• Geomechanics and Engineering
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• 제18권2호
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• pp.205-213
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• 2019

A calculation model of reservoir pressure field distribution around multiple production wells in a heavy oil reservoir is established, which can overcome the unreasonable uniform-pressure value calculated by the traditional mathematical model in the multiwell mining areas. A calculating program is developed based on the deduced equations by using Visual Basic computer language. Based on the proposed mathematical model, the effects of drainage rate and formation permeability on the distribution of reservoir pressure are studied. Results show that the reservoir pressure drops most at the wellbore. The farther the distance away from the borehole, the sparser the isobaric lines distribute. Increasing drainage rate results in decreasing reservoir pressure and bottom-hole pressure, especially the latter. The permeability has a significant effect on bottom hole pressure. The study provides a reference basis for studying the dynamic pressure field distribution before thermal recovery technology in heavy oilfield and optimizing construction parameters.

• Advances in concrete construction
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• 제15권5호
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• pp.333-348
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• 2023

Fast infrastructure development boosts the demand for shotcrete. Despite sand and stone being the most common coarse and fine aggregates for shotcrete, excessive exploration of these materials challenges the ecological environment. This study utilized an industrial solid waste, high-titanium heavy slag, blended with steel fibers to form Wet Shotcrete of Steel Fiber-reinforced High-Titanium Heavy Slag (WSSFHTHS). It investigated its workability, shotcrete performance and mechanical properties under different water-to-cement ratios, fly ash content, superplasticizer dosage, and steel fiber content. The tunnel excavation and support were investigated by conducting finite element numerical simulation analysis and was used in 3 tunnel lining pipes in Zhonggouwan tailing pond. The major findings are as follows: (1) The water-to-cement ratio (w/c ratio) significantly impacted the compressive strength of WSSFHTHS. The highest 28-day compressive strength of 60 MPa was achieved when the w/c ratio was 0.38; (2) Adding fly ash improved the workability and shotcrete performance and strength development of WSSFHTHS. The best anti-permeability performance was achieved when the fly ash constituted 15%, with the lowest permeability coefficient of 4.596 × 10-11 cm/s; (3) The optimum superplasticizer dosage for WSSFHTHS is 0.8%. It provided the best workability and shotcrete performance. Excessive dosage resulted in water bleeding and poor aggregate encapsulation, while insufficient dosage decreased flowability and adversely affected shotcrete performance; (4) The dosage of steel fibers significantly impacted the flexural and tensile strength of WSSFHTHS. When the steel fiber dosage was 45 kg/m³, the 28-day flexural and tensile strengths were 8.95 MPa and 6.15 MPa, respectively; (5) By integrating existing shotcrete techniques, the optimal lining thickness was 80 mm for WSSFHTHS per simulation. The results revealed that after using WSSFHTHS, the displacement of the tunnel surrounding the rock significantly improved, with no cracks or hollows, similar to the simulation results.

• 의료법학
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• 제13권2호
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• pp.141-178
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• 2012

Korea's medical law prohibited medical advertisements in principle and permitted them on an exceptional cases. However, the decision of the Constitutional Court of 20005. 10. 27. 20003 Heonga 3, it was changed to a negative system which allows advertisements in principle and restricted only exceptionally. Dramatic increase of medical advertisements was made after that and many argued more deregulation because there was actually heavy regulations. In particular, there is almost no actual regulation on the article type advertisement due to the reason of protection of the freedom of press, media and occupation. However, there may be an unjust result if a specific article or specialists' opinion is made using a newspaper, broadcasting or magazine as a form of article type advertisement to specific medical specialists or medical institution or medical treatment method that falsifies consumers or makes consumers confused by unjust medical expectations or reliability, that also deteriorates just competition and that causes the misrecognition of consumers. In fact, there were actual damages of article type advertisements on the eye whitening surgery not long after the transfer to a negative system of medical advertisements. Victims raised a medical proceeding against the doctor who carried out the surgery, but there is actually no systematic warranty except for the indemnity request. Thus, this case demonstrated a vulnerable result of a negative system. As such, it is problematic that there is no proper regulations defined in the current law and regulations because of the reason of the protection of the freedom of press, publication and occupation despite damages of such article type advertisements. Accordingly, it is urgent to apply the current prevention regulations on the article type advertisements strictly, and to set up specific regulations.

• 한국언론정보학보
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• 제30권
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• pp.175-201
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• 2005

본 논문은 '다양성'이라는 규범적 가치에 입각해 뉴스 기사 선별 및 취재 경로와 관련한 미 신문의 뉴스 제작 방식에는 어떤 변화가 진행돼 왔는지를 통시적으로 살펴보고 있다. 이에 따라 본고에서는 '뉴스 토픽'과 '정보원' 등 두 가지 분야에서 지난 50년간 뉴욕 타임스와 시카고 트리뷴, 로스앤젤레스 타임스 등 3대 유력 일간지의 1면 기사를 분석, 연대기적인 가치 변화를 추적해 보았다. 데이터 분석 결과, 지난 반세기 동안 미 신문에서 정부 및 정치권에 대한 정보원의 의존도는 지속적으로 줄어들고 있는 반면, 기업/산업체발 정보원의 등장은 점차 빈번해 지고 있는 것으로 나타났다. 이와 함께, 뉴스 주제의 분포에 있어서는 사건, 사고 기사의 감소와 군사, 안보기사의 퇴조 속에, 경제, 건강, 교육 등과 같은 주제가 점차 활발하게 다뤄지고 있는 것으로 조사됐다. 그러나 전통적인 비인기 주제였던 빈곤, 노동, 소수자, 사회 갈등 등과 같은 토픽들은 시대를 거듭해도 제자리를 맴돌거나 오히려 줄어들고 있는 것으로 나타났다.

• Structural Engineering and Mechanics
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• 제30권6호
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• pp.651-664
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• 2008

The purpose of this study is to develop a rehabilitation technique for heavily earthquake damaged masonry buildings. A full scale one storey masonry building with window and door openings was manufactured and tested on the shock table by applying increased amplitude free vibration up to the point where heavy earthquake damage was observed. Damaged test building was rehabilitated with vertical and diagonal steel straps and then tested again. The effectiveness of improvements obtained by the rehabilitation technique was investigated. Steel straps improved the lateral strength and stiffness of masonry walls and limited the lateral displacement of building. Stability of the masonry walls were also improved by the steel straps. Steel straps reduced the natural period of the earthquake damaged masonry building and prevented the failure of the building at the same amplitude of free vibration.

• Smart Structures and Systems
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• 제11권5호
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• pp.453-476
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• 2013

DuraMote is a remote sensing system developed for the "NIST TIP project: next generation SCADA for prevention and mitigation of water system infrastructure disaster". It is designed for supervisory control and data acquisition (SCADA) of ruptures in water pipes. Micro-electro mechanical (MEMS) accelerometers, which record the vibration of the pipe wall, are used detect the ruptures. However, the performance of Duramote cannot be verified directly on a water distribution system because it lacks an acceptable recordable level of ambient vibration. Instead, a long-span cable-stayed bridge is an ideal test-bed to validate the accuracy, the reliability, and the robustness of DuraMote because the bridge has an acceptable level of ambient vibration. The acceleration data recorded on the bridge were used to identify the modal properties of the structure and to verify the performance of DuraMote. During the test period, the bridge was subjected to heavy rain, wind, and a typhoon but the system demonstrates its robustness and durability.

• Geomechanics and Engineering
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• 제16권4호
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• pp.341-353
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• 2018

A reinforced concrete pedestrian tunnel is constructed under a four-track surface railway. Heavy rainfall and soil exposure to drying lead to soil with different water content throughout the year. A railway is an open utility that is subject to rainfall without control on the quantity of the water on it and when there is a tunnel under a railway, the water content of the soil around the tunnel is very influential. This research shows the effects of change of water content in the soil around a pedestrian tunnel under a four-track surface railway. The pedestrian tunnel and the soil block around the tunnel are modeled in 3D by the FEM and are studied under the vibrations induced by the moving trains on the four-track surface railway for different soil water contents and the effects of the soil water content on the dynamic behavior of the tunnel and the surrounding soil are demonstrated.

• Composites Research
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• 제18권6호
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• pp.48-53
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• 2005

본 연구에서는 방탄물성이 매우 우수한 알루미나-실리카계 방탄재료(PL-8)의 방탄물성을 향상시키기 위해 성형압력 및 소결온도를 변화시켰다. 물리/기계적 물성을 측정 한 후 성형작약(HEAT)/운동에너지(KE)탄에 대한 방탄물성을 측정하여 분석하였다. 그 결과 소결온도 $1235^{\circ}C$에서 성형작약탄에 대한 방탄물성이 가장 높았으며 기 개발된 알루미나-실리카계 방탄재료 (PL-8)에 비해 $22\%$ 방탄물성이 향상되었다.

• Computers and Concrete
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• 제8권6호
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• pp.617-629
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• 2011

In this investigation, reservoir sediment and municipal sewage sludge were sintered to form the artificial lightweight aggregates. The sintered aggregates were compared with the commercialized lightweight aggregates to in terms of potential alkali-silica reactivity and chemical stability based on analyses of their physical and chemical properties, leaching of heavy metal, alkali-silica reactivity, crystal phase species and microstructure. Experimental results demonstrated that the degree of sintering of an aggregate affected the chemical resistance more strongly than did its chemical composition. According to ASTM C289-94, all potential alkali-silica reactivity of artificial lightweight aggregates were in the harmless zone, while the potential reactivity of artificial lightweight aggregates made from reservoir sediment and municipal sewage sludge were much lower than those of traditional lightweight aggregates.

• Structural Engineering and Mechanics
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• 제28권2호
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• pp.221-238
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• 2008

Numerical solution to buckling analysis of beams and columns are obtained by the method of differential quadrature (DQ) and harmonic differential quadrature (HDQ) for various support conditions considering the variation of flexural rigidity. The solution technique is applied to find the buckling load of fully or partially embedded columns such as piles. A simple semi- inverse method of DQ or HDQ is proposed for determining the flexural rigidities at various sections of non-prismatic column ( pile) partially and fully embedded given the buckling load, buckled shape and sub-grade reaction of the soil. The obtained results are compared with the existing solutions available from other numerical methods and analytical results. In addition, this paper also uses a recently developed technique, known as the differential transformation (DT) to determine the critical buckling load of fully or partially supported heavy prismatic piles as well as fully supported non-prismatic piles. In solving the problem, governing differential equation is converted to algebraic equations using differential transformation methods (DT) which must be solved together with applied boundary conditions. The symbolic programming package, Mathematica is ideally suitable to solve such recursive equations by considering fairly large number of terms.