• Journal of Korean Society of Environmental Engineers
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• v.32 no.10
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• pp.957-964
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• 2010

The deactivated catalyzed diesel particulate filter-trap (DPF) was remanufactured by ultrasonic wave treatment with various prepared solutions, followed by active component re-impregnation, and the emission control performance and surface properties of remanufactured DPF were studied at various remanufacturing conditions. The proper ultrasonic wave cleaning time at various prepared solutions and optimal re-impregnation amounts of active component for the best emission control performance of DPF were investigated and its performance tests were also carried out with various temperatures for the conversions of CO, THC (total hydrocarbon) and PM (particulate matter) by catalytic reaction test unit using bypass gas from the diesel engine dynamo system. It was found that the emission control performance of DPF remanufactured with the high-temperature air washing, ultrasonic wave cleaning at acid/base solutions and active component re-impregnation method was recovered to 95% level of its activity compared to that of the fresh DPF, which was caused by removing the deactivating materials from the surface of the DPF, through the analyses of performance test and their surface characterization by Optical microscope, EDX, ICP, TGA, and porosimeter.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.12
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• pp.969-976
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• 2011

In this study we aims to evaluate the effects of 1/3 mol% $Co_3O_4$ addition on the reaction, microstructure development, resultant electrical properties, and especially the bulk trap and grain boundary properties of $ZnO-Bi_2O_3-Sb_2O_3$ (Sb/Bi=2.0, 1.0, and 0.5) system (ZBS). The samples were prepared by conventional ceramic process, and characterized by XRD, density, SEM, I-V, impedance and modulus spectroscopy (IS & MS) measurement. In addition of $Co_3O_4$ in $ZnO-Bi_2O_3-Sb_2O_3$ (ZBSCo), the phase development, density, and microstructure were controlled by Sb/Bi ratio. Pyrochlore on cooling was reproduced in all systems. The more homogeneous microstructure was obtained in ZBSCo (Sb/Bi=1.0) system. In ZBSCo, the varistor characteristics were improved drastically (non-linear coefficient ${\alpha}$=23~50) compared to ZBS. Doping of $Co_3O_4$ to ZBS seemed to form $V^{\cdot}_o$(0.33 eV) as dominant defect. From IS & MS, especially the grain boundary of Sb/Bi=0.5 system is composed of electrically single barrier (0.93 eV) and somewhat sensitive to ambient oxygen with temperature.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.6
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• pp.128-136
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• 2007

It is well known that two representative methods satisfy EURO-IV regulation from EURO-III. The first method is to achieve the regulation through the reduction of NOx in an engine by utilizing relatively high EGR rate and the elimination of subsequently increased PM by DPF. However, it results in the deterioration of fuel economy due to relatively high EGR rate. The second is to use the high combustion strategy to reduce PM emission by high oxidation rate and trap the high NOx emissions with DeNOx catalysts such as Urea-SCR. While it has good fuel economy relative to the first method mentioned above, its infrastructure is demanded. In this paper, the number distribution of nano PM has been evaluated by Electrical Low Pressure Impactor(ELPI) and CPC in case of Urea-SCR system in second method. From the results, the particle number was increased slightly in proportion to the amount of urea injection on Fine Particle Region, whether AOC is used or not. Especially, in case of different urea injection pressure, the trends of increasing was distinguished from low and high injection pressure. As low injection pressure, the particle number was increased largely in accordance with the amount of injected urea solution on Fine Particle Region. But Nano Particle Region was not. The other side, in case of high pressure, increasing rate of particle number was larger than low pressure injection on Nano Particle Region. From the results, the reason of particle number increase due to urea injection is supposed that new products are composited from HCNO, sulfate, NH3 on urea decomposition process.

• Journal of Forest and Environmental Science
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• v.28 no.2
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• pp.84-96
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• 2012

A special type of indigenous knowledge on plants utilization and farming system was explored by the Garo tribe community in the North-East region of Bangladesh, which correspond to the severe dependence on homestead forest. Results show that the Garo are totally dependent on the natural resources and that the extent of their dependency is faithfully reflected in their ethno-botanical knowledge. Dependencies that the study addressed focused on various aspects of food, fruit, energy, timber and health care on plants products. Garo tribe community in Bangladesh followed agrosilvipastoral system in their homesteads. They have indigenous hunting procedure to trap the animal in the forest. A total of 9 foods, 15 fruits, 12 energy-producing and 11 timber species was found and recorded that the Garo used in their daily life. Moreover, Garo used 23 medicinal plants species and have vast indigenous knowledge about using herbal medicine in daily health care practices. The Garo women do mostly the household activities, managing homestead forest and helping agricultural field where men perform all hard working activities like ploughing, cutting trees, digging the soil, preparation of horticultural and agricultural land, hunting, etc. The overall quality of life of the Garo could be considerably upgraded if ethno-botanical issues and their own indigenous knowledge will complement with scientific knowledge. The findings of the study conclude that the conservation of the indigenous knowledge of the Garo tribe related to plants utilization can also be turned to good account in forest conservation and is an important tool in this tribal area of Bangladesh.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.30 no.2
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• pp.85-99
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• 2004

Purpose: This study observed the changes in the telomerase activity, it's developmental regulation, PCNA expression, and their correlation in rat's upper digestive organs during growth and aging. Materials and Methods: Upper digestive organs(buccal mucosa, gingiva, palate, submandibular and parotid glands, and tongue) were aseptically removed from Sprague-Dawley rats of fetal(gestational 20 days), growing(1, 2, 3, 5, and 7 weeks after birth) and adult(12 week old). Samples for telomerase activity were frozen on liquid nitrogen immediately after sacrifice, and stored until the use at $-75^{\circ}C$ in order to measure it. Telomerase activity was measured by a PCR-based telomeric repeat amplication protoco(TRAP) assay and quantitated with Photometric Telo TAGGG Telomerase PCR ELISA plus(Roche Diagnostics GmbH. Mannheim. Germany). PCNA expression were measured immunohistochemistry with anti PCNA Ab-1, Clone PC10(NeoMark. California. USA). Results: 1. Telomerase activities in buccal mucosa, palate and gingiva were the highest in fetus and decreased gradually or rapidly after birth and then diminished, but In salivary gland and tongue were the highest in fetus and also high at 1 week and then decreased rapidly. 2. PCNA expression in buccal mucosa, gingiva, Tongue and salivary gland was the highest in fetus and decreased gradually and then diminished. but only in palate decreased rapidly after birth and then diminished. Conclusion: The highest telomerase activity of embryonic stage decreased rapidly after birth in rat's upper digestive organs. There may be a developmental regulation of telomerase activity, but not a tissue-specific. This telomerase activity seems correlated closely with PCNA expression in rat's upper digestive system.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.7
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• pp.689-696
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• 2010

The Because of its high thermal efficiency, the direct injection (DI) diesel engine has emerged as a promising potential candidate in the field of transportation. However, the amount of nitrogen oxides ($NO_x$) increases in the local high-temperature regions and that of particulate matter (PM) increases in the diffusion flame region during diesel combustion. In the de-$NO_x$ system the Lean $NO_x$ Trap (LNT) catalyst is used, which absorbs $NO_x$ under lean exhaust gas conditions and releases it in rich conditions. This technology can provide a high $NO_x$-conversion efficiency, but the right amount of reducing agent should be supplied to the catalytic converter at the right time. In this research, the emission characteristics of a diesel engine equipped with a micro-reformer that acts as a reductants-supplying equipment were investigated using an LNT system, and the effects of the exhaust-gas temperature were also studied.

• Ocean and Polar Research
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• v.25 no.3
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• pp.331-345
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• 2003

The fishing ground surrounding Wangdol-cho is not only overexploited by the littering of dilapidated fishing net and equipment, but also by fishermen's overfishing, surpassing optimum fisheries resources. In addition, increasing fishing efforts (number of fishing vessel and fishing net, etc) contribute to the deterioration of fishing ground, and it is urgently required that schemes to tackle the problems should be taken. To effectively address the problems as such, this paper aims to propose sustainable utilization and management scheme of fishing ground through classification of fishing ground surrounding Wangdol-cho as one area which is less than 50m deep, measuring $13.66km^2$ and the other, permission fishing area of Gill Net fishery, measuring $347.23km^2$. The analysis shows that, for the water area less than 50m deep, implementation from a short-term perspective includes autonomous management fishery by gill net and trap fishery. For the permission fishing area of Gill Net fishery, implementation includes limit on fishing period, real name system of fishing equipment and limit on fishing equipment. Implementation from a medium and long-term perspective includes limit on scuba diving, designation of underwater sightseeing zone, sea farming, facilities of surveillance, adoption of approval system for the permission fishing area of Gill Net fishery and introduction of report system for fishing.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.52 no.3
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• pp.232-240
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• 2016

Marine casualties originated from fishing vessels occupied about 71.2% of the whole marine casualties in Korea from 2008 to 2014, which has not changed much for a long time. Therefore, a pragmatic counterplan to decrease in casualties in fishing vessel is indispensable for reduction of marine casualties in Korea. Since the casualties occurred by fishing vessels may incline to a specific type of casualties according to the difference in the operating type; in this paper, 11 fishing types which occurred casualties frequently in numbers and occupied ratio were selected. Since the most frequent occurring casualties in fishing vessels were from collisions and fire explosion in statistics from KMST (2008~2014), the study focused on them. The collision is given a great deal of weight in all the casualties mostly due to the negligence of duty regardless of the job types. Gill netter, trap fishing boat, jig boat, multiple fishing boat and stow netter have their own specific causes of casualties in collision according to the operating types. The cause of fire explosion was mainly due to poor inspection and maintenance the electric cord. For this reason, it may be necessary for an operator to make strict precaution on the other vessels under way systematically, keep the regulation for preventing collisions, and for an engineer on watch to make a check the electricity periodically to reduce the fire explosion.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.40 no.4
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• pp.203-210
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• 2017

Data clustering is one of the most difficult and challenging problems and can be formally considered as a particular kind of NP-hard grouping problems. The K-means algorithm is one of the most popular and widely used clustering method because it is easy to implement and very efficient. However, it has high possibility to trap in local optimum and high variation of solutions with different initials for the large data set. Therefore, we need study efficient computational intelligence method to find the global optimal solution in data clustering problem within limited computational time. The objective of this paper is to propose a combined artificial bee colony (CABC) with K-means for initialization and finalization to find optimal solution that is effective on data clustering optimization problem. The artificial bee colony (ABC) is an algorithm motivated by the intelligent behavior exhibited by honeybees when searching for food. The performance of ABC is better than or similar to other population-based algorithms with the added advantage of employing fewer control parameters. Our proposed CABC method is able to provide near optimal solution within reasonable time to balance the converged and diversified searches. In this paper, the experiment and analysis of clustering problems demonstrate that CABC is a competitive approach comparing to previous partitioning approaches in satisfactory results with respect to solution quality. We validate the performance of CABC using Iris, Wine, Glass, Vowel, and Cloud UCI machine learning repository datasets comparing to previous studies by experiment and analysis. Our proposed KABCK (K-means+ABC+K-means) is better than ABCK (ABC+K-means), KABC (K-means+ABC), ABC, and K-means in our simulations.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.21 no.3
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• pp.101-115
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• 2011

A botnet is a huge network of hacked zombie PCs. Recognizing the fact that the majority of email spam is sent out by botnets, a system that is capable of detecting botnets and zombie PCS will be designed in this study by analyzing email spam. In this study, spam data collected in "an email spam trail system", Korea's national spam collection system, were used for analysis. In this study, we classified the spam groups by the URLs or attached files, and we measured how much the group has the characteristics of botnet and how much the IPs have the characteristics of zombie PC. Through the simulation result in this study, we could extract 16,030 zombie suspected PCs for one hours and it was verified that email spam can provide considerably useful information in tracing zombie PCs.