• Journal of the Korean Society for Precision Engineering
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• v.12 no.12
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• pp.30-37
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• 1995

The mechanical seals, which are installed in rotating machines like pump and compressor, are gengrally used as sealing devices in the many fields of industries. The failure of mechanical seals such as leakage,fast and severe wear, excessive torque, and squeaking results in big problems. To monitor the failure of mechanical seals and to propose the proper monitoring techniques with artificial neural network, sliding wear experiments were conducted. Torque and temperature of the mechanical seals were measured during experiments. Optical microstructure was observed for the wear processing after every 10 minute sliding at rotation speed of 1750 rpm and scanning electron microscopy was also observed. During the experiment, the variation of torque and temperature that meant an abnormal phenomenon, was observed. That experimental data recorded were applied to the developed monitoring system with artificial neural network. This study concludes that torque and temperature of mechanical seals wil be used to identify and to monitor the condition of sliding motion of mechanical seals. An availability to monitor the mechanical seal failure with artificial neural network was confirmed.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.09a
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• pp.144-147
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• 2003

In this study, the mass transfer behaviors of phenanthrene, anthracene, and pyrene in soil slurry reactor (SSR) using two-liquid phase (TLP) system were investigated. The mass transfer ratio and rate of PAH in the TLP system using light paraffine oil, which has the highest solubility of PAH, were influenced by the amount of light paraffine oil and mixing speed. When the amount of light paraffine oil decreased from 15 % to 2.5 % (v/v), the mass transfer ratio of anthracene decreased significantly compared with that of phenanthrene and pyrene. As mixing speed increased, the initial mass transfer rate of PAH within 1 day was enhanced. However, each final mass transfer ratio of three PAHs after 5 day was similar irrespective of mixing speed.

• Smart Media Journal
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• v.2 no.3
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• pp.54-61
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• 2013

NFC is a Near Field wireless Communication technology, comes to the fore as an important technology of Mobile Payment System with supply of devices and diffusion of services. Because of the fact that the NFC retail payment services, ticketing, smart cards are able to operate in one device, it(NFC Technology) can make disclosure of personal information and security risks. Thus, the problem of security in NFC technology is essential, and the need for research on security threats are increasing. In this paper, we wil analyze for NFC's vulnerabilities and security technology.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 1998.04a
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• pp.287-292
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• 1998

The purpose of the subjects described in this paper is to share the inforamation and utilize expensive equipmints and supercomputer at remote site ghrough the latist telecommunication and control technology without tempoual and spatial limitation. The major subjects areabstracted as two. One for developing computer supported cooperative works and experimintal systims which make it possible that researchers discuss about the result of collaborated research and exchange data. And the other for connecting the university, research institutes and industries in the country to information Highway applying developed systim. The gargeted filds of this project are Machinery Design, Chemistry and Chemical Engineering and wil be expanded to polymer Engineering, Medicine, Agricultural Chemicals.

• Proceedings of the Membrane Society of Korea Conference
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• 1991.04a
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• pp.9-9
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• 1991

This paper will begin by describing osmosis and how reverse osmosis works. It will show how osmotic pressure affects reverse osmosis operations. It uill explain salt rejection, membrane flux, and recovery rates and the affect that salt built up has on membrane performance. It wil 1 explain the limitations of RO performance and why pretreatment is important. It will describe the two basic types of membrane, asymmetric and thin-film composite and explain the difference between these types plus compare cellulose acetate types to aromatic polyamide type membranes. It will discuss operating efficiences as it compares to feedwater pressure, concentration, temperature and pH. Finally, it will discuss the differences between tubular, plate and frame, hollow fiber and spiral wound element design. It will be a paper that talks about the basics of RO systems and should give a person who is unfamiliar with RO a basic introduction to this type of separation technology.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 1999.10c
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• pp.271-276
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• 1999

This study is performed to evaluate an elastic properties and acid-resistance of concrete using pine needle ash(PNA). Materials used for this experiment are PNA , normal portland cement, natural fine and coarse aggregate. Test results show that the highest ultrasonic pulse velocity , dynamic and static modulus of elasticity is achieved by 5% PNA filled PNA concrete, which has showed similar with those of thei normal cement concrete. Acid-resistance of PNA concrete is increased with increase of the contnet of PNA , it is 1.29 times of the normal cement concrete by 5% PNA fille PNA concrete an d2.57 times by 15% PNA filled PNA concrete . Accordingly , PNA concrete wil greatly improve the properties of concrete.

• International Journal of Advanced Culture Technology
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• v.10 no.3
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• pp.57-62
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• 2022

This paper is intended to study the tragedy of Kim Sung-han's short stories 'Extreme' and 'Return'. The author describes the postwar chaotic reality as a tragic reality in the novel as the pain of the times people experience. In the novels "Extreme" and "Return," war is violence, and all human beings who participate in it are victims of the violence of war. However, in "Extreme," Tatsuko expresses her will to fight against the tragic reality in "Return." Kim Sung-han never wants them to stay in the tragic world, although the tragic reality of the main characters in his novel ends in a tragic ending. He wants them to fight against the tragic reality.

• Korean Journal of Oriental Medicine
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• v.1 no.1
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• pp.209-244
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• 1995

The time therapy in oriental medicine is to reserch physiological activity and pathological variation with time, or time with disease. In that, this therapy is to research the development of disease, progress, diagnosis, treatment, and the meaning of preventive medicine. The theory of time therapy has been developed form heaven-human corresponding principle, and fourtimes of seasons is related with human life. After that, this theory affects in yin-yang five circle principle and organ-meridian match system. The independent development was formed later, but the origin has progressed for a logn times. in relation with time therapy, traditional acupuncture therory suggested five semen. In twenty century, the doctor rheinhold voll suggested energy exchange theory, this theory is based on time therapy, but has partial differance also too. His oppinion is this´ the energy present in the body has a circulation following the acupuncture teaching, i.e., the organs and their meridians are flooded in a certain sequence by this flowing energy. This maximum times of the organs are of physiologic and pathologic significance to man. In next time, we will discuss the indivisual theory in detail, and wil have comparison, and considering too.

• Proceedings of the KIEE Conference
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• 2001.11a
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• pp.161-164
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• 2001

Transmuted impurity atoms formed in neutron-irradiated ZnO thin films were theoretically identified first and then experimentally confirmed by Photoluminescence (PL). ZnO thin films grown by plasma-assisted molecular beam epitaxy were irradiated by neutron beam at room temperature. Among eight isotropes naturely exiting in ZnO films, only $^{64}Zn$, $^{68}Zn$, $^{70}Zn$ and $^{18}O$ were expected to transmute into $^{65}Cu$, $^{69}Ga$, $^{71}Ga$ and $^{19}F$, respectively. The concentrations of these transmuted atoms were estimated by considering natural abundance, neutron fluence, and neutron cross section. The neutron-irradiated ZnO thin films were characterized by PL. In the PL spectra of these ZnO thin film, the Cu-related PL peaks were seen, but the Ga- or F-associated PL peaks were absent. This observation demonstrates the existence of $^{65}Cu$ in the ZnO. In this paper, emission mechanism of Cu impurities wil1 be described and the reason for the absence of the Ga- or F-associated PL peaks will be discussed.

• The Journal of the Korea institute of electronic communication sciences
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• v.10 no.4
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• pp.513-519
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• 2015

Static analysis is one of the software source code analysis tools. 9 static analysis methods of three groups are recommended by international electro-technical commission about software safety related standard in IEC 62279. In this paper we choose the proper static analysis method from IEC 62279 about the train wayside communication system, Shorten the time of railway signalling software development using LDRA tools. And it wil be useful to improve the effective development of the safety-related software.