• The Journal of the Korean dental association
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• v.20 no.12 s.163
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• pp.1025-1028
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• 1982

1) The authors have had a case of crown fractured upper central incisor with open apex and non vital pulp. 2) The patient was 8 years old female. 3) Apical closure has been induced with the use of calcium hydroxide and gutta percha cone. 4) At nine month after filling with calcium hydroxide and gutta percha cone, apical closure was observed by radiograph. 5) Root canal was permanently filled gutta percha cone and zinc oxide eugenol by the lateral condensation technique.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.10a
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• pp.197-198
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• 2008

The forging process produces complicated and designed components in a die at high productivity for mass production and minimizes the machining amount for favorable material utilization; the forging products used at highly stressed sections are well accepted at a wide range of industry such as automobile, aerospace, electric appliance and et cetera. Accordingly, recent R&D activities have been emphasized on improvement of forging die-life and near net shaping technology for cost effectiveness and better performance. Usually closing and consolidation of internal void defects in a ingot is a vital matter when utilized as large forged products. It is important to develop cogging process for improvement of internal soundness without a void defect and cost reduction by solid forging alone with limited press capacity. For experiments of cogging process, hydraulic press with a capacity of 800 ton was used together with a small manipulator which was made for rotation and overlapping of a billet. Size of a void was categorized into two types; ${\phi}$ 6.0 mm and ${\phi}$ 9.0 mm to investigate the change of closing and consolidation of void defects existed in the large ingot during the cogging process. In addition for forming experiment of piston grown air drop hammer with a capacity of 16 ton was used. The experiment with piston crown was carried out to show the formability and void closing status. In this paper systematic configuration for closing process of void defects were expressed based on this experiment results in the cogging process. Also forging defects through forming process for piston crown was improved using the experiment results and FE analysis. Consequently this paper deals with the effect of radial parameters in cogging process on a void closure far large forged products and formability of piston crown.

• Korean journal of applied entomology
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• v.33 no.4
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• pp.250-256
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• 1994

Flight behavior of Mntsucoccus thunbergianae males and their response to the synthetic sex pheromone, (6R.lOR)-matsuone, were studied in Pinus thunbergiana forests More males were flying around the tree crown than near the ground. A dispenser loaded w~th 50 vg of the pheromone appeared to affect the density of male flights less than 10 meters Sticky traps with 50 pg of the pheromone attracted flylng males, but those with 1 pg were not effectwe in a forest wlth high crown closure, more males were tmpped at upper crown level than near the ground whereas males appeared to be more responsive to pheromone near the ground in a forest with low crown closure Monitoring new scale iniestations with pheromone mps was much more effective than egg sac surveys, the customary detecting procedures Maiing disruption was not achieved by placing 32 mg of pheromone m a space of l X l X l meter.

• Journal of Korean Society of Forest Science
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• v.112 no.4
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• pp.544-553
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• 2023

The purpose of this study was to reveal the thermal comfort and physiological and psychological effects of spending time in broad-leaved forests in suumer. Thirty-one university students (with an average age of 21.4 ± 2.1 years) participated in the study, and a within-subjects experimental design methodology was used. The participants moved to an experimental site (with a crown closure of 76.6%) or a control site (25.9%), sat on a chair to eliminate the impact of movement, and rested for 5 minutes with closed eyes. At this time, thermal comfort, heart rate variability, heart rate, and forehead temperature were continuously measured. After that, blood pressure and pulse rate were measured, and a subjective evaluation was conducted. As a result, spending time at an experimental site showed a statistically significant decrease in the predicted mean vote and the percentage of dissatisfied values, enhancement of parasympathetic nerve activity, decrease of forehead temperature, diastolic blood pressure, heart rate, pulse rate, and improvement of personal thermal sensation (thermal sensation vote and comfort sensation vote). In conclusion, it was found that a forest with high crown closure reduces thermal stress and induces physiological and psychological relaxation.

• Korean Journal of Agricultural and Forest Meteorology
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• v.1 no.2
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• pp.127-134
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• 1999

This study was performed to obtain the basic data to present rational silvicultural tending plan. It makes these widely distributed pine-oak mixed stand and each of pure stand in middle province on object of this study and do comparative analysis of light condition about stand parameter and natural regeneration according to each slope(north, west and south) conditions of location in central part of South Korea. Sample plots for pine-oak mixed stand and pine and oak pure stand were established on each of southern, northern and western slopes based upon site and growth conditions of the slope. Sample plot was a circle of 0.05ha with a diameter of 25.24 m. A sample plot has between 30 and 40 tree in it. Total 23 sample plots were established; 9 pure pine stands, 8 pine-oak mixed stands. and 6 pure oak stands across lower, middle, upper parts of slopes. Relative light intensity within a stand was' measured by crown- photo(fish-eye lens; 180$^{\circ}$) system through fish-eye lens and by comparing each plot with the denuded through PAR-sensor. The crown closure ratio of pure pine stand (75%) shows much lower than that of mixed stand (90.9%) and pure oak stand (93%). The relative light intensity within a stand showed an opposite result. The crown closure of mixed stands tended to become gradually low as the slope moves from the north to the south, but the relative light Intensity within the stand tended to rise. By analyzing the relationship between the relative light intensity within a stand and stand parameter, light intensity within a stand tended to decrease as the diameter and N/ha increase. Number of oak seedlings and light intensity within a stand is in a straight-line regression relation. In particular, the number of oak seedlings was the highest in mixed stands on the southern slope. But no single pine seedling was found. The unfavorable conditions of l0cm thick litter layer and low relative light intensity in a stand (ranging between 4% and 8%) is considered to prevent pine seeds from germinating.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.72-74
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• 2003

Forest canopy density is an ideal representative of the forest habitat situations. It can directly or indirectly depict the canopy structure and gap size in the forestland, thus could be applied to assessment of wildlife’s diversit y. Since population survey of vegetation and wildlife diversities is a key issue for sustainable forest ecosystem management, many research efforts have been focused on forest canopy density using multispectral data in the last two decades. Unfortunately, prediction of canopy density using large scaling remote sensing data remains a challenging issue. Due to recent advances in hyperspectral image sensors hyperspectral imagery is now available for environmental monitoring. In this paper, we conduct experiments to monitor complicated environments of forestland that can be captured by using hyperspectral imagery and further be analyzed to test a prediction model of forest canopy density. The results show that 95% of canopy density could be well described by using 2 difference vegetation indices (DVIs), which are difference of blue and green reflectances rband_100-rband_150 and difference of 2 short wave infrared reflectancse rband_406-rband_410 With the wavelengths of band no. 100, 150, 406, and 410 specified by 462.39 nm, 534.40 nm, 918.22 nm and 924.41 nm respectively.

• Korean Journal of Remote Sensing
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• v.28 no.5
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• pp.587-596
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• 2012

Verifying about eligibility of targeted site is necessary for execute Afforestation and Reforestation Clean Development Mechanism (A/R CDM) project which is followed by system of Kyoto protocol. The site have to be identified by which could not be in conformity with definition of forest. This study tried to propose a technology of classify for site selection of A/R CDM. We chose several parts of Yangpyeng as study area and applied LiDAR data and remotely sensed imagery for considering about tree height, degree of crown closure, and land area which 3 factors for identify forest. LiDAR data was used for offset the shortage of remotely sensed imagery that cannot perfectly determine the forest definition due to absence of 3-dimentional information, but can be obtained from LiDAR. Considering tree height, degree of crown closure, and land area simultaneously by moving window, classified fields to forest and non forest based on pixel size. As a result, 124.06 ha for suitable to doing plantation and approximately 357.02 ha are in negative. Technology that applied for analyzing will provide fundamental methodology not only site selection for A/R CDM, but will be utilized in other Kyoto protocol.

• Journal of Periodontal and Implant Science
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• v.28 no.2
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• pp.273-280
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• 1998

This study was to compare the patients wearing comfortable distally extending cantilever bridges (DECBs) with those having discomfortable ones, in the aspect of the periodontal condition & prosthodontic status. The subjects in the present study were 164 patients appointed to Seoul National University Dental Hospital. One group was consisted of 101 patients wearing comfortable DECBs and the other group were made of 64 patients who had felt discomfort. On clinical parameters, there were no significant difference between 2 groups in plaque index, tooth mobility & probing depth, but gingival index was higher in group wearing discomfortable DECBs. In prosthodontic status, the ratio of pontic oversize was higher in the group of discomfortable DECBs, but there were no significant difference in the view of crown overcontour, overhanging margin & interproximal space closure between 2groups. This study failed to clarify causal factors of discomfortable DECBs.

• Journal of Korean Society of Forest Science
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• v.98 no.4
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• pp.409-416
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• 2009

Forest biomass estimation is essential for greenhouse gas inventories and terrestrial carbon accounting. Remote sensing allows for estimating forest biomass over a large area. This study was conducted to estimate forest biomass and to produce a forest biomass map for Muju county using forest biomass conversion table developed by field plot data from the 5th National Forest Inventory and Landsat TM-5. Correlation analysis was carried out to select suitable independent variables for developing regression models. It was resulted that the height class, crown closure density, and age class were highly correlated with forest biomass. Six regression models were used with the combination of these three stand variables and verified by validation statistics such as root mean square error (RMSE) and mean bias. It was found that a regression model with crown closure density and height class (Model V) was better than others for estimating forest biomass. A biomass conversion table by model V was produced and then used for estimating forest biomass in the study site. The total forest biomass of the Muju county was estimated about 8.8 million ton, or 128.3 ton/ha by the conversion table.

• Korean Journal of Soil Science and Fertilizer
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• v.24 no.3
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• pp.177-182
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• 1991

This study was carried out to clarify the effects of grassland afforestation on some chemical properties of the Japanese ceder(Cryptomeria japonica) forest soil in Cheju Island. The following results were obtained in this study ; 1. T-C, T-N, exch. cations and base saturation in the surface soil(0~10cm) decreased sharply from planting to crown closure. However, after crown closure, exch. Ca and Mg increased considerably. On the other hand, there were no definit changes below surface soil. 2. In vertical distribution of chemical properties, T-C, T-N, exchangeable acidity and exch. cations decreased with soil depth. Especially, exch. Ca and Mg of surface soil in closed stand show a higher value than that in open stand, but there were no variation below surface soil. 3. In closed stand, the amounts of exch. Ca, Mg and K were 1.8 times, 1.6 times and 1.5 times greater than those in open stand. There was no significant difference between open and closed stand in T-C and T-N. 4. The ratios of the amounts of nutrients in surface soil to those in mineral horizons(ha, 50cm) between the open and closed stand showed 30% and 50% for exch. Ca, 30% and 40% for exch. Mg, 38% and 38% for exch. K, respectively.