• Korean Journal of Veterinary Service
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• v.20 no.1
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• pp.79-93
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• 1997

The sulfonamide is one of potentiative antimicrobial agents which is being used widely in veterinary medicine for control of several animal diseases such as mastitis as well as for promotion of growth. However, the misusages of sulfonamides in food producing animals, especially cattle produce several considerable problems in human health caused from residues of this antibiotic in milk product. To determine the most effective analytical methods for residual sulfonamides in raw milk, this study was performed comparatively using by some applicable screening detecting method such as TTC, Charm II test (sulfonamides), and Lactek tests (sulfamethazine kit). The positive result from screening tests was confirmed by HPLC method. Milk samples (540 raw milks) were collected from dairy farms. Results of this study are summariezed as follorrs ; 1. All samples (540 raw milks) showed negative response from TTC test, however, 18 raw milks of those samples responded positively to Charm II test. 2. By Lactek test, residual sulfamethazine was detected from 4 raw milks. Fifteen raw milks of 18 samples which were classified as positive one by Charm II test, showed positive response 3. Retention time of sulfonamides added at the level of 100ppb into sklm milk was ranged from 1.55 minute to 23.3 minute. Recovery rates of sulfonamides were variable from 6.7% upto 94.2% depended on the types of sulfonamlde. 4. Single type of sulfonamides was detected from 10 raw milk samples, 2 types of sulfonamides from 3 samples and 3 types from 2 raw milks by HPLC. 5. Sulfonamides was detected in this study were 5 types : 11 samples for sulfisomidine, 5 samples for sulfamethazine, 3 samples for sulfadlmethoxine, 2 samples for sulfathiazole and 1 sample for sulfadiazine. 6. The highest levels of residual sulfonamides was 210.3 ppb of sulfamethazine but the lowest concentration of residue was 2.2 ppb of sulfamethazine and sulfisomidine, respectively. Number of samples detected positively in this experiment were belows : above 100 ppb for 1 sample (4.5%) (sulfamethazine), 50~100 ppb for 4 samples (18.1%) (each 2 samples for sulfamethazine and sulfisomidine, respectively), 25~50 ppb for 6 samples (27.1%) (2 sulfisomidine, each 1 sample for sulfadiazine, sulfadimethoxine, sulfamethazine and sulfathiazole, respectively), 10~25ppb for 3 samples (13.7%) (3 sulfisomidine), and below 10ppb for 8 samples (36.4%) (4 sulfisomidine, 2 sulfadimethoxine and each 1 for sulfamethazine and sulfathiazole).

• Steel and Composite Structures
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• v.46 no.3
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• pp.385-401
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• 2023

Steel is becoming increasingly popular due to its high strength, excellent ductility, great assembly performance, and recyclability. In reality, steel structures serving for a long time in atmospheric, industrial, and marine environments inevitably suffer from corrosion, which significantly decreases the durability and the service life with the exposure time. For the mechanical properties of corroded steel, experimental studies are mainly conducted. The existing numerical analyses only evaluate the mechanical properties based on corroded morphology at the isolated time-in-point, ignoring that this morphology varies continuously with corrosion time. To solve this problem, the relationships between pit depth expectation, standard deviation, and corrosion time are initially constructed based on a large amount of wet-dry cyclic accelerated test data. Successively, based on that, an in-situ pitting evolution method for evaluating the residual tensile strength of corroded steel is proposed. To verify the method, 20 repeated simulations of mass loss rates and mechanical properties are adopted against the test results. Then, numerical analyses are conducted on 135 models of corrosion pits with different aspect ratios and uneven corrosion degree on two corroded surfaces. Results show that the power function with exponents of 1.483 and 1.091 can well describe the increase in pit depth expectation and standard deviation with corrosion time, respectively. The effect of the commonly used pit aspect ratios of 0.10-0.25 on yield strength and ultimate strength is negligible. Besides, pit number ratio α equating to 0.6 is the critical value for the strength degradation. When α is less than 0.6, the pit number increases with α, accelerating the degradation of strength. Otherwise, the strength degradation is weakened. In addition, a power function model is adopted to characterize the degradation of yield strength and ultimate strength with corrosion time, which is revised by initial steel plate thickness.

• The Korean Journal of Pesticide Science
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• v.13 no.2
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• pp.79-86
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• 2009

In order to elucidate the residual characteristics of the insecticides, bifenthrin and imidacloprid, the pesticides were sprayed onto the squash and their residues were analyzed with GC-ECD and HPLC. Detection limits of the pesticides were $0.005\;mg;kg^{-1}$ and recoveries of bifenthrin and imidacloprid in squash were from 100.87 to 104.31 and from 79.71 to 92.54%, respectively. Half-lives of bifenthrin and imidacloprid in squash were from 1.8 to 2.9 and from 1.5 to 2.5 days, respectively. Initial concentration of bifenthrin and imidacloprid sprayed at the recommended rate and double rate of recommendation were less than their MRLs. And also, residueal concentrations of the pesticides were rapidly decreased in squash with time. At harvest, estimated daily intakes (EDIs) of the pesticides were less than 0.6% of their acceptable daily intakes (ADIs).

• Korean Journal of Veterinary Service
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• v.23 no.4
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• pp.321-333
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• 2000

In order to know the depletive changes of sulfamethazine residues in senlm and practical organs of rats orally administered with sulfamethazine sodium(SMS), the concentration of sulfamethazine was measured in serum and tissue(kidney, liver, spleen, testis, and skeletal muscle) of rats with using high performance liquid chromatography(HPLC). SMS was orally administrated to sprague-dawley male rats(body weight, 200~300g) with using sonde at the rate of 20mg/100g body weight(recommended therapeutic dose) on once a day for 3 days. There were investigated the depletive changes of the sulfamethazine in serum, kidney, liver, spleen, testis and skeletal muscle of rat at the time 8 hours, 1st, 2nd, 3rd, 4th, 5th and 6th day after administration SMS, respectively. The results obtained were summarized as follows; 1. After oral administration of the SMS, the mean concentrations of sulfamethazine in serum according to the time lapsed were showed 215.53$\pm$42.99ppm at the 8 hours after withdrawal of medicated sulfamethazine. And gradually according to the time lapsed, the concentrations of sulfamethazine residues in serum were significantly (p<.05) decreased 25.87$\pm$5.18ppm at 1st day, 2.30$\pm$0.61ppm at 3rd day and 0.11$\pm$0.02ppm at 6th day respectively. 2. The mean concentrations of sulfamethazine in kidney, liver, spleen, muscle and testis according to the time lapsed after administration SMS were showed 83.82$\pm$12.16, 81.77$\pm$12.88, 36.96$\pm$5.35, 35.96$\pm$TEX>$\pm$1.39 and 27.89$\pm$1.92 ppm at the 8 hours, respectively. And gradually according to the time lapsed, the concentrations of sulfamethazine residues in the each of samples were significantly(p<.05) decreased such as 7.15$\pm$0.26, 5.62$\pm$0.72, 2.43$\pm$0.29, 1.99$\pm$0.14 and 3.11$\pm$0.48 ppm at 1st day, 0.52$\pm$0.04, 1.32$\pm$0.22, 0.13$\pm$0.03, 0.15$\pm$0.06 and 0.26$\pm$0.11ppm at 3rd day, and 0.03$\pm$0.01, 0.11$\pm$0.03, 0.02$\pm$0.01, 0.009$\pm$0.001 and 0.02$\pm$0.01 ppm at 6th day, respectively. 3. After oral administration of the SMS to rats, the residual concentrations of sulfamethazine in skeletal muscle were significantly (p<.05) decreased 35.96$\pm$1.39 to 0.009$\pm$$\pm$0.001 ppm between 8 hours and 6th day, respectively From the 4th day, the residual concentrations of sulfamethazine were showed 0.10$\pm$0.04 ppm below 0.1 ppm at the permitted limit concentration of muscle in Korea. In conclusion, this study could be suggested the relationship between administrated period, doses of sulfonamides and residual aspects of serum and practical organs, and the importance of observing ceasing period of antibiotic drugs before forwarding livestocks to slaughter.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.3
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• pp.163-169
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• 2016

To establish the equitable distribution of total energy load, a representative cluster based routing protocol LEACH selects cluster heads randomly in accordance with the pre-determined probability every round. But because the current energy level of sensor nodes is not considered, if a sensor node which has little residual energy is elected as a cluster head, it can not live to fulfil the role of cluster head which has big energy load. As a result, the first time of death of a node is quickened and the service quality of WSN gets worse. In this regard we propose a new routing method that, by considering the current energy of a cluster head and the distance between cluster heads and a base station, selects the sub cluster head for saving the energy of a cluster head. Simulation results show that the first time of death of a node prolongs, more data arrive at the base station and the service quality of WSN improves.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.1
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• pp.22-31
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• 1997

The grain boundary etching method as a method for assessing degradation of structural materials has received much attention because it is simple, inexpensive and easy to apply to real components. In this study, the effectiveness of the method is verified by successfully applying the technique to in-service components of aged fossil power plants such as main steam pipes, boiler headers an turbine rotors. A new degradation parameter, intersecting number ratio (N$_{1}$/N$_{0}$), is employed. The intersecting number ratio (N$_{1}$/N$_{0}$) is defined as the ratio of intersection number (N$_{1}$) obtained from 5-minute picric acid etched surface to the number (N$_{0}$) obtained from nital etched surface. Two kinds of test materials, 2.25Cr-1Mo steel and 1Cr-1Mo-0.25V steel, were artificially thermal-aged at 630.deg. C in different levels of degradation., (N$_{1}$/N$_{0}$) were measured. And, correlations between the measured values and LMP values calculated from aging temperature and aging time were sought. To check the validity of the correlations obtained in laboratory, similar data were measured from service components in four old Korean fossil power plants. These on-site measurement data were in good correlation with those obtained in the laboratory.oratory.

• Journal of Institute of Control, Robotics and Systems
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• v.6 no.8
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• pp.638-651
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• 2000

When the bandwidth resources in a packet-switched network are shared among sessions by MAX-MIN flow control each session is required to transmit its data into the network subject to the MAX-MIN fair rate which is solely determined by network loadings. This passive behavior of sessions if fact can cause seri-ous QoS(Quality of Service) degradation particularly for real-time multimedia sessions such as video since the rate allocated by the network can mismatch with what is demanded by each session for its QoS. In order to alleviate this problem we extend the concept of MAX-MIN fair bandwidth allocations as follows: Individual bandwidth demands are guaranteed if the network can accommodate them and only the residual network band-width is shared in the MAX-MIN fair sense. On the other hand if sum of the individual bandwidth demands exceeds the network capacity the shortage of the bandwidth is shared by all the sessions by reducing each bandwidth guarantee by the MAX-MIN fair division of the shortage. we present a novel flow control algorithm to achieve this extended MAX-MIN fairness and show that this algorithm can be implemented by the existing ATM ABR service protocol with minor changes. We not only analyze the steady state asymptotic stability and convergence rate of the algorithm by appealing to control theories but also verify its practical performance through simulations in a variety of network scenarios.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.44 no.4
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• pp.65-75
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• 2021

This study explores multiple variables of an OTT service for discovering hidden relationship between rating and the other variables of each successful and failed content, respectively. In order to extract key variables that are strongly correlated to the rating across the contents, this work analyzes 170 Netflix original dramas and 419 movies. These contents are classified as success and failure by using the rating site IMDb, respectively. The correlation between the contents, which are classified via rating, and variables such as violence, lewdness and running time are analyzed to determine whether a certain variable appears or not in each successful and failure content. This study employs a regression analysis to discover correlations across the variables as a main analysis method. Since the correlation between independent variables should be low, check multicollinearity and select the variable. Cook's distance is used to detect and remove outliers. To improve the accuracy of the model, a variable selection based on AIC(Akaike Information Criterion) is performed. Finally, the basic assumptions of regression analysis are identified by residual diagnosis and Dubin Watson test. According to the whole analysis process, it is concluded that the more director awards exist and the less immatatable tend to be successful in movies. On the contrary, lower fear tend to be failure in movies. In case of dramas, there are close correlations between failure dramas and lower violence, higher fear, higher drugs.

• Journal of the Korea Concrete Institute
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• v.23 no.4
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• pp.431-440
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• 2011

Concrete structures exposed to fire produce changes in their internal structure, resulting in their service life reduction due to the deterioration of its strength and performance capacity. The deterioration level are dependent on the temperature, exposure time, concrete mix proportions, aggregate property, and material properties. This study was performed to evaluate the thermal behavior of ultra-high strength concrete for the parameters of water to cement ratio (compressive strength), fine to total aggregate ratio, and maximum coarse aggregate size. At room temperature and $500^{\circ}C$, tests of ultrasonic pulse velocity, resonance frequency, static modulus of elasticity, and compressive strength are performed using ${\varnothing}100{\times}200\;mm$ cylindrical concrete specimens. The results showed that the residual mechanical properties of ultra-high strength concrete heated to $500^{\circ}C$ is influenced by variation of a water to binder ratio, fine to total aggregate ratio, and maximum coarse aggregate size.

• Geomechanics and Engineering
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• v.19 no.6
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• pp.499-511
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• 2019

The reliability of reinforced concrete structures is frequently compromised by the deterioration caused by reinforcement corrosion. Evaluating the effect caused by reinforcement corrosion on structural behaviour of corrosion damaged concrete structures is essential for effective and reliable infrastructure management. In lifecycle management of corrosion affected reinforced concrete structures, it is difficult to correctly assess the lifecycle performance due to the uncertainties associated with structural resistance deterioration. This paper presents a stochastic deterioration modelling approach to evaluate the performance deterioration of corroded concrete structures during their service life. The flexural strength deterioration is analytically predicted on the basis of bond strength evolution caused by reinforcement corrosion, which is examined by the experimental and field data available. An assessment criterion is defined to evaluate the flexural strength deterioration for the time-dependent reliability analysis. The results from the worked examples show that the proposed approach is capable of evaluating the structural reliability of corrosion damaged concrete structures.