• Transactions of the Korean Society of Mechanical Engineers
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• v.9 no.2
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• pp.158-173
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• 1985

An experimental investigation has been made to study the interaction between and incident oblique shock wave and an unstabilized turbulent boundary layer on a solid surface downstream of a porous surface with air injection through the porous surface. The boundary layer upstream of the interaction is unstabilized by the injection and provokes a shock wave which eventually interacts with the unstabilized boundary layer after reflecting from the upper wall of the test section. Three cases having diferent upstream Mach numbers and different shock strengthes are studied. According to the level of the unstabilization, two cases are of attached boundary layers and the other one is of a separated boundary layer. The result shows that the reflected wavey system is composed of the compression wave, expansion wave fan, and recompression wave like the ordinary interaction while the separated boundary layer strengthens the reflected expansion waves. The interactions of the attached boundary layers show a similar tendency of the upstream wall pressure distribution as that of the ordinary interacton but the pressure rise rather decays in the downstream region. In case of the separated boundary layer, the wall pressure continues to rise in the downstream as opposed ot the former cases. This indicates that the interaction region spreads out widely adn the viscous effect of the separated boundary layer smoothens the abrupt pressure increase due to the shock inpingement.

• Korean Journal of Organic Agriculture
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• v.4 no.1
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• pp.75-84
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• 1995

This study was carried out to find the effects of the mixtures of earthworm cast, peatmoss, and vermiculite as a vegetable plant growth medium on the growth pepper seedlings. The mixed ratios of earthworm cast-peatmoss-vermiculite were 40-20-40, 40-30-30, 40-40-40, 50-20-30, 50-30-20, 60-10-30, 60-20-20 and 60-30-10%. The results of the study are as follows: 1, There was a significant difference of plant length, leaf area, shoot dry weight, root dry weight and biological yield per plant for growth stages and mixed ratios(p<0.05). But there was no significant interactions for both of them. 2. The nursery soil with earthworm cast was generally higher than the control treatment in shoot dry weight, root dry weight adn biological yield per plant. The shoot dry weight and biological yield per plant were high in the treatment including 60% of the earthworm cast to the 3rd week and in the one including 50% from the 4th week. But in root dry weight, the treatment including 40% of it was higher than treatment of the others. 3. The shoot dry weight per plant in treatments consisting both of 40% of earthworm, 40% of peatmoss and 20% of vermiculite and of 60%, 10% and 30% was more significant than that in the control treatment(p<0.05). 4. The average relative growth rates of shoot dry weight, root dry weight and biological yield for all treatments were higher than the ratio of control treatment except the ration of the treatment consisting of 60% of earthworm, 20% of peatmoss and 20% of vermiculite.

• Journal of Life Science
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• v.11 no.2
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• pp.121-125
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• 2001

Some attempts were made to investigate the biological characterisitcs of the green rice leafhopper(GLH) , Nepthotettix cincticeps Uhler in terms of nymphal development, emergence ratio. preovipositional period, growth index, adult longevity and fecundity fed on rice cultivar, Chucheongbyeo with no resistance gene and water foxtail, Alpecurus aequalis Sobol. var. amurensis Ohwi at 20 and $25^{\circ}C$ with a 16L;8D photoperiod. Development period of nymph on rice cultivar and water foxtail at $25^{\circ}C$ was shorter than that at 2$0^{\circ}C$ by twofold. The nymphal period of female was about one day longer than that of male. The mean emergence ratio of female and male on rice cultivar and water foxtail was 40.0, 76.7, 38.3, 73.3% at 20 and $25^{\circ}C$, respectively. Preovipositional period on rice cultivar and water foxtail at $25^{\circ}C$ was shorter that at 2$0^{\circ}C$ by twofold. Growth index on rice cultivar adn water foxtail at $25^{\circ}C$was higher than that at 2$0^{\circ}C$ by fourfold. Under the 20 and $25^{\circ}C$ condition, the longevity of female and male was longer on water foxtail than on rice cultivar, but the fecundity of GLH was higher on rice cultivar than on water foxtail. In conculsion, water foxtail seems to be adequate for spring host of GLH.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.35S no.6
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• pp.46-54
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• 1998

This paper presents a method for designing robust fuzzy $H^{\infty}$ controllers which stabilize nonlinear systems with parameter uncertainty adn guarantee an induced $L_{2}$ norm bound constraint on disturbance attenuation for all admissible uncertainties. Takagi and Sugeno's fuzzy models with uncertainty are used as the model for the uncertain nonlinear systems. Fuzzy control systems utilize the concept of so-called parallel distributed compensation(PDC). Using a single quadratic Lyapunov function, the stability condition satisfying decay rate and disturbance attenuation condition for Takagi and Sugeno's fuzzy model with parameter uncertainty are discussed. A sufficient condition for the existence of robust fuzzy $H^{\infty}$ controllers is then presented in terms of linear matrix inequalities(LMIs). Finally, design examples of robust fuzzy $H^{\infty}$ controllers for uncertain nonlinear systems are presented.

• Journal of Technology Innovation
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• v.5 no.1
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• pp.206-222
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• 1997

The conventional analysis with which justifies government intervention of the private sector's innovation activities is the market failure approach. According to such analysis, fund allocation through autonomous market mechanisms is not optimal in technology financing because of the disparity between the desirable level of investment for society as a whole and that for private firms. To optimize the fund allocation, public policies such as subsidy, preferencial loan and venture capital investment programs are designed for technology development projects performed by private firms. They, however, have not been effective in increasing private investment for such projects. In most cases, it was found that little considerations given to the relationship between uncertainty embodied in technology development projects and each types of financing. With respect to optimizing fund allocation, technology development projects should be financed by different means according to their probability of success and the expected value of technology. Employing various theoretical models on financing decision-making we verify here that technology development projects to be supported by commercial banks or venture capital institutions is limited contingent upon levels of uncertainty adn expected value. Under the assumption that financial institutions are risk averse, loan or investment can be available only if the probability of success of the project is higher than the probability premium and the current market rate of interest. Therefore, the projects that have lower probability of success and/or small expected return are excluded from commercial loan or investment programs. However, the remaining projects, whose probability of success is low but with high expected return, may be applied under government subsidy programs. To achieve optimality of fund allocation and to activate technology financing, we conclude that there should be a systematic division of role among financial institutions including government commercial banks, and venture capital institutions.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.9 no.4
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• pp.387-395
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• 1999

The strain, surface and interfacial energies of III-V ternary systems were calculated for three kinds of structure modes: the Frank-van der Merwe(FM) mode, the Stanski-Krastanov(SK) mode and the Volmer-Weber(VW) mode. The free energy for each mode was estimated as functions of thickness and composition or lattice misfit. Through comparison of the free energy of each mode, it was found that the thickness-composition phase diagrams of III-V ternary systems can be determined only by considering the balance of the free energy and three kinds of structure modes appear in the phase diagrams. The SK mode appears only when the lattice misfit is large and/or the lattice layer is thick. The most stable structure of the SK mode is a cluster with four lattice layers or minimum thickness on a wetting layer of increasing lattice layers. The VW mode appears when the lattice misfit is large and the lattice layer is thin and only in the INPSb/InP and GaPSb/GaP system which have the largest lattice misfit of III-V ternary systems. The stable region of the SK mode in the GaPSb/GaP and InPSb/InP phase diagrams is largest of all because the composition dependence of the strain energy of these systems is stronger than that of the other systems. The critical number of lattice layers below which two-dimensional(2D) layers precede the three-dimensional(3D) nucleation in the SK mode at x=1.0 depends on the lattice misfit.

• Journal of Life Science
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• v.11 no.6
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• pp.612-617
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• 2001

Seedlings of red pepper (Capsicum annum L.) were exposed to various doses of ${\gamma}$-radiation )($^{60}$ Co)and cultivated in the 1/2,000 a pot. Plant hight the number of leaves, flowers and fruits, chlorophyll contents, plant dry weight, ac- tivites of antiozidant enzymes such as superoxide dismutase(SOD) adn peroxidase(POD), were determined. Plant height of seedling treated with 1 Gy of ${\gamma}$-radiation was increased up to 16.6% as compared to untreated control at 80 days after treatment, while those treated with 20 Gy or 50 Gy was decreased 22.0% or 75.0% respectively. The plants treated with 1 Gy or 5 Gy were increased the number of leaves up to 41.2% and 24.9% as well as dry weight of fruit up to 58.4% and 49.4% respectively. However treatment of radiation higher than 20 Gy significantly inhibited the growth, chlorophyll content and yield of pepper fruit. Activities of antioxidant enzymes, SOD and POD were tem-porary increased within one or five days after treatment depending on the doses of treatment , and the activities were gradually decreased to control level of lower thereafter. The SOD and POD activities in the leaves of pepper plant treated with 50 Gy were 5.5 and 6.0folds higher than that of control at five days after treatment, respectively.

• Korean Journal of Animal Reproduction
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• v.22 no.3
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• pp.229-235
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• 1998

These experiments were conducted to investigate the effects and optimal concentrations of RPMI 1640 amino acids, MEM vitamins and human follicular fluid(hFF) as additives in the medium for in vitro culture of mouse embryos. The results obtained were as follows. 1. The development rates of blastocyst stage were 54.5%, 65.4%, 48.2%, 57.4% and 35.5% when the medium was added to 0.25%, 0.5%, 1%, 2% of RPMI 1640 amino acid and control, respectively. The addition of 0.5% RPMI 1640 amino acid was the best concentration. 2. The development rates of blastocyst stage were 22.4%, 31.3%, 21.9%, 19.0% adn 12.8% when the medium was added to 0.25%, 0.5%, 1%, 2% of MEM vitamin and control, respectively. The addition of 0.5% MEM vitamin was the best concentration. 3. The development rates of blastocyst stage were 20.9%, 21.9%, 18.9%, 29.4% and 20.6% when the medium was added to 2.5%, 5%, 10%, 20% of hFF and control, respectively.

• Korean Journal of Animal Reproduction
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• v.17 no.4
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• pp.305-310
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• 1994

These expriments were carried out to investigate existence of H-Y antibody in the rat serum immunized against H-Y antigen from rat spleen cells and effect of H-Y antiserum on development of mouse male embryos. The results obtained were summerized as follows : 1. When mouse embryos were cultured for 48∼72 hrs in the Ham's F10 containing 16% of FBS(fetal bovine serum) or RNS(rat normal serum), percentages of embryos developed from 2, 4, 8 and 16-cell embryo to morulae were 20, 27, 94 and 100%, respectively, in FBS and 8, 7, 94 and 100%, respectively, in RNS. Eight to 16-cell embryos showed no difference in development rate between FBS adn RNS. 2. When 8∼16-cell mouse embryos were cultured for 24∼48 hrs in the Ham's F10 containing FBS, RNS＋GPC(guinea pig complement) and RAS(rat antiserum)＋GPC, proportions of embryos developed to the expanded blastocyst stage were 100, 82.4 and 52.1∼53.6%(ave.52.9), respectively, so that it was suggested that rat antiserum suppressed development of male embryos. 3. When 8∼16-cell mouse embryos were cultured for 24∼48 hrs in the Ham's F10 containing FBS, RNS, RNS＋GPC and RAS＋GPC, proportions of embryos developed to the expanded blastocyst stage were 94.5, 90.9, 82.3 and 47%, respectively, and the embryos developed in the medium containing RAS＋GPC seemed to be female. These results indicated that the antisera prepared through immunized against H-Y antigen from rat spleen cell, possessed H-Y antibody which supressed development of male embryos.

• The International Journal of Costume Culture
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• v.2 no.1
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• pp.31-42
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• 1999

The category killer that has been rapidly growing mainly in advanced countries since early 1990's, is a mew distribution model which aims for obtaining market controlling power by surpassing competing businesses in a specific area of products. The domestic situation of category killers is very different from that of advanced ones abroad since it has just been introduced into the Korean market. At the moment, there are only 10 or so companies operating in the market : Geopyung's , Taeheng's , Midopa's , of Sinsegye Department store, adn of Yerim International. The purpose of this study is to examine problems of domestic companies in the present market by analysing the operation status of category killers in domestic markets as well as foreign ones, and to suggest a counter-strategy of category killers for the distribution environment of the 21st century to improve the competitiveness of Korean distribution industry. The competitiveness of category killers lies above all in products lines. Category killers are equipped with the greatest number of products lines among those of competing businesses due to maximized product selections in an limited range. Another source of competitiveness may be found in balanced strategy positioning. That is to say, category killers are in a position where they can adjust policies towards any of the three purposes while aiming at them altogether : prices of discount stores, products range of specialty stores, and customer service level of department stores. It is also necessary for efficient store operation to use information technology such as electronic data interchange (EDI), electronic pose system(EPOS) and electronic funds transfer (EFTPOS). As for the cost structure, category killers can gain an advantage over other business since operating cost of various sections can be saved. There are, however, certain risks that category killers with strong competitiveness may influence on other businesses a great deal and even facilitate their decline. Yet it seems that the growth of category killers will be more viciously restrained by continuous challenges from other businesses. The distribution industry is supposed to develop through such competition and restraint.