• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.269-270
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• 2006

Brake noise is classified according to frequency territory: judder, groan and squeal. Squeal noise of disk brake is a noise and self excited vibration with frequency of $1{\sim}10Khz$ caused by the friction force between the disk and the pad of the automobile. Passengers in a vehicle feel uncomfortable. It causes unstable characteristic to the brake system when you try to stop the vehicle. Thus this study aims to find in which conditions the vehicles are stable during the braking hour and find ways to decrease a squeal noise and the vibration by measuring various factors including squeal noise and self excited vibration between the pad and disk brake system during the braking hour. From the result the countermeasure for a squeal noise and a vibration decrease is established. Also the analyzed data is found to be useful and can be applied to the actual brake model.

• Journal of Korean Society on Water Environment
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• v.23 no.1
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• pp.33-37
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• 2007

Microelectrodes for measuring nitrogenous compounds (${NH_4}^+$, ${NO_3}^-$) that were applied into the microfluidics chips was investigated, and the effect of temperature was especially examined. In this specific research, microelectrodes were first calibrated to check the function, and then microsensor that was combined microelectrode with microfluidic chip was re-calibrated. Experimental results showed that there are no change in the function between microelectrode and microfluidic chip. The electro motive force (EMF) for the ${NH_4}^+$ microsensor was similar to the one theoretically calculated from Nernst equation, but the EMF for ${NO_3}^-$ showed minor change.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.1 s.106
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• pp.50-56
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• 2006

Since most of small form-factor drives have a load/unload mechanism and the flying height of the head is getting lower as the capacity of disk drives increases, the load/unload velocity becomes one of the important factors to ensure the reliability of the load/unload mechanism. To control the load/unload velocity accurately, velocity sensing is essential. In this paper, we introduce a very practical method that acquires the load/unload velocity from the back electromotive force (BEMF) of a voice coil motor (VCM) and propose a calibration method for measuring the BEMF from a given circuit. Moreover, the effect of calibration error and temperature variation on the measurement of BEMF is shown by simulation. Then, this present method is applied to the load/unload velocity controller and is verified from the experimental result.

• Korean Medical Education Review
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• v.22 no.1
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• pp.9-15
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• 2020

Currently, accreditation within medical education is a priority on the agenda for many countries worldwide. The World Federation for Medical Education's (WFME) launch of its first trilogy of standards in 2003 was a seminal event in promoting accreditation within basic medical education (BME) globally. Parallel to that, WFME also actively spearheaded a project to recognize the accrediting agencies within individual countries. The introduction of competency-based medical education (CBME) with the two key concepts of "entrusted professional activity" and milestones has enabled researchers to identify the relationship between patient outcomes and medical education. Recent data driven by CBME has been used for the continuous quality improvement of trainees and training programmes as well. The goal of accreditation has shifted from the single purpose of quality assurance to balancing quality assurance and quality improvement. Even though there are a plethora of types of postgraduate medical education (PGME), it may be possible to accredit resident programmes on a global scale by adopting the concept of CBME. In addition, the alignment of the accreditation for BME and PGME, which center on competency, will be achievable. This argument may extend the possibility of measuring the outcomes of the accreditation itself against patient outcomes as well. Therefore, evidence of the advantages of costly and labor-consuming accreditation processes will be available in the near future and quality improvement will be the driving force of the accreditation process.

• International Journal of Aeronautical and Space Sciences
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• v.17 no.2
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• pp.139-148
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• 2016

The passive control methods such as horizontal and vertical fences on the lower surface of the bluff body were applied to suppress the vortex shedding and enhance the aerodynamic stability of flow. For investigating the effects of the passive control methods, wind tunnel experiments on the unsteady flow field around a bluff body near a moving ground were performed. The boundary layer and velocity profiles were measured by the Hot Wire Anemometer (HWA) system and the vortex shedding patterns and flow structures in a wake region were visualized via the Particle Image Velocimetry (PIV) system. Also, it is a measuring on moving ground condition that the experimental values of the critical gap distances, Strouhal numbers and aerodynamic force FFT analyses. Through the experiments, we found that the momentum supply due to moving ground caused the vortex shedding at the lower critical gap distance rather than that of fixed ground. The horizontal and vertical fences increase the critical gap distance and it can suppress the vortex shedding. Consequently, the stability characteristics of the bluff body near a moving ground could be effectively enhanced by the simple passive control such as the vertical fences.

• Journal of Oral Medicine and Pain
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• v.5 no.1
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• pp.5-10
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• 1980

Numerous investigators have pointed out that the force of the tongue against the teeth within the dental arches is normally compensated for by the action of the musculature of the cheeks and lips, and that the tongue at rest occupies a large part of the oral cavity. The purpose of this study was to estimate the maximum areas of the tongue movement by measuring the inner area of the dental arches of both the maxilla and the mandible. This study was based on the study models of 30 children and 128 adults who had clinically good occlusion. There were 15 male and 15 female children whose ages ranged from four years to seven years and 82 male and 46 female adults whose ages ranged from fifteen years to fifty four years. The obtained results were as follows : 1. The mean of the maximum areas within the primary dental arches of both the maxilla and the mandible were $7.06\pm0.8\textrm{cm}^2, 5.49\pm0.77\textrm{cm}^2$ in male children and $6.82\pm0.98\textrm{cm}^2, 5.28\pm0.80\textrm{cm}^2$ in female children respectively. 2. The mean of the maximum areas within the permanent dental arches of both the maxilla and mandible were $17.01\pm2.38\textrm{cm}^2, 13.57\pm1.57\textrm{cm}^2$ in male and $16.75\pm2.08\textrm{cm}^2, 13.36\pm1.01\textrm{cm}^2$ in female respectively.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.27 no.2
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• pp.87-93
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• 2015

Recently, the heat exchangers are requiring higher performance and reliability since they are being used under the operating condition of high temperature and pressure. To satisfy these requirements, we need special materials and bonding technology. This study presents a manufacturing technology for high temperature and high pressure micro channel heat exchanger using Inconel 617. The bonding performance for diffusion bonded heat exchanger was examined and analyzed. The analysis were conducted by measuring thermal and mechanical properties such as thermal diffusivity and tensile strength, and parametric studies about bonding temperature and pressing force were also carried out. The results provided insight for bonding evaluation and the bonding condition of $1200^{\circ}C$, and 50 tons was found to be suitable for this heat exchanger. From the results, we were able to establish the base technology for the manufacturing of Inconel 617 heat exchanger through the application of the diffusion bonding.

• Journal of Power System Engineering
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• v.3 no.1
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• pp.16-22
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• 1999

The purpose of this study is to prevent the stick, scuffing, scratch between piston and cylinder, is to contribute the piston design such as piston profile, clearance by calculating reaction force by over-lap of piston skirt, as measuring the temperature distributions of cylinder wall. The experiment has been peformed to obtain data during actual engine operation. Temperature gradient in peripheral and axial distributions of cylinder wall according to torque and speed of engine were measured by use of an 800cc class gasoline engine. The results obtained are summarized as follows ; 1) The temperature of cylinder wall at TDC was about $50{\sim}75^{\circ}C$ higher than temperature of cooling water. 2) The rear side temperature of top dead center was $141^{\circ}C$(1/4 load) in axial distribution, whereas the rear side of midway position temperature was $98^{\circ}C$. 3) The temperature of cylinder wall increased in according to rising temperature of cooling water. 4) The thrust side temperature of cylinder wall was about $15^{\circ}C$ in all load test. 5) The rear side temperature of top dead center was $159^{\circ}C$ (1/2 load) in peripheral distribution, it was about $39^{\circ}C$ higher than thrust side temperature.

• Nuclear Engineering and Technology
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• v.47 no.1
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• pp.115-125
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• 2015

Background: Residual stress always exists on any kind of welded area. This residual stress can cause the welded material to crack or fracture. For many years, the hole-drilling method has been widely used for measuring residual stress. However, this method is destructive. Nowadays, electronic speckle pattern interferometry (ESPI) can be used to measure residual stress with or without the hole-drilling method. ESPI is an optical nondestructive testing methods that use the speckle effect. Mechanical properties can be measured by calculation of the phase difference by the variation of temperature, pressure, or loading force. Methods: In this paper, the residual stress on the butt-welded area is measured by using ESPI with a suggested numerical calculation. Two types of specimens are prepared. Type I is made of pure base metal part and type II has a welded part at the center. These specimens are tensile tested with a material test system. At the same time, the ESPI system was applied to this test. Results: From the results of ESPI, the elastic modulus and the residual stress around the welded area can be calculated and estimated. Conclusion: With this result, it is confirmed that the residual stress on the welded area can be measured with high precision by ESPI.

• Journal of the Society of Naval Architects of Korea
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• v.51 no.5
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• pp.349-355
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• 2014

The resistance test of a high speed craft such as planing ship is performed with a high speed towing carriage instead of ordinary towing carriage because of the speed limitation. In the resistance test using high speed towing carriage, the model ship is fixed to the carriage to restrain the running attitude for enough measuring time. Such method is called fixed model test method. In the fixed model test method, to get the appropriate running attitude, the model test is iteratively repeated until the trim moment and lift force are close to zero. In this research, trim free model test method is investigated to reduce the number of iteration. And, the limitation of towing speed range in the trim free model test method is investigated.