hojun Yang

Mr. hojun Yang

HCI laboratory
orcid

Research Focus & Metrics

Academic Career Length

7Years (2020-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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9 February 2021 in Applied Sciences
Verified
Journal Article
Open access
PDF file
SeonWoo LeeSeonWoo Lee
SeonWoo Lee
HYHyeontak Yu
Hyeontak Yu
hojun Yanghojun Yang
hojun Yang
ISINSEO SONG
INSEO SONG
JCJungMu Choi
JungMu Choi
JKJangwoo Kwon
Jangwoo Kwon
Hypergravity accelerators are a type of large machinery used for gravity training or medical research. A failure of such large equipment can be a serious problem in terms of safety or costs. This paper proposes a prediction model that can proactively prevent failures that may occur in a hypergravity accelerator. An experiment was conducted to evaluate the performance of the method proposed in this paper. A 4-channel accelerometer was attached to the bearing housing, which is a rotor, and time-amplitude data were obtained from the measured values by sampling. The method proposed in this paper was trained with transfer learning, a deep learning model that replaced the VGG19 model with a Fully Connected Layer (FCL) and Global Average Pooling (GAP) by converting the vibration signal into a short-time Fourier transform (STFT) or Mel-Frequency Cepstral Coefficients (MFCC) spectrogram and converting the input into a 2D image. As a result, the model proposed in this paper has seven times decreased trainable parameters of VGG19, and it is possible to quantify the severity while looking at the defect areas that cannot be seen with 1D.

25 December 2020 in Preprints.org
Verified
Preprint
Open access
SeonWoo LeeSeonWoo Lee
SeonWoo Lee
HYHyeontak Yu
Hyeontak Yu
hojun Yanghojun Yang
hojun Yang
ISInSeo Song
InSeo Song
JYJaeHeung Yang
JaeHeung Yang
JKJangWoo Kwon
JangWoo Kwon
Hypergravity accelerators are a type of large machinery used for gravity training or medical research. A failure of such large equipment can be a serious problem in terms of safety or costs. This paper proposes a prediction model that can proactively prevent failures that may occur in a hy-pergravity accelerator. The method proposed in this paper was to convert vibration signals to spectograms and perform classification training using a deep learning model. An experiment was conducted to evaluate the performance of the method proposed in this paper. A 4-channel accel-erometer was attached to the bearing housing, which is a rotor, and time-amplitude data were obtained from the measured values by sampling. The data were converted to a two-dimensional spectrogram, and classification training was performed using a deep learning model for four conditions of the equipment: Unbalance, Misalignment, Shaft Rubbing, and Normal. The ex-perimental results showed that the proposed method had a 99.5% F1-Score, which was up to 23% higher than the 76.25% for existing feature-based learning models.