• Journal of Korea Water Resources Association
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• v.51 no.9
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• pp.747-759
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• 2018

Multivariate regional frequency analysis has advantages of regional and multivariate framework as adopting a large number of regional dataset and modeling phenomena that cannot be considered in the univariate frequency analysis. To the best of our knowledge, the multivariate regional frequency analysis has not been employed for hydrological variables in South Korea. Applicability of the multivariate regional frequency analysis should be investigated for the hydrological variable in South Korea in order to improve our capacity to model the hydrological variables. The current study focused on estimating parameters of regional copula and regional marginal models, selecting the most appropriate distribution models, and estimating regional multivariate growth curve in the multivariate regional frequency analysis. Annual maximum rainfall and duration data observed at 71 stations were used for the analysis. The results of the current study indicate that Frank and Gumbel copula models were selected as the most appropriate regional copula models for the employed regions. Several distributions, e.g. Gumbel and log-normal, were the representative regional marginal models. Based on relative root mean square error of the quantile growth curves, the multivariate regional frequency analysis provided more stable and accurate quantiles than the multivariate at-site frequency analysis, especially for long return periods. Application of regional frequency analysis in bivariate rainfall-duration analysis can provide more stable quantile estimation for hydraulic infrastructure design criteria and accurate modelling of rainfall-duration relationship.

• Information and Communications Magazine
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• v.24 no.4
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• pp.27-35
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• 2007

음성 통신을 할 때 배경 잡음이 존재하게 되면 일반적으로 음질이 저하된다. 이것은 잡음 자체가 듣기 싫다거나 음성을 더 작게 들리게 만들기 때문이기도 하고 음성 코덱이 잡음이 섞이지 않은 깨끗한 음성에 최적화되어 있어서 잡음이 섞인 음성에 대한 코딩 효율이 떨어지기 때문이기도 하다. 이 논문에서는 잡음에 의한 음성 통신의 품질 저하를 막기 위한 방법으로서 음성 향상(speech enhancement) 기술과 음성 강화(speech reinforcement) 기술에 대해 소개한다. 음성 향상 기술이란 전송부의 마이크에서 녹음된 잡음과 음성이 섞인 입력 음성으로부터 깨끗한 음성을 추정하는 기술을 말한다. 음성 향상 기술은 상당히 오랜 기간 동안 연구되어 온 기술이며, 최근에는 각 파라미터의 분포에 의존하는 방법보다 확률 모델에 기반한 방법이 각광을 받고 있으며 인간의 청각 특성을 고려한 음성 향상 방법도 제안되고 있다. 음성 강화 기술이란 수신단에서 주변 잡음에 따라 전송되어 온 음성을 주파수별로 증폭하여 더 잘 들리도록 만드는 기술이다. 음성 향상이 내 주위의 잡음이 상대방에게 들리는 음성에 미치는 영향 혹은 상대방 주변의 잡음이 나에게 들리는 소리에 미치는 영향을 줄여주는 기술이라면 음성 강화는 내 주위의 잡음이 나에게 들리는 음성에 미치는 영향을 상쇄해 주는 기술이다. 이 경우 주변 잡음은 어떤 전자 시스템도 거치지 않고 귀로 직접 들어오기 때문에 잡음 자체를 줄여 주는 것은 힘들고 전송되어 온 음성을 적절히 증폭 혹은 변형함으로써 귀에 들리는 음질 또는 명료성을 개선하게 된다. 이 논문에서는 통계 모델을 기반으로 한 음성 향상 기법과 인간의 청각 특성을 고려한 음성 향상 기법, 그리고 음성 강화 기법에 대해 설명한다.을 시도한 결과 안정적이고 반복 가능한 급성 심부전 모델을 얻을 수 있었다. bench scale실험결과와 같이 AOC는 배수관망에서의 박테리아 증식과 크게 상관관계를 갖고 있는 것으로 밝혀졌다.)', 'have a headache (2.10±0.79)', 'poor memory (2.09±0.83)', 'no appetite (1.99±0.85)', As for the correlation between iron parameter and clinical symptoms related to anemia, the hematocrit rate was negatively correlated with 'get a cold easily', 'pale face', 'feeling blue', 'difficult digestion' (p<0.05). The level of iron was negatively correlated with 'tired out easily', 'get a cold easily' (p<0.05) and TS (%) were negatively correlated with 'tired out easily (p<0.05)', 'get a cold easily (p<0.01). Our study resulted that the prevalence of a iron deficiency of a middle school girl is very high, therefore the guidelines for iron supplementation and nutritional education to improve their iron status should be provided.한 질소제거를 N-balance로부터

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.3
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• pp.360-369
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• 2012

Parent material, climate, topography, biological factors, and time are considered five soil forming factors. This study was conducted to elucidate the effects of several environment factors on soil distribution using quantitative analysis method, called soil series estimation algorithm in the soils of Jeju Island. We selected environment factors including mean temperature, annual precipitation, surface geology, altitude, slope, aspect, altitude difference within 1 $km^2$ area, topographic wetness index, distance from the shore, distance from the mountain peak, and landuse for a quantitative analysis. We analyzed the ranges of environment factors for each soil series and calculated probabilities of possible-soil series for certain locations using estimation algorithm. The algorithm can predicted exact soil series on the soil map with correctness of 33% on $1^{st}$ ranking, 62% within $2^{nd}$ ranking, 74% within $5^{th}$ ranking after estimating using randomly extracted environment factors. In predicted soil map, soil sequences of Entisols-Alfisols-Andisols on northern area and Alfisols-Ultisols-Andisols on western area can be suggested along increasing altitude. More modeling studies will be needed for the genesis process of soils in Jeju Island.

• Korean Journal of Environmental Biology
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• v.40 no.2
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• pp.214-223
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• 2022

Among migratory insect pests, Mythimna seperata and Cnaphalocrocis medinalis are invasive pests introduced into South Korea through westerlies from southern China. M. seperata and C. medinalis are insect pests that use rice as a host. They injure rice leaves and inhibit rice growth. To understand the distribution of M. seperata and C. medinalis, it is important to understand environmental factors such as temperature and humidity of their habitat. This study predicted current and future habitat suitability models for understanding the distribution of M. seperata and C. medinalis. Occurrence data, SSPs (Shared Socio-economic Pathways) scenario, and RCP (Representative Concentration Pathway) were applied to MaxEnt (Maximum Entropy), a machine learning model among SDM (Species Distribution Model). As a result, M. seperata and C. medinalis are aggregated on the west and south coasts where they have a host after migration from China. As a result of MaxEnt analysis, the contribution was high in the order of Land-cover data and DEM (Digital Elevation Model). In bioclimatic variables, BIO_4 (Temperature seasonality) was high in M. seperata and BIO_2 (Mean Diurnal Range) was found in C. medinalis. The habitat suitability model predicted that M. seperata and C. medinalis could inhabit most rice paddies.

• Journal of Broadcast Engineering
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• v.18 no.3
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• pp.401-408
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• 2013

In this paper, we propose a method that automatically detects organs having similar appearances in medical images by learning both context and appearance features. Since only the appearance feature is used to learn the classifier in most existing detection methods, detection errors occur when the medical images include multiple organs having similar appearances. In the proposed method, based on the probabilities acquired by the appearance-based classifier, new classifier containing the context feature is created by iteratively learning the characteristics of probability distribution around the interest voxel. Furthermore, both the efficiency and the accuracy are improved through 'region based voting scheme' in test stage. To evaluate the performance of the proposed method, we detect femur and tibia which have similar appearance from SKI10 knee joint dataset. The proposed method outperformed the detection method only using appearance feature in aspect of overall detection performance.

• Korean Journal of Remote Sensing
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• v.21 no.6
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• pp.493-503
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• 2005

In this study, the weight of evidence(WofE) technique based on GIS was applied to spatially estimate the groundwater yield characteristics at the Pocheon area In Gyunggi-do. The groundwater preservation depends on many hydro-geologic factors that include hydrologic data, land-use data, topographic data, geological map and other natural materials collected at the site, even with man-made things. All these data can be digitally processed and managed by GIS database. In the applied technique of WofE, the prior probabilities were estimated as the factors that affect the yield on lineament, geology, drainage pattern or river system density, landuse and soil. We calculated the value of the weight values, W+ and W-, of each factor and estimated the contrast value of it. Results by the groundwater yield characteristic computation using this scheme were presented feasibility map in the form of the posterior probability to the consideration of in-situ samples. It is concluded that this technique is regarded as one of the effective techniques for the feasibility mapping related to the estimation of groundwater-bearing potential zones and its spatial pattern.

• Journal of Korea Water Resources Association
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• v.54 no.9
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• pp.705-718
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• 2021

Climate change has a significant impact on vegetation growth and terrestrial ecosystems. In this study, the possibility of ecological drought was investigated using satellite remote sensing data. First, the Vegetation Health Index was estimated from the Normalized Difference Vegetation Index and Land Surface Temperature provided by MODIS. Then, a joint probability model was constructed to estimate the possibility of vegetation-related drought in various precipitation/evaporation scenarios in forest areas around 60 major ASOS sites of the Meteorological Administration located throughout Korea. The results of this study show the risk pattern of drought related to forest vegetation under conditions of low atmospheric moisture supply or high atmospheric moisture demand. It also identifies the sensitivity of drought risks associated with forest vegetation under various meterological drought conditions. These findings provide insights for decision makers to assess drought risk and develop drought mitigation strategies related to forest vegetation in a warming era.

• Journal of Advanced Navigation Technology
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• v.27 no.6
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• pp.888-896
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• 2023

When an aircraft is landing, it is expected that the aircraft will follow a specified approach procedure and then land at the airport. However, depending on the airport situation, neighbouring aircraft or the instructions of the air traffic controller, there can be a deviation from the specified approach. Detecting aircraft approach patterns is necessary for traffic flow and flight safety, and this paper suggests clustering techniques to identify aircraft patterns in the approach segment. The Gaussian Mixture Model (GMM), one of the machine learning techniques, is used to cluster the trajectories of aircraft, and ADS-B data from aircraft landing at the Gimhae airport in 2019 are used. The aircraft trajectories are clustered on the plane, and a total of 86 approach trajectory patterns are extracted using the centroid value of each cluster. Considering the correlation between the approach procedure pattern and overshoots, the distribution of overshoots is calculated.

• The KIPS Transactions:PartB
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• v.17B no.2
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• pp.107-114
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• 2010

A guitar, a piano, and a violin are popular musical instruments for User Created Contents(UCC). However the patterns of audio signal generated by a guitar and a piano are too similar to differentiate. The difference between two musical instruments can be found by analyzing the frequency variation per each band near signal peaks. The distribution of probability on the existence of signal peaks based on Cumulative Histogram were applied to musical instrument recognition. Experiments with statistical models of the frequency variation per each band near signal peaks showed the 14% improvement of musical instrument recognition.

• Journal of Advanced Navigation Technology
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• v.16 no.3
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• pp.471-479
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• 2012

In cellular femto systems, femto Base stations(f-BSs) can be installed unnecessarily and overcrowded in small areas. This will cause an interference problem and it can impact on the capacity, blocking probability, and coverage of femtocells in the shared channel systems. In this paper, we propose a load distribution scheme by using forced handover and probabilistic subchannel scheduling policy to resolve the problem. The proposed scheme operates in distributed manner though communication with neighboring f-BSs, and includes self-detection of overcrowded area and radio resource management based on measurements. We evaluate the performance of the proposed scheme in terms of average cell throughput and average throughput per users.