• Bulletin of the Korean Mathematical Society
• /
• v.35 no.4
• /
• pp.837-845
• /
• 1998

In this work, we consider Euler approxiamtion for one-dimensional jump-diffusion processes under Yamada-Watanabe type conditions on the coefficients which turns out to converge to the strong solution in uniform $L^1$-sense.

• Proceedings of the Technology Innovation Conference
• /
• 1998.06a
• /
• pp.226-249
• /
• 1998

Technology diffusion policy can be defined as the role of government in linking knowledge production with usage. It has an importance due to the fact that linking knowledge between the producing agent and using agent does not automatically occur. If knowledge produced by an R&D agent is not used by somebody else, the knowledge may deteriorate to a social loss since knowledge production consumes a considerable degree of social resources. Explicit technology diffusion policies are not found in Korea. There we, however, a number of implicit policies to promote technology diffusion, mainly by promoting cooperation among universities, industries and research institutes. Government R&D programs have provided incentives for cooperative research projects, and many government sponsored institutes have been assigned the role of technology assistance for small and medium sized firms. Nevertheless, diffusion policies remain weak in comparison to other innovation and technology policies. This is reflected in the relatively small scale of government support for technology diffusion programs. In addition, there is no systematic approach between the different ministries for enhancing diffusion across technologies, institutions, sectors and regions. A comprehensive evaluation of government diffusion programs, which is necessary for improving policy and program design, is lacking. Enhancing the diffusion of technology in Korea will require the strengthening of policies at different levels, including; 1) increasing the orientation of science and technology policies towards diffusion; 2) increasing the scale of existing diffusion programs; 3) developing new diffusion programs, in particular sector-specific or manpower training programs; 4) developing policies to encourage a culture of cooperation that can facilitate technology diffusion; and 5) carrying out substantial policy research to develop diffusion policies.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.24 no.2
• /
• pp.248-253
• /
• 1987

Boron diffusion into silicon through poly\ulcorneri-SiO2 was carried out for the diffusion with low concentration using CVD-BN. The result of direct boron diffusion from BN into silicon and that of boron diffusion through SiO2 from BN into silicon was compared with the result of boron diffusion through poly-Si-SiO2 from BN into silicon. In the case of boron diffusion through poly Si-SiO2, the low concentration diffusion was obtained, that is the boron surface concentration in silicon Cs=10**16 Cm**-3, and the glassy compounds were not seen.

• International Journal of Aeronautical and Space Sciences
• /
• v.7 no.2
• /
• pp.50-55
• /
• 2006

Currently, a gas fueled diffusion flame is used for the relay torch system. It could be burned cleanly but should be stable at severe weather condition such as rain of up to 55 mm/h, winds of up to 70 km/h and also produce a highly bright yellow visible flame. This paper presents torch diffusion flame characteristics on the various wind speeds and rainfall conditions. From the results, flame lengths are controlled by the momentum flux ratio of fuel and ambient air flow and flame stability is much influenced by the mixing characteristics with air flow. Flame is fluctuated above than 200 mm/h rainfall and blow out is occurred about 300 mm/h rainfall condition.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2005.11a
• /
• pp.515-518
• /
• 2005

In recent years, many research works have been carried out in order to obtain a more controlled durability and long-term performance of concrete structures exposed to chloride environments. In particular, the development of new procedures for probability-based durability analysis and design has been proved to be very valuable. To carry out the procedures described above, the statistical properties of design valuables such as diffusion coefficient of chloride ion, surface chloride concentration, and chloride threshold value etc. should be known. For this purpose, this paper presents the statistical properties of the diffusion coefficient of chloride ion such as mean value and standard deviation with water-cement(w/c) ratio and curing conditions, respectively. It was observed from the test that the standard deviation for the diffusion coefficient of chloride ion was found to be small with decrease in the w/c ratio irrespective of curing conditions and that of standard curing was found to be smaller than that of field curing.

• 한국방재학회:학술대회논문집
• /
• 2007.02a
• /
• pp.177-180
• /
• 2007

Numerical simulations on the suspended load in the Do jang fish port are carried out. Suspended load is analysed by using the two-dimensional advection-diffusion equation. To describe behaviors of a pollutant in costal zone, a split-operator method is applied to the numerical model. The advection part is first solved by SOWMAC and then the diffusion part is solved by a three-level locally implicit scheme.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2001.11a
• /
• pp.221-226
• /
• 2001

Chloride diffusion effect of cement paste, freezing and thawing test, carbonation of concrete specimen were carried out using inorganic coating material. According to the chloride ions diffusion test, it is elucidated that permeability and diffusion coefficient of Cl￣ ions and apparent coefficient of coated cement paste is smaller than plain cement paste. A durability of coated concrete specimen was enhanced by the experiment result of concrete carbonation and freezing thawing test.

• Ocean and Polar Research
• /
• v.26 no.1
• /
• pp.43-50
• /
• 2004

The diffusion model, which considers diffusion and sorption, is proposed. The FEM program developed on the basis of the diffusion model provides the estimation of chloride concentration according to cyclic humidity and sorption. After the humidity diffusion analysis is carried out, the chloride ion diffusion and sorption analysis are conducted on the basis of the preestimated humidity data in each element. Each element has different analysis variables at different ages and locations. At early ages, the difference between inner and outer relative humidity causes the chloride ion penetration by sorption. As the humidity diffusion reduces the difference with age, the effect of sorption on the chloride ion penetration decreases. By the way, the cyclic humidity increases the effect of sorption on the chloride ion penetration at early ages, and the quantity of chloride ion around steel at later ages. Therefore, the in situ analysis of chloride ion penetration for marine concrete structures must be performed considering the cyclic humidity condition and the long term sorption.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
• /
• v.4 no.4
• /
• pp.263-271
• /
• 2000

To investigate the distribution of air pollutants dispersion in the horizontal wind fields, a chaff release experiment was carried out by an airplane. The temporal and spatial variations of a chaff plume from an elevated point source using the WSR-88D(NEXRAD) radar. The observed profiles of radar reflectivity were compared with the Gaussian diffusion model at slightly unstable atmospheric condition. The present study shows that the distributions of radar reflectivity from chaffs and their concentration by the model are in general agreement with time variation. The dispersion coefficients in downwind($\sigma$(sub)x) and crosswind($\sigma$(sub)y) spread data exceeded what has generally been found at Pasquill and Brigg\`s estimates. As a result, it was clearly shown that horizontal and vertical diffusion coefficients are more accurately determined as compared with theoretical coefficients. At longer diffusion distances(than 10km), a radar observation provided the determination of maximum range and diffusion height more qualitatively, too.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.20 no.3
• /
• pp.207-212
• /
• 2007

The concentration profiles of deep energy levels($E_c$ -0.23e V, $E_v$+0.36e V and $E_c$ -0.23e V) in platinum-diffused silicon have generally a sharp gradient in the vicinity of the surface of the silicon wafer. In this work two efficient methods are proposed to obtain the uniform concentration profiles throughout the silicon wafer. One is that the platinum diffusion is carried out at $1000^{\circ}C$ for 1h in oxygen atmosphere. In this case the values of obtained uniform concentration, $1{\times}10^{15}cm^{-3}$ for the $E_c$ -0.23e V level, and 1{\times}10^{14}cm^{-3}$ for the $E_c$ -0.52e V level, are very restricted, respectively. The other is two-step annealing process. The platinum diffusion is carried out at $850{\sim}1100^{\circ}C$ in a nitrogen ambient for 1h and then the annealing is performed at $1000^{\circ}C$ in oxygen ambient after removing platinum-source from the platinum diffused samples. The advantage of this method is that the uniform concentration of these levels required power devices can be controlled by setting the desired temperatures when the platinum diffusion is carried out in nitrogen ambient.