FEM을 이용한 선삭가공 절삭조건의 영향 분석

임세환,송춘삼,홍석관,강정진,김주현 한국공작기계학회 2007 한국공작기계학회 추계학술대회논문집 Vol.2007 No.-

A plane strain finite element model is developed to simulate turning with continuous chip formation using adaptive remeshing during the thermal-mechanical coupled analysis. Comparisons between the experimental and simulation results for cutting forces are performed to validate FE analysis results. Influences of machining parameters such as depth of cut, cutting speed and feed rate on cuting force and shear angle are analyzed by Taguchi method. The more depth of cut and feed rate result in the increase of cutting forces, but the rates of increase are decrease due to the larger shear angle. As the cutting speed increases, von Mises stress of workpiece near the tool tip decreases because the strength of specimen decreases at high temperature above 500℃. This thermal effect on cutting force is negligible because the affected area is very localized and the average values of von Mises stress in the shear plane are the same among the diverse cutting parameters.

국소성 분절성 사구체 경화증의 완전 관해 후 발병한 IgA 신병증 1예

임현민,김현정,박민석,주혜원,최원,김상현,박원도 인제대학교 2006 仁濟醫學 Vol.27 No.-

We report a rare case of primary glomerular disease with IgA nephropathy in a 43-year old man. 7-years ago, he was diagnosed with minimal change nephrotic syndrome. After treatment with steroid for 1-year, azotemia and proteinuria were improved. But, nephrotic range proteinuria was relapsed within 1 week after cessation of steroid. Renal biopsy revealed focal segmental glomerulosclerosis, and achived a complete remission with the use of steroids and cyclophosphamide. Then, he was followed up with normal renal function for 4-years. On admission, the patient showed generalized edema and marked proteinuria. In 3rd renal biopsy, mesangial proliferative glomerulonephritis with diffuse global sclerosis was observed. Electron microscopy showed electron-dense deposit on the mesangium with slight mesangial proliferation, and immunofluoroscence microscopy showed granular deposits of IgA and IgM. These features were consistent with IgA nephropathy, different from results of previous biopsies. The pathogenesis of IgA nephropathy occurred with primary FSGS is not clear, as well as treatment. Now, proteinuria is improving, steroid and cyclophosphamide are probably useful for the disease.

역기능 완벽주의 : 인지세트, 대처방식 및 심리적 부적응과의 관계 Relation to cognitive set, coping and psychological maladjustment

임주현,정남운 가톨릭대학교 사회과학연구소 2003 社會科學硏究 Vol.19 No.-

본 연구는 역기능 완벽주의와 심리적 부적응 사이의 매개변인들의 효과를 경로분석을 통하여 모델 검증하였다. 여기서 매개변인은 사회적 지지 지각과 자기지각으로 이루어진 인지세트와 대처방식으로, Lazarus와 Folkman(1984)이 제안한 적응에 대한 스트레스와 대처 모델(stress and coping model of adjustment)에 근거하여 설정되었다. 기본 경로모델 중 부합도가 충분하지 않은 모형을 단계적으로 수정하여 최종모델을 채택하는 과정을 거쳤다. 그 결과 각각의 수정된 경로모델에서 사회적 지지 지각과 대처방식은 매개변인의 효과를 나타냈으나, 자기 지각은 사회지지 지각과만 유의미한 관계를 나타냈고 매개효과는 나타내지 않았다. 역기능 완벽주의와 우울 모델, 역기능 완벽주의와 불안 모델에서는 한 가지 직접경로와 두 가지 간접경로를 볼 수 있었고, 역기능 완벽주의와 강박 모델에서는 직접경로와 간접경로가 각각 한 가지씩 나타났다. 마지막으로 본 연구가 지니는 의의와 제한점, 그리고 추후 연구를 위한 제안 사항들을 기술하였다. This study was to investigate the effect of mediation variables between perfectionism and psychological maladjustments by verifing path model. Mediation variables are cognitive set including social support perception, self perception and coping strategy based on the Stress and Coping Model of Adjustment by Lazarus and Folkman(1984). The final model was modified repeatedly when fit indexes of base path model were not enough to explain data. The result showed that modification path models were selected about depression, anxiety, obsession-compulsion. As a result, social support perception and coping strategy had an effect on mediation variable. Self perception was related with only social support perception and didn't have an effect on mediation variables. Specifically first, There were one direct path and two indirect paths between perfectionism and depression of psychological maladjustments. Second, There were one direct path and two indirect paths like depression model between perfectionism and anxiety of psychological maladjustments. Third, There were one direct path and indirect path. At the end of this, implications, the limitations of this study and suggestions for future were discussed.

북미자유무역협정의 정치경제학: 그 성격과 성과를 중심으로

임현진,이성형,송주명 서울대학교 국제지역원 1996 국제지역연구 Vol.5 No.2

이 글은 1994년도에 출범한 북미자유무역협정의 역사적 배경에서 출발하여 협정에 이르기까지의 각국의 협상 목표와 전략, 그리고 세계경제 전반에 미치는 영향과 협정의 주요 내용, 마지막으로 지난 3년간의 공과를 간단히 검토하고 있다. 세계적 차원에서 경제적 경쟁이 심화되면서 북미 3국은 기존의 상호의존성을 토대로 자유무역지대를 창출하는데 성공하지만 각국의 목표는 조금씩 다르다. 미국은 상대적으로 경제적 이익보다는 멕시코의 안정이라는 정치적인 목료를 고려하였고, 멕시코는 발전모델의 변경에 소요되는 재워조달이라는 경제적 이유가 가장 고려되었으며, 캐나다는 반면에 불참의 불이익을 회피하기 위해 북미자유무역협정에 가입하였다. 3년간 실험 끝에 역내의 무역창출 효과는 상당히 제고되었고 산업내 무역도 활발하게 전개되고 있지만 무역분쟁은 아짇고 크게 줄지 않고 있다. 초기의 낙관론과 달리 북미자유무역협정이 미주자유무역지대로 발전할 가능성은 상당히 약하다. This study examines the historical background of the NAFTA of 1994, negotiation targets and strategies of each country involved, its impact on the world economy as a whole, and its successes and failures over the past three years. While the three North American countries succeeded in establishing a free trade area based on reciprocity in the context of deepening economic competition in the world economy, the objectives of each country in this process slightly differ each other: The United States places more emphasis on a political objective-the stabilization of Mexico; Mexico is more interested in obtaining financial resources for remolding the existing economic development model; and Canada tried to avoid the possible economic disadvantages due to the boycott. After the three year economic experiment, the effect of trade creation within the trade area and intra-industry trade have been enhanced, whereas the trade disputes among the members still remain high. But the possibility of developing the NAFTA into the AFTA seems to be modest at the moment.

대학생을 위한 리더십향상 집단상담 구안 및 효과 연구

박현주,김민정,임진,엄혜련 西江大學校 學生生活相談硏究所 2005 人間理解 Vol.26 No.-

현대사회에서의 리더십은 크게 셀프리더십, 팔로워십, 능력부여리더십, 서번트리더십으로 분류될 수 있다. 한국의 대학생은 향후 인생의 목표를 설정하고 계획하여 추진하고 더불어 공동체의 일원으로 서로 교류하고 성장 한다는 발달적 과제를 가지고 있다. 따라서 대학생의 리더십은 셀프리더십을 바탕으로 한 자기관리, 대인관계 관리, 공동체 참여로 구성된다. 본 연구에서는 대학생의 리더십을 향상시키기 위한 집단상담을 구안하였으며 구조화된 대학생 리더십향상 집단상담을 2005년 1월에 실시하였다. 참여한 총 10명의 집단원들을 대상으로 집단상담 전 후에 각 구성요소를 측정하는 설문조사를 실시하였으며, 통계적으로 유의미한 차이는 아니었으나 자기관리, 대인관계관리, 공동체참여 각 영역 모두에서 향상된 양상을 보였다. 또한 집단원들의 회기별 피드백을 토대로 본 프로그램의 효과를 검증하였으며 본 프로그램의 보다 효과적인 적용을 위한 논의를 덧붙였다. Leadership, nowadays, can be classified into four different kinds: self-leadership, followership, empowering-leadership, and servant leadership. Korean university students have developmental tasks as members of group such as setting a life goal, making a plan, making an action, associating with others, and being advanced. Therefore, the elements of leadership program for university students based on self-leadership are self management, interpersonal relationship management, and participating in a group. In this study, a structured program for developing leadership of university students was designed, and operated on Jan, 2005. Surveys which measured each elements of the program were given to ten students who were participated in a group before and after the program. A statistical result was not significant. However, each elements, self management, interpersonal relationship management, and participating in a group, showed a progress. Session reviews by students were also used to verify the effect of the program. Further suggestions and studies for more effective application of the program were discussed.

인공 석회화 기질의 개발 및 파골세포에 의한 기질흡수에 관한 연구

김현만,박주철,임도선,박수진,김윤지,고재승 대한구강해부학회 1997 대한구강해부학회지 Vol.21 No.1

To develop artificial matrix resorbable by osteoclasts can be used as a model system that biological function of osteoclasts would be assayed in vitro in a standardized condition instead of using heterogenous bone or dentin slices. The present study developed artificial substrates consisted of apatite crystals. collagen gen. agar, apatite crystals under collagen film, mixture of apatite crystals and collagen, and mixture of agar and apatite crystals. And osteoclastic attachement and resorption activity on the each substrate was assayed in vitro. Osteoclasts attached to apatite crystals, collagen, mixture of apatite crystals and collagen, and mixture of apatite crystals and agar, however, not to agar. This suggested that apatite crystals and collagen should be exposed on the surface of artificial substrate where osteoclasts can attach. Osteoclasts attached to the substrate resorbed the substrate consisted of apatite crystals, mixture of apatite crysals and collagen, and apatite crystals under thin film of collagen, however, not of collagen, mixture of apatite crystals and agar. This suggested that the first phase of osteoclasts in resorbing matrix is to secrete acid and the end result of this phase, whatever it may be, may activate secretion of hydrolytic enzymes specific to organic components.

저칼슘식이로 사육한 생쥐의 골수세포 배양에 의한 파골세포양세포의 형성

박주철,강선주,임도선,김현만,고재승 대한구강해부학회 1995 대한구강해부학회지 Vol.19 No.1

Although it is now well established that osteoclasts are derived from mononuclear hematopoietic stem cells, most likely within the granulocyte-macrophage lineage, the exact differentiation process of osteoclast precusors has only been partially discovered. This study was carried out to investigate the following topics by examining the osteoclast-like cell formation from the calcium-deficient mouse bone marrow cells; 1) the effect of calcium deficiency on the formation of the mononuclear phagocytes and the mononuclear precusors of the osteoclast in the mouse bone marrow; 2) the effect of TNF (tumor necrosis factor)-α on the differentiation of osteoclast-like cells from the calcium-deficient mouse bone marrow culture; 3) the formation of the osteoclast-like cell from the calcium-deficient mouse bone marrow mononuclear cells and the relationship between the osteoblast cell line(MC3T3E1) and osteoclast-like cell formation; 4) formation of the osteoclast-like cells from the mononuclear cells which were col1ected from PTH-pretreated mouse bone marrow cells to investigate the relationship between PTH and calcium deficiency in osteoclast-like cell formation. Bone marrow cells were isolated from marrow of mouse feeding normal diet or calcium deficient diet for 7 and 14 days. Bone marrow mononuclear cells were fractionated by cetrifugation on Hypaque-Ficoli density gradients. PTH-pretreated mouse bone marrow mononuclear cells were obtained by collecting the nonadherent cells after the culture of normal mouse marrow cells with PTH for 6 days. The prepared cells were cultured on dentin disc at the concentration of 1.5-2 X 10^(6) cells per 0.5ml of a-MEM containing 10% FCS for 3, 5 and 7 days. Thereafter, TRAP staining, NSE staining, effect of calcitonin on the osteoclast-like cell and scanning electron microscope analysis of resorption lacunae on the dentin disc were performed. The results were as follows; 1. Number of the osteoclast precusors and mononuclear phagocytes in bone marrow was increased by calcium-deficient diet. 2. More osteoclast-like cells were formed from the calcium-deficient mouse bone marrow cells than from normal cells. 3. Formation of osteoclast-like cells was significantly stimulated by TNF-α in normal mouse bone marrow cells and calcium-deficient mouse bone marrow cells at concentration of l0ng/ml and 100ng/ml. 4. Osteoblast cell line(MC3T3E1) did not play an important role in osteoclast-like cell formation. 5. Formation of the osteoclast-like cells from the mononuclear cells which were collected from PTH-pretreated mouse bone marrow cells was similar to that of calcium-deficient mouse bone marrow mononuclear cells, which suggests that the effect of calcium deficiency in osteoclast formation may be mediated by PTH.

GT rotary file을 이용한 만곡 근관형성시 작업 효율 및 file 변형 발생에 관한 연구

신주희,백승호,배광식,임성삼,윤수한,김병현 대한치과보존학회 2001 Restorative Dentistry & Endodontics Vol.26 No.5

Root canal preparation process is of utmost importance in successful treatment of root canal. Also, one of the most important purpose of the root canal preparation is to enlarge the root canal three dimensionally without changing the curvature of the root canal. However, as the curvature of the root canal increases, there are many difficulties involved in formation of optimum root canal. Therefore, in order to solve the above mentioned problems, new developments in methods of root canal preparation and equipments for such purposes were made. Recently, vigorous studies about newly introduced engine-driven nitckel-ti-tanium rotary file are conducted. As shown in research results to dates, it is well established that the use of nickel-titanium file is better suited for curved root canal than stainless steel file in maintaining the curvature of root canal and reducing the deformation of root canal. However, it is also acknowledged that there are a few discrepancies in research results according to protocol, due to failure to remove variables in experiments. In addition, although it is recommended by the manufacturer that the GT rotary file should maintain a low rotational speed of 150∼350rpm and 'light pressure' as light as not to break the lead of a pencil, academic studies about the vertical force which is not yet standardized are not sufficiently explored. Therefore, this research devised and utilized a special research equipment to standardize the appropriate range of vertical force for GT rotary file through experiments by breaking of the lead of a pencil as expressed by the manufacturer and to accurately measure factors involved through repeating and recreating the environment of root canal preparation. Forming nine experimental groups by varying the vertical forces (150g, 220g, 300g) and rpm (150rpm, 250rpm, 350rpm), the effects of changing vertical forces and rpm on working efficiency were measured in terms of time expended in root canal preparation by crown-down method using a transparent resin block with 35 degree curvature and GT rotary file (z-test). The following research using this special research equipment that involved nine experimental groups and varying the vertical force for root canal preparation from 300g which is within the normal vertical force range to 700g and 1000g which fall outside the normal rpm range. The results were as follows : 1.Analysis of the experiment results revealed that the tome spent in root canal preparation decreased as the vertical forces and rpm increased (p<0.05). Also, the effects of rpm were greater than those of the vertical forces within the normal vertical force range (β-weight test) . 2.Observation of the deformation of GT rotary file revealed that deformation increases in a direct correlation with the vertical force increase and in a reverse correlation with the rpm decrease, In the case of the vertical forces close to the normal range, the probability of GT rotary file deformation were quite different depending on the rpm changes. In the case of◎eater tier◎cal forces, the occurrences of deformation of the file were more frequent regardless of the rpm changes. 3.Deformation and breakage of file were also commonly observed in the expended time measurement experiments and GT rotary file deformation experiments in which low speed rpm (150rpm) was used and at the curved portion of the resin block. Key words : GT rotary file, Crown-down method, Working efficiency, Vertical force, Rpm, Deformation and breakage of file

상악 절치부-토크에 의한 치아 이동과 응력 분포에 관한 유한요소법적 연구

윤현주,임용규,이동렬,조영수 대한치과교정학회 2005 대한치과교정학회지 Vol.35 No.2

본 연구는 상악 절치부에 active 토크가 가해졌을 경우, 교정력을 직접 받은 치아와 인접 치아의 반응을 알아보고자 상악 치아 및 치조골의 유한요소 모델을 제작하고, stainless steel, NiTi, TMA 세 종류의 각형 호선을 육면체 요소로 모델링하여 유한요소 모델을 완성하였다. 호선이 브라켓에 삽입되었을 때 브라켓에 발생하는 반력과 모멘트를 구하였고, 이것을 유한 요소 모델에 적용하여 각 치아의 변위와 응력 분포를 측정하였다. 브라켓에 발생하는 반력은 근원심 방향과 협설 방향으로의 힘은 0에 가까우며, 중절치, 측절치, 견치의 브라켓 근심측에서는 정출력이 원심측에서는 압하력이 발생하였다. 힘과 모멘트의 크기는 측절치에서 최대였고, 중절치, 견치 순으로 감소하였고, 소구치 부위와 대구치 부위에서는 급격히 감소하였다. 중절치와 측절치는 치관 협측, 원심 경사 이동과 압하를 보였으며, 견치는 치관 설측 원심 경사와 정출을 보였고, 제1소구치는 치관 설측 경사이동을 보였다. .019×.025 SS을 사용하여 상악 절치부에 토크를 부여하는 경우에는 측절치에 과도한 힘이 집중되므로, 임상에서 토크를 조절할 경우에는 NiTi나 TMA 호선을 사용하는 것이 바람직하리라고 생각된다. The purpose of this study was to investifate the stress distribtion in the periodontal tissue and the displacement of teeth when active torque was applied to the maxillary incisors by three-dimen-sional finite element analysis. A three- dimensional finite element model consisted of the maxillary teeth and surrounding periodontal membrane, .022×.028 Roth prescription bracket and stainless steel. NiTi and TMA rectangular ideal arch wires which were modeled by hexahedron elements. Applied active torques were 2, 5 and 10 degrees. The findings of this study showed that the reaction force acting on the bracket was the extrusion force on the mesial side of the incisors and canine and the intrusion force on the distal side of the incisors and canine.The amount of force and moment was greatest at the lateral incisor. When active anterior labial crown torque was applied, labial crown and distal tipping and intrusion of the incisors took place, and lingual crown distal tipping and extrusion of the canin occured. An excessive force was concentrated on the lateral incisor, when the stainless steel wire was used. NiTi or TMA wire os desirable for torque control.

자동 경계 탐지(Automated Border Detection)심초음파도를 이용한 좌심방 면적 및 기능의 평가

김현주,주승재,임진형,정효균,이영수,유호대,차태준,이재우 대한순환기학회 1998 Korean Circulation Journal Vol.28 No.2