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일기 예보를 이용한 기계 학습 기반의 레일 온도 예측 모델 개발
홍성욱(SungUk Hong),이현우(Hyunwoo Lee),박찬(Chan Park),정현석(Hyunsuk Jung),박철정(CheolJeong Park),김형욱,홍성경(SeongKyung Hong),조성진(Seong J Cho) 대한기계학회 2018 대한기계학회 춘추학술대회 Vol.2018 No.12
In railway safety management, rail-temperature is directly affects the buckling of rails is very important. The previous rail-temperature prediction models have been developed for predicting the rail-temperature, but lack of versatility and performance. In this study, we suggest a novel rai-temperature model based on machine learning with high performance and universally available. We constructed a monitoring station to measure rail-temperature and local weather conditions, and then performed the measurements for 10 months. Using measured data, we found new features that affect rail-temperature. The model was constructed using XGboost, one of the machine learning methods, and the optimal hyperparameter was selected through k-fold cross validation. Our novel rail-temperature model can be used anywhere in the world because rail-temperature can be predicted using only weather forecast data. In particular, the novel rail-temperature prediction model can predict the local rail temperature after 67 hours from the weather forecast of Korea Meteorological Administration. It is expected to help planning railway management plan.
자외선 차단 코팅을 위한 나노섬유 멤브레인 및 휴대용 전기방사 시스템 개발
이현우(Hyunwoo Lee),홍성욱(Sunguk Hong),박찬(Chan Park),정현석(Hyunsuk Jung),김형욱(Hyonguk Kim),박철정(Cheol Jeong Park),홍성경(Seong Kyung Hong),조성진(Seong J. Cho) 대한기계학회 2018 대한기계학회 춘추학술대회 Vol.2018 No.12
As the harmfulness of ultraviolet(UV) rays is widely known, it has become important to protect the skin from ultraviolet rays. However, current sunscreens have the disadvantages of promoting skin disorders due to chemical composition, and short duration. Here, we introduce a novel portable electrospinning system that can coat UV-blocking nanofibrous membrane. Conventional electrospinning systems are not portable, as they include a high voltage power supply(HVPS) that is large in size, heavy in weight, expensive and has a wired power supply. To overcome these limitations, we replaces HVPS with batteries and high-voltage amplifiers. Nanofibers contain nanoparticles to increase the UV blocking effect. In addition, we confirmed UV transmittance, water resistance, and removal test. Unlike conventional sunscreen agents, nanofiber-based sunscreen is expected to be very useful for organ transplant patients or skin disease patients who are vulnerable to UV rays.
나노 크랙 기반의 안정성 있는 One-step laser encapsulation sensor 개발
박찬(Chan Park),정현석(Hyunsuk Jung),이현우(Hyunwoo Lee),홍성욱(Sunguk Hong),김형욱(Hyonguk Kim),홍성경(Seong Kyung Hong),조성진(Seong J. Cho) 대한기계학회 2018 대한기계학회 춘추학술대회 Vol.2018 No.12
Recent, development of flexible strain sensors that can be attached directly onto the skin, such as wearable electronic devices, has attracted attention. However, flexible sensors are generally exposed to various environments, such as sweat, humidity or dust, which cause noise and shorten the sensor lifetimes. This study reports the development of a nano-crackbased flexible sensor with mechanically, thermally, and chemically stable electrical characteristics in external environments using a novel one-step laser encapsulation (OLE) method optimized for thin films. The OLE process allows simultaneous patterning, cutting, and encapsulating of a device using laser cutting and thermoplastic polymers. The processes are simplified for economical and rapid production. Sensors protected with OLE exhibit mechanical, thermal, and chemical stability under water-, heat-, dust-, and detergent-exposed conditions. As a result, we developed sensors that can be measured in various environments using OLE processes.