• 한국수소및신에너지학회논문집
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• 제28권1호
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• pp.56-62
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• 2017

Although most electricity production contributes to air pollution, the vehicle organizations and environmental agency categorizes all EVs as zero-emission vehicles because they produce no direct exhaust or emissions. Currently available EVs have a shorter range per charge than most conventional vehicles have per tank of gas. EVs manufacturers typically target a range of 160 km over on a fully charged battery. The energy efficiency and driving range of EVs varies substantially based on driving conditions and driving habits. Extreme outside temperatures tend to reduce range, because more energy must be used to heat or cool the cabin. High driving speeds reduce range because of the energy required to overcome increased drag. Compared with gradual acceleration, rapid acceleration reduces range. Additional devices significant inclines also reduces range. Based on these driving modes and climate conditions, this paper discusses the performance characteristics of EVs on energy efficiency and driving range. Test vehicles were divided by low / high-speed EVs. The difference of test vehicles are on the vehicle speed and size. Low-speed EVs is a denomination for battery EVs that are legally limited to roads with posted speed limits as high as 72 km/h depending on the particular laws, usually are built to have a top speed of 60 km/h, and have a maximum loaded weight of 1,400 kg. Each vehicle test was performed according to the driving modes and test temperature ($-25^{\circ}C{\sim}35^{\circ}C$). It has a great influence on fuel efficiency amd driving distance according to test temperature conditions.

• 한국재료학회지
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• 제32권7호
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• pp.320-325
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• 2022

Single OLED and tandem OLED was manufactured to analyze the electroluminescence characteristics of DC driving, AC driving, and full-wave rectification driving. The threshold voltage of OLED was the highest in DC driving, and the lowest in full-wave rectification driving due to an improvement of current injection characteristics. The luminance at a driving voltage lower than 10.5 V (8,534 cd/m²) of single OLED and 20 V (7,377 cd/m²) of a tandem OLED showed that the full-wave rectification drive is higher than that of DC drive. The luminous efficiency of OLED is higher in full-wave rectification driving than in DC driving at low voltage, but decrease at high voltage. The full-wave rectification power source may obtain higher current density, higher luminance, and higher current efficiency than the AC power source. In addition, it was confirmed that the characteristics of AC driving and full-wave rectification driving can be predicted from DC driving characteristics by comparing the measured values and calculated values of AC driving and full-wave rectification driving emission characteristics. From the above results, it can be seen that OLED lighting with improved electroluminescence characteristics compared to DC driving is possible using full-wave rectification driving and tandem OLED.

• 한국자동차공학회논문집
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• 제24권6호
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• pp.635-641
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• 2016

Regenerative braking performance of an electrically powered vehicle is closely related to driving distance per battery charge. An electric vehicle uses appropriate amounts of mechanical braking force and electromagnetic regenerative braking force to recover energy and increase driving efficiency. In particular, when it drives on a downhill road, energy recovery rate is maximized through regenerative braking during coasting based on the mass inertia of the vehicle. Since an electric two-wheeled vehicle covered in this paper is lighter than an electric four-wheeled vehicle, the improvement of its driving distance per battery charge through regenerative braking is different from an electric four-wheeled vehicle. This study compared the driving characteristics of an electric two-wheeled vehicle based on regenerative braking. Two driving test modes were simulated with a chassis dynamometer system. By analyzing the measurement of a chassis dynamometer, the driving characteristics of a two-wheel electric vehicle, such as driving efficiency, were analyzed. In addition, test results were reviewed to draw the limitations of conventional test methods for regenerative braking performance of an electric two-wheel vehicle.

• 한국기후변화학회지
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• 제7권1호
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• pp.85-93
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• 2016

This study the efficiency of greenhouse gas reduction of 'low carbon car collaboration fund' and its alternative 'control of average fuel efficiency and greenhouse gas', and 'improving driving behavior' were analyzed by using LEAP, long term energy analysis model. Total 4 scenarios were set, baseline scenario, without energy-saving activity, 'low carbon car collaboration fund' scenario, 'fuel efficiency improving scenario', and 'improving driving behavior' scenario. The contents of analysis were forecast of energy demand by scenario and application as well as reduction of greenhouse gas emission volume, and the period taken for analysis was every 1 year during 2015~2030. Baseline scenario, greenhouse gas emission volume in 2015 would be 7,935,697 M/T and 13,081,986 M/T in 2030, increased 64.8%. The analysis result was average annual increase rate of 3.4%. The expected average annual increase rate of other scenarios was, 'low carbon car collaboration fund' scenario 1.7%, 'fuel efficiency improving' scenario 3.0%. and 'improving driving behavior' scenario 3.4%. and these were each 1.7%, 0.3%. 0.3% reduce from baseline scenario. The largest reduction was 'low carbon car collaboration fund' scenario, and there after were 'fuel efficiency improving scenario', and 'improving driving behavior' scenario.

• Journal of Information Display
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• 제5권1호
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• pp.16-21
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• 2004

The effects of an auxiliary address pulse driving scheme, in which an auxiliary short pulse is applied to the address electrode during a sustain-period, were examined under the various image patterns of the 42-inch WVGA ac-PDP. When the auxiliary address pulse driving scheme was applied, the luminance of the red, green and blue cells were measured respectively. And the luminance, luminous efficiency, and current were measured under the full-white pattern of the 42-inch ac-PDP. As a result, the luminance of blue cells was improved approximately by 17 %, whereas the luminous efficiency of the full-white pattern was improved approximately by 34 % without a misfiring discharge in comparison with conventional driving scheme.

• 한국융합학회논문지
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• 제9권4호
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• pp.1-7
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• 2018

전기자동차용 전동기는 운전모드에 따라 효율특성이 차이가 나기 때문에 저속 및 고속의 운전모드에서 고효율특성을 평가하기 위한 연구는 매우 중요하다. 따라서 전기자동차 구동용 전동기의 고토크 및 고출력 밀도, 고효율특성을 변경할 수 있는 설계 방안이 필요하다. 본 논문에서는 매입형 영구자석 동기전동기의 고정자와 회전자의 직경비를 각각 0.62, 0.65, 0.68로 변경 설계하여 전 운전구간의 효율특성과 시내 및 고속도로 운전모드에서의 평균효율특성을 분석하였다. 전 운전구간의 효율특성을 분석한 결과, 직경비가 증가할수록 고효율 구간이 저속 저토크 구간으로 이동하고, 직경비가 감소할수록 고효율 구간이 고속 저토크 부근으로 이동함을 확인하였다. 시내 및 고속도로 운전모드에서의 평균효율특성을 분석한 결과, 직경비 0.68 모델이 직경비 0.63 및 0.65 모델보다 평균효율이 높게 분석되었으며 시내 및 고속도로 주행모드에 적합함을 확인하였다.

• 조명전기설비학회논문지
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• 제26권8호
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• pp.1-7
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• 2012

In this paper, a new LED driving circuit which is able to control dimming of LED is proposed using charge pump. The proposed LED driving circuit steps down the input voltage to operate LED without DC-DC converter. The operation of this driving circuit is verified by P-Spice simulation, and the characteristics of the driving circuit is measured and evaluated in the experiments. As a result, the driving circuit efficiency of 88.5[%] is obtained when all LEDs are turned on by digital control method at the highest dimming level(255/255).

• Journal of Electrical Engineering and Technology
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• 제12권5호
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• pp.1934-1944
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• 2017

As a key component of high-voltage power conversion system for electric vehicles (EVs), bidirectional DC/DC (Bi-DC/DC) is required to have high efficiency and light weight. Conventional design methods optimize the Bi-DC/DC at the maximum power dissipation point (MPDP). For EVs application, the work condition of the Bi-DC/DC is not strict as the MPDP, where the design method using MPDP may not be optimal during travel of EVs. This paper optimizes the Bi-DC/DC converter targeting efficiency and weight based on the driving cycle. By analyzing the two-phase interleaved Bi-DC/DC for hybrid energy storage systems (HESS) of EVs, its power dissipation is calculated, and an efficiency model is derived. On this basis, weight models of capacitor, inductor and heat sink are built, as well as a dynamic temperature model of heat sink. Based on these models, a method using New European Driving Cycle (NEDC) for optimal design of Bi-DC/DC which simultaneously considered efficiency and weight is proposed. The simulation result shows that compare with conventional optimization methods revealed that the optimization approach based on driving cycle allowed significant weight reduction while meeting the efficiency requirements.

• Journal of Magnetics
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• 제20권2호
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• pp.148-154
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• 2015

48-V ISG (Integrated Starter Generator) system has attracted attention to improve the fuel efficiency of ICE (Internal Combustion Engine) vehicle. One of the key components that significantly affects the cost and performance of the 48-V ISG system is the motor. In an ISG motor, the core and copper loss make the motor efficiency change because the motor has a broad driving operated range and more diverse driving modes compared with other motors. When designing an ISG motor, the selection of an electrical steel sheet is important, because the electrical steel sheet directly influences the efficiency of the motor. In this paper, the efficiency of the ISG motor, considering core loss and copper loss, is analyzed by testing different types of electrical steel sheets with respect to the driving speed range and mode. Using the results of a finite element method (FEM) analysis, a method to select the electrical steel sheet is proposed. This method considers the cost of the steel sheet and the efficiency according to driving mode frequency during the design process of the motor. A wound rotor synchronous machine (WRSM) was applied to the ISG motor in this study.

• 한국지반공학회논문집
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• 제16권1호
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• pp.235-241
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• 2000

기존의 장대강관말뚝 공법들은 말뚝의 용접이음이나 관내토의 제거 작업으로 인하여 공비와 공기가 증가하고 이들 작업이 진행되는 동안 시간효과에 의하여 말뚝의 관입 저항이 증가하여 타입이 어려워지는 등 각종 비경제적인 문제점들을 갖고 있다. 이러한 문제들을 해결하기 위하여 본 연구에서는 새로운 장대강관말뚝 공법을 제안하였으며, 제안된 공법의 시공성과 경제성을 분석하기 위하여 모형말뚝시험을 행하였다. 시험결과 새로 제안된 장대말뚝공법은 기존 공법에 비해 공기와 공비는 절감되고 지지력은 증가시키는 것으로 나타났다.