• Korean Journal of Agricultural and Forest Meteorology
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• v.19 no.1
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• pp.10-18
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• 2017

Korean Red Pine (Pinus densiflora) has been protected and used as the most ecologically and socio-culturally important tree species in Korea. However, as dieback of Korean red pines has occurred in the protected area of the forest genetic resources. The aims of this study is to identify causes for dieback of pine tree by investigating topographical characteristics of pine tree dieback and its correlation to meteorological factors. We extracted the dead trees from the time series aerial images and analyzed geomorphological characteristics of dead tree concentration area. As a result, 1,956 dead pine trees were extracted in the study region of 2,600 ha. Dieback of pine trees was found mostly in the areas with high altitude, high solar radiation, low topographic wetness index, south and south-west slopes, ridgelines, and high wind exposure compared to other living pine forest area. These areas are classified as high temperature and high drought stress regions due to micro-climatic characteristics affected by topographic factors. As high temperature and drought stress are generally increasing with climate change, we can evaluated that a risk of pine tree dieback is also increasing. Based on these geomorphological characteristics, we developed a pine tree dieback risk map using Maximum Entropy Model (MaxEnt), and it can be useful for establishing Korean red pine protection and management strategies.

• Journal of the Korean earth science society
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• v.33 no.6
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• pp.510-518
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• 2012

The Holocene climate change has been studied based on humus analysis of sediments that came from the Nam River basin in the Jinju, Gyeongnam. Humus and soil organic carbon analyses were performed to interpret the climate change and OSL dating and radiocarbon dating were conducted to determine the age of the sediments. The age determinations revealed that the sediments were formed approximately from $10,000{\pm}100$ yr. BP to $4,370{\pm}50$ yr. BP (2,970 BC) The deposits were classified into five layers based on sediments color and texture, and the climate change of each layer has been interpreted. The general climate was found out to be warm. The study result illustrated that section I was the lowest layer and section V the highest among the five surveyed sections. One the other hand, relatively cold events were detected in the sections ranging from I and II to III in terms of temperature. In term of humidity, sections II and III are estimated to have been relatively dry. Sections IV and V were relatively warm and dry, and the section IV tends to be warmest of the entire sedimentary. In addition, there is a tendency that the total soil organic carbon shows relatively high values under the cooler and humid climatic condition.

• Restorative Dentistry and Endodontics
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• v.34 no.2
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• pp.113-119
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• 2009

The purpose of this study was to compare the tensile bond strength of several self-adhesive resin cements bonded to dentin surfaces with different wet conditions. Three self-adhesive resin cements: Rely-X Unicem (3M ESPE, St. Paul, MN. USA). Embrace Wetbond (Pulpdent. Oakland. MA. USA). Maxcem (Kerr. Orange. CA. USA) were used. Extracted sixty human molars were used. Each self-adhesive resin cement was adhered to the dentin specimens (two rectangular sticks from each molar) in different wet conditions. Tensile bond strength were measured using universal testing machine (EZ Test. Shimadzu corporation. Kyoto. Japan) at a crosshead speed of 1.0mm/min. After the testing. bonding failures of specimens were observed by Operative microscope (OPMI pro, Carl Zeiss. Oberkochen, Germany). T-test was used to evaluate the effect of dentin surface wetness. One-way ANOVA test was used to evaluate the tensile bond strength of self-adhesive resin cements in the same condition. Scheffe's test was used for statistical analyzing at the 95% level of confidence. The result showed that wetness of dentin surface didn't affect tensile bond strength of self-adhesive resin cements and Maxcem showed the lowest tensile bond strength.

• Food Engineering Progress
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• v.21 no.3
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• pp.267-272
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• 2017

To improve dispersibility of cereal powder without additives, granulation of cereal powder was conducted using fluidized-bed granulator. Operation condition was sample 300 g, internal temperature $40^{\circ}C$, ventilation speed $30-90m^3/h$, inlet temperature $90^{\circ}C$ and spray pressure 2.5 bar. The amount of distilled water (20-45%) as binder, granulation time (10-15 min) and drying time (3-10 min) were controlled. Mean diameter over volume (Brouckere mean, $D_{4,3}$) was increased from $123{\mu}m$ to $263{\mu}m$ and dispersibility was improved from 73% to 92.25% at experiment conditions. Wettability (wetting time) was drastically decreased from 5,000 second to 7 second. Granulation of cereal powder did not affect sinkability and mean diameter over volume as wet analysis was about the same between raw and granulated cereals. Such phenomenon means that granulation with only water as binder enables cereal powder to disperse in water or milk without rapid sedimentation.

• Journal of the Korean Geotechnical Society
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• v.39 no.1
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• pp.15-25
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• 2023

Recent weather changes have led to an increase in heavy rainfall resulting in frequent large-scale slope failures. To minimize damage to life and property, a measurement system is used in slope failure warning systems. However, understanding the slope failure behavior is difficult as the measurement system only measures a specific point. Therefore, numerical analysis must be p erformed with the measurement system. The soil water characteristic curve (SWCC) drying curve and boundary conditions that consider evapotranspiration and precipitation have been applied to numerical analysis, but the hysteresis of SWCC affects the numerical analysis results. To address this, a new evapotranspiration calculation method is proposed and applied to boundary conditions, and the measurement data are compared with the results of the numerical analysis. This method takes into account the different infiltration behaviors on evapotranspiration according to the drying and wetting curves of the SWCC, and allows for a more rational prediction of water movement on unsaturated slopes.

• Journal of the Korean Geosynthetics Society
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• v.10 no.2
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• pp.73-79
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• 2011

Based on the results of Part 1 of our two-parts paper, the possibility on field applicability of CMDS(Coal Mine Drainage Sludge) mixed with bentonite and cement as a liner in landfill sites was investigated. The optimum moisture content that met the landfill liner condition was obtained when the ratio of CMDS: bentonite: cement was 1: 0.5: 0.3 in a lab-scale. The relative compaction was measured in 90.1%, which results for construction field have been generally acceptable. In this study, a large-scale Lysimeter($1.0m{\times}1.5m{\times}2.0m$) was used to simulate the effects of the layer on the freeze/thaw by -20 average temperature. The mixture after freezing/thawing showed compressive strength more than $5kg/cm^2$, which was satisfied with EPA standards. Initial permeability of CMDS was $7.10{\times}10^{-7}cm/s$ and permeability its mixture after freezing/thawing was increased to $9.80{\times}10^{-7}cm/s$. The change of temperature in the layers rises and falls with linear and temperature gradient keep maintain the present state. Moisture contents in the layers have not been radically changed. Through the leaching test determined by KSLT method, it was found that heavy metals excluding Zn and Ni were not leached out or leached out less than the standards during 7 cycles of freezing/thawing process. Since it shows the increased permeability about 1.5 times and slight change in moisture content, but it was satisfied with EPA standar through 7 cycles of freezing/thawing process, this mixture can be applied as a liner in landfill final cover system.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.4
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• pp.609-617
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• 2000

This study is aimed at investigating an effect of HCl gas on selective reduction of NOx over a CuHM and $V_2O_5-WO_3/TiO_2$ catalyst. SCR process is the most effective method to remove NOx, but catalyst can be deactivated by the acidic gas such as HCl gas which is also included in flue gas from the incinerator. In dry condition of flue gas, the CuHM catalyst treated by HCl gas has shown higher NO removal activity than the fresh catalyst. The activity of the catalyst can be restored by treating at $500^{\circ}C$. On the contrary. $V_2O_5-WO_3/TiO_2$ catalyst is obviously deactivated by HCl and the deactivation increases in proportion to the concentration of HCl gas. The deactivated catalyst is not restored to it's original activity by heat treatment for regeneration. In wet flue gas stream, the CuHM catalyst has shown lower activity than fresh catalyst and $V_2O_5-WO_3/TiO_2$ catalyst was severely deactivated by HCl treatment. The activity loss of catalysts are mainly due to the decrease of Br$\ddot{o}$nsted acid site on the catalyst surface by $NH_3$ TPD. The change of BET surface area of CuHM catalyst after the reaction isn't observed but $V_2O_5-WO_3/TiO_2$ catalyst is observed. The amount of $Cu^{{+}{+}}$ and $V_2O_5$ is decreased after the reaction. From these results, it is expected that CuHM catalyst should be better than $V_2O_5-WO_3/TiO_2$ catalyst for its application to the incineration of flue gas.

• Restorative Dentistry and Endodontics
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• v.35 no.5
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• pp.335-343
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• 2010

Objectives: To compared the effect of different levels of moisture of root canal on the sealing ability after filling with four different types of sealer. Materials and Methods: Single-rooted teeth (n = 90) instrumented to and apical size of 0.06 / 45 were randomly assigned to 12 experimental groups (n = 7 per group), positive/negative control groups (n = 3 per group). The teeth of the experimental groups (a. DRY; b. PAPER POINT DRY; c. WET) were obturated with sealer (Group 1-3: Sealapex; Group 4-6: AH plus; Group 7-9: Tubuli-seal; Group 10-12: EndoRez) and warm vertical compaction method. After 7 days in $37^{\circ}C$, 100% humidity, the coronal-to-apical microleakage was evaluated quantitatively using a glucose leakage model. The leaked glucose concentration was measured with spectrophotometer at 1, 3, 7, 14, 21, and 30 days. Data were recorded ad mmol/L and statistically analysed with the two-way ANOVA and Duncan test (p = 0.05). Results: Throughout the experimental period Tubuli-seal/WET (Group 9) showed the highest mean cumulative glucose penetration (178.75 mmol/L), whereas AH plus/DRY (Group 4) had the least (20.78 mmol/L). Conclusions: The results of this study demonstrated that the moisture condition of root canals at the time of obturation and the type of sealer that was used had a significant effect on leakage and sealing ability. Thus drying procedure according to sealer types is a critical step and should not be missed in endodontic treatment.

• Korean Journal of Agricultural Science
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• v.4 no.2
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• pp.157-166
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• 1977

These experiments were carried out to analyse the correlation among various soil parameters which characterize the mechanical properties of the disturbed and undisturbed soil, and to analyse Atterberg Limits for the basin of downstream of Hanriver Keum river, Nakdong river, and Asan bay. 1. Wet density of soil was the lowest in the basin of Nakdong river which contains the highest amount of clay minerals among the soil samples, and was increased in the order of Han river, Keum river and Asan bay. It was appeared that the unit weight of natural soil was changed in accordance with the clay mineral content which determines the moisture content. 2. Curved relationship was recognized, showing that dry density of soil was decreased with increasing the moisture content. Soils from the basin of Asan bay were appeared to have the highest dry density and the next was those of Keum river, the second lowest Han river, and the lowest Nakdong river. 3. When the liquid limit of soils was over 40 percent, their plastic index was above the A-line of plastic chart. 4. Between dry density and void ratio of soils, a curved relationship was found, in which dry density was decreased as void ratio increased, and the differences between them became greater in soils containing higher amount of coarse grained soil. Decreasing tendency of dry density in accordance with increase of void ratio was the most significant at Asan bay which contained the lowest clay content, and other decreasing order of dry density was Keum river, Han river, and Nakdong river.

• Korean Journal of Agricultural and Forest Meteorology
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• v.15 no.2
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• pp.85-101
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• 2013

In order to search for distribution characteristics on C4 plants at the paddy fields, uplands, orchard and roadside in South Korea, vascular plants were investigated. Flora investigation had been carried out from May 2002 to October 2006 at 241 plots. In the results of survey, the flora of these areas consist of 74 families, 231 genera and 352 species totally. The class frequencies were arranged by the order of Magnoliopsidae (255 species), Monocotyledoneae (89 species), Pteropsida (7 species) and Sphenopsida (1 species). The number of species in each investigated agricultural field types was 55 families with 203 species in paddy field, 49 families with 218 species in uplands, 44 families with 115 species in orchard and 48 families with 202 species in roadside respectiviely. Representative species compositions of these four agricultural field types were characterized by Artemisia princeps, Persicaria thunbergii in paddy field, Artemisia princeps, Erigeron annuus in upland and roadside, Commelina communis, Digitaria ciliaris in orchard, respectively. Therefore, indicative species in agricultural ecosystem was Artemisia princeps. Among the investigated 352 species, $C_4$ plants identified were 38 species, and the occurrence ratio of $C_4$ monocotyledonous plants were higher in paddy field, orchard and roadside than upland. Such differences in the occurrence ratio of $C_4$ plants under diverse agricultural field types reflect differences in environmental condition such as micro-climate, soil moisture under various agricultural fields. Dominant $C_4$ monocotyledonous plants were Digitaria ciliaris and Commelina communis, while $C_4$ dicotyledonous plants were Amaranthus mangostanus and Chenopodium album var. centrorubrum in agricultural fields. Naturalized plants were identified as 47 species and occurrence ratio were higher in upland and roadside than other agricultural field types. Among the investigated naturalized plants, $C_4$ plants were Amaranthus mangostanus and Amaranthus retroflexus. Distribution characteristics of representative $C_4$ plants in agricultural field types, revealed that the projected increase in temperature due to climate change may provide better conditions for the growth of $C_4$ plants. Thus, the necessity of long-term monitoring should be conducted on the diffusion of $C_4$ plants that may threaten influence agroecosystem in Korea.