• 동력기계공학회지
• /
• 제10권1호
• /
• pp.12-18
• /
• 2006

A three-degree of freedom model of intake system was contrived and investigated in various ways for the purpose of the amelioration of the volumetric efficiency in a low and transient engine speed for a multi cylinder diesel engine. The basic concept beyond this model started from the theory that each degree of freedom model has volumetric efficiency peak as many as its number of the degree of freedom. The volumetric efficiency affects significantly to the engine performance; torque characteristics, fuel economy and emission level. For commercial vehicles and stationary engines, the engine is designed so as to produce their best performance near the normal engine speeds, thus the low engine speed area has a tendency of poor volumetric efficiency. The aim of this study was highlighted on the amelioration of volumetric efficiency of low engine speed area in a multi cylinder diesel engine matched with an additional Helmholtz resonator. By the use of VIS(variable induction system) volumetric efficiency at low engine speed range was significantly improved. The availability of control by combination of VIS and CIS(conventional induction system) will be proposed as a variable induction system that would be an appropriate model for amelioration of the volumetric efficiency at low engine speed.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2006년도 제37회 하계학술대회 논문집 D
• /
• pp.2163-2164
• /
• 2006

It is desirable to monitor the vital signals, such as ECG, of a emergency patient during transfer in the hospital as well as in the ambulance. The purpose of this study is to develop a system which provides a real-time and wireless ECG to the medical staff nearby patient during transfer in hospital. In this context, we developed a low-power, low-cost and portable ECG system consisting of 1) ECG measurement and RF transmission module and 2) RF receiving and LCD display module. The developed system is expected to be useful in monitoring ECG of a patient during transfer in the hospital.

• JSTS:Journal of Semiconductor Technology and Science
• /
• 제14권1호
• /
• pp.70-82
• /
• 2014

A nano-power CMOS voltage reference is proposed in this paper. Through a combination of switched-capacitor technology with the body effect in MOSFETs, the output voltage is defined as the difference between two gate-source voltages using only a single PMOS transistor operated in the subthreshold region, which has low sensitivity to the temperature and supply voltage. A low output, which breaks the threshold restriction, is produced without any subdivision of the components, and flexible trimming capability can be achieved with a composite transistor, such that the chip area is saved. The chip is implemented in $0.18{\mu}m$ standard CMOS technology. Measurements show that the output voltage is approximately 123.3 mV, the temperature coefficient is $17.6ppm/^{\circ}C$, and the line sensitivity is 0.15 %/V. When the supply voltage is 1 V, the supply current is less than 90 nA at room temperature. The area occupation is approximately $0.03mm^2$.

• 중소기업융합학회논문지
• /
• 제1권1호
• /
• pp.55-65
• /
• 2011

모바일 통신, 센서 네트워크, 웨어러블 컴퓨터 등 IT 응용기술 분야의 급속한 발전으로 인하여 매우 다양한 영역에서 임베디드 소프트웨어의 요구가 증가하고 있다. 이러한 다양한 응용영역에서 저전력을 소모하는 임베디드 소프트웨어의 개발은 배터리를 이용한 전원공급 시스템으로 인하여 매우 중요하게 여겨지고 있다. 따라서 본 논문에서는 임베디드 소프트웨어의 개발 과정에서 소모전력 특성을 고려하는 소프트웨어 개발 기법에 대하여 제안한다. 일반적으로 소프트웨어의 소모전력은 코드 기반 분석을 통해 절감할 수 있지만, 이 경우는 소프트웨어를 다시 개발할 수도 있는 문제점을 가지고 있다. 따라서 저전력 소모에 대한 요구사항을 기반으로 소프트웨어 개발 과정에서 소모전력을 감소시켜야 하는 방법이 필요하다. 제안하는 소모전력 절감을 위한 임베디드 소프트웨어 개발 프로세스는 다양한 응용분야에서 활용되는 모바일 시스템의 개발에 활용하여 소모전력 측면에서의 경쟁력있는 소프트웨어의 개발이 가능하게 할 것으로 판단된다.

• 한국군사과학기술학회지
• /
• 제17권4호
• /
• pp.485-491
• /
• 2014

An Antenna & RF system for a fly-away satcom terminal application on ka-band is presented in this paper. The Fly-away satellite terminal can be moved and operated by two person and adapt automatic satellite tracking system in order to decrease the tracking time. Additionally, for low-power consumption, compact size and light-weight, a dual reflector antenna is constructed using dual-offset gregorian antenna structure. For minimize weight, the reflector of the antenna is made of Magnesium. For low-power consumption and light-weight, the pHEMT MMIC compound devices is utilized. The Electronic Band-Gap(EBG) Low-Pass Filter(LPF) is designed for harmonic rejection. In the receiving part, Low-Noise Block converter(LNB) structure is designed for compact and lightweight. In this paper, fly-away satcom terminal with low-power consumption, compact size and light-weight is described with antenna system and RF system performances. Through the experimentation, fly-away terminal's EIRP is more than 50dBW, G/T is more than $17dB/^{\circ}K$.

• 동력기계공학회지
• /
• 제14권5호
• /
• pp.63-70
• /
• 2010

Recently the power window system is widely used in automobiles to increase convenience of passengers and drivers. However some accidents or injuries have been caused by malfunction or misusage of the system. Therefore safety regulations of the system to cope up with these accidents have been strengthened gradually in many countries. Especially in America, since 2005, all vehicles which had power window system should be contented with FMVSS 118-S5 regulations. We suggest very low-cost anti-pinch window control system satisfying the regulation in this paper. Hall sensors are used and installed around a motor rotor with ring magnet to detect motor speed for anti-pinch. The optimum number of hall sensor and location angel of them are mainly investigated to get sufficient speed resolution for anti-pinch. Through some experiments, the validity of the suggested system was verified to satisfy the regulation.

• 전기의세계
• /
• 제27권5호
• /
• pp.5-12
• /
• 1978

1.Power utilities and CRIEPI are very active in almost all aspects of power systems research. 2.About 50% of research activity of CRIEPI is made under the joint work with power utilities. 3.Research motivation of manufactures are mainly stimulated by the need of power utilities and manufacturers are closely collaborating with power utilities. 4.Main effort of universities is concentrated upon the theoretical aspects of network analysis and the means of stability improvement. Univer sities are doing research rather independently of industry unless inexceptional cases. 5.Universities are making a significant contribution to the exploration of new horizon of power systems engineering, namely, in the research on the social impact on the future of power system. 6.Current main interest of power systems reserch is centered around the stability problem and power system operation and control. Research activity in power system planning is rather low as compared to that in these two major fields. A similar statement holds for the analysis of electromagnetic transients and short circuit analysis. However a new research field is sprouting in the area of power system protection.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2016년도 전력전자학술대회 논문집
• /
• pp.40-41
• /
• 2016

The inverter resistance welder requires AC/DC converter of high efficiency because the converter changes a commercial ac power source to low voltage dc power source. Harmonic components that occur in the conversion process of converter decrease system power factor and deal great damage in electric power system. To improve such problems, this paper proposes a high efficiency AC/DC converter for inverter resistance welder. The switching devices in the proposed converter are operated by soft switching technique using a new quasi-resonant circuit. As a result, the proposed AC/DC converter obtains low switching power loss and high efficiency.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2004년도 하계학술대회 논문집 D
• /
• pp.2310-2312
• /
• 2004

In Korea Electric Power Corporation (or KEPCO), several Demand-Side Management (or DSM) program have been carried out to effectively meet electric power demand at least costs by modifying customers electricity use patterns. As one of them, KEPCO applies low-priced night thermal-storage power service for heat appliances to facilitate efficient use of power facilities by shifting relatively high daytime demands to night hours to build loads during the off-peak periods. In the market of heat-storage type water-heater, electric water-heater has been mostly used, but it has low energy efficiency and needs high capacity electric equipments. So in order to replace these electric water heaters, 15 HP air-source heat pump water heater is developed in Korea Electric Research Institute (or KEPRI). This paper shows that measurement system for performance testing of heat pump water heater is established and heating capacity and performance is analyzed and measured for out-door environmental change.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2006년도 추계학술대회 특별세미나 특별세션
• /
• pp.209-218
• /
• 2006

This paper presents the comparison and analysis of the power supply system of a Maglev train and conventional electric railway. Even though all Maglev trains have batteries on their vehicles, electric power supply from the ground side is necessary for levitation, propulsion, on-board electrical equipment, battery recharging, and so on. At low speeds up to $100{\sim}150(km/h)$, the Maglev train, generally, uses a mechanical contact, a current collector as same as conventional electric railway. However, at high speeds, the Maglev train can no longer obtain power from the ground side by using a mechanical contact. Therefore, high speed Maglev trains use their own way to deliver the power to the vehicle from the ground. In this paper, the power supply systems of the german, japanese, and korean low- and high-speed Maglev trains have been reviewed.