• Proceedings of the Korea Concrete Institute Conference
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• 1996.10a
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• pp.394-400
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• 1996

Recently, the construction of infrastructures has been booming and acceleratin to keep up with rapid economic growth. Consturction activities and operation of transportation facilities caues unfavorable effects such as civil petitions associated with vibration-induced damages or nuisances. Vibration-controlled mixtures are latex, rubber powder and plastic resin, which have been deternimed to reduce vibration by and large reduce vibration. KS F2437 and travel time method have been used to figure out 1st natural frequency and dynamic elastic moduli. Dynamic damping ratios have been computed by adopting the polynomial curvefitting method and the geometric analysis method on the frequency spectrum curve, of which results have been compared and analyzed hereon.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2013.05a
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• pp.176-177
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• 2013

The composite PC rahmen structure, called Green Frame, allows the main structural members such as PC column and beam to be produced on the site, resulting in a reduction of PC member transportation cost and the margin of PC plant (operation cost and profit), making it more economic than the bearing wall structure. To apply the Green Frame to practice, not only installation but also insitu-production process should be considered. Therefore, this study analyse the influence factors on insitu-production and installation schedule of composite precast concrete members. The results shall be used as basic criteria on the planning of insitu-production and installation of Green Frame.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.35 no.9
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• pp.143-150
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• 2019

The purpose of this study was to propose how to determine the setting time related to the determination of the surface finish working time of the concrete using a Durometer, which is used as a rubber hardness meter. Two different types of Durometer were used to measure the setting time of the concrete. High flowing concrete with 40% of water to binder ratio was fabricated maintaining $600{\pm}100mm$ of slump flow. The test results indicated that the application of the Durometer resulted in a high correlation with the penetration resistance tester in both mortar and concrete. When measuring the setting time of the concrete, with properly used with Durometer, evaluation of the setting time of the concrete can be available. Therefore, it is thought that the measurement of the final set of the durometer C type can be useful to decide the limit time of the finishing operation and the time of the rejuvenation of the curing process by measuring the finishing set at 40 HD in the case of the initial set and 10 HD in the case of D type.

• The Journal of Korean Medical History
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• v.34 no.2
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• pp.45-63
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• 2021

This study considers the stages of curriculum development for the integrated curriculum of Pusan National University Graduate School & Hospital of Korean Medicine, and specifically the KAS2021 (announced in 2019), improvement measures for the curriculum of the College of Traditional Korean Medicine, and the case of the College of Medicine. The introduction of integrated curriculum in the College of Traditional Korean Medicine starts from the members (doers)' agreement. In the process of development, the organization that represents the members, the organization that sets up a goal and designs the curriculum, and the organization that executes them should fulfill their own roles. The stage of development and operation should have the support system for manpower, institution, administration, and finance. The curriculum (draft) should be concrete enough to be operated in reality. For the smooth operation of integrated education, it is necessary to secure more full-time teachers than before, and it is also necessary to have an organization fully in charge of monitoring and improving the operation. For the introduction and operation of integrated curriculum in Traditional Korean Medicine education, the members' agreement, institutional change, support system, and the cultivation of manpower for the operation/evaluation/development of curriculum should be considered.

• Journal of the Earthquake Engineering Society of Korea
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• v.6 no.1
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• pp.33-41
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• 2002

Recently, the seismic safety evaluation of concrete gravity dams is raised due to the damage or the failure of dams occurred by the 1995 Kobe earthquake, the 1999 Taiwan earthquake, etc. Failre of dam may incur loss of life and properties around the dam as well as damage to dam structure itself. Recently, there has been growing much concerns about 'earthquake-resistance' or 'seismic safety'of existing concrete gravity dams designed before current seismic design provisions were implemented. This research develops three evaluation levels for seismic safety of concrete gravity dams on the basis of the evaluation method of seismic safety of concrete gravity dams in U.S.A., Japan, Canada, and etc. level 1 is a preliminary evaluation which is for purpose f screening. Level 2 is a pseudo-static evaluation on the basis of the seismic intensity method. Finally, level 3 is a detail evaluation by the dynamic analysis. Evaluation results on existing concrete gravity dam on operation showed good seismic performance under the designed artificial earthquake.

• Journal of the Korean Society of Radiology
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• v.13 no.1
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• pp.73-80
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• 2019

Neutrons are generated by the nuclear reaction, which is absorbed into the concrete wall and causes the activation during cyclotron operation. The purpose of this study is to investigate the effect of neutron activation and radiative concrete on concrete type. This experiment used Monte Carlo simulation and RESRAD model. The results of the experiment showed that the higher the content of Fe in concrete, the greater the shielding rate. The effect of $^{56}Fe(n,\;2np)^{54}Mn$ reaction on workers is also increased. However, radioactive nuclides have low activity and have very low impact on workers. Radioactive concrete should be treated as general wastes with less than its self-disposal tolerance level, and it should be recycled to the surface such as road repair rather than landfill to minimize the effect of $^{14}C$.

• International Journal of Highway Engineering
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• v.17 no.4
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• pp.1-9
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• 2015

PURPOSES : The purpose of this study is to revise the weight to power ratio of the representative truck in S. Korea. So far, S. Korea has been using the unit lb/hp, and the construction machines were not considered in the evaluation of the performance of trucks. METHODS : This study was performed to recommend the use of ISO system of units, and to analyze the weight to power ratios of the representative trucks in S. Korea, including the dump trucks, concrete mixer trucks, and asphalt and concrete diffusers. RESULTS: From this study, the 85 percentile value of the weight to power ratio of the trucks in S. Korea's was found to be 103.6 kg/kw. CONCLUSIONS : The performance standard for the representative truck has to be increased upward, considering the travel pattern of the dump trucks, concrete mixers, and asphalt and concrete diffuser trucks, travel distances, narrow area (work zone) of operation, and the saving in construction budget for climbing lane. Based on this study, the weight to power ratio of the representative truck in S. Korea could possibly be revised to 100~110 kg/kW.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2004.06a
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• pp.43-51
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• 2004

In order to decommission the shielding concrete of KRR(Korea Research Reactor) -1＆2, it must be exactly determined activated level and range by neutron irradiation during operation. To determine the activated level and range, it must be sampled and analyzed the core sample. But, there are difficulties in sample preparation and determination of the measurement efficiency by self-absorption. In the study, the full energy efficiency of the HPGe detector was compared with the measured value using standard source and the calculated one using Monte Carlo simulation. Also. self-absorption effects due to the density and component change of the concrete were calculated using the Monte Carlo method. Its results will be used radioactivity analysis of the real concrete core sample in the future.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.113-116
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• 2003

To maximize the productivity in machining molds and dies, machine tools should operate at high speeds. During the high speed operation of moving frames or spindles, vibration problems are apt to occur if the machine tool structures are made of conventional steel materials with inferior damping characteristics. However, self-excited vibration or chatter is bound to occur during high speed machining when cutting speed exceeds the stability limit of machine tool. Chatter is undesirable because of its adverse effect on surface finish, machining accuracy, and tool lift. Furthermore, chatter is a major cause of reducing production rate because, if no remedy can be found, metal removal rates have to be lowered until vibration-free performances is obtained. Also, the resonant vibration of machine tools frequently occurs when operating frequency approaches one of their natural frequencies because machine tools have several natural frequencies due to their many continuous structural elements. However, these vibration problems are closely related to damping characteristics of machine tool structures. This paper presents the use of polymer concrete and sandwich structures to overcome vibration problems. The polymer concrete has high potential for machine tool bed due to its good damping characteristics with moderate stiffness. In this study, a polymer concrete bed combined with welded steel structure i.e., a hybrid structure was designed and manufactured for a high-speed gantry-type milling. Also. its dynamic characteristics were measured by modal tests.

• Smart Structures and Systems
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• v.17 no.4
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• pp.631-646
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• 2016

Although the deployment of wireless sensors for structural sensing and monitoring is becoming popular, supplying power to these sensors remains as a daunting task. To address this issue, there have been large volume of ongoing energy harvesting studies that aimed to find a way to scavenge energy from surrounding ambient energy sources such as vibration, light and heat. In this study, a magnetic resonance based wireless power transfer (MR-WPT) system is proposed so that sensors inside a concrete structure can be wirelessly powered by an external power source. MR-WPT system offers need-based active power transfer using an external power source, and allows wireless power transfer through 300-mm thick reinforced concrete with 21.34% and 17.29% transfer efficiency at distances of 450 mm and 500 mm, respectively. Because enough power to operate a typical wireless sensor can be instantaneously transferred using the proposed MR-WPT system, no additional energy storage devices such as rechargeable batteries or supercapacitors are required inside the wireless sensor, extending the expected life-span of the sensor.