• Restorative Dentistry and Endodontics
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• v.29 no.5
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• pp.413-422
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• 2004

Established microleakage tests have their own disadvantages. In this study, 3D reconstruction method was tried to overcome these disadvantages. Four types of microleakage tests were used and relationships among them were estimated: penetrated dye volume: marginal adaptability: degree of dye penetration and relative penetrated length to cavity wall. Twenty-four Class V cavities were bulk filled with composite (Esthet X) following surface treatments: N group (no treatment): E group (etching only): T group (etching + Prime & Bond NT). 50% silver nitrate was used as a dye solution after thermocycling ($5^{\circ}C{\;}&{\;}55^{\circ}C$, 1.000 times). Teeth were serially ground with a thickness of 0.2 mm. Volume of dye penetration was estimated from a three-dimensionally reconstructed image with a software (3D-DOCTOR). Percentage of margin without gap was estimated from SEM and degree of dye penetration and the relative length of dye penetration to overall cavity wall were also estimated. ANOVA and Scheffe test for dye volume, Kruskal-Wallis and Mann-Whitney test for marginal quality, Spearman's rho test for checking of relationships among methods were used. The results were as follows: 1. Dye penetration could be seen from several directions, furthermore, its volumetric estimation was possible. 2. Reverse relationship was found between dye volume and marginal quality (r = -0.881/ p = 0.004). 3. Very low relationship was seen between dye volume and two-dimensional tests (degree of dye penetration and relative length). However, 2D evaluation methods showed high relationship (p = 0.002-0.054) each other. 4. Three times vertical section could be recommended as a 2D test.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.1
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• pp.81-88
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• 2011

This paper presents a design of spiral antenna with broad bandwidth for non-linear junction detector(NLJD). An elliptical patch as radiating element located on center position of radiating surface, as well as the spiral elements on radiating surface was designed for broad bandwidth of spiral antenna. An antenna ground structure generating the multi resonance by spiral slit inserted on ground surface was also proposed. In order to realize high directivity and high gain of the proposed antenna, the cavity wall made of Fr4-epoxy and the metal cap were considered in design. As a result, the calculated gain of antenna with metal cap was improved about 3 dB with comparison of antenna without metal cap and the measured main beam directivity toward -z axis direction agreed well with calculation result. The measured axial ratio satisfied the circular polarization within -z axis ${\pm}45^{\circ}$ at design frequency bands and showed reasonable agreement with prediction.

• Restorative Dentistry and Endodontics
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• v.26 no.4
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• pp.316-325
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• 2001

The purpose of this study was to evaluate the effect of adhesive curing timing on the direction of polymerization shrinkage of light-curing composite resin. In this study, the curing times of adhesive and composite resin were measured by differential scanning calorimeter(DSC). 28 extracted human molars were embedded in clear resin and box-type cavities were prepared. Based on DSC data, the experimental teeth were divided into 4 groups. Group 1: no bond; Group 2: late curing; Group 3: Intermediate curing; Group 4: Early curing. After treating with adhesive, the buccal cavities were filled with Z-100 hybrid composite resin and the lingual ones were filled with AEliteflo flowable composite resin. The depressions at the surface were measured by surface profilometer, then the specimens were embedded in clear resin and sectioned. Impressions were obtained and used to get epoxy resin replicas. The epoxy replicas were gold-coated and observed under SEM. Average Maximum Gap(AMG), Gap Proportion(GP), Average Marginal Index(AMI) were used to compare the shrinkage gap of each group. The results were statistically analyzed using the Kruskal-Wallis One Way ANOVA, Student-Newman-Keuls method. The results of this study were as follows. 1. Average Maximum Gap, Gap Proportion, Average Marginal Index and depression at the surface or Z-100 hybride composite resin were smaller than those of AEliteflo flowable composite resin(P<0.05). 2. When the bonding between composite resin and tooth structure was strong, the shrinkage gap was small, and depression at the surface was deep(P<0.05). 3. In the well-bonded group, light-curing composite resin shrank toward bonded cavity wall, not toward light source. The result suggested that the direction of polymerization shrinkage was affected by the quality of bonding in the dentin-resin interface. The strong was the bonding between composite resin and tooth structure, the smaller was the gap and the deeper was the depression at the surface. Then the flow to compensate the polymerization shrinkage proceeded from surface to bonded cavity wall.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.1
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• pp.36-46
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• 2013

This paper proposes the design of broadband spiral antenna for a potable non-linear junction detector (NLJD) system. To realize the broadband antenna design, it was considered optimization of the number of spiral turns by iteration calculation. Ground plane with the Archimedean spiral slit to keep the same current distribution between radiating plane and ground is considered for circular polarization design. In order to realize high directivity and high gain of the proposed antenna, the cavity wall and the metal cap which is located on back of ground plane were also considered in design. Measurement results of return loss were agreed well with VSWR 2:1 at interested frequency band among 2.4 to 2.44 GHz, 4.84 to 4.92 GHz and 7.28 to 7.36 GHz. Measured axial ratio was observed 3 dB below and showed reasonable agreement with simulation results. Characteristics of the RHCP(Right Hand Circular Polarization) with the measured gain of 6.8 dBi above at interested frequency band were also observed.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.11
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• pp.103-108
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• 2019

The cooling rate and the uniformity of mold temperature, in the injection molding process, possess great influences on the productivity and quality of replications. The conformal cooling channel, which is of a uniform spacing from the mold cavity by the metal additive manufacturing process, receives much attention recently. The purpose of this study is to develop a mold core with a curved conformal cooling channel for a pottery-shaped thick-wall cosmetic container through the hybrid method of direct metal tooling (DMT) process. In this study, we design a mold core that contains the curved cooling channel for the container. A method that divides the cavity is proposed and the DMT process is carried out to form the curved cooling channel. The test mold core, with the curved conformal cooling channel, has been fabricated by the proposed method to confirm the feasibility of the design concept. We show that no leakage is observed for the additive manufactured test mold core, and its physical properties demonstrate that it can be sufficiently used as the injection mold core.

• 한국태양에너지학회:학술대회논문집
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• 2008.11a
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• pp.226-231
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• 2008

The heat transfer characteristics of a solar high-temperature receiver with heat pipes was investigated by numerical simulation. The concentration ratio of the solar receiver ranges 1000 and the concentrated heat is required to be transported to a certain distance for specific applications. This study deals with internal geometry variation of a solar receiver incorporating high-temperature heat pipe. The isothermal characteristics in the receiver section is of major concern. The diameter of the solar thermal receiver was 120 mm and the length was 400 mm. The angle of receiver end wall was varied between $0^{\circ}$ and $45^{\circ}$. The wall thickness of the heat pipe channel was 4mm and 48 axial channels of the same dimensions were attached to the outer wall of the receiver with even spacing in the circumferential direction. The channels are changed to high-temperature sodium heat pipes. Commercial softwares were employed to deal with the radiative heat transfer inside the receiver cavity and the conduction heat transfer along the channels. The numerical results are compared and analyzed from the view Point of high-temperature solar receiver.

• Tuberculosis and Respiratory Diseases
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• v.48 no.1
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• pp.84-90
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• 2000

The appearance of a tumor in the chest wall is rare compared to that in any other part of the body. It can be classified into benign and malignant types and can be located in the rib, clavicle, sternum, cartilage and soft tissues. Tumors that are metastatic are commonly located in the lung, breast, bone and pleura. But, the soft tissue mass of anterior chest wall is rarely metastasized from a distant organ that is not confined to the thoracic cavity. This and thus has rarely been described. A 68-year-old man was admitted to our hospital with a chief complaint of resting dyspnea. A huge non-tender mass of about $10{\times}15$ cm in size was visible on his left lower anterior chest wall. We pathologically confirmed that the mass was a metastatic renal cell carcinoma of clear cell type by incision biopsy. Through an incision biopsy, the mass was pathologically confirmed as a metastatic renal cell carcinoma of the clear cell type.

• Restorative Dentistry and Endodontics
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• v.17 no.1
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• pp.222-234
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• 1992

The purpose of this study was to evaluate the systemic and local production of immunoglobulins and their levels in patients with periapical cysts using Enzyme - Linked Immunosorbent Assay. Streptococcus sanguis, Bacteroides gingivalis, and Bacteroides intermedius were grown for use as antigen and they were harvested by centrifugation. The patients were divided into two groups: patients of periapical cysts and normal control. 5 patients of each group were selected and their blood were obtained via intravenous puncture prior to surgical operation. Sera were prepared by centrifugation of each blood samples. Cyst fluid were aspirated from cystic cavity and cyst wall were excised at operation. Control tissue were also excised at extraction site of impacted wisdom teeth from normal control. Each tissue was prepared by homogenization and centrifugation. Then antibodies of each sample were measured by modified ELISA. The following results were obtained: 1. Serum IgG and IgM levels were not significantly different between patients with periapical cyst and normal control. 2. IgG and IgM levels of cyst fluid to Bacteroides gingivalis and Bacteroides intermedius were significantly higher than those of serum of patients with periapical cyst, but there was no significant difference to Streptococcus sanguis. 3. IgG and IgM levels of cyst wall to Bacteroides gingivalis and Bacteroides intermedius were significantly higher than those of control tissue, but there was no significant difference to Streptococcus sanguis. 4. IgG and IgM levels in cyst fluid and IgG levels in cyst wall were highest to Bacteroides gingivalis, and IgM levels in cyst wall were highest to Bacteroides intermedius.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.5 s.120
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• pp.496-502
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• 2007

In this paper, a slotted waveguide feeder for the electric field uniformity in multi-mode cavity is designed and fabricated. In case of the conventional feeder, a mode stirrer or a turntable is used for improving electric field uniformity in the multi-mode cavity. The proposed feeder has four slots, which have uniform radiation characteristic, on broad wall and shorted terminations at both ends. The electric field uniformity is simulated by CST's MWS(Microwave Studio) for the conventional and proposed feeders, respectively. The fabricated feeder shows the return loss of less than -20 dB at 2.45 GHz. To verify the validity of our proposal, the temperature distribution of the water samples in the multi- mode cavity is observed after a few minutes' heating. The proposed feeder is confirmed to have much better field uniformity in the multi-mode cavity than the conventional feeder.

• Advances in aircraft and spacecraft science
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• v.7 no.5
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• pp.425-440
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• 2020

The work presented herein is a numerical investigation of the flow field inside a resonant igniter, with the aim of predicting the performances in terms of cavity temperature and noise spectrum. A resonance ignition system represens an attractive solution for the ignition of liquid rocket engines in space missions which require multiple engine re-ignitions, like for example debris removal. Furthermore, the current trend in avoiding toxic propellants leads to the adoption of green propellant which does not show hypergolic properties and so the presence of a reliable ignition system becomes fundamental. Resonant igniters are attractive for in-space thrusters due to the low weight and the absence of an electric power source. However, their performances are strongly influenced by several geometrical and environmental parameters. This motivates the study proposed in this work in which the flow field inside a resonant igniter is numerically investigated. The unsteady compressible Reynolds Averaged Navier-Stokes equations are solved by means of a finite volume scheme and the effects of several wall boundary conditions are investigated (adiabatic, isothermal, radiating). The results are compared with some available experimental data in terms of cavity temperature and noise spectrum.