• Proceedings of the Optical Society of Korea Conference
• /
• 2009.10a
• /
• pp.235-236
• /
• 2009

파장이 길고 에너지가 낮은 근적외선 영역 광자 두 개를 동시에 여기했다가 형광으로 방출하는 비선형 현상을 이용한 이광자 현미경은 살아있는 세포를 넘어 생체조직 깊은 곳에서 일어나는 생물학적 변화 관찰 및 3차원 이미지 해석이 가능한 매우 효과적인 장비이다. 그러나 상용화된 이광자 현미경은 매우 고가이고 응용의 다양성을 위한 구조적 변형이 매우 힘들다. 본 논문에서는 모드잠김 이터븀 광섬유 레이저를 이용하여 비용 효율이 높고 다루기 쉬운 이광자 현미경을 구현 하고자 한다.

• KCID journal
• /
• v.14 no.2
• /
• pp.225-235
• /
• 2007

The shape of streamflow hydrograph during the early period of spring is very much controlled by the area and depth of snow cover especially in mountainous area. When we simulate the streamfolw of a watershed snowmelt, we need some information for snow cover extent and depth distribution as parameters and input data in the hydrological models. The purpose of this study is to suggest an extraction method of snow cover area and snow depth distribution using Terra MODIS image. Snow cover extent for South Korea was extracted for the period of December 2000 and April 2006. For the snow cover area, the snow depth was interpolated using the snow depth data from 69 meteorological observation stations. With these data, it is necessary to run a hydrological model considering the snow-related data and compare the simulated streamflow with the observed data and check the applicability for the snowmelt simulation.

• Coupled systems mechanics
• /
• v.9 no.3
• /
• pp.219-235
• /
• 2020

Natural convection of nanofluid flow between two vertical flat plates has been analyzed in uncertain environment.Anon-Newtonian fluid SodiumAlginate (SA) as base fluid and nanoparticles ofCopper(Cu) are taken into consideration. In thepresentstudy,we have takennanoparticle volume fraction as an uncertain parameterin terms offuzzy number. Fuzzy uncertainties are controlled by r-cut and parametric concept. Homotopy PerturbationMethod (HPM) has been used to solve the governing fuzzy coupleddifferential equationsforthe titled problem.Forvalidation, presentresults are comparedwith existingresultsforsome special casesviz. crisp case andthey are foundto be ingood agreement.

• Proceedings of the KOSOMBE Conference
• /
• v.1996 no.05
• /
• pp.235-239
• /
• 1996

In recent years, the optical properties of multiple-scattering media like tissue have been studied for their potential applications in medicine. In this work the optical properties of multiple scattering media were investigated using the time-resolved reflectance measurement. The reflected light was measured by time-correlated single photon counting system. The transport scattering and absorption coefficient are related to the initial rapid decay and the subsequent decay in reflected light, respectively. Also the optical properties of the samples were measured by conventional method, ie., using continuous wave light. When the distance between the light source and the detector is over 8mm, the optical coefficient can be measured accurately using the suggested method.

• Proceedings of the KIPE Conference
• /
• 2012.07a
• /
• pp.234-235
• /
• 2012

본 연구는 가정에서 사용하는 부하는 IT 직류 부하가 증가함에 따라서 기존의 배전망이 내재하고 있는 변환 손실을 줄이고자 직류와 교류를 동시에 사용하는 Hybrid 배전을 적용하여 실제 데이터 분석을 통하여 Hybrid 배전시스템에 대한 연구하였다.

• Nuclear Engineering and Technology
• /
• v.49 no.6
• /
• pp.1234-1239
• /
• 2017

Basic research on the accelerator-driven system is conducted by combining $^{235}U$-fueled and $^{232}Th$-loaded cores in the Kyoto University Critical Assembly with the pulsed neutron generator (14 MeV neutrons) and the proton beam accelerator (100 MeV protons with a heavy metal target). The results of experimental subcriticality are presented with a wide range of subcriticality level between near critical and 10,000 pcm, as obtained by the pulsed neutron source method, the Feynman-${\alpha}$ method, and the neutron source multiplication method.

• Nuclear Engineering and Technology
• /
• v.56 no.4
• /
• pp.1250-1253
• /
• 2024

Activity measurement of the primary circuit water of fission reactors is one method that can provide early detection of a damaged fuel assembly in the reactor core. This is an important aspect in the safe operation of the reactor and for radiation protection of staff. Radionuclides in the primary circuit water are produced by the activation of stable nuclides and the fission of fissile nuclides, mainly the isotope ²³⁵U. In the LVR-15 research reactor, measurement of the activity of the primary circuit water has been regularly undertaken since 1996. A water sample is taken from the primary circuit every week and the activities are measured four days later using gamma spectrometry. The results of these long-term measurements from 1996 to 2022 are presented. The activity time dependences of the individual radionuclides are discussed in relation to fuel assembly damage and for events connected to contamination of the water by objects inserted into the primary circuit during experiments carried out near the reactor core.

• Journal of Radiation Industry
• /
• v.17 no.1
• /
• pp.93-100
• /
• 2023

This study analyzes the neutron shielding performance of Soft Magnetic Material and proposes a military application. In general, the military protection facility has been constructed with thick concrete, so Soft Magnetic Material, consisting of boron, was used with concrete in this study. To do so, Monte-Carlo N-Particle (MCNP) was applied to simulate the Watt-fission neutron spectrum of ²³⁵U and ²³⁹Pu. As a result, a configuration of polyethylene and Soft Magnetic Material is evaluated about four times better than borated polyethylene concerning the atomic weight of boron inside each shielding material. Also, when a nuclear weapon explosion is simulated in MCNP, 1 mm of Soft Magnetic Material with 20 cm of concrete shows about 55% more additional neutron shielding performance compared to when Soft Magnetic Material is not used. In this work, the neutron shielding performance of Soft Magnetic Material could be identified and Soft Magnetic Material would be useful for neutron shielding if applicable to concrete structure.

• Nuclear Engineering and Technology
• /
• v.54 no.1
• /
• pp.1-10
• /
• 2022

This study discusses the effect of using ²³²Th instead of ²³⁸U on the neutronic characteristics and the main operating parameters of the pressurized water reactor (PWR). MCNPX version 2.7 was used to compare the neutronic characteristics of UO₂ with (Th, ²³⁵U)O₂ and (Th, ²³³U) O₂. Firstly, the infinity multiplication factor (K_inf), thermal neutron flux, and power distribution have been studied for the investigated fuel types. Secondly, the effect of Gd₂O₃ and Er₂O₃ on the K_inf and on the radial thermal neutron flux and thermal power has been investigated to distinguish which of them is more suitable than the other in reactivity management. Thirdly, to illustrate the effectiveness of ²³²Th in decreasing the inventory of both the actinides and non-actinides, the concentration of plutonium (Pu) isotopes and minor actinides (MAs) has been simulated with the fuel burnup. Besides, due to their large thermal neutron absorption cross-section, the concentrations of ¹³⁵Xe, ¹⁴⁹Sm, and ¹⁵¹Sm with the fuel burnup have been investigated. Finally, the main safety parameters such as the reactivity worth of the control rods (ρ_CR), the effective delayed neutron fraction β_eff, and the Doppler reactivity coefficient (DRC) were calculated to determine to which extent these fuel types achieve the acceptable limits.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
• /
• v.13 no.2
• /
• pp.155-161
• /
• 2015

Technetium-99m (^99mTc) is an important, short-lived decay product of molybdenum-99 (⁹⁹Mo), and it is considered the backbone of the modern nuclear diagnostic procedures. Since fission of ²³⁵U is the main source of production of ⁹⁹Mo, either highly-enriched uranium (HEU) targets or low-enriched uranium (LEU) targets are irradiated in the research reactors. The use of LEU targets is being promoted by the international community to avoid the proliferation issues linked with the use of HEU. In order to define the waste management strategy at the planning stage of establishment of an LEU based ⁹⁹Mo production facility, the impact of the use of LEU targets on the radioactive waste stream of the ⁹⁹Mo production facility was analyzed. Because the volume of uranium waste is estimated to increase six times, the use of high uranium density targets and the utilization of hot isostatic pressing were recommended to reduce the increased waste volume from the use of LEU based targets.