• 한국태양에너지학회 논문집
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• 제37권5호
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• pp.1-11
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• 2017

A study on Nacelle Lidar (Light detection and ranging) measurement error and the data reliability verification was carried out at Haengwon wind farm on Jeju Island. For measurement data error processing, the characteristics of Nacelle Lidar measurements were analyzed by dividing into three parts, which are weather conditions (temperature, humidity, atmosphere, amount of precipitation), mechanical movement (rotation of wind turbine blades, tilt variation of Nacelle Lidar) and Nacelle Lidar data availability. After processing the measurement error, the reliability of Nacelle Lidar data was assessed by comparing with wind data by an anemometer on a met mast, which is located at a distance of 200m from the wind turbine with Nacelle Lidar. As a result, various weather conditions and mechanical movement did not disturb reliable data measurement. Nacelle Lidar data with availability of 95% or more could be used for checking Nacelle Lidar wind data reliability. The reliability of Nacelle Lidar data was very high with regression coefficient of 98% and coefficient of determination of 97%.

• 한국전자통신학회논문지
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• 제8권11호
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• pp.1647-1654
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• 2013

실외 도로에서의 차량 검출 성능은 기상 상태, 태양 이동에 의한 그림자, 조도 변화 등에 영향을 받는다. 본 논문에서는 낮 시간대의 실외도로에서 이러한 주변 환경변화에 강건한 배경 추정 알고리즘과 연동한 차량 검출 시스템을 제안한다. 배경 추정 알고리즘은 혼합 가우시안 모델을 적용하고 후보 영역에 대한 차량 검출은 Adaboost 알고리즘을 적용하였다. 흐린 날, 비오는 날 등 동일한 실제 도로에서 서로 다른 기후에 획득한 CCTV 비디오 영상을 사용한 실험을 통해 제안하는 방법이 일반 도로에서의 차량 검출에 유용한 것을 확인하였다.

• 전력전자학회논문지
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• 제25권1호
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• pp.1-5
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• 2020

Solar power generation systems require maximum power point tracking (MPPT) control to operate PV panels at their maximum power point (MPP). Most conventional MPPT algorithms are based on the slope-tracking concept. A typical slope-tracking method is the perturb and observe (P&O) algorithm. The P&O algorithm measures the current and voltage of a PV panel to find the operating point of the voltage at which the calculated power is maximized. However, the measurement error of the sensor causes irregularity in the calculation of the generated power and voltage control. This irregularity leads to the problem of not finding the correct MPP operating point. In this work, the power output of a PV panel based on the P&O algorithm is simulated by considering the insolation profiles from typical clear and cloudy weather conditions and the errors of current and voltage sensors. Simulation analysis suggests the optimal control period and perturbation voltage of MPPT to maximize its target efficiency under real weather conditions with sensor tolerance.

• 한국정보통신학회논문지
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• 제12권11호
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• pp.1939-1946
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• 2008

전국 수역의 녹조 및 해파리 발생, 유류오염 등에 의한 해양 생태계 파괴에 따른 심각한 문제에 따라 해양의 상태를 공중과 해양에서 관측할 수 있는 방법으로 헬기나 선박을 통원하는 조사 방법은 고유가 시대의 유류비 및 인건비 등의 예산문제로 년 중 사용회수는 극히 제한되어 있으며 일기가 좋지 않을 때에는 아예 출동조차 못하고 있는 실정이다. 이를 극복하기 위해 해양에서 발생하는 제반사항을 악천후에도 무인으로 고 품질의 해양 환경 측정 및 모니터링 조사를 자동으로 할 수 있는 무인 자동 모니터링 시스템이 유지비가 거의 들지 않고 인건비 유류비를 절약할 수 있을 뿐만 아니라, 각 센서들의 네트워크화, 측위기반 센싱 기법을 적용할 경우 조수가 있는 해양에서 센서의 위치 변동과 현재 위치를 파악할 수 있어 조사내용의 양과 질을 높일 수 있는 장점을 갖는다.

• 국제학술발표논문집
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• The 9th International Conference on Construction Engineering and Project Management
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• pp.616-623
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• 2022

Some regions and states, such as Wyoming, have harsh weather conditions, forcing most transportation projects to be completed under tight schedules. However, construction projects are not only delayed by weather conditions, but also delayed by other factors such as contractor's competency, resource availability, coordination issues, and safety. Also, the construction method, geographical location of the projects, and inability to follow baseline schedules accurately due to the contractor's resource allocation are also reasons for the delay. This paper discusses the main reasons for the delay in the public transportation projects based on Daily Work Reports (DWRs) from five different transportation projects of the last three years in Wyoming. This paper focuses on the inconsistencies of the contractor's schedules to complete the project according to the baseline schedule. First, the authors collected DWRs and baseline schedules from the Wyoming Department of Transportation (WYDOT). Second, the DWR data are compared against the baseline schedules to determine the reasons for delaying their significance. Finally, the paper presents the recommendations to mitigate the effects of delays on public transportation projects as well as to improve the documentation process of DWR data.

• 한국농공학회논문집
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• 제65권5호
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• pp.81-91
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• 2023

As abnormal weather conditions escalate, water disasters such as droughts and floods occur more frequently. These natural disasters are fatal to agricultural reservoirs, where the operation techniques vary greatly depending on the season and weather conditions, and response through intake works is limited. In response, governments like the Korea Rural Community Corporation have researched efficient water supply methods through irrigation channels. Therefore, previous studies analyzed the irrigation process using numerical models to determine an efficient irrigation system. However, SWMM and EPANET used in previous studies are limited in quantitative agricultural irrigation process analysis. Therefore, this study developed AIRISS to simulate and analyze agricultural irrigation. Specifically, we simulated the irrigation process in the Ssangbong area of South Korea and simulated the irrigation process to verify the performance of the numerical model. AIRISS, developed in this study, is specialized in simulating the agricultural irrigation process. It can check the supply to each paddy and the condition of each paddy.

• 천문학논총
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• 제38권3호
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• pp.111-123
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• 2023

In this study, quantitative analysis is attempted on data collected from Chilgapsan Observatory Star Park in Cheongyang-gun, Chungcheongnam-do. The aim of this experimental study in which quantitative analysis of the Astronomical Science Museum in Korea is conducted is to investigate its current situation and secure basic data. As of July 31, 2023, it has had 283,931 cumulative visitors in total. It had the largest number of visitors when it opened (2009 year), after which their number reduced steadily until the pandemic (COVID-19, 2020-2022). Recently, however, the number of visitors has increased. Generally, the number of visitors is highest in August (20.8%) and least in April (4.1%). The visit rate is higher on weekends (Saturday and Sunday) than on weekdays (Monday-Friday), and groups comprise only about 5.3% of the total number of visitors. Moreover, it can be confirmed that the number of visitors increases sharply during events. Finally, it was confirmed that the visit rate was unaffected by weather conditions. Considering these results, we propose the following strategies: 1) Establish a special program that reflects "the weekend effect." 2) Prepare a plan to attract group visitors during the weekdays using "the event effect." 3) Arrange alternative programs (e.g., experiential activities) that can be conducted indoors regardless of weather conditions. We think that our findings will help establish a roadmap for the direction the Astronomical Science Museum should take and aid in preparing a strategic foundation to preemptively respond to unexpected situations (e.g., pandemics).

• 한국환경과학회지
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• 제33권7호
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• pp.523-532
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• 2024

In popular tourist destinations such as Jeju and Gangwon, electric rental cars are increasingly adopted. However, sudden battery drain due to weather conditions can pose safety issues. To address this, we developed a battery consumption analysis model that considers resistive energy factors such as acceleration, rolling resistance, and aerodynamic drag. Focusing on the effects of ambient temperature and wind speed, the model's performance was evaluated during an empirical validation period from November to December 2023. Comparing predicted and actual state of charge (SoC) across different routes identified ambient temperature, wind speed, and driving time as major sources of error. The mean absolute error (MAE) increased with lower temperatures due to reduced battery efficiency. Higher wind speeds on routes 1 and 6 resulted in larger errors, indicating the model's limitation in considering only tailwinds for aerodynamic drag calculations. Additionally, longer driving times led to higher actual SoC than predicted, suggesting the need to account for varying driver habits influenced by road conditions. Our model, providing more accurate SoC predictions to prevent battery depletion incidents, shows high potential for application in navigation apps for electric vehicle users in tourist areas. Future research should endeavor to the model by including wind direction, HVAC system usage, and braking frequency to improve prediction accuracy further.

• 대기
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• 제29권4호
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• pp.463-480
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• 2019

This study classified heavy rain types from K-means clustering for the hourly relationship between rainfall intensity and cloud top height over the Korean peninsula, and then examined their statistical characteristics for the period of June~August 2013~2018. Total rainfall amount of warm-type events was 2.65 times larger than that of the cold-type, whereas the lightning frequency divided by total rainfall for the warm-type was only 46% of the cold-type. Typical cold-type cases exhibited high cloud top height around 16 km, large reflectivity in the upper layer, and frequent lightning flashes under convectively unstable condition. Phenomenally, the cold-type cases corresponded to cloud cluster or multi-cell thunderstorms. However, two warm-type cases related to Changma and typhoon were characterized by heavy rainfall due to long duration, relatively low cloud top height and upper-level reflectivity, and the absence of lightning under the convectively neutral and extremely humid conditions. This study further confirmed that the forecast skill of rainfall could be improved by applying correction factor with the overestimation for cold-type and underestimation for warm-type cases in the Local Data Assimilation and Prediction System (LDAPS) operational model (e.g., BIAS score was improved by 5%).

• 전기학회논문지
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• 제56권10호
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• pp.1791-1795
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• 2007

Small ions generated at conductor corona sources remain in the atmosphere until they recombine with ions of opposite polarity, attach to aerosols, or make contact with an object. Ion current density is major factor to design conductor configuration of DC overhead transmission line. Several techniques have been used to measure the ion current of HVDC overhead transmission line. In this study, the ion current density was measured by a plate electrode made of a metal flat board at DC corona cage. The sensitivity of the plate electrode is $0.156uA/m^2/V$. To obtain an useful database on corona discharge, it is necessary to do corona test on several kinds of conductor bundles. Therefore, a number of experiments were conducted on several kinds of conductor bundles. To reliably analyze ion effects, corona cage test data were obtained over a long period of time under various weather conditions and expressed as a statistical distribution. Ion current density distribution in foul weather shows a significant increase in levels over the corresponding fair weather. Based on this results, we evaluated the environmental characteristic caused by ion flow of three candidated conductor bundles.