• Journal of the korean academy of Pediatric Dentistry
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• v.29 no.1
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• pp.51-56
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• 2002

Russell-Silver syndrome is a type of intrauterine growth retardation, characterized by short stature noted at birth, hemiatrophy or asymmetry, variation in sexual development and other abnormalities, including cafe-aulait pigmentation and clinodactyly. Facial features commonly associated with this syndrome are a small triangular face, decreased facial height, down-turned corners of the mouth(shark's mouth), a small mandible, and occasionally asymmetry. The major intra-oral features of the syndrome that have been reported are a high-arched palate, delayed tooth eruption, microdontia, hypodontia, and crowding. These cases were diagnosed at birth as Russell-Silver syndrome by clinical features such as prenatal growth retardation, short stature, low body weight, et al., and have been treated with growth hormone. The purpose of this paper is to report the dental findings of two patients and review the pertinent literature through the two cases.

• Journal of the korean academy of Pediatric Dentistry
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• v.25 no.3
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• pp.533-538
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• 1998

[ $Garr{\grave{e}}'s$ ] osteomyelitis is a chronic form of osteomyelitis in which periosteum is thickened with peripheral reactive bone formation. Carl $Garr{\grave{e}}$ first reported localized periosteal thickening as a response to mild stimuli. In dental literatures, Pell et al. first reported $Garr{\grave{e}}'s$ osteomyelitis in jaws. This disease frequent occurs in youngsters and usually in mandible. It usually results in hard swelling over the jaws with little or no pain. Palpation reveals a localized bony swelling lesion. In radiographic findings, it usually reveals laminated periosteal thickening on lesion. The treatment of $Garr{\grave{e}}'s$ osteomyelitis usually consists of elimination of the sources of infection, i.e., either extraction of an infected teeth or root canal therapy. Two children were admitted with the chief complaint of intraoral swelling on lower deciduous molar areas which was diagnosed as $Garr{\grave{e}}'s$ osteomyelitis. The root canal therapy and antibiotic therapy were performed and prognosis was checked. From these case studies, some results were obtained as follows : With the aid of root canal therapy and antibiotic administration, the size of periapical lesions was reduced, the mandible with bony swelling recovered its normal shapes radiographically, and the permanent tooth germs resumed sound development.

• Journal of dental hygiene science
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• v.20 no.1
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• pp.44-50
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• 2020

Background: Smartphones are a modern necessity. While they are convenient to use, smartphones also have side effects such as addiction. This study assessed the relationship between smartphone use, a part of everyday life in modern society, and oral health. Methods: An analysis was conducted using 2017 Korea Youth Risk Behavior Web-based Survey data. The propensity score estimation algorithm used logistic regression and 1:1 matching algorithm using nearest-neighbor matching. After matching, a total of 15,032 participants were classified into two groups containing 7,516 teenagers each who did and did not use smartphones, respectively. Results: Comparison of oral health behaviors according to smartphone use revealed a statistically significant difference in the frequency of tooth brushing per day, use of oral hygiene products, intake of foods harmful to oral health, and experience of oral health education (p<0.05). The factors affecting oral pain experience of adolescents were examined. Compared to male participants, female participants had an odds ratio of 1.627 for oral pain (p<0.05). According to the household income level, compared to the group with higher income, the group with lower income showed higher oral pain experience (p<0.05). Oral pain experience was 1.601 times more frequent among teenagers using smartphones (p<0.05). Conclusion: The results of this study indicated that use of smartphones by adolescents affected their oral health. These findings indicate the need for improved oral health management through the use of effective school oral health programs and individual counseling by oral health professionals, promotion of information dissemination through public media, and development of prevention strategies.

• Korean Journal of Agricultural Science
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• v.47 no.2
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• pp.327-335
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• 2020

The purpose of this study was to analyze the load distribution and contact safety factor for the power take off (PTO) gear of a 71 kW class agricultural tractor. In this study, a simulation model of the PTO gear-train was developed using Romax DESGINER. The face load factor and contact safety factor were calculated using ISO 6336:2006. The simulation time was set at 2,736 hours considering the lifetime of the tractor, and the simulation was performed for each PTO gear stage at the engine rated power conditions. As a result of the simulation, the face load factors for the driving gear at the PTO 1^st, 2^nd and 3^rd stages were 1.644, 1.632, and 1.341, respectively. The contact safety factors for the driving gear at the PTO 1^st, 2^nd and 3^rd stages were 1.185, 1.216, and 1.458, respectively. As the PTO gear stage was increased, the face load factor decreased, and the contact safety factor increased. The load distributions for all the PTO gears were concentrated to the right of the tooth width. This causes stress concentrations and shortens the lifespan of the gears. Therefore, it is necessary to improve the face load factor and the contact safety factor with macro-geometry and micro-geometry.

• The Journal of Advanced Prosthodontics
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• v.7 no.2
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• pp.160-165
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• 2015

PURPOSE. In this study, a temporal abutment fixation screw, designed to fracture in a controlled way upon application of an occlusal force sufficient to produce critical micromotion was developed. The purpose of the screw was to protect the osseointegration of immediate loaded single implants. MATERIALS AND METHODS. Seven different screw prototypes were examined by fixing titanium abutments to 112 Mozo-Grau external hexagon implants (MG Osseous$^{(R)}$; Mozo-Grau, S.A., Valladolid, Spain). Fracture strength was tested at $30^{\circ}$ in two subgroups per screw: one under dynamic loading and the other without prior dynamic loading. Dynamic loading was performed in a single-axis chewing simulator using 150,000 load cycles at 50 N. After normal distribution of obtained data was verified by Kolmogorov-Smirnov test, fracture resistance between samples submitted and not submitted to dynamic loading was compared by the use of Student's t-test. Comparison of fracture resistance among different screw designs was performed by the use of one-way analysis of variance. Confidence interval was set at 95%. RESULTS. Fractures occurred in all screws, allowing easy retrieval. Screw Prototypes 2, 5 and 6 failed during dynamic loading and exhibited statistically significant differences from the other prototypes. CONCLUSION. Prototypes 2, 5 and 6 may offer a useful protective mechanism during occlusal overload in immediate loaded implants.

• Journal of the korean academy of Pediatric Dentistry
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• v.32 no.3
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• pp.491-498
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• 2005

Occlusal fissures and pits are ideal places for the development of caries. Pit and fissure sealants are now considered as a very effective means to prevent dental caries. The purpose of this investigation was to examine the effect on the sealant penetration of the elapse of time from the application of sealant until exposure to visible light, and to examine the effect of the filler content and tooth position on the sealant penetration. 192 extracted human premolars were used to this experiment. Following enamel conditioning, a light-polymerized sealant was applied and 4 different periods of time(3, 5, 10, 20 seconds) were allowed until exposure to the light source. The results obtained were as follows; 1. According to time, in both unfilled sealant and filled sealant penetration increases deeply through mindfulness. 2. Sealant that apply to mandiblar premolar penetrated deeply through than to maxillay teeth. 3. Penetration difference according to filler content, unfilled sealant penetrated deeply through than filled sealant. The result from this study indicated that unfilled sealant penetrated most deeply in mandible when at least 20s time elapsed.

• Journal of the Korea Convergence Society
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• v.9 no.3
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• pp.39-44
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• 2018

In this paper, we propose a monitoring method of smartphone to integrate IoT technology to monitor the state of the vehicle for fault diagnosis of E-Mobility power converter. In China, EV regulations are being implemented to promote technological development and market changes in electric vehicles. To meet this trend, E-Mobility should study suitable monitoring technology. The OBD-II method used in existing automobiles is a wired / wireless communication method. In order to apply it to E-Mobility, additional interface and communication link are required. In this paper, we propose a technology to monitor the status information of power converter for E-Mobility by combining existing technology with IoT. This technology simplifies the existing network protocol and hardware interface, and confirms that the E-Mobility power converter and smartphone can be interworked for easy user monitoring. And we have done research to make high value product design from the aspect of function.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.963-966
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• 2005

Recently, Ubiquitous Computing appeared to achieve service that is intelligence enemy without being courted in restriction that is time and space enemy based on developing computer network and Internet festinately. RFID (Radio Frequency Identification) technology that process information of tag that is attached in physical object by point technology that capacitate this Ubiquitous Computing through radio frequency identify is noted. Present RFID connection technologies are Auto-lD Lab and EPCglobal Inc. To center research for standardization progress. But, present RFID related researches connected with tag and leader are progressed vigorously and research about middleware or software description to service actuality tooth is insufficient misgovernment. In this treatise, therefore, characteristic of comparison and analyze about EPC network architecture proposed Auto-lD Lab and EPCglobal Inc. and conceptual application architectures had used existent application development and integration.

• Journal of Biosystems Engineering
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• v.27 no.2
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• pp.89-96
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• 2002

The trend of consumption of vegetable soybeans is increasing because they are recognized as the clean vegetable. The works requiring the most intensive labor are threshing and seperation ones, and they form about 80% of total labour for vegetable soybeans production. It is necessary to develop the vegetable soybeans-thresher for the sake of cost down of vegetable soybeans production. The purpose of this study is to acquire the basic informations to design of the vegetable soybeans-thresher. We make the experimental system which control the speed of threshing cylinder and the teeth gap and investigate the detachment forces. The result are as follows ; The ratio of un-threshed soybeans-pod to stem after threshing work is decreasing as the threshing cylinder speed increases: 0.0% and 2.8% at 55m/s and 18m/s of threshing cylinder speed respectively. Also the ratio of un-threshed soybeans-pod to stem is shown as 2.0% below in the condition of 64~160mm of teeth gap and over 28m/s of threshing cylinder speed. The damaged pod ratio of detached soybeans after threshing work is decreasing as the threshing cylinder speed increases: 4.8% and 1.3% at 55m/s and 18m/s of threshing cylinder speed respectively. The minimum damaged pod ratio of detached soybeans are shown as 1.0%, 1.5% and 1.9% at 18m/s, 28m/s and 37m/s of threshing cylinder speed respectively. The average detachment forces of pods are shown as 1.5kg$_{f}$ for 3 grains, 1.2kg$_{f}$ for 2 grains and 0.8kg$_{f}$ for 1 grain respectively. The maximum detachment force of pod is shown as 2.7kg$_{f}$ for 3 grains. grains.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.2
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• pp.185-192
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• 2014

Planetary gear design is complex because it involves a combination of discrete variables such as module, integer variables such as the number of teeth, and continuous variables such as face width and aspect ratio. Thus, an optimum design technique is needed. In this study, we applied a genetic algorithm to the design optimization of a planetary gear. In this algorithm, tooth root strength and surface durability are assessed with fundamental variables such as the number of teeth, module, pressure angle, and face width. With the help of this technique, gear designers could reduce trial and error in the initial design stages, thus cutting the time required for planetary gear design.