• Journal of Korean Tunnelling and Underground Space Association
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• v.7 no.1
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• pp.3-12
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• 2005

The behaviors of the ground in crossed zone and the existing upper tunnel in shallow cover due to the excavation of new lower tunnel Rectangularly crossed to that was studied. Model tests were performed in the large scale test pit, the size was '$4.0m(width){\times}3.8m(height){\times}4.1m(length)$'. Test ground was constructed uniformly by sand in middle density. Results of the model tests show that earth pressure and settlement of the ground in crossed zone were redistributed due to the longitudinal arching effect by the excavation of lower tunnel. Upper tunnel blocks stress flow due to the longitudinal arching effect by excavation of lower tunnel.

• Environmental Engineering Research
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• v.25 no.3
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• pp.374-383
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• 2020

Landfill gas (LFG) emissions from a given amount of landfill waste depend on the carbon flows in the waste. The objective of this study was to more accurately estimate the first-order decay parameters through methane (CH₄) and carbon flow balances based on the analysis of a full-scale landfill with long-term data and detailed field records on LFG and leachate. The carbon storage factor for the case-study landfill was 0.055 g-degradable organic carbon (DOC) stored per g-wet waste and the amounts of DOC lost with the leachate were less than 1.3%. The appropriate CH₄ generation rate constant (k) for bulk waste was 0.24 y-1. The the CH₄ generation potential (L0) values ranged 33.7-46.7 m3-CH₄ Mg-1, based on the fraction of DOC that can decompose (DOCf) value of 0.40. Results show that CH4 and carbon flow balance methods can be used to estimate model parameters appropriately and to predict long-term carbon emissions from landfills.

• Stress
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• v.26 no.4
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• pp.277-289
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• 2018

Background: The purpose of this study is to develop a short form of the normal depression scale for individual use in the school, health, industry, organization, and counseling settings, based on the original normal depression scale (17 items). Methods: To achieve this purpose, we selected five items from the original test and analyzed data using Mplus 7.4 and SPSS 21.0. Results: The normal depression scale-short form consists of 5 items. The reliability of the short form (test-retest reliability) was good. The content validity and internal structure validity (1 factor model) were verified. The cut score between normal and dysfunctional depression was determined to be 18. Conclusions: The normal depression scale-short form for individual screening is verified to have good reliability and validity, so it is expected to be useful to perform quick screening of normal depression in the practical settings.

• Electronics and Telecommunications Trends
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• v.33 no.4
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• pp.1-13
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• 2018

Deep learning (DL) models have been widely applied to AI applications such image recognition and language translation with big data. Recently, DL models have becomes larger and more complicated, and have merged together. For the accelerated training of a large-scale deep learning model, model parallelism that partitions the model parameters for non-shared parallel access and updates across multiple machines was provided by a few distributed deep learning frameworks. Model parallelism as a training acceleration method, however, is not as commonly used as data parallelism owing to the difficulty of efficient model parallelism. This paper provides a comprehensive survey of the state of the art in model parallelism by comparing the implementation technologies in several deep learning frameworks that support model parallelism, and suggests a future research directions for improving model parallelism technology.

• Journal of Korean Society of Disaster and Security
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• v.12 no.1
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• pp.23-34
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• 2019

It is an urgent issue to manage and reduce non-point pollution sources for improving the water quality of stream and lakes in rural areas. In this study, in order to reduce non-point pollution sources in rural area, Gabion mattresses was proposed to provide protection of riverbanks with anaerobic and aerobic area. The utilization of this was assessed by lab scale model test and pilot plant test. After filling the inside of the gabion mattresses with aggregate, the filtration zone under anaerobic and aerobic conditions was formed to treat the contaminants. In addition, vegetation was deposited on the surfae of the gabion to prevent the inflow of soil and to promote purification by the plant. COD and nitrogen content (T-N, $NH_4{^+}$, -N, $NO_3{^-}N$) were monitored in model and field tests. The lab scale model test showed removal efficiency of 17% of TCOD, 35% of SCOD, 14% of TN, 62% of $NH_4{^+}$, -N, and 33% of $NO_3{^-}$ N. Also, pilot plant test showed removal efficiency of 24% of TCOD, 29% of SCOD, 47% of TN, 50% of $NH_4{^+}-N$, 33% of $NO_3{^-}$, N and 29% of TP.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.41 no.2
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• pp.99-108
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• 2004

This thesis deals a method to deliver more realistic sound by cancelling the cross-talk which is inherent to the 5.1 channel speaker system. The acoustical model for cross-talk cancellation is the free field model. This model minimizes distortion of sound. I used the bark scale sound quality compensation which based on psycho-acoustic. For the surround channels, band-limited sound quality compensation is performed in the frequency domain. I also performed the sound quality assessment test on the traditional 2 channel stereo and 5.1 channel system. This test is performed in the test chamber which satisfies the ITU-R specifications. I uses the IACC(Inter-Aural Cross-Correlation) to determine the preferences of the amateur and the golden ear experts to asses the trans-aural filter. According to the result from the proposed method, I got more the 38㏈ separation rates with the Dolby standard speaker array. The results on the diffusion by the subjective test with the experts shows 0.4 point increased then before.

• Journal of the Korean housing association
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• v.17 no.2
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• pp.125-134
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• 2006

The tightness of windows have devoted to the improvement of thermal insulation and energy saving in buildings. But it is known that this tightness causes some side effects such as low ventilation, low capacity to humidity and temperature control and these are not profitable for inhabitants. To act on these side effects, Korean traditional windows which are composed of Han-Ji(Koreand traditional paper) and Chang-Sal(Korean traditional wooden frame) have been studied to get a reasonable solutions for these problems. In this study, to compare the thermal and humidity control performance of current window(12 mm pair) and Korean traditional windows, frames which are made of existing window and Korean traditional windows are adapted to scale model house and then humidity and temperature of in and out of scale model house are measured and analysed. The results of this study are followings ; 1) When Korean traditional window charges 20cm(1/8 of total window area) from total window area, Han-Ji window has higher thermal insulation than that of existing window in daytime. There is the most big thermal difference when double faced with double-ply Han-Ji window is placed to mock-up house. In night-time, the temperature difference is very small so this means that Korean traditional window is good to cover direct sunlight in daytime and reduce the temperature of balcony. One faced with one-ply han-Ji window has the best humidity penetration performance among three type of Korean traditional windows. 2) When Korean window area enlarged to 40cm(1/4 of total window area), the function of 40cm width Han-Ji window is higher than that of 20cm's. This means that enlargement of Han-Ji window cover direct sunlight more and is more efficient in humidity penetration.

• Journal of the Korean Society of Industry Convergence
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• v.9 no.4
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• pp.285-291
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• 2006

A traffic accident is occurred by unbalance of reciprocal action of driver, vehicle and road conditions. To prevent the traffic accident, rapid and perfect road improvement is needed. But most of road improvement plans have insufficient budget. So decision maker has to determine the priority to invest. A model in this study, analyzing the effect of road conditions to the traffic accident, helps to decide the priority in road improvement. This study considered five danger indices ; 1) traffic volume, 2) speed variance, 3) vehicle mixing rate, 4) curved line radius, and 5) difference between design speed and running speed. Danger rate composed by five indices can be a scale of priority of improvement. The model in this study didn't consider all of factors about traffic accident. But this study can propose the methodology for traffic safety policy. For deriving the model, this study used data from highways in Korea and United States. Therefore the model has to apply the highways only.

• Journal of the Korean Operations Research and Management Science Society
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• v.38 no.4
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• pp.1-9
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• 2013

We propose a heuristic algorithm for war-game model that is appropriate for warfare in which the maneuver of the attacker is relatively certain. Our model is based on a multi-weapon extention of the Lanchester's square law. However, instead of dealing with the differential equations, we use a multi-period linear approximation which not only facilitates a solution method but also reflects discrete natures of warfare. Then our game model turns out to be a continuous game known to have an ${\varepsilon}$-Nash equilibrium for all ${\varepsilon}{\geq}0$. Therefore, our model approximates an optimal warfare strategies for both players as well as an efficient reinforcement of area defense system that guarantees a peaceful equilibrium. Finally, we report the performance of a practical best-response type heuristic for finding an ${\varepsilon}$-Nash equilibrium for a real-scale problem.

• The Journal of the Korean dental association
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• v.51 no.9
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• pp.511-517
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• 2013

To assess the association between oral health and general health, this study examined the relationship between chewing difficulty and twelve chronic health conditions such as hypertension, hyperlipidemia, diabetes, cerebro- and cardiovascular disease, musculoskeletal disease, respiratory disease, eye/nose/throat disease, stomach/intestinal ulcer, renal dysfunction, thyroid disease, depression, and cancer in Korea. The study population was 3,066 elders aged 65 years old and more from the fourth Korean National Health and Nutrition Examination Survey. Chewing difficulty was measured on a 5-point Likert scale. Chronic conditions were assessed by self-reported questionnaire. Confounders were age, gender, education, income, smoking, drinking, and obesity. Chi-square test, general linear model, and multiple logistic regression model were done with complex sampling design. Musculoskeletal disease (adjusted odds ratio=1.33), respiratory disease (adjusted odds ratio=1.52), and cancer (adjusted odds ratio=1.58) were independently associated with chewing difficulty. Multiple chronic conditions with more than 4 chronic disease showed significant association with chewing difficulty (adjusted odds ratio=1.37).