• Journal of Electrical Engineering and Technology
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• 제13권2호
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• pp.591-598
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• 2018

Short term load forecasts complexly affected by socioeconomic factors and weather variables have non-linear characteristics. Thus far, researchers have improved load forecast technologies through diverse techniques such as artificial neural networks, fuzzy theories, and statistical methods in order to enhance the accuracy of load forecasts. Short term load forecast errors for special days are relatively much higher than that of weekdays. The errors are mainly caused by the irregularity of social activities and insufficient similar past data required for constructing load forecast models. In this study, the load characteristics of Lunar New Year's Day holidays well known for the highest error occurrence holiday period are analyzed to propose a load forecast technique for Lunar New Year's Day holidays. To solve the insufficient input data problem, the similarity of the load patterns of past Lunar New Year's Day holidays having similar patterns was judged by Euclid distance. Lunar New Year's Day holidays periods for 2011-2012 were forecasted by the proposed method which shows that the proposed algorithm yields better results than the comprehensive analysis method or the knowledge-based method.

• International journal of advanced smart convergence
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• 제5권2호
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• pp.24-37
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• 2016

This paper proposes to increase the efficiency of energy in nodes, which rapidly drops during the transmission of the Low Energy Adaptive Clustering Hierarchy (LEACH), through the use of dual-hop layered application in the sensor field. Along with introducing the dual-hop method in the data transmission, the proposed single-hop method for short-range transmission and multi-hop transmission method between the cluster heads for remote transmission were also introduced. Additionally, by introducing a partial multi-hop method in the data transmission, a single-hop method for short range transmission method between the cluster heads for remote transmission was used. In the proposed DL-LEACH, the energy consumption of the cluster head for remote transmission reduced, as well as increased the energy efficiency of the sensor node by reducing the transmission distance and simplifying the transmission route for short-range transmission. As compared the general LEACH, it was adapted to a wider sensor field.

• Earthquakes and Structures
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• 제8권4호
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• pp.859-887
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• 2015

Structural health monitoring (SHM) has gained in popularity in recent years since it can assess the performance and condition of instrumented structures in real time and provide valuable information to the asset's manager and owner. Operational modal analysis plays an important role in SHM and it involves the determination of natural frequencies, damping ratios and mode shapes of a constructed structure based on measured dynamic data. This paper presents the operational modal analysis and seismic response characterization of the Tsing Ma Suspension Bridge of 2,160 m long subjected to different earthquake events. Three kinds of events, i.e., short-distance, middle-distance and long-distance earthquakes are taken into account. A fast Bayesian modal identification method is used to carry out the operational modal analysis. The modal properties of the bridge are identified and compared by use of the field monitoring data acquired before and after the earthquake for each type of the events. Research emphasis is given on identifying the predominant modes of the seismic responses in the deck during short-distance, middle-distance and long-distance earthquakes, respectively, and characterizing the response pattern of various structural portions (deck, towers, main cables, etc.) under different types of earthquakes. Since the bridge is over 2,000 m long, the seismic wave would arrive at the tower/anchorage basements of the two side spans at different time instants. The behaviors of structural dynamic responses on the Tsing Yi side span and on the Ma Wan side span under each type of the earthquake events are compared. The results obtained from this study would be beneficial to the seismic design of future long-span bridges to be built around Hong Kong (e.g., the Hong Kong-Zhuhai-Macau Bridge).

• 한국전기전자재료학회논문지
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• 제23권2호
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• pp.169-173
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• 2010

Because of power consumption increase, global warming, and limitation of installation, not only high reliability and interruption capability but also compact and light power apparatuses are needed. In this paper, E field calculation and experiment were processed to identify the influence of the shape of end shield and gap distance. It is expected that the results of FEM simulation and experiments could be the basic data to develop VI. the results of FEM simulation and experiments are as following. Firstly, maximum E fields were compared by means of finite element method as a function of the shape of end shield. 3 types of models were used to analyze maximum E field of each model and the influence of shape of shield could be identified. As a result, proposed L type shield could reduce the maximum E field by 20%. Secondly, the influence of the gap distance between end shields on E field was analyzed. As the gap distance become short the gap distance between inner walls of ceramic also become short. And the maximum E field concentrated on inner wall of ceramic finally increased. Thirdly, the experiment was conducted by fabricating each prototype. As a result, no creepage occurred in shieldless model. In other words, creepage occurred in the shield-installed models. And creepage inception voltages were different from each other because of the difference of maximum E field. Fourthly, The equation that shows relation between calculated E field and measured creepage inception voltage was proposed as a result of FEM analysis and experiment. It is concluded that when designing VI this equation could be important data to reduce time and cost by identifying indirectly the optimal gap distance and the shape of shield required to prevent creepage.

• 생명과학회지
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• 제14권1호
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• pp.57-60
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• 2004

육종재료를 얻기 위하여 부산ㆍ경남지역에서 수집된 우리나라 재래종 옥수수 49계통에 대하여 주성분분두법을 이용하여 계통간 거리를 구하였고, 이를 이용하여 계통분류를 실시하였던 바 다음과 같은 결과를 얻었다. 계통간 거리에 의해 49계통은 4개의 계통군으로 분류되었고, 계통군 I 에는 11계통, 계통군 II에는 20계통, 계통군 III에 는 14계통, 그리고 계통군 IV에는 4계통이 속하였다. 계통군 I은 조생, 단간, 소수, 소분얼형의 계통들이었고, 계통군 II는 조생, 장간, 대수, 다수, 소분얼형의 계통이었고, 계통군 III은 만생, 단간, 소수, 다분얼형 의 계통이었고, 계통군 IV는 중생, 장간, 대수, 다수, 다분얼형의 계통들이었다.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2004년도 춘계학술발표대회 논문집
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• pp.219-222
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• 2004

The effects of short fiber and particle hybrid reinforcement on fatigue crack propagation behaviors in aluminum matrix composites have been investigated. Single and hybrid reinforced 6061 aluminum containing same 20 $Al_2O_3\;volume\%$ with four different constituent ratios of short fibers and particles were prepared by squeeze casting method and tested to check the near-threshold and stable crack growth behavior. The fatigue threshold of the composites increased with portion of particle contents and showed the improved crack resistance especially in low stress intensity range. Addition of particle instead of short fiber also increased fracture toughness due to increase of inter-reinforcement distance. These increase in both fatigue threshold and fracture toughness eventually affected the fatigue crack growth behavior such that the crack growth curve shift low to high stress intensity factor value. Overall experimental results were shown that particle reinforcement was enhanced the fatigue crack resistance over the whole stress intensity factor range.

• 유통과학연구
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• 제12권10호
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• pp.99-108
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• 2014

Purpose - The goals of this study are the following. First, this study focused on customer satisfaction of in-flight service. Specifically, in-flight duty free items were considered because of their potential value related with the differentiated strategy of airline companies. Second, this study analyzed feasible strategies that would fence off the aversive attitudes of consumers toward innovation regarding in-flight duty free items. Third, this study strived to discover implicit routes related with the reactions of of consumers to innovation. Fourth, the construal level theory was applied to the context of in-flight service. Psychological distance is expected to promote acceptance of innovation for duty free items. Research design, data, and methodology - This study consisted of three experiments. All data were collected through the participation of university students. First, the experiment employed a 2×2 between-subject design. The first independent variable was temporal distance (long vs. short of navigation time). The second independent variable was innovativeness (innovative duty free items vs. typical items). Further, experiment 2 involved a 2×2 between-subject design. The first independent variable was social distance (typical vs. atypical stewardess image). The second was innovativeness that was based on a pattern similar to that of the prior experiment. The third experiment involved a 2×2×2 design. The first and second independent variables were temporal distance and item innovation, respectively, based on the method of experiment 1. The third independent variable was cognitive depletion (depletion vs. control condition). Results - Experiment 1 demonstrated that the innovation of duty free items would need to consider the journey time of the airline. Specifically, innovative items were preferred in case of a long journey; typical items, however, were liked in a short journey. Further, experiment 2 demonstrated that, in spite of a short journey, innovative items would be preferred if an atypical stewardess was serving. An atypical stewardess was linked with social distance, and the psychological effects would activate a creative and flexible mindset that would fit with innovative duty free items. The final experiment was accomplished for the examination of cognitive processing of psychological distance on innovation-acceptance. Specifically, if the effects were related with systematic processing, then cognitive effort would be needed. In contrast, if they were related with heuristic processing, then such efforts would not be required. The same pattern appeared under both cognitive depletion and control condition; therefore, the effects of psychological distance were implied to be heuristic processing. Conclusions - Managers need to consider the navigation time, stewardess concepts, and depletion of consumers as important factors for innovative strategy regarding in-flight service. Longer journeys are more successful for innovative trials. Further, a more atypical stewardess image is more successful for atypical service. Long navigation and unfamiliar stewardesses may activate creative and flexible thinking. Further, cognitive depletion of consumers is not a dominant factor of psychological distance effects, because the effects are not related with systematic processing, but with heuristic processing.

• 대한디지털의료영상학회논문지
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• 제12권2호
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• pp.119-125
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• 2010

In order to demonstrate the value of long-distance radiography, we have studied how distance affects images in chest frontal radiography and compared short-distance and long-distance images in chest lateral radiography. Cardiothoracic ratio(CTR %) of 50 patients with no disease in the chest(10 each at the age of 20~60) were evaluated in Supine AP(100 cm), Sitting AP(100 cm), Sitting AP(180 cm), and Erect PA(180 cm). In lateral radiography, we evaluated and compared left lateral radiography(100 cm and 180 cm) of the patients based on the horizontal maximum of the heart. The average value of CTR(%) were 0.48 in Erect PA(180 cm), 0.52 in Supine AP(100 cm), 0.50 in Sitting AP(100 cm), 0.49 in Sitting AP(180 cm), which were Supine AP(100 cm) > Sitting AP(100 cm) > Sitting AP(180 cm) > Erect PA(180 cm). The average value of Maximum transverse diameter of left of the cardiac(MLD), which showed how much axis of spine was slanted to the left, was 90.67 mm in Erect PA(180 cm), 103.92 mm in Supine AP(100 cm), 93.54 mm in Sitting(100 cm), 89.84 mm in Sitting AP(180 cm), 58.11 mm in the minimum value and 118.79 mm in the maximum value. The average value of Maximum transverse diameter of right side of the cardiac(MRD), which suggested how much axis of spine was slanted to the right, was 47.18 mm in Erect PA(180 cm), 48.12 mm in Supine AP(100 cm), 44.98 mm in Sitting AP(180 cm), and the minimum value 26.84 mm and the maximum value 65.30 mm. There was no standard method to calculate; therefore, the horizontal maximum of the heart was used for lateral radiography. The average value was 121.07 mm in 100 cm and 109.76 mm in 180 cm. Sitting AP(180 cm) among the types was closest to C-PA(180 cm). As a result, during C-AP radiography, long-distance radiography lessened shadow of the heart more than that of short distance, Sitting position more than Supine position.

• 제어로봇시스템학회논문지
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• 제17권2호
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• pp.149-156
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• 2011

This paper reveals a distance estimation algorithm based on multi-code ultrasonic and wireless sensor network. For measuring the distances among the sensor nodes, each ultrasonic transmitter transmits multi-code ultrasonic signal simultaneously. Receivers use cross correlation method to separate the coded signals. The information of measured distances is broadcasted to each sensor node by wireless sensor network. The wireless sensor network measures the distance among the sensor nodes using the received signal strength of the broadcasting. The multi-code ultrasonic have a limitation of measurable distance. And the received signal strength is affected from an environment. This paper measures a distance using ultrasonic and a received signal strength in short range. These measured data are applied to the least square estimation algorithm. By the expansion of the fitting curve, a distance measurement in long range using the received signal strength is compensated. The coupled system reduce the error to an acceptable level.

• 전자공학회논문지SC
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• 제45권6호
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• pp.108-116
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• 2008

본 논문에서는 스테레오 비전에서 시차를 이용하여 근거리뿐만 아니라 원거리의 장애 물체에 대해서도 신뢰성 있는 거리를 추정하기 위한 알고리즘을 제안한다. 시차를 이용한 거리 측정에서 양자화 오차는 원거리에서의 거리 정확도를 떨어뜨리게 되므로, 이를 최소화하기 위해 부화소 보간법(sub-pixel interpolation)을 이용하여 시차 정확도를 향상시키고 거리 정확도 및 경로 추적의 최적화를 위해서 향상된 적응형 퍼지 칼만 필터(EAFSTKF : Enhanced Adaptive Fuzzy Strong Tracking Kalman Filter)를 사용한다. 제안한 방법은 차량과 같이 다양한 동적인 움직임에 의한 비선형성에 대하여 기존 칼만 필터에서 발생되는 발산 문제(divergence problem)를 해결할 수 있고, 거리의 정확도 및 신뢰도도 높일 수 있다. 몬테카를로(Monte Carlo) 방법을 이용한 모의실험 결과 제안한 방법은 기존 방법들과 거리 오차율(RMSER : Root Mean Square Error Rate)을 비교하였을 때, strong tracking Kalman filter(STKF)에 비하여 성능이 약 13.5%정도 향상되었음을 보여준다.