• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.1009-1012
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• 2004

Recently, the concern on sound qualify (SQ) is on the steep increase in the fields of vehicle and home appliance and over the fast few decades a considerable number of studies have been conducted on SQ evaluation. As a result, basic procedure for SQ evaluation has been already suggested. Although most interesting sounds have time-varying features, however, little is known about their SQ evaluation. The purpose of this study is to systematize a method for SQ evaluation of non-stationary sound. For this, various listening tests procedure for non-stationary sound is introduced and it is attempted to find out correlation between various SQ metrics and subjective data obtain from listening test. Booming of car interior noise in acceleration is used as an example and finally, representative value is obtained for the interesting sensation of non-stationary sound.

• Proceedings of the IEEK Conference
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• 2003.11b
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• pp.7-10
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• 2003

In this paper, we present a new echo kernel, which is a modification of polar echo kernel. to improve the detection performance and robustness against attacks. Polar echo kernel may take advantage of large detection margin from the polarity of inserted echo signal, but its poor frequency response in low frequency band degrades sound quality. To solve this problem, we applied bipolar echo pulses to the polar echo kernel. Using the proposed echo kernel the distributions of autocepstrum peaks fur data ‘0’ and ‘1’ are located more distant and improvement of detection performance is achieved. It also makes the low frequency band flat so that the timbre difference in the polar echo kernel can be removed to reproduce the imperceptible sound qualify. Informal listening tests as well as robustness test against attacks were performed to evaluate the proposed echo kernel. Experimental results demonstrated the superiority of the proposed echo kernel to both conventional unipolar and polar echo kernels

• Proceedings of the KIEE Conference
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• 2002.11b
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• pp.202-205
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• 2002

This paper presents the reliability evaluation methods considering the momentary voltage quality in power distribution systems. The voltage qualify phenomena deal with this paper are sustained and momentary interruptions and voltage sags. Conventional evaluation indices and methods are summarized for the sustained interruptions, and the assessment methodologies of momentary interruptions and voltage sags are proposed. The evaluation methods are divided into the analytical method and Time Sequential Monte Carlo simulation. The proposed methods are tested using the modified RBTS (Roy Billinton Test System) form and historical reliability data of KEPCO system.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.6
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• pp.33-39
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• 1998

This paper is related to economic design of tool-resetting period in NC machining. In NC lathe machining, the mean and variance of components dimension fluctuate in slow time and we should reset tool program to compensate the variation from the fluctuation. In this paper. we propose the procedure determining the optimal resetting period based on the total expected operating cost which consists of resetting cost and the quality cost related to dimension variation. As a case study, using experimental data about dimension changes of a lathe machining, we obtain the regression equations of mean and variance of the dimension fluctuation, total expected operating cost, and optimal resetting period.

• Proceedings of KOSOMES biannual meeting
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• 2001.10a
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• pp.117-134
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• 2001

Quality costs seem to be one of the effective tools to assess quality management activities, but shipping industries have not controlled quality costs because of difficulty in cost itemization and cost data collection. This study has attempted to itemize shipping quality costs in detail and researches the composition of actual quality costs of sampled shipping companies in Korea. Result of research shows that stopping quality costs were composited by 24.3%, 3.8% and 71.8% of prevention costs, appraisal costs and failure costs, respectively and very high relationship between total qualify cost and other quality costs. This research also recommended practical methods for quality management by using indexes of quality costs.

• Journal of the Korea Safety Management & Science
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• v.1 no.1
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• pp.7-17
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• 1999

As the loss from break-downs and errors, which became more frequent with the growth of elaborateness, complexity and in scale of the plant and equipments, are enormous, the improvement in the reliability, maintenance, safety, and qualify become to have interest. The fault diagnosis is a systematic and unified method to find errors, which is based on the interpretation that data, subconsciously, have noises. But, as most of the methods are inferences based on binomial logic, the uncertainty is not correctly reflected. In this study, we suggest, to manage the uncertainty in the system efficiently on the point of predictive maintenance, We should use fuzzy expert system, which make the decision considering uncertainty possible by taking linguistical variable and fixed quantity by using the fuzzy theory concepts on the basis of an expert's direct observation and experience.

• Journal of the Korean Operations Research and Management Science Society
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• v.29 no.2
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• pp.59-75
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• 2004

Recommendation is a personalized information filtering technology to help customers find which products they would like to purchase. Collaborative filtering works by matching customer preferences to other customers in making recommendations. But collaborative filtering based recommendations have two major limitations, sparsity and scalability. To overcome these problems we suggest using adjusted product hierarchy, grain. This methodology focuses on dimensionality reduction and uses a marketer's specific knowledge or experience to improve recommendation quality. The qualify of recommendations using each grain is compared with others by several experimentations. Experiments present that the usage of a grain holds the promise of allowing CF-based recommendations to scale to large data sets and at the same time produces better recommendations. In addition. our methodology is proved to save the computation time by 3∼4 times compared with collaborative filtering.

• Journal of Applied Tourism Food and Beverage Management and Research
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• v.15 no.2
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• pp.99-122
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• 2004

The purposes of this study and to develop the model to prove the structural relationship between service orientation and customer satisfaction, to find out the mediation variables between them, to survey and analyze their roles empirically, and to prove the probability of applying the strategic frame to all hotels in Korea. For these purposes, the author developed a structural model which consists of six variables. The data were collected from 7 hotels and analyzed with AMOS program. The findings can be summarized ad follows : First, the higher customer expectation, the lower customer satisfaction. Second, the higher customer expectation, the higher customer perceived quality. Third, the higher customer perceived qualify, the higher customer satisfaction. Fourth, the higher customer perceived quality, the higher customer perceived value. Sixth, the higher customer satisfaction, the lower customer complaint. Seventh, the higher customer satisfaction, the higher customer loyalty.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.613-616
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• 1999

An active-matrix LCD using thin film transistors (TFTs)has been widely recognized as having potential for high-quality color flat-panel displays. Pixel-Design Array Simulation Tool (PDAST) was used to profoundly understand the gate signal distortion and pixel charging capability, which are the most critical limiting factors for high-quality TFT-LCDs. Since PDAST can simulate the gate data and pixel voltages of a certain pixel on TFT array at any time and at any location on an array, the effect of the new set of capacitance models on the pixel operations can be effectively analyzed, The set of models which is adopted from VLSI interconnections calculate more precise capacitance. The information obtained from this study could be utilized to design the larger area and finer image quality panel.

• Proceedings of the IEEK Conference
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• 2002.06a
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• pp.53-56
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• 2002

In this paper, we study the network structure that can guarantee the end-to-end quality of service in the Explicit multicast network. In order to guarantee the end-to-end quality of service, we adopt the end-to-end measurement based admission control (EMBAC) scheme. For the effective measurement of the network state and minimum influence on the current data traffic, the queue structure, which the drop precedence in assured forwarding (AF) Per hop behavior (PHB) of the differentiated service (Diffserv) is applied to, is proposed. Through a simulation, we show that EMBAC can make tile controlled load service in tile AF PHB applied Xcast network, and the qualify of the admitted traffic is guaranteed. In addition, the performance of the EMBAC is changing according to the selling parameter of AF PHB.