• Korean Journal of Optics and Photonics
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• v.20 no.4
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• pp.249-254
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• 2009

In our study, the Hanle spectrum and nonlinear magneto-optic effect (NMOE) signals were observed as a function of magnetic field on $D_1$ line of $^{87}Rb$ atoms contained in a paraffin coated vapor cell. We observed the double structure from the Hanle and the NMOE spectrum in the paraffin coated Rb vapor cell. The narrow spectral width of the narrow resonance signal is approximately 1 kHz and the magnitude is approximately 10 percent of the total spectrum. Also, the NMOE signals corresponding to the Hanle configuration consisted of two different dispersion-like features. At the near zero magnetic field, a sharp slope signal was centered, and its value was 10 mV/${\mu}T$ with laser power was $200{\mu}W$.

• Journal of the Korean Society of Radiology
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• v.16 no.1
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• pp.15-23
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• 2022

3D printing technology is being used in various fields such as medicine and biotechnology, and materials containing metal powder are being commercialized through recent material development. Therefore, this study intends to analyze the photon spectrum during added filtration using 3D printing material during diagnostic X-ray examination through simulation. Among the Monte Carlo techniques, MCNPX (ver. 2.5.0) was used. First, the appropriateness of the photon spectrum generated in the simulation was evaluated through SRS-78 and SpekCalc, which are X-ray spectrum generation programs in the diagnostic field. Second, photon spectrum the same thickness of Al and Cu filters were obtained for characterization of 3D printing materials containing metal powder. In addition, the total photon fluence and average energy according to changes in tube voltage were compared and analyzed. As a result, it was analyzed that PLA-Al required about 1.2 ~ 1.4 times the thickness of the existing Al filter, and PLA-Cu required about 1.4 ~ 1.7 times the thickness of the Cu filter to show the same degree of filtration. Based on this study in the future, it is judged that it can be utilized as basic data for manufacturing 3D printing additional filters in medical fields.

• Korean Journal of Optics and Photonics
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• v.1 no.1
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• pp.1-6
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• 1990

We studied two-photon-resonant three-photon ionization processes via 4D[channel #1] and 5S(channel #2] intermediate state of Na atom in a quartz ionization cell. For each channel. the bandwidth of ionization spectrum increased linearly with laser intensity and the ionization signal followed J3 dependence at low intensity. Compared with channel # 1 . ionization signal of channel #2 was enhanced by a factor of 20 - 25. The measured AC Stark shift factor of 3S - 4I) transition was $174\pm60MHz/MW/textrm{cm}^2$..

• Korean Journal of Optics and Photonics
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• v.16 no.6
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• pp.490-493
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• 2005

We have experimentally studied supercontinuum generation in a photonic crystal fiber as a function of pump wavelength and intensity with 100 fs pulsewidth. A supercontinuum over 750 nm spectral width with amplitude variation less than 10 dB has been achieved. It was generated by coupling femtosecond pulses from a mode-locked Ti:Sapphire laser into a 2 m long photonic crystal fiber. Adjusting the parameters of the pump source, it was also possible to control different spectral features of the supercontinuum radiation.

• Journal of the Korean Society of Radiology
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• v.8 no.5
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• pp.249-254
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• 2014

Medical linear accelerator is used for radiotherapy since it was developed in 1952, the utilization rate is further increased. It is used high energy radiotherapy using the energy of the photon of 6 MeV or more is universal at present, but the creation of the neutron by photonuclear reaction cause a problem that is radiation exposure of patients and operators. Therefore, in this study, to analyze the spectrum of the photon beam of 6 to 24 MV that occurred in the medical linear accelerator using the Monte Carlo code MCNPX, the number of photons of 7.41 MeV or more, which is a neutron production threshold energy of tungsten and average energy. The result of 24 MV in the beginning and the 8 MV was 0.59% of the total number of detected photons and it was founded that the number of photons are increased which are possible to cause the photonuclear reaction.

• Proceedings of the Optical Society of Korea Conference
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• 1990.02a
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• pp.185-189
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• 1990

고강도 레이저 장에서 마그네슘 원자의 다광자 이온화에 미치는 레이저 parameter의 영향을 Time-of-Flight spectrometer를 사용하여 분광학적 방법으로 연구하였다. 진공 챔버 속에서 파장 532nm와 1064nm인 레이저 펄스를 강도 1010-13W/'$ extrm{cm}^2$ 범위내에서 변화시키며 마그네슘 원자와 반응시켜서 Mg+ 및 Mg2+ 이온을 생성시켰으며 레이저의 파장, 강도 및 편광에 따른 광전자 스펙트럼을 구하였다. 또한, 전자 두 개를 방출하고 생성된 Mg2+ 이온의 발생 기구에 대하여 논하였다.

• Proceedings of the Optical Society of Korea Conference
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• 2003.02a
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• pp.204-205
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• 2003

미량기체의 흡수스펙트럼을 높은 감도로 측정하는 공동 광자감쇠 분광법(cavity ringdown spectroscopy； CRDS)을 나노초 레이저 펄스의 차주파수 생성(difference-frequency generation； DFG)을 광원으로 이용하여 파장 3 ~ 4 $\mu\textrm{m}$ 영역에서 구현하였다. CRDS는 고반사율 거울로 이루어진 광학적 공동에 단일 파장의 빛을 가두었다가 그 에너지의 시간적 감소율을 측정하여 공동 속 기체의 흡수율을 알아내는 방법이다. (중략)

• Progress in Medical Physics
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• v.8 no.2
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• pp.35-43
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• 1997

The knowledge of x-ray spectra is highly desirable in some investigation involves the differential penetrating power and absorption coefficient correction of various photon beam. The transmission data were obtained from the 80 kVp and 120 kVp of CT x-ray beam with the aluminium filter which is designed in a 30 cm of diameter and pipe-typed filter was prepared from 5.0 mm upto 92.3 mm of thickness. To obtain the reconstructed spectra of CT x-ray, the investigator used the iterative numerical analysis which has been extended to include the tungsten characteristics from experimental transmission data with energy interval of 2 keV. Comparison of the calculated transmission data from the reconstructed spectra with that of measurement shows good agreement in both 80 kVp and 120 kVp x-ray beams. This numerical analysis based on iteratively calculation of fractional exposure per energy interval shows the high potential of usefulness of determination the x-ray spectra from the attenuated beam in diagnostic energy range.

• Korean Journal of Optics and Photonics
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• v.18 no.2
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• pp.100-104
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• 2007

We have measured the optical spectra while varying the temperature of photonic crystal fibers (PCFs) with periodic air holes in the cladding. These are liquid crystal infiltrated fibers. For the liquid crystal infiltrated PCFs, we obtained the transmission of several wavelengths at specific temperatures. The transmission power could be reduced by about $10\sim15dB$ by varying the applied temperature in the liquid crystal PCF. We expect that it is applicable as a wavelength switching device in the specific wavelength band.

• Proceedings of the Optical Society of Korea Conference
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• 2008.07a
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• pp.137-138
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• 2008