• Journal of Korea Water Resources Association
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• v.44 no.7
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• pp.553-563
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• 2011

According to the improvement of computer's performance, the development of Geographic Information System (GIS), and the activation of offering information, a distributed model for analyzing runoff has been studied a lot in recently years. The distribution model is a theoretical and physical model computing runoff as making target basin subdivided parted. In the distributed model developed by this study, the volume of runoff at the surface flow is calculated on the basis of the parameter determined by landcover data and a two-dimensional diffusion wave equation. Most of existing runoff models compute velocity and discharge of flow by applying Manning-Strickler's mean velocity equation and Manning's roughness coefficient. Manning's roughness coefficient is not matched with dimension and ambiguous at computation; Nevertheless, it is widely used in because of its convenience for use. In order to improve those problems, this study developed the runoff model by applying not only Manning-Strickler's equation but also Chezy's mean velocity equation. Furthermore, this study introduced a power law of exponential friction factor expressed by the function of roughness height. The distributed model developed in this study is applied to 6 events of fan-shape basin, oblong shape test basin and Anseongcheon basin as real field conditions. As a result the model is found to be excellent in comparison with the exiting runoff models using for practical engineering application.

• The KIPS Transactions:PartB
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• v.11B no.1
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• pp.71-76
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• 2004

The recent ERP and CRM is mostly focused on the conventional function performances. However, the recent business environment has brought the change in market due to the rapid progress of internet and e-commerce. It is mostly becoming e-business and spreading out as development of the relationship with other cooperating companies, the rapid progress of the relationship with customers, and intensification competitive power through the development of business progress in the organization. CRM(custom relationship management) is a kind of the marketing progress which forms, manages, and intensifies the relationship between the customers and companies to manage the acquired customers and increase the worth of customers for the company. It needs the system base which analyzes the information of customers since it functions on the basis of various information about customers and is linked to the business category such as producing, marketing, and decision making. Since ERP is extending its function to SCM, CRM, and SEM(strategic Enterprise Management), the 21 century s ERP develop as the strategy tool of e-business and, as the mediation for this, will subdivide the functions of CRM effectively by the analogic study of data. Also, to accomplish classification work of the file which in existing becomes accomplished with possibility work with an automatic movement with the user will be able to accomplish a more efficiently work the agent which in order leads the machine studying law, it is one thing with system feature.

• Journal of the Korean earth science society
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• v.31 no.6
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• pp.608-624
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• 2010

Morphological surveys of southern Gyeonggi Bay in the Yellow Sea were conducted for2 years (2006 and 2007) by using multibeam echosounder for investigating the morphological features of bedforms. The subaqueous dunes are shown in various shapes (A~F type) and continuous spectrum of heights and lengths of transverse-to-current dunes on the wide range of sedimentary types. The height-length power-law correlation of dunes is $H_{mean}=0.0393L^{0.8984}$ (r=0.66). The comparison between Flemming (1988)'s correlation and height-length correlation of this study indicates that the subaqueous dunes in the study area are equilibrated in the present hydrological and sedimentary environment. The major controlling factors to thedevelopment and maintenance of subaqueous dunes are both strong tidal currents and the abundant availability of sand. Marine sand mining, artificial impact, changes from the original shape to an irregular shape of the subaqueous dunes with a shorter wavelength and lower height, which has influence on the development and maintenance of bedform because it causes a decrease of the availability of sediment. Water depth and sedimentary characteristics, and othercontrolling factors seem to play limited roles in the development and maintenance of subaqueous dunes.

• Journal of Navigation and Port Research
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• v.39 no.3
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• pp.217-222
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• 2015

In this research, sea routes of domestic coaster liners between 2005 and 2013 were studied via social network analysis. Study of the sea routes revealed that they follow power-law in a scale-free form, a characteristic found often in social network. We have looked into centrality, which is a major standard in the field of social network analysis. We have also analyzed the annual changing trend in the centrality of the connectivity, examined the effect of quantity through the comparison with the original quantitative analysis method, and lastly, verified the relationship between the centrality of connectivity and mediation. Then, we were able to identify ports according to priority using these factors. This research assumed and interpreted the coaster liners route as a single network and suggested useful results. Based on these results, directing of development of domestic coaster liners route development and other factors will be achieved more smoothly. And if we utilize social network analysis method in other various fields - for example, the centrality of airport and the diplomatic realations analysis of the neighboring country - we will be able to effectively analyze events in diverse perspectives.

• Journal of the Korean Institute of Gas
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• v.14 no.3
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• pp.26-34
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• 2010

KOGAS, established in 1983 by law to ensure stable gas supply to the public, is responsible for the wholesale distribution to 30 city gas companies that deal with the retail distribution of natural gas in their geographic areas. The gas imported by KOGAS is measured by checking the level difference of LNG shipped in tankers before and after unloading. The analysis of gas composition is essential because the imported gas price is determined by its calorific value. The turbine meter is widely used for measuring the gas sold to city gas companies. Unlike the metering system for power plants, there is no gas chromatograph since the custody transfer of gas to the city gas companies is not billed by calorific value, but by volume basis. The gas quantity that a city gas company has bought from KOGAS is not equal to the quantity that the company sold to its customers. There have been some discrepancies between the wholesale gas meter readouts and retail ones due to some inherent errors of meters and some operational issues of the meters. This paper investigates the controversies regarding the real quantity of gas between distributors and consumers. It will discus and suggest desirable policies, both technically and economically, in order to solve the discrepancies of gas measurement.

• Journal of the Korean Institute of Gas
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• v.21 no.5
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• pp.1-8
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• 2017

Currently gas safety management in the industrial field has been done by LDAR as contact method or methane leak detector as non-contact method. But LDAR method requires a lot of man-power and methane leak detector have the limitation of methane only. Therefore the Research on the OGI(optical gas image) has big attention by industry. This research was undertaken to see the effect of background temperature difference of gas cloud on the clarity of OGI. The background temperature control panel was constructed to cool down the background temperature. OGI was taken at the various methane gas ejection rate and the designed temperature difference. The experimental results showed that the OGI(when the temperature difference is $-6^{\circ}C$) is more clear thane the OGI(when the temperature difference is zero). To quantify the clarity difference, MATLAB's RGB analysis method was employed. The RGB value of the OGI at ${\Delta}T-6^{\circ}C$ was 20% lower than the OGI at ${\Delta}T0^{\circ}C$. The clarity difference by T difference can be explained by the total radiation law. When the background temperature of the gas is lower than the air temperature, the radiation energy coming into the OGI lens is increasing. As the energy is increasing, the OGI image becomes clear.

• Tribology and Lubricants
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• v.34 no.5
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• pp.197-207
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• 2018

Thermal deterioration of fuel due to long-term storage influences engine performance and causes malfunctions. Fuel stability is usually evaluated via heat resistance and thermal stability during a brief heat shock at high temperature; storage stability in this scenario means that there is very little change in the quality of the fuel during long-term storage. In addition, rubber-based products such as oil seals, O-rings, and rubber hoses can influence the quality of the fuel. When these rubber products are in contact with fuel, they can swell, mechanically weaken, and occasionally crack, thus leaking low molar weight rubber and additives including plasticizer and antioxidant into the fuel to degrade its properties and shorten its useful lifetime. This study determines the thermal stabilities of three kinds of synthetic fuels by evaluating their low temperature kinematic viscosities, chemical composition changes via GC analyses, gross heat of combustion, and color changes. We evaluate the compression set of O-rings by immersing one NBR and two FKM rubber O-rings in the three synthetic fuel samples in airtight containers at variable storage temperatures for six months; from this, we estimate the lifetimes of the O-rings using the Power law model. There were very little changes in the chemical compositions and gross heat of combustion after six months of the experiment. The lifetimes are thus dependent on the materials of the rubber products, and in particular, the FKM O-ring was calculated to have a theoretical lifetime of 200 to 5,700 years. These results indicate that the synthetic fuels maintain their physical properties even after long-term storage at high temperatures, and the FKM O-ring is suitable for long-term sealing of these fuels.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.27 no.4
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• pp.246-257
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• 2015

The progressive degradation paths of structures have quantitatively been tracked by using stochastic processes, such as Wiener process, gamma process and compound Poisson process, in order to consider both the sampling uncertainty due to the usual lack of damage data and the temporal uncertainty associated with the deterioration evolution. Several important features of stochastic processes which should carefully be considered in application of the stochastic processes to practical problems have been figured out through assessing cumulative damage and lifetime distribution as a function of time. Especially, the Wiener process and the gamma process have straightforwardly been applied to armors of rubble-mound breakwaters by the aid of a sample path method based on Melby's formula which can estimate cumulative damage levels of armors over time. The sample path method have been developed to calibrate the related-parameters required in the stochastic modelling of armors of rubble-mound breakwaters. From the analyses, it is found that cumulative damage levels of armors have surely been saturated with time. Also, the exponent of power law in time, that plays a significant role in predicting the cumulative damage levels over time, can easily be determined, which makes the stochastic models possible to track the cumulative damage levels of armors of rubble-mound breakwaters over time. Finally, failure probabilities with respect to various critical limits have been analyzed throughout its anticipated service life.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.2
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• pp.50-57
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• 2007

Shocks are excited by impulsive forces and cause discomfort in vehicles. Current standards define means of evaluating shocks and predicting their discomfort, but the methods are based on research with a restricted range of shocks. This experimental study was designed to investigate the discomfort of seated subjects exposed to a wide range of vertical shocks. Shocks were produced from the responses of one degree-of-freedom models, with 16 natural frequencies (from 0.5 to 16 Hz) and four damping ratios (0.05 0.1, 0.2 and 0.4), to a hanning-windowed half-sine force inputs. Each type of shock was presented at five vibration dose values in the range $0.35\;ms^{-1.75}$ to $2.89\;ms^{-1.75}$. Fifteen subjects used magnitude estimation method to judge the discomfort of all shocks. The exponent in Stevens' power law, indicating the rate of growth in discomfort with shock magnitude, decreased with increasing fundamental frequency of the shocks. At all magnitudes, the equivalent comfort contours showed greatest sensitivity to shocks having fundamental frequencies in the range 4 to 12.5 Hz. At low magnitudes the variations in discomfort with the shock fundamental frequency were similar to the frequency weighting $W_b$ in BS 6841, but low frequency high magnitudes shocks produced greater discomfort than predicted by this weighting. At some frequencies, for the same unweighted vibration dose value, there were small but significant differences in discomfort caused by shocks having different damping ratios. The rate of increase in discomfort with increasing shock magnitude depends on the fundamental frequency of the shock. In consequence, the frequency-dependence of discomfort produced by vertical shocks depends on shock magnitude. For shocks of low and moderate discomfort, the current methods seem reasonable, but the response to higher magnitude shocks needs further investigation.

• Journal of Korean Library and Information Science Society
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• v.9
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• pp.115-144
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• 1982

In ordinary modern wester expression 'the Renaissance' was used to denote the impact made by dead Hellenism civilization in western Christendom, particularly Italian literary and artistic movement at Northern and central Italy in the late medieval period. However, A.J. Toynbee examined the renaissance from the different aspect of view. In his great work "A Study of History" in vol. IX, he succeeded in establishing the theory of historic civilization encounters in space and in time; and in time, civilization of the present and the past or between dead and infant successor contacts on the analogy of parenthood and sonship in the relation of A n.0, pparentation-and-Affiliation. The distinguished his view of 'Renaissance' was illustrated in the sense of encounters between a grown-up civilization and the 'ghost' of its long-dead predecessor. The renaissances (by the process of evocation of ghost of its parent society) has not only one single aspect of literary and artistic field but also in politics, law, science and philosophy, languages and literatures and visual arts, and religion. The main theme of this study is to examine the development of libraries and its historical meaning through Toynbee's literary renaissance. His renaissance of Languages and Literatures has three typical steps: They are: 1st step-to restive the dead literature's remains: 2nd step-to remaster their meaning: 3rd step-to reproduce them in counterfeits... Through its first and second steps, collecting and editing, annotating by compiling an anthology, thesaurus, lexicon or encyclopedia, and in its third step publishing mostly imitation of classics took place. Toynbee depicted the five outstanding eminent representatives of literary renaissance who had a n.0, ppeared on the state of history down to the time of writing. They are: Assurbanipal, Constantine prophyrogenitus, Yung Lo, K'ang Hsi, and Ch'ien Lung and the last four had all been emperors of imperia rediviva. As the result of the examination of these five emperors with three steps of literary renaissance, the common result may be summarized as follows: 1. Those emperors of imperia rediviva interested in intellectual work and study, they also were deeply involved in collecting classics in an ostensible reason. 2. There were strong political intention of collecting materials as an a n.0, ppeasement policy of civilization by transferring scholars energies to an intellectual field. 3. Under the rulers of a resuscitated universal state, the literary renaissance were a product of political plane and that the total size of collection and work were huge. 4. Since there were strong exercise of sovereign power, an active censorship by distortion and elimination was inevitable. 5. There existed newly developed strained atmosphere between grown-up and long-dead parent civilization, whenever the book collection movement had occurred. 6. Over adhesion to the parent civilization caused imitation of classic work and the creative activities were stagnated.stagnated.