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김종문,Kim, Jong-Mun 한국방위산업진흥회 1993 國防과 技術 Vol.- No.178
단기간에 효과가 나타나지 않는 군사력 건설의 투자는 지속성이 중요하고 일시적 단절 및 삭감은 추후에 더 큰 부담과 비경제적 효과를 유발시킬 가능성이 크기 때문에 적정국방비를 안정적으로 확보함이 요구됩니다
$H_{infty}$ 제어기의 자기부상 시스템에의 적용
김종문,김석주,박민국,최영규,Kim, Jong-Moon,Kim, Seog-Joo,Park, Min-Kook,Choi, Young-Kiu 대한전기학회 2002 전기학회논문지 D Vol.51 No.11
In this paper, a suspension control of a magnetic levitation(MagLev) system with flexible rail is designed and presented. The numerical modelling for the electromagnetic system to be controlled as a target plant is carried out. And dome kinds of the hardware system including CPU board, AD board, DA board, sensors, and switching power amplifier are described. Using the derived model, the stabilizing controllers, such as PID and $H_{\infty}$ controller, for the MagLev system are designed using the MATLAB toolbox. The designed controllers are validated by some experimental results as well as numerical simulations. So it is shown that $H_{\infty}$ controller can give the better performance for the plant with flexible modes than PID controller.
다중 자기부상 시스템의 분산형 $H_{\infty}$ 제어
김종문,이상혁,최영규,Kim Jong-Moon,Lee Sang-Hyuk,Choi Young-Kiu 대한전기학회 2005 전기학회논문지 D Vol.54 No.12
In this paper, an application of a decentralized $H_{\infty}$ controller(DHC) to multiple controlled-permanent magnet(CMAG) magnetic levitation(Maglev) systems is presented. The designed DHC using two Riccati equations iteratively has simpler structure and needs less computational loads than conventional centralized $H_{\infty}$ controller. A target plant is a hybrid-type CMAG system with permanent magnet and coil, and its mathematical model is firstly derived to design the DHC. To implement the designed algorithm, a real Maglev vehicle system including digital controller, chopper, sensor, etc., is manufactured. To compare the performances of the DHC method with an observer-based state feedback control(OSFC), the input tracking and disturbance rejection characteristics are experimentally tested. As performance indices(PI), integral of squared error(ISE), integral of absolute error(IAE), integral of time multiplied by absolute error(ITAE) and integral of time multiplied by squared error(ITSE) are used. From the experimental results, it can be seen that the input tracking and disturbance rejection performances of the DHC are better than those of the conventional controller.
준밀폐형 2상자연순환 회로 내에서의 유동 진동에 관한 실험적 연구
김종문,이상용,Kim, Jong Moon,Lee, Sang Yong 대한기계학회 1998 大韓機械學會論文集B Vol.22 No.12
In the present experimental study, the flow behavior in a semi-closed two-phase natural circulation loop was examined. Water was used as the working fluid. Heat flux, heater-inlet subcooling, and flow restrictions at the heater-inlet and at the expansion-tank-line were taken as the controlling parameters Six circulation modes were identified by changing heat flux and inlet subcooling conditions ; single-phase continuous circulation, periodic circulation (A), two-phase continuous circulation, and periodic circulations (B), (C), and (D). Among these, the single-phase and two-phase continuous-circulation modes exhibit no significant oscillations and are considered to be stable. Periodic circulation (A) is characterized by the large amplitude two-phase f10w oscillations with the temporal single-phase circulation between them, while periodic circulation (B) featured by the flow oscillations with continuous boiling inside the heater section. Periodic circulation (C) appears to be the manometric oscillation with continuous boiling. Periodic circulation (D) has the longer period than periodic circulation (B) and a substantial amount of liquid flow back and forth through the expansion-tank-line periodically ; this mode is considered the pressure drop oscillation. Parametric study shows that the increases of the inlet- and expansion-tank-line- restrictions and the decrease of inlet subcooling broaden the range of the stable two-phase(continuous circulation) mode.
습식법에 의한 Hydroxyapatite 분말제조와 그 분체특성
김종문,김겸,이서우,Kim, Jong-Moon,Kim, Kyum,Lee, Seo-Woo 한국세라믹학회 1991 한국세라믹학회지 Vol.28 No.1
The hydroxyapatite powders were prepared by the reaction of Ca(CH3COO)2$.$H2O and H3PO4 in aqueous solution. Effect of Ca/P mole ration and pH value on the powder characteristics were investigated. For phosphoric acid was dissociated to PO43- ion above pH 10, the preparation condition of hydroxyapatite by H3PO4 solution had this value. Dried powders were agglomerated each other. The mean agglomerate particle diameter was minimum when the condition was pH 11, Ca/P=1.75 and its specific surface area was 97㎡/g. All powders had poor crystallinity and small CO2. It prevented CaCO3 from using aspirator in preparation and maturing time. In most cases, hydroxyapatite was decomposed into ${\beta}$-TCP at more than 800$^{\circ}C$, into ${\alpha}$-TCP at 1200$^{\circ}C$. However non-decomposed hydroxyapatite was remained in Ca/P=1.85.
지주막하출혈에 의한 지연성 허혈신경장애의 진단에 있어서 경두개도플러 검사의 신뢰도
김종문,강성돈,Kim, Jong Moon,Kang, Sung Don 대한신경외과학회 2000 Journal of Korean neurosurgical society Vol.29 No.7
Objective : The reliability of transcranial doppler sonography(TCD) for predicting delayed ischemic neurologic deficit( DIND) was investigated in patients with aneurysmal subarachnoid hemorrhage(SAH). Methods : The velocity of blood flow through the middle cerebral artery was measured by TCD in 70 patients treated surgically within 72 hours due to ruptured cerebral aneurysm. A correlation between measured maximal mean blood flow velocities and clinical factors including age, hypertension, Hunt-Hess grade, Fisher grade, DIND, and outcome was made. Results : An age-dependent reduction of the measured maximal mean velocities was found(r=-0.4043, p<0.001). Flow velocities in hypertensive patients were significantly lower than in the normotensive individuals(two-tailed T test, p<0.05). There was no significant difference between the flow velocities and evaluated other clinical factors. When the flow velocities of 14 patients who developed DIND were compared with those of patients without deficits, no significant difference was seen. A significant increase in flow velocities in the days before the onset of DIND was found only in 4 of 14 cases. High flow velocities did not necessarily mean impending neurological deficits : 6 of 70 patients tolerated flow velocities over 160cm/s. Conclusion : We suggest that TCD readings have limited utility for predicting DIND following SAH, especially in older or hypertensive patients. More direct measurements of blood flow are necessary to adequately predict which patients are at high risk of DIND.