• Journal of Information Processing Systems
• /
• v.6 no.3
• /
• pp.413-434
• /
• 2010

Wireless sensor networks are usually characterized by dense deployment of energy constrained nodes. Due to the usage of a large number of sensor nodes in uncontrolled hostile or harsh environments, node failure is a common event in these systems. Another common reason for node failure is the exhaustion of their energy resources and node inactivation. Such failures can have adverse effects on the quality of the real-time services in Wireless Sensor Networks (WSNs). To avoid such degradations, it is necessary that the failures be recovered in a proper manner to sustain network operation. In this paper we present a dynamic Energy efficient Real-Time Job Allocation (ERTJA) algorithm for handling node failures in a cluster of sensor nodes with the consideration of communication energy and time overheads besides the nodes' characteristics. ERTJA relies on the computation power of cluster members for handling a node failure. It also tries to minimize the energy consumption of the cluster by minimum activation of the sleeping nodes. The resulting system can then guarantee the Quality of Service (QoS) of the cluster application. Further, when the number of sleeping nodes is limited, the proposed algorithm uses the idle times of the active nodes to engage a graceful QoS degradation in the cluster. Simulation results show significant performance improvements of ERTJA in terms of the energy conservation and the probability of meeting deadlines compared with the other studied algorithms.

• Korean Journal of Veterinary Service
• /
• v.42 no.3
• /
• pp.127-133
• /
• 2019

The purpose of this study was to investigate the contamination level of representative mycotoxins that have adverse effects on livestock by using LC-MS/MS method and to utilize the results as basic data for the establishment of quality control system for feed, and to provide information on production and storage. A total of nine mycotoxins, including aflatoxin $B_1$, aflatoxin $B_2$, aflatoxin $G_1$, aflatoxin $G_2$, ochratoxin A, fumonisin $B_1$, fumonisin $B_2$, deoxynivalenol (DON), zearalenone (ZEN) were simultaneously analyzed in LC-MS/MS under ESI positive mode. Fumonisin $B_1$ and fumonisin $B_2$ were detected from 3 cases of 75 forage produced in Incheon area, the detection rate was 4.0%. The detection concentration was 0.01~0.02 mg/kg, which was lower than the domestic recommended limit. Fumonisins were detected in a slightly different manner from the results of mycotoxin studies reported in Korea, which is attributed to the high temperature and dry summer weather of the year. The result of LC-MS/MS method performance of 9 mycotoxins, the recovery of DON was quite low as $41.53{\pm}3.91%$ that is not suitable for simultaneous analysis. This is probably due to that the extract solution used in this study was not suitable for the extraction of DON, along with the characteristics of a very dry forage. For the study of mycotoxins in Incheon area forage for the first time, further investigation is needed for the safe supply of livestock products.

• Korean Journal of Veterinary Service
• /
• v.43 no.4
• /
• pp.261-265
• /
• 2020

Each commercial cyromazine insecticide has different HPLC conditions. The aim of this study was to establish a standardized chromatographic method for the determination of cyromazine in commercial insecticides. The separation was achieved on two C18 columns - Waters® Bondapak C (4×300 nm i.d., 10 ㎛) and X bridge (4.6×250 nm i.d., 5 ㎛) using a mobile phase composed of water/methanol/ethanolamine (76:24:0.1, v/v), with UV detection at wavelengths 230 nm and 254 nm. A total of six commercial cyromazine insecticides were analyzed. In this study, the optimal high-performance liquid chromatography conditions for the analysis of cyromazine were as follows: a mobile phase of water/methanol/ethanolamine (76:24:0.1, v/v) at a flow rate of 1.0 mL/min and a detection wavelength of 230 nm using a X bridge C18 column (4.6×250 nm i.d., 5 ㎛) at a column temperature of 25℃. The calibration curve was linear in the concentration range of 5~50 ㎍/mL, with a correlation coefficient of 0.99995. The cyromazine detection limit was 0.2 ㎍/mL, and the limit of quantification was 0.59 ㎍/mL. The percentage recovery ranged from 99.8% to 101.0% for cyromazine, and the relative standard deviation was not over 2.0%. The cyromazine concentration ranged from 92.7% to 109.4% and was within the acceptable range (90~120%) for the percent of the labeled amount. This method was found to be suitable for determining cyromazine in commercial insecticides.

• Journal of Korean Physical Therapy Science
• /
• v.30 no.4
• /
• pp.29-43
• /
• 2023

Background: In the rehabilitation of stroke patients, regular physical activity is very important not only as a treatment for maximal functional recovery but also as a strategy to prevent the recurrence of stroke. The purpose of this study was to objectively measure the amount of physical activity in people with stroke, and to examine the differences in motor and cognitive function according to a level of physical activity. Design: A cross-sectional study. Methods: Physical activity (GENEActiv), motor function (Fugl-Meyer Assessment), cognitive function (Montreal Cognitive Assessment-Korean version), and the Korean version of Modified Barthel Index were evaluated in adult stroke patients with hemiplegia. Results: There was no statistically significant difference in the level of physical activity according to the motor and cognitive function. There was no statistically significant difference in motor and cognitive function according to the level of physical activity, but there was a statistically significant difference in the MBI (p<.01). Conclusion: As a result of the difference in the MBI according to the level of physical activity, it was found that the more moderate to vigorous physical activities are performed, the higher the independence in daily living. These results can be interpreted as that the more often you participate in physical activities such as physical therapy (gait training), the better your independence in ADL. Since regular physical activity participation of adult stroke patients can improve daily living performance, it is considered necessary to participate in physical activities such as continuous physical therapy.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2008.11a
• /
• pp.1387-1390
• /
• 2008

In a wireless network, handover latency is very important in supporting user mobility with the required quality of service (QoS). In view of this many schemes have been developed which aim to reduce the handover latency. The Hierarchical Mobile IPv6 (HMIPv6) approach is one such scheme which reduces the high handover latency that arises when mobile nodes perform frequent handover in Mobile IPv6 wireless networks. Although HMIPv6 reduces handoff latency, failures in the mobility anchor point (MAP) results in severe disruption or total disconnection that can seriously affect user satisfaction in ongoing sessions between the mobile and its correspondent nodes. HMIPv6 can avoid this situation by using more than one mobility anchor point for each link. In [3], an improved Robust Hierarchical Mobile IPv6 (RH-MIPv6) scheme is presented which enhances the HMIPv6 method by providing a fault-tolerant mobile service using two different MAPs (Primary and Secondary). It has been shown that the RH-MIPv6 scheme can achieve approximately 60% faster recovery times compared with the standard HMIPv6 approach. However, if mobile nodes perform frequent handover in RH-MIPv6, these changes incur a high communication overhead which is configured by two local binding update units (LBUs) as to two MAPs. To reduce this communication overhead, a new cost-reduced binding update scheme is proposed here, which reduces the communication overhead compared to previous schemes, by using an increased number of MAP switches. Using this new proposed method, it is shown that there is a 19.6% performance improvement in terms of the total handover latency.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.8 no.1
• /
• pp.137-149
• /
• 2004

A new software paradigm is required on the development of network and various service requirements. With this, many studies on a mobile agent have been made. For the execution of the mobile agent, migration is the most important factor that influences the performance of the mobile agent. In this paper we propose the method that leads to high migration efficiency in order to improve the performance. The features of our migration technique are as follows. First, the migration technique creates the dynamic itinerary that appropriately copes with the network conditions and the platform changes to improve the agent execution efficiency. Second, it perfecters an executed code to reduce the amount of the mobile data and reduces the execution time by instantiating the agent in advance. Third, it improves the execution efficiency by using the checkpoint-based recovery method that does not execute the agent again and recovers the process states even though the errors take place. Though the simulation we compare the proposed method with the existing methods. The simulation result shows that the proposed method outperform the existing methods in terms of migration.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.19 no.1
• /
• pp.94-131
• /
• 2007

A review on the papers published in the Korean Journal of Air-Conditioning and Refrigerating Engineering in 2004 and 2005 has been done. Focus has been put on current status of research in the aspect of heating, cooling, air-conditioning, ventilation, sanitation and building environment. The conclusions are as follows. (1) Most of fundamental studies on fluid flow were related with heat transportation of facilities. Drop formation and rivulet flow on solid surfaces were interesting topics related with condensation augmentation. Research on micro environment considering flow, heat, humidity was also interesting for comfortable living environment. It can be extended considering biological aspects. Development of fans and blowers of high performance and low noise were continuing topics. Well developed CFD and flow visualization(PIV, PTV and LDV methods) technologies were widely applied for developing facilities and their systems. (2) The research trends of the previous two yews are surveyed as groups of natural convection, forced convection, electronic cooling, heat transfer enhancement, frosting and defrosting, thermal properties, etc. New research topics introduced include natural convection heat transfer enhancement using nanofluid, supercritical cooling performance or oil miscibility of $CO_2$, enthalpy heat exchanger for heat recovery, heat transfer enhancement in a plate heat exchanger using fluid resonance. (3) The literature for the last two years($2004{\sim}2005$) is reviewed in the areas of heat pump, ice and water storage, cycle analysis and reused energy including geothermal, solar and unused energy). The research on cycle analysis and experiments for $CO_2$ was extensively carried out to replace the Ozone depleting and global warming refrigerants such as HFC and HCFC refrigerants. From the year of 2005, the Gas Engine Heat Pump(GHP) has been paid attention from the viewpoint of the gas cooling application. The heat pipe was focused on the performance improvement by the parametric analysis and the heat recovery applications. The storage systems were studied on the performance enhancement of the storage tank and cost analysis for heating and cooling applications. In the area of unused energy, the hybrid systems were extensively introduced and the life cycle cost analysis(LCCA) for the unused energy systems was also intensively carried out. (4) Recent studies of various refrigeration and air-conditioning systems have focused on the system performance and efficiency enhancement. Heat transfer characteristics during evaporation and condensation are investigated for several tube shapes and of alternative refrigerants including carbon dioxide. Efficiency of various compressors and expansion devices are also dealt with for better modeling and, in particular, performance improvement. Thermoelectric module and cooling systems are analyzed theoretically and experimentally. (5) According to the review of recent studies on ventilation systems, an appropriate ventilation systems including machenical and natural are required to satisfied the level of IAQ. Also, an recent studies on air-conditioning and absorption refrigeration systems, it has mainly focused on distribution and dehumidification of indoor air to improve the performance were carried out. (6) Based on a review of recent studies on indoor environment and building service systems, it is noticed that research issues have mainly focused on optimal thermal comfort, improvement of indoor air Quality and many innovative systems such as air-barrier type perimeter-less system with UFAC, radiant floor heating and cooling system and etc. New approaches are highlighted for improving indoor environmental condition as well as minimizing energy consumption, various activities of building control and operation strategy and energy performance analysis for economic evaluation.

• Journal of fish pathology
• /
• v.34 no.1
• /
• pp.71-80
• /
• 2021

Cephalexin, a semi-synthetic cephalosporin antibiotic, has long been used in fish aquaculture in various countries under legal authorization. The drug is thus widely available for use in other aquatic species except fishes like the crustacean whiteleg shrimp. This study aims to develop a sensitive method for laboratory residue studies to adopt in withdrawal period determinations. Through repeated trials from the existing methods developed for other food animal tissues, it was possible to achieve a sensitive high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method. The results showed that at a concentration of 0.1 mg/kg, the recovery rate was 81.79%, and C.V. value was 8.2%, which meet the recovery rate and C.V. recommended by Codex guideline. After satisfactory validation of analytical procedures, applicability to the shrimp tissue was confirmed in experimentally cephalexin-treated whiteleg shrimp. As a result, most muscle samples were detected below the limit of quantification (0.05 mg/kg) after day 3, and most hepatopancreas samples were detected below the limit of quantification after day 14. In particular, the limit of quantification 0.05 ppm with the presently developed method suggests sufficient sensitive over the current legal maximum residue limit of 0.2 mg/kg set for fishes.

• Analytical Science and Technology
• /
• v.35 no.3
• /
• pp.136-142
• /
• 2022

According to media reports, the carcasses of euthanized abandoned dogs were processed at high temperature and pressure to make powder, and then used as feed materials (meat and bone meal), raising the possibility of residuals in the feed of the anesthetic ketamine and dexmedetomidine used for euthanasia. Therefore, a simultaneous analysis method using QuEChERS combined with high-performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry was developed for rapid residue analysis. The method developed in this study exhibited linearity of 0.999 and higher. Selectivity was evaluated by analyzing blank and spiked samples at the limit of quantification. The MRM chromatograms of blank samples were compared with those of spiked samples with the analyte, and there were no interferences at the respective retention times of ketamine and dexmedetomidine. The detection and quantitation limits of the instrument were 0.6 ㎍/L and 2 ㎍/L, respectively. The limit of quantitation for the method was 10 ㎍/kg. The results of the recovery test on meat and bone meal, meat meal, and pet food showed ketamine in the range of 80.48-98.63 % with less than 5.00 % RSD, and dexmedetomidine in the range of 72.75-93.00 % with less than 4.83 % RSD. As a result of collecting and analyzing six feeds, such as meat and bone meal, prepared at the time the raw material was distributed, 10.8 ㎍/kg of ketamine was detected in one sample of meat and bone meal, while dexmedetomidine was found to have a concentration below the limit of quantitation. It was confirmed that the detected sample was distributed before the safety issue was known, and thereafter, all the meat and bone meal made with the carcasses of euthanized abandoned dogs was recalled and completely discarded. To ensure the safety of the meat and bone meal, 32 samples of the meat and bone meal as well as compound feed were collected, and additional residue investigations were conducted for ketamine and dexmedetomidine. As a result of the analysis, no component was detected. However, through this investigation, it was confirmed that some animal drugs, such as anesthetics, can remain without decomposition even at high temperature and pressure; therefore, there is a need for further investigation of other potentially hazardous substances not controlled in the feed.

• Korean Journal of Food Science and Technology
• /
• v.41 no.3
• /
• pp.258-264
• /
• 2009

The principal objective of this study was to estimate the measurement uncertainty associated with determination of deoxynivalenol (DON), a mycotoxin generated by Fusarium strain, in food. In service of this goal, wheat as a food matrix was analyzed via high performance liquid chromatography-ultraviolet (HPLC-UV) detection using an immunoaffinity column for clean-up. The uncertainty sources in the measurement process were identified by sample weight, final volume, and sample concentration in extraction volume with components including standard stock solution, working standard solution, 5 standard solutions, calibration curve, matrix, and instrument. The expanded uncertainty for DON at a concentration of 300 ${\mu}g/kg$ was estimated as 71.62 ${\mu}g/kg$ using a coverage factor of two, which provides a confidence level of approximately 95%. The most influential component in the uncertainty sources was the recovery of the wheat matrix, followed by the calibration curve. These results indicate that all efforts may be directed toward reducing the uncertainties of the recovery of the wheat matrix and the calibration curve to obtain a reliable HPLC-UV method for DON analysis in wheat.