• Korean Journal of Soil Science and Fertilizer
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• v.23 no.1
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• pp.8-14
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• 1990

Retardation and hydrodynamic dispersion coefficient necessary for model of water and solute movement in a soil were determined for horizontal soil column with different initial soil water conditions. The soil columns were compacted with sandy loam soil. The bulk density was $1,350+50kg/m^3$, and initial water contents were 0.05, 0.08 and 0.14. Advancement of 0.05% $CaSO_4$ solution was used as the standard and advancements of 0.5% KCl, $CaCl_2$ and $KH_2PO_4$ were compared. Retardation of non-reactive $Cl^-$ was related with the initial soil water content, ${\theta}n$, as ${\theta}/({\theta}-{\theta}n)$, and anion exclusion was ignored. Retardations of active $K^+$, $Ca^{{+}{+}}$ and $H_2PO_4{^-}$ were related as 1/(R+1) $^*{\theta}/({\theta}-{\theta}n)$, in which R was retardation coefficient. Measured R was 0.64 for $K^+$, 0.80 for $Ca^{{+}{+}}$ and 2.6 for $H_2PO_4{^-}$, respectively. Calculated R using Langmuir adsorption isotherm showed fair degree of applicability. Soil water diffusivity, $D({\theta}),m^2/sec$, calculated for different initial water content showed unique function as $$log(D({\theta}))=13.448{\theta}-9.288$$ Hydrodynamic dispersion coefficient of $Cl^-$ above soil water content 0.36 was similar to soil water diffusivity and decreased to near self diffusion coefficient at soil water content near 0.2. Those of $K^+$, $Ca^{{+}{+}}$ $H_2PO_4{^-}$ at soil water content of 0.38 were $5.5{\times}10^{-6}$, $2.4{\times}10^{-6}$ and $7.1{\times}10^{-7}m^2/sec$ and decreased rapidly with decreasing soil water content lower than 0.36.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.38
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• pp.38.1-38.10
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• 2016

Background: The aims of this study are to evaluate the lip morphology and change of lip commissure after mandibular setback surgery (MSS) for class III patients and analyze association between the amount of mandibular setback and change of lip morphology. Methods: The samples consisted of 14 class III patients treated with MSS using bilateral sagittal split ramus osteotomy. Lateral cephalogram and cone-beam CT were taken before and about 6 months after MSS. Changes in landmarks and variables were measured with 3D software program $Ondemand^{TM}$. Paired and independent t tests were performed for statistical analysis. Results: Landmarks in the mouth corner (cheilion, Ch) moved backward and downward (p < .005, p < .01). However, cheilion width was not statistically significantly changed. Landmark in labrale superius (Ls) was not altered significantly. Upper lip prominence angle (ChRt-Ls-$ChLt^{\circ}$) became acute. Landmarks in stomion (Stm), labrale inferius (Li) moved backward (p < .005, p < .001). Lower lip prominence angle (ChRt-Li-$ChLt^{\circ}$) became obtuse (p < .001). Height of the upper and lower lips was not altered significantly. Length of the upper lip vermilion was increased (p =< 0.01), and length of the lower lip vermilion was decreased (p < .05). Lip area on frontal view was not statistically significantly changed, but the upper lip area on lateral view was increased and change of the lower lip area decreased (p > .05, p < .005). On lateral view, upper lip prominent point (UP) moved downward and stomion moved backward and upward and the angle of Ls-UP-Stm ($^{\circ}$) was decreased. Lower lip prominent point (LP) moved backward and downward, and the angle of Stm-LP-Li ($^{\circ}$) was increased. Li moved backward. Finally, landmarks in the lower incisor tip (L1) moved backward and upward, but stomion moved downward. After surgery, lower incisor tip (L1) was positioned more superiorly than stomion (p < .05). There were significant associations between horizontal soft tissue and corresponding hard tissue. The posterior movement of L1 was related to statistically significantly about backward and downward movement of cheilion. Conclusions: The lip morphology of patients with dento-skeletal class III malocclusion shows a significant improvement after orthognathic surgery. Three-dimensional lip morphology changes in class III patients after MSS exhibited that cheilion moved backward and downward, upper lip projection angle became acute, lower lip projection angle became obtuse, change of upper lip area on lateral view was increased, change of lower lip area decreased, and morphology of lower lip was protruding. L1 was concerned with the lip tissue change in statistically significant way.

• The korean journal of orthodontics
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• v.36 no.6
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• pp.412-421
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• 2006

Objective: The result of finite element analysis depends on material properties, structural expression, density of element, and boundar or loading conditions. To represent proper elastic behavior, a finite element model was made using Hounsfield unit (HU) values in CT images. Methods: A 13 year 6 month old male was used as the subject. A 3 dimensional visualizing program, Mimics, was used to build a 3D object from the DICOM file which was acquired from the CT images. Model 1 was established by giving 24 material properties according to HU. Model 2 was constructed by the conventional method which provides 2 material properties. Protraction force of 500g was applied at a 45 degree downward angle from Frankfort horizontal (FH) plane. Results: Model 1 showed a more flexible response on the first premolar region which had more forward and downward movement of the maxillary anterior segment. Maxilla was bent on the sagittal plane and frontal plane. Model 2 revealed less movement in all directions. It moved downward on the anterior part and upward on the posterior part, which is clockwise rotation of the maxilla. Conclusion: These results signify that different outcomes of finite element analysis can occur according to the given material properties and it is recommended to use HU values for more accurate results.

• The Journal of Korean Academy of Prosthodontics
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• v.46 no.4
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• pp.420-430
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• 2008

Statement of problem & Purpose: Articulators are very important for education and overall clinical situation in the field of prosthodontics, however preexisting articulators are designed and built based on maxillofacial structures and mean values of mandibular movement of Western people. Purpose of this research is to find out a adequate basis for applicating these articulators, presently used for clinical education, for Korean. Material and methods: 59 Korean adults (41 males, 18 females), aged between 24 to 41, where selected for this study. Two pairs of both maxillary and mandibular models were made for each examinee. These models where attached to both KaVo PROTARevo 7 and Hanau Modular semiadjustable articulators by using facebow transfer, than sagittal condylar inclination, occlusal plane inclination and position of mandibular on the articulator where measured. Result and conclusion: 1. Mean sagittal condylar inclination for KaVo PROTAR semiadjustable articulator was $33.75^{\circ}$(standard deviation $12.46^{\circ}$) meanwhile Hanau Modular semiadjustable articulator showed $40.72^{\circ}$(standard deviation $12.09^{\circ}$) for mean sagittal condylar inclination. 2. Mean occlusal plane inclination for KaVo PROTAR semiadjustable articulator was $-2.76{\circ}$(standard deviation $3.63^{\circ}$) meanwhile Hanau Modular semiadjustable articulator showed $11.87^{\circ}$ (standard deviation $3.63^{\circ}$) for mean occlusal plane inclination. 3. On the average center of the mandibular dentition were in the range of 5 to 7 mm of the central position of the articulator. Both anterior and posterior dentition were positioned at the center of the articulator vernacularly for KaVo PROTAR semiadjustable articulators, meantime for Hanau Modular semiadjustable articulator, anterior dentition was positioned 5 mm downwards and 3mm upwards for posterior dentition from vertically central position of the articulator.

• Korean Journal of Soil Science and Fertilizer
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• v.19 no.4
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• pp.339-344
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• 1986

Frost damage which can reduce yields, impair fruit quality and cause loss of trees is closely related to the occurrence of daily minimum temperature. Horizontal distribution of air temperature minima can be characterized by conditions of radiational cooling and gravitational movement of cold air, which are influenced by the regional topographic features. Observations were made on the air temperature minima over Yangpyeong area, to delineate potential effects of topography on the temperature pattern during spring season. Two routes were selected for the observation. Liquid glass minimum thermometers were installed at 17 sites through the old peach orchards which had been closed due to the frequent freeze-frost hazards during the recent years. This route was 8.5km long and the highest point was 350m above mean sea level. The other route, which was 2.5km in distance, was run with a digital resistance thermometer during the hour just before sunrise. Observations were made both on a calm-clear day (April 30, 1986) and a windy-overcast day (May 1, 1986). The temperature on April 30 was in increasing trend with elevation but this was modified at near the riverside and the downtown area. An orchard lying on a hilltop showed the temperature $1^{\circ}C$ higher than near by lowland of which elevation was about 30m lower. The minimum temperature on the overcast day was little affected by terrestrial conditions but by the atmospheric lapse condition. The peach orchards severely damaged by cold air were found in the area where the lowest minimum temperature was observed. The results may be useful for selection of the proper orchard location to be developed in an area.

• Proceedings of the Korean Geotechical Society Conference
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• 1991.10a
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• pp.87-102
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• 1991

It has been reported that the failure of Carsington Dam in Eng1and occured due to the existence of a thin yellow clay layer which was not identified during the design work, and due to pre-existing shears of the clay layer. The slope stability analyses during the design work, which utilized traditional circular arc type failure method and neglected the existence of the clay layer, showed a safety factor of 1.4. However, the post-failure analyses which utilized translational failure mode considering the clay layer and the pre-existing shear deformation revealed the reduction of safety factor to unity. The post-failure analysis assumed 10。 inclination of the horizontal forces onto each slice based on the results of finite element analyses. In this paper, Bishop's simplified method, Janbu method, and Morgenstern-Price method were used for the comparison of both circular and translational failure analysis methods. The effects of the pre-existing shears and subsquent movement were also considered by varying the soil strength parameters and the pore pressure ratio according to the given soi1 parameters. The results showed factor of safefy 1.387 by Bishop's simplified method(STABL) which assumed circular arc failure surface and disregarding yellow clay layer and pre-failure material properties. Also the results showed factor of safety 1.093 by Janbu method(STABL) and 0.969 by Morgenstern-Price method(MALE) which assumed wedge failure surface and considerd yellow clay layer using post failure material properties. In addition, dam behavior was simulated by Cam-Clay model FEM program. The effects of pore pressure changes with loading and consolidation, and strength reduction near or at failure were also considered based on properly assumed stress-strain relationship and pore pressure characteristics. The results showed that the failure was initiated at the yellow clay layer and propagated through other zones by showing that stress and displacement were concentrated at the yel1ow clay layer.

• The korean journal of orthodontics
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• v.34 no.1 s.102
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• pp.71-81
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• 2004

In this study, we attempt to investigate the mechanisms by which PDL cells regulate osteoclast formation and also tc know whether PDL retained their characteristic phenotype during tooth eruption and interdental separation. Rats were prepared at developmental days 21 (pre-root formation), 27(toot development), 34(advanced root formation/eruption) and at later times(adult rats). To induce severe resorption state of alveolar bone and tooth root, interdental separation with brass wire was performed between the lower first and second molars for 2 weeks in adult rats. Rat mandibles were demineralized and embedded in paraffin, and horizontal and frontal section were prepared for immuno-histochemical analysis using PDL-specific protein 22 (PDLs22), receptor activator of NFKB ligand (RANKL) and osteoprotegerin (OPG) antibodies. 1. Root formation and eruption stage of tooth development. 1) PDLs22 immunolocalization was observed in tooth follicle/PDL cells and osteoblasts throught out the root formation and eruption stages of tooth development. 2) RANKL expression became stronger at eruption stage than root formation stage of tooth development. 3) Strong expression of OPG was detected in follice/PDL cells of toot formation stage but it was decreased with tooth eruption. 2. Interdental separation between lower first and second molar 1) Comparared to normal animal, multinucleated osteoclasts and odontoclasts were markedly induced in the alveolar bone and tooth root with PDL remodeling in hematoxylin-eosin section. 2) PDLs22 expression was decreased with interdental separation. 3) RANKL expression was Increased with interdental separation in PDL fibroblasts, osteoblasts, odontoclasts and it lacunae, resorting dentin, cementum and bone matrix. 4) OPG expression was slightly decreased in the PDL cells adjacent to the alveolar bone and root surface with interdental separation. These results suggested that during tooth eruption and tooth movement, RANKL and OPG in the periodontal tissues are important determinants regulating balanced alveolar bone and tooth root resorption. And it is also suggested that PDL cells retained their characteristic phenotype during tooth eruption and interdental separation except for the short period of PDL remodeling.

• The korean journal of orthodontics
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• v.27 no.3 s.62
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• pp.373-389
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• 1997

The purpose of this stdudy was to evaluate the effect of maxillary protraction and the relapse of hard and soft tissue after maxillary protraction. For this study 29 patients who were treated with maxillary protractor and labiolingual archwire were selected. Their mean age was 9 years 4 months and mean treatment period was 8.5 months. Lateral cephalograms were taken at pretreatment, immediately after treatment and one to three months after removal of the maxillary protractor. They were traced on skeletodental and soft tissue structures based on Burstone's analysis and analyzed by Quick-Ceph Image Digitizing System(ORTHODONTIC PROCESSING). The mean and standard deviation between pretreatment and posttreatment and between posttreatment and retention period for each cephalometric variable were calculated. Student t-test was used to determine the statistical significance of the changes in each variable. Correlation coefficients between hard tissue and soft tissue were used to determine interrelationship. The results were as follows. 1. After maxillayy protraction, the maxilla and maxillary dentition moved antero-inferiorly, the mandibld and mandibular dentition moved postero-interiorly and palatal plane rotated antero-superiorly by $0.59^{\circ}$. 2. After maxillary protraction, the soft tissue of upper lip moved antero-interiorly with the movement of hard tissue but the antero-posterior position of lower lip was stable in spite of the change of hard tissue. The thickness of upper lip was decreased and that of lower lip was increased after maxillary Protraction. 3. During the retention period, the position of jaws was relatively stable but upper and lower anterior teeth and antero-superiorly rotated palatal plane relapsed to original position. 4. During the retention period, the soft tissue of lips was stable antero-posteriorly and moved mote inferiorly than posttreatment. 5. The correlation coefficients between the postion of upper and lower incisal edge and that position of lips were high, especially in horizontal change.

• The korean journal of orthodontics
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• v.29 no.6 s.77
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• pp.673-688
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• 1999

This study was conducted in order to analyze the mechanical characteristics of multiloop edgewise archwire (MEAW). The purposes were 1) to compare load deflection rate (LDR) of MEAW with that of various other arch wires in the individual interbracket span, 2) to compare the wire stiffness in the interbracket span with that in the multi-L-loop region (the span from distal border of the bracket of the lateral incisor to the mesial border of the buccal tube of the second molar), and 3) to verify the experimental results with theoretically derived formula. The single L-loops of five different horizontal lengths and multi-L-loops for the upper and lower arches were made out of .$016\times.022$ permachrome stainless steel wire. Straight segment of plain stainless steel, TMA and NiTi wire of the same dimension were prepared. The LDR was measured using Instron model 4466 with the load cell of 50N capacity at cross head speed of 1.0mm/min, and maximum deflection of 1.0mm. Five specimens were tested under each experimental condition. The wire stiffness number for each interbracket region and multi-L-loop region was calculated from the LDR and the interbracket spans. By dividing the theoretical model of multi-L-loop into 35 linear segments, the energy stored in each segment was obtained. Then the LDR and wire stiffness of single L-loop and multi-L-loop were calculated and compared. The findings were as follows : 1) The average LDR of MEAW in the individual interbracket region was 1/1.53 of that of the NiTi,1/2.47 of TMA and 1/5.16 of the plain stainless steel wire. 2) The wire stiffness of MEAW in the multi-L-loop region was 1.53 times larger than that in the interbracket region, and the LDR was almost twice as large as that of NiTi in that region. 3) According to the theoretically derived equation, the wire stiffness of the single L-loop was lower than that of multi-L-loop. The results of this study suggest that MEAW has the unique mechanical Property which could allow individual tooth movement and transmit elastic force effectively through the entire arch wire.

• Korean Journal of Applied Biomechanics
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• v.12 no.2
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• pp.345-359
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• 2002

The purpose of the study was to provide the fundamental data to instruct athletes through the analysis athletes' movement in javelin. Three athletes in the level of national representative were participated in this study. The study analyzed kinematic variables(lead foot and releasing javelin) through 3-D analysis and obtained the following results. 1. During withdrawal, it is important to maintain of running horizontal velocity. 2. It was showed that throng average height was $84{\pm}3.3%$ and javelin adequative degree, Among the athletes, $S_2$ who had the best record was released the javelin with the fast velocity, but throw the javelin with the less releasing velocity. 3. $S_2$ released after lead foot were completely landed and therefore it is no problem in a kinematic aspect. However, $S_1$ angle was too small. it caused increase of release velocity to be prevented. 4. $S_2$ showing the best result indicated shorter in duration time. Generally, the shorter duration time in release phase showed the longer release distance. Especially $S_1$ and $S_3$ showing the worse result indicated the longer duration time in preparatory phase, causing the breakup of force. Therefore to improve the record, it should be decreased the duration time in preparatory phase. 5. Compared with $S_1$ and $S_3$, $S_2$ showing the best record indicated the higher velocity in center of mass, trunk, upper arm, lower arm and hand That is the higher velocity of upper arm at release leaded the better velocity transfer from upper arm to following lower arm and hand, these action should be considered to be helpful of better record. According to the above conclusion, when the athletic leaders cauch athletes, they should focus on maintaining knee angle, upper body and hip angle in a previous stage of release and throwing angle, throwing height, throwing velocity in a release stage.