• Journal of the Korean Society of Radiology
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• v.7 no.2
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• pp.157-163
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• 2013

This study was to analyze quantitatively movement of planning target volume (PTV) and change of PTV volume through movement of diaphragm according to breathing phase. The purpose of present study was to investigate optimized respiration phase for radiation therapy of lung cancer. Simulated breathing training was performed in order to minimize systematic errors which is caused non-specific or irregular breathing. We performed 4-dimensional computed tomography (4DCTi) in accordance with each respiratory phase in the normalized respiratory gated radiation therapy procedures, then not only defined PTVi in 0 ~ 90%, 30 ~ 70% and 40 ~ 60% in the reconstructed 4DCTi images but analyzed quantitatively movement and changes of volume in PTVi. As a results, average respiratory cycle was $3.4{\pm}0.5$ seconds by simulated breathing training. R2-value which is expressed as concordance between clinically induced expected value and actual measured value, was almost 1. There was a statistically significant. And also movement of PTVi according to each respiration phase 0 ~ 90%, 30 ~ 70% and 40 ~ 60% were $13.4{\pm}6.4mm$, $6.1{\pm}2.9mm$ and $4.0{\pm}2.1mm$ respectively. Change of volume in PTVi of respiration phase 30 ~ 70% was decreased by $32.6{\pm}8.7%$ and 40 ~ 60% was decreased by $41.6{\pm}6.2%$. In conclusion, PTVi movement and volume change was reduced, when we apply a short breathing phase (40 ~ 60%: 30% duty cycle) range. Furthermore, PTVi margin considered respiration was not only within 4mm but able to get uniformity of dose.

• Geophysics and Geophysical Exploration
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• v.17 no.2
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• pp.66-73
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• 2014

To estimate the shear-velocity ($v_s$) structure beneath the WIZ station on White Island in New Zealand, we applied receiver function (RF) inversion and H-${\kappa}$ stacking methods to 362 teleseismic events (Mw > 5.5) recorded during April 20, 2007 to September 6, 2013. Using 71 RFs with errors less than 20% after 200 iterative computations, we determined that the depth to Moho of $v_s$ = 4.35 km/s is $24{\pm}1km$ within a 15 km radius of the station. In an 1-d $v_s$ model derived by RF inversions, a 4-km thick low-velocity layer (LVL) at depths of 18 ~ 22 km was identified in the lower crust. This LVL, which is 0.15 km/s slower than the rocks above and below it, may indicate the presence of a deep magma reservoir. The H-${\kappa}$ stacking method yielded an estimate of the depth to the Moho of 24.5 km, which agrees well with the depth determined by RF inversions. The low $v_p/v_s$ ratio of 1.64 may be due to the presence of gas-filled rock or hot crystallizing magma.

• Journal of the Korean earth science society
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• v.37 no.7
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• pp.448-464
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• 2016

The purpose of this study is to optimize the parameters related to consensus coherency within the PCL 1300, the operating program of wind profiler, from a validation of wind data between rawinsonde and wind profiler at Chupungryeong ($36^{\circ}13^{\prime}$, $127^{\circ}59^{\prime}$) site in Korea. It is then to analyze the diurnal and seasonal characteristics of the turbulence energy dissipation rate (${\varepsilon}$) in clear and rainy days from March 2009 to February 2010. In comparison of the wind data between wind profiler and rawinsonde during April 22-23, 2010, it was shown in a big error more than $10ms^{-1}$ over the height of 3,000 meters in the zonal (u) and meridional (v) wind components. When removing more than $10ms^{-1}$ in each wind speed difference of u an v components between the two instruments, the correlation coefficients of these wind components were 0.92 and 0.88, respectively, and the root mean square errors were 3.07 and $1.06ms^{-1}$. Based on these results, when the data processing time and the minimum available data within the PCL 1300 program were adjusted as 30 minutes and 60%, respectively, the bias errors were small. In addition, as a result of an analysis of sensitivity to consensus coherency of u and v components within the PCL1300 program, u components were underestimated in radial coherency, instantaneous and winbarbs coherency, whereas v components were overestimated. Finally by optimizing parameters of the PCL1300 program, the diurnal and seasonal means of ${\varepsilon}$ at each height were higher in rainy days than those in clear days because of increasing in the vertical wind speed due to upward and downward motions. The mean ${\varepsilon}$ for clear and rainy days in winter was lower than those of other seasons, due to stronger horizontal wind speed in winter than those in other seasons. Consequently, when the turbulence energy dissipation rates in the vertical wind speed of more than ${\pm}10cm\;s^{-1}$ were excluded for clear and rainy days, the mean ${\varepsilon}$ in rainy days was 6-7 times higher than that in clear days, but when considering them, it was 4-5 times higher.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.8
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• pp.703-710
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• 2012

At the stage of conceptual design of a helicopter, it is a general way using low fidelity analysis methods because of a large number of design calculations and trade-off studies. Determination of empirical parameters used in analysis codes for more practical design, depends on an user's design experiences, which effects on the accuracy and the fidelity of conceptual design results. Thus, more precise and logical method should be required to determine the empirical parameters used in the conceptual design of a helicopter. The present method is to be used not only in verifying the empirical parameters generated by design requirements, but also regenerate them if they contain any errors. Empirical parameters produced by present method were used to design a helicopter with a payload objective and performance constraints of an operating helicopter. As a result, weights and geometries of designed helicopter matched the target value within 5% significance level, proving that the suggested parameter generating method can be useful in the conceptual design of a helicopter.

• Journal of the Korea institute for structural maintenance and inspection
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• v.20 no.5
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• pp.50-57
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• 2016

The present study proposed three inspection reliability indices which compared inspection results evaluated at in-depth(routine) inspection and in-depth safety inspection; Nominal inspection reliability index, Real inspection reliability index, and DS nominal inspection reliability index. The methods to improve the inspection reliability were also proposed. Since bridge inspection process is critical to ensuring the safety of bridges and identifying repair and maintenance needs, the quality of the inspection data produced from the inspection process is very important. Consequently, the inspection reliability indices were suggested to evaluate quality of current inspection practices. Specifically, approximately 85% of inspection errors evaluated by the DS nominal inspection reliability index are within 1 rating grade(equal to or less than damage score ${\pm}0.1$). In order to improve the inspection reliability, transportation agency should implement QC(Quality Control) practices and develop professional expertises of inspectors by higher requirements for inspectors, on-off line inspection training and etc.

• The korean journal of orthodontics
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• v.35 no.3 s.110
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• pp.216-226
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• 2005

The purpose of this study was to test and compare the accuracy and reliability of soft tissue profile predictions generated from two computer software programs (Quick Ceph Image $Pro^{TM}$ (ver 3.0) and $V-Ceph^{TM}$(ver 3.5)) for mandibular set-back surgery. The presurgical and postsurgical lateral cephalograms of 40 patients (20 males and 20 females) were traced on the same acetate paper with the reference taken as the cranial base outline. The presurgical skeletal outlines were digitized onto each computer program and the mandible was moved to mimic the expected surgical procedure with reverence to the mandibular anterior border and lower incisor position of the actual postsurgical skeletal outline. The soft tissue profile was generated and the amount and direction of skeletal movement was calculated with each software. The predicted soft tissue profile was compared to the actual postsurgical soft tissue profile. There were differences between the actual and the predicted surgical soft tissue profile charges in the magnitude and direction, especially the upper lip. lower lip and the soft tissue chin (P<0.05). Quick Ceph had more horizontal measurement errors and thickness errors for the upper lip and lower lip, but V-Ceph had more vertical measurement errors of the lower lip (P<0.05). There was a positive correlation between the prediction errors and the amount of mandibular movements in the vertical position of Sn, the horizontal position of Ls and the upper lip thickness for V-Ceph, and there was a negative correlation in the horizontal position and the thickness of the lower lip for Quick Ceph (P<0.05). However all of the Prediction errors of both imaging softwares were ranged within 3mm, and this was considered to be allowable clinically.

• The Journal of the Acoustical Society of Korea
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• v.26 no.2
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• pp.61-68
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• 2007

The frequency response of a microphone, which indicates the frequency range that a microphone can output within the approved level, is one of the most significant standards used to measure the characteristics of a microphone. At present, conventional methods of measuring the frequency response are complicated and involve the use of expensive equipment. To complement the disadvantages, this paper suggests a new algorithm that can measure the frequency response of a microphone in a simple manner. The algorithm suggested in this paper generates the Optimized Aoshima's Time Stretched Pulse(OATSP) signal from a computer via a standard speaker and measures the impulse response of a microphone by convolution the inverse OATSP signal and the received by the microphone to be measured. Then, the frequency response of the microphone to be measured is calculated using the signals. The performance test for the algorithm suggested in the study was conducted through a comparative analysis of the frequency response data and the measures of frequency response of the microphone measured by the algorithm. It proved that the algorithm is suitable for measuring the frequency response of a microphone, and that despite a few errors they are all within the error tolerance.

• Journal of Korean Ophthalmic Optics Society
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• v.15 no.2
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• pp.195-199
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• 2010

Purpose: This study was to investigate the relevance between refractive and anatomical changes temporarily on the eyes after alcohol ingestion. Methods: Eight subjects (16 eyes) which were $24.5{\pm}1.5$ aged males drunk the alcohol of 0.42 g per kg of body weight within 30 minutes. Refractive errors, the radius of corneal curvature, corneal thickness, pupillary size, intraocular pressure, and the length of the ocular axis at 1 h, 4 h, and 24 h after alcohol ingestion were compared with them of non-alcoholic state. Results: At 1 h after alcohol ingestion, breath alcohol concentration was the highest (p<0.001), more negative spherical power was needed (p<0.05) for correction, pupillary diameter was decreased (p<0.05), intraocular pressure was decreased (p<0.001), and the length of the ocular axis was increased compared with each one of non-alcoholic state. At 4 h after alcohol ingestion, all anatomical changes were the same tendency as at 1 h after alcohol ingestion. But at 24 h after alcohol ingestion, both refractive changes and anatomical changes were not significant compared with them of non-alcoholic state. Conclusions: Temporary changes of refractive error after alcohol ingestion may be related with decrease of intraocular pressure and increase of the length of ocular axis.

• Progress in Medical Physics
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• v.10 no.3
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• pp.133-140
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• 1999

In this paper, as a preliminary study for developing a full 3D electron dose calculation algorithm, We developed 2.5D electron dose calculation algorithm by extending 2D pencil-beam model to consider three dimensional geometry such as air-gap and obliquity appropriately. The dose calculation algorithm was implemented using the IDL5.2(Research Systems Inc., USA), For calculation of the Hogstrom's pencil-beam algorithm, the measured data of the central-axis depth-dose for 12 MeV(Siemens M6740) and the linear stopping power and the linear scattering power of water and air from ICRU report 35 was used. To evaluate the accuracy of the implemented program, we compared the calculated dose distribution with the film measurements in the three situations; the normal incident beam, the 45$^{\circ}$ oblique incident beam, and the beam incident on the pit-shaped phantom. As results, about 120 seconds had been required on the PC (Pentium III 450MHz) to calculate dose distribution of a single beam. It needs some optimizing methods to speed up the dose calculation. For the accuracy of dose calculation, in the case of the normal incident beam of the regular and irregular shaped field, at the rapid dose gradient region of penumbra, the errors were within $\pm$3 mm and the dose profiles were agreed within 5%. However, the discrepancy between the calculation and the measurement were about 10% for the oblique incident beam and the beam incident on the pit-shaped phantom. In conclusions, we expended 2D pencil-beam algorithm to take into account the three dimensional geometry of the patient. And also, as well as the dose calculation of irregular field, the irregular shaped body contour and the air-gap could be considered appropriately in the implemented program. In the near future, the more accurate algorithm will be implemented considering inhomogeneity correction using CT, and at that time, the program can be used as a tool for educational and research purpose. This study was supported by a grant (＃HMP-98-G-1-016) of the HAN(Highly Advanced National) Project, Ministry of Health & Welfare, R.O.K.

• Korean Journal of Remote Sensing
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• v.29 no.1
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• pp.95-104
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• 2013

In this study, a novel method is proposed for retrieving relative surface temperature from single-channel middle infra-red (MIR, 3-5 ${\mu}m$) remotely sensed data. In order to retrieve absolute temperature from MIR data, it is necessary to accommodate at least atmospheric effects, surface emissivity and reflected solar radiance. Instead of retrieving kinematic temperature of each target, we propose an alternative to retrieve the relative temperature between two targets. The core idea is to minimize atmospheric effects by assuming that the differential at-sensor radiance between two targets experiences the same atmospheric effects. To reduce effective simplify atmospheric parameters, each atmospheric parameter was examined by MODTRAN and MIR emissivity derived from ASTER spectral libraries. Simulation results provided a required accuracy of 2 K for materials with a temperature of 300 K within 0.1 emissivity errors. The algorithm was tested using MODIS band 23 MIR day time images for validation. The accuracy of retrieved relative temperature was $0.485{\pm}1.552$ K. The results demonstrated that the proposed algorithm was able to produce relative temperature with a required accuracy from only single-channel radiance data. However, this method has limitations when applied to materials having very low temperatures using day time MIR images.