• Korean Chemical Engineering Research
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• v.53 no.1
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• pp.16-21
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• 2015

The body structure of diaphragm type preaction valve was improved in order to reduce the pressure drop. The pressure drop must be kept within 20.7 kPa to pass the revised (2012. 2. 9) standard for alarm valve and preaction valve. The pressure drop test was carried out by KFI (Korea Fire Institute) standard. The pressure drop of a preaction valve was higher than that of an alarm valve. Causes for increasing the pressure drop were investigated with the fluid flow in the valve. The preaction valve had more pressure drop factors (changes in velocity and direction) compared with the alarm valve. Inner structure of the preaction valve was changed to the clapper type to remove the pressure drop factors. In 80A and 100A size of preaction valves, the pressure drop was reduced from 80.9 and 171.0 kPa to 14.4 and 14.2 kPa respectively, after the change of the structure.

• Journal of the Microelectronics and Packaging Society
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• v.15 no.2
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• pp.37-45
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• 2008

In this study, reliabilities of Cu (60 um)/SnAg (20 um) double-bump flip chip assemblies were investigated for the flip chip interconnections on organic substrates with 100 um pitch. After multiple reflows at $250^{\circ}C\;and\;280^{\circ}C$, bump contact resistances were almost same regardless of number of reflows and reflow temperature. In the high temperature storage test, there was no bump contact resistance change at $125^{\circ}C$ up to 2000 hours. However, bump contact resistances slightly increased at $150^{\circ}C$ due to Kirkendall voids formation. In the electromigration test, Cu/SnAg double-bump flip chip assemblies showed no electromigration until about 600 hours due to reduced local current density. Finally, in the thermal cycling test, thermal cycling failure mainly occurred at Si chip/Cu column interface which was found out the highest stress concentration site in the finite element analysis. As a result, Al pad was displaced out under thermal cycling. This failure mode was caused by normal compressive strain acting Cu column bumps along perpendicular direction of a Si chip.

• Journal of Korean Society of Transportation
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• v.25 no.4
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• pp.57-66
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• 2007

According to the rapid economic growth and the escalation of recreational tourism activities due to the change of job and working patterns, currently various traffic problems often occur in tourist areas. As tourist traffic, contrary to general traffic, is not regional but rather from outside the area of interest, it is hard to grasp the traffic situation surrounding the tourist area. Furthermore, since the traffic is concentrated during a limited tourist season, it is difficult to examine and solve the problem. In this study, in order to test the feasibility of introducing a traffic transfer system to reduce congestion in tourist areas, the authors considered the differences in traffic congestion between typical and tourist seasons and designed a willingness to pay model. The willingness to pay amount for a shuttle bus fare is assumed as 1,430 Won and 1,650 Won is assumed for a transfer parking charge. These amounts were slightly above the current bus fare in the study area, but many people thought that the introduction of a traffic transfer system would help to relieve the traffic congestion approaching the tourist area and to develop tourism resources. As the willingness to pay appeared high from the persons used in this study, it was indirectly confirmed that the introduction of a traffic transfer system would be a step in the right direction.

• Journal of the Korean Society of Hazard Mitigation
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• v.6 no.3 s.22
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• pp.47-56
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• 2006

With the aim to develop the monitoring technology on background atmosphere and climate change over Korean Peninsula, observations and studies on chemical, physical and optical properties of the atmospheric aerosols are made. Aerosol number concentration are measured with Optical Particle Counter from 2001 to 2003 at Gosan for 8 size intervals from 0.3 to $25{\mu}m$ diameter range. For the seasonal variation, the number concentration of coarse particles in spring at Gosan was higher than other seasons due to the influence of sand storm in spring. There is no significant correlations between fine particles ($0.3{\sim}0.5{\mu}m$) and meteorological parameters, such as relative humidity, wind speed and visual range, while the correlation between the number concentration of small particles ($0.5{\sim}2.23{\mu}m$) and relative humidity showed a positive value. This trend was inversed for the case of wind speed: aerosol number concentration showed a small decreasing tendency with increasing wind speed for small particles but the high wind speed in winter season increased coarse particle concentration. Finally, Particles most efficient in light extinction were found to be at the size of about $0.5{\sim}1{\mu}m$.

• Journal of Korea Water Resources Association
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• v.40 no.1 s.174
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• pp.11-24
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• 2007

There exist various difficulties in runoff analysis due to many ungauged basins in Korea and the runoff phenomena is also more and more complicated by the change of geologic characteristics due to the urbanization. So, we use GIS technique which is widely used in hydrologic field and cell runoff concept for the fast and effective runoff simulation. This study uses the observations of 6 stage stations in Wi-Cheon watershed and simulates the watershed parameters by using WMS model. We construct DEM by the grids which are consisted based on the criteria of minimum area according to land use. The cell runoff is estimated by an average weighted method using mean annual streamflow and mean maximum daily streamflow obtained from six stage stations. The runoff ratio at arbitrary site is estimated by conducting the direction analysis of streamflow and by removing sinkhole. We compare the simulated and observed runoffs and know that the simulated runoff shows the valid results. So, we could use the geographical information and cell runoff concept for more fast and effective runoff simulation studies.

• 한국사회정책
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• v.24 no.2
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• pp.245-275
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• 2017

It is attempted here to explain change in welfare attitudes for two decades in 10 countries with the cohort effect, especially differences in societal values between generations. It was found that for the last 20 years pro-welfare attitudes of the public has been strengthened, on which the generation has impact, more by the cohort effect than by the age effect, and that the Millennials/Y-generation are the strongest supporters for the state welfare. Value-differences between cohorts, as a background factor for the cohort effect on welfare attitudes, are clear but show a kind of linear trend from the older to the younger cohorts. As for the cohort effect on welfare attitudes, it is expected, at least for the short-term future, in the direction toward supporting the expansion of the state welfare. Korean welfare attitudes show an exceptional pattern - preferring income inequality as incentives, and at the same time, the expansion of governmental welfare responsibility, which echoes recent arguments of contradictoriness and non-class-orientedness of Korean welfare attitudes. Especially, Korean Millennials/Y-G shows this contradictory welfare attitudes the most strongly, which is unique between 10 countries in this study, implying their fierce competition is being internalized. It is expected that the contradictoriness of Korean welfare attitudes may limit its possibility to back up welfare expansion in Korea.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.7
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• pp.950-957
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• 2023

For safe mooring and towing between the ship and port, the equipment must be designed in accordance with the relevant international regulations. However, some small shipyards and engineering companies often do not fully comprehend the core contents. Therefore, the international regulations regarding towing and mooring equipment are reviewed and the bollard and chock are newly developed based on the Mooring Equipment Guideline 4 (MEG4) standards. A bollard is a mooring equipment used to fix a mooring rope to the hull. It has two columns and is mostly used in a figure eight pattern knots under the mooring condition. The chock, which is used to change the mooring rope direction coming into the ship from outside, is manufactured using a casting with curvature. The two mooring equipment are widely used in the stern, bow, and mid-side. Owing to the increase in the size of container vessels and LNG ships, the mooring rope load has increased and the safe working load of the mooring equipment must be revised. This study summarizes and examines the results of the allowable stress method obtained using finite element analysis modelling. To consider the mesh size effect, a reasonable criteria was suggested by referring the existing class guidance. Additionally, the safe working load was verified through nonlinear collapse analysis, and the elastic region against load increments was confirmed. Furthermore, the proposed evaluation method can be used to develop similar equipment in the near future.

• Journal of the Korean Regional Science Association
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• v.40 no.1
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• pp.37-51
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• 2024

To respond to local extinction, South Korea, under the leadership of the Ministry of the Interior and Safety, identified depopulated areas in 2021 and launched the Local Extinction Response Fund in 2022. However, due to its early stage of implementation, analyzing the characteristics and changes of policy response to local extinction at the central government level remains a challenge. In contrast, Japan, facing similar issues of local extinction as South Korea, has established a robust central government-led response system based on the Regional Revitalization Act and the Comprehensive Strategy and Basic Policy on Community-Population-Job Creation. Hence, this study examines Japan's policy responses to local extinction by analyzing the first and second periods of the Comprehensive Strategy and Basic Policy on Community-Population-Job Creation. For the analysis, topic modeling was employed to enhance text analysis efficiency and accuracy, complemented by expert interviews for validation. The results revealed that the first-period strategy's topics encompassed economy and society, start-up, local government, living condition, service, and industry. Meanwhile, the second-period strategy's topics included resource, the New Normal, woman, digital transformation, industry, region, public-private partnership, and population. The analysis highlights that the policy target, policy direction, and environmental change significantly influenced these policy shifts.

• Journal of the Korean GEO-environmental Society
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• v.11 no.7
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• pp.25-31
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• 2010

In this study, it was intended to suggest new cooling method that enables to improve the applicability and added value higher than existing slag by applying new cooling method(powder cooling slag) at the time discharging slag, which is produced from the ash melting system that the plasma torch is used for the first time in Korea. It is suggested the applicative direction in the development of future recycling process by discovering its nature of material and applicative possibility as earthwork material. The ashes produced after the sewage sludge discharged from Y city was incinerated by the fluidized bed method and was used as test materials. As result of XRF(X-Ray Flourescence Spectrometry) analysis, main ingredient of sewage sludge ashes was $SiO_2$(32%) besides CaO, $Al_2O_3$, $Fe_2O_3$, and so on. In addition, as result of XRD analysis, traditional diffuse pattern of glass could be found from granulated air-cooled slags, while a minor crystal phase could be observed from powder cooling slag, because the powder on the surface exists in the state not melted. From EDX(Energy Dispersive X-ray Spectroscopy) analysis, it is deemed that powder ingredient has no change before and after it is used as cooling medium, and accordingly it is thought that the powder can be produced as the material where the function is added if used in different shape.

• Informatization Policy
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• v.25 no.1
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• pp.3-29
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• 2018

The Federal Communications Commission voted to repeal net neutrality protections on December 14, 2017. This is the very opposite decision of the net neutrality rule that the Obama administration has consistently maintained. The ensuing storm from the repeal of net neutrality protections has an extensively effect enough on individuals and businesses to cover the entire spectrum, and the impact is hard to assess in the U. S. content industry, which dominates the worldwide Internet content and platform market. On the other hand, Korea's net neutrality protections have been firmly pursued, and there is no sign of change even after the decision happened in the U. S. Net neutrality is not a simple theme that is associated with the Constitution, such as freedom of expression, as well as the issue of network enhancement to prepare for 5G. Accordingly, this study examines how the net neutrality has been carried out in the U. S. and Korea over the years, and provides the issues of Internet enhancement, perspectives of ISP and ICP, and implications for the Constitution, market economy, fair competition and zero rating. This research delivers future direction and implications of domestic net neutrality policies.