• 전기학회논문지
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• 제59권3호
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• pp.575-580
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• 2010

This paper is to design an optimum power conversion device for the system required for development of a low cost 3-phase power inverter. For this purpose, in order to meet with endurance required by the industry, failure mode is standardized to guarantee lifetime of a power semiconductor by monitoring real time power loss and to facilitate failure mode analysis. As normality of heat loss of a power semiconductor is identified remaining in a certain range by comparing heat rise slope between that is calculated by using average current or average loss and that is measured at a heat sink, its feasibility is confirmed by experiment.

• 조명전기설비학회논문지
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• 제25권1호
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• pp.70-77
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• 2011

Sewage treatment plants, consuming 1,756[GWh] which is 0.53[%] of national wide electricity consumption, is one of the electricity consuming facilites. At the research of electricity consumption and power quality analysis on sewage treatment plants, average utilization of transformer was less than 40[%] because peak load was very lower than its capacity due to excess capacity. So reduction of power loss can be achieved by transformer design optimization. The achievement in this research, is to meet reduction of power loss through optimizing the capacity and to improve as high efficiency-low loss transformer while the transformer is operating.

• 인터넷정보학회논문지
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• 제6권4호
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• pp.115-124
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• 2005

본 논문에서는 이동 멀티캐스트(MoM) 프로토콜에서 DMSP 핸드오프로 인하여 발생하는 패킷 손실 문제를 여러 DMSP 선택 방식에 대하여 모의실험을 통하여 조사하였다. 모의실험 결과로 한 개의 DMSP를 갖는 MoM프로토콜에서는 상당한 패킷손실이 발생하는데 이를 최소화하기 위하여 두 가지 향상된 멀티캐스트 방안을 제안한다. 제안된 첫 번째 방안은 백업 DMSP를 사용하여 망 내부에서의 트래픽은 증가하지만 패킷 손실율을 크게 줄일 수 있는 방안이다. 제안된 두 번째 방안은 확장된 DMSP 기능을 추가하여 망 내부에서의 트래픽도 낮게 유지하면서 동시에 패킷 손실율을 최소화하는 방안이다.

• Progress in Superconductivity
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• 제6권1호
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• pp.32-36
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• 2004

To investigate the influence of strip width and inter-strip separation on the ac loss, arrays of parallel strips with different widths and separations were prepared. Studies on the hysteresis-loss characteristics of multifilamentary YBCO films were performed. The local magnetic field due to magnetization currents is measured by a scanning Hall probe microscope. Based on these results a conceptual design for a low loss YBCO coated conductor is suggested.

• 한국통신학회논문지
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• 제28권4A호
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• pp.238-246
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• 2003

본 논문에서는 현재까지 셀룰라 서비스와 PCS서비스를 위해 얻어진 전파전파 측정에 대한 전체적인 요약을 하였다. 이렇게 얻어진 협대역신호 기반의 측정치와 광대역 신호에 의한 이동통신 채널 측정에 대해 고찰을 한 후 미국 캘리포니아의 오클랜드시에서 얻어진 측정치를 이용하여 불규칙한 높이의 건물로 이뤄진 도시 환경에서 쓰일 수 있는 마이크로셀용 신호 감쇄 예측 공식을 만들고, 이를 균일한 높이의 건물로 이뤄진 환경에서 얻은 신호 감쇄 예측 공식과 비교하였다.

• 한국컴퓨터정보학회논문지
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• 제22권8호
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• pp.9-14
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• 2017

In this paper, we propose the smart belt system for preventing loss of items using Beacon. The proposed system monitors the distances of the registered items via the belt that is always worn. The belt determines the loss of the items by measuring the relative distance via RSSI (Received Signal Strength Indicator) value of the signals received from the BLE (Bluetoothl Low Energy) sensor, which is attached on the items such as bags and wallets. If the registered item is determined to be lost, the belt rings to remind the user of the loss. The missing status could be known to users through the smartphone application connected to the belt. The smartphone application communicates with the belt using Beacon, and provides users with a quick and easy way to check the status of their items.

• 비파괴검사학회지
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• 제31권6호
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• pp.616-625
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• 2011

Ensuring the designed prestress force is very important for the safety of prestressed concrete bridge. The loss of prestress force in tendon could significantly reduce load carrying capacity of the structure. In this study, an automated prestress-loss monitoring system for prestressed concrete girder using PZT-interface and wireless impedance sensor node is presented. The following approaches are carried out to achieve the objective. Firstly, wireless impedance sensor nodes are designed for automated impedance-based monitoring technique. The sensor node is mounted on the high-performance Imote2 sensor platform to fulfill high operating speed, low power requirement and large storage memory. Secondly, a smart PZT-interface designed for monitoring prestress force is described. A linear regression model is established to predict prestress-loss. Finally, a system of the PZT-interface interacted with the wireless sensor node is evaluated from a lab-scale tendon-anchorage connection of a prestressed concrete girder.

• 한국세라믹학회지
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• 제34권6호
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• pp.561-568
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• 1997

The effects of sintering temperature and oxygen partial pressure on the electromagnetic properties of Mn-Zn ferrites were investigated. The grain increased with increasing temperature. The power loss at 100 kHz was decreased, while the power loss at 500 kHz was increased as the grain size increased with sintering temperature. Sintering with low oxygen partial pressure at 115$0^{\circ}C$ resulted in high density and initial permeability, and decreased the power loss at 100 kHz and 500 kHz. The oxygen partial pressure lower than 10-2 atm. during heating, significantly suppressed the hysteresis loss. However, the oxygen activity did not affect the grain size of sintered cores.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제50권1호
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• pp.10-14
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• 2001

The superconducting transmission cable is one of interesting part in power application using high temperature superconducting wire. One important parameter in HTS cable design is transport current sharing because it is related with current transmission capacity and loss. In this paper, we calculate self inductances of each layer and mutual inductances between two layers from magnetic field energy, and current sharing of each layer for 4-layer cable using the electric circuit model which contain inductance and resistance (by joint and AC loss). Also, transport current losses which are calculated by monoblock model and Norris equation are compared. As a results, outer layer has always larger transport current than inner layer, and current capacity of each layer is largely influenced by resistance per unit cable length. As a conclusion, for high current uniformity and low AC loss, we have to decrease inductances themselves or those differences.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 B
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• pp.1049-1050
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• 2006

This paper is proposed to a novel DC-DC converter operated high efficiency for loss-less snubber capacitor. The general converters of high efficiency is made that the power loss of the used switching devices is minimized. To achieve the soft switching operation of the used control switches, the proposed converter is constructed by using a loss-less snubber capacitor. The proposed converter achieves the soft-switching for all switching devices without increasing their voltage and current stresses. The result is that the switching loss is very low and the efficiency of converter is high. The soft switching operation of the proposed converter is verified by digital simulation and experimental results.