• Journal of the Computational Structural Engineering Institute of Korea
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• v.27 no.5
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• pp.337-343
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• 2014

This paper presents a continuum-based shape design sensitivity analysis(DSA) method for crack propagation problems using a reproducing kernel method(RKM), which facilitates the remeshing problem required for finite element analysis(FEA) and provides the higher order shape functions by increasing the continuity of the kernel functions. A linear elasticity is considered to obtain the required stress field around the crack tip for the evaluation of J-integral. The sensitivity of displacement field and stress intensity factor(SIF) with respect to shape design variables are derived using a material derivative approach. For efficient computation of design sensitivity, an adjoint variable method is employed tather than the direct differentiation method. Through numerical examples, The mesh-free and the DSA methods show excellent agreement with finite difference results. The DSA results are further extended to a shape optimization of crack propagation problems to control the propagation path.

• Journal of IKEEE
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• v.22 no.2
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• pp.495-498
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• 2018

In this paper, we propose an DAP system for dose evaluation of medical and industrial X-ray generator. Based on the DAP measurement technique using the Ion-Chamber, the proposed system can clearly measure the exposure radiation dose generated by the diagnostic X-ray apparatus. The hardware part of the DAP measures the amount of charge in the air that is captured by an X-ray. The high-speed processing algorithm part for cumulative radiation dose measurement through microcurrent measures the amount of charge captured by X-ray at a low implementation cost (power) with no input loss. The wired/wireless transmission/reception protocol part synchronized with the operation of the X-ray generator improves communication speed. The PC-based control program part for interlocking and aging measures the amount of X-ray generated in real time and enables measurement graphs and numerical value monitoring through PC GUI. As a result of evaluating the performance of the proposed system in an accredited testing laboratory, the measured values using DAP increased linearly in each energy band (30, 60, 100, 150 kV). In addition, since the standard deviation of the measured value at the point of 4 division was ${\pm}1.25%$, it was confirmed that the DAP showed uniform measurements regardless of location. It was confirmed that the normal operation was not less than ${\pm}4.2%$ of the international standard.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.1
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• pp.1-12
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• 2004

In this paper, we take advantage of the characteristics of optical burst switching (OBS) to support service-differentiation in optical networks. With the offset time between control packet and burst data, the proposed scheme uses different offset time of each service class. As contrasted with the Previous method, in which the high Priority service use only long offset time, it derives the burst loss rate as a QoS parameter in consideration of conservation law and given service-differential ratios and decides a reasonable offset time for this QoS finally Firstly proposed method classifies services into one of high or low class and is an algorithm deciding the offset time for supporting the required QoS of high class. In order to consider the multi-classes environment, we expand the analysis method of first algorithm and propose the second algorithm. It divides services into one of high or low group according to their burst loss rate and decides the offset time for high group, and lastly cumulates the offset time of each class. The proposed algorithms are evaluated through simulation. The result of simulation is compared with that of analysis to verify the proposed scheme.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.2
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• pp.217-224
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• 2012

In general, transportation sources include both on-road vehicles and off-road equipment. Off-road vehicles have usually used diesel engines, which have the disadvantage of high NOx emission. Common rail direct injection (CRDI) and after-treatment systems have been applied to meet the exhaust gas emission regulations for diesel vehicles. In the present, agricultural machinery has satisfied the Tier 3 emission regulations by using waste gate turbocharger (WGT) and internal exhaust gas recirculation (EGR). In this paper, the combustion and emission characteristics of an EGR system applied to a 56kW off-road vehicle in non-road transient cycle (NRTC) mode have been investigated. The EGR map was made from foundation experiments determining the EGR duty for all engine operating conditions, and then this map was applied to the NRTC mode. Consequently, the NOx emission was reduced by the EGR system, and the Tier 4 interim emission regulations were satisfied by using both the EGR system and an after-treatment system.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.10
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• pp.1115-1130
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• 2012

In nuclear power plants, the reactor pressure vessel (RPV) upper head control rod drive mechanism (CRDM) penetration nozzles are fabricated using J-groove weld geometry. Recently, the incidences of cracking in Alloy 600 CRDM nozzles and their associated welds have increased significantly. The cracking mechanism has been attributed to primary water stress corrosion cracking (PWSCC), and it has been shown to be driven by welding residual stresses and operational stresses in the weld region. The weld-induced residual stress is the main factor contributing to crack growth. Therefore, an exact estimation of the residual stress is important for ensuring reliable operation. This study presents the residual stress computation performed for an RPV CRDM penetration nozzle in Korea. Based on two and three dimensional finite element analyses, the effect of welding variables on the residual stress variation is estimated for sensitivity analysis.

• Journal of Mushroom
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• v.13 no.4
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• pp.288-293
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• 2015

In the structural investigation of cultivation facilities, the proportion of farmers to grown with double or triple structure were investigated 96%. It has been shown to grow with a stable cultivation facilities structure against environmental changes. The results of the analysis of the changes in the cultivation environment of Yeoju area in July-august, temperature and humidity of the external instrument shelter was $20.2{\sim}29.9^{\circ}C$ and 66.2~99.9% respectively. In the greenhouse 2 model capable of temperature environment regulation in the cultivation facility, temperature and humidity were investigated $19.3{\sim}25.7^{\circ}C$ and 81.6~99.9% respectively. Result of the survey of fruiting body characteristics and yields in the greenhous 2, pileus diameter and stipe length were investigated 66.2 and 54.1 mm, yield of mushroom and individual weight were 312 g and 26.6 g. High-temperature environment regulation shows the improvement of the quality and productivity of the mushroom. Power consumption of the air conditioning has been investigated using 56kwh/day, electricity costs were calculated 2195 won/day.

• Journal of IKEEE
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• v.19 no.3
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• pp.311-318
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• 2015

This dissertation proposes method for development technology of voice and SMS(Short Message Service) alarming system based on modbus protocol. The proposed technology is composed of the following 3 stages; hardware development based on microprocessor, development of input and output driver for modem, mp3 decoder, making modbus protocol stack. In the stage of hardware development based on microprocessor, we develop hardware which receives alarm from modbus master and transmit sms message, play mp3. In the stage of development of input / ouput device driver such as modem, mp3 decoder, we develop program which control each devices. In the stage of making modbus protocol stack, voice and sms alarm system is made for receiving alarm via modbus protocol. To evaluate performance of proposed technology, we issued alarm to voice and sms alarming system on purpose. As a result, response speed of detecting alarm was 10.7ms, communication distance was 1.2Km, operating temperature was from $-25^{\circ}C$ to $70^{\circ}C$, we confirmed supporting modbus protocol. And we verified that proposed voice and sms alarming system in the thesis has a performance to be used as an industrial building alarming system.

• Journal of IKEEE
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• v.24 no.2
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• pp.673-676
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• 2020

In this paper, we propose a whole-body management system using ultra-low temperature cyclical cooling method combined with IT technology. The proposed system has the following characteristics. First, it minimizes maintenance costs by circulating nitrogen gas cooled by ultra-low temperature inside the controller. Secondly, based on the information measured by the temperature sensor and oxygen concentration sensor, nitrogen gas is supplied to provide safe ultra-low temperature whole-body management. Thirdly, after entering the user's height, it provides convenient, ultra-low temperature whole-body care that can be controlled using an automatic lift. Fourth, it provides an easy-to-access, easy-to-manage GUI and a manager-only web program for whole-body management system operation. The results tested by the authorized testing agency to assess the performance of the proposed system were measured in the range of ±5%, the world's highest temperature sensor accuracy, and a range of -110℃ to -150℃ greater than the world's highest whole-body management temperature range(-110℃ ~ -140℃). In addition, humidity was measured at less than 40%, the world's highest, and oxygen concentration was more than 18%, the world's highest. Therefore, the effectiveness of the methods proposed in this paper was demonstrated because they produced the same results as the world's highest levels.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.10 no.3
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• pp.1-8
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• 2011

The parking guidance system can increase driver's convenience with detailed parking information service, but it continuously consumes electrical energy with large amount of sensors, displays and control modules. With the increase of the demand for green and sustainable building design, it becomes a meaningful issue for parking guidance system to reduce operating power. This paper presents the preliminary design and estimated results of a parking guidance system which is optimized to reduce the power consumption mainly on detectors and displays. The system design is based on commercial wireless parking detectors, wireless-loop-detector and earth-magnetic-detector. We have performed system architecture design, communication network design, parking information service scenario planning, battery life regulation and at last operating power estimation. With the 7 years of battery replace cycle, the estimated result for power consumption of designed system was 0.33W/slot, which is 13% of the traditional system's estimation result. The estimated annual maintain cost was similar to the traditional ultrasonic sensor based system's. The low power operable designed system can be expected to reduce CO2 emission.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.39 no.5
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• pp.232-242
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• 2002

In a MPLS(Multiprotocol Label Switching) network, it is important to reduce the number of labels and LSP(Lable Switched Path)s for network resource management. MTP(Multipoint-to-Point) LSP can be used to solve this problem. In consideration of traffic engineering, MTP LSP must be chosen to enhance the availability of network and link utilization. Also, a fast mechanism to setup MTP LSPs is required for rerouting capability against link failure. In this paper, we propose a fast MTP LSP traffic engineering of multipath MTP LSP by using a mapping of a MTP LSP upon Diffserv PHBs(Per Hop Behavior) in a Diffserv-capable MPLS network. In the proposed traffic engineering, we determine multiple MTP LSPs in a hierarchical manner according to the characteristics of different services. By using Monte-Carlo method for traffic load balancing process, it provides fast rerouting capability in case of frequent link failure across large network. Out method produces to be nearly optimal within reasonable run-times. It's time complexity is in O( Cn$^2$logn) as conventional multipath routing and it is much faster than Linear Programming approach. Simulation results show that the proposed traffic engineering can be controlled effectively in an administrative manner and enhance the availability of network in comparison with conventional multipath routing.