• ALGAE
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• v.37 no.4
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• pp.293-299
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• 2022

To examine the effects of substratum types on the growth of Caulerpa okamurae, sand surface and sand burial experiments were conducted. Five assimilators (erect fronds) per replicate were cultured for 15 d on the surface of three different treatments: fine sand (200 ㎛), coarse sand (600 ㎛), and no sand (control). Also, three stolons and three assimilators were buried by fine grain or coarse grain sands and incubated for 15 d. In both experiments, other culture conditions included 25℃, 30 μmol photons m^-2 s^-1, and 16 : 8 h L : D (light : dark). In both experiments, stolon + assimilator-, assimilator-, and stolon-weights were measured. Relative growth rates (RGRs) of stolon + assimilator weights ranged from 0.43 to 1.95% d^-1 at no sand and fine sand treatment, respectively. RGRs for the weight of stolon + assimilator and new assimilators were significantly greater on the fine- and coarse sand surface than the control. In the burial experiments, RGRs of stolons (4.28% d^-1 at coarse sand and 5.57% d^-1 at fine sand, respectively) were significantly greater than those of assimilators (1.38% d^-1 at fine sand and 1.82% d^-1 at coarse sand, respectively). When stolons were buried, RGRs for assimilators were greater at the fine sand than at the coarse sand treatment. On the other hand, RGRs of buried assimilators for total frond weights and for newly produced stolons were significantly greater at the coarse sands than at the fine sands. In conclusion, C. okamurae grew well with all substrates of sands and showed better growth on fine sands than coarse ones. This result suggests that the growth of stolons and assimilators of C. okamurae is stimulated after stable attachment to the sand substrates by rhizophores. In addition, stolons showed higher growth rates than the assimilators in the sand burial states, indicating that stolons are more tolerant to low light than assimilators of C. okamurae.

• Journal of Ecology and Environment
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• v.47 no.2
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• pp.14-26
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• 2023

Background: An important consideration for the risk assessment of transgenic plants is their overwintering potential in a natural ecosystem, which allows the survival of the seed bank and may lead to seed reproduction. Here, we investigated the overwintering of sunflower (Helianthus annuus L.) seeds in the laboratory (temperatures: -5, -1, 5, and 10℃) and in the field (burial depth: 0, 5, 15, and 30 cm) as a case study to examine the invasiveness of transgenic crops. Results: Sunflower seeds germinated when incubated at 5℃ and 10℃ for 2, 4, 6, and 12 weeks but not when incubated at -5℃ or -1℃. However, the seeds incubated at -5℃ or -1℃ germinated when they were transferred to the optimal germination temperature (25℃). Up to 16.5% and 15.0% of seeds were dormant when cultured at sub-zero temperatures in a Petri dish containing filter paper and soil, respectively. In the field trial, soil temperature, moisture, and microbial communities differed significantly between soil depths. Germination-related microorganisms were more distributed on the soil surface. Seeds buried on the surface decayed rapidly from 4 weeks after burial, whereas those buried at depths of 15 cm and 30 cm germinated even 16 weeks after burial. No dormancy was detected for seeds buried at any depth. Conclusions: Although sunflower seeds did not overwinter in situ in this study, we cannot exclude the possibility that these seeds lie dormant at sub-zero temperatures and then germinate at optimal temperatures in nature.

• Korean Journal of Heritage: History & Science
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• v.55 no.1
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• pp.63-84
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• 2022

One of the ancient nomadic cultures, the Saka is generally regarded as an important intermediary in the ancient Eurasian cultural network. This study is the reinterpretation of the excavations conducted on the Katartobe tombs site of the Saka culture through a joint three-year-long project by the National Research Institute of Cultural Heritage in Korea in collaboration with the Cultural Heritage Research Institute under the National Museum of the Republic of Kazakhstan. The main discussion of the study deals with the burial rituals performed by the community who built the Katartobe tombs by the comparison and review of the various researches on the Saka tombs based on the archaeological artifacts discovered during excavation. The research has shown that the Saka tribes maintained the tradition of burying domesticated animals, such as horses, with its owner and performed burial rituals which often involved the use of fire. The archaeological remains of the Saka also show that the burial rituals like these formed the key aspect of their cultural heritage. The archaeological discoveries also show that the Saka mourners built wooden cists under a single mound when they needed to bury multiple corpses at once and sustained the practice of excarnation when burying the bodies of those who died in the different periods of time. Some burials included a tomb passage which was used not only for carrying the deceased but also for a separate burial ritual. The main discussion of this study also deals with the remnants of bones of animals buried with their deceased owners in the same kurgan, as well as the animal species and their locations in the kurgan, resulting in the discovery of diverse meanings connected with them. The pottery buried in the tombs were largely ceremonial offering vessels, just like others excavated at nearby Saka tombs and located around the buried corpse's head facing toward the west. The excavation of the tombs also shows that two vessels were arranged at the corners of the coffin where the feet are located, revealing the characteristic features of the burial practices maintained by the tribe who built the Katartobe tombs. It may be too early to come to a definite conclusion on the burial practices of the Saka due to the relative lack of research on the kurgans across Central Asia. Excavations so far show that the kurgans clustered in a single archaeological site tend to display differences as well as uniformities. In conclusion, the ancient Central Asian tombs need more detailed surveys and researches to be able to make strides in an effort to restore the cultural heritage of the ancient Central Asian tribes who played a crucial role in the Eurasian cultural landscape.

• Geomechanics and Engineering
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• v.22 no.1
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• pp.49-63
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• 2020

Studying the critical response characteristics of box culverts with diverse geometrical configurations under seismic excitations is a necessary step to develop a reasonable design method. In this work, a numerical parametric study is conducted on various soil-culvert systems, aiming to highlight the critical difference in the seismic performances between three- and four-sided culverts. Two-dimensional numerical models consider a variety of burial depths, flexibility ratios and foundation widths, assuming a visco-elastic soil condition, which permits to compare with the analytical solutions and previous studies. The results show that flexible three-sided culverts at a shallow depth considerably amplify the spectral acceleration and Arias intensity. Larger racking deformation and rocking rotation are also predicted for the three-sided culverts, but the bottom slab influence decreases with increasing burial depth and foundation width. The bottom slab combined with the burial depth and structural stiffness also significantly influences the magnitude and distribution of the dynamic earth pressure. The findings of this work shed light on the critical role of the bottom slab in the seismic responses of box culverts and may have a certain reference value for the preliminary seismic design using R-F relation.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.30 no.1
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• pp.139-147
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• 1997

Sediment transport around artificial habitat which is induced by the change ol flow due to installation of the structure plays a role not only as a defect function of subsidence and burial but also bottom-environment control function. This study examined the characteristics of local scouring and deposition with sediment sizes, current velocities and installation direction of artificial habitat in flow field. Resultant subsidence and burial processes are investigated and discussed with Reynolds number. Together with sediment number and dimensionless time elapse, prediction formulas are established by combining these relationships. Bottom control function as cultivating effects is discussed with installation direction, and applicability of countermeasures is compared and stone pavement method is recommended.

• Korean Journal of Environmental Biology
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• v.28 no.3
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• pp.150-157
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• 2010

Biodegradation behavior of poly(butylene succinate-co-butylene adipate) (PBSA) was examined when PBSA was buried in the natural soil and the soil inoculated with Burkholderia cepacia after sterilization. After 80 days of the soil burial test at room temperature, the PBSA film buried in the natural soil lost 34.0% of its intial weight, while the same film lost 59.2% of its initial weight when buried in the sterile soil inoculated with B. cepacia. The optical and SEM observations of the surface morphology of the PBSA film also indicated that the surface erosion and rupture took place faster when the film was buried in the sterile soil inoculated with B. cepacia compared to the film buried in the natural soil. Viable cell number in the natural soil and that the sterile soil inoculated with B. cepacia increased by a factor of 6~7 and 10~14, respectively as compared to the initial viable cell number.

• Journal of the Korean Society of Clothing and Textiles
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• v.30 no.4 s.152
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• pp.607-614
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• 2006

This study was carried out to suggest the optimal spinning process condition which provides a proper range of tenacity and biodegradability as textile fibers. The effects of the melt spinning speed and heat treatment on the mechanical property and biodegradability of polylactic acid fiber were investigated. Polylactic acid(PLA) was spun in a high spinning speed of $2000{\sim}4000m/min$. Each specimen was heat-treated at $100^{\circ}C$ during 30min. Mechanical properties such as breaking stress and the degree of crystallinity were evaluated using WAXS. Biodegradability was estimated from the decrease of breaking stress, weight loss, and the degree of crystallinity after soil burial. Experimental results revealed that heat treated specimens showed higher breaking stress than untreated specimens, but the increase was not so high as was expected from the remarkable change of crystallinity by heat treatment. It was concluded that breaking stress was more influenced by spinning speed than heat treatment. In the soil burial test, however biodegradability calculated from weight loss was more influenced by heat treatment than spinning speed.

• 보존과학연구
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• s.16
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• pp.59-111
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• 1995

Chemical composion and crystal form of Corrosion products found on archaeological iron objects were analyzed using X-ray fluorescence analysis, micro-X-ray powder diffraction analysis and ion chromatographic technique. The nature and behavior of the corrosion products were studied in order to aid in the conservation and restoration of burial iron objects. Twenty-two samples analyzed in this study were collected from iron object found in Korea and Japan. The corrosion products of iron objects from burial mounds contain $\alpha$-FeOOH, $\beta$-FeOOH, $\gamma$-FeOOH, $Fe_3O_4$and amorphous iron hydroxides. The content of $\alpha$-HeOOH is the greatest. Because, Ageing for long period should change the amorphous iron hydroxides is considerably less than that in usual atmospheric corrosion products. The concentration of chlorine and sulfine is remarkably variable ($Cl^-$ : 100- 30,000ppm, $SO_4^-2$ : 20-10,000ppm),but the reasons are unclear. The presence of generally high concentrations of chlorine and sulfine the corrosion products of iron objects seem to be influenced by the marine climatic condition. The presence of high chlorine and sulfine concentrations in the corrosion products of iron objects seem to be influenced by the marine burial environments.

• Geomechanics and Engineering
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• v.30 no.4
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• pp.383-392
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• 2022

Although pipelines are composed of segmental tubes commonly connected by rubber gasket or push-in joints, current studies mainly simplified pipelines as continuous structures. Effects of joints on three-dimensional deformation mechanisms of existing pipelines due to tunnel excavation are not fully understood. By conducting three-dimensional numerical analyses, effects of pipeline burial depth, tunnel burial depth, volume loss, pipeline stiffness and joint stiffness on bending strain and joint rotation of existing pipelines are explored. By increasing pipeline burial depth or decreasing tunnel cover depth, tunneling-induced pipeline deformations are substantially increased. As tunnel volume loss varies from 0.5% to 3%, the maximum bending strains and joint rotation angles of discontinuous pipelines increase by 1.08 and 9.20 times, respectively. By increasing flexural stiffness of pipe segment, a dramatic increase in the maximum joint rotation angles is observed in discontinuous pipelines. Thus, the safety of existing discontinuous pipelines due to tunnel excavation is controlled by joint rotation rather than bending strain. By increasing joint stiffness ratio from 0.0 (i.e., completely flexible joints) to 1.0 (i.e., continuous pipelines), tunneling-induced maximum pipeline settlements decrease by 22.8%-34.7%. If a jointed pipeline is simplified as a continuous structure, tunneling-induced settlement is thus underestimated, but bending strain is grossly overestimated. Thus, joints should be directly simulated in the analysis of tunnel-soil-pipeline interaction.

• Journal of The Geomorphological Association of Korea
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• v.25 no.3
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• pp.71-87
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• 2018

As part of further study on Gwangseungri coastal deposits which occurred at 10 ~ 15m above sea level and was analyzed as palaeo-coastal flood-type sediments, six burial ages of six additional samples from the two cross sections (KST1 and, KST2) near to the points of the past study were estimated and the geochemical analysis was performed. Further investigation on the cross section KST1 revealed a reversal of the burial age at the bottom of the section which was identified as palaeo-flooding sediments and supposed to have been buried about 350 years ago. At the lower part of the KST1, the burial age of the sediment layer was estimated to be 3,800 years. The lower part of KST2 sediments was identified as sediments that was formed about 6,600 years ago and about 20,000 years ago. Considering the inclination of the sediment layers, the coastal flooding sedimentsreported to have formed 700 years ago in the previousstudy are located at the top and the KST1 section analyzed in thisstudy seemed to be connected to the lower part. The chemical analysis showed that the relationship between these layers was not continuous but had a discontinuous characteristic influenced by a specific event, and the chemical composition also showed a rapid change. If we judge these together, the lowest part of Gwangseungrisediment layerseemed to have formed during the last glacial period but it was hard to find its origins clearly. On top of this layer, a fine sediment layer containing gravels was also formed.Itseemed thatsedimentation did not occur continuously, but was affected by temporary events in such a way that after a sediment layer was formed, it stopped. Since then, a coastal flooding event occurred about 700 years ago, and part of flooded sediments accumulated in the rear slope. After that, when a flood layer including additional granular materials about 350 years ago was formed, sedimentation along the slope seemed to have occurred.