• Journal of the Korea Convergence Society
• /
• v.7 no.5
• /
• pp.175-180
• /
• 2016

The demand for accurate freeform apsheric surface is increasing to satisfy the optical performance. In this paper, we develop the algorithm for opto-mechatronics convergence, that reconstruct the surface 3D profiles from the curvarure data along two orthogonal directions. A synthetic freeform surface with 8.4 m diameter was simulated for the testing. The simulation results show that the reconstruction error is 0.065 nm PV(Peak-to-valley) and 0.013 nm RMS(Root mean square) residual difference. Finally the sensitivity to noise is diagnosed for probe position error, the simulation results proving that the suggested method is robust to position error.

• The KIPS Transactions:PartB
• /
• v.14B no.4
• /
• pp.241-248
• /
• 2007

An L-curve corner detection method is proposed for the determination of the regularization parameter in optical flow estimation. The method locates the positive peak whose curvature difference from the just right-hand negative valley is the maximum in the curvature plot of the L-curve. while the existing curvature-method simply finds the maximum in the plot. Experimental results show that RMSE of the estimated optical flow is greater only by 0.02 pixels-per-frame than the least in the average sense. The proposed method is also compared with an existing curvature-method and the adaptive pruning method, resulting in the optical flow estimation closest to the least RMSE.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.26 no.2
• /
• pp.94-101
• /
• 1989

Transport properties of 2DEG at AlGaAs/GaAs interface such as average electron energy, flight distance, each valley occupancy ratio, average electron velocity for various fields are investigated by MONTE-CARLO method. As the electric field increases, more electrons transit drastically from (000) valley to (000) upper valley. This phenomenon shows the nonstationary effect such as velocity overshoot. The duration of the transient decreases from about 1.4 psec for electric field E = 7KV/cm to about 0.7 psec for 12KV/cm. The average electron velocity during transient transport in 2DEG is about 8 times the steady-state velocity for E = 12KV/cm at room temperature. In comparison with bulk GaAs the peak velocity in the 2DEG is higher than that in even pure bulk GaAs at electric field E = 7 KV/cm. On the basis of the fact that the electrons in the 2DEG have larger peak velocity and shorter transient time of velocity than those in the bulk GaAs, it is suggested that the device with 2DEG may obtain higher mobility than that with bulk GaAs.

• The Journal of Korean Society for Radiation Therapy
• /
• v.22 no.1
• /
• pp.25-32
• /
• 2010

Purpose: In radiotherapy that takes into account respiration using a RPM (Real time Position Management, Varian, USA) system, which can treat in consideration of the movement of tumor, infrared reflective markers supplied by manufacturers cannot obtain respiratory signal if the couch rotates at a certain angle or larger. In order to solve this problem, the author developed the 3D infrared reflective marker named 'Kw-marker' that can obtain respiratory signal at any angle, and evaluate its usefulness. Materials and Methods: In order to measure the stability of respiratory signal, we put the infrared reflective marker on the 3D moving phantom that can reproduce respiratory movement and acquired respiratory signal for 3 minutes under each of 3 conditions (A: $couch\;0^{\circ}$, a manufacturer's infrared reflective marker B: $couch\;0^{\circ}$, Kw-marker C: $couch\;90^{\circ}$, Kw-marker). By analyzing the respiratory signal using a breath analysis program (Labview Ver. 7.0), we obtained the peak value, valley value, standard deviation, variation value, and amplitude value. In order to examine the rotation error and moving range of the target, we placed a B.B phantom on the 3D moving phantom, and obtained images at a couch angle of $0^{\circ}$ and $90^{\circ}$ using OBI, and then acquired the X, Y and Z values (mm) of the ball bearing at the center of the B.B phantom. Results: According to the results of analyzing the respiratory signal, the standard deviation at the peak value was A: 0.002, B: 0.002 and C: 0.003, and the stability of respiration for amplitude was A: 0.15%, B: 0.14% and C:0.13%, showing that we could get respiratory signal stably by using the Kw-marker. When the couch rotated $couch\;90^{\circ}$, the mean rotation error of the ball bearing, namely, the target was X: -1.25 mm, Y: -0.45 mm and Z: +0.1 mm, which were within 1.3 mm on the average in all directions, and the difference in the moving range of the target was within 0.3 mm. Conclusion: When we obtained respiratory signal using the Kw-marker in non-coplanar treatment where the couch rotated, we could acquire respiratory signal stably and the Kw-marker was effective enough to substitute for the manufacturer's infrared reflective marker. When the rotation error and moving range of the target were measured, there was little difference, indicating that the displacement of the reflector movement in couch rotation is the cause of change in the scale and amplitude of respiratory signal. If the converted value of amplitude height according to couch angle is studied further and applied, it may be possible to perform non-coplanar phase-based gating treatment.

• Journal of the Korea Society of Computer and Information
• /
• v.15 no.9
• /
• pp.67-76
• /
• 2010

This paper proposes a image-based water level measurement method, which adapt to the ruler's surface condition. When the surface of a ruler is deteriorated by mud, drifts, or strong light reflection, the proposed method judges the pollution of ruler by comparing distance between two levels: the first one is the end position of horizontal edge region which keeps the pattern of ruler's marking, and the second one is the position where the sharpest drop occurs in the histogram which is construct using image density based on the axis of image height. If the ruler is polluted, the water level is a position of local valley of the section having a maximum difference between the local peak and valley around the second level. If the ruler is not polluted, the water level is detected as the position having horizontal edges more than 30% of histogram's maximum value around the first level. The detected water level is converted to the actual water level by using the mapping table which is construct based on the making of ruler in the image. The proposed method is compared to the ultrasonic based method to evaluate its accuracy and efficiency on the real situation.

• The Journal of Advanced Prosthodontics
• /
• v.8 no.3
• /
• pp.235-240
• /
• 2016

PURPOSE. In this study, the aim of this study was to evaluate the effect of implant surface treatment on cell differentiation of osteoblast cells. For this purpose, three surfaces were compared: (1) a modified SLA (MSLA: sand-blasted with large grit, acid-etched, and immersed in 0.9% NaCl), (2) a laser treatment (LT: laser treatment) titanium surface and (3) a laser and acid-treated (LAT: laser treatment, acid-etched) titanium surface. MATERIALS AND METHODS. The MSLA surfaces were considered as the control group, and LT and LAT surfaces as test groups. Alkaline phosphatase expression (ALP) was used to quantify osteoblastic differentiation of MC3T3-E1 cell. Surface roughness was evaluated by a contact profilometer (URFPAK-SV; Mitutoyo, Kawasaki, Japan) and characterized by two parameters: mean roughness (Ra) and maximum peak-to-valley height (Rt). RESULTS. Scanning electron microscope revealed that MSLA (control group) surface was not as rough as LT, LAT surface (test groups). Alkaline phosphatase expression, the measure of osteoblastic differentiation, and total ALP expression by surface-adherent cells were found to be highest at 21 days for all three surfaces tested (P<.05). Furthermore, ALP expression levels of MSLA and LAT surfaces were significantly higher than expression levels of LT surface-adherent cells at 7, 14, and 21 days, respectively (P<.05). However, ALP expression levels between MSLA and LAT surface were equal at 7, 14, and 21 days (P>.05). CONCLUSION. This study suggested that MSLA and LAT surfaces exhibited more favorable environment for osteoblast differentiation when compared with LT surface, the results that are important for implant surface modification studies.

• Journal of Forest and Environmental Science
• /
• v.39 no.1
• /
• pp.13-19
• /
• 2023

We investigated Soil respiration in Bluepine forest of western Bhutan, in relation to soil temperature, moisture content and soil pH and it was aimed at establishing variability in space and time. The Bluepine forest thrives in the typical shallow dry valleys in the inter-montane Bhutan Himalaya, which is formed by ascending wind from the valley bottom, which carries moisture from the river away to the mountain ridges. Stratified random sampling was applied and the study site was classified into top, mid, low slope and further randomized sample of n=20 from 30 m×30 m from each altitude. The overall soil respiration mean for the forest was found 2248.17 CO₂ g yr^-1 and it is ~613.58 C g yr^-1. The RS from three sites showed a marginal variation amongst sites, lower slope (2,309 m) was 4.64 μ mol m^-2 s^-1, mid slope (2,631 m) was 6.78 μ mol m^-2 s^-1 and top slope (3,027 m) was 6.33 μ mol m^-2 s^-1 and mean of 5.92 μ mol m^-2 s^-1, SE=0.25 for the forest. Temporal distribution and variations were observed more pronounced than in the space variation. Soil respiration was found highest during March and lowest in September. Soil temperature had almost inverse trend against soil respiration and dropped a low in February and peak in July. The moisture in the soil changed across months with precipitation and pH remained almost consistent across the period. The soil respiration and soil temperature had significant relationship R²=-0.61, p=0.027 and other variables were found insignificant. Similar relationship are reported for dry season in a tropical forest soil respiration. Soil temperature was found to have most pronounced effect on the soil respiration of the forest under study.

• The Journal of Korean Academy of Prosthodontics
• /
• v.35 no.1
• /
• pp.31-42
• /
• 1997

This study was performed to investigate the surface roughness of the Cerec Vita Mark II polished by various polishing techniques, compare with that of the Vintage enamel porcelain glazed by high temperature glazing technique. All of the Cerec specimen were finished with sequential use of high speed diamond burs(grit 45, 30 and $15{\mu}m$). The groups were divided into 5 groups : Group I : Cerec Vita Mark II block specimens polished with Sof-lex discs. Group II : Cerce Vita Mark II block specimens polished with Two Striper MPS. Group III : Cerce Vita Mark II block specimens polished with Enhance. Group IV : Cerce Vita Mark II block specimens polished with Porcelain laminate polishing FG kit. Group V : Vintage enamel porcelain glazed by high temperature glazing Technique. Each group was consisted of 10 specimens. The surfaces produced were examined quantitatively using a laser specular reflectance machine(Perthen RM600-s, Feinpruf Perthen GmbH., Germany) and qualitatively under SEM(JSM-5400, JEOL, Japan). The Results were as follows : 1. The arithmetic mean roughness value(Ra) in groups 1, 2, 3 and 4 was higher than that of group5. There was statistically significant difference(P<0.05). 2. The arithmetic mean roughness value(Ra) decreased in the following orders : group 1, group 2, group 4, group 3 and there was no statistically significant difference between group 1 and group 2, group 3, and group 4. There was statistically significant difference among group 1, 2, and group 3, 4 and group 5(P<0.05). 3. The maximum individual peak-to-valley-height(Rmax) decreased in the following orders : group 2, group 1, group 4, group 3, group 5 and there was no statistically significant difference between group 1 and 2, group 1 and group 4, group 3 and group 5. There was statistically significant difference among group 1, 2, and group 1, 4 and group 3, 5(P<0.05). 4. The treated surfaces of group 5 had smoother surface than that of groups 1, 2, 3, 4 with SEM.

• Korean Journal of Optics and Photonics
• /
• v.11 no.6
• /
• pp.452-456
• /
• 2000

A measurement unit and signal processing algorithm have been developed for predicting arterial oxygen saturation noninvasively. The measurement set-up was composed of a probe including light source and photodetector, optical signal processing section, LED driving circuit, PC interface software for data acquisition and data processing software. Light from the LED's was irradiated onto the finger nail bed and transmitted light was measured at different wavelengths. An effective baseline correction method was developed and measured data were analyzed by using various data processing methods and prediction algOlithms. For performance evaluation, a pulse oximeter simulator (Bio- Tek Instrument Inc.) was used as reference. The best performance in terms of the correlation coefficient and the standard deviation was obtained under the following conditions; when the arterial signals were computed in terms of area rather than peak-valley difference, and when the algorithm calculating by $In(I_p/I_v)/I_{avr}$ value for pulsation waveform was used. In in vivo test, prediction was improved when the developed baseline correction method was used. In addition, wavelengths of 660 nm and 940 nm provided better linearity and precision than wavelengths of 660 nm and 805 nm. 05 nm.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.29 no.9 s.240
• /
• pp.1235-1242
• /
• 2005

A district heating(DH) system supplies environmentally-friend heat and is appropriate for reduction of energy consumption and/or air pollutions. The DH transmission pipe, composed of supply and return pipes, has been used to transmit the heat and prevent heat loss during transportation. The two types of pipes are operated at a temperature of $75\~115^{\circ}C\;and\;40\~65^{\circ}C$, respectively, with an operating pressure of less than 1.568MPa. The objectives of this paper are to systematize data processing of transition temperature and investigate its effects on fatigue life of DH pipes. For the sake of this, about 5 millions temperature data were measured during one year at ten locations, and then available fatigue lift estimation schemes were examined and applied to quantify the specific thermal fatigue life of each pipe. As a result, a relational database management system as well as reliable fatigue lift evaluation procedures is established for Korean DH pipes. Also, since the prototypal evaluation results satisfied both cycle-based and stress-based fatigue criteria, those can be used as useful information in the future fer optimal design, operation and energy saving via setting of efficient condition and stabilization of water temperature.