• 말소리와 음성과학
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• 제7권1호
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• pp.79-86
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• 2015

This study explored the vowel effect on acoustic perturbation measures in voice quality analysis. For this study, the perturbation parameters (%jitter, %shimmer) and noise parameter (SNR) were measured with 7 Korean vowels (/a/, /ɛ/, /i/, /o/, /u/, /ɯ/, /ʌ/) using CSpeech with 50 Korean normal young adults (24 males and 26 females). A significant vowel effect was found only in %shimmer and in particular, low-back /a/vowel was significantly different from other vowels in %shimmer. The least perturbation and noise were exhibited on high-back /ɯ/ and /o/ vowel, respectively. Based on tongue height, a significant higher %shimmer was demonstrated on low vowels than high vowels. In addition, back vowels in tongue advancement and rounded vowels in lip rounding showed significantly less perturbation and noise. The least variability of perturbation and noise within individuals was demonstrated on the vowel /i/ in three repeated measures. However, there was no significant difference among 3 token measures in single session among vowels tested except the vowel /o/. Consequently, the vowel /a/ commonly used in acoustic perturbation measures exhibited higher perturbation and noise whereas higher stability and less variability were demonstrated on the high-back vowel /u/. These results suggested that the Korean high-back vowel /u/ can be more appropriate and reliable for perturbation acoustic measures.

• 생약학회지
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• 제19권3호
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• pp.201-207
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• 1988

Samples of red ginseng, which had been manufactured and packaged by the Korean Monopoly Corporation, were stored at ambient temperatures and humidities ($12{\sim}28^{\circ}$ and $55{\sim}68$ percent) for one to nine years to examine their overall quality stability. The proximate compositions, contents of 50% ethanol and water extracts of the samples and the TLC and HPLC patterns of ginsenosides in the samples remained almost unchanged in all cases. The lipids and fatty acids in the samples, which are otherwise susceptible to oxidation, were stable judged on the basis of the changes of the TLC and GLC patterns of the lipids and fatty acids. It was also found that polyunsaturated fatty acids such as linoleic(C18:2) and linolenic and(C18:3) present in the samples had been very stable during the long storage periods. It, therefore, seems that the autoxidations of the lipid and fatty acids of red ginseng were prevented by antioxidative compounds which will be progressively formed in red ginseng through non-enzymatic browning reactions during manufacturing process and long-term storage.

• 한국수소및신에너지학회논문집
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• 제28권6호
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• pp.712-720
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• 2017

As Korean government has activated the renewable portfolio standard (RPS) since 2012, producers have been seeking and using the various renewable resources to meet the RPS quota. One of these efforts, Power Bio-Fuel oil demonstration project is being conducted to check the operability and compatibility with fossil fuel, Fuel oil (B-C) from 2014. The oil is a mixture of vegetable oil and animal fat or fatty acid ester of them and should satisfy some specification to use the power generation. The oil's quality and combustion characteristics are different from conventional oil, Fuel oil (B-C) in current power plant facility. In this study, it was investigated the storage stability and malodor intensity of Bio-Fuel oil.

• 한국수소및신에너지학회논문집
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• 제27권1호
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• pp.106-113
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• 2016

Lean burn engine, classified into port injection and direct injection, is recognized as a promising way to meet better fuel economy. Especially, LPG direct injection engine is becoming increasingly popular due to their potential for improved fuel economy and emissions. Also, LPDi engine has the advantages of higher power output, higher thermal efficiency, higher EGR tolerance due to the operation characteristics of increased volumetric efficiency, compression ratio and ultra-lean combustion scheme. However, LPDi engine has many difficulties to be solved, such as complexity of injection control mode (fuel injection timing, injection rate), fuel injection pressure, spark timing, unburned hydrocarbon and restricted power. This study is investigated to the influence of spark timing, fuel injection position and fuel injection rate on the combustion stability of LPDi engine. Piston shape is constituted the bowl type piston. The characteristics of combustion is analyzed with the variations of spark timing, fuel injection position and fuel injection rate (early injection, late injection) in a LPDi engine.

• The Journal of Asian Finance, Economics and Business
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• 제9권2호
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• pp.29-36
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• 2022

This study uses the panel probit model to investigate and evaluate the relationship between exchange rate regimes, political stability, and carbon dioxide during currency crises. To understand currency crisis times, we study a panel dataset of seven South Asian nations that contain annual observations from 1996 to 2020. Furthermore, we created the EMPI exchange market pressure indicator to detect crises. Our results strongly suggested that fixed exchange rate is negatively associated with currency crises, with good regulatory quality and better effective governments. Simultaneously, the floating exchange rate is positively related to the currency crises in those countries where the rule of law has less adequately flowed. However, CO₂, exports, and interest rates are buoyantly associated with crises. The floating exchange rate, the rule of law, exports, and interest rate are associated positively and contribute more prone to the crisis episodes. Negatively associated variables contributed less amid crises episodes: fixed exchange rate regime, government effectiveness, and regulatory quality. Meanwhile, CO₂ has a positive relationship with a currency crisis and contributes more likelihood to the probability of a currency crisis. Countries that adopted the fixed exchange rates with effective governments and regulatory quality faced more minor currency crises.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2009년도 추계학술대회 논문집
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• pp.233-234
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• 2009

• Asian-Australasian Journal of Animal Sciences
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• 제33권5호
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• pp.812-824
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• 2020

Objective: The aim of this work was to assess the effect of fermented blueberry (FB; 2%, 4%, and 6%) on the oxidative stability and volatile molecule profiles of emulsion-type sausage stored at 4℃ for 28 days. Methods: The antioxidant activity of FB was determined through radical-scavenging activity against 2, 2-diphenyl-1-picrylhydrazyl (DPPH) and hydroxyl radicals. Four formulations of sausage treatments with different FB levels (0%, 2%, 4%, 6%) were prepared, then peroxide value (POVs), thiobarbituric acid-reactive substances (TBARS) values, protein carbonyls and thiol groups were measured. The aroma profiles of sausages for each treatment was also determined. Results: The half maximal inhibitory concentration indicated that FB had greater scavenging ability than ascorbic acid against DPPH and hydroxyl radicals. Sausages with FB significantly retarded increases in POVs and TBARS, as well as in the content of protein carbonyls during all storage days (p<0.05). Particularly, 4% and 6% FB-treated sausages had better oxidation inhibition effects. However, FB accelerated the reduction in thiol groups (p<0.05). Additionally, FB inhibits the excessive formation of aldehyde compounds; for example, hexanal, which may cause rancid flavors, decreased from 58.25% to 19.41%. FB also created 6 alcohols (i.e., 2-methyl-1-propanol, 3-methyl-1-butanol, and phenylethyl alcohol), 5 ester compounds (i.e., ethyl acetate, ethyl lactate, and ethyl hexanoate) and 3-hydroxy-2-butanone in the sausages that contribute to sausage flavors. The principal component analysis showed that the aroma profiles of sausages with and without FB are easily identified. Conclusion: The addition of FB could significantly reduce the lipid and protein oxidation and improve oxidative stability for storage. Also, adding FB could inhibit rancid flavors and contribute to sausage flavors.

• 한국식품영양과학회지
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• 제28권6호
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• pp.1405-1407
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• 1999

A carotenoid pigment, which was a determinant for food quality, was extracted from a marine halophilic bacteria. The stability of the pigment extract was investigated for a food additive. The optimum temperature for stability was 20oC. The pigment degradation was significantly affected by solvent polarity, however, stable in salvent methanol and ethanol. The pigment degradation was highly sensitive to light and UV exposure.

• 한국전기전자재료학회논문지
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• 제25권2호
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• pp.125-128
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• 2012

We fabricated the electrolyte-insulator-semiconductor (EIS) devices with various high-k sensing membranes to realize a high quality pH sensor. The sensing properties of each high-k dielectric material were compared with those of conventional $SiO_2$ (O) and $SiO_2/Si_3N_4$ (ON) membranes. As a result, the high-k sensing membranes demonstrated better sensitivity and stability than the O and ON membranes. Especially, the $SiO_2/HfO_2$ (OH) stacked layer showed a high sensitivity and the $SiO_2/Al_2O_3$ (OA) stacked layer exhibited an excellent chemical stability. In conclusion, the high-k sensing membranes are expected to have excellent operating characteristics in terms of sensitivity and chemical stability for the biosensor application.

• 에너지공학
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• 제18권2호
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• pp.136-140
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• 2009

자동차 공회전은 운전자의 운전 만족도에 여러 영향을 미친다. 또한 보다 높은 연료 경제성의 요구가 고조됨에 따라, 자동차 생산자들은 계속적으로 보다 나은 운전조건의 혜택에 관심을 갖는다. 스파크 점화기관의 공회전에서 기관의 안정성은 연소변동에 의해 좌우되며, 기관의 안정성은 연료분사시기, 점화시기, 그리고 공기연료비 등의 요소들에 영향을 받게 된다. 본 연구에서는 공회전에서 연료분사시기, 점화시기 그리고 공기연료비 등에 따라, 연소의 안정성과 변동율에 미치는 영향을 조사하였다.