• 한국분무공학회지
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• 제27권2호
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• pp.101-108
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• 2022

Performance and emissions with different diesel injection methods were analyzed in a natural gas-diesel, dual-fuel engine under low-load conditions. Natural gas was supplied to intake port during the intake stoke to form a natural gas-air premixed mixture for all methods. Diesel was injected directly into the cylinder during the compression stroke in three ways: early injections, late injections, and a combination of early and late injections. The early injections had the highest thermal efficiency among the three methods owing to its highest combustion efficiency. The wide dispersion of diesel before the combustion initiation also allowed superior emissions characteristics.

• 한국자동차공학회논문집
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• 제22권3호
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• pp.210-219
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• 2014

The MPI dual injection engine can enhance the fuel efficiency and engine power. By using one injector per one intake port, MPI dual injection engine has an excellent fuel atomization and targeting injection. As the basic research for the MPI Dual injection engine design, this research was investigated in order to understand the characteristic of the in-cylinder flow and fuel behavior according to engine temperature condition and the fuel type in the MPI dual injection engines. The 3D unsteady CFD simulation for the MPI Dual injection engine was performed using STAR-CD. The engine operating condition was 2,000 rpm/WOT. The parameters for this study were fuel types, fuel temperatures and wall temperatures. As a result, the intake air amount, evaporated fuel in the cylinder and the fuel film on the wall were presented according to parameters that depend on the fuel properties and engine wall temperature. Also, the results were influenced by in-cylinder flow such as the intake flow, back flow and so on.

• International Journal of Automotive Technology
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• 제5권1호
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• pp.9-16
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• 2004

An experimental study was carried out to characterize the spray atomization process of micro-machined port fuel injectors with a piezoelectric atomization device, which can generate pressure pulsations through vibration of a piezoelectric transducer. In this study, several types of micro-machined arrays such as 30∼200-microns of hole arrays were tested. Both a dual-stream and a central-port injectors with micro-machined arrays were tested and compared with normal port fuel injectors. The spray visualization was conducted to characterize overall spray structure and phase Doppler particle analyzer (PDPA) system was used to quantify the droplet size and velocity. In addition, the pressure history was recorded by using digitized signal from pressure transducer. The results showed that modulation is effective to the spray atomization for tested injectors and atomization performance depends on injector design factors, orifice sizes, and frequency and power of the modulator. A number of resonance frequencies of the modulator was modified by injector parameters and temperature. In addition, our results suggested that design of sufficient space among holes is critical to avoid droplet coalescence in the multi-hole micro-machined injectors.

• 한국항만학회지
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• 제11권2호
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• pp.273-280
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• 1997

Recently the importance of the cargo handling equipments in a port has been increasing to get strong competition from other ports. Many ports are making efforts to modernize their cargo handling equipments. The kernel technology of such equipments is the speed control of DC motor which is used as an essential part of them. In this paper, we discuss the speed control of a DC motor as a basic work for building cargo handling equipments in a port. DC Motors are still widely used in industrial fields, as driving power motor for electrical fields. DC drives, being easy to control, are widely used in many variable-speed and position control drive system. Traditional analog control circuits used in such applications have many disadvantages. Complex control schemes are difficult to implement with analog components. All these factor and invention of the microprocessor has made it possible to use digital control circuits, using microprocessing system. These digital circuits have been found to be reliable, flexible, and also immune to noise. In this paper it presents the speed control of a SCR DC motor driver which using dual converter by 80c196kc microprocessor. We developed a thyristor power amplifier which does not cause damage thyristor because it is designed to prevent triggering the two SCRs in the same arm simultaneously. And it was analyzed voltage and currents wave at reactive load.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2007년도 추계학술대회 및 제23회 정기총회
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• pp.216-218
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• 2007

세계 선진항만은 해운물류시장의 변화에 대응하고, 경쟁력 확보 방안으로 첨단 자동화 장비와 운영시스템 도입을 통한 자동화를 지향하고 있다. 국내 부산항 신항 또한 자동화 컨테이너터미널로 개발을 추진하고 있는 것으로 알려져 있다. 자동화 터미널은 각종 자동화 장비와 시스템이 유기적으로 구성되어 있으며, 이들의 효율적인 운영을 통해 생산성을 향상시킬 수 있다. 터미널의 안벽과 장치장 사이의 컨테이너 운송을 담당하는 이송장비는 컨테이너터미널의 핵심장비로 이의 효율적인 운영은 컨테이너터미널의 생산성과 직결되어 있다. 본 연구에서는 자동화 컨테이너터미널의 운영생산성 향상을 위한 하역장비와 이송장비의 운영방안에 대하여 연구한다. 특히 DHST(Dual Hoist Second Trolley)타입의 QC와 ASHC의 장비특성과 장비간의 연계작업을 고려하여, QC의 대기시간을 최소화하여 하역 생산성을 최대화할 수 있는 ASHC Dispatching Rule을 제시하고자 한다.

• Management Science and Financial Engineering
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• 제5권1호
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• pp.1-25
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• 1999

There is a worldwide trend to automate the handling operations in port container terminals in an effort to improve productivity and reduce labor cost. This study iscusses how to apply an AGV(automated guided vehicle) system to the handling of containers in the yard of a port container ter-minal. The main issue of this paper is how to assign tasks of container delivery to AGVs during ship operations in an automated port container terminal. A dual-cycle operation is assumed in which the loading and the discharging operation can be performed alternately. Mixed integer linear program-ming formulations are suggested for the dispatching problem. The completion time of all the dis-charging and loading operations by a quayside crane is minimized, and the minimization of the total travel time of AGVs is also considered as a secondary objective. A heuristic method using useful properties of the dispatching problem is suggested to reduce the computational time. The perfor-mance of the heuristic algorithm is evaluated in light of solution quality and computation time.

• 전기의세계
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• 제36권3호
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• pp.190-204
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• 1987

본고에서는 이중입출력 메모리(Dual-Port RAM)를 이용한 영상 입력장치(Image Memory)의 설계 및 그 제어 신호 발생기에 대하여 논하였다. 이중 입출력 메모리 소자인 TMS4161은 기존의 표준 64K x 1DRAM Port와 256bit의 내부적 Shift REgister와 연결된 Serial Port가 있어서, 실시간 영상 처리 및 그래픽 용으로 사용하기에 적합하나, 그 사용에 있어서 가장 어려운 문제로 제안된 주소 신호 발생기 및 요구중재기에 대한 해결 방안을 제시하였다. 또한 서로 독립적인 두개의 입출력 장치가 있다는 장점을 이용하여 하드웨어에 의한 실시간 처리도 가능한 구조로 쉽게 확장할 수 있어서 소프트웨어에 의한 실시간 처리로 가능하리라 사료된다. 앞으로는 512x512x8의 영상 메모리 구조 뿐만 아니라 1024x1024x8의 영상메모리 구조에 대하여 더욱 연구할 필요가 있다고 본다.

• 한국통신학회논문지
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• 제19권6호
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• pp.1046-1055
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• 1994

본 논문에서는 영상 신호처리에 적합한 고속 1 line VRAM을 ASIC화 설계하기 위하여 엑세스 시간특성 및 집적도가 우수한 3-TR dual-port 다이나믹 셀을 채용하여 메모리 코어를 설계하였다. 고속 파이프라인 동작을 위하여 서브어레이 1로부터 첫 행을 분리하였고, TM기 비트 라인에 데이터 래치 구조를 채용하여 한 번지의 동시 입.출력이 가능하도록 설계하였다. 주변 회로로 번지 선택기, 1/2V 전압 발생기를 각각 설계하여 개선된 동작특성을 확인한 후 1.5[ m] CMOS 설계규칙을 이용하여 ASIC화 설계하였다.

• 제어로봇시스템학회논문지
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• 제5권6호
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• pp.691-697
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• 1999

This paper describes the implementation of a high speed image processing board. This image processing board is consist of a image acquisition part and a image processing part. The image acquistion part is digitizing the image input data from CIS and save it to the dual port RAM. By putting on the dual port memory between two parts, during acquistion of image, the image processing part can be effectively processing of large-volume image data. Most of all image preprocessing part are integrated in a large-scaled FPGA. We arwe using ADSP-2181 of the Analog Device Inc., LTD. for a image processing part, and using the available all memory of DSP for the large-volume image data. Especially, using of IDMA exchanges the data with the external microprocessor or the external PC, and can watch the result of image processing and acquired image. Finally, we show that an implemented image processing board used for the simulation of image retreval by the one of the typical application.

• 융합보안논문지
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• 제8권2호
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• pp.71-78
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• 2008

이 연구는 인터넷 망과 조직이 자체보안을 위해 별도로 구축한 내부 망을 하나의 망으로 합쳐서 통합 체계를 구축하여 경제적이며 안전하게 인터넷과 내부 응용 서비스를 사용하는 방안을 제시하고자 한다. 기존에 일부에서 사용되고 있는 망 전환 장치는 기계적인 한계가 있으며 인터넷과 내부 망을 위한 별도의 네트워크를 구성해야 하는 문제점 때문에 연동성과 보안의 목표인 인증 및 암호화에 대한 대책이 부족하고 체계 구축 시 많은 비용이 소요되는 단점이 있다. 이에 ATM Forum 역 다중화 기술과 IPSec을 적용하여 네트워크 성능을 향상하고 구축비용을 절감하며 신뢰성 있는 이중 방어 체계의 구축 방안을 제안하고자 한다. 아울러 망 관리 기술을 이용한 Scanning 공격 기술과 SNMP, Spooler Port 등의 취약점을 집중 분석한 후 본 논문에서 제안한 이중 방어 체계 기반의 대응 방안을 제시하였다.