• Journal of the Korean Society of Manufacturing Process Engineers
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• v.3 no.1
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• pp.28-37
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• 2004

An on-line monitoring system of endmill failure such as weal, chipping, and fracture is developed using AE, cutting force Characteristic variations of AE and cutting force signals due to endmill failure are identified as follows. When endmill fracture occurs, AE count rate shows a rapid Increase in conjunction with a subsequent decrease while a standard deviation of the principal cutting force Increases significantly. The increase of AE count rate precedes the Increase of standard deviation of principal cutting force. Chipping results in relatively small increase and decrease of AE count rate without any significant variation of the cutting force Gradual increase of AE count rate and mean principal cutting force are Identified to be related with the wear of cutter. A cutter fracture detection algorithm is developed based on the present results. The signals me normalized to enhance the applicability of the algorithm to Wide those of fresh cutters, and qualitative characteristics of AE signals encountered at the moment of fracture are employed. It is demonstrated that the algorithm can detect the cutter fracture successfully.

• Journal of the Korean Applied Science and Technology
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• v.25 no.4
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• pp.418-428
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• 2008

Transesterification of fat of Tra catfish with methanol in the presence of the KOH catalyst yields fatty acid methyl esters (FAME) and glycerol (GL). The effects of the reaction temperature and reaction time on rate constants and kinetic order were investigated. Three regions were observed. In the initial stage, the immiscibility of the Tra fat and methanol limited the reaction rate, hence this region was controlled by the mass transfer. Subsequent to this region, produced FAME like a co-solvent made the reaction mixture homogeneous, therefore the conversion rate increased rapidly so it was controlled by the kinetic parameters of the reaction until the equilibrium was approached in the final slow region. A second-order kinetic mechanism was proposed involving second regions for the forward reaction. The rate determining step for the overall KOH catalyzed-methanolysis of Tra fat was the conversion of triglycerides (TG) to diglycerides (DG). This rate constant was increased from 0.003 to $0.019min^{-1}$ when the reaction temperature was increased from 35 to $60^{\circ}C$. Its calculated activation energy was 14.379 ($kcal.mol^{-1}$).

• Structural Engineering and Mechanics
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• v.44 no.6
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• pp.801-814
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• 2012

The strain rate effects on the interaction between a Mode I matrix crack and an inclined elliptic matrix-inclusion interface under dynamic tensile loadings were investigated numerically, and the results are in agreement with previous experimental data. It is found, for a given material system, that there are the first and the second critical strain rates, by which three kinds of the subsequent crack growth patterns can be classified in turn with the increasing strain rate, namely, the crack deflection, the double crack mode and the perpendicular crack penetration. Moreover, such a crack deflection/penetration behavior is found to be dependent on the relative interfacial strength, the inclined angle and the inclusion size. In addition, it is shown that the so-called strain rate effect on the dynamic strength of granule composites can be induced directly from the structural dynamic response of materials, not be entirely an intrinsic material property.

• The Journal of Asian Finance, Economics and Business
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• v.8 no.5
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• pp.37-41
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• 2021

This study aims to investigate the relationship between the exchange rate and Trade Balance. Trade Balance is used as the dependent variable, and the independent variables are Exchange Rate, Gross Domestic Product, and Inflation. Augmented Dickey-Fuller unit root test was adopted to test the stationary property of time series data, Auto Regressive Distributed Lag model was employed to find the long run and short-run relationship and long-run adjustment, Bound test approach, the unrestricted Error Correction Model and Granger Causality Test are used to analyze the data from 1977 to 2019. The research findings suggest that inflation has a positive impact on the trade balance in the short run. The exchange rate and the Gross Domestic Product have adverse effects on Trade balance in the long run. The coefficient of ER in the previous year is negative, and the coefficient of TB in the previous year is positive and significant. This is consistent with the J-Curve phenomenon, which states that devaluation may not improve trade balance in the immediate period, but will significantly impact the trade balance improvement in subsequent periods. Hence Marshall Lerner Condition exists in Sri Lanka.

• The Bulletin of The Korean Astronomical Society
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• v.44 no.1
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• pp.48.2-48.2
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• 2019

Tidal disruption events (TDEs) provide evidence for quiescent supermassive black holes (SMBHs) in the centers of inactive galaxies. TDEs occur when a star on a parabolic orbit approaches close enough to a SMBH to be disrupted by the tidal force of the SMBH. The subsequent super-Eddington accretion of stellar debris falling back to the SMBH produces a characteristic flare lasting several months. It is theoretically expected that the bolometric light curve decays with time as proportional to $t^{-5/3}$. However, some of the observed X-ray light curves deviate from the $t^{-5/3}$ decay rate, while some of them are overall in good agreement with the $t^{-5/3}$ law. Therefore, it is required to construct the theoretical model for explaining these light curve variations consistently. In this paper, we revisit the mass fallback rates semi-analytically by taking account of the stellar internal structure, orbital eccentricity and penetration factor. We find that the mass fallback rate is shallower than the standard $t^{-5/3}$ decay rate independently of the polytropic index, and the orbital eccentricity only changes the magnitude of the mass fallback rate. Furthermore, the penetration factor significantly can modify the magnitude and variation of mass fallback rate. We confirm these results by performing the computational hydrodynamic simulations. We also discuss the relevance of our model by comparing these results with the observed light curves.

• ETRI Journal
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• v.31 no.1
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• pp.21-30
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• 2009

In low bit-rate video transmission, the payload of a single packet can often contain a whole coded frame due to the high compression ratio in both spatial and temporal domains of most modern video coders. Thus, the loss of a single packet not only causes the loss of a whole frame, but also produces error propagation into subsequent frames. In this paper, we propose a novel whole frame error concealment algorithm which reconstructs the first of the subsequent frames instead of the current lost frame to suppress the effects of error propagation. In the proposed algorithm, we impose a constraint which uses side match distortion (SMD) and overlapped region difference (ORD) to estimate motion vectors between the target reconstructed frame and its reference frame. SMD measures the spatial smoothness connection between a block and its neighboring blocks. ORD is defined as the difference between the correlated pixels which are predicted from one reference pixel. Experimental results show that the proposed algorithm effectively suppresses error propagation and significantly outperforms other conventional techniques in terms of both peak signal-to-noise ratio performance and subjective visual quality.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.152-152
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• 2017

Plants exposed to environmental stress for long durations often can adapt to stress conditions with improved tolerance. Moreover this acquired tolerance to stress can be retained even after reverting to destressed growth conditions, which is known to stress memory. In these adaptation and stress memory processes, epigenetic regulation, such as DNA methylation and histone modifications play a key role. Here, we showed that regenerated rice plants from embryogenic callus exposed to gradually increasing NaCl concentrations (up to 120 mM NaCl) acquired salt tolerance and their enhanced tolerance are inherited to subsequent generations. The rice plants (R0) regenerated from rice callus under saline conditions were transplanted into normal paddy field and R1 seeds were harvested. These R1 seeds displayed higher germination rate on MS medium containing 100mM NaCl than wild-type. The callus derived from R1 seeds showed better growth than control callus on high salinity medium. And the salt-adapted R1 plants exhibited higher chlorophyll contents and also higher $K^+/Na^+$ ratio than wild-type rice under saline conditions. The results indicated that rice plants successfully adapted to saline growth conditions during regeneration on high salt medium and moreover this acquired tolerance to salt stress was inherited subsequent generation.

• Journal of Biosystems Engineering
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• v.27 no.6
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• pp.491-500
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• 2002

This study was carried out to investigate experimentally the effect of the tire inflation pressure of a tractor on soil compaction and tractive performance. Two kinds of field experiments were conducted using an agricultural tractor. One experiment is concerned with the tractive performance of the tractor at the three levels of tire inflation pressure; 50kpa, 100kpa and 200kpa, and the other one is about the soil compaction at the four levels of tire inflation pressure; 50kpa, 100kpa, 150kpa and 200kpa, at three different numbers of passes; 1, 3 and 5 passes. From the results of the field experiment, it was found that decreasing the tire inflation pressure decreased the motion resistance of tractor and increased the tractive force and tractive efficiency. The tractive and working performance of the tractor could be improved by the reduction of tire inflation pressure. Increasing the inflation pressure and the number of passes increased the soil compaction. Rate of compaction increased rapidly at the first pass and declined at subsequent passes. To reduce the effect of soil compaction for the whole field, it is recommended that tractor should follow the rut of the first pass from the subsequent passes, and decrease the inflation pressure of the driving tires up to allowable minimum level.

• East Asian Economic Review
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• v.24 no.2
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• pp.127-164
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• 2020

We perform an econometric assessment of the role that pharmaceutical innovation-the introduction and use of new drugs-has played in improving the health of Koreans, by investigating whether diseases for which more new drugs were launched had larger subsequent increases in longevity and smaller subsequent increases in hospitalization. Drugs launched during 1993-2012 are estimated to have increased mean age at death from all diseases by 1.71 years between 1995 and 2015 and 1.09 years between 2005 and 2015. We also estimate that new drugs increased the five-year relative survival rate from all cancers combined by 23.2 percentage points-78.5% of the total increase-between 1993-1995 and 2011-2015, and that new drugs launched during 2008-2010 reduced the number of hospital days in 2017 by 13.0 million. If the drugs launched during 2003-2012 had had no effect on other medical expenditure in 2015, the cost per life-year gained would not have exceeded 6332 USD. Therefore, even if we ignore the effect of new drugs on hospital utilization, the drugs launched during 2003-2012 were very cost-effective, overall. When reduced hospital utilization is accounted for, the evidence indicates that, in the long run, pharmaceutical innovation was cost-saving as well as life-year saving.

• Asian-Australasian Journal of Animal Sciences
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• v.16 no.4
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• pp.489-493
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• 2003

Reproductive traits of sows are determined chiefly by the genetic background of the dam herself. Whether the breed of the serviced boars also contributes is not yet clear. A total of 8,946 litters of Landrace (L) sows from 68 farms were examined. Of these, 876, 1,260, and 6,810 litters were produced from natural mating with L, Yorkshire (Y), and Duroc (D) breeds, respectively. The birth litter size (BLS), weaning litter size (WLS), live born piglets (LBP), and survival rate % (SR), of every litter were recorded. A general linear-model procedure was followed to estimate the effects of boars' breed (B), parity (P) and B${\times}$P interaction on the reproductive traits of the sows. Results show that BLS, WLS, and LBP were all significantly (p<0.001) affected by B and P. SR% was significantly influenced by B but not by P. L sows crossbred with Y or purebred with L produced litters with higher BLS, WLS, and LBP values than those bred with D. Pure L breeding yielded litters with lower SR% than did crossbreeding with D, while the difference between SR% due to LY and that due to LD crossbreeding was not significant. The interaction of B with P was significant with respect to BLS, WLS, and LBP (p<0.001), but not SR%. No significant B effect on reproductive traits was measured in sows at their first parity; but at latter parities, LL or LY produced litters with similarly high BLS, WLS and LBP, which values were all significantly greater than those of LD litters. The breed of boar evidently affected the subsequent reproductive performance of L sows and this effect may be further manipulated by the parity effect. Breed differences in semen quality and the success of fetus development with different interactions of the genetic background with the uterus function of the sow that may contribute to these effects are discussed.