• Journal of the Society of Naval Architects of Korea
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• v.45 no.4
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• pp.345-352
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• 2008

The motion of a projectile initiated by the release of highly pressurized air is simulated presuming the flow field as a two dimensional one. The effects of water compressibility on projectile movements are investigated, comparing results based on the Fluent VOF model where water is treated as an incompressible medium with those from the presently developed VOF scheme. The present model considers compressibility of both air and water. The Fluent results show that the body moves farther and at higher speeds than the present ones. As time proceeds, the relative difference of speed and displacement between the two results drops substantially, after acoustic waves in water traverse and return the full length of the tube several times. To estimate instantaneous accelerations, however, requires implementation of the water compressibility effect as discrepancies between them do not decrease even after several pressure wave cycles.

• Structural Engineering and Mechanics
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• v.12 no.5
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• pp.541-558
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• 2001

The design specifications of guard fences in Japan were reexamined and the revised specifications were implemented from April 1999. Because of the huge consumption in time and cost to test the performances of full-scale guard fences in the field, some assumptions are adopted while modifying the design specifications, and numerical analyses are necessary to confirm the impact performance and safety level of new types of steel highway guard fences. In this study, the finite element models are developed for the heavy trucks and steel highway guard fences to reenact their behaviors, and the solution approach is carried out using nonlinear dynamic analysis software of structures in three dimensions (LS-DYNA). The numerical simulation results are compared with the full-scale on-site testing results to verify the proposed analysis procedure. The collision process is simulated and it is also made possible to visualize the movement of the truck and the performances of guard fences. In addition, the energy shift of the truck kinetic energy to the truck and guard fence Internal energy, and the energy absorption of each guard fence component are studied for the development of a new design methodology of steel highway guard fences based on the energy absorption capacity.

• Proceedings of the KAIS Fall Conference
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• 2007.11a
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• pp.367-370
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• 2007

한국수자원공사에서 개발한 유출모의 모형인 RRFS의 입력자료로 사용되는 소유역별 각 용수에 대한 회귀율은 생공용수의 경우에는 65%, 농업용수의 경우에는 35%로 하여 일괄적으로 입력되어 있으나 이러한 값은 대략적으로 추정된 값이다. 따라서 본 연구에서는 금강수계내 전체에 대한 용수체계도를 대청댐 상류, 청주권, 대전권, 대청댐 하류 및 하구언권으로 구분하여 각 권역별로 작성하여 유출체계에 의한 메커니즘을 도시하였다. 본 연구에서는 체계적인 용수이용별 물이용수급현황 분석을 통해 물이용현황을 파악하는 것에 목적을 삼고 용수계통도 작성을 통한 권역별 용수체계를 분석하고자 하였다. 금강유역내 총 14개의 소유역에 대한 용수계통도 작성을 통해 용수수급현황을 분석하고, 궁극적으로 용수수급현황도를 작성하고자 각 권역별 하천 수계현황 조사, 용수사용현황 조사, 주요 용수시설물 현장조사 및 용수계통도를 작성하였다.

• Journal of the Korean Geophysical Society
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• v.7 no.4
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• pp.269-276
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• 2004

Optical fiber sensors have shown a potential to serve real time health monitoring of the structures. They can be easily embedded or attached to the structures and are not affected by the electro-magnetic field. Furthermore, they have the flexibility of the sensor size and very highly sensitive. In this study, we conducted several laboratory and field tests using a novel optical sensor based on Brillouin scattering. One of the advantages of this technique is that the bare fiber itself acts as sensing element without any special fiber processing or preparation. Test results have shown that BOTDR can be a great solution for sensor systems of Civil Engineering Smart Structures.

• Journal of the Korean Geophysical Society
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• v.7 no.4
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• pp.305-311
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• 2004

Several sensor systems are used to estimate the reinforceing effect of pile in hihg cut slopes, and to find a failure zone in slopes effectively. Inclinometer, extensometer and V/W sensor have shown a great potentiality to serve real time health monitoring of the slope structures. They were embedded or attached to the structures, we conducted field tests and test results have shown great solutions for sensor systems of Civil Engineering Smart Structures. This research is to seek for the relationships among the slope movement and the reinforceing effect of pile, and the strain distribution in a active zone by analyzing the data from the in-situ measurement so that the possible failure zone should be well defined based on the relationships. Also, the relationships between temperature and reinforceing effect of pile, and the strain distribution are estimated in this paper.

• Journal of Korean Association for Spatial Structures
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• v.19 no.3
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• pp.33-40
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• 2019

A seismic isolation system is one of the most effective control devices used for mitigating the structural responses due to earthquake loads. This system is generally used as a type of base isolation system for low- and mid-rise building structures. If the base isolation technique is applied to high-rise buildings, a lot of problems may be induced such as the movement of isolation bearings during severe wind loads, the stability problem of bearings under large compression forces. Therefore, a mid-story isolation system was proposed for seismic protection of high-rise buildings. Residence-commerce complex buildings in Korea have vertical irregularity because shear wall type and frame type structures are vertically connected. This problem can be also solved by the mid-story isolation system. An effective analytical method using super elements and substructures was proposed in this study. This method was used to investigate control performance of mid-story isolation system for residence-commerce complex buildings subjected to seismic loads. Based on numerical analyses, it was shown that the mid-story isolation system can effectively reduce seismic responses of residence-commerce complex tall buildings.

• Journal of Ocean Engineering and Technology
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• v.33 no.3
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• pp.280-288
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• 2019

A submerged breakwater is one of the coastal structures used to reduce wave energy and coastal erosion. However, a submerged breakwater has a negative aspect in that a strong rip current occurring around an open inlet due to a difference in mean water levels at the front and rear sides of the structure leads to scouring. Such scouring has a bad effect on its stability. In order to eliminate this kind of demerit, this study investigated an artificial reef of the overflow type with openings. We also developed a program where the flows around the artificial reef of the overflow type could be analyzed numerically. An unstructured grid system was used to cover the various geometries, and the level set method was applied to treat the movement of the free surface. To verify these numerical schemes, hydraulic physical tests were performed on the submerged breakwater and double breaking type artificial reef. Then, the wave height and velocity distribution around the reef were examined using the experimental results. Comparisons between the results of hydraulic and numerical tests showed reasonable agreement.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.36 no.3
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• pp.129-134
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• 2020

The current evaluation time period for the construction management service is the project completion or after project completion. Therefore, the construction manager has the following problems. First, it is difficult to prepare the evaluation due to the new field movement of the existing participating engineer. Next, the CM work is complex as well as extensive. Therefore, the critical success factors of the construction technology services evaluation are required as a systematic performance standard of CM work. In this study, we extracted the critical success factors that can systematically prepare the evaluation from the early stage of the project through in - depth interviews with experts. And, this study was analyze the priority of each factor by using AHP technique. As a result, the most important factors were related to the systemization of the preparation process, the construction manager work capabilities and practical construction management. And the priorities of all factors were analyzed high in the factors suggested by the owner groups. The results of this analysis are expected to provide the standards that construction management service performer carry out structured management of construction management throughout the project.

• English & American cultural studies
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• v.14 no.1
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• pp.1-26
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• 2014

Multicultural theories fully fledged around the 1980s and the early 1990s. Emerging in the 1960s thanks to the Civil Rights movement, multiculturalism has become the grand American national narratives, whose tenets recognize and respect people with diverse racial and cultural backgrounds. This period, however, witnessed the eruption of violent and destructive rebellions or uprisings involving racial minorities. Racial conflicts and tensions exploded at the moment when multiculturalism was widely practiced in areas including education and public policy revealing that complicated problems are embedded in the urban ghettos. American popular culture, specifically addresses antagonisms among different races or ethnicities in Bed-Stuy in New York. Although the film is mainly concerned with the collision among races, it lets ambivalent and cacophonous values and ideologies be present in the black community. On the other hand, Ice Cube's "Black Korea" empowers the black community when it deals with the turbulent relationship between black residents and Korean American merchants. Simultaneously, it denigrates Korean Americans as gasta raps often target the institution like government or police. In short, while attempts to search the ideas of coexistence and juxtaposition through polyphonic features embodied in the film "Black Korea" seems to depend on the dualistic system when it deals with the black-Korean conflicts and as a result it just reveals the chasm between two communities.

• Acta Via Serica
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• v.7 no.1
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• pp.105-130
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• 2022

This paper argues that the war in Syria is partly the result of a global Islamist wave that contributed to fuelling conflict across large regions of Asia and Africa. Of course, the war that has consumed Syria since 2011 most certainly has multiple interrelated causes and driving forces, and any attempt to isolate one or even two or three runs the risk of advancing an overly simplistic interpretation of history. This essay, therefore, does not aim to offer an appraisal of the multiple variables that contributed to the war in Syria. Instead, it zeroes in on how political Islam came to impact Syria and its people. In doing so, it demonstrates how competing varieties of political Islam represented leading causes of conflict. Indeed, different Islamist movements contributed to the outbreak of the war in 2011, fuelled the conflict for years on end, and to this day represent major obstacles to the achievement of sustainable peace. Four broad Islamist currents are especially relevant to the case of Syria: the Muslim Brotherhood; the Shia revivalist movement at the nexus of the alliance between Iran, Hezbollah, and Syria; Salafi jihadism and its volatile and fractious underworld of competing armed groups, from Al-Qaeda to the Islamic State; and Recep Tayyip Erdoğan's market-friendly Islamism, which induced Turkey to intervene in Syria's civil war.