• Journal of Dental Rehabilitation and Applied Science
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• v.36 no.1
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• pp.1-11
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• 2020

Purpose: The purpose was to compare shear bond strength (SBS) of three types of resin for temporary restoration to polyetherketoneketone (PEKK) depending on surface modification. Materials and Methods: Sixty disks made from PEKK were air-abraded with 110 ㎛ alumina particles (Cobra, Renfert GmbH, Hilzinge, Germany) and thirty specimens were divided into two groups each: PEKK without Visio.link (Bredent, Senden, Germany)(U) and with Visio.link (P). Resins for temporary restoration (polymethylmethacrylate; PMMA, polyethylmethacrylate; PEMA, bis-acryl composite resin) in the shape of a square with one side 3.2 mm were bonded to PEKK twenty respectively and classified into six groups (UM, UE, UC, PM, PE and PC). All specimens were stored in distilled water at 37℃ for 24 hours. SBS of each group was measured at a crosshead speed of 2 mm/min in universal testing machine. SBS was compared using one-way ANOVA and a Tukey HSD test (P = 0.05). Results: Group UM and group UE showed a significant difference in SBS with group UC (P < 0.05). Group PC showed a significant increase in SBS than group UC (P < 0.05). Conclusion: It is recommended to apply Visio.link to PEKK for adhering bis-acrylic composite resin, but not for PMMA and PEMA in clinical practice.

• Journal of Veterinary Clinics
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• v.27 no.6
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• pp.740-745
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• 2010

Patent ductus arteiosus (PDA) is the persistent opening of ductus arterious located between pulmonary artery and descending aorta after birth. Although PDA can be occluded by surgical ligation, interventional closure of PDA using various devices is being rapidly replaced to surgical ligation, because of its non-invasive nature of treatment and minimal post-care after treatment. Main problem encountering in interventional treatment in toy breed dogs is vascular inaccessibility due to small size of artery. Although transvenous approach using jugular veins has been developed, this technique requires experienced skill to locate occlude devices into PDA and has high risk of accidental dislodgement of occluding devices (i.e. embolization coils or vascular plugs). Therefore, in this study, we developed a modified technique for coil embolization using mini-angiocatheter with trans-femoral approach in toy breed dogs (< 3.0 kg of body weight). With this modified method, we were successfully treated two toy breed (Maltese) dogs with the left to right shunted PDA.

• International journal of advanced smart convergence
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• v.6 no.2
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• pp.51-58
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• 2017

Recently, rapid advances of Ethernet and IP technology have brought many changes in the sound industry. In addition, due to AoIP-based audio transmission technology, various problems of the acoustic system (sound quality deterioration due to long distance transmission, complicated wiring) have improved dramatically. However, when many distributed audio systems are connected with AoIP equipment, if there is a problem in the equipment, it is impossible to operate the connected system. AoIP equipment only can transmit audio signals but cannot adjust the system for acoustic environment. In this paper, AoIP equipment is to be installed with sound equipment on a one-to-one basis, so that various existing problems can be solved and adjustment of sound quality (reverberation, echo, delay and EQ) can be possible by AoIP-based OAC (On-site Audio Center) with built-in DSP function. As a result, uncompressed real-time transmission by distributed transmission/receipt module in OAC (On-site Audio Center) and high quality sound by adjustment of sound quality with built-in DSP can be acquired. It is expected that OAC based sound system will be the industry standard in ubiquitous environment.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05b
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• pp.379-384
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• 1996

Thermal-hydraulic performance has been analyzed for an advanced reactor core loaded with hexagonal fuel assemblies. Currently available CHF prediction models and data base for triangular lattice bundles have been thoroughly reviewed, and as a result the KfK-3 CHF correlation with limit CHFR of 1.235 has been determined to be most appropriate. The pressure drop model in COBRA-IV-I code has been modified for the analysis of triangular lattice rod bundles. In view of maximizing the thermal margin, the geometry of a hexagonal fuel assembly, such as rod diameter and rod pitch, has been optimized with a fixed fuel assembly cross sectional area The optimum value of the moderator-to-fuel volume ratio is estimated to lie between 0.65 to 1 with 9.5 mm rod diameter. The thermal margin of these hexagonal fuel assemblies in the AP600 core has been evaluated and compared with that of square lattice fuel assemblies such as VANTAGE-5H and KOFA. The analysis result shows that the performances of hexagonal fuel assemblies are more favorable than the square fuel assemblies in the aspect of steady-state overpower margin.

• Nuclear Engineering and Technology
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• v.22 no.2
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• pp.95-100
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• 1990

The exact expression for the 1151 force on a fuel assembly in a reactor core is derived in terms of calculable hydraulic parameters. The relation for the lift force. pressure drop, buoyancy force, viscous force. and fuel assembly weight is discussed. Based on the derived exact expression. error analysis is made for a simple expression applying COBRA IV-i to a typical PWR fuel assembly. The error analysis revealed that the error of the simple expression consists of four terms and the overall error depends on the flow rate change direction, and its magnitude is about 1%.

• Nuclear Engineering and Technology
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• v.33 no.3
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• pp.283-297
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• 2001

The CHF in PWR rod bundles is usually predicted by the local flow correlation approach based on subchannel analysis while difficulty exists due to the existence of spacer grids especially with mixing vanes. In order to evaluate the effect of spacer grids on CHF, the experimental rod bundle data with various types of spacer grids were analyzed using the subchannel code, COBRA-IV-i. For the Plain grid data, a CHF correlation was described as a function of local flow conditions and heated length, and then the residuals of the CHF in mixing vaned grids predicted by the correlation were examined in various kinds of grids. In order to compensate for the residual, three parameters, distances between grids and from the last grids to the CHF site, and equivalent hydraulic diameter were introduced into a grid parameter function representing the remaining effect of spacer grids predicted most of the CHF data points in plaing grids within $\pm$20 percent error band. Good agreement with the CHF data was also shown when the grid parameter function for mixing vaned grids of a specific design was used to compensate for the residuals of the CHF data predicted by the correlation.

• Physical Therapy Korea
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• v.20 no.3
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• pp.27-35
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• 2013

The aim of this study was to compare the electromyographic (EMG) activity levels of the scapular upward rotators [upper trapezius (UT), lower trapezius (LT), and serratus anterior (SA)] and other scapular muscles [posterior deltoid (PD), levator scapulae (LS), and infraspinatus (IS)] during isometric lower trapezius exercises. Twenty males with no medical history of shoulder pain or upper extremity disorders were recruited for this study. EMG activity was recorded from the UT, LT, SA, PD, LS, and IS while subjects performed three different exercises: Prone arm lift (PAL), Backward rocking diagonal arm lift (BRDAL), Modified Prone Cobra (MPC). One-way analysis of variance (ANOVA) was used to determine any significant differences among the three exercises. A lower relative activation of UT, LT, and SA was seen with the MPC than with the other exercises (p<.05). The relatively lower activation of the UT identified, the MPC exercise as the preferred choice for preferential strengthening the LT (p<.05). However, a higher activation in the PD, LS, and IS occurred with the MPC than with the other exercises (p>.05). The recruitment pattern of synergist varied depending on the exercise posture. These findings suggest that exercise posture is an important factor in the selection of strengthening exercise for weak muscle.

• Proceedings of the Korean Nuclear Society Conference
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• 1997.10a
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• pp.534-539
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• 1997

A CHF table method has been assessed in this study for rod bundle CHF predictions. At the conceptual design stage for a new reactor, a general critical heat flux (CHF) prediction method with a wide applicable range and reasonable accuracy is essential to the thermal-hydraulic design and safety analysis. In many aspects, a CHF table method (i.e., the use of a round tube CHF table with appropriate bundle correction factors) can be a promising way to fulfill this need. So the assessment of the CHF table method has been performed with the bundle CHF data relevant to pressurized water reactors (PWRs). For comparison purposes, W-3R and EPRI-1 were also applied to the same data base. Data analysis has been conducted with the subchannel code COBRA-IV-I. The CHF table method shows the best predictions based on the direct substitution method. Improvements of the bundle correction factors, especially for the spacer grid and cold wall effects, are desirable for better predictions. Though the present assessment is somewhat limited in both fuel geometries and operating conditions, the CHF table method clearly shows potential to be a general CHF predictor.

• Restorative Dentistry and Endodontics
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• v.19 no.1
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• pp.106-113
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• 1994

Dental professions are considered high risk for contracting hepatitis infection. In Korea, many patients are hepatitis B virus carriers. HBV are most efficiently transmitted by blood. Root canal treatment, as in cases of acute pulpitis always accompanied by contaminated blood. Therefore it is absolutely necessary to use irrigation solutions having strong antiviral effect for prophylaxis both dental personnel and patients. The purpose of this study was to investigate the antiviral effect of seven root canal irrigation solutions by radioimmunometric test. The solutions were 5% sodium phyochlorite, 5% cresol, 2% glutaraldehyde, 3% hydrogen peroxide, 0.05% chlorohexidine, 10% iodine, and 70% isoprophyl alcohol. Each irrigation solutions was mixed with serum preparated from HBsAg positive patients and sera were diluted to 1:1. 1:4. 1:20 and 1:100. Percentage of radioactivity was assayed with AUK(Sorbin biomedica, Italy) and COBRA(Packwood Instrument company, USA). Sodium hypochlorite and glutaraldehyde showed most strong antivral activity against HBsAg. Isoprophyl alcohol had moderate antiviral effect and the effect and the effect was increased especially in 1:4 solution. Hydrogen peroxide exihibited very weak aintivral activity. Cresol, chlorohexidine, and iodine exhibited little antiviral activity.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.19 no.2
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• pp.205-214
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• 2021

Currently, the interim storage pools of spent fuels in South Korea are expected to become saturated from 2024. It is required to prepare an operation plan of a domestic dry storage facility during a long-term period, with the researches on safety evaluation methods. This study modified the FRAPCON code to predict the spent fuel integrity evaluation such as the axial cladding temperature, the hoop stress and hydrogen distribution in dry storage. The cladding temperature in dry storage was calculated using the COBRA-SFS code with the burnup information which was calculated using the FRAPCON code. The hoop stress was calculated using the ideal gas equation with spent fuel information such as rod internal pressure. Numerical analysis method was used to calculate the degree of hydrogen diffusion according to the hydrogen concentration and temperature distribution during a dry storage period. Before 50 years of dry storage, the cladding temperature and hoop stress decreased rapidly. However, after 50 years, they decreased gradually and the cladding temperature was below 400 K. The initial temperature distribution and hydrogen concentration showed a parabolic line, but hydrogen was transferred by the hydrogen concentration and temperature gradient over time.