• Atmosphere
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• v.25 no.2
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• pp.205-219
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• 2015

In this study, the simulation results of temperature by regional climate model (Reg- CM4) over South Korea were corrected by Hempel et al. (2013)'s method (Hempel method), and evaluated with the observation data of 50 stations from Korea Meteorological Administration. Among the 30 years (1981~2010) of simulation data, 20 years (1981~2000) of simulation data were used as a training data, and the remnant 10 years (2001~2010) data were used for the evaluation of correction. In general, the Hempel method and parametric quantile mapping show a reasonable correction both in mean and extreme climate of temperature. As the results, the systematic underestimation of mean temperature was greatly reduced after bias correction by Hempel method. And the overestimation of extreme climate, such as the number of TN5% and freezing day, was significantly recovered. In addition to that, the Hempel method better preserved the temporal trend of simulated temperature than other bias correction methods, such as the quantile mapping. However, the overcorrection of the extreme climate related to the upper quantile, such as TX5% and hot days, resulted in the exaggeration of the simulation errors. In general, the Hempel method can reduce the systematic biases embedded in the simulation results preserving the temporal trend but it tends to overcorrect the non-linear biases, in particular, extreme climate related to the upper percentile.

• Korean Journal of Logic
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• v.22 no.3
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• pp.351-395
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• 2019

Hempel's original intuitions about the raven's paradox are summed up in three ways. The first is known as the paradoxical conclusion: If one observes that an object a - about which nothing is antecedently known - is a non-black non-raven, then this observation confirms that all ravens are black. The second is an intuitive verdict of the misled conclusion of the paradox: If one observes that an object a - which is known to be a non-raven - is non-black (hence, is a non-black non-raven), then this observation does not confirmationally affect that all ravens are black. The third is a comparative claim between the two intuitions: the degree of confirmation appearing in the first intuition is greater than the degree of confirmation in the second intuition. The Standard Bayesian Solution of the paradox is evaluated to fleshed Hempel's intuitions out by establishing the first intuition. However, such an evaluation of this solution should be further analyzed because Hempel's intuition is not the only one. The solution of paradox does not establish the second intuition in a strict sense. However, I think the Bayesian solution will establish the second intuition based on its typical strategy of quantitative vindication. If only quantitative vindication is accepted, this evaluation of the solution remains valid. Nevertheless, the solution fails to establish the third intuition. In this article, I propose a new way to apply the Bayesian method to establish Hempel's intuitions, including the third intuition. If my analysis is correct, the Standard Bayesian Solution of the raven's paradox could indeed flesh Hempel's intuitions out by denying one of the assumptions considered essential.

• Korean Journal of Logic
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• v.20 no.3
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• pp.367-390
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• 2017

Much of literature on the paradoxes of confirmation has been focused on the problems raised by the fact that a nonblack nonraven confirms the hypothesis that every raven is black. In this paper I would like to emphasize that more interesting problems are still waiting to be explained, if we notice that a black nonraven confirms the raven hypothesis as well. For this I examine what Hempel exactly means by the paradoxes of confirmation, and show that the previous discussions on the paradoxes were at most partial solutions. Then I argue that Hempel presupposes the so-called 'converse consequence condition' regarding confirmational evidence. Finally I discuss what impact is made on the Bayesian solution to the paradoxes, if we accept a more faithful interpretation to Hempel.

• Bulletin of the Korean Mathematical Society
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• v.56 no.2
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• pp.515-520
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• 2019

We give new evidence that "complicated" Heegaard surfaces behave like incompressible surfaces. More precisely, suppose that a closed connected orientable 3-manifold M contains a closed connected incompressible surface F which separates M into two (connected) components $M_1$ and $M_2$. Let S be a Heegaard surface of M. Our result is that if the Hempel distance of S is at least four, then S is isotoped so that $S{\cap}M_i$ is incompressible for each i = 1, 2.

• Bulletin of the Korean Chemical Society
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• v.28 no.6
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• pp.1035-1038
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• 2007

• Bulletin of the Korean Mathematical Society
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• v.52 no.3
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• pp.735-740
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• 2015

Tomova [8] gave an upper bound for the distance of a bridge surface for a knot with two different bridge positions in a 3-manifold. In this paper, we show that the result of Tomova [8, Theorem 10.3] can be improved in the case when there are two different bridge spheres for a link in $S^3$.

• Animal cells and systems
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• v.13 no.2
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• pp.187-203
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• 2009

Neustonic calanoid copepods were collected at the South Sea of Korea using a David-Hempel neuston net. Four Pantel/apsis species (P. armata Giesbrecht, P. rega/is Dana, P. vil/asa Brady and P. yamadae Mori) were identified and the former three species were first recorded in the Korea. We present redescription of the four species with SEM micrographs of female genitalia. Female genital structure is species-specific and can be very useful for species classification in the genus Pantel/apsis. Also we discuss zoogeography of Pantel/apsis species and provide with a key to the species hitherto known in the Korean waters.

• Ocean Science Journal
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• v.43 no.4
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• pp.209-222
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• 2008

To understand physical structures in the Korean waters, we investigated the spatio-temporal distribution of Pontella species known as indicator species of water mass using a David-Hempel neuston net from April 2002 to March 2003. Five Pontella species (P. chierchiae Giesbrecht, P. fera Dana, P. latifurca Chen and Zhang, P. securifer Brady and P. sinica Chen and Zhang) were found. Their abundance increased from May to October with increasing the surface water temperature. Pontella chierchiae predominantly appeared in the whole areas while P. latifurca scarcely occurred in coastal waters. The other three species (P. fera, P. securifer and P. sinica) were rarely found in the South Sea of Korea on August to September. We suggest that P. securifer and P. fera as oceanic species can play a role in an indicator species of the Tsushima Warm Current while P. sinica as Chinese coastal species is affected by the diluted waters of the Yantze River. We also provide re-description of the three species (P. chierchiae, P. fera and P. latifurca) insufficiently described and discuss their zoogeography.

• Journal of Communications and Networks
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• v.6 no.1
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• pp.9-18
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• 2004

Self-encoded multiple access (SEMA) is a unique realization of random spread spectrum. As the term implies, the spreading code is obtained from the random digital information source instead of the traditional pseudo noise (PN) code generators. The time-varying random codes can provide additional security in wireless communications. Multi-rate transmissions or multi-level grade of services are also easily implementable in SEMA. In this paper, we analyze the performance of SEMA in additive white Gaussian noise (AWGN) channels and Rayleigh fading channels. Differential encoding eliminates the BER effect of error propagations due to receiver detection errors. The performance of SEMA approaches the random spread spectrum discussed in literature at high signal to noise ratios. For performance improvement, we employ multiuser detection and Turbo coding. We consider a downlink synchronous system such as base station to mobile communication though the analysis can be extended to uplink communications.

• The Korean Journal of Applied Statistics
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• v.32 no.1
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• pp.99-109
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• 2019

We compared the confidence intervals of estimators using various bootstrap methods for a Random Coefficient Autoregressive(RCA) model. We consider a Quasi score estimator and M-Quasi score estimator using Huber, Tukey, Andrew and Hempel functions as bounded functions, that do not have required assumption of distribution. A standard bootstrap method, percentile bootstrap method, studentized bootstrap method and hybrid bootstrap method were proposed for the estimations, respectively. In a simulation study, we compared the asymptotic confidence intervals of the Quasi score and M-Quasi score estimator with the bootstrap confidence intervals using the four bootstrap methods when the underlying distribution of the error term of the RCA model follows the normal distribution, the contaminated normal distribution and the double exponential distribution, respectively.