• Computers and Concrete
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• 제20권5호
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• pp.529-537
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• 2017

Excessively elevated temperature can lead to cracks in prestressed concrete (PC) continuous bridge with box girder on the pier top at cement hydration age. This paper presents a case study for evaluating the behavior of PC box girder during the early hydration age using a two-stage computational model, in the form of computer program ANSYS, namely, 3-D temperature evaluation and determination of mechanical response in PC box girders. A numerical model considering time-dependent wind speed and ambient temperature in ANSYS for tracing the thermal and mechanical response of box girder is developed. The predicted results were compared to show good agreement with the measured data from the PC box girder of the Zhaoshi Bridge in China. Then, based on the validated numerical model three parameters were incorporated to analyze the evolution of the temperature and stress within box girder caused by cement hydration heat. The results of case study indicate that the wind speed can change the degradation history of temperature and stress and reduce peak value of them. The initial casting temperature of concrete is the most significant parameter which controls cracking of PC box girder on pier top at cement hydration age. Increasing the curing temperature is detrimental to prevent cracking.

• 전기학회논문지
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• 제59권2호
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• pp.291-297
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• 2010

A system called demand response programs (DRP) is being introduced among various countries owing to the lack of new generation capacity and the higher fuel generation cost. It is a program which provides for the end-users to select their consumption of electricity by recognizing the value of their consumption in real time. That is, Demand Response can be defined as the changes in electric usage by end-use customers from their normal consumption patterns in response to changes in the price of electricity or other signals. It is expected that the effects of DRP are preventing price spike, improving supply reliability and social welfare and increasing option of customers. Considering the customer's thermal comfort zone, this paper determines the most profitable combination of optimal incentives and amounts of load reduction for a retailer to maximize profits according to predicted outdoor temperatures while implementing DRP.

• Journal of Hydrospace Technology
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• 제1권1호
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• pp.29-40
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• 1995

This paper describes the procedure to predict steady and unsteady performances of a contrarotating propeller(CRP) by a mixed formulation of the boundary value problem(BVP) far the flow around a CRP. The blade BVP is treated by a classical vortex lattice method, whereas the hub BVP is solved by a potential-based panel method. Blades and trailing wakes are represented by a vortex and/or source lattice system, and hubs are represented by normal dipole and source distributions. Both forward and aft propellers are solved simultaneously, thus treating the interaction effect without iteration. The unsteady performance is computed directly in time domain. The new numerical procedure requires a large amount of storage and computing time, which is however no longer a limit in a modern computer system. Sample computations show that the steady performance compares very well with the experiments. The predicted unsteady behavior shows that the dominant harmonics of the total forces are multiples of not only the number of blades of the forward and aft propellers but also the product of both blade numbers. The magnitude of the latter harmonics, present also in uniform oncoming flow, may reach abort 50% of the mean torque for the aft propeller, which in turn may cause a serious vibration problem in the complicated contrarotating shafting system.

• Earthquakes and Structures
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• 제24권5호
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• pp.377-391
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• 2023

The high seismic risk has once again revealed in Türkiye with two major earthquakes that occurred on 06.02.2023, which took its place among the most destructive earthquakes in the last century. Totally, 65 earthquakes that occurred in the historical period in Türkiye were taken into account within the scope of this study. The seismic parameters were compared by considering the last two earthquake hazard maps for the epicenters of these earthquakes. Earthquake Intensity (I) of historical earthquakes were converted to Peak Ground Acceleration (PGA) by using suggested relations. Structural analyzes were performed for a sample reinforced-concrete building by using the obtained PGA's and predicted PGA's in the last two earthquake hazard maps. In the structural analysis, two different material groups such as low (C12-S220) and normal (C25-S420) were selected. As the material strength increased, the period value decreased, while the seismic capacity and stiffness increased. It has been determined that there are differences between the measured and proposed seismic risks for some earthquakes, and as a result, there are significant differences between the expected target displacement values from the structures. Therefore, it will not be possible to estimate the damage and to determine the building performance realistically. The main purpose of the study is to reveal whether the earthquake risk is adequately represented on seismic and structural parameters.

• 한국농공학회논문집
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• 제66권2호
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• pp.1-12
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• 2024

In order to integrate two consolidation theories of Terzaghi's consolidation theory and Mesri's secondary compression theory and to identify a model suitable for analyzing stress-strain behavior over time, numerical analysis on consolidation tests were conducted using a modified cam-clay model and a soft soil creep model and the following conclusions were obtained. The results of numerical analysis applying the theory that a linear proportional relationship is established between the void ratio at logarithmic scale and the permeability coefficient at logarithmic scale is better agreement with the result of oedometer test than the results of applying constant hydraulic conductivity. The modified cam-clay model is a model that does not include secondary compression, but the slope of the normal consolidation line corresponding to the compression index of the standard consolidation test includes secondary compression, so the actual settlement curve over time is lower than the predicted value through numerical analysis. It always gets smaller. Other previous studies that applied Terzaghi's consolidation theory to consolidation test analysis showed the same results and were cross-confirmed. The soft soil creep model, which includes secondary compression in the theory, showed good agreement in all sections including secondary compression in the consolidation test results. It was judged appropriate to use a soft soil creep model when performing numerical analysis of soft clay ground.

• 한국항공우주학회지
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• 제49권6호
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• pp.521-528
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• 2021

위협평가가 끝난 공중항적에 대해 적절한 대응무기를 할당하기 위해서는 교전예상지점을 고려하여 교전적합성을 평가하는 것이 필요하다. 논문에서는 공중항적이 교전공간을 통과할 때 공중항적의 상대거리, 접근방위각 및 고도 등 다변량 속성정보를 가지고 베이지안 정리를 적용하여 교전공간내 위치에 따른 격추확률을 계산하는 방법을 제시하였다. 계산결과 교전공간내에서의 각 지점별 격추확률값의 분포형태는 최적의 예상요격지점을 기준으로 다변량 정규분포를 따르고 있음을 확인하였고, 계산된 격추확률값은 교전공간을 통과하는 공중항적의 교전가능성 평가에 적용가능할 것으로 기대된다.

• 대한핵의학회지
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• 제34권1호
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• pp.39-54
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• 2000

목적: 디피리다몰 부하 심근 관류 SPECT 를 관동맥질환 환자의 예후 예측에 이용하여 장기간 추적하였을 때 정상 심근 SPECT 소견의 비례위험도가 달라지는지를 조사하여 정상 SPECT로 언제까지 예후가 양호하다고 예측할 수 있는지 보았다. 대상 및 방법: 관동맥질환이 의심되어 심근 관류 SPECT를 시행한 환자 1,169명을 대상으로 심장원인 사망이나 심근 경색이 발생한 중한 사건과 관동맥우회로술이나 관동맥성형술을 시행한 경한 사건을 합한 전체 심장사건의 발생률과 예측성능을 분석하였다. 비례위험도의 시간의존성을 분석하는 통계적 방법을 개발하고 적용하여 추적기간에 따른 예측도 차이를 조사하였다. 결과: 다변량 Cox 비례위험도 모델에서 전체 심장 사건을 예측하는데 심근 관류 SPECT의 가역성관류 감소가 독립적인 예후 예측 성능을 보였으며 관동맥조영술 소견에 더하여 부가효용을 나타냈다. 심근 SPECT의 가역성관류감소는 중한 사건을 예측하는 독립적 예측성능을 보였으나 관동맥조영술에 더하여 부가효용을 나타내지는 않았다. SPECT 소견의 비례위험도는 추적기간이 경과하면서 증가하였다. 전체 심장사건을 예측하는 비례위험도가 심근 SPECT 정상군에서 추적기간 말기에 유의하게 달라졌으며(p<0.001) 정상심근 SPECT의 위험률의 변이점은 4.4년이었다. 결론: 심근 SPECT에 나타난 가역성 관류 감소는 전체심장 사건을 예측하는 독립적이고 부가적인 성능을 보였다. 심근 관류 SPECT에서 정상일 때 장기추적 중 4.4년 후에는 예후 예측 위험도가 유의하게 증가하였다.

• 한국지반공학회지:지반
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• 제10권3호
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• pp.55-78
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• 1994

풍화화강토는 화강암이나 화강편마암이 풍화된 흙으로 건설현장에서 빈번하게 접하고 있는 우리나라의 대표적인 토질이며, 공기에 노출되거나 물과 접촉하면 강도특성이 쉽게 변화하는 문제성이 많은 토질로 알려져 있다. 이 연구에서는 이러한 풍화화 강토의 역학적 특성을 파악하기 위하여 기원과 구성성분이 다른 안동과 김천에서 풍화화 강토를 채취하여 실내다짐에 의하여 공시체를 제작한 후에 등방압밀배수 및 비배수시험을 실시하였으며, 시험결과를 분석하여 여러가지의 강도특성을 분석하고 Cam-Clay모델에의 적용성을 검토하였다. 안동과 김천시료의 기원은 상이하지만 전단저 항각과 압축특성은 실용적으로 동일하였다. 비체적대 평균유효응력공간에서 정규압축곡선과 한계상태선이 유일한 것으로 나타났으며 응력-변형률 거동특성은 점성토나 모래의 특성과는 다르게 나타났다. 과압밀비가 2이상일 경우에 유효 응력비가 한계상태에 수렴하였지만 응력-변형률 관계에서 최대음력이 나타나지 않았다. 응력경로는 이론적인 Roscoe면 아래로 이동하면서 한계상태에 접근하였다. 정규압밀비배수시험에서 간극수압계수(A,)는 1.3정도이었는데 이것은 전단중에 발생하는 입자파쇄현상에 의한 것으로 판단되었다. 과압밀비가 7정도에서 부(-)의 간극수압과 체적팽창현상이 발생하였다. 구성식에 의하여 실측치와 이론치를 비교한 결과, 배수거동에서는 만족할만한 결과를 구할 수 있었다.

• Asian Pacific Journal of Cancer Prevention
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• 제15권4호
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• pp.1863-1869
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• 2014

The amplification of telomerase component (TERC) gene could play an important role in generation and treatment of haematological malignancies. This present study was aimed to investigate copy number amplification status of TERC gene in chronic myeloid leukaemia (CML) patients who were being treated with imatinib mesylate (IM). Genomic DNA was extracted from peripheral blood of CML-IM Resistant (n=63), CML-IM Respond (n=63) and healthy individuals (n=30). TERC gene copy number predicted (CNP) and copy number calculated (CNC) were determined based on $Taqman^{(R)}$ Copy Number Assay. Fluorescence in situ hybridization (FISH) analysis was performed to confirm the normal signal pattern in C4 (calibrator) for TERC gene. Nine of CML patients showed TERC gene amplification (CNP=3), others had 2 CNP. A total of 17 CML patients expressed CNC>2.31 and the rest had 2.31>CNC>1.5. TERC gene CNP value in healthy individuals was 2 and their CNC value showed in range 1.59-2.31. The average CNC TERC gene copy number was 2.07, 1.99 and 1.94 in CML-IM Resistant patients, CML-IM Respond and healthy groups, respectively. No significant difference of TERC gene amplification observed between CML-IM Resistant and CML-IM Respond patients. Low levels of TERC gene amplification might not have a huge impact in haematological disorders especially in terms of resistance towards IM treatment.

• 정보보호학회논문지
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• 제31권3호
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• pp.401-410
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• 2021

최근 산업제어시스템은 인터넷에 연결하지 않은 폐쇄적 상태로 운영하는 과거와 달리 원격지에서 데이터를 확인하고 시스템 유지보수를 위해서 개방적 통합적인 스마트한 환경으로 변화하고 있다. 반면에 상호연결성이 증가하는 만큼 산업제어시스템을 대상으로 사이버 공격이 증가함에 따라 산업 공정의 비정상 탐지를 위한 다양한 연구가 진행되고 있다. 산업 공정의 결정적 규칙적인 점을 고려하여 정상데이터만을 학습시킨 탐지 모델의 결과 값과 실제 값을 비교해서 비정상 여부를 판별하는 것이 적절하다고 할 수 있다. 본 논문에서는 HAI 데이터셋 20.07과 21.03을 이용하며, 순환신경망에 게이트 구조가 적용된 GRU 알고리즘으로 서로 다른 타임 스텝을 적용한 모델을 결합하여 앙상블 모델을 생성한다. 그리고 다양한 성능평가 분석을 통해 단일 모델과 앙상블 순환신경망 모델의 탐지 성능을 비교하였으며 제안하는 모델이 산업제어시스템에서 비정상 탐지하는데 더욱 적합한 것으로 확인하였다.