• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2007.06a
• /
• pp.191-191
• /
• 2007

유효 산화막 두께가 약 2.0nm 정도의 $ZrO_2$ 절연막 위에 Ta-Mo 금속 합금과 Ru-Zr 금속 합금을 Co-sputtering 방법을 이용하여 여러 가지 일함수를 갖는 MOS capacitor를 제작하여 전기적 재료적 특성에 관하여 연구를 하였다. 그 결과 각각의 금속 합금 게이트는 4.1eV 에서 5.1eV 사이의 다양한 일함수를 나타냈으며, $400^{\circ}C$, $500^{\circ}C$, $600^{\circ}C$, $700^{\circ}C$, $800^{\circ}C$ RTA 후의 C-V특성 곡선 및 I-V 측정을 통하여 누설전류를 확인하였다. 그 결과 Ta-Mo 금속 합금의 경우 스퍼터링 파워가 100W/70W에서 NMOS에 적합한 일함수를 가졌으며, Ru-Zr 금속 합금의 경우 스퍼터링 파워가 50W/100W에서 NMOS에 적합한 일함수를 가졌다. 열처리 후의 C-V특성 곡선에서도 정전용랑 값이 거의 변하지 않았으며 평탄 전압의 변화도 거의 없었다. 누설전류 특성에서는 물리적 두께가 비슷한 기존의 $SiO_2$ 절연막에서 실험결과와 비교하여 약 100배 정도 감소되었음을 알 수 있었다. 또한 기존의 실험들에서 나타난 열처리 후의 $ZrO_2$ 절연막과 Si 기판 사이의 Interfacial layer 의 동반 두께 증가로 인한 전기적 특성 저하가 나타나지 않는 줄은 특성을 보여준다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2010.05a
• /
• pp.489-490
• /
• 2010

• ETRI Journal
• /
• v.7 no.4
• /
• pp.3-10
• /
• 1985

After the light from an incoherent LED was transmitted through the multimode fibers which were linked over 10 km, the nearfield power distribution reached the steady-state independent of launching conditions. It has been also found that the steady-state output power distribution showed the pattern of Gaussian function. In this steady-state Gaussian function pattern, the measured losses of fibers were very repeatable values. In case of using LD source, the speckle phenomena in near -field power distribution appeared until the distance of 10 km. And the output power distribution did not reach the steady-state shown in LED even over 20km on account of the coherence and the nonuniform lasing modes of LD. But the measured losses of fibers were nearly stable in this long distance.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.31 no.8
• /
• pp.99-106
• /
• 2003

Geometrical design variables are numerically investigated to improve aerodynamic performance of the supersonic impulse turbine of a turbopump in a liquid rocket engine. Aerodynamic redesign was performed for maximization of the blade power. Four design variables considered are blade angle, blade thickness and radii of upper and lower arc blade with appropriate constraints. A fast Navier-Stokes solver was developed and Chien's k-$\varepsilon$ turbulence modelling was used for turbulence closure. In initial shape, a flow separation was found in the middle of blade chord. However, it disappeared in final shape via its geometrical design variable change. About 3.2 percent of blade power was increased from this research.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.26 no.2
• /
• pp.103-111
• /
• 2014

The wave power, extracted from a circular array of small power buoys, is investigated under the potential theory. It is assumed that the buoy's radius, the draft, and the separation distance are much smaller than the water depth, the wave length, and the radius of a circular deployment area. The boundary value problem involving the macro-scale boundary condition on the mean surface covered by buoys is solved using the eigenfunction expansion method. The capture width, which is defined as the ratio of the extracted power to the wave power per unit length of the incident wave crest, is assessed for various combinations of packing ratio, radius of a circular array, and PTO damping coefficient. It is found that the circular array deployment is more effective in the viewpoint of efficiency than the single large buoy of the same total displaced volume.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2009.04a
• /
• pp.639-642
• /
• 2009

LN2440SBC 임베디드 보드는 ARM 코어 방식의 S3C2440A CPU를 가진 임베디드 컴퓨터 시스템이다. 이 시스템에 부착한 터치스크린 기능을 가진 TFT LCD 키트인 LP35의 구동을 위해서는 ARM 코어, LCD 컨트롤러, 그리고 LCD 장치와의 통신을 위한 SPI(serial peripheral interface)의 초기화와 LCD 화면에 이미지, 선, 도형 같은 것들의 출력을 가능하게 해주는 그래픽스 라이브러리 함수들이 필요하다. 본 논문은 이같은 기능들을 가지는 LP35를 위한 드라이버의 구현 방법을 기술한다. 특히, 드라이버 구동을 위한 초기화 방법과 화면 출력 기능들의 구현을 위해 필요한 픽셀 디스플레이 함수의 구현에 중점을 두어 설명한다. 또한 픽셀 디스플레이 함수를 이용한 기본 그래픽스 라이브러리 함수들에 대해 설명한다. 드라이버의 초기화를 위해서는 클럭 속도 설정, 범용 입출력 핀(GPIO)을 LCD와 SPI 용으로의 할당. SPI의 마스터/슬레이브 및 보오 레이트 설정, LCD 컨트롤러 레지스터 설정을 통한 LCD 기능 선택. 그리고 SPI를 통한 LCD 장치로의 파워 온(power on) 명령 전달 등이 수행된다.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.21 no.12
• /
• pp.1104-1111
• /
• 2011

This paper investigates the filtered velocity feedback(FVF) controller for the reduction of the acoustic power radiated from a clamped beam. The instability problem due to the non-collocated sensor/actuator configuration when using PZT actuator should be sorted out. The roll-off property of the FVF controller at high frequency helps to alleviate the instability. The dynamics of clamped beams under forces and moments pair and the FVF controller are first formulated. The formulation of the sound radiated power is followed. The open loop transfer function(OLTF) synthesized with 100 modes is used to determine the stability of the control system. The control performance is finally estimated. The levels of the vibration and the sound radiated power are reduced in the wide bandbelow the tuning mode of the FVF controller.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2007.11a
• /
• pp.12-22
• /
• 2007

This paper presents to predict the powertrain structure-borne noise which is primary resource of interior noise. As the first step, it is built up a hybrid powertrain model which is based on the real powertrain which is verified with static and dynamic properties. The methods for verifying are modal analysis and running vibration testing which are experimentally implemented. Based on the Hybrid powertrain component model, an initial predictive assembly model is simulated. As the second step, the characteristic transfer functions are measured that are dynamic stiffness of rubber mounts and vibro-acoustic transfer function based on the acoustic reciprocity. Several techniques utilizing special experimental devices have been proposed for this research. Finally, the structure-borne noise by powertrain will be predict and verify with dynamic simulation and experiment.

• Proceedings of the KIPE Conference
• /
• 2008.06a
• /
• pp.434-436
• /
• 2008

같은 정격을 가진 배터리 일지라도 온도나 노화에 따라 용량, Direct current internal resistance(DCIR)이 서로 다른 값을 나타낸다. 또한, 용량과 DCIR의 상관관계가 항상 성립하는 것은 아니다. 이러한 특성으로 인해 펄스파워 관련 State of health(SOH)를 알기 어렵다. 이번 논문에서는 해밍네트워크를 이용한 리튬이온 배터리의 특성을 분석, 연구하였다. 펄스파워는 전압의 함수이다. 배터리 충방전 프로파일을 이용하여 전압패턴들을 선정한 후 특성 파라미터를 이용하여 해밍네트워크에 사전에 학습시킨다. 다음, 임의의 배터리 데이터를 통계 처리하여 전압패턴 특성 파라미터를 추출한 후 신경회로망에 입력하여 학습한 전압패턴들 중 임의의 배터리에 맞는 배터리를 선정한다. 패턴선정은 상온에서 10개의 리튬이온 프레시 배터리(1.3Ah)가 이용되었고 검증을 위해 DCIR 값을 구하였다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2011.10a
• /
• pp.377-383
• /
• 2011

This paper reports the filtered velocity feedback (FVF) controller to reduce the acoustic power from clamped beams. The instability problem due to the non-collocated sensor/actuator configuration when using PZT actuator should be resolved. The roll-off property of the FVF controller at high frequency helps to alleviate the instability. The dynamics of clamped beams under forces and moments pair and the FVF controller are first formulated. The formulation of the sound radiated power is followed. The open loop transfer function (OLTF) synthesized with 100 modes is used to determine the stability of the control system. The control performance is finally estimated. The levels of the vibration and the sound radiated power are reduced in the wide band below the tuning mode of the FVF controller.