• 한국해양공학회지
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• 제22권2호
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• pp.65-71
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• 2008

Recently, many researches in relation to data transmission with faster speed and greater volume, many researches have been carried out on sonar systems for underwater communication. According to these researches, an acoustic transducer for underwater communication requires wide bandwidth properties. In domestic researches for underwater communication sonar, an operating frequency in the range of $20{\sim}40\;kHz$ is used. In this paper, we propose anon-resonance type acoustic transducer for underwater communication. The TVR (transmitting voltage response) characteristics increased linearly as the frequency increased, and the RVS (receiving voltage sensitivity) characteristics were constant as the frequency increased. Traditional techniques for wide bandwidth transducershave a limit and a transmission loss difference at lower and higher frequency operating ranges. In this paper, the new transducer proposed decreased the transmission loss under some conditions. It was optimized with the FE analysis tool (ATILA) and evaluated using the TVR and the RVS characteristics in the range of $10{\sim}90\;kHz$. The value of TVR was 138 dB at 20 kHz and 148 dB at 40 kHz, and the differences was 12 dB. The value of RVS was $195{\pm}2\;dB$ and nearly constant. From theseresults, it is certain that the developed transducers can be used for an underwater communication network in the 1.3 km range with both a 20 kHz bandwidth and 30 kHz center frequency.

• 응용통계연구
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• 제29권1호
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• pp.85-98
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• 2016

본 논문은 장외거래 수익률을 이용하여 추정한 여러 실현변동성들을 실증적으로 비교분석한다. 실제 금융 자산 시장에서는 장외시간이나 휴일에 거래가 적거나 드물게 나타나기 때문에 하루 전체의 실현변동성을 정확히 계산하는데 문제가 발생한다. 이를 해결하기 위해 제안되어진 장외거래 수익률을 여러 가지 방법으로 반영한 다양한 실현변동성의 추정치들에 대한 검토가 이루어진다. 실제 데이터의 실현변동성 추정치들의 예측정확성을 비교하기 위해 미국의 NASDAQ 지수와 S&P500 지수와 우리나라의 KOSPI 지수와 원/달러환율이 분석된다. 적분변동성의 불편추정치인 다음날의 로그수익률의 제곱을 기준으로 일일 실현 변동성의 추정치들은 비교되어지며 비교를 위해 절대평균오차(MAE)와 제곱평균오차근(RMSE)이 이용된다. 또한 통계적 추론을 위하여 Model Confidence Set(MCS) 방법과 Diebold-Mariano 검정법을 사용한다. 세 가지 주가지수 데이터에 대해 동일한 최적 방법이 선택되어지는데, 장외시간 수익률을 이용하여 장내시간 실현변동성의 크기 조정을 한 방법이다.

• 한국축산식품학회지
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• 제28권4호
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• pp.401-407
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• 2008

본 연구는 옻나무 급여기간이 한우육의 냉장저장 중 품질특성에 미치는 영향을 구명하고자 실시하였다. 거세한우들에게 옻나무가 4% 첨가된 사료를 도축전 0(대조구), 3, 4, 5 및 6개월 동안 급여하여 모두 동일하게 28개월령에 도축하였다. 공시재료는 우둔(M. semitendinosus) 부위를 $3{\pm}0.2^{\circ}C$에서 7일 동안 저장하였다. 조지방 함량은 4 및 5개월 급여구들이 다른 급여구들에 비해 낮았으나(p<0.05), 조단백질 함량 및 보수력은 높았다(p<0.05). 지방산 조성은 3, 4 및 5개월 급여구들의 단가불포화지방산 함량이 다른 급여구들보다 높았다(p<0.05). 저장 중 TBARS는 옻나무 급여구들에서 억제되었으며, MetMb은 3, 4 및 5개월 급여구들이 다른 급여구들에 비해 서서히 축적되었다. 표면육색은 3, 4 및 5개월 급여구들이 저장 7일까지 다른 급여구들보다 L값, a값 및 C값을 높게 유지하였으며, 특히, 저장 7일째의 a 값은 4개월 급여구가 가장 높았다(p<0.05). 결론적으로 한우에게 옻나무 4%사료를 4-5개월 동안 급여했을 때 다른 급여기간들보다 쇠고기의 보수력, 단가불포화지방산 함량 및 색택 향상에 효과적이었다.

• 한국소음진동공학회논문집
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• 제18권4호
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• pp.424-431
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• 2008

Recently, it is required that acoustic transducers for underwater detection and communication sensor have wide bandwidth and low operating frequency. In this research, the new acoustic transducer is proposed. This transducer is tonpilz type, and made of 1-3 piezoelectric composites as a driving parts. The developed transducer is evaluated the TVR(transmission voltage response) and RVS(receiving voltage sensitivity) characteristics around $4{\sim}14\;kHz$ frequency range and is compared to conventional tonpilz transducer made of solid piezoelectric ceramics as a driving parts. The resonance frequency of the developed transducer is decreased by 30% and the -3 dB bandwidth is increased by 90%, compared to conventional transducer with same dimensions. The value of TVR is decreased by 9 dB and The value of RVS is the same at resonance frequency.

• 한국수정란이식학회지
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• 제15권3호
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• pp.237-245
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• 2000

This study was carried out to elucidate whether sperm contain a factor inducing second polar body extrusion and to search for an effective collection method of the sperm factor Thus, sperm extract, dialyzed sperm-extract or liquid chromatographic fractions of sperm extract was microinjected into ovulated oocytes. And the microinjected oocytes were incubated for 24 hours to investigate about the extrusion of second polar body. The results obtained were as follows; 1. Sperm extract significantly increased the second polar body extrusion. 2. Sperm extract showed five major fractions at retention volumes (RVs) 1.25, 1.37, 1.84, 2.10 and 2.67ml after separation with Superose 12 column. These sperm extract fractions did not significantly increase the second polar body extrusion. 3. Dialyzed sperm-extract significantly increased the second polar body extrusion 4. Dialyzed sperm-extract showed three maior fractions at RVs 1.88, 2.14 and 2.77ml after separation with Superose 12 column. Of these fractions, the fraction RV2.14 significantly increased the second polar body extrusion. In conclusion, sperm extract contained a factor inducing the second polar body extrusion and the factor was contained largely in fraction RV2.14 after dialysis and liquid chromatographic fractionation of sperm extract.

• Communications for Statistical Applications and Methods
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• 제23권3호
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• pp.203-213
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• 2016

We investigate volatility spillover aspects of realized volatilities (RVs) for the log returns of the Korea Composite Stock Price Index (KOSPI) and the Hang Seng Index (HSI) from 2009-2013. For all RVs, significant long memories and asymmetries are identified. For a model selection, we consider three commonly used time series models as well as three models that incorporate long memory and asymmetry. Taking into account of goodness-of-fit and forecasting ability, Leverage heteroskedastic autoregressive realized volatility (LHAR) model is selected for the given data. The LHAR model finds significant decompositions of the spillover effect from the HSI to the KOSPI into moderate negative daily spillover, positive weekly spillover and positive monthly spillover, and from the KOSPI to the HSI into substantial negative weekly spillover and positive monthly spillover. An interesting result from the analysis is that the daily volatility spillover from the HSI to the KOSPI is significant versus the insignificant daily volatility spillover of the KOSPI to HSI. The daily volatility in Hong Kong affects next day volatility in Korea but the daily volatility in Korea does not affect next day volatility in Hong Kong.

• Toxicological Research
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• 제14권4호
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• pp.541-545
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• 1998

This experiment carried out to compare the protective effects of some antioxidants to hydroxyl radicals in embryonic mouse whole brain tissue culture. The ICR mouse whole brain (13 embryonic day) was cultured in hydroxyl radical system in which radicals were generated by 20 mU / ml glucose oxidase (GO). In this experiment, to make ferrous iron from ferric iron, iron as an accelerator, and ascorbic acid as a reductant were used. For comparison of the protective effects to hydroxyl radicals, antioxidants such as desferrioxamine (DFX), laccase. water or ethanol extracts from Rhus Vemiciflua Stokes (RVS), and $\alpha$-tocopherol were used, because they relate to metal ion. The results of this experiment showed that all antioxidants protected effectively the cytotoxicity from hydroxyl radicals in the brain cultures. More than 70% of cell viabilities among different antioxidants was at 1 mM DFX, 1.43 $\mu\textrm{m}$ laccase, 12.5 $\mu\textrm{m}$ water extract, 12.5 $\mu\textrm{m}$ ethanol extract and 50 $\mu\textrm{m}$ $\alpha$-tocopherol individually, compared with 20 mU/ml GO alone. In comparison to the antioxidative activities of antioxidants, laccase and extracts from RVS showed strong antioxidative effects even at low concentration.

• 대한건축학회논문집:계획계
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• 제34권7호
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• pp.47-57
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• 2018

As a preliminary step for developing vulnerability assessment model of terrorism, this study aims to deduce and classify architectural design elements of multi-use buildings to protect them from terrorism using explosives. For these objectives, eleven domestic and foreign guidelines of anti-terrorism, including RVS which is one of the commonly used tools for assessing vulnerability to terrorism, were analyzed. As results, 2 scenarios of explosive attack, 4 layers of defense, and 58 architectural design elements for risk assessment of terrorism were deduced. And the design elements were categorized into 18 groups based on their purpose and function to take into account the supplementary effects among them. Then, the design measures applicable for each element were classified into several grades on the basis of its protection or risk level. Lastly, 11 multi-use buildings were selected and investigated how the elements suggested in this study were applied to them.

• 한국식품과학회지
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• 제49권3호
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• pp.318-323
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• 2017

본 연구는 옻씨의 볶음 시간을 선정함으로써 관능적 특성을 분석하고, 볶은 옻씨를 함유한 차 음료를 제조하여 품질특성을 조사하였다. 또한, 저장기간에 따른 항산화활성 변화를 알아보고자 저장 온도(4, 25 및 $40^{\circ}C$)를 달리하여 28일간 저장하면서 7일 간격으로 항산화 활성을 측정하여 저장시 발생할 수 있는 변화를 살펴보았다. 차 음료를 제조하고자 기호도 조사를 통하여 가장 높은 점수를 받은 15분 볶은 옻씨로 결정되었다. 선정된 볶음군을 함유한 차 음료에 대한 pH는 A 차 음료는 7.12, B 차 음료는 7.21, C 차 음료는 7.20, D 차 음료는 7.38로 나타났다. 당도는 모든 차 음료에 대하여 $0.1-0.2^{\circ}Bx$의 범위로 나타났다. L값은 A 차 음료는 16.90, B 차 음료는 17.62, C 차 음료는 18.85, D차 음료는 18.96로 나타났고, a값은 A 차 음료는 -0.12, B 차 음료는 -0.45, C 차 음료는 -0.22, D 차 음료는 -1.17로 나타났으며 b값은 A 차 음료는 8.84, B 차 음료는 7.45, C 차 음료는 6.03, D 차 음료는 6.40으로 옻씨 자체의 색이 엷은 적갈색을 보이며 옻씨의 추출물 색으로 가까운 황색을 나타낸 A 차 음료가 가장 비슷한 값을 나타내었다. 또한, 관능검사를 통하여 맛과 전체적인 바람직성에서 A 차 음료가 높은 점수로 평가되어졌다. A차 음료에 대하여 저장 중 총 폴리페놀 및 총 플라보노이드 함량 변화는 시간이 경과함에 따라 조금 감소하였다가 증가하였지만 초기값과 비교시 비슷한 값을 나타내었다. 저장기간과 온도에 따라 관계없이 비슷한 값을 나타내어 항산화력도 높을 것으로 보인다. 저장 중 DPPH 라디칼 및 ABTS 라디칼 소거활성은 저장 기간이 길어질수록 큰 변화가 없었으며 초기값과 비교시 유의적인 차이가 없었다. 저장 중 미생물학적 안전성 검사에서는 모든 시료에서 미생물이 검출되지 않아 저장 안전성을 유지하는 것으로 나타났다.

• Natural Product Sciences
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• 제13권1호
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• pp.1-5
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• 2007

Dietary flavonoids have antioxidant and antitumor promoting effects. Rhus verniciflua Stokes (RVS) is a flavonoid-rich herbal medicine and has long been used as a food additive and an antitumor agent in Korea. Previous study demonstrated that a purified flavonoid fraction prepared from RVS, herein named RCMF (the RVS chloroform-methanol fraction), exhibited growth inhibition and induced apoptosis in human osteosarcoma(HOS) cells. This study evaluated if p53-mediated pathway is associated with the RCMF-induced apoptosis in HOS cells. RCMF was shown to be capable of inducing apoptosis of the cells, as expected, and transparently increased p53 expression in the cells. However, the RCMF-induced cytotoxicity was suppressed by transfecting the cells with antisense p53 oligonucleotide, which also inhibited the decrease of Bcl-2 and the increase of Bax in mitochondria, and the release of cytochrome c into cytosol. This finding suggests that p53-mediated mitochondrial stress is required for RCMF-induced apoptosis in HOS cells.