• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.9 no.3
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• pp.1-10
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• 2013

Open loop geothermal heat pumps have great potential where the groundwater resources are sufficient. Performance of open loop geothermal heat pump systems is considered higher than that of ground source heat pumps. Head and power calculation of submersible pumps, heat pump units, and piping are numerically based on regression data. Results shows that the system performance drops as the water level drops, and the lowest flow rates generally achieve the highest system COPs. The highest achievable cooling system COPs become 6.34, 6.12, and 5.95 as the groundwater levels are 5m, 15m, and 25m. The highest heating system COPs also become 4.59, 4.37, and 4.20. Groundwater level and submersible pump selection greatly influence the system performance of open loop geothermal heat pumps. It needs to be analysed during the design process of open loop geothermal heat pump system, possibly with analysis tools that include wide range of pump product data.

• Journal of the Society of Naval Architects of Korea
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• v.45 no.5
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• pp.554-561
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• 2008

This paper deals with an intelligent digital ship which aims at development to support economic and safe services through an integration into the hierarchically layered digital signals such as ship's navigation, maneuvering and control signal and establishing a one-man bridge system in order to provide a support systems between ship and land station. This paper introduces the results of the mid-term project sponsored from Ministry of Commerce, Industry and Energy which consists of three sub-project such as INS(Intelligent Navigation System), AIS(Automatic Identification System), and IMIT (Integrated Maritime Information Technology). The INS system that can allow ships to navigate economically and safely through the integration and analysis of national data within the ship. AIS is a system that reports automatically on the location of the ship in order to prevent the collision between ships and between the ship and the land. IMIT is a integrated system for providing an efficient and economic support system between ships and the land and a ship-land platform and technologies.

• Journal of the Korean Solar Energy Society
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• v.31 no.5
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• pp.140-145
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• 2011

In this study, the performance and behavior of solar heating system according to the system control scheme, variable flow control (proportional control) and constant flow control (on-off control) was carried out by experiment. The on-off control is used generally for solar thermal system by now. But the proportional control is used for the solar district heating system which is supplied the higher temperature of water than that of desired. The proportional control logic that pump speed is varied in an attempt to maintain a specified outlet temperature of solar heating system was developed and tested for the use widely for the small and medium solar thermal system. The results are as following. First, the proportional controller which is made here could be adopted the characteristics for setting temperature control. Second, the proportional control is better than the on-off control in the side of the performance of thermal stratification in storage tank. Third, the operating energy(electricity consumption by pump) of solar thermal system can be saved more than 60% using the proportional control comparing to the on-off control.

• Journal of the Korean Institute of Gas
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• v.23 no.5
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• pp.44-51
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• 2019

The system components and implementation methods to be considered when constructing a system for plant safety training in a virtual environment were classified according to plant characteristics. When constructing a safety training system based on VR, the necessary components may be different according to the characteristics of the plant, and the basic system components to be built according to the target plant are presented. In order to support the proposed system, we implemented a city gas governor safety training system, which is a relatively simple facility. Through this, we propose guidelines for the construction of a suitable VR-based plant safety training system in the plant to be applied.

• Journal of Aerospace System Engineering
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• v.13 no.5
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• pp.16-23
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• 2019

This paper describes the design and analysis of a periscope imaging system installed at the engine test facility in the Agency for Defense Development. The periscope system is a cylinder-shaped image observation system installed at the rear of the engine and at the top of the diffuser. The periscope system has high risk of breaking because it is directly affected by high temperature (2300 K) and products of combustion. Thus, we used 1D heat transfer calculation, and 2D and 3D CFD analysis to confirm the heat flux and temperature distribution. Also, the cooling performance was verified. In the current design, using the periscope system, we can see flame shapes, control of the nozzle, and stability of the exhaust flow visually.

• Journal of Power System Engineering
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• v.21 no.1
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• pp.5-10
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• 2017

Pitch drive system in wind turbine is composed by the planetary gear system to satisfied its required performance such as long life and light weight for gear train. When the planetary gear system can reduce its volume and weight, the power consumption of the wind turbine can be reduced. In this study, the planetary gear system of the pitch drive system in medium-sized wind turbine is obtained for weight reduction by shape optimization method. And the planetary gear system is verified for their strength by the structural analysis.

• ETRI Journal
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• v.34 no.5
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• pp.649-654
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• 2012

This paper presents a novel 16-quadrature-amplitude-modulation (QAM) E-band communication system. The system can deliver 10 Gbps through eight channels with a bandwidth of 5 GHz (71-76 GHz/81-86 GHz). Each channel occupies 390 MHz and delivers 1.25 Gbps using a 16-QAM. Thus, this system can achieve a bandwidth efficiency of 3.2 bit/s/Hz. To implement the system, a driver amplifier and an RF up-/down-conversion mixer are implemented using a $0.1{\mu}m$ gallium arsenide pseudomorphic high-electron-mobility transistor (GaAs pHEMT) process. A single-IF architecture is chosen for the RF receiver. In the digital modem, 24 square root raised cosine filters and four (255, 239) Reed-Solomon forward error correction codecs are used in parallel. The modem can compensate for a carrier-frequency offset of up to 50 ppm and a symbol rate offset of up to 1 ppm. Experiment results show that the system can achieve a bit error rate of $10^{-5}$ at a signal-to-noise ratio of about 21.5 dB.

• The Korean Journal of Food And Nutrition
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• v.6 no.3
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• pp.158-168
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• 1993

For the conversion of WAD to NADP, Immobilized Brevibacterium ammoniagenes cells with NAD kinase was coupled with ATP-generating system by acetate kinase. The membrane permeability of B. ammoniagenes was improved by toluene treatment of cells. The toluene treated B. ammoniagenes cells were immobilized for stable enzyme activity. Partially purified acetate kinase was used in the reaction system. The optimum conditions for the efficient conversion of UAD to WADP by energy-coupled system were investigated. B. ammoniagenes cells treated with toluene for the Improvement of membrane permeability showed 4.5 fold improved permeability in the conversion of NAD to NADP compared with Intact cells. 3% k-carrageenan as the immobilization matrix of B. ammoniagenes showed the best efficiency for the conversion of NAD to NADP The optimum conditions for the WAR to WARP conversion reaction coupled nth ATP-generating system were 10mM acetylphosphate, 5mM ADP 200mM inorganic phosphate, 10mM MgCl2, 250mg/ml Immobilized cells, 49.3mUnit/ml acetate kinase, pH 7.5 and 37$^{\circ}C$. Under the optimum conditions, 72% of 5mM(340mg/ml ) NAD was converted to UADP In 12 hours.

• Korean Journal of Head & Neck Oncology
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• v.18 no.2
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• pp.179-183
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• 2002

Objective: A comparison of American Joint Committee on Cancer (AJCC) 1988 and 1997 nasopharyngeal carcinoma (NPC) classifications was made in terms of patient distribution and efficacy in predicting prognosis. Materials and Methods: Between Jan. 1981 and Dec. 1998, 60 cases of node negative nasopharyngeal carcinoma were retrospectively reviewed. The extent of disease each patients restaged according to the 4th and 5th AJCC system and Ho system, respectively. Results: The overall and disease free 5-year survival rates were 61.1% and 62.6%, respectively. Among T classifications of 4th AJCC, 5th AJCC and Ho staging system were not observed significantly different in disease-free survival rates, respectively. Conclusion: We observed a better patient distribution with AJCC 1997 comparing to AJCC 1988. The new classification also attained better statistical significances among stages in the overall survival and disease free survival rates was needed.

• Imaging Science in Dentistry
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• v.42 no.1
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• pp.1-4
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• 2012

Purpose : Hand-held dental x-ray system is a self contained x-ray machine designed to perform intraoral radiography with one or two hands. The issue about its usage as general dental radiography is still in dispute. The aim of the present study was to assess the relationship between the amount of battery charge and the tube voltage in different handheld dental x-ray systems. Materials and Methods : Seven hand-held dental x-ray units were used for the study. Tube voltage was measured with Unfors ThinX RAD (Unfors Instruments AB, Billdal, Sweden) for 3 consecutive exposures at the different amount of battery charge of each unit. The average and the deviation percentage of measured kV from indicated kV of each unit were calculated. Results : Tube voltage of only 1 unit was 70 kV (indicated by manufacturer) and those of the others were 60 kV. Tube voltage deviation percentage from the indicated kV at the fully charged battery was from 2.5% to -5.5% and from -0.8% to -10.0% at the lowest charged battery. Conclusion : Tube voltages of all units decreased as the residual amount of the battery charge decreased. It is suggested that the performance test for hand-held x-ray system should be performed for the minimum residual charged battery as well as the full charged one. Persistent battery charging is suggested to maintain the proper tube voltage of the hand-held portable x-ray system.