• 응용통계연구
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• 제30권2호
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• pp.271-280
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• 2017

우리나라 뉴스에서 매일 빠지지 않는 내용은 아마도 부동산 경제에 관한 것이라고 생각된다. 많은 사람들은 부동산 가격의 변동에 관한 전문가들의 예측에 관심을 갖고 있다. 매매가격 혹은 전세가격을 예측하기위해 일반적으로 많이 사용되는 방법은 박스-젠킨스에 기반을 둔 자기회귀이동평균모형이다. 본 논문에서는 자기회귀모형과 다변량 자료분석에서 사용하는 독립성분분석을 결합하여 예측하는 방법을 시도하여 보았다. 매매가격과 전세가격을 두 개의 독립성분으로 재설정하고 독립성분들을 이용하여 예측한 후 역변환을 통해 매매가격과 전세가격을 예측하는 방법을 시도하였다. 그 결과 일반적인 자기회귀이동평균모형을 사용할 때 보다 독립성분을 활용한 예측이 실제 지수에 더 유사한 값들을 얻을 수 있음을 보였다.

• 응용통계연구
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• 제32권6호
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• pp.851-865
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• 2019

하나의 시계열 자료에서 다양한 특징을 발견하는 일은 간단한 문제가 아니다. 본 논문에서는 하나의 시계열 자료에서 복수의 패턴을 찾아내어 예측 정확도를 높이는 방식인 다중 결합 예측 알고리즘을 소개한다. 이 알고리즘은 시간적 결합과 예측값 조합의 개념을 사용한다. 시간적 결합 방식을 통해, 하나의 시계열 자료에서 여러 개의 시계열 자료를 생성할 수 있으며, 각각의 자료는 별도의 특성을 가지게 된다. 여러 개의 시계열 자료에서 다양한 특성을 추출하기 위하여 지수평활법을 사용하고 시계열 요소들 및 이들의 예측값을 계산한다. 마지막 단계에서 시계열 요소 별로 예측값을 혼합 한 후, 각 시계열 요소들의 조합값을 더하여 최종 예측값을 만든다. 실증 분석으로 국내 교통사고 발생 건수를 예측한다. 분석 결과, 기존의 다른 예측 방식보다 예측 성능이 우수함을 확인할 수 있다.

• 천문학회보
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• 제38권1호
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• pp.63.1-63.1
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• 2013

To improve the forecast capability of geomagnetic storms, we consider the real time solar and near Earth conditions together, since the characteristics of CMEs can be modified during their transit from the Sun to the Earth, and the geomagnetic storms may be directly affected by not only solar events but also near Earth interplanetary conditions. Using 55 CME-Dst pairs associated with M- and X-class solar flares, which have clearly identifiable source regions during 1997 to 2003, we confirm that the peak values of negative magnetic field Bz and duskward electric field Ey prior to Dst minimum are strongly related with Dst index. We suggest the solar wind criteria (Bz<-5 nT or Ey>3 mV/m for t>2 hr) for moderate storm less than -50 nT by modifying the criteria for intense storms less than -100 nT proposed by Gonzalez and Tsurutani (GT, 1987). As the results, 90% (28/31) of the storms are correctly forecasted by our criteria. For 15 exceptional events that are incorrectly forecasted by only CME parameters, 12 cases (80%) can be properly forecasted by solar wind criteria. When we applying CME and solar wind conditions together, all geomagnetic storms (Dst<-50 nT) are correctly forecasted. Our results show that, the storm forecast capability of the 2~3 days advanced warning based on CME parameters can be improved by combining with the urgent warning based on the near Earth solar wind condition.

• 정보처리학회논문지B
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• 제16B권1호
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• pp.55-62
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• 2009

협업여과는 추천시스템에서 널리 사용되는 기법으로 다른 사용자의 평가를 기반으로 아이템을 추천하는 기법이다. 사용자 데이터베이스를 이용하는 메모리기반 협업여과에는 사용자기반 기법과 아이템기반 기법이 있다. 사용자기반 협업여과는 유사한 선호도를 가지는 이웃사용자들의 선호도를 바탕으로 특정 아이템에 대한 선호도를 예측하는 반면, 아이템기반 협업여과는 아이템들의 유사도를 바탕으로 특정 사용자의 선호도를 예측한다. 본 논문에서는 추천의 성능을 향상시키기 위하여 이웃사용자와 이웃아이템 크기의 비율을 가중치로 하여 사용자기반 예측값과 아이템기반 예측값을 결합함으로써 최종 예측값을 생성하는 결합예측기법을 제안한다. MovieLens 데이터 셋과 BookCrossing 데이터 셋을 이용한 실험을 통해 본 논문에서 제안한 결합예측기법이 영화와 책에 대하여 사용자기반과 아이템기반보다 예측의 정확성을 향상시킴을 보인다.

• 응용통계연구
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• 제1권2호
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• pp.10-26
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• 1987

미래의 한 관측값이 여러 방법으로 예측되었을 때, 이들 예측값들을 적절한 방법으로 결합 시키면 더 좋은 예측값을 얻을수 있게 된다. 본 논문에서는 결합예측을 위한 기존의 방법들을 간략히 소개하고, 결합 가중치의 추정을 위한 몇가지 대안적 절차를 제시한 후, 국내의 여러 자료들을 이용한 실증적 분석을 통하여 결합방법들에 대한 예측력을 비교 $\cdot$ 검토하게 된다. 실증적 분석 결과에 의하면, 제한 회귀가중치, 제한 로버스트 회귀가중치 및 혼합 회귀 가중치에 의한 결합방법들이 로버스트했다. 그러나 모든 경우에서 항상 가장 우수한 결합 방법은 발견될 수 없으므로 사전적으로 개별예측들의 특성을 분석하여, 대응되는 결합방법을 선책한다면 보다 유용한 예측결과를 얻을수 있게 된다.

• Current Optics and Photonics
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• 제4권3호
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• pp.174-185
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• 2020

Multiscattering occurs when a laser transmits into dense atmosphere targets (e.g. fogs, smoke or clouds), which can cause depolarization effects even though the scattering particles are spherical. In addition, multiscattering effects have additional information about microphysical properties of scatterers. Thus, multiscattering can be utilized to study the microphysical properties of the liquid water cloud. In this paper, a Monte Carlo method was used to simulate multi-scattering transmission properties of Lidar signals in the cloud. The results showed the slope of the degree of linear polarization (SLDLP) can be used to invert the extinction coefficient, and then the cloud effective size (CES) and the liquid water content (LWC) may be easily obtained by using the extinction coefficient and saturation of the degree of linear polarization (SADLP). Based on calculation results, a microphysical properties inversion method for a liquid cloud was presented. An innovative multiscattering polarization Lidar (MSPL) system was constructed to measure the LWC and CES of the liquid cloud, and a new method based on the polarization splitting ratio of the Polarization Beam Splitter (PBS) was developed to calibrate the polarization channels of MSPL. By analyzing the typical observation data of MSPL observation in the northern suburbs of Nanjing, China, the LWC and CES of the liquid water cloud were obtained. Comparisons between the results from the MSPL, MODIS and the Microwave radar data showed that, the microphysical properties of liquid cloud could be retrieved by combining our MSPL and the inversion method.

• 한국멀티미디어학회논문지
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• 제18권6호
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• pp.772-779
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• 2015

Advancing information technology have rapidly changed our service environment of life, culture, and industry. Computer information communication system is applied in medical, health, distribution, and business transaction. Smart is using new information by combining ability of computer and information. Although agriculture is labor intensive industry that requires a lot of hands, agriculture is becoming knowledge-based industry today. In agriculture field, computer communication system is applied on facilities farming and machinery Agricultural. In this paper, we designed and implemented application that provides personalized agriculture related information at the actual farming field. Also, this provides farmer a system that they can directly auction or sell their produced crops. We designed and implemented a system that parsing information of each seasonal, weather condition, market price, region based, crop, and disease and insects through individual setup on ubiquitous environment using location-based sensor network and processing data.

• 대한산업공학회지
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• 제25권4호
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• pp.437-447
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• 1999

Previous researches on risk attitudes or on the typical utility functions have mostly focused on how the risk attitude of decision maker varies when changes are made in one or two lottery reference points such as consequence domain and magnitude of probability under assumed risk situations represented by simple lotteries. It is, however, very difficult to forecast dominant risk attitudes under risk situations which exhibit a complex combination of many reference points. In this study, twelve risk situations which a decision maker may confront in real decision-making situations were formulated by combining in various ways three reference points, that is, magnitude of probability, consequence domain, and magnitude of gain or loss. Then through a questionnaire dominant risk attitudes under every assumed risk situation were investigated, and the general shape of utility function implied by the experimental results were derived. Results of the present study show that none of the three reference points have dominant effect over the others due to complicated interaction between them, and given the twelve risk situations the observed risk attitude widely varies from strong risk taking to strong risk aversion.

• 한국항해학회지
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• 제20권4호
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• pp.1-6
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• 1996

A vessel in distress might be well identified when both the variables affecting the drifting of the vessel and the extent to which the variables affect the drifted vessel are known. And also the disembarking place inside the ship might be easily located if the drifting poised is forecasted. The forecasting method of the drifting poise is resolved by combining the vectors of the current and the wind. It is, however, very hard to forecast the effect of the wind, which should be mainly determined by field survey. This study aims at identifying the drifting characteristics of medium/large ships, considering only the effect of the wind. The experiment revealed the following results. $\circled1$ The drifting poise is determined by the aspect ratio of the ship and the shape of the superstructure of the ship. $\circled2$ Drifting direction is quite stable when wind speed goes over a certain level. $\circled3$ Drifting speed is 3-7% of the wind speed in case of T/S Hannara.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2012년도 학술발표회
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• pp.200-204
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• 2012

In engineering hydrology, an estimation of precipitation loss is one of the most important issues for successful modeling to forecast flooding or evaluate water resources for both surface and subsurface flows in a watershed. An accurate estimation of precipitation loss is required for successful implementation of rainfall-runoff models. Precipitation loss or hydrological abstraction may be defined as the portion of the precipitation that does not contribute to the direct runoff. It may consist of several loss elements or abstractions of precipitation such as infiltration, depression storage, evaporation or evapotranspiration, and interception. A composite loss rate model that combines four loss rates over time is derived as a lumped form of a continuous time function for a storm event. The composite loss rate model developed is an exponential model similar to Horton's infiltration model, but its parameters have different meanings. In this model, the initial loss rate is related to antecedent precipitation amounts prior to a storm event, and the decay factor of the loss rate is a composite decay of four losses.