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반사면 위에서의 컴팩트 원형 하이브리드 소음 제어 시스템
이상현(Sanghyeon Lee),박영진(Youngjin Park) 한국소음진동공학회 2023 한국소음진동공학회 논문집 Vol.33 No.6
The compact hybrid noise control system is proposed to prevent noise-induced hearing loss of workers in industrial sites. Noise in a wide frequency band can be reduced through a hybrid method combining a noise barrier, which is a passive noise reduction method, and active noise control. Unlike conventional active noise barriers that use semi-infinite barriers and error microphones, a finite-sized circular barrier is used for movability, and a control filter based on theoretically calculated sound fields is applied without error microphones for convenience of installation and calibration. However, in the prior study, simulations and experiments were conducted under free field conditions. Because free field conditions are acceptable only in specific spaces, the verification of the compact hybrid noise control system on the ground is required for practical use. Therefore, in this study, the compact hybrid noise control system is examined on a reflecting surface. To retain the advantages of movability and simple installation, a theoretical model in the free field should be used to obtain a control filter. Nevertheless, it is shown that the noise in the target control space is reduced by approximately 6 dB in a frequency band of interest. It is also demonstrated that the noise reduction performance can be improved by suppressing the noise reflection through a sound absorbing material and active noise control.
가스터빈 연소기에서 메탄과 수소 혼합 비율 및 운전조건에 따른 연소특성 연구
이상현(Sanghyeon Lee),이재빈(Jaebin Lee),안병민(Byeongmin Ahn),강도원(Dowon Kang),김민국(Minkuk Kim),최민성(Minsung Choi) 한국연소학회 2023 KOSCOSYMPOSIUM논문집 Vol.2023 No.11
This study investigated the combustion characteristics in a gas turbine combustor with varying methane and hydrogen mixing ratios and operating conditions. We conducted study through CFD analysis and presented the results of temperature, velocity, fuel mixedness, and NOx emissions for hydrogen mixture. All simulations were conducted under high-pressure conditions at 25.9 bar, and hydrogen mixture were varied from 0% to 60%. The simulation results showed that as the mixture ratio increased, NOx exhibited the most significant difference, while the other parameters did not show a significant impact.
이상현(Lee, Sanghyeon) 한국노동연구원 2022 노동정책연구 Vol.22 No.1
이 연구는 간호조무사 실습생이 근로기준법상 근로자에 해당할 수 있는지와 그 보호방안을 검토한다. 법령에서 정한 바에 따라 의무적으로 병․의원에서 780시간 이상의 실습을 하는 간호조무사 실습생은 노무제공을 하고 있지만 근로기준법상 근로자로 인정받지 못하여 무급 노무제공, 업무상 재해 대책미비, 부당한 실습계약 해지 등의 문제를 겪고 있다. 무급 노무제공자에 대한 근로자 지위에 관한 논의는 계속 이루어지고 있지만 간호조무사 실습생과 같이 자격증 취득을 위한 의무 실습은 여전히 사각지대로 존재하고 있다. 이 글에서는 근로자 지위를 판단하는 종래의 판례 기준 등에 대한 검토와 함께 노무제공을 하는 간호조무사 실습생이 근로자 지위를 가질 수 있는지 검토하였다. 현재 실습계약의 외관이 임금을 목적으로 하고 있지 않은 점, 실습생은 교육훈련을 목적으로 하고 있는 점 등에도 불구하고 근로자 지위가 인정될 수 있는지가 주요 내용이다. 이러한 검토를 토대로 이들에게도 노동법의 보호가 필요하다는 것을 확인하고 그 보호방안에 대해 제언하였다. This study examines whether nursing assistant(licensed practical nurse) trainees can constitute employees under the Labor Standards Act and their protection measures. Nursing assistant(licensed practical nurse) trainees who practice more than 780 hours in hospitals and clinics are obligated to provide labor, but are not recognized as workers under the Labor Standards Act, resulting in problems such as unpaid labor, insufficient industrial accident measures, and unfair termination of training contracts. Although the review of the status of workers for unpaid labor providers continues, mandatory practice for obtaining certificates, such as nursing assistants(licensed practical nurses), still exists as blind spots. In this paper, along with a review of conventional precedent standards for judging employee status, it was reviewed whether nursing assistant(licensed practical nurse) trainees who provide labor can have employee status. The main content is whether the status of employees can be recognized despite the fact that the appearance of the current training contract is not for wage purposes and that trainees are for education and training purposes. Based on this review, it was confirmed that they also need to be protected under the labor law and protection measures are suggested.
동적 저궤도 위성 네트워크를 위한 Dueling DQN 기반 라우팅 기법
김도형,이상현,이헌철,원동식,Dohyung Kim,Sanghyeon Lee,Heoncheol Lee,Dongshik Won 대한임베디드공학회 2023 대한임베디드공학회논문지 Vol.18 No.4
This paper deals with a routing algorithm which can find the best communication route to a desired point considering disconnected links in the LEO (low earth orbit) satellite networks. If the LEO satellite networks are dynamic, the number and distribution of the disconnected links are varying, which makes the routing problem challenging. To solve the problem, in this paper, we propose a routing method based on Dueling DQN which is one of the reinforcement learning algorithms. The proposed method was successfully conducted and verified by showing improved performance by reducing convergence times and converging more stably compared to other existing reinforcement learning-based routing algorithms.