• Journal of Korean Society of Steel Construction
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• v.20 no.6
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• pp.807-815
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• 2008

The brittle failure where is occurred the welding position of column-beam flange of WUF-B connection that consider about a seismic detail possess a superior ductility capacity before Northridge earthquake 1994, require newly study about WUF-B connection. SAC Steel Project suggests a seismic detail to FEMA-350 by supporting of FEMA. It revise shape of weld access holes of WUF-B connection, welding processand welding material etc, In spite of these revision, AISC Seismic Provisions (2005) prescribe WUF-B connection using an only OMF. Recently in Korea, as the earthquake of about seismic intensity 5 occur, the necessity of revision for connection seismic detail comes to the front in Korea and FEMA-350 connection seismic details are going to include in KBC-2008 as it is. In this study, two column-beam connection specimens were marked by using SM490, SN490 built-up H-section, and based on WUF-B detail prescription of FEMA350. The parameters of the specimens are types of steel (SM, SN), and evaluate the capacities of structure and seismic by experiment. Finally we confirm a superior ductility capacity aboutspecimens JB-1 and JB-2, using SM490 and SN490,and these specimens had sufficient OMF and SMF seismic capacity, as indicated in AISC Seismic Provisions (2005).

• Journal of Korean Society of Water and Wastewater
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• v.33 no.1
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• pp.9-16
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• 2019

The algal blooms in stagnant streams and lakes have caused many problems. Excessive algae leads to disturbance of ecosystem and overload of water treatment processes. Therefore, phosphorus(P), source of algal blooms, should be controlled. In this study, a filtration trench has been developed to convert dissolved phosphorus into hydroxyapatite(HAP) so that it could be crystallized on the surface of 'phosphorus removal granular material'; and residual particulate phosphorus could be removed by additional precipitation and filtration. The front and rear parts of filtration trench consisted of 'phosphorus removal granular material contact bed' and 'limestone filtration bed', respectively. As a result of the column test using phosphorus removal granular material and limestone serially, $PO_4-P$ was removed more than 90% when EBCT(empty bed contact time) of the contact bed was over 20 minutes; and T-P represented 60% of removal efficiency when total EBCT was over 1.5 hours. The results of column tests to figure out the sedimentation characteristics showed that more than 90% of particulate phosphorus could be removed within 24 hours. It was necessary to optimize the filtration part in order to increase removal efficiency of T-P additionally. Also, it was confirmed through the simulation of Visual MINTEQ that most of particulate phosphorus in the column tests is the form of HAP. Based on the results of the study, it could be suggested that the design parameters are over 0.5 hour of EBCT for phosphorus removal granular material contact bed and over 1.5 hours of EBCT for limestone filtration bed.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2019.11a
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• pp.150-152
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• 2019

In this study, the effects of the wave field changes due to the coastal structure on the hydrodynamic performance of the OWC wave energy, converter are analyzed using a three-dimensional numerical wave tank technique (NWT). The OWC device is simulated numerically by introducing a linear pressure drop model, considering the coupling effect between the turbine and the OWC chamber in the time domain. The flow distribution around the chamber is different due to the change of reflection characteristics depending on the consideration of the breakwater model. The wave energy captured from the breakwater is spatially distributed on the plane of the front of the breakwater, and the converted pneumatic power increased when concentrated in front of the chamber. The change of the standing wave distribution is repeated according to the relationship between the incident wavelength and the length of the breakwater, and the difference in energy conversion performance of the OWC was confirmed.

• Journal of Soil and Groundwater Environment
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• v.6 no.2
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• pp.3-13
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• 2001

It has been known that nonlinear characteristics of sorption affect the transport behavior of water soluble pollutants in soils. However detailed experimental studies have not been performed to verify the effect of non-linearity of adsorption isotherm on transport of chemicals in porous media. In this research, the distortion of breakthrough curves of a cationic surfactant (cetylpyridinium chloride, CPC) in a engineered stainless steel column packed with glass beads were investigated. Glass beads with about 110 $\mu\textrm{m}$diameter coated with a thin n-decane film were used as the media providing the sorption surface for CPC. The CPC adsorption isotherm on the surface of n-decane from aqueous solution was a typical Langmuir type. The breakthrough curve of CPC using step Input showed a late breakthrough on the front side and early breakthrough on the back side accordance to the shape of the isotherm. The retardation factor of CPC was found to be a strong function of the input concentration, which also a manifestation of the non-linearity of the isotherm. The retardation factors for the CPC with step input agreed with those of pulse input that the maximum concentrations are controlled to be the same as the step input concentrations. This results support the validity of the unproven field practices of using hydrogeotracers with non-linear adsorption isotherms to determine the hydrogeological parameters, e.g., NAPL saturation, air-water or NAPL-water interfacial areas.

• Explosives and Blasting
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• v.26 no.1
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• pp.23-37
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• 2008

The Dongdaemoon complex stadium is scheduled to remodelled into an international park, which will be named Design Plaza. The Dongdaemoon baseball field was constructed with Rahmen Structure which comprised beams, slabs and columns. In order to assure for viewing, the stadium was composed unusual structure that the height of the front column and the back column was designed differently. The bleachers was an upper arch form for viewing. The slab was not flat unliked the general infrastructure and tilted in stairway type for viewing. If we had applied the mechanical demolition method, we could have predicted several problems. Firstly, the stand could be unstable when the heavy equipment was to crush the reinforced concrete on the slab. Because the slab was not flat. Secondly, the construction expense and construction duration could be increase when the large equipment was to crush the reinforced concrete on the ground. Because the height of the stand was too high to crush on the ground so it needed to build a filling. Thus, we applied both the mechanical demolition method and explosives demolition method at the design stage. The result of explosives demolition was of complete success in terms of structural movement and controlled blasting noise and vibration. This case study provided a good example for a successful application of explosives demolition in urban areas.

• Ocean and Polar Research
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• v.45 no.3
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• pp.141-153
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• 2023

Biological pump processes generated by diatom production in the surface water of the Southern Ocean play an important role in exchanging CO₂ gas between the atmosphere and ocean. In this study, the biogenic opal content of the sediments was measured to elucidate the variation in the primary production of diatoms in the surface water of the Southern Ocean since the last glacial period. A piston core (COR-1bPC) was collected from the Conrad Rise, which is located in the Indian sector of the Southern Ocean. The sediments were mainly composed of siliceous ooze, and sediment lightness increased and magnetic susceptibility decreased in an upward direction. The biogenic opal content was low (38.9%) during the last glacial period and high (73.4%) during the Holocene, showing a similar variation to that of Antarctic ice core ΔT and CO₂ concentration. In addition, the variation of biogenic opal content in core COR-1bPC is consistent with previous results reported in the Antarctic Zone, south of the Antarctic Polar Front, in the Southern Ocean. The glacial-interglacial biogenic opal production was influenced by the extent of sea ice coverage and degree of water column stability. During the last glacial period, the diatom production was reduced due to the penetration of light being limited in the euphotic zone by the extended sea ice coverage caused by the lowered seawater temperature. In addition, the formation of a strong thermocline in more extensive areas of sea ice coverage led to stronger water column stability, resulting in reduced diatom production due to the reduction in the supply of nutrient-rich subsurface water caused by a decrease in upwelling intensity. Under such environmental circumstances, diatom productivity decreased in the Antarctic Zone during the last glacial period, but the biogenic opal content increased rapidly under warming conditions with the onset of deglaciation.

• Korean Journal of Heritage: History & Science
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• v.48 no.2
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• pp.120-141
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• 2015

This paper is a preliminary study of architectural characteristics of Jangdae (general's podium), which shows one of the technical changes in fortification of Joseon Dynasty. As a facility for commands of generals and training for officers and men, it was located inside a fortress. Although it is not certain when the first Jangdae was built, the number of them dramatically increased around 18th century. Since the top priority function of the Jangdae was the prospect, it was installed at the hilly spot with open architecture. In addition, the open structure of Eupseong fortress towers on the riverside banks could simultaneously offer the functions as viewing around and Jangdae. Since Jangdae was also a place for military drills and reviews of soldiers, a wide podium was positioned at the front to muster the soldiers. This feature was standardized in the space organization of Jangdae in Joseon, and a mere podium was installed unless the topographic restrictions allows enough space. On the other hand, as a place for a commander, the hierarchy of the Jangdae was revealed through a variety of architectural characteristics. The hierarchy was assigned to the commander's space through the altitude difference, and diverse ornaments were added to show a sense of class. The floor plan of the Jangdae building can be largely categorized into rectangle and square, and the typical sizes of the former are $5{\times}4$ Kans (traditional measuring unit between two columns) and $3{\times}2$ Kans. Out of these two types, buildings of $5{\times}4$ Kans were found in flat land and eupseong fortresses with large space, and the relatively smaller ones of $3{\times}2$ Kans in mountain fortresses. All buildings of square floor plan had $3{\times}3$ Kans style, and the center Kan was twice wider than the side Kan to make the central space wide. It seems that the purpose was to secure the interior space of the upper story because the center Kan accounts for the floor area of the upper story. Some Jangdae's had internal story to form overhead space. The multi-roofed tower style with eaves attached to the upper and lower story is found exclusively in Jangdae. The buildings shows the Onkanmulim style which extends Naejinju (inner column) of the lower story to be the Byeonju (outer column) of the upper story, and the log-framed floor in the upper floor was structured by inserting the Changbang (connecting beam) between the Naejinju's and joining the log frames. In addition, the towers in eupseong fortresses had log-framed floor in the upper floor by setting up the high Nuhaju (column underneath a roof) and joining Cheongbang to the upper part of the column while it cannot be regarded as multi-roofed because only the upper part has a roof.

• Journal of architectural history
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• v.10 no.3 s.27
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• pp.45-60
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• 2001

The Tongdo temple have been transformed continuously since its first establishment about 1300 years ago. Nevertheless three critical elements specified by 'Jajangyulsa', founder of the temple have not varied over the times but rather strengthened and strongly combined. All elements and doctrines of the religion coexist and form a harmony within the whole of the temple. This researcher examined what changes, or combinations, in spatial formation were sought for such unique structures of the Tongue temple by focusing mainly on the Sangrojun area of the temple to obtain the following findings. First. unlike a work by a Japanese researcher 'Sekino Tadashi', the east yard of the main building was found located on the section line which corresponded to the separation line of Yungkuncheokdo(營建尺度=measure running) from the edge of the Keumkangkyedan(金剛戒壇 =Buddhist platform) embankment to the corner column of the Kamrodang. This was confirmed as a result of the review of photos shown in [Chosun Kojukdobo]. Second, the number of stairs used for the Keumkangkyedan was thought to become three when the temple was firstly restored in 1379 as a result that this researcher reviewed Chinese literature 'DoSun' and [Kyedandokyung(戒壇圖經)], records by 'Lee saek' and 'Jung Shihan', studies of Yungkun measure and actual changes in the temple. Then the temple was forth restored in 1705 when the second of the stairs was changed in area and height and at the same time grounded hard for a space for a Buddhist service. Third, the roof of the main building was probably changed in shape during the Koryo period when the plane structure, furnish arrangement, emphasized front, stone lanterns of the building and political factors of that time were all considered. Fourth, the main building was Initially designed to provide a Buddhist sermon service which was assumedly followed by a similar service at a Keumkangkyedan. Thus the main building had a small window on the northern side which might be opened up to look out or otherwise go outside like a door. However, the window was probably locked up like a surrounding wall since the main building was entirely repaired after the end of Japanese invasion of Korea in 1592.

• Journal of Environmental Science International
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• v.14 no.11
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• pp.1063-1069
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• 2005

In order to investigate the distribution of suspended particulate matter of the surface water in the South Sea of Korea in early winter, the cruise results during 2 to 8 December 2004 were analyzed in relation to the hydrography. The front was formed along the line connecting between Tsushima and Cheju Islands, which divided the water into two water masses; the coastal water with for temperature and for salinity, and the Tsushima Warm Current Water with high temperature and high salinity. In the coastal water the suspended particulte matter was 5.0-6.5 mg/l, while in the oceanic water suspended particulate matter was 4.5-5.0 mg/l. The coastal water showed higher mixing effects, compared to the oceanic area where vertical stratification was clearly formed. These indicate that the distribution of suspended particulate matter was affected by the stratification or mixing of the water column. Also it is suggested that the mixing effects of sea surface cooling and rind play an important role on the distribution of suspended particulate matter in the South Sea of Korea in winter time.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.8
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• pp.1577-1584
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• 2002

This paper develops a finite element model for studying the occupant behavior and injury cofficients of a large-sized cab-over type truck. Since it does not have a room to absorb collision energy and deformation in front of the passenger compartment the deformation is directly transmitted to the passenger compartment. Moreover, since its steering column is attached on the frame, severe deformation of the frame directly affects on the steering wheel's movement. Therefore, if the occupant behavior and injury coefficients analysis is performed using a finite element model developed based on a sled test, it is very difficult to expect acquiring satisfactory results. Thus, the finite element model developing in this paper is based on the frontal crash test in order to overcome the inherent problems of the sled test based model commonly used in the passenger car. The occupant behavior and injury coefficients analysis is performed using PAM-CRASH installed in super-computer SP2. In order to validate the reliability of the developed finite element model, a frontal crash test is carried out according to a test method used fur developing truck occupant's secondary safety system in european community and japan. That is, test vehicle's collision direction is vertical to the rigid barrier and collision velocity is 45kph. Thus, measured vehicle pulses at the lower parts of the left and right B-pilla., dummy chest and head deceleration profiles, HIC(head injury criterial) and CA(chest acceleration) values, and dummy behavior from the frontal crash test are compared to the analysis results to validate reliability of the developed model.