• Journal of Power Electronics
• /
• v.10 no.6
• /
• pp.762-768
• /
• 2010

This paper describes the development of a new islanding detection method for inverter-based distributed generation systems, which uses a signal cross-correlation scheme between the injected reactive current and the power frequency deviation. The proposed method injects 1% of the reactive current to the rated current which brings about a negligible degradation of the power quality. It discriminates the islanding state, when the calculated cross-correlation index is larger than 0.5. The operational feasibility was verified through computer simulations with PSCAD/EMTDC software and experimental research with a hardware prototype. The proposed method can detect the islanding state without degrading the power quality at the point of common connection. Further study is required to overcome the cancellation of the injected reactive current from multiple distributed generation units interconnected with the utility grid.

• 대한핵의학회:학술대회논문집
• /
• 2002.11a
• /
• pp.32.1-32.1
• /
• 2002

• 대한핵의학회:학술대회논문집
• /
• 2000.05a
• /
• pp.66.1-66.1
• /
• 2000

• Current Optics and Photonics
• /
• v.8 no.2
• /
• pp.151-155
• /
• 2024

Optical systems often suffer from optical aberrations caused by imperfect hardware, which places significant constraints on their utility and performance. To reduce these undesirable effects, a comprehensive understanding of the aberrations inherent to optical systems is needed. This article presents an effective method for aberration detection using Zernike polynomials. The process involves scanning the object plane to identify the optimal focus and subsequently fitting the acquired focus data to Zernike polynomials. This fitting procedure facilitates the analysis of various aberrations in the optical system.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.57 no.1
• /
• pp.65-72
• /
• 2008

This paper describes the development of a novel islanding detection method, which uses the signal cross-corelation scheme between the injected reactive current and the power frequency deviation. The existing method, which injects the reactive current of 2.5-5% to the rated current and detects the frequency deviation directly, brings about lowing the power quality due to the harmonic pollution. The proposed method eliminates the weak point of the existing method, because it injects the reactive current less than 1% to the rated current. The operational feasibility was verified through computer simulations with PSCAD/EMTDC software, and experimental works with a 10kVA hardware prototype. The proposed method can detect the islanding status effectively without lowing the power quality of interconnected distributed generation system.

• 대한핵의학회:학술대회논문집
• /
• 2002.05a
• /
• pp.9-13
• /
• 2002

Clinical application of positron emission tomography (PET) is rapidly increasing for the detection and staging of cancer at whole-body studios performed with 2-[fluorine-18]fluoro-2-deoxy-D-glucose (FDG). Although many cancers can be detected by FDG-PET, there has been limited clinical experience with FDG-PET for the defection of gynecological cancers including malignancies in uterus and ovary. FDG-PET can show foci of metastatic disease that may not be apparent at conventional anatomic imaging and can and in the characterization of indeterminate soft-tissue masses. Most gynecological cancers need to surgical management. FDG-PET can improve the selection of patients for surgical treatment and thereby reduce the morbidity and mortality associated with inappropriate surgery. FDG-PET is also useful for the early detection of recurrence and the monitoring of therapeutic effect. In this review, I discuss the clinical feasibility and limitations of this imaging modality in patients with gynecological cancers.

• Bulletin of the Korean Chemical Society
• /
• v.33 no.11
• /
• pp.3696-3700
• /
• 2012

The colorimetric and fluorescent cyanide recognition properties of 2-[(9-ethyl-9H-carbazol-3-yl)methylene]-propanedinitrile (1) in $CH_3CN-H_2O$ (2/1, v/v, HEPES 10 mM, pH = 7.0) solution were evaluated. The optical recognition process of probe 1 exhibited high sensitivity and selectivity to cyanide ion with the detection limit of $2.04{\times}10^{-6}$ M and barely interfered by other coexisting anions. The sensing mechanism of probe 1 is speculated to undergo a nucleophilic addition of cyanide to dicyanovinyl group present in compound 1. The colorimetric and fluorescent dual-modal response to cyanide makes probe 1 has a potential utility in cyanide detection.

• Proceedings of the KIEE Conference
• /
• 2003.07b
• /
• pp.1114-1116
• /
• 2003

Voltage sags are known as a serious problem causing mal-operation of equipment like computers, process controllers and adjustable-speed drives. In this paper, characterization of voltage sag and an overview of methods used in the mitigation of voltage sags are presented. Moreover a fast detection method for voltage disturbances is explored. The algorithm is based on the theory that allows a set of three-phase voltages be converted the d-q value. The utility input voltages are sensed and then converted to some quantities in the d-q transformation. And the difference between reference value and input value are showed that some disturbances happened in the system.

• Proceedings of the KIEE Conference
• /
• summer
• /
• pp.217-219
• /
• 2004

The installation of small sized dispersed generation(DG) units operating in parallel with the utility supply presents several technical problems for the protection and control of the system. One of the critical concerns is the occurrence of islanding. Hence, this paper propose the Digital Universal Relay(DUR) including anti-islanding function as DG interconnection interface. The existent islanding detection algorithms are examined. And the most effective and reliable method of those is modified for DUR application. The modified algorithm is evaluated through the modeling of the test system by PSCAD/EMTDC.

• Smart Media Journal
• /
• v.12 no.11
• /
• pp.125-133
• /
• 2023

Traditional attire has assumed a pivotal role within the contemporary fashion industry. The objective of this study is to construct a computer vision model tailored to the recognition of traditional costumes originating from five distinct countries, namely India, Korea, Japan, Tanzania, and Vietnam. Leveraging a dataset comprising 1,608 images, we proceeded to train the cutting-edge computer vision model YOLOv8. The model yielded an impressive overall mean average precision (MAP) of 96%. Notably, the Indian sari exhibited a remarkable MAP of 99%, the Tanzanian kitenge 98%, the Japanese kimono 92%, the Korean hanbok 89%, and the Vietnamese ao dai 83%. Furthermore, the model demonstrated a commendable overall box precision score of 94.7% and a recall rate of 84.3%. Within the realm of the fashion industry, this model possesses considerable utility for trend projection and the facilitation of personalized recommendation systems.