• Korean Journal of Optics and Photonics
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• v.8 no.5
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• pp.372-376
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• 1997

We study the time resolved anti-Stokes Raman spectroscopy with correlated pump and Stokes waves. When only two pump waves with relative delay are incident into a Raman medium, the Stokes waves generated by stimulated Raman scattering couple with the pump waves to generate anti-Stokes signal. Since the correlation between Stokes and the pump waves are not perfect and not quantified yet, we make a simple model fot it and calculate the normalized anti-Stokes signal intensities as a function of time delay. The broadband light regarded as chaotic field.

• The Science & Technology
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• v.9 no.5 s.84
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• pp.51-54
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• 1976

과학과 기술이 발달하고 생활수준이 높아질수록 에너지의 소비량은 누증된다. 이 중에도 특히 열에너지는 대부분 석유나 석탄에 의존할 수 밖에 없는 것이 우리나라의 실정인 것이다. 우리나라의 에너지 총소비량 54.169억둔(1975년도 상공부 에너지개발과 발표)을 어떻게 얼마나 석유와 석탄으로 충당해 나갈 수 있느냐가 문제인 것이다. 석유파동으로 한번 큰 쇼크를 받었었다. 석탄의 매장량에도 한계가 있다. 여기서 이에 대체할 수 있는 방법이 없을까 해서 온 세계는 태양열발전을 서두루고 천연개스 발전 또는 지하석유자원발굴에 혈안이 되고 있다. 그런데 아직까지도 효율이 좋고 필요한 양을 자유로히 입수할 수 있는 석유등의 화석연료가 있기 때문에 새로운 연료자원의 개발이나 보급이 잘 안되는 원인의 하나였다 하겠다. 그러나 오늘날 점점 석유는 양적 한계와 제적이 심해질 뿐 아니라 언제또 공급에 제동이 걸릴지 모르고 격증하는 에너지를 보완하기 위해서는 새로운 에너지원의 개발을 서두루지 않으면 않되게 된 것이다. 자연자원중에서도 원료공급량이 풍부하고 비교적 간단한 시설로 얻어지는 메탄개스를 이용해보자는 계획이 지난 '69년도부터 산림녹화, 농촌연료해결, 환경개선등을 위해 정부시책의 일환으로 전국 농촌에 「메탄개스」이용을 관장해 왔다. 그러나 경제적부담이 힘겨운 농가사정과 시설상의 불합리, 관리의 불편등으로 호흥을 못받고 있는 실정이다. 여기서 이러한 여러가지 미비점을 과학적인 분석과 연구를 거듭하여 마침내 실용가능성을 보인 창원탱크 Co.(허범진씨)의 삼원식 메탄개스 발삼정화조라 하겠다.

• Journal of Korean Society for Geospatial Information Science
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• v.18 no.1
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• pp.31-39
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• 2010

After oil shock, the importance of renewable energy has emerged and it came to the fore again as Korean government declared the policy on low-carbon green growth. Among various renewable energies, it is generally accepted that wind power is the most practical alternative. In this paper we showed the process of producing wind speed map from Gangwon Regional Meteorological Administration's 2008 data. We mapped monthly average and maximum wind speed and compared several interpolation methods applied to the weather data. This wind speed map, which reflects Gangwon's topographical and climatic regional characteristics, is expected to be a good tool for wind farm location analysis.

• Korean Journal of Optics and Photonics
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• v.20 no.6
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• pp.375-380
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• 2009

The scattering of a normally incident monochromatic light by optically active concentric double cylinders is studied by using a numerical method. A numerical code is developed on the basis of the analytical solutions, and the angular distributions of the intensity and the polarization of the scattered light are computed for some specific cases. The numerical code can be used to non-invasively determine the size, structure, and composition of a double cylinder with high accuracy by measuring the angular distribution of the scattered light by an experiment.

• Nuclear Engineering and Technology
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• v.4 no.2
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• pp.116-131
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• 1972

A fast neutron time-of-flight spectrometer has been constructed with suitable choice of target thickness and proton bombarding energy in Li$^{7}$ (p, n) Be$^{7}$ nuclear reaction for a continuous keV spectrum of neutrons at 0 degree in 1-nsec pulse from a Van do Graaff and a time-pick-up fast neutron detector assembled with a 5 mm-thick 92% enriched B$^{10}$ slab and four heavily shielded 4＂$\times$3＂ NaI scintillation detectors. Energy resolution of this spectrometer is better than 0.3% at 50 keV and the signal-to-background ratio is also improved. Total cross section measurements of several separated single isotopes have been carried out with this spectrometer and analyzed by Rmaxtrix multi-level computer code. The spin values and resonance parameters of each individual resonances are given.

• Development and Reproduction
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• v.2 no.2
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• pp.141-148
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• 1998

The fine structure of spermatozoa of Pungtungia herzi was examined with scanning and transmission electron microscopies. The spermatozoa of p. herzi are approximately 37.4 ${\mu}{\textrm}{m}$ in length and a relatively simple cell with a spherical nucleus, a short midpiece and a tail. The acrosome is not present as in most teleost fishes. The ultrastructure of spermatozoa represents typical characteristics of cyprinid spermatozoa including the lateral insertion of flagellum, the organization of centriolar complex in shallow nuclear fossa, and the occurrence and asymmetrical arrangement of mitochondria. In the nuclear envelope and mitochondrion, however there were some morphological differences for their ultrastructure. The nuclear envelope is severely undulated and the shallow nuclear fossa contains two centrioles which are at the angle of some 130$^{\circ}$ each other. The most significant feature can be observed with the mitochondrion; five or more mitochondria, which are shown in primary spermatocyte, fuse to form a single one in the mature spermatozoon. The mitochondrial aspect is different from that of other cyprinid spermatozoa, where their mitochondria have a conventional aspect and never fuse to form a mitochondrial derivative. In terms of sperm evolution the fused mitochondria are regarded as the apomorphic character in comparison with the separate mitochondria. The single mitochondrion is not reported in cyprinid spermatozoon except the case of Rhodeus.

• The Korean Journal of Petroleum Geology
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• v.12 no.1
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• pp.14-19
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• 2006

The electromagnetic (light) waves have a limitation to penetrate media, ie, water and sea-bottom layers, due to high energy attenuation, but acoustic (sound) waves play as the good messenger to gather the underwater target information. Therefore, the acoustic methods are applied to almost all of ocean equipments and technology in terms of in-water and sub-bottom surveys. Generally the sound character is controlled by its frequency. In case that the sound source is low frequency, the penetration is high and the resolution is low. On the other hand, its character is reversed at the high frequency. The common character at the both of light and sound is the energy damping according to the travel distance increase.

• Proceedings of the Korea Contents Association Conference
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• 2003.05a
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• pp.132-138
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• 2003

The caustic effect provides some of the most amazing indirect illuminated light patterns or scenery one could find in nature. We can perceive this in forms of twinkling stars, shimmering, visually deflected spoon in the water and other various occasions. To generate the caustic effect more realistic and effectively in 3D animation the understanding of the caustic effect and its application is very crucial. However, thor exists various factors in creating the caustic effect other than two main factors discussed in this paper and these factors will require to be studied and tested. In this report, various cases, which used the caustic effect to create more realistic scenery are studied and the role of the caustic effect played in various sceneries are analyzed. In addition to these case studies it is also experimented with changes in different conditions On the basis of the result of case studies, the report demonstrates how the caustic effect can be used to create more realistic scenery by conducting substantiate experiment and research on practicing 3D animation. With all of these researches, the paper is to present the education guide to produce more realistic scenery in 3D animation.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.24 no.4
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• pp.277-286
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• 2012

In the numerical simulation of wave fields using a multi-phase flow model that considers simultaneous flows of materials with different states such as gas, liquid and solid, there is need of an accurate representation of the interface separating the fluids. We adopted an algebraic interface capturing method called tangent of hyperbola for interface-capturing(THINC) method for the capture of the free-surface in computations of multi-phase flow simulations instead of geometrical-type methods such a volume of fluid(VOF) method. The THINC method uses a hyperbolic tangent functions to represent the surface, and compute the numerical flux for the fluid fraction functions. One of the remarkable advantages of THINC method is its easy applicability to incorporate various numerical codes based on Navier-Stokes solver because it does not require the extra geometric reconstruction needed in most of VOF-type methods. Several tests were carried out in order to investigate the advection of interfaces and to verify the applicability of the THINC method to wave fields based on the one-field model for immiscible two-phase flows (TWOPM). The numerical results revealed that the THINC method is able to track the interface between air and water separating the fluids although its algorithm is fairly simple.

• Geophysics and Geophysical Exploration
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• v.14 no.1
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• pp.98-104
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• 2011

Numerical simulation in exploration geophysics provides important insights into subsurface wave propagation phenomena. Although elastic wave simulations take longer to compute than acoustic simulations, an elastic simulator can construct more realistic wavefields including shear components. Therefore, it is suitable for exploration of the responses of elastic bodies. To overcome the long duration of the calculations, we use a Graphic Processing Unit (GPU) to accelerate the elastic wave simulation. Because a GPU has many processors and a wide memory bandwidth, we can use it in a parallelised computing architecture. The GPU board used in this study is an NVIDIA Tesla C1060, which has 240 processors and a 102 GB/s memory bandwidth. Despite the availability of a parallel computing architecture (CUDA), developed by NVIDIA, we must optimise the usage of the different types of memory on the GPU device, and the sequence of calculations, to obtain a significant speedup of the computation. In this study, we simulate two- (2D) and threedimensional (3D) elastic wave propagation using the Finite-Difference Time-Domain (FDTD) method on GPUs. In the wave propagation simulation, we adopt the staggered-grid method, which is one of the conventional FD schemes, since this method can achieve sufficient accuracy for use in numerical modelling in geophysics. Our simulator optimises the usage of memory on the GPU device to reduce data access times, and uses faster memory as much as possible. This is a key factor in GPU computing. By using one GPU device and optimising its memory usage, we improved the computation time by more than 14 times in the 2D simulation, and over six times in the 3D simulation, compared with one CPU. Furthermore, by using three GPUs, we succeeded in accelerating the 3D simulation 10 times.