• 항공우주시스템공학회지
• /
• 제6권4호
• /
• pp.7-11
• /
• 2012

Recently, the renewable energy has been widely used as a wind energy and solar energy resource due to lack and environmental issues of the mostly used fossil fuel. In this situation, the interest in wind power has been risen as an important energy source. For this blade a high efficiency wind turbine blade was designed with the proposing aerodynamic design procedure, and a light and low cost composite structure blade was designed considering fatigue life. Structural analyses including load case study, stress, deformation, buckling, fatigue life and vibration analysis were performed using the Finite Element Method.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2007년도 추계학술대회 논문집
• /
• pp.1668-1673
• /
• 2007

In light of the growing traffic congestion problem and congestion cost, the container transport by railway has to be increased. The freight transport by railway can have decided advantages over trucks in terms of energy efficiency, emissions and cost for certain freight movements, just as transportation in the metropolitan region can have great advantages over driving truck. But the freight transport by truck should gain significant mobility benefits from a freight railway system. Thus, the DMT(Dual Mode Trailer) transport system which is coupled railway transport advantages with load transport advantages has been developed and used in the european countries. The DMT transport will therefore serve the areas required by transport organizers. This paper describes the various DMT transport systems and its strength and weakness.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2008년도 추계학술대회B
• /
• pp.2126-2130
• /
• 2008

Gasoline engine have proved its utility in light, medium and heavy duty vehicle in every sector of the world community. The concern about long term availability of petroleum and the increasing threat for the environment by the increasing load of vehicular emission, compel the technology to upgrade itself for meeting the challenges. CNG is environmentally clean alternative to the existing SI Engines with out much change in the hardware. Many researchers have found this as a potential substitute to meet the energy requirement. Higher octane number and higher self ignition temperature make it a good gaseous fuel. Although power output is slightly lesser than the gasoline it's thermal efficiency is better than the gasoline for the same SI Engine. Results showed that reduced CO, hydrocarbon emissions is a favorable outcome, with slight increase in $NO_x$ emission when compared with gasoline fuel to dual fuel mode in the existing SI Engines.

• 한국환경보건학회지
• /
• 제34권6호
• /
• pp.423-432
• /
• 2008

In this study, we investigated the possibility of auto control and the proper operating factors in the BNR(Biological Nutrient Removal) process using an NADH(Reduced Nicotinamide Adenine Dinucleotide) fluorometer, which characterized the emitted fluorescence when activated by flashes of UV light at 460 nm. In terms of finding adequate operating parameters, results indicted that nitrification efficiency decreased in the controlled DO while denitrification efficiency decreased in the controlled pH. The above results indicated that controlled operating condition after combination with NADH, DO and pH was resonable. Result obtained from the correlation between NADH and pH showed that variation trend of influent loading was similar to those of NADH and pH, and also the variation cycle was repeated on a daily basis. Consequently, this result showed the increase of BOD loading caused the nitrification efficiency to decrease because air-flow, required for nitrification, was reduced, and so the NADH value was increased. From these results, it is possible to use NADH flourimetry to assess the variation of organic load and nitrification efficiency in the case of small change in influent pH such as in sewage and also to handle and operate the load variation in the auto control system using the NADH fluorometer.

• 전기전자학회논문지
• /
• 제23권3호
• /
• pp.1104-1107
• /
• 2019

본 논문에서는 데드 타임을 줄여 전력 효율을 높이기 위해 데드 타임 제어기를 이용한 웨어러블 AMOLED 디스플레이용 DC-DC 부스트 변환기를 제안한다. 또한, 본 변환기에서는 경부하에서 전력 효율을 높이고 출력 전압 리플을 감소시키기 위해 PWM-SPWM (set-time variable pulse width modulation) 듀얼 모드를 이용한다. 제안하는 회로는 $0.18{\mu}m$ BCDMOS 공정을 이용하여 시뮬레이션을 한 결과 1 mA~70 mA의 부하 전류 범위에서 39%~96%의 전력 효율과 2 mV의 리플 전압을 가졌다. 본 회로의 전력 효율은 PWM-SPWM 방식보다 최대 2% 상승하였고, PWM 방식보다 최대 8% 상승하였다.

• Journal of Power Electronics
• /
• 제11권2호
• /
• pp.188-193
• /
• 2011

A highly efficient AC-DC converter for small wind power generation systems using a brushless DC generator (BLDCG) is presented in this paper. The market standard AC-DC converter for a BLDCG consists of a three-phase diode rectifier and a boost DC-DC converter, which has an IGBT and a fast recovery diode (FRD). This kind of two-stage solution basically suffers from a large amount of conduction loss and the efficiency greatly decreases under a light load, or at a low current, because of the switching devices with a P-N junction. In order to overcome this low efficiency, especially at a low current, a three-phase bridgcless converter consisting of three upper side FRDs and three lower side Super Junction FETs is presented. In the overall operating speed region, including the cut-in speed, the efficiency of the proposed converter is improved by up to 99%. Such a remarkable result is validated and compared with conventional solutions by calculating the power loss based on I-V curves and the switching loss data of the adopted commercial switches and the current waveforms obtained through PSIM simulations.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2011년도 전력전자학술대회
• /
• pp.179-180
• /
• 2011

This paper focuses on the Current-Voltage concurrent control method devoted to the multiple LED (light-emitting diode) string driver. Isolated DC to DC converter with cascaded chopping switch is proposed for smart lighting system such as light with sensor or back light unit of display, which need to control the current of parallel connected multiple LED stings and regulate DC voltage for micro controller for brightness control. The proposed circuit regulates the current of parallel connected multiple LED strings and additional DC voltage output simultaneously. To verify the performance, experimental results are presented based on the prototype board. 5V, 1A voltage mode electric load and two LED strings with different forward voltages are used for output loads. 23W output power is achieved and measured efficiency is in the range of 85%-87%

• 자동차안전학회지
• /
• 제12권2호
• /
• pp.7-13
• /
• 2020

Recently, there is a big issue of downsizing on brake system according to fuel efficiency and regenerative braking cooperation control. Especially, small cars have improved in a variety ways such as electric vehicle and smart car compared to previous small cars. So, small brake system is strongly required in the car industry. A new small brake system for light compact vehicles was proposed in this paper. For this system, the solid type disc and caliper were newly developed. And the important design factors were considered to reduce brake size. First, we calculated the temperature rise of disc through heat capacity formula and CAE analysis. Second, we analyzed the housing and carrier stiffness of caliper to select the reasonable condition. Finally, the superiorities of the developed brake system were verified by heat capacity, consumption liquid level, braking feeling, judder, wear test and regenerative braking cooperation control analysis. A developed brake system is expected to be useful for brake system of light compact platform.

• 스마트미디어저널
• /
• 제7권2호
• /
• pp.71-77
• /
• 2018

본 논문에서는 신재생에너지 발전과 연계한 에너지저장시스템(ESS)의 최적 운영을 위한 에너지관리시스템(EMS)의 구성요소 설계 시 고려할 기능, 운영 효과 분석과 전력요금 절감 방안을 제안한다. 이를 위해 태양광 발전 시스템에 리튬이온전지 기반의 배터리 시스템과 에너지관리시스템 연계 및 구축방안을 제시하고, 1년 동안 운영 데이터에 대한 분석한 결과를 기술한다. 또한 시스템 운영 효과를 높이기 위한 방안으로 EMS를 이용하여 최대수요 발생시간대의 피크전력을 경부하 시간대 충전전력으로 대체하여 ESS 전용 요금제에 따른 요금편익과 부하 평준화에 기여하는 효과를 제안한다.

• 한국산학기술학회논문지
• /
• 제20권1호
• /
• pp.384-390
• /
• 2019

친환경 저에너지 중점의 건축설계의 중요성이 점점 커져가고 있다. 또 한편으로는 좀 더 미시적인 관점의 에너지 절약 설계 기법이 요구되고 있다. 이러한 분위기 속에서 에너지 시뮬레이션의 필요성이 점차 증가하고 있으며, 특히 BIM 기반의 에너지 시뮬레이션은 높은 효율성으로 인해 주목받고 있다. 하지만 BIM의 데이터는 아직까지는 미시적인 에너지와 관련된 파라메터가 적용되어 있지 않다. 따라서 본 연구는 조도 센서에 의한 조명 제어 시뮬레이션을 통해 센서 조명 파라메터의 생성 필요성에 대해서 연구하고자 한다. 연구는 BIM을 통해 생성된 데이터를 바탕으로 조도 센서를 설치하고 조도 시뮬레이션을 통해 센서등의 스케줄 데이터를 생성하였다. 그리고 이렇게 생성된 스케줄 데이터를 바탕으로 에너지 시뮬레이션을 실시하여 소비전력의 감소율을 확인하였다. 연구에 따르면 조명에 따른 열부하량과 소비전력량이 각각 20%이상 감소하는 것으로 나타났다. 따라서 센서 조명 파라메터는 미시적인 에너지 절약 설계를 위해서 BIM 데이터 내에 생성될 필요가 있다고 판단된다. 본 연구는 센서 조명 파라메터의 생성에 국한된 것이 아니라, 이와 같이 미시적인 변인들을 검토하고 BIM 데이터 내에 적용할 필요가 있음을 밝히기 위해 수행되었다.