• 한국지진공학회논문집
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• 제3권3호
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• pp.9-20
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• 1999

프레임 구조물의 접합부 손상을 평가하기 위하여 접합부 손상모델과 신경망기법을 이용한 손상평가기법을 제안하였다 구조물의 보-기둥 접합부를 접합부의 회전강성을 갖는 등가의 스프링요소로 표현하였으며 접합부의 손상도는 손상 전 후의 고정도계수의 감소비율로 정의하였다 손상평가를 위하여 다층퍼셉트론즈 신경망 기법을 제안하였으며 손상평가성능을 향상시키기 위하여 부분구조추정법, 노이즈첨가학습, 자료교란법등의 기법을 적용하였다 10층 프레임 구조물에 대한 수치 예제해석과 2층 프레임 구조물에 대한 실험 예제해석을 통하여 제안기법의 유용성을 평가하였다 계측지점이 일부분으로 제한되어 있고 계측자료에 심한 계측오차가 포함되어 있는 경우에도 손상평가가 합리적으로 이루어질수 있음을 알 수 있었다.

• International Journal of Advanced Culture Technology
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• 제8권1호
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• pp.62-70
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• 2020

As an effective means of price discrimination, some suppliers offer trade credit to the distributors in order to stimulate the demand for the product they produce. The availability of the delay in payments from the supplier enables discount of the distributor's selling price from a wider range of the price option in anticipation of increased customer's demand. Since the distributor's lot-size is affected by the demand for the customer, the distributor's lot-size and the selling price determination problem is interdependent and must be solved at the same time. Also, in many common business transactions, the distributor pays the shipping cost for the order and hence, the distributor's ordering cost consists of a fixed ordering cost and the shipping cost that depend on the order quantity. In this regard, we deal with the joint lot-size and price determination problem when the supplier allows delay in payments for an order of a product. The positive effects of credit transactions can be integrated into the EOQ (economic order quantity) model through the consideration of retailing situations, where the customer's demand is a function of the distributor's selling price. It is also assumed that the distributor's order cost consists of a fixed ordering cost and the variable shipping cost. We formulate the distributor's mathematical model from which the solution algorithm is derived based on properties of an optimal solution. A numerical example is presented to illustrate the algorithm developed.

• 한국지반공학회논문집
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• 제29권1호
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• pp.61-70
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• 2013

본 연구에서는 2차원 유한차분 해석을 이용하여 절리암반에 시공된 말뚝기초의 선단지지력을 분석하였다. 이를 위해 암반의 절리상태를 고려할 수 있는 Hoek-Brown 항복규준을 이용하여 다양한 조건의 수치해석이 수행되었다. 넓은 범위의 절리상태를 고려하기 위하여 GSI를 주 매개변수로 설정하였고 말뚝 직경, 암반의 일축압축강도, Hoek-Brown 상수 $m_0$의 매개변수 영향을 살펴보았다. 본 연구결과 매개변수들의 변화에 따른 절리 암반에 설치된 말뚝기초의 선단지지력 변화 경향을 확인하였고 이러한 결과를 토대로 매개변수 분석에 따른 선단지지력 결과를 도출하였다.

• Steel and Composite Structures
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• 제35권3호
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• pp.327-341
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• 2020

The use of high-strength steel and concrete in the construction industry has been gaining increasing attention over the past few decades. With it comes the need to utilise high-strength structural bolts to ensure the design load to be transferred safely through joint regions, where the space is limited due to the reduced structural dimensions. However, research on the behaviour of high-strength structural bolts under various loading combinations is still insufficient. Most of the current design specifications concerning high-strength structural bolts were established based on a very limited set of experimental results. Moreover, as experimental programs normally include limited design parameters for investigation, finite element analysis has become one of the effective methods to assist the understanding of the behaviour of structural components. An accurate and simple full-range stress-strain model for high-strength structural bolts under different loading combinations was therefore developed, where the effects of bolt fracture was included. The ultimate strength capacities of various structural bolts obtained from the present experimental program were compared with the existing design provisions. Furthermore, design recommendations concerning the pure shear and tension, as well as combined shear and tension resistance of Grade 10.9 high-strength structural bolts were provided.

• 한국정밀공학회지
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• 제28권5호
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• pp.623-631
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• 2011

Metallic sandwich panels based on a truss core structure have been developed for a wide range of potential applications with their lightweight and multi-functionality. Structural performance of sandwich panels can be predicted from the studies on mechanical behavior of a unit cell of truss core structures. Analytical investigations on the unit cell provide approximated guidelines for the design of overall core structures for a specific application in short time. In this study, the effects of geometrical parameters on mechanical behavior of a pyramidal shape of unit cell were investigated with analytical models. The unit cell with truss member angle of 45 degree was considered as reference model and other models were designed to have the same weight and projected area but different truss member angle. All truss members were assumed to be connected with pin joint in analytical models. Under the assumptions, the equivalent strength and stiffness of the unit cell under compressive and shear loads were predicted and compared. And finally, the optimum core member angle to have maximum mechanical property could be calculated and verified with FE analysis results.

• 한방재활의학과학회지
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• 제25권4호
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• pp.161-167
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• 2015

Objectives The objective of this study is to report the improved case of Korean medicine treatment with Shinbaro3 pharmacopuncture for supraspinatus tendinitis and subdeltoid bursitis. Methods We used Shinbaro3 pharmacopuncture with other Korean medicine treatment (acupuncture, herbal medicine, cupping and chuna) for this patient. This case is measured and assessed by Numerical Rating Scale (NRS), shoulder range of motion (ROM) and shoulder physical examination. Results The NRS decreased from 10 to 2 and the patient showed nearly full shoulder range of motion. Also physical examination of shoulder was improved. Conclusions Korean medicine treatment with Shinbaro3 pharmacopuncture is proved to be helpful to relieve pain and recover function on shoulder joint.

• Steel and Composite Structures
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• 제27권6호
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• pp.717-725
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• 2018

One of the most important design criteria in military tunnels and armoured doors is to resist the blast loads with minimum structural weight. This can be achieved by using steel sandwich panels. In this paper, the nonlinear behaviour of steel sandwich panels, with different core materials: (1) Hollow (no core material); (2) Rigid Polyurethane Foam (RPF); and (3) Vulcanized Rubber (VR) under free air blast loads, was investigated using detailed 3D nonlinear finite element models in Ansys Autodyn. The accuracy of the finite element model proposed was verified using available experimental test data of a similar steel sandwich panel tested. The results show the developed finite element model can be reliably used to simulate the nonlinear behaviour of the steel sandwich panels under free air blast loads. The verified finite element model was used to examine the different parameters of the steel sandwich panel with different core materials. The result shows that the sandwich panel with RPF core material is more efficient than the VR sandwich panel followed by the Hollow sandwich panels. The average maximum displacement of RPF sandwich panel under different ranges of TNT charge (1 kg to 10 kg at a standoff distance of 1 m) is 49% and 53% less than the VR and Hollow sandwich panels, respectively. Detailed empirical design equations were provided to quantify the maximum deformation of the steel sandwich panels with different core materials and core thickness under a different range of blast loads. The developed equations can be used as a guide for engineer to design steel sandwich panels with RPF and VR core material under a different range of free air blast loads.

• Geomechanics and Engineering
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• 제27권5호
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• pp.497-509
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• 2021

A large deformation FEM (Finite Element Method) based numerical analysis has been performed to study the behaviour of the bell-shaped anchor embedded in undrained saturated (cohesive) soil with the help of finite element based software ABAQUS. A typical model anchor with bell-diameter of 0.125 m, embedded in undrained saturated soil with varying cohesive strength (from 5 kN/m² to 200 kN/m²) has been chosen for studying the characteristic behaviour of the bell-shaped anchor installed in cohesive soil. Breakout factors have been evaluated for each case and verified with the results of experimental model tests for three different types of soil samples. The maximum value of breakout factor was found as about 8.5 within a range of critical embedment ratio of 2.5 to 3. An explicit model has been developed to estimate the breakout factor (F_c) for uplift capacity of bell-shaped anchor within clay mass in terms of H/D ratio (embedment ratio). It was also found that, the ultimate uplift capacity of the anchor increases with the increase of the value of cohesive strength of the soil and H/D ratio. The empirical equation developed in the present investigation is usable within the range of cohesion value and H/D ratio from 5 kN/m² to 200 kN /m² and 0.5 to 3.0 respectively. The proposed model has been validated against data obtained from a series of model tests carried out in the present investigation. From the stress-profile analysis of the soil mass surrounding the anchor, occurrence of stress concentration is found to be generated at the joint of anchor shaft and bell. It was also found that the vertical and horizontal stresses surrounding the anchor diminish at about a distance of 0.3 m and 0.15 m respectively.

• 지구물리와물리탐사
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• 제10권1호
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• pp.19-28
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• 2007

이 연구에서는 심부 퇴적층의 S-파 속도구조 추정을 위하여 여러 지점에서 획득된 수신함수와 표면파 위상속도 자료를 이용하는 유전자 알고리즘 기반 복합 역산기법을 제안하였다. 이 방법은 서로 다른 지점에서 획득된 자료를 동시에 역산하기 위해, 역산대상 지역 내 모든 측점 상부의 지층 물성 - 특히 S-파 속도 -이 균열하다고 가정하는 방식으로 역산대상 지역 상부층의 층서적 연속성을 고려한다. 인공합성 자료를 이용한 수치실험 결과, 본 방법은 제한된 주기대역을 가지는 표면파 위상속도 자료만을 모델링 할 때 발생하는 심부 지층 물성정보에 대한 불확실성을 효과적으로 줄일 수 있음을 보여주었다. 또한 본 연구에서는 한 지점에서 획득된 지진파 기록으로부터 구해진 수선함수와, 일본 동경 중부지역에서 수행된 미소진동탐사로부터 획득된 두 개의 레일리파 위상속도 자료에 대해 제안된 기법을 적용하였다. 그 결과, 추정된 지하 구조는 선행된 탄성파 굴절법 탐사와 심부 시추공 자료와 잘 일치하는 양상을 보여주었다. 이러한 측면에서, 제안된 방법은 수신함수만을, 흑은 표면파 위상속도 자료만을 이용하는 개별역산에 비해 보다 정확하고 신뢰할 수 있는 모델을 제공하는 방법이 될 수 있을 것으로 판단된다.

• 한국해안해양공학회지
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• 제7권2호
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• pp.156-162
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• 1995

스커트의 유연성을 고려한 2차원 오일붐 모델에 대한 수치해법을 개발하였다. 본 수치모델에서는 부체를 강체로, 스커트를 장력이 걸려 있는 막으로, 스커트의 아래끝엔 집중질량이 놓여 있다고 가정하였다. 유동은 포텐셜이라고 가정하였으며 부체와 스커트의 연결부에서는 변위가 연속이라는 운동학적 조건을 그리고 스커트의 아래끝에는 집중질량에 대한 동력학적인 조건을 부가하였다. 수치해법은 선형포텐셜유동 이론에 근거한 Green 함수방법에 기초를 두고 있다. 스커트의 변형을 미리 알 수 없으므로 방사 포텐셜(radiation potential)과 부체의 변위 그러고 스커트의 변형을 동시에 구하는 방식을 택하였다. Green 정리를 적용하여 얻은 적분방정식과 부체의 운동방정식 그리고 스커트의 변형 관계식을 이산화하여 방사포텐셜과 부체의 변위 그리고 스커트의 변위에 대한 선형대수 방정식을 얻었다. 수치계산결과에 의하면 스커트의 유연성이 부체의 운동응답을 다소 줄일 수 있으며 부체의 공진체계를 바꿀 수 있음을 확인하였다. 그리고 오일붐의 운동응답특성에 영향을 주는 인자들 중에서 스커트의 길이와 집중질량을 파라미터로 하여 오일붐 모델의 운동응답특성을 비교해 보았다. 스커트가 유연한 경우와 스커트가 강체인 경우의 저주파수 극한해는 거의 일치하고 있어 수치해의 타당성을 간접적으로 확인할 수 있었다.