• Journal of Korea Water Resources Association
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• v.31 no.5
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• pp.553-564
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• 1998

For the proper design and management of underground storage cavern, groundwater flow around cavern should be analyzed. Since this flow is influenced by spatial nonuniformity of hudraulic conductivity, the two-dimensional finite element flow model incorporating stochastic concepts was developed to analyze influences due to this nonuniformity. Monte Carlo technique was applied to obtain an approximate solution for two-dimensional, steady flow in a stochastically defined nonuniform medisu. For this purpose, the values of hydraulic conductivity were generated for each element with known mean and standard deviations. The uncertainty in model prediction depends on both the nonuniformity in hydraulic conductivity and the natures of the flow system such as water curtain and boundary condition. Therefore the uncertainties in predicted hydraulic head and gradient are the greatest where the mean hydraulic gradients are relatively large and far from the boundaries. Especially, we relate these uncertainties with well known gas tightness condition.

• Journal of Digital Convergence
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• v.13 no.7
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• pp.293-304
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• 2015

Meta-analysis was conducted to examine effects of computer based virtual reality on clinical rehabilitation in Korea. The data were analyzed as the ICF categorizations. The papers used in this study were located through domestic data search engines. The fifteen studies were selected among the studies published between 1995 and 2014. The PEDro score was used for qualitative assessment. The sample size and the average and standard deviations of pre and post tests were analyzed through a meta-analysis. The PEDro scores of the selected studies were 6 points higher and 338 participants were involved. The effect size of combined data was 1.030, activities and participation 1.120, sensory function 1.199 as indicated by a "large effect size" and the effect size of mental function was 0.557 as indicated by a "medium effect size." As a result, virtual reality program as a adjunctive therapeutic methods has proven the effect. In particular, the effects were demonstrated in activities and participation, sensory function. However there was no evidence of the effectiveness of mental function.

• Nuclear Engineering and Technology
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• v.18 no.1
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• pp.9-16
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• 1986

Simulation of the system thermal-hydraulic parameters was carried out following the KNUl (Korea Nuclear Unit-1) loss of normal feedwater transient sequence occurred on November 14, 1984. Results were compared with the plant transient data, and good agreements were obtained. Some deviations were found in the parameters such as the steam flowrate and the RCS (Reactor Coolant System) average temperature, around the time of reactor trip. It can be expected since the thermal-hydraulic parameters encounter rapid transitions due to the large reduction of the reactor thermal power in a short period of time and, thereby, the plant data involve transient uncertainties. The analysis was performed using the RELAP5/MOD1/NSC developed through some modifications of the interphase drag and the wall heat transfer modeling routines of the RELAP5/MOD1/CY018.

• The KIPS Transactions:PartD
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• v.10D no.6
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• pp.1025-1032
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• 2003

Percentiles are convenient measures of the entire range of values of simulation outputs. However, unlike means and standard deviations, the observations have to be stored since calculation of percentiles requires several passes through the data. Thus, percentile (PE) requires a large amount of computer storage and computation time. The best possible computation time to sort n observations is (O($nlog_{2}n$)), and memory proportional to n is required to store sorted values in order to find a given order statistic. Several approaches for extimating percentiles in RS(regenerative simulation) and non-RS, which can avoid difficulties of PE, have been proposed in [11, 12, 21]. In this paper, we implemented these three approaches known as : leanear PE, batching PE, spectral $P^2$ PE in the context of sequential steady-state simulation. Numerical results of coverage analysis of these PE approachs are present.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.21 no.4
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• pp.353-359
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• 1999

Purpose : A new method of lateral cephalometric analysis for midface, focusing on zygomatic bone, was created in this study, and measured in Korean adults. The purposes of this study are understanding about new approach for midfacial depression, especially zygomatic bone, and using to make adequate diagnosis and treatment plan. Materials and methods : In this study, esthetic Korean adults, 25 males and 25 females who were between $0^{\circ}$ and $4^{\circ}$ in ${\angle}ANB$, and between 62% and 70% in P/A facial height ratio, and had normal overbite and overjet, were used. Orbitale(Or) and Soft tissue orbitale(Or') were used for indicators of anteroposterior position of zygomatic area. And, mean value and standard deviation of linear and angular measurements, and ratio about each linear measurements, were obtained. then, standard deviation diagram - wiggle diagram - was made for visualization of results. Results : Mean values, standard deviations and ranges of 19 measurements were obtained, and among them, 5 linear measurements that had large standard deviation were excluded and the others were used for making standard deviation diagram. In standard deviation diagram, the following results were obtained. 1. If the measurements are located on more left side of mean-value-vertical -line, the potential of midfacial hypoplasia are stronger, especially zygomatic area. 2. If the measurements are located on more right side of mean-value-vertical-line, the potential of midfacial hypoplasia are decreased. Conclusion : This study presented a new method of lateral cephalometric analysis focusing on zygomatic bone in Korean adults. We expect that the results of this study can be used as parameter when clinicians make decisions about diagnosis and treatment plan for rehabilitation of esthetics and function. But, it is necessary to prove its usefulness, and to further evaluate the results.

• Journal of the East Asian Society of Dietary Life
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• v.9 no.1
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• pp.55-63
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• 1999

This research was conducted to estimate waste rates of 69 food items after pre-preparation and amounts of food wastes disposed and it's reduction effect by education in some institutional foodservices for reduction of the food wastes. The result are as follows: 1. The waste rates were 55.40% for sweet corn, 5.73% for potatoes, 19.14% for sweet potatoes, and 33.47% for chestnuts. 2. The waste rates of fruits were 0.21-49.36%. Food items with over 40% waste rate were banana, watermelon, and pineapple. 3. The waste rates of vegetables were 1.14-52.90%. The number of foods with under 10% waste rate were 14 items(red pepper, green pepper, chard, and so on), 10-20% was 9 items(perilla leaf, chinese cabbage, ginger root, and so on), 20-30% was 5 items(root of chinese bellflower, garlic, radish-leaves, burdock, welsh onion-large type), 30-40% was 3 items(shepherd's purse, head lettuce, kale) and over 40% was 3 items(water dropwort, crown daisy, mallow). 4. The waste rates were 24.30% in chicken, 9.53-13.79% in eggs, and 9.30-55.32% in fishes. The waste rates of vegetables and fishes were higher than those of other food groups. 5. There were significantly different in amount of food wastes disposed (g/person/day) to institutional foodservices (hospital＞industrial institution＞ Korean restaurant＞elementary school). The amount of food wastes disposed, especially amount in pre-preparation phase, after education for reduction of food wastes was significantly reduced. Since these study results show significant deviations in food waste rates and education effect, there should be more studies for standard waste rates of each food and systematic education method for reduction of food wastes.

• Structural Engineering and Mechanics
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• v.74 no.1
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• pp.55-67
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• 2020

The common practice to predict the characteristic structural load effects (LEs) in long reference periods is to employ the extreme value theory (EVT) for building limit distributions. However, most applications ignore that LEs are driven by multiple loading events and thus do not have the identical distribution, a prerequisite for EVT. In this study, we propose the composite extreme value modeling approach using clustering to (a) cluster initial blended samples into finite identical distributed subsamples using the finite mixture model, expectation-maximization algorithm, and the Akaike information criterion; (b) combine limit distributions of subsamples into a composite prediction equation using the generalized Pareto distribution based on a joint threshold. The proposed approach was validated both through numerical examples with known solutions and engineering applications of bridge traffic LEs on a long-span bridge. The results indicate that a joint threshold largely benefits the composite extreme value modeling, many appropriate tail approaching models can be used, and the equation form is simply the sum of the weighted models. In numerical examples, the proposed approach using clustering generated accurate extrema prediction of any reference period compared with the known solutions, whereas the common practice of employing EVT without clustering on the mixture data showed large deviations. Real-world bridge traffic LEs are driven by multi-events and present multipeak distributions, and the proposed approach is more capable of capturing the tendency of tailed LEs than the conventional approach. The proposed approach is expected to have wide applications to general problems such as samples that are driven by multiple events and that do not have the identical distribution.

• Journal of Korean Society for Atmospheric Environment
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• v.32 no.2
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• pp.184-192
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• 2016

Recently, studies on reducing mercury have been actively conducted worldwide, which include the current status of mercury emissions and mercury control technology. Among the control technology, Sorbent Trap measurement method has been aggressively developed due to its reliability, easiness in measurement and analysis. The purpose of this study is to evaluate the applicability of the new international measurement method; Sorbent Trap. For this, the study compared the Sorbent trap method (US EPA Method 30B) and the Korean Standard Method for Examination of Air (ES 01408.1) to evaluate their reliability, and developed mercury emission factors. As the result, the relative standard deviations (% RSD) of the two methods were 3.5~13.4% at Coal-fired Power Plants (CPP), 4.0~18.4% at Cement Kilns (CK), and 3.0~11.3% at Medical Waste Incinerators (MWI). The emissions factors were developed as 14.50 kg/ton at CPP, 45.10 kg/ton at CK, and 1,290.2 kg/ton at MWI.

• Computers and Concrete
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• v.17 no.6
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• pp.787-799
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• 2016

Climate anomalies in recent years, numerous natural disasters caused by landslides and a large amount of entrained sands and stones in Taiwan have created significant disasters and greater difficulties in subsequent reconstruction. How to respond to these problems efficaciously is an important issue. In this study, the sands and stones were doped with recycled materials (waste LCD glass sand, slag powder), and material was mixed for recycled ready-mixed soil. The study is based on security and economic principles, using flowability test to determine the water-binder ratio (W/B=2.4, 2.6, and 2.8), a fixed soil: sand ratio of 6:4 and a soil: sand: glass ratio of 6:2:2 as fine aggregate. Slag (at concentrations of 0%, 20%, and 40%) replaced the cement. The following tests were conducted: flowability, initial setting time, unit weight, drop-weight and compressive strength. The results show that the slump values are 220 -290 mm, the slump flow values are 460 -1030 mm, and the tube flow values are 240-590 mm, all conforming to the objectives of the design. The initial setting times are 945-1695 min. The unit weight deviations are 0.1-0.6%. The three groups of mixtures conform to the specification, being below 7.6 cm in the drop-weight test. In the compressive strength test, the water-binder ratios for 2.4 are optimal ($13.78-17.84kgf/cm^2$). The results show that Recycled ready-mixed soil materials (RRMSM) possesses excellent flowability. The other properties, applied to backfill engineering, can effectively save costs and are conducive to environmental protection.

• Journal of the Korean Society for Library and Information Science
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• v.55 no.4
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• pp.67-87
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• 2021

Public library accessibility directly affects library usage, and the disproportionate distribution of accessibility is a decisive factor limiting the equitable provision of library services. In this regard, this study analyzed the spatial accessibility of public libraries in Busan and identified the factors affecting accessibility of public libraries using spatial regression analysis. As a results of the analysis, the accessibility of public libraries in the Busan showed large deviations by region. Also, spatial distribution of public libraries had no correlation with the settled population and use of public transportation, and location of public libraries was inefficient, in terms of social equity. The results of this study will assist to understand the spatial accessibility of public libraries in Busan, to identify factors that affect the accessibility. Moreover, this study is expected to be utilized as fundamental data for releasing disparities of the spatial accessibility and selecting new location of public library in Busan.