• Journal of Bio-Environment Control
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• v.27 no.4
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• pp.277-284
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• 2018

For the main variables to be selected by the designer for the heating and cooling load calculation in greenhouses, in order to evaluate the effect of these design values on the heating and cooling load, the simulations were carried out by varying the respective design values. Based on these results, we proposed the design values which should pay special attention to selection. The design values which have the greatest effect on the heating load were the overall heat transfer coefficient of the covering material and the design outdoor temperature was next. The effect of the design values according to the number of spans showed little difference. In the case of the single-span greenhouse, the effect of the design values related to the underground heat transfer can not be ignored. However, in the case of the multi-span greenhouse, the effect of the design values related to the underground heat transfer and the infiltration rate were insignificant. The design values which have the greatest effect on the cooling load were the solar radiation into the greenhouse and the evapotranspiration coefficient, followed by the indoor and outdoor temperature difference and the ventilation rate. The effect of the design values showed a great difference between the single-span greenhouse and the multi-span greenhouse, but there was almost no difference according to the number of spans. The effect of the overall heat transfer coefficient of the covering material was negligible in both the single-span greenhouse and the multi-span greenhouse. However, the effect of the indoor and outdoor temperature difference and the ventilation rate on the cooling load was not negligible. Especially, it is considered that the effect is larger in multi-span greenhouse.

• Progress in Medical Physics
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• v.23 no.2
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• pp.81-90
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• 2012

The effect of setup uncertainties on CTV dose and the correlation between setup uncertainties and setup margin were evaluated by Monte Carlo based numerical simulation. Patient specific information of IMRT treatment plan for rectal cancer designed on the VARIAN Eclipse planning system was utilized for the Monte Carlo simulation program including the planned dose distribution and tumor volume information of a rectal cancer patient. The simulation program was developed for the purpose of the study on Linux environment using open source packages, GNU C++ and ROOT data analysis framework. All misalignments of patient setup were assumed to follow the central limit theorem. Thus systematic and random errors were generated according to the gaussian statistics with a given standard deviation as simulation input parameter. After the setup error simulations, the change of dose in CTV volume was analyzed with the simulation result. In order to verify the conventional margin recipe, the correlation between setup error and setup margin was compared with the margin formula developed on three dimensional conformal radiation therapy. The simulation was performed total 2,000 times for each simulation input of systematic and random errors independently. The size of standard deviation for generating patient setup errors was changed from 1 mm to 10 mm with 1 mm step. In case for the systematic error the minimum dose on CTV $D_{min}^{stat{\cdot}}$ was decreased from 100.4 to 72.50% and the mean dose $\bar{D}_{syst{\cdot}}$ was decreased from 100.45% to 97.88%. However the standard deviation of dose distribution in CTV volume was increased from 0.02% to 3.33%. The effect of random error gave the same result of a reduction of mean and minimum dose to CTV volume. It was found that the minimum dose on CTV volume $D_{min}^{rand{\cdot}}$ was reduced from 100.45% to 94.80% and the mean dose to CTV $\bar{D}_{rand{\cdot}}$ was decreased from 100.46% to 97.87%. Like systematic error, the standard deviation of CTV dose ${\Delta}D_{rand}$ was increased from 0.01% to 0.63%. After calculating a size of margin for each systematic and random error the "population ratio" was introduced and applied to verify margin recipe. It was found that the conventional margin formula satisfy margin object on IMRT treatment for rectal cancer. It is considered that the developed Monte-carlo based simulation program might be useful to study for patient setup error and dose coverage in CTV volume due to variations of margin size and setup error.

• Korean Journal of Agricultural and Forest Meteorology
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• v.16 no.1
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• pp.39-50
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• 2014

This paper reviews the results of recent observations in the Yeonsuri valley of Mt. Youngmun during springtime (March to May) in 2012. Automated weather stations were installed at twelve sites in the valley to measure temperature and 2, 3 dimensional wind. We examined temporal and spatial characteristics of temperatures and wind data. The Yeonsuri valley springtime average temperature lapse rate between the top and bottom of the entire period is $-0.44^{\circ}C/100$ m. It can be changed by the synoptic weather conditions, the lapse rates is greatest in order of clear days ($-0.48^{\circ}C/100$ m), rainy ($-0.41^{\circ}C/100$ m) and cloudy days ($-0.40^{\circ}C/100$ m). In the night, the temperature inversion layer (thermal belt) and the cold pool are formed within the valley. In addition, we measured temperature and wind distribution from the bottom to 3.5 m, the cold layers existed up to 1.5 m, which were affected by ground mixed layer. The results will provide useful guidance on agricultural practices as well as model simulations.

• Journal of the Korean Geographical Society
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• v.28 no.4
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• pp.285-297
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• 1993

For the application of the diffusion equation, slope height and maximum slope angle are calculated from the plotted slope profile. Using denudation rate as a solution for the diffusion equation, an apparent age index can be calculated, which is the total amount of denudation through total time. Plots of slope angle versus slope height and apparent age index versus slope height are useful for determining relative or absolute ages and denudation rates. Mathematical simulation plots of slope angle versus slope height can generate equal denudation-rate lines for a given age. Mathematical simulations of slope angle versus age for a given slope height, for equal denudation-rate at a particular profile site, and for comparing to other sites having controlled ages.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.8B
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• pp.691-700
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• 2006

Based on the destination IP address of incoming packets, the Internet routers determine next hops and forward packets toward final destinations through If address lookup. The bandwidth of communication links increases exponentially fast as well as the routing table size grows significant as the number of single host networks attached to the Internet increases. Since packets should be processed at wire-speed, the increased link speed reduces the processing time of a packet in routers, and hence more efficient and fast IP address lookup algorithms and architectures are required in the next generation routers. Most of the previous IP lookup schemes compare routing prefixes of shorter length first with a given input IP address. Since IP address lookup needs to find the most specific route of the given input, search continues until the longest matched prefix is found while it keeps remembering the current test matching prefix. In this paper, based on binary search on prefix length, we proposed a new IP address lookup algorithm which compares longer prefixes first. The proposed scheme is consisted of multiple tries with prefixes on leaves only. The trie composed of the longest prefixes is primarily searched whether there is a match with the given input. This processing is repeated for the trio of the next longer prefixes until there finds a match. Hence the proposed algorithm provides the fast search speed. The proposed algorithm also provides the incremental update of prefixes while the previous binary search on length scheme does not provide the incremental update because of pre-processing requirement. In this paper, we performed extensive simulations and showed the performance comparisons with related works.

• Journal of Korean Society of Forest Science
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• v.106 no.1
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• pp.77-86
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• 2017

This study was conducted to analyze the relationship among climatic factors and radial growth of Pinus densiflora and Larix kaempferi in South Korea. To determine the climate-growth relationship, cluster analysis was applied to group surveyed regions by the climatical similarity, and a dendroclimatological model was developed to predict radial growth for each climate group under the RCP 4.5 and RCP 8.5 scenarios for greenhouse gases. The cluster analysis showed four climatic clusters (Cluster 1~4) from 10 regions for P. densiflora and L. kaempferi. The dendroclimatological model was developed through climatic variables and standardized residual chronology for each climatic cluster of P. densiflora and L. kaempferi. Four climatic variables were used in the models for P. densiflora ($R^2$ values between 0.38 to 0.58). Two to five climatic variables were used in the models for L. kaempferi ($R^2$ values between 0.31 to 0.43). The growth simulations with two RCP climate-change scenarios(RCP 4.5 and RCP 8.5) were used for growth prediction. The radial growth of the Cluster 4 of P. densiflora, the mountainous region at high elevation, tend to increase, while those of cluster 2 and 3 of P. densiflora, the region of the hightest average temperature, tends to decrease. The radial growth of the Cluster 1 of L. kaempferi the region of the lowest minimum temperature, while that of Cluster 2, the region of the highest average temperature, tends to decrease. The radial growth of Cluster 3 of L. kaempferi, the region in the east coast and Cluster 4, the region at high elevation, tends to hold steady. The results of this study are expected to provide valuable information necessary for predicting changes in radial growth of Pinus densiflora and Larix kaempferi caused by climate change.

• Journal of the Korean Institute of Landscape Architecture
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• v.43 no.4
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• pp.15-26
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• 2015

The Daegu Metropolitan Transit Corporation Advisory Committee has chosen 5 styles of bridge-pier designs, including coating, graphic, planting, billboard and safety-facility style, based on the results of landscape simulations from a previous study. This study was conducted to investigate citizen's preferences and emotional images for each style of bridge-pier design, by aiming at the pilot urban landscape improvement section from Daebong Bridge in Suseong Gu to the crossroads near Dongseong Elementary School in Daegu Metropolitan City. The questionnaire was drawn up regarding the urban landscape improvement plans applied to the research area, and the questions were about citizens' perception of bridge-pier structures generated by constructing a light rail transit, important factors to consider when designing bridge piers, preferences for each style of bridge-pier design and emotional impact. 60.4% of the survey participants were found to perceive bridge-pier structures as unattractive, so it was necessary to improve them aesthetically. Regarding visual factors of bridge-pier designs, color was most important at 5.81, followed by form at 5.57. Regarding aesthetic component factors, harmony was most important at 6.07, followed by amenity at 6.00. In the survey participants' preference for each bridge-pier design, the graphic style was preferred most at 4.14, followed by the planting style. In emotional adjectives used for each bridge-pier design, the coating style, the safety-facility style and the non-treatment style showed similar results, and all of these styles were evaluated as artificial, lifeless and desolate. The graphic style and the billboard style showed different tendencies, depending on visual factors and aesthetic component factors applied to the graphic design used for these two bridge-pier styles. Since natural materials were used for the planting style, however, it showed high preference for such emotional images as natural and lively. The emotional adjective 'amiable' was found to affect citizens' preferences for each bridge-pier aesthetic improvement plan most, and it was also analyzed to have an effect on all the styles of bridge-pier designs. To improve the landscape of a light rail transit being constructed inside the urban area, this study quantitatively extracted citizens' preferences and emotional adjective for every style of bridge-pier design applied to the pilot urban landscape improvement section, and it is expected that the results of this study will be used as basic data to improve the landscape of bridge piers.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39A no.5
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• pp.258-270
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• 2014

In this paper, we investigate channel capacity of two kinds of uplink OFDMA (Orthogonal Frequency Division Multiple Access) schemes, i.e. ZCZ (Zero Correlation Zone) code time-spread OFDMA and sparse SC-FDMA (Single Carrier Frequency Division Mmultiple Access) robust to access timing offset (TO) among multiple users. In order to reflect the practical condition, we consider not only access TO among multiple users but also peak to average power ratio (PAPR) which is one of hot issues of uplink OFDMA. In the case with access TO among multiple users, the amplified signal of users by power control might affect a severe interference to signals of other users. Meanwhile, amplified signal by considering distance between user and base station might be distorted due to the limit of amplifier and thus the performance might degrade. In order to achieve the maximum channel capacity, we investigate the combinations of transmit power so called ASF (adaptive scaling factor) by numerical simulations. We check that the channel capacity of the case with ASF increases compared to the case with considering only distance i.e. ASF=1. From the simulation results, In the case of high signal to noise ratio (SNR), ZCZ code time-spread OFDMA achieves higher channel capacity compared to sparse block SC-FDMA. On the other hand, in the case of low SNR, the sparse block SC-FDMA achieves better performance compared to ZCZ time-spread OFDMA.

• Korean Journal of Agricultural and Forest Meteorology
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• v.11 no.4
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• pp.192-205
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• 2009

The unexpected wind over the Mt. Hwawang on 9 February 2009 was deadly when many spectators were watching a traditional event to burn dried grasses and the fire went out of control due to the wind. We analyzed the fatal wind based on wind flow simulations over a digitized complex terrain of the mountain with a localized heating area using a three dimensional computational fluid dynamics model, CFD_NIMR_SNU (Computational Fluid Dynamics_National Institute of Meteorological Research_Seoul National University). Three levels of fire intensity were simulated: no fire, $300^{\circ}C$ and $600^{\circ}C$ of surface temperature at the site on fire. The surface heat accelerated vertical wind speed by as much as $0.7\;m\;s^{-1}$ (for $300^{\circ}C$) and $1.1\;m\;s^{-1}$ (for $600^{\circ}C$) at the center of the fire. Turbulent kinetic energy was increased by the heat itself and by the increased mechanical force, which in turn was generated by the thermal convection. The heating together with the complex terrain and strong boundary wind induced the unexpected high wind conditions with turbulence at the mountain. The CFD_NIMR_SNU model provided valuable analysis data to understand the consequences of the fatal mountain fire. It is suggested that the place of fire was calm at the time of the fire setting due to the elevated terrain of the windward side. The suppression of wind was easily reversed when there was fire, which caused updraft of hot air by the fire and the strong boundary wind. The strong boundary wind in conjunction with the fire event caused the strong turbulence, resulting in many fire casualties. The model can be utilized in turbulence forecasting over a small area due to surface fire in conjunction with a mesoscale weather model to help fire prevention at the field.

• Journal of the Korean Institute of Landscape Architecture
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• v.39 no.1
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• pp.35-45
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• 2011

The landscape of Seoul was dynamically changed and developed with the rapid post-war economic growth. Seoul city designated a height regulation district to preserve and manage the city landscape and protect it from haphazard construction. The designation of a maximum height regulation district has obvious purpose and simple regulations which makes the implementation and management easy to apply yet the altitude restriction lacks an objective basis for its enforcement. Many studies have been done and the current uniform height regulation requires more objective and logical guidelines. This study selected the Bukhan Mountain area, a National Park designated to protect the environment, to present a new landscape height guideline to minimize environmental degradation and to harmonize the artificial and natural landscapes of the area. Document research was done to identify the regulation types(absolute height regulation, view line regulation, oblique line restriction regulation) and principles for height regulation district establishment, acknowledge the current status and issues of the Bukhan Mountain area's maximum height regulation district. Gangbuk-Gu was chosen as the site and survey was conducted on outstanding view points and view corridors of residents. From document research, an appropriate landscape height guideline was selected and applied to Gangbuk-Gu. According to the guideline, suitable heights for buildings were suggested. These were then applied to three-dimensional simulations and a final guideline was suggested.