• Journal of the Korean Association of Geographic Information Studies
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• v.23 no.4
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• pp.156-172
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• 2020

The purpose of this study was to predict road surface temperature using high-resolution solar radiation data. The road surface temperature prediction model (RSTPM) was applied to predict road surface temperature; this model was developed based on the heat-balance method. In addition, using SOLWEIG (SOlar and LongWave Environmental Irradiance Geometry-model), the shadow patterns caused by the terrain effects were analyzed, and high-resolution solar radiation data with 10 m spatial resolution were calculated. To increase the accuracy of the shadow patterns and solar radiation, the day that was modeled had minimal effects from fog, clouds, and precipitation. As a result, shadow areas lasted for a long time at the entrance and exit of a tunnel, and in a high-altitude area. Furthermore, solar radiation clearly decreased in areas affected by shadows, which was reflected in the predicted road surface temperatures. It was confirmed that the road surface temperature should be high at topographically open points and relatively low at higher altitude points. The results of this study could be used to forecast the freezing of sections of road surfaces in winter, and to inform decision making by road managers and drivers.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2002.11a
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• pp.430-431
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• 2002

기상변동에 대한 적절한 해석을 위하여 장기관측을 통한 다양한 지표 생태계에서의 수분 및 에너지 순환에 대한 연구가 진행(Grelle, et al., 1997: Wilson and Baldocchi, 2000)되고 있으며, 모형을 이용한 연구에서도 이에 대한 검증과 보다 정확한 자료의 산출을 위해서 양질의 관측자료가 절대적이라 할 수 있다. 또한 대기에 비하여 상대적으로 그 영향이 오래 지속되는 토양특성에 대한 정확한 토양수분 자료를 사용할 경우 기후 및 기상 예측의 정확도 향상에 크게 기여하는 것으로 알려져 있다(Atlas et al. 1993). (중략)

• Korean Chemical Engineering Research
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• v.52 no.1
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• pp.68-74
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• 2014

In the spiral wound module of the pressure-retarded osmosis (PRO) system for the salinity gradient power generation, effects of the inlet pressure differences between feed-channel and draw-channel were studied. Fluxes of water and solute through membrane and power were estimated. The water flux through membrane decreased along the x-direction and increased along the y-direction with the increase of inlet pressure differences between two channels. On the other hand, the solute flux through membrane showed the opposite trend. The concentration of flow in the feed-channel increased a lot along the y-direction and that in the draw-channel decreased along the x-direction. In our system, for the inlet pressure differences of 1~11 atm, the flow rate in the feed-channel decreased about 8~13% and that in the draw-channel increased by the same amount. The power density increased and then decreased with the increasing inlet pressure difference.

• Journal of Korean Society of Water and Wastewater
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• v.35 no.1
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• pp.93-100
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• 2021

Forward osmosis (FO) process is a chemical potential driven process, where highly concentrated draw solution (DS) is used to take water through semi-permeable membrane from feed solution (FS) with lower concentration. Recently, commercial FO membrane modules have been developed so that full-scale FO process can be applied to seawater desalination or water reuse. In order to design a real-scale FO plant, the performance prediction of FO membrane modules installed in the plant is essential. Especially, the flux prediction is the most important task because the amount of diluted draw solution and concentrate solution flowing out of FO modules can be expected from the flux. Through a previous study, a theoretical based FO module model to predict flux was developed. However it needs an intensive numerical calculation work and a fitting process to reflect a complex module geometry. The idea of this work is to introduce deep learning to predict flux of FO membrane modules using 116 experimental data set, which include six input variables (flow rate, pressure, and ion concentration of DS and FS) and one output variable (flux). The procedure of optimizing a deep learning model to minimize prediction error and overfitting problem was developed and tested. The optimized deep learning model (error of 3.87%) was found to predict flux better than the theoretical based FO module model (error of 10.13%) in the data set which were not used in machine learning.

• Journal of Astronomy and Space Sciences
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• v.15 no.2
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• pp.437-447
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• 1998

Orbit error analysis was performed for the GPS navigation solutions and ground station tracking data of the KOMPSAT (Korea Multi-Purpose SATellite), which will be launched in 1999 for cartography of Korean peninsula as main mission. A least square method was used for the orbit determination and prediction error simulation including tracking data noises and dynamic modeling errors. It was found that a short-term periodic orbit determination error was caused by the tracking data noise and dominant orbit prediction error was caused by solar flux uncertainty.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.1 no.1
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• pp.50-62
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• 1989

Shoreline change of Haeundae beach was predicted by one-line model considering interaction of seawalls and longshore variation of wave height . Wave deformation was calculated by combined wave refraction-diffraction model . In this shoreline change model, empirical constants and offshore sediment transport rate are treated as calibration parameters, and the calculated results are in good agreement with the observed data.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.177-177
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• 2022

기후변화 및 해안 구조물의 증가 등 여러 원인이 연안침식 및 해안선 변화와 같은 연안의 지형변화를 가속하고 있다. 빠르게 변화하는 연안의 지형변화예측 및 대응책 강구를 위해서는 연안의 유사이송 현상에 대한 신속한 예측이 필요하다. 본 연구에서는 GPU 엔진 기반 파랑해석모형인 Celeris Advent를 활용하여 실시간으로 연안의 유사이송 모의가 가능한 수치모형을 개발하였다. Celeris Advent는 GPU의 병렬코어를 활용해 실시간 연산과 GUI를 통한 사용자와의 실시간 상호작용이 가능한 모형이다. 지배방정식은 확장형 Boussinesq 방정식에 유사이송방정식을 양방향 결합하여 구성하였고, 지배방정식에는 하이브리드 유한체적-유한차분 수치기법을 적용하여 이송항은 유한체적법(Kurganov & Petrova, 2007), 소스항은 유한차분법을 통해 이산화하여 해석한다. 유사이송방정식은 수심적분형 이송확산방정식에 침식 및 퇴적 플럭스를 반영하는 소스항을 결합하여, 이송항 및 확산항을 통해 유사의 이송/확산을 고려함과 동시에 소스항을 통해 하상과의 상호작용을 고려하였다.

• Korean Journal of Agricultural and Forest Meteorology
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• v.22 no.2
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• pp.79-91
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• 2020

Accurate assessment of greenhouse gas emissions is a cornerstone of every climate change response study, and reliable assessment of greenhouse gas emission data is being used as a practical basis for the entire climate change prediction and modeling studies. Essential, fundamental technologies for estimating greenhouse gas emissions include an on-site monitoring technology, an evaluation methodology of uncertainty in emission factors, and a verification technology for reductions. The closed chamber method is being commonly used to measure gas fluxes between soil-vegetation and atmosphere. This method has the advantages of being simple, easily available and economical. This study presented the technical bases of the closed chamber method for measuring methane fluxes from a rice paddy. The methane fluxes from rice paddies occupy the largest portion of a single source of greenhouse gas in the agricultural field. We reviewed the international and the domestic studies on automated chamber monitoring systems that have been developed from manually operated chambers. Based on this review, we discussed scientific concerns on chamber methods with a particular focus on quality control for improving measurement reliability of field data.

• Clean Technology
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• v.19 no.3
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• pp.219-225
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• 2013

Environment-friendly and surfactant-free aqueous cleaning agents have been developed in order to solve various problems generated by surfactants in the aqueous cleaning agents. Aqueous surfactant-free cleaning agents, S-1 and S-2 have been formulated with water-soluble solvents such as propylene glycol and propylene glycol ether on their main components and with some additives. These solvents were chosen because of their good solubility in water and excellent solubility of fluxes which are major contaminants of printed circuit board in the electronic industry. Physical properties of the formulated and the imported cleaning agents were measured to predict their cleaning performance, and their cleaning abilities of flux and solder contaminants were evaluated under the various ultrasonic frequencies by a gravimetric method. The measurement results show that the physical properties of cleaning agent V are generally similar with those of formulated cleaning agents S-1 and S-2. Both the cleaning agent V and the formulated cleaning agents S-1 and S-2 showed similar trends that their pH decrease in the beginning and then increases later on with the increase of their dilution in water. It is considered that the wetting indices of the cleaning agents calculated with experimental values do not not have any influence on their cleaning ability. In ultrasonic cleaning tests under three ultrasonic frequencies of 28, 45, and 100 kHz, their best performances of cleaning solder and flux were obtained at 45 kHz and 28 kHz, respectively, and the cleaning performance of the formulated cleaning agents S-1 and S-2 was better than that of the cleaning agent V. However, in the case of the recommended diluted concentration of 25 wt% cleaning solution, the cleaning performance of the cleaner V for solder and flux was better in the initial stage of cleaning compared to the formulated cleaners. And it may be concluded that the formulated cleaning agents S-1 and S-2 can be applied to cleaning of solder and flux in the industry, based on the experimental results in this study.

• Applied Chemistry for Engineering
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• v.19 no.4
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• pp.397-401
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• 2008

To verify model adaptation and flexibility, non-isothermal simulation for perlite expansion has been carried out. Temperature-dependent perlite properties are applied to energy equations for bubble temperature change and perlite melt temperature gradient. Bubble temperature is changed with volume change, water evaporation, and heat flux from melt. Temperature gradient of perlite melt is affected by decreasing bubble temperature. As a result, prediction model and code have been developed below 1100 K with 5% accuracy. At 1100~1400 K, lower 7% accuracy has been obtained from the calculation results.