• Proceedings of the KIEE Conference
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• 1993.11a
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• pp.135-138
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• 1993

The Modelling, design and analysis of the steady state and performance characteristic of the constant switching frequency P.W.M controlled LLC and LLCC-type P.R.C are presented continuous conduction mode of operation. A set of characteristic frequency are plotted which design parameters can be obtained.

• Journal of Magnetics
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• v.18 no.3
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• pp.317-320
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• 2013

We studied the polarization state in an apertureless scanning near-field microscopy (a-SNOM) operating in reflection mode by using three-dimensional Finite-difference Time-domain (FDTD) method. As a result, the electric field around tip apex in the near-field region enhanced four times stronger than the incident light for ppolarization when the tip-sample separation was 10 nm. We find that the p- and s-polarization state is maintained for the scattered light when the probe is perpendicular to the sample. When the probe is not perpendicular to the sample, the polarization state of scattered light will rotate an angle that equals to the inclination angle of probe with p-polarization illumination. On the other hand, the polarization state will not rotate with s-polarization illumination.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.105.3-105
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• 2001

In this paper, a current mode two-input maximum (Max) and minimum (Min) operations scheme, which is a useful building block for analog fuzzy inference systems, is presented. The Max and Min operations are incorporated in the same scheme with parallel processing. The proposed scheme comprises a MOS class AB/B configuration and current mirrors. Its simple structure can provide a high efficiency. The performance of the scheme exhibits a very sharp transfer characteristic and high accuracy. The proposed scheme achieves a high-speed operation and is suitable for real-time systems. The simulation results verifying the performances of the scheme are agreed with the expected values.

• Science of Emotion and Sensibility
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• v.27 no.2
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• pp.81-90
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• 2024

In this study, we aimed to determine the effect on cerebral blood vessels of various stimulus intensities using transcutaneous electrical nerve stimulation (TENS). In particular, we wanted to monitor changes in blood flow and structural changes in the blood vessels in the common carotid artery (CCA) through low-intensity electrical stimulation that can cause non-perceptual sensory stimulation. Twenty-four healthy adults in their 20s participated in this study. Three stimulus intensities (below the sensory threshold, at the sensory threshold, and above the sensory threshold) were applied in random order. Changes in blood flow velocity according to the intensity of TENS stimulus were measured by placing the Doppler ultrasound transducer 1 cm below the CCA bifurcation, and the vascular structure was measured using B-mode imaging. C-mode Doppler and B-mode images were acquired before, during, and after the intervention for each stimulus, and changes in blood pressure were measured in each session. As a result, it was confirmed that peak systolic velocity (PSV) decreased significantly after the intervention in non-perceived sensory stimulation below the threshold, compared to other thresholds (p = .008). In particular, the PSV decreased by 3.04% on average compared to before stimulation (p = .011). However, there was no significant change in the CCA diameters before and after stimulation at all intensities. It was found that short-term, non-perceptual sensory stimulation was effective in reducing the blood flow rate without causing significant changes in either the blood vessel diameter or blood pressure. This change appears to be caused by a decrease in blood flow due to the effect of subtle vasodilation at non-perceptual sensory stimulation, and at stimulation intensity higher than that, the sympathetic nerves in the blood vessels are stimulated excessively and the blood vessels constrict. Therefore, this study can be rated as an important attempt to control blood flow through stimulation without such a psychological burden and sensory discomfort in the carotid area.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.12
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• pp.38-44
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• 2002

A walking training robot is proposed to provide stable and comfortable walking supports by reducing body weight load partially and a force control of an arm of walking training robot using sliding mode controller is also proposed. The current gait training apparatus in hospital are ineffective for the difficulty in keeping constant unloading level and for the constraint of patients' free walking. The proposed walking training robot effectively unloads body weight during walking. The walking training robot consists of an unloading manipulator and a mobile platform. The manipulator driven by an electro-mechanical linear mechanism unloads body weight in various levels. The mobile platform is wheel type, which allows patients to walt freely. The developed unloading system has advantages such as low noise level, lightweight, low manufacturing cost and low power consumption. A system model fur the manipulator is established using Lagrange's equation. To unload the weight of the patients, sliding mode control with p-control is adopted. Both control responses with a weight and human walking control responses are analyzed through experimental implementation to demonstrate performance characteristics of the proposed force controller.

• IEMEK Journal of Embedded Systems and Applications
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• v.15 no.5
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• pp.215-225
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• 2020

Light detection and ranging (LiDAR) sensors detect the distance of the surrounding environment and objects. Conventional LiDAR sensors require a certain amount of a power because they detect objects by transmitting lasers at a regular interval depending on a constant resolution. The constant power consumption from operating multiple LiDAR sensors is detrimental to autonomous and electric vehicles using battery power. In this paper, we propose two algorithms that improve the inefficient power consumption during the constant operation of LiDAR sensors. LiDAR sensors with algorithms efficiently reduce the power consumption in two ways: (a) controlling the resolution to vary the laser transmission period (T_P) of a laser diode (LD) depending on the vehicle's speed and (b) reducing the static power consumption using a sleep mode depending on the surrounding environment. A proposed LiDAR sensor with a resolution control algorithm reduces the power consumption of the LD by 6.92% to 32.43% depending on the vehicle's speed, compared to the maximum number of laser transmissions (N_x·max). The sleep mode with a surrounding environment-sensing algorithm reduces the power consumption by 61.09%. The proposed LiDAR sensor has a risk factor for 4-cycles that does not detect objects in the sleep mode, but we consider it to be negligible because it immediately switches to an active mode when a change in surrounding conditions occurs. The proposed LiDAR sensor was tested on a commercial processor chip with the algorithm controlling the resolution according to the vehicle's speed and the surrounding environment.

• KSBB Journal
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• v.8 no.4
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• pp.341-350
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• 1993

As an effort to develop an alternative transportation fuel, the production of methanol from methane gas was studied using the resting cells of an obligatory methanotroph, Methylosinus trichosporium OB3b. The reaction was carried out in high concentration phosphate buffer solutions with the flask-grown cells containing the exclusively cytoplasmic methane monooxygenase (sMMO) activity. The methanol accumulation rate was observed to be 79nmo1/mg·min during the initial 4.5hr. Phosphate-dependent inhibition was found for both sMMO and methanol dehydrogenase (MDH) activities, and the inhibition constants were 185mM and 42mM, respectively. The inhibition mode was noncompetitive. Methanol was found to be very inhibitory to the sMMO activity and the inhibition constant (noncompetitive) was 21mM when propylene was used as substrate. The sMO activity in the resting cells was declined very fast and the rate became very high during the methanol production. These results indicate that the use of M. trichosporium OB3b as a biocatalyst for the methanol production is heavily dependent on the stable maintenance of the whole-cell SMO activity as well as the effective alleviation of product inhibition.

• The Journal of Advanced Prosthodontics
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• v.3 no.2
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• pp.90-95
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• 2011

PURPOSE. To compare the fracture resistance and the mode of failure of endodontically treated teeth restored with different post-core systems. MATERIALS AND METHODS. Root canal treatment was performed on 40 maxillary incisors and the samples were divided into four groups of 10 each. For three experimental groups post space preparation was done and teeth were restored with cast post-core (Group B), stainless steel post with composite core (Group C) and glass fiber post with composite core using adhesive resin cement (Group D). Control group (A) samples were selected with intact coronal structure. All the samples were prepared for ideal abutment preparation. All the samples were subjected to a load of 0.5 mm/min at $130^{circ}$.until fracture occurred using the universal testing machine. The fracture resistance was measured and the data were analyzed statistically. The fracture above the embedded resin was considered to be favorable and the fracture below the level was considered as unfavorable. The statistical analysis of fracture resistance between different groups was carried out with t-test. For the mode of failure the statistical analysis was carried out by Kruskal-Wallis test and Chi-Square test. RESULTS. For experimental group Vs control group the fracture resistance values showed significant differences (P<.05). For the mode of failure the chi-square value is 16.1610, which means highly significant (P=.0009) statistically. CONCLUSION. Endodontically treated teeth without post core system showed the least fracture resistance demonstrating the need to reinforce the tooth. Stainless steel post with composite core showed the highest fracture resistance among all the experimental groups. Teeth restored with the Glass fiber post showed the most favorable fractures making them more amenable to the re-treatment.

• Journal of Dental Rehabilitation and Applied Science
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• v.18 no.2
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• pp.101-111
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• 2002

The purpose of this study was to evaluate the fracture strength of porcelain fused to gold crown and gold electroformed crown according to incisal and incisal under 3mm. In this study, 28 gold electroformed crown and 28 porcelain fused to gold crown were fabricated. Fracture strength testing was carried out using an Instron 8871(Instron Corporation, U.S.A) at a cross head speed of 5mm/min. All of the measurements were statistically analyzed by Independent t-testing, and k-s testing. Statistical significance was set in advance at the probability level of less than 0.05. All measurements were analized with Windows $SPSS^{(R)}$ Version 10.0 software for the personal computer. The results of this study were as follows; 1. Comparison by location (1) A compared fracture strength of incisal and incisal under 3 mm, there was statistical significant difference between gold electro -formed crown and porcelain fused to gold crown (p<0.05). 2. Comparison by loading (1) When compared fracture strength of incisal, there was no significant difference between gold electroformed crown ($619.90{\pm}53.54N$)and porcelain fused to gold crown($674.68{\pm}87.42N$). (2) When compared fracture strength of incisal under 3 mm, there was significant difference between gold electroformed crown($688.29{\pm}14.88N$) and porcelain fused to gold crown($1931.81{\pm}29.64N$) (p<0.05). 3. Mode of fracture When compared of fracture mode, gold electroformed crown showed mode of fracture and fracture line reaching coping region and porcelain fused to gold crown showed only in porcelain region.

• The Journal of Advanced Prosthodontics
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• v.8 no.6
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• pp.489-493
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• 2016

PURPOSE. This in-vitro study aimed to evaluate the fracture resistances and failure modes of endodontically treated mandibular premolars restored with endocrowns and conventional post-core retained crowns. MATERIALS AND METHODS. Thirty mandibular premolars were assigned into three groups (n=10): GI, intact teeth; GE, teeth with endocrowns; GC, teeth with conventional post-core supported crowns. Except for the teeth in group GI, all specimens were cut to 1.5 mm above the cementoenamel junction and endodontically treated. Both endocrowns and conventional crowns were fabricated from lithium-disilicate blocks using a CEREC 3D CAD/CAM unit. All specimens were subjected to thermocycling and then to $45^{\circ}$ oblique compressive load until fracture occurred. The fracture resistance and failure mode of each specimen were recorded. Data were analyzed with one-way ANOVA and LSD Post Hoc Test (${\alpha}=.05$). RESULTS. The fracture resistances of GE and GC were significantly lower than that of GI (P<.01), while no significant difference was found between GE and GC (P=.702). As of the failure mode, most of the specimens in GE and GC were unfavorable while a higher occurrence of favorable failure mode was presented in GI. CONCLUSION. For the restoration of mandibular premolar, endocrown shows no advantage in fracture resistance when compared with the conventional method. Both of the two methods cannot rehabilitate endodontically treated teeth with the same fracture resistances that intact mandibular premolars have.