• Journal of the Korean Statistical Society
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• 제27권3호
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• pp.265-278
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• 1998

In this paper, we suggest two-phase adaptive cluster sampling schemes. The main feature of the two-phase sampling is that the information collected in the first phase sample is utilized in the selection of the second phase sample. The conventional two-phase sampling is, however, not sufficient to increase efficiency when the population of interest is rare and clustered. In the proposed sampling scheme, the first phase sample is selected with adaptive cluster sampling procedure and the second phase sample is selected by PPSWR and $\pi$PS sampling. We investigate unbiased estimators of population total and their variance for the proposed sampling schemes respectively. Finally we compare these suggested sampling schemes using numerical examples .

• Communications for Statistical Applications and Methods
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• 제9권2호
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• pp.479-489
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• 2002

The case which applies two-phase sampling to stratification and nonresponse problem, it is a poweful and effective technique. In this paper we study the calibration estimator and its variance estimator for the population total using two-phase sampling method according to the of auxiliary information for population and sample having strong correlation with an interested variable in unit nonresponse situation. The auxiliary information that available both at first-phase and second-phase sampling can be used to improve weights by the calibration procedure. A weight which corresponds to the product of sampling weights and response probability is calculated at each phase of sampling.

• Journal of the Korean Physical Society
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• 제73권9호
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• pp.1219-1224
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• 2018

We investigate the evolutionary dynamics and the phase transitions of the island model which consists of subdivided populations of individuals confined to two islands. In the island model, the population is subdivided so that migration acts to determine the evolutionary dynamics along with selection and genetic drift. The individuals are assumed to be haploid and to be one of two species, X or Y. They reproduce according to their fitness values, die at random, and migrate between the islands. The evolutionary dynamics of an individual based model is formulated in terms of a master equation and is approximated by using the diffusion method as the multidimensional Fokker-Planck equation (FPE) and the coupled non-linear stochastic differential equations (SDEs) with multiplicative noise. We analyze the infinite population limit to find the phase transitions from the monomorphic state of one type to the polymorphic state to the monomorphic state of the other type as we vary the ratio of the fitness values in two islands and complete the phase diagram of our island model.

• Communications for Statistical Applications and Methods
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• 제17권2호
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• pp.165-181
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• 2010

This paper presents some chain ratio-type estimators for estimating finite population variance using two auxiliary variables in two phase sampling set up. The expressions for biases and mean squared errors of the suggested c1asses of estimators are given. Asymptotic optimum estimators(AOE's) in each class are identified with their approximate mean squared error formulae. The theoretical and empirical properties of the suggested classes of estimators are investigated. In the simulation study, we took a real dataset related to pulmonary disease available on the CD with the book by Rosner, (2005).

• The Plant Pathology Journal
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• 제31권1호
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• pp.33-40
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• 2015

Pigeonpea Sterility Mosaic Disease (PSMD) is an important foliar disease caused by Pigeonpea sterility mosaic virus (PPSMV) which is transmitted by eriophyid mites (Aceria cajani Channabasavanna). In present study, a F2 mapping population comprising 325 individuals was developed by crossing PSMD susceptible genotype (Gullyal white) and PSMD resistant genotype (BSMR 736). We identified a set of 32 out of 300 short decamer random DNA markers that showed polymorphism between Gullyal white and BSMR 736 parents. Among them, eleven DNA markers showed polymorphism including coupling and repulsion phase type of polymorphism across the parents. Bulked Segregant Analysis (BSA), revealed that the DNA marker, IABTPPN7, produced a single coupling phase marker (IABTPPN $7_{414}$) and a repulsion phase marker (IABTPPN $7_{983}$) co-segregating with PSMD reaction. Screening of 325 F2 population using IABTPPN7 revealed that the repulsion phase marker, IABTPPN $7_{983}$, was co-segregating with the PSMD responsive SV1 at a distance of 23.9 cM for Bidar PPSMV isolate. On the other hand, the coupling phase marker IABTPPN $7_{414}$ did not show any linkage with PSMD resistance. Additionally, single marker analysis both IABTPPN $7_{983}$ (P<0.0001) and IABTPPN $7_{414}$ (P<0.0001) recorded a significant association with the PSMD resistance and explained a phenotypic variance of 31 and 36% respectively in $F_2$ population. The repulsion phase marker, IABTPPN7983, could be of use in Marker-Assisted Selection (MAS) in the PPSMV resistance breeding programmes of pigeonpea.

• 응용통계연구
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• 제22권2호
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• pp.387-402
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• 2009

In this paper we have considered the problem of estimating the population mean $\bar{Y}$ of the study variable y using auxiliary information in presence of non-response. Classes of estimators for $\bar{Y}$ in the presence of non-response on the study variable y only and complete response on the auxiliary variable x is available, have been proposed in different situations viz., (i) population mean $\bar{X}$ is known, (ii) when population mean $\bar{X}$ and variance $S^2_x$ are known; (iii) when population mean $\bar{X}$ is not known: and (iv) when both population mean $\bar{X}$ and variance $S^2_x$ are not known: single and two-phase (or double) sampling. It has been shown that various estimators including usual unbiased estimator and the estimators reported by Rao (1986), Khare and Srivastava (1993, 1995) and Tabasum and Khan (2006) are members of the proposed classes of estimators. The optimum values of the first phase sample size n', second phase sample size n and the sub sampling fraction 1/k have been obtained for the fixed cost and the fixed precision. To illustrate foregoing, we have carried out an empirical investigation to reflect the relative performance of all the potentially competing estimators including the one due to Hansen and Hurwitz (1946) estimator, Rao (1986) estimator, Khare and Srivastava (1993, 1995) and Tabasum and Khan (2006) estimator.

• 한국광학회지
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• 제8권5호
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• pp.357-361
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• 1997

밀도반전된 Nd:YAG에서 자체 교차하는 빔경로를 구성하여 위상공액파 레이저를 발진 시켰다. 서로 교차하는 두빔에 의한 spatial hole burning에 의해 3차 비선형 분극이 유도되어 레이저 공진기 내부의 위상 왜곡(phase distortion)이 자체 보정됨을 관측하였고, 레이저 이득체내에서 형성되는 동적 부피 격자의 생성과 소멸에 의한 효과로 반치폭 20 나노초의 자연 Q-switched 레이저 펄스가 발진되었다. 평균 펄스당 출력 에너지는 10 Hz 동작에서 200 mJ로 측정되었으며, 최대 전체 출력 효율은 0.8%로 나타났다.

• 한국통신학회논문지
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• 제24권9A호
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• pp.1425-1433
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• 1999

본 논문은 ETSI에 의해 정의된 무선 LAN(Wireless LAN)의 표준안인 HIPERLAN(HIgh PErformance Radio LAN) 타입 1의 매체 접근 제어 프로토콜에 관하여 해석적으로 분석한다. HIPERLAN의 채널 접근 계층(Channel Access Control layer)에서 사용하는 EY-NPMA(Elimination Yield-Nonpreemptive Priority Multiple Access)의 채널 경쟁 단계 중에서 제어 단계(Elimination phase)와 양보 단계(Yield phase)의 무선 가입자 모델에 대하여 분석한다. 그리고, 분석 결과를 이용하여 전송 단계(Transmission phase)에서 패킷 전송의 성공확률을 해석적으로 구한 후, 시뮬레이션을 이용한 성능 평가를 통하여 분석 결과를 검증한다.

• 한국응용곤충학회지
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• 제42권4호
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• pp.367-381
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• 2003

곤충의 분산다형성이란 비상능력과 관련된 다형성으로 그 구체적 내용으로는 시다형성, 비상근다형성 그리고 비상행동변이성 등과 이들과는 별개로 개체군 밀도의존적인 상변이성이 있다. 분산다형성은 시간적으로나 공간적으로 이질적인 서식처 환경에 대응하기 위하여 이동형인 “유시형이나 장시형”과 정주형인 “무시형이나 단시형”을 생활사에 적절히 짜넣은 적응적 형질이다. 점변태곤충류에서는 유충과 성충의 생태학적지위가 중복되여 있어 유충과 성충이 생활공간과 그 밖의 요구조건을 달리하고 있는 완전변태류나 반변태류에 비하여 분산다형성의 예가 대단히 많다. 무시형 또는 단시형곤충은 같은 종의 유시형 또는 장시형곤충에 비하면 초산연령이 빠르고 총산란수도 많은 것이 보통이여서 자연증가율(r)이 크다. 단시형과 관련된 환경요인으로는 서식처의 시간적 영속성이나 공간적 이질성, 먹이조건, 개체군밀도, 온도, 일장 기타 여러 가지가 알려지고 있다 서식처의 환경조건에 대한 분산다형성발현상은 종에 따라 다를 뿐 아니라 암수간에도 차가 있고 같은 종에서도 계통간에 차가 있는 극히 탄력적인 현상이다. 분산다형성의 문제는 생리학, 유전학 그리고 생태학등에 걸친 폭넓은 학문분야로 특히 생태유전학이나 정량유전학분야치 연구는 분산다형성의 유전적본질 구명에 중요하다 하겠다.

• 한국임상약학회지
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• 제26권4호
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• pp.312-317
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• 2016

Objective: Midazolam is mainly metabolized by cytochrome P450 (CYP) 3A. Inhibition or induction of CYP3A can affect the pharmacological activity of midazolam. The aims of this study were to develop a population pharmacokinetic (PK) model and evaluate the effect of CYP3A-mediated interactions among ketoconazole, rifampicin, and midazolam. Methods: Three-treatment, three-period, crossover study was conducted in 24 healthy male subjects. Each subject received 1 mg midazolam (control), 1 mg midazolam after pretreatment with 400 mg ketoconazole once daily for 4 days (CYP3A inhibition phase), and 2.5 mg midazolam after pretreatment with 600 mg rifampicin once daily for 10 days (CYP3A induction phase). The population PK analysis was performed using a nonlinear mixed effect model ($NONMEM^{(R)}$ 7.2) based on plasma midazolam concentrations. The PK model was developed, and the first-order conditional estimation with interaction was applied for the model run. A three-compartment model with first-order elimination described the PK. The influence of ketoconazole and rifampicin, CYP3A5 genotype, and demographic characteristics on PK parameters was examined. Goodness-of-fit (GOF) diagnostics and visual predictive checks, as well as bootstrap were used to evaluate the adequacy of the model fit and predictions. Results: Twenty-four subjects contributed to 900 midazolam concentrations. The final parameter estimates (% relative standard error, RSE) were as follows; clearance (CL), 31.8 L/h (6.0%); inter-compartmental clearance (Q) 2, 36.4 L/h (9.7%); Q3, 7.37 L/h (12.0%), volume of distribution (V) 1, 70.7 L (3.6%), V2, 32.9 L (8.8%); and V3, 44.4 L (6.7%). The midazolam CL decreased and increased to 32.5 and 199.9% in the inhibition and induction phases, respectively, compared to that in control phase. Conclusion: A PK model for midazolam co-treatment with ketoconazole and rifampicin was developed using data of healthy volunteers, and the subject's CYP3A status influenced the midazolam PK parameters. Therefore, a population PK model with enzyme-mediated drug interactions may be useful for quantitatively predicting PK alterations.