• Communications for Statistical Applications and Methods
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• 제7권1호
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• pp.107-118
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• 2000

Due to the close relation between cointegration test and multiple unit roots test multiple unit roots test are greatly studied by many researchers,. In this paper we suggest the symmetric type unit roots test which is an adjusted method of Shin (1999) Also we have a small Monte-Carlo simulation study to compare the power of the statistic developed in this paper with those of Shin (1999) and adjusted Fuller statistic(1996)

• Journal of the Korean Statistical Society
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• 제23권1호
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• pp.167-178
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• 1994

To estimate coefficient matrix in autoregressive model, usually ordinary least squares estimator or unconditional maximum likelihood estimator is used. It is unknown that for univariate AR(p) model, unconditional maximum likelihood estimator gives better power property that ordinary least squares estimator in testing for unit root with mean estimated. When autoregressive model contains multiple unit roots and unconditional likelihood function is used to estimate coefficient matrix, the seperation of nonstationary part and stationary part of the eigen-values in the estimated coefficient matrix in the limit is developed. This asymptotic property may give an idea to test for multiple unit roots.

• Journal of the Korean Statistical Society
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• 제28권1호
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• pp.45-55
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• 1999

Knowing the number of unit roots is important in the analysis of k-dimensional multivariate autoregressive process. In this paper we suggest simple multiple unit roots test statistics based on least squares estimator for the multivariate AR(1) process in which some eigenvalues are one and the rest are less than one in magnitude. The empirical distributions are tabulated for suggested test statistics. We have small Monte-Calro studies to compare the powers of the test statistics suggested by Johansen(1988) and in this paper.

• 충청수학회지
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• 제26권3호
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• pp.657-669
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• 2013

A general class of two-point optimal fourth-order methods is proposed for locating multiple roots of a nonlinear equation. We investigate convergence analysis and computational properties for the family. Special and simple cases are considered for real-life applications. Numerical experiments strongly verify the convergence behavior and the developed theory.

• 응용통계연구
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• 제7권1호
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• pp.103-112
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• 1994

본 논문에서는 비정상(단위근) 시계열이 포함된 다변량 시계열 자료에서 단위근에 해당되는 계수행렬 추정량의 극한 분포가 정상시계열의 유무에 상관없이 일정하다는 것을 밝혔다. 또한 단위근만 존재하는 다변량 시계열에서 다중단위근을 검정하는 검정통계량을 제안하였다.

• Communications for Statistical Applications and Methods
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• 제15권5호
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• pp.719-726
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• 2008

In this paper we consider a joint test for seasonal cointegrating(CI) ranks that enables us to simultaneously model cointegrated structures across seasonal unit roots in seasonal cointegration. A CI rank test for a single seasonal unit root is constructed and extended to a joint test for multiple seasonal unit roots. Their asymptotic distributions and selected critical values for the joint test are obtained. Through a small Monte Carlo simulation study, we evaluate performances of the tests.

• Mycobiology
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• 제30권3호
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• pp.146-153
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• 2002

Two types of mycorrhizae, orchid(OM) and arbuscular mycorrhizae(AM), were observed in the cortical cells of Botrychium ternatum roots. The vesicles or arbuscules of AM fungi were examined and the fresh or digestive pelotons by other species of basidiomycetes were also observed in the roots under light microscope. These symbioses were, as the genomic DNAs extracted from roots of B. ternatum reacted with the specific primers, confirmed with PCR technique, being added to more strong evidences. These discoveries were rarely happened in the roots, especially a fern in nature. OM was observed in the roots of B. ternatum collected from the nationwide areas, whereas AM was only in the roots of B. ternatum collected from Chung-Buk areas. It is speculated that OM are associated with the nitrogen cycle in Islands and the growth of B. ternatum in the inland of Central Korea is related to both the phosphate and nitrogen cycle in the nature. The results suggest that B. ternatum is a typical species with two types of mycorrhizae under various growing conditions.

• Mycobiology
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• 제31권4호
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• pp.196-199
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• 2003

A very reliable and specific method for the identification of fungi in ectotrophic mycorrhizal symbiosis was developed using a specific PCR assay based on the amplification of the ITS1 region. To obtain specific data, an ITS-diagnostic assay was carried out that reveals genera and species specific sequences. Here, an application of one method is presented, which covers the identification of pure mycelia, basidiocarps as well as mixed samples such as ectomycorrhizal roots that were mingled with remains of the host plant. For this purpose a protocol was established that allowed the extraction of DNA from single mycorrhizal roots. In order to perform a specific ITS analysis we generated a new ITS-primer(ITS8) by a multiple alignment of five different genera and species of mycorrhizal fungi. The utilization of ITS1 and ITS8 resulted in specific PCR amplicons, which were characterized by sequencing without purification steps, even when the template DNA was associated with roots.

• 대한수학회논문집
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• 제20권2호
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• pp.247-257
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• 2005

In this paper we calculate two special types of multiple zeta values, $\zeta(\{4\iota+2\}_n)\;and\;\zeta(\{4\iota\}_n)$ using the primitive roots of unity, which may be simpler and easier.

• Journal of Plant Biotechnology
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• 제8권1호
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• pp.37-41
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• 2006

In vitro mass multiplication of Vanilla planifolia was investigated using node as explant. Multiple shoots were developed in MS medium supplemented with $2.0mgl^{-1}$ 6-benzylaminopurine and $1.0mgl^{-1}$ $\alpha$-naphthalene acetic acid. Multiple shoots were maintained for 6-T weeks with regular subculturing at the end of $3^{rd}$ week onto fresh medium. The maximum number of shoots at the rate of 12.8 per node segment was achieved over a period of four weeks. The elongated shoots were separated from the shoot clusters and were transferred onto half strength MS medium supplemented with indole-3-acetic acid ($1.0mgl^{-1}$) over a period of 28 days for induction of roots. The development of roots was observed on $7^{th}$ day of incubation. The in vitro raised plantlets were transferred to poly-cups, covered with polyethylene sheets and maintained under shade net for 25 days for hardening. Finally these plants were transferred to field and recorded that 85 % of tissue cultured plants were survived. From the present study, a simple and efficient micropropagation protocol was developed for Vanilla planifolia using single node segments as explants.