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미세 연소기 개발(I) - 소형 연소기 환경에서의 연소 특성 -
이대훈,최권형,권세진,Lee, Dae-Hun,Choe, Gwon-Hyeong,Gwon, Se-Jin 대한기계학회 2002 大韓機械學會論文集B Vol.26 No.1
Combustion phenomena in a sub-millimeter scale combustor have been investigated. To evaluate scale effect on flame propagation characteristics, a cylindrical combustion chamber with variable depth was built in-house. The combustor was charged with premixed gas of hydrogen and air and ignited electronically. A piezo electric pressure transducer recorded transient pressure after the ignition. Measurements were made at different test conditions specified with chamber depth and initial pressure as parameters. Visual observation was made through a quartz glass window on top side of the combustion chamber using high speed digital video camera. From the pressure data, available work was estimated and compared with energy input required for stable ignition. The preliminary results suggested that the net thermal energy release is sufficient to generate power and enables a combustor of the size in the present study to be used as the energy source of a micro power devices .
Li-ion 전지 성능 개선을 위한 플라즈마 기술 응용
이대훈,허민,Lee, Dae-Hun,Heo, Min 재료연구소 2010 機械와 材料 Vol.22 No.3
최근 아이폰, 아이패드 등으로 대표되는 소형 가전의 보급이 확대되고 있으며 hybrid 및 plug-in 전기자동차가 주목을 받으면서 2차 전지 기술에 대한 시장과 기술의 관심이 높아지고 있다. 2차 전지 기술은 기본적으로 전기 화학과 재료 분야 연구자들의 역할이 중요하지만 생산 및 공정이라는 관점에서 기계공학 연구자들이 기여할 부분들이 많이 있다. 본 논고에서는 특히 플라즈마 기술을 이용, 2차 전지의 성능 개선 및 혁신을 위한 기술적 접근 가능성에 대해 살펴보고 몇 가지 가능한 연구 주제들을 제시하고자 한다.
이대훈,권세진,Lee, Dae-Hun,Gwon, Se-Jin 대한기계학회 2002 大韓機械學會論文集B Vol.26 No.1
With the introduction of Fractal notation, various fields of engineering adopted fractal notation to express characteristics of geometry involved and one of the most frequently applied areas was turbulence. With research on turbulence regarding the surface as fractal geometry, attempts to analyze turbulent premised flame as fractal geometry also attracted attention as a tool for modeling, for the flame surface can be viewed as fractal geometry. Experiments focused on disclosure of flame characteristics by measuring fractal parameters were done by researchers. But robust principle or theory can't be extracted. Only reported modeling efforts using fractal dimension is flame speed model by Gouldin. This model gives good predictions of flame speed in unstrained case but not in highly strained flame condition. In this research, approaches regarding fractal dimension of flame as one representative value is pointed out as a reason for the absence of robust model. And as an extort to establish robust modeling, Presents methods treating fractal dimension as statistical variable. From this approach flame characteristics reported by experiments such as Da effect on flame structure can be seen quantitatively and shows possibility of flame modeling using fractal parameters with statistical method. From this result more quantitative model can be derived.
이대훈,김의화,이승미,Lee, Dae-Hun,Kim, Ui-Hwa,Lee, Seung-Mi 한국섬유공학회 1989 한국섬유공학회지 Vol.26 No.5
The microscopic structure of the yarn was observed in order to clarify the reason why the mechanical properties of the air-jet spun yarns differ from those of the ring or opened rotor yarns. Some structural parameters of the yarns were obtained by the tracer fibre technique. Zonal distributions of the constituent fibres were derived and the orientation density functions of the fibres in the several yarns were introduced by the statistical method. The distributions of the polar angle in all yarns have a good correlation with the radial direction of yarns, but those of azimuthal angles were random. It was observed microscopically that the air-jet spun yarns were constituted of the false twisted fibres, fasciated fibres, wrapping fibres and fuzz although their fractions will be changed by the spinning parameters. The most of the fibres in air-jet spun yarns are oriented to the yarn axis. Therefore the constituent fibres contact each other more closely, so that the yarn bulkiness decreases. The relative initial modulus of air-jet spun yarns is lower than that of ring or open-end rotor yarns and it is ascribed to the distribution of polar angles of the fasciated fibres in the air-jet spun yarns.
태권도 국가대표 선수들의 경기력 요인에 대한 탐색적 접근
이대훈(Lee, Dae-Hun),신민철(Shin, Min-Chul),강유원(Kang, Yu-Won) 한국체육과학회 2022 한국체육과학회지 Vol.31 No.5
The purpose of this study was to explore the performance factors of national taekwondo players and to present improvement and support measures for the factors. Research participants were seven female national team athletes participating in the 2022 World Taekwondo Championships, we used photovocie, participatory action research strategy. The process of photo-voice was categorized in the order of factors of the national Taekwondo players were categorized into internal and external factors. Sub-topics of the inner factors were ‘mirror that shines on me’, ‘fight against weight’, ‘time alone’, and ‘routine that protects me’, and the outer factors were categorized into ‘my own endorphins’, ‘fatal encounters’, and ‘growth in pain’. Based on the results of this study, we discussed on inherent performance factors and offered some suggestions for future improvement and support.
NH₃-CO₂용 캐스케이드 냉동시스템의 최대 성능 예측
이대훈(Dae-Hun Lee),전민주(Min-Joo Jeon),손창효(Chang-Hyo Son),오후규(Hoo-Kyu Oh) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.5
In this paper, cycle performance analysis of NH₃-CO₂(R717-R744) cascade refrigeration system is presented to offer the basic design data for the operating parameters of the system. The operating parameters considered in this study include subcooling and superheating degree and condensing and evaporating temperature in the ammonia(R717) high temperature cycle and the carbon dioxide low temperature cycle. The main results were summarized as follows : The COP of cascade refrigeration system increases with the increasing superheating degree, but decreases with the increasing subcooling degree. The COP of cascade refrigeration system increases with the increasing condensing temperature, but decreases with the increasing evaporating temperature. Therefore, superheating and subcoolng degree, compressor efficiency, and evaporating and condensing temperature of NH₃-CO₂(R717-R744) cascade refrigeration system have an effect on the COP of this system. A multilinear regression analysis was employed in terms of subcooling, superheating, evaporating, condensing, and cascade heat exchanger temperature difference in order to develop mathematical expressions for maximum COP and an optimum evaporating temperature.
The Torque Developed in Single Yarn Due to Yarn Tension
양중식,이대훈,이재곤,Yang, Jung-Sik,Lee, Dae-Hun,Lee, Jae-Gon The Korean Fiber Society 1986 한국섬유공학회지 Vol.23 No.1
실에 장력을 가할 때 발생하는 토오크를 두가지 경우에 대하여 구하였다. 실을 인장시킬 때 횡방향 수축이 업슨 경우를 고려하며, <수식>으로 표시되며 실의 부피변화가 없는 경우는, <수식>으로 표시된다. 19가닥의 고무사로 만든 모형실을 만들어 이 모형실에 하중을 가하고 그 때의 토오크를 측정하였다. 실의 연계수와 팩킹 팩터가 증가함에 따라서 토오크는 거의 직선적으로 증가하였다. 실의 네트 토오크는 연계수 뿐만아니라 실의 직경의 크기에 비례함을 알았다. The expressions of the torque due to applied yarn tension are derived in two cases, i.e., for the case of no lateral contraction in the yarn, <Equation> and for the case of constant volume change in the yarn, <Equation> Experiments are also performed with the model yarn made of 19 rubber-covered filaments. The torque increases almost linealy with the twist multiplier and packing factor of the yarn. The net yarn torque is proportional to yarn radius as well as twist multiplier.