• Journal of Korean Society of Forest Science
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• v.100 no.3
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• pp.402-407
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• 2011

The objectives of this study were to analyze the crown vertical structure, crown bulk density, and to develop regression models for predicting crown fuel load using the data from 10 destructively sampled Pinus densiflora trees in Bonghwa, Gyeongbuk. The fuel loads were observed higher in the middle portion of the vertical distribution of crown followed by the lower portion and upper portion of Pinus densiflora, respectively. Approximately 25% crown fuel load was found in the needle while 33% was observed in the branches with <1 cm diameter with a total of 58% available fuel loads. The average crown bulk density was $0.45kg/m^3$, and $0.27kg/m^3$ of this was available in the needles and branches with <1 cm diameters. The resulting models in linear equations were able to account for 84% and 88% of the observed variation, while the allometric equations with diameter at breast height as the single predictor showed better results to account for 90% and 95% of the observed variation in the available crown fuel loads and total crown fuel loads, respectively. The suggested equations in this study could provide quantitative fuel load attributes for crown fire behavior models and fire management of red pine stands in Bonghwa areas.

• The Journal of the Korean dental association
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• v.54 no.7
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• pp.492-500
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• 2016

Crown fractures are a common type of dental injuries and very frequently occurred on maxillary anterior teeth, area of requiring a rapid aesthetic recovery. Crown fragment reattachment is a simple and conservative method to restore the fractured teeth. The technique promotes esthetic outcomes as utilizing natural contour, shade, surface texture of teeth and gives mechanical similarity in terms of wear-resistance. Also it gives emotional positive responses to patients and requires less of chair time and costs. This case report presents two cases of crown fragment reattachments on maxillrary anterior teeth, including one complicated crown fracture and one uncomplicated crown fracture. If the fragment is available in cases of crown fractures, reattachment of fragment can be regarded as a predictable alternative. However, it is all the time important that a close conversation informing the patients about the limitations and prognoses of this treatment option.

• Journal of Integrative Natural Science
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• v.9 no.1
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• pp.28-34
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• 2016

A number of chiral selectors have been developed and applied for enantiomer separation of a variety of chiral compounds. Among these chiral selectors are chiral crown ethers, a class of synthetic host polyether molecules that bind protonated chiral primary amines with high selectivity and affinity. In this paper, two important chiral crown ethers as chiral selectors of bis-(1,1'-binaphthyl)-22-crown-6 and (18-crown-6)-2,3,11,12-tetracarboxylic acid (18-C-6-TA) are focused. They have been widely used to resolve the enantiomers of chiral compounds containing a primary amino moiety using chiral stationary phases (CSPs) or chiral selectors by high-performance liquid chromatography (HPLC), capillary electrophoresis (CE) and so on in chirotechnology. Also, it was described that the commercially available covalent type HPLC CSPs derived from (+)- and (-)-18-C-6-TA have been developed and successfully applied for the resolution of various primary amino compounds including amino acids.

• Journal of Korean Society of Forest Science
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• v.99 no.3
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• pp.391-396
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• 2010

To analyze the characteristics of canopy fuel in Pinus densiflora stand, which is essential to assess the crown fire hazard, allometric equations for estimation of crown fuel biomass were developed by subjectively categorized crown fuel component and crown bulk density was analyzed by available fuel component categories. Ten trees were destructively sampled at Pinus densiflora stand in Mt. Palgong in Daegu and their crown fuels were weighed separately for each fuel category by size classes and by living and dead. Regression equations that estimate crown fuel load by diameter at breast height(D) or additional total height(H) were derived. The adjusted coefficient of determination values were the highest (${R^2}_{adj}$=0.835-0.996) and standard error of estimate were the lowest (SEE=0.074-0.638) in the allometric equation lnWt=${\alpha}+{\beta}lnD+{\gamma}lnH$ in average. However, in needles and small branches categories, the differences in ${R^2}_{adj}$ and SEE between equations were not significant. Crown bulk density (CBD), which was calculated by crown fuel load divided by crown volume, was 0.067 kg/$m^3$ in average when only needles were considered as available crown fuel and 0.097 kg/$m^3$ when needles and branches (0-0.5 cm diameter) were considered. The increments of CBD of needles and small branches were little even when diameter at breast height increased.

• Proceedings of the PSK Conference
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• 2003.04a
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• pp.285.1-285.1
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• 2003

ChiroSil RCA(+) and SCA(-) HPLC chiral stationary phases (CSPs) developed by covalently bonding (+)- and (-)-(18-crown-6)-2,3,11,12-tetracarboxylic acid (18-C-6-T A) to silica gel were employed for enantioresolution of racemic amino compounds, respectively. Also, these 18-C-6-TA covalently bonded CSPs were compared to a commercially available Crownpak CR CSP prepared by coating chiral crown ether as a chiral selector on ODS column. (omitted)

• KSBB Journal
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• v.27 no.4
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• pp.199-206
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• 2012

Chiral crown ethers are synthetic macrocyclic polyethers that bind protonated chiral primary amines with high selectivity and affinity. They have been widely used to separate or distinguish the enantiomers of chiral compounds containing a primary amino moiety by high-performance liquid chromatography, capillary electrophoresis, and NMR spectroscopy. In this paper, two important chiral crown ethers including chiral binaphthyl unit and (18-crown-6)-2,3,11,12-tetracarboxylic acid as chiral selectors are focused. And several chiral resolution techniques and their applications in chirotechnology using these chiral crown ethers with related chiral recognition mechanism studies are reviewed. Especially, it was shown that the commercially available HPLC columns based on (18-crown-6)-2,3,11,12-tetracarboxylic acid have been developed and successfully applied for the resolution of various primary amino compounds including amino acids.

• Journal of Korean Society of Forest Science
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• v.100 no.2
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• pp.266-272
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• 2011

This study was conducted to analyze the characteristics of crown fuel biomass and to develop allometric equations for the estimation of crown fuel biomass by subjectively categorized the crown component in Pinus densiflora stands. A total of ten representative trees were destructively sampled in Youngju region. Crown fuel were weighed separately for each fuel category by size class. The results of this study showed that foliar moisture content was 119% while the average crown moisture content was 105.3%. The crown fuel/total fuel loading ratio was 30%, needles and twigs with less than 1 cm diameter accounted 50.3% for its fuel/crown fuel loading ratio. Adjusted multiple coefficient of determination of suggested allometric equations ranged from 0.6846 to 0.9246 for crown fuel biomass, 0.8308 for crown volume.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.33 no.6
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• pp.321-332
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• 2021

The crown wall with parapet on top of the rubble mound breakwater represents a relatively economic and efficient solution to reduce the wave overtopping discharge. However, the inclusion of parapet leads to increased wave pressure on the crown wall. The wave pressure on the crown wall is investigated by physical model test. To design the crown wall the wave loads should be available, and the horizontal wave pressure is still unclear. Regarding to the horizontal wave pressure on the crown wall, a series of experiments were conducted by changing the rubble mound type structure and the wave conditions. Based on these results, pressure modification factors of Goda's (1974, 2010) formula have been suggested, which can be applicable for the practical design of the crown wall of the rubble-mound breakwater covered by tetrapods.

• The Journal of Korean Academy of Prosthodontics
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• v.44 no.1
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• pp.85-102
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• 2006

Statement of problem: Currently, there are some 20 different geometric variations in implant/abutment interface available. The geometry is important because it is one of the primary determinants of joint strength, joint stability, locational and rotational stability. Purpose: As the effects of the various implant-abutment connections and the prosthesis height variation on stress distribution are not yet examined this study is to focus on the different types of implant-abutment connection and the prosthesis height using three dimensional finite element analysis. Material and method. The models were constructed with ITI, 3i TG, Bicon, Frialit-2 fixtures and solid abutment, TG post, Bicon post, EstheticBase abutment respectively. And the super structures were constructed as mandibular second premolar shapes with 8.5 mm, 11 mm, 13.5 mm of crown height. In each model, 244 N of vertical load and 244 N of $30^{\circ}$ oblique load were placed on the central pit of an occlusal surface. von Mises stresses were recorded and compared in the crowns, abutments, fixtures. Results: 1. Under the oblique loading, von Mises stresses were larger in the crown, abutment, fixture compared to the vertical loading condition. 2. The stresses were increased proportionally to the crown height under oblique loading but showed little differences with three different crown heights under vertical loading. 3. In the crown, the highest stress areas were loading points under vertical loading, and the finish lines under oblique loading. 4. Under the oblique loading, the higher stresses were located in the fixture/abutment interface of the Bicon and Frialit-2 systems compared to the ITI and TG systems. Conclusions: The stress distribution patterns of each implant-abutment system had difference among them and adequate crown height/implant ratio was important to reduce the stresses around the implants.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.42 no.4
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• pp.469-480
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• 2022

To design the crown wall of rubble-mound breakwaters, the horizontal wave load should be available, but determining this load remains difficult. Lee et al. proposed modification factors for Goda's formula for the horizontal wave pressures on acrown wall. The empirical formula by Lee et al. was based on a two-dimensional model test with a relatively narrow armour crest width in front of the crown wall. In this study, a series of experiments at the same facility were conducted on the horizontal wave pressures on the crown wall of a rubble-mound breakwater with a wide armour crest width. As a result, the pressures of the unprotected part of the crown wall were nearly identical to the narrow crest width. However, the pressures of the protected part tended to decrease with a change in the armour crest width. From the experimental results, the horizontal pressure modification factors of Goda's formula including the armour crest width effect are suggested here and are likely applicable to practical designs of the crown walls of rubble-mound breakwaters covered with tetrapods.