• Journal of Life Science
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• 제12권5호
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• pp.544-548
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• 2002

The object of this study was to investigate nitrogen fixation activity of rhizobium inoculated at seed coat when drought condition was applied in flowering period of soybean c.v. Samnamkong. The rhizobia used in this experiment were indigenous rhizobium, R2l4, RJl-29, USDA110 and USDA122. The experiment was done with 1/2000 Wagner pots in laboratory and greenhouse and was tested in completely randomized design with four replications. Nitrogen fixation activity in coventional culture was the highest in R2l4 and indigenous rhizobium among the five rhizobia strains. As given drought condition from flowering to maturity, nitrogen fixation activity was higher in R2l4 and RJl-29 than indigenous rhizobium. Leaf area and relative index (drought/convention) of pod weight were higher in USDA122, RJl-29 and R2l4 than indigenous rhizobium as given drought condition from flowering to maturity. High positive correlation was observed between nitrogen fixation activity of rhizobium and relative index(drought/convention) of pod weight. High negative correlation was observed between respiration of plant and relative index (drought/convention) of leaf area.

• Korean Journal of Ichthyology
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• 제27권3호
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• pp.217-227
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• 2015

Reproductive biology and population dynamics of Luciogobius guttatus were investigated. Higher gonadosomatic index (GSI) was observed from March~May. The fecundity ranged form 241 eggs at 3.1~4.0 cm (SL) to 716 eggs at 5.1~5.7 cm (SL). The relationship between length (SL) and fecundity (F) was $F=11.242SL^{2.464}$ ($R^2=0.65$) and fecundity increased with length. We estimated the SL at 50% group maturity as 2.6 cm. The spawning period was March~May. The von Bertalanffy growth function (VBGF) estimates were: $L_{\infty}=63.00mm$ TL; $K=0.85yr^{-1}$. The structure of recruitment pattern obtained by the FiSAT II program indicated one normally distributed group. The growth performance index (${\phi}$) was calculated with 3.53. Natural mortality rate (M) was $1.00yr^{-1}$.

• Korean Journal of Fisheries and Aquatic Sciences
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• 제39권5호
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• pp.391-397
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• 2006

This study correlated changes in estradiol-l7$\beta$ ($E_2$), testosterone (T), 17$\alpha$,20-dihydroxy-4-pregnen-3-one (DHP), and vitellogenin (VTG) levels with changes in the gonadosomatic index (GSI) and ovarian histology during the annual reproductive cycle of the wild marbled sole, Limanda yokohamae. Synchronous oocyte development occurs in this fish. Ovary maturity was classified into four periods, based on histological observations: the spawning (December to February), post-spawning (February to April), recovery (May to August), and vitellogenic (September to November) periods. Seasonal changes in the GSI were inversely correlated with water temperatures and reflected the degree of ovarian maturity. Plasma VTG levels were correlated with changes in the GSI, which increased from September to a peak in January, and levels remained comparatively high until February. Estradiol-17$\beta$ was at baseline levels (<0.11 ng/mL) during the spring and summer, and peaked rapidly (1.55$\pm$0.445 ng/mL) from October to January. Plasma T and DHP levels had a similar profile; they rose markedly during the spawning period and remained low (or were not detectable) from spring through autumn. These data indicate that changes in plsama steroid hormones and VTG levels are correlated with the annual ovarian activity of the marbled sole. Based on these results and published reports, it appears that in this species DHP is the most important maturation-inducing steroid and that T is also related to final maturation.

• Korean Journal of Veterinary Research
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• 제46권3호
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• pp.285-289
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• 2006

This study was performed to assess the growth plate closure time with aging in the Korean native goat. Radiographs of proximal and distal epiphysis of humerus, radius, ulna, femur and tibia were obtained at 2, 3, 4, 5, 6, 7, 8, 9, 11, 12, 13, 14, 17, 18, 20, 21, 30, 43 and 52 weeks after birth in 30 Korean native goats. The secondary ossification centers were scrutinized and assessed the maturity process on the basis of the criteria(stage 0 to 10). The secondary ossification centers of proximal and distal epiphysis of humerus, radius, femur and tibia and proximal ulna epiphysis appeared immediately after birth. While, that of distal ulna epiphysis appeared during the 1st to 2nd week of life. The fusion of distal humeral epiphysis occurred during the period from 8 to 12 months. The fusion of proximal radial epiphysis and distal tibial epiphysis were found at 1 year. The fusion of proximal and distal epiphysis of ulna and femur, proximal epiphysis of humerus and tibia and distal epiphysis of radius were found at 1 year or more than 1 year. As a result, growth plate closure was highly related to age in the Korean native goat and it is suggested that the estimation of animal's age might be useful by illustration of maturity process of the secondary ossification centers in the Korean native goat.

• Fisheries and Aquatic Sciences
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• 제7권1호
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• pp.16-22
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• 2004

Plasma steroid hormone levels in the viviparous rockfish (Sebastes schlegeli) were examined in relation to gonadal histology under controlled photoperiods and water temperatures. To investigate those effects in S. schlegeli the photoperiod was maintained at 15L:9D in June and then it was gradually decreased to 9L: 15D in October. It was then gradually increased to 12L:12D in January, followed by 14L:I0D in February. The water temperature was $19-20^{\circ}C$ in July. From August to October, it was from $18^{\circ}C\;to\;12^{\circ}C$. Then, it was dropped to a low of $19-11^{\circ}C$ in November to December and then gradually increased to $14-15^{\circ}C$ in February. In females, both plasma $estradiol-l7\beta\;$ (E2) and testosterone (T) levels from August to February showed a similar pattern in both the treatment and the control groups. In the treatment group, the peaks of plasma E2 and T were observed in November, and the peaks were closely correlated to histological observations. Oocytes contained many yolk globules (final vitellogenic oocytes), and oocytes at the migratory nucleus stage increased in size. Plasma levels of progesterone did not change much throughout the experimental period. However, in the control group, the peaks of E2, T, and progesterone were observed in February. These results indicate that the controlled photoperiod and water temperature accelerated sexual maturity, corresponding to the advancement of plasma E2 and T peaks by approximately 3 months. In males, plasma T levels showed a similar pattern from August to October in the treatment and control groups, though levels in the treatment group were higher than those in the control group. From histological observations, the treatment group copulated one month earlier.

• Korean Journal of Ichthyology
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• 제23권2호
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• pp.111-118
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• 2011

The maturation and spawning of filefish, Stephanolepis cirrhifer were investigated using samples randomly collected in the East Sea of Korea from August 2009 to July 2010. The total length at 50% group maturity of filefish was estimated to be 11.7 cm. Based on monthly changes in maturity stages and gonadosomatic index (GSI), the spawning period was estimated to be from June to September, and the peak spawning from August to September. The fecundity (F) ranged from 693,981 eggs to 7,383,429 eggs at 23.6 cm between minimum and maximum total length (TL) 13.3 cm and 23.6 cm respectively. The relationship between TL and F was expressed as F=$12.19TL^{4.208}$ ($R^2$=0.727). The sex ratio of male to female was 1 to 0.9.

• Journal of Information Technology Services
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• 제9권2호
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• pp.43-72
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• 2010

The Korean mobile telecommunication service market is faced with a tremendous competitive period, in which the market is entering into the maturity stage with launching of the 3rd generation service and with introduction of mobile number portability. In general, it is more important to sustain the old customers than to attracting new customers, as the life cycle of an industry is entering the maturity stage in which the growth rate of new customers is decreasing gradually or becoming stagnant. Until now, many researches had tested whether the customer satisfaction and loyalty were the core factors of sustaining customers or not. Also service quality and switching cost were given a remarkable attention for their possibility of exogenous factors, which could exercise effects to customer satisfaction and loyalty. In the same context, mobile telecommunication business has to seek a way to maintain the existing customers instead of promoting new customers. So this study investigates whether the service quality and switching barrier of mobile telecommunication could have effects on the customer satisfaction and loyalty, which are recognized as an efficient means to sustain the current customers. In order to test the hypothesis on the effects of service quality and switching barrier of mobile telecommunication to customer satisfaction and loyalty in Korean telecommunication industry, this study collected the questionnaire response data of students including middle and high school students and undergraduates, who are regarded as the major customers in that mobile telecommunication industry.

• The Journal of Fisheries Business Administration
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• 제38권2호
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• pp.63-78
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• 2007

The objective of this study is to examine the speculative efficiency of shrimp futures market. Testing for the speculative efficiency hypothesis is carried out using Johansen's the maximum-likelihood cointegration method and Fama(1984) regressison model. Analysis data are obtained Kansai Commodities Exchange in Osaka and are daily data of frozen shrimp futures and cash prices for all trading days in the time period from September 6, 2002, frozen shrimp futures is introduced, to May 10, 2007. The empirical results are summarized as follows:First, there exists the cointegrating relationship between realized spot India 16/20, Indonesia 16/20, vietnam 16/20 prices and futures prices of the 14 day to maturity. Second, shrimp futures contract prices do not behave as unbiased predictor s of future spot shrimp prices. This indicates that the shrimp futures market is inefficient.

• Journal of Korean Society for Quality Management
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• 제23권4호
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• pp.74-89
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• 1995

In recent years, the safety of customers and the demand for rights to be protected from the risk have become stronger than ever day by day, and the function concerning product liability(PL) and quality assurance(QA) has been emphasized. Basically these functions can be obtained by inspection and there is the single rectifying sampling inspection for attribute (KSA-3105) as an existing method. But we can not say this method is good enough because of limitations in the range of applications and the approximate design of inspection methods which can not meet the rapidity and accuracy of quality information transfer according to the maturity of information period. Therefore, in this paper, a new algorithm is developed which can design the accurate inspection method by using the linear cost function that has not been considered in the existing inspection methods. Also in addition to this, a optimal rectifying sampling inspection plan, contributing to minimize the total costs, can be developed by programming the algorithm developed in this study and it can be applied to any field having many processes almost limitlessly.

• Proceedings of the Korea Concrete Institute Conference
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• 한국콘크리트학회 2002년도 봄 학술발표회 논문집
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• pp.711-716
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• 2002

The purpose of this study is to develop a strength control model for application of variety internal condition at construction field. The results of this study were shown as follows ; 1) According to results of compressive strength of concrete by using equivalent age, new curve is applicable of construction field because there is similar relation with logistic curve. 2) It is shown that the construction period is shorten by reduction of the formwork removal time, because a predicted compressive strength of using the new curve is high than proposed compressive strength of standard.