• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2006.11a
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• pp.624-627
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• 2006

This study is to establish the direction to produce owner's basic specifications (English version) necessary for producing project specifications available internationally in the projects to develop water resources. The principal conclusions of this study are as follows; (1) The original text necessary for producing the international owner's basic specifications should be specifications of one part between northern America and Europe. (2) The work break down structure of the international owner's basic specifications shall be conform to the international break down structure of specifications, and the MasterFormat(2004) of CSI is recommended. (3) The construction management methods, for example, as to standards, laws, and etc. in the international owner's basic specifications should be available internationally.

• The Journal of Fisheries Business Administration
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• v.45 no.2
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• pp.29-38
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• 2014

This study is to analyse the timing of the structural change of price volatility and the asymmetry of price volatility during the period before and after the timing of the structural change of price volatility using Jeju Farming Olive Flounder's production area market price data from January 1, 2007 to June 30, 2013. The analysis methods of Quandt-Andrews break point test and Threshold GARCH model are employed. The empirical results of this study are summarized as follows: First, the result of Quandt-Andrews break point test shows that a single structural change in price volatility occurred on May 4, 2010 over the sample period. Second, during the period before structural change, daily price change rate has averagely positive value which means price increase, but during the period after structural change daily price change rate has averagely negative value which means price decrease. Also, daily volatility of price change rate during the period before structural change is higher than during the period after structural change. This indicates that price volatility decreases after structural change. Third, the estimation results of Threshold GARCH Model show that the volatility response against price increase is larger during the period after structural change than during the period before structural change. Also the result shows the volatility response against price decrease is larger during the period after structural change than during the period before structural change. And, irrespective of the timing of structural change, price increase has an larger effect on volatility than price decrease. This means volatility is asymmetric at price increase.

• Elastomers and Composites
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• v.39 no.2
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• pp.95-104
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• 2004

New compounds were made using various NR/BR blend ratio and oil content to improve mechanical properties of rubber isolator at low temperature. Mechanical properties were investigated as a function of NR/BR blend ratio and oil content. Hardness and tensile modulus generally increased, but tensile strength and elongation at break decreased with increasing BR content. Hardness, tensile modulus and tensile strength decreased, but elongation at break were nearly the same with increasing oil content. The glass transition temperature of NR and BR were found to be $-50^{\circ}C$ and $-90^{\circ}C$ respectively based on the abrupt drops in storage elastic modulus and peak of loss factor. Two distinct transition temperature were observed in NR/BR blend compounds and each transition point was not affected by blend level indicating incompatible nature of NR/BR blend.

• Journal of Biosystems Engineering
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• v.41 no.4
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• pp.365-372
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• 2016

Purpose: Tea is the most frequently consumed drink worldwide, next to water. About 75% of the total world tea production includes black tea, and withering is one of the major processing steps critical for the quality of black tea. There are two types of tea withering methods: physical and chemical withering. Withering can be achieved by using tat, tunnel, drum, and trough withering systems. Of these, the trough withering system is the most commonly used. This study focuses on the different types of withering, their effect on the various quality attributes of tea, and other aspects of withering methods that affect superior quality tea. Results: During physical withering, tea shoots loose moisture content that drops from approximately 70-80% to 60-70% (wet basis). This leads to increased sap concentration in tea leaf cells, and turgid leaves become flaccid. It also prevents tea shoots from damage during maceration or rolling. During chemical withering, complex chemical compounds break down into simpler ones volatile flavor compounds, amino acids, and simple sugars are formed. Withering increases enzymatic activities as well as the concentration of caffeine. Research indicates that about 15% of chlorophyll degradation occurs during withering. It is also reported that during withering lipids break down into simpler compounds and catechin levels decrease. Improper withering can cause adverse effects on subsequent manufacturing operations, such as maceration, rolling, fermentation, drying, and tea storage. Conclusion: Freshly harvested leaves are conditioned physically and chemically for subsequent processing. There is no specified withering duration, but 14-18 h is generally considered the optimum period. Proper and even withering of tea shoots greatly depends on the standards of plucking, handling, transportation, environmental conditions, time, and temperature. Thus, to ensure consumption of high quality tea, the withering step must be monitored carefully.

• Journal of the Korean Wood Science and Technology
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• v.22 no.2
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• pp.46-53
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• 1994

This study was conducted to investigate a feasibility of manufacturing wood fiber thermoplastic composites and to evaluate their mechanical properties. Wood fiber as a potential reinforcing filler was compounded with two thermoplastics (polypropylene and high density polyethylene) in high intensity thermokinetic plastic mixer aided with a wetting agent. It was found that wood fiber thermoplastic composites could be manufactured by injection molding process. The tensile and flexural strength of injection molded specimens were improved greatly with increasing wood fiber concentration. Tensile and flexural modulus increased proportionately with wood fiber concentration. Wood fiber provided reinforcement with thermoplastics in terms of strength and modulus. However, the percent elongation at break and energy to break were reduced with increasing wood fiber loadings. Impact strength also showed similar trend.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.21 no.2
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• pp.41-47
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• 2021

Manufacturing is facing radical changes around the world. The manufacturing industry, which has been changing since Germany, is now being introduced, improved, and developed worldwide by manufacturers under the name of smart factory. By utilizing IT technologies such as artificial intelligence and cloud at the production site, the desire to break away from the past manufacturing environment is increasing. How these technologies will be efficient in the future, manufacturing worldwide now faces radical changes. The manufacturing industry, which has been changing since Germany, is now being introduced, improved, and developed worldwide by manufacturers under the name of smart factory. By utilizing IT technologies such as artificial intelligence and cloud at the production site, the desire to break away from the past manufacturing environment is increasing. Discussions continue on how these technologies can be used efficiently and effectively. Increasingly, the expansion of the range from factory areas to regions, countries, and around the world raises the need for international standards for interactions. In this paper, we propose a design and implementation method for managing facilities, sensors, etc. as assets and monitoring facility data collected through OPC UA.

• The Journal of the Convergence on Culture Technology
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• v.7 no.1
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• pp.211-215
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• 2021

The number of megacities are increasing, due to the global urbanization. Along with this change, climate change, social development and technology advance make the calamities complicated and more devastating. Especially, megacities are hyper-netted, hyper-connected and hyper-converged with population more than 10 million and their domain. When calamities break out, the damage will be aggravated for they lead to another ones. Since megacities are the center of politics, economics and culture of a nation. so when complex disaster break out in megacities, this may be developed to a peril to the national security. Therefore, pan-government effort must be concentrated in preparing abilities to forecast, react, rapid response and resilience.

• Nuclear Engineering and Technology
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• v.56 no.6
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• pp.2002-2010
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• 2024

Korea Atomic Energy Research Institute (KAERI) has operated an integral effect test facility, the Advanced Thermal-Hydraulic Test Loop for Accident Simulation (ATLAS), with reference to the APR1400 (Advanced Power Reactor 1400) for tests for transient and design basis accidents simulation. A test for a loss of coolant accident (LOCA) at the top of the reactor pressure vessel (RPV) had been conducted at ATLAS to address the impact of the loss of safety injections (LSI) and to evaluate accident management (AM) actions during the postulated accident. The experimental data has been utilized to validate system analysis codes within a framework of the domestic standard problem program organized by KAERI in collaboration with Korea Institute of Nuclear Safety. In this study, the test has been analyzed by using thermal-hydraulic system analysis codes, MARS-KS 1.5 and TRACE 5.0 Patch 6, and a comparative analysis with experimental and calculation results has been performed. The main objective of this study is the investigation of the thermal-hydraulic phenomena during a small break LOCA at the RPV upper head with the LSI as well as the predictability of the system analysis codes after the AM actions during the test. The results from both codes reveal that overall physical behaviors during the accident are predicted by the codes, appropriately, including the excursion of the peak cladding temperature because of the LSI. It is also confirmed that the core integrity is maintained with the proposed AM action. Considering the break location, a sensitivity analysis for the nodalization of the upper head has been conducted. The sensitivity analysis indicates that the nodalization gave a significant impact on the analysis result. The result emphasizes the importance of the nodalization which should be performed with a consideration of the physical phenomena occurs during the transient.

• Journal of the Korean earth science society
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• v.45 no.3
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• pp.203-213
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• 2024

This study aimed to investigate the seasonal patterns of multiple bar formation in summer and flattening in winter on the macrotidal Sinduri beach in Taean, and to understand the processes their formation and subsequent flattening. Beach profiling has been conducted regularly over the last four years using a VRS-GPS system. Surface sediment samples were collected seasonally along the transectline, and grain size analyses were performed. Tidal current data were acquired using a TIDOS current observation system during both winter and summer. The Sinduri macrotidal beach consists of two geomorphic units: an upper high-gradient beach face and a lower gentler sloped intertidal zone. High berms and beach cusps did not develop on this beach face. The approximately 400-m-wide intertidal zone comprises distinct 2-5 lines of multiple bars. Mean grain sizes of sand bars range from 2.0 to 2.75 phi, corresponding to fine sands. Mean sizes show shoreward coarsening trend. Regular beach-profiling survey revealed that the summer profile has a multi-barred morphology with a maximum of five bar lines, whereas, the winter profile has a non-barred, flat morphology. The non-barred winter profiles likely result from flattening by scour-and-fill processes during winter. The growth of multiple bars in summer is interpreted to be formed by a break-point mechanism associated with moderate waves and the translation of tide levels, rather than the standing wave hypothesis, which is stationary at high tide. The break-point hypothesis for multi-bars is supported by the presence of the largest bar at mean sea-level, shorter bar spacing toward the shore, irregular bar spacing, strong asymmetry of bars, and the 10-30 m shoreward migration of multi-bars.

• Journal of Sensor Science and Technology
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• v.4 no.4
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• pp.75-80
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• 1995

In order to fabricate the piezoelectric thin film of the PZT-PNN ternary compound, the metal alkoxides were used as starting materials. The electrical and crystalline properties of the thin film were evaluated. The X- RD study shows that the crystallization of the film is optimized at $550^{\circ}C$ of sintering temperature. According to the D-E hysterisis curve, the coercive field is 28.8 kV /cm, and the remanent polariztion is $18.3\;{\mu}C/cm^{2}$. The break down voltages of the thin films are $76.0\;{\sim}\;27.0\;MV/m$. When the sintering temperature is raised, the break down voltage is lowered. As a result of measuring the C-V characteristic curve of the ternary compound piezoelectric thin film, the relative dielectric constants are 406 for the composition (50:40:10), 1084 for the composition (50:30:20), 723 for the composition (45:35:20) and 316 for the composition (40:40:20).