• Advances in aircraft and spacecraft science
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• v.1 no.2
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• pp.197-218
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• 2014

Quite a demanding task frequently arises in space engineering, when dealing with the cargo accommodation of modules and vehicles. The objective of this effort usually aims at maximizing the loaded cargo, or, at least, at meeting the logistic requirements posed by the space agencies. Complex accommodation rules are supposed to be taken into account, in compliance with strict balancing conditions and very tight operational restrictions. The context of the International Space Station (ISS) has paved the way for a relevant research and development activity, providing the company with a remarkable expertise in the field. CAST (Cargo Accommodation Support Tool) is a dedicated in-house software package (funded by the European Space Agency, ESA, and achieved by Thales Alenia Space), to carry out the whole loading of the Automated Transfer Vehicle (ATV). An ad hoc version, tailored to the Columbus (ISS attached laboratory) on-board stowage issue, has been further implemented and is to be used from now on. This article surveys the overall approach followed, highlighting the advantages of the methodology put forward, both in terms of solution quality and time saving, through an overview of the outcomes obtained to date. Insights on possible extensions to further space applications, especially in the perspective of the paramount challenges of the near future, are, in addition, presented.

• Journal of the Korean Society of Hazard Mitigation
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• v.8 no.1
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• pp.39-45
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• 2008

The most important elements in flexible pavement design criteria are stress and strain distributions. To obtain reasonable stress and strain distributions in pavements, moving wheel loads must be applied to analyze the pavement responses. In this study, finite element analysis was used to identify the three-dimensional states using the vehicle load into a constant-position / time-variable load (25, 50 and 80km/hr). In an elastic system, the strain is the same in both longitudinal and transverse directions under a single wheel. However, the same is not necessary in a viscoelastic system. Test results showed that the maximum values between transverse and longitudinal strains the bottom of asphalt concrete base layers under 25km/hr were were about 40 percent.

• Journal of Korean Society of Transportation
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• v.15 no.1
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• pp.175-192
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• 1997

첨단 교통정보 시스템(ATIS)의 핵심요소라고 할 수 있는 동적경로안내 시스템 (Dynamic Route Guidance System)은 운전자가 목적지에 도착하기까지 실시간 교통정보를 토대로 최적경로를 안내해줌으로써 날로 심화되고 있는 교통혼잡을 최소화 할 수 있으리라 기대를 모으고 있다. 특히 교통사고나 긴급 도로공사 등으로 인해 발생하는 돌발적 교통혼잡하에서는 DRGS의 역할이 더욱 커질 것으로 예상되고 있다. 본 논문은 돌발적 교통혼잡하에서 보다 효과적인 DRGS의 경로안내 전략을 수립하고 평가하는데 그 목적이 있다. 이를 위해 우선 하부구조기반 DRGS와 개인차량기반 DRGS의 장단점을 비교하고 시스템 아키텍쳐와 경로안내전략의 관계를 규명하였다. 또한 효율적인 경로안내를 위해 사용자평형 (User Equilibrium) 경로안내전략과 시스템 최적화(System Optimal) 경로안내 전략을 이상형교통망 (Idealized Network)을 통해 비교 분석하였다. 그리고 돌발적 교통 혼잡하에서 사용자평형 경로 안내를 사용할 경우 야기될 수 있는 Braess Paradox 문제와 시스템 최적경로안내를 사용할 경우 일어날 수 있는 사용자 호응도(User Compliance) 문제를 동시에 감안한 적응 형 경로안내 전략을 개발하였다. 이 방법은 위의 경로 안내 전략들이 가지고 있는 장단점을 상황에 따라 평가하여 경로안내 전략을 선택하는 과정을 수행시간을 절약하지 못할 것으로 평가되면 사용자 호응도를 고려하여 사용자 평형 전략을 선택하도록 하였다. 돌발적 교통 혼잡하에서 통행 시간을 동적으로 예측하기 위해서는 이산 확정적 대기행렬모형 (Discrete Deterministic Queueing Model)이 적용되었다. 한편, 적응형 전략의 효율성을 평가하기 위 해 이상형교통망과 실제 미국 Virginia 주의 Fairfax Country에 소재한 주간 고속도로 66번 과 인접 교통망을 대상으로 각종 돌발교통혼잡상황을 전제로 한 Traffic Simulation과 정보 제공 시나리오를 INTEGRATION Model을 사용하여 실행하였다. 그 결과 적응형전략이 단지 사용자평형 경로안내전략만 사용하는 경우에 비해 교통 혼잡도와 유고상황의 체류정도에 따라 3%에서 10%정도까지 전체통행시간을 절약할 수 있다는 결론을 얻었다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.9
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• pp.4169-4182
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• 2011

Dynamic development of the Information Communications and Technology is changing countries around the world to establish the e-government to enhance their national administrative system efficiently. This paper proposes the method to implement the e-government efficiently in the developing countries. To reach the goal, the e-government development indices evaluated by United Nations are analyzed to catch the clues to take-off the e-government development stage. In addition, we scrutinize the e-Government Master Plans of Mongolia, Kyrgyzstan and Nepal supported by Korea in order to elicit the priority projects which are the indispensible components on the way of building e-government. We cross-check and standardize the projects which the investigation target countries define respectively. We also analyze the projects which are evaluated by their priorities in compliance with the portfolio method to elicit the road map of the optimum which is able to implement the e-government efficiently with reducing trials and errors.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.18 no.3
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• pp.46-57
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• 2019

Generally speeding appeared to be the most contributing factor of fatalities occurred in work zones, and highway agencies in South Korea have concerned of the safety of workers and drivers in the poor circumstances. In this study, a portable variable message signs (PVMS) system as an alternative of control speeding in work zones was implemented. This study evaluated the safety effectiveness of the PVMS based on speeds and the compliance with the speed limit. Linear regression and logistic regression models were adopted to quantify the safety effect of the PVMS between the 'before' and 'after'. The results showed that most of points had statistically significant speeds reduction experience after PVMS installation. Also, the percentage of vehicle exceeding the speed limit by 10 km/h or more was decreased significantly between 50 and 80% in the 'after' periods compared to the 'before' periods. Therefore, the PVMS would be contributed to benefit safety in work zones which there is a difference in design speed of the adjacent normal section.

• Journal of the Korea Society for Simulation
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• v.30 no.1
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• pp.43-54
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• 2021

Since COVID-19 (Severe acute respiratory syndrome coronavirus type 2, SARS-Cov-2) was first discovered at the end of 2019, it has spread rapidly around the world. This study introduces an agent-based simulation model representing COVID-19 spread in South Korea to investigate the effect of detect level (contact tracing) on the virus spread. To develop the model, related data are aggregated and probability distributions are inferred based on the data. The entire process of infection, quarantine, recovery, and death is schematically described and the interaction of people is modeled based on the traffic data. A composite logistic functions are utilized to represent the compliance of people to the government move control such as social distancing. To demonstrate to effect of detect level on the virus spread, detect level is changed from 0% to 100%. The results indicate active contact tracing inhibits the virus spread and the inhibitory effect increases geometrically as the detect level increases.

• Environmental and Resource Economics Review
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• v.32 no.3
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• pp.149-166
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• 2023

The emissions trading system, introduced to reduce greenhouse gas emissions, experienced a sharp increase in emission allowance prices during the second plan period (2018-2020), which led to an increase in the demand for smooth supply and demand of emission allowances, while suppliers anticipating a shortage of emission allowances in the future did not participate in trading. Therefore, the authority temporarily revised the guidelines to ensure that the amount of allowances carried forward is proportional to the trading volume as a market stabilization measure. Through an optimization process using a dynamic nonlinear mathematical model, this paper analyzes the impact of the government's intervention on the carryover policy on GHG emission reductions and emission allowance market prices. According to the simulation analysis results, banking regulations could cause a decline in prices during the regulation period, even though the initial policy was predicted to be adopted.

• Journal of Korean Society of Steel Construction
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• v.19 no.6
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• pp.751-760
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• 2007

The purpose of this study is to evaluate the seismic performance of the frame which is assumed to be used with Welded Unreinforced Flange-Bolted web (WUF-B) connections and detailed in compliance with FEMA 350 recommended seismic design criteria. In FEMA 350, these types of connections are only valid for Ordinary Moment-Resisting Steel Frames (OMRSFs). For this purpose, based on test results, we proposed an analytical model for the Post-Northridge WUF-B connections with different panel zone strength ratios. Using the connection model, SAC Phase II three and nine-story frames were modeled and analyzed. From a nonlinear static pushover analysis, ductility, maximum strength, and the maximum interstory drift ratio were investigated for buildings with Post-Northridge details. Moreover, the maximum interstory drift ratio of each performance level (IO and CP) was also investigated through Incremental Dynamic Analysis (IDA). Analytical results were compared with those of buildings with either Pre-Northridge connection or ductile connections with no fracture. The analytical results showed that buildings with Post-Northridge WUF-B connections provide superior strength and interstory drift ratio capacity than buildings with Pre-Northridge WUF-B connections.

• Journal of the Society of Naval Architects of Korea
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• v.30 no.3
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• pp.116-126
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• 1993

The finite element method(FEM) has been commonly used for structural dynamic analysis. However, the direct global application of FEM to large complex structures such as ships and offshore structures requires considerable computational efforts, and remarkably more in structural dynamic optimization problems. Adoption of the component-mode synthesis method is an efficient means to overcome the above difficulty. Among three classes of the component-mode synthesis method, the free-interface mode method is recognized to have the advantages of better computational efficiency and easier implementation of substructures' experimental results, but the disadvantage of lower accuracy in analytical results. In this paper, an advanced method to improve the accuracy in the application of the free-interface mode method for the vibration analysis of large complex structures is presented. In order to compensate the truncation effect of the higher modes of substructures in the synthesis process, both residual inertia and stiffness effects are taken into account and a frequency shifting technique is introduced in the formulation of the residual compliance of substructures. The introduction of the frequency shrift ins not only excludes cumbersome manipulation of singular matrices for semi-definite substructural systems but gives more accurate results around the specified shifting frequency. Numerical examples of typical structural models including a ship-like two dimensional finite element model show that the analysis results based on the presented method are well competitive in accuracy with those obtained by the direst global FEM analysis for the frequencies which are lower than the highest one employed in the synthesis with remarkably higher computational efficiency and that the presented method is more efficient and accurate than the fixed-interface mode method.

• The Korean Journal of Physiology
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• v.15 no.1
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• pp.27-36
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• 1981

Relatively little has been done on the metabolic changes of the lung produced by the excessive alcohol ingestion to the point of the acute alcohol intoxication. In the present study, an effort was made to clarify the possible changes of the pulmonary surfactant system by the acute alcohol ingestion. The dynamic pulmonary compliance and the levels of protein and inorganic phosphorus (Pi) of both lung lavage and extract were chosen as the parameters of the pulmonary surfactant activities. The albino rats of both sexes were used, and 1.5 ml of 50% ethanol per 100 g body weight was given by oral intubation, and the experiment was performed at 1, 3, 6, 12, and 24 hours after the alcohol ingestion. The rat was sacrificed by cutting the carotid arteries, and blood sample for the determination of hematocrit(Hct) and the blood alcohol concentration was obtained. Both lungs were completely removed without dammage to the lung tissue, and the pulmonary compliance was measured by the changes of pressure-volume(P-V) curves by inflating or deflating the lung with air. Immediately after the P-V curves were recorded, the lung lavage was obtained by washing the lobes with 15ml of isotonic saline 3 times with a syringe. Next, total lungs were homogenized and filtered to obtain the lung extract. The protein and Pi levels were measured using the lung lavage and extract as the samples, and the lung/body weight ratio(L/B ratio) was also calculated. The results thus obtained were compared with the normal values and summarized as follows. The blood alcohol concentration reached the highest level of $0.71{\pm}0.02\;g\;%$ at 1 hr and gradually decreased until 24 hrs$(0.36{\pm}0.02\;g%)$ after the alcohol ingestion, but all the experimental groups showed significant increase comparing with the normal. The highest Hct value was obtained at 1hr$(64.86{\pm}2.45%)$ and significantly elevated value was continued throughout the experiment. The L/B ratio was significantly lowered from 3hrs until 24hrs after the alcohol ingestion but from 6 th hr on, a generally elevated value was observed with a significant value at 12 hrs and gradual recovery to the normal value at 24 hrs after the alcohol ingestion. The pulmonary compliance at inflation and deflation did not change appreciablly from the normal until 3 hrs after the alcohol ingestion but from 6 th hr on, a generally elevated value was observed with a significant value at 12 hrs and gradual recovery to the normal value at 24 hrs after the alcohol ingestion. The protein level of the lung lavage stowed a significantly increased value of $12.36{\pm}0.35\;mg/gm(3rd hr)$, $12.70{\pm}0.74\;mg/gm(12 th hr)$, and $12.65{\pm}0.88\;mg/gm(24 th hr)$, respectively, comparing with the normal value of $10.65{\pm}0.62\;mg/gm$, and the Pi level also showed a similar tendency of significant increase at 12th hr $(7.65{\pm}0.63\;{\mu}mol/gm)$ and 24 th hr$(6.70{\pm}0.36\;{\mu}mol/gm)$ comparing with the normal value of $5.32{\pm}0.20\;{\mu}mol/gm$. The protein level of the lung extract in the alcohol group was generally similar to the normal value with a slight decrease at 1st and 3 rd hr, tut the Pi level of the lung extract was generally increased in the alcohol group, and a significant increase was observed at 6 th hr$(17.77{\pm}1.54\;{\mu}mol/gm)$, 12 th hr$(13.92{\pm}0.78\;{\mu}mol/gm)$ and 24 th hr$(14.57{\pm}0.53\;{\mu}mol/gm)$ of the alcohol ingestion comparing with the normal value of $10.34{\pm}0.37\;{\mu}mol/gm$. From the above, it may be concluded that the acute alcohol intoxication produces the metabolic changes of the lungs by the increased surfactant activities and elevated pulmonary compliance.