• Korean Journal of Agricultural and Forest Meteorology
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• v.15 no.4
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• pp.312-319
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• 2013

Our understanding of the sensitivities of crop responses to changes in carbon dioxide, temperature, and water is limited, which makes it difficult to fully utilize crop models in assessing the impact of climate change on future agricultural production. Genetic coefficients of CERES-Barley model for major domestic cultivars in South Korea (Olbori at Suwon, Albori at Milyang, Saessalbori at Iksan, and Samdobori at Jinju) were estimated from the observed data for daily weather and field trials for more than 10 years by using GenCalc in DSSAT. Data from 1997-2002 annual crop status report (Rural Development Administration, RDA) were used to validate the crop coefficients. The sitecalibrated CERES-Barley model was used to perform crop growth simulation with the 99 treatments of step change combinations in temperature, precipitation and carbon dioxide concentration with respect to the baseline climate (1981-2010) at four sites. The upper boundary corresponds to the 2071-2100 climate outlook from the RCP 8.5 scenario. The response surface of grain yield showed a distinct pattern of model behavior under the combined change in environmental variables. The simulated grain yield was most sensitive to $CO_2$ concentration, least sensitive to precipitation, and showing a variable response to temperature depending on cultivar. The emulated impacts of response surfaces are expected to facilitate assessment of projected climate impacts on a given cultivar in South Korea.

• Journal of Korean Society of Transportation
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• v.34 no.2
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• pp.180-190
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• 2016

Atmospheric pollutants such as Nitrogen Oxides(NOx), Carbon Monoxide(CO), Carbon Dioxide($CO_2$), Particulate Matter(PM) and Hydrocarbons(HC) come from vehicle exhaust gases. Emission curves based on average travel speeds have been employed for estimating on-road emissions as well as evaluating environmental impacts of transportation plans and policies in Korea. Recently, there is a growing interest in estimation methods of vehicle emissions considering relationship between vehicle dynamic driving characteristics and emissions, and incorporating such emission estimators into traffic simulation models. MOVES Lite, a simplified version of MOVES, is one of the estimation methods. In this study, the authors performed a study to develop an adaptable version of MOVES Lite for Korea, called MOVES Lite-K. Vehicle types, driving characteristics, emission rates, and emission standards of Korea were reflected in MOVES Lite-K. The characteristics of emission calculation of MOVES Lite-K and NIER emission curves were compared and the adaptability of MOVES Lite-K were examined.

• Journal of Korea Water Resources Association
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• v.43 no.11
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• pp.995-1009
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• 2010

Accelerated soil erosion due to extreme climate change, such as increased rainfall intensity, and human-induced environmental changes, is a widely recognized problem. Existing soil erosion models are generally based on the gross erosion concept to compute annual upland soil loss in tons per acre per year. However, such models are not suitable for event-based simulations of erosion and deposition in time and space. Recent advances in computer geographic information system (GIS) technologies have allowed hydrologists to develop physically based models, and the trend in erosion prediction is towards process-based models, instead of conceptually lumped models. This study aims to propose an effective and robust distributed rainfall-sediment yield-runoff model consisting of basic element modules: a rainfall-runoff module based on the kinematic wave method for subsurface and surface flow, and a runoff-sediment yield-runoff model based on the unit stream power method. The model was tested on the Cheoncheon catchment, upstream of the Yongdam dam using hydrological data for three extreme flood events due to typhoons. The model provided acceptable simulation results with respect to both discharge and sediment discharge even though the simulated sedigraphs were underestimated, compared to observations. The spatial distribution of erosion and deposition demonstrated that eroded sediment loads were deposited in the cells along the channel network, which have a short overland flow length and a gentle local slope while the erosion rate increased as rainfall became larger. Additionally, spatially heterogeneous rainfall intensity, dependant on Thiessen polygons, led to spatially-distinct erosion and deposition patterns.

• Journal of Korea Water Resources Association
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• v.43 no.11
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• pp.985-994
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• 2010

Typoon Maemi landed on the southern coast of Korean Peninsula at 21:00, September 12, 2003 with a central pressure of 950 hPa. A three dimensional (3D) inundation model was established to calculate the storm surge and flooded area due to Typoon Maemi. A field survey of storm surge traces in Masan City was carried out to evaluate the inundation water depth. Hydromet-Rankin Vortex model was used to calculate the atmospheric pressure and the surface wind fields. The inundation area, storm surge and typoon-induced current were calculated using the 3D model. The peak of computed storm surge in Masan Port using the 3D model was 238 cm, and the observed peak was 230 cm. The simulated storm surge and the inundation area showed good agreement with field survey data. The comparison of the 3D and the two dimensional (2D) models of storm surge was carried out, and the 3D model was more accurate. The computed typoon-induced currents in the surface layer of Masan Bay went into the inner bay with 30~60 cm/s, while the currents in the bottom layer flowed out with 20~40 cm/s.

• Korean Journal of Agricultural and Forest Meteorology
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• v.12 no.3
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• pp.183-196
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• 2010

Increasing human activity due to rapid economic growth and land use change alters the patterns of the Asian monsoon, which is key to crop yields in Asia. In this study, we tested the performance of regional climate model (RegCM3) by simulating important components of Indian summer monsoon, including land-ocean contrast, low level jet (LLJ), Tibetan high and upper level Easterly Jet. Three contrasting rain years (1994: excess year, 2001: normal year, 2002: deficient year) were selected and RegCM3 was integrated at 60 km horizontal resolution from April 1 to October 1 each year. The simulated fields of circulations and precipitation were validated against the observation from the NCEP/NCAR reanalysis products and Global Precipitation Climatology Centre (GPCC), respectively. The important results of RegCM3 simulations are (a) LLJ was slightly stronger and split into two branches during excess rain year over the Arabian Sea while there was no splitting during normal and deficient rain years, (b) huge anticyclone with single cell was noted during excess rain year while weak and broken into two cells in deficient rain year, (c) the simulated spatial distribution of precipitation was comparable to the corresponding observed precipitation of GPCC over large parts of India, and (d) the sensitivity experiment using NIMBUS-7 SMMR snow data indicated that precipitation was reduced mainly over the northeast and south Peninsular India with the introduction of 0.1 m of snow over the Tibetan region in April.

• Journal of Science Education
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• v.36 no.1
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• pp.35-48
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• 2012

The purpose of this study was to analyze inquiry activities in the middle school science textbooks focused on the unit 'Nutrition of Plants' of the 2007 revision curriculum and the corresponding unit 'The Structure and Function of Plants' of the 7th curriculum in terms of content, process and contexts of inquiries. The average number of the inquiry activities in the unit 'Nutrition of Plants' was 9.2, which was a 3.8 decrease than in the unit 'Structure and Function of Plants'. In the respective of process of the inquiry activities, 'observation' was most prevailing in the basic inquiry process and 'data interpretation' was most prevailing in the integrated inquiry process in both of the units. In the respective of the types and contexts of the inquiry activities, 'experiment/observation' was most prevailing and the percentage of the natural scientific contexts was larger in both of the units. In the unit 'Nutrition of Plants', the components of the integrated inquiry process and the percentage of personal contexts were larger than in the unit 'Structure and Function of Plants'. And simulation activities were newly presented and technical contexts and natural environmental contexts were included in the unit 'Nutrition of Plants'. This study makes a suggestion that a wider variety of inquiry activities should be included when new science textbooks are developed.

• Journal of KIISE:Databases
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• v.34 no.5
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• pp.448-464
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• 2007

Location-Based Services (LBSs) provide results to queries according to the location of the client issuing the query. In LBS, techniques such as caching and prefetching are effective approaches to reducing the data transmission from a server and query response time. However, they can lead to cache inefficiency and network overload due to the client's mobility and query pattern. To solve these drawbacks, we propose a semantic prefetching (SP) scheme using prefetching segment concept and improved cache replacement policies. When a mobile client enters a new service area, called semantic prefetching area, proposed scheme fetches the necessary semantic information from the server in advance. The mobile client maintains the information in its own cache for query processing of location-dependent data (LDD) in mobile computing environment. The performance of the proposed scheme is investigated in relation to various environmental variables, such as the mobility and query pattern of user, the distributions of LDDs and applied cache replacement strategies. Simulation results show that the proposed scheme is more efficient than the well-known existing scheme for range query and nearest neighbor query. In addition, applying the two queries dynamically to query processing improves the performance of the proposed scheme.

• Journal of Biomedical Engineering Research
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• v.24 no.5
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• pp.427-434
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• 2003

In this paper, we present a speech-based Environmental Control System(ECS) and its application. In the concrete, an ECS using the speech recognition and an portable wheelchair lift control system with the speech synthesis are developed through the simulation and the embodiment. The developed system apply to quadriplegic man and we evaluate the result of physical effect and of mental effect. Speech recognition system is constructed by real time modules using HMM model. For the clinical application of the device, we investigate the result applied to 54-years old quadriplegic man during a week through the questionnaires of Beck Depression Inventory and of Activity Pattern Indicator. Also the motor drive control system of potable wheelchair lift is implemented and the mechanical durability is tested by structural analysis. Speech recognition rate results in over 95% through the experiment. The result of the questionnaires shows higher satisfaction and lower nursing loads. In addition, the depression tendency of the subject were decreased. The potable wheelchair lift shows good fatigue life-cycle as the material supporting the upper wheelchair and shows the centroid mobility of safety. In this paper we present an example of ECS which consists of real-time speech recognition system and potable wheelchair lift. Also the experiments shows needs of the ECS for korean environments. This study will be the base of a commercial use.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.25 no.6
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• pp.394-404
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• 2013

In the present study, the characteristics of spectral peakedness parameter $Q_p$, bandwidth parameter ${\varepsilon}$, and spectral width parameter ${\nu}$ were analyzed as a first step to define the swell waves quantitatively. For the analysis, the joint probability density function of significant wave heights and peak periods were newly developed. The MCMC(Markov Chain Monte Carlo) simulations have been performed to generate the significant wave heights and peak periods from the developed probability density functions. Applying the simulated significant wave heights and peak periods to the theoretical wave spectrum models, the spectral shapes parameters were obtained and analyzed. Among the spectral shape parameters, only the spectral peakedness parameter $Q_p$, is shown to be independent with the significant wave height and peak wave period. It also best represents the peakedness of the spectral shape, and henceforth $Q_p$ should be used to define the swell waves with a wave period. For the field verification of the results, wave data obtained from Hupo port and Ulleungdo were analyzed and results showed the same trend with the MCMC simulation results.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.6
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• pp.185-195
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• 2017

In recent years, unexpected bridge fire accidents have increased because of augmenting the number of traffic volumes and hazardous materials by the increment in traffics and distribution business. Furthermore, in accordance with the effort of using the under space of bridges, the ratio of occupied by combustible materials like oil tanker or lorry has been increased. As a result, the occurrence of bridge fire has been growing drastically. In order to mitigate the accident of bridge fire, risk assessment of bridge fire has been studied, however, practical risk models considering safety from users' viewpoints were scarce. This study represented quantitative risk assessment model applicable to national road bridges in Korea. The primary factors with significant impacts on bridge fire accidents was chosen such as clearance height, materials of bridges, arrival time of fire truck and fire intensity. The selected factors were used for Fire Dynamics Simulation (FDS) and the peak temperature calculated by FDS in accordance with the fire duration and fire intensity. The risk assessment model in bridge fire reflected the FDS analysis results, the fire damage criteria, and the grade of fire truck arrival time was established. Response plans for bridge fire accidents according to the risk assessment output has been discussed. Lastly, distances between bridges and fire stations were calculated by GIS network analysis. Based on the suggested assessment model and methodology, sample bridges were selected and graded for the risk assessment.