• Journal of Korean Society of Environmental Engineers
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• v.36 no.4
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• pp.286-294
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• 2014

The purpose of this study is to investigate the effects of applying density current generator (hereafter referred to as DCG to large lakes on the operating conditions of DCG, de-stratification, water quality improvement and inhibition of algae occurrence. As a result of a survey conducted to derive the optimum operating parameters of DCG in a condition to minimize eco-toxicity, the following conclusions were obtained. During the survey period, a marked stratification appeared in September to October 2011 and May 2012. At this time, the average depth of water to form thermocline was found to be $5{\pm}2$ m, so the location of discharge port for the operation of DCG was determined to be about 5 m below from the surface. To minimize the adverse effects of benthos and obtain the effect of water mixture at the time of water circulation, the mixing ratio of surface water and deep water was designed to be 3:1 by means of ecotoxicological assessment on the DCG operating characteristics. To select the appropriate operating hours for DCG, DCG was operated by 12 hr, 24 hr, 36 hr and 48 hr. As its result, the formation of thermocline did not occur during the operation of 36 hr. Also, It was effected that start reoperating from 3rd day after stop 2days under the condition of operated during 36 hr with calculated power consumption. Under the above conditions, the results of DO and water temperature analysis during the operation of DCG showed that the stratification, which was distinct previously, appeared to be weak, and relatively lower levels than those before operation were found as a result of water quality analysis on COD and chlorophyll-a, which leads to the conclusion that the water body is maintained at a stable condition due to the circulation of water by the occurrence of density current resulting from the operation of DCG.

• Korean Chemical Engineering Research
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• v.58 no.4
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• pp.541-549
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• 2020

The Drug Delivery System (DDS) is defined as a technology for designing existing or new drug formulations and optimizing drug treatment. DDS is designed to efficiently deliver drugs for the care of diseases, minimize the side effects of drug, and maximize drug efficacy. In this study, the optimization of tripolyphosphate (TPP) concentration on the size of Chitosan nanoparticles (CNPs) produced by crosslinking with chitosan was measured. In addition, the characteristics of Fe₃O₄-CNPs according to the amount of iron oxide (Fe₃O₄) were measured, and it was confirmed that the higher the amount of Fe₃O₄, the better the characteristics as a magnetic drug carrier were displayed. Through the ninhydrin reaction, a calibration curve was obtained according to the concentration of γ-aminobutyric acid (GABA) of Y = 0.00373exp(179.729X)-0.0114 (R² = 0.989) in the low concentration (0.004 to 0.02 wt%) and Y = 21.680X-0.290 (R² = 0.999) in the high concentration (0.02 to 0.1 wt%). Absorption was constant at about 62.5% above 0.04 g of initial GABA. In addition, the amount of GABA released from GABA-Fe₃O₄-CNPs over time was measured to confirm that drug release was terminated after about 24 hr. Finally, GABA-Fe₃O₄-CNPs performed under the optimal conditions were spherical particles of about 150 nm, and it was confirmed that the properties of the particles appear well, indicating that GABA-Fe₃O₄-CNPs were suitable as drug carriers.

• The KIPS Transactions:PartC
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• v.18C no.5
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• pp.343-360
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• 2011

The objective of this paper is to analyze and characterize to simulate routing observations on end-to-end routing circuits and a ping experiment of a virtual network after modeling, such as IPv6 migration, an OSPFv3 routing experiment based on an IPv6 environment, and a ping experiment for IPv4/IPv6 dual-stack networks and IPv6 network for OSPFv3 routing using IPv6 planning and operations in an OPNET Modeler. IPv6 deployment based largely on the integrated wired and wireless network was one of the research tasks at hand. The previous studies' researchers recommended that future research work be done on the explicit features of both OSPFv3 and EIGRP protocols in the IPv4/IPv6 environment, and more research should be done to explore how to improve the end-to-end IPv6 performance. Also, most related work was performed with an IPv4 environment but lacked studies related to the OSPFv3 virtual network based on an end-to-end IPv6 environment. Hence, this research continues work in previous studies in analyzing IPv6 migration, an OSPFv3 routing experiment based on IPv6, and a ping experiment for IPv4/IPv6 dual-stack networks and IPv6 network for OSPFv3 routing. In the not too distant future, before enabling the default IPv6, it would help to understand network design and deployment based on an IPv6 environment through IPv6 planning and operations for the end-user perspective such as success or failure of connection on IPv6 migration, exploration of an OSPFv3 routing circuit based on an end-to-end IPv6 environment, and a ping experiment for IPv4/IPv6 dual-stack networks and IPv6 network for OSPFv3 routing. We were able to observe an optimal route for modeling of an end-to-end virtual network through simulation results as well as find what appeared to be a fast ping response time VC server to ensure Internet quality of service better than an HTTP server.

• Journal of Radiation Protection and Research
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• v.40 no.3
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• pp.162-167
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• 2015

Although the perfomance indicators of the nuclear power plants in Korea show optimal, it requires detailed analysis and discussion centered on the radiation dose. As analysis methods, analysis on the radiation dose of nuclear power plants over the past five years was assessed by comparing the relevant radiation dose of radiation workers and per capita average annual radiation dose of the world's major nuclear power stations was also analyzed. The radiation workers over the annual radiation dose limit of 50 mSv were not. The contrast ratio of the radiation exposure according to the reactor type was the normal operation of PHWR was 6.2% higher than those of the PWR. This shows the radiation work of PHWR during normal driving operation is much more than those of PWR. According to the Performance Indicators of the World Association of Nuclear Operator, the annual radiation dose per unit in 2013 showed 527 man-mSv of Korea is the best country among the major nuclear power generating states, the world average was 725 man-mSv. The annual per capita radiation dose is about 80% less than 1 mSv of the public dose limit and also the average per capita dose showed a very low level as 0.82 mSv. Workers in related organizations showed 1.07 mSv, the non-destructive inspection agency workers showed 3.87 mSv. The remarkable results were due to radiation reduced program such as development of radiation shielding and radiation protection. In conclusion, the radiation exposured dose of nuclear power plants workers in Korea showed a trend which is ideally reduced. But more are expected to be difficul and the psychological insecurity against the operation of the nuclear power plants is existed to the residents near the nuclear power plants. So the radiation dose reduction policy and radiation dose follow up study of nuclear power plants will be continously excuted.

• Journal of the Korean GEO-environmental Society
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• v.13 no.9
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• pp.5-16
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• 2012

In the case of using the soil materials created by cutting in-situ ground directly without adjusting particle size, it is recommendable to seek the compaction property or material constant required for filling design or density control through indoor test, and many studies on this subject have been carried out during that time. The researches conducted during that time, however, were focused on the mixed materials with different diameters that exist in a natural condition. There has been no study conducted using coal fly ash that is by-product of the thermal power plant that is actively considered as the building materials. Therefore, this study was aimed at implementing compaction test and examining the basic engineering property in order to explore the influence of crushing the particles through compacting the admixture of crushed stone and coal fly ash produced from thermal power plant on its engineering property, and then the impact of the admixture volume of each material on compaction property and material property by conducting the One-Dimensional Compression Test. As result of compaction test, the optimum moisture ratio of coal fly ash was shown to be approx. 23%. As result of compaction test in accordance with the mixed ratio of coal fly ash and crushed stone under the same compaction energy and moisture ratio, dry unit weight tended to drop when the mixed ratio of coal fly ash exceeded 30%, while it reached approx. $1.81gf/cm^3$ when the mixed ratio was 30%. As result of One-Dimensional Compression Test in accordance with the mixed ratio of crushed stone and coal fly ash, the change in void ratio by particle crushing was at the highest level in the case of coal fly ash 100%, while the lowest level in the case of crushed stone 100%. In the case of mixed materials of crushed stone and coal fly ash, compression index was at the lowest level in case of coal fly ash 30%, and therefore this ratio of mixed material was judged to be the most stable from an engineering aspect.

• Journal of the Korean Institute of Landscape Architecture
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• v.44 no.5
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• pp.59-67
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• 2016

In landscape design by public institutions, although the costs and species of landscape trees stipulated by the Korean Public Procurement Service(PPS) are generally adhered to, the PPS regulations about planting trees with well-developed rootlets are almost entirely neglected. This study aimed to evaluate the performance of buried container modules, which are a new technology and product in landscape production that is able to reduce the defect rate while complying with regulations. To this end, this study measured rootlet density, rootlet development length, rootlet survival rate on excavation, and impairments of tree growth for 3 months after root pruning, and compared these variables for the container modules with those for trees that underwent root pruning in bare ground, and those that were cultivated in a container above ground. The results were as follows: First, the rootlet density was 88% for the trees in container modules, which was very high. Trees that underwent standard root pruning in bare ground had a somewhat lower density of 64%. Meanwhile, the trees that were cultivated in pots above ground died, invalidating measurement. Second, in terms of rootlet development and rootlet survival rate, the trees in container modules showed a mean length of 10.4cm, and 100% survival rate, indicating that there was no rootlet damage caused by excavation. For the trees that only underwent root pruning in bare ground, the mean length was 25.6cm and the rootlet survival rate was only half that of the trees in container modules, at 56%, demonstrating considerable damage. Rootlet development did not occur at all in the trees grown in pots. Third, the trees in container modules and those that underwent root pruning in bare ground did not show any deaths during the root pruning process, or any impairments such as stunted leaf growth. Conversely, the trees grown in pots nearly all died, and severe impairments of tree growth were observed. As shown by the results above, when we evaluated the performance of buried container modules, they showed the most outstanding performance of the three models tested in this study. The container modules prevent defects by stimulating early rooting in environments that with poor conditions for growth, or in trees that are not suited to the summer environment Therefore, it is expected that they would be an optimal means by which to enable compliance with rules such as the regulation presented by the PPS.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.6
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• pp.715-721
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• 2007

Residual calcium concentration is high, in general, at the effluent of the fluoride removal process in the electronics industry manufacturing semiconductor and LCD. To increase the stability of the membrane process incorporated for reuse of wastewater, the residual calcium is required to be pre-removed. Hyperkinetic Vortex Crystallization(HVC) process was installed in the electronics industry manufecturing semi conductor as a pilot scale for accelerating calcification of calcium ion. Compared to the conventional soda ash method, the 31% higher calcium removal efficiency was achieved when HVC was applied at the same sodium carbonate dosage. In order to maintain the economic calcium removal target of 70% preset by manufacturer, the dosing concentration of the soda ash was 530 mg/L based on influent flowrate. The seed concentration in the reactor was one of the critical factors and should be maintained in the range of $800\sim1,200mg$ SS/L to maximize the calcium removal efficiency. The calcite production rate was 0.30 g SS/g $Na_2CO_3$ in the average. The economic HVC passing time of the mixture was in the range of $2\sim5$ times. Relatively, stable calcium concentration was maintained in the range of $30\sim72$ mg/L(average 49 mg/L) although the calcium concentration in the feed was severely fluctuated with $74\sim359$ mg/L(average 173 mg/L). The HVC process was characterized as environment-friendly technology reducing chemical dosage and chemical sludge production and minimizing maintenance cost.

• Journal of Food Hygiene and Safety
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• v.28 no.2
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• pp.124-129
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• 2013

The method for detection foods containing allergenic materials by PCR was developed in this study. To detect allergenic raw material from processed food, species specific primer which up to 200bp for PCR product were designed or selected from advanced research. As target materials, 14 items were selected (12 target materials for allergen in Korea, 2 target materials for allergen in foreign countries). The amplicon size for eggs, milk, buckwheat, peanuts, beans, wheat, mackerel, crab, shrimp, pork, peach, tomato, almond, and sesame were confirmed 281, 131, 138, 120, 118, 127, 211, 174, 231, 138, 174, 132, 103, and 220bp, respectively. And any non-specific bands were not detected among each others. Detection method for allergenic material developed in this study could be used to investigate inaccurate goods for allergen labeling or non-intentional contaminant during processed foods manufacturing. In addition, the system will be usefully to detection accurate allergenic raw materials of export for other countries.

• Korean Journal of Agricultural and Forest Meteorology
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• v.16 no.2
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• pp.103-113
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• 2014

Under climate change, it is likely that the suitable area for forage crop cultivation would change in Korea. The potential cultivation areas for italian ryegrass (Lolium multiflorum L.), which has been considered one of an important forage crop in Korea, were identified using the EcoCrop model. To minimize the uncertainty associated with future projection under climate change, an ensemble approach was attempted using five climate change scenarios as inputs to the EcoCrop model. Our results indicated that most districts had relatively high suitability, e.g., >80, for italian ryegrass in South Korea. Still, suitability of the crop was considerably low in mountainous areas because it was assumed that a given variety of italian ryegrass had limited cold tolerance. It was predicted that suitability of italian ryegrass would increase until 2050s but decrease in 2080s in a relatively large number of regions due to high temperature. In North Korea, suitability of italian ryegrass was considerably low, e.g., 28 on average. Under climate change, however, it was projected that suitability of italian ryegrass would increase until 2080s. For example, suitability of italian ryegrass was more than 80 in 10 districts out of 14 by 2080s. Because cold tolerance of italian ryegrass varieties has been improved, it would be preferable to optimize parameters of the EcoCrop model for those varieties. In addition, it would be possible to grow italian ryegrass as the second crop following rice in Korea in the future. Thus, it merits further study to identify suitable areas for italian ryegrass cultivation after rice using new varieties of italian ryegrass.

• Korean Journal of Agricultural and Forest Meteorology
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• v.20 no.2
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• pp.175-182
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• 2018

Knowledge of the optimum cultivation period for Chinese cabbage would help growers especially in spring in Korea. Growth and yield of Chinese cabbage in a temperature gradient chamber was evaluated for the growing periods of 64 days from three set of transplanting dates including March 6, March 20, and April 3 in 2017. Air temperature in the chamber was elevated step-by-step, by $2^{\circ}C$ above the ambient temperature. This increment was divided into three phases; i.e. low (ambient+$2^{\circ}C$, A), medium (ambient+$4^{\circ}C$, B), and high temperature (ambient+$6^{\circ}C$, C). The fresh weight of Chinese cabbage was greater under B and C conditions in the first period and A in the second period, which indicated that GDDs affected the fresh weight considerably. However, leaf growth (number, area, length, and width) did not differ by GDDs. Bolting appeared under A condition in the first period, which was caused by low temperature in the early growth stage. Soft rot was developed under C condition in the second period and all temperature conditions in the third period, which resulted from high temperature in the late stage. Fresh weight increased when GDDs ranged from 587 to 729. However, it decreased when GDDs > 729. The maximum expected yield (16.3 MT/10a) was attained for the growing period of 64 days from transplanting date during which GDDs reached 601. The GDDs for optimum cultivation ranged from 478-724 under which the yield was about 95% (15.5 MT/10a) of maximum fresh weight. Such an optimum condition for GDDs was validated at five main cultivation regions including Jindo, Haenam, Naju, Seosan, and Pyeongtaek in Korea. In these regions, GDDs ranged from 619-719. This suggested that the optimum GDDs for Chinese cabbage cultivation would range from 478-724, which would give the useful information to expect the cultivation periods for ensuring maximum yield.