• Journal of the Korean Society of Propulsion Engineers
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• v.14 no.5
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• pp.57-64
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• 2010

A performance test of inter propellant seal for a 75 ton class turbopump is conducted using water to evaluate leakage and endurance performance. Each part of fuel pump side and oxidizer pump side for a prototype inter propellant seal has been tested for verifying endurance performance during total accumulated test time 2,100 sec in water. The fuel pump side part with one-stage seal of carbon floating ring shows average leakage rate 13.7 gram/sec under average seal differential pressure 9.4 bar. On the other hand, the oxidizer pump side part with two-stage seal assembly of carbon floating rings shows average leakage rate 7.3 gram/sec under average seal differential pressure 9.5 bar. After the endurance performance test, the inter propellant seal shows good physical condition. A leakage performance test of the inter propellant seal for cryogenic environment will be performed using LN2 in the near future.

• Proceedings of KOSOMES biannual meeting
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• 2004.11a
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• pp.49-56
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• 2004

It has been estimated that up to $80\%$ of all marine accidents have human elements as a cause. t of these, human elements of crew fatigue is main causes of marine accident. Crew fatigue involves sleep, schedule. workload. off-time. alcohol health and stress. With a ship handling simulator, the effect of alcohol on ship operational performance is studied for each 0.05 and $0.08g\%$ blood alcohol concentrations. A main effect for alcohol was found indicating that ship operational performance was significantly impaired by this alcohol relative to performance in the non-alcohol condition. The results of this research can be applied to minimize marine accidents as basic data.

• Proceedings of KOSOMES biannual meeting
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• 2007.11a
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• pp.1-7
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• 2007

To illustrate the variation of oceanic condition around artificial upwelling structure which is located in the South Sea of Korea, cm observations were carried out on December, 2005, April, August and October, 2006. Temperature, salinity and density(sigma-t) was nearly homogeneous through the whole depth by mixing of the seawater in winter. Stratification was not clear in spring, and it was only formed weakly in the surface layer shallower than 10m. Stratification was formed about $10{\sim}20$ m depth in summer and about $30{\sim}40$ m depth in autumn. Vertical gradient of temperature was larger than that in the part of western area along the artificial seamount in summer and autumn. The variation of stratification was also occurred around near the artificial structure area after set up structure.

• Proceedings of KOSOMES biannual meeting
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• 2007.11a
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• pp.51-55
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• 2007

As for satellite programs, the multipurpose satellite 1(KOMPSAT-1) was successfully launched on Dec. 21, 1999 and operated for three years. It is still properly operated even though its life cycle was ended. The development of KOMPSAT-2 (Korea Multipurpose Satellite-2) is near completion and the development of KOMPSAT-3, KOMPSAT-5 and COMS (Communication, Ocean, Meterological Satellite) are proceeding swiftly. In KORDI(Korea Ocean Research and Development Institute), the KOSC (Korea Ocean Satellite Center) construction project is being prepared for acquisition, processing and distribution of sensor data via L-band from GOCI(Geostationary Ocean Color Imager) instrument which is loaded on COMS(Communication, Ocean and Meteorological Satellite); it will be launched in 2000. Ansan(the headquarter of KORDD has been selected for the location of KOSC between 5 proposed sites, because it has the best condition to receive radio wave. The data acquisition system is classified antenna and RF. Antenna is designed to be ${\emptyset}$ 9m cassegrain antenna which has 19.35 $G/T(dB/^{\circ}K)$ at 1.67GHz, RF module, is divided into LNA(Low noise amplifier) and down converter, those are designed to send only horizontal polarization to modem The existing building is re-designed and classified for the KOSC operation concept; computing room, board of electricity, data processing room, operation room Hardware and network facilities have been designed to adapt for efficiency of each functions. The distribution system which is one of the most important systems will be constructed mainly on the internet, and it is also being considered constructing outer data distribution system as a web hosting service for to offering received data to user under an hour.

• Advances in concrete construction
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• v.10 no.5
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• pp.393-402
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• 2020

The given research focuses on examining the effect of relatively humidity (RH) and curing temperature on the hydrates as well as the porosity of calcium sulfoaluminate (CSA) cement pastes. Numerous tests, which consist of mercury intrusion porosimetry (MIP), thermosgravi metric (TG) and X-ray diffraction (XRD) were conducted. Various characterization techniques which include, scanning electron microscopy, Fourier transform microscopy along with X-ray diffraction evaluations were conducted on the samples to examine phase formation and crystallinity, morphology and microstructure along with bond formations and functional groups, respectively. During long-term study, the performance of concrete which consisted of limestone and flash-calcined was close to those from standard Portland cement concrete. Traditional classifications and methods of corrosion were widely used for the assessment of steel in concrete which may get employed to concrete which contains LC3 to recalibrate the range of polarization resistance for passitivity condition. For example, there is up to 79.5% and 146% respective flexural and compressive strengths. Moreover, they developed more advance electrical and thermo-mechanical performance with a substantial reduction in absorption of water of close to 400%. These advantages allow this research crucial to evaluate how these methods can be applied. Additionally, the research evaluates developed and more advanced cement preservation and repair techniques. The conclusion suggests concerted efforts by various stakeholders such as policy makers to enable low-carbon rates.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.1
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• pp.53-58
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• 2017

UFMC is known as the one among novel multi-carrier modulation techniques which are designed for replacing OFDM for 5G wireless communication systems. It is the generalized model of OFDM and FBMC, which combines the advantages of OFDM and FBMC and avoids their weak points. UFMC is more robust in synchronization condition like Time-frequency misalignment compared to CP-OFDM. Moreover UFMC is more proper to burst uplink transmission like M2M 5G Communications. In this paper we analyze the BER performance in various channels and speeds. The simulation result shows that the BER performance is lowered when mobile devices are moving fast and the BER performance is so sensitive for the good channel environment.

• Journal of agricultural medicine and community health
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• v.27 no.1
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• pp.1-8
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• 2002

Pest control is required for protecting the food supply and for controlling disease vectors. Unfortunately, there is no perfectly safe form of pest control. Pesticides are commonly used for pest control. Pesticides are defined under the US Federal Insecticide Fungicide and Rodenticide Act(FIFRA) as any substance or mixture of substances intended to prevent, destroy, repel, or mitigate pests, and any substance or mixture of substances intended for use as a plant regulator, defoliant, or dessicant(40 CFR Part 152). Currently in the United States, there are 890 active ingredients registered as pesticides. Approximately one billion pounds of active ingredient are used in the US per year. Unlike most chemicals(anti-neoplastic and anti-micobial medications are the principal exceptions), pesticides are specifically designed to kill and cause harm. Because society allows these chemicals to be disseminated into the environment, it is important to monitor the health effects associated with these releases. This represents an important justification for establishing and maintaining surveillance systems for acute pesticide-related illness and injury. A comprehensive, national surveillance system for acute pesticide-related illness and injury does not currently exist in the US. Although the United States has several surveillance systems for this condition, none provide a complete understanding of the problem of acute pesticide-related illness and injury. The Toxic Exposure Surveillance System(TESS) and Bureau of Labor Statisitics(BLS) are useful for assessing magnitude and trends. The state-based surveillance systems are more useful for timely identification of outbreaks and emerging problems. Efforts are underway to increase the number of states that conduct surveillance, and to broaden the use of the standardized case definition to facilitate aggregation of data across states. Through such efforts, a comprehensive, national surveillance system may be attainable.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.6 s.324
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• pp.1-7
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• 2004

The development of direct receiver techniques is expected to be a solution for future wideband or multi-band wireless systems based on software defined radio. In this Paper, we study the regeneration of I and Q signals for the SDR based direct conversion receiver, so that we can handle a wide bandwidth and maintain maximal flexibility in system utilization. After modeling the basic system considering the real wireless communication environment, and studying the impact of imperfect phase imbalance on the performance of a direct conversion receiver, we propose a suboptimal I and Q signal regeneration algorithm for the system. The proposed algerian regenerates I and Q signals using a real time early-late compensator which effectively estimates phase imbalances and gives feedback in a directreceiver. The proposed algorithm is shown to mitigate the impact of AWGN and improves performance especially at low SNR channel condition. According to the computer simulation, the BER performance of the proposed system is at least about 4 dB better than conventional systems under $45{\~}55$ degrees random phase errors.

• Journal of Digital Contents Society
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• v.17 no.4
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• pp.287-293
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• 2016

Some studies require sufficient amount of time, spaces, and financial condition for practical exercises and training. In particular for the Medical education, time and space limitation is very high and difficulties occurs, since the practices are done with cadavers (deceased human body). Many alternate 3D Virtual surgery training system exist currently, however the burdensome of obtaining those costly equipments is problematic. Providing the surgical environment as similar to real as possible using 3D Virtual Reality can be a solution to current problems. The effectiveness of training could be maximized with minimized costs without the general interfaces such as keyboard and mouse, but with Oculus Rift and Leap Motion. This paper will develop and practice the 3D Virtual Operation System with two devices to investigate the possibility and expand to other Simulation fields.

• Korean Journal of Human Ecology
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• v.9 no.3
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• pp.5-21
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• 2006

The purpose of this study was to grasp the consciousness of adolescents about their future in old aged housing. This research was executed with a questionnaire survey method. Data samples were collected from 255 students who finished first grade curriculum in high schools in Chonbuk province and Seoul city. The results were as followed. First, a healthcare plan was very highly recognized by students, and they wanted to live as couples or single in their old age. Second, the respondent students recognized elderly housing as a home for the aged, a silver town and nursing home. 72.1% of the respondents preferred a single detached house as an elderly house form. They preferred an elderly housing district with well provided convenient facilities for daily living. They wanted to live in the country or rest areas for the aged. They preferred an interior space composition with LDK with 2 bedrooms. 52.0% students wanted a neighborhood for their friends to live together. Third, 28.3% of the respondent students thought the appropriate time to move in elderly exclusive housing was 66-70 years old. And when their physical condition worsened or they needed care, they would. want to move into that housing. Also, they wanted the most convenient facility and a medical care facility in elderly exclusive housing. Forth, students' space design needs for elderly were high, more than 4 points. It was especially needed safety in space design, and this grade was 4.56(,53) points. Also the needs of safety and the convenient facilities.equipments were statistically significant by boys and girls.