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수치해석을 이용한 와이어-쏘 자유면의 진동저감 효과 분석
유명한(Myeong han Yu),안성권(Sung kwon Ahn),사공명(Myung Sagong),류성하(Sung ha Ryu) 한국철도학회 2014 한국철도학회 학술발표대회논문집 Vol.2014 No.10
현재 국내 터널발파 시 주로 사용되고 있는 방법은 Drilling & Blasting mehtod를 사용한다. 하지만 이 공법으로 터널을 시공하면 주변에 존재하는 각종 구조물과 가옥에 피해를 입힌다. 이에 본 연구에서 터널 발파 시 와이어-쏘의 선절취 후 자유면에 대한 진동저감효과를 확인하기 위하여 동역학적 유한요소 수치해석을 실시하였다. 와이어-쏘의 선절취 시 암반에 자유면이 생기게 되어 화약이 폭발할 때 매질에 대한 진동의 전달이 감소하게 된다. 수치해석을 실시한 결과 발파 발생지역에서 이격 거리별 변위는 자유면이 있는 model에서의 변위보다 자유면이 없는 model에서의 변위가 크게 측정되는 것을 확인 할 수 있었다. In modern days, most common use of tunnel blasting method is Drilling & Blasting. But this method is some problem that is Vibration and Noise During the process of blasting. In this study a dynamic numerical analysis has been performed in order to confirm the effect of free surface of wiresaw in tunnel blasting process. The result is that displacement value no free surface lager than freesurface.
유비쿼터스 및 모바일 컴퓨팅 : SWoT 기반 실시간 모니터링 시스템 개선
유명한 ( Myung Han Yu ),김상경 ( Sangkyung Kim ) 한국정보처리학회 2015 정보처리학회논문지. 컴퓨터 및 통신시스템 Vol.4 No.7
USN-based real-time monitoring systems, which receive raw data from sensor nodes and store the processed information in traditional servers, recently get to be replaced by IoT(Internet of Things)/WoT(Web of Things)-based ones. Especially, Social Web of Things(SWoT) paradigm can make use of cloud storage over Social Network Service(SNS) and enable the possibility of integrated access, management and sharing. This paper proposes an improved SWoT-based real-time monitoring system which makes up for weak points of existing systems, and implements monitoring service integrating a legacy sensor network and commercial SNS without requiring additional servers. Especially, the proposed system can reduce emergency propagation time by employing PUSH messages.
CoAP 기반 센서네트워크를 위한 SWoT 서비스 탐색
유명한 ( Myung Han Yu ),김상경 ( Sang Kyung Kim ) 한국정보처리학회 2015 정보처리학회논문지. 소프트웨어 및 데이터 공학 Vol.4 No.9
On the IoT-based sensor networks, users or sensor nodes must perform a Service Discovery (SD) procedure before access to the wanted service. Current approach uses a center-concentrated Resource Directory (RD) servers or P2P technique, but these can cause a point-of-failure or flooding of SD messages. In this paper, we proposes an improved SWoT SD approach for CoAP-based sensor networks, which integrates Social Web of Things (SWoT) concept to current CoAP-based SD approach that makes up for weak points of existing systems. This new approach can perform a function like a keyword or location-based search originated from SNS, which can enhances the usability. Finally, we implemented a real system to evaluate.
기울기량 검출용 IoT 센서노드의 측정 및 전송방법의 개선
유명한(Yu Myung-han),송호승(Song Ho Seung) 대한전기학회 2021 대한전기학회 학술대회 논문집 Vol.2021 No.10
기존의 기울기량 검출용 IoT 센서노드는 각도 측정, 데이터 변환 및 저장, 무선전송의 세 단계 절차를 반복하며 동작한다. 본 연구는 IoT 센서노드 성능개선 중 가장 큰 이슈인 전력효율 측면에서 해당 절차를 개선하였다. 이는 설정된 주기에 따라 반복하여 측정/전송하는 기존 절차와 달리, 실제로 특정한 각도 이상의 물리적인 입력이 있을 경우에만 데이터를 측정 및 바로 전송하도록 하고, 그 이외의 시간에는 IoT 센서노드의 전원을 완전히 소거한다. 주기적으로 발신하는 상태확인 메시지 또한 별도의 워치독(Watchdog) 타이머를 통해 구현하여 전력소비량을 최소화한다. 실험을 통해 측정과정에서 발생하는 전력소비량을 줄이고 무선 데이터량이 줄어들었음을 확인한다. The existing IoT sensor node for detecting the amount of inclination operates by repeating the three-step procedure - angle measurement, data conversion and storage, and wireless transmission. This study improved the procedure in terms of power efficiency, which is the biggest issue among IoT sensor node performance improvement. Unlike the existing procedure of repeatedly measuring and transmitting according to a set period, data is measured and transmitted immediately only when there is a physical input over a certain angle, and the power of the IoT sensor node is completely removed at other times. The periodically transmitted status check message is also implemented through a separate watchdog timer to minimize power consumption. Through the experiment, it is confirmed that the power consumption generated during the measurement process is reduced and the amount of wireless data is reduced.
동축 공기다단 LPG화염의 NOx 생성특성에 관한 연구
김한석,안국영,김호근,유명종,백승욱,Kim, Han-Seok,Ahn, Kook-Young,Kim, Ho-Keun,Yu, Myung-Jong,Baek, Seung-Wook 대한기계학회 2003 大韓機械學會論文集B Vol.27 No.2
Experimental and numerical studies have been done to examine the effects of excess air ratio and tertiary air swirl number on the formation characteristics of NOx in a pilot scale combustor adopting a multi-air staged burner. In numerical calculation the mathematical models for turbulence, radiation and nitric oxide chemistry were taken into account. The radiative transfer equation was solved using the discrete ordinates method with the weighted sum of gray gases model. In the NOx chemistry model, the chemical reaction rates for thermal and prompt NOx were statistically averaged using a probability density function. The results were validated by comparison with measurements. For the experiment, a 0.2 MW pilot multi-staged air burner has been designed and fabricated. Using the numerical simulation developed here, a variation of thermal and prompt NOx formation was predicted by changing the excess air ratio and tertiary air swirl number. As the excess air ratio increased up to 1.9, the formation of the total as well as thermal NOx at exit increased while the prompt NOx decreased. The formation of thermal NOx was more affected by concentration of $O_2$ and $N_2$ than gas temperature. When the tertiary air swirl number increased, the formation of the total as well as the prompt NOx slightly decreased.