• Proceedings of the KSR Conference
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• 1998.05a
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• pp.273-279
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• 1998

This study represents the technique about the noise reduction of HVAC equipment for high speed train(HST) operating at 200km/h. HST is different from the low speed train in the various points as well as the speed. Especially, the noise of cabin is closely related to the comfort of passenger and the noise from HVAC is one of main noise source in the cabin. In this study, the noise from HVAC was reduced by 5 dB(A) using the concept of multiple resonator and guide vein. Therefore, the noise of cabin decreased from 60 dB(A) to 55 dB(A) at the center of the cabin.

• 한국전산유체공학회:학술대회논문집
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• 2009.04a
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• pp.335-340
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• 2009

Operating medium or large scale industrial boilers in partial load condition, the burner should undergo the off-design points resulting in poor exhaust gas characteristics. To obtain the stable turn down performance, two or more burners can be used for the industrial boiler. In case multiple burners are adopted, the heat transfer can be enhanced by arranging the burners properly. In the present study, numerical simulations have been conducted for the combustion chamber of a 2 t/h class industrial boiler in order to clarify the heat transfer characteristics at the combustion chamber.

• Journal of the Korean Operations Research and Management Science Society
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• v.19 no.3
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• pp.63-79
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• 1994

Many vehicle fleet planning systems have been suggested to minimize the routing distances of vehicles or reduce the transportation cost. But the more considerations the method takes, the higher complexites are involved in a large number of practical situations. The purpose of this paper is to vehicle fleet planning system. This paper is considered multi-objective optimization. The vehicle fleet planning system developed by this study involves such complicated and restricted conditions as one depot, multiple nodes (demand points), multiple vehicle types, multipel order items, and other many restrictions for operating vehicles. The proposed algorithm is compared with the nearest neighbor heuristic (NNH) and the savings heuristic (SAH) algorithm in terms of total logistics cost and driving time. This method constructs a route with a minimum number of vehicles for a given demand. This method can be used to any companys which vehicle fleet planning system under circumstances considered in this paper.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.2
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• pp.97-104
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• 2000

Pneumatic cylinder is widely used for mechanical handling systems. Often, the impact occurs at the both ends points of pneumatic cylinder and generates destructive shock with in the structural operating members of the machine or equipment. To reduce the damage of system, therefore, shock absorbing devices are required. Cushioning of pneumatic cylinders at one or both ends of piston stroke is used to reduce the shock and vibration. The cylinder body have to withstand under high velocity and load. In this research, the pneumatic cushioning cylinder moving tests have been conducted for different load mass and supply pressure. The velocity of pneumatic cylinder actuation system with multiple orifice cushion sleeve which is set vertically controled with meter-in/out system. This study examines the dynamic characteristics of pneumatic cylinder with cushion devices. It turns out that the cushion pressure is mainly a function of the external load rather than the supply pressure. The cushion region characteristics was also revealed in the meter-in system.

• Journal of computational fluids engineering
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• v.14 no.2
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• pp.77-83
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• 2009

Operating medium or large scale industrial boilers in partial load condition, the burner should undergo the off-design points resulting in poor exhaust gas characteristics. To obtain the stable turn down performance, two or more burners can be used for the industrial boiler. In case multiple burners are adopted, the heat transfer can be enhanced by arranging the burners properly. In the present study, numerical simulations have been conducted for the combustion chamber of a 2 t/h class industrial boiler in order to clarify the heat transfer characteristics at the combustion chamber.

• Transactions of the Korean Society of Automotive Engineers
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• v.21 no.4
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• pp.8-15
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• 2013

Recently many kinds of electric vehicles have been developed as many governments demand the environmental friendly vehicles. In this paper, study of load optimization for the electric vehicle which has multiple axle power system was conducted. For the analysis of the vehicle which has three or four driving axles, a method based on the geometry and assumptions that considering axles as a spring model and normal forces of the axles are proportional to the displacement of the axles was applied with basic vehicle dynamics. With the developed vehicle analysis technique, algorithm to find the optimal motor operating points was developed. Using this algorithm, it was possible to find the optimization of vehicle load distribution for multiple axles according to the driving cycles. Also, control logic for the vehicle can be developed based on the optimization simulation results.

• Journal of Korean Clinical Nursing Research
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• v.17 no.2
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• pp.204-214
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• 2011

Purpose: This study was aimed to provide information on the awareness of patient safety culture and safety care activities among operating room (OR) nurses and to analyze the factors influencing the safety care activities. Methods: For this descriptive research, self-reported questionnaires were administered to 168 OR nurses who were working at the university-affiliated and general hospitals. The collected data were analyzed using descriptive statistics, t-test, ANOVA, $Scheff{\grave{e}}$ test, Pearson's correlation coefficient and Stepwise multiple regression with SPSS/WIN 17.0. Results: The mean score of the awareness on patient safety culture was 3.27 out of 5 points and that of safety care activity was 4.31 out of 5. The statistically significant difference was found between experience of safety education and the awareness on patient safety culture. Also, the scores of safety care activities were significantly different according to OR nurses' position, education levels, and experience of safety education. There was a positive correlation between the awareness of patient safety culture and safety care activity. Their explanatory power on safety care activity was 8.8%, which includes working environment in operating room 3.3% and nursing position 5.5%. Conclusion: Compared to the level of patient safety activities, the OR nurses' awareness on patient safety culture was low. Given the specific characteristics and conditions in each hospital, it needs to increase the OR nurses' awareness on patient safety culture and activities related to patient safety.

• Journal of Power Electronics
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• v.17 no.2
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• pp.442-452
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• 2017

This paper deals with the input-output modeling of a vector controlled PMSM drive system and design of a simple multiple model adaptive control (MMAC) scheme with desired transient responses. We present a discrete-time modeling technique using closed-loop identification that can experimentally identify the equivalent models in the d-q coordinates. A bank of linear models for the equivalent plant of the current loop is first obtained by identifying them at several operating points of the current to account for nonlinearity. Based on these models, we suggest a simple q-axis MMAC combined with a fixed d-axis controller. After the current controller is designed, another equivalent model including the current controller in the speed control loop shall be similarly obtained, and then a fixed speed controller is synthesized. The proposed approach is demonstrated by experiments. The experimental set up consists of a surface mounted PMSM (5 KW, 220V, 8 poles) equipped with a flywheel load of 220kg and a digital controller using DSP (TMS320F28335).

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.2
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• pp.253-270
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• 2013

To achieve accurate localization information, complex algorithms that have high computational complexity are usually implemented. In addition, many of these algorithms have been developed to overcome several limitations, e.g., obstruction interference in multi-path and non-line-of-sight (NLOS) environments. However, localization systems those have complex design experience latency when operating multiple mobile nodes occupying various channels and try to compensate for inaccurate distance values. To operate multiple mobile nodes concurrently, we propose a localization system with both low complexity and high accuracy and that is based on a chirp spread spectrum (CSS) radio. The proposed localization system is composed of accurate ranging values that are analyzed by simple linear regression that utilizes a Big-$O(n^2)$ of only a few data points and an algorithm with a self-calibration feature. The performance of the proposed localization system is verified by means of actual experiments. The results show a mean error of about 1 m and multiple mobile node operation in a $100{\times}35m^2$ environment under NLOS condition.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.6
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• pp.34-42
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• 2014

This paper presents a low-complexity and high-throughput symbol detector for two-spatial-stream multiple-input multiple-output systems based on the modified maximum-likelihood symbol detection algorithm. In the proposed symbol detector, the cost function is calculated incrementally employing a multi-cycle architecture so as to eliminate the complex multiplications for each symbol, and the slicing operations are performed hierarchically according to the range of constellation points by a pipelined architecture. The proposed architecture exhibits low hardware complexity while supporting complicated modulations such as 256 QAM. In addition, various modulations and antenna configurations are supported flexibly by reconfiguring the pipeline for the slicing operation. The proposed symbol detector is implemented with 38.7K logic gates in a $0.11-{\mu}m$ CMOS process and its throughput is 166 Mbps for $2{\times}$3 16-QAM and 80Mbps for $2{\times}3$ 64-QAM where the operating frequency is 478 MHz.