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Influence of Positional Changes of Arms and Legs to Electrocardiogram
Joo-Eun Song,Min-Ju Song,Ye-Sul Kim,Ha-Nuel Yang,Ye-Jin Lee,Dongju Jung 대한의생명과학회 2018 Biomedical Science Letters Vol.24 No.1
Electrocardiogram (ECG) is a widely used method to diagnose electrical activity of heart. Although it is a reliable and easy method, ECG could be interfered by electrical signals. One of the interfering signals is electromyogram (EMG) that is caused by muscle contraction in any parts of the body except heart. To avoid the EMG noise, an examinee is advised to be relaxed on supine position while measuring ECG. Sometimes, patients who can"t put their arms and legs down on bed due to some reasons such as cast on arms or legs necessarily have the EMG noise. But detailed information about how much of the noise could be induced by positional change of arms and legs has not been reported. Here we examined the noise by analyzing ECG data from 14 candidates, 7 males and 7 females. The ECG data was obtained using the standard 12 lead ECG. EMG noise was induced by raising arms and legs at 90°, 60° or 30°. Because arms are located close to the heart, noise by the raised arms was analyzed toward left or right arm separately. All of the examinees showed similar pattern of the EMG noise. EMG noise by positional change of left or right arm was clearly monitored in different limb leads. Change of leg positions induced the noise that was monitored in aVF of augmented leads and II and III of limb leads. There was a difference in degree of the noise between male and female examinees. In addition to the EMG noise, decrease of PR interval was monitored in particular positional changes, which was prominent in male examinees. These results will enlarge fundamental understanding about EMG noise in ECG.
송현우(Hyun Woo Song),문병우(Byung Woo Moon),최재구(Jae Gu Choi),최원석(Won Suk Choi),송동주(Dongju Song),구재민(Jae-Mean Koo),석창성(Chang-Sung Seok) 대한기계학회 2014 大韓機械學會論文集A Vol.38 No.12
가스터빈에 적용되는 열차폐코팅은 가동 중 반복적인 열피로에 의하여 파손되므로, 열차폐코팅의 내구성평가가 필요하다. 고온 환경에 노출된 열차폐코팅의 내부에는 열생성산화물(TGO)이 성장하게 되는데, 이러한 열생성산화물(TGO)의 성장은 열차폐코팅의 주요 파손 원인으로 알려져 있다. 따라서 TGO의 성장을 고려한 열차폐코팅의 내구성평가는 반드시 선행되어야 하는 연구이다. 본 연구에서는 김대진 등의 연구 결과로부터 열화시간에 따른 TGO 성장을 고려하여 유한요소해석을 수행하였으며, 이로부터 응력과 열화시간 사이의 관계를 도출하였다. 또한 열화시간에 따른 유한요소해석 결과와 김대진 등의 접착강도 시험 결과의 비교를 통하여 열차폐코팅의 내구성을 평가하였다. The thermal barrier coating (TBC) applied to a gas turbine can be damaged by repeated thermal fatigue during operation, so an evaluation of its durability is needed. Thermally grown oxide (TGO) is generated inside the TBC in a high-temperature environment. The growth of TGO is known to be the main cause of damage to the TBC. Therefore, the durability of TBC should be evaluated according to the growth of TGO. In this research, Kim et al."s work on the growth of TGO with aging was used as a basis for finite element analysis. The relationship between stress and aging was derived from the finite element analysis results. The durability of the TBC with aging was evaluated through a comparison between the results of the finite element analysis and a bond strength test.
Dongju Lee,Hwangjun Song IEEE 2011 IEEE transactions on multimedia Vol.13 No.4
<P>In this paper, we propose a Luby transform encoding pattern-aware symbol packetization algorithm to minimize the quality degradation of video streaming service caused by packet losses over wireless network. To achieve this goal, the relationship among Luby transform encoded symbols is analyzed based on Luby transform encoding pattern, and the proposed packetization algorithm is designed to minimize packet loss effects by reducing the dependency among packets conveying Luby transform encoded symbols. Finally, experimental results are provided to show the performance of the proposed algorithm.</P>
주현철(Hyunchul Joo),이동주(Dongju Lee),한상천(SangChun Han),송황준(Hwangjun Song) 한국통신학회 2012 韓國通信學會論文誌 Vol.37 No.2B
본 논문은 이종 무선망 환경에서 효과적인 영상 스트리밍 시스템에 대해 다룬다. 제안하는 영상 스트리밍 시스템은 파운틴 코드를 영상 스트리밍 서비스에 적합하도록 변형하고, 파운틴 코드의 지연 및 블록 복구 실패율 제약 조건들을 만족시키면서 다중 경로를 통해 영상 스트림의 비트율을 최대화한다. 마지막으로, 제안하는 시스템이 이종 무선망 환경에서 각 경로의 상태 정보를 기반으로 제어 변수를 동적으로 설정함으로써 고화질의 안정적인 영상 스트리밍 서비스를 사용자에게 제공할 수 있음을 보인다. In this paper, we propose an efficient video streaming system over heterogeneous wireless networks. The proposed system modifies fountain code for the video streaming service and maximizes the target video encoding rate using multiple paths while satisfying delay and block recovery failure rate constraints of fountain code. Finally, the proposed system provides the seamless video streaming service of high quality to subscribers by dynamic adaptation of control parameters based on the states of each path over heterogeneous wireless networks.
In-situ synthesis of TiC/Fe alloy composites with high strength and hardness by reactive sintering
Lee, Junho,Lee, Dongju,Song, Myung Hoon,Rhee, Wonhyuk,Ryu, Ho Jin,Hong, Soon Hyung Elsevier 2018 Journal of materials science & technology Vol.34 No.8
<P><B>Abstract</B></P> <P>Fe alloy composites reinforced with in-situ titanium carbide (TiC) particles were fabricated by reactive sintering using different reactant C/Ti ratios of 0.8, 0.9, 1 and 1.1 to investigate the microstructure and mechanical properties of in-situ TiC/Fe alloy composites. The microstructure showed that the in-situ synthesized TiC particles were spherical with a size of 1–3μm, irrespective of C/Ti ratio. The stoichiometry of in-situ TiC increased from 0.85 to 0.88 with increasing C/Ti ratio from 0.8 to 0.9, but remained almost unchanged for C/Ti ratios between 0.9 and 1.1 due to the same driving force for carbon diffusion in TiC<I> <SUB>x</SUB> </I> at the common sintering temperature. The in-situ TiC/Fe alloy composite with C/Ti=0.9 showed improved mechanical properties compared with other C/Ti ratios because the presence of excess carbon (C/Ti=1 and 1.1) resulted in unreacted carbon within the Fe alloy matrix, while insufficient carbon (C/Ti=0.8) caused the depletion of carbon from the Fe alloy matrix, leading to a significant decrease in hardness. This study presents that the maximized hardness and superior strength of in-situ TiC/Fe alloy composites can be achieved by microstructure control and stoichiometric analysis of the in-situ synthesized TiC particles, while maintaining the ductility of the composites, compared to those of the unreinforced Fe alloy. Therefore, we anticipate that the in-situ synthesized TiC/Fe alloy composites with enhanced mechanical properties have great potential in cutting tool, mold and roller material applications.</P>