• Journal of Navigation and Port Research
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• v.30 no.1 s.107
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• pp.97-104
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• 2006

Recently the first stage qf construction for Busan new port emerged over the sea surface at the north container terminal site. With this, there are lot of discussions and debates on increasing the water depth at the approaching channel and mooring basin from the existing 15m to 18m by dredging work in order to be able to serve 12,000TEU containership, and at the same time, correction to the reclamation plan of hinterland at the part of Undong Bay qf the new port site. Since the attack of typhoon 'Maemi' in 2003, it is expected that the design wave parameters for coastal and harbor structures in this area would be somewhat changed and so the extreme wave condition at each terminal and tranquility of berthing area does, and therefore, it is necessary to analyze the tranquility at each berth Hence in this study, we constructed a wave model for these conditions and performed simulation together with the circulation model simulation, compared with the field data collected The result showed the increase of the harbor response throughout the basin but not severe condition However, a certain location needs to be prepared for the rough sea condition when a severe typhoon hit the site.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.3 no.3
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• pp.1-7
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• 1983

In spite of extensive knowledge of the surface chemistry and the transport mechanism in filtration systems, there is still insufficient understanding of the physical characteristics of suspensions and the system components. Because of this, no filtration mechanisms are mathematically generalized to the full extent. The purpose of this paper is to propose experimental equations for the filtration process. using the tracer study in filter layer. Some of results are as follows. (1) The Volume of the specific deposit (${\sigma}$) in filtration was directly measurable using the tracer study without interrupting the filtration. (2) It was also confirmed that the head loss in filtration was greatly in fluenced by the micro-air babbles. (3) The correction coefficient(f) was introduced into the Kozeny-Carman equation in order to apply it for the clogging filter media. The coefficient(f) was experimentally obtained. The total head loss of the filter media is given by next equation. $${\frac{h}{h_0}}={\frac{1}{L}}{\int}^{z=L}_{z=0}f({\sigma})g({\varepsilon}_0,{\sigma})dz$$ $$f=aexp(-b{\sigma})$$ The above equation was applicable without regard to the variation of the suspension concentration, the filter medium diameter, the filter depth, the filtration velocity, and the amount of aluminum in all continuous filtration experiments. (4) The total head loss was graphically generalized assuming mathematical filtration models I II (see fig. 7,8) (5) The total head loss was obtained from the filtration model in the field filtration conditions. (see fig. 9,10)

• Journal of the Korean earth science society
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• v.22 no.1
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• pp.47-64
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• 2001

Water mass classification was conducted using the data of 1985 and 1986 in the East China Sea and the Korea Strait. Kuroshio water (type K) and mixed water (type I) were broadly distributed at 50 m depth in winter and spring, and mixed waters (type I to IV) were distributed in summer and autumn. At 100 m depth of the East China Sea, and mixed water (type I) was broadly distributed in winter and spring, and mixed waters (type I to III) were in summer, and type I was in autumn. Water mass in summer is the most influenced from the Chinese coastal water. In the Korea Strait, the Kuroshio water (type K) was the main water mass in winter and spring, and mixed waters (type I to IV) were in summer and autumn. If temperatures are corrected to remove the cooling effect from the atmosphere, the Kuroshiowater region was diminished, however the mixed water region was expanded in winter and spring. This shows that although the Kuroshio water appears to be a main water mass of the East China Sea and the Korea Strait in winter andspring, in reality the mixed water (type I) which is slightly changed from the Kuroshio water (type K) widely distributed. The tongue-shaped distribution of low density surface water indicates that the water mixed with the Chinese coastal water flows to the Korea Strait and the Okinawa in summer.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.36 no.3
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• pp.341-348
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• 2016

Harbor facilities require long-term durability and safety, and also maintain the performance requirement until the durability life. However, existing harbor facilities are becoming superannuated with durable years and durability is declined by erosion of the sea and damage from sea. In addition, harbor facilities will be in demand for the expansion of harbor and offshore structures with rising economic power by enhancement of domestic industry and increase of import and export. Therefore, in this study, two kinds of nondestructive test (NDT) techniques (schmidt rebound hammer and ultrasonic sensor) are verified for the effective maintenance of underwater concrete structures including harbor facilities. Sea field applicability of Schmidt hammer and ultrasonic sensor was verified by comparing field test result with sea field test result and also deduced the compressive strength estimation equation by depth of the water. On the basis of the sea field test result, compressive strength estimation equation which was deduced by multiple regression analysis indicated highest accuracy compared to other equations, especially it will be more likely to be used in underwater because of the depth of water correction. In the future, if schmidt hammer and ultrasonic sensor which were invented as waterproofing are used with ROV (Remotely Operated Vehicle), it will be possible to make a diagnosis of high reliability for underwater concrete structures and set up a ubiquitous concept of NDT system.

• Radiation Oncology Journal
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• v.8 no.1
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• pp.115-124
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• 1990

The characteristics of 23 MV photon beam have been presented with respect to clinical parameters of central axis depth dose, tissue-maxi mum ratios, scatter-maximum ratios, surface dose and scatter correction factors. The nominal accelerating potential was found to be $18.5\pm0.5$ MV on the central axis. The half-value layer (HVL) of this photon beam was measured with narrow beam geometry from central axis, and it has been showed the thickness of $24.5\;g/cm^2$. The tissue-maximum ratio values have been determined from measured percentage depth dose data. In our experimental dosimetry, the surface dose of maximum showed only $9.6\%$ of maximum dose at $10\times10\;cm^2$, 100 cm SSD, without blocking tray in. The TMR'S of $0\times0$ field size have been determined to get average $2.3\%$ uncertainties from three different methodis; are zero effective attenuation coefficient, non-ilnear least square fit of TMR's data and effective linear attenuation coefficient from the HVL of 23 MV photon beams of dual energy linear accelerator.

• The Journal of Engineering Geology
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• v.17 no.4
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• pp.511-516
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• 2007

Active method MASW(Multi channel Analysis of Surface Waves), which is one of the surface wave exploration methods, has the difficulties to supply enough shear wave velocity log, caused by short spread length and lack of low frequency energy. To make up this defect, the passive method MASW survey is taked and analysised in Daeku subway construction site, Jungpyung-dong Gyeongsan city. The passive method MASW using the microtremor, improve the quality of the overtone record by applying the azimuth correction caused offline sources. And combing with active overtone record which is acquired by same geometry has the benefits of improve shallow depth resolution and extend possible investigation depth. To take the optimized acquisition parameters, the 2m, 4m, and 6m geophone spacing is tested. And 2m spacing overtone image could make the reliable shear wave velocity log.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2005.10a
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• pp.117-124
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• 2005

Recently the first stage of construction for Busan new port emerged over the sea surface at the north container terminal site. With this, there are lot of discussions and debates on increasing the water depth at the approaching channel and mooring basin from the existing 15m to 18m by dredging work in order to be able to serve 12,000TEU containership, and at the same time, correction to the reclamation plan of hinterland at the part of Undong Bay of the new port site. Since the attack of typhoon 'Maemi' in 2003, it is expected that the design wave parameters for coastal and harbor structures in this area would be somewhat changed and so the extreme wave condition at each terminal and tranquility of berthing area does, and therefore, it is necessary to analyze the tranquility at each berth. Hence in this study, we constructed a wave model for these conditions and performed simulation together with the circulation model simulation, compared with the field data collected. The result showed the increase of the harbor response throughout the basin but not severe condition. However, a certain location needs to be prepared for the rough sea condition when a severe typhoon hit the site.

• Journal of Korean Society for Geospatial Information Science
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• v.21 no.4
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• pp.3-12
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• 2013

In order to evaluate dredging results scientifically the system which can manage and estimate working process by monitoring dredging process in real-time needs to be constructed. We constructed real-time dredging management system for guidance of a dredging vessel and for survey of dredging construction. This system was designed to have functions of dredger location by GPS, ship direction measurement by GPS/Gyroscope combination, Grab position measurement, dredging depth measurement and correction. In addition, we developed the programs for controlling and operating the constructed system. The system could induce the vessel to accurate position and conduct dredging according to plan and the effectiveness of the system was evaluated through the results of application to actual dredging construction site.

• Journal of Radiation Protection and Research
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• v.1 no.1
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• pp.22-30
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• 1976

The perturbation of dose distribution adjacent to cavities in high energy electron has shown that the percentage of dose increase varies markedly as a function of the build-up layer, the length and thickness of the cavities, and the electron energy. The dose distribution showed that cavities similar in size to those encountered in the head and neck measured by industrial film dosimetry and corrected by ionization chambers. The most increased doses by measuring are resulted in a localized dose of up to 130% of that measured at the depth of maximum dose within a homogeneous tissue equivalent phantom. The measured values and correction factors of dose perturbation due to air cavities showed in diagrams and would be summarized as follows. 1. In $8{\sim}12MeV$ electron beams, the most marked dose is observed when the build-up layer thickness is 0.5cm and cavity volume is $2{\times}2{\times}2cm^3$. 2. The highest dose point is located under cavity when the energy is increased and cavity length is longer. 3. The cavity length at which the maximum percentage dose occurs decreases with increasing energy. 4. The highest percentage cavity doses are obtained when the energy is high, the build-up layer is thin, the thickness of the cavity is large, and the length of the cavity is approximately 1 to 3cm. 5. The doses of upper portion of cavity are less than the standard dose distribution as 5 to 10%. 6. The maximum range of electron beam are extended as much as thickness of cavity. 7. A cavity having a length of 5cm closely approximates a cavity of infinite length.

• Journal of Periodontal and Implant Science
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• v.44 no.4
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• pp.201-206
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• 2014

Purpose: Aggressive periodontitis, especially in its severe form, was traditionally considered to have an unfavourable prognosis. It required a complex treatment and its stabilization was often achieved by surgical therapy. The aim of this study was to investigate the results of nonsurgical periodontal treatment in severe generalized forms of aggressive periodontitis. Methods: Patients with advanced generalized aggressive periodontitis were included in the study. Probing depth (PD) of pockets ${\geq}7mm$ and clinical attachment level (CAL) of sites with attachment loss ${\geq}5mm$ were measured at baseline before nonsurgical periodontal treatment, at re-evaluation, and after treatment. The following other parameters were recorded: resolution of inflammation and bone fill. We compared the baseline values with re-evaluation and posttreatment values using the Friedman test. The Wilcoxon test with the Bonferroni correction was used for both re-evaluation and posttreatment values. Results: Seven patients with 266 periodontal sites were examined. A significant difference was found between values, reported as medians with interquartile ranges, for PD at baseline (7.94 [7.33-8.19] mm) and both re-evaluation (4.33 [3.63-5.08] mm) and posttreatment (3.54 [3.33-4.11] mm) values (P=0.002). A significant difference was also found between values for CAL at baseline (9.02 [7.5-9.2] mm) and both re-evaluation (6.55 [6.30-6.87] mm) and posttreatment (6.45 [5.70-6.61] mm) (P=0.002). Inflammation was resolved and angular bone defects were repaired in all cases. Conclusions: These therapeutic results suggest that this form of periodontitis could have positive outcomes after nonsurgical periodontal treatment. The reparative potential of tissue affected by severe aggressive periodontitis should encourage clinicians to save apparently hopeless teeth in cases of this form of periodontitis.