• Journal of Korean Society of Coastal and Ocean Engineers
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• v.16 no.4
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• pp.206-212
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• 2004

The numerical analysis on the wave screening performance of the submerged breakwater with various crown widths is presented. The fluid motion is considered as linearized two dimensional potential flow and the finite element method is used to analyze the wave screening performance of the submerged breakwater. It is found that single-submerged breakwater with large crown width shows the most effective wave screening performance and single-submerged breakwater with small crown width also shows fairly good wave screening performance but its effectiveness is less than that of single-submerged breakwater with large crown width. However, double- or triple-submerged breakwater with small crown width shows more effective wave screening performance than that of single- or double-submerged breakwater with large crown width. It is expected that the submerged breakwater with small crown width is economical because it reduces the size of structure.

• The Korean Journal of Ecology
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• v.8 no.4
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• pp.197-200
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• 1985

The relations of crown width and DBH for Pinus densiflora, Pinus rigida, Pinus koraiensis, and Ginkgo biloba were accomplished to estimate the level of crown competition. Measurements of the relations revealed that crown width and DBH were highly correlated for the same species. Also it seems that these relations are independent of age and site quality. The results of regression analysis were as follow: P. densiflora, Y=0.3477X+0.3828 r=0.95 p. rigida, Y=0.3537X+0.1645 r=0.95 P. koraiensis, Y=0.2895X+0.6310 r=0.92 G. biloba, Y=0.4360X+0.0995 r=0.90 The significant differences between G. biloba and pine species seems due to their structural differences of crown formation according to tree species. As results of computing Maximum Crown Area and Crown Competition Factor as indices of crown competition, they indicated that P. densiflora would grow better under the natural conditions.

• Journal of Korean Society of Forest Science
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• v.96 no.2
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• pp.189-196
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• 2007

Allometry, basal area equations, and volume equations were developed with various tree measurement variables for the major species, Quercus mongolica and Quercus variabilis, in Korean natural hardwood forests. For allometry models, the relationships between total height-DBH, crown width-DBH, height to the widest portion of the crown-total height, and height to base of crown-total height were investigated. Multiple regression methods were used to relate annual basal area growth to tree variables of initial size (DBH, total height, crown width) and relative size (relative diameter, relative height) as well as competition measures (competition index, crown class, exposed crown area, percent exposed crown area, live crown ratio). For tree volume equations, the combined-variable and Schumacher models were fitted with DBH, total height and crown width for both species.

• Journal of Korean Society of Forest Science
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• v.99 no.2
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• pp.204-212
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• 2010

This study was performed in 22 unthinned Larix olgensis plantations in northeast China. Data were collected on 95 sample trees of different canopy positions and the diameter at breast height ($d_{1.3}$) ranged from 5.7 cm to 40.2 cm. The individual tree models for the prediction of vertical distribution of live crown, branch and needle biomass were built. Our study showed that the crown, branch and needle biomass distributions were most in the location of 60% crown length. These results were also parallel to previous crown studies. The cumulative relative biomass of live crown, branch and needle were fitted by the sigmoid shape curve and the fitting results were quite well. Meanwhile, we developed the crown ratio and width models. Tree height was the most important predictor for crown ratio model. A negative competition factor, ccf and bas which reflected the effect of suppression on a tree, reduced the crown ratio estimates. The height-diameter ratio was a significant predictor. The higher the height-diameter ratio, the higher crown ratio is. Diameter at breast height is the strongest predictor in crown width model. The models can be used for the planning of harvesting operations, for the selection of feasible harvesting methods, and for the estimation of nutrient removals of different harvesting practices.

• 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.

• The korean journal of orthodontics
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• v.15 no.1
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• pp.115-121
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• 1985

This study was intended to investigate the effect of mesiodistal crown widths of the anterior teeth on the incisor relationship and to determine whether incisor width ratio and anterior width ratio could be used to assess interarch tooth width harmony. From the casts taken from 63 subjects, 26 of open bite, 18 of deep bite and 19 of normal over bite with age of 17-20, mesiodistal crown widths of maxillary and mandibular 6 anterior teeth were measured with Boley gauge. On the basis of tooth measurements, anterior and incisor width ratio were calculated. The cephalograms were taken from same subjects to measure the degree of over bite and over jet and to compare the craniofacial bony structures between open bite, deep bite and normal over bite. Correlations among the anterior width ratio, incisor width ratio, over bite and over jet were calculated. The results were as follows. 1. There were no differences in mesiodistal widths of anterior teeth, incisor width ratio and anterior width ratio between open bite, deep bite and normal over bite. 2. The incisor width ratio and anterior width ratio can be useful in the assessment of tooth width harmony because the incisor width ratio and anterior width ratio were stable statistically and significantly correlated with each other. 3. Over bite and over jet were not correlated with incisor width ratio and anterior width ratio.

• Journal of Forest and Environmental Science
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• v.27 no.1
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• pp.47-54
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• 2011

Allometry and basal area equations were developed with various tree measurement variables for the major species; Quercus variabilis, Quercus mongolica, Pinus koraiensis and Larix leptolepis in Korea. For allometry models, the relationships between total height-DBH, crown width-DBH, height to the widest portion of the crown-total height, and height to base of crown-total height were investigated. Multiple regression methods were used to relate annual basal area growth to tree variables of initial size (DBH, total height, and crown width), relative size (relative diameter and relative height) as well as competition measures (competition index, crown class, and live crown ratio).

• Journal of Korean Port Research
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• v.9 no.2
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• pp.51-64
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• 1995

Generally, it is pointed out that the submerged breakwater with one row can not regulate the long period waves efficiently, because the crown width is very shorter than the wave length of the long period waves. Therefore, the wide crown is needed to raise the controlling efficiency for the long period waves. This study picks up the submerged breakwater with two rows which has smaller construction materials comparing to the one row and discusses the wave controlling function for the long period waves. Judging from the results obtained by using the strict dividing region method, the submerged breakwater with two rows can more regulate the long period waves than one row can, especially, in case that crown width and inner width of its construction come to be wider.

• The korean journal of orthodontics
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• v.50 no.5
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• pp.314-323
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• 2020

Objective: To identify the available evidence on the effects of rapid maxillary expansion (RME) with three-dimensional imaging and provide meta-analytic data from studies assessing the outcomes using computed tomography. Methods: Eleven electronic databases were searched, and prospective case series were selected. Two authors screened all titles and abstracts and assessed full texts of the remaining articles. Seventeen case series were included in the quantitative synthesis. Seven outcomes were investigated: nasal cavity width, maxillary basal bone width, alveolar buccal crest width, alveolar palatal crest width, inter-molar crown width, inter-molar root apex width, and buccopalatal molar inclination. The outcomes were investigated at two-time points: post-expansion (2-6 weeks) and post-retention (4-8 months). Mean differences and 95% confidence intervals were used to summarize and combine the data. Results: All the investigated outcomes showed significant differences post-expansion (maxillary basal bone width, +2.46 mm; nasal cavity width, +1.95 mm; alveolar buccal crest width, +3.90 mm; alveolar palatal crest width, +3.09 mm; intermolar crown width, +5.69 mm; inter-molar root apex width, +2.85 mm; and dental tipping, +3.75°) and post-retention (maxillary basal bone width, +2.21 mm; nasal cavity width, +1.55 mm; alveolar buccal crest width, +3.57 mm; alveolar palatal crest width, +3.32 mm; inter-molar crown width, +5.43 mm; inter-molar root apex width, +4.75 mm; and dental tipping, 2.22°) compared to pre-expansion. Conclusions: After RME, skeletal expansion of the nasomaxillary complex was greater in most caudal structures. Maxillary basal bone showed 10% post-retention relapse. During retention period, uprighting of maxillary molars occurred.

• The Journal of the Korean dental association
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• v.21 no.5 s.168
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• pp.415-423
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• 1983

A total of 202 full coverage crowns from 31 patients was investigated to find out the relationships between crown contour and gingival response. Every experimental crown has its contralateral natural tooth for its control group. Gingival Index and buccolingual width of the crowns were measured on both experimental and control group. Following conclusions were obtained from the study. 1. Most of the crown restorations were overcontoured and the increments were servere at cervical and height of contour area. 2. Height of contour and contact point of the restored crown were located near cervical area. Besides, most crowns had narrow embrasure with wide contact area. 3. Gingival Index around crown restorations was significantly larger than that of control group. 4. the interrelationship between Gingival Index and restored material or restored period was not verified at 5% significant level. 5. When grouping the artificial crowns into overcontoured, normal contoured, and undercontoured group by their width increment, the gingival inflammation was the severest in the overcontoured group and the mildest in the undercontoured group.