• Journal of Advanced Marine Engineering and Technology
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• v.24 no.3
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• pp.79-87
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• 2000

This paper describes experimental investigations of helium-air exchange flow through openings with vertical partitions. Such exchange flows may occur following rupture accident of stand pipe in high temperature gas cooled reactor. Exchange flow rates are investigated experimentally by using partitioned opening and opening with extended partition to assess fluids interference of the exchange flow at the stand pipe rupture accident. A tests vessel with the two types of opening on top of test cylinder is used in the experiments. An estimation method of mass increment is developed and applied to measure the exchange flow rate. A technique of flow visualization by Mach-Zehnder interferometer is provided to recognize the exchange flows. Amplitude and progress of interference fringes of the flows are observed and used as a support in comparison with the exchange flow rates. Flow passages of upward flow of the helium and downward flow of the air for both two types of the opening are separated by inserted partition within the opening, but in the case of partitioned opening, unseparated flow is formed at the opening entrance and the two flows interface. The exchange flow rate for the partitioned opening is not greater than that of the opening with extended partition because of the fluids interference at the entrance of opening. Finally, the fluids interference at the opening entrance is found to be one of important factors on the helium-air exchange flow rate.

• Journal of the Korea Safety Management & Science
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• v.16 no.4
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• pp.305-311
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• 2014

Recently, though it was developed several services using the context-awareness technology of IoT, there exist also obstacles for high quality service. Specifically it is short the study for uncertainty of context-awareness. This study focused on understanding the effect of frequency interference among several environmental factors for location determination to increase precision of location determination. It was found that frequency interference between devices using 2.4Ghz frequency effect on the location determination precision. It was resulted that frequency interference increase the error of location determination precision. Then, we confirmed that it was required the suitable compensation method corresponding to frequency interference.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.1
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• pp.18-34
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• 2014

It is widely believed that cognitive radio (CR) networks have an opportunistic nature and therefore can only support best-effort traffics without quality-of-service (QoS) guarantees. In this paper, we propose a centralized CR network that adopts interference averaging techniques to support QoS guaranteed traffics under interference outage constraints. In such a CR network, a CR user adaptively adjusts its transmit power to compensate for the channel loss, thereby keeping the receive signal power at the CR base station (BS) at a constant level. The closed-form system capacity of such a CR network is analyzed and derived for a single cell with one CR BS and multiple CR users, taking into account various key factors such as interference outage constraints, channel fading, cell radius, and locations of primary users. The accuracy of the theoretical results is validated by Monte Carlo simulations. Numerical and simulation results show promising capacity potential for deploying QoS-guaranteed CR networks in frequency bands with fixed primary receivers. Our work can provide theoretical guidelines for the strategic planning of centralized CR networks.

• Journal of Mechanical Science and Technology
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• v.19 no.11
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• pp.1988-1997
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• 2005

This study is concerned with structural integrity evaluations for the interference-fit flywheels in reactor coolant pumps (RCPs) of nuclear power plants. Stresses in the flywheel due to the shrinkage loads and centrifugal loads at the RCP normal operation speed, design overspeed and joint-release speed are obtained using the finite element method (FEM), where release of the deformation-controlled stresses as a result of structural interactions during rotation is considered. Fracture mechanics evaluations for a series of cracks assumed to exist in the flywheel are conducted, considering ductile (fatigue) and non-ductile fracture, and stress intensity factors are obtained for the cracks using the finite element alternating method (FEAM). From analysis results, it is found that fatigue crack growth rates calculated are negligible for smaller cracks. Meanwhile, the material resistance to non-ductile fracture in terms of the critical stress intensity factor (K$_{IC}$) and the nil-ductility transition reference temperature (RT$_{NDT}$) are governing factors for larger cracks.

• Journal of Korea Multimedia Society
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• v.16 no.5
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• pp.601-609
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• 2013

One of the most serious factors constraining the next generation cellular mobile consumer communication systems will be the severe co-channel interference experienced at the cell edge. Such a capacity-degrading impairment combined with the limited available spectrum resource makes it essential to develop more spectrally efficient solutions to enhance the system performance and enrich the mobile user's application services. This paper proposes a unique hybrid method of frequency hopping (FH) and subcarrier-reuse-partitioning that can maximize the system capacity by efficiently utilizing the available spectrum while at the same time reduce the co-channel interference effect. The main feature of the proposed method is that it applies an optimal combination of different frequency reuse factors (FRF) and FH-subcarrier allocation patterns into the partitioned cell regions. From the simulation results, it is shown that the proposed method can achieve the optimum number of subcarrier subsets according to the frequency-reuse distance and results in better performance than the fixed FRF methods, for a given partitioning arrangement. The results are presented in the context of both blocking probability and BER performances. It will also be shown how the proposed scheme is well suited to FH-OFDMA based cellular systems aiming at low co-channel interference performance and optimized number of subcarriers.

• Journal of Dental Rehabilitation and Applied Science
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• v.21 no.1
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• pp.43-57
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• 2005

Temporomandibular disorders have been defined as a collective term embracing a number of clinical problems that involve the temporomandibular joint, the masticatory nuscles, and associated structures. There have been many different contributing factors of TMDs which were traumatic, occlusal, pathophysiological and psychosocial. Among there factors, the effect of occlusion on TMDs have been a controversy for a long time. The purpose of this study was to investigate the effect of occlusal factors and oral habits on TMDs. In this study, 140 subjects with signs and symptoms of TMDs and diagnosed of TMD in the Orofacial Pain clinic of Yonsei University Dental Hospital though March to July 2004 were selected for the TMDs group and 50 subjects without any signs and symptoms of TMDs as the control group. The subjects were evaluated clinically in TMDs' Occlusal and Prosthodontic Restoration examinations. TMDs' examination was composed of the TMJ pain, sound, locking, temporal or masseter muscle palpation, mandibular movement, oral habits and headache. Occlusal examination was made of overjet, overbite, lost teeth number, nonfunctional interference, midline shift, then pattern of lateral movement and attrition. prosthodontic restoration examination had the existence of restoration, placement, then number of crown or bridge and Satisfiable index which estimated the quality of occlusal state of prosthodontic restorations. Following results were obtained : 1. The prevalence of TMDs was higher in their 20s & 30s, female of the TMD patients group. 2. The clenching frequency in the TMDs group(40.71%) was higher than those in the control group(18.00%), and there was a significant statistical difference(p<0.05). 3. The frequency of Nonfunctional interference in the TMDs group(10.00%) was higher than those in then Control group(2.00%), and there was a significant statistical difference(p<0.05). The result of this study indicated TMDs prevalence was higher in their 20s, 30s, female group of TMDs patients similar to the previous studies. Clenching and nonfunctional interference were estimated as the contributing factors of TMDs.

• Journal of Oral Medicine and Pain
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• v.44 no.3
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• pp.92-102
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• 2019

Purpose: To investigate the masticatory function of patients with different temporomandibular disorders (TMD) phenotypes, and to explore the risk factors for the masticatory function of TMD patients among multiple biopsychosocial variables using patient-reported outcomes (PROs). Methods: Clinical features and TMD diagnoses of 250 cases were investigated by reviewing medical records. Psychosocial factors were evaluated using four questionnaires representing pain severity and pain interference (Brief Pain Inventory), pain catastrophizing (Pain Catastrophizing Scale, PCS), psychological distress (Symptom Check List-90-Revised, SCL-90R) and kinesiophobia (Tampa Scale for Kinesiophobia for Temporomandibular Disorders, TSK-TMD). Masticatory function, as a dependent variable, was determined using the Jaw Functional Limitation Scale (JFLS). Kruskal-Wallis test and Spearman's rank correlation were used for analyses. Results: A total of 145 cases were included and classified into four subgroups including group 1: TMD with internal derangement without pain (n=14), group 2: TMD with muscle pain (n=32), group 3: TMD with joint pain (n=60) and group 4: TMD with muscle-joint combined pain (n=39). Pain severity (p=0.001) and interference (p=0.022) were the highest in group 2, but the mean global score of JFLS was the highest in group 3, followed by group 4, group 2, and group 1 (p=0.013). Pain severity, pain interference, the mean global score of PCS and the mean global score of TSK-TMD showed significant and moderate correlation with the mean global score of JFLS. All subdimensions and the global severity index of SCL-90R had significant, but weak correlations with all scores of JFLS. Conclusions: The results suggest that masticatory functional limitation depends on the TMD phenotypes. Among the various PROs, pain perception, pain catastrophizing and kinesiophobia seem to be more influential risk factors on jaw function than psychological distress, such as depression and anxiety.

• Nuclear Engineering and Technology
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• v.55 no.12
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• pp.4570-4575
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• 2023

Noise and Radio-frequency interference or RFI causes a significant restriction on the Free induction Decay or FID signal detection of the Nuclear Quadrupole Resonance procedure. Therefore, using this method in non-isolated environments such as industry and ports requires extraordinary measures. For this purpose, noise reduction algorithms and increasing signal-to-noise-and-interference ratio or SNIR have been used. In this research, sodium nitrite has been used as a sample and algorithms have been tested in a non-isolated environment. The resonant frequencies for the 150 g of test sample were measured at 303 K at about 1 MHz and 3.4 MHz. The main novelty in this study was, (1) using two types of antennas in the receiver to improve adaptive noise and interference cancellation, (2) using a separate helical antenna in the transmitter to eliminate the duplexer, (3) estimating the noise before sending the pulse to calculate the weighting factors and reduce the noise by adaptive noise cancellation, (3) reject the interference by blanking algorithm, (4) pulse integration in the frequency domain to increase the SNR, and (5) increasing the detection speed by new pulse integration technique. By interference rejection and noise cancellation, the SNIR is improved to 9.24 dB at 1 MHz and to 7.28 dB at 3.4 MHz, and by pulse integration 44.8 dB FID signal amplification is achieved, and the FID signals are detected at 1.057 MHz and 3.402 MHz at room temperature.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2015.11a
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• pp.172-173
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• 2015

Construction project involves numerous repetitive operations. Especially in high-rise and apartment houses projects, the amount of repetitive operations increase and a preceding operations delay causes serious damage to the total duration of the project. This study deducts work delay factors by site engineer interview and survey. The study analyzes daily report data to deduct crucial processes affecting masonry work which has been investigated to be one of preliminary processes conducted at the beginning of finish work.

• 한국연소학회:학술대회논문집
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• 2005.10a
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• pp.314-319
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• 2005

In this study, the combustion characteristics were investigated with the variation of design factors on multiple slit gas burner. The design factors consist of slit height, width, spacing, and inner length. The combustion characteristics were made analysis of the CO emission and NOx emission by using CO analyzer and NOx analyzer. The lower perimeter to area and the narrow spacing extends the lift-flame limit. The CO emission increases with the increasing perimeter to area ratio at the same condition. The NOx emission is found to be less significant with the port perimeter to area ratio. The flame interference might highly depend on the spacing and port perimeter to area ratio, and it also affects the burner performance.