• The Transactions of the Korean Institute of Electrical Engineers A
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• v.55 no.5
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• pp.185-190
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• 2006

The security analysis relates to the ability of the electric systems to survive sudden disturbances such as electric short circuits or unanticipated loss of system elements. It is composed of both steady state and dynamic security analyses, which are not two separate issues but should be considered together. In steady state security analysis including voltage security analysis, the analysis checks that the system is operated within security limits by OPF (optimal power flow) after the transition of a new operating point. On the other hand, dynamic security analysis deals that the transition will lead to an acceptable operating condition. Transient stability, which is the ability of power systems to maintain synchronism when subjected to a large disturbance, is a principal component in dynamic security analysis. Usually any loss of synchronism will cause additional outages. They make the present steady state analysis of the post-contingency condition inadequate for unstable cases. This is the reason of the need for dynamics of systems. Probabilistic criterion can be used to recognize the probabilistic nature of system components and shows the possibility of system security. A comprehensive conceptual framework for probabilistic static and dynamic assessment is presented in this paper. The simulation results of the Western System Coordinating Council (WSCC) system compare an analytical method with Monte-Carlo simulation (MCS). Also, a case study of the extended IEEE Reliability Test System (RTS) shows the efficiency of this approach.

• Korean Journal of Animal Reproduction
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• v.20 no.3
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• pp.225-232
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• 1996

The purpose of this study was to evaluate effects of hormonal treatments on corpus lutea, follicles and development stage of embryos for enhancing the production efficiency of in vivo porcine embryos suitable to introduce fo foreign genes. Hundred and twenty gilts were allocated to 6 experimental group in different combinations of hormones PG 600, PMSG, hCG and altrenogest. When gilts were treated with chorionic gonadotrophin 200 IU and serum gonadotrophin 200 IU(PG 600), altrenogest, serum gonadotrophin (PMSG) 1,000 IU, and chorionic gonadotrophin(hCG) 750 IU (PAPh), the numbers of corpus luteum (30.4) were significantly higher than those of other treatment groups (P<0.05). The number of corpus luteum from ovary in either right (9.1) or left (10.1) side was not significantly changed with hormone treatments. Number of follicles in control was 20.7, which was higher than those of hormonal treatment groups. The average numbers of 1, 2, 4 and 8 cell staged embryos were 8.1, 1.4, 1.6 and 1.0 in control, but the numbers of 1-cell stage in PAPh treatment group was 24.2, which was significantly higher than those of treatment groups (P<0.05). Therefore, these data indicated that hormonal treatment, especially PAPh, enhanced the developments of follicles, corpus lutea and embryos and increased the collection rate of the 1-cell stage embryos to introduce of foreign genes.

• Journal of Physiology & Pathology in Korean Medicine
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• v.21 no.3
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• pp.666-670
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• 2007

Efficacy of antioxidative activity and nitrite scavenging ability of methanol extract from Ricinus communis. was investigated. Electron-donating ability of extract at RC$_{50}$ was 114.02 ${\mu}g$/mL. After addition of 0.46 mg/mL extract, autoxidation of pyrogallol decreased to 32.99% by superoxide dismutase-like activity. In antioxidative activity of extract against linoleic acid during incubation times of 24, 48, 96 hours at 40$^{\circ}C$, lipid peroxidation values significantly decreased by 85.50%, 87.77%, 90.95% with addition of 0.2 mg/mL, respectively. Total phenolic content was determined as gallic acid equivalents (GAE) and values revealed 83.98 ${\pm}$ 5.66 GAE ${\mu}g$/mg of extract. Nitrite scavenging ability showed the most remarkable effect at pH 1.2, decreasing to 47.24% by addition of 0.2 mg/mL. These results suggest that methanol extract from Ricinus communis. can be used as bioactive and functional material.

• Journal of Energy Engineering
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• v.15 no.4 s.48
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• pp.256-276
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• 2006

Transmission congestion is one of the key factors to local market power in competitive electricity markets. Financial transmission rights provide the financia] protection to their holders by paying back the congestion rent. A variety researches have shown that the existing trading mechanisms on transmission right can exacerbate market power. This paper proposes an alternative methodology in mitigating the local market power using the Contingent Transmission Rights on the locational marginal pricing scheme. The proposed methodology was demonstrated with the Optimal Power Flow.

• Asian-Australasian Journal of Animal Sciences
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• v.19 no.11
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• pp.1623-1631
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• 2006

The objective of this study was to evaluate the effect of protein and energy on goats fed oil palm fronds (OPF) as roughages. Twenty-four male Saanen goats aged between 7 and 8 months and weighing $23.4{\pm}1.6kg$ were used in a $2{\times}3$ factorial design. Factors were three levels of urea (3%, 4% or 5%) and two levels of energy (low energy (LE) or high energy (HE)). On average, all parameters measured, including dry matter intake (DMI), nutrient digestibility, digestible nutrient intakes, ruminal ammonia-N ($NH_3$-N), ruminal total volatile fatty acid (total VFA) and individual VFA concentrations (mM/L), microbial N supply, P/E ratio and N retention were higher for HE compared to LE diets. Significant (p<0.05) interactions were found between levels of urea and energy for nonstructural carbohydrate (NSC) and energy (DE) digestibilities, ruminal $NH_3$-N and total VFA concentrations. HE diets had higher N absorption and retention than LE diets. Interactions between urea and energy for plasma urea nitrogen (PUN), heat production (HP), and urine and faeces N excretion were significantly lower (p<0.05) for the HE diets than those recorded for the LE diets. The results indicated that supplementation of energy enhanced utilization of urea and resulted in higher animal performance as a consequence of improved ruminal fermentation, microbial yield and N balance. However, the optimal level of urea supplementation remained at 3% in the HE diet.

• Proceedings of the KIEE Conference
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• 2005.11b
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• pp.46-48
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• 2005

This paper discusses a probabilistic method for power system security assessment. The security analysis relates to the ability of the electric power systems to survive sudden disturbances such as electric short circuits or unanticipated loss of system elements. It consists of both steady state and dynamic security analyses, which are not two separate issues but should be considered together. In steady state security analysis including voltage security analysis, the analysis checks that the system is operated within security limits by OPF (optimal power flow) after the transition to a new operating point. Until now, many utilities have difficulty in including dynamic aspects due to computational capabilities. On the other hand. dynamic security analysis is required to ensure that the transition may lead to an acceptable operating condition. Transient stability, which is the ability of power systems to maintain synchronism when subjected to a large disturbance. is a principal component in dynamic security analysis. Usually any loss of synchronism may cause additional outages and make the present steady state analysis of the post-contingency condition inadequate for unstable cases. This is the reason for the need of dynamic studies in power systems. Probabilistic criterion can be used to recognize the probabilistic nature of system components while considering system security. In this approach. we do not have to assign any predetermined margin of safety. A comprehensive conceptual framework for probabilistic static and dynamic assessment is presented in this paper. The simulation results of the Western System Coordinating Council (WSCC) system compare an analytical method with Monte-Carlo simulation (MCS).

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.6
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• pp.2973-2977
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• 2016

Opisthorchis viverrini is still a serious problem in Northeastern and Northern Thailand. Active surveillance is required to determine updated data for further prevention and control planning. Therefore, this study aimed to examine the prevalence and risk factors for O. viverrini in three provinces, Northeastern Thailand. A cross-sectional survey was conducted during October 2015 to March 2016 at Kaeng Sanam Nang district of Nakhon Ratchasima province, Waeng Noi district of Khon Kaen province, and Khon Sawan district of Chaiyaphum province, Thailand. Stool samples were examined by using a modified Kato-Katz Thick smear technique. From a total of 978 participants screened, O. viverrini infection was found in 1.74%, the majority opf positive cases being male (6.62%), age group 51-60 years old (4.21%), educated at primary school (8.43%), occupied with agriculture (9.62%),having an income <4,000 baht per month (4.82%), and living in Khon Sawan district (8.43%). Participants had a high knowledge level (42.43%), good attitude level (34.76%), and fair level (38.04%). The present study indicates the O. viverrini infection rate is low, but elderly males with primary school education involved in agriculture are still frequently effected particularly in Khon Sawan district. Therefore, this risk group requires behavior modification and continued monitoring.

• Journal of Electrical Engineering and Technology
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• v.5 no.3
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• pp.353-362
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• 2010

This paper presents a centralized control algorithm for power system performance in the Korean power system using Flexible AC Transmission Systems (FACTS) devices. The algorithm is applied to the Korean power system throughout the metropolitan area in order to alleviate inherent stability problems, especially concerns with voltage stability. Generally, control strategies are divided into local and centralized control. This paper is concerned with a centralized control strategy in terms of the global system. In this research, input data of the proposed algorithm and network data are obtained from the SCADA/EMS system. Using the full system model, the centralized controller monitors the system condition and decides the operating point according to the control objectives that are, in turn, dependent on system conditions. To overcome voltage collapse problems, load-shedding is currently applied in the Korean power system. In this study, the application of the coordination between FACTS and switch capacitor (SC) can restore the solvability without load shedding or guarantee the FV margin when the margin is insufficient. Optimal Power Flow (OPF) algorithm, for which the objective function is loss minimization, is used in a stable case. The results illustrate examples of the proposed algorithm using SCADA/EMS data of the Korean power system in 2007.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.45 no.2
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• pp.33-40
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• 2013

Powdered additive or organic filler is used to improve paperboard thickness and to reduce drying energy consumption in the Korean paperboard industry. In a previous study, we identified alternative non-lignocellulosic resources to wood powder, specifically brewers grain and oil palm frond powders, and verified that these materials had the same functionality as wood powder. The main drawback of the use of such additives, including both lignocellulosic and non-lignocellulosic resources, is the deterioration in paperboard strengths. Therefore, we carried out a basic study on the surface modification of brewers grain and oil palm frond powders to improve the strengths of paperboard. Surface modification was performed using various types of cationic and oxidized starches. The streaming current and zeta-potential of the two non-lignocellulosic powders were measured and CLSM images were taken to assess the surface modification.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.5
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• pp.78-84
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• 2006

As electric power systems have been moving from a vertically integrated structure to a deregulated environment, calculating reactive power service charges is a new challenging theme for market operators. This paper examines various methods for reactive power management adopted in some deregulated foreign and domestic markets and then proposes a new method to calculate reactive power service charges using a reactive power market. The reactive power market is operated based on bids from the generating sources and is settled on uniform prices by running reactive OPF programs after the day-ahead electricity market. The proposed method takes into account recovering not only the costs of installed capacity but also the lost opportunity costs incurred by reducing active power output to increase reactive power production. A numerical sample study is carried out to illustrate the processes and appropriateness of the proposed method.