• Journal of the Korean Society of Environmental Restoration Technology
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• v.14 no.2
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• pp.47-57
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• 2011

This study monitored forest plant species vulnerable to climate change in Jiri Mountain, one of Korea's representative alpine regions, in order to securely preserve plant genetic resources susceptible to climate change and to utilize the results as basic data for bioclimatology prediction and management on a long-term basis. A majority of indicator plants tended to blossom one week to one month later in 2010 than in 2009. As with the blooming dates, the falling dates of blossoms became later in most species, with the exception for Weigela florida and Oplopanax elatus. Leaf bursting as well fell on later dates in a majority of species excluding Carpinus laxiflora and Cupressus sempervirens, displaying the most obvious differences among the data of analysis of the 2009-2010 physiological cycle changes. It is believed that was due to the fact that temperatures in February, March and April, which affect plants' blossoming and leaf bursting, were lower in 2010 than in 2009 and that cold temperatures in the winter lasted for a longer period in 2010 than in 2009. The dates of leaves being changed to red were similar in 2009 and 2010 by being or later or earlier by several weeks in 2010 than in 2009 without any regularity. Most species' leaves began to fall at similar dates in 2009 and 2010 or at later dates by one to two weeks in 2010 than in 2009. The temperature differences in late 2009 and late 2010 were not so large, resulting in similar dates of falling leaves, and gaps in several indicator plants' physiological cycles without any regularity can be attributed to each individual plant's physiological and environmental characteristics.

• Atmosphere
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• v.29 no.2
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• pp.183-196
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• 2019

High-quality and high-resolution meteorological information is essential to reduce damages due to disastrous weather phenomena such as flash flood, strong wind, and heat/cold waves. There are many meteorological observation stations operated by Korea Meteorological Administration (KMA) in Seoul Metropolitan Area (SMA). Nonetheless, they are still not enough to represent small-scale weather phenomena like convective storm cells due to its poor resolution, especially over urban areas with high-rise buildings and complex land use. In this study, feasibilities to use additional pre-existing networks (e.g., operated by local government and private company) are tested by investigating the effects of network density on the gridded horizontal distribution of two meteorological variables (temperature and precipitation). Two heat wave event days and two precipitation events are chosen, respectively. And the automatic weather station (AWS) networks operated by KMA, local-government, and SKTechX in Incheon area are used. It is found that as network density increases, correlation coefficients between the interpolated values with a horizontal resolution of 350 m and observed data also become large. The range of correlation coefficients with respect to the network density shows large in nighttime rather than in daytime for temperature. While, the range does not depend on the time of day, but on the precipitation type and horizontal distribution of convection cells. This study suggests that temperature and precipitation sensors should be added at points with large horizontal inhomogeneity of land use or topography to represent the horizontal features with a resolution higher than 350 m.

• Journal of Plant Biotechnology
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• v.42 no.1
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• pp.43-48
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• 2015

It is a serious situation that the farmers' income has gradually decreased due to the decline of productivity of fruit trees infected with viroids. It has been known that Persimmon viroid (PVd) and Citrus viroid (CVd) are economically important viroids that can infected persimmon. In this study, the incidence of CVd and PVd in 'Fuyu' persimmon were identified as 41% and 34% in JeollaNam-do, respectively. The collected persimmon samples infected by both PVd and CVd were used for testing efficiency of the viroid inactivation methods. The samples were subjected to single treatment of the heat treatment ($37^{\circ}C$), cold treatment ($4^{\circ}C$), or antiviral agent treatment (Ribavirin), and double treatment of combinations of the three methods. Viroid inactivation efficiency was confirmed through RT-PCR. In the case of the samples subjected to cold treatment for 4 weeks, the viroid inactivation efficiency was most significantly high as 67% against the survival rate of 100%. In addition, in the case of the samples treated for 2 weeks with the antiviral agents and cold treatment, the viroid inactivation rate was similar to that of the cold treatment. In conclusion, the cold treatment showed the highest viroid inactivation efficiency, and this result will provide valuable information for production of viroid-free persimmon.

• Asian-Australasian Journal of Animal Sciences
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• v.27 no.7
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• pp.1050-1056
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• 2014

This study investigated the main factors influencing digester temperature and methods to reduce heat losses during the cold season in the subtropics. Four composite digesters (two insulated and two uninsulated) were buried underground to measure their internal temperature ($^{\circ}C$) at a depth of 140 cm and 180 cm, biogas production and methane ($CH_4$) concentration in biogas from August to February. In parallel the temperature of the air (100 cm above ground), in the slurry mixing tank and in the soil (10, 100, 140, and 180 cm depth) was measured by thermocouple. The influent amount was measured daily and the influent chemical composition was measured monthly during the whole experimental period. Seasonal variations in air temperature significantly affected the temperature in the soil, mixing tank and digester. Consequently, biogas production, which is temperature dependent, was influenced by the season. The main factors determining the internal temperature in the digesters were insulation with Styrofoam, air temperature and temperature of slurry in the mixing tank. Biogas production is low due to the cold climate conditions in winter in Northern Vietnam, but the study proved that storing slurry in the mixing tank until its temperature peak at around 14:00 h will increase the temperature in the digester and thus increase potential biogas production. Algorithms are provided linking digester temperature to the temperature of slurry in the mixing tank.

• KIPS Transactions on Computer and Communication Systems
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• v.4 no.9
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• pp.289-296
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• 2015

The explosive growth of information has been difficult for users to get an appropriate information in time. The various ways of new services to solve problems has been provided. As customized service is being magnified, the personalized recommendation system has been important issue. Collaborative filtering system in the recommendation system is widely used, and it is the most successful process in the recommendation system. As the recommendation is based on customers' profile, there can be sparsity and cold-start problems. In this paper, we propose personalized movie recommendation system using collaborative filtering techniques and context-based techniques. The context-based technique is the recommendation method that considers user's environment in term of time, emotion and location, and it can reflect user's preferences depending on the various environments. In order to utilize the context-based technique, this paper uses the human emotion, and uses movie reviews which are effective way to identify subjective individual information. In this paper, this proposed method shows outperforming existing collaborative filtering methods.

• The Transactions of the Korea Information Processing Society
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• v.3 no.7
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• pp.1669-1679
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• 1996

In this paper, we address the problem of how to replace huffers in multimedia database systems with time-varying skewed data access. The access pattern in the multimedia database system to support audio-on-demand and video-on-demand services is generally skewed with a few popular objects. In addition the access pattem of the skewed objects has a time-varying property. In such situations, our analysis indicates that conventional LRU(least Recently Used) and LFU(Least Frequently Used) schemes for buffer replacement algorithm(ABRN:Adaptive Buffer Replacement using Neural suited. We propose a new buffer replacement algorithm(ABRN:Adaptive Buffer Replacement using Neural Networks)using a neural network for multimedia database systems with time-varying skewed data access. The major role of our neural network classifies multimedia objects into two classes:a hot set frequently accessed with great popularity and a cold set randomly accessed with low populsrity. For the classification, the inter-arrival time values of sample objects are employed to train the neural network.Our algorithm partitions buffers into two regions to combine the best roperties of LRU and LFU.One region, which contains the 핫셋 objects, is managed by LFU replacement and the other region , which contains the cold set objects , is managed by LRUreplacement.We performed simulation experiments in an actual environment with time-varying skewed data accsee to compare our algorithm to LRU, LFU, and LRU-k which is a variation of LRU. Simulation resuults indicate that our proposed algorthm provides better performance as compared to the other algorithms. Good performance of the neural network-based replacement scheme means that this new approach can be also suited as an alternative to the existing page replacement and prefetching algorithms in virtual memory systems.

• The Plant Pathology Journal
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• v.27 no.3
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• pp.232-341
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• 2011

Pink snow mold, caused by Microdochium nivale, is a major disease on cool season turfgrasses in golf courses in northern Unites States. The relative susceptibility of 17 commercial cultivars of three bentgrass species (creeping, colonial and velvet bentgrass) to Microdochium nivale and the aggressiveness of M. nivale eight isolates obtained from infected turfgrasses on golf courses in Wisconsin were evaluated under controlled conditions. For the field trial, susceptibility of 2 year-old 12 commercial bentgrass cultivars was evaluated after inoculating three M. nivale isolates in the fields. There were significant differences in disease severities among the three bentgrass species, particularly between tetraploids (creeping and colonial) and diploid (velvet) species, and among cultivars within each species, indicating that there are varying levels of susceptibility in species and cultivars to M. nivale. Host resistance by days of cold hardening was confirmed, by detecting the resistance by 30 days of cold hardening treatments. In field trial, susceptibility of 12 bentgrass cultivars was highly correlated to the results obtained from growth chamber experiments. The positive correlation of the susceptibility between growth chamber experiments and field trials demonstrates that the growth chamber method is a useful technique for saving time, space and labor to evaluate efficiently pink snow mold susceptibility of bentgrass cultivars. This study could be applied to evaluating susceptibility of bentgrass to pink snow mold and also predicting a prospective evaluation of bentgrass cultivars to pink snow mold in fields in a breeding program.

• Journal of KIISE
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• v.43 no.11
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• pp.1188-1200
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• 2016

Recommendation systems play a significant role in providing personalized information to users, with enhanced satisfaction and reduced information overload. Since the mid-1990s, many studies have been conducted on recommendation systems, but few have examined the recommendations of information from people in the online social networking environment. In this paper, we present a hybrid recommendation method that combines both the traditional system of content-based techniques to improve specialization, and the recently developed system of social network-based techniques to best overcome a few limitations of the traditional techniques, such as the cold-start problem. By suggesting a state-of-the-art method, this research will help users in online social networks view more personalized information with less effort than before.

• Journal of Broadcast Engineering
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• v.14 no.2
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• pp.189-196
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• 2009

We propose a hybrid broadcast scheduling based on a combination of periodic and on-demand data scheduling methods for mobile data broadcasting in convergence networks from communication and broadcasting. We consider an environment in which the forward channel is for data broadcasting and the reverse channel is for sending data requests via cellular phones, WLAN, WiBro, etc. Collecting statistics of requests from clients, the server partitions the data items into hot-item and cold-item sets. Hot items are sent based on a push-based scheduling. An on-demand scheduling method is applied to cold items. Performance evaluation from simulations shows that our proposed scheduling algorithm yields small response time with high successful response ratio.

• Journal of the Korean Applied Science and Technology
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• v.36 no.4
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• pp.1410-1419
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• 2019

In this research, it is to find a method that frost does not form on the outdoor unit to develop a heat pump capable of heating in cold regions. For this reason, we produced an incubator capable of creating an environment of -25℃, and constructed an experimental apparatus so that experiments in the room were possible. However, it is necessary to grasp the characteristics of the air reaching the front of the heat pump outdoor unit installed in the experimental apparatus, and flow analysis was performed using ANSYS CFX, which is general-purpose software. As a result, the flow velocity of the air reaching the front of the outdoor unit in the outdoor unit chamber in the entire region of the simulation conditions (5.0 to 7.5 m/s) has many differences in the upper and lower portions, resulting in a natural state. It turned out that the condition can not be satisfied. Therefore, it is determined that it is necessary to additionally install a frequency divider at the front of the outdoor unit to make the flow velocity constant.