• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.61 no.12
• /
• pp.1765-1773
• /
• 2012

The accuracy of load forecast is very important from the viewpoint of economical power system operation. In general, the weekdays' load demand pattern has the continuous time series characteristics. Therefore, the conventional methods expose stable performance for weekdays. In case of special days or weekends, the load demand pattern has the discontinuous time series characteristics, so forecasting error is relatively high. Especially, weekdays near the thanksgiving day and lunar new year's day have the mixed load profile characteristics of both weekdays and weekends. Therefore, it is difficult to forecast these days by using the existing algorithms. In this study, a new load forecasting method is proposed in order to enhance the accuracy of the forecast result considering the characteristics of weekdays and weekends. The proposed method was tested with these days during last decades, which shows that the suggested method considerably improves the accuracy of the load forecast results.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2017.05a
• /
• pp.275-278
• /
• 2017

The automotive society is facing many challenges in minimizing the energy loss to improve performance and fuel economy of the vehicle. This work "Implement of Power Density for AC Generator Using a Fill Factor of Slot" is a research in Electrical Generator design, to improve power density of Alternator used in conventional IC engine powered vehicles. The power density of the alternator directly influences the fuel economy and performance in the motor vehicle. The size and weight of the alternator can be reduced by suitably designing power density of alternator. The simulation model of alternator is made and tested for different stator space factor using solid and round conductor to demonstrate the improvement in the output performance and efficiency. The result shows that there is an average 10% improvement in efficiency of alternator by using the solid conductor. The energy balance of the system also increased SOC in the base model.

• Journal of Power Electronics
• /
• v.14 no.5
• /
• pp.980-988
• /
• 2014

This paper proposes an online gain tuning algorithm for a robust sliding mode speed controller of surface-mounted permanent magnet synchronous motor (SPMSM) drives. The proposed controller is constructed by a fuzzy neural network control (FNNC) term and a sliding mode control (SMC) term. Based on a fuzzy neural network, the first term is designed to approximate the nonlinear factors while the second term is used to stabilize the system dynamics by employing an online tuning rule. Therefore, unlike conventional speed controllers, the proposed control scheme does not require any knowledge of the system parameters. As a result, it is very robust to system parameter variations. The stability evaluation of the proposed control system is fully described based on the Lyapunov theory and related lemmas. For comparison purposes, a conventional sliding mode control (SMC) scheme is also tested under the same conditions as the proposed control method. It can be seen from the experimental results that the proposed SMC scheme exhibits better control performance (i.e., faster and more robust dynamic behavior, and a smaller steady-state error) than the conventional SMC method.

• The Transactions of the Korea Information Processing Society
• /
• v.3 no.6
• /
• pp.1542-1552
• /
• 1996

This paper presents a design and implementation of an extended directory system in manage and provide an effective search operation of the DFR(Document Filing and Retrieval) Object's attributes. For this, the design and implementation of a configuration model for interworking between the DFR and directory systems, an association mechanisms between two application's operation, extended directory schema and extended DIT(Directory Information Tree) are described. In a distributed environment, the interworking between the DFR and directory system implemented by using QUIPU 8.0 of ISODE(ISO Development Environment) directory system is tested. based on the result of this paper, an extended model of the directory system is proposed for proving search operation of various application's objects.

• The Transactions of the Korean Institute of Electrical Engineers A
• /
• v.51 no.8
• /
• pp.398-402
• /
• 2002

The ELD computation has been based upon the so-called B-coefficient which uses a quadratic approximation of system loss as a function of generation output. Direct derivation of system loss sensitivity based on the Jacobian-based method was developed in early 1970s', which could eliminate the dependence upon the approximate loss formula. However, both the B-coefficient and the Jacobian-based method require a complicated Procedure for calculating the system loss sensitivity included in the constraints of the optimization problem. In this paper, an ELD formulation in which only the bus power equations are defined as the constraints has been introduced. Derivation of the partial derivatives of the system loss with respect to the generator output and calculation of the penalty factors for individual generators are not required anymore in proposed method. A comprehensive solution procedure including calculation of the Jacobians and Hessians of the formulation has been presented in detail. Proposed ELD formulation has been tested on a sample system and the simulation indicated a satisfactory result.

• KSBB Journal
• /
• v.25 no.6
• /
• pp.513-519
• /
• 2010

Marine bacterium producing pigment was isolated from the solar saltern of Mijo-myeon, Namhae, Korea. Based on phenotypic characteristics and 16S rRNA sequence analysis, the strain was identified as Kocuria sp., which produced a yellow pigment. The pigment showed UV absorption maximum at 469nm. The bacterial strain grew well on Marine broth 2216 culture medium. Productivity of the pigment reached the maximum value after 44 hours at $30^{\circ}C$, 2% NaCl and pH 6.0. The pigment was produced best when supplied by 1% lactose as a carbon source and 1% beef extract as a nitrogen source. The result of the color stability study showed that pigment extracted from the strain by ethanol was stable at $-20-25^{\circ}C$ and also showed higher stability over 70% for 14 days in light conditions at $25^{\circ}C$. The pigment extract was also stable for all metal ions tested, except for $FeCl_2$.

• Journal of Information Technology Applications and Management
• /
• v.20 no.4
• /
• pp.67-81
• /
• 2013

Domestic telecommunication companies have increased in marketing expenditures and capital investments in their plants and equipments. Their expectation for their investment sometimes results in the shrinking of their ARPUs(average revenues per user) as well as decreasing of net profits. Those financial efforts have not always been positive relation with their ARPUs. Since western and european telecommunication industry recently have similar situation with our market where their mobile and network users have been saturated so that no more increased users are estimated. Therefore, this paper aims for first to explore methods maximizing the investments efficiency for the telecommunication company so that we choose bechmarked telecommmunication companies to explore their investment managing situation with resepct to their marketing and capital expenditure. Secondly this paper tried to suggest several public policy guidelines for domestic telecommunication industry. Total seventeen foreign telecommunication companies were selected and data set through official IR as well as AR were chosen. Curvilinear logarithmic regression analysis were tested to obtain elasticities as well as marginal effects. As a result, overspending on the marketing investment showed more negative indicators to their revenues, on the other hand, more investment in the Capex such as network infrastructures and other service facilities were more likely related to positive revenues.

• Journal of the Korean Chemical Society
• /
• v.40 no.12
• /
• pp.719-723
• /
• 1996

An inverse photoemission spectrometer has been built and tested to study the unoccupied electron energy states of solid surfaces. It consists of a low energy electron gun and a band pass photon detector in an ultra-high vacuum chamber. The electron ray tracing simulation and current measurement of the electron gun show a good focus and a high flux of electron current. The overall resolution of the spectrometer is 0.74 eV and the sensitivity of the photon detector is about 10 counts/$sec{\cdot}{\mu}A.$ As a test experiment, the inverse photoemission spectra of a Ge(111) sample is in good agreement with the theoretical result.

• Journal of the Ergonomics Society of Korea
• /
• v.20 no.2
• /
• pp.47-57
• /
• 2001

To simulate an actual slip to measure floor slipperiness, slip resistance testers simulate slip in only forward direction because forward slip in the landing phase was found to be the most important factor for loss of balance. Backward slip in the take off phase was possible but was excluded in the friction test protocol because it was not dangerous. However, backward slip was tested in the friction test protocol without any theoretical background of the significance in generating dangerous slips and falls and was proven to be as good as forward slip in measuring floor slipperiness. Therefore, this study was designed to investigate the significance of backward slip in generating dangerous slips and falls with different combinations of floor and shoe sole. The results showed different tendency of backward slip in take off phase being significant in generating dangerous slips and falls because backward slip in the takeoff phase affected gait pattern disturbances seriously. resulted in dangerous falls. Fast toe velocity increased the severity of backward slip and confirmed the significance of backward slip in generating dangerous slips and falls. As a result, this study recommends the utilization of backward slip in the measurement of floor slipperiness.

• Journal of Korean Critical Care Nursing
• /
• v.11 no.3
• /
• pp.12-22
• /
• 2018

Purpose : This methodological study develops an oral health assessment tool for critically ill patients. Method : From February 15 to April 30, 2014, this study was conducted to test the validity and reliability of the tool at two general hospitals and three medical and surgical intensive care units (ICUs) in Seoul, Korea. Results : The result of the intraclass correlation coefficient to test the between-observer reliability by analyzing the oral health assessment scores before and after oral nursing care showed that .93 of before oral care and .90 of after oral care. The correlation coefficient values of .68 (p<.001) and .71 (p<.001) before and after providing oral nursing care, respectively, indicated the presence of a statistically significant correlation between the tool and the criterion. Using the paired t-test, the differentiated validity of the tool was tested in patients who had developed pneumonia after entering the ICU. A statistically significant difference in scores was found between the time of entering the ICU and that of developing pneumonia (t=-8.73, p<.001), which provided evidence for the differentiated validity of the tool. Conclusions : Since the validity and reliability of the tool developed in this study were verified, this tool can be used to assess the oral health conditions of critically ill patients.