• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.8
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• pp.200-207
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• 2016

The automotive seat is an important component that moves in sync with the driver and is actively being developed with various new functions. The aim of this work is to develop a lightweight seat cushion extension module using a lightweight material. To this end, a structural strength analysis, vertical strength test, and durability test were conducted. In the structural analysis, the maximum value of deformation under vertical load was 4.98 mm at the front of the upper panel. The maximum stress was approximately 105 MPa, which occurred at the point of contact between the upper and lower panels of the module. The vertical strength test showed a maximum vertical deformation of 5.31 mm under a vertical load, which differed from the analysis results by approximately 6.45%. The structural safety of the product was verified by the fact that it showed no harmful deformation or damage during operation after the vertical strength test and a durability test for 20,000 cycles. Furthermore, the use of engineering plastics made it possible to reduce the weight by approximately 30% compared to existing products. The lack of damage after tests verified the passenger safety, strength, and rigidity of the product. The results are expected to be applied for improving environmental and fuel efficiency regulations and preventing accidents due to driver fatigue. The applications of this module could be expanded various types of vehicles, as well as other industries in which eco-friendly and lightweight materials are used.

• Journal of Korean society of Dental Hygiene
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• v.9 no.3
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• pp.468-478
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• 2009

This research was performed to provide basic data for the development of infection related dental hygiene studies by surveying the current condition of recognition among students in the department of dental hygiene toward hospital infection management while receiving the following results by using a personal self-administered survey method targeting 303 students in the department of dental hygiene from certain areas. 1. With the current condition of recognition on the sanitization and sterilization of instruments among students in the department of dental hygiene(study), the rate at which surgical instruments are to be sterilized with autoclaves was 79.9% which was relatively higher than other instruments while it was shown that prosthetic instruments for treatment was 56.4%, conservative instruments for treatment was 51.8%, and ultrasonic scaler tip was 51.1% while the way syringe tips(36.1%) and the dental anesthetic apparatus(27.9%) were revealed to require sanitization by alcohol. 2. The 'hand wash' area was the highest with 4.71 while the 'materials and environment management' area and 'equipment management' area appeared high respectively with 4.43 and 4.41. 3. With the current condition of recognition on equipment management, 'equipments used for contagious patients are separately washed after a one-time use and must be sterilized or separated-and-discarded' was the highest with 4.82 while 'sterilization equipments with humidity or water on it are considered contaminated and are not used' showed the lowest recognition level with 3.90. 4. Regarding the current condition of materials and environment management, 'contagious and general trash are separated and discarded' was the highest with 4.70 while 'the refrigerator for medicine storage is cleaned on a regular basis once a month' was revealed as the lowest with 4.11. 5. With the current condition of recognition on hand washing, 'one must wash their hands after coming in contact with contagious patients, was the highest with 4.90 while washing hands after taking off gloves' appeared as the lowest with 4.51 point. To conclude department of dental hygiene there is to infection management and necessary about organization disinfecting and pasteurization to strengthen an education in order raising a stamp helping practical ratio about the infection management which whole, is from presence at a sickbed and connection does and about the infection management which is substantial and educational program development leads feed with the fact that deepening studying which is continuous must become accomplished becomes.

• Journal of Veterinary Clinics
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• v.11 no.2
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• pp.529-537
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• 1994

Sector scanner which has a conical end is used to image through the intercostal space because heart is protected by the ribs. Cardiac data published all around the world were also obtained by sector scanner. Although scanners being used in every small animal practice and animal hospital at college in Korea include convex ape and linear type, linear type is not appropriate f3r cardiac scan because of a wide contact surface. The purpose of this study is to establish ultrasonographic images of normal cardiac structures by measuring shape, size of reflectable cardiac structure according to restraint position in scanning normal heart of the puppies with 6.5 MHz convex scanner(SonoAce 4500, Medison, Korea) used in our veterinary teaching hospital, Seoul national university. Seventeen male and female puppies considered having healthy hear by X-ray and clinical examination are used feom April to July 1994. Scanning point selection of probe head and the distinction of imaged cardiac structures were accomplished by necropsy and cardiac scanning performed through thoracotomy under general anesthesia. At 10 o'clock position of transducer(at an angle of 30$^{\circ}$ between imaginary line from elbow joint to 3rd sternum and probe head, 60$^{\circ}$ from body surface, 4th intercostal space of right thorax) with the marker of scanner toward the head of dogs right atrium, left atrium and left ventricle were observed in 2, 3, 4, 5 intercostal space(2cm from the sternum) of experimental dog positioned ventrodorsally under general anesthesia. Under these conditions, the numerical values of imaged diastolic hear are as follows : the distance from skin to apex(mean$\pm$S.D) 47.53$\pm$6.94mm, thickness of left ventricular wall 6.00$\pm$1.60mm, length of left ventricle 16.27$\pm$5.31mm, width of left ventricle 15,33$\pm$4.25mm, length of left atrium 12.33$\pm$3.82mm, width of left atrium 11. 33$\pm$3.94mm, length of right atrium 1.00$\pm$2.41mm, width of right atrium 11.21$\pm$2.76mm and the area of left ventricle 270.92$\pm$109.81mm$^2$, area of left atrium 98.00$\pm$41.08mm$^2$, area of right atrium 62.75$\pm$21.04mm$^2$.

• Journal of Conservation Science
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• v.26 no.2
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• pp.149-156
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• 2010

One of resins, V-Flon is useful as a coating material because YK-D80, which is a solvent for V-Flon, is not highly volatile. However, it can not completely harden and can flow out when metal artifacts are joined and restored in the process of the treatment. Therefore, after the impregnation process in order to accelerate the hardening speed of a coating material, usually a dry oven was adopted. This study focused on finding the problems on the dry oven which is employed to increase the speed and investigating the most effective solvent and its composition by checking any change occurred depending on the concentration of solvents. Six different types of solvents were selected and samples were prepared in a manner that they were impregnated with solvents in three concentrations respectively (10%, 20%, 30%). To determine the condition of the samples, the stability evaluation was performed by measuring the change of color and the gloss, the thickness of coated layers, the corrosion after coating, the water resistance by contact angles. Through the comparative experiments between the natural drying and the artificial drying using a dry oven, it was found that when the dry oven is used, some problems are identified on the point of forming a uniform and stable layer because of the unstable data collected from the forced artificial dry. The experiments performed using 3 different concentration rates (10%, 20%, 30%) presented that in the case of 10% V-Flon in Xylene (using as a solvent), its layer was thin as well as it showed the high water-barrier property, which allows it to form the stably coated layer with the lower gloss and color change.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.14 no.2
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• pp.169-178
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• 2016

The properties of wastes for melting need to be considered to minimize the maintenance of refractory and to discharge the molten slags smoothly from a plasma torch melter. When the nonflammable wastes from nuclear facilities such as concrete debris, glass, sand, etc., are melted, they become acid slags with low basicity since the chemical composition has much more acid oxides than basic oxides. A molten slag does not have good characteristics of discharge and is mainly responsible for the refractory erosion due to its low liquidity. In case of a stationary plasma torch melter with a slant tapping port on the wall, a fixed amount of molten slags remains inside of tapping hole as well as the melter inside after tapping out. Nonmetallic slags keep the temperature higher than melting point of metal because metallic slags located on the bottom of melter by specific gravity difference are simultaneously melted when dual mode plasma torch operates in transferred mode. In order to minimize the refractory erosion, the compatible refractories are selected considering the temperature inside the melter and the melting behavior of slags whether to contact or noncontact with molten slags. An acidic refractory shall not be installed in adjacent to a basic refractory for the resistibility against corrosion.

• Journal of Korean society of Dental Hygiene
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• v.7 no.4
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• pp.455-470
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• 2007

The usage of appropriate disinfectants is essential for infection control in dental hospitals, dental clinics. Inadequate use of disinfectants is the cause of human or environmental toxicity and is a waste of cost. This study was aimed to assess the level of knowledge on the disinfection and chemical disinfectants among dental workers in dental hospitals, dental clinics. It's ultimately intended to serve as a basis for the preparation of more effective, appropriate educational programs on the disinfection and manuals on the use of disinfectants for dental workers. This study enforced a questionnaire with 184 dental workers employed in dental hospitals, dental clinics from 15 Aug. to 15 Sep. 2007, in the area of Daejeon. The obtained result were as follows; 1. The population sociological feature of dental hospital and dental clinic showed that significant differences of dental service career(pM0.039). Dental service career of dental workers shows; below 3 years 42.9%, 4~6 years 34.7%, more than 7 years 22.4% in dental hospitals, below 3 years 30.4%, 4~6 years 26.7%, more than 7 years 43.0% in dental clinics(pM0.039). 2. The average score of dental workers knowledge in 'Critical item soaks in high-level disinfectants for 20minutes was 2.73V0.49 point, got from knowledge of dental instrument is appropriate to immerse before sterilization in the dental device disinfection(pM0.002). 3. In the general disinfection which it follows in education experience of chemical disinfectants direction for use, 'Direction for use by Spaulding process classification' responded that the correct answer was the education experience dental workers 60.0%, the education non-experience dental workers 39.5%(p=0.026). 4. In the dental device disinfection which it follows in education experience of chemical disinfectants direction for use. 'High level disinfection is not applied for the non-critical items and equipment' responded that the education experience dental workers 49.2%, the education non-experience dental workers 31.9%(pM0.045), 'Semi-critical items is applied same method in presence of the infection disease which it acts responded that the education experience dental workers 44.6% answer back, the education non-experience dental workers 24.4%(pM0.017). 5. 'A hand disinfectants of anticeptics have effect' the education experience dental workers 78.5% answer back, the education non-experience dental workers 52.9%(pM0.003). 1t uses with hand disinfectants when the instruments which be imbrued and patient contact', the education experience dental workers 78.5% answer back, the education non-experience dental workers 62.2%(pM0.026), 'Boric acid solution uses for the skin disinfectants the education experience dental workers 52.3% answer back, the education non-experience dental workers is 37.0%(pM0.016), 'Gluconate have effective difference which it follows in chemical disinfectant consistency and the solution type' education experience dental workers 72.3% answer back, education non-experience dental workers 47.9%(pM0.004). 6. The education experience dental workers were appeared higher than the education non-experience dental workers in knowledge of the disinfection and chemical disinfectants. Consequently system and the specialty education which is standardized continuously must be provided to all dental workers.

• Journal of Biosystems Engineering
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• v.42 no.2
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• pp.86-97
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• 2017

Purpose: This study aims to evaluate the applicability of a tractor-baler system equipped with a newly developed round baler by conducting stability analyses via static-state mathematical simulations and verification experiments for the tractor equipped with a loader. Methods: The centers of gravity of the tractor and baler were calculated to analyze the transverse overturning of the system. This overturning of the system was analyzed by applying mathematical equations presented in previous research and comparing the results with those obtained by the newly developed mathematical simulation. For the case of the tractor equipped with a loader, mathematical simulation results and experimental values from verification experiments were compared and verified. Results: The center of gravity of the system became lower after the baler was attached to the tractor and the angle of transverse overturning of the system steadily increased or decreased as the deflection angle increased or decreased between $0^{\circ}$ and $180^{\circ}$ on the same gradient. In the results of the simulations performed by applying mathematical equations from previous research, right transverse overturning occurred when the tilt angle was at least $19.5^{\circ}$ and the range of deflection angles was from $82^{\circ}$ to $262^{\circ}$ in counter clockwise. Additionally, left transverse overturning also occurred at tilt angles of at least $19.5^{\circ}$ and the range of deflection angles was from $259^{\circ}$ to $79^{\circ}$ in counter clockwise. Under the $0^{\circ}$ deflection angle condition, in simulations of the tractor equipped with a loader, transverse overturning occurred at $17.9^{\circ}$, which is a 2.3% change from the results of the verification experiment ($17.5^{\circ}$). The simulations applied the center of gravity and the correlations between the tilt angles, formed by individual wheel ground contact points excluding wheel radius and hinge point height, which cannot be easily measured, for the convenient use of mathematical equations. The results indicated that both left and right transverse overturning occurred at $19.5^{\circ}$. Conclusions: The transverse overturning stability evaluation of the system, conducted via mathematical equation modeling, was stable enough to replace the mathematical equations proposed by previous researchers. The verification experiments and their results indicated that the system is workable at $12^{\circ}$, which is the tolerance limit for agricultural machines on the sloped lands in South Korea, and $15^{\circ}$, which is the tolerance limit for agricultural machines on the sloped grasslands of hay in Japan.

• Korean Journal of Clinical Laboratory Science
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• v.52 no.1
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• pp.53-61
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• 2020

Cell migration is a central process for recovering from wounds triggered by physical distress besides embryogenesis and cancer metastasis. Wound healing assay is widely used as a fundamental research technique for investigation of two-dimensional cell migration in vitro. The most common approach for imitating physical wound in vitro is mechanical scratching on the surface of the confluent monolayer by using sharp materials. The iron metal pin with a suspension spring for fine adjustment of the orthogonal contact surface between the scratching point and the individual bottom of multi-well plate with planar curvatures were adopted for the creative invention of a 96-well plate wound maker. While classic tips drew diverse and zigzag scratching patterns on the confluent monolayer, our wound maker displayed synchronized linear wounds in the middle of each well of a 96-well plate that was seeded with several cell lines. Given that several types of multi-well plates commercially available are compatible with our lab-made wound maker for creating uniform scratches on the confluent monolayer for the collective cell migration in wound healing assay, it is certain that the application of this wound maker to the real-time wound healing assay in high content screening (HCS) is superior than utilization of typical polypropylene pipette tips.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.37 no.2
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• pp.114-121
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• 2011

Introduction: The aim of this study was to demonstrate that the simulation surgery on rapid prototype (RP) model, which is based on the 3-dimensional computed tomography (3D CT) data taken before surgery, has the same accuracy as traditional orthograthic surgery with an intermediate splint, using an optoelectronic tracking navigation system. Materials and Methods: Simulation surgery with the same treatment plan as the Le Fort I osteotomy on the patient was done on a RP model based on the 3D CT data of 12 patients who had undergone a Le Fort I osteotomy in the department of oral and maxillofacial surgery, Seoul National University Dental Hospital. The 12 distances between 4 points on the skull, such as both infraorbital foramen and both supraorbital foramen, and 3 points on maxilla, such as the contact point of both maxillary central incisors and mesiobuccal cuspal tip of both maxillary first molars, were tracked using an optoelectronic tracking navigation system. The distances before surgery were compared to evaluate the accuracy of the RP model and the distance changes of 3D CT image after surgery were compared with those of the RP model after simulation surgery. Results: A paired t-test revealed a significant difference between the distances in the 3D CT image and RP model before surgery.(P<0.0001) On the other hand, Pearson's correlation coefficient, 0.995, revealed a significant positive correlation between the distances.(P<0.0001) There was a significant difference between the change in the distance of the 3D CT image and RP model in before and after surgery.(P<0.05) The Pearson's correlation coefficient was 0.13844, indicating positive correlation.(P<0.1) Conclusion: Theses results suggest that the simulation surgery of a Le Fort I osteotomy using an optoelectronic tracking navigation system I s relatively accurate in comparing the pre-, and post-operative 3D CT data. Furthermore, the application of an optoelectronic tracking navigation system may be a predictable and efficient method in Le Fort I orthognathic surgery.

• Journal of Dental Rehabilitation and Applied Science
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• v.29 no.3
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• pp.259-271
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• 2013

The purpose of this study was to make the stress distribution produced by simulated different load under two types of internal connection implant system (stepped and tapered type) by means of 3D finite element analysis, The finite element model was designed with the parallel placement of the one fixtures ($4.0mm{\times}11.5mm$) with reverse buttress thread on the mandibular 1st molar. Two models were loaded with 200 N magnitude in the vertical direction on the central position of the crown, the 1.5 mm and 3 mm buccal offset point from the central position of the fixture. The oblique load was applied at the angle of $30^{\circ}$ on the crown surface. Von Mises stress value was recorded and compared in the fixture-bone interface in the bucco-lingual dimension. The results were as follows; 1. The loading conditions of two internal connection implant systems (stepped and tapered type) were the main factor affecting the equivalent bone strain, followed by the type of internal connections. 2. The stepped model had more mechanical stability with the reduced max. stress compared to $11^{\circ}$ tapered models under the distributed oblique loading. 3. The more the contact of implant-abutment interface to the inner wall of implant fixture, the less stress concentration was reduced.