• Journal of Radiation Protection and Research
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• 제16권1호
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• pp.53-72
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• 1991

An integrated model is developed in this paper for the performance assessment of high level radioactive waste repository. This integrated model consists of two simple mathematical models. One is a multiple-barrier failure model of the repository system based on constant failure rates which provides source terms to biosphere. The other is a biosphere model which has multiple pathways for radionuclides to reach to human. For the parametric uncertainty and sensitivity analysis for the risk assessment of high level radioactive waste repository, Latin hypercube sampling and rank correlation techniques are applied to this model. The former is cost-effective for large computer programs because it gives smaller error in estimating output distribution even with smaller number of runs compared to crude Monte Carlo technique. The latter is good for generating dependence structure among samples of input parameters. It is also used to find out the most sensitive, or important, parameter groups among given input parameters. The methodology of the mathematical modelling with statistical analysis will provide useful insights to the decision-making of radioactive waste repository selection and future researches related to uncertain and sensitive input parameters.

• 한국물환경학회지
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• 제26권5호
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• pp.781-788
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• 2010

A pilot study was performed to examine the feasibility of multiple stage of constructed wetland (CW) for nutrient removal. The system is composed of six wetland cells connected with water-ways. The hydraulic of wetland cells is designed as free water surface flow. The treatment capacity was $25m^3d^{-1}$ at HRT of about one day for each cell. The magnitude of nutrient removal was related with the length of wetlands and plant density. Total N and P removal rates were 1353 and $246mg\;m^{-2}d^{-1}$ respectively. The pilot-scale reactor was model as continuous flow system containing contribution of CSTR and PFR typed-reactors. The $k-C^*$ model equation was applied to predict N and P reduction. The result indicated the equation was well guided to estimate reduction of $NO_3-N$ and $PO_4-P$.

• 한국수정란이식학회지
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• 제13권2호
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• pp.127-137
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• 1998

This experiment was carried out to investigate the factors affecting superovulation in rabbits and to determine the effect of pFSH and PMSG on ovarian superovulatory responses and embryo production, and the effect of superovulation treatment with a single injection of pFSH dissolved in polyvinylpyrrolidone on the ovarian responses and the embryo quality. The results obtained were suonmerized as follows: Superovulatory response resulted in significantly (P<0.05) higher ovulation rates and more embryos in spring or autumn, compared with summer or winter. Repeated superovulatory treatments with PMSG leaded to a significantly(P<0.05) decreased number of total follicles and recovered ova. Superovulation with pFSH resulted in the higher number of ovulated follicles and recovered ova than with PMSG. A single subcutaneous injection of pFSH dissolved in 25% PVP resulted in the more ovulation points(33.2) and recovered embryos(30.2), which were comparable to the multiple injections of pFSH(44.8 vs 37.7).These results indicated that the treatment with a single injection of FSH dissolved in PVP was an efficient and simple alternative method to the conventional multiple FSH injections for superovulation in rabbits.

• Journal of Microbiology and Biotechnology
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• 제13권6호
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• pp.1001-1007
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• 2003

Metal ions contamination may inhibit microorganisms involved in the biodegradation of organic compounds and affect biodegradation rates. Therefore, it is likely that bioremediation of xenobiotics-contaminated soils and waste will require inoculation with efficient biodegrading microbial communities, with capabilities of being resistant to heavy metals as well. Two different transconjugants (Pseudomonas sp. KMl2TC and P. aeruginosa TC) were constructed by conjugation experiments. Results on MIC, induction and growth inhibition strongly indicated that arsenic-resistant plasmid, pKM20, could be mobilized, and the newly acquired phenotype of pKM20 was not only expressed but also well regulated, resulting in newly acquired resistances to $As^{5+},\;As^{3+},\;and\;Sb^{3+} in\;addition\;to\;Cd^{2+},\;Zn^{2+},\;and\;Hg^{2+}$. The phenol- degradation efficiencies of Pseudomonas sp. KMl2TC were maintained significantly even at high heavy metal concentrations at which these efficiencies of P. aeruginosa TC were completely impaired. The results in this study on the effects of heavy metals on phenol degradation, especially after conjugation, are the first ever reported. All the results described in this study encourage to establish a goal of making "designer biocatalysts" which could degrade certain xenobiotics in the area contaminated with multiple heavy metals.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권11호
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• pp.5410-5426
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• 2019

With the advent of the fifth-generation (5G) era, Massive multiple-input multiple-output (MIMO) relay systems have experienced the rapid development. Recently, the performance analysis models of Massive MIMO relay systems have been proposed, which are mostly based on Rayleigh fading channels. In order to create a more suitable model for 5G Internet of Things scenarios, our study is based on the Rician fading channels, where line-of-sight (LOS) path exists in the channels. In this paper, we assume the channel state information (CSI) is perfect. In this case, we use statistical information to derive the analytical exact closed-form expression for the achievable sum rate of the uplink for the Massive MIMO two-hop relay system over Rician fading channels. Moreover, considering the different communication scenarios, we derive the analytical exact closed-form expression for the achievable sum rates of the uplink for other three scenarios. Finally, based on these expressions, we make simulations and analyze the performance under different transmit powers and Rician-factors, which provides a theoretical basis and reference for further research.

• Clinical and Experimental Pediatrics
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• 제54권11호
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• pp.429-435
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• 2011

Although Korean population has been growing steadily during the past four decades, the nation is rapidly becoming an aging society because of its declining birth rate combined with an increasing life expectancy. In addition, Korea has one of the lowest fertility rates in the world due to fewer married couples, advanced maternal age, and falling birth rate. The prevalence of low birth weight infants and multiple births has been increased compared with the decrease in the birth rate. Moreover, the number of congenital anomalies is expected to increase due to the advanced maternal age. In addition, the number of interracial children is expected to increase due to the rise in the number of international marriages. However, the maternal education level is high, single-mother birth rate is low, and the gender imbalance has lessened. The number of overweight babies has been decreased, as more pregnant women are receiving adequate prenatal care. Compared to the Asian average birth weight, the average birth weight is the highest in Asia. Moreover, the rate of low birth weight infants is low, and infant mortality is similarly low across Asia. Using birth data from Statistics Korea and studies of birth outcomes in Korea and abroad, this study aimed to assess the changes in maternal and infant characteristics associated with birth outcomes during the past four decades and identify necessary information infrastructures to study countermeasures the decrease in birth rate and increase in low birth weight infants in Korea.

• 한국위성정보통신학회논문지
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• 제10권2호
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• pp.102-108
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• 2015

일반적으로 TDMA(Time Division Multiple Access)를 기반으로 하는 양방향 위성 통신 시스템에서는 중심국과 멀리 떨어진 단말국간의 네트워크 동기를 필요로 한다. 본 논문은 양방향 위성시스템을 위한 국제규격인 DVB-S2/RCS2에서 제시한 NCR(Network Clock Reference) 복원 구조를 기반으로 네트워크 클럭 동기에 대한 개념을 설명한다. 또한 DVB-S2에서 CCM(Constant Coding & Modulation) 운용 모드와 부호율, 변조방식을 바꿔 throughput을 최적화 하는 ACM(Adaptive Coding & Modulation) 운용 모드를 지원하는 새로운 NCR 삽입 구조를 제안하였으며 이에 대한 시뮬레이션을 통해 타당성을 검증하였다.

• 한국통신학회논문지
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• 제31권3C
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• pp.228-236
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• 2006

다중 반송파(MC)기술과 CDMA기술이 결합된 MC-CDMA 시스템은 주파수 선택적 페이딩에 의한 신호감쇄를 완화시키면서 높은 전송률에 대한 요구를 만족시킬 수 있는 전송방식이다. 본 논문에서는 전송률이 서로 다른 다양한 서비스들을 지원하기 위한 비동기 MC-CDMA 시스템을 제안하고 다중간섭제거기를 적용한 시스템의 성능을 분석한다. 제안된 시스템에서는 전송속도에 따라 병렬 부 채널의 수(P)를 조절함으로서 다중전송률 MC-CDMA 시스템을 구성하였으며 효과적인 다중접속 간섭제거를 위해 하이브리드 간섭제거(HIC) 방식을 사용한다. 다중경로 환경 하에서 단일전송률을 갖는 시스템과 제안된 시스템의 성능을 분석하였으며 간섭제거기를 사용하여 성능이 향상됨을 보였다.

• The Journal of the Acoustical Society of Korea
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• 제20권2E호
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• pp.17-24
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• 2001

In this paper, we propose the bootstrap and aggregating (bagging) vector quantization (VQ) classifier to improve the performance of the text-independent speaker recognition system. This method generates multiple training data sets by resampling the original training data set, constructs the corresponding VQ classifiers, and then integrates the multiple VQ classifiers into a single classifier by voting. The bagging method has been proven to greatly improve the performance of unstable classifiers. Through two different experiments, this paper shows that the VQ classifier is unstable. In one of these experiments, the bias and variance of a VQ classifier are computed with a waveform database. The variance of the VQ classifier is compared with that of the classification and regression tree (CART) classifier[1]. The variance of the VQ classifier is shown to be as large as that of the CART classifier. The other experiment involves speaker recognition. The speaker recognition rates vary significantly by the minor changes in the training data set. The speaker recognition experiments involving a closed set, text-independent and speaker identification are performed with the TIMIT database to compare the performance of the bagging VQ classifier with that of the conventional VQ classifier. The bagging VQ classifier yields improved performance over the conventional VQ classifier. It also outperforms the conventional VQ classifier in small training data set problems.

• 한국통신학회논문지
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• 제17권7호
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• pp.719-729
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• 1992

본 논문은 레이다 목표물 검파에 유용한 MXTM(maximum trmmed mea)-CFAR(constant false alarm rate) 처리기를 제안하고, 성능분석을 통하여 기존의 CFAR 처리기와 비교하였다. 제안된 MXTM-CFAR처리기는 클러터경계에서 좋은 성능을 갖는 GO(greatest of)-CFAR 처리기와 균질 또는 비균질상황에서 좋은 성능을 갖는 기존의 순서통계에 근거한 TM-CFAR 처리기를 결합한 형태이다. 균질상황, 간섭표적상화 및 클러터경계에서 구한 검파확률, 오경보율과 임계치를 통하여 성능을 분석하고 기존의 CFAR 처리기와 비교하였다. 제안된 처리기는 균질상황과 간섭표적상화에서 OS(order statistics)및 TM-CFAR 처리기와 같은 성능을 유지하면서 클러터 경계에서 오경보율을 줄일 수 있어으며 처리시간을 단축 시킬 수 있었다.