• Journal of information and communication convergence engineering
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• 제20권1호
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• pp.22-30
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• 2022

The reinforcement learning algorithm has proven its potential in solving sequential decision-making problems under uncertainties, such as finding paths to route data packets in wireless sensor networks. With reinforcement learning, the computation of the optimum path requires careful definition of the so-called reward function, which is defined as a linear function that aggregates multiple objective functions into a single objective to compute a numerical value (reward) to be maximized. In a typical defined linear reward function, the multiple objectives to be optimized are integrated in the form of a weighted sum with fixed weighting factors for all learning agents. This study proposes a reinforcement learning -based routing protocol for wireless sensor network, where different learning agents prioritize different objective goals by assigning weighting factors to the aggregated objectives of the reward function. We assign appropriate weighting factors to the objectives in the reward function of a sensor node according to its hop-count distance to the sink node. We expect this approach to enhance the effectiveness of multi-objective reinforcement learning for wireless sensor networks with a balanced trade-off among competing parameters. Furthermore, we propose SDN (Software Defined Networks) architecture with multiple controllers for constant network monitoring to allow learning agents to adapt according to the dynamics of the network conditions. Simulation results show that our proposed scheme enhances the performance of wireless sensor network under varied conditions, such as the node density and traffic intensity, with a good trade-off among competing performance metrics.

• 한국농공학회논문집
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• 제63권3호
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• pp.13-26
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• 2021

Recent drought events in the South Korea and the magnitude of drought losses indicate the continuing vulnerability of the agricultural drought. Various studies have been performed on drought hazard assessment at the regional scales, but until recently, drought management has been response oriented with little attention to mitigation and preparedness. A vulnerability assessment is introduced in order to preemptively respond to agricultural drought and to predict the occurrence of drought. This paper presents a method for spatial, Geographic Information Systems-based assessment of agricultural drought vulnerability in South Korea. It was hypothesized that the key 14 items that define agricultural drought vulnerability were meteorological, agricultural reservoir, social, and adaptability factors. Also, this study is to analyze agricultural drought vulnerability by comparing vulnerability assessment according to weighting method. The weight of the evaluation elements is expressed through the Analytic Hierarchy Process (AHP), which includes subjective elements such as surveys, and the Entropy method using attribute information of the evaluation items. The agricultural drought vulnerability map was created through development of a numerical weighting scheme to evaluate the drought potential of the classes within each factor. This vulnerability assessment is calculated the vulnerability index based on the weight, and analyze the vulnerable map from 2015 to 2019. The identification of agricultural drought vulnerability is an essential step in addressing the issue of drought vulnerability in the South Korea and can lead to mitigation-oriented drought management and supports government policymaking.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제9권3호
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• pp.206-212
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• 2009

This paper presents an optimized integrated task planning and control approach for manipulating a nonholonomic robot by mobile manipulators. Then, we derive a kinematics model and a mobility of the mobile manipulator(M2) platform considering it as the combined system of the manipulator and the mobile robot. to improve task execution efficiency utilizing the redundancy, optimal trajectory of the mobile manipulator(M2) platform are maintained while it is moving to a new task point. A cost function for optimality can be defined as a combination of the square errors of the desired and actual configurations of the mobile robot and of the task robot. In the combination of the two square errors, a newly defined mobility of a mobile robot is utilized as a weighting index. With the aid of the gradient method, the cost function is minimized, so the path trajectory that the M2 platform generates is optimized. The simulation results of the 2 ink planar nonholonomic M2 platform are given to show the effectiveness of the proposed algorithm.

• 정보관리학회지
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• 제28권1호
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• pp.309-326
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• 2011

기존 메타데이터의 품질 측정 방법은 오류가 발생한 레코드를 단순히 계수하여 그 비율로 품질을 측정하였다. 이러한 한계를 극복하기 위해 메타데이터 요소별로 상대적 중요 정도를 나타내는 가중치를 적용함으로서, 메타데이터 품질을 체계적으로 계량화 하는 측정 방법을 제시하고자 하였다. 구체적인 가중치 부여 방법으로 엔트로피, 이용자 과업, 그리고 이용 통계를 활용하였다. 또한 이들을 결합하여 통합 가중치를 제시하고 실제 서비스 되고 있는 학술지 기사 메타데이터에 적용하였다. 실험 결과, 엔트로피 가중치 방법은 데이터 자체의 특성을 잘 반영하며, 이용자 과업을 적용한 방법은 이용자의 정보요구를 해결하는 필요한 메타데이터 요소를 제시하며, 통합 가중치는 특정 메타데이터 요소의 오류에 영향을 받지 않으면서 균형 잡힌 측정값을 제시하여 계량화 방법에 적합한 것으로 나타났다.

• 한국환경과학회지
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• 제22권3호
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• pp.303-308
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• 2013

This paper proposed a new method for estimating missing values in time series rainfall data. The proposed method integrated the two most widely used estimation methods, general linear model(GLM) and ordinary kriging(OK), by taking a weighted average of covariance matrices derived from each of the two methods. The proposed method was cross-validated using daily rainfall data at thirteen rain gauges in the Hyeong-san River basin. The goodness-of-fit of the proposed method was higher than those of GLM and OK, which can be attributed to the weighting algorithm that was designed to minimize errors caused by violations of assumptions of the two existing methods. This result suggests that the proposed method is more accurate in missing values in time series rainfall data, especially in a region where the assumptions of existing methods are not met, i.e., rainfall varies by season and topography is heterogeneous.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1994년도 추계학술대회 논문집
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• pp.481-486
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• 1994

An image processing and pattern recognition program was developed in order to recognize the nummerinc displays on gas flow meters. the testing process of the accuracy of gas flow meters are to be automated, using the developed software. There are already many known pattern recognition algorithms for recognition of the letters. To upgrade the recognization accuracy, four different algorithms are applied in sequentially in the software. An calculation method to assign the weighting factors for the result of each algorithm was developed. It showed 98% accuracy by the pattern recognition of displaying numbers of gas mwters of 33 differnt types. This pattern recognition system is to be integrated in a industry.

• 자원환경지질
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• 제30권3호
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• pp.241-248
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• 1997

In this study, Ichon basin is selected as study area and regional analysis of geological structure are done by using lineament analysis. The factors which affects slope stability, are chosen, and integrated to database using GIS (Geoscientific Information System). Landsat TM band 4, 5 and 7 are choosen and processed by various image enhancement technique to analyse the regional geological lineaments. Spatial distribution of lineament is analysed through lineament density map and study area can be divided the eight structural domains. Considering environmental geological characteristics of study area, rating and weighting of each factors for slope stability analysis are determined and spatial analysis of regional slope stability is examined through overlaying technique of GIS. The result of areal distribution of slope stability shows that the most unstable area is all over Mt. Buksung, Mt. Daepo, Mt. Songrim and Mt. Yankak.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 1998년도 춘계 학술발표회 논문집 Proceedings of EESK Conference-Spring 1998
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• pp.44-51
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• 1998

A seismic attenuation formula is derived from the intensity maps of medium sized four earthquakes that occurred in the southern part of Korean peninsula. In order to obtain the seismic attenuation formula, the the coefficients of four attenuation equations representing the intensity maps are integrated using the proper weighting factors depending on the credibility of the data are assigned to. The proposed formula shows the trend of attenuation similar to the ones for the Eastern North America for the region within the epicentral distance of 200km, but produces higher attenuation at farther distances. Though the attenuation curve is not derived from the instrumental data, the result could be a useful tool for the analysis of seismic hazard in Korean peninsula.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 G
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• pp.3190-3192
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• 1999

A Novel wide-band wide-tunable current-mode (CM) gamma corrector for HDTV camera applications is proposed. The gamma corrector provides accurate gamma control in a wide range by simple electrical adjustment of weighting amplifiers' gain. It has wide signal bandwidth more than 40MHz sufficient for HDTV video signal processing and is implementable with simple integrated circuit with low power dissipation of 125mW.

• 한국항해항만학회지
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• 제43권5호
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• pp.302-309
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• 2019

This study introduces the navigational environment database(DB) compiling water depth, sediment type and marine managed areas (MMAs) in coastal waters of South Korea. The water depth and sediment data were constructed by combining their sparse points of electronic navigation chart and survey data with high spatial resolution using the inverse distance weighting and natural neighbor interpolation method included in ArcGIS. The MMAs were integrated based on all shapefiles provided by several government agencies using ArcGIS because the areas should be used in an emergency case of ship. To test the validity of the constructed DB, we conducted a test application for grounding and anchoring zones using a ship accident case. The result revealed each area of possible grounding candidates and anchorages is calculated and displayed properly, excluding obstacle places.