• The Korean Journal of Financial Management
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• v.23 no.1
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• pp.243-266
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• 2006

This paper tests cross hedging performance of the KOSPI 200 stock index futures to hedge the downside risk of the KOSPI, KOSPI 200 and KOSDAQ50 spot market. For this purpose we introduce the minimum variance hedge model, bivariate GARCH(1,1) and EGARCH(1,1) model as hedge models. The main results are as follows; First, we find that the direct hedge performance of KOSPI 200 index futures is better than those of indirect hedge performance. second, in case or cross hedge performance the hedge effect of KOSPI 200 stock index futures market against KOSPI 200 stock index spot market is relatively better than those of KOSPI 200 index futures against KOSPI and KOSDAQ spot position. Third, for the out-sample, hedging effectiveness of the risk-minimization with constant hedge ratios is higher than those of the time varying bivariate GARCH(1,1) and EGARCH(1,1) model. In conclusion, investors are encouraged to use simple risk-minimization model rather than the time varying hedge models like GARCH and EGARCH model to hedge the position of the Korean stock index cash markets.

• Journal of Electrical Engineering and Technology
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• v.13 no.5
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• pp.1874-1885
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• 2018

The customer side operation is getting more complex in a smart grid environment because of the adoption of renewable resources. In performing energy management planning or scheduling, it is essential to forecast non-controllable resources accurately and robustly. The PV system is one of the common renewable energy resources in customer side. Its output depends on weather and physical characteristics of the PV system. Thus, weather information is essential to predict the amount of PV system output. However, weather forecast usually does not include enough solar irradiation information. In this study, a PV system power output prediction model (PPM) under limited weather information is proposed. In the proposed model, meteorological radiation model (MRM) is used to improve cloud cover radiation model (CRM) to consider the seasonal effect of the target region. The results of the proposed model are compared to the result of the conventional CRM prediction method on the PV generation obtained from a field test site. With the PPM, root mean square error (RMSE), and mean absolute error (MAE) are improved by 23.43% and 33.76%, respectively, compared to CRM for all days; while in clear days, they are improved by 53.36% and 62.90%, respectively.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.28 no.4
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• pp.102-108
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• 2005

Single PPM Quality Innovation Movement is originally developed quality program in Korea for supplier's quality level-up since 1995. The quality target is below the 10ppm(parts per million) in outgoing quality and delivered goods plus field claim. Recently 1,053 companies is received Single PPM Quality Certification from government. This quality program is to realized the anticipated results not only duality level's increasing, but also company's confidence, competitiveness. We were able to obtain participations of 75 questionnaire, and derived statistics by means of SPSS/PC version 10.0. In this study, we find the bottleneck factor for promotion and upgrade S-PPM, and suggest a way out of difficulties.

• Asian-Australasian Journal of Animal Sciences
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• v.17 no.12
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• pp.1736-1740
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• 2004

Since the application of relatively high levels of heavy metals in the compost poses a potential hazard to plants and animals, the content of heavy metals in the compost with animal manure is important to know if it is as a fertilizer. Measurement of heavy metals content in the compost by chemical methods usually requires numerous reagents, skilled labor and expensive analytical equipment. The objective of this study, therefore, was to explore the application of near-infrared reflectance spectroscopy (NIRS), a nondestructive, cost-effective and rapid method, for the prediction of heavy metals contents in compost. One hundred and seventy two diverse compost samples were collected from forty-seven compost facilities located along the Han river in Korea, and were analyzed for Cr, As, Cd, Cu, Zn and Pb levels using inductively coupled plasma spectrometry. The samples were scanned using a Foss NIRSystem Model 6500 scanning monochromator from 400 to 2,500 nm at 2 nm intervals. The modified partial least squares (MPLS), the partial least squares (PLS) and the principal component regression (PCR) analysis were applied to develop the most reliable calibration model, between the NIR spectral data and the sample sets for calibration. The best fit calibration model for measurement of heavy metals content in compost, MPLS, was used to validate calibration equations with a similar sample set (n=30). Coefficient of simple correlation (r) and standard error of prediction (SEP) were Cr (0.82, 3.13 ppm), As (0.71, 3.74 ppm), Cd (0.76, 0.26 ppm), Cu (0.88, 26.47 ppm), Zn (0.84, 52.84 ppm) and Pb (0.60, 2.85 ppm), respectively. This study showed that NIRS is a feasible analytical method for prediction of heavy metals contents in compost.

• Journal of Preventive Medicine and Public Health
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• v.27 no.1 s.45
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• pp.44-58
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• 1994

This study was conducted to examine the levels of total and organic mercury in the scalp hair of the elementary school children and adults, and their relationship with the consumption pattern of fishes and shellfishes. The scalp hair samples were collected from the occipital part of 115 children and 131 adults in costal, urban and rural areas of Kyungpook province from June to August 1991. The mercury content was analysed by the atomic absorption spectrophotometer (model IL. 555) with atomic vapor accessory (model IL. 440). The total and organic mercury contents of hair were significantly higher (p<0.01) among the children who prefer fish and/or shellfish (7.728 ppm, 6.610 ppm), and canned fish and/or fish pastes (6.969 ppm, 5.885 ppm) than those who prefer meat (4.822 ppm, 3.905 ppm) and vegetables (3.974 ppm, 3.224 ppm). The children who prefer to eat the canned fish without cooking showed a higher mercury content than the children who prefer to eat it as stew or mixed with vegetables (p<0.01). There was a dose-response relationship between the intake frequency of canned fish, raw fish and cooked fish and the content of total and organic mercury of hair, the children who eat fish almost everyday showed 2 times higher than those who eat rarely (p<0.01). The mercury content in the hair of the children who eat raw fish was significantly higher than that of the children who eat boiled or broiled fish (p<0.01). The total and organic mercury contents of adult scalp hair increased with age up to the forties and slightly decreased in the fifties. The mercury contents of those who were engaged in the fishery and raw fish restaurant were 2 times higher than those of the farmers. The mercury content of the persons who were favorite dishes of fish and shellfish were most high, and who prefer raw fish were 2 times higher than those of the persons who prefer vegetables and broiled fish. The contents of total and organic mercury in adult scalp hair showed also a increasing tendency with the intake frequency of raw and cooked fish.

• The Journal of Information Systems
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• v.30 no.3
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• pp.65-91
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• 2021

Purpose In this study, we investigated the impact of perceived risk and switching costs on switching intention to cloud service based on PPM (Pull-Push-Mooring) model. Design/methodology/approach We focused on revealing the switching factors of the switching intention to the cloud services. The switching factors to the cloud services were defined as perceived risk consisting of performance risk, economic risk, and security risk, and switching costs consisting of financial and learning costs. On the PPM model, we defined the pull factors consisting of perceived usefulness and perceived ease of use, and the push factor as satisfaction of the legacy system, and the mooring factor as policy supports. Findings The results of this study as follows; (1) Among the perceived risk factors, performance risk has a negative effect on the ease of use of pull factors, and finally it was found to affect the switching intention to the cloud services. Therefore, cloud service providers need to improve trust in cloud services, service timeliness, and linkage to the legacy systems. And it was found that economic risk and security risk among the perceived risk factors did not affect the switching intention to the cloud services. (2) Of the perceived risk factors, financial cost and learning cost did not affect the satisfaction of the legacy system, which is a push factor. It indicates that the respondents are positively considering switching to cloud service in the future, despite the fact that the respondents are satisfied with the use of the legacy system and are aware of the switching cost to cloud service. (3) Policy support was found to improve the switching intention to cloud services by alleviating the financial and learning costs required for cloud service switching.

• Journal of Plant Biotechnology
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• v.50
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• pp.108-114
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• 2023

In vitro conservation is one of the most effective strategies for rare plant protection, especially for orchid species. To maximize the success rates of in vitro explant establishment (stage I) in conservation programs, the application of tissue culture additives such as Plant Preservative Mixture^TM (PPM^TM) should be emphasized. In this study, we used Dendrobium thyrsiflorum Rchb.f. (1875) seeds and seedlings as a model for the evaluation of PPM^TM's phytotoxicity in the meristematic tissues of epiphytic orchids. PPM^TM had no observable inhibitory effect on protocorm, shoot, or root development when it was supplemented at 0.1%. PPM^TM supplementation caused adverse effects on D. thyrsiflorum explants at concentrations > 0.2%. At high concentrations, young in vitro seedlings showed damage, especially at the root tissue level. Based on this model, supplementation of 0.1-0.2% PPM^TM to culture media was successfully implemented to establish in vitro cultures of other rare orchid species in our conservation program.

• Journal of Environmental Science International
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• v.2 no.4
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• pp.271-278
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• 1993

Optimal biodegradation kinetics models to the initial nonylphenol ethoxylates-30 concentration were investigated and had been fitted by the linear regression. Microorganisms capable of degrading nonylphenol ethoxylates-30 were isolated from sewage near Ulsan plant area by enrichment culture technique. Among them, the strain designated as EL-10K had the highest biodegradability and was identified as Pseudomonas from results of taxonomical studies. The optimal conditions for the biodegradation were 1.0 g/ι of nonylphenol ethoxylates-30 and 0.02 g/ι of ammonium nitrate at pH 7.0 and 3$0^{\circ}C$. The highest degradation rate of nonylphenol ethoxylates-30 was about 89% for 30 hours incubation on the optimal condition. Biodegradation data were fit by linear regression to equations for 3 kinetic models. The kinetics of biodegradation of nonylphenol ethoxylates was best described by first order model for 0.1 $\mu\textrm{g}$/ι nonylphenol ethoxylates-30 ; by Monod no growth model and Monod with growth model for 0.5 $\mu\textrm{g}$/mι and 1.0, 5.0 $\mu\textrm{g}$/mι, respectively.

• Journal of Environmental Health Sciences
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• v.16 no.2
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• pp.1-10
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• 1990

This study was performed to evaluate a applicability of TCM(Texas Climatological Model) model to a industrial area sush as CUNSAN and a possibility to provide necessary informaitons for air quality management. The air pollutants were measured at 6 sampling sites of GUNSAN industrial area from june to july in 1989. The model was checked by comparing the observed data with estimated data. The meteorological data for wind direction and wind speed were obtained from the observatory station in GUNSAN. The results are summarized as follows. 1. Average concentrations of air pollutants at all sampling sites were SO$_{2}$ 0.011-0.019 ppm. NO$_{2}$ 0.012-0.017 ppm. CO 0.6-1.0 ppm. TSP 45.8-64.2 $\mu$g/m$^{3}$. 2. The emission amounts show that point source are in general higher than area source. 3. As a results of correlation analysis, relationship between SO$_{2}$ concentration in the observed value and estimated value showed positive significance.(r = 0.766) 4. The sulfer content of the 1.6% at present to 0.8%, which means a 53.3% reduction. By controlling stack height could be lowered 14.5%, but the effective way of emission control is use of the lower sulfer fuels than controlling stack height. 5. The ratio between SO$_{2}$ contration in the observed value and estimated value showed 1.05. There-fore, the TCM model was quite effective in predicting air quality in GUNSAN industrial area.

• Proceedings of the Safety Management and Science Conference
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• 2012.04a
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• pp.313-323
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• 2012

Single PPM Quality Innovation Program is to pursuit of defects below 10ppm in outgoing quality for strengthen the small and medium enterprise's competitiveness. This study aims to find that whether quality innovation promotion is significant or not in the ISO 9001 certification enterprises. To perform this research, we surveyed CEOs, managers and workers working for manufacturing business, we distributed 250 sheets totally and withdrew 171 sheets. We analyzed 135 sheets that we could use for this research using SPSS 15.0 and AMOS 18.0 program.