메탄/공기 층류 부분예혼합화염의 상세 라디칼(OH*, CH* 그리고 C₂*) 정보와 배기매출물에 관한 실험적 연구

정용기,오정석,전충환,장영준,Jeong Yong Ki,Oh Jeong Seog,Jeon Chung Hwan,Chang Young June 대한기계학회 2005 大韓機械學會論文集B Vol.29 No.2

An experimental study was performed to investigate the effects of partially premixing, varying the equivalence ratios from $0.79{\sim}{\infty}$, on NOx emissions and chemiluminescence of excited $OH^{\ast},\;CH^{ast}\;C_2^{\ast}$ radicals in laminar partially premixed flames. the signal from the electronically excited state of $OH^{\ast},\;CH^{ast}\;C_2^{\ast}$ was detected through a band pass filter with a photo multiplier tube, which are processed to the intensity ratio ($C_2^{\ast}/CH^{\ast},\;C_2^{\ast}/OH^{\ast},\;and\;CH^{\ast}/OH^{\ast}$) to reveal the correlation with local equivalence ratio. And measurements of NOx emission were made to investigate the relationship between visible flame appearance, chemiluminescence, and EINOX. The results demonstrated that (1) the flames at ${\phi}<1.59$ exhibited classical double flame structure, at ${\phi}>4.76$, the flames exhibited diffusion flame structure, and the intermediate flames at $1.59<{\phi}<4.76$ was a merged flame, (2) the $OH^{\ast}$ peak was located inside the $CH^{\ast}\;and\;C_2^{\ast}$ radical for all measured conditions and the emission intensity ratio of $C_2^{\ast}/CH^{\ast}\;and\;C_2^{\ast}/OH^{\ast}$ were identified as good marker for local equivalence ratio over a range of ${\phi}=0.79{\sim}1.2\;and\;CH^{\ast}/OH^{\ast}\;is\;0.79<{\phi}<1.9$. However, it was difficult to predict the equivalence ratio in partially premixed flames using this system for ${\phi}>2.38$, (3) the minimum NOX emission index (EINOx) is obtained for a equivalence ratio of 3.19 in the intermediate flames.

Protective Effects of Portulaca oleracea L. Extract against Matrix Metalloproteinase Production and Reactive Oxygen Species Generation Induced by Ultraviolet B Radiation in Human Keratinocytes

Jung Hwan Oh(오정환),Fatih Karadeniz(파티 카라데니즈),Jung Im Lee(이정임),So Young Park(박소영),Youngwan Seo(서영완),Chang-Suk Kong(공창숙) 한국생명과학회 2018 생명과학회지 Vol.28 No.8

쇠비름(Portulaca oleracea.L)은 쇠비름과에 속하는 한해살이풀로서 리놀렌산과 같은 불포화지방산, 페놀성 화합물, 플라보노이드, 비타민 C, 미네랄 함량이 높은 것으로 보고되어 있다. 본 연구에서는 쇠비름 추출물을 이용하여 UVB를 조사한 인간각질형성세포에서 광노화 억제능을 확인하였다. Matrix metalloproteinases는 세포의 기질을 분해하는 효소로 MMP-1는 collagenase, MMP-2와 MMP-9는 gelatinases로 피부 진피층을 구성하는 type Ⅰ collagen을 분해시키는데 영향을 미친다. UVB를 조사한 인간각질형성세포에서 쇠비름 추출물을 처리했을 때 MMP-1, -2, -9의 발현이 감소하였으며, type Ⅰ procollagen의 발현은 증가하는 것으로 나타났다. 또한 쇠비름 추출물을 처리한 군에서 UV에 의한 ROS 생성이 감소하였는데 이는 Nrf-2의 활성화를 통한 항산화 인자 SOD-1과 OH-1의 발현 증가로 인해 세포내 ROS 생성이 감소한 것으로 사료된다. 따라서 본 연구 결과를 통해 쇠비름 추출물이 UVB를 조사한 인간각질형성세포에서 MMP 인자 및 항산화 인자의 발현 조절을 통해 광노화로부터의 세포 보호능을 가지는 것을 확인하였으며 나아가 화장품 소재로서의 개발 가능성을 확인하였다. Portulaca oleracea L. is an edible plant widely consumed in daily diet throughout Europe, Asia and America. In this study, protective effects of P. oleracea L. extracts against oxidative stress and matrix metalloproteinase (MMP) activity induced by ultraviolet B (UVB) radiation were investigated using HaCaT immortal human keratinocytes. In this context, the mRNA and protein productions of MMPs (MMP-1, -2, and -9) and type I procollagen, which are major markers of photoaging induced by UVB radiation in HaCaT keratinocytes, were evaluated. Furthermore, UVB-induced reactive oxygen species (ROS) generation and mRNA and protein expression levels of superoxide dismutase-1 (SOD-1), oxygenase-1 (OH-1), and nuclear factor-erythroid 2-related factor-2 (Nrf-2), all of which are associated with the antioxidant balance, were investigated. As shown by the results, UVB radiation induced ROS formation and led to increased production of MMPs and decreased collagen production in human keratinocytes, which resulted in skin photoaging or photodamage. The treatment with P. oleracea L. extracts downregulated MMP (MMP-1, -2, and -9) production and upregulated type I procollagen expression in UVB-induced HaCaT cells. Furthermore, treatment with the extracts decreased UVB-induced ROS generation and increased the expression of antioxidant enzymes, such as SOD-1 and OH-1, through the Nrf-2 pathway. Taken together, these results suggest that P. oleracea L. extracts could be a potential cosmeceutical agent for the prevention of skin photoaging or photodamage.

Role of LuxIR Homologue AnoIR in Acinetobacter nosocomialis and the Effect of Virstatin on the Expression of anoR Gene

( Man Hwan Oh ),( Chul Hee Choi ) 한국미생물 · 생명공학회 2015 Journal of microbiology and biotechnology Vol.25 No.8

Quorum sensing is a process of cell-to-cell communication in which bacteria produce autoinducers as signaling molecules to sense cell density and coordinate gene expression. In the present study, a LuxI-type synthase, AnoI, and a LuxR-type regulator, AnoR, were identified in Acinetobacter nosocomialis, an important nosocomial pathogen, by sequence analysis of the bacterial genome. We found that N-(3-hydroxy-dodecanoyl)-L-homoserine lactone (OH-dDHL) is a quorum-sensing signal in A. nosocomialis. The anoI gene deletion was responsible for the impairment in the production of OH-dDHL. The expression of anoI was almost abolished in the anoR mutant. These results indicate that AnoI is essential for the production of OH-dDHL in A. nosocomialis, and its expression is positively regulated by AnoR. Moreover, the anoR mutant exhibited deficiency in biofilm formation. In particular, motility of the anoR mutant was consistently and significantly abolished compared with that of the wild type. The deficiency in the biofilm formation and motility of the anoR mutant was significantly restored by a functional anoR, indicating that AnoR plays important roles in the biofilm formation and motility. Furthermore, the present study showed that virstatin exerts its effects on the reduction of biofilm formation and motility by inhibiting the expression of anoR. Consequently, the combined results suggest that AnoIR is a quorum-sensing system that plays important roles in the biofilm formation and motility of A. nosocomialis, and virstatin is an inhibitor of the expression of anoR.

메탄 공기 층류 부분 예혼합화염에서 예혼합 정도에 따른 화염구조와 질소산화물의 배출에 미치는 영향에 관한 연구

오정석(Jeong Seog Oh),정용기(Yong Ki Jeong),전층환(Chung Hwan Jeon),장영준(Young June Chang) 대한기계학회 2003 대한기계학회 춘추학술대회 Vol.2003 No.11

It is shown that the effect of variable parameters on flame structures and NOx emissions in the laminar<br/> partially premixed methane-air flames with a co-axial Bunsen burner. Objectives of this paper is to<br/> understand the effects of flow variables on NOx emissions and the flame structure with OH<br/> chemiluminescence, including reconstructed image by abel inversion processing at each conditions. A fuel<br/> flowrate of 200 [cc/min] was fixed and the amount of air was varied from 400 to 1200 [cc/min]. The<br/> experimental variables were equivalence ratio( ), fuel split percentage( ) and inner tube recess(x/D). Flow<br/> conditions were ranged from 1.36~4.76(equivalence ratio), 50~100(fuel split percentage) and 0~20(inner<br/> tube recess). NOx analyzer and ICCD camera with a OH filter were used as a main experimental<br/> apparatus. In addition, Abel inversion, which is a kind of tomography and valuable to estimate a<br/> two-dimensional structure of co-axial flames from cubical information, was employed for combustion<br/> diagnostics. Results from this study indicate that the main effects depend on equivalence ratio and next<br/> sigma, x/D for NOx production and OH formation. Throughout Abel inversion, we could affirm the<br/> maximum position and the tendency of OH radical intensity by variants at five axial heights above the<br/> burner exit.

개교환자에 있어서 Digital Sound Spectrograph를 사용한 음향 음성학적 비교연구

오득재,이환수,김오환 全北大學校 齒醫學硏究所 1993 전북치대논문집 Vol.11 No.1

The purpose of this study was to comparing the speech of openbite patients with normal adults and taking the fundamental data for comparing changes in post-orthognathic surgery state. Studies in speech changes of orthognathic surgery have been examined by subjective evaluation. Thus we were taken the objective results using a digital sound spectrogaph with computer-based speech analysis system. One experimental group and one control group were used for this study. They were respectively composed of six openbite patients and ten normal adults with Angles' classification Ⅰ. The results were as follows : 1. In openbite patients, Articulatory positions are formed posteriorly in pronouncing the vowel sounds. 2. Low articularoty sounds were shown in tone color(bandsidths of the first, second formants) of speech of openbite patients. 3. There was no forming the pronouncing constriction remarkable in fricative sound of openbite patinets. 4. There was the delay appearance of articulation reaction time to enlargement of total duration, vowedl duration in openbite patients.

機械加工品의 最適加工速度에 關한 硏究

成煥泰,吳澤烈,吳煥燮 慶熙大學校 1980 論文集 Vol.10 No.-

In this study, the optimum mathematical models were made in order to derive Optimum Machining speed which is due to be established in the production of each manufactures as an important parameter based upon the cutting speed, in case of making manufactures of multi-kinds into unit-production processing. The economical optimum cutting speed has been set up by using the above phenomenon as a proper system, and the results from the comparative analysis between the above model & the actual cutting work data, are summarized as follows. (1) The mathematical models for the optimum machining speed are derived into the expressions (23), (24), (25), (26), (27), (28), (29). (2) The basic expressions of the optimum machining speed are derived into (32), (34), (36), (37), (39), (40), (41), (44), for the purpose of each estimation of the maximum efficiency standard, the minimum cost standard and the maximum profits rate standard. (3) The example of setting up the optimum cutting speed of multi-kinds manufacturing production was formulated, and the experimental theoretical values were known to be in the same range as a result of the comparative study between the cutting speed obtained by the cutting test & the optimum cutting speed calculated by the theoretical expressions.

공공기술 기반 여성기술창업에 관한 탐색적 연구: 여성연구소기업을 중심으로

오영환(Oh, Young-Hwan),정양헌(Chung, Yang-Hon) 한국경영교육학회 2021 경영교육연구 Vol.36 No.4

[연구목적] 본 연구에서는 여성기술창업에 대한 연구가 미흡한 시점에서 공공기술을 기반으로 설립되는 여성연구소기업의 창업가에 대한 인터뷰를 통해 창업 동기, 목적, 창업아이템 선정, 사업화 과정, 특성 등을 파악하여 연구소기업이 여성기술창업 지원제도로서 적합한가와 여성기술창업의 활성화방안을 살펴보고 시사점을 제공하고자 하였다. [연구방법] 본 연구는 질적 연구방법론인 근거이론에 대한 이론들과 기존에 수행되었던 여성기술창업, 연구소기업 등의 연구들을 충분히 검토하고, 8명의 연구소기업의 여성창업가를 대상으로 인터뷰를 진행하였다. 근거이론의 탐색적 접근방법을 통해 인터뷰 내용을 개방코딩, 축 코딩, 선택코딩 등으로 분석하여 여성기술창업의 특성을 확인해 보았다. [연구결과] 연구결과로 공공기술을 기반으로 설립된 연구소기업은 연구개발특구의 설립지원, 기술사업화 과제, 성장 지원 등과 대학 및 연구원의 기술지원 등으로 유익한 여성기술창업지원 제도이다. 따라서 주도적 개인 성향과 기술 기반의 창업역량을 보유한 예비 여성창업가를 적극 발굴하여 여성연구소기업을 더욱더 확대해야 한다. [연구의 시사점] 본 연구는 여성기술창업의 활성화를 위해 여성 친화적 기술 및 제품과 연계된 기술창업지원 프로그램 확대, 여성연구소기업에 대한 지원 확대 및 우대, 창업기업의 기술사업화를 위한 기술지원과 사업화 프로그램 강화, 여성창업가의 일과 가정의 양립으로 인한 어려움을 해소할 수 있는 인력지원 등이 확대되어야 한다는 시사점을 제공한다. [Purpose] In this study, we interviewed women CEO in Research Institute Companies established to identify their startup motivations, the purpose of a startup, the selection of startup items, the commercialization process, and the characteristics of women-led technology startups to provide implications and examine whether a Research Institute Spin-off Company is suitable and expandable as a women-led technology startup support system. [Methodology] This study conducted interviews with 8 women CEO of Research Institute Spin-off Companies. Through the grounded theory, the interview contents were analyzed to identify the characteristics of women-led startups. [Findings] As a result of research, it is show that a Research Institute Spin-off Company established based on public technology is a beneficial women-led technology startup support system, having the support from the INNOPOLIS, technology commercialization projects, various growth supports, and technical support from universities and research institutes. It is suggested that women-led Research Institute Spin-off Companies should be further expanded by actively discovering prospective women entrepreneurs that have a personal tendency of playing a leading role and entrepreneurship capable of building a technology startup. [Implications] This study suggests that in order to revitalize women-led technology startups, there needs to be an expansion of technology startup support programs connected to women-friendly technologies and products, expanded support and preference towards women-led Research Institute Spin-off Companies, expansion of technology and commercialization support to resolve the difficulties of technology commercialization, and personnel support to relieve the work-family balance of women entrepreneurs.

The prediction of the tooth size in the mixed dentition for Korean

Moon, Sung-Hwan,Kim, Seong-Oh,Yu, Hyung-Seong,Choi, Byung-Jai,Choi, Hyung-Jun,Lee, Jae-Ho 大韓小兒齒科學會 2006 大韓小兒齒科學會誌 Vol.33 No.2

이번 연구의 목적은 혼합치열기 아동에서 미맹출된 견치와 소구치의 크기를 예측하는데 있어서 한국인에 맞는 방정식을 만들기 위함이다. 미맹출 치아의 크기를 예측하는 것은 혼합치열기 교정 진단과 치료계획 수립에 있어서 매우 중요하다. 미맹출된 견치와 소구치 크기를 예측하는 방법은 몇가지가 있지만 그중에서도 가장 흔하게 쓰이는 것이 모이어의 예측표와 다나카와 존스턴의 방정식이 있다. 하지만 그것들은 백인을 위해서 제작된 것이고 치아 크기는 인종에 따라서 다르다고 알려져 있다. 이번 연구에서는 치아크기를 측정하여 하악 영구 절치의 크기 합과 견치 및 소구치의 크기 합 사이의 상관관계를 구하고 회귀방정식을 이용해서 한국인에 맞는 예측표를 만들었다. 연세대학교 치과대학에 재학중인 178명의 한국 학생(남 108명, 여 70명, 평균연령 21.63)을 대상으로 실험하였다. 영구치의 근원심 폭경을 석고모형상에서 calipers를 이용해서 측정하였다. 성별간의 치아 크기는 차이가 있었다(p<0.05). Correlation coefficient는 0.57에서 0.64의 범위였고, standard errors of the estimates 는 여성에서 0.6으로써 남성보다 우수하였다. r^(2)값은 0.27에서 0.41의 범위를 나타내었다. Estimating the size of unerupted teeth is an essential aspect of orthodontic diagnosis and treatment planning in the mixed dentition. Several methods were introduced and used for the prediction. The most common methods among these would be Moyers probability chart and Tanaka and Johnston equations. These are currently used widely, but they were developed for Caucasians. Because there are clear racial differences in teeth size, the objectives of this study were to produce correlation coefficients between the combined mesiodistal widths of the permanent mandibular incisors and those of the canines and premolars for each quadrant, and prediction tables with regression equations, specifically for Korean. 178 young adults (70 women, 108 men, mean age 21.63 years) were selected from the College of Dentistry, Yonsei University, Seoul, Korea. The mesiodistal crown diameters of the permanent teeth were measured with calipers. Significant sexual dimorphism was found in tooth sizes. The correlation coefficients between the total mesiodistal width of the mandibular permanent incisors and those of the maxillary and mandibular canines and premolars were found to be between 0.52 and 0.64. The standard error of the estimatation was better (0.60) for women and the r^(2) values ranged from 0.27 to 0.41 for both sexes, Prediction tables were prepared for Korean. This study showed larger canine and premolar diameters than Tanaka and Johnston's and Moyers' studies which might be due to the racial differences. Further investigations with a larger sample size will be needed for more representative data on the Korean population.

이중동축 메탄/공기 층류 부분 예혼합화염에서의 화염구조와 자발광 배출 특성 안쪽관 연료주입의 영향

오정석(Jeong Seog Oh),정용기(Yong Ki Jeong),전충환(Chung Hwan Jeon),장영준(Young June Chang) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.11

In this study, the effect of central fuel injection on a coaxial laminar CH₄/air flame was experimented at the defined premixing condition(φ=1.90, σ=50/75/100%, x/D=10). The partial premixing parameter are the equivalence ratio that total fuel is fixed at 200cc/min, the fuel split degree which means the percentage of fuel entering the outer tube to the total amount, and the mixing distance indicating the nonreactant mixture's homogeneity between inner tube top and burner exit. The object is to investigate the flame structure and chemiluminescence characteristics of laminar partial premixed flame as changing mixing parameters. The radical signal was acquired from ICCD camera and PMT. Each intensity was compared with Abel inverted value for measuring the effect of background light on the peak signal location and the intensity at central preheat zone. The results show that the peak location of each radical was broaden as the fuel split degree increasing because the mixing quality was enhanced. and OH* is a good indicator for flame front between reaction and preheat zone. At last C₂* has the same tendency with CH* but a thinner reaction zone than CH* due to a rapid decay on the burned gas side.

BEM을 이용한 크랙전파 해석 및 수명예측에 관한연구

吳煥燮,結城良治 慶熙大學校 材料科學技術硏究所 1992 材料科學技術硏究論集 Vol.5 No.-

Stress analysis of surface crack tips becomes very important in the recent development of leak-before-break(LBB) concepts. In this study the stress intensity falter k analyzed by considering the fatigue fracfure process which is characterized by interface coalesence and growth. Criteion parameters derived from the stress intensity factor obtained from the boundary element method(BEM) are used to predict the fatigue life. We develop the surface crack growth analysis system using the stress intensity factor data base and also fatigue crack growth law. The results are obtained as some kind of fatigues.