• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 1996년도 춘계학술대회 논문집
• /
• pp.808-812
• /
• 1996

Reduction gear with internal gear pair need functions such as compact size, high reduction ratios, high transmission efficiency, and low noise. Feasible design region of the internal gear pair with a small tooth difference is extremely limited because the internal gear pair is subject to interference in meshing and cutting. Single-objective optimal design can not simulataneously satisfy the manifold requirements of the internal gear pair and can not determine the economical specification of a pinion cutter. Multi-objective optimal design which include the specification of the pinion cutter in design variables is developed, considering the manufacturing error of an internalgear pair and the re-sharpening of the pinion cutter.

• 한국공작기계학회:학술대회논문집
• /
• 한국공작기계학회 1996년도 추계학술대회 논문
• /
• pp.167-172
• /
• 1996

A Dual Mass Flywheel system is a evolution to the reduction of torsional vibration and impact noise occuring in powertrain when a vehicle is eit-her moving or idling. The name already explains what it is : The mass of the conventional single mass flywheel is divided. One section continues to belong to the mass moment of inertia of the engine-side. The ot-her section increass the mass moment of inertia of the transmission-side. The two masses are connected via a spring /damping system. This reduces the speed at which the dreaded resonance occurs to below idle speed. Since 1984 Dual Mass Flywheel has been de-veloped again and again. But the prosidures of de-velopment of D.M.F system didn't have had differe-nce from conventional clutch system's trial and err-or This paper presents the method for systematical design of D.M.F system with demensionless design variables of D.M.F system mass ratio between two flywheels λ. natual frequency rate of two flywheel s, ${\gamma}$and viscosity coefficient ζ. And experimental re-sults are used to prove these theoretical results.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1997년도 추계학술대회 논문집 학회본부
• /
• pp.209-211
• /
• 1997

This paper describes the TNA(Transient Network Analyzer) modeling/operating methods and the analysis results of expected overvoltages of 765 kV system in 2005 by the TNA. The power system is expressed as the equivalent inductance of power system, power source, transmission line, switch, and etc. in the TNA. We have examined the overvoltages in the ground fault case, the fault clearing case and the closing/re-closing case. The maximum line-to-line overvoltage is 1.87 p.u., which occurs between SS and SA at the fault clearing case.

• Journal of Electrical Engineering and Technology
• /
• 제10권3호
• /
• pp.1377-1382
• /
• 2015

Power system restoration following a massive blackout starts with re-energizing Primary Restorative Transmission (PRT) systems at first. As power systems have been gradually enlarged and become more complex, periodical evaluation and reassignment of PRTs are needed. So far it has been decided by try and error approach by corresponding human experts to analyze and evaluate them. This paper presents an intelligent system that finds optimal primary restoration paths using analytic and heuristic knowledge from PSS/E data, and suggests an optimal PRTs depending on the condition of Ferranti effect or a reactive power capability margin of black-start generator. This system was tested in Korea Electric Power system, and showed a promising result.

• 한국정보처리학회:학술대회논문집
• /
• 한국정보처리학회 2016년도 추계학술발표대회
• /
• pp.258-261
• /
• 2016

환자가 가정에서 네트워크를 통해 자신의 건강정보를 원격지에 위치한 의사에게 전송하여 이에 대한 진단을 받는 원격건강정보 모니터링 시스템에서 환자의 개인건강정보의 보호는 매우 중요한 과제이다. 본 논문에서는 신원기반 프록시 재암호화 기법을 사용하여 환자가 다수의 의사를 선택하여 각 의사들에게 개인건강정보를 전송하여 진단을 받는 환경을 가정하여 환자가 가지는 연산부담을 줄이기 위해 환자의 비밀키로 생성한 암호문을 프록시가 재암호화하여 의사가 가진 비밀키로 복호화 할 수 있도록 하는 기법을 제안한다.

• Journal of Information Processing Systems
• /
• 제14권5호
• /
• pp.1272-1285
• /
• 2018

The paper presents a novel embedded multifunctional media sever (EMMS) for mobile devices to receive various media programs. Being different from other contemporary system research, the paper mainly studies how to design a reception solution for terrestrial digital television (DTV) on mobile devices and how to enable mobile devices can receive DTV program, enjoy video-on-demand (VOD), achieve video surveillance and relay Internet video program via local Wi-Fi simultaneously. In the system design, we integrate broadcasting-terrestrial DTV tuner, streaming media re-transmission system, VOD disk, video camera and access interface to the Internet into EMMS, which can either receive terrestrial DTV radio signals and demodulate out digital transport stream (TS), or can read streaming media bit-stream from VOD disk, surveillance camera or access interface to the Internet. The experimental results show the proposed system is stable and quality-efficient. Comparing with the other systems, the proposed system has the least packet loss rate and response time.

• 한국시뮬레이션학회논문지
• /
• 제13권4호
• /
• pp.55-69
• /
• 2004

In MANET(Mobile Ad-hoc Network), unlike in wired networks, a path configuration should be in advance of data transmission along a routing path. Frequent movement of mobile nodes, however, makes it difficult to maintain the configured path and requires re-configuration of the path very often. It may also leads to serious problems such as deterioration of QoS in mobile ad-hoc networks. In this paper, we proposed a Reactive Routing Keyword (RRK) routing procedure to solve those problems. Firstly, we noticed it is possible in RRK routing to assign multiple routing paths to the destination node. We applied this feature into active networks and SNMP information based routing by storing unique keywords in cache of mobile nodes corresponding to present and candidate routings in a path configuration procedure. It was shown that the deterioration of QoS which may observed in Dynamic Source Routing(DSR) protocol was greatly mitigated by using the proposed routing technique.

• ETRI Journal
• /
• 제24권2호
• /
• pp.153-160
• /
• 2002

High Altitude Platforms-craft maintaining stations in the stratosphere at altitudes of around 20 km-have been proposed as a means of supporting wireless telecommunications. They could exploit the best aspects of both terrestrial and satellite systems and support efficient frequency re-use plans. For solar powered platforms the power available for the downlink amplifiers may be minimal, particularly at night and/or higher latitudes. This paper discusses a novel type of link based on a modulated retro-directive transponder carried by the HAP. Relying chiefly on the ground station infrastructure, this would substantially reduce power consumption on the platform. We investigate the efficiency of the transponder aperture as a function of its area by developing general models for losses in the transmission lines which interconnect antenna pairs in the retro-directive array.

• 제어로봇시스템학회논문지
• /
• 제12권8호
• /
• pp.789-797
• /
• 2006

A new method for the GPS repeater based indoor positioning is proposed and its feasibility is verified by experiments in previous paper. But the problems how can identify switching GPS repeater's ID and when switching will be occurred are remained. To solve the problem faced with, we propose the time synchronized switching GPS repeater and the methods of the detection of switching time and the estimation of TDOA. First, switching GPS repeater retransmits the signals synchronized on GPS time, sequentially. Always, first switching time is synchronized with 1 PPS. Second, we formulate the detection of switching time and the estimation of TDOA and propose the various methods. No method is existed absolutely superior to others in any conditions but the method is existed superior to others in specific condition. Finally, feasibility of indoor positioning using time-synchronized switching GPS repeater is evaluated through experiments in anechoic chamber and general environment with multipath.

• ETRI Journal
• /
• 제30권4호
• /
• pp.535-545
• /
• 2008

This paper introduces a systematic top-down and bottom-up design methodology to assist the designer in the implementation of continuous-time (CT) cascade sigma-delta (${\Sigma}{\Delta}$) modulators. The salient features of this methodology are (a) flexible behavioral modeling for optimum accuracy-efficiency trade-offs at different stages of the top-down synthesis process, (b) direct synthesis in the continuous-time domain for minimum circuit complexity and sensitivity, (c) mixed knowledge-based and optimization-based architectural exploration and specification transmission for enhanced circuit performance, and (d) use of Pareto-optimal fronts of building blocks to reduce re-design iterations. The applicability of this methodology will be illustrated via the design of a 12-bit 20 MHz CT ${\Sigma}{\Delta}$ modulator in a 1.2 V 130 nm CMOS technology.