국소적 간병변이 다면 역동적 자기공명영상 소견

김도중 대한영상의학회 1995 대한영상의학회지 Vol.33 No.6

Purpose : To evaluate the dynamic enhancement patterns of focal hepatic lesions using breath-hold dynamic MRimaging for differential diagnosis. Materials and Method : Thirty three patients (24 men and 12 women, mean age of55 years) with 56 known liver masses on CT scan and US underwent MR imaging with 1.5T. After T1-weighted fastmultiplanar spoiled gradient recalled (FMPSPGR) imaging, breath-hold FMPSPGR images were obtained at 0, 1, 3, 5,and 10 minutes after bolus injection of Gd-DTPA. The cases consisted of 16 hepatocellular carcinomas, 24hemangiomas, 6 metastases, 3 cholangiocellular carcinomas, and 7 hepatic cysts. The dynamic enhancement patternswere evaluated on the basis of initial enhancement study and, the degree of enhancement was also levaluatied.Results : Of 24 hemangiomas, most cases showed centripetal filling-in pattern of enhancement except 3 cases whichshowed homogeneous enhancement pattern on the early dynamic phase. All hemangiomas showed very high signalintensity which persisted to the delayed phase. The eccentric enhancement pattern was the most common type inhemangiomas (63%). Hepatocellular carcinomas had heterogeneous enhancement pattern on early and delayed phase (81,88%) and showed diminished signal intensity on the delayed images. 14 of 16 hepatocellular carcinomas (88%) hadperitumoral halo. Variable enhancement patterns was observed in metastases including progressive centripetalfilling-in pattern (67%). All metastases showed prominent peritumoral halos and low signal intensity.Cholangiocellular carcinomas showed early centripetal filling-in and heterogeneous enhancement pattern on delayedphase. None of hepatic cysts showed enhanced. Conclusions : Dynamic breath-hold MR imaging with Gd enhancementallows accurate assessment of hemodynamic status of hepatic lesions and is useful in differential diagnosis offocal hepatic lerions.

열차의 곡선주행능 해석에 관한 연구

김도중,박삼진,Kim, Do-Jung,Park, Sam-Jin 한국기계연구원 1985 기계연구원소보 Vol.14 No.-

Kyung-p-1 main line is characterized by its curves radii of which are considerably small. It is essential for running time reduction of train to improve capabilities of curve negotiation. This improvement can be achieved by designing a bogie with flexible suspension system. The effect of the improvement is mainly concerned in the primary yaw stiffness of bogie suspension. This paper gives a linear analysis for the motion of railway vehicle on curved track and gives also computer simulation results for Semaul Train. The results introduce a conclusion that the primary yaw stiffness of Semaul train is too rigid to be self-steering on Kyung-pu main line curves.

실업계 고교 교육과정 운영의 정상화 방안

김도중 인간교육자원경영학회 2004 학술대회 자료집 Vol.14 No.-

濟州地城 貴金屬工團 造成時 産業振興 및 運營戰略에 關한 方向 : 貴金屬工團 設立 妥當性 檢査를 中心으로

김도중,김대경 제주관광대학 1995 論文集 Vol.1 No.-

휠 세트 Yaw 운동을 고려한 바퀴와 선로 사이의 3차원 접촉 기하 해석

김도중,박삼진,Kim, Do-Jung,Park, Sam-Jin 한국기계연구원 1985 기계연구원소보 Vol.15 No.-

Dynamics of railway vehicles are strongly influenced by the wheel/rail contact forces. Wheel/rail contact geometric characteristics are important parameters to determining wheel/rail contact forces. In general, geometric relations between wheel and rail are represented by nonlinear functions of the wheelset lateral excursion and the relative yaw angle. There are some analytical and experimental studies to show the influences of the wheelset lateral displacement on wheel/rail geometric relations. Recently radial steering bogie which is designed to have flexible yaw motions of wheelsets was developed to improve curve negotiation performance. The radial steering bogie makes it important problem to study the effects of wheelset yaw motion on wheel/rail geometric relations. This paper describes the method to analyze 3-dimensional wheel/rail contact geometry considering wheelset yaw motion and describes also some computer simulation results.

원통형 스프링의 동특성 해석을 위한 헬리컬 로드 유한요소 개발

김도중,이덕영 한국소음진동공학회 1999 소음 진동 Vol.9 No.3

A 3-dimensional helical rod finite element is devloped for the dynamic analysis of cylindrical springs. Element matrices are formulated using the Galerkin's method, and an exact static deflection curve is used as a shape function. Because the resultant mass and stiffness matrices of the model are symmetric, effective direct solution method can easily be applied for analysing dynamic behavior of springs. The model is used to analyze the dynamic characteristics of a typical automotive valve spring. The effectiveness of the developed helical rod element is verified by comparing the results of the proposed method with those of a classical theory and experiments. The helical element developed in this study is superior to a straight beam element and a 2-dimensional curved beam element for this problem.

올리브핵 퇴행성비대의 자기공명영상 소견

김도중 대한영상의학회 1997 대한영상의학회지 Vol.36 No.6

자동차 엔진 밸브 스프링의 최적설계에 관한 연구

김도중 울산대학교 기계부품 및 소재 특성평가연구센터 1999 연구보고서 Vol.1999 No.-

밸브 스프링은 밸브트레인의 동적 거동과 엔진의 성능에 매우 중요한 영향을 미치는 부품이다. 스프링의 설계 공간 제약과 높아지는 성능 요구 조건으로 인하여 최근에는 비원형 단면 스프링의 사용이 보편화되고 있다. 본 연구의 목적은 엔진 사양에 가장 적합한 최적원형 단면 스프링의 응력 분포, 밸르 스프링의 비선형 진동특성. 밸브트레인의 운전 성능, 등이 고려될 것이다. 1차년도 연구인 당해년도에는 비원형 단면을 가지는 밸브 스프링의 응력 분포를 계산하는 프로그램을 개발했다. 이론적인 해가 존재하는 몇 가지 예에 대하여 프로그램을 실행한 결과 이론값과 응력분포를 얻었다. 프로그램은 주어진 엔진에 가장 적합한 최적의 밸브 스프링을 설계할 수 있도록 확장될 것이다. Valve spring is one of critical components which influence valve train dynamics and engine performance. Because the size and performance are so tightly controlled, recent engines have a tendency to use valve springs with non circular cross section wire. The purpose of this study is to develop a computer software for designing optimal valve springs. The program includes stress analysis of valve spring with non circular cross section, vibration analysis of nonlinear spring surging, and kineto-static analysis of valve trains. In this year, a computer program was developed which analyze stress distribution in the valve spring wire with non circular cross section. In the test run of typical problems, the program gives exact values with analytical solutions. The program will be extended to design an optimal valve spring which gives best performance for a given engine.

[論文] 캠 형상 최적설계를 위한 밸브 트레인 동특성 해석 모델

김도중(D.J.Kim) 한국자동차공학회 1993 오토저널 Vol.15 No.2

A numerical modeling technique is proposed for computer simulations of high speed valve train dynamics. The dynamic terms in the valve spring reaction forces are calculated using linear vibration theory for given kinematic valve motions. Because the spring dynamics are analyzed before the time stepping integration. spring surge phenomena can be included without using additional computer time. In addition to that, steady state response of the valve train dynamics can be obtained by just one cycle simulation. Consequently, valve train dynamics can be simulated very quickly without noticeable errors in accuracy. The experimental results prove the computer model developed here is accurate and also computationally efficient. The model is especially useful for cam profile optimizations.

DRRD캠 형상 최적설계를 위한 다항식 합성법과 캠 로우브면적에미치는 형상계수들의 영향

김도중(Dojoong Kim),박성태(Sungtac Park) 한국자동차공학회 1993 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-

A multi-polynomial method is proposed to synthesize DRRD cam protiles. A cam Jill duration is divided into 10 sections. cach of them is expressed by a polynomial equation. 12 design variables are extracted from the cam profile displacement. velocity, and acceleration curves. Because all the design variables have physical meanings which arc familiar to most cam designers, it is easy to imagine a profile shape from the design variables. The design envelope of the method is wide enough to be used in DRRD automotive cam designs. Polydyne cams, widely used in automotive engines. are included into the envelope. Unlike Polydyne cams. the method provides capability of wide velocity factor variations. which gives much flexibility in flat-faced t:Jppet design. Area factor of profiles designed by the method can be increased 5 - 10% compared to those of Polydyne cams without increasing acceleration factor. The method is especially useful for cam profile optimizations.<br/>