Micro-CT System for Small Animal Imaging

남기용,김경우,김재희,손현화,유종현,강성훈,천권수,박성훈,윤권하,Nam, Ki-Yong,Kim, Kyong-Woo,Kim, Jae-Hee,Son, Hyun-Hwa,Ryu, Jeong-Hyun,Kang, Seoung-Hoon,Chon, Kwon-Su,Park, Seong-Hoon,Yoon, Kwon-Ha Korean Society of Medical Physics 2008 의학물리 Vol.19 No.2

살아있는 마우스 영상화를 목적으로 겐트리 회전형과 평판영상검출기를 기반으로 한 고분해능 마이크로 컴퓨터단층촬영 장치를 개발하였다. 이 장치는 주로, 마이크로 크기 광원사이즈를 갖는 X-선 광원, Csl (TI)과 결합된 평판형 상보성 금속산화 반도체 영상검출기(CMOS), 선형이송 카우치, 위치정보 엔코더와 결합된 겐트리, 그리고 영상데이터 처리를 위한 병렬처리 시스템으로 구성되었다. 본 장치는 겐트리 회전형으로 설계되었는데, 이는 살아있는 마우스를 CT 영상을 얻는데 있어서 마우스 움직임에 기인한 영상결점의 최소화에 유리하고 촬영하는 동안 쥐의 호흡마취시행에 여러 가지 장점을 갖기 때문이다. CT팬텀을 이용하여 개발한 CT장치의 공간해상도, 영상대비도 그리고 영상균일도를 평가하였다. 결과로써, 본 장치의 공간해상도는 MTF 곡선으로부터 10%에 해당하는 약 11.3 cycles/mm을 얻었으며, 마우스에 대한 방사선 피폭선량은 81.5 mGy의 결과를 얻었다. 저대비 영상팬텀을 이용한 영상실험에서 분해가능 최소영상대비차는 약 46 CT였다. $55{\times}55{\times}X100\;{\mu}^3$의 복셀(voxel) 크기에서 영상의 불균일도는 약 70 CT 임을 얻었다. 또한 본 연구에서는 살아있는 마우스의 몸체, 뼈, 그리고 간에 대한 영상 테스트 결과를 제시하였다. We developed a high-resolution micro-CT system based on rotational gantry and flat-panel detector for live mouse imaging. This system is composed primarily of an x-ray source with micro-focal spot size, a CMOS (complementary metal oxide semiconductor) flat panel detector coupled with Csl (TI) (thallium-doped cesium iodide) scintillator, a linearly moving couch, a rotational gantry coupled with positioning encoder, and a parallel processing system for image data. This system was designed to be of the gantry-rotation type which has several advantages in obtaining CT images of live mice, namely, the relative ease of minimizing the motion artifact of the mice and the capability of administering respiratory anesthesia during scanning. We evaluated the spatial resolution, image contrast, and uniformity of the CT system using CT phantoms. As the results, the spatial resolution of the system was approximately the 11.3 cycles/mm at 10% of the MTF curve, and the radiation dose to the mice was 81.5 mGy. The minimal resolving contrast was found to be less than 46 CT numbers on low-contrast phantom imaging test. We found that the image non-uniformity was approximately 70 CT numbers at a voxel size of ${\sim}55{\times}55{\times}X100\;{\mu}^3$. We present the image test results of the skull and lung, and body of the live mice.

파라미터 변화에 따른 IPMSM 특성

남기용(Ki-Yong Nam),이지영(Ji-Young Lee),이근호(Geun-Ho Lee),홍정표(Jung-Pyo Hong),정연환(Yeon-Hwan Jung) 대한전기학회 2004 대한전기학회 학술대회 논문집 Vol.2004 No.7

고속 PMSM의 2차원 등가 역기전력 해석 방법에 대한 연구

남기용(Ki-Yong Nam),황성률(Sung-Ryul Hwang),신판석(Pan-Seok Shin) 대한전기학회 2017 대한전기학회 학술대회 논문집 Vol.2017 No.7

비가역성 실혈성 쇽에서 본 가토심근, 혈장의 전해질 및 혈당량 변화

김기환,남기용,Kim, Ki-Whan,Nam, Kee-Yong 대한생리학회 1968 대한생리학회지 Vol.2 No.1

Twenty white rabbits anesthetized with nembutal (30 mg/kg) were employed in this experiment. Five of them served as controls; the remaining rabbits as experimental group were subjected to irreversible hemorrhagic shock. Shock was induced by bleeding the animals until mean blood pressure decreased to a level of 50-40 mmHg. This level of pressure was maintained for 3-4 hours, after which the drawn blood was reinfused. The reinfusion of blood caused the elevation of arterial pressure almost the control level for some minutes, after which a gradual and progressive decline of blood pressure became evident. This decline was thought to be the result from irreversible hemorrhagic shock. When mean blood pressure declined to less than 50 mmHg, chest was opened and samples of arterial blood and left ventricular muscle were taken. Left ventricular muscle and blood plasma were analyzed for potassium, sodium, chloride and water content. Blood glucose concentration was determined by Somogyi-Nelson's method. Extracellular and intracellular myocardial water and electrolyte content were calculated on the basis that electrolytes are distributed between plasma water and interstitial water according to Gibbs-Donnan equilibrium. In this calculation extracellular water was substituted for Na space. The findings obtained were as follows: 1. The concentration of blood glucose was 87mg% in the controls and it rose to 222 mg% in shock (P<0.01). 2. Plasma potassium elevated significantly from 3.3 mEq/l in controls to 8.0 mEq/l in shock (P<0.01), while small decreases in sodium (151-146 mEq/l) and chloride (102-96 mEq/l) were observed (P<0.3, P<0.1), 3. The changes of blood water content (83.1-84.3%) and cardiac water content (77.5-78.3 gm/100gm WT) were observed. 4. In control animals myocardial potassium levels which averaged 30.2 mEq/100 gmDT rose significantly to 40.3 mEq/100 gmDT in shock (P<0.01), while moderate decreases in sodium(16.3-14.3 mEq/100 gmDT) were observed in shock. 5. The calculated transmembrane resting potential of left ventricular muscle of control animals averaged 95 mV, while rabbits in shock averaged 77 mV. (P <0.01). The findings of this experiment do not correspond with the conclusions that myocardial depression seems to be the cause of irreversible hemorrhagic shock, because the excitability of heart muscle is elevated. From the point of view that the lowered transmembrane resting potential, the cause of death in terminal stage of irreversible hemorrhagic shock may be ventricular fibrillation. It can't be said, however, that the lowered transmembrane resting potential is responsible for the transition from reversible to irreversible hemorrhagic shock. The marked increase in blood glucose suggested that glycogenolysis in the liver is favorably active in shock.

혈관 및 장관 평활근의 K-경축 발생기전

김기환,황상익,남기용,Kim, Ki-Whan,Hwang, Sang-Ik,Nam, Kee-Yong 대한생리학회 1979 대한생리학회지 Vol.13 No.1

The activation mechanism of K-induced contracture was studied in renal vascular muscle which does not generate an action potential readily and in taenia coli which generates a spike potential spontaneously. Helical strips of arterial muscle from rabbit renal arteries and longitudinal strips of taenia coli from guinea-pig's colons, respectively, were prepared. All experiments were performed in Tris-buffered Tyrode solution which was aerated with 100% $O_2$ and kept $35^{\circ}C$. Renal arterial muscles developed the contracture rapidly, which was composed of a small phasic and a large tonic components, when exposed to a 40 mM K-Tyrode solution. In the absence of external $Ca^{++}$, however, no K-contracture appeared. The contracture induced by K-depolarization was abolished by the treatment with verapamil, which is known to be a selective $Ca^{++}-blocker$ through potential-sensitive $Ca^{++}-channel$. K-contracture of taenia coli showed the contracture composed of a large phasic and a small tonic components. In the $Ca^{++}-free$ Tyrode solution, only the tonic component was abolished and almost no change in the phasic component was observed. The amplitude of tonic component was dependent on the external $Ca^{++}$; The tonic component increased dose-dependently by a stepwise increase of the external $Ca^{++}$, and this component decreased in parallel with the increase of verapamil in the external medium. The results of this experiment suggest that K-contracture of rabbit renal artery is the direct result of the influx of the external $Ca^{++}$, while that of taenia coli is the result of both $Ca^{++}$ influx and the release of sequestered $Ca^{++}$.

적출 유두근에서 근육길이에 따른 계단현상 및 칼슘 수축력의 변화

김기환,엄융의,남기용,Kim, Ki-Whan,Earm, Yung-E,Nam, Kee-Yong 대한생리학회 1980 대한생리학회지 Vol.14 No.2

The effects of various inotropic interventions on the shape of the steady state length tension relation and the length-dependent activation process in cardiac muscle were studied. The influence of inotropic interventions upon the action potential was also observed. The range of varying muscle length was from the optimal length$(l_{max})$, where the active tension production is maximal, to 0.85 $l_{max}$. Changes in stimulus frequency or in external bathing Ca concentration constituted the inotropic interventions in this experiment. The papillary muscles were isolated from the rabbit right ventricles and perfused with $HCO-_3\;-buffered$ normal Tyrode solution which was aerated with $3%\;CO_2-97%\;O_2$ mixed gas and kept at $35^{\circ}C$. Resting Passive tension at $l_{max}$ was approximately 30% of the total tension and appeared from the muscle length of 0.90 $l_{max}$. The effect of stimulus frequency on the steady state level of developed tension was: As the stimulus frequency was increased from 0.1 to 0.5 Hz, there was little change in developed tension. As the frequency was increased further, to a value of about 3 Hz, tension increased steeply. Further increase of the frequency to 5 Hz had little additional effect on the developed tension. The length-tension curves for isometric peak tension became more steeper with the degree of potentiation by inotropic interventions. The relative steepness of the normalized length-tension curves where tension production was expressed as a percentage of maximal tension developed at $l_{max}$, varied inversely with the level of inotropic state and these curves were not superimposable one another. Thus at the stimulus frequency of 2 Hz or at the external Ca concentration of 8 mM, the relative decline in the developed tension for a given change in muscle length was considerably less than the decline observed at the frequency of 0.5 Hz or at the concentration of 2 mM Ca. Action potential duration was prolonged significantly as the frequency increased from 0.2 to 2 Hz, and this change in action potential duration was not observable on the changes in muscle length. There was a tendency of the hyperpolarization of membrane potential when the muscle length was shortened from $l_{max}$ to 0.95 $l_{max}$. These results support the hypothesis that there is a length-dependence of the activation process.

인버터 시스템에서 스위치 온드랍에 의한 출력 전류 왜곡 보상

이광해(Gwang-Hae Lee),남기용(Ki-Yong Nam) 대한전기학회 2018 대한전기학회 학술대회 논문집 Vol.2018 No.-

통계적 기법에 의한 24,000rpm 초고속 스핀들 개발

임정숙(Joeng-suk Lim),남기용(Ki-Yong Nam),정원지(Won-Jee Chung),이춘만(Choon-Man Lee) 한국생산제조학회 2006 한국공작기계학회 춘계학술대회논문집 Vol.2006 No.-

The spindle system with a built-in motor can be used to simplify the structure of machine tools, to improve the machining flexibility of machine tools, and to perform the high speed machining. In this system the shaft is usually assumed as a rigid rotor. In the high-speed spindle system design, it is very important to know the contribution ratio of core parts to improve static and dynamic stiffness. The natural frequency and deformation of the spindle end is obtained by FEM mode analysis. And statistical method was used to draw most suitable condition of each part.

PC를 이용한 GMS/WEFAX 수신 및 영상처리 시스템 개발(1) -시스템 Hardware의 개요

윤기준 ( Gi Joon Yun ),박경윤 ( Kyoung Yoon Park ),서명석 ( Myoung Seok Suh ),조용민 ( Young Min Cho ),남기용 ( Ki Yong Nam ),김민수 ( Min Soo Kim ) 大韓遠隔探査學會 1993 大韓遠隔探査學會誌 Vol.9 No.1

In this study, an integrated GMS(Geostationary Meteorological Satellite) receiving ground system, which includes the real-time reception and image processing of WEFAX data, has been developed. The demodulator, PC interface and application softwares of the system were made and integrated with the commercially available antenna and receiver. Hardwars of the system were described in this part. This system operates at IBM PCI/AT or above. It can be used for students at school and for application research in the fields of meteorology, oceanography, hydrology and astronomy.

소형화 연 X-선 투과현미경을 위한 새로운 광학설계와 개발

김경우(Kyong-Woo Kim),권영만(Young-Man Kwon),김규겸(Kyu-Gyeom Kim),김재희,민종환(Jong-Hwan Min),임종혁(Jong-Hyeok Lim),남기용(Ki-Yong Nam),민진영(Jin-Young Min),윤권하(Kwon-Ha Yoon) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.5

In this paper the conceptual design and development of a compact vertical type soft x-ray microscope is described. This x-ray microscope operates in the water window wavelength region (2.3~4.4㎚), where natural contrast between carbon (protein) and oxygen (water) allows imaging of unstained biological material their natural, hydrated environment. Until now, operational x-ray microscopes are based on synchrotron radiation sources, which limit their accessibility. Many biologists would benefit from having the x-ray microscope as a tool among other tools in their own laboratory. For this purpose we introduced the compact vertical type soft X-ray microscope with 50 ㎚ resolution for biomedical application. The compact vertical type soft x-ray microscope is based on a laser plasma x-ray source, doubled ellipsoidal condenser reflective optics, diffractive zone plate optics and MCP coupled with CCD to record an x-ray image. The source is a liquid-jet target laser plasma source, which is practically debris free and suitable for high average power operation. The flux, brightness and bandwidth of this source has been simulated and optimized for X-ray microscopy for biology application. A doubled ellipsoidal condenser reflective mirror operates as condenser and illuminates the sample. The high resolution imaging is currently performed with a ~12% efficient Au zone plate with an outmost zone width of 36㎚. Detection is performed with a Chevron typed MCP coupled with CCD.