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SCR-HP 밸브의 온도 및 개폐 신호를 이용한 잔여 수명 예측 알고리즘
이수환(Suhwan Lee),염은섭(Eunseop Yeom) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.11
Selective catalytic reduction (SCR) was applied to ships in order to comply with the emission standards set by the International Maritime Organization(IMO). The butterfly valve used in the SCR under high pressure(HP) condition is referred to as the SCR-HP valve, which continuously exposed to the exhaust gas with high-temperature. The thermal deformation and abrasion can result in leakage under long-term operation. Based on temperature and opening/closing signals acquired through experiments, long-term operational data (6 years) were simulated. In virtual data, converged temperature signal can be processed by the signal processing algorithm using opening/closing signal. Interpolation and noise removal were performed on the separated temperature signals. The autoregressive integrated moving average(ARIMA) prediction model was applied to predict the remaining life of the valve.
ARIMA를 활용한 실시간 SCR-HP 밸브 온도 수집 및 고장 예측
이수환(Suhwan Lee),홍현지(Hyeonji Hong),박지수(Jisoo Park),염은섭(Eunseop Yeom) 한국가시화정보학회 2021 한국가시화정보학회지 Vol.19 No.1
Selective catalytic reduction(SCR) is an exhaust gas reduction device to remove nitro oxides (NOx). SCR operation of ship can be controlled through valves for minimizing economic loss from SCR. Valve in SCR-high pressure (HP) system is directly connected to engine exhaust and operates in high temperature and high pressure. Long-term thermal deformation induced by engine heat weakens the sealing of the valve, which can lead to unexpected failures during ship sailing. In order to prevent the unexpected failures due to long-term valve thermal deformation, a failure prediction system using autoregressive integrated moving average (ARIMA) was proposed. Based on the heating experiment, virtual data mimicking temperature range around the SCR-HP valve were produced. By detecting abnormal temperature rise and fall based on the short-term ARIMA prediction, an algorithm determines whether present temperature data is required for failure prediction. The signal processed by the data collection algorithm was interpolated for the failure prediction. By comparing mean average error (MAE) and root mean square error (RMSE), ARIMA model and suitable prediction instant were determined.
Enhancement of Fall-Detection Rate using Frequency Spectrum Pattern Matching
이수환 ( Suhwan Lee ),오동익 ( Dongik Oh ),남윤영 ( Yunyoung Nam ) 한국인터넷정보학회 2017 인터넷정보학회논문지 Vol.18 No.3
To the elderly, sudden falls are one of the most frightening accidents. If an accident occurs, a prompt action has to be taken to deal with the situation. Recently, there have been a number of attempts to detect sudden falls using acceleration sensors embedded in the mobile devices, such as smart phones and wrist-bands. However, using the sensor readings only, the detection rate of the falls is around 65%. Ordinary daily activities such as running or jumping could not be well distinguished from the falls. In this paper, we describe our attempts on improving the fall-detection rate. We implemented a wrist-band fall detection module, using a three-axis acceleration sensor. With the pattern matching on the fall signal-strength frequency spectrum, in addition to the conventional signal strength measurement, we could improve the detection rate by 9% point. Furthermore, by applying two wrist-bands in the experiment, we could further improve the detection rate to 82%.
안전한 해상통신망을 위한 일반화된 WiMAX MMR 확장 프로토콜
이수환(Suhwan Lee),손주영(Jooyoung Son) 한국마린엔지니어링학회 2010 한국마린엔지니어링학회 학술대회 논문집 Vol.2010 No.10
Currently cost-effective communication technologies are needed for high speed data exchanges at sea. Wireless environments at sea require some specific communication security solutions as well. In this paper, a generalized version of the augmented WiMAX MMR protocol is proposed which we have newly developed following the restricted augmented version. That could be much closer to a realistic solution of broadband data communications and securities at sea which is mostly with no base station.
스마트 폰 기반 3D 프린팅 칩을 이용한 적혈구 변형성 측정
이수환(Suhwan Lee),홍현지(Hyeonji Hong),염은섭(Eunseop Yeom),송재민(Jae Min Song) 한국가시화정보학회 2020 한국가시화정보학회지 Vol.18 No.3
RBC (red blood cell) deformability is one of factors inducing blood shear thinning effect. Reduction of RBC deformability increases blood viscosity in high shear region. In this study, 3D printed chip with proper distribution of wall shear rate (WSR) was proposed to measure RBC deformability of blood samples. To fabricate 3D printed chip, the design of 3D printed chip determined through numerical simulation was modified based on the resolution of the 3D printer. For the estimation of pressure drop in the 3D printed chip, two bypass outlets with low and high WSR are exposed to atmospheric pressure through the needles. By positioning the outlet of needles in the gravity direction, the formation of droplets at bypass outlets can be captured by smartphone. Through image processing and fast Fourier transform (FFT) analysis, the frequency of droplet formation was analyzed. Since the frequency of droplet formation is related with the pressure at bypass, high pressure drop caused by reduction of RBC deformability can be estimated by monitoring the formation of blood droplets using the smartphone.