• KIEE International Transactions on Power Engineering
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• 제5A권3호
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• pp.244-251
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• 2005

Power transfer capability has been recently highlighted as a key issue in many utilities. It is determined by the thermal stability, dynamic stability and voltage stability limits of generation and transmission systems. In particular, voltage stability affects power transfer capability to a great extent in many power systems. This paper presents a tool for determining total transfer capability from a static voltage stability viewpoint using IPLAN, which is a high level language used with the PSS/E program. The tool was developed so as to analyze static voltage stability and to determine the total transfer capability between different areas from a static voltage stability viewpoint by tracing stationary behaviors of power systems. A unified power flow controller (UPFC) is applied for enhancing total transfer capability between different areas from the viewpoint of static voltage stability. Evaluation of the total transfer capability of a practical KEPCO power system is performed from the point of view of static voltage stability, and the effect of enhancing the total transfer capability by UPFC is analyzed.

• E2M - 전기 전자와 첨단 소재
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• 제7권3호
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• pp.231-235
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• 1994

The multi-dielectric layer $SiO_2$/$Si_3{N_4}$/$SiO_2$ (ONO) is used to improve charge retention and to scale down the memory device. The nitride layer of MNOS device is oxidize to form ONO system. During the oxidation of the nitride layer, the change of thickness of nitride layer and generation of interface state between nitride layer and top oxide layer occur. In this paper, effects of oxidation of the nitride layer is studied. The decreases of the nitride layer due to oxidation and trapping characteristics of interface state of multi layer dielectric film are investigated through the C-V measurement and F-N tunneling injection experiment using SONOS capacitor structure. Based on the experimental results, carrier trapping model for maximum flatband voltage shift of multi layer dielectric film is proposed and compared with experimental data. As a results of curve fitting, interface trap density between the top oxide and layer is determined as being $5{\times}10^11$~$2{\times}10^12$[$eV^1$$cm^2$].

• Journal of Power Electronics
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• 제5권4호
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• pp.289-304
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• 2005

This paper describes a simple control structure and power conditioning system for an indirect vector controlled stand-alone induction generator (IG) used to operate under variable speed. The required reactive power for the IG system is supplied by means of a capacitor bank and a voltage-source PWM converter. Using a capacitor bank to transfer the reactive power to the IG under the rated speed and no-load conditions starts the IG operation and reduces the PWM converter size. The vector control structure for the variable speed IG power conditioning system compensates for changes in the electrical three-phase and DC loads while considering the magnetizing curve of the IG. The vector control structure is developed to regulate the DC link voltage of the PWM converter and the IG output voltage. The experimental and simulated performance results of the IG power conditioning system at various speeds and loads are given and show that this proposed scheme can be used efficiently for a variable speed, wind energy conversion system.

• 한국산학기술학회논문지
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• 제7권6호
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• pp.1185-1193
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• 2006

차세대 인터넷과 같은 무한 네트워크에서 정보시스템은 다양한 공격과 사고의 발생으로 손상을 입고 그 사용자들은 막대한 비용의 손실을 입는다. 본 논문에서는 보안 시스템의 비용효과 측면에서 적정수준의 투자를 할 수 있는 효과적인 의사결정을 지원할 수 있도록 하는 정보시스템의 생존성 관리 모델을 제안하였다. 시뮬레이션을 통하여 서비스 가중치를 고려한 비용에 따라 생존성이 어떻게 변화하는지를 검사하였다. 방어 비용이 방어 수준에 따라 변화하기 때문에 비용/생존성과 서비스 가중치/생존성 그래프를 도출하여 관리자가 적정 수준의 보안을 유지하는 방어 비용을 결정할 있도록 하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 추계학술대회 논문집 학회본부A
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• pp.239-241
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• 1998

The probabilistic production simulation of power system generally has been used to formulate a reasonable power production plan or generation planning. It integrates the convolution process of a generating unit's random outage(FOR) with equivalent load duration curve(ELDC), and provides the reliability indices of power system. This paper presents the reliability characteristics of power system reflected on demand side management and proposes the modified ELDC representation technique due to the high-efficient end-use diffusion among the customers. Load reductions are simulated from the multi-state deconvolution process with the saved capacity of end-use. Case study shows the computed reliability from the power system production simulation incorporated with DSM planning scheme.

• 한국소음진동공학회논문집
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• 제18권1호
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• pp.26-34
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• 2008

This paper summarizes a design procedure of radiated noise from engine blocks of marine engines. This air-borne noise is one of the significant noise contributors including the aeroacoustic noise due to intake and exhaust and the re-radiation due to structure-borne noise. Excitation forces by engine operations are evaluated taking into account the power generation mechanism from the burning process to the subsequence motion of internal parts; piston, connecting rod, and crank shaft. The acoustic transfer vector method is incorporated to effectively simulate the radiated noise field under the various operation conditions. A contribution analysis for the various excitations to the radiated noise is conducted. It is found that the firing pressure is the main source of the radiated noise, and so the structure of the cylinder can be modified to significantly reduce the radiated noise from the engine block.

• 한국지진공학회논문집
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• 제26권2호
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• pp.95-103
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• 2022

In order to evaluate the earthquake safety of equipment in structures, it is essential to analyze the In-Structure Response Spectrum (ISRS). The ISRS has a peak value at the frequency corresponding to the structural vibration mode, but the frequency and amplitude at the peak can vary because of many uncertain parameters. There are several seismic design criteria for ISRS peak-broadening for fixed base structures. However, there are no suggested criteria for constructing the design ISRS of seismically isolated structures. The ISRS of isolated structures may change due to the major uncertainty parameter of the isolator, which is the shear stiffness of the isolator and the several uncertainty parameters caused by the nonlinear behavior of isolators. This study evaluated the effects on the ISRS due to the initial stiffness of the bi-linear curve of isolators and the variation of effective stiffness by the input ground motion intensity and intense motion duration. Analyzing a simplified structural model for isolated base structure confirmed that the ISRS at the frequency of structural mode was amplified and shifted. It was found that the uncertainty of the initial stiffness of isolators significantly affects the shape of ISRS. The variation caused by the intensity and duration of input ground motions was also evaluated. These results suggested several considerations for generating ISRS for seismically isolated structures.

• International Journal of Computer Science & Network Security
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• 제22권11호
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• pp.373-380
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• 2022

The field of land surveying is changing dramatically due to the way data is processed, analyzed and presented. Also, there is a growing demand for digital spatial information, coming primarily from the GIS (Geographical Information System) user community. Such a demand has created a strong development potential for a new land surveying software. An overview of the development and capabilities of a land surveying software platform based on the Windows system, SurveyingMap, is presented. Among its many features, SurveyingMap provides a lot of adaptability for networks adjustment, geodetic and plane coordinates transformation, contouring, sectioning, DTM (Digital Terrain Model) generation, and large scale mapping applications. The system output is compatible with well known computer aided drafting (CAD) /GIS packages to expand its scope of applications. SurveyingMap is also suitable for non-technical users due to the user-friendly graphic user interface. The system could be used in engineering, architecture, GIS, and academic teaching and research, among other fields. Two applications of SurveyingMap, extension of field control and large scale mapping, for the case study area are established. The results demonstrate that the system is adaptable and reasonably priced for use by college and university students.

• 한국정밀공학회지
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• 제10권3호
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• pp.161-167
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• 1993

This paper deals with a new method for the machining of a die cavity defined by sculptured surfaces. In machining die cavities or pockets, process planners have been faced with some troulbes. One of the troubles ius to rebove a great deal of material within a given boundary while avoiding cutter interference. Cutter interference is a ciritical problem in NC machining of a die cavity. Even though this cavity machining has been implemented in many CAM systems, most of them can handle limited shapes of cavities or pockets. In this paper, a procedure has been developed to machine die cavity or pocket of a sculptured surface. The offset surfaces of the part surfaces and boundary surfaces are determined to calculate the intersection curves. These intersection curves form a FACE on the part surface, and the interference free tool pathe is generated by eliminating the points outside the FACE when computing the cutter contact (CC) data. Additionally, the cutter location (CL) data obtained from the CC data convert to an NC data. The NC data generated through this algorithm are verified on the CINCINNATI milling machine. A propotype die cavity machining system has been implemented in FORTRAN language and FIGARO graphics library on IRIS workstation.

• Genomics & Informatics
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• 제21권2호
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• pp.24.1-24.7
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• 2023

Assays of clinical diagnosis and species identification using molecular markers are performed according to a quantitative method in consideration of sensitivity, cost, speed, convenience, and specificity. However, typical polymerase chain reaction (PCR) assay is difficult to quantify and have various limitations. In addition, to perform quantitative analysis with the quantitative real-time PCR (qRT-PCR) equipment, a standard curve or normalization using reference genes is essential. Within the last a decade, previous studies have reported that the digital PCR (dPCR) assay, a third-generation PCR, can be applied in various fields by overcoming the shortcomings of typical PCR and qRT-PCR assays. We selected Stilla Naica System (Stilla Technologies), Droplet Digital PCR Technology (Bio-Rad), and Lab on an Array Digital Real-Time PCR analyzer system (OPTOLANE) for comparative analysis among the various droplet digital PCR platforms currently in use commercially. Our previous study discovered a molecular marker that can distinguish Hanwoo species (Korean native cattle) using Hanwoo-specific genomic structural variation. Here, we report the pros and cons of the operation of each dPCR platform from various perspectives using this species identification marker. In conclusion, we hope that this study will help researchers to select suitable dPCR platforms according to their purpose and resources.