• Journal of the Korea Institute of Military Science and Technology
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• v.24 no.4
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• pp.457-466
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• 2021

This paper describes the design of model-based fault diagnosis software to apply to the propulsion system in tracked amphibious assault vehicle which consists of an engine, a transmission, a cooling system, and two waterjets. This software includes specific functions to detect the failures regarding sensor malfunctions, mechanical malfunctions, control errors, and communication errors. This software generates the proper malfunction codes which are classified as the warning and caution. In order to validate the fault diagnosis software, the manual and automatic test are performed using the test program with 32 test cases. Test results show that the designed fault diagnosis software is reliable and effective for applying to the propulsion system.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.1
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• pp.1-9
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• 2015

To satisfy stricter $NO_X$ emission regulations for light- and heavy-duty diesel vehicles, a control algorithm needs to be developed based on a selective catalytic reaction (SCR) dynamics model for chemical reactions. This paper presents the development and validation of a SCR dynamics model through test rig experiments and MATLAB simulations. A nonlinear state space model is proposed based on the mass conservation law of chemical reactions in the SCR dynamics model. Experiments were performed on a test rig to evaluate the effects of the $NO_X$ and $NH_3$ concentrations, gas temperature, and space velocity on the $NO_X$ conversion efficiency for the urea-SCR system. The parameter values of the proposed SCR model were identified using the experimental datasets. Finally, a control-oriented model for an SCR system was developed and validated from the experimental data in a MATLAB simulation. The results of this study should contribute toward developing a closed-loop control strategy for $NO_X$ and $NH_3$ slip reduction in the urea-SCR system for an actual engine test bench.

• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
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• v.8 no.7
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• pp.475-484
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• 2018

The propulsion control device of an electric railway vehicle is a key main component corresponding to an engine of an automobile, and a device for controlling this is a device called a GDU (Gate Drive Unit). Also, when the frequency of failure of the propulsion control system was analyzed, the nonconformity ratio of GDU was the highest. GDU was not able to access core technologies due to the introduction of foreign products, and there were general problems with overall maintenance activities due to discontinuation of GDU of the manufacturer. The GDU has reached the end of its life with 23 to 14 years of long-term use.In order to solve these problems, this study was designed to identify the proper life span by analyzing compatible GDU's acquisition and failure, and to improve the existing system of maintenance focusing on health inspection. Maintenance of the components with a short life span compared to the entire service life is essential. Most foreign parts introduced at the beginning of the construction are not replaced due to technical problems or long-term operation. However, due to the characteristics of railway vehicles with a long life span of more than 25 years, it is necessary to maintain them for a long period of time. The study should be more concrete and empirical. The replacement type GDU of capacitors was able to easily measure the life of the capacitance by removing the capacitor modules, measure the life span of each unit test, and accurately perform preventive maintenance of the capacitor.

• Journal of the Korean Society of Propulsion Engineers
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• v.17 no.1
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• pp.1-8
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• 2013

A liquid-monopropellant hydrazine thruster has several outstanding advantages such as relatively-simple structure, long/stable propellant storability, clean exhaust products, and so on. Therefore hydrazine thruster has such a wide application as orbit and attitude control system (ACS) for space vehicles. A hydrazine thruster with the medium-level thrust to be used in the ACS of space launch vehicles (SLV) has been developed, and its ground firing test result is presented in terms of thrust, impulse bit, temperature, and chamber pressure. It is verified through the performance test that the response and repeatability of thrust are very excellent, and the thrust efficiencies compared to its ideal requirement are larger than 93%.

• The Transactions of the Korean Institute of Power Electronics
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• v.8 no.6
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• pp.534-542
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• 2003

Small electric motors in an automobile perform various tasks such as engine cooling, pumping, HVAC etc. At present, most of them are DC motors supplied by 12V or 24V batteries. However, DC motors suffer from low efficiency, life cycles and reliability. Therefore, there is a growing interest in substituting DC motors for advanced at motors including switched reluctance motors(SRM). Although there are several other forms SRM convertors, they are either unsatisfactory to the control performance or unsuitable for the 12V battery source. Especially, a conventional asymmetric converter of SRM provides the best flexible and effective control to the current waveform of SRM, but it has the most switches and produces conducting voltage drops across two power switches during SRM operation. For automotive applications with a 12V battery source, this circuit is inadequate. For considering the requirement for effective operation and simple structure of converter in the limited internal circumstance of automobiles, the author inclines toward selecting Modified C-dump converter and Energy efficient c-dump converter.

• Smart Media Journal
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• v.12 no.9
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• pp.60-71
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• 2023

A microservice architecture that accommodates the heterogeneity of various development environments and enables flexible maintenance can secure business agility to manage services in line with rapidly changing requirements. Due to the nature of MSA, where communication between microservices within a service is frequent, the boundary security that has been used in the past is not sufficient in terms of security, and a Zerotrust system is required. In addition, as the size of microservices increases, definition of access control policies according to the API format of each service is required, and difficulties in policy management increase, such as unnecessary governance overhead in the process of redistributing services. In this paper, we propose a microservice architecture that centrally manages policies by separating access control decision and enforcement with a general-purpose policy engine called OPA (Open Policy Agent) for collective and flexible policy management in Zerotrust security-applied environments.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.40 no.2
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• pp.138-143
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• 2004

This experimental paper deals with the performance of tanks that are turned the active A.R.T(Anti-Rolling Tank) when the fluid transfers from wing tank to the opposite tank by the power developed by the automatic control system (INTERING Stabilizer), which was installed in the fishery training ship T/S. A - RA (G/T:990 tons) of Cheju National University. In this paper, the author has tested the performance of INTERING Stabilizer for the signals obtained by the inclinometer in irregular waves and compared with the results obtained in passive mode operation at stop and at various ship speeds. The performances of the system were confirmed the results as follows through the tests: 1. The average amplitude and significant roll (${\pi}$1/3) of the passive and active mode operations in the condition of stoped engine and underway were obtained 8.30$^{\circ}$, 4.37$^{\circ}$, 8.30$^{\circ}$, 4.37$^{\circ}$, and 5.01$^{\circ}$, 4.36$^{\circ}$, 5.50$^{\circ}$, 5.10$^{\circ}$, respectively. 2. The rates of performance of active mode operations were carried out during a sea trial in the condition of stop engine and underway resulted in 47.5%, 12.7%, respectively, therefore the active mode operation estimated to be improved more than passive mode operation. 3. Active - A.R.T by INTERING Stabilizer didn't affect the amplitude of pitching.

• Journal of Aerospace System Engineering
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• v.16 no.1
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• pp.97-103
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• 2022

An aircraft component can only be mounted on an aircraft if it has been certified to have a structural robustness under flight load conditions. Among the major components of the aircraft, a pylon is a structure that connects external equipment such as an engine, and external attachments with the main wing of an aircraft and transmits the loads acting on it to the main structure of the aircraft. In civil aircraft, when there is an incident of fire in the engine area, the pylon prevents the fire from spreading to the wings. This study presents the results of structural static tests performed to verify the structural robustness of a fuel pylon used to mount external fuel tank in an aircraft. In the main text, we present the test set-up diagram consisting of test fixture, hydraulic pressure unit, load control system, and data acquisition equipment used in the structure static test of the fuel pylon. In addition, we introduce the software that controls the load actuator, and provide a test profile for each test load condition. As a result of the structural static test, it was found that the load actuator was properly controlled within the allowable error range in each test, and the reliability of the numerical analysis was verified by comparing the numerical analysis results and the strain obtained from the structural test at the main positions of the test specimen. In conclusion, it was proved that the fuel pylon covered in this study has sufficient structural strength for the required load conditions through structural static tests.

• The KIPS Transactions:PartB
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• v.11B no.5
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• pp.603-610
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• 2004

The distributed Information Retrieval System centrally controlled by mediator or meta search engine result in congestion of heavy traffic and int he problem of increment of cost for the reason of the design of complicated algorithm for central control and installation of hardware. So to figure out this problem, the way is needed that has independent retrieval functionality and can cooperate each other without dependency. In this paper, we overview a few works involved in distributed information retrieval system, then, implement algorithm and design the frame-work of distributed information retrieval system using sequential transferring method(STM) including multiple information retrieval system separated from central control. For this first of all, we present a web partition policy which devide and manage web logically and we present the sequential query processing way by means of illustration through changing numbered information retrieval system. Then, we also present 3-layered structure of framework and function and module of each layer suitable for information retrieval system. Last of ail, for effective implementation of STM algorithm we analysis module structure and present description of pseudocode of this, and show that the proposed STM algorithm works smoothly by demonstration of sequential query transfer process between servers.

• Journal of Welding and Joining
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• v.33 no.3
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• pp.25-31
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• 2015

Due to environmental regulations (RoHS, WEEE and ELV) of the European Union, electronics and automotive electronics have to eliminate toxic substance from electronic devices and system. Specifically, reliability issue of lead-free solder joint have an increasing demand for the car electronics caused by ELV banning. The authors prepared engine control unit and cabin electronics soldered with Sn-3.0Ag-0.5Cu (SAC305). To compare with the degradation characteristics of solder joint strength, thermal cycling test (TC), power-thermal cycling test (PTC) and series tests were conducted. Series tests were conducted for TC and PTC combined stress test using the same sample in sequence and continuously. TC test was performed at $-40{\sim}125^{\circ}C$ and soak time 10 min for 1000 cycles. PTC test was applied by pulse power and full function conditions during 100 cycles. Combined stress test was tested in accordance with automotive company standard. Solder joint degradation was observed by optical microscopy and environment scanning electron microscopy (ESEM). In addition, to compare with deterioration of bond strength of quad flat package (QFP) and chip components, we have measured lead pull and shear strength. Based on the series test results, consequently, we have validated of series test method for lifetime and reliability of Pb-free solder joint in automotive electronics.