• 한국정보디스플레이학회:학술대회논문집
• /
• 한국정보디스플레이학회 2003년도 International Meeting on Information Display
• /
• pp.604-607
• /
• 2003

Three ring type LC compounds substituted with isothiocyanato group and fluoro atoms in phenyl ring were synthesized, and blended with KL-series LC mixtures for TV application of TN and IPS-mode. Clearing temperature of new LC mixtures are shown $10{\sim}35{\square}$ higher than commercial mixtures. And response time was also improved $10{\sim}20%$ faster than conventional LC mixtures.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2001년도 추계학술대회 논문집 전력기술부문
• /
• pp.73-76
• /
• 2001

This paper presents a new systematic contingency selection, screening and ranking method for on-line transient security assessment. Transient stability of a particular generator is influenced most by fault near it. Fault at the transmission lines adjacent to the generators are selected as contingency. Two screening methods are developed using the sensitivity of modal synchronizing torque coefficient and computing an approximate critical clearing time(CCT) without time simulation. The first method, which considers only synchronizing power, may mislead in some cases since it does not consider the acceleration power. The approximate CCT method, which consider both the acceleration and deceleration power, worked well. Finally the Single Machine Equivalent(SIME) method is implemented using IPLAN of PSS/E for detailed stability analysis.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2003년도 하계학술대회 논문집 A
• /
• pp.363-365
• /
• 2003

Recently, the concern of power qualiaty problem is increasing. Especially, Voltage quality problem have been increased important problem. Electronic device was affected by voltage sag. So, sensitive load that included many electronic Device was affected by voltage sag. also, it may have economic loss. In this paper, we argue the coordination scheme considering the loss of sensitive load. The coordination device of distribution system for instaneous fault is recloser and sectionalizer, But, the fault clearing time of recloser is more than 2 seconds. So, voltage sag generates long time that affected sensitive load. HS(high speed switchgear) has fast fault clearing time(0.015s) that not affected sensitive load. Therefore, the coordination applied HS is used. The proposed schemes are proved and evaluated by a case study using PSCAD/EMTDC simulation.

• 대한전기학회논문지:전력기술부문A
• /
• 제49권6호
• /
• pp.253-258
• /
• 2000

This paper presents an application of Kohonen neural networks to assess the dynamic security of power systems. The dynamic security assessment(DSA) is an important factor in power system operation, but conventional techniques have not achieved the desired speed and accuracy. The critical clearing time(CCT) is an attribute which provides significant information about the quality of the post-fault system behaviour. The function of Kohonen networks is a mapping of the pre-fault system conditions into the neurons based on the CCTs. The power flow on each line is used as the input data, and an activated output neuron has information of the CCT of each contingency. The trajectory of the activated neurons during load changes can be used in on-line DSA efficiently. The applicability of the proposed method is demonstrated using a 9-bus example.

• 전력전자학회논문지
• /
• 제24권5호
• /
• pp.349-355
• /
• 2019

A grid-connected inverter with critical loads should be able to supply a stable voltage to critical loads at mode change and during clearing time while detecting unintentional islanding. This study proposes a mode transfer method for a grid-connected inverter with critical loads. The proposed method, which integrates the grid-connected and islanded mode control loops into one control block, provides an autonomous and seamless mode transfer from the current control to the voltage control. Therefore, the proposed scheme can supply a stable voltage to critical loads at mode change and during clearing time. Experimental results are provided to validate the proposed method.

• Applied Microscopy
• /
• 제46권3호
• /
• pp.134-139
• /
• 2016

Detailed structural and molecular imaging of intact organs has incurred academic interest because the associated technique is expected to provide innovative information for biological investigation and pathological diagnosis. The conventional methods for volume imaging include reconstruction of images obtained from serially sectioned tissues. This approach requires intense manual work which involves inevitable uncertainty and much time to assemble the whole image of a target organ. Recently, effective tissue clearing techniques including CLARITY and ACT-PRESTO have been reported that enables visualization of molecularly labeled structures within intact organs in three dimensions. The central principle of the methods is transformation of intact tissue into an optically transpicuous and macromolecule permeable state without loss of intrinsic structural integrity. The rapidly evolving protocols enable morphological analysis and molecular labeling of normal and pathological characteristics in large assembled biological systems with single-cell resolution. The deep tissue volume imaging will provide fundamental information about mutual interaction among adjacent structures such as connectivity of neural circuits; meso-connectome and clinically significant structural alterations according to pathologic mechanisms or treatment procedures.

• 수산해양교육연구
• /
• 제21권4호
• /
• pp.586-591
• /
• 2009

The marine traffic accidents go on increasing owing to the increment of marine traffic capacity, and the solutions about these matters are vigorously considering by many researchers. When the watch officer navigates to the narrow channel, bend or an area obscured by an intervening obstruction and around the harbour limit he must follow the planned track. The watch officer can safely navigate along the course laid down only when he alters his course in advance before the new course distance earlier than the course alternation point. If we call this point to be changed in advance a turning bearing, the turning bearing is decided according to the direction and the range from the clearing objects. The turning bearing helps the watch officer to determine whether the ship is at wheel-over position or not. The author in this paper suggest how to make and use a curve graph which is decided according to the direction and the distance from the clearing objects. If the watch officer utilize this curve graph he can judge swiftly and precisely whether his ship is at the wheel - over position or not.

• 동아시아경상학회지
• /
• 제3권2호
• /
• pp.13-20
• /
• 2015

Online or e-banking has been adopted as key banking innovation in Uganda adopted by all financial institutions in the country. This research explored the state of e-banking and its efficacy in Uganda banking industry. A correlation analysis approach was adopted for this research. In Uganda, the banking sector has been liberalized with telecommunications allowed to effect e-banking and ecommerce transactions. The study concentrated on the periods of years 2011/2012 and 2012/2013. Findings from this research revealed that BOU uses UNISS for real time gross settlement (RTGS). Since its adoption a +1 coefficient correlation was realized. With the use of mobile money, also a +1 coefficient correlation was achieved for the period under consideration. As regards the use of e-cheques, there was a drop reflected by -2.8 percent which could have been attributed to perception of the users, though there was a +1 coefficient correlation when considering e-cheque transactions and the monetary value. The use of EFT in Uganda generated a +1 coefficient correction considering the number of users and the monetary value involved. Bank of Uganda should work hard and make or go live with electronic banking supervision software which would aid them with their supervisory roles.

• 대한전기학회논문지:전력기술부문A
• /
• 제54권6호
• /
• pp.306-314
• /
• 2005

In this paper, a new approach that is based on EEAC & only with network solutions for CS&S in the transient stability assessment is developed. The proposed CS&S algorithm in conjunction with EEAC to include the capability of performing on-line TSA without TDS is used to calculate the critical clearing time for stability index. In this algorithm, all generators are represented by classical models and all loads are represented by constant impedance load models. The accelerating & synchronizing power coefficient as an index is determined at its disturbance through solving network equation directly. As mentioned above, a new index for generator is generally used to determine the critical generators group. The generator rotor angle is fixed for non-critical generators group, but has equal angle increments for critical generators group. Finally, the critical clearing time is calculated from the power-angle relationship of equivalent OMIB system. The proposed CS&S algorithm currently being implemented is applied to the KEPCO system. The CS&S result was remarkably similar to TSAT program and SIME. Therefore, it was found to be suitable for a fast & highly efficient CS&S algorithm in TSA. The time of CS&S for the 139 contingencies using proposed CS&S algorithm takes less than 3 seconds on Pentium 4, 3GHz Desktop.

• 전기학회논문지
• /
• 제66권10호
• /
• pp.1466-1473
• /
• 2017

Generally, electrical torque in synchronous generator is balanced with the rotor mechanical torque under steady-state condition. Thus, the synchronous generator rotor rotates at constant speed. However, under fault condition, the electrical torque output is suddenly decreased and the sum of both torques does not remain constant. If the mechanical torque is not decreased at the same time, the generator rotor would accelerate. Therefore, this accelerating generator rotates at different speeds with respect to other generators in the power system. This phenomena is called as Out-of-Step (OOS). In this paper, we presented a certain two-step type quadrilateral OOS relay setting, which is applicable in actual field, and examined the validity of its setting value with OOS simulation conditions due to delayed fault clearing in transmission line. In order to conduct the study of OOS relay characteristics, we checked the impedance locus and generator output characteristics under the various delayed fault clearing conditions. Moreover, we proposed a countermeasure for avoiding the misoperation of OOS relay during the stable swing by modifying the setting values.