• 한국환경과학회지
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• 제26권10호
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• pp.1167-1180
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• 2017

Numerical Weather Prediction (NWP) models such as the Weather Research and Forecasting (WRF) model are essential for forecasting one-day-ahead solar irradiance. In order to evaluate the performance of the WRF in forecasting solar irradiance over the Korean Peninsula, we compared WRF prediction data from 2008 to 2010 corresponding to weather observation data (OBS) from the Korean Meteorological Administration (KMA). The WRF model showed poor performance at polluted regions such as Seoul and Suwon where the relative Root Mean Square Error (rRMSE) is over 30%. Predictions by the WRF model alone had a large amount of potential error because of the lack of actual aerosol radiative feedbacks. For the purpose of reducing this error induced by atmospheric particles, i.e., aerosols, the WRF model was coupled with the Community Multiscale Air Quality (CMAQ) model. The coupled system makes it possible to estimate the radiative feedbacks of aerosols on the solar irradiance. As a result, the solar irradiance estimated by the coupled system showed a strong dependence on both the aerosol spatial distributions and the associated optical properties. In the NF (No Feedback) case, which refers to the WRF-only stimulated system without aerosol feedbacks, the GHI was overestimated by $50-200W\;m^{-2}$ compared with OBS derived values at each site. In the YF (Yes Feedback) case, in contrast, which refers to the WRF-CMAQ two-way coupled system, the rRMSE was significantly improved by 3.1-3.7% at Suwon and Seoul where the Particulate Matter (PM) concentrations, specifically, those related to the $PM_{10}$ size fraction, were over $100{\mu}g\;m^{-3}$. Thus, the coupled system showed promise for acquiring more accurate solar irradiance forecasts.

• 대기
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• 제31권4호
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• pp.433-443
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• 2021

The wind speed and wind direction in Yeongdong are one of the crucial meteorological factors for forecasting snowfall in this area. To improve the snowfall forecast in Yeongdong region, Yeongdong Extreme Snowfall-Windstorm Experiment, YES-WEX was designed. We examined the wind field variation simulated with Local Data Assimilation and Prediction System (LDAPS) using observed wind field during YES-WEX period. The simulated wind speed was overestimated over the East Sea and especially 2 to 4 times in the coastal line. The vertical wind in Yeongdong region, which is a crucial factor in the snowfall forecast, was not well simulated at the low level (850 hPa~1000 hPa) until 12 hours before the forecast. The snowfall distribution was also not accurately simulated. Three hours after the snowfall on the East Sea coast was observed, the snowfall was simulated. To improve the forecast accuracy of snowfall in Yeongdong region, it is important to understand the weather conditions using the observed and simulated data. In the future, data in the northern part of the East Sea and the mountain slope of Taebaek observed from the meteorological aircraft, ship, and drone would help in understanding the snowfall phenomenon and improving forecasts.

• 한국방재안전학회논문집
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• 제16권2호
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• pp.49-56
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• 2023

영향예보는 기존의 기상요소 중심의 예보에서 벗어나 기상상황에 따른 잠재적 사회경제적 위험도 정보를 함께 제공하는 것을 의미한다. 기상 선진국들은 영향정보 제공 및 확산을 위한 기술개발에 인력과 재정을 투입하고 있지만 국내에서는 영향예보에 대한 인식이 확산되어 있지 않다. 또한 영향예보 피해가 많이 발생하는 홍수, 태풍 등의 재난에 초점이 맞춰져 있으며 상대적으로 피해발생이 적은 교통 분야의 강풍으로 인한 차량 위험 영향 평가에 대한 연구는 부족한 실정이다. 국내에서는 강풍으로 인한 차량 전도에 대한 피해 사례는 많이 없지만 과거 피해 사례가 존재하며 연구에 대한 필요성이 높아지고 있다. 강풍으로 인한 차량의 위험(Risk) 평가를 위해서는 도로의 취약성(Vulnerability)이 필요하며 본 연구에서는 도로의 취약성 기준을 산정하는 것을 목적으로 하였다. 도로의 취약성 평가는 도로의 고도, 차선 수, 도로 유형으로 평가하였다. 분석결과 사고사례가 있던 지역의 취약성 지역을 잘 재현하는 것으로 나타났다. 본 연구의 성과를 이용하여 차량 운전자에게 잠재적 위험에 대한 객관적인 평가 마련에 대한 기준으로 활용할 수 있을 것이라 판단된다.

• 대기
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• 제28권2호
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• pp.141-151
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• 2018

The KIAPS global model and data assimilation system were extended to assimilate brightness temperature from the Sondeur $Atmosph{\acute{e}}rique$ du Profil $d^{\prime}Humidit{\acute{e}}$ Intertropicale par $Radiom{\acute{e}}trie$ (SAPHIR) passive microwave water vapor sounder on board the Megha-Tropiques satellite. Quality control procedures were developed to assess the SAPHIR data quality for assimilating clear-sky observations over the ocean, and to characterize observation biases and errors. In the global cycle, additional assimilation of SAPHIR observation shows globally significant benefits for 1.5% reduction of the humidity root-mean-square difference (RMSD) against European Centre for Medium-Range Weather Forecasts (ECMWF) Integrated Forecast System (IFS) analysis. The positive forecast impacts for the humidity and temperature in the experiment assimilating SAPHIR were predominant at later lead times between 96- and 168-hour. Even though its spatial coverage is confined to lower latitudes of $30^{\circ}S-30^{\circ}N$ and the observable variable is humidity, the assimilation of SAPHIR has a positive impact on the other variables over the mid-latitude domain. Verification showed a 3% reduction of the humidity RMSD with assimilating SAPHIR, and moreover temperature, zonal wind and surface pressure RMSDs were reduced up to 3%, 5% and 7% near the tropical and mid-latitude regions, respectively.

• 한국농림기상학회지
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• 제19권3호
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• pp.180-194
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• 2017

기상위험에 선제적으로 대응할 수 있도록 하기 위하여 농장별 정밀 날씨추정, 작목별 기상위험의 알림과 대응지침의 전달 등 개별 농가 단위의 농업기상위험 관리 기술이 본 연구의 선행 성과물로 개발된 바 있다. 현재 470 자원 농가와 950농장을 대상으로 시군 단위로 관내 농장의 날씨와 기상위험 현황을 시각적으로 파악할 수 있는 GIS 기반 분포형 경보 시스템이 구축되어 현업 서비스가 운영 중이다(http://www.agmet.kr). 그러나 모든 농가를 서비스 대상으로 하다 보니 많은 작목과 기상위험요소가 나열되어 개별 농가가 시스템에 접속하여 자기 농장만의 농업기상위험 정보를 확인하기에는 불편한 사항이 많다. 따라서 개별 농장별로 정보 확인 편의성을 위하여 휴대전화 번호만을 이용하여 자기 농장만의 날씨, 작목의 생육단계, 작목 기상위험을 최대 미래 9일까지 조회하고, 기상특보 및 기상위험 주의, 경보 수준을 알림 정보로 제공받을 수 있는 농업기상재해 조기경보 모바일용 어플리케이션을 개발하였다. 스마트폰으로 본 시스템에 접속하여 농장별 날씨와 재배작목의 생육단계, 생육단계별 기상위험과 대응지침을 제공 받는 등 농장별로 특화된 기상위험을 사전 경고 정보로 신속하게 확인할 수 있다. 자기 농장만의 과거부터 미래까지 날씨와 기상위험을 단순하고 보기 쉽게 정리하여 농가에 제공함으로써 기존의 GIS 기반 기상위험 분포형 경보 시스템이 가진 정보 접근 불편함을 해소하였다.

• 대기
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• 제21권4호
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• pp.391-404
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• 2011

This study investigates the impact of cumulus parameterization scheme (CPS) with different horizontal grid sizes on the simulation of the local heavy rainfall case over the Korean Peninsula. The Weather Research and Forecasting (WRF)-based real-time forecast system of the Joint Center for High-impact Weather and Climate Research (JHWC) is used. Three CPSs are used for sensitivity experiments: the BMJ (Betts-Miller-Janjic), GD (Grell-Devenyi ensemble), and KF (Kain-Fritsch) CPSs. The heavy rainfall case selected in this study is characterized by low-level jet and low-level transport of warm and moist air. In 27-km simulations (DM1), simulated precipitation is overestimated in the experiment with BMJ scheme, and it is underestimated with GD scheme. The experiment with KF scheme shows well-developed precipitation cells in the southern and the central region of the Korean Peninsula, which are similar to the observations. All schemes show wet bias and cold bias in the lower troposphere. The simulated rainfall in 27-km horizontal resolution has influence on rainfall forecast in 9-km horizontal resolution, so the statements on 27-km horizontal resolution can be applied to 9-km horizontal resolution. In the sensitivity experiments of CPS for DM3 (3-km resolution), the experiment with BMJ scheme shows better heavy rainfall forecast than the other experiments. The experiments with CPS in 3-km horizontal resolution improve rainfall forecasts compared to the experiments without CPS, especially in rainfall distribution. The experiments with CPS show lower LCL(Lifted Condensation Level) than those without CPS at the maximum rainfall point, and weaker vertical velocity is simulated in the experiments with CPS compared to the experiments without CPS. It means that CPS suppresses convective instability and influences mainly convective rainfall. Consequently, heavy rainfall simulation with BMJ CPS is better than the other CPSs, and even in 3-km horizontal resolution, CPS should be applied to control convective instability. This conclusion can be generalized by conducting more experiments for a variety of cases over the Korean Peninsula.

• 해양환경안전학회:학술대회논문집
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• 해양환경안전학회 2003년도 추계학술발표회
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• pp.163-166
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• 2003

The seasonal mean wind direction and wind speed in a greater coasting area are investigated using the ECMWF(European Centre for Medium-Range Weather Forecasts) data for 11 years from 1985 to 1995. In winter, the main wind direction in Korea and vicinity, Taiwan and vicinity, and the North Pacific Ocean of middle latitudes is a northwesterly wind, northeasterly wind, and westerly wind respectively. The wind speed is strongest in the East China Sea, the South China Sea, and the North Pacific Ocean of low latitudes(Beaufort wind scale 5-6). A distribution pattern of wind direction in spring and fall is similar to that in winter. Seasonal mean wind speed is strongest in winter and the next is fall. The wind speed in summer is generally weak. However, that in the Indochina and vicinity is strong by the influence of Asian monsoon.

• The Journal of the Acoustical Society of Korea
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• 제23권3E호
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• pp.91-97
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• 2004

In this paper, we propose a classification system of TV program scenes based on audio information. The system classifies the video scene into six categories of commercials, basketball games, football games, news reports, weather forecasts and music videos. Two type of audio feature set are extracted from each audio frame-timbral features and coefficient domain features which result in 58-dimensional feature vector. In order to reduce the computational complexity of the system, 58-dimensional feature set is further optimized to yield l0-dimensional features through Sequential Forward Selection (SFS) method. This down-sized feature set is finally used to train and classify the given TV program scenes using κ -NN, Gaussian pattern matching algorithm. The classification result of 91.6% reported here shows the promising performance of the video scene classification based on the audio information. Finally, the system stability problem corresponding to different query length is investigated.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 1992년도 춘계학술발표회 한국항해학회
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• pp.21-43
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• 1992

The recently-developed automated vessels require a system which evaluates the operating condition of the ship at present position form weather information as well as sensors; forecasts the operation condition the sea state to come in foreseeable future ; and suggests the optimum course and speed for ship's sa-fety. According to a study deck wetness propeller racing slamming rolling vertical acceleration lateral acce-leartion vertical bending moment at midship etc. were chosen as the factors for evaluating seakeeping per-formance. As a mater of fact there is no developing the hardware of a system which could consider all the factors onseakeeping performance. This study introduces a theoretical method which makes it possible to evaluate the seakeeping perfor-mance byapplying a theory from reliability engineering and thereby establishing a safety space. lation of stochastic processes with the factors presently adopted for evaluating sekakeeping performance. and develops the overall eseakeeping performance evaluation system in consideration of the safety of human being cargoes and the ship This method of evaluation shall be of much use in developing the practical system of seakeeping perfor-mance of a ship in waves.

• 설비공학논문집
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• 제24권11호
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• pp.759-766
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• 2012

To estimate the cooling load for the following day, outdoor temperature and humidity are needed in hourly base. But the meteorological administration forecasts only maximum and minimum temperature. New methodology is proposed for predicting hourly outdoor temperature and humidity by using the forecasted maximum and minimum temperature. The correlations for normalized outdoor temperature and specific humidity has been derived from the weather data for five years at Seoul, Daejeon and Pusan. The correlations for normalized temperature are independent of date, while the correlations for specific humidity are linearly dependent on date. The predicted results show fairly good agreement with the measured data. The prediction program is also developed for hourly outdoor dry bulb temperature, specific humidity, dew point, relative humidity, enthalpy and specific volume.