• Journal of Chest Surgery
• /
• 제18권3호
• /
• pp.461-465
• /
• 1985

Rupture of the aorta following blunt trauma of the thorax may occur more frequently than has generally been recognized. Actual complete transection of the aorta usually results in immediate death but varying degrees of lesser disruption permit increased chance of survival. Chronic traumatic aneurysms are so designated following a period of 3 months from the traumatic incident. The exact time required for the acute process and hematoma to convert into an aneurysm is unknown. Because a thoracic surgeon encounters so few of these aneurysms, it is difficult for him to arrive at sound dicta of management from his personal experience. It is not surprising that controversy exists concerning the therapeutic approach to the aneurysm which is asymptomatic and is discovered months or years after the causative injury. In the hope of improving the surgical treatment of patients with this condition, we reported one case with chronic traumatic aneurysm of the descending thoracic aorta.

• 대한안전경영과학회:학술대회논문집
• /
• 대한안전경영과학회 2001년도 춘계학술대회
• /
• pp.189-193
• /
• 2001

This paper analyses the tool switching problem in the dynamic environment, where parts to be processed on a flexible machine arrive randomly. As the total number of tools required to Process a set of parts on the machine is generally larger than the available magazine storage capacity, tool switches between parts are usually necessary. We assume that tool switching must be made just before the processing of the parts. Since the time required for tool switches can be significant relative to processing time and cause the processing of parts to be delayed, it is desirable to minimize the number of tool switches. Therefore, we present one heuristic algorithm to minimize the total number of tool switches and the t)reposed heuristic is compared with the KTNS (Keep Tool Needed Soonest) policy on randomly generated problems.

• 대한산업공학회지
• /
• 제12권1호
• /
• pp.19-30
• /
• 1986

This paper provides an evaluation of static flowshop scheduling heuristics for minimizing makespan as an objective function in the dynamic flowshop model, in which new jobs with stochastic processing times arrive at the shop randomly over time and are added into the waiting jobs for processing. A total of sixteen scheduling heuristics, including several revisions and combinations of previously reported me-sixteen scheduling heuristics, including several revisions and combinations of previously reported methods, are surmmarized. These scheduling rules are evaluated via computer using a SLAM discrete event simulation model. The results for the simulation are analyzed using both statistical and nonstatistical methods. The results from the study suggest which of the popular scheduling rules hold promise for application to practical dynamic flowshop problems.

• 대한산업공학회지
• /
• 제26권1호
• /
• pp.27-35
• /
• 2000

For a weighting method to be practically valid, it should produce weights which coincide with the relative importance of attributes perceived by the decision maker. In this paper, 'bootstrapping' is used to compare the practical validities of five weighting methods frequently used; the rank order centroid method, the rank reciprocal method, the rank sum method, the entropic method, and the geometric mean method. Bootstrapping refers to the procedure where the analysts allow the decision maker to make careful judgements on a series of similar cases, then infer statistically what weights he was implicitly using to arrive at the particular ranking. The weights produced by bootstrapping can therefore be regarded as well reflecting the decision maker's perceived relative importances. Bootstrapping and the five weighting methods were applied to a job selection problem. The results showed that both the rank order centroid method and the rank reciprocal method had higher level of practical validity than the other three methods, though a large difference could not be found either in the resulting weights or in the corresponding solutions.

• 대한산업공학회지
• /
• 제32권4호
• /
• pp.373-381
• /
• 2006

This paper considers a scheduling problem for a hybrid flowshop with dynamic order arrival. A hybrid flowshop is an extended form of a flowshop, which has serial stages like a flowshop but there can be more than one machine at each stage. In this paper, we propose a new method for the problem of scheduling with the objective of minimizing mean tardiness of orders which arrive at the shop dynamically. The proposed method is based on the list scheduling approach, however we use a more sophisticated method to prioritize lots unlike dispatching rule-based methods. To evaluate the performance of the proposed method, a simulation model of a hybrid flowshop-type production system is constructed. We implement well-known dispatching rules and the proposed methods in the simulation model. From a series of simulation tests, we show that the proposed methods perform better than other methods.

• Industrial Engineering and Management Systems
• /
• 제15권2호
• /
• pp.131-142
• /
• 2016

We consider a multi-server queueing system without buffer and with two types of customers as a model of operation of a mobile network cell. Customers arrive at the system in the marked Markovian arrival flow. The service times of customers are exponentially distributed with parameters depending on the type of customer. A part of the available servers is reserved exclusively for service of first type customers. Customers who do not receive service upon arrival, can make repeated attempts. The system operation is influenced by random factors, leading to a change of the system parameters, including the total number of servers and the number of reserved servers. The behavior of the system is described by the multi-dimensional Markov chain. The generator of this Markov chain is constructed and the ergodicity condition is derived. Formulas for computation of the main performance measures of the system based on the stationary distribution of the Markov chain are derived. Numerical examples are presented.

• 대한수학회보
• /
• 제50권2호
• /
• pp.611-626
• /
• 2013

In the paper we study the finite-time ruin probability in a general risk model with constant interest force, in which the claim sizes are pairwise quasi-asymptotically independent and arrive according to an arbitrary counting process, and the premium process is a general stochastic process. For the case that the claim-size distribution belongs to the consistent variation class, we obtain an asymptotic formula for the finite-time ruin probability, which holds uniformly for all time horizons varying in a relevant infinite interval. The obtained result also includes an asymptotic formula for the infinite-time ruin probability.

• 대한수학회보
• /
• 제57권5호
• /
• pp.1269-1297
• /
• 2020

In this paper, we consider a two-species parabolic-parabolic-elliptic chemotaxis system with weak competition and a fractional diffusion of order s ∈ (0, 2). It is proved that for s > 2p₀, where p₀ is a nonnegative constant depending on the system's parameters, there admits a global classical solution. Apart from this, under the circumstance of small chemotactic strengths, we arrive at the global asymptotic stability of the coexistence steady state.

• 한국정보처리학회논문지
• /
• 제7권6호
• /
• pp.1949-1955
• /
• 2000

This paper proposes a multistage interconnection ATM switching network without internal blocking. The first is recirculating shuffle-exchange network improved on hardware complexity. The next is connected to Rank network with tree structure. In this network, after the packets transferred to the same output ports are given each priority, only a packet with highest priority is sent to the next, an the others are recirculated to the first. Rearrangeability through decomposition and composition algorithm is applied for the transferred packets in hanyan network and all they arrive at a final destinations. To analyze throughput, waiting time and packet loss ratio according tothe size of buffer, the probabilities are modeled by a binomial distribution of packet arrival.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2009년도 제40회 하계학술대회
• /
• pp.1638_1639
• /
• 2009

This paper propose a mobile robot for the obstacle avoidance control. The proposed method based on self-organization method is a way to escape of obstacle. Optimal path planning and obstacle avoidance, depending on its final goal will arrive at exactly the mobile robot. Simulation results show the validity of the proposed method.