• The Korean Journal of Applied Statistics
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• v.35 no.3
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• pp.357-370
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• 2022

In this paper, Tobit and Heckit models are introduced. These models have been used for analyzing censored data. Censoring occurs at a specific point and a large number of observations are distributed with a positive probability at a certain point. Censoring can occur due to observing limitation or exogenous variables. Tobit and Heckit models are used to correct sample selection bias, which can occur when an ordinary linear regression model is fitted to censored data. However, the difference between the two models is not clearly accounted for; hence, they have often been used interchangeably. Therefore, the suitability of the models was validated through simulated data, and demonstrated through real data. As the result, it was confirmed that both Tobit and Heckit models are well-fitted to the data censored due to observing limitation, although Tobit model was fitted parsimoniously. In contrast, only Heckit model is well-fitted to the data censored due to exogenous variables.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.22 no.6
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• pp.17-31
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• 2023

An activity-based model requires detailed population information to model individual travel behavior in a disaggregated manner. The recent innovative approach developed deep generative models with novel regularization terms that improves fidelity and diversity for population synthesis. Since the method relies on measuring the distance between distribution boundaries of the sample data and the generated sample, it is crucial to obtain well-defined continuous representation from the discretized dataset. Therefore, we propose an improved entity embedding models to enhance the performance of the regularization terms, which indirectly supports the synthesis in terms of feasible and diverse populations. Our results show a 28.87% improvement in the F1 score compared to the baseline method.

• The Korean Journal of Malacology
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• v.18 no.2
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• pp.83-91
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• 2002

Reproductive cycle of natural population and artificial control experiments of gonadal development by the conditions of water temperatures-feeding and starvation of Ruditapes philippinarum were investigated by histological observations. The reproductive cycle of natural population in females and males can be categorized into five successive stages; early active (February to March), late active (April to May), ripe (April to August), partially spawned (May to October), and spent-inactive stage (August to March). In the artificial control experiments, gonadal development of this species was inhibited by the low water temperature (10$^{\circ}C$). In the experimental group which was exposed to artificial high water temperatures of 19$^{\circ}C$ and 22$^{\circ}C$, gonadal development was accelerated by the higher water temperatures and was faster (about one month) than that in natural populations. In the high water temperatures-feeding experimental group, the gonadal developmental phase was faster in the small-size group than that in the large-size group, and was faster in lower water temperature (10$^{\circ}C$)(p=0.01). The gonad developmental phases in the high water temperature (22-28$^{\circ}C$)-starvation experimental group showed faster (paired sample t-test, p=0.004) than those in the high water temperature-feeding group in females and males. In the high water temperature-feeding experimental group of female and male gonadal developments of small sized group were more sensitive than those in large sized group after 42 days cultivation, However, the gonadal development of male was more sensitive to the lower water temperature than female. On the whole, sexual maturation in the high water temperature experimental group was faster than those in the low water temperature group, and showed a significant difference (paired sample t-test, p=0.001) between female and male. In the starvation experimental group after 42 days, gonadal developments in the high water temperature-large male group showed faster than those in the high water temperature-large female group. However, in small size, gonad developmental phases showed the same pattern between feeding and starvation experimental groups. During the main spawning season, in the high water temperature-starvation experimental groups in females and males, their gonadal development showed faster than that in higher water temperature-feeding experimental group regardless of their sexes and individual sizes and showed a significant difference (paired sample t-test, p=0.004).

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.8 no.4
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• pp.84-92
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• 2009

In this paper, using the received signal strength of radio beacon such as Wi-Fi, Bluetooth, CDMA and GPS signal from the satellite, we propose the system of positioning which considered indoor and outdoor based on the Place Lab. Conventional Place Lab utilize the various positioning parameters to estimate the indoor location. However, this conventional system has limitations with respect to the range and efficiency of usage. Therefore, we defined the converged model of multisensor data and re-organized the Place Lab to overcome the limitation of a conventional system. Proposed system uses the radio beacon signal and GPS signal together to estimate the location. Furthermore, it provides the seamless PNS service with many mobile devices because this system realized by the OSGi bundle. This proposed system has evaluated the performance with SAMSUNG T*OMNIA SCH-M490 smart phone and the result shows the system is able to support the PNS service.

• Korean Journal of Plant Taxonomy
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• v.41 no.1
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• pp.1-9
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• 2011

Artemisia capillaris Thunb. and A. scoparia Waldst. & Kit. are classified by their root shape, leaf size and capitulum size. However, these characteristics are not nearly as useful when attempting to identify the two species owing to the continuous variation in them. Another important taxonomic characteristics is the habit, whether it is the subshrubs or perennial herbs of A. capillaris Thunb. or the annual or biennial herbs of A. scoparia Waldst. & Kit.. All observed specimens and living individuals in Korea are subshrubs or perennial herbs, and annual or biennial examples are not found. Therefore, it is considered that A. scoparia Waldst. & Kit. is not distributed in Korea.

• The Korean Journal of Zoology
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• v.37 no.4
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• pp.545-553
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• 1994

척추동물의 초기 발생에 관여하는 물질로 알려져 있는 retinoic acid(RA)를 Xenopus 배(embryo)에 처리한 결과, 체절의 형성에 이상 발생이 나타났다 즉 낭배 초기에 RA에 노출된 개체의 체절은 대조군의 화살머리 모양((((() 대신 기등 모양(1111)을 형성하고 있었으며, 고농도일수록 직선에 가까운 모습을 하고 있었다. 신경배 시기에 노출된 개체의 체절은 정상적인 분절이 이루어지지 않았으며, 이들 이상 체질의 위치는 처리 시기에 따라 다르게 나타났으나 농도에는 영향을 받지 않았다. 그러나 분절 과정중 일어나는 체절 세포들의 회전은 RA에 의해 억제되지 않았다. 이와 같은 결과는 체절의 형성에 분절 이전의 세포의 행동을 주도하는 프로그램과 분절을 주도하는 프로그램이 분리되어 있음을 암시한다. 한 가지 특이한 사항은 열처리 등으로 유발된 혼란이 수 개의 체절에 국한되어 나타나는 점과는 달리 RA의 처리는 어느 지점 이 후부터 모든 체절에 혼란을 야기시킨다는 점이다. 이와 같은 연속적인 분절의 흔란 현상은 RA가 다른 저해제에 의해 영향을 받는 유전자의 활동을 조절하는 전 단계의 유전자에 영향을 주기 때문인 것으로 사료된다. 또한 신경배 시기에 RA에 노출된 배의 a-cardiac actin은 정상적으로 발현되는데 비해 낭배 초기에 RA에 노출된 배는 감소된 양의 a-cardiac actin myNA의 축적을 보였다. 그러나 EFI-u은 RA의 처리 시기와는 무관하게 정상적으로 발현되었다.

• The Korean Journal of Pesticide Science
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• v.14 no.2
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• pp.123-132
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• 2010

Six populations of the diamondback moth, Plutella xylostella, were collected from the different national areas for resistance and reared in laboratory for two sensitive population. These populations of P. xylostella were examined the developed resistance against commercial products of Bacillus thuringiensis. There were 3 products with B. thuringiensis subsp. kurstaki including Tyuneup$^{(R)}$, Thuricide$^{(R)}$ and Geumulmang$^{(R)}$ and 2 products with B. thuringiensis subsp. aizawai including Tobagi$^{(R)}$ and Scorpion$^{(R)}$. The sensitive population of diamondback moths were provided from National Academy of Agricultural Science (NP) and Highland Agriculture Research Center (GR population) and field populations were caught from 6 different national areas. Resistance against Tyuneup$^{(R)}$ was developed 4.8 and 2.5 times in SP and HS compared with GR population of diamondback moth, respectively. In case of Geumulmang$^{(R)}$, it was developed 9.9 and 6.8 times in SP and NM population compared with NP population, respectively. Otherwise, Tobagi$^{(R)}$ was showed higher resistance in HS than any other population compared with GR population, however, Scorpion$^{(R)}$ that is a same strain with Tobagi$^{(R)}$, was showed only double resistance to SP population. It was supposed that the development of resistance to B. thuringiensis might be caused by the continuous application of the specific commercial product at the specific area. So, we need to use the commercial products of B. thuringiensis in rotation with different B. thuringiensis strains. In the other hand, when HS population with highest resistance were reared in laboratory, their resistance ratio was rapidly dropped to 1.1 times at second generation. We have to examined the resistance mechanism of the diamondback moth to B. thuringiensis strains.

• The Korean Journal of Malacology
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• v.31 no.4
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• pp.315-322
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• 2015

The sex of bivalves is classified into gonochorism and hermaphroditism, and hermaphroditism is further divided into simultaneous (synchronous or functional), and sequential (asynchronous). The sequential hermaphroditism signifies sex reversal in accordance with seasons. In general, in the case of gonochoristic bivalves, manifestation of sex as female and male, after having identified the morphological sex, is limited to a period of the life cycle in any given individual. In order to accurately identify sex, continuous monitoring of changes in the sex during life cycle is necessary by tagging the sex. In the bivalves, sex reversal and sequential hermaphroditism has been reported in the Ostreidae, Pectinidae, Veneridae and Arcidae etc.. Most of these studies have reached this conclusion based on evidence derived from sex ratio change in accordance with the age within same populations. Sex change in the sequential hermaphroditic bivalves normally occurs when the gonad is undifferentiated between spawning seasons. Two factors are involved in sex determination and sex change in bivalves, namely genetic and environmental. However, more detailed research is needed on the effect of the genetic and environmental factors involved in sex determination and sex change of bivalves.

• Korean Journal of Environmental Biology
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• v.37 no.3
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• pp.426-432
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• 2019

The aim of the present study was to investigate the temporal changes of moth communities in two forest types of the agroecosystem in the southwestern part of Korea, an isolated hillock forest and a continuous mountain forest. Temporal changes in the numbers of moth species and individuals at both forests showed no significant difference, although the numbers of individuals in the isolated hillock forest were decreased. The relationship between changes in moths and body size based on wingspan revealed that the larger moths decreased more in the isolated hillock forest, whereas no effect of body size on change of moths was observed in continuous mountain forest samples. Non-metric multidimensional scaling resulted in the grouping of moth communities by forest types and 10-year time intervals. In the future, long-term monitoring is needed to track the changes in moth communities in agroecosystems. Additionally, we need to investigate the effect of other ecological variables on changes in moth diversity.

• Korean Journal of Plant Resources
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• v.26 no.4
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• pp.457-462
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• 2013

Molecular study were conducted to evaluate taxonomic identities of Echinochloa crus-galli (L.) Beauv. and Echinochloa crus-galli var. echinata (Willd.) Honda in Dokdo. Echinochloa crus-galli complex of two species 26 individuals analyse based on nuclear ribosomal DNA (ITS region) and cpDNA (trnH-psbA, trnL-F). At a result, two species were same sequence. Characters the length of the lemma and the length of the awn traits were identity of the species was unclear. According to, Taxonomy treatments that is based on existent morphological characters should thinks again. On the other hand, in the case of ITS, Echinochloa crus-galli (L.) Beauv. and Echinochloa crus-galli var. echinata (Willd.) Honda at the Dokdo forms from other clades with individuals that is collected at land area and Ulleungdo. These result is showing that is flowing independent evolution trends.