• 대한전기학회:학술대회논문집
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• 대한전기학회 1987년도 정기총회 및 창립40주년기념 학술대회 학회본부
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• pp.106-108
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• 1987

Until now, inflow has been handled an independent log-normal random variable in the problem of planning the long-term operation of a multi-reservoir hydrothermal electric power generation system. This paper introduces the detail study for making rule curve by applying weekly time interval for handling inflows. The hydro system model consists of a set of reservoirs and ponds. Thermal units are modeld by one equivalent thermal unit. Objective is minimizing the total cost that the summation of the fuel cost of equivalent thermal unit at each time interval. For optimization, stochastic dynamic programming(SDP) algorithm using successive approximations is used.

• 대한기계학회논문집
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• 제18권1호
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• pp.53-64
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• 1994

Rouge cutting process takes the major portion of machining operation using NC milling machine. Especially, most of the machining time is spent in this process when molds are machined. Therefore, an efficient algorithm for generating the tool path for rough cutting is suggested in this paper. The first step of the procedure is getting the volume to be machined by applying the Boolean operation on the finished model and the workpiece which have been modeling system. Basic principle of determining machining procedure is that a large tool should be used at the portion of the simple shape while a small tool should be used at the complex portion. This principle is realized by representing the volume to be machined by an octree, which is basically a set of hexahedrons, and matching the proper tools with the given octants. When the tools are matched with the octants, the tool path can be derived at the same time.

• Journal of Mechanical Science and Technology
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• 제20권10호
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• pp.1567-1575
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• 2006

In an automatic combination weigher, the line feeders distribute the product to several weighing hoppers. The ability to supply appropriate amount of product to the weighing hoppers for each combination operation is crucial for the overall performance. Determining the right duration of operating a line feeder to supply a given amount of product becomes very challenging in case of products which are irregular in volume or specific gravity such as granular secondary processed foods. In this research, several schemes were investigated to determine the best way for a line feeder to approximate the next operating time in order to supply a set amount of irregular goods to the corresponding weighing hopper. Results obtained show that a weighted least squares method (WLS) employing 10 data points is the most effective in determining the operating times of line feeders.

• Current Optics and Photonics
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• 제2권5호
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• pp.413-421
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• 2018

We propose a novel methodology based on the multiplication function to improve the signal-to-noise ratio (SNR) for vibration detection in a phi optical time-domain reflectometer system (phi-OTDR). The extreme-mean complementary empirical mode decomposition (ECEMD) is designed to break down the original signal into a set of inherent mode functions (IMFs). The multiplication function in terms of selected IMFs is used to determine a vibration's position. By this method, the SNR of a phi-OTDR system is enhanced by several orders of magnitude. Simulations and experiments applying the method to real data prove the validity of the proposed approach.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.1049-1058
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• 2011

This paper suggests blending time adjusting method of braking command characteristics management and Set value test for optimizing of braking deceleration to enhance the precise position stopping. This method minimizes pneumatic-braking degree deviation by characteristics management, and secures braking stability at braking. By Set value test method, braking blending characteristics are analyzed accurately. And by optimal timing tuning at braking blending, It enhanced the precise position stopping with stabilization of deceleration To demonstrate the usefulness of these suggestion, I modeled for Deajeon Line #1. And through comparison with case of related companies, the proposed method which this paper suggested is proved to be superior to others.

• 한국응용과학기술학회지
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• 제35권2호
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• pp.357-366
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• 2018

본 연구는 가정용 냉장고를 대상으로 냉동실과 냉장실의 설정온도를 각기 달리할 경우 냉동실과 냉장실 고내의 온도를 실측하여 냉장고 식품 보관 온도분포를 추정하고자 한다. 또한, 각 실의 설정온도를 중심으로 상하로 온도차가 얼마나 큰가를 파악하고, 설정온도로 회복하는데 소요되는 시간을 파악하고자 한다. 그리고 설정된 온도로 회복하기 위해 소비하는 전력량을 측정함으로서 가정용 냉장고의 최적 설정조건을 제시하고자 한다. 그 결과, 냉동실 온도가 $-18^{\circ}C$를 실현한 조건은 Case 3, Case 6, Case 8, Case 9로 냉동실 조건보다는 냉장실의 설정온도를 저온으로 할 경우에만 냉동실의 온도가 적정온도를 나타냈다. 이 조건에서 냉장실의 온도는 최저 $-1.1^{\circ}C$, Case 6은 $-1.5^{\circ}C$, Case 8은 $-1.1^{\circ}C$, Case 9는 $-0.8^{\circ}C$로 영하의 온도를 보였다. 또한 각 케이스의 운전시작 10시간 동안 누적소비전력량은 Case 4를 제외하고는 냉동실 및 냉장실의 설정온도가 낮을수록 컸으며, Case 4는 운전시작이 13:30분에 시작되었기에 09시경에 운전을 시작한 다른 조건보다는 낮시간의 환경온도가 높은 이유로 전력소비가 크다는 것을 확인하였다.

• Journal of Positioning, Navigation, and Timing
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• 제3권2호
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• pp.71-81
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• 2014

Time synchronization system using dual frequency bands is designed and the error sources are analyzed for alternative synchronized-pseudolite navigation system (S-PNS) which aims at military application. To resolve near/far problem, dual frequency band operation is proposed instead of pulsing transmission which degrades level of reception. In dual frequency operation H/W delay should be considered to eliminate errors caused by inter-frequency bias (IFB) difference between the receivers of the pseudolites and users. When time synchronization is performed across the sea, multipath error is occurred severely since the elevation angle between pseudolites is low so total reflection can be happened. To investigate the difference of multipath effects according to location, pseudolites are set up coastal area and land area and performances are compared. The error source related with tropospheric delay is becoming dominant source as the coverage of the PNS is broadening. The tropospheric delay is measured by master pseudolite receiver directly using own pseudorange and slave pseudorange. Flight test is performed near coastal area using S-PNS equipped with developed time synchronization system and test results are also presented.

• KIEE International Transactions on Power Engineering
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• 제2A권3호
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• pp.83-88
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• 2002

An over current relay(OCR), one of the most frequently used protective devices, has time-current characteristics (TCC) to control its trip time according to the current level. It is because an appropriate operating time interval is necessary for coordination with other protective devices. A set of TCC curves of an OCR is, in general, given by the supplier from which a curve is selected by the operator. Therefore, in many cases, it is impossible to consider the operation condition of the given power system exactly. A novel concept of an OCR is suggested in this paper. The proposed OCR has an internal correction module so that it may produce the most adequate TCC curve according to the given protective information for coordination with other devices. With the generated TCC curve, a variety of operation and coordination conditions can be taken into consideration in an effective manner. The suggested OCR is applied to a simple test power system to show very promising results from a coordination point of view.

• 한국멀티미디어학회논문지
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• 제11권9호
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• pp.1267-1276
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• 2008

허혈성 심장 질환자가 급성 심근경색으로 병원에 도착하여 경피적 관상동맥 중재술을 받는데 까지 걸리는 시간(door-to-balloon time)은 환자의 사망률에 매우 큰 영향을 미친다. 본 연구에서는 기존에 병원에서 사용하고 있는 응급서비스시스템을 개선하고자 3단계의 시간 중 보호자에게 연락과 보호자가 병원에 도착할 때까지의 시간(door-to-data time), 이후 시술동의서에 서명할 때까지의 시간(data-to-decision time)을 줄이고자 하였다. 새로운 e-응급서비스시스템은 급성심근경색을 가진 응급시술환자에 대한 병원 내 응급서비스시스템 내의 데이터베이스를 구축하였고 허혈성 심장 질환자로서 부산대학교병원에 주기적으로 내원하는 환자에게 건강카드(health card)를 발급하였다. 아울러 사전시술동의서는 공인된 전자화 문서로 보관하도록 하였다. 새로운 전자화 시스템은 복잡한 진료 및 시술 절차를 획기적으로 감소시킬 수 있다. 그러므로 응급환자에 대한 인명구조를 용이하게 하고 사망률을 감소시키는 효과를 기대할 수 있다. 뿐만 아니라, 기존 시스템의 복잡한 절차로 인한 의료진과 환자의 고충을 동시에 해결하는 효과도 기대할 수 있다.

• 정보통신설비학회논문지
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• 제9권4호
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• pp.124-130
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• 2010

This paper considers a power saving technique of set-top box (STB) that turns the signal into content which is then displayed on the television (TV) screen. A traditional power saving scheme, Auto Power Down (APD), was devised to reduce the power consumption of STB. APD checks whether the user is watching TV over a period of time and enforces STB into stand-by mode when the check result reveals the user is not watching TV. This paper proposes an enhanced power saving scheme that transits STB operation mode to 'stand-by' immediately when STB recognizes the change of TV's external input signal. The proposed scheme does not require the monitoring time to check the users' watching TV, and transits to standby mode faster than the conventional APD, which results in better performance in power saving. The simulation result shows that the proposed scheme achieves 2 to 11% improvement in power consumption compared with the conventional APD.