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Kiseok Sung,Hesham Rakha 한국경영과학회 2009 Management Science and Financial Engineering Vol.15 No.1
A network model and a Genetic Algorithm (GA) is proposed to solve the simultaneous estimation of the trip distribution and traffic assignment from traffic counts in the congested networks in a logitbased Stochastic User Equilibrium (SUE). The model is formulated as a problem of minimizing a non-linear objective function with the linear constraints. In the model, the flow-conservation constraints are utilized to restrict the solution space and to force the link flows become consistent to the traffic counts. The objective of the model is to minimize the discrepancies between two sets of link flows. One is the set of link flows satisfying the constraints of flow-conservation, trip production from origin, trip attraction to destination and traffic counts at observed links. The other is the set of link flows those are estimated through the trip distribution and traffic assignment using the path flow estimator in the logit-based SUE. In the proposed GA, a chromosome is defined as a real vector representing a set of Origin-Destination Matrix (ODM), link flows and route-choice dispersion coefficient. Each chromosome is evaluated by the corresponding discrepancies. The population of the chromosome is evolved by the concurrent simplex crossover and random mutation. To maintain the feasibility of solutions, a bounded vector shipment technique is used during the crossover and mutation.
고정비용과 비선형 단위운송비용을 가지는 수송문제를 위한 이단유전알고리즘에 관한 연구
성기석(Kiseok Sung) 한국경영과학회 2016 韓國經營科學會誌 Vol.41 No.4
This paper proposes a Bi-level Genetic Algorithm for the Fixed Charge Transportation Problem with Non-linear Unit Cost. The problem has the property of mixed integer program with non-linear objective function and linear constraints. The bi-level procedure consists of the upper-GA and the lower-GA. While the upper-GA optimize the connectivity between each supply and demand pair, the lower-GA optimize the amount of transportation between the pairs set to be connected by the upper-GA. In the upper-GA, the feasibility of the connectivity are verified, and if a connectivity is not feasible, it is modified so as to be feasible. In the lower-GA, a simple method is used to obtain a pivot feasible solution under the restriction of the connectivity determined by the upper-GA. The obtained pivot feasible solution is utilized to generate the initial generation of chromosomes. The computational experiment is performed on the selected problems with several non-linear objective functions. The performance of the proposed procedure is analyzed with the result of experiment
Metastable Ge<sub>1–<i>x</i></sub>C<sub><i>x</i></sub> Alloy Nanowires
Kim, Byung-Sung,Lee, Jae-Hyun,Son, Kiseok,Hwang, Sung Woo,Choi, Byoung Lyong,Lee, Eun Kyung,Kim, Jong Min,Whang, Dongmok AmericanChemical Society 2012 ACS APPLIED MATERIALS & INTERFACES Vol.4 No.2
<P>Carbon-containing alloy materials such as Ge<SUB>1–<I>x</I></SUB>C<SUB><I>x</I></SUB> are attractive candidatesfor replacing silicon (Si) in the semiconductor industry. The additionof carbon to diamond lattice not only allows control over the latticedimensions, but also enhances the electrical properties by enablingvariations in strain and compositions. However, extremely low carbonsolubility in bulk germanium (Ge) and thermodynamically unfavorableGe–C bond have hampered the production of crystalline Ge<SUB>1–<I>x</I></SUB>C<SUB><I>x</I></SUB> alloymaterials in an equilibrium growth system. Here we successfully synthesizedhigh-quality Ge<SUB>1–<I>x</I></SUB>C<SUB><I>x</I></SUB> alloy nanowires (NWs) by a nonequilibrium vapor–liquid–solid(VLS) method. The carbon incorporation was controlled by NW growthconditions and the position of carbon atoms in the Ge matrix (at substitutionalor interstitial sites) was determined by the carbon concentration.Furthermore, the shrinking of lattice spacing caused by substitutionalcarbon offered the promising possibility of band gap engineering forphotovoltaic and optoelectronic applications.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/aamick/2012/aamick.2012.4.issue-2/am201446u/production/images/medium/am-2011-01446u_0006.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/am201446u'>ACS Electronic Supporting Info</A></P>
성기석 한국경영과학회 1999 한국경영과학회지 Vol.24 No.2
A genetic algorithm to determine the optimal signal sequence and double cycle pattern is described The signal sequence and double cycle pattern are used as the input for TRANSYT to find optimal signal timing at each junction in the area traffic networks in the genetic process, the partially matched crossover and simple crossover operators are used for evolution of signal sequence and double cycle pattern respectively A special conversion algorithm is devised to convert the signal sequence into the link-stage assignment for TRANSYT Results from tests using data from an area traffic network in Leicester region R are given
성기석,박지혁 한국경영과학회 1997 한국경영과학회 학술대회논문집 Vol.- No.2
For parallel processing, the compiler partitions a loaded program into a set of tasks and makes a schedule for the tasks that will minimize parallel processing time for the loaded program. Building an optimal schedule for a given set of partitioned tasks of a program has known to be NP-complete. In this paper we introduce a GA(Genetic Algorithm)-based scheduling method in which a choromosome consists of two parts of a string which decide the number and order of tasks on each processor. An additional computation is used for feasibility constraint in the chromosome. By granularity theory, a partitioned program is categorized into coarse-grain or fine-grain types. There exist good heuristic algorithms for coarse-grain type partitioning. We suggested another GA adaptive to the coarse-grain type partitioning. The infeasibility of chromosome is overcome by the encoding and operators. The number of processors are decided while the GA find the minimum parallel processing time.
프로세서의 수가 한정되어있는 병렬계산모델에서 유전알고리즘을 이용한 스케쥴링해법
성기석,박지혁 한국경영과학회 1998 韓國經營科學會誌 Vol.23 No.2
In the parallel processing systems, a compiler partitions a loaded program into tasks, allocates the tasks on multiple processors and schedules the tasks on each allocated processor. In this paper we suggest a Genetic Algorithm(GA) based scheduling method to find an optimal allocation and sequence of tasks on each processor. The suggested method uses a chromosome which consists of task sequence and binary string that represent the number and order of tasks on each processor respectively. Two correction algorithms are used to maintain precedency constraints of the tasks in the chromosome. This scheduling method determines the optimal number of processors within limited numbers, and then finds the optimal schedule for each processor. A result from computational experiment of the suggested method is given.
분지한계기법을 이용한 무환네트워크에서 최대물동량경로의 해법에 관한 연구
성기석,임준묵 한국경영과학회 1995 韓國經營科學會誌 Vol.20 No.3
The Maximum Origin-Destination Flow Path Problem (MODFP) in an Acyclic Network has known as NP-hard. K. S. Sung has suggested an Optimal Algorithm for MODFP based on the 'Pseudo flow of arc' and the K-th shortest path algorithm. When we try to solve MODFP problem by general Branch and Bound Method (BBM), the upper and lower bounds of subproblems are so weak that the BBM become very inefficient. Here we utilized the 'Pseudo flow of arc' for the tight bounds of subproblems so that it can produce an efficient BBM for MODFP problem.
Ahn, Sang Bong,Jang, Kiseok,Jun, Dae Won,Lee, Byung Hoon,Shin, Kye Jung Plenum Pub. Corp.] 2014 Digestive diseases and sciences Vol.59 No.12
<P>Liver X receptor (LXR) is an oxysterol-activated nuclear receptor involved in the control of major metabolic pathways for cholesterol homeostasis and lipogenesis. Although the role of LXR in hepatic steatosis is well known, its correlation with intrahepatic inflammation and fibrosis has not been thoroughly studied. We investigated the association between LXRα, hepatic inflammation, and fibrosis, as well as its correlation with other intrahepatic lipid transporters in patients with nonalcoholic fatty liver disease (NAFLD).</P>