• 한국가스학회:학술대회논문집
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• 2005.05a
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• pp.198-198
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• 2005

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.53 no.3
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• pp.149-156
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• 2004

This paper deals with the effective protection method for the household electric appliances against lightning surges invading from the Power lines. Direct or induced lightning is the main cause of the breakdown of household electric appliance. The most effective protection method is to install SPDs(surge protective devices) at household electric appliances. If SPDs were not installed at most household electric appliances, it is necessary to install SPDs on the mains. Therefore the propagation aspect and protection methods of lighting surges coming into household electric appliances through the mains was experimentally investigated. The in actual-sized test circuits results of protection method for 8 household electric appliances including computer monitors and TV set could be summarized as follows: The breakdown characteristics of household electric appliances from lightning surges were significantly changed with the their input impedance. Namely, the types of input impedance are classified into infinite, resistive or inductive impedances. Especially, the monitor for computer with inductive input impedance from lightning surges was relatively weak against lightning surges. It was confirmed that the self inductance of branch circuits on the mains have protection effect for household electric appliances against lightning surges invading from the power lines. Also the varistors installed at cabinet panel or circuit-breaker were more effective than multi-tap outlet with varistors. When installed varistors in cabinet panel and multi-tap outlet together, the surge protection effect is much more excellent in technical and economical aspects.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2005.11a
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• pp.125-130
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• 2005

This paper suggests an efficient method of protection ratio calculation and shows some calculated results applicable to frequency coordination in microwave relay system networks, and the net filter discrimination (NFD) associated with Tx spectrum mask and overall Rx filter characteristics has been examined to obtain the adjacent channel protection ratio. The protection ratio comprises several factors such as C/N of modulation scheme, noise-to-interference ratio, multiple interference allowance, fade margins of multi-path and rain attenuation, and NFD. According to computed results for 6.7 GHz, 64-QAM, and 60 km at BER $10^{-6}$, fade margin and co-channel protection ratio are 41.1 and 75.2 dB, respectively, In addition, NFD for channel bandwidth of 40 MHz reveals 28.9 dB at the first adjacent channel, which results in adjacent channel protection ratio of 46.3 dB. The proposed method provides some merits of an easy calculation, systematic extension, and applying the same concept to frequency coordination in millimeter wave relay system networks.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2000.05a
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• pp.115-121
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• 2000

As the development of industry water quality of river is going to bad because of waste water of an industrial complex and general home agricultural chemicals exhaust of $SO_3$ and CO gas acid rain and so on. Corrosion damage of boiler factory equipment and so forth occur quickly due to using of the polluted water resulting in increasing leak accident. Especially working life of hot water boiler using the polluted water becomes more short and energy loss increases. The cathodic protection method is the most economical and reliable one to prevent corrosion damage of steel structures. Mg-base alloys galvanic anode protection of cathodic protection method is suitable for than application of hot water boiler using water with high specific resistance such as tap water. This paper is studied on the cathodic protection characteristics of how water boiler. In tap water and 0.001mol/$\ell$ NaCl solution the characteristics of anodic polarization of Mg-base alloys galvanic anode and tube material is investigated the measurement of cathodic protection potential according to the time elaspsed is carried out.

• Journal of Photoscience
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• v.9 no.2
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• pp.236-239
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• 2002

Sunscreens have been advocated as an important means of preventing skin cancer. UV-induced immunosuppression is important for skin cancer development, yet the effectiveness of sunscreens in protecting the human immune system from UV radiation is unclear. The only currently accepted method of sunscreen rating is the Sun Protection Factor (SPF) based on prevention of erythema. We developed an in vivo non-invasive method for evaluating protection of the human immune system from UV radiation based on recall contact sensitivity to nickel, a common allergen. Using this system we showed that broad-spectrum sunscreens provide greater protection to the immune system than sunscreens which protect from UVB only. UVA was found to be immunosuppressive. We developed this technique to enable the study of solar simulated UV radiation dose responses and determined Immune Protection Factors (IPFs) for six commercially available sunscreens based on limits of protection from the dose response data. We found that the IPF did not correlate with the SPF and that protection from erythema therefore cannot be used to predict protection of the immune system. However, IPF was significantly correlated to the UVA protective capability of the sunscreens, indicating that sunscreen protection from UVA is important for prevention of immunosuppression. We recommend that sunscreens should be rated against their immune protective capability to provide a better indication of their ability to protect against skin cancer.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.10
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• pp.1212-1216
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• 2014

This study aims to find out the best anode location for buried pipelines. Numerical simulation program known as CATPRO (Elsyca, Belgium) were used for confirming the best location of anodes and the effects of impressed current cathodic protection system. Applied conditions for numerical simulation were similar to on-site environmental conditions for optimal application of cathodic protection system. Used criterion of cathodic protection was NACE SP 0169, which describes that minimum requirement for cathodic protection is -850mV vs. CSE. Various layouts for anodes' installation were applied, which were distance between anodes, anode installation location, and applied current. The areas where cathodic protection potential was lower than -850mV vs. CSE was limited up to 50m from anode installation locations. It was founded numerical analysis obtain cost-effective and efficient cathodic protection methods before design and application the impressed cathodic protection system to on-site environment.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.736-740
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• 2004

In order to overcome the problems of simulation methods, the power system transient stability assessment method using critical fault clearing time functions has been developed. Using the above method, this paper has developed the new method which can assess accurately and efficiently the effects of control and protection systems on transient stability which is the most important characteristic to assess in power systems. At first, critical fault clearing time functions CCT(W:load) are defined by taking notice of the fact that transient stability is mainly controlled by fault clearing time and load. Next, the method to be enable to assess accurately and efficiently the effects of control and protection systems on transient stability has been newly developed by using the above functions. Finally, it has been applied to the effect assessment in the occurrence of a three-phase fault in a model power system. Results of application have been clarified its effectiveness.

• Korean Journal of Agricultural Science
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• v.38 no.2
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• pp.315-324
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• 2011

Riparian vegetation distribution patterns and diversity relative to various fluvial geomorphic channel patterns, stream bank stabilization methods, and stream flow processes are described and interpreted for selected nature-friendly small stream bank protection of Goesan, central Korea. Idong Stream Pilot Project, which began in May 2003 and finished in December 2003, was selected to develop effective methods which was nature-friendly stream bank protection. The project aim to maintain or increase stream bank stabilization ecosystem goods and services while protecting downstream and stream bank ecosystem. A number of protecting methods which were a Flight of fieldstone, Vegetation block, Green river block, Stone net, Green environment block, Eco friendly cobble, Vegetation mat and Geo-green cell and Firefly block were applied on the bank of Idong stream. The stream sites have been monitored about vegetation conditions each method in 2007. We selected six points to separately investigate in left and right bank. The main purpose of this study was to find out suitable methods and to improve stream restoration techniques for ecosystem. On the stream bank, H environment block method (9.7) was the highest average of vegetation coverage and Firefly block method (3.87) was the lowest average in applied methods.

• Journal of Electrical Engineering and Technology
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• v.12 no.2
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• pp.612-620
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• 2017

Relay coordination in power system is a complex problem and so far, meta-heuristic algorithms and other methods as an alternative approach may not properly deal with large scale relay coordination due to their huge time consuming computation. In some cases the relay coordination could be unachievable. As the urgency for a proper approach is essential, in this paper an innovative and simple relay coordination method is introduced that is able to be applied on optimization algorithms for relay protection coordination. The objective function equation of operating time of relays are divided into two separate functions with less constraints. As the analytical results show here, this equivalent method has a remarkable speed with high accuracy to coordinate directional relays. Two distribution systems including directional overcurrent relays are studied in DigSILENT software and the collected data are examined in MATLAB. The relay settings of this method are compared with particle swarm optimization and genetic algorithm. The analytical results show the correctness of this mathematical and practical approach. This fast coordination method has a proper velocity of convergence with low iteration that can be used in large scale systems in practice and also to provide a feasible solution for protection coordination in smart grids as online or offline protection coordination.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.12
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• pp.6177-6200
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• 2018

In order to achieve the goal of protecting medical images, some existing watermark techniques for medical image protection mainly focus on improving the invisibility and robustness properties of the method, in order to prevent unnecessary medical disputes. This paper proposes a novel copyright method for medical image protection based on visual secret sharing (VSS) and cellular automata transform (CAT). This method uses the protected medical image feature as well as VSS and a watermark to produce the ownership share image (OSI). The OSI is used for medical image verification and must be registered to a certified authority. In the watermark extraction process, the suspected medical image is used to generate a master share image (MSI). The watermark can be extracted by combining the MSI and the OSI. Different from other traditional methods, the proposed method does not need to modify the medical image in order to protect the copyright of the image. Moreover, the registered OSI used to verify the ownership and its appearance display meaningful information, facilitating image management. Finally, the results of the final experiment can prove the effectiveness of our method.