• KDI Journal of Economic Policy
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• v.38 no.4
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• pp.77-94
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• 2016

This paper examines the empirical magnitude of local human capital spillovers in Korea during the 1980s and mid-1990s. Local human capital spillovers exists if plants in regions with a higher level of human capital can produce more given their own amount of input (Moretti 2004c). In particular, this paper explores an educational reform in South Korea which exogenously induced a large amount of variation in regional human capital levels. Using annually collected plant level data, I explore the effect of changes in the regional human capital levels induced by this reform on plant productivity in Korea. My results suggest that this effect is limited. I find a positive correlation between a regional level of human capital and plant productivity. However, after further addressing endogeneity using an instrumental variable, the effect of the overall regional human capital level on productivity decreases and becomes statistically insignificant.

• The KSFM Journal of Fluid Machinery
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• v.13 no.3
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• pp.59-64
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• 2010

To analyze the three-dimensional flow in tunnel caused by operation of jet fan, both experimental and computational studies have been conducted. The experimental analysis of tunnel flow induced by jet fan is conducted on a real-scale apparatus with jet fan and tunnel, and air velocity at the monitoring points is measured for variation of fan's RPM. The three-dimensional numerical analysis including tunnel and jet fan is carried out for the same geometric configuration as the experimental analysis. The experimental and computational results are compared to examine the applicability of the numerical method.

• Proceedings of the KSME Conference
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• 2001.11b
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• pp.444-449
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• 2001

A numerical parametric study is conducted to simulate shock-induced combustion with a variation in freestream conditions. A steady combustion front is established if the freestream Mach number is above the Chapman-Jouguet speed of the mixture. On the other, an unsteady reaction front is established if the the freestream Mach number is below or at the Chapman-Jouguet speed of the mixture. The three cases have been simulated for Machs 4.18, 5.11, and 6.46 with a projectile diameter of 15 mm. Machs 4.18 and 5.11 shows an unsteady reaction front, whereas Mach 6.46 represents a steady reaction front. Thus Chapman-Jouguet speed is one of deciding factor for the instabilities to trigger.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.390.1-390
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• 2002

In this study, we investigate the plugging effect on the CE type steam generator tube. The natural frequency and mode shape will be changed due to decrease of the effective mass distribution along the tube. We compared the variation of stability ratio for plugged tube with that fur unplugged one. The natural frequency increased because of removing the cooling water inside the steam generator tube, but the stability ratio decreased inversely because of changing the vibrational mode shape. We also investigated the turbulent excitation effect.

• Current Optics and Photonics
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• v.1 no.6
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• pp.649-654
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• 2017

In this communication, we present an expression to determine thermal lensing in isotropic materials. The heat equation is analytically solved when a Gaussian spatial laser beam profile is introduced to a cylindrical geometry of optics using a complete set of Bessel functions. This expression permits explicit calculation of variation of focal length induced by thermal lensing and allows thermal effects for various material parameters on the optics. We applied our model to a high absorption material (Ti:sapphire) and also transparent material (thallium garnet or TGG) and found that the thermal lensing can be reduced more than 4 times by adjusting the laser beam waist and optics dimensions. Our analysis is completely general and applicable to any optical system.

• Computers and Concrete
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• v.12 no.1
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• pp.91-107
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• 2013

Corrosion of RC bridge decks eventually leads to delamination, severe cracking and spalling of the concrete cover. This is a prevalent deterioration mechanism and demands for the most costly repair interventions during the service life of bridges worldwide. On the other hand, decisions for repairs are usually made whenever the extent of a limit crack width, reported in routine visual inspections, exceeds an acceptable threshold level. In this paper, while random fields are applied to account for spatial variation of governing parameters of the corrosion process, an analytical model is used to simulate the corrosion induced crack width. However when dealing with random fields, the Monte Carlo simulation is apparently an inefficient and time consuming method, hence the utility of neural networks as a surrogate in simulation is investigated and found very promising. The proposed method can be regarded as an invaluable tool in decision making concerning maintenance of bridges.

• Korean Journal of Pharmacognosy
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• v.23 no.3
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• pp.137-141
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• 1992

The cells of Rubia cordifolia var. pratensis were transformed by Agrobactrium tumefaciens strain 11157. Surface-sterilized young leaves and stems of the plants were cocultivated with bacterial suspensions. Crown galls induced from stems were cultured with variation of culturing conditions and compared with untransformed cells. The growth rates and production of anthraquinone pigments of cells were remarkably improved by transformation. Furthermore, hairy roots were induced by inoculation or cocultivation with Agrobacterium rhizogenes strains.

• Korean Journal of Plant Resources
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• v.11 no.2
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• pp.195-201
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• 1998

Some morphological character were surveyed and PR-proteinases were induced and characterized from Lilium formosanum Wallace endeimc to Cheju island . Its flower characters were similar to those of white trumpet lilies(Lilium longiflorum Thunb) although its flowering period was later than that of white trumpet lilies and it hadd a wide range of variation among individuals. Six PR-proteinases(II-2, III-1, III-2, IV-1, IV-2 and V) were induced from bulbs by 2.5mM salicylic acid and almost excreted into the intercellular spaces. These PR-proteinases were strongly activated by Ca 2+, , whereas they were strongly inhibited by Cu2+ Co2+ and Fe2+ . Three PR proteinases(II-2, IV-1 and IV-2) were strongly inhibited by 1, 10 -phenanthroline, indicating that these enzymes are metallo-proteinases. Three PR-proteinases(III-1, III-2 and V) had a high sensitivity to PMSF and required $\beta$-mercaptoethanol for their activities. These results indicate that these proteinases are cysteine proteinases.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1241-1242
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• 2006

Electromagnetic properties of $CeO_2$ doped and undoped YBaCuO superconductors were evaluated to investigate the effect of pinning center on the magnetization and magnetic shielding. The variation $\DeltaM$ with doping was maximum for 3% doping and decrease with further doping. The magnetic shielding was evaluated by measuring the induced voltage in secondary coil and the voltage initially set to 0.5V, decreased to 0.17V and 0.28V respectively for the undoped and 3% $CeO_2$ doped sample. The much less change in the induced voltage for the 3% doped sample is attributed to the increased flux shielding by shielding vortex current. The $CeO_2$ was converted to fine $BaCeO_3$ particles which were trapped in YBaCuO superconductor during the reaction sintering. The trapped fine particles, $BaCeO_3$ may be acted as a flux pinning center.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2029-2032
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• 2008

In this study, we have investigated the effects of upstream rectangular winglet pair (RWP) on the heat/mass transfer coefficients in a dimple. Dimple print diameter was fixed at 20mm and the dimple depth was 4.0mm (0.4H). The dimple surface was coated with naphthalene for mass transfer experiment and the test plate was positioned at a rectangular straight duct whose aspect ratio (W/H) was 20. A rectangular winglet pair was positioned at y/d=-2.5. The RWP angle ($\beta$) was varied from $15^{\circ}$ to $60^{\circ}$. The Reynolds number, based on the duct height (H), was 5,000. with changing the RWP angle ($\beta$), the induced vortices had different flow characteristics; longitudinal or transversal vortices. These variation of induced vortices affected on the heat/mass transfer characteristics in the dimple.