• Journal of the korean academy of Pediatric Dentistry
• /
• v.48 no.4
• /
• pp.437-448
• /
• 2021

The purpose of this study is to analyze morphological characteristics of maxillary primary molar's root and root canal. 268 children aged 3 - 7 years (175 boys, 93 girls) who had CBCT (152 children) and 3D CT (116 children) taken in Seoul National University Dental Hospital from January 2006 to April 2020 were included. The number of roots and root canals were analyzed in 1002 teeth without any root resorption or periapical pathologies. Curvature, angulation, length of root and root canal, as well as cross-sectional shapes of the root canal were analyzed in 218 teeth. By using Mimics and 3-Matics software, volume, surface area, and volume ratio of root canal was analyzed in 48 teeth. More than half of maxillary primary molars have 3 roots and 3 root canals. The degree of symmetry of root canal type was about 0.63 (Cohen's kappa coefficient). The most frequent shape of roots and canals was linear in 1^st primary molars and curved in 2^nd primary molars. Angulation, length of root and root canals was the largest on palatal roots. Most teeth showed ovoid or round shapes at apex. The largest root canal volume, surface area, volume ratio was found in the palatal roots.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.27 no.3
• /
• pp.268-275
• /
• 1982

This study was conducted to obtain basic informations for breeding and improving cultural practices of sesame (Sesamum indicum L.) through investigation of several agronomic characters of 82 major varieties plants in April 20, May 15 and June 20. Stem diameter and plant height were largest in early planting(April 20). On the contrary, they were smallest in late planting(June 15). Therefore, the later planting, the poorer the vegetative growth on the basis of stem diameter and plant height. Number of capsules per plant and number of grains per capsule were 88 and 54, respectively, in the early planting, while they were decreased to 25 capsules and 40 grains in late planting. The percentage of ripeness and 1000 grain weight 78 and 2.3g in the April 20planting while they were 58% and 2.1g in June 20 planting indicating the later planting, the lower the ripeness. Grain yield per m1 in April 20 and June 20 planting was 112 and 18g respectively. Consequently, grain yield significantly decreased as planting delayed. On the basis of the vegetative and reproductive growth, varieties could be classified into early, conventional, late and indetermediate planting adapted groups. The major yield components were highly and postively correlated with accmulated sunshine hours and temperatures confirming that grain yield was closely related with sunshine and temperature. Among the varieties tested, Gurye and Local 135 had more than 150 capsules. Haenam and Woogang had more than 75 grains per capsule. Since grain yield oflate planted sesame were significantly different among the varieties, breeding of sesame for after barly cropping would be more effective under late cultural condition of after barly.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.29 no.1
• /
• pp.76-83
• /
• 1984

This experiment was performed to investigate the flowering habit of sesame (Sesamum indicum L.). Sesame varieties tested could be classified into 8 different plant types by their morphological traits such as capsule shape, capsule setting habit and branching types among sesame gene pool of Crop Experiment Station, ORD. The first flower was appeared at the lowest node on main stem. Flowers were appeared progressively toward the tip of the main stem and also toward the tips of branches. The interval of flowering for a node was about one day, but 3 to 8 days for the flowers on the tips. Side flowers started at 4 to 5 nodes lower than those of center flower at the same day. Flowers were beared 2 by 1 node on the middle part of flower setting node (7-9) in mono capsule setting habit in spite of its normal is 1 by 1 node on the other nodes. Flowers were beared opposite direction on each node of stem and flowering toward the tip of main stem composed of cross shape between nodes and spiral, reverse of clockwise direction. We called this habit as cross spiral flowering order and cross spiral phyllotaxis. The first flower on branches was appeared when center flower on the 5th node of main stem began to flower. The branches produced at higher nodes on main stem showed larger flowering periods and more number of flowers than that at lower parts. BTB (Branch, Tricapsule, Bicarpels, 4 Loculi) type showed three capsule setting habits and same flowering period both on main stem and branches while BTQ (Branch, Tricapsule, Quadricarpels, 8 Loculi) type showed three capsule setting habit on main stem and mono-capsule setting habit on branches. In BTQ type, the period of flowering was much shorter on branches than on main stem. Branching type was considered more promising than non branching type for the breeding of early maturing high yielding variety because branching type has the advantage of bearing a lot of flowers in comparatively short flowering period.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.42 no.5
• /
• pp.489-496
• /
• 1997

This study was carried out to develop and investigate integrated mechanization system on polyethylene(P.E.) film mulching culture in sesame. Field trials were carried out to develop optimum mechanics for each step of manual operation in sesame culture and demonstrated those developed mechanics of sesame dibbling vinyl mulcher, sesame binder, sesame thresher and sesame grader at the farmer, s field of Hwasong (Kyunggi-do) in 1994 and 1995. Newly developed sesame dibbling vinyl mulcher brought saving manpower 280 hrs /ha for sowing and P.E. film mulching with it's 98％ of labour saving for the harvesting operation of sesame. Sesame Binder showed 93％ labour saving for cutting and binding with only 22 hrs /ha compared to 330 hrs /ha that of conventional. Sesame thresher was appeared to have 85％ effects of labour saving for threshing with completely dry sesame bundles at one time by 23 hrs /ha compared to 151 hrs /ha that of conventional. Sesame grader was appeared to have 72％ effects for sesame grain grading with 12 hrs /ha compared to that of conventional 54 hrs /ha. Grain yield of integrated mechanization culture system showed 6％ higher than that of coventional. Integrated mechanization culture system (sesame dibbling vinyl mulcher ＋ sesame binder ＋ sesame thresher ＋ sasame grader) showed 62％ of labour saving effects through whole steps of sesame culture by 472 hrs /ha compared to that of conventional 1, 230 hrs /ha.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.50 no.1
• /
• pp.75-88
• /
• 2023

The aim of this retrospective study was to evaluate the demographic characteristics of pediatric dental patients who underwent dental treatment under general anesthesia (DTGA) at the Seoul National University Dental Hospital from January 2011 through December 2020 and compare the patterns of repeated DTGA between dental patients with severe disabilities (DSD) and non-DSD (healthy or medically compromised patients without DSD). There were 1,857 DTGAs among 1,719 patients (mean age = 5.1 years; males = 59.3%; ASA 2 or above = 52.9%; DSD = 26.8%). Overall, 6.6% of patients underwent repeated DTGA, and the rate of repeated DTGA over a 10-year period was 7.4%. ASA 2 or above (p < 0.0001) and DSD (p < 0.0001) were more likely to undergo repeated DRGA compared to ASA 1 and non-DSD. At both GA1 and GA2, DSD received significantly more restorative treatment on permanent teeth than non-DSD (p = 0.002, p < 0.0001, respectively). There has been an increasing demand for DTGA in pediatric dentistry over the last 10 years. Regular check-ups and preventive oral health care are necessary for pediatric dental patients with severe disabilities to reduce the possibility of repeated DTGA.

• Economic and Environmental Geology
• /
• v.56 no.1
• /
• pp.1-11
• /
• 2023

In this study, we explore the morphological and geochemical characteristics for 440 manganese nodules collected from two different water depths [ARA12B-St52 (150 m, n = 239) and ARA12B-St58i (73 m, n = 201)] on the continental shelf of the East Siberian Sea from the ARA12B expedition in 2021. We also discussed the variations in the characteristics of manganese nodules with varying water depths in the Arctic Sea. The sizes of the nodules are generally greater than 3 cm at both sites. However, there is an obvious difference in the morphology with water depths. For the nodules collected at 150 m, brown-black colored tabular, tube, and ellipsoidal shapes with a rough surface texture are dominant. On the other hand, yellow-brown tabular shapes with a smooth surface texture are common for the nodules collected at 73 m. Furthermore, the slope of trend line between size and weight is significantly different at both sites: particularly, the slopes of nodules at 150 and 73 m are 1.60 and 0.84, respectively. This indicates the difference in the internal structure, porosity, and constituting elements between both nodules. Micro X-ray Flourescence (µ-XRF) results clearly demonstrate that the internal textures and chemical compositions are different with water depths. The nodules at 150 m are composed of a thick Mn-layer and a thin Fe-layer centered on the nucleus, while the nodules at 73 m are alternately grown with thin Mn- and Fe- layers around the nucleus. The average chemical compositions obtained by µ-XRF are 40.6 wt% Mn, 5.2 wt% Fe, and 7.9 Mn/Fe ratio at 150 m, and 10.3 wt% Mn, 19.0 wt% Fe, and 0.6 Mn/Fe ratio at 73 m. The chemical compositions of the nodules at 150 m are similar to those of nodules from the Peru Basin in the Pacific Ocean, while the compositions of the nodules at 73 m are similar to those of nodules from the Cook Islands or the Baltic Sea. The observed morphological and geochemical characteristics of the nodules show a clear difference at the two sites, which indicates that the aqueous conditions and formation processes of the nodules in the Arctic Sea vary with the water depths.

• Journal of the Korean Geotechnical Society
• /
• v.26 no.7
• /
• pp.49-58
• /
• 2010

This paper presents experimental results of a series of 1-g shaking table model tests performed on end-bearing single piles and pile groups to investigate the effect of particle size on the dynamic behavior of soil-pile systems. Two soil-pile models were tested twice: first using Jumoonjin sand, and second using Australian Fine sand. In the case of single-pile models, the lateral displacement was almost within 1% of pile diameter which corresponds to the elastic range of the pile. The back-calculated p-y curves show that the subgrade reaction of the Jumoonjin-sand-model ground was larger than that of the Australian Fine-sand-model ground at the same displacement. This phenomenon means that the stress-strain behavior of Jumoonjin sand was initially stiffer than that of Australian Fine sand. This difference was also confirmed by resonant column tests and compression triaxial tests. And the single pile p-y backbone curves of the Australian fine sand were constructed and compared with those of the Jumoonjin sand. As a result, the stiffness of the p-y backbone curves of Jumunjin sand was larger than those of Australian fine sand. Therefore, using the same p-y curves regardless of particle size can lead to inaccurate results when evaluating dynamic behavior of soil-pile system. In the case of the group-pile models, the lateral displacement was much larger than the elastic range of pile movement at the same test conditions in the single-pile models. The back-calculated p-y curves in the case of group pile models were very similar in both sands because the stiffness difference between the Jumoonjin-sand-model ground and the Australian Fine-sand-model ground was not significantly large at a large strain level, where both sands showed non-linear behavior. According to a series of single pile and group pile test results, the evaluation group pile effect using the p-multiplier can lead to inaccurate results on dynamic behavior of soil-pile system.

• Journal of Korean Society of Forest Science
• /
• v.111 no.1
• /
• pp.136-149
• /
• 2022

In this study, the performance of a nonlinear mixed-effects (NLME) model used to estimate the stem taper of Pinus densiflora in Gangwon Province was compared with that of a nonlinear fixed-effects (NLFE) model using several performance measures. For the diameters of whole tree stems, the NLME model improved on the performance of the NLFE model by 26.4%, 42.9%, 43.1%, and 0.9% in terms of BIAS, MAB, RMSE, and FI, respectively. For the cross-section areas of whole tree stems, the NLME model improved on the performance of the NLFE model by 67.7%, 44.7%, 45.8%, and 1.0% in terms of BIAS, MAB, RMSE, and FI, respectively. Based on the analysis of 12 relative height classes of tree stems, stem taper estimation performance was also reasonably improved by the NLME model, which showed better MAB, RMSE, and FI at every relative height class compared with those of the NLFE model. In some classes, the NLFE model had better BIAS than the NLME model (stem diameter: 0.05, 0.2, 0.3, and 0.8; stem cross-section area: 0.05, 0.3, 0.5, 0.6, and 1.0). However, the NLME model enhanced the performance of stem diameter and cross-section area estimations at the lowest stem part (0.2 m from the ground). Improvements for stem diameter in terms of BIAS, MAB, RMSE, and FI were 84.2%, 69.8%, 68.7%, and 3.1%, respectively. For stem cross-section areas, the improvements in BIAS, MAB, RMSE, and FI were 98.5%, 70.1%, 68.7%, and 3.1%, respectively. The cross-section area at 0.2 m from the ground occupied 22.7% of total cross-section area. Improvements in estimation of cross-section area at the lowest stem part indicate that stem volume estimation performance could also be enhanced. Although NLME models are more difficult to fit than NLFE models, the use of NLME models as a standard method for the estimating the parameters of stem taper equations should be considered.

• Journal of the Korean Orthopaedic Association
• /
• v.54 no.6
• /
• pp.519-527
• /
• 2019

Purpose: To evaluate the treatment result in polyostotic fibrous dysplasia classified according to the involvement of the femoral head. Materials and Methods: Twenty-three patients from March 1987 to March 2014 were reviewed retrospectively. Patients with no involvement of the physeal scar in the femoral head were classified as Type I, and those with involvement of the physeal scar were classified as Type II. A plain radiograph was used to measure the femoral neck shaft angle, articulo-trochanteric distance (ATD), and anterior bowing through the lateral view. A teleoroentgenogram of the lower limb was used to measure the leg length discrepancy and lower extremity mechanical axis. The pre- and postoperative femoral neck-shaft angle and ATD were compared to assess the degree of correction of the deformity. Results: Among a total of 46 cases (23 patients), 28 cases (23 patients) had lesions in the proximal femur. Type I were 16/28 cases (15/23 patients) and Type II were 12/28 cases (9/23 patients). The preoperative proximal femoral neck-shaft angle was 116.8° in Type I and 95.3° in Type II. The ATD was 12.08 mm in Type I and -5.54 mm in Type II. The deformity correction showed significant improvement immediately after surgery, the deformity correction was lost in Type II (neck shaft angle Type I: 133.8°-130.8°, Type II: 128.6°-116.9°, and ATD Type I: 17.66-15.72 mm, Type II: 7.44-4.16 mm). The extent of anterior bowing was 12.74° in Type I and 20.19° in Type II. The mean differences of 12 mm between the 9 patients who showed a leg length discrepancy and the lower extremity mechanical axis showed 4 cases of lateral deviation and 7 cases of medial deviation. Conclusion: In polyostotic fibrous dysplasia, when the femur head is involved, the femur neck shaft angle, ATD, and anterior bowing of the femur had more deformity, and the postoperative correction of deformity was lost, suggesting that the involvement of the femoral head was an important factor in the prognosis of the disease.

• Journal of Korean Society of Forest Science
• /
• v.112 no.4
• /
• pp.472-489
• /
• 2023

This study was conducted to derive the optimal estimation equations for deriving the green and dry weights of Larix kaempferi (Japanese larch) and Pinus rigida (Rigida pine), which are major coniferous tree species in South Korea. The equations were then used to develop weight tables. Table development began with the sampling of 150 L. kaempferi and 90 P. rigida trees distributed throughout the national scale, after which green weights were measured on-site. Samples from each stand were then collected, and their dry weights were measured in a laboratory. The equation used to calculate green and dry weights was divided into a one-variable formula that uses only the diameter at breast height (DBH) and a two-variable equation that employs DBH and height. The equations used to estimate the green and dry weights of logs were divided into one- and two-variable equations using DBH. Statistical data, such as the fitness index (FI), root mean square error, standard error of estimation, and residual diagram, were used to verify the suitability of the estimation equations. Applicability was examined by calculating weights using the derived optimal equations. The equation W = bD+cD² was used in measurements involving only DBH, whereas the equation W = aD^bH^c was employed in cases involving both diameter and height at breast height. The FI of W = bD+cD² was 0.91, while that of W = aD^bH^c was 0.95, both of which are high values. With these estimation formulas, weight tables for the green and dry weights of L. kaempferi and P. rigida were prepared and compared with weight tables created 20 years ago. The green and dry weight tables of both species were larger.