• Transactions of Materials Processing
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• v.32 no.4
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• pp.173-179
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• 2023

In this study, the age-hardening behavior and tensile properties of a cast AZ91-0.3Ca-0.2Y (SEN9) alloy are investigated and compared with those of a commercial AZ91 alloy. Even after homogenization heat treatment, the SEN9 alloy contains numerous undissolved secondary phases, Al₈Mn₄Y, Al₂Y, and Al₂Ca, which results in a higher hardness value than the homogenized AZ91 alloy. Under aging condition at 200 ℃, both the AZ91 and SEN9 alloys exhibit the same peak-aging time of 8 h, but the peak hardness of the latter (86.8 Hv) is higher than that of the former (83.9 Hv). The precipitation behavior of Mg₁₇Al₁₂ phase during aging significantly differs in the two alloys. In the AZ91 alloy, the area fraction of Mg₁₇Al₁₂ discontinuous precipitates (DPs) increases up to ~50% as the aging time increases. In contrast, in the SEN9 alloy, the formation and growth of DPs during aging are substantially suppressed by the Ca- or Y-containing particles, which leads to the formation of only a small amount of DPs with an area fraction of ~4% after peak aging. Moreover, the size and interparticle spacing of Mg₁₇Al₁₂ precipitates of the peak-aged SEN9 alloy are smaller than those of the peak-aged AZ91 alloy. The homogenized AZ91 alloy exhibits a higher tensile strength than the homogenized SEN9 alloy due to the finer grains of the former. However, the peak-aged SEN9 alloy has a higher tensile elongation than the peak-aged AZ91 alloy due to the smaller amount of brittle DPs in the former.

• Journal of Korean Physical Therapy Science
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• v.7 no.2
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• pp.711-725
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• 2000

The purpose of this study was to determine the effects of knee flexor isokinetic training on the mean peak torque of knee muscles and hamstrings-to-quadriceps ratio(H/Q ratio) in hemiplegia able to walk independently for more than 10 meters, to analyze the effect of torque increasing on functional aspects; fatigability and ambulation times, also. Forty-one adult subjects with hemiplegia secondary to a stroke partipated in this study. All participants were in/out patients at the College of Medicine, Pocheon CHA University, Pundang CHA General Hospital. The patients were allocated to two groups: one group exclusively for isokinetic maximal voluntary knee flexor training at $150^{\circ}$/sec(n=20) and the other exclusively for isokinetic maximal voluntary knee flexor training from $30^{\circ}$/sec to $150^{\circ}$/sec (n=21) gradually. The allocation was performed according to patient age, sex, affected side to minimize imbalance between the two training groups. Training was carried out from February 14th, 2000 to April 15th, 2000. Analysis of the data was done by means of t-test, x2-test, paired t-test, ANOVA, and multiple regression analysis. The results of this study were as follows: 1. There were no significant differences between the two groups in mean peak torque of knee muscles and relative decreases in knee extensor mean peak torque with increased knee flexor velocities before training (P<.05). 2.There was no significant differences between the two groups in the H/Q ratio, and no relative increases with increased knee flexor velocities before training. 3. there were significant changes in mean peak torque in group A after training(P<.05), but no significant differences as the velocity increased 4.there were significant changes in mean peak torque in group B after training(P<.05), but no significant differences as the velocity increased 5.there were no significant differences between the two groups, and no significant differences in mean peak torque increase rate between the groups with increased knee flexor velocities after training 6.H/Q ratio increased with increased knee flexor velocities between the two groups, but not statistically And there was no significant differences between the groups with increased knee flexor velocities 7.After training, Ambulation time and its decreasing rate decreased significantly in group B (P<.05) 8Before and after training, there was no significant differences between the groups in the fatiguability 9. In the multiple regression analysis, mean peak torque increase rate of the knee extensor and flexor were higher in group B than A(P<.05), and significantly higher with increased knee flexor velocities (P<.05) Also, training method influenced on Ambulation times decreases significantly(P<.05). Results indicated that knee flexor isokinetic training was effective to knee extensor and flexor mean peak torque increase in the hemiplegia able to walk independently for more than 10 meters. Therefore, we were able to conclude that gradual training from low to high velocity was more effective in the increase of mean peak torque of knee joint and decrease of Ambulation times than training only at high velocity.

• Journal of the Korean Society for Nondestructive Testing
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• v.35 no.5
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• pp.291-298
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• 2015

An array type probe for monitoring metal tubes is proposed in this paper which utilizes peak value and peak time of a pulsed eddy current(PEC) signal. The probe consists of an array of encircling coils along a tube and the outside of coils is shielded by ferrite to prevent source magnetic fields from directly affecting sensor signals since it is the magnetic fields produced by eddy currents that reflect the condition of metal tubes. The positions of both exciter and sensor coils are consecutively moved automatically so that manual scanning is not necessary. At one position of send-receive coils, peak value and peak time are extracted from a sensor PEC signal and these data are accumulated for all positions to form an array type peak value signal and an array type peak time signal. Numerical simulation was performed using the backward difference method in time and the finite element method for spatial analysis. Simulation results showed that peak value increases and the peak appears earlier as the defect depth or length increases. The proposed array signals are shown to be excellent in reflecting the defect location as well as variations of defect depth and length within the array probe.

• Journal of Applied Biological Chemistry
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• v.63 no.1
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• pp.29-33
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• 2020

The objective of this study was to develop a fast and accurate method of variety discrimination and geographical discrimination origin of Korean angelica (Korean variety, Angelica gigas Nakai) by using TDU-GC/MS. Two peaks of decursin and decursinol, which are coumarin derivatives were identified in the range of Total Ion Chromatogram (TIC) RT 26.9-27.2 of the Korean angelica by GC/MS analysis at the time of condensation in a refrigerated condensation system after thermal desorption of sample extracts. In case of Chinese angelica (Chinese variety), ligustilide peak was detected at the RT 17.2. In order to investigate the difference of volatile components according to the geographical origin of Korean variety, the mass spectra were measured by TDU-GC/MS at the range of m/z 40-400 amu. The TIC of domestic cultivation and Chinese cultivation of the Korean variety, Angelica gigas Nakai showed the same tendency as a whole. However, in partial scans of TIC, two peaks detected at 15.54 and 16.05 of RT showed different peak patterns between Korean angelica (Korean variety) cultivated in Korea and in China. The ratio of Peak A (RT 15.54) and B (RT 16.05) was 0.0-0.2 for domestic cultivation and 0.5-2.8 for Chinese cultivation, confirming the possibility of discriminating origin by comparing the TIC peak pattern of TDU-GC/MS.

• Phonetics and Speech Sciences
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• v.4 no.3
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• pp.43-49
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• 2012

This paper describes the categorical effects of pitch accent contrasts in a mimicry task. It focuses, specifically, on examining how fundamental frequency (f0) variation reflects phonological contrasts from speakers of two distinct varieties of Korean (i.e., North Kyungsang and South Cholla). The results showed that, in a mimicry task using synthetic speech continua, there was a categorical effect in f0 peak timing for North Kyungsang speakers, but the timing of f0 peaks and valleys in the responses of South Cholla speakers was more variable, presenting a gradient or non-categorical effect. Evidence of categorical effects was represented as the shift of f0 peak times along an acoustic continuum for North Kyungsang speakers. The range for the shift of f0 valley times was much narrower, compared to that of f0 peak times. The degree of a shift near the middle of the continuum showed variability across individual mimicry responses. However, the categorical structure in mimicry responses regarding the clustering of f0 peak points was more significant for North Kyungsang speakers than for South Cholla speakers. Additionally, the finding of the current study implies that the location of f0 peak times depends on individuals' imitative (or cognitive) abilities.

• Applied Biological Chemistry
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• v.2
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• pp.36-39
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• 1961

It has been ascertained that S-(1, 2-dichlorovinyl) L-cysteine (DCVC) is probably the toxic component in the trichloro-ethylene extracted soybean oil meal on the bovine. For the study of the metabolites of DCVC, the components with radioactive $S^{35}$-in the urine of the calf, to which $S^{35}$-DCVC was administrated, were separated using of cellulose powder with propanol-water (70:30 V/V) which is easily removable by evaporation. As the results followings were obtained: Peak 1, which shows fractions containing single $S^{35}$-radioactive components, whose Rf is 0.815 Peak 2, which shows fractions containing jingle $S^{35}$-radioactive component, whose Rf is 0.447 Peak 3, which shows fractions containing both $S^{35}$-radioactive components whose Rfs are 0.090 and 0.171 Peak 4, which shows fractions containing single $S^{35}$-radioactive component, whose Rf is 0.142. Peak 5, which shows fractions containing single $S^{35}$-radioactive component, whose Rf is 0.084. Besides these, two of small peak were obtained. Although, the resolving power of the cellulose powder column is not sufficient, it is applicable for the study of the components of metabolytes of DCVC conveniently with the rest of removable solvent easily. Also the components with radioactive $S^{35}$ in the feces of the calf were separated using citrate buffer gradient system of Moore and stein. As the results; three $S^{35}$-radioactive components were separated.

• Proceedings of the KIEE Conference
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• 2008.11a
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• pp.460-462
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• 2008

일반 수용가를 대상으로 한 효율적인 수요관리의 한 방법으로써 Dynamically-Administered Critical Peak Pricing[1] 요금제를 이용하여 일반 수용가 대상 수요관리를 스마트 미터기인 Smart Cabinet Panel(SCP)를 개발하여 적용하였다. 이 DA-CPP 요금제에는 핵심이 되는 최적 critical peak 시점을 푸는 하위 문제들 및 방법론들이 존재하는데, 우리는 energy service provider(ESP)가 관리해야 할 수용가의 수가 매우 많다는 점에 주목하여, 각 수용가의 1일 부하 사용량 패턴을 몇 개의 그룹으로 나누어 각 그룹에 대해 critical peak 최적 시점을 결정하는 연구를 수행하였다. 이러한 수용가 부하량 패턴그룹화를 위해 인공 지능의 여러 기법 중 하나인 self-organizing map(SOM)을 사용하였다 그리고 ESP와 수음가가 통신할 수 있도록 개발된 SCP를 통해 Critical Peak을 적용하였다.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.11
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• pp.75-80
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• 2012

In this paper, the operational characteristics due to the introduction of the superconducting fault current limiter(SFCL) with a peak current limiting function were analyzed in the power distribution system. The parallel structure of the superconducting element can operate the peak current limiting function depending on the transient amplitude of fault current. We studied the operating characteristics of the introduction of the SFCL with a peak current limiting function in the power distribution system. Furthermore, we were analyzed between the SFCL with a peak current limiting function and the protection devices in the power distribution system, through the short circuit experiments.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.13 no.6
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• pp.315-319
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• 2003

The quality, quantity, color, and characteristics were found out cultured seawater pearls and freshwater pearls. In the XRF measurement Ca chemical combinations were the main elements and Sr was detected at higher levels for the sea-water pearl and Si, S, Ca, Mn, P and other elements were found at higher levels for the fresh-water pearls. Such differences is judged to be caused by the ion diluted in sea and fresh water which affects the pearl elements. Although near similar structural peak was shown for the FT-IR measurement, the fresh-water pearl showed a lower peak for the 2344 wave. For the results of PL, the peak for fresh-water measured with Hd-Cd Laser at 455 nm was higher and with the Ar-ion Laser measurements, peaks were high at 545 nm and 570 nm for fresh-water pearl and sea-water pearls respectively.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.586-587
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• 2008

지난 논문 "Critical Peak Pricing 요금제를 이용한 일반 수용가 대상 수요관리의 방법" 및 그 후속 연구에서는 일반 수용가를 대상으로 한 효율적인 수요관리의 한 방법으로써 Critical Peak Pricing 요금제를 제안하였다[1]. 또한 이 요금제에서 핵심이 되는 최적 critical peak 시점을 푸는 하위 문제들 및 방법론을 제시하였는데, 이 논문에서는 그 하위 문제들 중 수용가의 부하를 예측하는 문제를 다룬다. 우리는 energy service provider(ESP)가 관리해야 할 수용가의 수가 매우 많다는 점에 주목하여, 각 수용가의 1일 부하 사용량 패턴을 몇 개의 그룹으로 나누어 각 그룹에 대해 critical peak 최적 시점을 결정하는 연구를 수행하였다. 이러한 수용가 부하량 패턴 그룹화를 위해 인공 지능의 여러 기법 중 하나인 self-organizing map(SOM)을 사용하였다.