• Transactions of the Korean Society of Automotive Engineers
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• v.4 no.6
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• pp.223-228
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• 1996

The frequency of the brake squeal noise can be changed during braking, and this frequency shifting is due to variation of braking deceleration rate. The natural frequency of the brake system also shifted according to deceleration rate. It makes difficult to treat this problem. This paper shows an experimental study on the brake squeal noise having main frequencies of about 450~500Hz. And it shows how to improve the brake squeal noise problem.

• Journal of the Korean Mathematical Society
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• v.32 no.1
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• pp.7-15
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• 1995

Multigrid method has been used widely to solve elliptic problems because of its applicability to many class of problems and fast convergence ([1], [3], [9], [10], [11], [12]). The estimate of convergence rate of multigrid is one of the main objectives of the multigrid analysis ([1], [2], [5], [6], [7], [8]). In many problems, the convergence rate depends on the regularity of the solutions([5], [6], [8]). In this paper, we present an improved estimate of reduction factor of multigrid iteration based on the proof in [6].

• Proceedings of the Acoustical Society of Korea Conference
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• 1984.12a
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• pp.66-69
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• 1984

This paper is a study on the Endpoint Detection for Korean Speech Recognition. In speech signal process, analysis parameter was classification from Zero Crossing Rate(Z.C.R), Log Energy(L.E), Energy in the predictive error(Ep) and fundamental Korean Speech digits, /영/-/구/ are selected as date for the Recognition of Speech. The main goal of this paper is to develop techniques and system for Speech input ot machine. In order to detect the Endpoint, this paper makes choice of Log Energy(L.E) from various parameters analysis, and the Log Energy is very effective parameter in classifying speech and nonspeech segments. The error rate of 1.43% result from the analysis.

• Proceedings of the Korean Ceranic Society Conference
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• 1986.12a
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• pp.211-225
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• 1986

Silicon carbide coating has been studied using a graphite substrate, a mixture of tetramethylsilane and hydrogen or argon at deposition temperature (T) of 950 to $1200^{\circ}C$ total pressure of 20 to 50 torr and carrier gas flow rate of 0 to 901/h. Deposition kinetic study has shown that a transition, from a surface reaction limited process to a diffusion limited one, takes place near $1100^{\circ}C$. Deposition rate depends directly upon the experimental parameters. The influence of the main process parameters is also discussed to relate the physiochemical properties of the coating to the deposition conditions.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.6 no.3
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• pp.309-317
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• 1996

Al2O3 thin films were deposited on Si-wafer (100) using organo-aluminum compounds at low pressure by chemical vapor deposition (CVD) method. The vapor of the organo-metallic precursor was carried by pure N2 gas. The deposition rate increased and then saturated as Tsub increased with increasing the AIP flow rate. The main contamination didn't found in deposited films except carbon. The H-O(H2O) IR absorption band decreased in intensity as the deposition temperature increased, and completely disappeared through annealing.

• Journal of the Korean Society of Safety
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• v.8 no.4
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• pp.91-94
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• 1993

The main purpose of this study was to develop fuzzy models in order to decide system failure rate in industrial accident prevention. The purposed linguistic approach uses the Zadeh's concept of a linguistic variable with value which are not number. The problem of measurement Is the assignment of numbers to reprresnt properties of the involved events, object, or situation. Thus, in this study, part standard compatibility function was used.

• Journal of Aerospace System Engineering
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• v.13 no.4
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• pp.50-59
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• 2019

The design of the main control valve, which is the main component of the flap control system, was based on actual manufacturing experience on the basis of trial and error method. In this paper, a model-based part design method is proosed. The flap control system consists of a main control valve, fail-safe valve, solenoid valve, LVDT and force motor. The main control valve consists mainly of a spool and slot. The important design parameters of the main control valve are the slot width, overlap and clearance. AMESim is linked to the model and it analyzes the flow path of the main control valve. Applying the proposed design procedure, it was confirmed that the required performance was satisfied within the allowable machining error range.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.1028-1032
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• 2004

In order to prevent machine tool feed slide system from transient vibrations during operations, machine tool designers usually adopt some typical design solutions; box-in-box typed feed slides, optimizing moving body for minimum weight and dynamic compliance, and so on. Despite all efforts for optimizing design, a feed drive system may experience severe transient vibrations during high-speed operation if its feed rate control is unsuitable. A rough feed rate curve having discontinuity in its acceleration profile causes a serious vibration problem in the feed slides system. This paper presents a feed rate optimization of a ball screw driven machine tool feed slide system for its minimum vibration. Firstly, a ball screw feed drive system was mathematically modeled as a 6-degree-of-freedom lumped parameter system. Next, a feed rate optimization of the system was carried out for minimum vibrations. The main idea of the feed rate optimization is to find out the most appropriate smooth acceleration profile with jerk continuity. A genetic algorithm was used in this feed rate optimization

• Clinical and Experimental Reproductive Medicine
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• v.44 no.2
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• pp.105-110
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• 2017

Objective: The purpose of this study was to evaluate the efficacy of frozen mixed double-embryo transfer (MDET; the simultaneous transfer of day 3 and day 5 embryos) in comparison with frozen blastocyst double-embryo transfer (BDET; transfer of two day 5 blastocysts) in patients with repeated implantation failure (RIF). Methods: A total of 104 women with RIF who underwent frozen MDET (n = 48) or BDET (n = 56) with excellent-quality embryos were included in this retrospective analysis. All frozen embryo transfers were performed in natural cycles. The main outcome measures were the implantation rate, clinical pregnancy rate, multiple pregnancy rate, and miscarriage rate. These measures were compared between the patients who underwent MDET or BDET using the chi-square test or the Fisher exact test, as appropriate. Results: The implantation and clinical pregnancy rates were significantly higher in patients who underwent MDET than in those who underwent BDET (60.4% vs. 39.3%, p=0.03 and 52.1% vs. 30.4%, p=0.05, respectively). A significantly lower miscarriage rate was observed in the MDET group (6.9% vs. 10.7%, p=0.05). In addition, the multiple pregnancy rate was slightly, but not significantly, higher in the MDET group (27.1% vs. 25.0%). Conclusion: MDET was found to be significantly superior to double blastocyst transfer. It could be regarded as an appropriate approach to improve in vitro fertilization success rates in RIF patients.

• Journal of Environmental Science International
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• v.5 no.3
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• pp.337-346
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• 1996

The purpose of this study was to provide basic data of the growth characteristics of the landscape trees for better landscape planting design, construction and maintenance through the prediction of landscape change as time passes fly the analysis of survival rate, distribution patterns & increment percent of tree height, width, stem diameter (breast or surface) of widely used six tree species in Seongnam-si Eunhang-jugong apartment housing areas (8 years have passed after landsape alanting work). The main results can be summarized as followed. The tree survival rate of Pinus parviflora was the highest rate 89.2% than any other species, but Acer buergerianum showed the lowest survival rate at that of it 35.0%, & that of Picea abies 70.5 %, Metasequoia glyptostroboides 71.6%, Maknolia denudata 38.9%, Acer paimatum was 71.7%, As a whole, the tree survival rate of coniferous trees were relatively high. The tree height increment percent of the deciduous species wert relatively high. And that of Metasequoia glyptostroboides was the highest rate 11.61% than any other species, but that of Magnolia denudata was the lowest rate 5.59% than any other species. According to this results, the increment percent of trees in this apartment areas were comparatively lower than that of each related species planted in nursery area. And this results would be considered when landscape experts do landscape planting design, construction & maintenance. The distribution patterns of present tree size showed a Normal Distribution like any other biological features.