• Journal of the Korean Society for Precision Engineering
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• v.18 no.5
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• pp.42-49
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• 2001

In This paper, we present a collaborative method for material delivery using a distributed vehicle agents system. Generally used AGV(Autonomous Guided Vehicle) systems in FA(Factory Automation) require extraordinary facilities like guidepaths and landmarks and have numerous limitations for application in different environments. Moreover in the case of controlling multi vehicles, the necessity for developing corporation abilities like loading and unloading materials between vehicles including different types is increasing nowadays for automation of material flow. Thus to compensate and improve the functions of AGV, it is important to endow vehicles with the intelligence to recognize environments and goods and to determine the goal point to approach. In this study we propose an interaction method between hetero-type vehicles and adaptive fuzzy logic controllers for sensor-based path planning methods and material identifying methods which recognizes color. For the purpose of carrying materials to the goal, simple color sensor is used instead of intricate vision system to search for material and recognize its color in order to determine the goal point to transfer it to. The technique for the proposed method will be demonstrated by experiment.

• The Journal of the Acoustical Society of Korea
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• v.23 no.7
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• pp.548-553
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• 2004

In this paper we propose modified LBG algorithm to minimize quantization errors. When we apply conventional LBG algorithm for speaker verification system, problems that result from small amount of training data can be generated. That is, quantization error comes from fixed-sized codebook without any consideration for speaker characteristics and splitting vector in the wrong direction worsen performance of speaker verification system. So, we propose modified clustering method that has variable sized codebook according to speaker characteristics and makes right splitting direction by finding the farthest member away from mean and then find another member from the member. Simulation results show effectiveness of the proposed algorithm.

• Membrane and Water Treatment
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• v.10 no.4
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• pp.265-275
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• 2019

This study aimed to develop a compact partial nitritation step by forming granules with high Ammonia-Oxidizing Bacteria (AOB) fraction using the Air-lift Granulation Reactor (AGR) and to evaluate the feasibility of treating reject water with high ammonium content by combination with the Anammox process. The partial nitritation using AGR was achieved at high nitrogen loading rate ($2.25{\pm}0.05kg\;N\;m-3\;d^{-1}$). The important factors for successful partial nitritation at high nitrogen loading rate were relatively high pH (7.5~8), resulting in high free ammonia concentration ($1{\sim}10mg\;FA\;L^{-1}$) and highly enriched AOB granules accounting for 25% of the total bacteria population in the reactor. After the establishment of stable partial nitritation, an effluent $NO_2{^-}-N/NH_4{^+}-N$ ratio of $1.2{\pm}0.05$ was achieved, which was then fed into the Anammox reactor. A high nitrogen removal rate of $2.0k\; N\;m^{-3}\;d^{-1}$ was successfully achieved in the Anammox reactor. By controlling the nitrogen loading rate at the partial nitritation using AGR, the influent concentration ratio ($NO_2{^-}-N/NH_4{^+}-N=1.2{\pm}0.05$) required for the Anammox was controlled, thereby minimizing the inhibition effect of residual nitrite.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.1
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• pp.89-93
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• 2009

In this paper, we investigated effect of sensing time on the performance of enhanced spectrum sensing method, which is the energy detector with multiples of verification using time delay, under Suzuki channel. We assumed that SNR is 1dB, $P_{FA}=0.1$ and various mobile speed such as 3, 60, 110 km/h. The performance is investigated by simulation and compared to that of conventional energy detector.

• Proceedings of the IEEK Conference
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• 2000.06a
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• pp.37-40
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• 2000

As the number of CDMA subscribers increases, CDMA systems utilize more than one CDMA carrier In order to accommodate Increasing capacity requirement. In this paper, we present a new analytical method for evaluating the Erlang capacity of CDMA systems with multiple CDMA carriers. in the case of the algorithm proposed in 〔5〕, the calculation complexity for evaluating the call blocking probability Is increased proportionally to the sixth power of the number of used CDMA carriers when the CDMA system supports voice and data services. Consequently, It is Impractical to calculate Erlang capacity with the algorithm of 〔5〕especially when the number of used CDMA carriers is larger than 3. To resolve this problem, we propose a new analytical method for evaluating the Erlang capacity. The calculation complexity of the proposed method for evaluating call blocking probability is increased just proportionally to the second power of the number of used CDMA carriers when the CDMA systems support voice and data services.

• Proceedings of the KSME Conference
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• 2001.06d
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• pp.751-758
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• 2001

Exergy concept is applied to the analysis of part-load performance of gas turbine engine. Exergy is a useful tool to find the source of irreversibility in thermal system. In this study, details of the performance characteristics of a heavy-duty gas turbine, l50MW-class GE 7FA model, are described by theoretical investigations with exergy analysis. Result shows that exergy destruction rate of gas turbine increases with decreased load, which means increase of irreversibility. Also, it is found that variations of IGV angle and amount of cooling air for turbine blades are closely related to the inefficiencies of compressor and turbine, respectively.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.05a
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• pp.533-538
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• 2001

This study was peformed to control the thermal crack of the mat footing slab in the multi-purposed buildings. In this study, we executed the mixing design of concrete to satisfy the workability and the quality according to the site conditions. And, we evaluated quantitatively about the possibility of thermal crack by using hydration heat analysis system. Finally, we proposed the optimal mixing conditions, curing methods and curing period which all factors are considered. As a results, the optimal mixing conditions were : W/B 41%, unit binder 375kg/$cm^{2}$, FA replacement ratio 20%. Lowest thermal stress was 22.0kgf/$cm^{2}$ and at that time thermal crack index was over 1.5, when the coefficient of thermal conductivity was lowest among the curing conditions. And, the total curing time was estimated at 6.7 days according to curing steps.

• Journal of the Korean Ceramic Society
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• v.25 no.4
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• pp.309-314
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• 1988

In this study, the effect of the size of sintered body on resonant and filter characteristics in Pb(Sn1/2Sb1/2)O3-PbTiO3 piezo-electric system were investigated. The attenuation characteristics of ring-dot type and ladder type filter were also investigated. As the size of sintered body was decreased, the resonant characteristic(Fr, Fa) and the center frequency(Fo) were increased. As the poling field was increased, the Kp and bandwidth were increased. The big difference between rign-dot type and ladder type was the sharpness of bandwidth, selectivity and the movement of center frequency.

• International Journal of Quality Innovation
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• v.5 no.2
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• pp.106-121
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• 2004

This paper investigates customer knowledge management activities of Taiwan's plastic industries. The results demonstrate that the bulk of customer knowledge comes from data related to customer purchase orders and complaints. Furthermore, marketing, production, and research and development are the main departments that developed and reuse customer knowledge. The benefits derived from knowledge management for enterprises do not vary with the position of the vendor on the business scope. In addition, the benefits derived by customers from knowledge management are directly related to the benefits gained by the five major business functions, while the benefits derived from the customer knowledge management are also directly related to customer satisfaction. Summarizing the above results, an Acquisition-Development-Reuse (ADR) model is proposed and can provide the enterprises with a systematic reference model when the business attempts to construct a customer knowledge management system.

• 한국정보통신설비학회:학술대회논문집
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• 2007.08a
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• pp.269-272
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• 2007

In order to expand cell coverage, increase system capacity, and offer various multimedia service with high throughput in indoor environment, WiBro Access Point(AP) is developed. Home AP is IFA/Omni type and has stack-up structure of channel card and RF board. SOHO AP is designed to support up to 2FA and has remote RF(RRF) structure using UTP method. Inter-operational test with mobile terminal were completed for 3 terminals using web browsing service simultaneously. The performance test results of WiBro AP are as follows: RCE(EVM) value is -34.431 dB for 64-QAM and throughput is up to 6.79 Mbps(DL) and 1.1 Mbps(UL) with 2.5m Line-of-Sight(LOS) condition.