CW Nd:YAG레이저를 이용한 금형 재료의 표면열처리

유영태,신호준,장우양 한국공작기계학회 2004 한국생산제조학회지 Vol.13 No.5

Laser heat treatment is an effective technique used to improve the tribological properties and also to increase the service life of automobile components such as camshafts, crankshatfs, lorry brake drums and gears. High power CO₂ lasers and Nd:YAG lasers are employed for localized hardening of materials and hence are of potential application in the automobile industries. The heat is conducted rapidly into the bulk of the specimen causing self-quenching action to occur and the formation of matrensitic structure. In this investigation, the microstructrual features occurring in Nd:YAG laser hardening SM45C and STD_(11) steel are discussed with the use of optical microscopic and scanning electron microscopic analysis. Moreover, This paper describes the optimisation of the processing parameters for maximum hardened depth of SM45C and STD_(11) steel specimens of 10mm thickness by using CW:YAG laser.

최근 8년간 K지방대학병원 응급실로 내원한 치과 응급환자에 관한 임상적 연구

유재하,김종배,김태우,문선재,권혁찬,김승범 大韓顎顔面成形再建外科學會 2001 Maxillofacial Plastic Reconstructive Surgery Vol.23 No.6

The delivery of the proper care to the emergency dental patients is more important in the aspdect of community dental service. To attain such a purpose requires the sacred duty to the training of oral and maxillofacial surgeons. This is a retrospective study on the characteristics of dental injuries and diseases in emergency patients. Ths study was based on a series of 2,649 patients treated as dental emergency patients at K country hospital of medical college, from Jan. 1, 1993, to Dec. 31, 2000. The obtained results were as follows. The trauma(71.6%) was the most frequent cause in dental emergency patients, odontogenic infection and oral hemorrhage were next in order of frequency. The primary interdental wiring and transpalatal wiring were frequent proper methods with rubber drainage for prevention of hemorrhage and infection in the primary care of jaw fracture. The peak incidence(45.0%) about the infection group was occurred in the pulpitis of advanced dental caries, and common treatments were the medication of antibiotics & anagesics and I&D. In the dentoalveolar hemorrhage group, a major cause was postoperative hemorrhage(57.9%) and hemostasis was obtained by pressure dressing, suture and drainage of infected wound. About TMJ disorder group, the peak incidence was showed in the post-traumatic myofascial pain dysfunction syndrome and its primary care was medications(anagesics & sedatives). In the other groups, various irritable specific pains were complained, such as trigeminal neuralgia-form pain, acute stomatitis, chemical burn, terminal stage neuritis of head & nech cancer and their primary care methods were various individually. For the rapid and correct care of the emergency dental disease above, well-trained education should be presented in the intern and resident curriculum of oral & maxillofacial surgery.

Trametes versicolor에 의한 상수리나무의 분해형태

유태방,윤민호,최우영,이종신 충남대학교 농업과학연구소 2001 농업과학연구 Vol.28 No.2

백색부후균 Trametes versicolor(CV5) 균주에 의한 wood lignin의 분해능을 조사하였다. CV5는 활엽수와 침엽수에 속하는 여러 수종의 프로토 리그닌 분해 시 활엽수에 한해서 분해되는 특성을 보였으며, 특히 상수리나무에서 33.5%의 가장 높은 리그닌이 분해되었다. 리그닌 분해에 관련된 phenoloxidase 분비능을 Bavendamm 시험을 통해 검토한 결과 CV5는 지금까지 연구된 우수 백색 부후균과 같은 유사 반응 형태를 나타내고 있음을 확인하였다. 또한 상수리 목재 chip표면에 CV5의 균사가 생육하면서 목재조직이 부후된 상태를 주사전자 현미경으로 관찰한 결과 목섬유 및 도관에서 균사의 침투와 목재조직의 분해를 확인하고 리그닌에 대한 높은 선택적 분해력을 갖고 있음을 구명하였다. Trametes versicolor(CV5) selected as a white-rot fungus with strong lignin degrading activity, in the previous paper, was investigated on a properties of degradation of wood lignin. Lignins of hardwoods, especially oak(Querous acutissima carruth) an paulownia (Paulownia coreana Uyeki) were considerably delignified by the CV5, however, softwoods used in this experiment were not delignified. Bavendamm's reaction was positive with several phenols on agar plates for the confirmation of a phenoloxidase secreted Through the morphologies of decayed wood chip observed with the aid of scanning electron microscopy, it was found that the hypha of CV5 penetrated the ray cells and vessels caused separation of the wood cellulose.

卵巢未分化胚細胞腫 1例

柳友國,李起煥,權善鎬,盧興泰 충남대학교 의과대학 지역사회의학연구소 1985 충남의대잡지 Vol.12 No.1

Ovarian Dysgerminoma is a tumor purely of germ cells without any attempt to form teratomatous elements and is believed to arise from the primordial germ cells of the indifferent stage of gonadogenesis. We have had a Dysgerminoma of right ovary in 28 years old multigravida and report the case with review of literatures briefly.

초등학교 자연과 교사용지도서 활용에 관한 분석

유병길,이태우 부산교육대학교 과학교육연구소 1999 科學敎育硏究 Vol.24 No.-

There is a gap between intended-curriculum and executed-curriculum. Teachers have many problems in practice when teachers execute intended-curriculum. In light of this, teacher's guide has very important roles in that teachers depend on teacher's guide when they teaches their learners. In this paper, we analyze problems with teacher's guide when they use it, and suggest some improvements.

UASB에 의한 有機性 廢水處理의 溫度影響에 관한 硏究

姜龍太,崔廷宇,全裕燦 東亞大學校 海洋資源硏究所 1991 硏究論文集 Vol.4 No.1

The purpose of this research was to investigate the effects of temperatures on the wastewater treatment. The experimental results used synthetic wastewater showed that removal efficiency of UASB ranged from 83 to 93 percents within a temperature ranges of 20 to 35℃, which indicated that the removal rates decreased approximately 2 or 3 percent as the temperatures reduced at intervals of 5℃. The production of waste sludge was a little, on the other hand, the treatment efficiency of it was very high. Obtained from this experimentation the values of temperature characteristic term(θ), Q?? and activated energy(E??) were 1.053, 1.69 and 9349cal/mole, respectively. We could find out the size and concentration of granular sludge decreased in proportion to the reduction of temperature, and a filamentous bacteria of Methanothrix spp. was prevailed more than a bacteria of other species in the granules.

석이로부터 분리한 페놀성 화합물의 phospholipase A_2 저해활성

김진우,송경식,유익동,장현욱,유승현,배강규,민태진 충남대학교 생물공학연구소 1997 생물공학연구지 Vol.5 No.-

호알카리성 진균 Cephalosporium sp. RYM-202가 생산하는 alkaline xylanase (CX-III)의 작용에 의해 xylan 기질로부터 생성되는 주요 가수분해 산물은 xylobiose와 중합도가 4 이상인 xylooligosaccharides이었다. 이 효소는 xylobiose에 대한 분해능을 가지고 있지 않지만 xylotriose로부터는 xylobiose를, xylotetraose로부터는 xylobiose와 xylotriose를 주산물로 형성하였다. 이러한 결과들은 CX-III가 transglycosidase 활성을 소유하는 전형적인 endo-type xylanase임을 보여준다. N-bromosuccinimide에 의한 CX-III의 화학적 변화 실험 결과 효소 1분자 당 2개의 tryptophan 잔기가 활성에 관여하는 것으로 나타났다. 그러나 iodoacetamide 및 diethylpyrocarbonate에 의한 효소활성의 저해효과는 나타나지 않음으로써 이 효소의 활성부위에 cysteine과 histidine 잔기가 필수적이지 않음이 확인되었다. The hydrolysis products formed from birchwood xylan by the action of an alkaline xylanase (CX-III) from alkalophilic Cephalosporium sp. RYM-202 were xylobiose and xylooligosaccharides polymerized with more than 4 sugar molecules. This enzyme was not active on xylobiose but readily attacked xylotriose accumulating xylobiose as a major product. The predominant end-products from xylotetraose by CX-III were xylobiose and xylotriose. These results indicate that the enzyme is typically endo-type xylanase possessing transglycosidase activity. Chemaical modification of CX-III with N-bromosuccinimide revealed that two tryptophan residues per molecule of CX-III were essential for its catalytic activity on xylan. On the other hand, iodoacetamide and diethylpyrocarbonate did not influence the activity of the enzyme, suggesting that cysteine and histidine residues are not involved in the active site of this alkaline xylanase.

코일형 곡관에서 층류맥동유동의 압력분포

박우룡,모양우,최주호,유영태 順天大學校 1992 論文集 Vol.11 No.1

The characteristic of the pressure distributions are studied theoretically and experimentally for the laminar steady flow and the laminar pulsating flow generated by the butterfly valve in the coiled pipes with the curvature ratios of 7 and 30. The pressure gredient ratios affact with Wormersley numbers, Dean numbers, velocity amplitude ratios and time averaged Reynolds numbers. The pressure gredient ratios of oscillatory components increase according to increasing the Wormersley number and the velocity amplitude ratio.

주물공장 근로자에서 발생한 국한성 석면폐증 1예

김태우,고동희,김민기,유승원,류향우,한정희,정순희 大韓産業醫學會 2009 대한직업환경의학회지 Vol.21 No.2

배경: 주물공장 근로자에서 발생한 석면폐증의 작업 관련성을 평가하고 그 증례를 보고하고자 한다. 증례: 30년간 주물공장에서 근무한 환자로 인후통, 기침, 노란 가래가 있어 검사한 결과 결핵이 의심되어 치료 하였으며, 치료 중 석면폐증으로 진단되었다. 작업 관련성 평가를 위해 실시한 폐 조직의 조직학적 검사에서 1 cm^(2)당 3개의 석면소체가 발견되었고, 투과전자현미경으로 분석한 석면 함유량은 23.26x10^(6) fibers/g이었다. 결론: 작업환경조사, 폐 조직의 석면 분석 등을 통해 작업 관련성이 높다고 판단하였다. Background: Foundry workers are known to be exposed to silica and have an increased risk of Silicosis. There are also reports that state these foundry workers were associated with asbestos-related change in the X-ray results of the lungs. This report discusses a case of localized asbestosis developed in a foundry worker who worked in 12 Korean foundries. Case report: A 49-year-o1d man who worked at molding and melting for 30 years, Presented with sore throat, cough and yellow sputum for 1 month. From physical and clinical examination, Pulmonary tuberculosis was highly suspicious; therefore, he was medicated for 6 months. After tuberculosis medication, the radiological finding was reactivation of tuberculosis, and an asbestos body was detected at a trans-bronchial lung biopsy. During an operation, operators found multiple palpable masses and bullae 10calized in the right upper lobe (RUL) and performed right upper lobectomy and right middle lobe wedge resection. Using hematoxylin-eosin stain and iron stain, we could detect asbestos bodies by light microscopy. We analyzed the asbestos fiber burden in dry lung tissue by transmission electron microscopy with energy dispersive X-ray spectrometer (TEM-EDX). The fiber type was chrysotile and the fiber burden was 23.26 x 10^(6) fiber/g dry lung. Discussion: This case study of a foundry worker with localized asbestosis is uncommon in Korea. We found an occupational relationship between the foundry worker and localized asbestosis through various investigative techniques such as measurements taken at his working environment, clinical, radiological and pathological examination of the foundry worker and mineralogical examination of the asbestos fiber.

비혈연간 동종조혈모세포이식의 단일기관성적 : Single Center Experience

김유진,김동욱,이석,이동건,박윤희,김희제,김태규,민우성,김춘추 대한조혈모세포이식학회 2003 대한조혈모세포이식학회지 Vol.8 No.2

연구배경: 비혈연간 조혈모세포이식은 HLA체계에 대한 이해의 증진과 새로운 검사법의 개발, 그리고 기증자 수의 증가에 힘입어 최근 빠르게 증가하고 있다. 방법: 가톨릭조혈모세포이식센터에서 1995년 10월부터 2001년 12월까지 비혈연간 이식을 받은 138명의 성인 환자를 대상으로 후향적 분석을 하였다. 결과: 질환별로 만성골수성백혈병 66예, 급성림프구성백혈병 23예, 급성골수성백혈병 16예, 재생불량성빈혈 21예, 골수이형성증후군 9예, 비호지킨림프종 2예, 그리고 발작성야간혈색소뇨증이 1예였다. 일차 생차부전은 분석가능한 136예 중 4예(2.9%)에서 발생하였다. Ⅱ도 이상의 급성이식편대숙주병의 발생률은 48.1%였고, 만성이식편대숙주병은 49.5%였다. 재발 이외의 사망원인 중 가장 높은 빈도를 보인 것은 폐렴으로, 독성사망 64예 중 36예(52.3%)에서 관찰 되었다. 만성골수성백혈병의 경우(n=66), 무병생존율, 재발률, 비재발성 사망률이 각각 45.7%, 11.4%, 49.2%였다. 무병생존율은 표준위험군이 고위험군에 비해 통계적으로 유의하게 높았다(50.3% vs 32.0%, p=0.03). 급성림프구성백혈병의 경우(n=23), 무병생존율, 재발률, 비재발성 사망률이 각각 30.0%와 49.4%, 44.8%였던 반면, 급성골수성백혈병에서는(n=16) 28.6%, 39.4%, 52.9%였다. 이들 급성백혈병에서는 표준위험군에 비해 고위험군에서 재발률과 비재발성 사망이 모두 높게 관찰되었다. 중증재생불량성빈혈의 경우(n=21), 무병생존율과 비재발성 사망이 37.3%와 62.7%였다. 결론: 본 연구의 결과 비혈연간 이식은 HLA적합 형제가 없는 혈액질환 환자들에게 유용한 치료법의 하나임을 알 수 있었다. 낮은 병기에서의 조기 이식과 분자생물학적 방법을 사용한 HLA 적합도의 개선이 이식관련 사망을 최소화시켜 비혈연간 이식의 효과를 더욱 확대시킬 수 있을 것으로 생각된다. Background: Unrelated allogeneic stem cell transplantation (U-SCT) is recently on a increasing trend supported by better understanding of HLA system, development of new HLA typing, and increase of donor pool. Methods: We retrospectively analyzed 138 adult patients who underwent U-SCT between October 1995 and December 2001 at Catholic Hematopoietic Stem Cell Transplantation Center. Results: Diagnoses were chronic myeloid leukemia (CML, n=66), acute lymphoblastic leukemia (ALL, n=23), acute myeloid leukemia (AML, n=16), severe aplastic anemia (SAA, n=21), myelodysplastic syndrome (MDS, n=9), non-Hodgkin lymphoma (NHL, n=2), and paroxysmal nocturnal hemoglobinuria (PNH, n=1). Primary engraftment failure was observed in 4 (2.9%) of 136 evaluable patients. Acute GVHD (≥grade II) occurred in 48.1% and chronic GVHD occurred in 49.5%. The most common cause of death other than relapse was pneumonia, which occurred 36 (52.3%) of 64 toxic deaths. In CML, disease-free survival (DFS), relapse rate, and non-relapse mortality (NRM) was 45.7%, 11.4%, and 49.2%. DFS of the standard-risk group (SR) was significantly better than that of high- risk group (HR) (50.3% vs 32.0%, P=0.03). In ALL, DFS, relapse rate, and NRM was 30.0%, 49.4%, and 44.8%, whereas corresponding figures for AML were 28.6%, 39.4%, and 52.9%. NRM and relapse rate were higher in HR compared to SR in acute leukemia. In SAA, DFS and NRM was 37.3% and 62.7%. Conclusion: We concluded that U-SCT is a feasible therapeutic option for patients lacking a HLA-matched sibling donor. Transplantation at earlier phase of disease with more accurate HLA matching by molecular typing can minimize treatment-related toxicity and could extend the benefit of U-SCT.