• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.25 no.12
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• pp.807-814
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• 2015

A control rod drive mechanism(CRDM) is a reactor regulating system, which inserts, withdraws or maintains a control rod containing a neutron absorbing material within a reactor core to control the reactivity of the core. The top-mounted CRDM for Jordan Research and Training Reactor(JRTR) with 5 MW power has been designed and fabricated based on the HANARO's experience through KAERI and DAEWOO consortium project. This paper describes the performance qualification test results to demonstrate the operability of a prototype and four production CRDMs during the reactor lifetime. The driving performance, the drop performance and the endurance tests for CRDM are carried out at a test rig simulating the actual reactor conditions. A vibration of internal components due to the coolant flow is also measured using a laser vibrometer. As a result, the CRDMs are driven having a good driving performance without a malfunction between command and output signals for the stepping motor. Also, the pure drop time and the impact acceleration are within 0.72 s and 4.2 g to meet the design requirements, and the vibrational displacement of control rod is measured as maximum $5.2{\mu}m$.

• The Journal of the Korea Contents Association
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• v.16 no.9
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• pp.78-84
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• 2016

Weapon, command, and communication system have been continually developed in the Korean military since last several decades. However, it is always asked to make a more effort on improving the ability of combat capability through people in order to achieve and maximize military power. In terms of improving the battlefield leadership, this research focused on ROTC(Reserve Officers'Training Corps), because the training junior officers lays a great foundation on basic strength of the military. This study theoretically and empirically examined the ROTC's quality and effectiveness of leadership. The proposed research model and hypotheses are mainly composed of four factors: personality, esprit de corps, and professionalism as independent variables; leadership effectiveness as a dependent variable. The empirical result revealed that esprit de corps, professionalism, and personality have a meaningful influence on leadership effectiveness. It is suggested that an ongoing training and education program of leadership for ROTC should be applied for achieving a better leadership effectiveness on the battlefield.

• The Journal of the Acoustical Society of Korea
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• v.28 no.5
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• pp.483-490
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• 2009

In this paper, we develop a speech interface that has acoustic echo cancelling and barge-in functionalities in the car environment. In the echo canceller, DT (Double-Talk) detection algorithm using the correlation coefficients between reference and desired signals can make DT detection errors often in the background noise. We reduce the DT detection errors by using the average power of noise and echo estimated from the input signal. In addition, to make it possible for drivers to give speech command to the system by interrupting the speaker output, barge-in functionality is implemented with the combination of DT detection and appropriate gain control of the speaker output. Through the computer simulation with the assumed car environment and experiment in the real laboratory environment, implemented speech interface has shown good performance in removing acoustic echo signals in the noisy environment with proper operation of barge-in functionality.

• Journal of Korea Multimedia Society
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• v.16 no.10
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• pp.1196-1203
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• 2013

In general, the cost of transceiver for wireless network configuration is more expensive than that for wired network. However, in case of environmental management system in a tunnel, the cost can be minimized by adopting low rate tranceiver because the amount of the exchanged data for tunnel monitoring is very small. When the obtained data from sensor node is sent directly to the corresponding command node, there is no need to consider routing problem of the data transfer. However in this case, sensor nodes are required to be implemented with high power transmitter and experience high energy consumption. To tackle this problem, relay nodes can be used to transfer the data of tunnel monitoring, and suitable routing protocols for selecting optimum path are needed. Therefore, in this paper, we propose a routing algorithm and a self-configuration protocol for environment management system in tunnel.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.518-523
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• 2008

Using network communication, KTX OBCS is KTX's core device which inspects operation status of various electric equipments and supports driving command, train control, train's maintenance, train crew's driving. Since this device is manufactured as specialized system, being dependent on TGV manufacture specification and France's high speed train operation method, actual technic transfer is difficult. Therefore, there are many difficulties, since most of interface signals are connected with OBCS when function improvement, maintenance, various electric equipments(propulsion control device, auxiliary power supply device, door control device etc.) are replaced with localized ones, which are required in operational view after introduction of KTX. Ergo, this study would like to contribute to function improvement and maintenance's efficiency, furthermore to realize technical independence, escaping from dependency of developed foreign technology in high speed train and electric equipments, through KTX OBCS' function analysis and mutual interface information analysis with peripheral device(driver console, PID system, fault display device, various electric equipments).

• Journal of the Korean Vacuum Society
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• v.17 no.1
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• pp.58-66
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• 2008

The KSTAR Current Lead System(CLS) with network based real-time distributed control system is implemented using an EPICS as a middle-ware software. The current lead system transfers current from magnet power supplies to superconducting magnet system and simultaneously supply the coolant to maintain superconducting state. To control the CLS at main control room an EPICS IOC server is installed in local control area. Using this server, it is able to be controlled and monitored the system in main control room through operator interface(OPI) which uses "caget" to read status and "caput" to write command with a unique name called PV. The EPICS IOC is developed using "ether-ip" driver to communicate with PLC. Also we achieved satisfactory results in operation and stability aspects from a long period commissioning test.

• Strategy21
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• s.46
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• pp.89-122
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• 2020

The longing for submarine manufacture and the fear of her power had exited for a long time, but submarine that could submerge and attack was built from 20th century by science technology development. The question, 'Submarine can exercise her power in naval warfare?' had exited before World War I, but the effective value of submarine was shown in the procedure of a chain of naval warfare during World War I and World War II. Germany and the United States made the best use of submarines at that time. The submarines of these nations mounted fierce attack on the enemy's battleships and merchant ships and blocked the sea lanes for war material. These fierce attack on ships became impossible After World War II, and the major powers reduced and coordinated the defence budget, so they considered the role of submarine. However, submarine is still powerful weapon system because she can secretly navigate under the water, and one of the most important force in the navy. The aim of this thesis is analyzing submarine roles in each naval warfare and integrating maritime strategy and weapon system technology into her roles. First, the research about represent submarine roles like anti-surfaceship warfare, anti-submarine warfare, intelligence gathering, land attack, supporting special operation and mine landing warfare will be presented, then the major naval warfare where submarine participated(during ex-World War I, World War I, World War II, The Cold War Era and post Cold War) and the analyzing of submarine roles by time will be presented. Submarine was developed for anti-surfaceship warfare during ex-World War I but could not make remarkable military gain in naval warfare because her performance and weapon was inadequate. However, the effective value of submarine in the procedure of a chain of naval warfare was shown during World War I and World War II. The major powers put battleships into naval warfare undiscriminatingly to command the sea power and submarines did massive damage to enemy navy power, so put a restraint the maritime power of enemy, and blocked the sea lanes for war material. After World War II, the battlefield situation changed rapidly and the concept of preemption became difficult to apply in naval warfare. Therefore, the submarine was unable to concentrate on anti-surfaceship mission. Especially during the Cold War era, nuclear submarine came to appear and her weapon system developed rapidly. These development gave submarines special missions: anti-submarine warfare and intelligence gathering. At that time, United States and Soviet submarines tracked other nation's submarines loaded with nuclear weapons and departing from naval their base. The submarines also collected information on the volume of ships and a coastal missile launching site in company with this mission. After Cold War, the major powers despatched forces to major troubled regions to maintain world peace, their submarines approached the shores of these regions and attacked key enemy installations with cruise missiles. At that time, the United States eased the concept of preemption and made the concept of Bush doctrine because of possible 911 terrorism. The missiles fired from submarines and surface battleships accurately attacked key enemy installations. Many nations be strategically successful depending on what kind of mission a submarine is assigned. The patterns of future naval warfare that my country will provide against will be military power projection and coalition/joint operations. These suggest much more about what future missions we should assign to submarines.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.5
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• pp.635-643
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• 2018

This paper propose a method to identify the motor parameters and improve input voltage error which affect the low speed position error of the back-emf(back electromotive force) based sensorless algorithm and to secure the operation reliability and stability even in the case where the load fluctuation is severe and the start and low speed operation frequently occurs. In the model-based observer used in this paper, stator resistance, inductance, and input voltage are particularly influential factors on low speed performance. Stator resistance can cause resistance value fluctuation which may occur in mass production process, and fluctuation of resistance value due to heat generated during operation. The inductance is influenced by the fluctuation due to the manufacturing dispersion and at a low speed where the change of the current is severe. In order to find stator resistance and inductance which have different initial values and fluctuate during operation and have a large influence on sensorless performance at low speed, they are commonly measured through 2-point calculation method by 2-step align current injection. The effect of voltage error is minimized by offsetting the voltage error. In addition, when the command voltage is used, it is difficult to estimate the back-emf due to the relatively large distortion voltage due to the dead time and the voltage drop of the power device. In this paper, we propose a simple circuit and method to detect the voltage by measuring the PWM(Pulse Width Modulation) pulse width and compensate the voltage drop of the power device with the table, thereby minimizing the position error due to the exact estimation of the back-emf at low speed. The suitability of the proposed algorithm is verified through experiment.

• Journal of Aerospace System Engineering
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• v.16 no.3
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• pp.105-114
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• 2022

The purpose of this study was to present a conceptual design of the 6U micro-satellite system for optical image of 3 m GSD. An optical camera system with a payload of 3 m GSD image was designed and optimized. The optical system has a diameter of Ø78 mm, length 250 mm, and 1400 mm focal length. The requirement and constraints were configured for the 6U micro-satellite bus system with the payload. Satisfying the requirement and constraints, the subsystems of the 6U bus were designed such as attitude and orbit control, propulsion, command and data handling, electrical power, communication, structures and mechanisms, and thermal control subsystem. The mass budget, power budget, and communication link budget were also confirmed for the 6U micro-satellite comprising the optical payload and the subsystems of bus. To take optical images, a mission operation concept is proposed for the 6U micro-satellite in a low-Earth orbit. A constellation comprising many 6U micro-satellites studied in this paper, can provide with various data for reconnaissance and disaster tracking.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.6
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• pp.553-558
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• 2011

This paper describes the development and test result of S-band Transmitter flight model(FM) of STSAT-3 by satellite research center(SaTReC), KAIST. The communication sub-system of STSAT-3 is consist of two different frequency band channels, S-band for Telemetry & Command and X-band for mission data. S-band Transmitter(STX) functionally made of modulator, frequency synthesizer, power amp and DC/DC converter. The transmission data is modulated by FSK(Frequency Shift Keying) and the interface between spacecraft sub-module and STX is RS-422 standard method. The FM STX is based on modular design. The RF output power of STX is 1.5W(31.7dBm) and BER of STX is under $1{\times}10^{-5}$ which meets the specification respectively. The FM STX is delivered Spacecraft Assembly, Integration and Test(AIT) level through the completion of functional Test and environmental(vibration, thermal vacuum) Test successfully.