• Korean Chemical Engineering Research
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• v.46 no.3
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• pp.585-597
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• 2008

The aim of this study was to find an analytic solution to the problem of determining the optimal capacity (lot-size) of a batch-storage network to meet demand for a finished product in a system undergoing random failures of operating time and/or batch material. The superstructure of the plant considered here consists of a network of serially and/or parallel interlinked batch processes and storage units. The production processes transform a set of feedstock materials into another set of products with constant conversion factors. The final product demand flow is susceptible to short-term random variations in the cycle time and batch size as well as long-term variations in the average trend. Some of the production processes have random variations in product quantity. The spoiled materials are treated through regeneration or waste disposal processes. All other processes have random variations only in the cycle time. The objective function of the optimization is minimizing the total cost, which is composed of setup and inventory holding costs as well as the capital costs of constructing processes and storage units. A novel production and inventory analysis, the PSW (Periodic Square Wave) model, provides a judicious graphical method to find the upper and lower bounds of random flows. The advantage of this model is that it provides a set of simple analytic solutions while also maintaining a realistic description of the random material flows between processes and storage units; as a consequence of these analytic solutions, the computation burden is significantly reduced.

• Journal of Plant Biotechnology
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• v.38 no.4
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• pp.241-250
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• 2011

The most part of vegetable oils is accumulated as storage lipid, triacylglycerol (TAG) in seed and used as energy source when seed is germinated. It is also used as essential fatty acids and energy source for human and animal. Recently, vegetable oils have been more and more an important resource because of the increasing demand of vegetable oils for cooking and industrial uses for bio-diesel and industrial feedstock. In order to increase vegetable oils using biotechnology, over-expressing or repressing the regulatory genes involved in the flow of carbon into lipid biosynthesis is critical during seed development. In this review, we described candidate genes may influence oil amount and investigate their potential for oil increase. Genes involved in the regulation from biosynthesis of fatty acids to the accumulation oils in seed can be classified as follows: First, genes play a role for synthesis precursor molecules for TAG. Second, genes participate in fatty acid biosynthesis and TAG assembly. Lastly, genes encodes transcription factors involved in seed maturation and accumulation of seed oil. Because factors/genes determining oil quantity in seed is complex as mentioned, recently regulation of transcription factors is being considered more favorable approach than manipulate multiple genes for increasing oil in transgenic plants. However, it should be figured out the problem that bad agricultural traits induced by the overexpression of transcription factor gene.

• Korean Journal of Ecology and Environment
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• v.34 no.3 s.95
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• pp.192-198
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• 2001

The Kyongan Stream and the inlet part of Paltang Reservoir are under significant influence of the effluent of sewage wastewater treatment plant (SWTP) and untreated domestic wastewater (DOW). The fertility of wastewater was evaluated through bioassay using natural phytoplankton population diluted in five levels. The concentrations of $NH_4$, SRP and SRSi were positively correlated with the biomass of phytoplankton. P concentration showed stronger correlation (r = 0.959, p<0.001)than other nutrients. Compared with the initial concentrations, $NH_4$ concentrations in samples from SWTP and DOW decreased 96% and 7%, respectively during the cultivation, and those of SRSi decreased 97% and 60%. However, $NO_3$ concentrations in samples neither showed any particular change nor any increase. Chl-a concentration ranged between $20\;{\mu}g/l$ and $125\;{\mu}g/l$, which maximum value increased up to 83 times. Estimated from the relationship between chl-a and SRP, the P concentration that can maintain the biomass of algae under mesotrophic state (<25\;{mu}g$\;chl-a/l$) was $83\;{mu}g\; P/l$. The volume of flow to maintain this level solely by natural dilution was about $16{\sim}25$ times of in flowing volume in the stream. However, it is not feasible to tap water of such quantity. Therefore, it is imperative to build an advanced sewage wastewater treatment facility that can reduce $NH_4$ and SRP concentrations that promote the growth of phytoplankton in discharged water.

• Journal of Animal Environmental Science
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• v.9 no.2
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• pp.69-78
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• 2003

In this study, the energy conversion equipment from the radiation energy to mechanical energy by using n­pentane as the operating fluid was constructed and the performance to pump the water was tested for the utilization of solar powered water pump. The equipment was designed optimally, after the theoretical analyses of the water pumping head and water quantity per cycle were done. The pentane vapour temperature in the condenser and the temperature of the outlet water from the condenser became lowered and the heat transfer rate became higher with decreasing the water inlet level to the condenser. The temperature difference between the condenser and the water tank was significant. Therefore, the distance between the water tank and condenser was recommended to be shorten and the diameter of their connecting pipe was recommended to be narrow in order to reduce the resistance of the fluid passage and improve the heat transfer rate. The amount of water pumped was 1.6­2.4 liters. Mass flow rate of the cooling water became lowered when the cooling water pipe was prolonged from the condenser to improve the heat transfer rate.

• KDI Journal of Economic Policy
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• v.32 no.4
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• pp.35-73
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• 2010

This paper examines consumption dynamics in relation to asset prices in Korea. Empirical analysis based on the error correction model shows that personal consumption is affected by changes in asset prices but the consumption converges to the long-run level of consumption corresponding to the total income flow in two years. This adjustment in consumption implies that the consumption error, reflected in the error correction term, should have predictability for the future consumption growth during the adjustment period. It is found that the error correction term has a long-run predictability for consumption over up to about 3 years; thus, confirming the error correction model. It is also found that housing prices have larger effects on consumption compared with stock prices in Korea. In addition, the effects of income and asset prices on consumption show bigger effects during contractionary period than expansionary period in business cycles. This paper also analyzes effects of asset wealth that reflects changes in both price and quantity. It is found that asset wealth has a long-run effect on consumption in addition to total income as determinants of consumption. Since wealth effects usually indicate the long-run effect of changes in asset wealth on consumption that is not explained by labor income, which is the proxy for human source of wealth, it is estimated with labor income used as a control variable. According to the estimation, the marginal propencity to consume out of asset wealth is approximately 2%. It means that 1,000won increase in asset wealth may lead to 20 won increase in consumption.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.6
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• pp.625-631
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• 2014

In this study, according to increase of thermoelectric power plants that use LNG, LNG-FSRU(Floating-Storage and Regasification Unit) appeared and it is installed on the Topside in order to deliver in a gaseous state to consumers who are in the shore. This study about the study on the characteristics analysis of the system depending on changes in performance with the vaporization and temperature of the heat source. For the characteristics analysis of the system, we devided vaporization method into Ethylene glycol water vaporization method and sea water as a heat source. Then the system that can vaporize 200ton per hour of LNG of $-157.9^{\circ}C$ and 10,400kPa was configured, and according to the temperature of supplied sea water, required minimum flow rate value was calculated. Also in case of using Ethylene glycol Water as a vaporization method, providing for regional and seasonal factors such as decrease of temperature of water. The system is configured by adding a steam boiler of $174.5^{\circ}C$, 775kPa as heat source. The generation amount of the steam required according to the performance of the vaporizer compared to the water temperature changes in the steam boiler and the amount of required evaporative performance due to changes in the quantity of steam and Ethylene glycol Water was confirmed.

• Ecology and Resilient Infrastructure
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• v.3 no.4
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• pp.247-255
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• 2016

Non-point pollutants from surface runoff during rainfall exert adverse effects on urban river water quality management. In particular, the first flush effect during the initial phase of rainfall can deliver significant amounts of pollutant loads to surface waters with extremely high concentrations. In this study, a sustainable first flush effect management system was developed by using settling and filtration that require no additional power or chemicals. A pilot scale experiment has shown that the removal of total suspended solid (TSS), total nitrogen (TN) and total phosphorus (TP) are in ranges of 84 - 95%, 31 - 46%, and 42 - 86%, respectively. An Integrated Stormwater Runoff Management System (ISTORMS) was also developed to efficiently manage the developed system by linking weather forecast, flow rate and water quality modeling of surface runoff and automatic monitoring systems in fields and in the system. This study can provide effective solutions for the management of urban river in terms of both quantity and quality.

• Journal of Physiology & Pathology in Korean Medicine
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• v.21 no.2
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• pp.444-452
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• 2007

Acupuncture treatment cures disease by regulating the functional excessiveness or deficiency which occurs in the meridian and visceral organs, and by letting stagnated Qi and Blood flow through the whole body and then controlling Qi. Whether or not to have Qi feeling is the main factor needed to manifest the efficacy of acupuncture. So it needs the very stimulus to make Qi felt rather than the simple stimulus. In order to have Qi feeling, it needs to acupuncture a patient according to patient's thinness or fatness, constitution, richness or poverty and age. And also it needs to vary the way to acupuncture a patient according to meridian, kinds of pulse, degrees of disease, new or old diseases, seasons with a disease and local areas of disease. In order to ascertain that it is important for the quality and quantity of acupuncture stimulus and the state of feeling acupuncture to get the efficacy of acupuncture, the experiment was planned to confirm whether the form and Qi of subject has different result according to the stimulated duration and depth. On the basis of the report that acupuncture on derma, when using electroacupuncture at Zusanli(ST 36) which denotes small intestinal motility, is more efficient than full depth acupuncture, I got the following result, after I observed whether the stimulated duration and depth give different efficacy according to the sex and weights of rat in experiment. The increased effects of small intestinal motility by electroacupuncture on Zusanli(ST 36) appeared after stimulating full depth for thirty minutes without distinction of sex and weights. This significant change was observed only in the female experimental group when I distinguished the sex. The small interstinal motility in rats by electroacupuncture at zusanli(ST 36) decreased in the 10 minutes' stimulated group and 30 minutes' stimulated group by duration on the one hand, and derma-deep stimulated group and full depth stimulated group by the depth of stimulus on the other hand, as the weights increased. This result shows that the duration and depth of acupuncture depends on the differences of acupuncture points, sex of the experimental animals, ages, and, weights. And the further study on the experimental and clinical differences and sextual differences need to be continued on.

• Korean Journal of Community Nutrition
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• v.12 no.5
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• pp.617-629
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• 2007

To ensure the microbiological safety of food items prepared after cooking process, this study was aimed to identify the hazards related with cooked foods donated to foodbanks through quantitative microbial analysis. Five foodbanks located in Incheon and Gyeonggi area among government-dominant foodbanks were surveyed from February to June, 2007. Manager, recipient, donator, type and quantity of donated foot and facility and equipment were examined for the general characteristics of foodbank. The time and temperature of food md environment were measured at steps from after-production to before-distribution, and the microbial analysis was performed mainly with indicator organism and major pathogens. The amount of cooked foods donated to each foodbank was about 20 to 30 servings and consisted of 80% of total donated foods. Only three foodbanks had separate offices for foodbank operation and four institutions had at least one temperature-controlled vehicle. The flow of donated foods was gone through the steps; production, meal service and holding at donator, collection by foodbank, transport (or holding after transport) and distribution to recipients. It took about 3.8 to 6.5 hours at room temperature from after-production to before-distribution. Only aerobic plate counts (APC) and coliforms were found in microbial analysis. The APC after production were relatively high in $8.2{\times}10^5,\;7.4{\times}10^5,\;6.9{\times}10^5$ and $4.2{\times}10^5 CFU/g$ while $2.8{\times}10^6, \;9.4{\times}10^5,\;1.0{\times}10^6$ and $5.4{\times}10^5CFU/g$ before distribution in mixed Pimpinella brachycarpa, mixed chard mixed amaranth and mixed spinach, respectively. The levels of coliforms in mixed chard and mixed spinach were complied with the standards of the Ministry of Education and Human Resources Management The level of APC in boiled pork was increased from $< 1.0{\times}10 CFU/g$ to $4.0{\times}10^2 CFU/g$. One of delivery vessels was shown $6.2{\times}10^3 CFU/100 cm^2$ in APC, which was over the standards for environment. One of serving tables also showed the high level of $1.2{\times}10^3 CFU/100 cm^2$ in APC and $6.6{\times}10^2 CFU/100 cm^2$ in coliforms. These results suggest the sanitary management of holding at donator and the time-temperature control are key factors to ensure the safety of cooked foods donated to foodbank.

• Korean Journal of Agricultural and Forest Meteorology
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• v.12 no.4
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• pp.264-276
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• 2010

The objectives of this study were to introduce the methods of soil respiration measurement, to review soil respiration studies conducted in Korea, and to suggest potential issues generated from using various methods for soil respiration measurement. According to the measurement principles, the methods of soil respiration measurements are classified as: alkali absorption method (AA), closed chamber method (CC), closed dynamic chamber method (CDC), and open flow method (OF). Based on the litereaure review on soil respiration studies in Korea, the CDC method was mostly used by the researchers (62%), followed by the AA (17%), OF (13%) and CC (8%) methods. Along with these methods, various instruments were used such as LI-6400-09, EGM-3, EGM-4, and automatic soil respiration chamber. Most of the soil respiration measurements were carried out in forest ecosystems and the reported soil respiration showed a wide range of variations from 130 to 900 mg $CO_2\;m^{-2}h^{-1}$. Continuous monitoring of soil respiration with minimal disturbance and the potential inconsistency in measurements are still the challenges facing the researchers, causing a paucity in quality datasets of sufficient quantity. Few attempts of intercomparison among different methods hinder the data users from synthetic analysis and assessment of the collected datasets. In order to better estimate soil carbon budget and understand their exchange mechanisms in key ecosystems of Korea, it is necessary to measure soil respiration at various plant functional types, soils, and climate conditions over a decadal time scale along with the study on the partitioning of soil respiration into autotrophic and heteorotrophic components.