• Korean Journal of Materials Research
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• v.11 no.7
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• pp.569-574
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• 2001

The crystal structure, surface morphology and preferred orientation of the copper electrodeposit were investigated by the using sulfate bath with $SiO_2$suspensions and the cathode substrate Au sputtered. As by the addition of colloidal silica in copper electrolytic bath and Au pre-coating on substrate, the crystal particles of deposits was fined-down, made uniform and the account of particles were increased. Hardness of copper electrodeposits with colloidal silica increased about 15% in comparison with that of pure copper deposit film and (111), (200) and (311) plane of X-ray diffraction patterns were almost swept away, so preferred orientation of the copper deposits changed from (111) to (110) plane by codeposit $SiO_2$ and precoating the substrate.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.23 no.1
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• pp.70-78
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• 2011

At Haeundae Beach in Busan, people were swept away by the fast-moving rip current and rescued, on August 13th and 15th, 2009 & July 29th and 30th, 2010. In predicting the wave-induced current and consequent tube movement for public safety, the coastal flows and waves are calculated at each time step and grid point by means of systematic interfacing of hydrodynamic and wave models (Lee, 2001). To provide a user-friendly simulation tool for end-users, the forecasting system has been built in a software package called HAECUM. Outputs from the system are viewed as graphs of tube positions with combined current vectors for easy decision of emergency management officials. The tube-wave interaction is taken into account and the traces of swim tube are simulated by using a Lagrangian random walk (Chorin, 1978; Lee, 1994). In this study, we use the Lee's approach (Lee, 1993) in estimating the surface onshore currents due to wave breaking.

• Journal of the Korean Society of Safety
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• v.25 no.3
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• pp.40-44
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• 2010

North Korea's discharge of water from a dam into the Imjin River that flows through the inter-Korean border swept away a riverside camping site early Sunday morning, killing six people. This tragic incident might have been prevented if the North had given prior notice of the release from its Hwanggang Dam to the South. Investigations are under way to determine the reasons behind the unexpected act. This incident was a man-made disaster not least death of six people. A water level monitoring system(WLMS) of the Imjin River was installed the bridge of Pilseung that operate three public institutions. The WLMS of the A institution set up warning siren and broadcasting as the water level has been rising the bridge of Pilseung in the Imjin River. But the A institution's system was already out of side before discharged of water a dam into the Imjin River and the operators were culpable negligence. The B institution's office employee on charges of negligence that might have contributed to the tragedy and one of the A institution's employees ignored 26 warning messages on the WLMS. This tragic incident was a man-made disaster not least death of six people and might have been prevented if the WLMS was normally operated and the system operators must be worked a tight.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.7 s.238
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• pp.828-836
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• 2005

Impingement/effusion cooling technique is used for combustor liner or turbine parts cooling in gas turbine engine. In the impingement/effusion cooling system, the crossflow generated in the cooling channel induces an adverse effect on the cooling performance, which consequently affects the durability of the cooling system. In the present study, to reduce the adverse effect of the crossflow and improve the cooling performance, circular pin fins are installed in impingement/effusion cooling system and the heat transfer characteristics are investigated. The pin fins are installed between two perforated plates and the crossflow passes between these two plates. A blowing ratio is changed from 0.5 to 1.5 for the fixed jet Reynolds number of 10,000 and five circular pin fin arrangements are considered in this study. The local heat/mass transfer coefficients on the effusion plate are measured using a naphthalene sublimation method. The results show that local distributions of heat/mass transfer coefficient are changed due to the installation of pin fins. Due to the generation of vortex and wake by the pin fin, locally low heat/mass transfer regions are reduced. Moreover, the pin fin prevents the wall jet from being swept away, resulting in the increase of heat/mass transfer. When the pin fin is installed in front of the impinging let, the blockage effect on the crossflow enhances the heat/mass transfer. However, the pin fin installed just behind the impinging jet blocks up the wall jet, decreasing the heat/mass transfer. As the blowing ratio increases, the pin fins lead to the higher Sh value compared to the case without pin fins, inducing $16\%{\~}22\%$ enhancement of overall Sh value at high blowing ratio of M=1.5.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.14 no.6
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• pp.71-85
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• 2011

In Okdong coal mine abandoned area, every year large amount of mine wastes have been swept away due to heavy rains in summer. Because pH of coal-mine waste is in the early 4, plant naturally does not grow there due to unfavorable condition for growing plant. This study had an experiment to grow plant for 6 months using Mycorrhizae which can be adapted well in acid soil. As a result of Experiment, In the infected experiment pot, 90% of the plants survived but in case of uninfected experiment pot, only 25% were alive. From Growth Experiment, it appeared that average stem length increase (cm/month), average fresh weight increase ($g^{fw}/month$), average dry weight increase ($g^{dw}/month$) were increased by 60%, 21%, 31% respectively. Especially, Mycorrhizae plays an important role in providing nutrients and water when seeding are established. Mycorrhizae prevents death caused by lack of nutrients and water and helps growth and development of plant when seeding are established in the early stage. This study proved that Mycorrhizae is comparatively effective in plant growth and prevention of erosion in coal-mine abandoned area.

• Korean Journal of Materials Research
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• v.11 no.5
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• pp.413-418
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• 2001

We investigated change of crystal structure, surface morphology and crystal orientation of the electrodeposited film from dispersed $SiO_2$ suspensions (colloidal silica) copper sulfate bath and arse corrosion potentials and physical specific properties. As addition of colloidal silica in copper electrolytic hath, the crystal Particles on filial was fined-down, made uniform and account of particles were increased. Hardness of copper electrodeposited film ascended about 15% and (111), (200) and (311) plane of X-ray diffraction patterns were almost swept away, so preferred orientation chanced from (111) to (110) plane. Also, corrosion potential of electrodeposited copper film was noble with colloidal silica addition.

• 한국해양학회지
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• v.1
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• pp.49-55
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• 1971

After the heavy precipitation from April 1969 to September 1970, more than 1.359 10$\^$6/㎥ of fresh water was discharged through diversion channel of the Namgang Dam. The sands and muds in the northern Sachon Bay were moved and swept away by the strong southsard flow which was observed to be speedier than five knots. The shellfish culture facility as well as the oysters and bivalves were buried. In Sachon Bay, a southward surface ebb current of approximately one knot stratifies above the northward flow of approximately 0.5 knot, which seems to be similar to the salt wedge estuary. The stratified current is responsible for the breaking of the gill nets and other fishing gears. The salinity of sea water in Chinju Bay decreased remarkably and the abnormal low salinity water lower than 5 was distributed in Sachon Bay. The low salinity water front was observed in eastern Chinju Bay and the Samchonpo Channel, where the salinity was increased from 4.6 to approximately 30 within half a tidal cycle. These caused the oysters and bivalves die, and drove anchovies and octopus out to the sea and prevented them from approaching the bay. The decrease of salinity causes the decrease of density and osmotic pressure of sea water. Turbid water would prevent the sunlight from penetrate into deep layer.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.1
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• pp.98-115
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• 2012

New trend called ubiquitous leads the recent business by standardization and integration. It should be the main issue how to guarantee the integration and accountability on each business, especially in mission critical system which is mainly supported by M2M (Machine to Machine) control mechanism. This study is from the analysis of digital forensics case study that is from the M2M Sensing Control Mechanism problem of the "Imjin River" case in 2009, where a group of family is swept away to death by water due to M2M control error. The ubiquitous surroundings bring the changes in the field of criminal investigation to real time controls such as M2M systems. The needs of digital forensics on M2M control are increasing on every crime scene but we suffer from the lack of control metrics to get this done efficiently. The court asks for more accurately analyzed results accounting high quality product development design. Investigators in the crime scene need real-time analysis against the crime caused by poor quality of mission critical systems. It seems to be every need of Real-Time-Enterprise, so called ubiquitous society on the case. We try to find the efficiency and productivity in discovering non-functional design defects in M2M convergence products focusing on three metrics in study model with quick implementation. Digital forensics system in present status depends on know-how of each investigator and is hard to expect professional analysis on every field. This study set up a hypothesis "Co-working of professional investigators on each field will qualify Performance and Integrity" especially in mission critical system such as M2M and suggests "Online co-work analysis model" to efficiently detect and prevent mission critical errors in advance. At the conclusion, this study proved the statistical research that was surveyed by digital forensics specialists around M2M crime scene cases with quick implementation of dash board.

• Journal of the Korean Institute of Landscape Architecture
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• v.40 no.2
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• pp.112-129
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• 2012

The aim of this study was to provide basic data in managing the project that was carried out on Bulgwangcheon in a nature-friendly way to improve the conditions around the areas, which was brought to completion in 2002, based on changes in ecological characteristics. For this propose, this study examined documents related to the project, compared physical and enviromnental changes before and after the project was conducted and analyzed changes in the stream ecosystem. The result showed that in areas that effluent water was often observed, especially when it rained, the river wall was washed away and vegetation was found damaged. As for actual vegetation, this study compared planting coverage of each section of the research area and actual vegetation charts. The results indicated that Lespedeza spp., Aster koraiensis among mixed seeds that were planted in the reservoir path were almost swept away while Festuca arundinacea dominated the areas. Phragmites communis, Miscanthus sacchariflorns and Salix gracilistyla which had been planted in a small number were also almost washed out though a small number of them were left to form a colony. After examining the topography and structure of the plant community, this study found that areas where mixed seed were planted had changed into two types of vegetation: First type of area is dominated by P and R which are usually raised in apron with abundant floating particles. The second type of area is dominated by dry gramineous plant such as F and A. Areas around low flow channel where Phragmites communis, Miscanthus sacchariflorus and Salix gracilistyla planting construction method is applied was washed away with the width of low flow channel reduced. Though P, M and S formed a small community in some areas around the low flow area, they were in small number and in composition of simple plant species. Two ways were suggested in this study to manage the stream in an ecological way. First, adequate revetment construction methods should be applied by monitoring the flow of the stream as well as considering the flood control of urban streams. Second, target vegetation communities that are suitable for the environment of the stream should be chosen and be plantedconstantly with high density. At the same time, ornamental native plants shouldn't be planted as they have been and disturbing vegetation should be removed.

• Journal of the Korean Geotechnical Society
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• v.28 no.7
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• pp.5-16
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• 2012

Soil-nailing is the most popular method of reinforcing for slope stability. In general, two factors are considered as failure modes during the soil-nailing design stages: pullout failure mode and shear failure mode that will occur on the most probable failure plane. In many cases, however, shallow failure can also occur when the ground near the slope face is swept away by the horizontal stress release during the staged top-down excavation. In this paper, an optimized soil-nailing design methodology is proposed by considering the three failure modes mentioned above: pullout failure; shear failure; and shallow failure. The variables to be optimized include the bonded length and number of soil-nailings, and the confining pressure that should be applied at the slope face. The procedure to obtain the optimized design variables is as follows: at first, optimization of soil-nailings, i.e. bonded length and number, against pullout and shear failure modes; and then, optimization of confining pressure at each excavation stage that is needed to prevent shallow failure. Since the two processes are linked with each other, they are repeated until the optimized design variables can be obtained satisfying all the constrained design requirements in both of the two processes.