• Journal of Korean Society of Transportation
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• v.17 no.1
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• pp.131-139
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• 1999

The quality of progression at signalized intersection has the largest potential effect. TRANSYT-7F is widely used to estimate the signal progression delay, but the progress of collecting and executing the compute program appears to be rather cumbersome. The research is to develop the analytical and progressing platoon delay model that is as simple as the methodology of HCM and familiar with the output of simulation model. The general approach to this research was conducted to examine the Rouphail and NCHRP 339 methodology together with the existing progression delay model (TRANSYT-7F. HCM). The scope is contained to be applicable only to cycles with no overflow queue and to obtain a comprehensive evaluation of the effects of changes in the quality of traffic signal progression on stopped delay and to be analyzed a simple mathematical method. The principle assumption for this model is that secondary flows is dispersed and partly mixed with average flow of the primary progressed flow. A second assumption is that through flow is consisted with the part of saturation flow at the front of it and the part of average flow at the rear of it. The delay equations vary for two arrival. The conclusion of this study could be summarized as 1)The evaluation of this model was consistently similar to that of TRANSYT-7F, 2) Platoon pattern has the real traffic flow characteristics. 3) The computing process of progression delay is made to have simple logic and easy calculation by integration, 4) This model could be estimated to be applied in almost all case.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.4
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• pp.326-335
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• 2014

Aerodynamic characteristics of the small two-stage turbo blower were investigated using commercial CFD tool(ANSYS CFX Ver. 14.5) in this paper. Turbo blower, which is a centrifugal type of turbomachinery, is used in various industries. It is used for application that required high static pressure rising at relatively small volumetric flow rate. In order to understand the mechanism of static pressure rising, the aerodynamic characteristics of the small two-stage turbo blower are analyzed at high rotating speed in this study. The k-${\omega}$ SST turbulence model, which is good at prediction of adverse pressure gradient flows, was applied. The CFD results of the turbo blower are validated by performance test. The static pressure rising of the turbo blower is nonlinearly increased over the first stage and the second stage. The secondary flow occurred at guide vanes, between the casing and the first impeller shroud, and the bottom of the impeller disk. As a result, It is required that whole fluid area is analyzed to predict aerodynamic characteristics of small two-stage turbo blower. and the result should be selected with considering for error from experiment and CFD.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.5
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• pp.326-334
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• 2012

To determine the concentrations and the mass flow of selected 10 perfluorinated compounds (PFCs), a field study was conducted in a wastewater treatment plant. Raw influent, primary influent, primary effluent, aeration tank effluent, secondary effluent, final effluent, dehydration liquor, primary sludge, thickened sludge, final sludge were collected over 3 days in the summer and the winter respectively. Collected samples were equally mixed and then served as an analytical sample. Total 10 compounds were analyzed. In terms of treated water, the concentration of perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA) were in range of N.D.~26.29 ng/L and N.D.~38.15 ng/L respectively. Perfluorononanoate (PFNA) and perfluorohexanesulfonate (PFHxS) were ranged from N.D. to 36.79 ng/L and from N.D. to 24.36 ng/L. In terms of sludges, a concentration of PFOS, PFOA, and perfluorodecanesulfonate (PFDS) were detected from 6.82 to 59.37 ng/g, from 0.13 to 0.37 ng/g, from N.D. to 0.83 ng/g respectively. Mass loading for PFCs increased during wastewater treatment except for PFNA. The observed increase in mass flow of PFCs may have resulted from biodegradation of precursor compounds.

• Archives of design research
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• v.20 no.1 s.69
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• pp.5-20
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• 2007

The aim of this research is to find out the flows of mega-trends and design trends by analyzing the factors that influence trend and design trends in the late 20th century. Moreover, it is to forecast and recommend design color trends by evaluating color trends in design trends for the near future. Secondary and primary research were used in parallel. In the late 20th century, mega-trends were analyzed from secondary research based on PEST. Design trends were analyzed from case studies in fashion, space, product and visual design. On this basis, design color trends were analyzed. Also, color trends were forecast for the near future. The results are as follows. Firstly, the main trends in the late 20th century were 'female thinking', 'back to the nature' and 'heaven of peace'. Second, main design trends in the 1970s were modernism, post-modernism and high-tech. In the 1980s, with those of the 1970s, ecology was introduced In the late 1980s. In the 1990s, modernism rose again and ecology had an influence. The trends of 'female thinking' and 'back to the nature' controled the design in the early 2000s. Third, design colors in the late 20th century changed from Red to Purple Blue. Tones changed from 'grayish' to 'dull' Finally, it was forecast that Purple Blue, Yellow Red and Green colors with 'grayish', 'dull' and 'deep' tones were going to be used mainly in the near future. Also, achromatic colors with female and warm nuances would be reflected in design parts. This research will be very useful in that it has built a concrete database reflected on design trends forecasting in the near future by organizing academically a methodology to identify trends reflected on design and identifying relation between mega-trends and design trends based on analyzing factors that influence trend.

• Journal of the Korean earth science society
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• v.32 no.7
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• pp.832-859
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• 2011

The importance of scientific education on accurate oceanic currents and circulation has been increasingly addressed because the currents have played a significant role in climate change and global energy balance. The objectives of this study are to analyze errors of the oceanic current maps in the textbooks, to discuss a variety of error sources, to suggest how to produce a unified oceanic current map of the East Sea for the students. Twenty-seven textbooks based on the 7th National Curriculum were analyzed and quantitatively investigated on the characteristics of the current maps by comparing with both the previous literature and up-to-date scientific knowledge. All the maps in the textbooks with different mappings were converted to digitalized image data with Mercator mapping using geolocation information. Detailed analysis were performed to investigate the patterns of the Tsushima Warm Current (TWC) in the Korea Strait, to examine how closely the nearshore branch of the TWC flows along the Japanese coast, to scrutinize the features of the offshore branch of the TWC south of the subpolar front in the East Sea, to quantitatively investigate the northern range of the northward-propagating East Korea Warm Current and its latitude turning to the east, and lastly to examine the outflow of the TWC near the Tsugaru Strait and the Soya Strait. In addition, the origins, southern limits, and distances from the coast of the Liman Current and the North Korea Cold Current were analyzed. Other erroneous expressions of the currents in the textbooks were presented. These analyses revealed the problems in the present current maps of the textbooks, which might lead the students to misconception. This study also addressed a necessity in a bridge between scientists with up-to-date scientific results and educators who needed educational materials.

• Journal of the Mineralogical Society of Korea
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• v.7 no.1
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• pp.49-61
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• 1994

As the groundwater flows along the fractures of crystalline rocks, it will be in contact with the fracture walls mostly coated by secondary minerals which are quite different form those of host rocks. The presence of fracture-filling minerals in crystalline rocks is important on the view point of radioactive waste disposal because of their great surface reactivity. The Surichi drill hole of 200 m in depth in the Yugu area composed mainly of Precambrian gneiss was selected to study the formation process of clay minerals on the fracture wall of gneiss, and their relation with present groundwater. The water-rock interaction in fractures resulted in the formation of gibbsite and clay minerals. They are formed by two different processes : (1) Incongruent dissolution of feldspar by groundwater diffused from a fracture path into rock matrix produced smectite and illite in situ, (2) on the wall of fracture, gibbsite, kaolinite, smectite and illite are formed by precipitation of dissolved species in groundwater. They show the paragenetic sequence such as gibbsite${\leftrightarrow}$kaolinite${\leftrightarrow}$smectite or illite. The paragenetic sequence of fracture-filling minerals was controlled by increase of pH of groundwater, decrease of fracture permeability by precipitation of fillings, and immobility of alkali or alkaline earths in groundwater. The groundwater from the Surichi borehole is a $Na-HCO_{3}$ type with pH range of 8.6-9.2. The sodium and bicarbonate in groundwater would be supplied by the dissolution of albite and calcite, respectively. The saturation index of groundwater and surface water calculated by WATEQ4F indicates that gibbsite and kaolinite are under precipitation to equilibrium state, and that smectite and illite are under equilibrium to redissolution environment. The stability relation of clay minerals in the $Na_{2}O-Al_{2}O_{3}-SiO_{2}-H_{2}O$ system shows that kaolinite is stable for all waters.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.4
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• pp.481-491
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• 2018

As the global business environment is dynamic, uncertain, and complex, supply chain management determines the performance of the supply chain in terms of the utilization of resources and capabilities of companies involved in the supply chain. Companies pursuing open innovation gain greater access to the external environment and accumulate knowledge flows and learning experiences, and may generate better business performance from dynamic capabilities. This study analyzed the effects of supply chain dynamic capabilities, open innovation, and supply uncertainty on supply chain performance. Through questionnaires on 178 companies listed on KOSDAQ, empirical results are as follows: First, integration and reactivity capabilities among supply chain dynamic capabilities have a positive effect on supply chain performance. Second, the moderating effect of open innovation showed a negative correlation in the case of information exchange, and a positive correlation in the cases of integration, cooperation and reactivity. Third, two of the 3-way interaction terms, "information exchange*open innovation*supply uncertainty" and "integration*open innovation*supply uncertainty" were statistically significant. The implications of this study are as follows: First, as the supply chain needs to achieve optimization of the whole process between supply chain components rather than individual companies, dynamic capabilities play an important role in improving performance. Second, for KOSDAQ companies featuring limited capital resources, open innovation that integrates external knowledge is valuable. In order to increase synergistic effects, it is necessary to develop dynamic capabilities accordingly. Third, since resources are constrained, managers must determine the type or level of capabilities and open innovation in accordance with supply uncertainty. Since this study has limitations in analyzing survey data, it is necessary to collect secondary data or longitudinal data. It is also necessary to further analyze the internal and external factors that have a significant impact on supply chain performance.

• Fire Science and Engineering
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• v.31 no.5
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• pp.53-62
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• 2017

Electric power which is the energy source of economy and industries requires long distance transportation due to regional difference between its production and consumption, and it is supplied through the multi-loop transmission and distribution system. Prior to its actual use, electric power flows through several transformations by voltage transformers in substations depending on the characteristics of each usage, and a transformer has the structure consisting of the main body, winding wire, insulating oil and bushings. A transformer fire that breaks out in substations entails the primary damage that interrupts the power supply to houses and commercial facilities and causes various safety accidents as well as the secondary economic losses. It is considered that causes of such fire include the leak of insulating oil resulting from the destruction of bottom part of bushings, and the chain reaction of fire due to insulating oil that reaches its ignition point within 1 second. The smoke detector and automatic fire extinguishing system are established in order to minimize fire damage, but a difficulty in securing golden time for extinguishing fire due to delay in the operation of detector and release of gas from the extinguishing system has become a problem. Accordingly, this study was carried out according to needs of active mechanism to prevent the spread of fire and block the leak of insulating oil, in accordance with the importance of securing golden time in extinguishing a fire in its early stage. A bushings fireproof structure was developed by applying the high temperature shape retention materials, which are expanded by flame, and mechanical flame cutoff devices. The bushings fireproof structure was installed on the transformer model produced by applying the actual standards of bushings and flange, and the full scale fire test was carried out. It was confirmed that the bushings fireproof structure operated at accurate position and height within 3 seconds from the flame initiation. It is considered that it could block the spread of flame effectively in the event of actual transformer fire.