• Journal of the Korean Vacuum Society
• /
• v.14 no.2
• /
• pp.78-83
• /
• 2005

Nanometric crystalline silicon (no-Si) embedded in dielectric medium has been paid attention as an efficient light emitting center for more than a decade. In nc-Si, excitonic electron-hole pairs are considered to attribute to radiative recombination. However the surface defects surrounding no-Si is one of non-radiative decay paths competing with the radiative band edge transition, ultimately which makes the emission efficiency of no-Si very poor. In order to passivate those defects - dangling bonds in the $Si:SiO_2$ interface, hydrogen is usually utilized. The luminescence yield from no-Si is dramatically enhanced by defect termination. However due to relatively high mobility of hydrogen in a matrix, hydrogen-terminated no-Si may no longer sustain the enhancement effect on subsequent thermal processes. Therefore instead of easily reversible hydrogen, phosphorus was introduced by ion implantation, expecting to have the same enhancement effect and to be more resistive against succeeding thermal treatments. Samples were Prepared by 400 keV Si implantation with doses of $1\times10^{17}\;Si/cm^2$ and by multi-energy Phosphorus implantation to make relatively uniform phosphorus concentration in the region where implanted Si ions are distributed. Crystalline silicon was precipitated by annealing at $1,100^{\circ}C$ for 2 hours in Ar environment and subsequent annealing were performed for an hour in Ar at a few temperature stages up to $1,000^{\circ}C$ to show improved thermal resistance. Experimental data such as enhancement effect of PL yield, decay time, peak shift for the phosphorus implanted nc-Si are shown, and the possible mechanisms are discussed as well.

• Korean Journal of Environmental Agriculture
• /
• v.16 no.2
• /
• pp.170-174
• /
• 1997

Constructed wetland system was studied to treat wastewater from industrial complex in rural area. Pilot plant at the Baeksuk Nongkong Danzi in Chunahn-City was used for field study. For the DO, the effluent concentration was higher than the influent concentration and it implies that natural reaeration supplies enough oxygen to the system. For the SS, the effluent concentration was consistently lower than the water quality standard even though the influent concentration varied significantly, which showed that SS was removed by the system effectively which is consist of soil and plants. For the BOD and COD, the average removal rate of them were 56% and 43%, respectively, therefore, the effluent concentration could not meet water quality standards when influent concentration was high. The removal rate of BOD and COD can be improved by supplemental treatment in addition to this system if necessary. For the T-N and T-P, the influent concentration of them were lower than the water quality standards than no further treatment was needed. Overall, the result showed that constructed wetland system is a feasible alternative for the treatment of wastewater from industrial complex in rural area. For actual application of this system, further study on design factors including loading rate, removal mechanism, and temperature effects is required to meet water quality standard consistently. Compared to existing systems, this system is quite competitive because it requires low capital cost, almost no energy and maintenance, and therefore, very cost effective.

• Journal of the Korea Organic Resources Recycling Association
• /
• v.19 no.1
• /
• pp.123-130
• /
• 2011

Objectives of this study were to compare the environmental effects of digestates produced in bioenergy village on the rice paddy field for recycling. Digestates were applied to the soils and the soil properties and the crop responses were analyzed according to the standard methods of soil evaluation. Plant height and the number of tiller showed similar results in both the conventional and digestate treated field, and the yield of rough rice was higher in the field treated with digestates than that with chemical fertilizer. The amounts of nitrogen absorbed in straw and grain were larger in the digestates-treated field than chemical fertilizer-treated one, and efficiency of nitrogen applied was shown to be the highest in 100% treated digestate of the pig manure. Exchangeable cation and pH increased in the soil treated with digestate after harvesting, but salt was not accumulated. With these results, it was concluded that resource recycling in green town can be facilitated through the securement of arable lands for the application of digestates and the proper use of these fertilizers. Long-term effects of digestate application on the soil environment should be sustainingly studied.

• Applied Chemistry for Engineering
• /
• v.30 no.2
• /
• pp.226-232
• /
• 2019

The biological wastewater treatment is more eco-friendly and can be used effectively in wastewater for a variety of purposes than that of the conventional treatment. In particular, the wastewater treatment using microalgae in biological treatment processes has attracted great attention due to its ability to remove economically nutrients from wastewater and have many advantages as a renewable energy source. This study was investigated to establish the optimal growth conditions for microalga Scenedesmus obliquus. Additionally, the removal efficiencies of nutrients (N, P) and heavy metals (Cu, Zn) from the synthetic wastewater were evaluated. As a results, the optimal growth conditions were established at $28^{\circ}C$, pH 7, and light and dark cycle of 14 : 10 h. In the evaluation of nutrient removal efficiencies at each concentrations of 500, 1,000, 5,000, and 10,000 mg/L, the removal rates were 17.6~70% N and 8.4~34% P in the single treatment and 12.0~58.0% N and 3.0~40.3% P in the binary mixture treatment. In addition, the evaluation of heavy metal removal efficiencies at each concentrations of 10, 30 and 50 mg/L, the removal rates were 13.7~40.3% Cu and 10.0~30.0% Zn in the single treatment and 16.0~40.0% Cu and 12.0~20.0% Zn in the binary mixture treatment. Based on the results of the study, it appears that Scenedesmus obliquus can be used for the removal of nutrients and heavy metals from the swine wastewater.

• Journal of the Korean Wood Science and Technology
• /
• v.43 no.3
• /
• pp.374-380
• /
• 2015

The quality characteristics of the woodpellet manufactured from two domestic pines (Pinus densiflora S. et Z. and Pinus rigida Mill.) were investigated for the efficient energy use of woody biomass resources. Properties of woodpellets such as moisture content, heating value, ash content, apparent density and durability were determined by using the standard test method of woodpellets of Korea Forest Research Institute (KFRI) and elemental analysis. The results of elemental analysis for C, H, O and N showed 61.42% carbon, 5.56% hydrogen, 32.87% oxygen, and 0.15% nitrogen for Pinus densiflora S. et Z. and 61.03% carbon, 5.96% hydrogen, 32.83% oxygen, and 0.18% nitrogen for Pinus rigida Mill. No significant difference between Pinus densiflora S. et Z. and Pinus rigida Mill was observed on elemental analysis. Heating values of each woodpellet were ranged from 19.00 to 19.42 MJ/kg which satisfied the first grade quality standard (${\geq}18.0MJ/kg$) by KFRI. The ash contents of woodpellet were slightly different between Pinus densiflora S. et Z. and Pinus rigida Mill., and satisfied the first grade quality standard (${\leq}0.7%$) by KFRI. Apparent density of woodpellet (Pinus densiflora S. et Z.) was passed the first grade standard level (${\geq}640kg/m^3$), and woodpellets from Pinus rigida Mill. satisfied the second grade quality of the standard. The moisture contents of each woodpellet were satisfied by the first grade quality standard (${\leq}10%$). The durability of woodpellet (Pinus densiflora S. et Z.) was passed the third grade level (${\geq}95%$), but Pinus rigida Mill. woodpellet was insufficient to satisfy the quality standard.

• Journal of Plant Biotechnology
• /
• v.42 no.3
• /
• pp.161-167
• /
• 2015

Sweetpotato [Ipomoea batatas (L.) Lam] grows well in harsh environmental conditions, and is cultivated as one of the top seven food crops in the world. Recently, sweetpotato is drawing interest from people as a healthy food because it is high in dietary fiber, vitamins, carotenoids and overall nutrition value. However, few studies have been conducted on sweetpotato genome sequencing in spite of its importance. This review is aimed at increasing the efficiency of sweetpotato genome sequencing research as well as establishing a base for gene utilization in order to control useful traits. Recently, animal and plant genome sequencing projects increased significantly. However, sweetpotato genome sequencing has not been performed due to polyploidy and heterogeneity problems in its genome. Meanwhile research on its transcriptome has been conducted actively. Recently, a draft of the diploid sweetpotato genome was reported in 2015 by Japanese researchers. In addition, the Korea-China-Japan Trilateral Research Association of Sweetpotato (TRAS) has conducted research on gene map construction and genome sequencing of the hexaploid sweetpotato Xushu 18 since 2014. The Bill & Melinda Gates Foundation launched the 'sweetpotato genomic sequencing to develop genomic tools for Sub-Sahara Africa breeding program'. The chloroplast genome sequence acquired during sweetpotato genome sequencing is used in evolutionary analyses. In this review, the trend of research in the sweetpotato genome sequencing was analyzed. Research trend analysis like this will provide researchers working toward sweetpotato productivity and nutrient improvement with information on the status of sweetpotato genome research. This will contribute to solving world food, energy and environmental problems.

• Korean Journal of Ecology and Environment
• /
• v.43 no.1
• /
• pp.55-68
• /
• 2010

The seasonal variation of microbial community, based on the bacteria, heterotrophic nanoflagellates (HNF), phytoplankton and ciliates, was investigated at three sites in the eutrophic brackish water of Lake Shihwa and its adjacent areas from May 2007 through May 2008. At the upstream-region site St. 1, compared to the other two sites, significantly lower salinities and higher concentrations of nutrients and chlorophyll $\alpha$ (Chl. $\alpha$) were recorded. The annual average abundances of bacteria at St. 1, St. 2 and St. 3 were $6.8{\times}10^6$, $7.4{\times}10^6$ and $4.6{\times}10^6\;cells\;mL^{-1}$, respectively. As for the annual average concentrations of HNF, $19{\times}10^2$, $6.7{\times}10^2$ and $5.9{\times}10^2\;cells\;mL^{-1}$, were recorded in St. 1, St. 2 and St. 3 respectively. The highest ciliate abundance appeared at St. 1 on 29 April, 2008 and in which, 99% were autotrophic ciliate Mesodinium rubrum (Myrionecta rubra). Significant linear correlations between the biomass of bacteria and Chl. $\alpha$ were found, however, no significant relationships between ciliates abudance/biomass and their prey organisms were detected in all three sites, implying relatively low energy transfer efficiencies between them. These results indicated that the trophic relationship between ciliates and their prey organisms in the microbial community might be influenced by indirect route since higher trophic level organisms did not directly correlate to those of lower trophic level, although high primary productions were detected in the eutrophic brackish water of Lake Shihwa and its adjacent areas.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.32 no.4
• /
• pp.470-475
• /
• 1999

This study was conducted to evaluate the utilization of animal by-product mixture (ABPM) as a dietary animal protein source of fish meal replacer, and to determine the effect of dietary chromic oxide in growing rainbow trout, Oncorhynchus mykiss. ABPM is a mixture of five anmial by-products such as meat and bone meal (MBM) feather meal (FM), squid live, powder(SLP), poultry by-product (PBP) and blood- meal (BM) at a specific weight based ratio. Diet 1 and 2 were formulated on a isonitrogenous and a isocaloric basis of $46.5\%$ crude protein and 16.7 KJ/g diet; diet 1 (WFM 100), $100\%$ of the animal protein source came from white fish meal; diet 2 (ABPM 40), $60\%$ WFM+$40\%$ ABPM as the animal protein source; diet 3 (-Cr) commercial diet without chromic oxide; diet 4 (+Cr), commercial diet with chromic oxide. After eight weeks of feeding trials, fish fed diet 2 had a significantly lower body weight gain (WG) and feed efficiency (FE) than that of fish fed the other diets (P<0.05). When comparing diet 3 with diet 4, no significant differences were found in WG and FE (P>0.05). There were no significant differences on condition factor, hematocrit level, serum phosphorus, bone phosphorus, whole body phosphorus, and bone ash among fish from all four diet groups. Fish fed diet 4 had a significantly higher whole body lipid than that of fish fed the other diets (P<0.05), These results indicated that ABPM could be used less than $40\%$ in growing rainbow trout with a sufficient period of acclimation, In addition, the $0.5\%$ of chromic oxide can be used to determine the apparent digestibility of the nutrients in the feed without any adverse effects on growth and body composition.

• International Area Studies Review
• /
• v.22 no.3
• /
• pp.3-27
• /
• 2018

This paper analyzes Cuba's market-oriented reforms to alleviate essential problems with socialist countries such as soft budget constraints and incentive problems. It also discuss about effectiveness of industrial policy as a development strategy. The soft budget constraints and incentive problems resulted in the collapse of Soviet bloc and COMECON in early 1990s. After the collapse, Cuban economy suffered a steep dive, and national income tumbling down rapidly. Cuban faced serious shortages of food, gasoline, and other basic necessities of life. To halt and partially reverse economic downturn and dire austerity in the 1990's, the Cuban government made some partial reforms to the inherited Soviet system of cental planningand faced severe shortage in food, energy, and daily necessities. In response to the economic crisis. Cuba introduced economic reforms and implemented industrial policy as a development strategy as long as Cuba maintained a strong socialist country. Cuban government established the economic free zone law and attempted to induce foreign direct investment by implementing export-led industrial policy. Fiedel Castro approved the Law No. 165 "Free Zones and Industrial Parks", in 1996. However, Cuba's ESZ strategy seems to have failed because of the U.S. sanctions, but also because of Cuba's own policies, which do not allow foreign investors to hire workers directly and impose a high implicit tax on wages. By limiting advanced techniques of personnel and organization management, indirect employment can result in lowering work efforts and productivity of workers, and aggravating production efficiency in the ESZs. Another reason to fail comes from the double wage structure due to the double monetary-exchange rate system. Most of the high non-wage costs result from the double exchange rate system. Due to Cuba's imbalanced industry and production structures, concentrated labor force, and urbanization and centralization of agriculture production, the industrial transformation development model suggested by Lewis has not been successful unlike other Asian agriculture-led development model. Cuba has to overcome many difficulties in implementing industrial policy as a development strategy.

• Korean Journal of Poultry Science
• /
• v.12 no.1
• /
• pp.7-16
• /
• 1985

Present experiment was undertaken to compare the effects of two dietary fats whose free fatty acid content was quite different on performances and on meat quality of broilers. Yellow grease or animal fat (trade name) containing 15 or 38.6% free fatty acid, respectively, was added to the broiler starter and finisher diets at levels of 3.0 and 5,0%, respectively. A total of 108, day old, male Maniker(Chunho) broiler chicks was alloted to 3 dietary treatments with 3 replications per treatment and 12 chicks per replication Though control diet was not supplemented with fat, the three dietary groups were made isocaloric and isonitrogenous. All the chicks were ad libitum fed the test diets for 8 weeks. Feed intake and body weight were measured every other week. Shank color was measured at the end of feeding trial by Roche Color Fan. To evaluate meat quality, 7 chicks of mean body weight were selected from each treatment group after the trial. Measurements were made for abdominal fat content, organoleptic scores for thigh and breast, and for contents of total lipids, free fatty acids, iodine values and peroxide values of the breasts. During the period from 0 to 4 weeks of age, the broilers fed the diets added with fats performed the same as those fed the control diet. However, the body weight gam (25%), feed intake (10.8%) and feed efficiency (11.3%) of chicks fed the fat-supplemented diets, during the finisher period (5-8 weeks), appeared significantly improved compared to those of control group (p＜0.05). During overall period of 8 weeks, body weight gain, feed intake, and feed efficiency of chicks fed the diets added with fats were, on the average, 16.2. 8.8 and 6.8%, respectively, better than, those of control Monwhile the performance between the chicks fed diets added with the two different fat sources appeared to be of the same tendency. Though the shank pigmentation was not statistically different among the treatments, the chicks fed the fat-supple ented diets tended to have slightly less pigments than the control. Organoleptic scores of thigh or breast of chicks fed the animal fat diet were of the same range as those of the other two groups. The contents of total lipids, free fatty acids, iodine values and peroxide values of breasts from broilers fed the various diets appeared to be in the same ranges among the treatments. The values for control, yellow grease and animal fat groups were 7.77, 6.66 and 6.32% for total lipids, 9.23, 9.7 and 9.31mg oleic acid/g fat for free fatty acids, 65.36, 63.89 and 59.25g/ 100g fat for iodine values, and 9.62, 10.46 and 8.79 meq/kg fat for peroxide values, respect vely. Changes of free fatty acids contents of breast during a storage for 10 da s at 4$^{\circ}C$ were also not different among the dietary groups. From the observations n. this experiment, it seems possible to conclude that the animal fat containing 38.6% free fatty acid can be used as efficiently as yellow grease in broiler diets without any adverse effects on meat quality.