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PSO 최적화 기법을 이용한 Ethylene Oxide Plant 배치에 관한 연구
박평재 ( Pyung Jae Park ),이창준 ( Chang Jun Lee ) 한국안전학회(구 한국산업안전학회) 2015 한국안전학회지 Vol.30 No.3
In the fields of plant layout optimization, the main goal is to minimize the construction cost including pipelines as satisfying all constraints such as safety and operating issues. However, what is the lacking of considerations in previous researches is to consider proper safety and maintenance spaces for a complex plant. Based on the mathematical programming, MILP(Mixed Integer Linear Programming) problems including various constraints can be formulated to find the optimal solution which is to achieve the best economic benefits. The objective function of this problem is the sum of piping cost, pumping cost and area cost. In general, many conventional optimization solvers are used to find a MILP problem. However, it is really hard to solve this problem due to complex inequality and equality constraints, since it is impossible to use the derivatives of objective functions and constraints. To resolve this problem, the PSO (Particle Swarm Optimization), which is one of the representative sampling approaches and does not need to use derivatives of equations, is employed to find the optimal solution considering various complex constraints in this study. The EO (Ethylene Oxide) plant is tested to verify the efficacy of the proposed method.
PSO 최적화 기법을 이용한 다층 구조의 플랜트 배치에 관한 연구
박평재 ( Pyung Jae Park ),이창준 ( Chang Jun Lee ) 한국화학공학회 2014 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.52 No.4
In the fields of researches associated with plant layout optimization, the main goal is to minimize the costs of pipelines for connecting equipment. However, what is the lacking of considerations in previous researches is to handle the multi floor processes considering the safety distances for domino impacts on a complex plant. The mathematical programming formulation can be transformed into MILP (Mixed Integer Linear Programming) problems as considering safety distances, maintenance spaces, and economic benefits for solving the multi-floor plant layout problem. The objective function of this problem is to minimize piping costs connecting facilities in the process. However, it is really hard to solve this problem due to complex unequality or equality constraints such as sufficient spaces for the maintenance and passages, meaning that there are many conditional statements in the objective function. Thus, it is impossible to solve this problem with conventional optimization solvers using the derivatives of objective function. In this study, the PSO (Particle Swarm Optimization) technique, which is one of the representative sampling approaches, is employed to find the optimal solution considering various constraints. The EO (Ethylene Oxide) plant is illustrated to verify the efficacy of the proposed method.
김종만,박평재,홍근,주동진,김관우,류제호,한영석,조재영,송기원,김봉완,김동식,김성훈,최상태,유영경,서경석,나양원,강구정,조재원 대한이식학회 2021 Korean Journal of Transplantation Vol.35 No.3
Background: Once-daily tacrolimus reduces non-compliance relative to twice-daily tacrolimus. However, little is known about the safety and efficacy of conversion from twice-daily tacrolimus to generic once-daily tacrolimus in liver transplantation (LT). Herein, we investigated the efficacy and safety of a switch from twice-daily tacrolimus to generic once-daily tacrolimus in patients with stable liver graft function. Methods: This prospective, multicenter, open-label, single-arm study was conducted in 17 medical centers for 1 year from July 2019 to July 2020 (NCT04069065). Primary end- point was the incidence of biopsy-proven acute rejection (BPAR) for 24 weeks after con- version. Secondary endpoints were graft failure, patient death, and adverse events (AEs). Results: Of 151 screened LT patients, 144 patients were enrolled. BPAR, graft failure, and patient death did not occur in this patient population. There were no statistical dif- ferences in blood tests, liver function tests, or biochemical tests between visits in any of the patients. Median tacrolimus trough level decreased abruptly from 4.7 ng/mL to 3.2 ng/mL after generic once-daily tacrolimus conversion, but median tacrolimus dose in- creased due to low tacrolimus trough level. Ninety-two adverse events occurred in 54 pa- tients. Liver enzyme levels increased in seven patients (4.9%) after the switch to generic once-daily tacrolimus, but the liver function tests of these patients normalized thereafter. There were three cases of severe AEs not related to investigational drug. Conclusions: Present study suggests that conversion from twice-daily tacrolimus to ge- neric once-daily tacrolimus is effective and safe in stable LT patients.