• Journal of the Korean Association of Geographic Information Studies
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• v.20 no.3
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• pp.181-194
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• 2017

This study aims to develop a regression model for forest volume estimation using field-collected forest inventory information and airborne LiDAR data. The response variable of the model is forest stem volume, was measured by random sampling from each individual plot of the 30 circular sample plots collected in Bonghwa-gun, Gyeong sangbuk-do, while the predictor variables for the model are Height Percentiles(HP) and Height Bin(HB), which are metrics extracted from raw LiDAR data. In order to find the most appropriate model, the candidate models are constructed from simple linear regression, quadratic polynomial regression and multiple regression analysis and the cross-validation tests were conducted for verification purposes. As a result, $R^2$ of the multiple regression models of $HB_{5-10}$, $HB_{15-20}$, $HB_{20-25}$, and $HBgt_{25}$ among the estimated models was the highest at 0.509, and the PRESS statistic of the simple linear regression model of $HP_{25}$ was the lowest at 122.352. $HB_{5-10}$, $HB_{15-20}$, $HB_{20-25}$, and $HBgt_{25}-based$ models, thus, are comparatively considered more appropriate for Korean forests with complicated vertical structures.

• Journal of the Korean Chemical Society
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• v.46 no.3
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• pp.265-278
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• 2002

A concept test was administered to college students and teachers to identify their understanding of chemical equilibrium and equilibrium shift. The subjects were 53 freshmen in the General Chemistry class, 28 juniors in the Physical Chemistry class and 26 seniors from a university and 10 high school teachers in Seoul. Test items include the calculations of partial pressure and concentration of the gas in the mixture, the equilibrium constant cal-culation and the prediction of equilibrium shift when an inert gas is added to the gaseous reaction system, and the equilibrium concentration calculation and the prediction of equilibrium shift when water or common ion is added to the weak acid solution. The test was focused to identify whether the subjects can predict equilibrium shift using the reaction quotient change for the situations in which Le Chatelier principle is difficult to apply. The results showed that the achievements of teachers and juniors were significantly higher than those of freshmen and seniors. Many stu-dents had difficulties in predicting equilibrium shift using the reaction quotient while they could calculate partial pres-sure and concentration for the same situation. It means they are lack of conceptual understanding of chemical equilibrium shift.

• Journal of Korean Ophthalmic Optics Society
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• v.16 no.1
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• pp.13-19
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• 2011

Purpose: The purpose of this study was to assess characterize overseas company's Cellulose acetate glasses frame sheets (overseas company's CA sheet) Also, the optimum content of plasticizer and melt extrusion condition of industrial CA resin were established for appropriate glasses frame. Methods: Overseas company's Cellulose acetate glasses frame sheets (overseas company's CA sheet) were characterized by $^1H$-NMR, GPC, and TGA. Also, the optimum content of plasticizer and melt extrusion condition of industrial CA resin were established. Results: The plasticizer of overseas company's CA sheet measured by $^1H$-NMR was diethyl phthalate, and its content was measured 30 wt% by TGA. Also, industrial CA resin showed enough melting behavior in the range of 190~200$^{\circ}C$. Compared to overseas company's CA sheet's tensile strength value of 2.2~2.8 kgf/$mm^2$, industrial CA resin exhibited sufficient tensile strength value of 2.3 kgf/$mm^2$ for glasses frame. Conclusions: Industrial CA resin with 30 wt% plasticizer content would be a promising material for glasses frame prepared by melt extrusion to replace China CA sheet.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.15 no.4
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• pp.343-353
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• 2017

Processing and equipment were tailored for engineering scale fabrication of $UO_2$ porous pellets, a feed material for the electrolytic reduction process in the PRIDE (PyRoprocessing Integrated DEmonstration) facility at KAERI (Korea Atomic Energy Research Institute). The starting materials, $UO_2$ powder and pre-milled surrogate oxide powders, were proportioned to simulate the chemical composition of spent fuel (so-called Simfuel). The Simfuel powders were homogenized by mixing, compacted into a pellet shape, and finally heat treated using a tumbling mixer, rotary press, and sintering furnace. After sintering at $1450^{\circ}C$ for 24 h in $4%\;H_2-Ar$, the average bulk density of the $UO_2$ Simfuel pellets was $6.89g{\cdot}cm^{-3}$, which meets the standard of the following electrolytic reduction process. In addition, the results of a microstructural analysis demonstrated that the sintered Simfuel $UO_2$ porous pellets accurately simulate the properties of spent fuel in terms of the formation of second phases. These results provide essential information for the massive fabrication of $UO_2$ porous pellets for engineering scale pyroprocessing research.

• Resources Recycling
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• v.24 no.3
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• pp.59-65
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• 2015

Recycling of vulcanized rubber products is a serious problem in the world. A quantity of generated waste tires becomes much more and more because of increasing demands on automobiles, resulted in the cause of serious secondary pollution by sulfur component that is crosslinked to incineration or landfill. In addition, crosslinked surfur is used to interfere with the binding of the raw material rubber. In this study, we analyzed the degree of devulcanization by the chemical devulcanization. Devulcanization ratio of the samples were systematically analysed by variables such as time and temperature. In addition, the effect of swelling method as a pre-treatment process was also measured. A rubber specimen was deepened in a organic 2-buthanol solutions during various times of 1 ~ 5 hrs at 100, 150, $200^{\circ}C$ respectively, then to calculate the crosslink density and the number average molecular weight by using a parallel expansion process, which showed devulcanization degree of analyzed samples quantitatively. Also, the mechanical properties were measured with the samples prepared by using a hot press.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.25 no.3
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• pp.1-8
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• 1980

Eight different weed community types growing in association with transplanted rice were identified in the experimental fields used in these studies. The Importance Value (LV.) of weed species growing in association with rice changed with time. The I. V. of Echinochloa glabrescens Munro ex Hook f. increased from 40 days after transplanting (DAT) until heading and then, decreased from heading to maturity of rice. However, the LV. of Monochoria vaginalis (Burm.) Pres!. and Echinochloa crus-galli ssp. hispidula (Retz.) Honda increased from 40 DAT to maturity while Scirpus maritimus L. decreased from 40 DAT. There was a high negative correlation between grain yield and weed weight at rice heading in all weed communities. The competitive ability of rice against weeds varied depending upon weed species. The highest yield decrease due to weed competition was obtained from the E. crus-galli ssp. hispidula-S. Maritimus community. Forty-two percent yield reduction was caused by competition of 100g dry weight of weeds per square meter of this community type at rice heading. The yield decrease for the same amount of weeds was 10% for the E. glabrescens community, 15% for the M vaginalis community and the M vaginalis-Scirpus supinus L. community and 21% for the M vaginalis-E. glabrescens-Fimbristylis littoralis Gaud.-S. maritimus community type.

• Journal of the Korean Ceramic Society
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• v.35 no.5
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• pp.421-428
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• 1998

The effect of silane coupling agents on the water stability of HAC/PVA based MDF cement composites which were modified with urethane and epoxy resin were studied as a function of the functional groups and addition amount of silane coupling agent. According to the composition of polymer matrix the silanes with different functional groups showed the different effectiveness. In case of the only PVA matrix the silane with vinyl functional group was more effective than other silanes. When the epoxy resin was added the silane of epoxy-methodxy group enhanced the flexural strength of dry and wet state more than other. In case of urethane-added MDF cement the silane of diamine group was effective and enhanced the water sta-bility fo MDF cement composite more and more as the addition amount of silane increased, Especially in case of warm-presed composite the effect of silane was enhanced By addition of 2wt% of silane with 야-amine group the flexural strength of urethane-added composites were enhanced by 20% more in dry state 40-70% in wet state in accord with the porosity analysis. The flexural strength of the poxy resin-added MDF cement composite was increased by addition of 1wt% and 2wt% silane of epoxy-methoxy group However the addition of 4wt% of silane decreased the flexural strength of dry and wet state by formation of closed pore in the polymer matrix.

• Korean Journal of Cognitive Science
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• v.24 no.4
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• pp.365-391
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• 2013

Negative repetition effect (NRE) refers to the phenomenon that the accuracy of report is impaired when a target was flanked by the same distractor than when by alternative distractor. To probe the nature of NRE, this study introduced attention window(s) indicating the positions where a target might be presented, and non-attention window(s) where a target could not be presented. Attention windows are supposed to help participants detect targets readily. Two among three positions are indicated by attention windows in Exp. 1, and a single large attention window encompassing central two positions among four positions was used in Exp. 2, and either large or small attention window was used depending on the number of target candidates in Exp. 3. In the result of three experiments, NREs were consistently observed when both positions of a target and a distractor were indicated by previous attention windows. However, NREs (including its tendency) and its opposite, PREs were observed when a distractor was presented in the non-attention position, depending on its distance from the target and the size of attention window. It seems that this pattern of repetition effects is hard to be explained by repetition blindness hypothesis (Kanwisher, 1991), positional uncertainty hypothesis (Keren & Boer, 1985), and inhibitory attention capture hypothesis (Kwak et al., 1993). Instead it was proposed that shifting of spatial attention should be considered accordingly with the structure of stimulus display. The promising role of this task was discussed in studying the relation of attention and perception.

• Resources Recycling
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• v.14 no.4 s.66
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• pp.22-33
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• 2005

Four sheet-shaped and one soft-shaped self-sealing waterproof materials were prepared to recycle some GRT(Ground Rubber Tires). Their physical properties were tested to consider characteristics of them. The self-sealing waterproof materials were consisted of GRT/super absorbent polymer(SAP)/binder and mold by a hot press after mixing with a batch-typed internal mixer. The average size of GRT particles was -40 mesh, SAPs were commercial GE-500F and poly(AM-SAS-AA) prepared in this work. Binders were PU. EVA, LDPE, SBR, and poly(2-EHA). And PU film was attached to improve the properties of waterproof materials. Characteristics of self-sealing waterproof materials consisted of by GRT/GE-500F/EV-600/PU film and GRT/GE-500F/SBR(vulcanization)/PU film among the developed self-sealing waterproof materials were similar to the commercial products. And properties of the soft-shaped self-sealing waterproof materials consisted of by GRT/GE-500F/Po1y(2-EHA) and CRT/Poly(AM-SAS-AA)/poly(2-EHA) were improved within from four times to twenty times compared to the one oi the commercial products.

• Journal of Life Science
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• v.19 no.12
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• pp.1821-1828
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• 2009

The purpose of this research was to investigate how the plyometric training and weight training program, applied in the field for exercise performance of throwing players, influenced improvement of athletic abilities, including agility, maximum muscular power, and strength. After implementing plyometric training and weight training to 21 high school throwing players for 10 weeks, we designed the next step. The 21 subjects were divided into two groups - women's group and men's group. All subjects were tested to determine agility using sidestep, burpee test, reaction time, lower body power and strength using standing long jump, standing jump, 30 m running, squats and leg presses. Additionally, isokinetic strength was measured using Cybex isokinetic dynamometer. The results showed that both groups demonstrated improvement in the standing long jump, standing jump and 30 m running after training. Particularly, the women's group indicated better improvement. Second, women's groups showed higher improvement in the sidestep and burpee test. However, in the reaction time test, the men's group indicated better improvement. Third, both groups showed better improvement in squats and leg presses after training. Particularly, the women's group indicated better improvement. Fourth, in the left and right side extension torque and flexion torque at a velocity of $60^{\circ}$/sec, both groups showed better improvement after training. In the left side extension peak torque, the men's group showed higher improvement, but the women's group showed higher improvement in the left side flexion and extension peak torque. Fifth, both groups showed better improvement in bench pressing and back strength after training. Particularly, the women's group indicated higher improvement.