• Journal of the Korean Geotechnical Society
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• v.16 no.2
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• pp.61-70
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• 2000

When clay foundations of embankments are treated with vertical drain, essentially, the strain occurs to vertical direction but the water flow is radial. The initial horizontal permeability and its variation with the vertical compression are key parameters for the choice of the type of drains, their spacing, and affect to the cost of the project. In this study, CRS consolidation test is performed to investigate the anisotropic characteristics of decomposed mudstone soil and direct permeability test is performed on the same specimens. The results of testing show that Ch is larger than Cv. specially, the Cv - $\sigma$v relationship for a soil sample is viewed from three different curve segments corresponding to overconsolidated, transition and normally consolidated states. The anisotropic ratio, rk(kh/kv) is 2.19. Coefficient of permeability in normally consolidated state is related to its void ratio and permeability parameter n. C can be determined from a linear plot of log[k(1+e)] versus log e. The slope, n, of graphs is the same, whereas the vertical intercept, log C, seems to vary somewhat for anisotropic.

• The Journal of Aerospace Industry
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• s.69
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• pp.88-98
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• 2007

서머타임은 1784년 벤자민 프랭클린에 의해 최초 제안된 이후, 제1차 세계대전중인 1916년 5월 1일 독일과 오스트리아에서 최초 도입되었고, 현재 전세계적으로 86개국 이상이 서머타임을 실시하고 있다. 우리나라의 경우 1948년 처음 도입하여 1960년까지 시행 하였으며, 이후 1987년 산업의 고도화와 올림픽 개최에 맞추어 동 재도를 재실시하였으나 여러가지 긍정적 영향에도 불구, 권위주의 정부의 국민의견 수렴이 없는 일방적 결정과 당시 미성숙된 노동자 근무여건, 특히 올림픽 경기의 외국 TV 방송시간에 맞추기 위한 올림픽용이라는 비판 등 국민적 거부감으로 시행 2년 후인 1989년 폐지되었다. 최근 사회적 여건의 성숙에 따라 서머타임 도입이 재 논의 되고 있으며, 서머타임이 도입될 경우 약 31만명의 외국인 관광객 추가 방한과 연간 약 4,340억원 이상의 추가 관광수입을 얻을 수 있을 것으로 예상된다. 특히 항공운송산업의 경우 100만명 이상의 국제선 탑승객 증가와 약 1,537억원의 항공운임 수입증가 효과를 거둘 수 있을 것으로 예상된다. 또한 항공운송산업 직접연관산업에서 약 400여명, 간접연관산업에서 3,000여명 등 항공운송산업 전체에서 총 3,400여명의 고용 효과를 유발할 것이다. 반면 서머타임 도입에 따라 CRS, GDS, 항공기 스케쥴, 운항·항행 시스템 및 각 공항별 Curfew 조정이 필요하나, 이미 전세계 항공 선진국 대부분이 수십여년간 서머타임을 도입하고 있어, 서머타임 도입에 따른 失이나 혼란보다는 得과 효용이 더 클 것으로 생각된다.

• Journal of Auto-vehicle Safety Association
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• v.6 no.2
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• pp.49-54
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• 2014

Development in vehicle industry could increase interest in children's safety recently. However the research of children safety is not being conducted as many as that of adult's. Especially the basic study for the vehicle crash on-board children was not much. This study focused on the effect of seatbelt anchorage points to evaluate children's safety in frontal crash. The current regulation of the seatbelt anchorage points is suitable for ranged from female 5% to male 95%. The assessment of children's safety at buckle up of no used CRS(child restraint system) was performed using frontal sled tests. The frontal crash pulse in sled tests was designed to the average of about 30 KNCAP frontal crash pulses. To reduce number of experiments, DOE is used. The Q6 child dummy and standard seat in UN R 129 were used. According to the analysis of test results, children's safety has been influenced by the points of seatbelt anchorage.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.12
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• pp.1662-1669
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• 2000

Various flame types are observed in a double concentric burner by varying equivalence ratio and flow rates in each tube. Observed flame types include bunsen-type flame, ring-shaped flame, outer lifted flame, inner lifted flame, and oscillatory lifted flame, The doman of existence of various flames is mapped with equivalence ratio and annular jet velocity. Each flame is investigated through direct photography and OH PLIF. As central air velocity increase, the blowout region is diminished and lifted oscillating flames are observed. Inner lifted flames are observed from bunsen flames or rich shaped flames by increasing central air velocity. For inner lifted flames, annular jet velocity, at flame liftoff decreases with increasing central air jet velocity. Axial velocity profile and temperature fie이 using LDV and CRS, respectively, for a typical inner lifted flame are also measured through which the role of tribrachial flame for stabilization in emphasized.

• Transactions of Materials Processing
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• v.9 no.4
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• pp.395-403
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• 2000

Formation of Shear Band under the adiabatic condition is widely observed In the engineering materials during rapidly forming process lot a thermally rate-dependent material. The shear band stems from evolution of a narrow region in which an intensive plastic flow occurs. The shear band often plays a role of a precursor of the ductile fracture during a forming process. The objective of this study is to investigate the localization behavior using numerical method. In this work, the implicit finite difference scheme is employed due to the ease of convergence and the numerical stability It is noted that physical and mechanical properties of materials determine how the shear band is formed and then localized. Material properties can be characterized with inertia number dissipation number and diffusion number. It is observed that the dimensionless numbers effect on localization. Using a parametric study, comparison was made between CRS-1018 steel with WHA (tungsten heavy alloy). The deformation behavior of material in this study include an isotropic hardening as well as thermal softening. Moreover, this study suggests that a kinematic hardening constitutive relation be required to predict a more accurate strain level at a shear band.

• Journal of Korean Society for Quality Management
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• v.38 no.2
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• pp.212-224
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• 2010

After the introduction of Volume-based Waste Fee System for municipal wastes, the disposal of food wastes became an issue in society. As this reason, recycling food wastes facilities play an important role such as converting of food waste into animal feed or composting of food waste. Therefore, there is need of efficiency measurement of the facilities to reduce the inefficiency of factors. The purpose of this paper is to make a reasonable suggestion for the improvement of inefficient recycling food wastes facilities. This paper assesses the relative efficiency of recycling food wastes facilities by examining the relationship between inputs and outputs in 41 facilities using data envelopment analysis(DEA). The result shows that 4 facilities whose values of CCR efficiency are 1, and 10 facilities whose values of BCC efficiency are 1, RTS indicates IRS of 17 facilities and CRS of 6 facilities.

• Journal of Information Technology Services
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• v.16 no.4
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• pp.1-13
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• 2017

This study examines how specific technology from Information and Communications Technology (ICT)-which plays a critical role in increasing productivity by promoting a spread of technology across the society though the use of big data, mobile or wearable devices-impacts of the productivity of society and productivity of added values, respectively. The impact of technology was studied from the perspective of efficiency levels of input. In order to provide an analysis, we have categorized ICT into 16 specific technologies and have set the number of companies and number of employees each as an input factor while setting the respective output and the output of added values as an output factor. Afterwards, we have applied data envelopment analysis (DEA) which is a form of nonparametric frontier analysis and measured the productivity and efficiency of added values for each technology. According to the analysis results, there were 2 technologies by the CRS standards, and 3 technologies by the VRS standards that showed relative efficiency levels. We have also presented some efficiency improvement strategies for specific technologies that revealed relative inefficiency and offered a reference set and projection point. In addition, we provide an analysis on scale efficiencies (SE), diminishing returns to scale (DRS), and increasing returns to scale (IRS) of each ICT.

• The Journal of the Korea Contents Association
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• v.8 no.8
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• pp.147-157
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• 2008

ERP is the general trend of industrial information system and many companies are introducing strategically to strengthen the competitive power. This paper analyzes the efficiency of introducing companies of ERP system using DEA model. We also suggest the introducing of ERP system which can be benchmarked based on analyzed information. We evaluate the CCR, BCC efficiency and RTS of 38 introducing companies of ERP system. The result shows that three enterprises whose values of CCR efficiency are 1, and seven enterprises whose values of BCC efficiency are 1. RTS indicates IRS of 22 companies. DRS of 2 companies and CRS of 4 companies.

• Journal of Navigation and Port Research
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• v.42 no.2
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• pp.143-152
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• 2018

Currently, there are very few papers that have examined the efficiency of Vietnamese ports. Of those that have, some of them take into account only a few container ports in Northern Vietnam. Others focus on comparing all types of ports in Vietnam with regard to the differences in efficiency scores when applying different methods to evaluate efficiency. However, there is no paper that specifically analyzes the efficiency of Vietnamese container ports throughout the country or that compares Vietnamese container ports with those of other countries in terms of efficiency. In order to provide more accurate and interesting information for container port authorities, in this study, 21 major Vietnamese container ports and seven major Korean container ports are selected and examined with regard to their levels of efficiency in 2016 using data envelopment analysis (DEA). This paper applies both constant return to scale (CRS) and variable return to scale (VRS) to explore the differences among overall technical efficiency, pure technical efficiency, and scale efficiency of the selected container ports. This study also indicate slacks and sets projections for inefficient ports.

• The Journal of Fisheries Business Administration
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• v.47 no.1
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• pp.63-86
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• 2016

The purpose of this study is to investigate production efficiency of Oceans and Fisheries Human Resources Development Programs Efficiency using Bootstrap-DEA. The study extracts 33 officials curriculum, 11 fisheries managers curriculum for its analytical. First, the study estimates technical, pure technical, and scale efficiency of each curriculums based on traditional DEA under the assumption of CRS and VRS. 8(official 7, managers 1) curriculums are identified as efficient DMUs under the CCR-model, and 13(official 10, managers 3) under the BCC-model. We provide inputs that allow inefficient curriculum to be efficient DMUs on a production frontier, and a reference set for their bench-marking. Second, rank test, Wilcoxon-Mann-Whitney test to find a statistical significance of heterogeneity existing in efficiences between Bootstrap-DEA tenical vs Bootstrap-DEA pure technical was no significant difference. We have identified that G10, 11, 12 13, 25, 31, 33, 39 curriculums are the most efficiently produced in the technical and pure technical efficiency. Also we managed to measure the inefficiency which exists in efficiently produced curriculums when estimating the bias corrected efficiency scores. In Technical efficiency, Operation and facility was significant at the 10%. In Pure technical efficiency, facility was significant at the 10%.