• Ocean and Polar Research
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• v.40 no.4
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• pp.213-222
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• 2018

We investigated seasonal variations in the abundance of the adults and the resting eggs of copepods to understand the role of copepod resting eggs for maintaining their population inhabiting the coastal area of Dadaepo, Korea. Adults and resting eggs of copepods were collected bi-monthly with a conical net (45 cm mouth diameter, $330{\mu}m$ mesh size) and van Veen grab ($0.1m^2$ area), respectively, from October 2016 to September 2017. The species of resting eggs were identified using mtCOI gene. The mean abundance of copepods was highest in October ($3686{\pm}1190inds{\cdot}m^{-3}$) and lowest in January ($176{\pm}60inds{\cdot}m^{-3}$) with the dominance of Paracalanus parvus s.l.. Among copepod producing resting eggs, Acartia omorii and Centropages abdominalis were dominant. The mean abundance of resting eggs was the highest in July ($9148{\pm}6787eggs{\cdot}m^{-2}$) and the lowest in October ($530{\pm}348eggs{\cdot}m^{-2}$). Most of the collected resting eggs were identified as A. omorii's. The mean abundances of A. omorii adults and resting eggs were highest in July, and both abundances fluctuated in a similar pattern except in September. In September, A. omorii adults were observed in a state of low abundance, while their resting eggs occurred in a state of high abundance. These results suggest that A. omorii maintain their population by producing a large quantity of resting eggs, particularly diapause eggs, before the seawater temperature rises. These eggs would hatch and be newly recruited to their population when the environmental condition becomes favorable.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.7
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• pp.950-957
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• 2023

For safe mooring and towing between the ship and port, the equipment must be designed in accordance with the relevant international regulations. However, some small shipyards and engineering companies often do not fully comprehend the core contents. Therefore, the international regulations regarding towing and mooring equipment are reviewed and the bollard and chock are newly developed based on the Mooring Equipment Guideline 4 (MEG4) standards. A bollard is a mooring equipment used to fix a mooring rope to the hull. It has two columns and is mostly used in a figure eight pattern knots under the mooring condition. The chock, which is used to change the mooring rope direction coming into the ship from outside, is manufactured using a casting with curvature. The two mooring equipment are widely used in the stern, bow, and mid-side. Owing to the increase in the size of container vessels and LNG ships, the mooring rope load has increased and the safe working load of the mooring equipment must be revised. This study summarizes and examines the results of the allowable stress method obtained using finite element analysis modelling. To consider the mesh size effect, a reasonable criteria was suggested by referring the existing class guidance. Additionally, the safe working load was verified through nonlinear collapse analysis, and the elastic region against load increments was confirmed. Furthermore, the proposed evaluation method can be used to develop similar equipment in the near future.

• Journal of Adhesion and Interface
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• v.25 no.1
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• pp.169-274
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• 2024

Recent attention has been drawn to materials that undergo reversible expansion and contraction in response to external stimuli, leading to morphological changes. These materials hold potential applications in various fields including soft robotics, sensors, and artificial muscles. In this study, a novel material capable of responding to high temperatures for protection or encapsulation is proposed. To achieve this, liquid crystal elastomer (LCE) with nematic-isotropic transition properties and polyimide (PI) with high mechanical strength and thermal stability were utilized. To utilize a solution process, a dope solution was synthesized and introduced into micro-printing techniques to develop a two-dimensional pattern of LCE/PI bilayer structures with sub-millimeter widths. The honeycomb-patterned LCE/PI bilayer mesh combined the mechanical strength of PI with the high-temperature contraction behavior of LCE, and selective printing of LCE facilitated deformation in desired directions at high temperatures. Consequently, the functionality of selectively and reversibly encapsulating specific high-temperature materials was achieved. This study suggests potential applications in various actuator fields where functionalities can be implemented across different temperature ranges without the need for electrical energy input, contingent upon molecular changes in LCE.

• Journal of Dental Rehabilitation and Applied Science
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• v.24 no.2
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• pp.213-230
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• 2008

The aim of this study was to analyze the initial movement and the stress distribution of each tooth and periodontal ligament during the lingual lever-arm retraction of 6 maxillary incisors using FEA. Two kinds of finite element models were produced: 2-properties model (simple model) and 24-properties model (multi model) according to the material property assignment. The subject was an adult male of 23 years old. The DICOM images through the CT of the patient were converted into the 3D image model of a skull using the Mimics (version 10.11, Materialise's interactive Medical Image Control System, Materialise, Belgium). After series of calculating, remeshing, exporting, importing process and volume mesh process was performed, FEA models were produced. FEA models are consisted of maxilla, maxillary central incisor, lateral incisor, canine, periodontal ligaments and lingual traction arm. The boundary conditions fixed the movements of posterior, sagittal and upper part of the model to the directions of X, Y, Z axis respectively. The model was set to be symmetrical to X axis. Through the center of resistance of maxilla complex, a retraction force of 200g was applied horizontally to the occlusal plane. Under this conditions, the initial movements and stress distributions were evaluated by 3D FEA. In the result, the amount of posterior movement was larger in the multi model than in the simple model as well as the amount of vertically rotation. The pattern of the posterior movement in the central incisors and lateral incisors was controlled tipping movement, and the amount was larger than in the canine. But the amount of root movement of the canine was larger than others. The incisor rotated downwardly and the canines upwardly around contact points of lateral incisor and canine in the both models. The values of stress are similar in the both simple and multi model.

• Journal of Periodontal and Implant Science
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• v.32 no.4
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• pp.781-800
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• 2002

The major goals of periodontal therapy are the functional regeneration of periodontal supporting structures already destructed by periodontal disease. There have been many efforts to develop materials and therapeutic methods to promote periodontal wound healing. With the development of non-resorbable membrane, GTR has proved to be the representive technique of periodontal regeneration. However, due to various clinical problems of non-resorbable membrane, resorbable membrane was developed and it showed to be clinically effective. The newly developed Para-Dioxanone membrane has a characteristic of non-woven fabric structures which is different from the generally used membranes with structure of mesh form. In addition, Chitosan membrane has been developed to apply its adventage maximally in GTR. Although a number of different types of membranes had been clinically used, researches on absorption rate of membranes were inadequate and limited to subjective opinions. However, since long term period of resorption and space maintenance are required in implant or ridge augmentation, accurate verification of resorption rate is clinically important. In this study, we had implanted Resolut(R), Biomesh(R), Para-Dioxanone membrane and Chitosan membrane (Size : 4mm ${\times}$ 4mm) on dorsal side of Sprague Dawley rat, and sacrified them after 4 weeks, 8 weeks, 12 weeks respectively. Histologic observation was carried out, and the following results were obtained by calculating the objective resorption rate. 1. In case of Resolut(R), external resorption took place initially, followed by internal resorption. Surface area are 5.76${\pm}$2.37$mm^2$, 4.90${\pm}$l.06$mm^2$, 4.90${\pm}$0.98$mm^2$ at 4 weeks, 8 weeks, 12 weeks respectively, and invasion rate of connective tissue to membrane are 31.6${\pm}$4.5%, 52.8${\pm}$9.4%, 56.4${\pm}$5.1% respectively. 2. Biomesh(R) showed a pattern of folding, relatively slow resorption rate with small size of membrane. Surface area are 3.62${\pm}$0.82$mm^2$, 3.63${\pm}$0.76$mm^2$, 4.07${\pm}$1.14$mm^2$ at 4 weeks, 8 weeks, 12 weeks respectively, and invasion rate of connective tissue to membrane are 26.1${\pm}$5.8%, 30.9${\pm}$3.4%, 29.2${\pm}$3.6%, respectively. 3. Para-Dioxanone membrane was surrounded by fibrous conncetive tissue externally, and resorption took place internally and externally. Surface area are 5.96${\pm}$1.05$mm^2$, 4.77${\pm}$10.76$mm^2$, 3.86${\pm}$0.84$mm^2$ at 4 weeks, 8 weeks, 12 weeks respectively, and invasion rate of connective tissue to membrane are 30.7${\pm}$5.1%, 53.3${\pm}$4.4%, 69.5${\pm}$3.1%, respectively. 4. Each fiber of Chitosan membrane was surrounded by connective tissue and showed external resorption pattern. It showed little invasion of inflammatory cells and excellent biocompatability. The resorption rate was relatively slow. Surface area are 6.01${\pm}$2.01$mm^2$, 5.49${\pm}$1.3$mm^2$, 5.06${\pm}$1.38$mm^2$ at 4 weeks, 8 weeks, 12 weeks respectively, and invasion rate of connective tissue to membrane are 31.3${\pm}$3.6%, 38.4${\pm}$3.80%, 39.7${\pm}$5.6%, respectively. Consequently, Para-Dioxanone membrane and Chitosan membrane are found to be clinically effective for their excellent tissue reaction and biocompatibility. Futhermore, the advantage of bone regenerating ability as well as the relatively long resorption period of Chitosan membrane, it might be widely used in implant or ridge augmentation.

• Progress in Medical Physics
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• v.21 no.1
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• pp.86-92
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• 2010

The purpose of this study was to measure curvature contour skin dose using radiochromic film and TLD for a conventional open field. We also attempted to quantify the degradation of skin sparing associated with use of immobilization devices for high energy photon beams and to calculate the skin dose with a help of Monte Carlo (MC) simulation. To simulate head-and-neck and shoulder treatment, a cylindrical solid water phantom 11 cm in diameter was irradiated with 6 MV x-rays using $40{\times}40\;cm^2$ field at 100 cm source axis distance (SAD) to the center of the phantom. Aquaplastic mesh mask was placed on the surface of the cylindrical phantom that mimicked relevant clinical situations. The skin dose profile was obtained by taking measurements from $0^{\circ}$ to $360^{\circ}$ around the circumference of the cylindrical phantom. The skin doses obtained from radiochromic film were found to be 47% of the maximum dose of $D_{max}$ at the $0^{\circ}$ beam entry position and 61% at the $90^{\circ}$ oblique beam position without the mask. Using the mask (1.5 mm), the skin dose received was 59% at $0^{\circ}$ incidence and 78% at $80^{\circ}$ incidence. Skin dose results were also gathered using thin thermoluminescent dosimeters (TLD). With the mask, the skin dose was 66% at $0^{\circ}$ incidence and 80% at $80^{\circ}$ incidence. This method with the mask revealed the similar pattern as film measurement. For the treatments of the head-and-neck and shoulder regions in which immobilization mask was used, skin doses at around tangential angle were nearly the same as the prescription dose. When a sloping skin contour is encountered, skin doses may be abated using thinner and more perforated immoblization devices which should still maintain immoblization.

• Journal of Yeungnam Medical Science
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• v.11 no.2
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• pp.293-302
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• 1994

The objective of this study was to establish a good methodology to isolate single smooth muscle cells that are alive and respond properly to pharmacological agents. Canine urinary bladders were employed as the source of single cells, and acetylcholine, atropine and imipramine were used as indicators of pharmacological responsiveness. Imipramine, an antidepressant drug exhibited the anticholinergic and calcium antagonizing properties on rat detrusor muscle. To establish a control value for a further experiment to elucidate the mechanism of action of imipramine on detrusor muscle, we measured the concentration-response of single cells to acetylcholine in the presesnce of imipramine by length of the cells and compared the result with the response in the presence of atropine. Tiny chops of smooth muscle taken from anesthetized canine urinary bladder were incubated in collagenase solution at $36^{\circ}C$ for 17-20 minutes. The collagenase solution included collagenase 1.2 mg/ml, soybean tryspin inhibitor 0.08 mg/ml, bovine serum albumin 2% in 10 ml Krebs-Henseleit buffer solution aerated with a consistent breeze of 95/5% $O_2/CO_2$, to maintain the pH at 7.4. After washing with plain K-H solution on 450 mesh, cells were dissociated from the digested tissue for 12-15 minutes. Cell suspension was transfered in 5 ml test tubes and acetylcholine was added for the final concentration to be $10^{-14}M{\sim}10^{-9}M$. To find the optimal time to fix the cells to determine the contractile responses, 1% acrolein was added 5, 10, 20, 30, 60 and 120 seconds after the administration of ACh. The length of cells fixed by acrolein were measured by microscaler via CCTV camera on phaes-contrast microscope. The average length of 50 cells from a slide glass was taken as the value of a sample at the very concentration point. Single cells were isolated from canine detrusor. The length of untreated cells varied from 82 ${\mu}m$ to 94 ${\mu}m$. The maximal response to actylcholine $10^{-9}M$ was accomplished within 5 seconds of exposure, and the shortening was $19{\pm}3$%. Atropine reduced the contraction of the cells concentration-dependently. Imipramine which exerts a cholinergic blocking action on some smooth muscles also reduced the contraction concentration-dependently and by a similar pattern as atropine. These findings document that imipramine may exerts a cholinergic blocking activity in the single smooth muscle cells isolated from canine urinary bladder.

• The Journal of Korean Academy of Prosthodontics
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• v.49 no.4
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• pp.316-323
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• 2011

Purpose: The purpose of this study was to investigate the effect of different thread designs on the marginal bone stresses around dental implant. Materials and methods: Standard ITI implant(ITI Dental Implant System; Straumann AG, Waldenburg, Switzerland), 4.1 mm in diameter and 10 mm in length, was selected as control. Test implants of four different thread patterns were created based on control implant, i.e. maintaining all geometrical design of control implant except thread pattern. Four thread designs used in test implants include (1) small V-shape screw (model A), (2) large V-shape screw (model B), (3) buttress screw (model C), and (4) trapezoid screw (model D). Surface area for unit length of implant was 14.4 $mm^2$ (control), 21.7 (small V-shape screw), 20.6 (large V-shape screw), 17.0 (buttress screw) and 28.7 $mm^2$ (trapezoid screw). Finite element models of implant/bone complex were created using an axisymmetric scheme with the use of NISA II/DISPLAY III (Engineering Mechanics Research Corporation, Troy, MI, USA). A load of 100 N applied to the central node on the crown top either in parallel direction or at 30 degree to the implant axis (in order to apply non-axial load to the implant NKTP type 34 element was employed). Quantification and comparison of the peak stress in the marginal bone of each implant model was made using a series of regression analyses based on the stress data calculated at the 5 reference points which were set at 0.2, 0.4, 0.6, 0.8 and 1.0 mm from implant wall on the marginal bone surface. Results: Results showed that although severe stress concentration on the marginal bone cannot be avoided a substantial reduction in the peak stress is achievable using different thread design. The peak marginal bone stresses under vertical loading condition were 7.84, 6.45, 5.96, 6.85, 5.39 MPa for control and model A, B, C and D, respectively. And 29.18, 26.45, 25.12, 27.37, 23.58 MPa when subject to inclined loading. Conclusion: It was concluded that the thread design is an important influential factor to the marginal bone stresses.