• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.20 no.5
• /
• pp.8-16
• /
• 2021

This study develops a shaft analysis model for the optimization of the power transmission system. The finite element method was used for the shaft analysis model. The shaft and gear were assumed Timoshenko beams. Strength was evaluated according to DIN 743, and gear misalignment was calculated through ISO 6336 and the coordinate system rotation. The analysis software for a power transmission system was developed using Visual Studio 2019. The analysis results of the developed program were compared with those of commercial software (MASTA, KISSsoft, and Romax). We confirmed that the force, deformation, and safety factors at each node were the same as those of the commercial software. The absolute value of the gear misalignment of the developed program and commercial software was different. However, the gear misalignment tended to increase with increasing the displacement in the tooth width direction.

• The korean journal of orthodontics
• /
• v.52 no.6
• /
• pp.451-460
• /
• 2022

Moebius syndrome (MBS) is a congenital neurologic disorder that causes cranio-facial abnormalities. It involves paralysis of the VI and VII cranial nerves and causes bilateral or unilateral facial paralysis, eye movement disorder, and deformation of the upper and lower limbs. The orofacial dysfunctions include microstomia, micrognathia, hypotonic mimetic and lip muscles, dental enamel hypoplasia, tongue deformity, open bite or deep overbite, maxillary hypoplasia, high arched palate, mandibular hyperplasia or features indicating mandibular hypoplasia. This case report presents a 7-year-old male patient who was diagnosed with MBS at the age 2 years. The patient displayed typical clinical symptoms and was diagnosed with Class II malocclusion with a large overjet/overbite, tongue deformity and motion limitation, and lip closure incompetency. Treatment was initiated using a removable appliance for left scissor bite correction. After permanent tooth eruption, fixed appliance treatment was performed for correction of the arch width discrepancy and deep overbite. A self-ligation system and wide-width arch form wire were used during the treatment to expand the arch width. After 30 months of phase II treatment, the alignment of the dental arch and stable molar occlusion was achieved. Function and occlusion remained stable with a Class I canine and molar relationship, and a normal overjet/overbite was maintained after 9.4 years of retainer use. In MBS patients, it is important to achieve an accurate early diagnosis, and implement a multidisciplinary treatment approach and long-term retention and follow-up.

• Journal of Korean society of Dental Hygiene
• /
• v.23 no.5
• /
• pp.395-402
• /
• 2023

Objectives: This study aimed to identify factors related to oral health and depression in Korean adults and contribute to the development of a mental health program to improve depression through oral health management. Methods: Data was obtained from the 2021 Korean Community Health Survey. The chi-square test was used to determine the differences in depression experience relative to general participant characteristics and their oral health. To determine the odds ratio and 95% confidence interval, multiple logistic regression analysis was used. All statistical analyses were performed using the SAS software (version 9.4). Results: The results suggest that depression may be influenced by gender, age, household generation, drinking habits, subjective health level, moderate to high exercise, breakfast, high blood pressure, diabetes, subjective oral health level, chewing discomfort, and tooth brushing. An increasing level of depression was associated with decreasing subjective oral health level (1.34 times), uncomfortable chewing (3.08 times), and frequency of toothbrushing after lunch or before going to bed (1.23 times and 1.58 times, respectively). Conclusions: Our study confirmed a close relationship between oral health and mental health. In developing health programs for improving depression, appropriate oral health care should be considered.

• Journal of Oral Medicine and Pain
• /
• v.19 no.2
• /
• pp.221-231
• /
• 1994

Age determination in children have been criticized because they rely on subjective estimations of tooth development, as seen in radiographs. This study was undertaken to obtain the objective estimation of developing teeth. The panoramic radiograph of 254 males and 254 females ranging from 6 to 14 years of age were studied. The structures measured were crown height, apex width and root length. The data weree statistically investigated with SPSS/PC + package. The results were as follows : 1. With the aid of a multiple regression model, a linear relationship between some of these distances and age was shown. 2. In th total material(6-14yr) and four-yr. intervals, linear equations are as follow : Boys : 6-14 age = 683 + 145.6 44RL + 126.6.45RL + 71.1 46DRL - 161.3 46DAW 6-10 age = 1202 + 72.6 46DRL + 100.2 44RL + 75.1 45RL 8-12 age = 3818 + 75.9 45RL - 190.9 44AW 10-14 age = 4151 + 58.6 45RL - 84.0 45AW - 130.6 44AW Girls : 6-14 age = 1587 + 104.9 45RL + 113.4 44RL - 233.1 46DAW + 81.4 47DRL - 255.9 46MAW 6-10 age = 1821 + 55.8 46DRL + 67.2 45RL - 184.2 46MAW + 56.3 44RL 8-12 age = 2435 + 68.2 45RLL + 71.3 44RL 10-14 age = 3485 + 49.9 47DRL - 51.3 45AW - 179.9 47DAW + 33.4 45RL + 39.4 44RL (DRL, length of distal root in molars. RL, root length in premolars. DAW, width of distal apex in molars. MAW, width of mesial apex in molars. AW, width of apex n molars)

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.26 no.5
• /
• pp.559-566
• /
• 2016

This study shows a development procedure and results of noise reduction for a new developed FF 8th speed automatic transmission. Based on planetary gear operating frequency analysis using PTA(planetary transmission analysis) program developed in 2012, It is expected that gear noise of the rear planetary gear set could be recognized easily in the concept design stage. Therefore, pRMC (planetary run many cases) analysis program that is developed in 2012 was applied to minimize the planetary gear noise level and noise distributions versus torque. To minimize noises coming from oil pump and final gears of a new transmission, several changes were applied, such as changing the clearance of double angular ball bearing, the oil pump rotor tooth number from 9 to 11 and the oil pump type from parachoid to megafloid and so on. Besides, stiffness values of the transmission case and the mount bracket were measured and reinforced properly. Finally, The total noise of the new FF 8th speed automatic transmission was developed successfully. Furthermore, E.O.L. testers also have been adapted to control the noise quality of automatic transmission assembly in the manufacturing factory. This paper could provide practical solutions to the automatic transmission NVH problems.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.25 no.7
• /
• pp.487-495
• /
• 2015

A generalized special program called planetary transmission analysis(here in after PTA) is developed to improve planetary gear noise in automatic transmission. PTA is capable of analyzing any typical one-degree-of-freedom automatic transmission gear train containing any number of simple, compound or complex-compound planetary gear sets. The kinematics module in PTA can compute the rotational speeds of gears and carriers and calculate the order frequencies to predict the planetary noise components. The power flow analysis module performs a complete static force analysis providing forces, moments, or torques of gears, bearings, clutches and connections. Based on the given type and number of planetary gear sets, the search algorithm determines all possible kinematic configurations and gear tooth combinations in a required set of gear ratios, while eliminating whole kinematic redundancies and unfavorable clutching sequences. By using PTA program, planetary internal speeds of new developed automatic transmission are early obtained; therefore, possibility of the noise problem could be predicted in early design stage. As implementing PTA in planetary gear NVH development procedure, planetary gear noise was successfully reduced by 10 dBA.

• Transactions of Materials Processing
• /
• v.17 no.1
• /
• pp.59-67
• /
• 2008

This paper is concerned with the development of multi-action die or multiple sliding die for the forming process of serrated sheets. Serrated sheets is used as a toothed or serrated seal for securing together overlapping portions of steel or plastic strapping ligature and have been produced conventionally in several methods such as rolling and indentation. Recently, longitudinally oriented thermoplastic materials have been widely used in the strapping industry, while such materials are quite slippery. Provided projections on a seal biting into the strap should overcome the slipperiness and also the tooth configuration must be closely controlled to avoid too much transverse penetration of the strap which could result in the shredding of the strap when it is placed under tension. The seal includes a central portion with a plurality of teeth which bite into one strap portion and a pair of reversely bent legs with a plurality of teeth which bite into the other strap portion. Forming processes applicable for serrated sheets have reviewed in qualitative sense to find possibility in terms of applicability of one of existing processes to the serrated sheet forming process. Existing seal products have been analyzed with enlarged picture of strap contacting surface of the seal by microscope. Based on the analyses of the existing forming processes and seal products, a new forming process is proposed for serrated sheets. The proposed process requires a multislide die which enables inclined indentation or cut-in into the seal material as well as scratching processes sequentially in a single action press.

• The Journal of Korean Society for School & Community Health Education
• /
• v.12 no.1
• /
• pp.91-102
• /
• 2011

Objectives: The purpose of this study is to identify the extent of the health behaviors of juveniles with experience in drug and the extent of their oral health behaviors. Then the impact of such factors on the oral health was analyzed. Methods: The analysis in this study used the raw data from 'The Fifth Korea Youth Risk Behavior Web-based Survey' after getting approval for use from the Center for Disease Control. The research subjects of this study were juveniles with experience in drug. Analysis was done by using 8 socio-demographic variables, 6 health behaviors related variables, 4 oral-health behaviors related variables and 1 oral health related variable. All survey data were analyzed by SPSS WIN 17.0 program. as frequency analysis and logistic regression. Results: The factors that give impact on the oral health of juveniles with drug experience were found as: gender, academic year, study grade, school type, school class, city scale, economic status, residential type, experience in alcohol, experience in smoking, obesity, frequency of medium-level physical exercise, eating breakfast frequency, hours of sleeping, number of tooth-brushing in one day, brushing teeth after lunch frequency, experience in dental treatment and experience in oral health training. Conclusions: In order to improve the oral health of juveniles with drug experience, health behaviors such as stop-smoking, stop-drinking and regular physical exercise are recommended. In addition, they should stop using drugs that threats their oral health. The development of nursing intervention to maintain the continuous enhancement of their oral health is also required.

• Journal of the East Asian Society of Dietary Life
• /
• v.15 no.4
• /
• pp.373-385
• /
• 2005

This study was carried out to investigate the lactation and weaning practice of infants and their mothers' attitude on infant nutrition. We interviewed 152 mothers in three pediatric clinics located in Sokcho city. From this survey, $76.3\%$ of infants was fed colostrum milk during first one week of life. During the first 4 months, $31.6\%$ of infants was fed breast-milk, while $42.8\%$ of them was fed bottled-milk. More housewives fed their babies with breast milk than the working mothers. Infants ate first weaning food at 5.73$\pm$1.86 months of life. Highly educated mothers showed positive response to the questionnaire : Breast-feeding is good for baby but it requires mother's sacrifice, and Breast-feeding may ruin the good shape of mothers. Highly income mothers responded negatively to the statement : Breast-feeding is not a must for infants since bottled-milk is a good substitution for breast-milk. Comparing with the mothers whose income was about 1 -2 million won per month, with ones who got paid less than 1 million won per month the former responded positively to : Breast-feeding is good for baby but it requires mother's sacrifice. Mothers recognized the importance of weaning in the following order : Supply of nutrition, Enforcement of digestion and absorption capability, Variety of taste, Disease prevention, Development of self-reliance, and Development of baby tooth. To improve the infants' nutritional status, education program on infant nutrition should be organized and run for the pregnant and lactating women in obstetrician and pediatric clinics and through the mass media as well.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.40 no.2
• /
• pp.127-132
• /
• 2013

Traumatic injuries to immature permanent teeth are common and the results can be destructive. Although Hertwig's epithelial root sheath is usually sensitive to trauma, it may resist damage from trauma thereby retaining its vitality and continuing to calcify a root under favorable conditions. This case report describes two cases of trauma to immature permanent incisors. The first case presents an avulsed maxillary central incisor which has been replanted. The other case shows completely avulsed mandibular central incisors which have not been replanted. However, both cases subsequently show continued growing roots separated from the main roots. This report highlights the ability of the immature pulp tissue to continue to form dentin and the robustness of Hertwig's epithelial root sheath to initiate root development despite a traumatic injury.