• Korean Journal of Construction Engineering and Management
• /
• v.15 no.6
• /
• pp.26-34
• /
• 2014

Highway construction is a combination of linear, repetitive, and highly equipment intensive operations. Various types of construction equipment are deployed to ensure undisrupted performance of construction, and thus productivity improvement and cost-saving can be achieved through well-thought-out planning. The selection of construction equipment is dependent upon construction sequence, site conditions, and construction methods. In the process of planning, management should consider various types of construction methods per each type of construction operation. Also, management should map out proper construction equipment operation plan that takes the construction duration and cost measures into consideration. However, limited availability of historic data from the similar types of operations has been a stumbling block to proper construction planning, making the operations performed based upon experience and intuition guided by rules-of-thumb. As a consequence, the planing phase rarely provided an adequate validity in the implementation phase. The researchers developed a process logic for each construction type that management can utilize from early phase of highway construction planning process. Moreover, derived the construction equipment combination optimized for efficiency by using the process simulation technique. The developed method is expected to be useful for the decision-making process that aims to evaluate efficiency of various process plans and to ensure optimal selection of construction equipment for highway construction projects.

• Proceedings of the KIEE Conference
• /
• 2005.07a
• /
• pp.295-297
• /
• 2005

본 논문에서는 지금까지 각각 독립적으로 운전되었던 동북아시아(대한민국, 북한, 러시아) 전력시스템이 계통 연계를 통하여 얻을 수 있는 경제적 효과에 대한 평가 프로그램의 개발에 대하여 설명한다. 본 평가 프로그램의 목적는 향후 동북아 전력시스템의 계통 연계시 각 나라들의 발전소 건설 및 운용, 그리고 연계설비(Tie line)의 투자비용을 최소화할 수 있는 방안을 찾아 내는 것이다. 이를 통해 독립적으로 운전되는 것에 비해 계통연계를 통한 것이 보다 높은 경제적인 효과를 거둘 수 있음을 최종적으로 보이고자 한다. 문제를 좀 더 쉽고 빠르며 효과적으로 풀기 위하여 신규 발전설비와 연계선로에 대한 계획측면의 변수와 발전양와 선로에 흐르는 조류양의 제약 그리고 각 노드에서의 전력수급 조건 둥의 운전측면의 변수를 함께 포함시킨 선형 계획법 (LP, Linear Programming) 모델 로 정식화한 뒤 최적화 프로그램인 CPLEX를 통하여 해를 구한다.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2004.05b
• /
• pp.292-297
• /
• 2004

본 연구에서는 단일목적 저수지와 다목적 댐의 최적운영을 위하여 전역최적해를 탐색하는 SCE-UA법을 사용하는 비선형계획법을 적용한 최적화 모형을 구성하고 과거 운영자료를 사용하여 모형의 적용성을 검토하고 분석하였다. 또한, 다목적댐의 운영수위 상승으로 인하여 발생하는 추가용수를 댐하류로 추가적으로 공급함에 따른 댐운영상의 문제점과 해결책을 제시했다. 관개용 단일 목적 저수지의 유입량은 하천망 모형인 SSARR 모형을 이용하여 추정하였다. 관개용 단일 목적저수지의 용수배분을 최적화한 결과, 실측치와 최적방류량간의 상대오차가 $-2.6\~10.5\%$ 범위를 나타냈으며, 비교적 실측방류량과 유사한 형태로 용수를 공급하는 길과를 나타냈다. 다목적 저수지의 최적운영을 위해 발전량, 저수량 및 필요수량의 관계를 목적함수로하는 최적화 모형을 구성하여 섬진강댐의 최적운영에 적용하였다. 섬진강댐의 댐하류 방류량 증가에 따른 운영상의 문제점을 해결하기 위하여 댐하류 유지용수량을 0.17, 0.50, 0.70, 1.0, 1.5, $3.0m^3/sec$ 방류하는 경우로 구분하여 최적운영한 길과, 댐하류 유지용수량이 $1.0m^3/sec$ 이하인 경우에 발전량이 실적평균발전량에 근접한 결과를 나타냈으며, 용수공급량도 계획공급량인 377.4 백만 $m^3$ 보다 $28.9\~100.7$ 백만 $m^3$ 만큼 많은 양을 공급하는 결과를 나타냈다.

• Journal of Korean Society of Rural Planning
• /
• v.20 no.4
• /
• pp.221-232
• /
• 2014

초고령화된 한국 농촌에서 다양한 교육 및 직업 배경을 가진 중장년층 귀농인구의 유입은 고령화 문제에 대한 대안의 하나로 부각되고 있다. 본 연구는 농가 고령화에 대한 귀농인구의 잠재적인 기여도 측면에서 귀농인구의 지역별 유입 유출 패턴을 분석하였다. 분석에는 로그선형모형과 총합레퍼런스코딩을 사용하였고, 분석자료는 통계청의 2013년 귀농 통계이다. 분석결과에 의하면, 귀농인의 절반 정도가 수도권에서 비수도권 지역으로 이주한 인구이고, 이들을 제외하면 귀농인의 대부분은 원 거주지가 있던 도 내에서 이동하고 있다. 귀농인의 귀농 전 대비 귀농 후 지역 내 오즈비(odds ratio)는 지역별로 차이가 있으며, 귀농인의 성별과 연령에 따라서도 지역별 유입 유출패턴이 다르다. 이는 귀농인 유입의 긍정적 효과를 높이기 위해서는 지자체별 차이를 반영한 특화된 정책이 필요하다는 것을 의미한다.

• Journal of Korea Water Resources Association
• /
• v.43 no.2
• /
• pp.131-138
• /
• 2010

Due to the increased water demand and severe drought as an effect of the global warming, the effluent from wastewater treatment plants becomes considered as an alternative water source to supply agricultural, industrial, and public (gardening) water demand. The effluent from the wastewater treatment plant is a sustainable water source because of its good quality and stable amount of water discharge. In this study, the water reuse system was developed to minimize total construction cost to cope with the uncertain water demand in future using two-stage stochastic linear programming with binary variables. The pipes in the water reuse network were constructed in two stages of which in the first stage, the water demands of users are assumed to be known, while the water demands in the second stage have uncertainty in the predicted value. However, the water reuse system has to be designed now when the future water demands are not known precisely. Therefore, the construction of a pipe parallel with the existing one was allowed to meet the increased water demands in the second stage. As a result, the trade-off of construction costs between a pipe with large diameter and two pipes having small diameters was evaluated and the optimal solution was found. Three scenarios for the future water demand were selected and a hypothetical water reuse network considering the uncertainties was optimized. The results provide the information about the economies of scale in the water reuse network and the long range water supply plan.

• Journal of the Korean Society of Hazard Mitigation
• /
• v.11 no.2
• /
• pp.147-156
• /
• 2011

The purpose of multipurpose reservoir operation in flood season is to reduce the peak flood at a control point by utilizing flood control storage or to minimize flood damage by controlling release and release time. Therefore, the most important thing in reservoir operation for flood season is to determine the optimal release and release time. In this study, goal programming is used for the optimal reservoir operation in flood season. The goal programming minimizes a sum of deviation from the target value using linear programming or nonlinear programming to obtain the optimal alternative for the problem with more than two objectives. To analyze the applicability of goal programming, the historical storm data are utilized. The goal programming is applied to the reservoir system operation as well as single reservoir operation. Chungju reservoir is selected for single reservoir operation and Andong and Imha reservoirs are selected for reservoir system operation. The result of goal programming is compared with that of HEC-5. As a result, it was found that goal programming could maintain the reservoir level within flood control level at the end of a flood season and also maintain flood discharge within a design flood at a control point for each time step. The goal programming operation is different from the real operation in the sense that all inflows are assumed to be given in advance. However, flood at a control point can be reduced by calculating the optimal release and optimal release time using suitable constraints and flood forecasting system.

• The Journal of Korean Society for Radiation Therapy
• /
• v.30 no.1_2
• /
• pp.169-176
• /
• 2018

Purpose : The purpose of this study is to evaluate clinical applicability of Co-60 ViewRay treatment plan to increase the skin dose in case of high skin dose is required such as Malignant Fungating Wound By measuring the presence / absence of Bolus application and skin dose by the treatment device and comparing it Materials and Methods : Nine inner measuring points of 2.5 cm lattice arrangement and all 13 measuring points including upper and lower left and right measuring points touching the chest and skin were marked. After CT was taken, each treatment plan was formulated through Eclipse and ViewRay-TPS, and a Fixed beam-IMRT treatment plan was formulated so that the left chest V2Gy=95 % is delivered. Before measurement QED detector was calibrated and the QED detector was positioned at the 13 measurement points displayed on Phantom and surface dose of each treatment planner was measured using 5 mm Bolus application using True-beam and View-ray before and after, measure three times and compare each before applying 5 mm Bolus. Results : The surface dose of the Co-60 ViewRay and the linear accelerator appeared at $76.8%{\pm}5.2%$ vs. $67.3{\pm}%7.5%$ and the surface dose after application of 5 mm Bolus was $87.6%{\pm}8.9%$ vs. $80.3%{\pm}10.2%$ It was measured at 10.2 % (p<0.001). Conclusion : As a result of the surface dose measurement of each treatment instrument, Co-60 ViewRay confirmed that the surface dose reached 95.6 % of 6 MV Linac with conventional 5 mm bolus, despite not using Bolus (p<0.001). Also, by utilizing magnetic resonance images for each treatment, it is possible to observe the change in the treatment site without the problem of exposure, it is easy to formulate an adaptive treatment plan and it is easy to secure the skin dose, so the size In the case of Malignant Fungating Wound patients who need fast skin changes and need high skin doses, Co-60 ViewRay is considered to be more useful than linear accelerators.

• Journal of Korean Institute of Industrial Engineers
• /
• v.23 no.1
• /
• pp.39-54
• /
• 1997

This paper presents four process models for machining processes : 1) an economical mathematical model of machining process, 2) a prediction model for surface roughness, 3) a decision model for fuzzy cutting conditions, and 4) a judgment model of machinability with automatic selection of cutting conditions. Each model was developed the economic machining, and these models were applied to theories widely studied in industrial engineering which are nonlinear programming, computer simulation, fuzzy theory, and neural networks. The results of this paper emphasize the human oriented domain of a nonlinear programming problem. From a viewpoint of the decision maker, fuzzy nonlinear programming modeling seems to be apparently more flexible, more acceptable, and more reliable for uncertain, ill-defined, and vague problem situations.

• Journal of the Korean Society of Safety
• /
• v.12 no.1
• /
• pp.122-128
• /
• 1997

A new approach, called "two-phase approach", has been proposed In this study. Using this approach to solve MONLP(multiobjective nonlinear programming problem), the solution process is divied into two phase. In the first phase, the min-operator is used to aggregate the membership degree of fuzzy goals and constraints. In the second phase, the $\gamma$-operator is used to test and find an efficient solution in the sense of nondominated. It has been shown that no matter what the solution of the problem is unique or not, an efficient solution can be always obtained at the second phase. The proposed approach can be applied to industrial safety problem with multiobjective problems. On the basis of proposed approach, an illustrative numerical example is presented.presented.

• Korean Management Science Review
• /
• v.26 no.2
• /
• pp.19-35
• /
• 2009

This paper investigated performance of the Markowitz's portfolio selection model with applications to Korean stock market. We chose Samsung-Group-Funds and KOSPI index for performance comparison with the Markowitz's portfolio selection model. For the most recent one and a half year period between March 2007 and September 2008, KOSPI index almost remained the same with only 0.1% change, Samsung-Group-Funds showed 20.54% return, and Markowitz's model, which is composed of the same 17 Samsung group stocks, achieved 52% return. We performed sensitivity analysis on the duration of financial data and the frequency of portfolio change in order to maximize the return of portfolio. In conclusion, according to our empirical research results with Samsung-Group-Funds, investment by Markowitz's model, which periodically changes portfolio by using nonlinear programming with only financial data, outperformed investment by the fund managers who possess rich experiences on stock trading and actively change portfolio by the minute-by-minute market news and business information.