• Journal of the Korean GEO-environmental Society
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• v.8 no.5
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• pp.5-14
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• 2007

The quantity of noxious wastes generated by the growth in industrialization and population in all over the world and its potential hazards in subsurface environments are becoming increasingly significant. The extraction of the contaminant from the soil and movement of the water are restricted due to the low permeability and adsorption characteristics of the reclaimed soils. Incorporated technique with PVDs have been used for dewatering from fine-grained soils for the purpose of ground improvement by means of soil flushing and soil vapor extraction systems. This paper is to evaluate several key parameters that affected to the performance of the PVDs specifically with regard to: well resistance of PVD, zone of influence, and smear effects. In the feasibility of contaminant remediation was evaluated in pilot-scale laboratory experiments. Well resistance is affected on the vertical discharge capacity of the PVDs under the various vacuum pressures. The discharge capacity increases consistently in areal extents with higher applied vacuum up to a limiting vacuum pressure. The head values for each piezometer at different vacuum pressures show that the largest head loss occurs within 14 cm of the PVD. Air flow rates and head losses were measured for the PVD placed in the model test box and the gas permeability of the silty soils was calculated. Increasing the equivalent diameter results in a decrease in the calculated gas permeability. It is concluded that the gas permeability determined over the 1,500 to 2,000 $cm^3/s$ flow rates are the most accurate values which yields gas permeability of about 3.152 Darcy.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.3
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• pp.1115-1122
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• 2013

Recently the demands for traffic information tend to increase, and travel time might one of the most important traffic information. To effectively estimate exact travel time, highly reliable traffic data collection is required. BIS(Bus Information System) data would be useful for the estimation of the route travel time because BIS is collecting data for the bus travel time on the main road of the city on real-time basis. Traditionally use of BIS data has been limited to the realm of bus operating but it has not been used for a variety of traffic categories. Therefore, this study estimates a route travel time on road networks in urban areas on the basis of real-time data of BIS and then eventually constructs regression models. These models use an explanatory variable that corresponds to bus travel time excluding service time at the bus stop. The results show that the coefficient of determination for the constructed regression model is more than 0.950. As a result of T-test performance with assistance from collected data and estimated model values, it is likely that the model is statistically significant with a confidence level of 95%. It is generally found that the estimation for the exact travel time on real-time basis is plausible if the BIS data is used.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.7
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• pp.773-778
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• 2015

Global warming has recently become an issue that has resulted in a growing trend to minimize environmental pollution. The International Maritime Organization (IMO) has shown that the majority of marine atmospheric pollution occurs as a result of emissions from marine vessels. Therefore, the environmental regulations and emission standards regarding marine vessels have gradually become stricter, and the research and development in this area is experiencing significant progress. In this study, a nozzle for a fuel oil scrubber was investigated using computational fluid dynamics (CFD) and particle imaging velocimetry (PIV). Experiments were conducted on scaled-down model of the scrubber to determine its performance, which was then compared with CFD results. Based on the experimental results, it was found that at a spray angle of $66^{\circ}$, the spray velocity at the nozzle was 20.1 m/s. From this comparison, a full-scale scrubber model was analyzed using CFD, and the effect of the positioning of the nozzle was studied.

• Transactions of the KSME C: Technology and Education
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• v.1 no.2
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• pp.199-204
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• 2013

In this paper, a new system requirement management tool and its application on the Urban Transit Maglev Project were introduced. In most R&D projects on complexity system such as transportation system, Systems Engineering(SE) activities are included on each project, and SE teams are using commercial computer-based tools to perform the SE activities. Even though SE tools help to manage huge data and documents on engineering efficiently, but well-designed functions of SE tools which support SE activities are not sufficiently used on the whole process of system engineering. In order to computer-based SE tools are to be effectively used on project management, most engineers who takes engineering and coordination roles, at least sub-project managers should be familiar to the tool and could be easily use it, but usability of commercial SE tools are very difficult for normal engineers with no experience on SE activities and SE tools. To overcome this difficulty, we developed a new system requirement management tool considering each user's scenario on using engineering tools. The developed tool could not cover whole SE processes, but designed to perform requirement engineering such as system requirements(SRs) management, specification management, traceability management, SRs' verification activity management and so on. All the entities on SR database are inter-connected by pre-recognized traceabilities, so even non-specialists on SE can easily browse the database and find entities concern, and linked information such as interacted entities, legal or engineering constraints, coordination documents, status of development and verification and so on. Also functions for SR verification tools, TPM(Technical Performance Measure) tools, DB searching tools with traceability, and report generation tools are included on the system.

• Journal of Korean Tunnelling and Underground Space Association
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• v.19 no.4
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• pp.567-576
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• 2017

In a performance-based design, the structural safety is estimated from pre- defined damage states and corresponding damage indices. Both damage states and damage indices are well defined for above-ground structures, but very limited studies have been performed on underground structures. In this study, we define the damage states and damage indices of a cut-and-cover box tunnel which is one of typical structures used in metro systems, under a seismic excitation from a series of inelastic frame analyses. Three damage states are defined in terms of the number of plastic hinges that develop within the structure. The damage index is defined as the ratio of the elastic moment to the yield moment. Through use of the proposed index, the inelastic behavior and failure mechanism of box tunnels can be simulated and predicted through elastic analysis. In addition, the damage indices are linked to free-field shear strains. Because the free-field shear strain can be easily calculated from a 1D site response analysis, the proposed method can be readily used in practice. Further studies are needed to determine the range of shear strains and associated uncertainties for various types of tunnels and site profiles. However, the inter-linked platform of damage state - damage index - shear wave velocity - shear strain provides a novel approach for estimating the inelastic response of tunnels, and can be widely used in practice for seismic designs.

• The Journal of the Korea Contents Association
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• v.20 no.2
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• pp.678-688
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• 2020

Occupational ethical awareness is a system of norms and standards of behavior and an important component of professionalism that affects organizational performance and commitment. The purpose of this study is to examine the mediating effect of professionalism on the relationship between job ethics and organizational commitment of civil servants. A survey was conducted on 300 central government officials with more than one year of employment. 261 copies were used for the final analysis. The results are as follows. First, the vocational ethics of civil servants had a significant effect on professionalism. The higher the years of service, the higher the level of ethics. Second, the work ethic of public officials had a significant effect on organizational commitment. These results can be interpreted as the internal commitment of civil servants to the state of work ethic. Third, the mediating effect of professionalism was verified in the relationship between public morality and organizational commitment. Based on these results, the public ethics of public servants are the basis for accepting public values and goals. Vocational expertise with embedded codes of conduct and value systems influences organizational commitment. As a practical implication for improving the ethical ethics of public officials, education programs for improving ethical consciousness according to job titles and duties were provided, and the ethical ethical competence was presented.

• THE INTERNATIONAL COMMERCE & LAW REVIEW
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• v.62
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• pp.3-32
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• 2014

Article 77 sets forth the principle of prevention applied in several legal systems. Under this principle the party threatened by ooss as a consequence of a breach of contract by the other party is not permitted to await passively incurrence of the loss and then sue for damages. He is obliged to take adequate preventive measures to mitigate his loss. If the injured party abstains from taking such excessive measures he will not be considered to have failed to mitigate the loss under Article 77. The sanction provided in Article 77 against a party who fails to mitigate his loss only enables the other party to claim reduction in the damages. The reduction in damages under Article 77 is equal to the amount by which the loss should have been mitigated if the injured party had taken reasonable measures to avert or to lessen it. The aim of Article 77 is to encourage mitigation of the loss. The duty to mitigate the loss applies not only to a breach of contract in respect of an obligation whose performance is currently due. but also to an anticipatory breach of contract under Article 71. Article 85 contemplates that the buyer is in delay in fulfilling the latter obligation, or else that he fails to pay the price when payment is to be made concurrently with delivery of the goods by the seller. In both these situations of default, the seller who is either in possession of the goods or otherwise able to control their disposition must take measures, reasonable in the circumstances, to preserve them. The right of retention of the goods y the seller exists until he is reimbursed by the other party for the reasonable expenses incurred. Article 87 and Article 88 of the Convention grant different rights to the party obligated to take steps to preserve the goods; Article 87 allows him to deposit them in the warehouse of a third person, and Article 88 to sell them by whatever means appropriate. A difference exists between paragraph Article 88 (1) which grants the right to sell, and paragraph (2) which imposes the duty to take reasonable measures to sell the goods.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.10
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• pp.817-822
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• 2017

The braking system is one of the most important components in vehicles and machines. It must exert a reliable braking force when they are brought to a halt. Generally, frictional heat is generated by converting kinetic energy into heat energy through friction. As the kinetic energy is converted into heat energy, high temperature heat is generated which affects the mechanical behavior of the braking system. Frictional heat affects the thermal expansion and friction coefficient of the brake system. If the temperature is not controlled, the brake performance will be decreased. Therefore, it is important to predict and control the heat generation of the brake. Various numerical analysis studies have been carried out to predict the frictional heat, but they assumed the existence of boundary conditions in the numerical analysis to simulate the frictional heat, because the simulation of frictional heat is difficult and time consuming. The results were based on the assumption that the frictional heat is different from the actual temperature distribution in a rotating brake system. Therefore, the reliability of the cooling effect or thermal stress using the results of these studies is insufficient. In order to overcome these limitations and establish a simulation procedure to predict the frictional heat, this study directly simulates the frictional heat generation by using a thermal-structure coupling element. In this study, we analyzed the thermo-mechanical behavior of a brake model, in order to investigate the thermal characteristics of brake systems by using the Finite Element method (FEM). This study suggests the necessity to directly simulate the frictional heating and it is hoped that it can provide the necessary information for simulations.

• The Journal of the Acoustical Society of Korea
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• v.32 no.6
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• pp.548-555
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• 2013

The localization of sources has a numerous number of applications. To estimate the position of sources, the relative delay between two or more received signals for the direct signal must be determined. Although the generalized cross-correlation method is the most popular technique, an approach based on eigenvalue decomposition (EVD) is also popular one, which utilizes an eigenvector of the minimum eigenvalue. The performance of the eigenvalue decomposition (EVD) based method degrades in the low SNR and the correlated environments, because it is difficult to select a single eigenvector for the minimum eigenvalue. In this paper, we propose a new adaptive algorithm based on Canonical Correlation Analysis (CCA) in order to extend the operation range to the lower SNR and the correlation environments. The proposed algorithm uses the eigenvector corresponding to the maximum eigenvalue in the generalized eigenvalue decomposition (GEVD). The estimated eigenvector contains all the information that we need for time delay estimation. We have performed simulations with uncorrelated and correlated noise for several SNRs, showing that the CCA based algorithm can estimate the time delays more accurately than the adaptive EVD algorithm.

• Journal of Navigation and Port Research
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• v.26 no.1
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• pp.146-151
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• 2002

Efficiency of dredging work depends on the types of equipment used, the sediments encountered, whether the work to be performed is new or for maintenance, pre and/or post hydrographic surveying and so forth. Among those, surveying accuracy which is directly determined by the control of the dredge's position and depth surveying accuracy being surveyed at the dredging point are important factors. The purpose of this study is to develop an integrated process management system for pump dredge. The system is composed of 4 sub-systems such as LADGPS for dredge positioning dredging point determination, tidal gauge and angular depth sensor for depth determination, and GIS and ENC process management. The process management system for pump dredge developed was installed on the pump dredge "EUNJIN PD-2" but is now producing work data for comparison with performance of the existing dredge. The data retrieved from the pump dredge process management system up to now shows similar result from the grab dredge management system which was developed previously. It is easy to operate, achieves good accuracy with only 45cm unevenness, reduces working perioa by 20 percint,. More precise evaluation of the system comes later after the dredging work is completed.completed.