• 대한전자공학회논문지TC
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• 제45권11호
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• pp.23-31
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• 2008

이 논문에서는 OFDM 및 SC-FDE 시스템에서 다이버시티 기술의 적용이 채널부호화율에 미치는 상관관계에 대해서 살펴본다. OFDM 시스템에서는 채널의 다중경로 프로파일에 따라서 적절한 채널부호화율의 결정이 필요하며 순환지연 다이버시티 기술을 적용하는 경우가 시공간 부호화 기술을 적용하는 경우보다 더 낮은 채널부호화율을 필요로 한다. 이에 반해서 OFDM에 DFT 확산을 적용한 SC-FDE 시스템에서는 낮은 채널부호화율을 적용할 필요성이 없으며 다이버시티 기술의 적용과 상관없이 상대적으로 높은 채널부호화율이 사용될 수 있다.

• Journal of Preventive Medicine and Public Health
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• 제53권4호
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• pp.220-227
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• 2020

Objectives: The aim of this study was to assess how different social determinants of health (SDoH) may be related to variability in coronavirus disease 2019 (COVID-19) rates in cities and towns in Massachusetts (MA). Methods: Data about the total number of cases, tests, and rates of COVID-19 as of June 10, 2020 were obtained for cities and towns in MA. The data on COVID-19 were matched with data on various SDoH variables at the city and town level from the American Community Survey. These variables included information about income, poverty, employment, renting, and insurance coverage. We compared COVID-19 rates according to these SDoH variables. Results: There were clear gradients in the rates of COVID-19 according to SDoH variables. Communities with more poverty, lower income, lower insurance coverage, more unemployment, and a higher percentage of the workforce employed in essential services, including healthcare, had higher rates of COVID-19. Most of these differences were not accounted for by different rates of testing in these cities and towns. Conclusions: SDoH variables may explain some of the variability in the risk of COVID-19 across cities and towns in MA. Data about SDoH should be part of the standard surveillance for COVID-19. Efforts should be made to address social factors that may be putting communities at an elevated risk.

• 대한지리학회지
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• 제39권1호
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• pp.88-101
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• 2004

본 연구는 재활용 생활계 폐기물의 수거경로를 살펴보고, 재활용품에 의한 수거유형과 지역특성과의 관계를 밝히는 것을 목적으로 한다. 분석결과는 다음과 같다. 인구규모가 크고 증가율이 높으며 제2차 산업 인구구성비와 재정자립도가 높은 지역에서는 종이류와 고철류가 주로 수거되고, 인구규모가 작고 증가율도 낮거나 감소하며, 제1차 산업 인구구성비와 농가율이 높은 농촌지역에서는 기타를 포함하여 고철류, 종이류, 병류 등의 다양한 수거가 나타난다. 이는 지역에 발달한 산업에 의해 재활용 생활계 폐기물의 수거유형이 다르다는 것을 의미한다.

• 한국가축번식학회지
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• 제19권4호
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• pp.265-270
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• 1996

This study was carried out to investigate on the survival rates and in vitro developmental rates of bisected bovine embryos by micromanipulator and micropipette. Bisected embryos were cultured for 1∼5 days in 20% FCS＋TCM-199 medium. Survival rate and in vitro developmental rate were defined as development rate on in vitro culture or FDA-test. The results are summarized as follows ; 1. The survival rates of intact or free zona pellucida of bisected embryos were 30.3 and 25.0%, respectively. And the survival rates of bisected embryos by micromanipulator and micropipette were 33.3 and 26.7%, respectively. The survival rate of bisected embryos was significantly lower than that of non-bisection embryos(65.0%). 2. The survival rates of bisection embryos in cultured for 12, 24, 48, 72 hrs with 20% FCS＋TCM-199 medium were 40.0, 30.0, 23.3 and 13.3%, respectively. 3. The in vitro developmental rates of intact of free zona pellucida of bisected embryos by micromainipulator and micropipettes were 33.3 and 26.7%, respectively. The survival rate of bisection embryos was significantly lower than that of non-bisection embryos(45.0%).

• East Asian Economic Review
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• 제24권1호
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• pp.61-87
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• 2020

Five diffusion models are estimated using three different foreign exchange rates to find an appropriate model for each. Daily spot exchange rates expressed as the prices of 1 euro, 1 British pound and 100 Japanese yen in US dollars, respectively denoted by USD/EUR, USD/GBP, and USD/100JPY, are used. The maximum likelihood estimation method is implemented after deriving an approximate log-transition density function (log-TDF) of the diffusion processes because the true log-TDF is unknown. Of the five models, the most general model is the best fit for the USD/GBP, and USD/100JPY exchange rates, but it is not the case for the case of USD/EUR. Although we could not find any evidence of the mean-reverting property for the USD/EUR exchange rate, the USD/GBP, and USD/100JPY exchange rates show the mean-reversion behavior. Interestingly, the volatility function of the USD/EUR exchange rate is increasing in the exchange rate while the volatility functions of the USD/GBP and USD/100Yen exchange rates have a U-shape. Our results reveal that more care has to be taken when determining a diffusion model for the exchange rate. The results also imply that we may have to use a more general diffusion model than those proposed in the literature when developing economic theories for the behavior of the exchange rate and pricing foreign currency options or derivatives.

• 한국수정란이식학회지
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• 제10권1호
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• pp.83-90
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• 1995

Production of calves after transfer of nuclear transplant embryos is the latest technology to be applied in commercial livestock breeding. The objective of this study was to establish an efficient procedure to produce offsprings from nuclear transplant embryos. The fusion rates (72.7% vs. 80.8%), cleavage rates (62.5% vs. 71.4%) and rates of development in vitro (12.0% vs. 15.2%) of nuclear transplant embryos were not significantly different between 30 and 40h maturation age of cytoplast. The in vivo and in vitro-derived embryos as nuclei donor were used in this system of bovine nuclear transplantation. Fusion rates of nuclear transplant embryos were not significantly different between in vivo and in vitro-derived embryos (73.0 and 79.2%, respectively). The percentage of embryos reaching the morulae or blastocysts were 21.8% for in vivo-derived embryos and 11.9% for in vitro-derived embryos (p<0.01). Pregnancy rates after embryo transfer of nuclear transplant embryos were not significantly different between in vivo and in vitro-derived embryos (45.9 and 40.5%, respectively). However, calving rates after embryo transfer of nuclear transplant embryos were significantly higher in the in vivo-derived embryos than in vitro (p<0.01). Further research for age of cytoplast and use of in vitro-derived embryos as nuclei donor is required in this system. In conclusion, these results clearly show that the use of in vitro-derived oocytes as recipient cytoplast can improve the nuclear transplant system for genetic progress in cattle.

• Clinical and Experimental Reproductive Medicine
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• 제25권3호
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• pp.299-304
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• 1998

Despite the rapid development of assisted reproductive technologies (ART) in recent years, implantation rates after replacement of embryos into the uterine cavity remains low. Several techniques such as culture conditions based on formulations of human tubal fluid and various ART techniques as GIFT, ZIFT, TET have been adopted in recent years to improve embryo viability in vitro and implantation rates. Also, coculture of human IVF-derived embryos have been used in an effort to increase the number of viable embryos following IVF and to improve synchrony between the developing embryo and the uterine environment. The aim of this study was to evaluate whether the use of co culture with autologous cumulus cells has a significant beneficial effect on the development of embryos in vitro and its relation to the pregnancy rates in 120 patients with previous failed IVF-ET from September, 1995 to January 1998. We obtained the results from which significant improvement in the quality of viable embryos were observed using a coculture system with autologous cumulus cells, but pregnancy rates in this group of patients did not differ from the rate in the standard IVF group during the same period. Our study shows that a simplified short-term coculture system with autologous cumulus cells may help rescue moderate quality embryos to cleave regularly.

• 한국패류학회지
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• 제13권2호
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• pp.203-210
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• 1997

As a prioiminary study on usage of metabolic charateristics of the indicator species for indirect estimation of environmental water quality, effects of environmental pollutants on survival, filtration and oxygen consumption rates in Corbicula aeana were investigated at 17$^{\circ}C$ and $25^{\circ}C$ in 10 day afrer treatmint of pollutants. In case of glucose and complex fertilizer, the survival rates of the clams were 100% without any relation to individual sizes and water temperatures. In small sizes at $25^{\circ}C$, the survival rates of the clams by NH$_{4}$CI concentration were shown 95% at 10 mg/1 and 15mg/1, and 90% at 20mg/1, respectively. But the survival rate was 95%at 20 mg/1 of NH$_{4}$CI concentration in small size at 17$^{\circ}C$. The higher filtration and oxygin consumption rates were shown in small size at higher water timperatures(over $25^{\circ}C$), and generally filtration and oxygen consumption rates decreased with increase of glucose, complex fertilizer and NH$_{4}$CI concentrations, respectively. In general, effects of filtration and oxygen consumption rates at NH$_{4}$CI concentrations were shown slightly larger than those of glucose and complex fertilizer.

• Computers and Concrete
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• 제20권3호
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• pp.339-350
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• 2017

Dynamic behaviours of reinforced concrete (RC) bending beams subjected to monotonic loading with different loading rates were studied. A dynamic experiment was carried out with the electro-hydraulic servo system manufactured by MTS (Mechanical Testing and Simulation) Systems Corporation to study the effect of loading rates on the mechanical behaviours of RC beams. The monotonic displacement control loading, with loading rates of 0.1 mm/s, 0.5 mm/s, 1 mm/s, 5 mm/s and 10 mm/s, was imposed. According to the test results, the effects of loading rates on the failure model and load-displacement curve of RC beams were investigated. The influences of loading rates on the cracking, ultimate, yield and failure strengths and displacements, ductility and dissipated energy capability of RC beams were studied. Then, the three-dimensional finite element models of RC beams, with the rate-dependent DP (Drucker-Prager) model of concrete and three rate-dependent model of steel reinforcement, were described and verified using the experimental results. Finally, the dynamic mechanical behaviours and deformation behaviours of the numerical results were compared with those of the experimental results.

• 한국컴퓨터정보학회논문지
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• 제25권7호
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• pp.39-46
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• 2020

최근, 대전 게임 분야에서, 가상 캐릭터들의 효과적인 설계를 위해 캐릭터의 승률을 효율적으로 예측할 수 있는 방법들이 매우 필요하다. 우리는 본 논문에서 이 문제를 해결하기 위해 시뮬레이션과 기계 학습을 결합하는 방법을 제안한다. 우선 대전 게임에서 가상 캐릭터의 대전 승률을 분석하기 위해서 시뮬레이션을 사용하고, 가상 캐릭터의 능력치에 따라서 승률을 예측하기 위해 회귀 모델에 기반한 기계 학습 기법을 적용한다. 제안한 기법으로 실험한 결과는 시뮬레이션 결과로 나온 승률과 기계 학습 기법이 예측한 승률이 거의 차이가 없다는 것을 확인하였다. 그리고 간단한 회귀 모델에 기반한 기계 학습으로도 실험에서 좋은 성능을 얻을 수 있었다.