• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.4
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• pp.34-43
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• 2012

The behaviors of the curved bridges which has been constructed in the RAMP or Interchange are very complicate and different than orthogonal bridges according to the variations of radius of curvature, skew angle and spacing of shoes. Occasionally, the camber of girder and negative reactions can be occurred due to bending and torsional moment. In this study, the effects on the negative reaction in the curved bridge were investigated on the basis of design variables such as radius of curvature, skew angle, and spacing of shoes. For this study, the twin-steel box girder curved bridge with single span which is applicable for the RAMP bridges with span length(L) of 50.0m and width of 9.0m was chosen and the structural analysis to calculate the reactions was conducted using 3-dimensional equivalent grillage system. The value of negative reaction in curved bridges depends on the plan structures of bridges, the formations of structural systems, and the boundary conditions of bearing, so, radius of curvature, skew angle, and spacing of shoes among of design variables were chosen as the parameter and the load combination according to the design standard were considered. According to the results of numerical analysis, the negative reaction in curved bridge increased with an decrease of radius of curvature, skew angle, and spacing of shoes, respectively. Also, in case of skew angle of $60^{\circ}$ the negative reaction has been always occurred without regard to ${\theta}/B$, and in case of skew angle of $75^{\circ}$ the negative reaction hasn't been occurred in ${\theta}/B$ below 0.27 with the radius of curvature of 180m and in ${\theta}/B$ below 0.32 with the radius of curvature of 250m, and in case of skew angle of $90^{\circ}$ the negative reaction hasn't been occurred in the radius of curvature over 180m and in ${\theta}/B$ below 0.38 with the radius of curvature of 130m, The results from this study indicated that occurrence of negative reaction was related to design variables such as radius of curvature, skew angle, and spacing of shoes, and the problems with the stability including negative reaction will be expected to be solved as taken into consideration of the proper combinations of design variables in design of curved bridge.

• Computational Structural Engineering
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• v.7 no.3
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• pp.95-103
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• 1994

The safety related components in the nuclear power plant should be designed to withstand the seismic load. Among these components the integrity of reactor internals under earthquake load is important in stand points of safety and economics, because these are classified to Seismic Class I components. So far the modelling methods of reactor internals have been investigated by many authors. In this paper, the dynamic behaviour of reactor internals of Yong Gwang 1&2 nuclear power plants under SSE(Safe Shutdown Earthquake) load is analyzed by using of the simpled Global Beam Model. For this, as a first step, the characteristic analysis of reactor internal components are performed by using of the finite element code ANSYS. And the Global Beam Model for reactor internals which includes beam elements, nonlinear impact springs which have gaps in upper and lower positions, and hydrodynamical couplings which simulate the fluid-filled cylinders of reactor vessel and core barrel structures is established. And for the exciting external force the response spectrum which is applied to reactor support is converted to the time history input. With this excitation and the model the dynamic behaviour of reactor internals is obtained. As the results, the structural integrity of reactor internal components under seismic excitation is verified and the input for the detailed duel assembly series model could be obtained. And the simplicity and effectiveness of Global Beam Model and the economics of the explicit Runge-Kutta-Gills algorithm in impact problem of high frequency interface components are confirmed.

• Korean Journal of Heritage: History & Science
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• v.53 no.2
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• pp.254-269
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• 2020

The purpose of this study is to propose guidance for wall renewal that is appropriate for an ancient city wall through application of advanced research and theories in wall design. It is a streetscape improvement project which forms part of the "Ancient City Image Finding Project". Study methods consist of advanced research classification, wall design theory contemplation, and analysis of the significance of designated ancient city areas and the "Ancient City Image Finding Project" status. Based on these methods, case study candidates were selected, case status and problems were identified, and improvement proposals were analyzed by comparing various features. Advanced wall research was classified into six categories including analysis of wall characteristics; wall design principle applications; wall structure, color, shape, and application; modern reinterpretation; palace walls; and house, temple, and village walls. The wall is an element of the streetscape improvement component of the "Ancient City Image Finding Project", with the characteristic of providing preceding experience in visual and cognitive awareness than interior structure. Case candidates for ancient city wall improvement are based on the composition distribution of the special conservation district in each ancient city as well as the conservation promotion district. Ultimately, the surrounding village of Gongju-si Geumseong-Dong Songsanri-gil, adjacent to the Royal Tomb of King Muryeong, was selected as the candidate. The "Ancient City Image Finding Project" of the surrounding village of Gongju-si Geumseong-Dong Songsanri-gil began with new Hanok construction. However, wall maintenance did not begin concurrently with that new Hanok construction. Support and maintenance took place afterwards as an exterior maintenance project for roadside structures. If the Hanok and wall were evaluated and constructed at the same time, the wall would have been built in unison with the size and design of the Hanok. The layout of the main building and wall of the Hanok is deemed to be a structure that is closed tightly because of its spatial proximity and tall height. Songsan-ri-gil's wall design should create a calm, subtle, and peaceful atmosphere with shapes, colors, and materials that express ancient city characteristics, but it is in an awkward position due to its sharpness and narrowness. The cause of the problem at Gongju-si Geumseong-dong Songsanri-gil, the case candidate, is that it is lacking significantly in terms of the aesthetic factors that traditional walls should possess. First, aesthetic consciousness seems to have disappeared during the selection and application process of the wall's natural materials. Second, the level of completion in design and harmony is absent. Maintenance guidance after analyzing the cause of problems in ancient city wall maintenance at Gongju-si Geumseong-dong Songsanri-gil, the subject area of research, is as follows: First, the Hanok design and layout of the wall and main gate should be reviewed simultaneously. Second, the one-sided use of natural stone wall in the Hanok wall design should be reexamined. Third, a permanent system to coordinate the opinions of citizens and experts during the planning and design phases should be employed. Fourth and finally, the Hanok's individuality shall be collectivized and its value as a cultural asset representing the identity of the community shall be increased.

• Journal of the Geological Society of Korea
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• v.54 no.5
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• pp.477-488
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• 2018

Fluid muds commonly occur in estuarine environments, but their ancient examples have rarely been studied in terms of depositional characteristics and processes. Cores of estuarine channel deposits of the Early Cretaceous McMurray Formation, Alberta, Canada show various mudstone layers that possess depositional characteristics of high clay-concentration flows. These mudstone layers are examined in detail through microscopic observation of thin sections and classified into three microfacies (<1 to 25 mm thick) on the basis of sedimentary texture and structures. Structureless mudstone (Microfacies 1) consists mainly of clay particles and contains randomly dispersed coarser grains (coarse silt to fine sand). This microfacies is interpreted as being deposited by cohesive mud flows, i.e., fluid muds, which possessed sufficient strength to support suspended coarser grains (quasi-laminar plug flow). Silt-streaked mudstone (Microfacies 2) mainly comprises mudstone with dispersed coarse grains and includes very thin, discontinuous silt streaks of coarse-silt to very-fine-sand grains. The texture similar to Microfacies 1 indicates that Microfacies 2 was also deposited by cohesive fluid muds. The silt streaks are, however, suggestive of the presence of intermittent weak turbulence under the plug (upper transitional plug flow). Heterolithic laminated mudstone (Microfacies 3) is characterized by alternation of relatively thick silt laminae and much thinner clay laminae. It is either parallel-laminated or low-angle cross-laminated, occasionally showing low-amplitude ripple forms. The heterolithic laminae are interpreted as the results of shear sorting in the basal turbulent zone under a cohesive plug. They may represent low-amplitude bed-waves formed under lower transitional plug flows. These three microfacies reflect a range of flow phases of fluid muds, which change with flow velocities and suspended mud concentrations. The results of this study provide important knowledge to recognize fluid-mud deposits in ancient sequences and to better understand depositional processes of mudstones.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.41 no.4
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• pp.347-355
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• 2021

During the earthquake, for multi-story structure, if the first floor is soft, the deformation will concentrate on that floor causing a serious damage to the column members which might leads to the collapse of the whole structure like Piloti structure during the Pohang earthquake in Korea. According to the 2016 National Disaster Management Research Institute's "Investigation of Seismic Reinforcement and Cost Analysis of Domestic Non-seismic Buildings", the rate of seismic resistance of private reinforced concrete buildings was 38.3 %. Among them, it was reported that the seismic-resistance ratio of the two to five-story structures was less than 50 %. Accordingly, the government is trying to improve the seismic rate through support projects, but the conventional seismic reinforcement methods are still expensive, and emergency construction is difficult. Therefore, in this study, the field applicability was evaluated by improving the reinforcement method using Velcro, which was developed through the research project of the Ministry of Land, Transport and Maritime Affairs in 2014. In order to improve the performance of the Velcro reinforcement method, introducing the initial tension of Velcro using high foaming rigid urethane filling between the Velcro and concrete of the columns was applied. Additionally, an experiment was conducted to evaluate the ductility of Velcro specimen from the concrete confinement effect. As a result, the ductility of the Velcro specimen was improved compare to Normal specimen. However, the energy dissipation capacity of VELCRO2 is better than VELCRO1, yet the maximum ductility of those two specimens did not show a significant difference. Therefore, the improvement of the internal filler material is still needed to have a better maximum ductility.

• Korean Journal of Heritage: History & Science
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• v.48 no.1
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• pp.62-79
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• 2015

The Stele for State Preceptor Doseon and Seon Master Sumi of Dogapsa Temple in Yeongam was erected in the fourth month of 1653. It was made with stone obtained from Yeosan(present-day Yeosan-myeon, Iksansi), and contains an inscription - engraved in the spring of 1651 - commemorating the two priests. The project to erect the monument was led by eminent monks, including Gakseong and Sucho, with the support of royal patrons and powerful statesmen including Prince Inpyeong(1622~1658). This monument is thought to be the first of its kind to have a capstone in the shape of a 'dragon loop' handle of the kind traditionally attached to the top of a temple bell. Stone stelae with a dragon-loop-shaped capstone continued to be used by the royalty and nobility of Joseon until the 18th century. The inscription engraved on the rear face of the monument reveals that it was made by Jo Mal-ryong, a renowned stonemason who worked on stone monuments and figures for royal tombs in the mid-Joseon period. He is known as the only stonemason to have been awarded the third highest rank(Jeong-sampum) of government, including the posts of Grand Master(Tongjeong Daebu) and General(Jeolchung Janggun), as recorded in the inscription. The monument corroborates the prevalent view that he was the creator of monumental capstones of the highest aesthetic merit in Joseon, and provides valuable insights about the leading artisans who produced monumental stones for royal tombs in the 17th century. This particular monument is highly regarded as a valuable historical relic because of the detailed information contained in the inscription, including the dates, work processes, patrons and artisans related with its creation, and because it features outstanding workmanship by some of the greatest artisans of the period. The monument also provides important clues about the transition from the Buddhist monuments created under the auspices of the royalty and nobility of mid-period Joseon to the symbolic stone structures and figures made for the tombs of royalty and nobility.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2019.04a
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• pp.21-22
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• 2019

Melanin is a mixture of pigmented biopolymers synthesized by epidermal melanocytes that determine the skin, eye, and hair colors. Melanocytes produce two different kinds of melanin, eumelanin (dark brown/black insoluble pigments found in dark skin and dark hair and pheomelanin (lighter red/yellow). The biological role of melanin is to prevent skin damage by ultraviolet (UV) radiation. However, the overproduction or deficiency of melanin synthesis could lead to serious dermatological problems, which include melasma, melanoderma, lentigo, and vitiligo. Therefore, regulating melanin production is important to prevent the pigmentation disorders. Myanmar has a rich in natural resources. However, the chemical constituents of these natural resources in Myanmar have not been fully investigated. In the effort to search for compounds with anti-melanin deposition activity from Myanmar natural resources, five plants were collected in Myanmar. Extracts of these collected five plants were tested for anti-melanin deposition activity against a mouse melanoma cell line (B16-F10) induced with ${\alpha}$-melanocyte-stimulating hormone (${\alpha}$-MSH) and 3-isobutyl-1-methylxanthine (IBMX), and their anti-melanin deposition activities were compared with the positive control, arbutin. Among the tested extracts, the CHCl3 extracts of the Premna serratifolia (syn: P. integrifolia) wood showed anti-melanin deposition activities with IC50 values of $81.3{\mu}g/mL$. Hence, this study aims to identify secondary metabolites with anti-melanin deposition activity from P. serratifolia wood of Myanmar. P. serratifolia belongs to the Verbenaceae family and is widely distributed in near western sea coast from South Asia to South East Asia, which include India, Malaysia, Vietnam, Cambodia, and Sri Lanka. People in Tanintharyi region located in the southern part of Myanmar utilize the P. serratifolia, Sperethusa crenulata, Naringi crenulata, and Limonia acidissima as Thanaka, traditional cosmetics in Myanmar. Thanaka is applied in the form of paste onto skins to make it smooth and clear, as well as to prevent wrinkles, skin aging, excessive facial oil, pimples, blackheads, and whiteheads. However, the chemical constituents responsible for their cosmetic properties are yet to be identified. Moreover, the chemical constituents of P. serratifolia was almost uncharacterized. Investigation of the P. serratifolia chemical constituents is thus an attractive endeavor to discover new anti-melanin deposition active compounds. The investigation of the chemical constituents of the active CHCl3 extract of P. serratifolia led to isolation of four new lignoids, premnan A (1), premnan B (2), taungtangyiol C (3), and 7,9-dihydroxydolichanthin B (4), together with premnan C (5) (assumed to be an artifact), one natural newlignoid,(3R,4S)-4-(1,3-benzodioxol-5-ylcarbonyl)-3-[(R)-1-(1,3-benzo dioxol-5-yl)-1-hydroxy methyl]tetrahydro-2-furanone (6), and five known compounds (7-11)1,2). The structures of all isolated compounds were determined on the basis of their spectroscopic data and by comparison with the reported literatures. The absolute configurations of 1-3 and 5 were also determined by optical rotation and circular dichroism (CD) data analyses1). The anti-melanin deposition activities of all the isolated compounds were evaluated against B16-F10 cell line. 7,9-Dihydroxydolichanthin B (4) and ($2{\alpha},3{\alpha}$)-olean-12-en-28-oic acid (11) showed strong anti-melanin deposition activities with IC50 values of 18.4 and $11.2{\mu}M$, respectively, without cytotoxicity2). On the other hand, compounds 1-3, 5, and 7 showed melanogenesis enhancing activities1). To better understand their anti-melanin deposition mechanism, the effects of 4 and 11 on tyrosinase activities were investigated. The assay indicated that compounds 4 and 11 did not inhibit tyrosinase. Furthermore, we also examined the mRNA expression of microphthalmia-associated transcription factor (MITF), tyrosinase (TYR), tyrosinase-related protein-1 (TRP-1), and tyrosinase-related protein-2 (TRP-2). Compounds 4 and 11 down-regulated the expression of Tyr and Mitf mRNAs, respectively. Although the P. serratifolia wood has been used as traditional cosmetics in Myanmar for centuries, there are no scientific evidences to support its effectiveness as cosmetics. Investigation of the anti-melanin deposition activity of the chemical constituents of P. serratifolia thus provided insight into the effectiveness of the P. serratifolia wood as a cosmetic agent.

• Korean Journal of Heritage: History & Science
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• v.42 no.3
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• pp.66-87
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• 2009

The definition of the structure of wooden chamber tomb(piled stone-type) is as follows. It is a tomb with wooden chamber, and stones were piled on top of the wooden chamber, and then a wooden structure was placed on top of the piled stones, and more stones were piled on top of the wooden structure, and sealed with clay. Of course this definition can vary according to periods, the buried, etc. Gyeongju-style piled stone type wooden chamber tombs have some distinguished characteristics compared to general definition of piled stone type wooden chamber tombs. Outside the wooden chamber, either stone embankments or filled-in stones were layed out, and pilet-in stones are positioned right above the wooden chamber, and almost every class used this type, and finally, it is exclusively found in Gyeongju area. First generations of this Gyeongju-style piled stone type wooden chamber tombs appeared in first half of 5th century. These tombs inherited characteristics like ground plan, wooden chamber, double chamber(inner chamber and outer chamber), piled stones, burial of the living with the dead, piled stones, from precedent wooden chamber tombs. However these tombs have explicit new characteristics which are not found in the precedent wooden chamber tombs such as stone embankments, wooden pillars, piled stones(above ground level), soil tumuluses. stone embankments and wooden pillars are exclusively found on great piled stone type above-ground level wooden chamber tombs such as the Hwangnamdaechong(皇南大塚). Stone embankments, wooden pillars, piled stones(above ground level) are all elements of building process of soil tumuluses. stone embankments support outer wall of above-ground level wooden chambers and disperse the weight of tumuluses. Wooden pillars functioned as auxiliary supports with wooden structures to prevent the collapse of stone embankments. Piled stones are consists of stones of regular size, placed on the wooden structure. And after the piled stones were sealed with clay, tumulus was built with soil. Piled stones are unique characteristics which reflects the environment of Gyeongju area. Piled stone type wooden chamber tombs are located on the vast and plain river basin of Hyeongsan river(兄山江). Which makes vast source of sands and pebbles. Therefore, tumulus of these tombs contains large amount of sands and are prone to collapse if soil tumulus was built directly on the wooden structure. Consequently, to maintain external shape of the tumulus and to prevent collapse of inner structure, piled stones and clay-sealing was made. In this way, they can prevent total collapse of the tombs even if the tumulus was washed away. The soil tumulus is a characteristic which emerges when a nation or political entity reaches certain growing stage. It can be said that after birth of a nation, growing stage follows and social structure will change, and a newly emerged ruling class starts building new tombs, instead of precedent wooden chamber tombs. In this process, soil tumulus was built and the size and structure of the tombs differ according to the ruling class. Ground plan, stone embankments, number of the persons buried alive with the dead, quantity and quality of artifacts reflect social status of the ruling class. In conclusion, Gyeongju-style piled stone type wooden chamber tombs emerged with different characteristics from the precedent wooden chamber tombs when Shilla reached growing stage.

• Journal of Korea Water Resources Association
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• v.52 no.10
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• pp.743-752
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• 2019

The flow in the meandering channel is characterized by the spiral motion of secondary currents that typically cause the erosion along the outer bank. Hydraulic structures, such as spur dike and groyne, are commonly installed on the channel bottom near the outer bank to mitigate the strength of secondary currents. This study is to investigate the effects of submerged vanes installed in a $90^{\circ}$ meandering channel on the development of secondary currents through three-dimensional numerical modeling using the hybrid RANS/LES method for turbulence and the volume of fluid method, based on OpenFOAM open source toolbox, for capturing the free surface at the Froude number of 0.43. We employ the second-order-accurate finite volume methods in the space and time for the numerical modeling and compare numerical results with experimental measurements for evaluating the numerical predictions. Numerical results show that the present simulations well reproduce the experimental measurements, in terms of the time-averaged streamwise velocity and secondary velocity vector fields in the bend with submerged vanes. The computed flow fields reveal that the streamwise velocity near the bed along the outer bank at the end section of bend dramatically decrease by one third of mean velocity after the installation of vanes, which support that submerged vanes mitigate the strength of primary secondary flow and are helpful for the channel stability along the outer bank. The flow between the top of vanes and the free surface accelerates and the maximum velocity of free surface flow near the flow impingement along the outer bank increases about 20% due to the installation of submerged vanes. Numerical solutions show the formations of the horseshoe vortices at the front of vanes and the lee wakes behind the vanes, which are responsible for strong local scour around vanes. Additional study on the shapes and arrangement of vanes is required for mitigate the local scour.

• Journal of Korean Society of Forest Science
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• v.100 no.4
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• pp.591-597
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• 2011

Forest carbon stock changes in a national forest were assessed by CBM-CFS3 model with different management scenarios to support decision making for a long term forest planning. Management scenarios were composed with 4 different levels of timber harvesting - current harvesting level (scenario1), 30% increment in each period (scenario2), 3 times increment (scenario3), and 5 times increment (scenario4). For each scenarios, changes in total carbon stocks, carbon stocks of each carbon pools, carbon stocks of harvested wood products (HWP) and age class structure were estimated over 100-year planning horizon. The estimated total carbon stock including HWP at the end of final period (100 years) was 433.1 tC/ha under scenario 1, but the age class structure has skewed right to the upper classes, which is not desirable for sustainable forest management. Under the scenario 4, however, the total carbon stock decrease to 385.5 tC/ha and the area of old growth forest show a significant decline. The estimated total carbon stock under scenario 2 and 3 were 411.7 tC/ha and 410.5 tC/ha respectively, and it was able to maintain the initial level of the forest carbon stocks during the planning horizon. Also the age class structures under the scenario 2 and 3 were evenly distributed from class 1 to class 8. Overall, scenario 2 and 3 were the most acceptable forest management options, in terms of carbon stock changes and age class structure.