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.

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.

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.

슬개골 골절과 동반된 후방 십자인대 손상

오정환,신규철 건국대학교 의과학연구소 1994 건국의과학학술지 Vol.4 No.-

Patellar fractures result from direct and/or indirect forces. The majority of the patellar fractures result from direct injuries and a fall on the knee or a direct blow sustained in the vehicular trauma is one of the common causes. Patellar fractures from indirect forces occur when the intrinsic strength of the patella is exceeded by the pull of the musculotendinous and ligamentous units attaching to it and typically occurs in the act of stumbling or partially falling. Posterior cruciate ligament disruption is generally caused by a posteriorly directed force on the proximal tibia, and hyperextension with abduction or external rotation movements have been also described in the production of posterior cruciate ligament injuries. Posterior cruciate ligament injuries are apt to be negelected frequently, and ipsilateral femoral shaft fracture or posterior dislocation of the hip also may be seen with direct injuries to the patella, but patellar fractures are rarely associated with posterior cruciate ligament injuries. So we are reporting four cases of the posterior cruciate ligament injuries as one of the combined entity, which had been neglected and associated with the patellar fracture after a review of the literatures.

경골 외과 건열골절 : Segond 골절, 외측 관절낭 징후 Segond Fracture or Lateral Capsular Sign 발생빈도, 손상기전, 임상적 의의, 및 치료 A Clinical Study of Their Incidence and Correlation in Four Cases

오정환 건국대학교 의과학연구소 2004 건국의과학학술지 Vol.13 No.-

Purpose : To evaluate the incidence, injury mechanism, clinical significance, and its treatment for the avulsion fracture of the lateral tibial condyle (or Segond fracture). Materials and Methods : Four cases of the avulsion fracture of the lateral tibial condyle (or Segond fracture) among 86 ACL injuries (4.7%) at the Konkuk University Min-Joong Hospital from September, 1993 to August, 1998 were evaluated. All were arthroscoped and managed according to the presence of the associated injuries or residual instabilities. Mean follow-up was 28.8 months with a minimum 12 months. Results : Examination of 86 ACL ruptures revealed a Segond fracture in 4 patients (4.7%). They all occurred in male, and nearly all were caused by sports injury and, understandabley, the accident mechanism always included knee flexion and internal rotation of the tibia. Two patients who had an associated injuries with ACL tear were managed by arthroscopically-assisted reconstruction using autogenous central one-third of the patellar tendon, and the other two by lumpectomy only because of the partial tear of the anteromedial bundle of ACL. The clinical results at the final follow-up were satisfactory. Conclusion : Avulsion fracture of the lateral tibial condyle, known as a Segond fracture or a lateral capsular sign, are increasingly associated with anterior cruciate ligament (ACL) rupture. This is a boy avulsion of the meniscotibial ligament and almost always occurs during knee flexion and internal tibial rotation, and in most cases only after damage to the primary ACL stabilizer. Examination of 86 ACL ruptures revealed a Segond fracture in 4 patients (4.7%). Nearly all were caused by sports injury and, understandably, the accident mechanism always included knee flexion and internal rotation of the tibia. This phenomenon, which is easy to detect by radiograph, can thus be regarded as a strong indication of an ACL injury.

기관골 신생증 1예

오영상,이은우,정종혁,문승원,김수현,김동한,양혁승,박정환,박경옥,강성수,이영직 朝鮮大學校 附設 醫學硏究所 2006 The Medical Journal of Chosun University Vol.31 No.2

Tracheobronchopathia osteoplastica is a rare disorder of unknown cause characterized by the projection of numerous bony or cartilaginous submucosal nodules into the tracheobronchial lumen with sparing of the posterior membranous portion of tracheobronchial tree. In the past, most of the cases were diagnosed as secondary finding at autopsy. Nowaday, the key component of the evaluation is flexible fiberoptic laryngoscopy and bronchoscopy, which typically demonstrates irregular spicules of subrnucosal bone and cartilage projecting into the tracheobronchial lumen and causing various degrees of airway obstruction. A 45 years old man was visited Sunchon St. Carollo hospital due to discomfort on throat. We saw several nodules just below vocal cord via laryngoscope. The computed tomography revealed multiple small calcified nqdules on trachea and both main bronchi. Pathologic finding of bronchoscopic biopsy showed abnormal proliferation of bony and cartilagious nodules in the tracheal submucosa. These fingdings were consistent with tracheobronchopathia osteoplastica. We report here on a case of tracheobronchopathia osteoplastica with review of literature.

外食産業 特殊性에 대한 考察

吳政煥 경기대학교 호텔경영연구소 1994 호텔경영연구논총 Vol.- No.3

In the rationalization of restaurant management, it is important that manager of the restaurant should consider social attributes. That is, the managers are required to observe modern food service industry in the direction that producer and consumer can be considerated. The public will memorize and envy forever the dinning-out business of J.W. Marriott, Mcdonald of R. Kroc, Lotteria in Korea today. This means that the food service industry which must be operated rationally has been successful. A small and medium restaurant is the business that satisfies basic wants of the public. A large restaurant can be said to be a consumption businessis. But in the case of exporing Know-how and service, the business increases the acquisition of foreign exchange as well as foreigner's purchasing power which makes a great contribution to the improvement of international payments. To this end, managers are asked to operates the food service industry rationally. Accordingly, more government support will be needed, and the actives and affirmative attitudes of managers are also required. Finally, the purpose of this study is to suggest that the managers of restaurants should consider the characteristics of the food service industry so that they may make a great contribution to the successful development of restaurants as a whole.

이종마찰압접재의 변형 및 균열 성장 거동 : STS304 와 SM15C재를 중심으로 For STS304 and SM15C

오정국,오환섭,박준건 조선대학교 동력자원연구소 1997 動力資源硏究所誌 Vol.19 No.1

In this study, behavior of crack growth and fracture under static tensile load in friction welded dissimilar materials, and necking phenomenon occuring at tensile yeilding point is shown. Crack is observed in heat affected zone including fine ferrite region of SM15C and heat affected zone of STS304. Plastic flow was occured by friction welding process, so direction of crack is inclined with welded surface. Fracture behavior of similar material is subject to joint of void, but dissimilar material is liable to joint of micro crack. Fibrous zone with the view of macroscope and dimple pattern with the view of microscope is observed at fracture surface.

골화석증 1례 보고

오정환,이문구 건국대학교 의과학연구소 1994 건국의과학학술지 Vol.4 No.-

Osteopetrosis, also known as Albers-Schonberg disease, marble bone, osteosclerosis fragilis, or chalk bone, is a rare hereditary, congenital and familial disease, characterized by a marked increase in the radiodensity of the bone and by an abnormality in the shape of the long bone, especially the metaphysis. It may occur in autosomal recessive form with severe, generalized bone changes in the new born infant that result in early death or in a more benign autosomal dominant form with less extensive bone involvement and relatively good prognosis. We experienced a case of a benign autosomal dominant form of osteopetrosis incidentally and reporting this case with a review of the literatures.

이종접합재 접합 계면근방 균열의 응력 및 파괴특성

오정국,차용훈,오환섭,박준건,박경식 朝鮮大學校 機械技術硏究所 1998 機械技術硏究 Vol.1 No.1

현재까지 이종마찰압접재의 강도측정은 실험 (7)-(15)에 의해 구해져 왔다. 하지만 최근 이종마찰압접재의 효율성을 인정하여 여러 실용 부품에 응용하려는 연구가 한창 진행중이다. 이종마찰압접재에 대한 저자들(1)-(6)의 기초실험결과 일반적인 단종재와는 상이한 파괴거동(3)이 관찰되었고, 파괴역학적인 관점에서 정성적인 data 확보가 필요하게 되었다. 따라서 본 연구에서는 인장시험시 이종마찰압접재의 접합강도와 미소균열들에 의한 파괴거동을 파괴역학적 관점에서 해석적으로 고찰하여 보고자 경계요소법(BEM ; Boundary Element Method)을 이용하여 접합계면을 포함하는 접합부를 중심으로 계면상의 응력분포와 계면의 중앙에 결함이 균열로써 존재하는 경우의 응력분포와 인장시험시 열영향부에서 관찰된 균열의 모델링을 통한 균열선단에서의 응력해석을 행하였고, 그 결과 얻어진 중요한 내용을 요약하면 다음과 같다. 계면의 중앙에 균열이 존재하는 접합계면의 표면부에서 응력의 특이성이 발생하며 탄성계수의 비가 증가할수록 특이성이 증가함이 관찰되었다. 탄성계수의 비가 일정한 경우 균열의 크기가 변화하여도 계면의 표면부에서 발생하는 특이성은 거의 같은 값을 갖게 되며, 탄성계수의 비가 증가할수록 표면부의 응력 특이성의 크기는 증가한다. 이종마찰압접재의 인장시험시 관찰된 균열을 모델링 하여 해석한 결과 최대 응력 기준으로 살펴볼 때 인접한 균열선단에서의 응력분포는 균열을 합체시키는 방향으로 작용함을 알 수 있다. In this study stress distribution on the interface and stress near tip of the sub-interface crack in the dissimilar friction welded material is analyzed by using of BEM( Boundary Element Method). Stress singularity near surface of model to analyze is observed for various crack length and ratio of elastic modulus. Tensile and shear stress distribution near two neithbor sub-interface crack tips are analyzed. Existance of singularity near surface on the interface is particular situation so that we need to investigate for dissimilar friction welded materials by means of numerical analysis method.