• Proceedings of the KOR-KST Conference
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• 2003.02a
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• pp.119-126
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• 2003

The aim of this research was to compare driver's workload among AHS (Automate Highway Systems) road sections in a virtual AHS environment that is based on a re Korean expressway in order to predict and compare the workloads imposed by the change (driver-vehicle interface and vehicle control authority. Road sections included the M (Manual Lane), TL1 (Transition Lane to enter the automated lane), AL (Automated Lane TL2 (Transition Lane to enter the manual lane after the end of automated driving), an post-AHS manual lane.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.40 no.5
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• pp.397-409
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• 2003

This paper describes an implementation of radix-4 trellis parallel architecture and backward state transition control trace back Viterbi decoder, and presents the application results to high speed wireless LAN. The radix-4 parallelized architecture Vietrbi decoder can not only improve the throughput with simple structure, but also have small processing delay time and overhead circuit compared to M-step trellis architecture one. Based on these features, this paper addresses a novel Viterbi decoder which is composed of branch metric computation, architecture of ACS and trace back decoding by sequential control of backward state transition for the implementation of radix-4 trellis parallelized structure. With the proposed architecture, the decoding of variable code rate due to puncturing the base code can easily be implemented by the unified Viterbi decoder. Moreover, any additional circuit and/or peripheral control logic are not required in the proposed decoder architecture. The trace back decoding scheme with backward state transition control can carry out the sequential decoding according to ACS cycle clock without additional circuit for survivor memory control. In order to evaluate the usefulness, the proposed method is applied to channel CODEC of the IEEE 802.11a high speed wireless LAN, and HDL coding simulation results are presented.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.50-55
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• 1998

This paper introduces the advantages of zero voltage transition(ZVT) boost converter for power factor correction and analyzes the control method of ZVT with IC UC3855. Practical design issues which include the components selection and design procedure are discussed. The experimental results are given.

• Journal of the Korean Society of Industry Convergence
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• v.5 no.2
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• pp.147-152
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• 2002

Because of the difference of the relative reactivity between two hydroxyl groups of the hydroquinone due to the steric hindrance of the substituent, many combinations of the substituent direction in the polyesters derived from asymmetrical diphenols such as monosubstituted hydroquinones was expected. It was studied how the mode of the direction affected the properties of the resulting polyesters in terms of the transition temperatures of the thermotropic polyesters prepared from terephthalic acid, 2,4-dichloroterephthalic acid, and phenylhydroquinone by the reaction using p-Toluenesulfonylchloride in pyridine. The direction was tried to control the relative reactivity by changing the reaction temperature and addition time of the hydroquinone, and by modifying it through an association of the hydroquinones with DMF.

• Journal of the Korean Ceramic Society
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• v.56 no.2
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• pp.184-190
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• 2019

To improve resistance in thermal shock of zirconia setter which is frequently and repeatedly exposed to high temperature, high degree of porosity and control of thermal expansion are needed for which the fused CSZ (CaO stabilized zirconia) is used to produce the zirconia setter. In the present study, the effects of sintering temperature, cool down condition, addition of CaO stabilizer, and addition of other additives on phase transition and thermal expansion behavior of the fabrication process of zirconia setter, were examined. The zirconia setter, fabricated with fused CSZ at 1550℃, exhibited 20.4 MPa of flexural strength, 6.8% of absorbance, and 27.9% of apparent porosity. The rapid change in thermal expansion of zirconia setter is observed at temperature around 800℃, and it was reduced by low firing temperature, slowed cooled down, and addition of CaO.

• Journal of Information Processing Systems
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• v.15 no.3
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• pp.570-592
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• 2019

The Event-B design pattern is an excellent way to quickly develop a formal model of the system. Researchers have proposed a number of Event-B design patterns, but they all lack formal behavior semantics. This makes the analysis, verification, and simulation of the behavior of the Event-B model very difficult, especially for the control-intensive systems. In this paper, we propose a novel method to transform the Event-B synchronous control flow design pattern into the labeled transition system (LTS) behavior model. Then we map the design pattern instantiation process of Event-B to the instantiation process of LTS model and get the LTS behavior semantic model of Event-B model of a multi-level complex control system. Finally, we verify the linear temporal logic behavior properties of the LTS model. The experimental results show that the analysis and simulation of system behavior become easier and the verification of the behavior properties of the system become convenient after the Event-B model is converted to the LTS model.

• Proceedings of the IEEK Conference
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• summer
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• pp.259-262
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• 2004

In most of the character recognition systems, the method of template matching or statistical method using hidden Markov model is used to extract and recognize feature shapes. In this paper, we used modified chain-code which has 8-directions but 4-codes, and made the chain-code of hand-written character, after that, converted it into transition chain-code by applying to HMM(Hidden Markov Model). The transition chain code by HMM is analyzed as signal flow graph by Mason's theory which is generally used to calculate forward gain at automatic control system. If the specific forward gain and feedback gain is properly set, the forward gain of transition chain-code using Mason's theory can be distinguished depending on each object for recognition. This data of the gain is reorganized as tree structure, hence making it possible to distinguish different hand-written characters. With this method, $91\%$ recognition rate was acquired.

• Journal of Korea Foundry Society
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• v.25 no.6
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• pp.254-258
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• 2005

Semisolid process is possible in any material system possessing a freezing range where the microstructure should consist of the nondendritic globular solid phase separated and enclosed by the liquid phase, referred to as semisolid slurry. There are two primary semisolid processing routes, thixocasting and rheocasting. Especially, rheocasting process has become a new focus in the field of semisolid process because of its many advantages such as no special billet required and possibility of in-house scrap recycling, compared with the thixocasting process. In-Ladle direct thermal control (DTC) rheocasting has been developed, based on the fact that there is slurry and mush transition in every molten metal and the transition, which normally occurs in the range of liquid traction of 0.1 to 0.6, could be controlled by controlling solid shape and relative solid-liquid interfacial energy. In this study, A356 Al alloy was investigated to verify In-Ladle DTC rheocasting for obtaining semisolid slurry. Modeling of heat transfer was carried out to investigate the effect of pouring temperature and ladle material, geometry and temperature and the simulation results were compared with the actual experiments.

• Journal of Power Electronics
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• v.15 no.4
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• pp.1026-1034
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• 2015

In this paper, a unified control strategy using the current space vector modulation (CSVM) technique is proposed and applied to a bidirectional three-phase DC/AC converter. The operation of the converter changes with the direction of the power flow. In the charging mode, it works as a buck type rectifier; and during the discharging mode, it operates as a boost type inverter, which makes it suitable as an interface between high voltage AC grids and low voltage energy storage devices. This topology has the following advantages: high conversion efficiency, high power factor at the grid side, tight control of the charging current and fast transition between the charging and discharging modes. The operating principle of the mode analysis, the gate signal generation, the general control strategy and the transition from a constant current (CC) to a constant voltage (CV) in the charging mode are discussed. The proposed control strategy has been validated by simulations and experimental results obtained with a 1kW laboratory prototype using supercapacitors as an energy storage device.

• Journal of Korean Society on Water Environment
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• v.30 no.4
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• pp.429-440
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• 2014

This study was conducted to investigate the main cause of water quality deterioration during the spring season in the transition zone between the South Han River and the river-reservoir Paldang. A water quality model modified from QUAL2E (U.S.EPA) was used, and the model showed that eutrophication and algal production in the low flow season affected about 60% of the organic pollution at the downstream of the South Han River. This result means that phosphorus control is prior to external organic material management to ameliorate the deterioration of water quality in the water body.