• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.9
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• pp.1030-1038
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• 2007

This paper presents the measurement results of strength of electromagnetic wave for GSM-900/GSM-1800 band which is used in Europe. The Giryong village and Sosan field are selected as candidate regions according to the measurement results in Gijang-gun, Busan. The vertical polarizations is about 12 dBm higher than horizontal polarization at two candidate places, and it is measured 25 dBm lower than urban. The maximum value of measured strength of vertical polarizations in the cellular/GSM-900 bands are -65 dBm at Giryong village and -69 dBm at Sosan field, respectively. The maximum value of measured results of PCS/GSM-1800 bands are -90.5 dBm at Giryong village and -85 dBm at Sosan field, respectively, We confirm that the receiving strength of electromagnetic wave are very weak below -65 dBm at two candidate places and the signals of GSM frequency bands not affect to conversional system, then it is considered as a suitable place for GSM mobile field test.

• Resources Recycling
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• v.30 no.3
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• pp.55-62
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• 2021

In Korea, a good recycled product (GR) certification system was introduced in 1997 to improve resource and energy use efficiency. However, in industry and society, recycled products are not used well because of the lack of awareness of recycled materials. In this study, the status of domestic and international quality standards for nickel materials was investigated, and the purity and electrochemical properties of nickel sulfate prepared from ore and nickel sulfate recovered from waste lithium-ion batteries were evaluated during the electroplating process. As a result of the test, it was found that there is no quality difference between recycled nickel sulfate and high-purity nickel sulfate reagents when used in the electroplating industry.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.3
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• pp.181-192
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• 2022

Active vibration control system(AVCS) for helicopter enables to control the vibration generated from the main rotor and has the superb vibration reduction performance with low weight compared passive vibration reduction device. In this paper, FxLMS algorithm-based vibration control software of the light civil helicopter tansmits the control command calculated using the signals of the tachometer and accelerometers to the circular force generator(CFG) is developed and verified. According to the RTCA DO-178C/DO-331, the vibration control software is developed through the model based design technique, and real-time operation performance is evaluated in PILS(processor in-the loop simulation) and HILS(hardware in-the loop simulation) environments. In particular, the reliability of the software is improved through the LDRA-based verification coverage in the PIL environments. In order to AVCS to light civil helicopter(LCH), the dynamic response characteristic model is obtained through the ground/flight tests. AVCS configuration which exhibits the optimal performance is determined using system optimization analysis and flight test and obtain STC certification.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.335-338
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• 2009

The process of charging an oxidizer in the liquid propellant rocket can divide into the cooling of the oxidizer tank, the high flow charge, the small flow charge, and the replenishment charge for the correction of temperature. The oxidizer of the Naro(KSLV-I) first stage uses the liquid oxygen. And the flow rate and the temperature specification corresponding to each charge mode are presented for the requirement. The flow throttling valve and heat exchanger are installed in the oxidizer filling system in order to satisfy this kind of the flow rate and temperature requirement specification. In this research, by using the Flowmaster which is a commercial one-dimension thermo-fluidic analysis program, one dimensional flow system analyses was performed to predict the exact flow rate at each specific mode. Also, the flow rate correction sensitivity of the flow control valves was analytically determined to satisfy the flow condition refinement at each mode within the limited certification test.

• Journal of Energy Engineering
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• v.25 no.4
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• pp.74-84
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• 2016

After Sep. 2017, the LEV3 emission standard will be applied to gasoline and gas vehicles in Korea. This standard has HWFET and SFTP standard as well as FTP-75. Most of LPG vehicles were certificated as SULEV in Korea. Until now, only FTP-75 standard is applying for the certification but it is expected that HWFET and SFTP are used after beginning LEV3. In this paper, 8 LPG and 4 gasoline vehicles were tested on FTP-75 and SFTP to check whether the LPG vehicles can meet LEV3 SFTP standard or not and to suggest direction of development. Most of test vehicles did not meet the SFTP standard. To make up for the fault, fuel injection control improvement is needed.

• Journal of Aerospace System Engineering
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• v.14 no.spc
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• pp.49-55
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• 2020

The average probability of a lightning strike to transport aircraft operating in airline service has been estimated to be approximately one strike in every year (or one strike per 1,000 through 20,000 flight hours). The important thing is not the probability of a lightning strike to aircraft, but the fact that aircraft is struck by lightning. Therefore, lightning protection design for aircraft should be qualified and compliance with airworthiness standards related to lightning protection must be substantiated in the process of certification. In this paper, I studied means of compliance for lightning protection through analysis of some test cases, including the KC-100 airplane that firstly obtained civil type certificate in Korea. Based on this paper, it will be also necessary to study on the effect of lightning for space launch vehicles.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2007.11a
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• pp.768-773
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• 2007

Standardization to information attribute of construction material is continuous demanded through the life cycle of a construction project, and the productivity elevation is derived of contribution effect in construction market. This study surveyed the means of acquisition and attribute of information to a staff in purchase, which are effected on the revitalization of information circulation to the construction material Proposed the standardization to information attribute of construction material that is based on improvement and application to the information attribute. And information attribute is classified with construction process through analysis on test list of quality certification. This study also suggested representative attribute of quality information, for the elevation of safety and quality in construction industry. Therefore, logicality of common information is based by analysis of mathematical statistics, systemicity of quality information is applied by MasterFormat(2004)

• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.4
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• pp.425-432
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• 2021

In this paper, We produced supporting for ginseng cultivation facilities as a material recycling product of CPW(Complex Plastic Wastes, CPW) from households. And we analyzed the characteristics of material recycling products according to the amount of r-LDPE(Recycled low density polyethylene, r-LDPE) used. As a result, as the amount of recycled LDPE used increa sed, the tensile strength a nd elonga tion of ma teria l recycled products using CPW increa sed, but a sh decrea sed. When the recycled r-LDPE usage is 5% or more, the physical properties of the material recycling product using CPW stably satisfy the quality standard (GRM 3093-2021) of supporting for ginseng cultivation facilities.

• Journal of Aerospace System Engineering
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• v.12 no.6
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• pp.17-22
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• 2018

The amount of fuel, which affects aircraft endurance, needs to be measured accurately. This paper deals with the implementation of a fuel quantity measurement system that consists of capacitive fuel sensor, DAQ board, and Labview software. The main circuit of the implemented system for measuring fuel quantity is simulated with Pspice to identify parameters, which are related to the change of fuel quantity. After simulation, we established that Vrms changes with the variation of fuel amount. The Vrms, which is the output of fuel sensor, is transmitted to the Labview software via the DAQ board of the implemented fuel quantity measurement system. The fuel quantity is also calculated using this software. The present simulation results indicated that the accuracy of the implemented fuel quantity measurement system improved with the filter application.

• Journal of the Korea Society of Computer and Information
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• v.27 no.2
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• pp.9-14
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• 2022

In this study, we propose a method for moving a device such as a flexible air sculpture while stably maintaining the user's desired posture. To accomplish this, a robot system with a structure of a mobile robot capable of running according to a given trajectory was studied by applying the PI algorithm and horizontal maintenance posture control using IMU. The air sculptures used in this study often use thin strings in a fixed posture. Another method is to put a load on the center of gravity to maintain the posture, and it is a system with flexibility because it uses air pressure. It is expected that these structures can achieve various results by combining flexible structures and mobile robots through the convergence process of digital sensor technology. In this study, posture control was performed by fusion of the driving technology of AGV(Automatic Guided Vehicle),, a field of robot, and technologies applying various sensors. For verification, the given performance evaluation was performed through an accredited certification test, and its validity was verified through an experiment.