• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.12
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• pp.3033-3039
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• 2000

Mechanical properties of the materials used for transportations and industrial machinery under high stain rate loading conditions have been required to provide appropriate safety assessment to these mechanical structures. The Split Hopkinson Pressure Bar(SHPB) technique with a special experimental apparatus can be used to obtain the material properties under high strain rate loading condition. There have been many studies on the material behavior under high strain rate compressive loading compared to those under tensile loading. In this paper, mechanical properties of the aluminum alloy, Al6061-T6, under high strain rate tensile loading were determined using SHPB technique.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2000.04a
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• pp.183-186
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• 2000

The high temperature deformation behavior of spray-formed Al-19wt%Si-1.87wt%Mg-0.085wt.%Fe alloy was studied by torsion testing in the strain rate range of 0.001-1 sec-1 and in the temperature range of 300-500 $^{\circ}C$. The relationship between stress temperature and strain rate is expressed using the Power law. the behavior of dynamic recrystallization is showed in 300-35$0^{\circ}C$, 1-0.1sec-1 and the behavior of dynamic recovery is showed in 450-50$0^{\circ}C$, 0.01-0.001sec-1 The size of Si particles is mall when the temperature is low and the strain rate is high. The strain rate sensitivity(m) and the apparent activation energy(Q) indicate the dependence on strain rate and temperature for flow stress respectively. The hot ductility is high when m is high and Q is low. The maps of strain rate sensitivity and apparent activation energy suggest the optimum processing conditions.

• Proceedings of the KIEE Conference
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• 1998.07g
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• pp.2480-2482
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• 1998

In this paper, the implementation of dual rate ADPCM using G.723 16Kbps and 40Kbps speech codec algorithm is handled. For small signals, the low rate 16Kbps coding algorithm shows the same SNR as the high rate 40Kbps coding algorithm, while the low rate 16Kbps coding algorithm shows the lower SNR than the high rate 40Kbps coding algorithm for large signal. To obtain the good trade-off between the data rate and synthesized speech quality, we applied low rate 16Kbps for the small signal and high rate 40Kbps for the large signal. Various threshold values determining the rate are tested for good trade off data rate and speech quality. Also the low pass filter effect of speech input and output devices is simulated at several cut-off frequencies. To simulation result shows the good speech quality at a low rate comparing with 16Kbps & 40Kbps.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.141-144
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• 2003

This paper proposes an analytical model of off-line feed rate scheduling to obtain an optimum feed rate for high speed machining. Off-line feed rate scheduling is presented as an advanced technology to regulate cutting forces through change of feed per tooth, which directly affects variation of uncut chip thickness. In this paper, the feed rate scheduling model was developed using a mechanistic cutting force model using cutting-condition-independent coefficients. First, it was verified that cutting force coefficients are not changed with respect to cutting speed. Thus, the feed rate scheduling model using the cutting-condition-independent coefficients can be applied to set the proper feed rates for high speed machining as well as normal machining. Experimental results show that the developed fred rate scheduling model makes it possible to maintain the cutting force at a desired level during high speed machining.

• Journal of Society of Preventive Korean Medicine
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• v.1 no.1
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• pp.126-136
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• 1997

To procide basic data for improvement of oriental medical care system, the questionnaire interview was carried out with community peoples, over 20 years old, selected randomly in Seoul, Pusan, Taegu and Taejon err. from 10th Mar. to 20th Apr. 1996. The result were summarized as follows: 1. In the general characteristics of subjects, the highest portion of each part was 52.4% of male, 22.4% of thirties, 37.1% of college graduates, 19.1% of married, 30.6% of town dwellers, 63.3% of muddle social class, 26.6% of housewife, 19.3% of student, 16.6% officer and 11.6% of professional technician. 2. The portion of subjects agree to open oriental clinic in western medicine hospital was 60.0%, that of disagreement was 20.1%, Among 60.0% of agreement group, the high rate was showed in female, fifties, middle school graduates, unemployed, middle social level. 3. The rate of positive responses in system of a herb specialist was 64.7%, that of negative responses was 11.6%. Among positive responses, the groups of high rate were male. twenties, above college graduates, student, middle-high social level and city dwellers. 4. In the question whether a pack of herb medicine should be included in medical insurance or not, the rate of agreement was 74.3%, that of disagreement was 4.1%. Amount agreement subjects, the high rate was showed in male, young age, high educated, city dwellers, professional technician middle social class. 5. In the cost of oriental medical care, the portion was divided by 70.3% of expensiveness,25.6% of moderate, 4.1% of low price. among 70.3% of high price, the high rate was in female, forties, agrolivestock-fishery, and town dwellers. 6. In the question what the herb doctor should do for the improvement of oriental medicine, the highest rate was 54.2% in further study. The next was 23.0% in need of western medical and 9.1% in no complain in present situation. Among 54.2% of further study, the high rate was showed in male, forties, high school graduate, profession technician, high social level, christian, married and city dwellers. 7. About institution of oriental care, 86.8% of subjects answered to need of improvement, 8.0% of them replied no problem as present. Amount 86.8% of subjects, the high rate was showed in male, twenties, above college graduate, sales, singles, high social level and city dwellers. 8. About necessity of western medical care instrument in oriental medical hospital, the rate of sightly need was 47.5%, inevitably need was 37.7%, no need was 6.3%, the Positive subjects were showed high rate in male, officer, singer, the younger age, the higher educated, better social level and city dwellers. These results might be useful information for establishing of oriental medical care policies, which open oriental medical clinic in western medical hospital, equip western medical care instrument in oriental medical hospital, improve oriental medical care instrument carry out a herb specialist system, balance the resonable medical care cost and effort for further study & research on oriental medicine to satisfy increasing need of oriental medicine.

• Proceedings of the IEEK Conference
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• 2001.06b
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• pp.297-300
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• 2001

Turbo code shows the great performance near Shannon limit on AWGN channel. Mainly, turbo code has been studied and designed for wireless digital communications. There are recent studies that applies turbo decoder on magnetic recording. Because of the limited capacity of magnetic storages, high rate turbo code is used for magnetic storages. This paper presents some issues on implementing high rate turbo code and structures for designing turbo decoder

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1997.10a
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• pp.80-83
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• 1997

The split Hopkinson bar technique is the most widely used method to study material behavior at high strain rate deformation. In the present paper, a torsional Hopkinson bar for testing thin-walled tube specimens at high strain rate is described. From the experiment of aluminum 6061, dynamic stress-strain relationship can be obtained and dynamic result is compared with static one.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2010.04a
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• pp.181-182
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• 2010

For real-time displacement monitoring of large-scale structures, the high-rate (>1 Hz) GPS data processing is necessary, which is not possible even for the scientific GPS data processing softwares. Since the baseline is generally very short in this case, most of the atmospheric effects are removed, resulting in the unknowns of position and integer ambiguity. The number of unknowns in real-time kinematic GPS positioning makes the positioning impossible with usual approach, thus two-step approach is tested in this study.

• Journal of the Korean Data and Information Science Society
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• v.18 no.3
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• pp.773-782
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• 2007

The statistical process control charts are very extensively used for monitoring of process mean, deviation, defect rate or reject rate. In this paper we consider a control chart to monitor the process reject rate in the high yield process, which is based on the observed cumulative probability of the number of items inspected until r defective items are observed. We first propose selection of the optimal value of r in the CPC-r charts, and also consider the usefulness of the chart in high yield process such as semiconductor or TFT-LCD manufacturing process.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2003.10a
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• pp.6-10
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• 2003

Accurate description of starting transient history allows and justifies the use of small margin of safety for the engine parts, resulting in high motor mass ratio in addition to satisfying the control and guidance requirements of the vehicle. Studies have been carried out for the prediction and reduction of ignition peak and pressure-rise rate during the starting transient of solid rocket motors. Numerical studies have been carried out using a two dimensional Navier-Stokes solver. It has been inferred through the parametric studies that, in the case of solid rocket motors with uniform port, high ignition peak is observed at high spread rate and low pressure-rise rate. In the case of the port with sudden expansion configuration, high ignition peak is observed at relatively high average spread rate and high-pressure rise rate. These studies are expected to aid the designer in reducing the ignition peak by altering the propellant properties or igniter characteristics without sacrificing the motor performance.