• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.30 no.2
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• pp.71-77
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• 2016

The dielectric barrier discharge (DBD) has low efficiency due to about 70% input power is consumed as thermal energy in the discharge space. However, because of the usage of DBD ozone generator is easier than other methods. The DBD ozone generator has been widely applied for high concentration ozone generation in the industrial application. But, the low-capacity compact DBD ozone generator is not applied so far. Therefore, the DBD ozone generator is necessary to improve ozone production efficiency and reduce the capacity. In this paper, the stainless steel pipe inner electrode was designed with hall type and screw type to improve the ozone production yield. The manufactured two inner electrodes were experimented with normal type for comparison of the discharge characteristics and the ozone generating characteristics. As the experimental results, the discharge current effective value of designed inner electrodes with hall type and screw type are higher than the normal type, due to unequal electric field is formed at the boundary. However, the difference of designed and original electrodes is less than 0.1mA that has no effect on the discharge characteristic. On the other hand, the screw type inner electrode increased higher than original model about 7 times when the flow rate of the oxygen source gas was increased from $0.6{\ell}/min$ to $1.0{\ell}/min$ The reason was assumed by the flow rate of the raw gas through the inner electrode was became fast that has a cooling effect. The designed hall type and screw type inner electrodes have shown good performances in ozone generation and ozone production that better than normal type in the same electrode surface area.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2006.05a
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• pp.295-299
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• 2006

The inner-structure bonded(ISB) sheet metal is defined as a composite sheet metal which has middle layer of truss-structure between two skin sheets. The characteristics such as ultra-light weight, high rigidity, high strength, etc are required especially for automobile parts. The characteristic of ISB sheet metal depends on inner-structure pattern or method of bonding. Pyramid type of crimped expanded metal is used for inner-structure and both of resistance welding and adhesive bonding are applied to make a specimen. As a result of compression test, it is appeared that forming limit is 10% reduction in thickness under a load of 8kgf per unit element(one inner-structure). In case of uniaxial tensile test the non-uniform surface integrity rather than the buckling of inner-structure happened at a load of 450kgf, which indicates elongation of 7.2% and thickness reduction of 13%. The eye-inspection method was applied to examine the defects occurring on the specimen during stretch forming. In case of biaxial stretch forming only the non-uniform deformation on the surface of a skin sheet could be observed. The forming limit in stretching of ISB sheet metal with the hemi-spherical punch of 150mm in diameter was 3mm in forming depth and 5% reduction in thickness.

• International Journal of Industrial Entomology and Biomaterials
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• v.18 no.2
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• pp.77-82
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• 2009

The egg shell of the tropical tasar silkworm, Antheraea mylitta is formed from the substances secreted by the follicular epithelium during the late vitellogenic stage. TEM study reveals the inner travecular and outer lamellar layer of chorion. The travecular layer is composed of the innermost wax layer, inner and outer chorionic layer. The inner and outer chorionic layers are connected to each other by vertical pillers forming of cavities. The lamellar layer is perforated by the aeropyles. SEM study reveals the differentiation of an anterior surface of the egg shell into four zones-micropylar, edge, aeropyles crown and disc zone. In the mycosis infected eggs the aeropyles and egg-shell surface are fully packed with the hyphae of the fungus, Aspergillus sydowi blocking of plastron respiration and causing the death of developing embryo so that mycosis infected eggs become sterile.

• Journal of Environmental Science International
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• v.19 no.9
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• pp.1093-1101
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• 2010

In this study, the indirect correlation of degradation characteristic and flow behavior in the de-NOx catalyst is investigated experimentally. The inner flow behavior in the de-NOx catalyst is varied from turbulent flow to laminar flow and the degradation of the de-NOx catalyst is remarkably affected by the inner flow. The degradation of the catalyst is increased in the upstream region near the inlet because injected turbulent flow enhances the adhesion of ash particle on the catalyst surface. The degradation of the catalyst near the inlet also governs the overall efficiency of the catalyst. The amount of adhered ash particles on the catalyst surface decreases as they progress downstream. This is due to the inner flow transition from turbulent flow to laminar flow.

• Journal of the Korean Society of Safety
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• v.12 no.2
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• pp.22-26
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• 1997

A small scale centrifugal oil separator consisted of two concentric tubes was fabricated for spilt oil recovery. With speed control of the inner tube, its performance of oil separation was investigated. Oil-water mixture is separated by forced vortex motion with the rotating inner tube. Velocity and pressure distributions in the tubes were calculated. Control of rotating speed, which is the most influencing parameter, showed an optimum value 946rpm corresponding to the acceleration of 20g at the inner tube surface. Separation performance was suddenly deteriorated at rotating speed higher than 1200rpm.

• Journal of Advanced Marine Engineering and Technology
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• v.10 no.2
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• pp.156-164
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• 1986

In the case of boiling on high temperature wall, vapor film covers fully or parcially the surface. This phenomenon, film boiling or transition boiling, is very important in the surface heat treatment of metal, design of cryogenic heat exchanger and emergency cooling of nuclear reactor. Mainly supposed hydraulic-thermal accidents in nuclear reactor are LCCA (Loss of Coolant Accident) and PCM (Power-Cooling Mismatch). Recently, world-wide studies on reflooding of high temperature rod bundles after the occurrence of the above accidents focus attention on wall temperature history and required time in transient cooling process, wall superheat at rewet point, heat flux-wall superheat relationship beyond the transition boiling region, and two-phase flow state near the surface. It is considered that the further systematical study in this field will be in need in spite of the previous results in ref. (2), (3), (4). The paper is the study about the fast transient cooling process following the wall temperature excursion under the CHF (Critical Heat Flux) condition in a forced convective subcooled boiling system. The test section is a vertically arranged concentric annulus of 800 mm long and 10 mm hydraulic diameter. The inner tube, SUS 304 of 400 mm long, 8 mm I.D, and 7 mm O.D., is heated uniformly by the low voltage AC power. The wall temperature measurements were performed at the axial distance from the inlet of the heating tube, z=390 mm. 6 chromel- alumel thermocouples of 76 .mu.m were press fitted to the inner surface of the heating tube periphery. To investigate the heat transfer characteristics during the fast transient cooling process, the outer surface (fluid side) temperature and the surface heat flux are computed from the measured inner surface temperature history by means of a numerical method for inverse problems of transient heat conduction. Present cooling (boiling) curve is sufficiently compared with the previous results.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.6
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• pp.409-415
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• 2016

In this study, we test the effects of the surface roughness on the hydro efficiency of double-suction centrifugal pumps ($Q=70.7m^3/min$, H = 87 m). The original surface of the impeller and inner casing were coated, resulting in surface-roughness reductions ranging from $100{\sim}110{\mu}m$ to $0{\sim}0.08{\mu}m$. We conducted experimental studies to measure the efficiency of the pumps and operating-pump electro energy variations with different surface roughness values. The experimental results showed that the efficiency of the pumps increased by about 0.8~1.79% and the electric energy of the operating pump was reduced by around 4.38 ~ 6.08%. These results indicate that the performance of the pumps depend largely on the surface roughness of the impeller and inner casing, and by reducing the surface roughness, we can improve the efficiency of the pump and reduce costs by reducing the electric energy consumption.

• The Journal of Advanced Prosthodontics
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• v.9 no.4
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• pp.252-256
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• 2017

PURPOSE. This in vitro study aimed to analyze and compare the reproducibility of zirconia and lithium disilicate crowns manufactured by digital workflow. MATERIALS AND METHODS. A typodont model with a prepped upper first molar was set in a phantom head, and a digital impression was obtained with a video intraoral scanner (CEREC Omnicam; Sirona GmbH), from which a single crown was designed and manufactured with CAD/CAM into a zirconia crown and lithium disilicate crown (n=12). Reproducibility of each crown was quantitatively retrieved by superimposing the digitized data of the crown in 3D inspection software, and differences were graphically mapped in color. Areas with large differences were analyzed with digital microscopy. Mean quadratic deviations (RMS) quantitatively obtained from each ceramic group were statistically analyzed with Student's t-test (${\alpha}=.05$). RESULTS. The RMS value of lithium disilicate crown was $29.2\;(4.1){\mu}m$ and $17.6\;(5.5){\mu}m$ on the outer and inner surfaces, respectively, whereas these values were $18.6\;(2.0){\mu}m$ and $20.6\;(5.1){\mu}m$ for the zirconia crown. Reproducibility of zirconia and lithium disilicate crowns had a statistically significant difference only on the outer surface (P<.001). The outer surface of lithium disilicate crown showed over-contouring on the buccal surface and under-contouring on the inner occlusal surface. The outer surface of zirconia crown showed both over- and under-contouring on the buccal surface, and the inner surface showed under-contouring in the marginal areas. CONCLUSION. Restoration manufacturing by digital workflow will enhance the reproducibility of zirconia single crowns more than that of lithium disilicate single crowns.

• Journal of Korean Dental Science
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• v.17 no.1
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• pp.36-44
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• 2024

Purpose: This study investigated the effect of dentin bonding agent acidity on surface microhardness of MTA. Materials and Methods: Forty cylindrical molds (3 mm×5 mm) were prepared, and three dentin bonding agents with different acidities: Adper Single Bond 2 (ASB), Single Bond Universal (SBU), and Clearfil SE bond 2 (CSE) were applied to the inner surface of the molds (n=10). No bonding agent was applied in the control group. MTA was mixed and inserted into the molds and sealed with a wet cotton pellet for 4 days. After setting, the Vickers microhardness (HV) test was done at 200, 400, 600 ㎛ from the inner surface of the mold. One-way ANOVA was conducted for all samples. A P-value of less than .05 was considered significant. Tukey HSD test was performed for post-hoc analysis. Results: The mean HV values and standard deviations were 67.02±11.38 (Con), 48.76±11.33 (ASB), 43.78±11.19 (CSE), 37.84±9.36 (SBU), respectively. The difference between the control group and the experimental groups was statistically significant (P<0.001). The difference between ASB and SBU was statistically significant (P<0.001), while the difference between SBU and CSE was not. There were no statistically significant differences between the various points from the inner surface of the mold within each group (P>0.05). Conclusion: Results of the current study indicate that use of dentin bonding agents with MTA can reduce the surface microhardness of MTA. Moreover, there is a direct relationship between the acidity of dentin bonding agents and the surface microhardness of MTA.

• Journal of the korean Society of Automotive Engineers
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• v.15 no.3
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• pp.89-95
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• 1993

This paper presents the development of CAD system for the design of lens of the Turn Signal Lamp that can model and simulate its optical performance. The system consists of three main modules: skin surface modeling module, inner lens modeling module and optical performance simulation module. Skin surface geometry can be modeled by the input of data file and inner lens can be modeled by the input of only four parameter using its geometric characteristics. Also light distribution pattern, the barometer of optical performance is generated by means of finite ray tracing method. The system display modeled geometry, ray tracing and generated light distribution pattern.