• Journal of Biomedical Engineering Research
• /
• v.34 no.2
• /
• pp.73-79
• /
• 2013

Purpose: The purposes of this study were to measure the dose distribution of Photodynamic therapy(PDT) laser with 635 nm wavelength using GafChromic film. Method & Result: We made each output 300 J by changing mW and sec using the laser beam radiation mode such as C.W(Continuous Wave) mode, Pulse mode and Burst Pulse mode and measured the does at 0 mm and 5 mm of distance from optic fiber catheter end to the film, and at 5 mm distance by changing the angle of the end of the optic fiber catheter as $0^{\circ}$ and $0.5^{\circ}$. The radiated film was scanned and OD(Optical Density) was compared. And two-dimensional isodose curves were obtained and the consistency of shapes was compared. It was confirmed that there was consistency between optic density and the dose radiated on the film when we radiated GafChromic film by changing distance and angle of 300 J output in each radiation mode coordinating mW and sec. Conclusion: In this study, we could identify the stability according to changes in laser beam modes, changes in output according to distance, changes in uniformity according to angle, and beam profiles using GafChromic film, and we could also get two-dimensional isodose curve. It was found that small change in the distance and angle that is made when optic fiber catheter was contacted on the treatment area did not make big effects on the output of beam and the uniformity of dose, and it was also found that GafChromic film could be utilized for the purpose of QA of PDT laser beam.

• Journal of Physiology & Pathology in Korean Medicine
• /
• v.24 no.1
• /
• pp.42-47
• /
• 2010

The pulse diagnosis is an important method in Oriental Medicine. Recently, there have been continuous attempts to replace the finger palpation by Oriental medical doctors (OMDs) by more objective tools based on machines, e.g., pulse analyzers. To improve the performance of the pulse analyzers, both the machine-appropriate interpretations for the pulse images appeared in the literature and the improvement in the repeatability and reproducibility of the measurement sensors are to be developed. As an attempt towards the transformation of the pulse images in terms of machine-appropriate language, in this work, we suggest an upgraded algorithm for the solid/deficient pulses, which are the two representative pulse images informing us how strong the pulse pressure is. It has been argued that one could determine the solid/deficient pulses by the maximum pulse pressure from pulse analyzers. However, by a clinical test, we found that the maximum pulse pressure alone is not sufficient to determine the solid/deficient pulses. In addition to the maximum pulse pressure, the mean pulse pressure averaged over for five different hold-down pressures(3-D MAC) is needed to improve the agreement with the OMD's decision for the solid/deficient pulse. We found that, among the data diagnosed with having either the solid pulse or deficient pulse by OMDs, the novel algorithm showed 86.0% diagnosis rate and 81.6% concordance rate.

• Journal of the Korean Society for Precision Engineering
• /
• v.23 no.7 s.184
• /
• pp.30-38
• /
• 2006

Laser cutting technology is one of flexible rapid manufacturing technologies with various advantageous including a high cutting speed, manufacturing of parts with a complex shape and others. The quality of the cut part and the optimum cutting conditions are highly dependent on the combination of the process parameters. The objective of this research works is to investigate the influence of process parameters, such as power of laser, cutting speed of laser and material thickness, on the surface roughness and the striation formation of the cut section for the case of cutting of CSP 1N sheet using high power Nd:YAG Laser with a continuous wave (CW). In order to find the relationship between process parameters and the surface roughness and the striation formation of the cut section, several experiments are carried out. Through the investigation of the empirical results, it has been shown that the surface roughness is highly related to the striation formation, including the frequency and angle of the striation, of the cut section. From the results of experiments, an optimum cutting speed for each cutting condition has been obtained to improve both the quality of the cut surface and the cutting efficiency.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.41 no.6
• /
• pp.483-489
• /
• 2017

An ultrasonic technique was developed to characterize the resonance behavior of a microcantilever operating in a megahertz regime. A high-power ultrasonic pulser and a contact transducer were employed to excite the silicon microcantilever, and a Michelson interferometer was used to obtain the time domain waveform. The natural frequency of the microcantilever was evaluated through the fast Fourier transform of the signal, and a numerical analysis using the finite element method confirmed the measurement data. The present study proposes a novel and facile method to evaluate nanoscale materials and structures with high sensitivity compared to conventional approaches.

• 한국해양학회지
• /
• v.25 no.4
• /
• pp.182-188
• /
• 1990

The sedimentation processes and heavy metal distributions at the Nakdong estuary were investigated during October 1987 and September 1988. The depositional sedimentary environment of the studied area was estuarine environments and was divided into three provinces depending on its textural parameters such as barrier, tidal falt, and water passes. The relationship between the textural parameters showed that the barrier was under strong wave action, that the tidal flat was under relatively weak wind-driven currents, and that the water passes were under strong and continuous tidal currents. Each environments was resulted from different transport mechanism. the sand barrier sediments were transported by all three populations including suspension, saltation, and bed load, and water pass-deposited sediments were by the bad load with some suspension population. In water mass over the studied area, the concentrations of heavy metals including Cu, Cd, $Cr^{+6}$, Pb and Zn were recorded to be 27.8, 6.7, 20.4, 16.3, and 37.3 ppb in their highest concentrations, respectively. and those in sediments were 20.0, 1.65, 25.4, 15.4, and 132.0 ppm, respectively. The total up take factored of Cu, Cd, $Cr^{+6}$, Pb, and Zn by V. Muller (corbicula fluminea) were 1600, 310, 310, 490 and 7900, respectively.

• Journal of Powder Materials
• /
• v.23 no.2
• /
• pp.91-94
• /
• 2016

High-quality colloidal CdSe/ZnS (core/shell) is synthesized using a continuous microreactor. The particle size of the synthesized quantum dots (QDs) is a function of the precursor flow rate; as the precursor flow rate increases, the size of the QDs decreases and the band gap energy increases. The photoluminescence properties are found to depend strongly on the flow rate of the CdSe precursor owing to the change in the core size. In addition, a gradual shift in the maximum luminescent wave (${\lambda}_{max}$) to shorter wavelengths (blue shift) is found owing to the decrease in the QD size in accordance with the quantum confinement effect. The ZnS shell decreases the surface defect concentration of CdSe. It also lowers the thermal energy dissipation by increasing the concentration of recombination. Thus, a relatively high emission and quantum yield occur because of an increase in the optical energy emitted at equal concentration. In addition, the maximum quantum yield is derived for process conditions of 0.35 ml/min and is related to the optimum thickness of the shell material.

• The Journal of Engineering Geology
• /
• v.16 no.3 s.49
• /
• pp.293-300
• /
• 2006

The groundwater movement in the west costal landfill area was analyzed by measuring N value by Standard Penetration Test, coefficient of permeability by falling head method, linear structure analysis by Digital Elevation Method, groundwater flow direction and rate by flowmeter logging due to tidal variation in the each borehole. The coefficients of permeability of the weathered zone and of the marine deposit showed similar values although some values of weathered zone show smaller values than those of the marine deposit. The major groundwater flow and rate in the marine deposit observed as east-west direction due to tidal variation, but on the other hand it was observed as N45E in weathered zone which is the major direction of the linear structures in the area. 2 hours delayed changes of the groundwater flow direction was observed during the 24 hours observation, and it seems to be a travel time of the tidal wave which cause the continuous change of the hydaulic gradient of the groundwater.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.16 no.2
• /
• pp.225-233
• /
• 1998

It is necessary to check the water quality of the lake on a continuous basis to determine the appearance of water pollution; however, it not only takes much time and expenses but it is considerably difficult to investigate the wide range of the area. If we use the remote sensing technique through the use of satellites, the status of water quality can be checked covering many wide areas simultaneously; and because the same area can be measured on a periodic basis, it is extremely effective in investigating the water quality. Furthermore, as some of the Landsat sensors carry characteristics which sense objects according to wave length, the distribution of water quality can be checked relatively accurately within a short period of time, while its image can be displayed in color. Hence, this research has attempted to extract water quality elements, such as transparency, water depth, and surface water temperature by utilizing the satellite data, and has prepared the water quality distribution image map of the Lake Hwajinpo by presenting the related empirical formula of the water quality elements. If the water quality distribution image map is prepared after extracting the water quality elements from the DN of the Landsat TM image and then carrying out TIN analysis through the use of GIS, relatively more accurate pattern can be learned covering a wide rage of area than the pattern presented based on the value obtained from actual observation.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.26 no.6
• /
• pp.555-563
• /
• 2015

This paper presents signal processing algorithms of a frequency-modulated continuous-wave(FMCW) radar altimeter and provides a practical assessment technique. The radar altimeter is initially operated in search mode, when the radar altimeter detects a valid altitude, search mode is switched to track mode and a altitude being tracked is displayed. The sweep bandwidth in each mode is a function of altitude to narrow the beat frequency bandwidth. In addition, transmit power and receiver gain in each mode are controlled to compensate for the dynamic range of wide altitude range. To assess more realistic operation, the radar altimeter was tested using the crane setup. The crane test demonstrated that signal processing algorithms described in this paper resulted in a reduced measurement error rate.

• Korean Journal of Optics and Photonics
• /
• v.10 no.2
• /
• pp.162-168
• /
• 1999

A new design of four-pass dye laser amplifier affording a narrow-bandwidth pulsed output is demonstrated to suppress the amplified spontaneous emission(ASE) carried by the amplifier output and reduce the possibility of parasitic oscillation in the amplifier. By the direct pulsed amplification of a cw 100 mW dye laser under a Q-switched doubled Nd:YAG laser pumping with energy of 5.6 mJ/pulse, high-peak-power pulsed output with 1.5-mJ energy in 130-MHz bandwidth is obtained corresponding to a power gain greater than $2{\times}10^6$ and an energy efficiency of 27%. The ASE ratio in the four-pass amplifier output is dramatically reduced by using a diffraction grating in the amplifier. Compared with the results obtained from the normal operation of the amplifier with no frequency-selective device, the ASE ratio is reduced by a factor in excess of 10 to remain under 1.5% of the amplifier output whereas the total output energy is slightly increased by ~4%.