• Environmental and Resource Economics Review
• /
• v.13 no.2
• /
• pp.301-322
• /
• 2004

The current petroleum stockpiling by Korean government is based on the static concept of dead-stock. However, the recent changes in economic environment is requiring a transition to the dynamic concept of flow-stock. This study suggested selective trading strategies using basis of changing oil prices as an option for improving the economics of domestic strategic petroleum reserve (SPR), and quantitatively analyzed their effects. For this purpose, we tested the validity of selective trading strategies using the weekly spot and forwards prices of WTI for the period of October 1997 to August 2002. Summarizing the simulation results, the selective trading strategies would increase the expected values of profits and decrease their volatilities compared to those of traditional routine strategies. And, the adoption of trigger value could increase the improvements by the selective trading strategies. Based on the results, we suggest that, in order to improve the economics of domestic petroleum stockpiling, it is necessary to actively utilize the reserve facilities and the reserved petroleum with proper derivatives position.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.67 no.3
• /
• pp.147-154
• /
• 2022

This study was conducted by directly sowing Asemi in late April at 30 × 10 cm intervals to determine the optimal irrigation method and irrigation amount to maximize the use of limited agricultural water and to increase the yield when growing rice in a desert climate. Conventional irrigation (Conv.), surface drip irrigation (Sur), subsurface drip irrigation (Sub.), and sprinkler irrigation (Spr.) methods were used. The following amounts of irrigation were tested based on field capacity (0.33 bar): 80% (V/V, FC80), 100% (FC100), and 120% (FC120), and data for 2 years were averaged. The total amount of irrigation by irrigation method was the lowest, at 627 ton/10 a, for Sub. irrigation with the FC80 treatment, which was 60.4% less than the amount of irrigation with the FC120 treatment (1,584 ton/10a). Sub. irrigation with the FC120 treatment gave the greatest amount of rice, at 665 kg/10 a, and this condition obtained a yield of 88.1% (754 kg/10 a) of the yield obtained with the conventional treatment. Therefore, when planting rice in a desert climate, subsurface drip irrigation at 120% of field capacity is considered advantageous to increase water use efficiency and crop yield.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.20 no.5
• /
• pp.533-541
• /
• 2007

The Zienkiewicz-Zhu(Z/Z) error estimate is slightly modified for the hierarchical p-refinement, and is then applied to L-shaped plates subjected to bending to demonstrate its effectiveness. An adaptive procedure in finite element analysis is presented by p-refinement of meshes in conjunction with a posteriori error estimator that is based on the superconvergent patch recovery(SPR) technique. The modified Z/Z error estimate p-refinement is different from the conventional approach because the high order shape functions based on integrals of Legendre polynomials are used to interpolate displacements within an element, on the other hand, the same order of basis function based on Pascal's triangle tree is also used to interpolate recovered stresses. The least-square method is used to fit a polynomial to the stresses computed at the sampling points. The strategy of finding a nearly optimal distribution of polynomial degrees on a fixed finite element mesh is discussed such that a particular element has to be refined automatically to obtain an acceptable level of accuracy by increasing p-levels non-uniformly or selectively. It is noted that the error decreases rapidly with an increase in the number of degrees of freedom and the sequences of p-distributions obtained by the proposed error indicator closely follow the optimal trajectory.

• Koreanishche Zeitschrift fur Deutsche Sprachwissenschaft
• /
• v.10
• /
• pp.125-154
• /
• 2004

Diesel Beitrag befasst sich mil der Sprache in gesellschaftlichen Umbruchssituationen aus der Perspektive einer spezifisch linguistischen Fragestellung. Im Zentrum der Untersuchung steht der Wandel der Sprachverwendung unter den Bedingungen der Demokratisierung der DDR und der Vereinigung mil der BRD seit der Wende 1989/90. Dieser Wandel wird am Beispiel der Lexik, und anhand von Losungen bzw. Demo-Spruchen konkretisiert. Im Zuge der 'Wende' sind $f\"{u}r$ beide Kommunikationsgemeinschaften - $\"{u}berwiegend$ aber $f\"{u}r$ die der neuen $Bundesl\"{a}nder$ - Neologismen in Gebrauch gekommen. Am bekanntesten sind: 'Mauerspecht', 'Wendehals', 'Moniagsdemo' und 'Stasi-Akte' usw. Andererseits wurden im Verlauf der Wende zahireiche Bezeichnungen, insbesondere $f\"{u}r$ $aufgel\"{o}ste$ Institutionen der DDR sowie viele verwaltungsspezifische $W\"{o}lfer$, historisiert. An Textbeispielen der Losungen des Herbstes 1989 werden uns die Dynamik sprachlicher Strukturen auf der einen Seite und die sich verandernden gesellschaftlichen $Verh\"{a}ltnisse$ in der $\"{o}ffentlichen$ Kommunikation der ehemaligen DDR auf der anderen Seite vol Augen gefuhrt. Verglichen mit den zum 1. Mai bekannt gegebenen of nziellen SED-Losungen, sind die Aktanten der Demo-Spruche das Volk, teils als Individuen und teils als spontan gebildete Gruppen. Im Unterschied zu den 'allen' offiziellen Losungen $repr\"{a}sentieren$ die Demo-$Spr\"{u}che$ verschiedenartige Sprechhandlungstypen: Nicht nur AUFFORDERN, APPELLIEREN, BEHAUPTEN, sondern auch FRAGEN, BESCHIMPFEN, DROHEN, $GR\"{U}{\ss}EN$usw. Gleichzeitig $\"{u}bernehmen$ sie viele Textmuster als sprachliche Stilmittel aus fem Bereich anderer Spruch- und Kurztextgattungen, wie zum Beispiel Sprichwort, Kinderreim, Aphorismus, Anspielung und verwenden auch Zitate. Auf diese Weise linden sich in den Wende-Losungen zahlreiche Belege $f\"{u}r$ intertextuelle $Bez\"{u}ge$. So schaffen diese Losungen $schlie{\ss}lich$ eine neue Qualitat des $\"{o}ffentlich-politischen$ Diskurses in der Gesellschaft. Am Rande der Untersuchungen haben wir $f\"{u}r$ das Deutsch in Ost und West festgestellt: $Bem\"{u}hungen$ der $Ann\"{a}herung$ und des sprachlich-kornrnunikativen Ausgleichs findet man seit der Wende 1989/90 eher auf der Seite der Ostdeutschen. Die sprachlichen Differenzierungen zwischen Ost- und Westdeutschland waren vornehmlich lexikalischer An. Es ist aber anzunehmen, dass es heute weniger die Sprache selbst ist als vielmehr das unterschiedliche Kommunikationsverhalten zwischen Ost- und Westdeutschen, das die Verstandigung zwischen Ost- und Westdeutschen schwierig zu machen scheint.

• Journal of Ocean Engineering and Technology
• /
• v.25 no.1
• /
• pp.39-43
• /
• 2011

This study has lowered the specific resistance by coating a thin film layer of Ag, playing the role of the electron donor on the ZnO that is used usefully for the transparent conductive oxides. Presently, this study has examined the transmittance and electric characteristics according to the thickness of the Ag thin film layer. Also, this study has observed the transmittance and electric characteristics according to the uppermost ZnO thin film layer of ZnO/Ag/ZnO symmetric film and has conducted the theoretical investigation. In order to observe the transmittance and electric characteristics according to the thickness of the Ag thin film layer and the uppermost ZnO thin film layer, this study conducted the film deposition at room temperature while making use of the DC magnetron sputtering system. In order to see the changes in the thickness of the Ag thin film layer, this study coated a thin film while increasing by 4nm; and, in order to see the changes in the thickness of uppermost ZnO thin film layer, it performed the thin film coating by increasing by 5nm. From the experimental result, the researchers observed that the best transmittance could be obtained when the thickness of the Ag thin film layer was 8nm, but the resistance and mobility increased as the thickness got larger. On the other hand, when the thickness of the uppermost ZnO thin film layer was 20nm, the experiment yielded the best transmittance with excellent electric characteristics. Also, when compared the ZnO/Ag asymmetric film with the ZnO/Ag/ZnO symmetric film, the ZnO/Ag asymmetric film showed better transmittance and electric characteristics.

• Journal of Korean Society on Water Environment
• /
• v.27 no.6
• /
• pp.848-854
• /
• 2011

The objective of this research was to experimentally test the effect of rice straw mats on the reduction of runoff, sediment and discharge under a laboratory scale with different rainfall intensity and slopes. We used the small runoff plots of $1m{\times}1m{\times}0.65m$ ($L{\times}W{\times}H$) in size were filled with loamy sand. Experimental treatments were bare (control), rice straw mats + PAM(SP), rice straw mats + PAM + sawdust(SPS) and rice straw mats + PAM + rice husks(SPR); slope of 10% or 20%; and rainfall intensity of 30 or 60 mm/hr. Runoff volume and coefficient from covered plots were significantly lower than those from control plots. Under the 30 mm/hr and 10% simulations, average runoff coefficient of covered plots decreased more than 92%. Under 60 mm/hr and 20% simulations, the ratios were between 39.8~58.1%. Under the condition of 30 mm/hr rainfall and 10% slope, sediment discharge from covered plots was practically zero. And at 20% plots, sediment reduction ratio was more than 95%. Under the condition of 60 mm/hr rainfall, sediment reduction ratio of 10 and 20% plots ranged between 86.3~95.3% and between 79.8~86.5%, respectively. The differences in initial runoff time, runoff and sediment discharge among different cover materials were not significant. Rainfall intensity showed higher impact on initial runoff time, runoff, and sediment discharge than slope. It was also shown that even if runoff reduction by surface cover were low, sediment discharge reduction could be very significant and contribute to improve the water quality of streams in sloping agricultural regions. It was concluded that the use of straw mat and PAM on sloping agricultural fields could reduce soil erosion and muddy runoff significantly and help improve the water quality and aquatic ecosystem in receiving waters.

• Journal of Preventive Medicine and Public Health
• /
• v.30 no.1 s.56
• /
• pp.103-128
• /
• 1997

The object of this study is to evaluate the possibility of chemical-induced liver disorder among workers exposed to various chemicals and to classify the the liver function abnormalities by causes and to analyse the risk factors for each liver disorders. A cross-sectional study including questionnaire survey, physical examination, laboratory tests and ultrasonography of liver was conducted on 1,126 workers, 459 workers in a coal chemical plant(company A) and 667 workers in an insulation material manufacturing factory(company B). An industrial hygienist reviewed the chemicals used in both companies and evaluated the work environments to classify the workers by chemical exposure semiquantitatively. The results are as follows: 1. Of 459 workers in company A, 83 workers(18.1%) are classified as nonexposed, group 163(35,5%) as short-term exposure group, 155(33.8%) as intermediately exposed group and 58(12.6%) as long-term exposed group bared on the mean daily exposure to hepatotoxic chemicals evaluated by an industrial hygienist. Of 667 workers in company B, 484(72.6%) workers were classified as nonexposed and 183(35.5%) as exposed group. 2. Workers with SGOT level higher than 40 IU/l were (10.0%) in company A and 77(11.5%) in company 3, and those with SGPT level higher than 35 IU/l were 118(25.7%) in company A and 198(29.7%) in company B. The differences were not significant between companies and between exposure groups(p>0.05). Workers with $\gamma-GT$ level higher than 62 IU/l were 29(6.3%) in company A and 77(11.5%) in company B (p<0.01). The difference between exposure groups was not significant(p>0.05) within companies. Workers with liver function abnormalities(defined as SGOT higher than 40 IU/l or SGPT higher than 35 IU/l) were 338(30.0%) among 1,126 workers. Of 338 workers with live. function abnormalities 139(12.3%) had fatty liver by ultrasonography, 79(7.0%) had alcoholic liver(defined as workers with liver function abnormalities with weekly alcohol consumption greater than 280 g for more than 5 years), 54(4.8%) had hepatitis B, 12(1.1%) had hepatitis C and the other 114(33.7%) was not otherwise classified. Prevalences of alcoholic liver and fatty liver were significantly lower in company A(prevalence ratio 0.24 for alcoholic liver, p<0.001, prevalence ratio 0.76 for fatty liver, p<0.05) but prevalences of liver disorders between exposure groups within companies were not significant(p>0.05). 3. Summary prevalence ratios(SPR) of live. function abnormalities, fatty live. and other liver disorders, adjusted by age and company were not significantly higher in exposed group in any chemicals(p>0.05) but in some chemicals, SPRs were significantly lower. 4. On simple analysis of risk factors for liver function abnormalities, prevalence odds ratio(POR) of those with age between 30 and 39 was 1.54(p<0.01) and those with age ever 40 was 1.51(p<0.01). POR of those with histories of liver disorders and general anesthesia was 1.77(p<0.001) and 4.02 for those with overweight and 6.23 for those with obesity, defined by body mass index(p<0.001). 5. On logistic regression analysis, risk factors of liver function abnormality were fatty liver(POR 2.92 for grade 1, 12.15 for grade 2), presence of hepatitis B surface antigen(POR 3.62) and obesity(POR 5.38 for overweight and 16.52 for obesity). Presence of hepatitis B surface antigen(POR 0.18) was the only preventive facto. of fatty live. Company(POR 0.30) and obesity(POR 2.49 for overweight, 4.52 for obesity) were related to the alcoholic live. Obesity(POR 2.94 for overweight) was the only significant risk factor of hepatitis B and there was no significant risk factor for liver function abnormality not otherwise classified. It is concluded that the evidence of liver disorder related with chemical exposure is not evident in these factories. It is also postulated that fatty liver and alcoholic liver is most common causes of liver function abnormalities among workers and effort for weight control and improvement of life style should be done.

• KSBB Journal
• /
• v.24 no.1
• /
• pp.1-8
• /
• 2009

In the past decade, we have observed rapid advances in the development of biochips in many fields including medical and environmental monitoring. Biochip experiments involve immobilizing a ligand on a solid substrate surface, and monitoring its interaction with an analyte in a sample solution. Metal nanoparticles can display extinction bands on their surfaces. These charge density oscillations are simply known as the localized surface plasmon resonance (LSPR). The high sensitivity of LSPR has been utilized to design biochips for the label-free detection of biomolecular interactions with various ligands. LSPR-based optical biochips and biosensors are easy to fabricate, and the apparatus cost for the evaluation of optical characteristics is lower than that for the conventional surface plasmon resonance apparatus. Furthermore, the operation procedure has become more convenient as it does not require labeling procedure. In this paper, we review the recent advances in LSPR research and also describe the LSPR-based optical biosensor constructed with a core-shell dielectric nanoparticle biochip for its application to label-free biomolecular detections such as antigen-antibody interaction.