무선랜에서의 협동 상향하향 링크 기회적 스케쥴링 기법

Thesis(doctors) --서울대학교 대학원 :전기. 컴퓨터공학부, 2009.2.Docto

지우기 행위를 바탕으로 한 회화제작연구 : 본인의 작품을 중심으로

학위논문(석사)--서울대학교 대학원 :서양화과 서양화전공,2004.Maste

Combustion Characteristics elan Optical Single Cylinder DI Diesel Entwine Equipped with a Common-Rail Injection System

An optical single cylinder diesel engine equipped with a common-rail injection system has been built to investigate diesel combustion and emission characteristics. Three optical widows (piston crown quartz for bottom view of the cylinders upper piston quartz for allowing laser sheet and liner quartz for side view) hale bean placed in the optical engine to visualize spray Characteristics and combustion process inside the cylinder. Before doing further research using various optical diagnostics with the optical engine, fundamental combustion experiments have been carried out with a wide range of engine operating conditions. The engine proved satisfactory, proper motoring in-cylinder pressure, allowable low cycle by cycle variation during combustion, similar trend with previously published results for various engine operating conditions. The research with the optical engine will, therefore, be extended further with variety of optical and laser diagnostics

Dimethyl Ether와 디젤의 분무 특성 비교

Dimethyl ether(DME) is one of the most attractive alternative fuel for compression ignition engine. Its main advantage in diesel engine application is high efficiency of diesel cycle with soot free combustion though conventional fuel injection system has to be modified due to the intrinsic properties of DME. Experimental study of DME and conventional diesel spray employing a common-rail type fuel injection system with a 5-holes sac type injector(hole diameter 0.168 mm/hole)was performed in a high pressure chamber pressurized with nitrogen gas. A CCD camera was employed to capture time series of spray images followed by spray cone angles and penetrations of DME were characterized and compared with those of diesel. Under atmospheric pressure condition, regardless of injection pressure, spray cone angles of the DME were wider than those of diesel and penetrations were shorter due to flash boiling effect. Tip of the DME spray was formed in mushroom like shape at atmospheric chamber pressure but it was disappeared in higher chamber pressure. On the contrary, spray characteristics of the DME became similar to that of diesel under 3Mpa of chamber pressure. Hole-to-hole variation of the DME spray was lower than that of diesel in both atmospheric and 3Mpa chamber pressures. At 25Mpa and 40Mpa of DME injection pressures, regardless of chamber pressure, intermittent DME spray was observed. It was thought that vapor lock inside the injector was generated under the two injection pressures

상호 연결된 대규모선형 시스템의 비집중 적응 안정화에 관한 연구

학위논문(박사) - 한국과학기술원 : 전기 및 전자공학과, 1984.8, [ v, 125 p. ]In this dissertation, a problem of stabilizing large scale interconnected linear systems when the system parameters are uncertain is considered. A method to design a local adaptive control so that the resultant closed-loop system is assured to be globally stable is developed for both continuous-time and discrete-time systems. The proposed local adaptive controls are a combination of a new adaptive feedback control for compensation of some effects by unknown system parameters and the conventional exact model-based linear feedback control for overriding the unfavorable effects by interconnections. Based on the present decentralized adaptive method, it is shown that a class of large scale systems formed by interconnecting a number of multi-input linear systems can be stabilized via local state feedback. Both the continuous-time case and the discrete-time case are treated. It is further shown that an interconnected system composed of a number of single-input single-output linear systems can be stabilized using only input and output measurements. Both the continuous-time case and the discrete-time case are treated.한국과학기술원 : 전기 및 전자공학과

Comparison of Macroscopic Spray Characteristics of Dimethyl Ether with Diesel

Dimethyl ether (DM) is one of the most attractive alternative fuel far compression ignition engine. Its main advantage in diesel engine application is high efficiency of diesel cycle with soot free combustion though conventional fuel injection system has to be modified due to the intrinsic properties of DME. Experimental study of DME and conventional diesel spray employing a common-rail type fuel injection system with a 5-holes sac type injector (hole diameter 0.168 ㎜/hole) was performed in a high pressure chamber pressurized with nitrogen gas. A CCD camera was employed to capture time series of spray images followed by spray cone angles and penetrations of DME were characterized and compared with those of diesel. Under atmospheric pressure condition, regardless of injection pressure, spray cone angles of the DME were wider than those of diesel and penetrations were shorter due to flash boiling effect. Tip of the DME spray was farmed in mushroom like shape at atmospheric chamber pressure but it was disappeared in higher chamber pressure. On the contrary, spray characteristics of the DME became similar to that of diesel under 3MPa of chamber pressure. Hole-to-hole variation of the DME spray was lower than that of diesel in both atmospheric and 3MPa chamber pressures. At 25MPa and 40MPa of DME injection pressures, regardless of chamber pressure, intermittent DME spray was observed. It was thought that vapor lock inside the injector was generated under the two injection pressures