• Journal of Communications and Networks
• /
• 제16권1호
• /
• pp.81-91
• /
• 2014

This paper proposes hidden-node aware grouping (HAG) algorithm to enhance the performance of institute of electrical and electronics engineers (IEEE) 802.15.4 networks when they undergo either severe collisions or frequent interferences by hidden nodes. According to the degree of measured collisions and interferences, HAG algorithm dynamically transforms IEEE 802.15.4 protocol between a contention algorithm and a contention-limited one. As a way to reduce the degree of contentions, it organizes nodes into some number of groups and assigns each group an exclusive per-group time slot during which only its member nodes compete to grab the channel. To eliminate harmful disruptions by hidden nodes, especially, it identifies hidden nodes by analyzing the received signal powers that each node reports and then places them into distinct groups. For load balancing, finally it flexibly adapts each per-group time according to the periodic average collision rate of each group. This paper also extends a conventional Markov chain model of IEEE 802.15.4 by including the deferment technique and a traffic source to more accurately evaluate the throughput of HAG algorithm under both saturated and unsaturated environments. This mathematical model and corresponding simulations predict with 6%discrepancy that HAG algorithm can improve the performance of the legacy IEEE 802.15.4 protocol, for example, even by 95% in a network that contains two hidden nodes, resulting in creation of three groups.

• Macromolecular Research
• /
• 제12권2호
• /
• pp.178-188
• /
• 2004

We performed molecular dynamics (MD) simulations at 300 K on a series of poly(benzyl ether) (PBE) dendrimers having a different core functionalities. We used the rotational isomeric state Metropolis Monte Carlo (RMMC) method to construct the initial configuration in a periodic boundary cell (PBC) before the MD simulations were undertaken. To elucidate the effects that the structural features have on the chain dimension, the overall internal structure, and the morphology, we monitored the radii of gyration, R$\sub$g/ and the conformational changes during the simulations. The PBE dendrimers in a glassy state adopted less-extended structures when compared with the conformations obtained from the RMMC calculations. We found that R$\sub$g/ of the PBE dendrimer depends on the molecular weight, M, according to the relation, R$\sub$g/∼M$\^$0.22/. The radial distributions of the dendrimers were developed identically in the PBC, irrespective of the core functionality. A gradual decrease in radial density resulted from the fact that the terminal branch ends are distributed all over the molecule, except for the core region.

• 한국임상수의학회지
• /
• 제33권1호
• /
• pp.70-73
• /
• 2016

Necrotizing meningoencephalitis (NME) is a unique idiopathic nonsuppurative inflammatory disease of central nervous system in small-sized breed dogs. A 9-year-old intact male Shih-Tzu dog with anorexia, vomiting, salivation and intermittent seizures was submitted to the Jeju National University for diagnosis. Grossly, there were no obvious lesions in the brain, except dilatation of most blood vessels in meninges. Histopathologically, brain revealed severe multifocal nonsuppurative inflammation in perivascular area of meninges and cerebral cortex. Some areas of cerebral parenchyma were replaced with lots of macrophages contained periodic acid-Schiff positive materials. Many new-formed blood vessels were observed around the necrotic regions using Gomori reticulum stain. Immunohistochemistry and reverse transcription-polymerase chain reaction were negative for toxoplasmosis and canine distemper virus. Based on the gross, histopathologic features and antigen detection methods, this case was diagnosed as NME. Here we reported the NME in relatively uncommon breed, Shih-Tzu dog, than other small breed dogs.

• 제어로봇시스템학회논문지
• /
• 제18권9호
• /
• pp.854-862
• /
• 2012

The optimal design of batch-storage network by using periodic square wave model provides analytical lot sizing equations for a complex supply chain network characterized as multi-supplier, multi-product, multi-stage, non-serial, multi-customer, cyclic system including recycling and/or remanufacturing. The network structure includes multiple currency flows as well as material flows. The processes are represented by multiple feedstock/product materials with fixed composition which are very suitable for production processes. In this study, transportation processes that carry multiple materials with unknown composition are added and the time frame is changed from single period into multiple periods in order to represent nonperiodic parameter variations. The objective function of the optimization involves minimizing the opportunity costs of annualized capital investments and currency/material inventories minus the benefit to stockholders in the numeraire currency. The expressions for the Kuhn-Tucker conditions of the optimization problem are reduced to a multiperiod subproblem for average flow rates and analytical lot-sizing equations. The multiperiod lot sizing equations are different from single period ones. The effects of corporate income taxes, interest rates and exchange rates are incorporated.

• 산업경영시스템학회지
• /
• 제46권4호
• /
• pp.93-100
• /
• 2023

In this paper, an alternative inventory policy that trades off the bullwhip effect at an upstream facility with cost minimization at a current facility, with the goal of reducing system wide total expected inventory costs, when external demand distributjon is autocorrelated, is considered. The alternative inventory policy has a form that is somewhere between one that completely neglects the autocorrleation and one that actively utilizes the autocorrelation. For this purpose, a mathematical model that allows us to evaluate system wide total expected inventory costs for a periodic review system is developed. This model enables us to identify an optimal inventory policy at a current facility that minimizes system wide total expected inventory costs by the best tradeoff of the bullwhip effect at an upstream facility with cost minimization at a current facility. From numerical experiments, it has been found that (i) when the autocorrelation is negative, the optimal policy is one that actively utilizes the autocorrelation, (ii) when the autocorrelation is small and positive, the optimal policy is one that neglects the autocorrelation, and (iii) when the autocorrelation is large and positive, the optimal policy is somewhere between one that actively utilizes the autocorrelation and one that neglect the autocorrelation.

• 제어로봇시스템학회논문지
• /
• 제7권10호
• /
• pp.867-873
• /
• 2001

The purpose of this study is to find analytic solution of determining the optimal capacity (lot-size) of multiproduct acyclic multistage production and inventory system to meet the finished product demand under the constraint of finite intermediate storage. Intermediate storage is a practical way to mitigate the material flow imbalance through the line of supply and demand chain. However, the cost of constructing and operating storage facilities is becoming substantial because of increasing land value, environmental and safety concern. Therefore, reasonable decision-making about the capacity of processes and storage units is an important subject for industries. The industrial solution for this subject is to use the classical economic lot sizing method, EOQ/EPQ(Economic Order Quantity/Economic Production Quantity) model, incorporated with practical experience. But EOQ/EPQ model is not suitable for the chemical plant design with highly interlinked processes and storage units because it is developed based on single product and single stage. This study overcomes the limitation of the classical lot sizing method. The superstructure of the plant consists of the network of serially and/or parallelly interlinked non-continuous processes and storage units. The processes transform a set of feedstock materials into another set of products with constant conversion factors. A novel production and inventory analysis method, PSW(Periodic Square Wave) model, is applied to describe the detail material flows among equipments. The objective function of this study is minimizing the total cost composed of setup and inventory holding cost. The advantage of PSW model comes from the fact that the model provides a set of simple analytic solutions in spite of realistic description of the material flows between processes and storage units. the resulting simple analytic solution can greatly enhance the proper and quick investment decision for the preliminary plant design problem confronted with economic situation.

• 대한한방내과학회지
• /
• 제38권6호
• /
• pp.891-901
• /
• 2017

Objectives: The aim of the study was to evaluate the anti-asthmatic effect of alismatis rhizoma and alisol acetate B combination therapy in a murine asthma model. Methods: C57BL/6 mice were sensitized to and challenged with a mixture of ragweed, dust mite, and aspergillus to induce an asthma animal model. Alismatis rhizoma extract and alisol acetate B combination therapy was co-administered only in the experimental group. To evaluate the anti-asthmatic effect of the combination therapy, inflammatory cell counts in bronchoalveolar lavage (BAL) fluid were determined, and tissue was examined histologically with hematoxylin and eosin (H & E) and periodic acid-Schiff (PAS) stains, by enzyme-linked immunosorbent assay (ELISA) of IgE, IL-4, and IL-5, and with reverse transcription polymerase chain reaction (RT-PCR) of IL-5, IL-33, MUC5AC. Results: Alismatis rhizoma and alisol acetate B combination therapy reduced the number of inflammatory cells, alleviated histologic features, and down-regulated all the investigated asthma mediators, IgE, IL-4, IL-5, IL-33, and MUC5AC. Conclusions: According to the above results, alismatis rhizoma and alisol acetate B combination therapy may have therapeutic potential for asthma.

• 대한한방내과학회지
• /
• 제34권4호
• /
• pp.412-427
• /
• 2013

Objectives : This study was carried out to compare the effects of Eejin-tang, Hyangsaeejin-tang and Naeso-san extracts on indomethacin-induced gastric mucosal lesions in mice. Methods : Experimental mice were divided into six groups. The normal group had no gastro-inflammation. In the control group, gastro-inflammation was elicited by indomethacin. Misoprostol, Eejin-tang, Hyangsaeejin-tang and Naeso-san group were those in which misoprostol, Eejin-tang extract, Hyangsaeejin-tang extract and Naeso-san extract were administered after gastro-inflammation is elicited. This study examined the anti-inflammation effects and distribution of mucus secreting cells, zonula occludin-1 (ZO-1), heat shock protein (HSP) 70, periodic acid-schiff reaction stain (PAS), peanut agglutinin (PNA), cyclooxygenase-1 (COX-1), 5-bromo-2'-deoxyuridine (BrdU), nuclear factor kappa-light-chain-enhancer of activated B cells (NF-${\kappa}B$) p65, inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). Results : 1. The hemorrhagic erosion and damaged mucus secreting cell, the positive reaction HSP70 increased in the control group, but decreased in the Eejin-tang, Hyangsaeejin-tang and Naeso-san groups. 2. The positive reaction of ZO-1, PAS, PNA, COX-1 and BrdU decreased in the control group, but increased in the Eejin-tang, Hyangsaeejin-tang and Naeso-san groups. 3. The positive reaction of NF-${\kappa}B$ p65, iNOS and COX-2 increased in the control group, but decreased in the Eejin-tang, Hyangsaeejin-tang and Naeso-san groups. Conclusions : Among the three extracts, the effects were in the order of Naeso-san, Hyangsaeejin-tang and Eejin-tang group, Naeso-san being the most effective.

• Archives of Plastic Surgery
• /
• 제39권6호
• /
• pp.593-599
• /
• 2012

Background This study aimed to investigate the possibility of isolating mesenchymal stem cells (MSCs) from human thigh adipose tissue and the ability of human thigh adipose stem cells (HTASCs) to differentiate into hepatocytes. Methods The adipose-derived stem cells (ADSCs) were isolated from thigh adipose tissue. Growth factors, cytokines, and hormones were added to the collagen coated dishes to induce the undifferentiated HTASCs to differentiate into hepatocyte-like cells. To confirm the experimental results, the expression of hepatocyte-specific markers on undifferentiated and differentiated HTASCs was analyzed using reverse transcription polymerase chain reaction and immunocytochemical staining. Differentiation efficiency was evaluated using functional tests such as periodic acid schiff (PAS) staining and detection of the albumin secretion level using enzyme-linked immunosorbent assay (ELISA). Results The majority of the undifferentiated HTASCs were changed into a more polygonal shape showing tight interactions between the cells. The differentiated HTASCs up-regulated mRNA of hepatocyte markers. Immunocytochemical analysis showed that they were intensely stained with anti-albumin antibody compared with undifferentiated HTASCs. PAS staining showed that HTASCs submitted to the hepatocyte differentiation protocol were able to more specifically store glycogen than undifferentiated HTASCs, displaying a purple color in the cytoplasm of the differentiated HTASCs. ELISA analyses showed that differentiated HTASCs could secrete albumin, which is one of the hepatocyte markers. Conclusions MSCs were islolated from human thigh adipose tissue differentiate to heapatocytes. The source of ADSCs is not only abundant abdominal adipose tissue, but also thigh adipose tissue for cell therapy in liver regeneration and tissue regeneration.

• 한국가금학회지
• /
• 제38권1호
• /
• pp.45-50
• /
• 2011

본 증례는 국내의 산란계 농장에서 사육 중이던 39일령 산란계 중추계군에서 신경 증상을 동반한 폐사를 나타내며, 부검 시 폐를 포함한 뇌, 간, 신장 등의 실질장기에서 직경 1~5 mm 크기의 황백색 결절이 다수 관찰되었다. 병리조직학적으로 다발성의 육아종성 병변이 폐, 뇌, 신장, 비장 등에서 관찰되었으며, 특히 폐의 결절 형성 및 건락성 육아종성 병변이 심한 정도로 나타나 호흡기를 통해 1차 감염이 이루어진 것을 확인할 수 있었다. 육아종성 결절을 SDA에 배양하여 집락의 색을 확인하고, 균사체의 Giemsa 염색 및 조직학적 병변상에서 PAS 염색 결과를 통해 Aspergillus 속 곰팡이인 것으로 확인할 수 있었고, 배양된 균사에 대한 유전학적 검사 결과 Aspergillus flavus로 동정되었다. A. flavus 균사는 폐, 뇌, 신장 및 선위에서 병변 중심부 및 변연부 모두에서 관찰되었고, 다핵 거대세포 및 섬유아세포가 염증세포들과 함께 둘러싸고 있는 것이 확인되었다. 특히 대뇌에서의 육아종성 병변 및 그로 인한 신경 증상이 임상 증상으로 발현된 것이 본 증례의 특징적인 소견이다.