• Title/Summary/Keyword: Electric power

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A Study on the Improvement Plan of the Urban Area Using the Three-Dimensional Road System -Focus on Shinbashi·Toranomon area in Japan- (입체도로제도를 활용한 도심 정비방안에 관한 연구 -일본 신바시, 토라노몬 재개발사업을 중심으로-)

  • Baek, Seung-Kwan
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.19 no.11
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    • pp.213-223
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    • 2018
  • This study assessed the maintenance plan of the Shimbashi-Toranomon Development Area in Japan, which has recently been completed using the three-dimensional road system. In the main relevant law system, a three-dimensional road system, which enables the construction of buildings above and below the road, was applied. The specific construction regulations applying the financing power and knowledge of private business operators were applied. In the development district, city maintenance guidelines were established, and housing and shopping malls were regulated. This purpose was to promote change, unity of distance, effective use of land, and continuous urban revitalization with charm and vitality. The main features of the maintenance plan were accessibility and greenery, comfort and a sophisticated design, and a maintenance concept utilizing historical buildings and road space through the participation of local residents and the opinions of related committees. In addition, in the case of the construction of the upper and lower roads, the construction restrictions were relaxed, and the separation of the roads and the undergrounding of electric poles were promoted. The main aim was to improve the convenience of the residents and produce a pleasant road landscape.

Recent Progress and Perspectives of Solid Electrolytes for Lithium Rechargeable Batteries (리튬이차전지용 고체 전해질의 최근 진전과 전망)

  • Kim, Jumi;Oh, Jimin;Kim, Ju Young;Lee, Young-Gi;Kim, Kwang Man
    • Journal of the Korean Electrochemical Society
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    • v.22 no.3
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    • pp.87-103
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    • 2019
  • Nonaqueous organic electrolyte solution in commercially available lithium-ion batteries, due to its flammability, corrosiveness, high volatility, and thermal instability, is demanding to be substituted by safer solid electrolyte with higher cycle stability, which will be utilized effectively in large-scale power sources such as electric vehicles and energy storage system. Of various types of solid electrolytes, composite solid electrolytes with polymer matrix and active inorganic fillers are now most promising in achieving higher ionic conductivity and excellent interface contact. In this review, some kinds and brief history of solid electrolyte are at first introduced and consequent explanations of polymer solid electrolytes and inorganic solid electrolytes (including active and inactive fillers) are comprehensively carried out. Composite solid electrolytes including these polymer and inorganic materials are also described with their electrochemical properties in terms of filler shapes, such as particle (0D), fiber (1D), plane (2D), and solid body (3D). In particular, in all-solid-state lithium batteries using lithium metal anode, the interface characteristics are discussed in terms of cathode-electrolyte interface, anode-electrolyte interface, and interparticle interface. Finally, current requisites and future perspectives for the composite solid electrolytes are suggested by help of some decent reviews recently reported.

Field Applications of Non-powered Downward Water Circulation System to Improve Reservoir Water Quality (저수지 수질개선을 위한 무동력 하향류 수류순환시스템의 현장적용성)

  • Jang, YeoJu;Lim, HyunMan;Jung, JinHong;Park, JaeRho;Kim, WeonJae
    • Ecology and Resilient Infrastructure
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    • v.6 no.2
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    • pp.109-119
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    • 2019
  • Eutrophication has occurred due to the inflow of various water pollutants in many Korean reservoirs with low depth, and algal blooms of surface layer and low oxygenation of deep layer have repeated every year. There are several existing technologies to alleviate the stratification of reservoirs, but it is difficult to apply them in field sites due to the necessity of electric power and low economic efficiency. In this study, a non-powered water circulation system using natural energy of wind and water flow has been developed, and two test-beds constructed in the reservoirs with different conditions and examined its field applicability. Through computational fluid dynamics (CFD) simulation, it has been shown that the water circulation system could induce the downward flow to mitigate the stratification between surface and deep layers, and its influence radius could reach about 30 m. As a result of long-term monitoring of the test-beds, various water quality improvement effects have been observed such as moderation of DO fluctuation by water circulation, reduction of DO supersaturation and prevention of excessive pH rising. In order to improve the applicability of the water circulation system, it is considered necessary to review countermeasures against flood and depth conditions of each reservoir.

Forecasting daily peak load by time series model with temperature and special days effect (기온과 특수일 효과를 고려하여 시계열 모형을 활용한 일별 최대 전력 수요 예측 연구)

  • Lee, Jin Young;Kim, Sahm
    • The Korean Journal of Applied Statistics
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    • v.32 no.1
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    • pp.161-171
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    • 2019
  • Varied methods have been researched continuously because the past as the daily maximum electricity demand expectation has been a crucial task in the nation's electrical supply and demand. Forecasting the daily peak electricity demand accurately can prepare the daily operating program about the generating unit, and contribute the reduction of the consumption of the unnecessary energy source through efficient operating facilities. This method also has the advantage that can prepare anticipatively in the reserve margin reduced problem due to the power consumption superabundant by heating and air conditioning that can estimate the daily peak load. This paper researched a model that can forecast the next day's daily peak load when considering the influence of temperature and weekday, weekend, and holidays in the Seasonal ARIMA, TBATS, Seasonal Reg-ARIMA, and NNETAR model. The results of the forecasting performance test on the model of this paper for a Seasonal Reg-ARIMA model and NNETAR model that can consider the day of the week, and temperature showed better forecasting performance than a model that cannot consider these factors. The forecasting performance of the NNETAR model that utilized the artificial neural network was most outstanding.

A Study on Design of Wind Blade with Rated Capacity of 50kW (50kW 풍력블레이드 설계에 관한 연구)

  • Kim, Sang-Man;Moon, Chae-Joo;Jung, Gweon-Sung
    • The Journal of the Korea institute of electronic communication sciences
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    • v.16 no.3
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    • pp.485-492
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    • 2021
  • The wind turbines with a rated capacity of 50kW or less are generally considered as small class. Small wind turbines are an attractive alternative for off-grid power system and electric home appliances, both as stand-alone application and in combination with other energy technologies such as energy storage system, photovoltaic, small hydro or diesel engines. The research objective is to develop the 50kW scale wind turbine blades in ways that resemble as closely as possible with the construction and methods of utility scale turbine blade manufacturing. The mold process based on wooden form is employed to create a hollow, multi-piece, lightweight design using carbon fiber and fiberglass with an epoxy based resin. A hand layup prototyping method is developed using high density foam molds that allows short cycle time between design iterations of aerodynamic platforms. A production process of five blades is manufactured and key components of the blade are tested by IEC 61400-23 to verify the appropriateness of the design. Also, wind system with developed blades is tested by IEC 61400-12 to verify the performance characteristics. The results of blade and turbine system test showed the available design conditions for commercial operation.

Time series clustering for AMI data in household smart grid (스마트그리드 환경하의 가정용 AMI 자료를 위한 시계열 군집분석 연구)

  • Lee, Jin-Young;Kim, Sahm
    • The Korean Journal of Applied Statistics
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    • v.33 no.6
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    • pp.791-804
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    • 2020
  • Residential electricity consumption can be predicted more accurately by utilizing the realtime household electricity consumption reference that can be collected by the AMI as the ICT developed under the smart grid circumstance. This paper studied the model that predicts residential power load using the ARIMA, TBATS, NNAR model based on the data of hour unit amount of household electricity consumption, and unlike forecasting the consumption of the whole households at once, it computed the anticipated amount of the electricity consumption by aggregating the predictive value of each established model of cluster that was collected by the households which show the similiar load profile. Especially, as the typical time series data, the electricity consumption data chose the clustering analysis method that is appropriate to the time series data. Therefore, Dynamic Time Warping and Periodogram based method is used in this paper. By the result, forecasting the residential elecrtricity consumption by clustering the similiar household showed better performance than forecasting at once and in summertime, NNAR model performed best, and in wintertime, it was TBATS model. Lastly, clustering method showed most improvements in forecasting capability when the DTW method that was manifested the difference between the patterns of each cluster was used.

The 4:1(50-Ω:12.5-Ω) microstrip-slot line impedance transformer using a dielectric resonator (유전체 공진기를 이용한 4:1(50-Ω:12.5-Ω) 마이크로스트립-슬롯 선로 임피던스 변환기)

  • Park, Ung-hee
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.24 no.11
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    • pp.1484-1491
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    • 2020
  • Since the slot line transmits electric and magnetic signals through the slot, the size of the slot greatly affects the signal power loss. In order to have low loss, the slot line is mainly used at a high frequency of above 3GHz on a substrate having a high dielectric constant(er). This paper proposes the 4:1 impedance transformer using a slot line on TLC-30 laminate (h=20mil, er=3.0; Taconic) being a relatively low dielectric constant at a frequency of 1.85GHz. In the proposed impedance transformer, the dielectric resonator is arranged on the slot line to reduce signal loss occurring at the slot line. The proposed 4:1 microstrip-slot line impedance transformer fabricated using a (Zr,Sn)TiO4 dielectric resonator(er=38) has the transmission loss(S21) of -0.375dB and the reflection value(S11) of -27.6dB at 1.855GHz. This confirms that the slot line can be stably used even in a low dielectric constant substrate and a low frequency region by using a dielectric resonator.

Development of Panel-Based Rapid Aerodynamic Analysis Method Considering Propeller Effect (프로펠러 효과를 반영 가능한 패널 기반 신속 공력 해석 기법 개발)

  • Tai, Myungsik;Lee, Yebin;Oh, Sejong;Shin, Jeongwoo;Lim, Joosup;Park, Donghun
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.49 no.2
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    • pp.107-120
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    • 2021
  • Electric-powered distributed propulsion aircraft possess a complex wake flow and mutual interference with the airframe, due to the use of many propellers. Accordingly, in the early design stage, rapid aerodynamic and load analysis considering the effect of propellers for various configurations and flight conditions are required. In this study, an efficient panel-based aerodynamic analysis method that can take into account the propeller effects is developed and validated. The induced velocity field in the region of propeller wake is calculated based on Actuator Disk Theory (ADT) and is considered as the boundary condition at the vehicle's surface in the three-dimensional steady source-doublet panel method. Analyses are carried out by selecting an isolated propeller of the Korea Aerospace Research Institute (KARI)'s Quad Tilt Propeller (QTP) aircraft and the propeller-wing configuration of the former experimental study as benchmark problems. Through comparisons with the results of computational fluid dynamics (CFD) based on actuator methods, the wake velocity of propeller and the changes in the aerodynamic load distribution of the wing due to the propeller operation are validated. The method is applied to the analysis of the Optional Piloted Personal Aerial Vehicle (OPPAV) and QTP, and the practicality and validity of the method are confirmed through comparison and analysis of the computational time and results with CFD.

A Review of Structural Batteries with Carbon Fibers (탄소섬유를 활용한 구조용 배터리 연구 동향)

  • Kwon, Dong-Jun;Nam, Sang Yong
    • Applied Chemistry for Engineering
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    • v.32 no.4
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    • pp.361-370
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    • 2021
  • Carbon fiber reinforced polymer (CFRP) is one of the composite materials, which has a unique property that is lightweight but strong. The CFRPs are widely used in various industries where their unique characteristics are required. In particular, electric and unmanned aerial vehicles critically need lightweight parts and bodies with sufficient mechanical strengths. Vehicles using the battery as a power source should simultaneously meet two requirements that the battery has to be safely protected. The vehicle should be light of increasing the mileage. The CFRP has considered as the one that satisfies the requirements and is widely used as battery housing and other vehicle parts. On the other hand, in the battery area, carbon fibers are intensively tested as battery components such as electrodes and/or current collectors. Furthermore, using carbon fibers as both structure reinforcements and battery components to build a structural battery is intensively investigated in Sweden and the USA. This mini-review encompasses recent research trends that cover the classification of structural batteries in terms of functionality of carbon fibers and issues and efforts in the battery and discusses the prospect of structural batteries.

EF Sensor-Based Hand Motion Detection and Automatic Frame Extraction (EF 센서기반 손동작 신호 감지 및 자동 프레임 추출)

  • Lee, Hummin;Jung, Sunil;Kim, Youngchul
    • Smart Media Journal
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    • v.9 no.4
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    • pp.102-108
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    • 2020
  • In this paper, we propose a real-time method of detecting hand motions and extracting the signal frame induced by EF(Electric Field) sensors. The signal induced by hand motion includes not only noises caused by various environmental sources as well as sensor's physical placement, but also different initial off-set conditions. Thus, it has been considered as a challenging problem to detect the motion signal and extract the motion frame automatically in real-time. In this study, we remove the PLN(Power Line Noise) using LPF with 10Hz cut-off and successively apply MA(Moving Average) filter to obtain clean and smooth input motion signals. To sense a hand motion, we use two thresholds(positive and negative thresholds) with offset value to detect a starting as well as an ending moment of the motion. Using this approach, we can achieve the correct motion detection rate over 98%. Once the final motion frame is determined, the motion signals are normalized to be used in next process of classification or recognition stage such as LSTN deep neural networks. Our experiment and analysis show that our proposed methods produce better than 98% performance in correct motion detection rate as well as in frame-matching rate.