• Journal of the Korean Geotechnical Society
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• v.25 no.12
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• pp.13-25
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• 2009

In this paper, a numerical procedure of probabilistic slope stability analysis that considers the spatial variability of soil properties is presented. The procedure extends the deterministic analysis based on the limit equilibrium method of slices to a probabilistic approach that accounts for the uncertainties and spatial variation of the soil parameters. Making no a priori assumptions about the critical failure surface like the Random Finite Element Method (RFEM), the approach saves the amount of solution time required to perform the analysis. Two-dimensional random fields are generated based on a Karhunen-Lo$\grave{e}$ve expansion in a fashion consistent with a specified marginal distribution function and an autocorrelation function. A Monte Carlo simulation is then used to determine the statistical response based on the random fields. A series of analyses were performed to verify the application potential of the proposed method and to study the effects of uncertainty caused by the spatial heterogeneity on the stability of slope. The results show that the proposed method can efficiently consider the various failure mechanisms caused by the spatial variability of soil property in the probabilistic slope stability assessment.

• Journal of the Korean Geotechnical Society
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• v.24 no.8
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• pp.111-123
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• 2008

Geotechnical engineering problems are characterized by many sources of uncertainty. Some of these sources are connected to the uncertainties of soil properties involved in the analysis. In this paper, a numerical procedure for a probabilistic analysis that considers the spatial variability of soil properties is presented to study the response of spatially random soil. The approach integrates a commercial finite difference method and random field theory into the framework of a probabilistic analysis. Two-dimensional non-Gaussian random fields are generated based on a Karhunen-$Lo{\grave{e}}ve$ expansion in a fashion consistent with a specified marginal distribution function and an autocorrelation function. A Monte Carlo simulation is then used to determine the statistical response based on the random fields. A series of analyses were performed to study the effects of uncertainty due to the spatial heterogeneity on the settlement and bearing capacity of a rough strip footing. The simulations provide insight into the application of uncertainty treatment to the geotechnical problem and show the importance of the spatial variability of soil properties with regard to the outcome of a probabilistic assessment.

• The Korean Journal of Food And Nutrition
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• v.37 no.3
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• pp.162-170
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• 2024

The domestic swine industry is currently facing a threat due to the recent increase in pork imports. This study aims to determine what factors influence consumers' intention to consume imported pork and suggest measures to support the domestic pork industry. To achieve this, we analyzed data from the Korea Rural Economic Institute's Food Consumption Behavior Survey using a binary logistic regression model. The results revealed that a higher intention to consume imported pork is linked to a higher intention to consume imported rice, purchasing meat online, frequent purchases of HMR, and procuring U.S. beef, especially among urban residents. On the other hand, a lower intention to consume imported pork is associated with a higher awareness of animal welfare certification, frequently dining out, and older age. Based on these findings, we propose the following response measures for the domestic swine industry: implementing educational programs, marketing, and advertising specifically targeting urban residents to improve their perception of domestic agricultural products; enhancing price competitiveness through distribution optimization; and developing policies to promote the use of domestic pork as an ingredient in processed foods.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.44 no.2
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• pp.161-172
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• 2024

A Copula approach has the advantage of providing structural dependencies for representing multivariate distributions for the hydrometeorological variable marginal distribution involved, however, copulas are inflexible for extending in high dimensions, and satisfy certain assumptions to make the dependency. In addition, since the process of estimating design rainfall under the future climate associated with durations given a return period is mainly analyzed by 24-hour annual maximum rainfalls, the dependency structure contains information only on the daily and sub-daily extreme precipitation. Methods based on bivariate copula do not provide information for other duration's dependencies, which causes the intensity to be reversed. The vine copula has been proposed to process the multivariate analysis as vines consisting of trees with nodes and edges connecting pair-copula construction. In this study, we aimed to downscale under climate change to produce sub-daily extreme precipitation data considering different durations based on vine copula.

• The Journal of Korean Academy of Prosthodontics
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• v.48 no.2
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• pp.111-121
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• 2010

Purpose: This 3D-FEA study was performed to investigate the influence of marginal bone loss pattern around the implant to the stress distribution. Material and methods: From the right second premolar to the right second molar of the mandible was modeled according to the CT data of a dentate patient. Teeth were removed and an implant ($\Phi\;4.0{\times}10.0mm$) was placed in the first molar area. Twelve bone models were created; Studied bone loss conditions were horizontal bone loss and vertical bone loss, assumed bone loss patterns during biologic width formation, and pathologic vertical bone loss with or without cortification. Axial, buccolingual, and oblique force was applied independently to the center of the implant crown. The Maximum von Mises stress value and stress contour was observed and von Mises stresses at the measuring points were recorded. Results: The stress distribution patterns were similar in the non-resorption and horizontal resorption models, but differed from those in the vertical resorption models. Models assuming biologic width formation showed altered stress distribution, and weak bone to implant at the implant neck area seams accelerates stress generation. In case of vertical bone resorption, contact of cortical bone to the implant may positively affect the stress distribution.

• Journal of Distribution Science
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• v.13 no.3
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• pp.79-91
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• 2015

Purpose - First, the study identifies and analyzes consumer preferences with regard to health foods and supplements. Second, it identifies and analyzes consumer preferences with regard to the properties of Vitamin C supplements. Third, in order to provide a basic data for the development of Vitamin C supplements and to measure how consumers value the properties of different Vitamin C products, a consumer survey was conducted through the choice-based conjoint model. Based on the results, the research estimates consumers' relative product-related priorities as well as price levels and willingness to pay (WTP) for different product types, and makes suggestions regarding consumer-oriented new product development and progressive directions for the successful launch of health foods and supplements. Research design, data, and methodology - This study aims to define the attributes of health foods and supplements based on several characteristics including their natural ingredients, product price, product originality, natural ingredient content, and additional functional ingredients, and makes suggestions regarding strategic market pricing and product development for health foods and supplements according to customer attitudes and characteristics. The research used choice-based conjoint analysis methodology based on the Multinomial Logic Model and collected 94 questionnaires filled out by users of Korean Vitamin C supplements. Results - Product price is the most influential factor among the five analyzed properties. When consumers buy Vitamin C products, the relative significance level of four of the examined properties is as follows: 40.9% for product price, 23.3% for product originality, 21.9% for natural ingredient content, and 13.9% for additional functional ingredients. Vitamin C content is excluded as it is not a statistically significant factor. It is interesting that supplement manufacturers and retailers consider Vitamin C content to be very important whereas consumers do not regard it as an important factor at the time of purchase. The results for the marginal willingness to pay (MWTP) for each property of Vitamin C supplements show that consumers are willing to pay an additional 11,146 Korean won for a 50% increase in the natural ingredient content. With regard to product originality, consumers are willing to pay an additional 11,301 Korean won for products manufactured in Europe than for products manufactured in China. Moreover, consumers show a greater preference for products manufactured in Korea than in Europe. However, consumers are not willing to pay more for additional Vitamin C or additional functional ingredients added to Vitamin C products. Conclusions - According to the results of consumer research on Vitamin C supplements, which represent a popular health food supplement in Korea, most Korean health food and supplement companies are not consumer- or market-oriented when developing new products. Companies gather information from either R&D specialists or sales managers and their opinions are highly reflected in new product development. The study's results will help companies recognize the importance of understanding consumers' unmet needs in advance to develop new products in the future.

• Korean Journal of Soil Science and Fertilizer
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• v.41 no.3
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• pp.214-222
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• 2008

This study was carried out to investigate the distribution characteristics, colonization patterns of arbuscular mycorrhizal fungi (AMF) at Ginseng- cultivated fields in Jeonnam province including Gokseong, Yeonggwang, Yeongam and Haenam area. Average density of AMF spores in all of analyzed areas was in the range of $3.4{\sim}5.9spores\;g^{-1}$ air-dried soil and spore density in the soil was increased gradually up to Ginseng cultivated fields grown for 3 years. However, AMF spore densities in the marginal field soil were $6.3{\sim}14.7spores\;g^{-1}$ air-dried soil and it was higher than those in Ginseng-cultivated field soils. A $45{\sim}106{\mu}m$ in diameter of AMF spores by size was dominant (74.3%) in Ginseng cultivated fields. AMF colonization association type in Ginseng roots was a Paris-type. Average rates of AMF infection ranged from 40% to 50%, while 64.4% of AMF infection occurred in Yeongam area. External hyphae length (EHL) in the rhizosphere soil of Ginseng cultivated field was in the range of $0.5{\sim}4.4m\;g^{-1}$ air-dried soil and the hyphae quantity was gradually increased proportional to increment of Ginseng cultivation years.

• Journal of Educational Research in Mathematics
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• v.23 no.4
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• pp.467-490
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• 2013

Correlation is a basic statistical concept which is necessary for understanding the relationship between two variables when they change values. In the middle school curriculum of Korea, only informal definition of correlation is taught with two-way data representations such as scatter plots and contingency tables. In this study, we investigated Korean high school students' understanding of correlation using a test consisting of 35 items about interpretation of scatter plot, contingency table, and text in realistic situation. 216 students from a high school in Seoul took the test for 20 minutes. From the results, we could observe the following: First, students did not have right criteria for determining the strength of correlation presented in scatter plots. Most of students could determine if there is correlation/no correlation and if the correlation is positive/negative by seeing the data presented in scatter plots. However, they did not judge by the closeness to the regression line but rather judged by the closeness between data points. Second, when statements about comparing the strength of correlation in the context of real life situation were given in text, the students had difficulty in understanding the distribution-related characteristic of the bi-variate data. Students had difficulty in figuring out the local distribution characteristic of data, which cannot be guessed merely based on the expression 'The correlation is strong' without statistical knowledge of correlation. Third, a large number of students could not judge the association between two variabels using conditional proportions when qualitative data are given in 2-by-2 tables. They made judgement by the absolute cell count and when the marginal sum of two categories are different for explanatory variable they thought the association could not be determined. From these results, we concluded that educational measures are required in order to remove such misconceptions and to improve understanding of correlation. Considering that the current mathematics curriculum does not cover the concept of correlation, we need to improve the curriculum as well.

• The Korean Journal of Financial Management
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• v.26 no.3
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• pp.139-169
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• 2009

This paper introduces the modified VaR which takes into account the asymmetry and fat-tails of financial asset distribution, and then compares its out-of-sample forecast performance with traditional VaR model such as historical simulation model and Riskmetrics. The empirical tests using stock indices of 6 countries showed that the modified VaR has the best forecast accuracy. At the test of independence, Riskmetrics and GARCH model showed best performances, but the independence was not rejected for the modified VaR. The Monte Carlo simulation using skew t distribution again proved the best forecast performance of the modified VaR. One of many advantages of the modified VaR is that it is appropriate for measuring VaR of the portfolio, because it can reflect not only the linear relationship but also the nonlinear relationship between individual assets of the portfolio through coskewness and cokurtosis. The empirical analysis about decomposing VaR of the portfolio of 6 stock indices confirmed that the component VaR is very useful for the re-allocation of component assets to achieve higher Sharpe ratio and the active risk management.

• Proceedings of the KOR-BRONCHOESO Conference
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• 1983.05a
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• pp.19.2-19
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• 1983

A Clinical and bacteriologcal observation was performed 128 cases of chronic otitis media who had taken middle ear surgery at Dept. of otolaryngology of St. Benedict Hospital during the period of Feb. 1981 to Feb. 1983. The following results were obtained. 1) Among total 128 cases, male were 60 cases (46.9%) and female were 68 cases (53.1 %) and age distribution showed 48 cases (37.5 %) in 3rd decade, 37 cases (28.9 %) in 2nd decade and 27 cases (21.1 %) in 4th decade. 2) Site distribution were 71 cases (55.5%) in right, 57 cases (44.5 %) in left. 3) Degree of preoperative hearing loss were 64 cases (50%) in moderate, 32 cases (25% ) in mild, 27 cases (21.1 %) in severe and 5 cases (3.9%) were normal. 4) Central perforation were observed in 65 cases (50.8 %), total perforation in 44 cases (34.4 %), attic perforation in 12 cases (9.4 %) and marginal perforation in 7 cases (5.4 %). 5) Pathologic changes of middle ear and mastoid antrum showed granulation in 81 cases (63.3 %), cholesteatoma in 47 cases (36.7%). 6) The route of approach were 123 cases (96.1%) in postauricular, 3 cases (2.3%) in transmeatal and 2 cases (1.6 %) in endaural. 7) Type of operation were 53 cases (41.4 %) in intact canal wall tympanoplasty with mastoidectomy, 42 cases (32.8 %) in tympanoplasty without mastoidectomy, 23 cases (18%) in modified radical mastoidectomy and 10 cases (7.8%) in radical mastoidectomy. 8) Type of anesthesia were 95 cases (74.2 %) by local anesthesia, 33 cases (25.8 %) were by general anesthesia. 9) Among 93 specimens of culture, proteus (31.2%), staphylococcus (28.7%), pseudomonas (23.7 %), streptococcus (7.5 %) and etc. (8.7%) in order of frequency.