환경친화적인 무기/유기 Core-Shell의 제조에 관한 연구

설수덕,임재길,임종민,권재범,이내우 한국안전학회 2004 한국안전학회지 Vol.19 No.1

Composite particles using inorganic and organic chemicals were synthesized and the results of those reaction were compared to variation of temperature and agitation speed in presence of CaCO₃ which was adsorbed SDBS. Also the synthesises were optimized according to conversion rate of composite particles. In inorganic/organic core-shell composite particle polymerization, CaCO₃ adsorbed by 0.5wt% surfactant SDBS was prepared initially and then core CaCO₃ was encapsulated by sequential emulsion polymerization using MMA at the addition of APS 3.16X 10^(-3)mo1/L to minimize the coagulated PMMA particle itself during MMA shell polymerization. Encapsulated PMMA on CaCO₃ as inorganic/organic core-shell particles was verified by Fr-IR and DSC analysis. It was found that the CaCO₃ was very well encapsulated by PMMA as shell. The surfaces were distinctly found as spindle shape and broad particle distribution after capsulation.

유화중합을 이용한 4원공중합 바인더의 제조와 특성

임종민,하선희,임재길,설수덕 東亞大學校 大學院 2004 大學院論文集 Vol.29 No.-

Styrene-Acrylonitrile-Ethylacrylate-N-Methyloacryamide Prepared by emulsion polymerization has broad applications for additives such as paint binder, adhesive for wood and paper due to its low glass transition temperature which help to plasticize substrate resins. Since emulsion polymerization has disadvantage that surfactant and ionic initiator degrade properties of the product polymer, Poly(St-EA-AN-NMA) was synthesized using ammonium persulfate(APS) as catalyst and sodium lauryl sulfate(SLS) as emulsion to prevent the degradation. The copolymer binder product was internally plasticized and has enhanced colloid stability, adhesion, tensile strength and elongation. During binder emulsion polymerization, no coagulation and complete conversion occur with the reactant mixture of 3.34wt%/monomer ammonium persulfate, 2.33wt%/monomer sodium lauryl sulfate, and the balanced monomer that the weight ratio of Styrene, Ethylacrylate, Acrylonitrile are 47wt%/monomer, 32wt%/monomer, 6.4wt%/monomer. The activation energies for 37, 42, 47, 52% Styrene content were checked as 28.1~36kcal/mol by Kissinger's method. Actually, reasonable solid content could be considered as 56% because of activation energy and adhesive characteristics.

SOME ANALYSES ON A PROPOSED METHOD OF THE OPTIMAL NETWORK SELECTION PROBLEM

Lim, Jong Seul The Korean Society for Computational and Applied M 2014 Journal of applied mathematics & informatics Vol.32 No.3

This paper introduces the approximation and a proposed method to deal the optimum location network selection problem such that the total cost is minimized. For the proposed method, we derived a feasible solution and the variance. To compare the performances of the approximation and the proposed method, computer simulation is also implemented. The result showed the solutions being optimum with 74% for the proposed method and 57% for the approximation. When the solutions is not optimum, maximum and average deviations are below 4% and 2% respectively. The results indicate a slightly better performance of the proposed method in a certain case.

A PROCESSOR SHARING MODEL FOR COMMUNICATION SYSTEMS

Lim, Jong Seul,Park, Chul Guen,Ahn, Seong Joon,Lee, Seoyoung 한국전산응용수학회 2004 Journal of applied mathematics & informatics Vol.15 No.1

we model communication and computer systems that process interactive and several and several types of background jobs. The scheduling policy in use is to share the processor among all interactive jobs and, at most, one background job of each type at a time according to the process sharing discipline. Background jobs of each type are served on a first-come-first-served basis. Such scheduling policy is called Processor Sharing with Background jobs (PSBJ). In fact, the PSBJ policy is commonly used on many communication and computer systems that allow interactive usage of the systems and process certain jobs in a background mode. In this paper, the stability conditions for the PSBJ policy are given and proved. Since an exact analysis of the policy seems to be very difficult, an approximate analytic model is proposed to obtain the average job sojourn times. The model requires the solution of a set of nonlinear equations, for which an iterative algorithm is given and its convergence is proved. Our results reveal that the model provides excellent estimates of average sojourn times for both interactive and background jobs with a few percent of errors in most of the cases considered.

DECOMPOSITION APPROXIMATION FOR OPEN QUEUEING NETWORKS

Lim, Jong-Seul 한국전산응용수학회 2001 The Korean journal of computational & applied math Vol.8 No.3

We present two decomposition approximations for the mean sojourn times in open single class queing networks. If there is a single bottleneck station, the approximations are asymptotically exact in both light and heavy traffic. When applied to a Jackson network or an M/G/1 queue, these approximations are exact for all values of the traffic intensity. AMS Mathematics Subject Classification : 68M20

AN INTERPOLATION APPROXIMATION VIA SIMULATION ON A QUEUEING NETWORK

Lim, Jong-Seul 한국전산응용수학회 2002 The Korean journal of computational & applied math Vol.9 No.2

In this paper we consider open queueing system with a Poisson arrival process which have a finite upper bound on the arrival rate for which the system is stable. Interpolation approximations for quantities of interest, such as moments of the sojourn time distribution, have previously been developed for such systems, utilizing exact light and heavy traffic limits. These limits cannot always be easily computed for complex systems. Thus we consider an interpolation approximation where all of the relevant information is estimated via simulation. We show that all the relevant information can in fact be simultaneously estimated in a single regenerative simulation at any arrival rate. In addition to light and heavy traffic limits, both the quantity of interest and its derivative (with respect to the arrival rate) are estimated at the arrival rate of the simulation. All of the estimates are then combined, using a least squares procedure, to provide an interpolation approximation.

THE INFLUENCE OF THE TIME SLICING OF A PROCESSOR SHARING COMMUNICATION MODEL

LIM, JONG SEUL,PARK, CHIN HONG,AHN, SEONG JOON 한국전산응용수학회 2005 Journal of applied mathematics & informatics Vol.17 No.1

Average memory occupancy and congestion in computer system or communication system may be reduced further if new jobs are admitted only when the number of jobs queued at CPU is below a certain threshold, run queue cutoff (RQ). In our previous paper we showed that response time of a job is invariant with respect to RQ if jobs do not communicate each other. In this paper, we prove that the invariance property by considering the evolution of the queue lengths as point processes. We also present an approximate method for the delay due to context switching under time slicing.

M/G/1 QUEUE WITH COMPLEX VACATION POLICIES

Lim, Jong-Seul,Oh, Choon-Suk 한국전산응용수학회 1999 Journal of applied mathematics & informatics Vol.6 No.3

Models of single-server queues with vacation have been widely used to study the performance of many computer communica-tion and production system. In this paper we use the formula for a wide class of vacation policies and multiple types of vacations based on the M/G/1 queue with generalized vacations and exhaustive service. furthermore we derive the waiting times for many complex vacation policies which would otherwise be to analyze. These new results are also applicable to other related queueing models. if they conform with the basic model considered in this paper.

GENERAL FORMULAS OF SOME VACATION MODELS

Lim, Jong-Seul Korean Society of Computational and Applied Mathem 2008 Journal of applied mathematics & informatics Vol.26 No.1

This paper describes a single-server queue where the server is unavailable during some intervals of time, which is referred to as vacations. The major contribution of this work is to derive general formulas for the additional delay in the vacation models of the single vacations, head of line priority queues with non-preemptive service, and multiple vacations and idle time.

A processor sharing model for communication system

Jong Seul Lim,박철근,안성준,Seoyoung Lee 한국전산응용수학회 2004 Journal of applied mathematics & informatics Vol.15 No.-

we model communication and computer systems that processinteractive and several and several types of background jobs. The schedulingpolicy in use is to share the processor among all interactive jobs and, atmost, one background job of each type at a time according to the processsharing discipline. Background jobs of each type are served on a first-come-first-served basis. Such scheduling policy is called Processor Sharing withBackground jobs (PSBJ). In fact, the PSBJ policy is commonly used onmany communication and computer systems that allow interactive usage ofthe systems and process certain jobs in a background mode. In this paper,the stability conditions for the PSBJ policy are given and proved. Sincean exact analysis of the policy seems to be very difficult, an approximateanalytic model is proposed to obtain the average job sojourn times. Themodel requires the solution of a set of nonlinear equations, for which aniterative algorithm is given and its convergence is proved. Our results revealthat the model provides excellent estimates of average sojourn timesfor both interactive and background jobs with a few percent of errors inmost of the cases considered.