보다 더 중점을 두어야 할 것으로 나타났다. TP 저농도의 경우 4개 기관이 1.14, 0.45, 0.64, 1.49 mg/L로 허용 상하한값을 벗어났으며, 고농도는 7개 기관이 허용 상하한값을 벗어나 TP 측정 분석의 신뢰도가 다소 좋지 않은 것으로 나타났다.

• 한국안전학회지
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• 제31권5호
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• pp.158-170
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• 2016

It has been applied several ways in order to prevent traffic accidents and speed management on the road which is one of very important factors to prevent accidents. In this study, it is analyzed whether the facility such as the flashing and crosswalk, speed cameras and intermittent warning signs affect on a driving deceleration or not. It has been shown that the flashing and crosswalk and speed cameras except intermittent warning signs play a role of reducing the driving speed. The result showed that these traffic safety facilities help to improve the average speed as well as velocity distribution which was derived by the speed deviation even if there were the difference between facilities. Speed limit display does not affect the deceleration of the driver. Therefore, it was founded in this research that there were the driving speed reduction effect due to the facilities on the road. In order to control the driving speed on the road, it is necessary to install facilities with appropriate location and spacing on the road. In addition, place that turns out suppressed speeding through speed management also are required adequate facilities such as speed cameras.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2005년도 춘계학술대회 논문집
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• pp.530-535
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• 2005

To monitor the flood level under heavy rainfall and the scour at railroad bridge, the system, which can effectively collect, store and transmit the data, is developed and applied to the field. The results in this study are as follows. 1) Monitoring for water level and scour depth is well done in view of the recording velocity and the accuracy of data which are measured. 2) This system is based on the web, internet and it is able to collect the realtime data and to analyze the risk. 3) When water level excesses the limit of danger level of a river on which railroad bridge is located, or when scour depth and angle of inclination of pier is increased, the scenario for early warning signal which sends to managers at central traffic control and drivers of trains is automatically made. It is judged that this system secures the safety of railroad and protects lives of train passengers as the warning signal sends to running train in advance at risky situation of railroad bridge under heavy rainfall.