대향류확산화염의 화염소화에 있어서 에지화염 역할에 관한 연구

정용호(Yong-Ho Chung),박대근(Dae-Geun Park),박정(Jeong Park),배대석,윤진한(Jin-Han Yun),길상인(Sang-In Keel),서상일 한국연소학회 2011 KOSCOSYMPOSIUM논문집 Vol.- No.42

The present study in nitrogen-diluted non-premixed counterflow flames with finite burner diameter experimentally investigates the important role of outer edge flame in flame extinction. Flame stability diagrams mapping the flame extinction response of nitrogen-diluted non-premixed counterflow flame to varying global strain rate in terms of burner diameter, burner gap, and velocity ratio are explored. Three flame extinction modes are identified: flame extinctions through the shrinkage of outer edge flame with as well as without having an oscillation of the outer edge flame prior to the extinction and flame extinction through a flame hole at the flame center. Measured flame surface temperature and numerical evaluation of the fractional contribution of each term in energy equation show that the radial conductive heat loss at flame edge destabilize the outer edge flame and the conductive heat addition as well as the convective heat addition to the outer edge from trailing diffusion flame to outer edge stabilizes the outer edge flame. The radial conductive heat loss at flame edge is the dominant extinction mechanism through the shrinkage of the outer edge flame. It is also shown that the reduction of flame length extends the flame extinction mode through the shrinkage of the outer edge flame to higher strain rate flame conditions.

마이크로 믹서 노즐 형상에 따른 수소 전소 화염 역화 특성

정용호(Yong Ho Chung),이원준(Won June Lee),황정재(Jeongjae Hwang),김민국(Min-Kuk Kim),민경욱(Kyungwook Min),조주형(Ju-Hyeong Cho),김한석(Han-Seok Kim),주해지(Hae-ji Ju) 한국연소학회 2022 KOSCOSYMPOSIUM논문집 Vol.2022 No.5

부력 효과의 최소화를 통한 대향류 확산화염 소화거동에 관한 실험적 연구

정용호(Yong Ho Chung),박정(Jeong Park),권오붕(Oh Boong Kwon),윤진한(Jin-Han Yun),길상인(Sang-In Keel),김영주(Young Ju Kim) 한국연소학회 2012 한국연소학회지 Vol.17 No.4

Experimental study was conducted to elucidate flame extinction phenomena in counterflow flame. Using a curtain helium flow significantly reduced buoyancy such that the flame can be positioned at the center between the upper and lower nozzles even at the velocity ratio of 1.0. The curves of critical diluent mole fraction versus global strain rate have C-shapes. The flame oscillation was observed prior to low strain rate flame extinction at both flame conditions with and without minimizing buoyancy force. The results show that, at low strain rate flame, the self-excitation frequency with the order of 1.0 Hz in the case of utilizing pure helium gradually decreases in increase of N₂ mole fraction in the curtain flow, meaning that buoyancy suppresses the self-excitation of the outer edge flame.

상호작용 하는 H₂-공기/CO-공기 예혼합화염에 미치는 H₂ 선호 확산 영향에 대한 수치적 연구

정용호(Yong Ho Chung),박정(Jeong Park),권오붕(Oh Boong Kwon),길상인(Sang In Keel),윤진한(Jin Han Yun) 한국연소학회 2013 한국연소학회지 Vol.18 No.4

The effects of preferential diffusion of hydrogen in interacting counterflow H₂-air and CO-air premixed flames were investigated numerically. The global strain rate was varied in the range 30-5917 s<SUP>-1</SUP>, where the upper bound of this range corresponds to the flame-stretch limit. Preferential diffusion of hydrogen was studied by comparing flame structures for a mixed average diffusivity with those where the diffusivities of H, H₂ and N₂ were assumed to be equal. Flame stability diagrams are presented, which show the mapping of the limits of the concentrations of H₂ and CO as a function of the strain rate. The main oxidation route for CO is CO + O₂ → CO₂ + O, which is characterized by relatively slow chemical kinetics; however, a much faster route, namely CO + OH → CO₂ + H, can be significant, provided that hydrogen from the H₂-air flame is penetrated and then participates in the CO-oxidation. This modifies the flame characteristics in the downstream interaction between the H2-air and CO-air flames, and can cause the interaction characteristics at the rich and lean extinction boundaries not to depend on the Lewis number of the deficient reactant, but rather to depend on chemical interaction between the two flames. Such anomalous behaviors include a partial opening of the upper lean extinction boundary in the interaction between a lean H2-air flame and a lean CO-air flame, as well as the formation of two islands of flame sustainability in a partially premixed configuration with a rich H₂-air flame and a lean CO-air flame. At large strain rates, there are two islands where the flame can survive, depending on the nature of the interaction between the two flames. Furthermore, the preferential diffusion of hydrogen extends both the lean and the rich extinction boundaries.

국제 표준을 위한 수소 충전 프로토콜 개발 현황

정용호(Yong-Ho Chung) 호서대학교 공업기술연구소 2021 공업기술연구 논문집 Vol.40 No.2

최근 차세대 에너지원으로 수소에너지가 주목받고 있으며, 특히 차량용으로 수소연료전지를 적용한 다양한 수소전기차가 개발 및 보급되고 있다. 이로 인해 수소전기차의 활발한 보급을 위한 중요한 인프라인 수소충전소의 보급이 활발히 진행되고 있으며, 해당 시설을 운영하는 핵심 기술인 충전 프로토콜에 대한 관심이 집중되고 있다. 기존에 운영 중인 충전소의 충전 규약은 SAE J2601을 적용하고 있으나, 해당 기준은 경량의 수소 차량에 적합한 방식으로, 대용량 혹은 다양한 모빌리티에 종합적으로 적용하기에는 한계점을 가지고 있다. 따라서 세계 각국의 다양한 신규 충전 프로토콜을 개발하기 위해 활발한 연구개발 활동을 진행하고 있으며, 자국에서 개발한 기술을 국제 표준화하려는 움직임도 점차 강해지고 있다. 본 연구에서 기존 프로토콜 및 최근 개발되고 있는 신규 프로토콜에 대해서 비교 분석하여 향후 진행 방향에 대해서 논의하고자 한다. Recently, hydrogen energy has been attracted as a next-generation energy source, and in particular, various hydrogen electric vehicles using hydrogen fuel cells for vehicles are being developed and distributed. As a result, the supply of hydrogen charging stations, which is an important infrastructure for the active dissemination of hydrogen electric vehicles, is actively progressing, and interest in the charging protocol, which is the core technology that operates the facility, is being focused. SAE J2601 is applied to the charging rules of existing charging stations, but this standard is suitable for lightweight hydrogen vehicles and has limitations in comprehensively applying it to large-capacity or various mobility. Therefore, active R&D activities are being carried out to develop various new charging protocols in countries around the world, and the movement to international standardize the technology developed in the country is also getting stronger. In this study, we intend to discuss the future direction by comparing and analyzing existing protocols and new protocols being developed recently.

나노 구조체를 활용한 바이오센서 연구

정용호(Yong-Ho Chung) 호서대학교 공업기술연구소 2020 공업기술연구 논문집 Vol.39 No.2

바이오센서 분야는 생체물질의 신호를 금속 전극을 통해 측정하여, 질병 마커의 검출이나, 환경 신호의 측정, 신호의 전자소자에의 응용 등을 주로 다루고 있다. 생체신호는 신호의 강도가 낮고, 외부 환경 변화에 따른 신호 편차로 인해 정밀한 측정이 어려워, 이를 개선하기 위해 다양한 연구들이 진행되고 있다. 구조적으로 불안정하고, 나노 수준의 크기를 갖는 생체물질의 신호를 측정하기 위해 금속 전극을 나노 수준으로 가공한 나노 구조체를 제작 및 활용하려는 다양한 연구가 있었으며, 본 연구에서는 특히 나노패터닝 기술을 활용한 전극 제작과 관련한 다양한 기술 및 연구결과를 소개하고, 향후 연구 방향에 대한 전망을 제시하고자 한다. The field of biosensors have mainly focused on the detection of disease markers, measurement of environmental signals, and application of signals to electronic devices by measuring signals of biological materials through metal electrodes. Bio-signals have low signal strength and, are difficult to accurately measure due to signal deviations according to the changes in external environments so that various studies have been conducted to improve them. There have been various studies to fabricate and utilize nanostructures processed with nano-level metal electrodes to measure signals of biological materials that are structurally unstable and have nano-level sizes. In this study, in particular, various technologies and research results related to electrode fabrication using nanopatterning technology are introduced, and prospects for future research directions are presented.

확률선택모형을 이용한 수출 중고 자동차 물동량 예측에 관한 연구 : 경인운하를 중심으로

정용호 ( Yong Ho Chung ) 한국유통경영학회 2009 유통경영학회지 Vol.12 No.1

기관지확장증의 임상적 고찰 (pp.273-278)

정용호 ( Yong Ho Chung ) 대한내과학회 1969 대한내과학회지 Vol.12 No.4

From January, 1965 to June, 1968, clinical observation was done for 129 cases of bronchiectasis, visited our department and pediatrics of Chonnam University Hospital. 1. The male-female ratio was 2: 1, and 2nd decade age group showed the highest incidence

부력의 영향을 최소화한 조건에서 대향류 확산화염의 화염 소화에 관한 실험적 연구

정용호(Yong Ho Chung),박진욱(Jin Wook Park),박정(Jeong Park),권오붕(Oh Boong Kwon),윤진한(Jin-Han Yun),길상인(Sang-In Keel) 한국연소학회 2014 한국연소학회지 Vol.19 No.2

Experiments were conducted to clarify role of the outermost edge flame on low-strain-rate flame extinction in buoyancy-suppressed non-premixed methane flames diluted with He and N2. The use of He curtain flow produced a microgravity level of 10-2-10-3g in N2- and He-diluted non-premixed counterflow flame experiments. The critical He and N2 mole fractions at extinction with a global strain rate were examined at various burner diameters (10, 20, and 25 mm). The results showed that the extinction curves differed appreciably with burner diameter. Before the turning point along the extinction curve, low-strain-rate flames were extinguished via shrinkage of the outermost edge flame with and without self-excitation. High-strain-rate flames were extinguished via a flame hole while the outermost edge flame was stationary. These characteristics could be identified by the behavior of the outermost edge flame. The results also showed that the outermost edge flame was not influenced by radiative heat loss but by convective heat addition and conductive heat losses to the ambient He curtain flow. The numerical results were discussed in detail. The self-excitation before the extinction of a low-strain-rate flame was well described by a dependency of the Strouhal number on global strain rate and normalized nozzle exit velocity.

높이 맵의 효율적인 뷰 의존적 표현

정용호(Yong Ho Chung),함원경(Won Kyung Hwam),박상철(Sang Chul Park) (사)한국CDE학회 2014 한국CDE학회 논문집 Vol.19 No.1

This paper proposes a procedure enabling the extraction of view-dependent triangular approximations from a height map. In general, procedures to approximate a height map use tree hierarchies. These methods, however, have a limitation in terms of accuracy, because they depend on tree hierarchy than terrain features. To overcome the difficult, we apply the simplification method for triangular meshes to a height map. The proposed procedure maintains full decimation procedure to support multiresolution. The maintenance of decimation procedure results in creation of the groups (trees), each of which consists of vertices that can be merged into one vertex (root node). As the groups have tolerance which is determined by some tests, they support the generation of view-dependent arbitrary triangular meshes.