• Journal of Korean Society for Geospatial Information Science
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• v.13 no.1 s.31
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• pp.3-10
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• 2005

This study attempts to measure effectively three dimensional deformation in road slopes using digital close-range photographs. After the still video images were acquired respectively on the same multi-station geometric configuration in two epoches, photo-triangulation was rallied out respectively by conventional standard bundle adjustment and free-net bundle adjustment and the computed results were compared with those of geodetic method by total station. Three dimensional coordinates and deformation amounts were able to be derived with the RMSE of sub-millimeter and the relative accuracy of $1/30,000{\sim}1/35,000$. It was shown that free-net bundle adjustment is about 13% higher than standard bundle adjustment in the accuracy of photo-triangulation. It was ascertained that the free-net technique is able to promote fast and accurate deformation surveying without the necessity of geodetic control survey in complicated industrial sites.

• Archives of Plastic Surgery
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• v.39 no.1
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• pp.25-30
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• 2012

Background : The soft palate functions as a valve and helps generate the oral pressure required for normal speech resonance. Speech problems and nasal regurgitation can result from a soft palatal defect. Reduction of the size of the velopharyngeal orifice is required to compensate for the lack of mobility in a reconstructed soft palate. We suggest a large volume folded free flap for reduction of the caliber and a palmaris longus tendon sling for suspension of the reconstructed palate. Methods : Six patients had total soft palate resection for tonsillar cancer and reconstruction with a large volume folded radial forearm free flap combined with a palmaris longus sling. A single surgeon and speech therapist examined the patients with three standardized speech assessment tools: nasometer test, consonant articulation test, and speech acuity test performed for speech evaluation. Results : Mean nasalance score was 76.20% for sentences with nasal sounds and 43.60% for sentences with oral sounds. Hypernasality was seen for oral sound sentences. The mean score of the picture consonant articulation test was 84% (range, 63% to 100%). The mean score of the speech acuity test was 5.84 (range, 5 to 6). These mean ratings represent a satisfactory level of speech function. Conclusions : The large volume folded free flap with a palmaris longus tendon sling for total soft palate reconstruction resulted in satisfactory prognosis for speech despite moderate hypernasality.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2001.04a
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• pp.45-47
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• 2001

Due to pressure from threatened legislation in Europe, consumer and governmental pressure in Japan, and glob머 market considerations in the US, there is a rapidly growing interest in lead-free solderinger, Although the move to lead free soldering seems inevitable, many problems will arise in production assembly. It is generally acknowledged that the lead-free solders available offer a much s smaller process window than lead/tin, related mainly to the higher soldering temperatures which naturally result from increases of liquidus temperatures of at least 300 C. However, raising reflow temperatures from the current 220-2300 C to 250 2600 C will lead to problems with the boards and components as well as i increasing oxidation effects. There is a need to keep reflow temperatures low without reducing solderablity. Some results on benefits of inert atmospheres are discussed in this paper. For example, testing in a nitrogen atmosphere, with 300 ppm oxygen, by the N National Physical Laboratory (NPU has revealed clear benefits for ine$\pi$mg lead-free alloys, by restoring the solderability to lead/tin levels, by enabling lower soldering temperatures. However, there has been little testing over a range of oxygen levels in nitrogen and this is an important issue in determining n nitrogen supply and oven costs. Some results are reported here from work by NPL conducted for BOC in w which solderability was evaluated for tin기ead and tin/silver/copper eutectic a alloys in a wetting balance over a range of oxygen levels form 10 ppm to 21% ( (air). The studies confirm that acceptable wetting times occur in inert atmospheres a at soldering temperatures 20 to 300 C lower than are possible in air.

• Steel and Composite Structures
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• v.27 no.6
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• pp.717-725
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• 2018

One of the most important design criteria in military tunnels and armoured doors is to resist the blast loads with minimum structural weight. This can be achieved by using steel sandwich panels. In this paper, the nonlinear behaviour of steel sandwich panels, with different core materials: (1) Hollow (no core material); (2) Rigid Polyurethane Foam (RPF); and (3) Vulcanized Rubber (VR) under free air blast loads, was investigated using detailed 3D nonlinear finite element models in Ansys Autodyn. The accuracy of the finite element model proposed was verified using available experimental test data of a similar steel sandwich panel tested. The results show the developed finite element model can be reliably used to simulate the nonlinear behaviour of the steel sandwich panels under free air blast loads. The verified finite element model was used to examine the different parameters of the steel sandwich panel with different core materials. The result shows that the sandwich panel with RPF core material is more efficient than the VR sandwich panel followed by the Hollow sandwich panels. The average maximum displacement of RPF sandwich panel under different ranges of TNT charge (1 kg to 10 kg at a standoff distance of 1 m) is 49% and 53% less than the VR and Hollow sandwich panels, respectively. Detailed empirical design equations were provided to quantify the maximum deformation of the steel sandwich panels with different core materials and core thickness under a different range of blast loads. The developed equations can be used as a guide for engineer to design steel sandwich panels with RPF and VR core material under a different range of free air blast loads.

• Coupled systems mechanics
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• v.9 no.5
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• pp.455-471
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• 2020

This paper presents the results of the study of vertically natural frequency of tractor tires are effected by changing different ground contacts and inflation pressures using the Free Decay Method. The results show that the natural frequencies of the tire are not affected while the vertical acceleration increased strongly due to the increase of inflation pressure when the tire performs free decay vibration on rigid ground. In addition, the number of natural frequency peaks of the tire also increases with increasing tire inflation pressure. On the other hand, the natural frequencies of the tractor tire increases strongly while the vertical acceleration decreases slightly with the increase of tire inflation pressure as the tire performs free decay vibration on soft soil. Further, the natural frequencies of tire-soil system are always higher than that of tire only, and it changed with changing the soil depth. Results also show the natural frequency of tire and tire-soil system is in the range of 3.0 to 10.0 Hz that lie within the most critical natural frequency range of the human body. These findings have to be mentioned and used as design parameters of the tractor suspension system.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.5
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• pp.653-662
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• 1999

In this paper, subharmonically injection locked oscillator(SILO) was designed and measured. SILO with series feedback was designed using Two Signal Method(TSM). The free-running oscillator frequency was 9.4 GHz with 6 dBm output power. In case of injection, the multiplied injected signal locked the free-running frequency. The locked signal output power was higher than any other spurious response at least 40 dB. The locking range was 220MHz (second subharmonic locking), 100 MHz(4th subharmonic locking), and phase noise was -111 dBc/Hz, -104 dBc/Hz at 100kHz offset, respectively.

• Journal of the Society of Naval Architects of Korea
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• v.38 no.4
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• pp.48-55
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• 2001

In this paper, sensitivity analysis for the coupled axial and torsional undamped free vibration of ship propulsion shafting is proposed. The purpose of this study is to effectively and optimally design the resonance frequencies of propulsion shafting affecting barred speed range of main engine by modifying the diameters of intermediate and propeller shafts. The presented method is validated by the sensitivity analysis for the natural frequencies of propulsion shafting of two real large merchant ships. In addition, the changes of natural frequency and resonance main engine speed are discussed in case that the diameter is varied within the range regulated by the rule of shipping register.

• Journal of the Korean Society of Safety
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• v.27 no.6
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• pp.7-13
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• 2012

A lack of study on the dynamic tensile strengths of Sn-based solder joints at high strain rates was the motivation for the present study. A modified miniature Charpy impact testing machine instrumented with an impact sensor was built to quantitatively evaluate the dynamic impact strength of a solder joint under tensile impact loading. This study evaluated the tensile strength of lead-free solder ball joints at strain rates from $1.8{\times}10^3s^{-1}$ and $8.5{\times}10^3s^{-1}$. The maximum tensile strength of the solder ball joint decreases as the load speed increases in the testing range. This tensile strength represented that of the interface because of the interfacial fracture site. The tensile strengths of solder joints between Sn-3.0Ag-0.5Cu and copper substrate were between 21.7 MPa and 8.6 MPa in the high strain range.

• KEPCO Journal on Electric Power and Energy
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• v.8 no.1
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• pp.31-36
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• 2022

This paper presents the measuring process of dynamic properties of offshore wind power foundation and provides consideration of each step. This Guideline enables to maintain consistent measuring procedure and therefore increase the reliability of test results. Small scaled suction bucket foundation was fabricated to represent the commercial support structure installation mechanism and two cases(free-free, free-fixed) of dynamic tests were performed at workshop. From the tests, the importance of dynamic properties of connection part between suction bucket and tower was figured out. More over, types and configuration of measuring devices are recommended which can help find the natural frequency of wind turbine foundation correctly. In field test, it was found that the natural frequency of suction bucket foundation was increased linearly with the penetration depth due to the confining effect of ambient soil. Meanwhile, it was not easy to get an enough excitation force with normal impact hammer because the N.F of suction bucket model was in the lower range of 0 Hz ~ 5 Hz. Therefore, new excitation method which has enough force and can excite lower frequency range was devised. This study will help develop safety check procedure of suction bucket foundation in field at each installation stage using the N.F measurement.

• Geomechanics and Engineering
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• v.30 no.5
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• pp.471-478
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• 2022

Creep of soils has a significant impact on mechanical properties. The one-dimensional consolidation creep test, thermal analysis test, scanning electron microscope (SEM) test, and mercury compression test were performed on Guilin red clay to study the changes in bound water and microstructure during the creep process of Guilin red clay. According to the results of the tests, only free and weakly bound water is discharged during the creep of Guilin red clay. When the consolidation pressure p is in the 12.5-400.0 kPa range, it is primarily the discharge of free water; when the consolidation pressure p is in the 800.0-1600.0 kPa range, the weakly bound water is converted to free water and discharged. After consolidation creep, the microstructure of soil changes from granular overhead contact structure to flat sheet-like stacking structure, with a decrease in the number of large and medium pores, an increase in the number of small and micro pores, and a decrease in the fractal dimension of pores. The creep process of red clay is the discharge of weakly bound water as well as the compression of large pores into small pores and the transition of soil particles from loose to dense.