• Proceedings of the Korean Institute of Building Construction Conference
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• 2004.05a
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• pp.101-104
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• 2004

If predicting of compressive strength of construction in construction field at early age is possibile, rational strength management & schedule plan is possible. With method for predicting strength of concrete, many researchers have been making study of maturity method. On the other hand, nowadays rationalization of construction capacity and reduction of a term of works due to improvement of construction capacity and application of a new method of construction is gathering strength with important issue. In accordance with this present condition, construction is being progressed in winter, but proper construction mothed and countermeasure for strength management is not established in case of winter construction. Therefore to investigate application in construction field at winter of strength prediction model that developed at former study, this study aim to measure application of developed strength prediction model through manufacture of mock-up concrete according to kind of strength level at 5$^{\circ}C$.

• Journal of Korea Multimedia Society
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• v.21 no.5
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• pp.599-608
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• 2018

As natural disasters are increasing due to the unusual weather and the modern society is getting complicated, the rapid change of the urban environment has increased human disasters. Thus, citizens are becoming more anxious about social safety. The importance of preparation for safety has been suggested by providing the disaster safety services such as regional safety index, life safety map, and disaster safety portal application. In this paper, we propose an application framework to predict the urban safety index based on user's location with realtime weather/atmosphere data after creating a predication model based on the machine learning using number of occurrence cases and weather/atmosphere history data. Also, we implement an application to provide traffic safety index with executing preprocessing occurrence cases of traffic and weather/atmosphere data. The existing regional safety index, which is displayed on the Si-gun-gu area, has been mainly utilized to establish safety plans for districts vulnerable to national policies on safety. The proposed system has an advantage to service useful information to citizens by providing urban safety index based on location of interests and current position with realtime related data.

• Computers and Concrete
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• v.16 no.6
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• pp.847-864
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• 2015

This study aimed to develop models of sulfate diffusion and ettringite content profile in cement paste for the predication of the damage behavior in cement paste subject to external sulfate. In the models, multiphase reaction equilibrium between ions in pore solution and solid calcium aluminates phases and the microstructure changes in different positions of cement paste were taken into account. The distributions of expansive volume strain and expansion stress in cement paste were calculated based on the ettringite content profile model. In addition, more sulfate diffusion tests and SEM analyses were determined to verify the reliability and veracity of the models. As the results shown, there was a good correlation between the numerical simulation results and experimental evidences. The results indicated that the water to cement ratio (w/c) had a significant influence on the diffusion of sulfate ions, ettringite concentration profile and expansion properties in cement paste specimens. The cracking points caused by ettringite growth in cement paste specimens were predicted through numerical methods. According to the simulation results, the fracture of cement paste would be accelerated when the specimens were prepared with higher w/c or when they were exposed to sulfate solution with higher concentration.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.18 no.6
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• pp.15-25
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• 2015

The growth of impermeable layers in the city center due to today's urban development is emerging as a major cause of urban heat island effects as well as recurring inland flood damages. In order to cope with such disasters caused by climatic changes, an artificial ground afforestation system is suggested as a fundamental solution that addresses both water environment and heat environment. For the afforestation system to replace the current disaster prevention facilities, quantitative performance verification through related numerical analysis models and actual survey monitoring is necessary. Therefore, this study seeks to propose the performance predication method for the heat environment of the afforestation system by looking into correlations between measurements by physical vegetation indicators such as LAI and FVC and forecasts from FASST, a vegetation canopy model used by US Corps of Engineers.

• Proceedings of the Korea Information Processing Society Conference
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• 2006.05a
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• pp.1259-1262
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• 2006

H.264는 기존의 압축 표준들보다 월등한 압축률을 가지고 있어 다양한 멀티미디어 서비스에 적합하다. 특히 적은 양의 데이터 전송으로 서비스 받을 수 있는 모바일 기기에서는 빼놓을 수 없는 기술이 되었다. 현재 모바일 기기에서 영상 서비스는 하드웨어 기반의 디코더 형식으로 되어 있기 때문에 소프트웨어 기반의 디코더 개발이 시급하다. 그러기 위해서는 모바일 기기에서 탑재된 적은 용량의 메모리를 사용하므로써 빠른 재생이 가능해야 한다. 그래서 영상 복호화시에 사용되는 메모리 양을 줄일 수 있도록 참조픽처의 메모리를 관리하는 방법을 제안한다. 기존의 고정크기를 갖는 장기 참조픽처를 배제하고 단기 참조픽처로써 대체하고 비참조 픽처의 사용은 POC(Picture Order Count)에 전체 사용하지 않고 단지 순서를 정하기 위해 메모리 로드없이 순서 조합에 필요한 위치만 갖도록 하였다. 그러므로, 모바일 기기에서 메모리의 사용을 최대한 줄여 영상을 재생할 수 있도록 제안하였다.

• Journal of Environmental Science International
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• v.18 no.8
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• pp.847-855
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• 2009

As a part of effort to establish an offshore wind resource assessment system of the Korean Peninsula, a numeric wind simulation using mesoscale climate model MM5 and a spatial distribution of offshore wind extracted from SAR remote-sensing satellite image is compared and analyzed. According to the analyzed results, the numeric wind simulation is found to have wind speed over predication tendency at the coastal sea area. Therefore, it is determined that a high-resolution wind simulation is required for complicated coastal landforms. The two methods are verified as useful ways to identify the spatial distribution of offshore wind by mutual complementation and if the meteor-statistical comparative analysis is performed in the future using adequate number of satellite images, it is expected to derive a general methodology enabling systematic validation and correction of the numeric wind simulation.

• Journal of Electrical Engineering and Technology
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• v.12 no.6
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• pp.2166-2176
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• 2017

Electricity price prediction plays a crucial part in making the schedule and managing the risk to the competitive electricity market participants. However, it is a difficult and challenging task owing to the characteristics of the nonlinearity, non-stationarity and uncertainty of the price series. This study proposes a hybrid improved strategy which incorporates data preprocessor components and a forecasting engine component to enhance the forecasting accuracy of the electricity price. In the developed forecasting procedure, the Seasonal Adjustment (SA) method and the Ensemble Empirical Mode Decomposition (EEMD) technique are synthesized as the data preprocessing component; the Coupled Simulated Annealing (CSA) optimization method and the Least Square Support Vector Regression (LSSVR) algorithm construct the prediction engine. The proposed hybrid approach is verified with electricity price data sampled from the power market of New South Wales in Australia. The simulation outcome manifests that the proposed hybrid approach obtains the observable improvement in the forecasting accuracy compared with other approaches, which suggests that the proposed combinational approach occupies preferable predication ability and enough precision.

• Journal of Mechanical Science and Technology
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• v.15 no.7
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• pp.951-961
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• 2001

The present article presents an extension to the computational model for spray/wall interaction and liquid film processes that has been dealt with in the earlier studies (Lee and Ryou, 2000a). The extensions incorporate film spread due to impingement forces and dynamic motion induced by film inertia to predict the dynamic characteristics of wall films effectively. The film model includes the impingement pressure of droplets, tangential momentum transfer due to the impinging droplets on the film surface and the gas shear force at the film surface. Validation of the spray/wall interaction model and the film model was carried out for non-evaporative diesel sprays against several sources of experimental data. The computational model for spray/wall interactions was in good agreement with experimental data for both spray radius and height. The film model in the present work was better than the previous static film model, indicating that the dynamic effects of film motion should be considered for wall films. On the overall the present film model was acceptable for predication of the film radius and thickness.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.15 no.2
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• pp.73-80
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• 2006

This paper describes a analysis on the chip thickness model required for cutting force simulation in ball-end milling. In milling, cutting forces are obtained by multiplying chip area to specific cutting forces in each cutting instance. Specific cutting forces are one of the important factors for cutting force predication and have unique value according to workpiece materials. Chip area in two dimensional cutting is simply calculated using depth of cut and feed, but not simply obtained in three dimensional cutting such as milling due to complex cutting mechanics. In ball-end milling, machining is almost performed in the ball part of the cutter and tool radius is varied along contact point of the cutter and workpiece. In result, the cutting speed and the effective helix angle are changed according to length from the tool tip. In this study, for chip thickness model analysis, tool and chip geometry are analyzed and then the definition of chip thickness and estimation method are described. The resulted of analysis are verified by compared with geometrical simulation and other research. The proposed chip thickness model is more precise.

• International Journal of Air-Conditioning and Refrigeration
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• v.13 no.2
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• pp.89-98
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• 2005

In this study, indoor VOCs concentration emitted from floor and furniture was measured after the installation of floor and furniture in a real residence. With the measured data, prediction method and predication equations for indoor concentration of each VOCs and BTEX were developed. The following conclusions were drawn from this study. First, according to the predicted results of concentration decrease of BTEX (benzene, toluene, ethylbenzene, m,p,o-xylene) after the installation of floor in a real residence, prediction equation can be expressed using exponential function. Second, in case of floor, more reliable prediction equation can be obtained by using cumulative value of indoor concentration than by using just hourly measured value directly. Indoor concentration of benzene can be expressed as $y=408.52(1­e^{-00031{\times}time})$ with $R^2$ of 0.94 which is significantly high value. Third, toluene showed the highest concentration in case of furniture installation indoors, and it needed the longest time for concentration decrease. However, other substances except toluene showed constant concentration throughout the measurement period. Fourth, in case of furniture installation indoors, prediction equation of toluene concentration decrease is estimated to be $y= 3616.3{\times}e^{(-0.1091{\times}time)}+513.96{\times}e^{(-0.0006{\times}time)}\;with\; R^2$ of 0.95 which is significantly high value.