• Journal of Multimedia Information System
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• v.5 no.2
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• pp.143-146
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• 2018

The eigen value problem of a coaxial cavity and a modified pill box cavity is investigated using the mode matching technique. The coaxial cavity has a cylindrical cavity with beam ports and center conductor. The pill box cavity is the same as a coaxial cavity without center conductor. The electric field and magnetic field are formulated in propagation region and resonance region. The boundary and orthogonal conditions are applied to the electric and magnetic fields. We derived the eigen value equation by the proposed procedure in a coaxial cavity and a modified pill box cavity. The electromagnetic field of the real structure is disturbed by the coaxial wire. The effect of the coaxial wire in pill box cavity with beam ports increase the dominant resonant frequency. The coaxial line method of the coupling impedance is not adequate for a cylindrical cavity. The results of the mode matching technique and simulation agree well. The results confirm the proposed formulation is valid.

• The Journal of the Korean dental association
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• v.36 no.2 s.345
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• pp.144-150
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• 1998

The dental insurance had been enforced in Korea past 20 years. The major part of the insurance was filling, and the filling was divided into two parts-the cavity preparation and cavity filling, The Cavity filling was estimated into 6 levels according to the cavity types. But the tooth cavity preparations was not evaluated by the cavity types but merely only one-the one visit filling or cavity preparation. Korean dentists tend to turn away from the amalgam to the non-insurance treatments. The purpose of this study was to relate the cavity preparations and cavity fillings to the cavity types. So I measured the real time and surveyed the relative difficulties of cavity preparations from the 31 dentists according to the cavity types, who had been trained in conservative dentistry. The conclusion of this study was below. 1. The estimations of tooth cavity preparation was divided same as the cavity filling. 2. There must be reasonable considerations about the times and difficulties in cavity preparation. 3. There was differences between the premolars and molars, upper jaw and lower one. 4. Two or more cavities in one tooth must be evaluated according to the number of cavities, not in one cavity.

• Journal of the korean academy of Pediatric Dentistry
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• v.8 no.1
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• pp.103-117
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• 1981

The data about dental caries obtained from 1438 preschool children (male 797, female 641) in Seoul aged from 3 to 6 were analyzed by their sexes, ages, jaws and teeth surfaces. The results were as follows. 1. dmf rate : 92.63% 2. dmft index : 6.06 dmft rate 30.81 % dmfs index : 11.82 dmfs rate 12.02 % 3. d,m & f rate d rate: 79.45% m rate: 8.15% f rate : 12.40 % 4. dft index : 5.94 5. The order of caries susceptible tooth 1. Lower deciduous 2nd molar 2. Lower deciduous 1st molar 3. Upper deciduous 2nd molar 4. Upper deciduous lateral incisor 5. Upper deciduous cental incisor 6. Upper deciduous lateral incisor 7. Lower deciduous canine 8. Upper deciduous canine 9. Lower deciduous central incisor 10. Lower deciduous lateral incisor 6. Predilection sites of each tooth A) Deciduous central incisor ; Max. : Mesial cavity Mand. : Mesio-distal cavity B) Decidous lateral incisor ; Max. : Mesial cavity Mand. : Distal cavity=Mesial cavity C) Deciduous canine; Max. : Labial cavity Mand. : Distal cavity D) Decidous 1st molar ; Max. : Disto-occlusal cavity Mand.: Disto-occlusal cavity E) Deciduous 2nd molar ; Max. : Linguo-occlusal cavity Mand.: Occlusal cavity 7. All the values in caries criteria in 1981 were somewhat lower than in 1968, but m & f rate were increased.

• Korean Journal of Animal Reproduction
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• v.18 no.4
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• pp.245-250
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• 1995

The appearance and function of corpora lutea(CL) with a central cavity in the ovaries of Korean Native Cattle (KNC) were investigated endocrinologically and histochemically. The CL were enucleated from KNC ovaries within 2~3 hrs local slaughter house and classified with central cavity CL or not. Enzymatically dispersed luteal cell (1$\times$106 live cell/ml of Dulbecco's Modified Eagle Media) with or without cavity of CL cultured at 37$^{\circ}C$ in a humidified incubation (5% CO2 : 95% air) for 72hr. A central cavity in the CL of KNC was found in 58.8% of CL-1, 34.9% of CL 2, 39.1% of CL-3, and 11.1% of CL-4, respectively. There were no significant difference between protein content of CL with and without a central cavity. Mean progesterone secretion after 36h of in vitro luteal cell culture were significantly (p<0.05) higher in CL with central cavity than without cavity. However, the luteal cavitic wall was composed of the connective tissue band of the reticular and collagen fibers and then these connective tissue band extended into the CL with cavity. These results suggest that the central cavity of CL may be caused infertility in KNC.

• Restorative Dentistry and Endodontics
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• v.29 no.6
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• pp.515-519
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• 2004

Straight access cavity design allows the operator to locate all canals, helps in proper cleaning and shaping, ultimately facilitates the obturation of the canal system. However, change in the fracture strength according to the access cavity designs was not clearly demonstrated yet. The purpose of this study was to determine the influence of different access cavity designs on the fracture strength in endodontically treated mandibular anterior teeth. Recently extracted mandibular anterior teeth that have no caries, cervical abrasion, and fracture were divided into three groups (Group 1 : conventional lingual access cavity, Group 2 : straight access cavity, Group 3 : extended straight access cavity) according to the cavity designs. After conventional endodontic treatment, cavities were filled with resin core material. Compressive loads parallel to the long axis of the teeth were applied at a crosshead speed of 2mm/min until the fracture occurred. The fracture strength analyzed with ANOV A and the Scheffe test at the 95% confidence level. The results of this study were as follows: 1. The mean fracture strength decrease in following sequence Group 1 (4558.90{\;}\pm{\;}77.40{\;}N$), Group 2 ($494.07{\;}\pm{\;}123.98{\;}N) and Group 3 ($267.33{\;}\pm{\;}27.02{\;}N). 2. There was significant difference between Group 3 and other groups (P = 0.00). Considering advantage of direct access to apical third and results of this study, straight access cavity is recommended for access cavity form of the mandibular anterior teeth.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.9
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• pp.3815-3821
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• 2012

The LCD frame is an important part which supports the BLU of medium/large sized TFT-LCD. To produce it efficiently, it is necessary to achieve the molding process improvement from 1 cavity to 2 cavity system. Because 2 cavity mold is compact and its hot-runner zone is broadened, it is difficult to control the temperature on the mold. In this study, injection molding analysis on the frame in 2 cavity process with FEA(Finite Element Analysis) software is carried out to estimate its quality. The calculated injection molding pressures and maximum deflection in 1 and 2 cavity processes are 41.13 MPa and 1.62 mm, 40.49 MPa and 1.66 mm respectively. The measured maximum flexure load and surface roughness of the left and right frame of 2 cavities are 209 N and 0.08 ${\mu}m$, 193 N and 0.10 ${\mu}m$ while those in 1 cavity are 140 N and 0.13 ${\mu}m$. Thermal image shows that the maximum standard deviation of the temperature on left and right side of 2 cavity mold is $1.23^{\circ}C$. The simulation and measurement results show that the quality of the frame in 2 cavity injection molding process as a whole is not worse than that of 1 cavity system. But maximum flexure loads of the frame in 2 cavity process are far greater than that in 1 cavity process.

• 유체기계공업학회:학술대회논문집
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• 2004.12a
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• pp.629-634
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• 2004

Cavities are inevitable structures in automobile configuration. The flow-induced noise is generated from the wheel housing section by the interaction between a rotating wheel and the unsteady flows in the cavity. In this research the wheel housing was assumed by a rectangular cavity for simplification. We measured the radiated sound from the 2-D cavity without cylinder and from the rotating cylinder in the cavity by using the sound source localization method with an acoustic mirror system. In the 2-D cavity case of low Mach number(Ma=0.029), the sound sources were found to be located near the leading edge of cavity due to the shear layer instabilities. Comparing the cases of the rotating and the non-rotating cylinder, it is observed that the sound Pressure levels around the rotating cylinder in the cavity increased and the main acoustic sources were located at the rear section of the rotating wheel.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.38 no.11
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• pp.55-62
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• 2001

Field penetration and scattering characteristics of two dimensional open cylindrical cavity is studied. Exact analysis for this sort of structure is not achieved even if there are unusual phenomena of field penetration and scattering with cavity and aperture size. In this paper, we calculate a wide range of open cavity characteristics by using of FMM method, which is extended method of MOM. We find external mode of open cylindrical cavity corresponding to internal mode of closed cavity. The characteristics of resonance and scattering of this region is different compare with non resonant area. The result of study will apply to the EM wave shielding and RCS control.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.12
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• pp.1241-1248
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• 2004

This paper presents an acoustic source localization technique on 2D cavity model in flow using a phased microphone array. Investigation was performed on cavity flows of open and closed types. The source distributions on 2D cavity flow were investigated in an anechoic open-jet wind tunnel. The array of microphones was placed outside the flow to measure the far field acoustic signals. The optimum sensor placement was decided by varying the relative location of the microphones to improve the spatial resolution. Pressure transducers were flush-mounted on the cavity surface to measure the near-filed pressures. It is shown that the propagated far field acoustic pressures are closely correlated to the near-field pressures and their spectral contents are affected by the cavity parameter L/D.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.701-708
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• 2003

This paper presents an acoustic source localization technique on 2D cavity model in flow using a phased microphone way. Investigation was performed on cavity flows of open and closed types. The source distributions on 2D cavity flow were investigated in anechoic open-jet wind tunnel. The array of microphones was placed outside the flow to measure the far field acoustic signals. The optimum sensor placement was decided by varying the relative location of the microphones to improve the spatial resolution. Pressure transducers were flush-mounted on the cavity surface to measure the near-filed pressures. It is shown that the propagated far field acoustic pressures are closely correlated to the near-field pressures. It is also shown that their spectral contents are affected by the cavity parameter L/D.