• 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 Intelligence and Information Systems
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• v.26 no.2
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• pp.43-56
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• 2020

Recommender systems help users make the best choice among various options. Especially, recommender systems play important roles in internet sites as digital information is generated innumerable every second. Many studies on recommender systems have focused on an accurate recommendation. However, there are some problems to overcome in order for the recommendation system to be commercially successful. First, there is a lack of transparency in the recommender system. That is, users cannot know why products are recommended. Second, the recommender system cannot immediately reflect changes in user preferences. That is, although the preference of the user's product changes over time, the recommender system must rebuild the model to reflect the user's preference. Therefore, in this study, we proposed a recommendation methodology using topic modeling and sequential association rule mining to solve these problems from review data. Product reviews provide useful information for recommendations because product reviews include not only rating of the product but also various contents such as user experiences and emotional state. So, reviews imply user preference for the product. So, topic modeling is useful for explaining why items are recommended to users. In addition, sequential association rule mining is useful for identifying changes in user preferences. The proposed methodology is largely divided into two phases. The first phase is to create user profile based on topic modeling. After extracting topics from user reviews on products, user profile on topics is created. The second phase is to recommend products using sequential rules that appear in buying behaviors of users as time passes. The buying behaviors are derived from a change in the topic of each user. A collaborative filtering-based recommendation system was developed as a benchmark system, and we compared the performance of the proposed methodology with that of the collaborative filtering-based recommendation system using Amazon's review dataset. As evaluation metrics, accuracy, recall, precision, and F1 were used. For topic modeling, collapsed Gibbs sampling was conducted. And we extracted 15 topics. Looking at the main topics, topic 1, top 3, topic 4, topic 7, topic 9, topic 13, topic 14 are related to "comedy shows", "high-teen drama series", "crime investigation drama", "horror theme", "British drama", "medical drama", "science fiction drama", respectively. As a result of comparative analysis, the proposed methodology outperformed the collaborative filtering-based recommendation system. From the results, we found that the time just prior to the recommendation was very important for inferring changes in user preference. Therefore, the proposed methodology not only can secure the transparency of the recommender system but also can reflect the user's preferences that change over time. However, the proposed methodology has some limitations. The proposed methodology cannot recommend product elaborately if the number of products included in the topic is large. In addition, the number of sequential patterns is small because the number of topics is too small. Therefore, future research needs to consider these limitations.

• Journal of Korean Society of Transportation
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• v.22 no.6
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• pp.133-144
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• 2004

A model and a measure which can evaluate the risk of rear end collision are developed. Most traffic accidents involve multiple causes such as the human factor, the vehicle factor, and the highway element at any given time. Thus, these factors should be considered in analyzing the risk of an accident and in developing safety models. Although most risky situations and accidents on the roads result from the poor response of a driver to various stimuli, many researchers have modeled the risk or accident by analyzing only the stimuli without considering the response of a driver. Hence, the reliabilities of those models turned out to be low. Thus in developing the model behaviors of a driver, such as reaction time and deceleration rate, are considered. In the past, most studies tried to analyze the relationships between a risk and an accident directly but they, due to the difficulty of finding out the directional relationships between these factors, developed a model by considering these factors, developed a model by considering indirect factors such as volume, speed, etc. However, if the relationships between risk and accidents are looked into in detail, it can be seen that they are linked by the behaviors of a driver, and depending on drivers the risk as it is on the road-vehicle system may be ignored or call drivers' attention. Therefore, an accident depends on how a driver handles risk, so that the more related risk to and accident occurrence is not the risk itself but the risk responded by a driver. Thus, in this study, the behaviors of a driver are considered in the model and to reflect these behaviors three concepts related to accidents are introduced. And safe stopping distance and accident occurrence probability were used for better understanding and for more reliable modeling of the risk. The index which can represent the risk is also developed based on measures used in evaluating noise level, and for the risk comparison between various situations, the equivalent risk level, considering the intensity and duration time, is developed by means of the weighted average. Validation is performed with field surveys on the expressway of Seoul, and the test vehicle was made to collect the traffic flow data, such as deceleration rate, speed and spacing. Based on this data, the risk by section, lane and traffic flow conditions are evaluated and compared with the accident data and traffic conditions. The evaluated risk level corresponds closely to the patterns of actual traffic conditions and counts of accident. The model and the method developed in this study can be applied to various fields, such as safety test of traffic flow, establishment of operation & management strategy for reliable traffic flow, and the safety test for the control algorithm in the advanced safety vehicles and many others.

• Water for future
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• v.5 no.1
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• pp.27-36
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• 1972

This thesis is the study of the rainfall probability depth in the major areas of Korea, such as Seoul, Pusan and Taegu. The purpose of the paper is to analyze the rainfall in connection with the safe planning of the hydraulic structures and with the project life. The methodology used in this paper is the statistical treatment of the rainfall data in the above three areas. The scheme of the paper is the following. 1. The complementation of the rainfall data We tried to select the maximm values among the values gained by the three methods: Fourier Series Method, Trend Diagram Method and Mean Value Method. By the selection of the maximum values we tried to complement the rainfall data lacking in order to prevent calamities. 2. The statistical treatment of the data The data are ordered by the small numbers, transformed into log, $\sqrt{}, \sqrt[3]{}, \sqrt[4], and$\sqrt[5], and calculated their statistical values through the electronic computer. 3. The examination of the distribution types and the determination of the optimum distibution types By the $x^2-Test$ the distribution types of rainfall data are examined, and rejected some part of the data in order to seek the normal rainfall distribution types. In this way, the optimum distribution types are determined. 4. The computation of rainfall probability depth in the safety project life We tried to study the interrelation between the return period and the safety project life, and to present the rainfall probability depth of the safety project life. In conclusion we set up the optimum distribution types of the rainfall depths, formulated the optimum distributions, and presented the chart of the rainfall probability depth about the factor of safety and the project life.ct life.

• Research in Plant Disease
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• v.12 no.2
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• pp.91-98
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• 2006

A filtrate powder, designated as KNF2022, produced from culture broth of Acinetobacter sp. KTB3 was tested for their inhibitory effects on Pepper mild mottle virus (PMMoV) infection to Nicotiana glutinosa or N. tabacum cv. Xanthi nc. When 1/100 dilution with distilled water was treated to the plants and PMMoV was inoculated, the inhibition was estimated to be 94.3 and 95.6%, respectively. The same concentrations of KNF2022 inhibited infections of Pepper mottle virus (PepMoV) and Cucumber mosaic virus (CMV) on Chenopodium amaranticolor by 97.1 and 92.5%, respectively. Duration of inhibitory activity of the filtrate powder from Acinetobacter sp. culture broth against PMMoV infection on N. glutinosa was maintained for 2 days at 80% inhibition level, however, the inhibitory effect was diminished from 4 days after treatment to 50% levels. To evaluate inhibitory effects on systemic host plants of the antiviral agent, symptom developments of PMMoV, PepMoV and CMV on KNF2022-treated pepper plants were investigated. Delayed symptom developments until 10 days after inoculation (DAI) were observed for all the three viruses when the viruses were inoculated individually, and these delayed symptom development effects were maintained until 30 DAI in case of PepMoV. Moreover, PepMoV was not detected by RT-PCR and ELISA until 30 DAI. These delayed symptom development effects were diminished in all combinations of three virus co-inoculations due to synergism of three viruses on symptom developments. Inhibitory effect of KNF2022 was verified under electron microscopic examinations using purified virus preparations. Particles of PMMoV and PepMoV were observed on specimens from 5 min after KNF2022 treatment, and the particle sizes were reached in the range of 200-250 nm and 400-600 nm, respectively. Furthermore, the viral particles were destructed and particle sizes were reached in the range of 100-150 nm and 300-500 nm, respectively, on 60 min after treatments. Reduction of local lesion numbers on N. tabacum cv. Xanthi nc and C. amaranticolor were accompanied with reduction of virus particle sizes. In the case of CMV destructed particle numbers were also increased according to incubation period after KNF2022 treatment and local lesions on C. amaranticolor were reduced.

• Journal of the Korean Association of Geographic Information Studies
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• v.25 no.1
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• pp.28-43
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• 2022

This study classified UAV image-based physical spatial types for parks in urban areas of Changwon City and analyzed thermal comfort characteristics according to physical spatial types by comparing them with ENVI-met thermal comfort results. Physical spatial types were classified into four types according to UAV-based NDVI and SVF characteristics. As a result of ENVI-met thermal comfort, the T_MRT difference between the tree-dense area and other areas was up to 30℃ or more, and it was 19. 6℃ at 16:00, which was the largest during the afternoon. As a result of analyzing UAV-based physical spatial types and thermal comfort characteristics by time period, it was confirmed that the physical spatial types with high NDVI and high SVF showed a similar to thermal comfort change patterns by time when using UAV, and the physical spatial types with dense trees and artificial structures showed a low correlation to thermal comfort change patterns by time when using UAV. In conclusion, the possibility of identifying the distribution of thermal comfort based on UAV images was confirmed for the spatial type consisting of open and vegetation, and the area adjacent to the trees was found to be more thermally pleasant than the open area. Therefore, in the urban planning stage, it is necessary to create an open space in consideration of natural covering materials such as grass and trees, and when using artificial covering materials, it is judged that spatial planning should be done considering the proximity to trees and buildings. In the future, it is judged that it will be possible to quickly and accurately identify urban climate phenomena and establish urban planning considering thermal comfort through ground LIDAR and In-situ measurement-based UAV image correction.

• Journal of Korea Water Resources Association
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• v.55 no.6
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• pp.393-404
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• 2022

Reliable terrestrial rainfall observations from satellites at finer spatial resolution are essential for urban hydrological and microscale agricultural demands. Although various traditional "top-down" approach-based satellite rainfall products were widely used, they are limited in spatial resolution. This study aims to assess the potential of a novel "bottom-up" approach for rainfall estimation, the parameterized SM2RAIN model, applied to the C-band SAR Sentinel-1 satellite data (SM2RAIN-S1), to generate high-spatial-resolution terrestrial rainfall estimates (0.01° grid/6-day) over Central South Korea. Its performance was evaluated for both spatial and temporal variability using the respective rainfall data from a conventional reanalysis product and rain gauge network for a 1-year period over two different sub-regions in Central South Korea-the mixed forest-dominated, middle sub-region and cropland-dominated, west coast sub-region. Evaluation results indicated that the SM2RAIN-S1 product can capture general rainfall patterns in Central South Korea, and hold potential for high-spatial-resolution rainfall measurement over the local scale with different land covers, while less biased rainfall estimates against rain gauge observations were provided. Moreover, the SM2RAIN-S1 rainfall product was better in mixed forests considering the Pearson's correlation coefficient (R = 0.69), implying the suitability of 6-day SM2RAIN-S1 data in capturing the temporal dynamics of soil moisture and rainfall in mixed forests. However, in terms of RMSE and Bias, better performance was obtained with the SM2RAIN-S1 rainfall product over croplands rather than mixed forests, indicating that larger errors induced by high evapotranspiration losses (especially in mixed forests) need to be included in further improvement of the SM2RAIN.

• Journal of the Korean Institute of Landscape Architecture
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• v.50 no.2
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• pp.1-22
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• 2022

The modification effects of street trees on outdoor thermal comfort in summertime according to tree planting types and road direction were analyzed using a computer simulation program, ENVI-met. With trees, the air temperature and wind speed decreased, and the relative humidity increased. In the case of mean radiant temperature (T_mrt) and human thermal sensation, physiological equivalent temperature (PET) and universal thermal climate index (UTCI), there was a decrease during the daytime. The greatest change among the meteorological factors by trees happened in Tmrt, and PET and UTCI showed similar patterns with T_mrt·The most effective tree planting type on thermal comfort modification was low tree height, wide tree crown, high leaf area index, and narrow planting interval (LWDN). T_mrt, PET and UTCI showed a large difference depending on shadow patterns of buildings and trees according to solar altitude and azimuth angles, and building locations. When the building shade areas increased, the thermal modification effect by trees decreased. In particular, results on the east and west sidewalks showed a large deviation over time. When applying the LWDN, the northwest, west and southwest sidewalks showed a significant reduction of 8.6-12.3℃ PET and 4.2-4.5℃ UTCI at 10:00, and the northeast, east and southeast sidewalks showed 8.1-11.8℃ PET and 4.4-5.0℃ UTCI at 16:00. On the other hand, when the least effective type (high tree height, narrow tree crown, low leaf area index, and wide planting interval) was applied, the maximum reduction was up to 1.8℃ PET and 0.9℃ UTCI on the eastern sidewalks, and up to 3.0℃ PET and 0.9℃ UTCI on the western ones. In addition, the difference in modification effects on T_mrt, PET and UTCI between the tree planting types was not significant when the tree effects were reduced by the effects of buildings. These results can be used as basic data to make the most appropriate street tree planting model for thermal comfort improvement in urban areas in summer.

• Food Science and Preservation
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• v.31 no.1
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• pp.149-160
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• 2024

Dextran is a glucose homo-polysaccharide with a predominantly α-1,6 glycosidic linkage of microbial source and is known to be produced primarily by lactic acid bacteria. However, it can also be obtained through the dextran dextrinase of acetic acid bacteria (Gluconobacter oxydans). The dextrin-based dextran was obtained from rice starch using G. oxydans fermentation of rice hydrolysate, and its properties were studied. Both dextrin- and rice hydrolysate-added media maintained the OD value of 6 after 20 h of incubation with acetic acid bacteria, and the gel permeation chromatography (GPC) analysis of the supernatant after 72 h of incubation confirmed that a polymeric material with DP of 480 and 405, which was different from the composition of the substrate in the medium, was produced. The glucose linkage pattern of the polysaccharide was confirmed using the proton nuclear magnetic resonance (¹H-NMR) and the increased α-1,4:α-1,6 bond ratio from 0.23 and 0.13 to 1:2.37 and 1:4.4, respectively, indicating that the main bonds were converted to α-1,6 bonds. The treatment of dextrin with a rat-derived alpha-glucosidase digestive enzyme resulted in a slow release of glucose, suggesting that rice hydrolysate can be converted to dextran using acetic acid bacteria with glycosyltransferase activity to produce high-value bio-materials with slowly digestible properties.

• Korean Journal of Applied Biomechanics
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• v.12 no.2
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• pp.109-130
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• 2002

The purpose of this paper was to make a comparative analysis for the difference of the various kinematic variation which is occurred in the each situation when pitchers throw a straight and a curve ball. Four pitchers, who are two national team players and two high level pitchers, were selected among the right over hand pitchers of D university in the Busan for this paper. The data were analyzed by using 3D equipment. The results of the analysis which was about the elapsed time of the pitching, the movement of the body center-point, the highest height of the left knee, stride length, knee joint angle, shoulder joint angle, elbow joint angle and wrist joint angle in the each section(ST, LKU, HBP, LCF, MCP, BRP) were as follows : 1. Pitching time in the each section and step in the pitching for straight and curve ball was similar. The total elapsed time of the straight and curve ball was 1.78${\pm}$0.07sec and 1.77${\pm}$0.11sec in the order. 2. The position change of the body center to the Z(above below) direction did not show significant difference in the each situation of the section and step between pitching for the straight and curve ball. 3. Height of the left knee did not show significant difference as 125.38${\pm}$11.85cm and 124.95${\pm}$11.63m in the each pitching motion for straight and curve ball. The rate(%H) between height and stride length showed 68.42${\pm}$5.53(%H), 68.40${\pm}$5.45(%H) in the each pitching motion. 4. Pitching for curve ball showed longer stride length than pitching for straight ball that as the stride length was 140.35${\pm}$4.96cm and 144.8${\pm}$1.69cm. The rate(%H) between height and stride length showed 76.9${\pm}$3.77(%H), 79.39${\pm}$2.23(%H) in the each pitching motion. 5. Left knee joint angle did not show significant difference in the ST, LKU and HBP section in the each pitching motion. However, it was shown that knee joint angle was flexed much more in the LFC, MCP and BRP section in the pitching for curve ball. 6. Right shoulder joint angle did not show significant difference in the ST, LKU and HSP section. However, when pitches threw a curve ball in the LKU section. In the LFC section, the right shoulder joint angle was extended much more in the pitching for curve ball, and the angle was extended much in the MCP and BRP section in the pitching for curve ball than straight ball. 7. Right elbow joint angle did not show significant difference in the ST, LKU and HRP section in the two pitching motion. The angle had more flexion in the LFC and MCP section in the pitching for curve ball than the pitching for straight ball. The angle in the each pitching motion for straight ball and curve ball were extended by a narrow margin in the BRP section. 8. Right wrist joint angle was extended much more in the LFC and MCP section in the pitching for curve ball. In the BRP section, the angle was extended much more in the pitching for straight ball than curve ball.