• The Journal of Korean Academy of Prosthodontics
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• v.41 no.2
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• pp.223-231
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• 2003

Statement of problem : Little is known about the effect of a counter-torque device and the internal hexagon of abutment on the tightening torque transmitted to the implant. Purpose : The purpose of this study was to examine the effect of a counter-torque device and the internal hexagon of abutment on the tightening torque transmitted to the implant. Material and Methods : In this study, three types of abutment were used, (1) two-piece conical abutment with hexagon, (2) two-piece conical abutment without hexagon, and (3) one-piece conical abutment without hexagon. The experimental groups were divided into five groups according to the type of abutment and the usage of a counter-torque device. Group I : two-piece conical abutment with internal hexagon was tightened without the use of a counter-torque device. Group II : two-piece conical abutment without internal hexagon was tightened without the use of a counter-torque device. Group III : one-piece conical abutment without internal hexagon was tightened without the use of a counter-torque device. Group IV : two-piece conical abutment with internal hexagon was tightened with the use of a counter-torque device Group V : two-piece conical abutment without internal hexagon was tightened with the use of a counter-torque device. Abutments were tightened 20Ncm torque with the use of manual torque wrench and then torque values were measured by torque-gauge. After the measurement of torque values, all groups were loosened with the use of manual torque wrench and then detorque values were measured by torque-gauge. Results : The results were as follows. 1. There were no differences in torque values among three types of abutment. 2. Regardless of the existence of the internal hexagon of abutment, a counter-torque device decreased the tightening torque transmitted to the implant about 92% 3. In group III showed the highest detorque value, however there were no differences among group I, II, IV and V. Conclusion : Within the limitations of this study, it was concluded that the internal hexagon of abutment has no effect on the tightening torque transmitted to the implant and the detorque value of abutment screw. The use of a counter-torque device is essential to prevent microfracture on the implant-bone interface but has no effect on preload.

• International Journal of Precision Engineering and Manufacturing-Green Technology
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• v.5 no.5
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• pp.571-581
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• 2018

In the present study, monitoring of elliptical vibration cutting process by utilizing internal data in the ultrasonic elliptical vibration device without external sensors such as a dynamometer and displacement sensor is investigated. The internal data utilized here is the change of excitation frequency, i.e. resonant frequency of the device, voltages applied to the piezoelectric actuators composing the device, and electric currents flowing through the actuators. These internal data change automatically in the elliptical vibration control system in order to keep a constant elliptical vibration against the change of the cutting process. Correlativity between the process and the internal data is described by using a vibration model of ultrasonic elliptical vibration cutting and verified by several experiments, i.e. planing and mirror surface finishing of hardened die steel carried out with single crystalline diamond tools. As a result, it is proved that it is possible to estimate the elements of elliptical vibration cutting process, e.g. tool wear and machining load, which are important for stable cutting in such precision machining.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.36 no.4
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• pp.255-261
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• 2010

Introduction: To evaluate the skeletal stability after a bilateral sagittal split osteotomy (BSSO) setback of the mandible fixed with a biodegradable internal fixation device or metal internal fixation device. Materials and Methods: Thirty consecutive patients underwent mandibular setback via BSSO. Fifteen patients were fixed with a biodegradable internal fixation device or metal internal fixation device respectively. Posteroanterior (PA) and lateral cephalograms were taken preoperatively and at two days, 5.5 months and 14.5 months postoperatively. The relevant skeletal points were traced and digitized to evaluate the skeletal changes postoperatively. The relapse rates were analyzed and compared statistically. Results: There was no statistically significant differences in postoperative stability between the two groups.(P<0.05) Conclusion: The biodegradable internal fixation device may make an effective device alternative to a metal internal fixation device for setback BSSO.

• Journal of Ocean Engineering and Technology
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• v.35 no.3
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• pp.216-228
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• 2021

In the present study, the performance of a floating oscillating water column (OWC) device has been studied in regular waves. The OWC model has the shape of a hollow cylinder. The linear potential theory is assumed, and a matched eigenfunction expansion method(MEEM) is applied for solving the diffraction and radiation problems. The radiation problem involves the radiation of waves by the heaving motion of a floating OWC device and the oscillating pressure in the air chamber. The characteristics of the exciting forces, hydrodynamic forces, flow rate, air pressure in the chamber, and heave motion response are investigated with various system parameters, such as the inner radius, draft of an OWC, and turbine constant. The efficiency of a floating OWC device is estimated in connection with the extracted wave power and capture width. Specifically, the piston-mode resonance in an internal fluid region plays an important role in the performance of a floating OWC device, along with the heave motion resonance. The developed prediction tool will help determine the various design parameters affecting the performance of a floating OWC device in waves.

• Korean Circulation Journal
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• v.53 no.7
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• pp.483-496
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• 2023

Background and Objectives: Atrial fibrillation (AF) is associated with decreased cardiac resynchronization therapy (CRT) benefits compared to sinus rhythm (SR). Effective biventricular (BiV) pacing is a determinant of CRT success, but AF can interfere with adequate BiV pacing and affect clinical outcomes. We investigated the effect of device-detected AF on clinical outcomes and optimal BiV pacing in patients with heart failure (HF) treated with CRT. Methods: We retrospectively analyzed 174 patients who underwent CRT implantation between 2012 and 2019 at a tertiary center. The optimal BiV pacing percentage was defined as ≥98%. Device-detected AF was defined as an atrial high-rate episode ≥180 beats per minute lasting more than 6 minutes during the follow-up period. We stratified the patients without preexisting AF at pre-implantation into device-detected AF and no-AF groups. Results: A total of 120 patients did not show preexisting AF at pre-implantation, and 54 had AF. Among these 120 patients, 19 (15.8%) showed device-detected AF during a median follow-up of 25.1 months. The proportion of optimal BiV pacing was significantly lower in the device-detected AF group than in the no-AF group (42.1% vs. 75.2%, p=0.009). The devicedetected AF group had a higher incidence of HF hospitalization, cardiovascular death, and all-cause death than the no-AF group. The device-detected AF and previous AF groups showed no significant differences regarding the percentage of BiV pacing and clinical outcomes. Conclusions: For HF patients implanted with CRT, device-detected AF was associated with lower optimal BiV pacing and worse clinical outcomes than no-AF.

• Nuclear Engineering and Technology
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• v.54 no.7
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• pp.2606-2613
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• 2022

Spent resin often exceeds radiation limits for safe disposal, creating a need for commercial-scale treatment techniques to reduce resin radioactivity. In this study, the radiological safety of a commercialized spent resin treatment device with a treatment capacity of 1 ton/day was evaluated. The results confirm that the device is radiologically safe in the event of an accident. This device desorbs ¹⁴C from the spent resin, allowing disposal as low-level waste instead of intermediate-level waste. The device also reduces overall waste by recycling the extracted ¹⁴C. Potential accident scenarios were explored to enable dose assessments for both internal and external exposure while preventing further spillage of the device and processing the spilled resin. The scenarios involved the development of a surface fracture on the resin mixture separator and microwave systems, which were operated under pressure and temperature of 0-6 bar and 0-150 ℃, respectively. In the case of accidents with separator and microwave device, the maximum allowable working time of worker were derived, respectively, considering external and internal exposures. When wearing the respirator corresponding to APF 50, in the case of the microwave device accident scenario, the radiological safety was confirmed when the maximum worker worked within 132.1 h.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.27 no.4
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• pp.324-333
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• 2005

Distraction osteogenesis for the advancement of hypoplastic maxilla of cleft patients has shown successful results. In this report, rigid external distraction(RED) system and internal distraction device were used for maxillary advancement. Each system has its advantages and disadvantages. Larger amount of advancement can be achieved with RED system. But complex external device may give patients psychological stress. Internal device is invisible. However its distraction amount have limitation for the advancement (< 20mm) and the vector cannot be changed freely during distraction. The authors treated five cleft patients with maxillary hypoplasia(three with RED system and two with internal distractor). Their results were clinically satisfactory. We present the pros and cons of RED and internal system for maxillary distraction osteogenesis.

• IMMUNE NETWORK
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• v.23 no.2
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• pp.18.1-18.15
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• 2023

It has been reported that some exercise could enhance the anti-viral antibody titers after vaccination including influenza and coronavirus disease 2019 vaccines. We developed SAT-008, a novel digital device, consists of physical activities and activities related to the autonomic nervous system. We assessed the feasibility of SAT-008 to boost host immunity after an influenza vaccination by a randomized, open-label, and controlled study on adults administered influenza vaccines in the previous year. Among 32 participants, the SAT-008 showed a significant increase in the anti-influenza antibody titers assessed by hemagglutination-inhibition test against antigen subtype B Yamagata lineage after 4 wk of vaccination and subtype B Victoria lineage after 12 wk (p<0.05). There was no difference in the antibody titers against subtype "A." The SAT-008 also showed significant increase in the plasma cytokine levels of IL-10, IL-1β, and IL-6 at weeks 4 and 12 after the vaccination (p<0.05). A new approach using the digital device may boost host immunity against virus via vaccine adjuvant-like effects.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.11
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• pp.898-903
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• 2001

In this study, we investigated amounts, distributions and sizes of pores of multilayer piezoelectric transformer, and predicted heat emission property and electrical characteristics according to designs of internal electrode. Forming densities of device having MLC, fingered and full filled internal electrode structure were 4.73 g/㎤, 4.80 g/㎤, 4.82 g/㎤ and forming porosities were 17.3737%, 13.1475%, 12.6121%, respectively. And sintered densities of MLC structured, fingered and full filled devices were 7.76 g/㎤, 7.75 g/㎤, 7.84 g/㎤ and sintered porosities were 4.0967%, 2.7132%, 2.5317%, respectively. Therefore, we concluded that fingered and full fi1led internal electrode devices, expecially, fingered internal electrode devices had cost-effective effect and maximum poling effect due to higher sintered density and lower porosity than MLC structured device. Also we can predict that they have an effect on good heat emission and high output properties of multilayer piezoelectric transformer.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.9
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• pp.75-79
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• 2011

The MOV(Metal Oxide Varistor), a voltage limiting element, has been installed in the SPD(Surge Protective Device) or inside the internal circuit of an electronic appliance for protection of the electric power system and electronic device against electrical surge. Such an MOV is exposed, however, to the risk of the thermal runaway resulting from excessive voltage and deterioration. In this paper, a reciprocal action has been tested and analyzed using a phosphorus bronze switching module and the low-temperature solder. And a short current break characteristic test linked with the circuit breaker has been performed to limit the inrush current when the MOV breaks down. It has been proven that the phosphorus bronze switching module installed inside the internal circuit can improve the safety of the power line system and the electronic device.