• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.5
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• pp.305-315
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• 2016

Due to the change from small volume production to small quantity batch production systems, individual companies have been attempting to produce a wide range of operating strategies, maximize their productivity, and minimize their WIP level by operating with the proper cycle time to defend their market share. In particular, using a complex workflow and process sequence in the manufacturing line has some drawbacks when it comes to designing the production strategy by applying analytical models, such as mathematical models and queueing theory. For this purpose, this paper uses three heuristic algorithms to solve the job release problem at the bottleneck workstation, product mix problem in multi-purpose machine(s), and batch size and sequence in batch machine(s). To verify the effectiveness of the proposed methods, a simulation analysis was performed. The experimental results demonstrated that the combined application of the proposed methods showed positive effects on the reduction of the cycle time and WIP level, and improvement of the throughput.

• Journal of the Korea institute for structural maintenance and inspection
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• v.20 no.4
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• pp.44-50
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• 2016

A study to apply phase change material(PCM) to rapid hardening cement paste forming semi-rigid pavement was carried out. The characteristics fresh and hardened paste were evaluated through the experiment for a total of 6 mixtures according to the cement type and the substitution of phase change material for acrylate. The fluidity by substituting phase change material for acrylate satisfied the target flow time of 10 to 13 seconds. In case of setting time, it was possible to secure the performance of rapid hardening cement by substituting phase change material, and if the substitution ratio over 60%, the initial set occurred 1 to 2 minutes faster than other mixtures. In case of compressive strength and bond strength, it showed similar strength characteristics with the plain mixture, and it satisfied both the target compressive and bonding strength of 36MPa and 2MPa. The mixture substituting phase change material showed higher resistance to chloride ion penetration than the mixture only using acrylate and the OPC level was insufficient. From the results of physical and mechanical performances of semi-rigid pavement cement paste, the phase change material substitution rate of 20% was effective in the range of this study.

• KIPS Transactions on Computer and Communication Systems
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• v.3 no.8
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• pp.261-270
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• 2014

As Internet traffic increases recently, much effort has been put on improving the performance of a web server. In addition to hardware side solutions such as replacement by high-end hardware or expansion of the number of servers, there are software side solutions to improve performance. Recent studies on these software side solutions have been actively performed. In this paper, we identify performance degradation problems occurring in a conventional TCP networking reception process and propose a way to solve them. We improve performance by combining three kinds of existing methods for Linux Networking Performance Improvement and two kinds of newly proposed methods in this paper. The three existing methods include 1) an allocation method of a packet flow to a core in a multi-core environment, 2) ITR(Interrupt Throttle Rate) method to control excessive interrupt requests, and 3) sk_buff data structure recycling. The two newly proposed methods are fd data structure recycling and epoll_event data structure recycling. Through experiments in a web server environment, we verify the effect of our two proposed methods and its combination with the three existing methods for performance improvement, respectively. We use three kinds of web servers: a simple web server, Lighttpd generally used in Linux, and Apache. In a simple web server environment, fd data structure recycling and epoll_event data structure recycling bring out performance improvement by about 7 % and 6%, respectively. If they are combined with the three existing methods, performance is improved by up to 40% in total. In a Lighttpd and an Apache web server environment, the combination of five methods brings out performance improvement by up to 36% and 20% in total, respectively.

• The KIPS Transactions:PartC
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• v.8C no.6
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• pp.793-805
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• 2001

In the recent priority system, high-priority packet will be served first and low-priority packet will be served when there isn\`t any high-priority packet in the system. By the way, even high-priority packet can be blocked by HOL (Head of Line) contention in the input queueing System. Therefore, the whole switching performance can be improved by serving low-priority packet even though high-priority packet is blocked. In this paper, we study the performance of preemptive priority in an input queueing switch for high speed switch system. The analysis of this switching system is taken into account of the influence of priority scheduling and the window scheme for head-of-line contention. We derive queue length distribution, delay and maximum throughput for the switching system based on these control schemes. Because of the service dependencies between inputs, an exact analysis of this switching system is intractable. Consequently, we provide an approximate analysis based on some independence assumption and the flow conservation rule. We use an equivalent queueing system to estimate the service capability seen by each input. In case of the preemptive priority policy without considering a window scheme, we extend the approximation technique used by Chen and Guerin [1] to obtain more accurate results. Moreover, we also propose newly a window scheme that is appropriate for the preemptive priority switching system in view of implementation and operation. It can improve the total system throughput and delay performance of low priority packets. We also analyze this window scheme using an equivalent queueing system and compare the performance results with that without the window scheme. Numerical results are compared with simulations.

• Journal of Soil and Groundwater Environment
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• v.11 no.5
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• pp.9-19
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• 2006

The accurate estimation of groundwater recharge is important for the proper management of groundwater systems. The widely used techniques of groundwater recharge estimation include water table fluctuation method, baseflow separation method, and annual water balance method. However, these methods can not represent the temporal-spatial variability of recharge resulting from climatic condition, land use, soil storage and hydrogeological heterogeneity because the methods are all based on the lumped concept and local scale problems. Therefore, the objective of this paper is to present an effective method for estimating groundwater recharge with spatial-temporal variability using the SWAT model which can represent the heterogeneity of the watershed. The SWAT model can simulate daily surface runoff, evapotranspiration, soil storage, recharge, and groundwater flow within the watershed. The model was applied to the Musimcheon watershed located in the upstream of Mihocheon watershed. Hydrological components were determined during the period from 2001 to 2004, and the validity of the results was tested by comparing the estimated runoff with the observed runoff at the outlet of the catchment. The results of temporal and spatial variations of groundwater recharge were presented here. This study suggests that variations in recharge can be significantly affected by subbasin slope as well as land use.

• Archives of Plastic Surgery
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• v.34 no.1
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• pp.1-7
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• 2007

Purpose: Human adipose tissue-derived stromal cells(hADSCs) can be expanded in vitro and induced to differentiate into multiple mesenchymal cell types. In this study we have examined various neuronal phenotypes and gene expression profiles of the hADSCs in the neuronal induction. Methods: The hADSCs were isolated from human adipose tissue and they were characterized by the flow cytometry analysis using CD13, CD29, CD34, CD45, CD49d, CD90, CD105 and HLA-DR cell surface markers. We differentiated the hADSCs into the neuronal lineage by using chemical induction medium and observed the cells with contrast microscopy. The immunocytochemistry and western blotting were performed using the NSE, NeuN, Trk-A, Vimentin, N-CAM, S-100 and ${\beta}$-Tubulin III antibodies. Results: The hADSCs were positive for CD13($90.3{\pm}4%$), CD29($98.9{\pm}0.7%$), CD49d($13.6{\pm}6%$), CD90 ($99.4{\pm}0.1%$), CD105($96%{\pm}2.8%$) but negative for CD34, CD45 and HLA-DR. The untreated cultures of hADSCs predominately consisted of spindle shaped cells and a few large, flat cells. Three hours after the addition of induction medium, the hADSCs had changed morphology and adopted neuronal-like phenotypes. The result of immunocytochemistry and western blotting showed that NSE, NeuN, Trk-A, Vimentin, N-CAM, S-100 and ${\beta}$-Tubulin III were expressed. However, NSE, NeuN, Vimentin were weakly expressed in the control. Conclusion: Theses results indicate that hADSCs have the capabillity of differentiating into neuronal lineage in a specialized culture medium. hADSCs may be useful in the treatment of a wide variety of neurological disorders.

• Journal of Chest Surgery
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• v.33 no.2
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• pp.117-124
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• 2000

Background: Nucleoside transport inhibitor(NTI) Keeps AMP, ADP, ATP levels high in myocytes by inhibiting adenosine cataboilsm so that it may preserve the myocardial contractability during ischemia In this study we investigated the effects of cyclic AMP phosphodiesterase inhibor(C-AMP PDSI) and S-P-nitrobenzyl-6 -thioniosine(NBT; a sort of NIT) on myocadial preservation and changes of constituent enzyme. Material and method: Twenty-six isolated rabbit hearts were perfused with Krebs-Henseleit buffer solution for 20 minutes arrested for 20 minutes and ten reperfused for 30 minutes. The following four groups were prepared and hemodynamic changes coronary effluent lactate dehydrogenase (LDH) a-hydroxybutylic accid(a-HBD) levels and myocardial LDH creatine kinase-MB (CK-MB) adenosine deaminase(ADA) a-HBD levels and myocardial LDH creatine kinase-MB (CK-MB) adenosine deaminase(ADA) a-HBD levels were analysed before and after cardiac arest ; Group I(control) ; the heart was only perfused with K-H ; Group II ; the heart was perfused with K-H including C-AMP PDSI(Amrinone 25mg/L); Group III ; the heart was perfused with K-H including NBT(4.19mg/L) ; Group IV ; the heart was perfused with K-H including C-AMP PDSI + NBT. Result : Left venticular developed pressure(LVDP) at 10 minutes of the equilibrium was significantly higher in group III(72.1$\pm$5.3 mmHg p<0.01) and group III(72$\pm$5.6 mmHg P<0.025) as compared with group I (40.8$\pm$4.7mmHg) and LVDP at 20 minutes of the reperfusion was significantly higher in group II(74$\pm$5.3mmHg p<0.01) and group III(72$\pm$5.6mmHg p<0.025) as compared with group I (44.2$\pm$4.6mmHg). Percentage recovery of LVDP at the reperfusion was the highest in group II(123.3%) Percentage recovery of coronary flow at the equilibrium reperfusion were higher in group II(310%, 270%) group III(230%, 290%) group IV(310%, 280%) as compared with group I (100%) respectively. Myocadial LDH level was significant lower in group IV(33495$\pm$1802 IU/gm p<0.04) as compared with group I(48767$\pm$1421 IU/gm) Myocadial CK-MB level was significant higher in group II(74820$\pm$1421 IU/gm) compared with group I (45450$\pm$1737 IU/gm) Myocadial ADA level was significant higher group IV(1215$\pm$8 IU/gm p<0.05) compared with group I(125$\pm$15 IU/gm) but there was no significant difference between group I and group II ,III, IV in changes of coronary effluent LDH, a-HBD levels. Conclusion: C-AMP PDSI solely appears to have a better effect on myocardial preservation after ischemia than NBT but with no synergistic effect and it could keep CK-MB leve high in myocardial tissues.

• Journal of Korean Society of Transportation
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• v.31 no.5
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• pp.60-70
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• 2013

This study aims to develop a truck priority on left-turn algorithm that can reduce greenhouse gas emissions by reducing heavy duty truck's stops at signalized intersection. The signal priority is granted for a left-turn phase, because heavy duty trucks can deteriorate left-turn traffic flow due to the low acceleration or deceleration rate and large turn radius. Truck priority allows to provide the stable speed control for heavy duty truck, and reduces emissions at the signal intersection. Also, two signal recovery strategies are compared for various traffic conditions. This study analyzes the effectiveness of truck priority such as greenhouse gas emissions and fuel consumption reduction, and total travel time saving using the PARAMICS and Comprehensive Modal Emissions Model (CMEM). The results show that signal priority for heavy duty trucks has an effect on reducing greenhouse gas emissions and fuel consumptions at non-peak hour. Also, it shows decreasing total travel time due to reducing truck stops.

• Horticultural Science & Technology
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• v.31 no.5
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• pp.544-551
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• 2013

The effect of different silicon (Si) sources and methods of application on the growth of two chrysanthemum cultivars grown in a soilless substrate was investigated. Rooted terminal cuttings of Dendranthema grandiflorum 'Lemmon Eye' and 'Pink Eye' were transplanted into pots containing a coir-based substrate. A nutrient solution containing 0 or $50mg{\cdot}L^{-1}$ Si from calcium silicate ($CaSiO_3$), potassium silicate ($K_2SiO_3$) or sodium silicate ($Na_2SiO_3$) was supplied once a day through an ebb-and-flood sub irrigation system. A foliar spray of 0 or $50mg{\cdot}L^{-1}$ Si was applied twice a week. Cultivar and application method had a significant effect on plant height. Cultivar, application method, and Si source had a significant effect on plant width. Of the three Si sources studied, $K_2SiO_3$ was found to be the best for the increasing number of flowers, followed by $CaSiO_3$ and $Na_2SiO_3$. In both the cultivars, sub irrigational supply of Si developed necrotic lesions in the older leaves at the beginning of the flowering stage as compared to the control and foliar spray of Si. Cultivar, application method, Si source, and their interactions had significant influence on leaf tissue concentrations of calcium (Ca), potassium (K), phosphorus (P), magnesium (Mg), sulfur (S), sodium (Na), boron (B), iron (Fe), and zinc (Zn). The addition of Si to the nutrient solution decreased leaf tissue concentrations of Ca, Mg, S, Na, B, Cu, Fe, and Mn in both cultivars. The greatest Si concentration in leaf tissue was found in 'Lemmon Eye' ($1420{\mu}g{\cdot}g^{-1}$) and 'Pink Eye' ($1683{\mu}g{\cdot}g^{-1}$) when $K_2SiO_3$ was applied through a sub irrigation system and by foliar spray, respectively.

• Korean Journal of Ecology and Environment
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• v.40 no.3
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• pp.370-378
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• 2007

The objective of this research was to diagnose integrative ecological health in Bansuk Stream, one of the tributaries of Gap Stream, using the fish assemblage during July 2006${\sim}$April 2006. For this research, we selected six sampling sites and applied some approaches such as the Index of Biological Integrity (IBI), Qualitative Habitat Evaluation Index (QHEI), and necropsy-based Health Assessment Index (HAI). The stream health condition, based on the IBI values, averaged 24 (n= 18, range: $10{\sim}46$), indicating "poor${\sim}$fair" condition according to the criteria of US EPA (1993). Physical habitat condition, based on the QHEI, averaged 116 (n=6, range: $77{\sim}139$), indicating "fair${\sim}$good" condition. Values of IBI were more correlated with 3 metrics of instream cover ($M_1$, r=0.553, p=0.017, n=18), flow/velocity ($M_3$, r=0.627, p=0.005, n=18), and riffes/bends ($M_7$, r=0.631, p=0.005, n=18) than other metrics. Value of HAI in the control was zero (i.e., excellent condition), while the values in the T1 and T2 treatments were 5 (range: 0${\sim}$30) and 50 (range: 40${\sim}$80), respectively. The maximum values of IBI (46) were coincided with zero of HAI. Thus, these approaches seem to be a good tool for a diagnosis and evaluations of stream ecosystem health.