• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2007년도 추계학술대회논문집
• /
• pp.820-823
• /
• 2007

In the wavenumber domain, each point on a radiation sphere indicates a plane wave of the frequency corresponding to radius of the sphere and the position on the sphere shows propagating direction of the plane wave. This concept is extended from the research by Choi[1] where he focus acoustic potential energy at a point on a radiation sphere. Here we propose the method to focus the energy at a point on the radiation sphere, as a result, we can easily generate a plane wave which propagates to any direction that we want.

• 대한교통학회:학술대회논문집
• /
• 대한교통학회 1993년도 한-중 국제학술회의 발표논문
• /
• pp.99-105
• /
• 1993

This Article analyses the present situation of Shanghai Harbour and the Harbour's important role in the development of chinese economy. The article forecasts that the yearly tonnage turnover of the port will reach about 200 million tons in the year of 2000, possibly reach to 270--300 million tons by the end of 2020. it also forecasts that the container handling capacity of the port will be 2 million TEUS in 2000 and 6 million TEUS in 2020 respectively. In order to keep pace with the present situation of opening up and developing Pudong new area, this article suggests that the strategic target of the management and development of Shanghai Harbour should be : grasp the opportunity of opening up and developing Pudong, take the building of the deep-waterway port as the main task, which can accept the third or fourth generation international container ships, bring into full play the traditional advantages the Harbour has, unfold the businesses in other fields, participate in the marketing competition, speed up the development of the Harbour itself, make efferts to build Shanghai Harbour into a port-industry-trade-transportation integral modernized international deep-water key port.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2011년도 제42회 하계학술대회
• /
• pp.1396-1397
• /
• 2011

The world has problem of petrifaction energy exhaustion and environment pollution. We are looking up various solution plans regarding this problem. Solar power is one of the solution to solve the energy shortage problem. But solar power is affected by insolation. So we study tracking solar power system for the generation of electricity more. In this paper, we compared fixed solar power system with horizontal and vertical tracking solar power system. Two method were on he Maximum Power Point(MPP) using Solar pro.

• 전력전자학회논문지
• /
• 제6권3호
• /
• pp.291-298
• /
• 2001

본 논문은 차세대 FACTS(flexible AC Transmission Systems)기술인 UPFC(Unified Power Flow Controller)의 시뮬레이션을 다룬다. UPFC의 해석과 모델을 통하여 전력조류제어를 시뮬레이션 한다. 전력시스템의 과도상태 및 제어에 대한 시간영역 시뮬레이션 프로그램인 EMTDC(Electro-Magnetic Transients in DC systems)를 사용하여 전력조류제어인 유효전력 및 무효전력제어를 수행하고 더불어 모선입력전압의 크기를 제어한다. 시뮬레이션 결과를 통하여 UPFC의 제어성능을 검증한다.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제9권7호
• /
• pp.2454-2467
• /
• 2015

Increasing traffic and bandwidth requirements bring challenges to the next generation wireless networks (5G). As one of the main technology in 5G networks, Ultra-Dense Network (UDN) can be used to improve network coverage. In this paper, a radio over fiber based model is proposed to solve the load balancing problem in ultra-dense network. Stochastic differential game is introduced for the load balancing algorithm, and optimal load allocated to each access point (RAP) are formulated as Nash Equilibrium. It is proved that the optimal load can be achieved and the stochastic differential game based scheme is applicable and acceptable. Numerical results are given to prove the effectiveness of the optimal algorithm.

• 한국연소학회:학술대회논문집
• /
• 한국연소학회 1999년도 제19회 KOSCO SYMPOSIUM 논문집
• /
• pp.183-188
• /
• 1999

For two engine design parameters; compression ratio and intake swirl ratio, measurement of concentrations of hydrocarbon species has been made as a function of various air-fuel ratio in order to investigate the ozone formation of HC emissions from LPG fuel. Higher compression ratio gave lower SR values due to larger aIkan species and higher BSR values because of larger NMHC generation. Swirl ratio did not affect HC emissions and ozone formation. For ${\lambda}=1.1{\sim}1.2$, higher SR values resulted from the species of aIken which has higher MIRs were highly produced. Leaner mixture showed lower SR values due to the increase of the aIkan which has a lower MIR.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2006년도 추계학술대회 논문집 Vol.19
• /
• pp.110-111
• /
• 2006

In this paper, we investigated resistance characteristic of chalcogenide material for next generation ReRAM nonvolatile memory device with laser irradiation. A AES is used to test Ag doping ratio into a As-Ge-Se-S thin film. A sample resistance was observed in real time with He-Ne laser(632.8nm). As a result, resistance of thermal treated As-Ge-Se-S thin film was $500{\Omega}$ which is smaller than initial $1.3M{\Omega}$. A resistance of non-treated Ag/As-Ge-Se-S thin film was $200{\Omega}$ which is lower than $35M{\Omega}$.

• 반도체디스플레이기술학회지
• /
• 제7권3호
• /
• pp.51-54
• /
• 2008

In this study, we investigated variations in undoped ZnO thin film properties with working pressure, $O_2$/Ar ratio, and annealing ambient. Higher vacuum pressure during deposition was observed to bring about slower growth rate resulting in samples with better crystallinity as well as hole generation efficiency through formation of shallower oxygen interstitial. Given that $O_2$/Ar ratio is greater than unity, O provided from the ambient to ZnO during annealing was found to preferably situate at interstitial sites. When He was used for the second annealing, significant changes were not observed. On the other hand, O ambient caused increased density of oxygen interstitial, thereby making the film more intrinsic-like high resistivity ZnO.

• 한국과학교육학회지
• /
• 제23권4호
• /
• pp.430-441
• /
• 2003

The purpose of this study was to investigate the effects of students' prior knowledge on scientific reasoning in solving a pendulum task with a computer simulation. Subjects were 60 Korean students: 27 fifth-grade students from an elementary school and 33 seventh grade students from a middle school located in a city with 300,000 people. This study adapted a pendulum task presented with a computer simulation on which subjects would use a pattern of multivariable causal inferences. The subjects were interviewed individually in a three-phase structured interview by the researcher and three assistants while he/she was investigating the pendulum task. This study showed that most students across grades focused heavily on demonstrating the primacy of their prior knowledge or their current hypothesis. In addition, students' theories that are part of one's prior knowledge have a significant impact on formulating, testing, and revising hypotheses. Therefore, this study supported the notion that students' prior knowledge had a strong effect on students' experimental intent and hypothesis evaluation.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 1997년도 추계학술대회 논문집
• /
• pp.847-850
• /
• 1997

This paper presents a strategy to develop the environmentally conscious machining process. To establish the knowledge the analytical and experimental methodology for he prediction of aerosol concentration due to cutting fluid atomization mechanism in machining operation. The established analytical model which is based on atomization theory analyzes the cutting fluid motion and aerosol generation in machining process. The impinging and evaporation experiments were performance to know the particle size ad evaporation rate of cutting fluid. The predictive models can be used as a basis for environmental impact analysis on the shop floor. It can be also facilitate the optimization of cutting fluid usage in achieving a balanced consideration of productivity and environmental consciousness.