재구성 가능형 공작기계의 주축 시스템 설계

장성현,정용민,황현영,최영휴,박종권 한국공작기계학회 2008 한국공작기계학회 춘계학술대회논문집 Vol.2008 No.-

During a decade, there are many researches on microfactory which is the miniature, flexible, and efficient manufacturing system for the micro/meso scale machining device. Moreover many micro machine tool has developed in Japan, U.S., Europe, and Korea. Already we developed a 3-axis micro milling machine with 300×200×320 ㎣ machine size for microfactory. In this study, we introduce the design of a high speed spindle system with air bearings for our micro milling machine. Desired operation speed range of the spindle system is 100,000 ~ 150,000 rpm. In. design step, we have consideration for minimum critical speed, compliance, and weight construction of the spindle system. The shaft length, the shaft outer diameter, bearing positions and bearing stiffness were set as the design values. After the final design of spindle model, we carried out dynamic analysis a spindle system for a micro milling machine by using ADROS, which is our own developed S/W for dynamic design analysis of rotor systems. As the result, we designed a spindle system having the critical speed above the operating speed.

다발성 연조직 종괴를 동반한 급성 림프구성 백혈병의 증례 보고

장정용,허경회,이원진,허민석,이삼선,최순철 대한구강악안면방사선학회 2005 Imaging Science in Dentistry Vol.35 No.2

A 15-year-old patient, who had been diagnosed and treated as Burkitt cell type acute lymphoblastic leukemia (ALLL3) already, visited our department. He complained of gingival enlargement and loosening teeth 1 month ago. The clinical examination revealed anterior open bite, gingival enlargement, and nontender swelling particularly in molar regions of both jaws. Deep periodontal pockets and severe mobility was shown on most of the teeth. The panoramic radiographs showed severe bone destruction and extrusion of the molars. The contrast enhanced CT showed multiple enhanced mass and bone marrow obliteration in both jaws. Chemotherapy was done and the swelling was subsided at 1 month later. In conclusion, radiologic findings of leukemia with soft tissue mass, known as chloroma or granulocytic sarcoma, mimic those of lymphoma, so blood test may be needed for the final diagnosis.

평면 2자유도 모델을 이용한 리니어 모터로 구동되는 다축 마이크로 밀링머신 크로스헤드의 진동해석

장성현,황현영,정용민,최영휴,홍정표 한국공작기계학회 2008 한국공작기계학회 추계학술대회논문집 Vol.2008 No.-

In this paper, a simple 2-D.O.F. planar motion model is proposed in order to analyze the snake motion of a cross head assembly of a Multi-axis micro milling machine (M4) for BT-factory, that is travelling on linear guide. In the proposed mathematical model, the friction between head and guide ways is neglected, and also the support structures including the linear guides of M4 are assumed to be rigid. The equations of motion of the proposed model are derived and successfully solved to determine vibration responses of a cross head assembly due to some applied traction forces.

다기능 5축 복합가공기 구조 최적설계 및 동강성 평가

정용민,장성현,황현영,최영휴,하종식 한국공작기계학회 2008 한국공작기계학회 추계학술대회논문집 Vol.2008 No.-

This paper describes a structural design. optimization for light weight and minimum compliance using G.A. and a study on dynamic stiffness evaluation of a 5-axes multi-tasking machine tool. Dynamic stiffness is one of important factors regarding to machine tool accuracy. In design optimization, we optimized the thickness of structural member which minimize the compliance and weight of the machine structure under several constraints. Furthermore, dynamic stiffness, in this study, were obtained by using both FEM analysis and an experimental dynamic stiffness test, that is a random excitation test by using a hydraulic exciter. Both the theoretical and experiment analysis results showed good agreement with each other. Finally, some discussion and review from the view point absolute dynamic stiffness were made based on the analysis results.

이산화된 탐색공간에서 다구찌 방법을 이용한 구조 최적설계에 관한 연구

장성현,정우영,정용민,권봉철,최영휴 한국공작기계학회 2008 한국공작기계학회 추계학술대회논문집 Vol.2008 No.-

Nowadays, there are several design problem having discrete variables in the industrial fields. The researchers are using the optimization method, such as genetic algorithm (GA), simulated annealing (SA), design of experiment (DOE) and taguchi method (TM), to solve it's design problem. Moreover, people want to decrease the computational cost and time. Therefore, in this paper, we proposed the iterative optimization algorithm which repetitively searched a local region to find best solution in discrete searching space using TM. The optimal solution in each local region is obtained by S/N ratio for the evaluation function that consists of the objective function and penalty function. Also, we have applied our algorithm to 3-bar, 10-bar, and 25-bar truss optimization problem.

수용성 절삭유제 내에서 Saccharomyces cerevisiae와 Escherichia coli의 성장에 관한 연구

정광진,최희영,김장규,원성호,김남기 成均館大學校 科學技術硏究所 1992 論文集 Vol.43 No.2

The water-soluble cutting oil was used in the type of the mixture of additive lubricant, surfactant, etc., as the organic nutrients, with water. Therefore it was easy to be affected by microbials ; they brought the bad odor by putridity, decreased the cutting property, and destroyed the emulsion phase. In the study using cells, Saccharomyces cerevisiae and Escherichia coli, we studied the effect of concentration and dilution ratio on the growth of cells and the cell growth rate, the pH variance and the change of oil's concentration. The results obtained in this experiment were as follows : 1) The result of test dilution ratio (water:oil) vs. cell growth was that by using E. coli, the growth was better in this order in emulsion type (sample 1) 50:1 > 30:1 > 100:1, and in the soluble type (sample 2) the order was 100:1 > 50:1 > 30:1. The effect of the cutting oil's concentration on the Saccaromyces cerevisiae's was less in this order 100:1 < 50:1 < 30:1 ; the maximum growth was occurred at 100:1. 2) In sample 1 by using E, coli, pH range was changed from 9.5 to 8.0 and refractive index(the cutting oil's concentration) was changed from 1.3327 to 1.3318. And in the test using S. cerevisiae, pH range was varied from 9.5 to 6.2 and refractive index was changed from 1.3330 to 1.3310. In sample 2 by using E. coil, pH was changed to 8.9 and refractive index was changed from 1. 3315 to 1.3313 and in that of using S cerevisiae, pH was changed to 8.1 and refractive index was decreased from 1.3355 to 1.3340.

partial pulpotomy를 이용한 미성숙 영구치의 치수 치료: 증례 보고

장기택,노승철,한세현,김정욱,김용수 大韓小兒齒科學會 1999 大韓小兒齒科學會誌 Vol.26 No.4

치수치료의 주요한 목적은 구강조직의 본래의 건강을 유지하는 것이며, 치수치료 시 가장 중요하고 어려운 점은 치수조직의 건강상태 또는 염증의 정도를 결정함으로써 최선의 치료방법을 결정하는 것이다. 미성숙 영구치는 풍부한 혈류 공급으로 다양한 손상에 성공적으로 반응하게끔 치수의 능력을 향상시킴으로써 많은 치수치료 술식을 위한 좋은 조건을 가지고 있다. 기저재(base) 또는 이장재(liner), 간접 치수복조술, 직접 치수복조술, 그리고 치경부 치수절단술을 포함한 여러 종류의 보존적인 치수치료가 미성숙 영구치를 위해 추천되어 왔다. 근래에는 외상으로 인하여 치수노출된 영구절치를 치료하는데 있어 주로 제시된 부분 치수절단술(partial pulpotomy)이 우식으로 인해 치수노출된 영구대구치를 치료하는 또다른 술식으로 제안되고 있다. 부분 치수절단술 후 치아가 다음의 criteria를 만족시킬 때 치유가 되었다고 결론지었다. 1. 임상적 무증상 2. dentin bridge 형성의 방사선학적 증거 3. 방사선상에 치수내 또는 치근단 병소가 없다는 증거 4. 지속적인 치근 발육과 미성숙 치아의 치근첨 형성 5. 성숙된 치아에서 정상적인 상아질의 축적 6. 전기치수검사에서 양성 반응 이에 저자는 미성숙 영구치에서 우식 또는 외상으로 인한 치수노출시 부분 치수절단술을 행하여 양호한 결과를 얻었기에 이를 보고하는 바이다. The primary objective of pulp treatment is to maintain the integrity and health of the oral tissues. The most important and difficult aspect of pulp therapy is determining the health of the pulp, or its stage of inflammation, so that a decision can be made regarding the best form of treatment. Immature permanent teeth are good candidates for many pulp healing procedures, due to their rich blood supply, which is believed to enhance the pulp's ability to react successfully to various insults. Healing was considered to have taken place when the tooth fulfilled the following criteria: 1. Abscence of clinical symtoms 2. Radiographic evidence of dentin bridge formation 3. No intrapulpal or periapical pathosis was evident radiographically 4. Continued root development and closure of the apex in immature teeth 5. Normal dentin apposition in mature teeth 6. Positive response to electrical pulp test This presents a report of cases in which immature permanent teeth, pulp-exposed by caries or trauma, was treated successfully by partial pulpotomy

Ni53-Fe47자성박막의 신형전류자기 기전력효과

정한,손희영,김미양,장현숙,이장로,이용호 숙명여자대학교 자연과학연구소 1994 자연과학논문집 Vol.- No.5

진공증착방법으로 제작한 Ni53-Fe47 박막에 관한 신형전류자기 기전력효과의, 전류와 자장 방향이 만드는 각θ의존성이, 자기저항효과의 cos 2θ, Hall 1효과의 경우 sin θ임에 대하여 sin 2θ로 관측되고, 이 효과의 자장에 의존하는 전압변화율이 자기저항효과와 비교할 때 차수가 다르게 큰 것이 조사된다. 이 효과가 2 Carrier형 모델로 이해 할 수 있음을 이론적으로 확인된다. A new Galvanomagnetic electromotive force effect of Ni53-Fe47 thin films is studied. The dependence of this effect on θ, angle between the current and the magnetic field, is found to be the form of sin 2θ, in contrast with that of the magnetoresistance effect cos2θand that of the Hall effect sinθ. Property of this effect is that 1the rate of the voltage variation depending on the magnetic field is extremely large as compared with the magnetiresistance effect. It is theoretically confirmed that this effect is well understood on the basis of the two carrier types model.

콩 단백질/펙틴/몬모릴로나이트 나노복합 필름의 특성 및 산소 투과도 연구

정세환,김성철,조규순,신용섭,장상희,홍기헌,이태진,신부영 嶺南大學校 工業技術硏究所 2004 工業技術硏究所論文集 Vol.32 No.2

In this study, Mechanical property, thermal property, watervapor, and oxygen permeability of biodegradable Soy protein/Pectin-montmorillonite nanocomposite, prepared with Na^(+)-MMT, have been studied. X-ray diffraction and TEM experiments an polymer/silicate composite samples demonstrated that the intercalation of polymer chains leads to increase in the spacing between silicate layers. In addition, it were found that the intercalated Soy protein/Pectin/montmorillonite nanocomposite were prepared. It was found that the addition of only a small of clay was enough to improve the thermal stability and mechanical property of Soy protein/Pectin/montmorillonite nanocomposite. watervapor of Soy protein/Pectin/montmorillonite nanocomposite was generally lower than that of Soy protein/Pectin. oxygen permeability of Soy protein/Pectin/montmorillonite nanocomposite was generally lower than that of Soy protein/Pectin.

위의 유암종과 선종의 병발 1례

장재식,강혁주,이중현,서영범,윤병구,김용섭,이구,서정일,양창헌,이창우,김정란,윤환중 東國大學校醫學硏究所 2000 東國醫學 Vol.7 No.-

유암종은 전신에 퍼져 잇는 장크롬친화성 세포에서 기원하는데 위의 유암종은 비교적 드문 질환으로 모든 유암종의 1.9~2.2%에 해당하며 위에 발생하는 종양의 1% 미만에서 보고되고 있다. 유암종은 일반적으로 증상이 비특이적이고 면역조직화학검사에 의해서 진단되기 때문에 과거에는 드물게 발견되었으나 최근 내시경 기기 및 술기의 발전과 검사 빈도의 증가 및 면역조직화학검사의 발달로 진단율이 증가 추세에 있으며, 드물지만 유암종에서 선암과 공존하는 예들이 보고되고 있다. 저자들은 심와부 동통을 주소로 내원한 70세 남자 환자의 상부위장관내시경 검사에서 위체상부의 대만곡에서 0.4×0.4 cm 크기의 중간 함몰을 가진 Yamada 1형의 용종과 함께 전정부의 전벽에서 0.8×0.5 cm 크기의 융기된 점막 소견을 보여 조직학적으로 각각 위유암종 및 위선종임을 확진한 후 내시경적 용종 절제술로 치료한 1예를 경험하였기에 문헌고찰과 함께 보고하는 바이다. Carcinoid tumors are arisen from enterochromaffin cells, which are scattered throughout the body. These tumors are composed of variable numbers of cells that contain endocrine granules in their cytoplasm, which can be identified by immunohistochemistry and electron microscopy. Gastric carcinoid tumors are relatively rare tumor, the reported incidence being 1.9~2.2% of all carcinoid tumors and less than 1% of all gastric tumors. Sometimes, composite carcinoid tumors and adenocarcinoma is reported. We experienced a case of the coincidence of carcinoid tumor and adenoma at the other site of the stomach in a 70 year old male patient. Gastrofiberscope showed 0.4×0.4 cm sized Yamada type I polyp with central depression on the greater curvature of the proximal body and 0.8×0.5 cm sized focal slightly elevated mucosa on the anterior wall of the antrum. The endoscopic biopsy specimens revealed carcinoid tumor and tubular adenoma with moderate atypism, respectively. The carcinoid tumor and adenoma were removed by endoscopic polypectomy. According to the follow-up gastrofiberoscopy after 7 month later, both lesions were nearly normal mucosa except whitish atrophic change after polypectomy.