• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.05a
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• pp.87-90
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• 2004

In this paper, net-shape forming of an automobile gear is investigated. Barrel, a component of automobile start motor, is adopted as a net-shape forming. In order to accomplish the goal of net-shape forming without cutting of tooth and cam after forming, forming ability is raised through billet treatment and die design. As a technique of billet treatment spheroidizing annealing of billet to get low hardness and molybdenum disulphide coating to get low contact friction between billet and die is carried out. One of critical points of die design, fillet radii variation of tooth of die is applied to get smooth surface of barrel after cold forging. As a measurement of tooth accuracy, distance between two pins and lead-tooth alignments are investigated. Cam profile accuracy is checked with a 3D measuring instrument. Results obtained from the tests revealed reasonable result with respect to design goal. By these results, the paper shows that reasonable results can be obtained by billet treatment and die design for net-shape forming.

• Transactions of Materials Processing
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• v.28 no.4
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• pp.183-189
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• 2019

Cylindrical worm reducers are generally used in various fields and forms throughout the industry, and demand is increasing due to their role as an integral part of the industry. Market trends require high-load, high-precision components, and small-sized reducers with large loads. When using a cylindrical worm reducer, a reducer designed with a reduced center distance while maintaining the same output torque results in gear wear. To overcome this difficulty, an enveloping worm gear reducer is introduced and studied. In this paper, three types of end mill tools are used to evaluate the tooth profile accuracy for each tool shape during machining of the tooth profile for a non-developed surface worm thread. The effect of the endmill shape on the accuracy of the tooth profile was analyzed by performing 3D modeling of the surrounding worm tooth profile based on the Hindley method. In this study, we analyzed tooth profile accuracy, tooth surface roughness, and tooth surface machining time, etc. Through the study, efficient machining conditions for the enveloping worm gears and the influence of parameters on the process were presented.

• Transactions of Materials Processing
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• v.26 no.2
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• pp.95-100
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• 2017

In this study, the method of process design for side forming of a tooth part used for a component of automobile transmission was suggested using FE-simulations. To develop the side forming for the tooth part, in this paper, the shape factors of B.T.Pin was considered as design parameters. The shape factors of B.T.Pin were selected to be the round of pin, reinforced angle and reinforced length. Based on FE simulation results, appropriate shape factor without causing any defects was selected. In addition, to increase the strength of pin, the combination of shape factor having minimum stress after side forming was selected using FE-simulation. In addition, with design of a die set, cold side forming of the tooth part was experimented to estimate effectiveness of the designed B.T.Pin. From experiments, it was found that the tooth part with complete formation of the tooth was obtained without making any forming defects and punch fracture.

• The Journal of Advanced Prosthodontics
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• v.9 no.4
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• pp.315-320
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• 2017

PURPOSE. The aim of this investigation was to analyze the dimensions of clinical crowns and to classify the crown and the gingival type in the anterior teeth in Korean young adults. MATERIALS AND METHODS. Casts were obtained from 50 subjects ranging in age from 24 to 32. Measurements of length and width were made on the casts using a pair of digital calipers on the entire dentition. Crown thickness and papilla height were also measured and MDW/CL (mesiodistal width to clinical length) and CW/CL (cervical width to clinical length) ratios of the maxillary anterior teeth were calculated. The K-clustering method was used for CW/CL to classify the anterior tooth shape into three groups (tapered, ovoid, and square), and one-way analysis of variance and Duncan's post-hoc comparison were used to evaluate statistical significance between the groups. Pearson's correlation analysis was performed between tooth shape and papillary height (PH) to demonstrate the correlation between tooth shape and gingival morphological characteristics. RESULTS. The average length of the maxillary central incisors was 9.89 mm; the mesio-distal width was 8.54 mm; and the ratio of width/length was 0.86 in Korean young adults. The average bucco-palatal thickness of the central incisor was 3.14 mm at the incisal 1/3 aspect. Ovoid type was the most common tooth shape (48%), followed by square type (29%) and taper type (23%) in the central incisors of Korean young adults. Tooth shape and gingival type were correlated with each other. CONCLUSION. New reference data were established for tooth size in Korean young adults and the data show several patterns of tooth shape and gingival type. Clinicians should diagnose and treat based on these characteristics for better results in the Korean population.

• Journal of Magnetics
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• v.21 no.4
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• pp.570-576
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• 2016

The shape optimization of the stator and the rotor is important for electrical motor design. Among many motor design parameters, the stator tooth and yoke width are a few of the determinants of noload back-EMF and load torque. In this study, we proposed an equivalent magnetic circuit of motor stator for efficient stator tooth and yoke width shape optimization. Using the proposed equivalent magnetic circuit, we found the optimal tooth and yoke width for minimal magnetic resistance. To verify if load torque is truly maximized for the optimal tooth and yoke width indicated by the proposed method, we performed finite element analysis (FEA) to calculate load torque for different tooth and yoke widths. From the study, we confirmed reliability and usability of the proposed equivalent magnetic circuit.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.12 no.1
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• pp.72-77
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• 2003

The stable driving condition of high speed gear is approached by shape modifications of a gear tooth. Recently, many gear designers are using FEM for the design and the manufacture of a high precision gear. In this paper, it is aimed to drive in stable sound level through the modification of the tooth and the shape of a gear. The simulation is used to understand the effect of holes for the decrement of weight and the stress variation for the tooth modification. Beam elements used to simulate the same condition as a real gear drive by FEM. The driven gear is simulated to 60,000rpm for the tooth modification.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.34 no.4
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• pp.445-449
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• 2008

Unerupted or erupted supernumerary tooth may cause crowding, diastema, cyst formation, resorption, and displacement or rotation of adjacent teeth. However, there are few studies about prognosis about the pathologic condition and expectation of spontaneous eruption. The object of this study is to evaluate factors predicting the spontaneous eruption of supernumerary tooth. 431 patients (346 males and 85 females, aged from 5 to 29 years) who visited our institution from 2002-2006 and were shown to have 471 mesiodentes was reviewed. Supernumerary teeth were classified inverted and not inverted state. In case of not inverted supernumerary tooth, eruption rate ac cording to length of supernumenary tooth, width of the tooth, angle between the tooth and incisor tooth, location (inside the incisor or not) and shape (conical or tubercle) were investigated. The regression model showed that length, width and angle were all important determinants of influencing the eruption of supernumerary tooth (p < 0.001, Pearson R: 0.619). There is no relation between shape and eruption of supernumerary tooth (p > 0.05). Location of mesiodens has an effect on eruption of supernumerary tooth (p < 0.01).

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.857-862
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• 2009

In this study, the numerical study has carried out to analyze the leakage in a steam turbine labyrinth seal. We modified tooth shape of the labyrinth seal and finds out difference of leakage in this study. Original model is straight labyrinth seal and its modified model is slant labyrinth seal. The numerical analyses are implemented on two models. The numerical results show that each leakage of tooth shape are found 0.4781 kg/s and 0.4485 kg/s, respectively. Slant labyrinth seal seals in a steam better than straight labyrinth seal. Since, actual clearance of the stream function in the slant model is smaller than the straight model.

• Journal of Korean society of Dental Hygiene
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• v.11 no.4
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• pp.465-474
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• 2011

Objectives : The removal of most reliable mechanical dental plaque that is to say tooth brushing was generalized to control of dental plaque, many oral health goods have also developed due to the effect differences followed by individual habit. The electric toothbrush have studied and developed widely as major field of study that electric toothbrush having various moving phase was sold and developed at the market. Methods : Accordingly author studied about selling electric toothbrushes shape (vibration type, ultra-sonic minuteness vibration type, semi rotation type) to raise the efficiency after comparing to the moving them that total 8 groups classified by poor tooth models for example normal set of tooth, crowding tooth, bracket attached tooth, prosthetic status etc. and executed plaque removal effect on the tooth through comparing experiment. Results : The removal rate of artificial plaque on the tooth was improved in proportion to the increase of tooth brushing time(p<0.05). The ultra-sonic minuteness vibration and semi rotation type was superior to toothbrush of vibration type comparing to the removal rate of plaque on the tooth(p<0.05). Conclusions : The electric toothbrush of supersonic minuteness vibration and semi rotation type can be recommended most of tooth types regardless of oral tooth setting status for example, normal set of tooth, crowding tooth, bracket attached tooth, porcelain tooth.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.24 no.1
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• pp.39-46
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• 1994

The purpose of this study was to evaluate the prevalence and distribution according to the types of tooth shape anomalies in permanent teeth of 6,082 persons by means of analysis of the full mouth periapical radiographs. And the following results were obtained ; 1. Among tooth shape anomalies, the highest incidence was observed on dilaceration (20.14%), foll owed by dens invaginatus(3.02%), peg lateralis(1.48%), taurodontism (0.34%), dens evaginatus (0.33%), talon cusp(0.20%), fusion(0.07%) and gemination(0%) in descending order of frequency. 2. Peg lateralis, dens invaginatus and dilaceration occurred more prevalent in females, and other types of tooth shape anomalies occurred more prevalent in males. 3. Dens evaginatus and taurodontism occurred with bilateral tendency, but other anomalies occur- ed with unilateral tendency. 4. As to the involved teeth, maxillary lateral incisors were the most frequently involved teeth on peg lateralis, dens invaginatus and talon cusp. And the mandibular premolars were the most frequently involved teeth on dens evaginatus, the maxillary first molars were on taurodontism, the maxillary second premolars were on dilaceration, and the mandibular incisors and canines were on fusion.