• Journal of Internet Computing and Services
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• v.12 no.6
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• pp.161-170
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• 2011

Despite some practical confusion over the variations in the diagram which may be drawn differently depending upon the CASE, the statechart of UML has been widely used to show the dynamic behaviour of the systems. Prior research has employed either simple switch-case statement or the state design pattern to generate source code from the statechart, which may result in varying source codes. This paper made an attempt to formally define the statechart and generate source codes from it. Firstly we cleaned up the XMI which was generated from different CASEs. This XMI has been translated to the EHA to identify automata contained in it. Then the elements of the statechart metamodel were mapped to the java programs. We also verified the quality of source codes by measuring functionality and maintainability. The case employed in this study was the air conditioner. The reason was that the case includes various states and transitions of interest. It was found that XMI was well extracted by removing some legacy codes in the CASE and the source codes were then successfully generated with the concurrency and hierarchy of the statechart. Further research is required to validate it practical significance with a larger case.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.05a
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• pp.127-130
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• 2010

The reception quality of broadcasting in car radio system may become poor due to the noise such as week signal strength, multipath, Adjacent Channel and so on. To improve this, some european nations and U.S. serve RDS(Radio Data System) on FM radio. AF(Alternative Frequency) and PI(Programme Identification) code contained information in RDS data are used to switch to the broadcasting having the best reception quality. There are many techniques and studies of maintaining the best reception quality. But many previous techniques are no longer the best way because RF chips are improved every year and noise components can be distinguished in detail. So this research will suggest the best switching technique to maintain the best reception quality.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.9A
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• pp.1276-1284
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• 1999

We have evaluated the BER's and CLP's of Wireless ATM (WATM) cells employing the concatenated FEC code with pilot symbols for fading compensation through the simulation in indoor wireless channel modeled as a Rayleigh and a Rician fading channel, respectively. The results of the performance evaluation are compared with those obtained by employing the convolutional code in the same condition. In Rayleigh fading channel, considering the maximum tolerance BER ( $10^-3$) as a criterion of the voice service, it is blown that the performance improvement of about 4 dB is obtained in terms of $E_b/N_o$ by employing the concatenated FEC code with pilot symbols rather than the convolutional code with pilot symbols.When the values of K parameter which means the ratio of the direct signal to scattered signal power in Rician fading channel are 6 and 10, it is shown that the performance improvement of about 4 dB and 2 dB is obtained, respectively, in terms of $E_b/N_o$ by employing the concatenated FEC code with pilot symbols considering the maximum tolerance BER of the voice service. Also in Rician fading channel of K=6 and K= 10, considering CLP = $10^-3$ as a criterion, it is observed that the performance improvement of about 3.5 dB and1.5 dB is obtained, respectively, in terms of $E_b/N_o$ by employing the concatenated FEC code with pilot symbols.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.8
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• pp.987-993
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• 2018

In the existing distribution automation system, the database is managed by each distribution office. But there is a high possibility to happened a problem during a fault processing because the representation of the connection switches between distribution offices are complicated. In addition, if a distribution office will be going to collapse due to disaster, for example, a big fire or earthquake, its own database may be lost. In order to solve this problem, it is necessary to have a structure of an integrated database management from an integration center to under the distribution office. To do this, the integration center must store and manage it as the database using the own office code.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.12B
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• pp.1728-1735
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• 2011

In this paper, satellite data link waveform is proposed which is based on the waveform of Link-16 but LDPC code is studied instead of CCSK code in order to be optimized to satellite nonlinear channel environment and transmission characteristics. And the DSM (Demux, Selective CH switch, and Mux) transponder structure is suggested which can remove all of the jamming signal out of the transmission signal band and convert uplink hopping frequency to desired ones of downlink. The results of BER and anti-jamming performance analysis shows that the required Eb/No and processing gain in the worst case partial band jammer of the proposed waveform are 2.5dB and 52dB respectively and the anti-jamming capacity improvement of DSM transponder is maximum 2dB.

• Structural Engineering and Mechanics
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• v.62 no.6
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• pp.739-748
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• 2017

Notches such as slots are typical geometric features on mechanical components that promote fatigue crack initiation. Unlike for components with open hole type notches, there are no conventional treatments to enhance fatigue behavior of components with slots. In this work we evaluate the viability of applying laser shock peening (LSP) to extend the fatigue life of 6061-T6 aluminum components with slots. The feasibility of using LSP is evaluated not only on damage free notched specimens, but also on samples with previous fatigue damage. For the LSP treatment a convergent lens was used to deliver 0.85 J and 6 ns laser pulses 1.5 mm in diameter by a Q-switch Nd: YAG laser, operating at 10 Hz with 1064 nm of wavelength. Residual stress distribution was assessed by the hole drilling method. A fatigue analysis of the notched specimens was conducted using the commercial code FE-Safe and different multiaxial fatigue criteria to predict fatigue lives of samples with and without LSP. The residual stress field produced by the LSP process was estimated by a finite element simulation of the process. A good comparison of the predicted and experimental fatigue lives was observed. The beneficial effect of LSP in extending fatigue life of notched components with and without previous damage is demonstrated.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.491-496
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• 2008

A HEV-relay plays a significant role as a mechanical switch which determines the operation of a gasoline engine or an electric motor in a hybrid electric vehicle (HEV). The HEV-relay has critical two problems in the operating process. First, the unstable current can occur in the operating process of the HEV-relay due to the severe bounce between moving and fixed electrode. Second, noises occur due to impact between electrodes in HEV-relay. In this research, spring properties such as stiffness and initial compression force, and electrode shape are designed to reduce the bounce time and noises caused by impact between moving and fixed electrode. The operating process of HEV-relay is simulated using LS-DYNA3D as explicit finite element code. The optimum spring properties are determined using the response surface method (RSM) as the design methodology, and the electrode shape is newly designed through the modifying the stiffness of moving and fixed electrode.

• Transactions of The Korea Fluid Power Systems Society
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• v.8 no.3
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• pp.1-7
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• 2011

As the technologies of electronic device have advanced these days, most of mechanical systems are designed with electronic control unit to take advantage of control parameter adaption to operating conditions and firmware flexibilities as well. On-board diagnosis, which detects the system malfunction and identifies potential source of error with its own diagnostic criteria, and fail-safe that can switch the mode of operation in view of recognized error characteristics enables easy maintenance and troubleshooting as well as system protection. This paper dealt with the development of diagnosis and fail-safe function for proportional flow control valve. All type of errors related to valve control system components are investigated and assigned to a specific hexadecimal codes. Cumulative error detection algorithm is applied in order for the sensitivity and reliability to be appropriate. Embedded simulator which runs simultaneously with system program provides the virtual error simulation environment for expeditious development of error detection algorithm. The diagnosis function was verified both with solenoid valve and embedded simulator test and it will enhance the valve control system monitoring function.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.1A
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• pp.115-124
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• 2007

In this paper, the I/Q mismatch problem between the transmission line and antenna switch is solved by a new CPW matching circuit for a VoWLAN terminal with 54 Mbps communication speed through the IEEE 802.11 b/g CCK/OFDM. I/Q performances with the new matching circuit are analyzed and improved by the output spectrum mask, the characteristics of the EVM(Error Vector Magnitude) due to the nonlinear CCK/OFDM demodulation data, and receiver's sensitivity.

• Proceedings of the KIEE Conference
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• 1999.07g
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• pp.3215-3217
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• 1999

In this paper, a new structure of realizing switching control logic for Data Weighted Average Technique is suggested. It uses memory and adder for summing past binary input and this summed data is used to select one switch in control logic. This control logic acts in parallel regardless of resolution so increasing resolution don't affect on converting speed. In this reason, high speed and high resolution D/A converter based on Data Weighted Average Technique could be made. In this paper, 4 bits current mode thermometer code D/A converter is degined and simulated by using HSPICE. Simulated results show that new structure of D/A converter has more than 250MHz converting speed and less than 0.0003[LSB] INL error. It is very useful in low power circuit because of using 3.3 V supply voltage.