• Journal of the Korea Organic Resources Recycling Association
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• v.9 no.4
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• pp.71-80
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• 2001

In order to evaluate the effectiveness of the organic and natural farming techniques, the actual conditions of the techniques were surveyed and some crops were cultivated in situ. The contents of available $P_2O_5$, exchangeable $Ca^{2+}$ and organic matter of the organic and natural farming soil as well as soil pH were higher than those of the non-organic and non-natural farming soil, and especially the content of organic matter amounting 54.0 g/kg was dominant. Income of the farmers cultivating the different crops with the organic and natural farming was high in order of red pepper in vinyl house > cucumber in vinyl house > fruit(pear) > lettuce in vinyl house > rice. The agricultural materials used in organic and natural farming were ranged from 22 to 25 kinds, representing low pH amounted from 2.9 to 4.5 and low contents of fertilizer ingredients. The expense for purchasing the materials was from three to five times higher than that of soil testing plot. The yields of test crops in the organic and natural farming plots were lower than those of soil testing plot, and the efficiencies of the disease and pest control by the application of the substitutes for pesticide were lower than those by pesticides.

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.2
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• pp.469-483
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• 2018

Steel bars have been widely used as the primary reinforcement for Precast Segmental Concrete Lining for TBM Tunnels. Previously, studies have been carried out to gauge the potential for steel fiber reinforcement to replace the use of steel bar reinforcements in the segmental lining to reduce the amount of the steel bar reinforcement. Steel fiber reinforcements have been investigated and widely applied to SFRC TBM linings to improve the constructability of SFRC TBM linings worldwide. However, the steel fiber reinforcement often caused punctures to the water membranes inside tunnel lining and had long-term durability deterioration issues caused by steel corrosion, as well as cosmetic problems. Therefore, this paper sought to gauge the potential of synthetic fiber reinforcements, which have proven to be very attractive substitutes for steel fiber reinforcements. This study analyzed the performance of both steel and synthetic fiber reinforcements in segmental linings and evaluated the applicability of the fiber reinforcements to the TBM Precast Concrete Segmental Linings of TBM tunnels. As a conclusion, this study demonstrates that the potential use of steel and synthetic fibers in various combination, can substitute the rebar reinforcement in the concrete mix for segmental concrete linings.

• The Journal of the Korea Contents Association
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• v.16 no.10
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• pp.150-162
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• 2016

This study empirically analyze the effect of government R&D investment to find out whether it complements or substitutes for the firm R&D. In order to do it panel data set was constructed for the period of three years from 2012 to 2014 based on the number of 1301 data by utilizing national technology information service(NTIS) and publicly announced financial statement. Analysis was implemented in consideration of size of the firm(large corporation, small and medium sized firm) of which sample was obtained from only listed company. The result of two-way fixed effect model and two-way random effect model is as follows. In case of large corporation, government R&D investment has an effect of substitute for the company's R&D on the other hand, small and medium sized firm shows an complementary effect. It verifies that current R&D policy is appropriate. Therefore government's direct subsidy is expected to be successful to fertilize firm's innovation by allocating government R&D budget efficiently.

• Journal of Korean Ophthalmic Optics Society
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• v.5 no.1
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• pp.173-180
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• 2000

To determine the effect of base curve and diameter of soft contact lenses on the fitting under the various corneal curvature, the model eyes which was made of either stainless steel or ordinary wood, were used as the substitutes for human eyes. The evaluations of fit of the soft contact lenses on both wood model eyes and human eyes were found to be very similar to each other. All the contact lenses except very thin ones became flat after fit on the stainless steel model eyes because the model eye could not preserve enough moisture to hold the edge of contact lenses on the steel ball's surface. The relationships between the base curves of contact lenses and radii of cornea for the optimum (normal) fit were measured as follows : corneal curvature (C.C)<7.6 mm : base curve(B.C) 8.4 mm, C.C 7.6~7.8 mm : B.C 8.4~8.5 mm. C.C 7.8~8.1 mm : B.C 8.6 mm. It is concluded that larger base curve is required for the eyes which have abnormal bulge on its cornea. It is found that very thin soft contact lenses can be easily twisted or folded regardless of moisture content when they were fit on the relatively dry eyes(corneas).

• Journal of the Society of Cosmetic Scientists of Korea
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• v.38 no.1
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• pp.33-41
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• 2012

An effective, environmentally friendly analytic methods using gas chromatography with mass spectrometric detector (GC-MSD) have been developed for the quantitative analysis of trace phthalate levels in cosmetics such as nail lacquer and hair spray. Since such cosmetics are largely comprised of organic solvents, conventional clean-up methods that have been widely used for phthalate analyses are in adequate. In addition, analysis of trace phthalate levels is notorious for its sensitivity to contamination, which causes high analytical values. A direct sample dilution method using an organic solvent was adopted to the sample preparation process to determine the exact amounts of phthalates and simultaneously avoid the high risk of secondary contamination. The method has many advantages including high accuracy, sensitivity, and simplicity in sample preparation. Dibutyl phthalate (DBP) and di (2-ethylhexyl) phthalate (DEHP) were selected for analysis because they have been frequently detected in cosmetics and consistently reported as endocrine disruptors in humans and animals. Internal standard method using two deuterium substitutes (DBP-$d_4$, DEHP-$d_4$) as the internal standard was also used. The results of 'Method validation' showed the capabilities of this method for the routine analysis of phthalates at the ppm level. The recovery ranges were between 95 % and 106.1 %, and relative standards deviations (RSD) were less than 3.9 % in fortified nail lacquer and hair spray samples at the concentration of $25{\mu}g/g$.

• Journal of Chest Surgery
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• v.31 no.12
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• pp.1127-1133
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• 1998

Background: There are no ideal substitutes for tracheal replacement. Therefore we investigated the possibility of clinical use of cryopreserved tracheal homograft with special interest in the viability and rejection of the epithelial cell and cartilage. Material and Method: Rabbit's trachea was sected and stored in liquid nitrogen tank for 1 month. Tracheal replacement was done in 45 rabbits with autograft(n=15, Group 1), fresh allograft(n=15, Group 2) and cryopreserved homograft(n=15, Group 3). After 7, 14, and 30 days, 5 rabbits in each group were sacrificed and the regeneration of epithelium and cartilage and the degree of rejection were assessed by counting the monocellular infiltration. Result: Investigation at day 7, showed no difference in epithelial regeneration, however, at days 14 and 30, Group 1 showed better regeneration of epithelium than groups 2 and 3. There was no difference of epithelial regeneration between group 2 and 3. There was little rejection at day 7, but at days 14 and 30, there was significant rejection in group 2 and group 3.(P<0.05). Group 3 showed lesser rejection than group 2 at days 14 and 30, but it was not statistically significant. Cartilage showed no rejection and maintained its viability in groups 2 and 3. Conclusion: Cryopreserved tracheal homograft can maintain its viability, therefore it may represent a possibility of clinical application for tracheal replacement. However, cryopreservation can not eliminate the antigenicity of the trachea completely. Furthere studies for lowering the antigenicity and rejection should be performed for an ideal substitute for tracheal replacement.

• Korean Business Review
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• v.22 no.2
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• pp.35-59
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• 2009

The drive for sustainable economic growth for the sub Saharan African region continues to occupy a central place in the debate of how to move the region forward. For decades, governments, policy makers, Non Governmental Organizations and world bodies including the World Bank, IMF, ADB, USIAD and the European Union have engaged policies aimed at bringing solutions to the horrendous poverty crisis to nations of this region. Despite these noble actions and intents, poverty and underdevelopment has prevailed in countries of the region such as Cameroon. Cameroon is mainly an agricultural economy with its products facing declining prices and competition from synthetic substitutes resulting to deficits of balance of trades. This has resulted to borrowing and debt. At the same time, it is a country blessed with an abundance of tourist resources. From the literature review, tourism potency to economic growth is overwhelming. This research was motivated by the quest to find answers to questions such as; why development policies during the last two decades not succeeded in achieving Economic growth in countries of this region particularly Cameroon and why the country/ region still beleaguered by poverty and debt despite haven implemented various economic development plans. In recent years, the role of tourism has become increasingly recognized in its role of economic growth and poverty alleviation. This study attempts to unveil tourism's contribution to economic growth and to push for Tourism development as an al ternative economic growth alternative to Cameroon. Previous economic policies have ignored to tie economic growth within the country's socio-economic, geo-political and environmental circumstances. Findings from this work suggest that any sound economic policy can not afford to ignore the country's stock of both human and fiscal capital. Findings presented herewith validate Tourism as a feasible indigenous economic growth alternative that helps bringing employment, capital investment and protect the environmental ruin.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.26 no.6
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• pp.636-643
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• 2000

Facial asymmetry is the most frequent disease in craniofacial deformities. And the primary causing area of that is mostly placing in mandible. That is to say, it is known that primarily, mandible grows excessively or deficiently, and other facial region involving maxilla undergoes compensatory growth secondarily, so asymmetric face develops. In facial asymmetry, the surgical correction of undergrowth is more difficult than that of overgrowth and the reason of it is the postoperative relapse caused by stress of surrounding soft tissues. It means the stress of surrounding soft tissues occurring after bone lengthening and reducing above stress is the same meaning with reducing postoperative relapse. Among various areas, mandibular ramus is the most difficult area to lengthen vertically and maintain its length. The reason of it is considered by many authors as the stress of surrounding pterygomasseteric sling which is enveloping lower border of mandible and interrupting elongation of ramal height. So we applied two different surgical procedures in which pterygomasseteric slings have different stress respectively to monkeys which have similar masticatory function and anatomy to human being and compared relapse by radiographic film and observed periodically the histochemical change of masseteric muscle fiber. So we could see the following results. The relapse was less in EVRO group in which we separated pterygomasseric sling in inferior border and didn't approximate muscle sling after vertical lengthening to minimize the stress of soft tissues than IVRO group in which we elongated ramal height preserving pterygomassetric sling. Of course, we could see a problem in EVRO group such as bone resorption in inferior border caused by uncovering the periosteum of inferior border. But we expect that such problem will be solved by developing periosteum substitutes for covering the exposed bone and minimizing the surgical trauma. In histochemical study of masseteric muscle fiber, the fiber constituents of EVRO group in which we minimized soft tissue stress was changed immediately after operation and maintained it for 1 year, whereas that of IVRO group in which we preserved soft tissue stress was changed in more portion after operation and recovered it by 1 year. By the histochemical results, we can see that the recovery of fiber constituents reflect the recovery of muscle stress and it is closely related with relapse phenomenon.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.27 no.6
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• pp.491-497
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• 2001

Polymethylmethacrylate(PMMA) is currently commonly used material for the reconstruction of bone defects and fixation of joint prosthetics following congenital and acquired causes. Although PMMA has widespread use, it does not possess the ideal mechanical characteristics with osteoconductivity and osteoinductivity required. In order to overcome these problem, addition of bovine bone drived defatting demineralized bone(BDB) powders to a PMMA bone cement was done for improvement of physical property and bone forming characteristics of composite. In order to investigate the influence of BDB reinforcement on the PMMA, we measured physical property of compressive, tensile, flexural strength, and scanning electron microscopic examinations. The results were obtained as follows: 1. The PMMA forms a solid cellular matrix with open cells about $100{\mu}m$ in variable size and incorporating BDB. BDB aggregates inside the cells form a porous network that is accessible from the outer surface. 2. The physical properties were compressive strength of mean $22.74{\pm}1.69MPa$, tensile strength of mean $22.74{\pm}1.69MPa$, flexural strength of mean $77.53{\pm}6.93MPa$. Scanning electron microscopic examinations were revealed that there was DBD particles form a highly porous agglomerates. BDB can be added PMMA in the form of dried powders, the composites are applicable as bone substitutes. BDB and PMMA mixture is shown to produce a class of composites that due to their microstructure and improved mechanical properties may be suitable for application as bone subsitutes. The mechanical and material properties of the BDB-PMMA bone substitute composites are competitive with those properties of a porous ceramic matrix of other hydroxyapatite and with those of natural bones.

• Journal of the Korean Magnetics Society
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• v.18 no.5
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• pp.185-189
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• 2008

We observe the change of coercivity and exchange bias, depending on inserting material and thickness in a [Pd(0.6 nm)/$Co(0.2)]_5$/ FeMn(10) multilayer structure with perpendicular anisotropy. When 0.78 and 1.28 nm thick NiFe substitutes for Co in a $[Pd(0.6 nm)Co(0.2)]_4$/Pd(0.6)/NiFe(t)/FeMn(10) structure, we obtain the exchange bias of 360 Oe. In addition, when $Co_8Fe_2$ and $Co_9Fe_1$ are inserted for Co/FeMn interface, we obtain the exchange bias of 380 nm for a 0.68 nm thick $Co_8Fe_2$ and 580 Oe for a 0.52 nm thick $Co_9Fe_1$.