• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 춘계학술대회논문집
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• pp.1022-1027
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• 2001

In this study, the train-induced vibration was measured at many locations at/around the actual service lines and the data base was constructed using the measurement results. The characteristics of train induced ground vibration was categorized and the empirical ground vibration estimating equations were developed. On the ground area (level grounds, embankments, cut sections), the vibration estimating equations were developed in terms of ground vibration level which was related with the distance from the source. Especially for the cut section areas, the vibration levels were expressed with the vibration receiving point expressed by the ratio of vertical distance to horizontal distance(V/H) from the source. As a result, when V/H is 0.96, the vibration estimating equation gives a minimum vibration level.

• 한국정보통신학회논문지
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• 제18권10호
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• pp.2523-2529
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• 2014

실외에서는 GPS를 기반으로 하는 다양한 위치 추정 시스템을 사용하여 위치 추정 서비스를 제공할 수 있으나, 실내에서는 가시위성의 부족과 신호의 미약으로 GPS를 사용할 수 없어 실내에 존재하는 자원을 기반으로 하는 위치 추정시스템을 사용하고 있다. 특히 WLAN의 신호를 이용하는 fingerprinting 기법은 AP에서 제공하는 RSSI를 이용하여 위치를 추정하기에 실내에서 이용하기에 적합하다. 하지만 fingerprinting 기법은 fingerprinting map을 구축하는 offline 단계에서 얼마나 정확한 데이터를 이용하였는가에 따라 위치 추정의 정확도가 달라지는 단점이 존재한다. 본 논문에서는 이러한 단점을 보완하기 위해 fingerprinting map을 구축하는 단계에서 다수의 데이터를 샘플링 하여 그 중 빈도가 높은 데이터를 저장하여 위치 추정 정밀도를 높이는 위치 추정 시스템을 제안한다. 제안하는 머저리티 샘플링 데이터 기반의 위치 추정 시스템은 map에 저장되어야 하는 RSSI를 클라이언트와 서버에서 가장 빈도가 높은 RSSI데이터를 필터링하여 map을 구축한 후 유사거리측정방식에 의해 위치를 추정하는 시스템이다. 실험결과 최소 87.5 %, 최대 90.4%의 위치 추정 정밀도를 가지는 것을 알 수 있으며, 최소 0.25 ~ 2.72m의 오차 범위를 가지는 것을 확인 할 수 있었다.

• Journal of the Korean Data and Information Science Society
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• 제13권1호
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• pp.47-53
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• 2002

A new redescending M-estimating function is introduced. The estimators by this new redescending function attain the same level of robustness as the existing redescending M-estimators, but have less asymptotic variances than others except few cases. We have focused on estimating a location parameter, but the method can be extended for a scale estimation.

• 한국농림기상학회지
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• 제4권4호
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• pp.203-212
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• 2002

주로 도시에 소재하는 표준기상관측소 자료의 공간 내삽에 의해 일 최저기온의 평년값을 추정할 때, 도시 열섬효과의 전이에 의해 전원지역에서 과다추정 되는 오류를 수정하기 위해 본 연구를 수행하였다. 도시열섬효과의 공간적인 확산을 모의하기 위해 먼저 불연속적인 변량인 시군 행정구역단위 인구를 지표피복도 상의 시가지 픽셀에만 할당하여 규칙적인 격자점 단위의 평균인구로 변환함으로써 연속적인 변량인 수치인구모형(DPM)으로 표현하였다. 다섯 가지 평활화 DPM 가운데 최적으로 판명된 사방 2.5 km DPM과 기온추정 오차간 회귀식을 기존의 거리-고도 보정 내삽과정에 결합하였다. 이 방법을 적용하여 추정된 평년(1971-2000) 월별 일 최저기온의 추정오차는 기존방법에 비해 최소 50%가 개선되었다.

• 한국군사과학기술학회지
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• 제12권6호
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• pp.768-775
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• 2009

In this paper, the sound source localization system in real time which uses the time delay of arrival signal is proposed. This system uses minimum microphones and surveillance camera for estimation of the sound source localization and sound direction. To apply this system to the military field, four models(model1~model4) are derived. Model 1 can be used to evaluate the sound source localization at the long distance. Model2 and model3 can be applied to estimate the sound direction. Model4 is useful for the special purpose and potable device. It is possible for this system to be used for the military guard and surveillance. As a result of experiments, It is shown that this system can estimate the sound source localization and the sound direction using minimum microphones.

• Journal of Electrical Engineering and Technology
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• 제13권6호
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• pp.2145-2157
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• 2018

Congestion Management (CM) is an attractive research area in the electrical power transmission with the power compensation abilities. Reconfiguration and the Flexible Alternating Current Transmission Systems (FACTS) devices utilization relieve the congestion in transmission lines. The lack of optimal power (real and reactive) usage with the better transfer capability and minimum cost is still challenging issue in the CM. The prediction of suitable place for the energy resources to control the power flow is the major requirement for power handling scenario. This paper proposes the novel optimization principle to select the best location for the energy resources to achieve the real-reactive power compensation. The parameters estimation and the selection of values with the best fitness through the Symmetrical Distance Travelling Optimization (SDTO) algorithm establishes the proper controlling of optimal power flow in the transmission lines. The modified fitness function formulation based on the bus parameters, index estimation correspond to the optimal reactive power usage enhances the power transfer capability with the minimum cost. The comparative analysis between the proposed method with the existing power management techniques regarding the parameters of power loss, cost value, load power and energy loss confirms the effectiveness of proposed work in the distributed renewable energy systems.

• Journal of Communications and Networks
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• 제17권4호
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• pp.370-383
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• 2015

Effective link quality estimation is a vital issue for reliable routing in wireless networks. This paper studies the performance of expected transmission count (ETX) under different traffic loads. Although ETX shows good performance under light load, its performance gets significantly worse when the traffic load is high. A broadcast packet storm due to new route discoveries severely affects the link ETX values under high traffic load, which makes it difficult to find a good path. This paper presents the design and implementation of a variation of ETX called high load - ETX (HETX), which reduces the impact of route request broadcast packets to link metric values under high load. We also propose a reliable routing protocol using link quality metrics, which is called link quality distance vector (LQDV). We conducted the evaluation of the performance of three metrics - HETX, ETX and minimum hop-count. The simulation results show that HETX improves the average route throughput by up to 25% over ETX under high traffic load. Minimum hop-count has poor performance compared with both HETX and ETX at all of the different traffic loads. Under light load, HETX and ETX show the same performance.

• 한국기후변화학회지
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• 제5권4호
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• pp.323-329
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• 2014

Since the terrain of Korea is complex, micro- as well as meso-climate variability is extreme by locations in Korea. In particular, air temperature of agricultural fields is influenced by topographic features of the surroundings making accurate interpolation of regional meteorological data from point-measured data. This study was carried out to compare spatial interpolation methods to estimate air temperature in agricultural fields surrounded by rugged terrains in South Korea. Four spatial interpolation methods including Inverse Distance Weighting (IDW), Spline, Ordinary Kriging (with the temperature lapse rate) and Cokriging were tested to estimate monthly air temperature of unobserved stations. Monthly measured data sets (minimum and maximum air temperature) from 588 automatic weather system(AWS) locations in South Korea were used to generate the gridded air temperature surface. As the result, temperature lapse rate improved accuracy of all of interpolation methods, especially, spline showed the lowest RMSE of spatial interpolation methods in both maximum and minimum air temperature estimation.

• 전자공학회논문지
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• 제52권5호
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• pp.214-221
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• 2015

본 논문에서는 측정 잡음에 의해서 출력 신호가 왜곡된 이산 시간 선형 스위치드 시스템의 스위칭 신호와 상태 변수를 관측하기 위한 강인한 추정 및 검출 기법을 제시한다. 첫째, 최소 거리 기준에 기초한 작동 모드 추정 알고리즘이 제안된다. 이 과정에서 모드의 추정값을 얻게 되고, 이를 이용하여 상태 변수 또한 관측할 수 있게 된다. 둘째, 주어진 스위치드 시스템의 작동 모드 변화 시점, 즉, 스위칭이 언제 발생하는지 검출하는 알고리즘이 고안된다. 시스템에 인가되는 측정 잡음이 유계라는 가정 하에, 제안된 추정 알고리즘은 주어진 스위치드 시스템의 작동 모드를 정확하게, 그리고 상태 변수를 근사적으로 추정하며, 검출 알고리즘은 실제 스위칭이 발생한 후, 미리 정해진 지연 시간이 지나가기 전에 스위칭 시간을 검출할 수 있다.

• Communications for Statistical Applications and Methods
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• 제24권5호
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• pp.493-505
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• 2017

Maximum likelihood estimation (MLE) of the generalized extreme value distribution (GEVD) is known to sometimes over-estimate the positive value of the shape parameter for the small sample size. The maximum penalized likelihood estimation (MPLE) with Beta penalty function was proposed by some researchers to overcome this problem. But the determination of the hyperparameters (HP) in Beta penalty function is still an issue. This paper presents some data adaptive methods to select the HP of Beta penalty function in the MPLE framework. The idea is to let the data tell us what HP to use. For given data, the optimal HP is obtained from the minimum distance between the MLE and MPLE. A bootstrap-based method is also proposed. These methods are compared with existing approaches. The performance evaluation experiments for GEVD by Monte Carlo simulation show that the proposed methods work well for bias and mean squared error. The methods are applied to Blackstone river data and Korean heavy rainfall data to show better performance over MLE, the method of L-moments estimator, and existing MPLEs.