• Nuclear Engineering and Technology
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• 제43권6호
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• pp.531-546
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• 2011

The backward differentiation formula (BDF) method is applied to a three-dimensional reactor kinetics calculation for efficient yet accurate transient analysis with adaptive time step control. The coarse mesh finite difference (CMFD) formulation is used for an efficient implementation of the BDF method that does not require excessive memory to store old information from previous time steps. An iterative scheme to update the nodal coupling coefficients through higher order local nodal solutions is established in order to make it possible to store only node average fluxes of the previous five time points. An adaptive time step control method is derived using two order solutions, the fifth and the fourth order BDF solutions, which provide an estimate of the solution error at the current time point. The performance of the BDF- and CMFD-based spatial kinetics calculation and the adaptive time step control scheme is examined with the NEACRP control rod ejection and rod withdrawal benchmark problems. The accuracy is first assessed by comparing the BDF-based results with those of the Crank-Nicholson method with an exponential transform. The effectiveness of the adaptive time step control is then assessed in terms of the possible computing time reduction in producing sufficiently accurate solutions that meet the desired solution fidelity.

• 대한기계학회논문집A
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• 제25권4호
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• pp.734-740
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• 2001

In this paper the stress intensity factor under uniform pressure in the arbitrarily-shaped plane crack configuration transformed elliptic crack by Mobius mapping are determined. Using Dysons formula Boussinesq-Papkovich potentials for mode I deformation are constructed. In the example the stress intensity factors are approximately calculated by least square method.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 추계학술대회논문집A
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• pp.117-122
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• 2000

In this paper the stress intensity factor under uniform pressure in the arbitrarily-shaped plane crack configuration transformed elliptic crack by Mobius mapping are determined. Using Dyson's formula Boussinesq-Papkovich potentials for mode I deformation are constructed. In the example the stress intensity factors are approximately calculated by least square method.

• Journal of Electrical Engineering and Technology
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• 제8권6호
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• pp.1409-1414
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• 2013

A new calculation method for iron loss coefficients is proposed by using the Steinmetz equation from Epstein data. The hysteresis loss must have linear characteristic according to the frequency. However, the existing iron loss coefficients are defined by formula of frequency. In this case, the hysteresis loss has non-linear characteristics by frequency. So, in this paper, the iron loss coefficients were defined by a function of the magnetic flux density, and the iron loss calculation is applied for Interior Permanent Magnet Synchronous Motor(IPMSM) of 600(W) and 200(W). The iron loss calculation results and the experimental results are compared according to the various materials.

• Journal of Yeungnam Medical Science
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• 제32권2호
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• pp.90-97
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• 2015

Background: Contrast-induced nephropathy (CIN) can cause serious adverse effects. To reduce the occurrence of CIN related computed tomography (CT) in emergency patients, we assessed the respective roles of serum creatinine (SCr) alone and estimated glomerular filtration rate (eGFR) as an early predictor for CIN related CT. Methods: For patients with SCr <1.5 mg/dL who underwent CT in emergency department (ED) between September 2012 and October 2013, we assessed the prevalence of CIN and its adverse effects. The Modification of Diet in Renal Disease Study (MDRD) and Cockcroft-Gault (CG) formula was used for the calculation of eGFR. Practical calculation was performed by electronic medical record (EMR) system for MDRD and internet calculating service for CG. And we investigated the prevalence of CIN in eGFR $<60mL/min/1.73m^2$ before CT. Results: A total of 1,555 patients were enrolled. The prevalence of CIN after CT was 4.6% and it showed correlation with renal deterioration, increased in-hospital mortality, and prolonged hospitalization. Despite baseline SCr <1.5 mg/dL, among enrolled patients, 11.3% as MDRD equation and 29.5% as CG formula were $<60mL/min/1.73m^2$ and in this condition, the prevalence of CIN was significantly high (odds ratio was 2.87 [1.64-5.02] as MDRD equation and 2.03 [1.26-3.29] as CG formula). Conclusion: Just SCr <1.5mg/dL was not appropriate to recognize preexisting renal insufficiency, but eGFR using MDRD equation was useful in predicting the risk of CIN related CT in ED. Using EMR, calculation of eGFR can be easier and more convenient.

• Nuclear Engineering and Technology
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• 제56권1호
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• pp.78-91
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• 2024

Double steel plate concrete composite shear wall (SCSW) has been widely utilized in nuclear power plants and high-rise structures, and its shear connectors have a substantial impact on the seismic performance of SCSW. Therefore, in this study, the mechanical properties of SCSW with angle stiffening ribs as shear connections were parametrically examined for the reactor containment structure of nuclear power plants. The axial compression ratio of the SCSW, the spacing of the angle stiffening rib arrangement and the thickness of the angle stiffening rib steel plate were selected as the study parameters. Four finite element models were constructed by using the finite element program named ABAQUS to verify the experimental results of our team, and 13 finite element models were established to investigate the selected three parameters. Thus, the shear capacity, deformation capacity, ductility and energy dissipation capacity of SCSW were determined. The research results show that: compared with studs, using stiffened ribs as shear connectors can significantly enhance the mechanical properties of SCSW; When the axial compression ratio is 0.3-0.4, the seismic performance of SCSW can be maximized; with the lowering of stiffener gap, the shear bearing capacity is greatly enhanced, and when the gap is lowered to a specific distance, the shear bearing capacity has no major affect; in addition, increasing the thickness of stiffeners can significantly increase the shear capacity, ductility and energy dissipation capacity of SCSW. With the rise in the thickness of angle stiffening ribs, the improvement rate of each mechanical property index slows down. Finally, the shear bearing capacity calculation formula of SCSW with angle stiffening ribs as shear connectors is derived. The average error between the theoretical calculation formula and the finite element calculation results is 8% demonstrating that the theoretical formula is reliable. This study can provide reference for the design of SCSW.

• Journal of Advanced Marine Engineering and Technology
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• 제33권6호
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• pp.965-974
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• 2009

The current study reviews the formula used to calculate the stability of an artificial reef in the breaking wave zone of coastal waters. A comparison was carried out between the existing formula and a new formula that takes into account the water particle velocity in the breaking wave zone. Water particle velocity was analyzed using the Fluent (CADMAS-SURF) software program. The new formula took into various factors, including the difference in the drag coefficient due to the direction of the current and the ratio of distance between two reefs. The drag coefficient of the artificial reef due to the direction of the current was 0.84 when the distance ratio was 0.5. When the artificial reef was placed at 45 degree angle to the current, the product of the drag coefficient and the project area were 40 to 46 % greater than when the reef was placed at 90 degree angle. Our results regarding the stability of an artificial reef indicate that the new formula provides the designers of artificial reefs with a more rational and economic design rationale rather than the existing formula.

• 한국가정과교육학회지
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• 제23권3호
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• pp.121-138
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• 2011

1962년 한국인 영양권장량의 제정부터 7차 개정을 거쳐 한국인 영양섭취기준으로 전환되고, 한국인 영양섭취기준이 개정되기까지 에너지를 중심으로 섭취권장량의 양적 변화 및 산출 방법 변화를 살펴보았다. 이에 근거하여 한국인의 에너지 섭취권장량의 개정 방향 및 설정 방법 등에 대하여 검토하고, 설정의 새로운 기법 마련을 위한 기초자료로 활용될 수 있기를 기대한다. 에너지 섭취권장량은 기초대사량(또는 휴식대사량), 활동대사량, 식이성 발열효과의 3가지 요인을 합한 양이다. 1962년 체중을 대입하여 산출하는 공식으로 시작하여 95년에는 휴식대사량(체중 대입 산출)에 평균활동계수를 적용하는 공식으로 전환되었다. 그리고 2005년 연령, 체격(신장, 체중)과 함께 4단계 활동단계를 구분, 대입하여 산출하는 에너지필요추정량이라는 새로운 에너지 섭취권장량이 소개되었다. 1962년 제정 이후 50년이 조금 안 되는 기간 동안 다소의 차이는 있으나 모든 연령대에서 에너지 섭취권장량이 감소하였으며, 이는 생활환경의 변화 즉 활동(노동)량의 감소가 원인으로 생각된다. 비만 인구의 증가와 이에 따른 만성 질환 이환율이 증가함에 따라 에너지 섭취권장량만은 다른 영양소와 달리 개인별 산출 및 적용이 권고되고 있으며, 현재 개인별 산출이 가능하다. 에너지 섭취권장량의 보다 정확한 추정을 위하여 우리 국민 대상의 에너지 소비량 연구 결과를 적용한 우리 국민의 공식이 마련될 수 있기를 기대한다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1989년도 하계종합학술대회 논문집
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• pp.216-220
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• 1989

Direct calculation algorithm for the elements of A matrix is suggested for a single machine connected to the infinite bus. Excitation system and power system stabilizer are included. When A matrix is partitioned into seven submatrices, we can identify the location of non-zero elements and formula for each element. No matrix inversion and multiplication are necessary.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 춘계학술대회논문집
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• pp.411-416
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• 2002

This paper is concerned with the development of web-based engineering calculation program using Javascript. Recently, various techniques are developed based on the advance of the internet environment. The Javascript can be used in the client PC without any interpreter which is necessary in Java. Simple formula can be easily constructed using the Javascript and the results can be readily available without any playing. In this study, we demonstrated the method of constructing engineering web useful for engineers.