• 대한의용생체공학회:의공학회지
• /
• 제36권4호
• /
• pp.115-122
• /
• 2015

A standard air flow generator system was developed to generate air flows of various levels simultaneously applied to two different air flow transducer modules. Axes of two identical standard syringes for spirometer calibration were connected with each other and driven by a servo-motor. Linear displacement transducer was also connected to the syringe axis to accurately acquire the volume change signal. The user can select either sinusoidal or square waveform of volume change and manually input any volume as well as maximal flow rate levels ranging 0~3 l and 0~15 l/s, respectively. Various volume and flow levels were input to operate the system, then the volume signal was acquired followed by numerical differentiation to obtain the air flow signal. The measured volumes and maximal air flow rates were compared with the user input data. The relative errors between the user-input and the measured stroke volumes were all within 0.5%, demonstrating very accurate driving of the system. In case of the maximal flow rate, relatively large error was observed when the syringe was driven very fast within a very short time duration. However, except for these few data, most measured flow rates revealed relative errors of approximately 2%. When the measure and user-input stroke volume and maximal flow rate data were analyzed by linear regression analysis, respectively, the correlation coefficients were satisfactorily higher than 0.99 (p < 0.0001). These results demonstrate that the servo-motor controls the syringes with enough accuracy to generate standard air flows. Therefore, the present system would be very much practical for calibration process as well as performance evaluation and comparison of two different air flow transducer modules.

• 한국공작기계학회논문집
• /
• 제15권1호
• /
• pp.1-7
• /
• 2006

A method of the volumetric error measurement and calibration of NC machine tools is studied using an artifact method. In this study, a hole-pate is designed and machined using stainless steel. We tested and applied the hole-plate artifact in a commercial CMM(Coordinate Measuring Machine), after calibration of the hole-plate using a precise CMM. It has been shown that not only the measurement of geometric error components but also the 2D length error calculation in a working volume is available using the hole-pate artifact method. The results of study can also be used in NC machine with touch probe as the same method in CMM.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 1998년도 춘계학술대회논문집; 용평리조트 타워콘도, 21-22 May 1998
• /
• pp.704-709
• /
• 1998

An automated calibration system of sound level meters was developed and tested. As a standard sound source, the speaker unit(Forstex FE208) cabineted by 440 * 390 * 490 mm$^{3}$(LHW) volume wood box was adopted. Including this source, the driving part was found out to have a good linearity of sound pressure output vs AC input. We use the Hybrid-Bisect, /Newton-Raphson method modified by the linearity as searching algorithm. Personal computer and program do the control, measurements, and calculations and finally do the accumulation of useful data and results. Several trials of automatic calibration using this developed system give reliable results.

• 천문학회보
• /
• 제43권1호
• /
• pp.68.2-68.2
• /
• 2018

Spectroscopic observations commonly use a slit or fiber; however, non-slit spectroscopy enables us to observe a larger number of targets in one frame of image. Hence, it has been adopted as an observational mode for observatories like HST and JWST. Slitless spectroscopy requires wavelength calibration solutions in order to distinguish and measure the absorption / emission lines from the spectra with high accuracy. We installed the Volume Phase Holographic (VPH) grating to SQUEAN camera on the McDonald 2.1m telescope and obtained images with spectral resolutions of ~ 100 and 200. In order to derive the wavelength calibration, we measured the distances between the 0th order images and spectral features of various quasars. The distances are converted to wavelengths using the known wavelengths of the emission lines. We tested several different methods of spectral extraction and peak estimation of emission lines. We will present the results for the wavelength calibration and suggest the reliable methods to find the solution.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2009년도 춘계 학술발표회
• /
• pp.23-29
• /
• 2009

A sand-cone method is commonly used to determine the density of the compacted soils. This method uses a calibration container to determine the bulk-density of the sand for use in the test. The density of the test or compacted soil is computed on the assumption that the calibration container has approximately the same size or volume and allows the sand to fall approximately the same height as a test hole in the field. However, in most cases the size or shape of test hole is not exactly the same as the calibration container. There is certain discrepancy between sand particle settlement or arrangement in the laboratory calibration and in the field testing, which may cause an erroneous determination of in-situ density. The sand filling process is simulated in the laboratory and its effect on the determination of density is investigated. Artificially-made holes with different heights and bottom shapes are prepared to simulate various shapes of the test hole in the field. The sands with different gradations are used in the testing to examine how sand grain size influences the determination of density in the field.

• Journal of Gastric Cancer
• /
• 제17권3호
• /
• pp.204-211
• /
• 2017

Purpose: Recently, a nomogram predicting overall survival after gastric resection was developed and externally validated in Korea and Japan. However, this gastric cancer nomogram is derived from large-volume centers, and the applicability of the nomogram in smaller centers must be proven. The purpose of this study is to externally validate the gastric cancer nomogram using a dataset from a medium-volume center in Korea. Materials and Methods: We retrospectively analyzed 610 patients who underwent radical gastrectomy for gastric cancer from August 1, 2005 to December 31, 2011. Age, sex, number of metastatic lymph nodes (LNs), number of examined LNs, depth of invasion, and location of the tumor were investigated as variables for validation of the nomogram. Both discrimination and calibration of the nomogram were evaluated. Results: The discrimination was evaluated using Harrell's C-index. The Harrell's C-index was 0.83 and the discrimination of the gastric cancer nomogram was appropriate. Regarding calibration, the 95% confidence interval of predicted survival appeared to be on the ideal reference line except in the poorest survival group. However, we observed a tendency for actual survival to be constantly higher than predicted survival in this cohort. Conclusions: Although the discrimination power was good, actual survival was slightly higher than that predicted by the nomogram. This phenomenon might be explained by elongated life span in the recent patient cohort due to advances in adjuvant chemotherapy and improved nutritional status. Future gastric cancer nomograms should consider elongated life span with the passage of time.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2011년도 춘계학술대회 논문집
• /
• pp.1109-1110
• /
• 2011

• 한국연초학회지
• /
• 제27권1호
• /
• pp.107-114
• /
• 2005

The uncertainty of measurement in quantitative analysis of ammonia by continuous-flow analysis method was evaluated following internationally accepted guidelines. The sources of uncertainty associated with the analysis of ammonia were the weighing of sample, the preparation of extracting solution, the addition of extracting solution into the sample, the reproducibility of analysis and the determination of water content in tobacco, etc. In calculating uncertainties, Type A of uncertainty was evaluated by the statistical analysis of a series of observation, and Type B by the information based on supplier's catalogue and/or certificated of calibration. It was shown that the main source of uncertainty was caused by the volume measurement of 1 mL and 2 mL, the purity of ammonia reference material in the preparation of standard solution, the reproducibility of analysis and the determination of water content of tobacco. The uncertainty in the addition of extraction solution, the sample weighing, the volume measurement of 50 mL and 100 mL, and the calibration curve of standard solution contributed relatively little to the overall uncertainty. The expanded uncertainty of ammonia determination in burley tobacco at $95\%$ level of confidence was $0.00997\%$.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2002년도 학술대회지
• /
• pp.507-510
• /
• 2002

An algorithm of 3-D particle image velocimetry(3D-PIV) was developed for the measurement of 3-D velocity Held of complex flows. The measurement system consists of two or three CCD camera and one RGB image grabber. Flows size is $1500{\times}100{\times}180(mm)$, particle is Nylon12(1mm) and illuminator is Hollogen type lamp(100w). The stereo photogrammetry is adopted for the three dimensional geometrical mesurement of tracer particle. For the stereo-pair matching, the camera parameters should be decide in advance by a camera calibration. Camera parameter calculation equation is collinearity equation. In order to calculate the particle 3-D position based on the stereo photograrnrnetry, the eleven parameters of each camera should be obtained by the calibration of the camera. Epipolar line is used for stereo pair matching. The 3-D position of particle is calculated from the three camera parameters, centers of projection of the three cameras, and photographic coordinates of a particle, which is based on the collinear condition. To find velocity vector used 3-D position data of the first frame and the second frame. To extract error vector applied continuity equation. This study developed of various 3D-PIV animation technique.

• 한국분무공학회지
• /
• 제20권4호
• /
• pp.217-222
• /
• 2015

In this study, Injection rate tests of a Diesel common-rail injector have been performed with injection volume measurement type injection rate test system EMI21 for construction of injector model can be used in an engine calibration mean valued model. The measuring principle of the test system is based on measurement of dispalcement of a movable measurement piston by the volume of fluid released by the injector. From these injection rate test results, the characteristics on shape of instantaneous injection rate and injection fuel amount have been investigated and injection fuel amount calculation equation based on test results has been newly constructed. This equation is very simple and calculation error is less than 5% with test results for wide range injection pressure (200~1800 bar) and injection duration ($200{\sim}1800{\mu}s$) conditions. So, it is anticipated that newly constructed simple injection fuel amount model in this study can be efficiently used on engine calibration and control model.