• Structural Engineering and Mechanics
• /
• 제49권1호
• /
• pp.65-80
• /
• 2014

This paper reports on the development of a minimum cost design model and its application for obtaining economic designs for reinforced High Strength Concrete (HSC) T-sections in bending under ultimate limit state conditions. Cost objective functions, behavior constraint including material nonlinearities of steel and HSC, conditions on strain compatibility in steel and concrete and geometric design variable constraints are derived and implemented within the Conjugate Gradient optimization algorithm. Particular attention is paid to problem formulation, solution behavior and economic considerations. A typical example problem is considered to illustrate the applicability of the minimum cost design model and solution methodology. Results are confronted to design solutions derived from conventional design office methods to evaluate the performance of the cost model and its sensitivity to a wide range of unit cost ratios of construction materials and various classes of HSC described in Eurocode2. It is shown, among others that optimal solutions achieved using the present approach can lead to substantial savings in the amount of construction materials to be used. In addition, the proposed approach is practically simple, reliable and computationally effective compared to standard design procedures used in current engineering practice.

• KIEAE Journal
• /
• 제16권3호
• /
• pp.129-135
• /
• 2016

Purpose: Building figuration is imperative to perceive the its value, environmental clean status and form. Therefore, maintenance activities of the building exterior are required to keep the housing condition and value. Each household should pay the repair cost which is brought out in the future. For this repair cost, the estimation model would needed to forecast and provide the required cost. This study aimed at providing the estimation model of the repair cost, using the repair survey data between the 2011 and 2014 in Seoul. Method: For these, it took various estimation function of repair cost such as 1st function, inverse function and so on. These above functions would be applied into the building exterior and outdoor facilities which figure the building shape and characteristics. Result: Results of this study are shown ; First, among 11 estimation models, the power function has a better statistics and goodness-of-fit than any other models. Second, the estimation model with a variable of household has a pattern in upward to the right. On the contrary, the model with management area is little downward to the right. Both of them are depended on the estimated parameter of the power function and the parameter smaller than 1.

• 간호행정학회지
• /
• 제13권2호
• /
• pp.199-207
• /
• 2007

Purpose: Clinical characteristics and medical cost were analyzed according to the surgical procedures for intertrochanteric fracture in aged patients to assess the appropriateness of treatment expense and to find possibility of reducing the medical cost. Method: Variable for the statistical analysis were; the clinical characteristics, medical cost according to the surgical procedures, the treatment success rate, the total medical expense, and the average expense per case. SAS Package Version 8.02. was used to analyze the relevant data. Results: Operative procedures differ significantly according to the gender and by the location of institution. Only significant clinical variables according to the operative procedure were duration of general anesthesia and amount of blood transfusion. Average cost per treatment was the highest in the bipolar hemiarthroplasty followed by the gamma nail and hip compressing screw. Average cost for bipolar hemiarthroplasty was significantly higher than other surgical procedures. Conclusions: The difference in hospital costs for treatment of intertrochanteric fracture originates from the utilized surgical procedures, mostly by the materials used. The method of surgical treatment should be carefully determined by the purpose of the surgery, in order to improve the quality of medical care and also to reduce the hospital cost.

• Design & Manufacturing
• /
• 제2권6호
• /
• pp.23-27
• /
• 2008

It is well known that the family-mold has an advantage to reduce the cost for production and mold. However, defects are frequently occurred by over packing the smaller volume cavity during molding, especially when the family-mold has a volumetric difference between two cavities. In this study, the cavity-filling imbalance was confirmed by the temperature and the pressure sensors, and a variable-runner system was developed for balancing the cavity-filling. Experiments of balancing the cavity filling was carried out in the family-mold with the variable-runner system, and balancing the cavity-filling was confirmed by changing the cross-sectional area of a runner in the variable-runner system with the temperature and pressure sensors. The influence of the injection speed to the balancing-capability of the variable-runner system was also examined in the experiment.

• 전기전자학회논문지
• /
• 제20권4호
• /
• pp.385-391
• /
• 2016

We demonstrated experimentally a variable optical frequency comb source using a cascaded dual parallel Mach Zehnder modulator (DPMZM) and a phase modulator (PM). With this simple configuration and applying low drive voltages, we generated variable comb source composed of spectral lines 3, 5, 7, 9 and 11 with 10-GHz frequency spacing, also generated 2 and 3 spectral lines with 20 GHz frequency spacing. The generated comb source maintains high spectral coherence across the entire bandwidth with good spectral flatness (within 1-dB for 2, 3, 5, 7 comb lines, within 2-dB for 9-comb lines and within 3-dB for 11 comb lines). The flat and variable comb source is mainly achieved by manipulating 6 operating parameters of DPMZM, setting RF amplifier gain, connected at phase modulator and phase shifters. Hence the method is simple and offers great flexibility in achieving flat and variable comb spectrum, which is experimentally demonstrated. This brings advantages of power efficiency due to low driving voltages, simplicity and cost effectiveness to the system.

• 소성∙가공
• /
• 제17권2호
• /
• pp.130-134
• /
• 2008

Resource and energy saving is a very important practice for the future as well as for today. Weight saving of structural parts, which are formed by extrusion, plays a key role in manufacturing field. The cross-sections of extruded parts with industrial aluminum are constant in the axial direction by conventional extrusion method. Especially, these aluminum parts used and manufactured in the car industry need other processes to vary the cross-section in the axial direction. However, applications of these parts are often limited by high cost. If the cross-section of the parts is variable by only extrusion with newly developed method, the application of extruded aluminum parts will actually increase. Therefore, a new CNC extruder that can control the section area of a car part was invented for the first time in the nation. Using the extrusion machine, the experiment was performed to validate its workability during the variable section extrusion process. Also, numerical analysis was carried out to investigate the flow mode with different speeds of main ram and various pocket shapes of a die-set in the variable section extrusion process.

• 한국태양에너지학회 논문집
• /
• 제33권5호
• /
• pp.41-50
• /
• 2013

Economic feasibility study using weighted average variable Jeju System Marginal Price, SMP, was conducted for Gasiri wind farm of Jeju Island. To predict the variable Jeju SMP, generator share ratio for SMP was calculated from the real time wind power production and the power demand data for years. Also, sensitivity analysis on Net Present Value, NPV, and Benefit/Cost Ratio, B/C ratio, were performed to clarify which factors are more important in assessing economic feasibility. The result shows that the Gasiri wind farm has a minimum of 110 billion won and a maximum of 132 billion won difference between fixed and variable SMP. Also, Capacity Factor, C.F., had the highest sensitivity for NPV, followed by SMP. Accordingly, when economic analysis for a potential wind farm site is carried out, the variable SMP as well as C.F. should be considered for more accurate assessment of the wind farm.

• 한국콘텐츠학회논문지
• /
• 제16권5호
• /
• pp.113-123
• /
• 2016

본 연구는 간호사를 대상으로 원가인식, 원가태도가 원가관리행동에 미치는 영향을 파악함으로써 이를 통한 간호사의 원가관리 역량 개발을 위한 근거자료를 마련하고자 한 것이다. 자료수집은 1년 이상 병원 근무 경력을 가진 간호사 150명을 대상으로 하였다. 자료분석은 통계분석 프로그램을 이용하여 기술통계, 상관관계분석, 다중회귀분석을 이용하였다. 연구 결과 간호사의 원가인식, 원가태도 및 원가관리행동 간에는 모두 유의한 양의 상관관계가 있는 것으로 나타났다. 또한 원가인식과 원가태도 중 간호사의 원가관리 행동에 영향을 미치는 요인은 원가태도인 것으로 파악되었다. 이에 본 연구의 결과가 간호사의 원가관리 행동 향상 프로그램 개발의 근거 자료로 활용될 수 있을 것으로 기대하며, 개발된 교육 프로그램의 타당성과 효과성을 분석하는 중재 연구 또한 필요함을 제안한다.

• 대한토목학회논문집
• /
• 제39권6호
• /
• pp.853-858
• /
• 2019

철도 네트워크를 효율적으로 사용하는 방법 중 하나는 연결선 건설을 통해 여러 노선이 하나의 선로를 공유하는 방법인데, 국내에서도 이미 사용하고 있거나 사업화 추진 중인 노선이 존재한다. 본 연구는 철도 연결선 건설시 사업화 단계가 아닌 계획 단계에서 연결선 건설의 위치 선정, 우선순위 산정 등에 필요한 연결선 설계 모형을 구축하고 이에 대한 해법을 제시하였다. 모형은 연결선건설비용, 노선운영비용, 이용자 총통행비용을 최소화하기 위한 비선형 최적화문제로 구축하였고, 결정변수로는 연결선 건설여부 및 방향, 노선의 열차 운행 빈도로 설정하였다. 본 연구에서는 문제 풀이 알고리즘과 경로선택 알고리즘을 각각 제시하였고, 예제네트워크에 적용을 통하여 모형의 실용성을 검증하였다. 향후 현실을 반영한 실제네트워크와 파라미터를 설정하여 연구의 결과를 발전시킬 여지가 있다.

• 대한교통학회지
• /
• 제25권5호
• /
• pp.183-193
• /
• 2007

전통적으로 혼잡통행료는 교통시설의 한계사회비용과 한계개인비용의 차이를 혼잡통행료로 부과함으로써 사용자 균형(user equilibrium)상태의 도로망을 체계최적(system optimum)으로 유도하는 한계비용가격(marginal cost pricing) 또는 최적혼잡통행료(first-optimal pricing)이론에 근거를 두고 있다. 이러한 이론을 기초로 본 연구에서는 가변수요를 갖는 다계층 도로이용자를 대상으로 링크 최적혼잡통행료의 이론적 특성을 살펴보고 혼잡통행료 징수에 따른 계층간 그리고 지역간 형평성을 분석하기 위한 방법론을 연구한다. 여기서, 도로이용자가 경험하는 경로통행비용은 시간요소(통행시간)와 화폐요소(혼잡통행료)의 2가지 판단기준으로 구성되고 시간가치에 의해 하나의 단위로 전환(trade off)이 가능하다. 경로 통행비용이 시간단위로 환산될 경우, 최적혼잡통행료는 시간단위 체계최적 조건으로부터 도출될 수 있고 경로통행비용이 화폐단위로 환산될 경우, 최적혼잡통행료는 화폐단위 체계최적 조건으로부터 도출될 수 있다. 따라서 본 연구에서는 이러한 체계최적 조건으로부터 도출된 최적혼잡통행료를 산정하는 모형을 개발하고 이를 통하여 계층간 형평성을 살펴본다.