• 한국자동차공학회논문집
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• 제10권1호
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• pp.59-66
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• 2002

This paper presents the process of the needle lift estimation ova common-rail injector fur HSDI(High Speed Direct Injection) diesel engines. A nonlinear mathematical model of dynamic behaviors of common-rail injector is established at first. Based on the mathematical model of the common-rail injector, the methodology of estimating the injector needle lift is introduced. A sliding mode observer is applied to overcome the model uncertainties. The common-rail injector model and the needle lift estimator are verified by simulations and experiments. The simulation and experimental results indicate that the model outputs are in a good agreement with experimental data, and the proposed nonlinear sliding observer can effectively estimate the needle lift.

• 한국유체기계학회 논문집
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• 제2권2호
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• pp.39-45
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• 1999

Pumped-storage power plants pumps the water from the lower reservoir to the upper reservoir using the extra electric power at night and generates electric power in the daytime. Currently it tends to be a high-head large-capacity machine. In this paper, we developed the computer programs for vibration analysis of the pump/turbine and generator/motor rotor system considering electromagnetic force, hydrodynamic unbalance force, dynamic characteristics of guide bearings and add mass of water. This program was verified by applying it to the real model and calculating the critical speed, natural mode and unbalance response.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 추계학술대회 논문집
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• pp.37-40
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• 2001

This paper is suggested an optimal switching angle of a switched reluctance motor drive system for maximum energy ratio. A new magnetizing method with a low-frequency increasing the energy conversion ratio that is related to the efficiency of motor is proposed As results, it improves the efficiency about 2[$\%$]. And a torque ripple is also reduced compared with that of the conventional switching angle magnetizing approach. In order to start softly regardless of a large ripple torque, the profile of phase current is predicted and current control mode was adapted when it is operated under the starting speed.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2005년도 춘계학술대회논문집
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• pp.368-371
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• 2005

In this paper, a small band pass filter is designed using new probe type for wireless communication system. In order to provide a band pass filter which can be reduced in dimension, can be reduced in height, and can be surface-mounted. The filter was fabricated using $TE_{01{\delta}}$ mode dielectric resonator. The input/output probes are attached to coner portion of the rectangular metal cavity. Results of the manufactured filter$(12{\times}12{\times}8mm)$ show that the center frequency is 9.953GHz, the insertion loss is -2.98 dB, the 3dB-bandwidth is 15 MHz, and the lode Q is 663.

• 한국산학기술학회:학술대회논문집
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• 한국산학기술학회 2010년도 추계학술발표논문집 1부
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• pp.417-420
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• 2010

최근 UWB, IEEE802.11n과 같은 고속 무선 통신에서는 고속의 암호/복호 처리가 요구되고 있다. 본 논문은 UWB, Zigbee, IEEE802.11과 같은 최신 무선 통신 기술에서 보안 기능의 근간이 되는 CCM(CTR+CBC-MAC) 보안 모드 구현에 관한 것이다. AES와 같은 블록암호알고리즘과 결합된 CCM 기능을 하드웨어로 구현하는 방법을 제시한다. 특히, MAC, DMA모듈과 Hard-wired된 형태로 구현하여 통신속도 저하없이 무선 데이터 송/수신과 동시에 실시간으로 암호/복호 연산을 수행할 수 있으며, CCM 구동 clock을 최소화하여 고속 동작과 저전력 설계의 목적을 달성할 수 있다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.451-454
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• 2007

This paper presents the pattern characteristic using the electrostatic drop-on-demand ink-jet printing system. In order to achieve the pattern characteristic of electrostatic inkjet printing, the capillary inkjet head system is fabricated using capillary tube, Pt wire and electrode, and is packaged by acrylic board for the accurate alignment between wire and electrode-hole. The applied DC voltage of 1.4 $\sim$ 2.0 kV used for the observation of electrostatic droplet ejection. Electrostatic droplet ejection is directly observed using a high-speed camera. For investigated pattern characteristic, conductive inkjet silver ink used. The higher voltage has a good condition which has micro dripping mode. Also, the droplet size decreases with increasing the supplied DC voltage. This paper shows the pattern which is formed by about 300um. Also, capillary inkjet head system will be applied industrial area comparing conventional electrostatic inkjet head system.

• 소음진동
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• 제11권2호
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• pp.315-322
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• 2001

This paper is focused on the frictionally induced thermoelastic instability (TEI) in automotive disk brakes. This instability leads to the formation of localized high temperature contact regions known as hot spots. This article investigates the themoelastic instability in automotive disk brake systems consisting of a finite thickness layer (disk) and two half-planes (pads) using a perturbation method. The antisymmetric mode involves hot spots located alternately on two sides of the disk. As a result the circumferentially periodic hot spots produce rotor surface distortion and Induce low frequency vibration. Also the effects of system parameters on the critical speed for TEI are investigated.

• 한국자동차공학회논문집
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• 제7권7호
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• pp.86-93
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• 1999

Turbocharger has been used to increase the performance of diesel engine, especially ship engine , for years. Recently, the turbocharger is being adopted not only for an agricultural engine but also for an automobile engine. To improve the performance of diesel engine , the problem of the reduction of A/F ratio in high speed should be solved. Turbocharger is well known for its cost effectiveness, reliability and duration . In this study, an experiment was conducted to verify simulation program . The results for natural aspiration engine and turbocharged engine were compared. In order to estimate the characteristics of exhaust gas, D-13 mode was selected. Power, torque and BSFC of turbocharged engine were increased than those of natural aspiration engine by about 48%, 46% and 5%, respectively . The components in exhaust gas except NOx from turbocharger engine were less than the amount set up for 2000-year regulation.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 2013년도 추계학술대회
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• pp.67-70
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• 2013

본 논문에서는 HEVC(high efficiency video coding)의 후처리 필터 중 하나인 적응적 샘플 오프셋(sample adaptive offset, SAO) 기술을 고속화 하는 방법을 제안한다. 기존의 SAO 는 원 영상과 복원된 영상간의 오차를 최소화하기 위해 각 블록마다 오프셋 값을 계산하므로 연산 복잡도가 매우 높다. 따라서 제안한 방법에서는 다양한 입력 영상에 대한 오프셋 사용빈도를 알아보고, 그 통계를 기반으로 불필요한 오프셋 연산을 생략한다.

• 한국콘텐츠학회논문지
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• 제4권1호
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• pp.67-75
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• 2004

본 논문은 공개키 기반구조(PKI-Public Key Infrastructure)에서 중추적인 역할을 담당하는 공개키 인증시스템을 설계하고 구현한다. 본 논문에서는 인증기관의 역할을 수행할 수 있는 공개키 인증시스템의 요구사항 및 특징을 분석하여, 실제 인증 서비스가 제공 가능한 인증과정은 HA및 FA한테 위임하고 설계한다. 인증 구조는 Root CA와 Home agent 및 Foreign agent로 구성되어 있고, 필요할 때 CA은 위임권을 HA나 FA한테 전송한다.