• Kyungpook Mathematical Journal
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• v.56 no.2
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• pp.529-539
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• 2016

In this paper, we obtain solution for the first order matrix dynamical system and also we provide set of necessary and sufficient conditions for complete controllability and complete observability of the Sylvester matrix dynamical system.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.4
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• pp.155-161
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• 2017

This paper suggests polynomial time solution algorithm for Sudoku puzzle problem. This problem has been known NP (non-deterministic polynomial time)-complete. The proposed algorithm set the initial value of blank cells to value range of [$1,2,{\cdots},9$]. Then the candidate set values in blank cells deleted by preassigned clue in row, column, and block. We apply the basic rules of Stuart, and proposes two additional rules. Finally we apply binary backtracking(BBT) technique. For the experimental Sudoku puzzle with various categories of solution, the BBT algorithm can be obtain all of given Sudoku puzzle regardless of any types of solution.

• Journal of Korean Society on Water Environment
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• v.24 no.1
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• pp.118-122
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• 2008

Degradations of phenol and chlorinated compounds mixtures were studied with ultrasound of 20 kHz and 0.57, 1.14 W/mL. In presence of carbon tetrachloride (CT), degradation rate of phenol is faster than chloroform (CF), dichloromethane (DCM) and phenol solution. It is due to that CT generates of free chlorine (HOCl and $OCl^-$) from the sonochemical degradation and plays a role of hydrogen atom scavenger. CF and DCM are react with free chlorine, so amount of free chlorine is smaller than CT solution. The degradation rates of chlorinated compounds decreased with co-presence of phenol in the solution due to the distribution ultrasonic energy to both compounds. The measured chloride ion was lower than the theoretical concentration assuming complete degradation. This means not all the contaminants destructed went through complete degradation.

• Journal of the Korea Society of Computer and Information
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• v.20 no.4
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• pp.111-117
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• 2015

The exam scheduling problem has been classified as nondeterministic polynomial time-complete (NP-complete) problem because of the polynomial time algorithm to obtain the exact solution has been unknown yet. Gu${\acute{e}}$ret et al. tries to obtain the solution using linear programming with $O(m^4)$ time complexity for this problem. On the other hand, this paper suggests chromatic number algorithm with O(m) time complexity. The proposed algorithm converts the original data to incompatibility matrix for modules and graph firstly. Then, this algorithm packs the minimum degree vertex (module) and not adjacent vertex to this vertex into the bin $B_i$ with color $C_i$ in order to exam within minimum time period and meet the incompatibility constraints. As a result of experiments, this algorithm reduces the $O(m^4)$ of linear programming to O(m) time complexity for exam scheduling problem, and gets the same solution with linear programming.

• The Journal of the Korean dental association
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• v.11 no.3
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• pp.199-203
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• 1973

Various concentration of formaldehyde solution (1%, 5%, 10%) were applied to cut pulp surface, for 3 minutes and the remaining pulp were carefully examined histo-pathologically. The result were as follows, 1. One week survival group which were treated by 1% formaldehyde solution showed seperation of odontoblast layer randomly and the weil's zone was undistinguishable. Deeper portion of this area was necrotic or coagulated. 2. Two week survival group which were treated 1% formaldehyde solution showed necrotic appearance spread from odontoblastic layer to weil's zone. 3. One and two week survival group which were treated 5% formaldehyde solution showed the odontoblastic layer was highly necrotic, under this zone empty net-work was seen. 4. One and two week survival group treated 10% formaldehyde solution showed complete destruction of pulp.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.27 no.4
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• pp.42-48
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• 2004

This paper concerns on a multiprocessor task scheduling problem with precedence relation, in which each task requires several processors simultaneously. Meta-heuristic generally finds a good solution if it starts from a good solution. In this paper, a tabu search is presented to find a schedule of minimal time to complete all tasks. A modified tabu search is also presented which uses a new initial solution based on the best solution during the previous run as the new starting solution for the next iteration. Numerical results show that a tabu search and a modified tabu search yield a better performance than the previous studies.

• Journal of applied mathematics & informatics
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• v.8 no.1
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• pp.181-197
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• 2001

A heuristic method TABU-CSP using Tabu Search (TS) is described for solving Constraint Satisfaction Problems (CSPs). The method is started with a complete but inconsistent solution of a binary CSP and obtained in prespecified number of iterations either a consistent solution or a near optimal solution with an acceptable number of conflicts. The repair in the solution at each iterative step is done by using two heuristics alternatively. The first heuristic is a min-conflicts heuristic that chooses a variable with the maximum number of conflicts and reassigns it the value which leads to the minimum number of conflicts. If the acceptable solution is not reached after the search continued for a certain number of iterations, the min-conflict heuristic is changed and the variable selected least number of times is chosen for repair. If an acceptable solution is not reached, the method switches back to the min-conflict heuristic and proceeds further. This allowed the method to explore a different region of search space space for the solution as well as to prevent cycling. The demonstration of the method is shown on a toy problem [9]which has no solution. The method is then tested on various randomly generated CSPs with different starting solutions. The performance of the proposed method in terms of the average number of consistency is checked and the average number of conflicts is conflicts is compared with that of the Branch and Bound(BB) method used to obtain the same solution. In almost all cases, the proposed method moves faster to the acceptable solution than BB.

• Korean Management Science Review
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• v.13 no.1
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• pp.1-12
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• 1996

This paper deals with production scheduling of block assembly shop in shipbuilding company. The Objectives of the schedule are leveling of daily total workload and fair assignment of workload to each department of the shop. Optimizing the objectives, we consider some restrictions which consisit of block due dates, workability of each department, and space restriction. We formulate the problem in mathematical form. But the model is too complex to find the optimal solution (the problem is NP-complete) and we use the genetic algorithm to find a good solution.

• Journal of the Korean Ceramic Society
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• v.30 no.9
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• pp.740-746
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• 1993

TiO2-SnO2 fine powders prepared by coprecipitation from TiCl4-SnCl4 aqueous solution, and their crystal structures were studied. All the TiO2-SnO2 fine powders calcined at 180~$700^{\circ}C$ showed the complete solid solution between TiO2(rutile structure) and SnO2(rutile structure). This crystal structure of TiO2-SnO2 powders is thought to be originated mainly from the heterogeneous nucleation of Ti-hydroxde on the Sn-hydroxide with coherent structure.

• Progress in Superconductivity and Cryogenics
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• v.4 no.1
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• pp.114-118
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• 2002

We introduce a design technique for homogeneous magnets using evolution strategy. The method has several advantages over existing techniques including: it allows complete flexibility in geometric constraints on the shape of both the coil and the homogeneous volume; it guarantees a globally optimal solution, and it automatically searches the minimum number of coils that satisfies given constraints.