• Journal of the Korean Society for Precision Engineering
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• v.15 no.1
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• pp.145-151
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• 1998

This paper addresses the results of an experimental and analytical research of cylindrical coil spring subjected to dynamic behavior. Transfer functions are presented for both deflection and transmitted force as the output with force as the input. Steady state sinusoidal magnitude ratio and transmittance are plotted along with experimental data. It is shown that dynamic characteristic of cylindrical coil spring must be used to enhance the reability of vibration system dynamic behavior analysis in actuating over some frequency.

• The Journal of Engineering Geology
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• v.21 no.4
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• pp.369-379
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• 2011

The application of appropriate rehabilitation works can improve productivity and water quality of clogged wells, with extending the operation of the wells for a certain period. This study verified rehabilitation effect of the clogged wells by means of explosive method and air brush surging and by using hydraulic tests, water quality, and geophysical logs (optical and acoustic televiewer logs) before and after the cleaning works on the two wells drilled in bedrock in Mt. Geumjeong, Busan City. Air-brush surging method resulted in maximum 273% increase of the productivity with the concentration of $F^-$, $SiO_2$, and a decrease of turbidity and the concentration of $Cl^-$, $NO_3^-$. The explosive method resulted in maximum 156% increase of the productivity with an increase of the concentration of $F^-$, $SiO_2$ and a decrease of turbidity, $Cl^-$, $NO_3^-$.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.15 no.4
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• pp.1-7
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• 2019

Cooling using the Han River has recently been spreading. The Ministry of Trade, Industry and Energy submitted a revised enforcement ordinance to include river water in renewable energy. Therefore, it is necessary to analyze the water temperature characteristics of Han River. Especially, it is necessary to investigate the effect on hot summer. In this study, we analyzed the water temperature of the last 11 years. It is intended to utilize the Han River for building cooling in the future.

• International Commerce and Information Review
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• v.9 no.1
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• pp.427-449
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• 2007

The question of what our cultural goods might have known in a major exporting market, has intrigued investigators since 2000 year. Actually, Maybe Korean cultural assets just didn't have time to get to know International or Asia market. But now, a new euphoria can be tasted, on the lips of the small but growing Korean Contents Mania, as New Korean Wave-Crust begin to welcome the priciest contents from korea. Given Asian's surging population for our entertainment contents-drama, movie, music, character, etc., and the sense of a positive response its newly international market, it is hardly surprising. Now, Korea Wave must play an important roles in our country- economy, business, specially. This paper is seeking in OSMU on Korean Contents in East-North Asian Market, and is developing about Korean Wave study model. and It also points to a different strategy for exporting cultural contents, suggesting it should be effected for model to OSMU.

• Plant Journal
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• v.5 no.4
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• pp.73-79
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• 2009

Increase of consumption in limited coal reserves leads prices surging. As a result, iron works which produce products with coal are in difficulties. Accordingly, it is required a lot of research of using non-caking coal that is relatively low cost and has abundant reserves. Direct drying and indirect drying are two major methods of drying the coal. Recently, to minimize the needed calories and to save energy, using fluidbed or fluidizing method is a recent main trend of minimizing the size of the facility and maximizing energy efficiency. However there is also disadvantage such as increasing facility investment because of installing additional facilities in the latter part. In this study, we will have theoretical researches on the indirect drying method with heat exchange system which have been traditionally used. As a result it is expected to increase the efficiency of the facility operation.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.23 no.58
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• pp.41-47
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• 2000

Global(mega) event has increased throughout the 1990s, with the biggest surge occurring in the Asia-Pacific region. Along with this upward trend, competition for more desirable tourists is also surging, so destinations cannot be complacent (Getz, 1997). Event is appearing as the powerful method in the fierce competition around the industry. International events like 99 Hanam Environment Expo have been held annually in Korea since 1991 in which the local government system started. The main roles of event are to enhance the image of communities and attract tourists (Kotler and Haider and Rein, 1993), to strengthen destination attractiveness as drawing power (Mill and Morrison, 1985), and so on. Focused on the destination image, the research (Sirakaya and Sheppard and McLellan, 1997) about the effect of perceived safety at a potential vacation destination showed that destination marketers, travel agents, and hospitality industry members should be concerned with improving their images when such images are negative with regard to safety. Event industry in Korea does not seriously recognize the importance of the safety management against accidents known for tarnishing the destination images. Moreover few safety standards or studies for event industry can be found. This paper investigated the safety factors considered by visitors of 99 Hanam Environment Expo and analyzed the correlation between the safety factors and the demographic characteristics of the visitors.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.7
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• pp.895-906
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• 2000

A three dimensional linear frequency-domain lifting surface panel method was used for the aerodynamic analysis of axial flow type micro-fans. As proven by the duct modeling, the tip clearance of the micro-fans tested is large enough to ignore the calculated effect of the duct system. As the numerical results and experimental data agreed well in the operating point region, the method was applicable in the parametric studies to determine the design parameters of axial flow fans. Experiments on micro-fans were carried out based on KS B 6311. The newly designed micro-fan showed improvements in both static pressure rise and volumetric flow rate compared to the existing fans at a given operating condition. No detection of surging and the smooth characteristic curve proved the improvement in performance. To reduce the fan noise in the fan design, it was necessary to make use of the frequency spectrum analysis data. Measurement of sound pressure level for micro-fans was conducted based on KS B 6361 and KS A 0705. The peak - which occurs at blade passage frequency and its higher harmonics due to the fan noise - was not detected. This justifies the design methodology of the blade.

• Journal of Information Technology Applications and Management
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• v.9 no.3
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• pp.113-127
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• 2002

The effort for software process improvement is lately surging its interest though it does not satisfy both developer and receiver In terms of low productivity, quality, delay and increasing cost. According to current research, software process improvement contributes to improvement of productivity, its Duality, reduction of development time and cost, and the prediction of the time limit for delivery, which means software process improvement affects competitive advantage among developers. The latest research is whether the investment for information technology substantially had effect on improvement of productivity. That is, software process improvement and maturity of software industries has influence upon economic efficiency and as a result, it plays an important role in whole industries. This research is that how does software process improvement using CMM (Capability Maturity Model) and SPICE (Software Process Improvement and Capability dEtermination) have a effect on factors of software engineering, and how does it have influence upon competitive advantage among SI firms. For this research, reusability, customizability, participation, and review & inspection are set to independent variable and process flexibility and process predictability are set to mediate Variable. Finally, competitive advantage among SI firms Is set to dependent variable. The targets for survey are laborers who work for SI firms. The result of this research is as follows: 1 ) Reusability, Customizability and participation is not rejected but review and Inspection is rejected in process flexibility which has significant level 0.05. 2) Reusability, Customizability and participation is not rejected but review and inspection Is rejected in process predictability which has significant level 0.05. 3) Process flexibility is not rejected and process predictability Is rejected in the competitive advantage of 51 industries which has significant level 0.05

• The Journal of Engineering Geology
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• v.22 no.1
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• pp.27-37
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• 2012

To investigate the effect of aquifer disturbance on hydraulic properties while well drilling at unconsolidated aquifer, the following tests were conducted: the surge block and air-surging methods, which are well development methods used after well drilling; and step-drawdown tests and constant-rate pumping tests, which are used to assess changes in the aquifer after well drilling and development. The result of step-drawdown tests indicated that drawdown for a pumping-rate of $700m^3/day$ was 21.62 m after well development, decreasing 4.39 m from 26.01 m after well drilling. The skin factor used to identify the well properties decreased from 7.92 after well drilling to 5.04 after well development, respectively, which shows the improvement of well. Constant-rate pumping tests revealed a small increase in aquifer transmissivity after well development at MW-2, -3, and -4, centering around pumping well, from $1.684{\times}10^{-3}{\sim}4.490{\times}10^{-3}m^2/sec$ to $4.002{\times}10^{-3}{\sim}4.939{\times}10^{-3}m^2/sec$. MW-1, however, showed decline in hydraulic conductivity from $1.018{\times}10^{-2}m^2/sec$ to $6.988{\times}10^{-3}m^2/sec$, which was caused by a small decrease of aquifer permeability around monitoring well MW-1 due to latent factor of air interception and clogging in aquifer during surging. This finding indicates that fine particles have an effect on hydraulic properties at unconsolidated aquifers during well drilling; therefore, we consider that well drilling and development have an effect on hydraulic properties.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.11
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• pp.1123-1129
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• 2015

A pair of two-way valves typically is used in automotive washing machines, where the water flow direction is frequently reversed and highly pressurized clean water is sprayed to remove the oil and dirt remaining on machined engine and transmission blocks. Although this valve system has been widely used because of its competitive price, its application is sometimes restricted by surging effects, such as pressure ripples occurring in rapid changes in water flow caused by inaccurate valve control. As an alternative, one three-way reversing valve can replace the valve system because it provides rapid and accurate changes to the water flow direction without any precise control device. However, a cavitation effect occurs because of the complicated bottom plug shape of the valve. In this study, the cavitation index and percent of cavitation (POC) were introduced to numerically evaluate fluid flows via computational fluid dynamics (CFD) analysis. To reduce the cavitation effect generated by the bottom plug, the optimal shape design was carried out through a parametric study, in which a simple computer-aided engineering (CAE) model was applied to avoid time-consuming CFD analysis and difficulties in achieving convergence. The optimal shape design process using full factorial design of experiments (DOEs) and an artificial neural network meta-model yielded the optimal waist and tail length of the bottom plug with a POC value of less than 30%, which meets the requirement of no cavitation occurrence. The optimal waist length, tail length and POC value were found to 6.42 mm, 6.96 mm and 27%, respectively.