• Journal of Korea Technology Innovation Society
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• v.10 no.3
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• pp.383-405
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• 2007

In this paper we estimate knowledge production function for 15 South Korean industry sectors using panel data. To accommodate the influence of inter-sectoral interactions on the creation of knowledge, we estimate parameters for related knowledge production functions using the Dynamic Seemingly Unrelated Regression(DSUR) model proposed by Mark et al. (2005). We find the elasticity of knowledge production with respect to the size of research staff to be 0.25 and that with respect to the existing stock of knowledge to be 0.35. The fact that the elasticity of new knowledge creation with regard to the existing knowledge stock is below 1 in South Korea corroborates the view that the rate of long-term growth of her economy is chiefly determined by the elasticity related to production functions of goods and services and the rate of population growth, and that her government policy, to ensure a continued growth for the Korean economy, must shift the focus of R&D policies from the current direct intervention-centered model to one consisting of indirect measures, namely supporting knowledge management and diffusion and the creation of a knowledge sharing system. In terms of R&D policy implications it could be consider that the national knowledge production system should strengthen the cumulative process of knowledge accumulation and population for research and development. Our country R&D policy, also, need to adopt a global approach to increase knowledge stock at the highest levels of a country.

• Journal of the Economic Geographical Society of Korea
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• v.9 no.3
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• pp.297-317
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• 2006

This article is aimed to find a more successful way to build a metropolitan-wide governance for enhancing industrial cluster in South-East region, Korea. We begin a research with reviewing a current study of regional cluster and its governance. New industrial system and agglomeration changed regional growth theory and urban system. In traditional system, a central city dominated economy of the metropolitan area. However, with development of new transportation and communication technology, a central city lost their superiority to suburban cities. In other words, growing competition between central and suburban cities changed traditional concentration and diffusion theory of urbanization which dominated urban geography for last decades. Next, current situation of development of industrial cluster in South-East region is examined to suggest policy for more competitiveness. South-East region has grown as the most prominent cluster of mechanical engineering and metal industry in Korea since the late 1970s. In the form of agglomeration and network of a specific and its related industry, South-East region has formed a linear industrial belt along with the inter-regional South Coast Highway and contain about ten industrial cities. Accompanying with this growing South-East region, a problem has risen from geographic mismatch between metropolitan-wide industrial cluster and its administrative boundary. Since industrial cluster has no specific administrative boundary, adequate government support for developing industrial cluster has not been provided. Responding to the problem, academics and policy makers maintain need in establishing a metropolitan-wide governance for supporting a cluster. At the end, this paper provides some implication to planners and policy makers.

• Journal of the Korean Magnetics Society
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• v.11 no.2
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• pp.72-77
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• 2001

Top spin valve films with PtMn antiferromagnetic layers were deposited using a multi-target dc magnetron sputtering in (100)Si substrates overcoated with 500 $\AA$ of Al$_2$O$_3$. Firstly, the post-deposition annealing was performed at 270$\^{C}$ in a unidirectional magnetic field of 3 kOe to induce the crystallographic transformation of the PtMn layer from a fcc (111) to a fct (111) structure. Secondly, the spin valve films were annealed without magnetic fields and magnetic properties were measured. In Si/A1$_2$O$_3$ (500$\AA$)/Ta(50$\AA$)NiFe(40$\AA$)/CoFe(17$\AA$)/Cu(28$\AA$)/CoFe (30$\AA$)PtMn(200$\AA$)Ta(50$\AA$) top spin valve samples, the MR ratio decreased slowly with increasing annealing temperature up to 325$\^{C}$. But above 325$\^{C}$, the MR ratio decreased rapidly to 1%, due to a collapse of the exchange coupling between a antiferromagnetic layer and a pinned layer with increasing annealing temperature. Also above 325$\^{C}$, the exchange biased field rapidly decreased and the interlayer coupling field rapidly increased with increasing annealing temperature. A change in the interlayer coupling field was resulted from the increase in interface roughness due to Mn-interdiffusion through the grain boundaries. We confirmed the temperature in changing magnetic properties agreed well with the blocking temperature of PtMn based spin valve structure.

• Journal of the Korean Society for Precision Engineering
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• v.3 no.1
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• pp.40-49
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• 1986

Crack, craze and void are common defects which may be found in the bulk of polymeric materials such as either themoplastics or thermosets. The healing phenomena, autohesion, of these defects are known to be a intrinsic material property of various polymeric materials. However, only a few experimental and theoretical investigations on crack, void and craze healing phenomena for various polymeric materials have been reported up to date [1, 2, 3]. This may be partly due to the complications of healing processes and lacking of appropriate theoretical developments. Recently, some investigators have been urged to study the healing phenomena of various polymenic materials since the significance of the use of polymer based alloys or composites has been raised in terms of specific strength and energy saving. In the earlier published reports [1, 2, 3, 4], the crack and void healing velocity, healing toughness and some other healing mechanical and physical properties were measured experimentally and compared with predicted values by utilizing a simple model such as the reptation model under some resonable assumptions. It seems, however, that the general acceptance of the proposed modeling analyses is yet open question. The crack healing processes seem to be complicate and highly dependent on the state of virgin material in terms of mechanical and physical properties. Furthermore, it is also strongly dependent on the histories of crack, craze and void development including fracture suface morphology, the shape of void and the degree of disentanglement of fibril in the craze. The rate of crack healing may be a function of environmental factors such as healing temperature, time and pressure which gives different contact configurations between two separated surfaces. It seems to be reasonable to assume that the crack healing processes may be divided in several distinguished steps like stress relaxation with molecular chain arrangement, surface contact (wetting), inter- diffusion process and com;oete healing (to obtain the original strength). In this context, it is likely that we no longer have to accept the limitation of cumulative damage theories and fatigue life if it is probable to remove the defects such as crack, craze and void and to restore the original strength of polymers or polymer based compowites by suitable choice of healing histories and methods. In this paper, we wish to present a very simple and intuitive theoretical model for the prediction of healed fracture toughness of cracked or defective polymeric components. The central idea of this investigation, thus, may be the modeling of behavior of chain molecules under healing conditions including the effects of chain scission on the healing processes. The validity of this proposed model will be studied by making comparisons between theoretically predicted values and experimentally determined results in near future and will be reported elsewhere.

• Journal of the Korean Ceramic Society
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• v.42 no.2 s.273
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• pp.104-109
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• 2005

To study the role of PbO as the buffer layer, Pt/PZT/PbO/Si with the MFIS structure was deposited on the p-type (100) Si substrate by the r.f. magnetron sputtering with $Pb_{1.1}Zr_{0.53}Ti_{0.47}O_3$ and PbO targets. When PbO buffer layer was inserted between the PZT thin film and the Si substrate, the crystallization of the PZT thin films was considerably improved and the processing temperature was lowered. From the result of an X-ray Photoelectron Spectroscopy (XPS) depth profile result, we could confirm that the substrate temperature for the layer of PbO affects the chemical states of the interface between the PbO buffer layer and the Si substrate, which results in the inter-diffusion of Pb. The MFIS with the PbO buffer layer show the improved electric properties including the high memory window and low leakage current density. In particular, the maximum value of the memory window is 2.0V under the applied voltage of 9V for the Pt/PZT(200 nm, $400^{\circ}C)/PbO(80 nm)/Si$ structures with the PbO buffer layer deposited at the substrate temperature of $300^{\circ}C$.

• Environmental and Resource Economics Review
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• v.19 no.1
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• pp.129-157
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• 2010

This paper is intended to evaluate energy efficiency policy in demand side, to assess the residential sector's energy efficiency policy and to analyze the system of energy efficiency practices. We examined residential energy consumption over the period 1990~2006. The decomposition method in the analysis was a logarithmic mean Divisia index (LMDI) techniques to decompose changes in energy intensity. First of all, the energy use in residential sector was adjusted to correct weather-induced variations in energy consumption, because adjustments for normal weather patterns facilitated inter-temporal comparison of intensity. The analysis on the residential sector shows that the overall energy intensity of the residential sector declined at an average 1.0% per year, while the structure effect increased by 1.8% per year, and the activity effect increased by 0.7% per year. In other words, the decline of floor space, number of household, and appliance ownership per capita has an effect on increase in residential consumption. The improvement in energy efficiency had strong contribution on the decrease of energy consumption. We find that the general results of analysis on residential energy are similar to those of IEA. The energy efficiency policy in residential sector is assessed to obtain some results during 1990~2006. In residential sector, structural variables such population per household, diffusion of appliance and activity factor such as population contributed to the increase of energy consumption while energy intensity effect induced the decrease of energy consumption. These findings are consistent with international trend as well as our prior expectation.

• Journal of Korean Society for Atmospheric Environment
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• v.21 no.4
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• pp.439-458
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• 2005

An automated analysis system for water soluble constituents in $PM_{2.5}$ has been developed. The system consists of a high capacity multi tube diffusion scrubber (MTDS), a low temperature particle impactor (LTPI), and two ion (anion and cation) chromatography (IC) systems. Atmospheric particles have been collected by passing sample air through a thermostated MTDS followed by a LTPI. This system allows simultaneous measurements of soluble ions in $PM_{2.5}$ at 30 minutes interval. At the air sampling flow rate of 1.0L/min, the detection limits of the overall system are in the order of tens of $ng/m^3$. This system has been successfully used for the measurement of particulate components of Seoul air from April 2003 to January 2004. $SO_4^{2-},\;NO_3^-,\;NH_4^+,\;NO_2^-,\;Cl^-,\;Na^+,\;K^+,\;Ca^{2+},\;and\;Mg^{2+}$ are the major ionic species for $PM_{2.5}$ at Seoul. Among them, $SO_4^{2-},\;NO_3^-\;and\;NH_4^+$ are the most abundant ions, contributed up to $86\%$ of the total and the concentrations were higher than those in any other urban sites in the world except for Chinese cities. There are high pollutant episodes which contribute about $15\~20\%$ of annual average values of the major ions. During the episode, the all parcels were transported from the asian continent and $PM_{2.5}$ were significantly neutralized. This suggests that aged and long range transported pollutants caused the high pollutant episodes. They showed a distinct daily and seasonal variations:they showed a peak in the early morning caused by the night-time accumulation of particulate matters. Atmospheric reactions including gas-to-particle reactions and inter-particle reactions and meteorological parameters including relative humidity and ambient temperature were described with related to the $PM_{2.5}$ 5 concentrations. All of the ionic species showed higher concentrations during the spring than those for summer and winter.

• Journal of the Korean Magnetics Society
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• v.22 no.2
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• pp.37-41
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• 2012

The Ag nanoparticles attached $La_{0.7}Sr_{0.3}Co_{0.3}Fe_{0.7}O_{3-{\delta}}$ (LSCF) perovskites were prepared by plasma method. The Ag nanoparticles with size of several nanometers deposited from the Ag target were coated on the surface of LSCF powders with size range from 0.2 to 3 ${\mu}m$. The agglomeration of Ag particles annealed at $800^{\circ}C$ under inert gas of Ar were rarely observed. The inter-diffusion between surface Ag and core LSCF is effectively strong to prevent aggregation of Ag nanoparticles. The wave number of FT-IR spectra for LSCF were largely shifted as the concentration of Ag on LSCF up to 2.11 wt.%. The ionic states of irons in LSCF were measured by M$\ddot{o}$ssbauer spectroscopy. The small amount of $Fe^{4+}$ ions are converted to $Fe^{3+}$ ions after Ag nanopartcles were coated on LSCF.

• Journal of the Korean Vacuum Society
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• v.19 no.3
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• pp.217-223
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• 2010

We grew multi-stacked InAs/$In_{0.1}Ga_{0.9}As$ DWELL (dot-in-a-well) structure by metal organic chemical vapor deposition and investigated optical properties by photoluminescence and I-V characteristics by dark current measurement. When stacking InAs quantum dots (QDs) with same growth parameter, the size and density of QDs were changed, resulting in the bimodal emission peak. By decreasing the flow rate of TMIn, we achieved the uniform multi-stacked QD structure which had the single emission peak and high PL intensity. As the growth temperature of n-type GaAs top contact layer (TCL) is above $600^{\circ}C$, the PL intensity severely decreased and dark current level increased. At bias of 0.5 V, the activation energy for temperature dependence of dark current decreased from 106 meV to 48 meV with increasing the growth temperature of n-type GaAs TCL from 580 to $650^{\circ}C$. This suggest that the thermal escape of bounded electrons and non-radiative transition become dominant due to the thermal inter-diffusion at the interface between InAs QDs and $In_{0.1}Ga_{0.9}As$ well layer.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.4
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• pp.301-307
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• 2002

Direct bonded SOI wafer pairs with $Si ll SiO_2/Si_3N_4 ll Si$ the heterogeneous insulating layers of SiO$_2$-Si$_3$N$_4$are able to apply to the micropumps and MEMS applications. Direct bonding should be executed at low temperature to avoid the warpage of the wafer pairs and inter-diffusion of materials at the interface. 10 cm diameter 2000 ${\AA}-SiO_2/Si(100}$ and 560 $\AA$- ${\AA}-Si_3N_4/Si(100}$ wafers were prepared, and wet cleaned to activate the surface as hydrophilic and hydrophobic states, respectively. Cleaned wafers were pre- mated with facing the mirror planes by a specially designed aligner in class-100 clean room immediately. We employed a heat treatment equipment so called fast linear annealing(FLA) with a halogen lamp to enhance the bonding of pre mated wafers We kept the scan velocity of 0.08 mm/sec, which implied bonding process time of 125 sec/wafer pairs, by varying the heat input at the range of 320~550 W. We measured the bonding area by using the infrared camera and the bonding strength by the razor blade clack opening method, respective1y. It was confirmed that the bonding area was between 80% and to 95% as FLA heat input increased. The bonding strength became the equal of $1000^{\circ}C$ heat treated $Si ll SiO_2/Si_3N_4 ll Si$ pair by an electric furnace. Bonding strength increased to 2500 mJ/$\textrm{m}^2$as heat input increased, which is identical value of annealing at $1000^{\circ}C$-2 hr with an electric furnace. Our results implies that we obtained the enough bonding strength using the FLA, in less process time of 125 seconds and at lowed annealing temperature of $400^{\circ}C$, comparing with the conventional electric furnace annealing.