• Journal of Korean Society of Water and Wastewater
• /
• v.31 no.6
• /
• pp.539-549
• /
• 2017

In water treatment process using microfiltration membranes, manganese is a substance that causes inorganic membrane fouling. As a result of analysis on the operation data taken from I WTP(Water Treatment Plant), it was confirmed that the increase of TMP was very severe during the period of manganese inflow. The membrane fouling fastened the increase of TMP and shortened the service time of filtration or the cleaning cycle. The TMP of the membrane increased to the maximum of $2.13kgf/cm^2$, but it was recovered to the initial level ($0.17kgf/cm^2$) by the 1st acid cleaning step. It was obvious that the main membrane fouling contaminants are due to inorganic substances. As a result of the analysis on the chemical waste, the concentrations of aluminum(146-164 mg/L) and manganese(110-126 mg/L) were very high. It is considered that aluminum was due to the residual unreacted during coagulation step as a pretreatment process. And manganese is thought to be due to the adsorption on the membrane surface as an adsorbate in feed water component during filtration step. For the efficient maintenance of the membrane filtration facilities, optimization of chemical concentration and CIP conditions is very important when finding the abnormal level of influent including foulants such as manganese.

• Journal of Information Technology Application
• /
• v.3 no.2
• /
• pp.67-82
• /
• 2001

The ILOF project addresses the needs of logistics industrial organizations to reduce information processing time, improve added and residual value of information and reduce processing and transportation costs. It deals with the information supply chain information systems shared by vertical partner as important entity, whose performance and optimization very significantly affects the efficiency and performance of logistics industries. This paper deals with logistics information exchange systems based on supply chain management, focusing on sharing database and processes between partners such as shipper, logistics broker, transportation company, shipping company etc., for smoothing the information flow, enhancing consumer service and reducing communication fee and labour costs. The significance of contribution of this research is the provision of a model for logistics information exchange including entity relationship diagram, data flow diagram and functions which is able to facilitate the formulation of a customer driven supply chain information network, there by enhancing the competitive edge of companies in logistics industries on local and global basis.

• Journal of the Korean Society of Safety
• /
• v.24 no.2
• /
• pp.17-22
• /
• 2009

Thermal stress and elastic creeping stress analysis was conducted by finite element method to simulate start-up process of a boiler header of 500MW standard fossil power plant. Start-up temperature and operating pressure history were simplified from the real field data and they were used for the thermal stress analysis. Two kinds of thermal stress analysis were considered. In the first case only temperature increase was considered and in the second case both of temperature and operating pressure histories were considered. In the first analysis peak stress was occurred during the temperature increase from the room temperature. Hence cracking or fracture may occur at the temperature far below the operating maximum temperature. In the results of the second analysis von Mises stress appeared to be higher after the second temperature increase. This is due to internal pressure increase not due to the thermal stress. When the stress components of radial(r), hoop($\theta$) and longitudinal(z) stress were investigated, compression hoop stress was occurred at inner surface of the stub tube when the temperature increased from room temperature to elevated temperature. Then it was changed to tension hoop stress and increased because of the operating pressure. It was expected that frequent start-up and shut-down operations could cause thermal fatigue damage and cracking at the stub tube hole in the header. Elastic-creeping analysis was also carried out to investigate the stress relaxation due to creep and stabilized stress after considerable elapsed time. The results could be used for assessing the creep damage and the residual life of the boiler header during the long-tenn service.

• Journal of the Korean Wood Science and Technology
• /
• v.24 no.3
• /
• pp.18-27
• /
• 1996

The feasibility of using stress-wave technique in the transverse direction for the assessment of early stages of decay was investigated using compression test specimens having different annual ring orientations subjected to decay by Tyromyces palustris for various time intervals. Decay detection, quantitative assessment of decay, and the prediction of residual strength of decayed wood with less than five percent weight loss can be feasible using stress-wave parameters (wave velocity, wave impedance, and stress-wave elasticity) and their percent reduction due to decay, measured by stress-wave technique in the transverse direction. The use of stress-wave technique in the transverse direction for the application of this technique to structural members in service is desirable, when considering the easiness of attachment of accelerometers of stress-wave measuring device on the surface of members and also accurate detection of localized decayed areas. In stress-wave technique in the transverse direction, stress-wave parameters measured were different according to the angles between wave propagation path and annual ring, due to the anisotropy of wood structure. Therefore, it is recommended to use percent reduction in stress-wave parameters instead of stress-wave parameters. This evaluation method using percent reduction in stress-wave parameters is ideal when it is impossible to observe annual ring orientation on the transverse surface of wood.

• The Korean Journal of Pesticide Science
• /
• v.9 no.3
• /
• pp.231-236
• /
• 2005

This study was conducted to determine the amounts of pesticide residues after treatment of criterion dose with 4 pesticides(tolclofos-m, folpet, procymidone, and triflumizole) under cultivated period and to compare the biological half-life of pesticides with 6 kinetic models(first, zero and second order kinetics, power function, elovich and parabolic model) and to establish proposed field tolerance using biological half-lives. Recovery of 4 pesticides form strawberry was ranged from 85.1 to 105.5%. For all of 4 pesticides, dissipation rate was over 73% at 5 days after application. Among 6 kinetic models, first order kinetic model (FO) was best fit to describe the relationship between residual pattern of pesticides and time. Therefore, half-lives were calculated by FO for establishing the field tolerance. These results showed that half-life should be calculated by comparative best fit kinetic model and field tolerance can help to prevent unacceptable agricultural products from marketing. It is good for both consumers and farmers having safe agricultural products and financial benefits, respectively.

• Applied Biological Chemistry
• /
• v.47 no.2
• /
• pp.228-237
• /
• 2004

ASE (accelerated solvent extraction) was used to develop an analytical method for reducing the sample preparation time in pesticide residues analyses of agricultural produce. The conditions of ASE were as follows: preheat 1 min, heat 5 min, static 1 min, solvent flush% 60 vol., nitrogen purge 60 sec, 4 cycles, 1,500 psi pressure, and $100^{\circ}C$ temperature. When n-hexane:acetone (4 : l, v/v) was used as, an extraction solvent, the extraction and purification efficiency of ASE did not show the considerable difference compared with solvent extraction, and the reduction of extraction solvent did not affect the performance of extraction. It was proved that ASE method can reduce, sample preparation time as the extraction and purification steps were combined, and the extraction solvent was significantly reduced.

• Asian Pacific Journal of Cancer Prevention
• /
• v.16 no.16
• /
• pp.7303-7307
• /
• 2015

Background: Leukemia is a common cancer among children and adolescents. Wilms' tumor gene (WT1) is highly expressed in patients with acute leukemia. It is found as a tumor associated antigen (TAA) in various types of hematopoietic malignancies and can be employed as a useful marker for targeted immunotherapy and monitoring of minimal residual disease (MRD). In this regard, WT1 is a transcription factor that promotes gene activation or repression depending on cellular and promoter context. The purpose of this study was assessment of WT1 gene expression in patients with acute leukemia, measurement of IL-12 and C3 levels in serum and evaluation of the relationship between them. Materials and Methods: We evaluated the expression of WT1 mRNA using real-time quantitative RT-PCR and serum levels of IL-12 and C3 using ELISA and nephelometry in peripheral blood of 12 newly diagnosed patients with acute leukemia and 12 controls. Results: The results of our study showed that the average wT1 gene expression in patients was 7.7 times higher than in healthy controls (P <0.05). In addition, IL-12 (P = 0.003) and C3 (P <0.0001) were significantly decreased in the test group compared to controls. Conclusions: WT1 expression levels are significantly higher in patients compared with control subjects whereas serum levels of interleukin-12 and C3 are significantly lower in patients. Wt1 expression levels in patients are inversely related with serum levels of IL-12 and C3.

• Fire Science and Engineering
• /
• v.26 no.6
• /
• pp.99-108
• /
• 2012

These days, spontaneous ignition phenomena by oxidizing heat frequently occur in the circumstances of processing and storing waste tires. Therefore, to examine the phenomena, in this work, this researcher conducted the tests of fires of fragmented waste tires (shredded tire), closely investigated components of the fire residual materials collected in the processing and storing place, and analyzed the temperature of the starting of the ignition, weight loss, and heat of reaction. For the study, this researcher conducted fire tests with fragmented waste tires in the range of 2.5 mm to 15 mm, whose heat could be easily accumulated, and performed heat analysis through DSC and TGA, DTA, DTG, and GC/MS to give scientific probability to the possibility of spontaneous ignition. According to the tests, at the 48-hour storage, rapid increase in temperature ($178^{\circ}C$), Graphite phenomenon, smoking were observed. And the result from the DTA and DTG analysis showed that at $166.15^{\circ}C$, the minimum weight loss occurred. And, the result from the test on the waste tire analysis material 1 (Unburnt) through DSC and TGA analysis revealed that at $180^{\circ}C$ or so, thermal decomposition started. As a result, the starting temperature of ignition was considered to be $160^{\circ}C$ to $180^{\circ}C$. And, at $305^{\circ}C$, 10 % of the initial weight of the material reduced, and at $416.12^{\circ}C$, 50 % of the intial weight of the material decreased. The result from the test on oxidation and self-reaction through GC/MS and DSC analysis presented that oxidized components like 1,3 cyclopentnadiene were detected a lot. But according to the result from the heat analysis test on standard materials and fragmented waste tires, their heat value was lower than the basis value so that self-reaction was not found. Therefore, to prevent spontaneous ignition by oxidizing heat of waste tires, it is necessary to convert the conventional process into Cryogenic Process that has no or few heat accumulation at the time of fragmentation. And the current storing method in which broken and fragmented materials are stored into large burlap bags (500 kg) should be changed to the method in which they are stored into small burlap bags in order to prevent heat accumulation.

• Korean small business review
• /
• v.31 no.4
• /
• pp.67-93
• /
• 2009

The purpose of this paper is to explore the relations between financial constraints and dividend smoothing of innovative small and medium sized enterprises(SMEs) listed on Korea Securities Market and Kosdaq Market of Korea Exchange. The innovative SMEs is defined as the firms with high level of R&D intensity which is measured by (R&D investment/total sales) ratio, according to Chauvin and Hirschey (1993). The R&D investment plays an important role as the innovative driver that can increase the future growth opportunity and profitability of the firms. Therefore, the R&D investment have large, positive, and consistent influences on the market value of the firm. In this point of view, we expect that the innovative SMEs can adjust dividend payment faster than the noninnovative SMEs, on the ground of their future growth opportunity and profitability. And also, we expect that the financial unconstrained firms can adjust dividend payment faster than the financial constrained firms, on the ground of their financing ability of investment funds through the market accessibility. Aivazian et al.(2006) exert that the financial unconstrained firms with the high accessibility to capital market can adjust dividend payment faster than the financial constrained firms. We collect the sample firms among the total SMEs listed on Korea Securities Market and Kosdaq Market of Korea Exchange during the periods from January 1999 to December 2007 from the KIS Value Library database. The total number of firm-year observations of the total sample firms throughout the entire period is 5,544, the number of firm-year observations of the dividend firms is 2,919, and the number of firm-year observations of the non-dividend firms is 2,625. About 53%(or 2,919) of these total 5,544 observations involve firms that make a dividend payment. The dividend firms are divided into two groups according to the R&D intensity, such as the innovative SMEs with larger than median of R&D intensity and the noninnovative SMEs with smaller than median of R&D intensity. The number of firm-year observations of the innovative SMEs is 1,506, and the number of firm-year observations of the noninnovative SMEs is 1,413. Furthermore, the innovative SMEs are divided into two groups according to level of financial constraints, such as the financial unconstrained firms and the financial constrained firms. The number of firm-year observations of the former is 894, and the number of firm-year observations of the latter is 612. Although all available firm-year observations of the dividend firms are collected, deletions are made in the case of financial industries such as banks, securities company, insurance company, and other financial services company, because their capital structure and business style are widely different from the general manufacturing firms. The stock repurchase was involved in dividend payment because Grullon and Michaely (2002) examined the substitution hypothesis between dividends and stock repurchases. However, our data structure is an unbalanced panel data since there is no requirement that the firm-year observations data are all available for each firms during the entire periods from January 1999 to December 2007 from the KIS Value Library database. We firstly estimate the classic Lintner(1956) dividend adjustment model, where the decision to smooth dividend or to adopt a residual dividend policy depends on financial constraints measured by market accessibility. Lintner model indicates that firms maintain stable and long run target payout ratio, and that firms adjust partially the gap between current payout rato and target payout ratio each year. In the Lintner model, dependent variable is the current dividend per share(DPS_t), and independent variables are the past dividend per share(DPS_t-1) and the current earnings per share(EPS_t). We hypothesized that firms adjust partially the gap between the current dividend per share(DPS_t) and the target payout ratio(Ω) each year, when the past dividend per share(DPS_t-1) deviate from the target payout ratio(Ω). We secondly estimate the expansion model that extend the Lintner model by including the determinants suggested by the major theories of dividend, namely, residual dividend theory, dividend signaling theory, agency theory, catering theory, and transactions cost theory. In the expansion model, dependent variable is the current dividend per share(DPS_t), explanatory variables are the past dividend per share(DPS_t-1) and the current earnings per share(EPS_t), and control variables are the current capital expenditure ratio(CEA_t), the current leverage ratio(LEV_t), the current operating return on assets(ROA_t), the current business risk(RISK_t), the current trading volume turnover ratio(TURN_t), and the current dividend premium(DPREM_t). In these control variables, CEA_t, LEV_t, and ROA_t are the determinants suggested by the residual dividend theory and the agency theory, ROA_t and RISK_t are the determinants suggested by the dividend signaling theory, TURN_t is the determinant suggested by the transactions cost theory, and DPREM_t is the determinant suggested by the catering theory. Furthermore, we thirdly estimate the Lintner model and the expansion model by using the panel data of the financial unconstrained firms and the financial constrained firms, that are divided into two groups according to level of financial constraints. We expect that the financial unconstrained firms can adjust dividend payment faster than the financial constrained firms, because the former can finance more easily the investment funds through the market accessibility than the latter. We analyzed descriptive statistics such as mean, standard deviation, and median to delete the outliers from the panel data, conducted one way analysis of variance to check up the industry-specfic effects, and conducted difference test of firms characteristic variables between innovative SMEs and noninnovative SMEs as well as difference test of firms characteristic variables between financial unconstrained firms and financial constrained firms. We also conducted the correlation analysis and the variance inflation factors analysis to detect any multicollinearity among the independent variables. Both of the correlation coefficients and the variance inflation factors are roughly low to the extent that may be ignored the multicollinearity among the independent variables. Furthermore, we estimate both of the Lintner model and the expansion model using the panel regression analysis. We firstly test the time-specific effects and the firm-specific effects may be involved in our panel data through the Lagrange multiplier test that was proposed by Breusch and Pagan(1980), and secondly conduct Hausman test to prove that fixed effect model is fitter with our panel data than the random effect model. The main results of this study can be summarized as follows. The determinants suggested by the major theories of dividend, namely, residual dividend theory, dividend signaling theory, agency theory, catering theory, and transactions cost theory explain significantly the dividend policy of the innovative SMEs. Lintner model indicates that firms maintain stable and long run target payout ratio, and that firms adjust partially the gap between the current payout ratio and the target payout ratio each year. In the core variables of Lintner model, the past dividend per share has more effects to dividend smoothing than the current earnings per share. These results suggest that the innovative SMEs maintain stable and long run dividend policy which sustains the past dividend per share level without corporate special reasons. The main results show that dividend adjustment speed of the innovative SMEs is faster than that of the noninnovative SMEs. This means that the innovative SMEs with high level of R&D intensity can adjust dividend payment faster than the noninnovative SMEs, on the ground of their future growth opportunity and profitability. The other main results show that dividend adjustment speed of the financial unconstrained SMEs is faster than that of the financial constrained SMEs. This means that the financial unconstrained firms with high accessibility to capital market can adjust dividend payment faster than the financial constrained firms, on the ground of their financing ability of investment funds through the market accessibility. Futhermore, the other additional results show that dividend adjustment speed of the innovative SMEs classified by the Small and Medium Business Administration is faster than that of the unclassified SMEs. They are linked with various financial policies and services such as credit guaranteed service, policy fund for SMEs, venture investment fund, insurance program, and so on. In conclusion, the past dividend per share and the current earnings per share suggested by the Lintner model explain mainly dividend adjustment speed of the innovative SMEs, and also the financial constraints explain partially. Therefore, if managers can properly understand of the relations between financial constraints and dividend smoothing of innovative SMEs, they can maintain stable and long run dividend policy of the innovative SMEs through dividend smoothing. These are encouraging results for Korea government, that is, the Small and Medium Business Administration as it has implemented many policies to commit to the innovative SMEs. This paper may have a few limitations because it may be only early study about the relations between financial constraints and dividend smoothing of the innovative SMEs. Specifically, this paper may not adequately capture all of the subtle features of the innovative SMEs and the financial unconstrained SMEs. Therefore, we think that it is necessary to expand sample firms and control variables, and use more elaborate analysis methods in the future studies.